2024 roadmap for sustainable batteries

Modification of aluminum current collectors with a conductive polymer for application in lithium batteries

The majority of published R&D in supercapacitors relies on testing at a small coin or Swagelok cell size. This is often due to a lack of availability of equipment and knowledge required to move to a larger scale. Whilst comparisons between materials and other components can be made at the small cell level, the actual performance in larger devices does not necessarily follow to the same extent. In many cases, a scaling factor can be applied to the values of energy and power density for an active material to give the corresponding values in large devices but this is not always the case. For the extrapolation of performance from small to large cell to be valid, many factors must be considered and matched to real devices such as electrode thickness, relative electrolyte amount, current collector properties and separator type. Whilst allowing an estimate of large device properties in this way from small cell level is useful, this approach does not consider many of the problems encountered when scaling up that also differ between cell geometries (cylindrical, pouch or prismatic) can result in predicted performances never being achieved. In the current work, the development from coin cell to >800 F A5 sized pouch cell (the same geometric area as the batteries of the Nissan Leaf) is reported using commercially available activated carbon (YP50-F, Kuraray, Japan) as the active material and TEABF4in acetonitrile electrolyte, with comparisons made throughout between the small and large scale. The scale-up of mixing of electrode ink is demonstrated from the 50 g to 10 Kg scale, with discussion of the effects of various components on the solid content achievable at the viscosities required for coating. Various parameters in electrode production are discussed in relation to their effects on cell performance at the coin and large pouch level including electrode thickness/loading and drying temperature profiles, the later of which being surprisingly shown to be responsible for delamination of electrode from current collectors and complete failure in large cells over time (not observed in coin cells). The effect of calendaring of electrodes at different temperatures is shown to produce a range of electrode densities, with the effect on adhesion, specific capacitance and ESR investigated in cell. It is shown that whilst electrode capacitance is, to a broad degree, unaffected by calendering, much benefit can be gained in terms of ESR and adhesion but that over-calendering has a major detrimental effect. The production of A5 sized pouch cells from the electrodes produced is illustrated, with early cell testing results used to highlight the problems faced in supercapacitor pouch cells resulting from early capacitance fade, gas production and a lack of compression. These problems are addressed through the application of external compression (as is provided in module assemblies and by the spring in coin cells) and through the float ageing of cells to a stable capacitance and subsequent gas removal, with the differences in time and energy required at coin and pouch cell level to achieve this highlighted. In conclusion, the effects and contributions of electrode thickness, number of electrodes, electrolyte mass and “parasitic” components such as packaging in pouch cells are considered in terms of both volumetric and gravimetