Materials Science: Revolutionizing Batteries, Biomaterials and Advanced Polymers

Credit: iStock SHAPE-SHIFTING BIOMATERIALS FOR TISSUE REGENERATION SUPERCHARGING BATTERIES WITH IMPROVED MATERIAL DESIGN EXPLORING THE TECHNIQUES USED IN POLYMER ANALYSIS MATERIALS SCIENCE Revolutionizing Batteries, Biomaterials and Advanced Polymers CONTENTS 04 Exploring the World of Medical Biomaterials 07 Could Hydrogel Help Mend a Broken Heart? 09 Shape-Shifting Biomaterials for Tissue Regeneration 12 Analytical Techniques in the Battery Lifecycle 16 Common Techniques in Battery Material Analysis 17 Innovative Hydrogel Dressing To Accelerate Diabetic Wound Healing 20 Supercharging Batteries With Improved Material Design 22 Exploring the Techniques Used in Polymer Analysis MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 3 TECHNOLOGYNETWORKS.COM FOREWORD The field of material science is experiencing a remarkable transformation. From enhancing battery storage for renewable energy to developing biomaterials that interact seamlessly with human tissue, the possibilities seem limitless. This eBook explores key developments in materials science, shedding light on the innovative approaches that are shaping the future. Whether it’s the creation of stronger, more flexible polymers for medical use or breakthroughs in battery technology that promise cleaner energy solutions, the chapters ahead delve into the materials revolutionizing industries and improving lives. By weaving together insights from cutting-edge research and practical applications, this eBook offers readers a glimpse into the future of material science and its impact on technology and sustainability. The Technology Networks editorial team The rapid development of new biomaterials is changing the healthcare landscape. Biomaterials are materials designed to safely interact with biological systems to support, improve or replace natural processes. In 2022, the biomaterials market reached $155 billion and is predicted to grow by 15.5% over the next two decades.1 This investment is helping to unlock new treatment strategies, from advanced prostheses and implantable devices to cutting-edge drug delivery systems and tissue regeneration techniques. This listicle will explore the different types of biomaterials, highlight their diverse properties and discuss how they are being applied to accelerate advanced medical treatments. What are biomaterials? A comprehensive definition of a “biomaterial” is difficult to achieve; it has evolved over the years as the field has grown and developed. The most widely accepted description defines a biomaterial as a substance that has been intentionally designed to interact with biological systems, whether for the treatment, augmentation or replacement of a biological function. Significant research into biomaterials began in the late 1960s, with an initial interest in materials that were “inert”. Early applications focused on dental and surgical treatments, such as the use of titanium for orthopedic and dental implants.2 Since then, the number of available biomaterials has grown rapidly. Broadly, biomaterials can be grouped based on their primary material and the properties of that material. Types of biomaterials Metals Metals have played a role in medical implants for over a century, ever since metal plates were first used to fix bone fractures.3 MATERIAL SCIENCE Exploring the World of Medical Biomaterials Steven Gibney, PhD 4 Credit: iStock TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 5 However, early attempts at metal implants often suffered from corrosion issues. This is exemplified by Sherman vanadium steel which, despite its relatively high hardness, displayed poor corrosion resistance when implanted in a biological environment.4 Since then, more advanced metallic materials have been developed, including titanium alloys, stainless steel alloys and cobalt–chromium alloys.5 These metals are biocompatible and corrosion resistant, ensuring any implants made from them will maintain structural integrity. This also makes them safer than their historical counterparts. The properties of metallic biomaterials make them ideal for load-bearing applications that require sufficient strength to withstand constant daily activity. This includes good physical strength, durability and a high elastic modulus. One of the most common applications for metallic biomaterials is artificial joints and orthopedic implants, such as hip and knee replacements.6 On a smaller scale, zinc- and magnesiumbased alloys have been used to create cardiovascular stents, small mesh tubes that are used to expand narrowed or blocked coronary arteries.7 Ceramics Ceramic biomaterials share many properties and applications with their metallic counterparts. This includes their high physical and mechanical strength, resistance to wear and generally good biocompatibility. However, bioceramics have several advantages when compared directly to metallic biomaterials, such as a higher melting temperature, extreme corrosion resistance, improved mechanical properties and a biocompatibility exceeding that of most metals.8 This combination of properties makes ceramic biomaterials well-suited for applications where durability and biocompatibility are crucial. Ceramics such as zirconia, also known as zirconium dioxide, are used extensively in dental implants, where their biocompatibility and resemblance to natural tooth structure make them successful replacements in dental procedures.9 Ceramics such as alumina and hydroxyapatite are employed in bone grafts and joint replacements and can also be used as coatings to reduce the wear and inflammatory response to larger implants.8 Polymers (natural and synthetic) Polymers represent one of the widest categories of biomaterials, encompassing both synthetic polymers, like polyethylene, and natural polymers, such as collagen. Polymeric biomaterials are valued for their versatility; the wide range of unique polymers available makes it possible to tailor their design to meet specific medical needs. Natural polymers have already been the subject of much study. For example, collagen – a natural protein present in skin and other connective tissues – has been widely used in the preparation of biological scaffolds and implants for tissue engineering and regeneration.8 Other natural polymers like fibrin, keratin, fibronectin and laminin have also been investigated as biomaterials for tissue engineering applications.10 Fibrin derived from blood can function as a natural sealant during surgeries, while decellularized matrices created by removing cellular components from tissues provide a framework for tissue regeneration.10,11 The integration of naturally occurring polymers as a biomaterial ensures a seamless interaction with the body, making them extremely biocompatible solutions for tissue repair, regeneration and transplantation. Synthetic polymers, such as nylon, polyethylene and polyester, can be heavily modified and engineered to suit a specific need. Synthetic polymers are also useful substitutes for patients with an allergy to certain natural polymers, as they are less immunogenic. The ability to modify synthetic polymers by adjusting their monomer structure makes it easy to adjust material properties to suit a specific need. This can include tweaking the physical or chemical properties to improve biodegradability, making them more suitable for tissue engineering applications.12 This also makes synthetic polymers valuable for the development of implantable devices, where polymers such as polylacticco-glycolic acid (PLGA), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) can be manufactured into 3D scaffolds using different methods, such as 3D printing, freeze-drying or electrospinning.13,14 TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 6 There is similar interest in the use of synthetic polymers for drug delivery applications, where polymers can be used to improve the efficacy of therapeutics, extend the release of compounds or target specific biological systems.15 Composite/hybrid materials Composite or hybrid biomaterials are created by combining different materials to create a product that possesses the optimal properties of their individual components. This ability to create custom combinations of biomaterials unlocks new avenues of interest when designing medical solutions. For instance, a combination of natural collagen and synthetic PLGA can be used to manufacture structures that display unique combinations of physicochemical properties including elasticity and strength, making them suitable for bone and soft tissue regeneration.16 Likewise, ceramic and metal biomaterials can be directly combined or mixed with polymers to create more effective joint replacements or for tissue reconstruction.16,17 The sheer number of possible combinations of biomaterials means that hybrid design is expected to become increasingly popular, allowing researchers to tune the properties of their material to their desired solution. The future of biomaterials Biomaterials have already brought about transformative innovations that have reshaped patient care and disease management. Ongoing research is laying the foundation for groundbreaking developments in biomaterials, from new types of materials to novel applications. This progress will also benefit from wider advances in technology, such as the use of 3D printing for personalized implants and the development of smart biomaterials that dynamically respond to physiological cues. Likewise, the integration of data-driven design and artificial intelligence (AI) solutions will accelerate the design and optimization of key biomaterials. The convergence of multidisciplinary approaches and emerging technologies will no doubt unlock new frontiers in the development and application of biomaterials, contributing to more personalized and effective medical treatments. • REFERENCES 1. Grand View Research. Biomaterials Market Size, Share & Trends Analysis Report By Product (Natural, Metallic, Polymer), By Application (Cardiovascular, Orthopedics, Plastic Surgery), By Region, And Segment Forecasts, 2023 – 2030. https://www. grandviewresearch.com/industry-analysis/biomaterialsindustry. Accessed January 2, 2024. 2. Vallet-Regí, M. Evolution of biomaterials. Front Mater. 2022;9:864016. doi:10.3389/fmats.2022.864016 3. Uhthoff HK, Poitras P, Backman DS. Internal plate fixation of fractures: short history and recent developments. J Orthop Sci. 2006;11(2):118-126. doi:10.1007/s00776-005-0984-7 4. Szczęsny G, Kopec M, Politis DJ, Kowalewski ZL, Łazarski A, Szolc T. A review on biomaterials for orthopaedic surgery and traumatology: From past to present. Materials (Basel). 2022;15(10):3622. doi:10.3390/ma15103622 5. Prasad K, Bazaka O, Chua M, et al. Metallic biomaterials: current challenges and opportunities. Materials. 2017;10(8):884. doi:10.3390/ma10080884 6. Davis R, Singh A, Jackson MJ, et al. A comprehensive review on metallic implant biomaterials and their subtractive manufacturing. Int J Adv Manuf Technol. 2022;120(3-4):1473- 1530. doi:10.1007/s00170-022-08770-8 7. Fu J, Su Y, Qin YX, Zheng Y, Wang Y, Zhu D. Evolution of metallic cardiovascular stent materials: A comparative study among stainless steel, magnesium and zinc. Biomaterials. 2020;230:119641. doi:10.1016/j.biomaterials.2019.119641 8. Vaiani L, Boccaccio A, Uva AE, et al. Ceramic materials for biomedical applications: an overview on properties and fabrication processes. J Funct Biomater. 2023;14(3):146. doi:10.3390/jfb14030146 9. Mussano F, Genova T, Munaron L, Faga MG, Carossa S. Ceramic biomaterials for dental implants: current use and future perspectives. In: Dental Implantology and Biomaterial. IntechOpen; 2016. doi:10.5772/62701 10. Kalirajan C, Dukle A, Nathanael AJ, Oh TH, Manivasagam G. A critical review on polymeric biomaterials for biomedical applications. Polymers. 2021;13(17):3015. doi:10.3390/ polym13173015 11. Canonico S. The use of human fibrin glue in the surgical operations. Acta Biomed. 2003;74 Suppl 2:21-25. PMID:15055028 12. Maitz, MF. Applications of synthetic polymers in clinical medicine. Biosurface and Biotribology. 2015;1(3):161-176. doi:10.1016/j.bsbt.2015.08.002 13. Xia D, Chen J, Zhang Z, Dong M. Emerging polymeric biomaterials and manufacturing techniques in regenerative medicine. Aggregate. 2022;3(5):e176. doi:10.1002/agt2.176 14. Teo AJT, Mishra A, Park I, Kim YJ, Park WT, Yoon YJ. Polymeric biomaterials for medical implants and devices. ACS Biomater Sci Eng. 2016;2(4):454-472. doi:10.1021/ acsbiomaterials.5b00429 15. Fenton OS, Olafson KN, Pillai PS, Mitchell MJ, Langer R. Advances in biomaterials for drug delivery. Adv Mater. doi:10.1002/adma.201705328 16. Lei B, Guo B, Rambhia KJ, Ma PX. Hybrid polymer biomaterials for bone tissue regeneration. Front Med. 2019;13(2):189-201. doi:10.1007/s11684-018-0664-6 17. Affatato S, Spinelli M, Squarzoni S, Traina F, Toni A. Mixing and matching in ceramic-on-metal hip arthroplasty: an invitro hip simulator study. J Biomech. 2009;42(15):2439-2446. doi:10.1016/j.jbiomech.2009.07.031 7 MATERIALS SCIENCECredit: iStock How do you un-break a heart? Well, if that broken heart belongs to Toni Braxton, you just need to say you’ll love her again. But for anybody else, a different approach is in order. Chemical engineers are one step closer to being able to repair damaged hearts, with researchers from the University of Waterloo, the University of Toronto and Duke University creating a new synthetic material that can replicate the biomechanical properties of human tissues. The material has been described in a new paper published in the journal PNAS. Biomimetic hydrogels Great strides have been made in the field of tissue engineering in recent years. However, current advancement has been somewhat limited by a lack of materials that can properly mimic the native nanofibrillar structures found in biological tissue. Another unique aspect of these fibrous networks formed by collagen or fibrin inside biological tissues is that they undergo a very strong stiffening response to shear and elongational strain forces, but soften when compressed. This mechanical behavior is rarely found in the synthetic materials developed for tissue engineering. Now, a team of researchers has designed a new hydrogel that can overcome these hurdles. Their hydrogel is made from gelatin and wood pulpderived cellulose nanocrystals. Scanning electron microscope images showed that the material has a fibrous nanostructure with large pores that can deal Could Hydrogel Help Mend a Broken Heart? Alex Beadle Credit: iStock TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 8 with nutrient and waste transport, similar to biological tissue. What is a hydrogel? A hydrogel is a three-dimensional network of crosslinked, hydrophilic polymers that can swell to hold large volumes of water. They are a popular material choice as a scaffold in tissue engineering, with their high water content providing a good environment for cell survival. The team also carried out experimental strain stiffening tests, to see if their material also exhibited the unusual stiffening and softening responses that biological fibrous networks do. These tests confirmed that the hydrogel had comparable mechanical properties to biological networks, with it performing very similarly to samples of fibrin gel. Hydrogels for cancer treatment, heart attack recovery The researchers have successfully used their tissuemimetic hydrogels to promote the growth of small-scale tumor replicas known as organoids. These are derived from donated tumor tissue, as described in a previous study. “Hydrogels that mimic the structure and properties of human tissues can recreate that environment for cells in a controlled setting,” explained first author Prof. Elisabeth Prince, director of the Prince Polymer Materials Lab, speaking to Technology Networks. “Growing tumor organoids in a biomimetic environment allows them to maintain their in vivo phenotype better, making them a better in vitro model of tumors. Also, it has tissue-mimetic hydrogels that can potentially support the healing of damaged tissues.” Prince and her team are currently aiming to test the effectiveness of cancer treatments on these organoids, with the idea of one day administering these treatments to patients in personalized cancer therapies. Another aim of her work is to develop injectable versions of this fibrous hydrogel material that can help to regrow heart tissue that has been damaged by a heart attack. “[These hydrogels] can be used as an in vitro platform for developing personalized cancer therapies and can serve as a scaffold for regeneration of damaged tissues,” Prince said. The tissue-like structure of the hydrogel, with its nanofibers, makes it well-suited to being a scaffold material. Next, Prince and her team are hoping to exploit the composite nature of these hydrogels by experimenting with different nanoparticles to try to add more functionality to the material. “We are trying to develop conductive versions of these biomimetic hydrogels to support electrical signaling in damaged cardiac and skeletal muscle tissue,” Prince said. • Prof. Elisabeth Prince was speaking to Alexander Beadle, Science Writer for Technology Networks. ABOUT THE INTERVIEWEE: Prof. Elisabeth Prince is an assistant professor in the Department of Chemical Engineering at the University of Waterloo. Her research interests lie at the interface of soft matter design, polymer chemistry, biomimetic materials and sustainability. REFERENCE: 1. Prince E, Morozova S, Chen Z, et al. Nanocolloidal hydrogel mimics the structure and nonlinear mechanical properties of biological fibrous networks. PNAS. 2023;120(51):e2220755120. doi: 10.1073/pnas.2220755120 9 MATERIALS SCIENCE Consider the humble pinecone. Found scattered on forest floors and covered in woody scales, the pinecone is a perfect example of nature’s clever shape-shifting engineering. When it is wet and humid, the scales stay closed, protecting the seeds. But when it is dry – ideal conditions for the seeds to disperse – the scales open and they are released. This naturally occurring shape-shifting structure inspired Skylar Tibbits, associate professor of design research at the Massachusetts Institute of Technology, in 2013 to design similarly "smart" materials for architecture and engineering. Think climate-adaptive building facades that can expand, contract or rotate in response to the outdoor temperature and sunlight, or flatpack furniture that self-assembles when you take it home. Enter the 4D printing revolution. This approach transcends the limitations of the static structures produced by 3D printing by adding a fourth dimension: time. Similar to the pinecone that closes its scales when wet, 4D materials are designed to autonomously change shape in response to a stimulus in their environment, such as humidity, temperature, light, pressure or magnetism. These shape-shifting materials are not just for architectural design. In recent years, 4D printing has become a transformative technology in the biomedical field, offering the potential to create smart biomaterials that change shape in response to specific physiological stimuli. In contrast to the passive materials that are traditionally used for tissue engineering, 4D printed materials are dynamic and can adapt to the constantly changing needs of the living body. So, how are these materials used in healthcare? 4D materials are first fabricated using 3D printing, then triggered by a stimulus to change their shape. This shape shift can be leveraged for deployable medical devices such as stents or orthopedic implants. Shape-Shifting Biomaterials for Tissue Regeneration Kaja Ritzau-Reid, PhD Credit: iStock TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 10 Rather than undergoing invasive surgery during implantation, materials can take on a temporary compact structure during surgery and then be deployed to their final full-size shape once they have reached the target location in the body. Some materials also benefit from being printed in a flat 2D configuration first. As Amir Zadpoor, a professor of biomaterials and tissue biomechanics at Delft University of Technology explains: “When the initial configuration of these materials is flat, it creates many opportunities for adding surface-related functionalities, including complex nanopatterns and electronic devices.” This can be particularly useful for creating complex surface nanopatterns that stimulate certain cells, or even kill bacteria, preventing infections upon implantation in the body. Shape-shifting mechanisms To create smart biomaterials there are several key requirements. Materials need to be compatible with modern 3D printing techniques (e.g., extrusion-based, light-based, bioprinting), be biocompatible and have the capability to undergo shape change in response to a specific stimulus. Taking inspiration from the pinecone, hydration is a popular stimulus in 4D printing approaches. Hydrogels are highly absorbent polymer networks that can swell or shrink in response to humidity.1 Researchers have found that by creating scaffolds with several layers, each with a different swelling mechanism, the material can bend in a controlled way when it is immersed in a liquid, creating tubular or curved structures. Zadpoor’s group recently showed that by using two different hydrogel-based materials with high- and low-swelling formulations, the scaffold could self-bend after liquid immersion, creating a curved structure that mimicked the natural structure of cartilage.2 They used this structure to grow bone cells, which were positioned in the hydrogel layers, creating a proof of concept for 4D printing multicellular cartilage tissue. Transforming geometries in the body A key benefit of using shape-shifting materials in biomedical applications is the level of adaptability and customization that is possible. For stents and prosthetics, this means that the implanted construct can adapt to the changing needs of the body. For example, a 4D printed intestinal stent was designed to be triggered by near-body temperature, allowing the stent to adjust its shape in direct response to the patient’s internal temperature.3 Similarly, vascular stents have been designed to change shape in response to blood flow or vessel diameter.4 These self-adaptive stents are highly customized, responding directly to their environment, which could reduce the need for surgical intervention in the future. 4D printing has also been used to create patches to help repair organ damage in the body. Heart attacks can cause severe damage to the heart tissue, and 4D scaffolds have been developed with a self-adaptive structure to mimic the curved surface and adapt to the contractions of the beating heart.5 To improve scaffold integration to the heart tissue, cells were added to fibrous scaffolds and aligned along the fibers to mimic the cellular architecture of heart tissue. Improving scaffold integration by incorporating cells into 4D scaffolds is a rapidly evolving field of study, with particular focus on which stage of the shape transformation process works best to add cells.6 Minimal, targeted delivery Shape-shifting materials are also advantageous for drug delivery strategies, as 4D-printed devices can be designed to release drugs in response to a specific stimulus at the target location, such as pH or temperature.7 In a recent proof-of-concept study, 4D printing technology converged with micro-robotics in a scene perhaps more reminiscent of a sci-fi space movie. The researchers created bioinspired puffball capsules – complete with ‘spores’ containing the drugs and an inbuilt propulsion system – that can be steered to their target site using a rotating magnetic field for on-demand TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 11 drug release.8 This futuristic meld of technologies gives a glimpse into a promising future for drug delivery in healthcare: highly customizable, minimally invasive, targeted care. Machine learning approaches Researchers are also starting to use AI and machine learning to fully leverage the adaptability that 4D printing offers. Using modeling and simulation, it is possible to predict the shape transformation of these materials, as well as the physiological responses. This will help to guide the selection of smart materials, as well as the ideal shape-shifting geometry during the design process. This can also inform multi-material printing, where multiple smart materials with different stimuli are used in the same scaffold or construct. Furthermore, the incorporation of sensors could offer real-time monitoring of the constructs, unlocking even more functionality. In the clinic All this sounds exciting and transformative for healthcare, but 4D-printed technologies for tissue engineering have yet to reach the clinic, largely due to some key challenges that still need to be addressed. For example, the 3D fabrication procedures used will need to be optimized to facilitate the large-scale production of these materials, as well as rigorous testing and approval processes that must be implemented before these materials reach the clinic. Each specific application will also have its own unique challenges, as requirements will differ enormously between different tissue engineering projects. Despite these challenges, it is clear why 4D printing has become a major research focus in the biomedical field. As Zadpoor explains, using shape-shifting materials can lead to a mixture of functionalities and microarchitecture that is not possible to create in any other way. It ultimately creates materials that are much more responsive and customizable to the human body. While several major hurdles will still need to be overcome before we see these technologies in the clinic, this bioinspired shape-shifting revolution will take us towards a new, 4D future in healthcare. • REFERENCES 1. Ramezani M, Mohd Ripin Z. 4D printing in biomedical engineering: advancements, challenges, and future directions. J Funct Biomater. 2023;14(7):347. doi: 10.3390/ jfb14070347 2. Díaz-Payno PJ, Kalogeropoulou M, Muntz I, et al. Swellingdependent shape-based transformation of a human mesenchymal stromal cells-laden 4D bioprinted construct for cartilage tissue engineering. Adv Healthc Mater. 2023;12(2):2201891. doi: 10.1002/ADHM.202201891 3. Lin C, Huang Z, Wang Q, et al. Mass-producible nearbody temperature-triggered 4D printed shape memory biocomposites and their application in biomimetic intestinal stents. Compos Part B Eng. 2023;256:110623. doi: 10.1016/J.COMPOSITESB.2023.110623 4. Zhou Y, Zhou D, Cao P, et al. 4D printing of shape memory vascular stent based on βCD-g-polycaprolactone. Macromol Rapid Commun. 2021;42(14):2100176. doi: 10.1002/MARC.202100176 5. Wang Y, Cui H, Wang Y, et al. 4D printed cardiac construct with aligned myofibers and adjustable curvature for myocardial regeneration. ACS Appl Mater Interfaces. 2021;13(11):12746-12758. doi: 10.1021/ acsami.0c17610 6. Kalogeropoulou M, Díaz-Payno PJ, Mirzaali MJ, van Osch GJVM, Fratila-Apachitei LE, Zadpoor AA. 4D printed shape-shifting biomaterials for tissue engineering and regenerative medicine applications. Biofabrication. 2024;16(2):022002. doi: 10.1088/1758-5090/ad1e6f 7. Zu S, Wang Z, Zhang S, et al. A bioinspired 4D printed hydrogel capsule for smart controlled drug release. Mater Today Chem. 2022;24:100789. doi: 10.1016/J. MTCHEM.2022.100789 8. Song X, Sun R, Wang R, et al. Puffball-inspired microrobotic systems with robust payload, strong protection, and targeted locomotion for on-demand drug delivery. Adv Mater. 2022;34(43):2204791. doi: 10.1002/ ADMA.202204791 ABOUT THE INTERVIEWEE: Amir Zadpoor is the Antoni van Leeuwenhoek professor in biomaterials and tissue biomechanics at Delft University of Technology, and professor of orthopedics at Leiden University medical center. His research focuses on biomechanics, biomaterials and biofabrication, including 4D printing and selffolding materials. 12 MATERIALS SCIENCE As the world shifts towards net zero, batteries will play an increasingly important part in our energy supply. Batteries are already commonplace in portable devices such as phones and laptops, and demand is rising for lithium-ion batteries that can power electric cars – over 14 million of which were sold globally in 2023.1 The ability to store and redistribute electricity generated by renewables will also be a crucial step in meeting national power needs, without recourse to fossil fuel sources. But every battery application requires slightly different properties, whether those are performance factors such as power output and lifetime, or practical considerations such as cost, weight and size. The precise balance of these characteristics is determined by the internal chemistry of the battery and manufacturers must carefully control these complex interactions to tailor the device performance to each specific application. Naturally, this requires a deep understanding of the composition of each piece of the battery unit and analytical techniques are therefore essential at every stage in the production line. 1. Analysis of raw materials Lithium-ion batteries are the most widely used battery type, being particularly suited for small portable devices and electric vehicles thanks to their high energy density and excellent operating efficiency. Deposits of this critical mineral are found globally as part of mixed metal ores. But, with no single ore or geological formation acting as a commercial source, processing requirements for this raw material will vary across different mining sites. Each individual mixed deposit must be analyzed to determine the exact quantity and proportion of every constituent element to ensure each is separated efficiently. Analytical Techniques in the Battery Lifecycle Victoria Atkinson, PhD Credit: iStock TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 13 This type of quantitative elemental identification is principally achieved through inductively coupled plasma optical emission spectroscopy (ICP-OES). Fundamentally, this technique reads the “energy fingerprint” of each element in the sample to provide a quantitative breakdown of the elemental composition. In ICP-OES, the apparatus first generates a hightemperature plasma by passing a flow of inert gas (usually argon) through an induction coil running a high-frequency alternating current. Collisions of these gas atoms with electrons accelerated by a magnetic field around the coil ionize the carrier gas, which becomes a plasma at temperatures above 6000 Kelvin. In the next stage, the sample is sprayed into the plasma stream as a mist. As the particles collide and interact with the plasma, individual atoms are ionized or excited, resulting in a series of fixed electronic energy transitions for each element. Each transition releases a single specific wavelength of light which is detected by a spectrometer, creating a characteristic emissions spectrum. The resulting experimental spectrum can then be compared against known standards to determine the identity and quantity of each element in the sample. 2. Analysis of battery components Each component in a battery, from the electrodes to the additives in the electrolyte, has been carefully tailored to optimize the battery for a particular application. Verifying the quality and composition of each battery element separately is therefore crucial to ensure the completed unit performs as expected and manufacturers use a raft of techniques to analyze each part before assembly. In a lithium-ion battery, the anodes (or negative electrodes) are typically made of graphite. They hold and release lithium ions from within their structure throughout a charge cycle. This means the material must be both porous and conductive to lithium ions while remaining fully compatible with the electrolyte and other chemical elements of the battery. Inductively coupled plasma mass spectrometry (ICP-MS)2 – a technique similar to ICP-OES but which records the atoms’ mass rather than an emission spectrum – is the most common technique to assess the purity of anode materials. Thermogravimetric mass spectrometry (TG-MS) is also used to evaluate whether any small molecules may have adsorbed onto the electrode surface during manufacture. This technique combines thermogravimetric analysis (TGA)3 – which measures mass changes as the temperature is increased to provide information about physical properties such as phase transition temperatures and adsorption processes – with mass spectrometry (MS) to identify small molecule contaminants from the molecular masses of their ions. The cathodes (or positive electrodes) are the major lithium component in a battery, being made from mixed lithium oxides. Like the anodes, cathode purity and quality is also easily determined by ICP-OES. The electrolyte solution, which transports lithium ions between the two electrodes, is a complex chemical mixture. It typically contains lithium salts (e.g., LiPF6 ), an organic solvent and a mixture of other additives to optimize battery function. The ratio of these different solution components determines the ultimate battery properties, thus monitoring and controlling their proportions is a necessary quality control step. Chromatographic techniques such as gas chromatography mass spectrometry (GC-MS) are used to evaluate the solvent composition: gas chromatography separates mixtures of gaseous compounds by their affinity to a stationary phase in a coiled column. The mass spectrometer then measures the mass of each chemical component in the mixture separately. Further techniques such as Fourier transform infrared spectroscopy (FTIR)4 and differential scanning calorimetry (DSC)5 are also used to analyze other electrolyte components such as binders, separators and coatings. 3. Analysis of the assembled battery Before sale, a finished battery will undergo a series of product tests to check that its performance and safety meet required performance and regulatory specifications. Where these checks identify a problem, TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 14 the manufacturers must be able to understand the root cause – whether it is due to a structural issue, damaged component or chemical incompatibility. Battery failure analysis is therefore an important step in the production pipeline. This process employs a wide range of techniques to probe every aspect of the battery structure, chemistry and performance. Techniques such as scanning electron microscopy (SEM)6 and energy dispersive X-ray spectroscopy (EDS)7 analyze the surface of electrodes and coatings to identify potential contaminants or imperfections which might impede the battery’s performance. SEM uses a focused beam of electrons to scan and image the surface of electrodes and coatings, while EDS uses scattered X-rays to identify contaminants by their characteristic electromagnetic emission spectra. The degradation of components is another major cause of battery failure. As such, studies into the aging and side reactions of various battery parts are a typical part of battery analysis.6,8 Impurities can react with the electrolyte, additives or separator in the battery during its function, leading to the formation of complex degradation products which reduce the efficiency of key electrochemical processes. Identifying these unwanted compounds helps to limit or prevent such side reactions. This is most commonly achieved using FTIR.9 Like ICP-OES, this technique relies on the fixed energy transitions within each compound (this time between vibrational energy levels) and produces a characteristic spectrum of IR absorption values for each compound. Thermal analyses of electrolyte constituents are also important, especially due to the potential for significant temperature changes during a battery charge cycle. Since electrolyte solvents are often volatile or flammable, characterizing the electrolyte’s thermal stability is paramount to the safe operation of the battery. Relevant metrics, such as decomposition temperature and phase transition temperatures, in addition to possible side reactions, can all be measured by TGA. The separator, a permeable membrane within the electrolyte which separates the anode and cathode to prevent short-circuiting, is also subject to temperature fluctuations during use. Differential scanning calorimetry (DSC) measures the amount of heat required to increase the temperature of the separator and is used to determine properties such as its decomposition temperature and glass transition temperature, both fundamental to the operational safety of the battery.3,10 4. Battery recycling and analysis of black mass In recent years, there has been a huge surge in demand for lithium and other critical minerals used for batteries.11 But our finite global supplies are beginning to feel the pressure of our modern need for battery technology.12,13 It is also important to recognize that while batteries reduce our reliance on fossil fuels, extensive mining for the necessary minerals creates an environmental and ethical dilemma. Some mining operations have been criticized for contaminating water supplies, mistreating workers and leaving lasting scars on the landscape.14 Fortunately, there are now several methods to recover these valuable materials from spent batteries, which can be reused in future cells. Used batteries can be collected, dismantled and shredded to create a material known as black mass. Black mass contains high concentrations of key metals such as lithium, manganese, cobalt and nickel. Identifying the components of black mass is crucial in determining how best to recover these individual metals. Elemental analysis methods such as ICP-OES, ICP-MS and EDS are used to determine the constituent elements and their proportions in the black mass, while chromatographic methods combined with mass spectrometry (e.g. GC-MS or ion chromatography) can separate the mixture and identify the components in the black mass. This knowledge then informs the metal recovery process, enabling the maximum amount of material to be recycled into new batteries while simultaneously reducing the quantity of spent waste sent to landfill. TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 15 Batteries rely on a careful balance of different chemistries to deliver optimum performance. It is therefore vital that manufacturers are able to monitor the composition of each part throughout the production process. Separating raw materials depends on knowing their constituent elements, producing quality components requires precision data about their structure and performance, while effective product testing relies on having techniques that are able to detect even the smallest deviations from the original design. Combining elemental analysis, spectroscopy, chromatography and mass spectrometry methods enables manufacturers to address each of these needs as they arise, streamlining the production process and ultimately extending the battery lifecycle. • REFERENCES: 5. International Energy Agency. Global EV Outlook 2023. https://www.iea.org/reports/global-ev-outlook-2023. Published April 2023. Accessed May 30, 2024. 6. Van Acker T, Theiner S, Bolea-Fernandez E, Vanhaecke F, Koellensperger G. Inductively coupled plasma mass spectrometry. Nat Rev Methods Primers. 2023;3(1):52. doi: 10.1038/s43586-023-00235-w 7. Pirsaheb M, Seifi H, Gholami T, et al. Thermal analysis techniques for evaluating the thermal stability of battery materials: A comprehensive review. J Anal Appl Pyrolysis. 2023;174:106136. doi: 10.1016/j.jaap.2023.106136 8. Amaral MM, Real CG, Yukuhiro VY, et al. In situ and operando infrared spectroscopy of battery systems: Progress and opportunities. J Energy Chem. 2023;81:472- 491. doi: 10.1016/j.jechem.2023.02.036 9. Xu X, Gan L, Chen R, et al. Effects of electrolyte/ cathode ratio on investigation of their thermal behaviors using differential scanning calorimetry. Appl Phys Lett. 2024;124(4):043901. doi: 10.1063/5.0177345 10. Tsuda T, Hosoya K, Sano T, Kuwabata S. In-situ scanning electron microscope observation of electrode reactions related to battery material. Electrochim Acta. 2019;319:158-163. doi: 10.1016/j.electacta.2019.06.165 11. Marschilok AC, Bruck AM, Abraham A, et al. Energy dispersive X-ray diffraction (EDXRD) for operando materials characterization within batteries. Phys Chem Chem Phys. 2020;22(37):20972-20989. doi: 10.1039/ D0CP00778A 12. Kuppan S, Duncan H, Chen G. Controlling side reactions and self-discharge in high-voltage spinel cathodes: the critical role of surface crystallographic facets. Phys Chem Chem Phys. 2015;17(39):26471-26481. doi: 10.1039/ C5CP04899K 13. Dopilka A, Gu Y, Larson JM, Zorba V, Kostecki R. NanoFTIR spectroscopy of the solid electrolyte Interphase Layer on a Thin-Film Silicon Li-Ion Anode. ACS Appl Mater Interfaces. 2023;15(5):6755-6767. doi: 10.1021/ acsami.2c19484 14. Sun YY, Hsieh TY, Duh YS, Kao CS. Thermal behaviors of electrolytes in lithium-ion batteries determined by differential scanning calorimeter. J Therm Anal Calorim. 2014;116(3):1175-1179. doi: 10.1007/s10973-014-3683-9 15. Lithium Statistics and Information. United States Geological Survey. https://www.usgs.gov/centers/ national-minerals-information-center/lithium-statisticsand-information. Accessed May 30, 2024. 16. Maisel F, Neef C, Marscheider-Weidemann F, Nissen NF. A forecast on future raw material demand and recycling potential of lithium-ion batteries in electric vehicles. Resour Conserv Recycl. 2023;192:106920. doi: 10.1016/j. resconrec.2023.106920 17. Backhaus R. Battery raw materials - where from and where to? ATZ Worldw. 2021;123(9):8-13. doi: 10.1007/ s38311-021-0715-5 18. Haider SA. The ethical dilemma of green economy: Examining the human and environmental costs of cobalt mining in DRC. Global Journal of Human-Social Science. 2023;23(B2):31-37. https://socialscienceresearch.org/ index.php/GJHSS/article/view/103694. COMMON TECHNIQUES IN BATTERY MATERIAL ANALYSIS CLICK HERE TO DOWNLOAD THE FULL INFOGRAPHIC X-RAY TECHNIQUES Degradation of the cell constituents during usage and storage, known as aging, is a major challenge. Chromatography-based methods, including liquid chromatography (LC), gas chromatography (GC) and ion chromatography (IC), are particularly useful for analyzing the battery electrolytes and electrode composition. Hyphenation of chromatographic techniques can allow further analytical questions to be answered. For example, gas chromatography-mass spectrometry (GC-MS), a destructive technique, is suited to compositional testing. In battery analysis, it has found utility in analyzing the gases generated by Li–ion batteries, giving insights on component degradation during repeated charging and discharging. Information impacting safety and optimal performance can also be gained from the analysis of cyclic carbonates. X-ray photoelectron spectroscopy (XPS) is a surface analysis technique that provides chemical state and elemental information about the top layer of a material (~ top 10 nm). The surface is exposed to an X-ray beam and the photoelectrons emitted from the surface are measured. This technique is particularly useful for analyzing the battery interfaces and changes in composition during use. X-ray fluorescence (XRF) spectroscopy identifies and quantifies the elemental composition of materials according to the X-rays emitted from sample atoms when they are energized. This non-destructive technique is able to identify inhomogeneities, inclusions, degradation products and defects. X-ray diffraction (XRD) can provide rapid, real-time structural information, helping to identify and quantify compounds and mineral compositions. It also assists in the analysis of material stability under stress and high temperatures. CHROMATOGRAPHY DATA ANALYSIS CARRIER GAS GC OVEN MASS SPECTROMETER Trap Injection Port Capillary Column Ionization Source Focusing Lens Detector Mass Analyzer RAMAN MICROSCOPY Raman microscopy combines imaging with pinpointed chemical analyses to provide molecular and structural information. This enables chemical mapping across a sample and has proven useful in mapping carbon-based materials, yielding information on defects and structural disorder and graphene stack size. It has also proven useful in developing alternative cathode materials and measuring the impact of additives on electrolytes. 17 MATERIALS SCIENCE The World Health Organization estimates that over 420 million people are living with diabetes worldwide. A common complication of diabetes is diabetic foot ulcer, and globally, there is a lower extremity amputation every 20 seconds.1 Diabetic wounds have multiple pathological features, including compromised vessel networks and persistent inflammation, which prevent the transport of oxygen, nutrients and waste to and from wound sites, disrupting wound healing. The global diabetic foot ulcer treatment market was valued at USD 8.2 billion in 2022 and is expected to reach USD 14.4 billion by 2032. The majority of diabetic wound care products are passive dressings, which merely provide a protective barrier against the external environment and do not actively promote wound healing. Here, we will describe three recent hydrogel technologies with novel concepts to promote diabetic wound healing. Innovative Hydrogel Dressing To Accelerate Diabetic Wound Healing Andy Tay, PhD Credit: iStock What is a hydrogel? Hydrogels are three-dimensional networks of crosslinked polymers that can absorb a large amount of water and swell while maintaining their structure. Hydrogels have uses in a variety of biomedical applications thanks to their superabsorbancy, biodegradability, biocompatibility, hydrophilicity and viscoelasticity. TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 18 Hydrogel with antibiofilm and antioxidant properties In a recent study, Pranantyo et al. described a synthetic hydrogel, named PPN, fabricated from crosslinked polyethylene glycol (PEG) hydrogel tethered with an antibacterial cationic polymer, polyimidazolium (PIM), and the antioxidant N-acetylcysteine (NAC).2 PIM was found to be a potent growth inhibitor for a wide spectrum of Gram-positive and Gram-negative bacteria implicated in diabetic wound infections. The authors found that their hydrogels were able to swell up to 10 times their initial water volume, and the swollen form was stable and exhibited constant mass after incubation for seven days in bacterial extracts and infected wound fluids. This suggests that PPN can soak up wound exudates and resist degradation by infected wound fluids, enabling the hydrogel to be ultralow-leachable and leave minimal residue at wound sites after dressing removal. This is crucial to prevent material-related inflammation. Using a 3D de-epidermised dermis human skin equivalent (DED-HSE) model, a living ex vivo tissue construct in which decellularized dermal scaffolds from human donors are repopulated with allogeneic donor keratinocytes, the authors showed that by day seven, their hydrogel was able to heal 40–50% of the initial wound size and promote proliferation of keratinocytes. Next, using an infected diabetic mice model, the team found that wounds treated with their hydrogel had more than 99.9% reduction in the colonization of all bacterial strains, including methicillin-resistant Staphylococcus aureus (MRSA), surpassing commercial silver-based antimicrobial dressings. This advantage also allowed their hydrogel-treated wound to be resolved of inflammation as indicated by a lower number of inflammatory monocytes in the wound tissues. Impressively, the antioxidants in the hydrogel also led to an increase in the concentrations of growth factors including vascular endothelial growth factors (VEGF) that promoted blood vessel formation and thicker granulation tissue associated with improved proliferation of fibroblasts and keratinocytes. Hydrogel loaded with exosomes Adipose-derived stem cell (ADSC)-derived exosomes are therapeutic agents in tissue regeneration as they contain bioactive proteins, nucleic acids and lipids. These molecules can contribute to wound healing by promoting anti-inflammation, inhibiting apoptosis and facilitating cell migration and proliferation. In a study published in Nature Communications, Han and colleagues describe the development of a hydrogel loaded with ADSC-derived exosomes and bovine serum albumin (BSA)-based oxygen nanobubbles to form a multifunctional wound dressing to boost oxygen levels in wound tissues and promote tissue regeneration.3 The use of BSA was also able to scavenge free radicals. Using human dermal fibroblasts in vitro, the authors showed that the oxygen nanobubbles relieved cells of hypoxia. Previous studies have found that hypoxic conditions lead to lower exosome delivery efficiency.4 The authors found that oxygen nanobubbles, which mitigated the hypoxic wound environment, significantly improved the delivery of therapeutic cargo from the exosomes. The multifunctional hydrogel also promoted better proliferation and migration of fibroblasts, along with angiogenesis in vitro. Finally, using a rat model of full-thickness wounds, hydrogel-treated animals showed flatter wound surfaces with continuous epidermis, demonstrating minimal keloid formation and scarless wound healing. Furthermore, the treated animals had a higher density of newly formed blood vessels and less inflammation. There were also lower numbers of pro-inflammatory M1-like macrophages and higher numbers of antiinflammatory M2-like macrophages. While this hydrogel was not used in a diabetic wound setting in the paper, the authors concluded that the technology has the potential to be applied to diabetic wounds, particularly because of its oxygen-supplying advantage. Mechanotherapy with hydrogel One medical device that is used for diabetic wound treatment is topical negative-pressure wound treatment (NPWT), which provides mechanical suction to TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 19 remove wound fluids and is correlated with improved wound closure.5,6 Meta-analyses found that dynamic mechanical loading during NPWT induced fibroblast cell division and migration, the secretion of growth factors and the formation of new blood vessels.7 Shou et al. developed a magnetic hydrogel using poly(ethylene glycol) diacrylate (PEGDA) containing magnetic particles. In the presence of a dynamic magnetic field, fibroblasts and keratinocytes encapsulated within the hydrogel were mechanically stimulated.8 This led to an improvement in cell proliferation, collagen deposition and VEGF production. The best effects were seen with three days of stimulation, an hour a day, while continual stimulation beyond day three led to a reduction in cell proliferation. Interestingly, the team found that fibroblasts were mechanically responsive while keratinocytes were not. Mechanical stimulation primarily activated fibroblasts to produce more extracellular matrix proteins and secretome, which activated keratinocytes, causing them to secrete more VEGF via the Ras/MEK/ERK pathway. Wanting to maximize the therapeutic impact of mechanical stimulation, the team also analyzed public databases of single-cell RNA sequencing and identified an exceptionally mechano-sensitive subpopulation of fibroblasts. They further verified this by showing that this subtype of fibroblasts proliferated faster and produced more collagen under mechanical stimulation. Using an in vivo diabetic mouse model, the team further showed that combining cell mechanotherapy led to a 200% faster wound healing rate with 200% better vascularization. As PEGDA is a non-biodegradable material and the hydrogel was applied to the wound surface rather than implanted, there was also no material-associated inflammation as assessed by counting the macrophage population and quantifying inflammation genes. Wound dressings play an important role in wound management. Although most commercial products are merely serving as a protective barrier, hydrogel can be endowed with additional properties to make it antibacterial or bioactive, which can accelerate wound healing. The use of multifunctional hydrogels as active wound dressings can help speed up wound healing, thus reducing the overall time for patients to restore their lifestyles and decreasing overall healthcare costs. • REFERENCES: 1. Liu R, Petersen BJ, Rothenberg GM, Armstrong DG. Lower extremity reamputation in people with diabetes: a systematic review and meta-analysis. BMJ Open Diabetes Res Care. 2021;9(1). doi: 10.1136/bmjdrc-2021-002325. 2. Pranantyo D, Yeo CK, Wu Y, et al. Hydrogel dressings with intrinsic antibiofilm and antioxidative dual functionalities accelerate infected diabetic wound healing. Nat Commun. 2024;15(1):954. doi: 10.1038/s41467-024-44968-y 3. Han X, Saengow C, Ju L, Ren W, Ewoldt RH, Irudayaraj J. Exosome-coated oxygen nanobubble-laden hydrogel augments intracellular delivery of exosomes for enhanced wound healing. Nat Commun. 2024;15(1):3435. doi: 10.1038/s41467-024-47696-5 4. Tong B, Liao Z, Liu H, et al. Augmenting intracellular cargo delivery of extracellular vesicles in hypoxic tissues through inhibiting hypoxia-induced endocytic recycling. ACS Nano. 2023;17(3):2537-2553. doi: 10.1021/acsnano.2c10351 5. Teot L, Ohura N. Challenges and management in wound care. Plast Reconstr Surg. 2021;147(1S-1):9S. doi: 10.1097/ PRS.0000000000007628 6. Daigle P, Despatis MA, Grenier G. How mechanical deformations contribute to the effectiveness of negativepressure wound therapy. Wound Repair Regen. 2013;21(4):498-502. doi: 10.1111/wrr.12052 7. Poteet SJ, Schulz SA, Povoski SP, Chao AH. Negative pressure wound therapy: device design, indications, and the evidence supporting its use. Expert Rev Med Devices. 2021;18(2):151-160. doi: 10.1080/17434440.2021.1882301 8. Shou Y, Le Z, Cheng HS, et al. Mechano-activated cell therapy for accelerated diabetic wound healing. Adv Mater. 2023;35(47):2304638. doi:10.1002/adma.202304638 20 MATERIALS SCIENCECredit: iStock A study led by myself, Assistant Prof. Edison Huixiang Ang from the National Institute of Education/Nanyang Technological University Singapore, with Prof. XingLong Wu and Dr. Jin-Zhi Guo from Northeast Normal University, has advanced sodium–ion battery technology. By enhancing cathodes with a vanadium–iron phosphate structure, we achieved superior ion conductivity and stability using cost-effective, eco-friendly materials. Published in Advanced Science under the 2023 Rising Stars special collection, this breakthrough could revolutionize large-scale energy storage. Fueling tomorrow: Innovating sodium–ion batteries for sustainable energy Driven by the need for cost-effective and eco-friendly energy storage solutions, our team embarked on a mission to enhance sodium–ion battery technology. With a focus on improving cathode performance, our research aimed to address the growing demand for efficient energy storage in a rapidly evolving world. To address the high cost, toxicity, poor conductivity, structural instability and limited cycling performance of conventional sodium (Na) super ionic conductor (NASICON) materials, our team developed Na₃.₀₅V₁.₀₃Fe₀.₉₇(PO₄)₃ (NVFP) encircled by highly conductive Ketjen Black (KB). We aimed to achieve enhanced ion diffusion, reduced volume change and superior cycling stability, paving the way for more sustainable and accessible energy solutions, aligning with global efforts towards a greener future. Supercharging Batteries With Improved Material Design Edison Huixiang Ang, PhD TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 21 Powering progress: Unveiling breakthroughs in sodium–ion battery technology The team synthesized NVFP with KB via a ballmilling assisted sol-gel method. We examined the structure modulation using in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy during electrochemical progress. The key findings of the paper were that: • Incorporating iron into vanadium-based cathodes enhanced conductivity and stability. • Pearl-like KB branch chains encircling NVFP particles improved overall conductivity. • An enhanced ion diffusion ability and low volume change (2.99%) were observed in the modified cathodes. • Remarkable cycling performance was achieved: 87.7% capacity retention over 5,000 cycles at 5 C. • Full cells exhibited a capacity of 84.9 mAh g−1 at 20 C with minimal capacity decay (0.016% per cycle at 2 C). Empowering energy: Advancing sustainable battery solutions We attribute the enhanced performance of the modified cathodes to a combination of factors. By incorporating iron into the vanadium-based structure and introducing the unique morphology of the KB branch chains, they created a synergistic effect that significantly improved conductivity and stability. This novel approach addresses critical challenges, including reducing the cost and toxicity of vanadium, enhancing ionic and electronic conductivity, improving structural stability, achieving durable cycling performance and maintaining high energy density and rate capability in the sodium– ion battery technology, laying the groundwork for practical applications in energy storage systems. This novel approach is environmentally friendly compared to alternative approaches because it reduces the use of toxic and expensive vanadium by incorporating cheaper, earth-abundant iron, and enhances battery performance and stability without relying on hazardous materials. These findings represent a significant advancement in the field of energy storage. By offering a cost-effective and environmentally-friendly solution for large-scale battery production, this innovation has the potential to revolutionize various industries. From renewable energy storage to electric vehicles, the adoption of sodium– ion batteries could be accelerated, leading to a more sustainable future. While the study showcases impressive performance enhancements, it primarily focuses on laboratory-scale experiments. Scaling up production and overcoming challenges in large-scale manufacturing remain significant hurdles. Furthermore, the long-term stability and performance of the modified cathodes in realworld applications necessitate further investigation. Recognizing these limitations underscores the importance of ongoing research and development to realize the potential of this technology fully in practical settings. Pioneering progress: Charting the path forward We propose several avenues for future exploration. Firstly, we suggest scaling up production processes to evaluate the feasibility of large-scale manufacturing. Additionally, investigating the long-term stability and performance of the modified cathodes in practical applications is crucial. Further experiments could focus on optimizing the composition and morphology of the cathode materials to enhance performance and address the remaining challenges. Continual refinement of this technology will be essential for its successful integration into sustainable energy storage systems on a commercial scale. • Reference: 1. Zhao XX, Fu W, Zhang HX, et al. Pearl-structure-enhanced NASICON cathode towards ultrastable sodium–ion batteries. Adv. Sci. 2023;10(19): 2301308. doi:10.1002/ advs.202301308 22 MATERIALS SCIENCE Synthetic polymers are a crucial, yet often overlooked, aspect of daily life. From the hard plastics used in packaging and consumer products to biocompatible coatings for medical materials, to advanced lightweight materials for automotive and aerospace engineering – these polymer molecules underpin a huge variety of modern advancements.1 As such polymers have become ubiquitous in everyday life, polymer analysis techniques have become increasingly important tools for scientists, allowing them to properly assess the performance of these materials in different environments. There is a wide variety of analytical techniques that can be applied to synthetic polymers, each offering a slightly different look at the chemical or physical properties of these compounds. Combining these methods, academics and R&D scientists can better understand and predict how these polymers will behave in different scenarios, paving the way for more advanced materials and breakthroughs in sustainability and plastics recycling. The importance of polymer analysis Polymer materials are made up of hundreds or thousands of repeating smaller “chain links,” known as monomers. The average molecular weight of these long polymer chains, as well as their density, crystallinity, molecular mass distribution, degree of cross-linking and the addition of any stabilizers or plasticizers can all have a significant impact on the eventual physical, thermal and mechanical properties of the polymer material.2 Modern polymer chemical analysis technologies offer R&D scientists a way to look at this fundamental structural information, which can be used to better understand why a polymer is behaving in a certain way. Exploring the Techniques Used in Polymer Analysis Alex Beadle Credit: iStock TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 23 Industrial producers of polymers and plastic products will also want to make use of mechanical testing methods in their quality control processes to ensure that their products meet all relevant performance and safety standards. Together, the broad range of existing polymer analysis techniques can be used to support and drive the creation of novel polymer materials with even more favorable properties for specialist applications. Chromatography and sustainable plastics research Chromatography is one of the first tools that a research lab might apply when creating a novel polymer material. “We usually start with chemical composition and molecular weight (length of the polymer chains) to assess new plastic materials,” said Erin E. Stache, an assistant professor of chemistry at Princeton University. “We can gather this information by using nuclear magnetic resonance (NMR) and size exclusion chromatography (SEC), sometimes also called gel permeation chromatography (GPC).” Despite recent advances, polymerization reactions do not produce a completely uniform set of polymers – there will be some natural variation in the chain length and molecular weight of the final molecules.3 This molecular weight distribution can affect the processability, mechanical strength and morphological phase behavior of the polymer.4 As a result, chromatographic methods play an important role in allowing scientists to separate these molecules into different fractions according to their size or weight and analyze their relative distribution. SEC uses porous gel beads packed inside a chromatographic column to separate a polymer dissolved in a solvent mobile phase according to their size.5 Smaller polymer molecules and ones with a lower molecular weight are more likely to get trapped in the beads’ pores, and as a result will take more time to pass through the chromatography column. This molecular weight data can also be useful to scientists wanting to study how polymers degrade in certain environments. This is a central research theme for the Stache Lab, in addition to its work investigating new polymerization techniques that yield easily degradable polymers and the recycling of waste plastics back into their monomer building blocks or other commodity chemicals. “Degradation or depolymerization requires characterization of the products,” Stache said. “These techniques help determine changes in molecular weight or modification of the polymer backbone. Then, we use this information to assess the effectiveness of our method and establish a mechanism for degradation or depolymerization. This information helps us optimize the process to be more efficient, always working towards the goal of a single product with high recovery.” Studying degradation with spectroscopic techniques Spectroscopy techniques can be a useful complement to chromatographic techniques in polymer structural characterization. The advent of high-resolution mass spectroscopy methods has seen this technique become increasingly more utilized for polymer analysis. Used together with chromatic separations, it is possible to generate extremely accurate molecular weight distribution measurements, as well as information relating to the polymer’s end groups and topology.6 Nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy and Raman spectroscopy are also common techniques applied in polymer analysis. These techniques are normally utilized for determining which functional groups are present in a polymer.7 “During degradation, we focus on the impact on molar mass, so GPC is really important for that where we can [use it],” said Andrew Dove, a professor of chemistry at the University of Birmingham. “NMR is also a very useful technique for us and we are starting to look at TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 24 more advanced methods there, like diffusion NMR and extending out at the moment to MRI [magnetic resonance imaging] techniques for imaging.” The Dove Research Group is heavily involved in exploring different aspects of polymer degradation. This includes the creation of biodegradable polymers and new polymers that can be more easily recycled, as well as polymers that can resist degradation in certain environments, such as polymer materials being used in the body for medical implants. Just like the Dove group, the Stache lab also makes use of spectroscopic techniques in their research to create a fully-formed chemical and structural characterization of the polymers they are working with. “For small molecule (<500 g/mol) identification, we use nuclear magnetic resonance (NMR), gas chromatography (GC), mass spectrometry (usually GC-MS), and infrared spectroscopy (FT-IR),” Stache said. “Combining all these techniques allows us to unequivocally determine the identity and quantity of products being formed.” Thermal techniques for polymer materials characterization Chromatographic and spectroscopic techniques allow scientists to study what is going on at the molecular level inside a polymer or plastic product. Thermal analysis techniques provide feedback on a more macro scale, giving an insight into the materials’ mechanical properties and thermal behavior. The most commonly applied thermal polymer characterization techniques are: differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA) and dynamic mechanical thermal analysis (DMTA).8 Using one or a combination of these techniques, it is possible to build up an idea of how a new polymer will react during manufacturing or when exposed to various external forces. Each of these methods operates on the principle of exposing a polymer material to heat, cold or a changing temperature and studying how the material and its properties vary under these conditions. TGA is concerned with studying changes in mass as a polymer is heated, which can be used to investigate the material’s thermal stability as well as the determination of any volatile species or fillers in the material. DSC is a calorimetry technique commonly used to study a material’s phase transitions. TMA and DMTA are both used to study a material’s response to external forces at different temperatures, with TMA using a constant force and DMTA applying periodically oscillating forces to assess deformation and kinetic properties such as thermal expansion.9 “TGA tells us the degradation temperature of the polymer, that is, the temperature at which the polymer will start to break down,” said Stache. “DSC tells us more about the physical properties of the polymer, such as glass transition temperature (Tg ) and melting temperature (Tc ),” “T g will tell us if the polymer is hard and glassy or soft and rubbery at a given operating temperature,” she explained. “Tc tells us the temperature at which the polymer will start to melt and flow.” Beyond assessing the performance of newly synthesized polymer materials, these thermal analysis methods are also routinely applied for studying polymer degradation. “We are interested in how degradation affects the materials’ properties, so we do a lot of the characterization by thermo-mechanical methods, like DSC, TGA, DMTA, tensile testing, etc.,” said Dove. In addition to chromatographic, spectroscopic and thermal analysis methods, there are a raft of other analytical techniques that can be applied to polymer analysis. X-ray diffraction and X-ray scattering data can be used to provide additional insights on the crystallinity of semi-crystalline polymers.10 Microscopy techniques can also provide extra information on a polymer’s microstructure and micromechanical properties.7 TECHNOLOGYNETWORKS.COM MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 25 Collectively, these techniques all contribute to the fabric of the polymer science sector, allowing researchers to produce more advanced, high-performance polymer materials with more favorable recycling and degradation profiles tailored to suit the modern world. • ABOUT THE INTERVIEWEES: Erin Stache is an assistant professor of chemistry at Princeton University. Research in her lab integrates organic chemistry, photo chemistry, inorganic materials, and polymer chemistry to pioneer fresh advancements in materials science and synthesis. A major aim of the Stache Lab is finding solutions for a more sustainable plastics economy through the application of innovative catalytic methods. Andrew Dove is a professor of chemistry at the University of Birmingham. He leads the Dove Research Group, a multinational collection of vibrant and dynamic researchers that are focused on challenges in polymer and materials science. He is part of the Birmingham Plastics Network, an interdisciplinary team of more than 40 academics working together to shape the fate and sustainable future of plastics. This unique team brings together chemists, environmental scientists, philosophers, linguists, economists and experts in many other fields, to holistically address the global plastics problem. REFERENCES 1. Knol WC, Pirok BWJ, Peters RAH. Detection challenges in quantitative polymer analysis by liquid chromatography. J Sep Sci. 2021;44(1):63-87. doi:10.1002/jssc.202000768 2. Physical, thermal, and mechanical properties of polymers. In: Biosurfaces. John Wiley & Sons, Ltd; 2014:329-344. doi:10.1002/9781118950623.app1 3. Murphy EA, Zhang C, Bates CM, Hawker CJ. Chromatographic separation: A versatile strategy to prepare discrete and well-defined polymer libraries. Acc Chem Res. 2024;57(8):1202-1213. doi:10.1021/acs. accounts.4c00059 4. Walsh DJ, Schinski DA, Schneider RA, Guironnet D. General route to design polymer molecular weight distributions through flow chemistry. Nat Commun. 2020;11(1):3094. doi:10.1038/s41467-020-16874-6 5. Pasch H, Bungu PE. 45 Years of polymer HPLC: A short review. Macromol Mater Eng. 2023:2300354. doi:10.1002/ mame.202300354 6. Jackson CA, Simonsick WJ. Application of mass spectrometry to the characterization of polymers. Curr Opin Solid State Mater Sci. 1997;2(6):661-667. doi:10.1016/ S1359-0286(97)80006-X 7. Alqaheem Y, Alomair AA. Microscopy and spectroscopy techniques for characterization of polymeric membranes. Membranes. 2020;10(2):33. doi:10.3390/ membranes10020033 8. Menczel JD, Prime RB, Gallagher PK. Introduction. In: Thermal Analysis of Polymers. John Wiley & Sons, Ltd; 2009:1-6. doi:10.1002/9780470423837.ch1 9. Saba N, Jawaid M. A review on thermomechanical properties of polymers and fibers reinforced polymer composites. J Ind Eng Chem. 2018;67:1-11. doi:10.1016/j. jiec.2018.06.018 10. Polizzi S, Fagherazzi G, Benedetti A, Battagliarin M, Asano T. Crystallinity of polymers by x-ray diffraction: a new fitting approach. Eur Polym J. 1991;27(1):85-87. doi:10.1016/0014- 3057(91)90130-G MATERIALS SCIENCE: REVOLUTIONIZING BATTERIES, BIOMATERIALS AND ADVANCED POLYMERS 26 TECHNOLOGYNETWORKS.COM CONTRIBUTORS Alex Beadle Alexander is a science writer and editor for Technology Networks. He writes news and features for the Applied Sciences section, leading the site’s coverage of topics relating to materials science and engineering. He holds a master’s degree in Materials Chemistry from the University of St Andrews, Scotland. Andy Tay, PhD Andy Tay received his PhD from the University of California, Los Angeles, focusing on neuromodulation and engineering. He subsequently completed his postdoctoral training at Stanford University where he developed nanotechnologies for immunoengineering. Andy Tay is currently a Presidential Young Professor at the National University of Singapore. Edison Huixiang Ang, PhD Dr. Edison H. Ang possesses a broad background and a diverse skill set within the field of materials science and engineering. He completed his undergraduate studies at Nanyang Technological University in Singapore. In 2017 he obtained his PhD from the same institution. Kaja Ritzau-Reid, PhD Kaja attained a BSc in genetics, MRes in neurotechnology and a PhD in bioengineering at Imperial College London. In 2022 she started a position as a post-doctoral research associate at Imperial College London, where she investigated the effects of materials on organoid and stem cell growth. She is currently working as a freelance science writer. Steven Gibney, PhD Steven has a BSc in pharmacology and a masters in bioscience from the University of Leeds, as well as a PhD in pharmacy from the University of Nottingham. After finishing his PhD, he spent two years working at an agency as a medical writer. Wanting to further develop his communication skills he joined Technology Networks as a science writer in 2023. Victoria Atkinson, PhD Dr. Victoria Atkinson is a freelance science writer and communicator, specializing in chemistry, sustainability and research culture. Previous to this, she was a science content developer and editor for the University of Oxford, where she completed her PhD (DPhil) in organic chemistry in 2021.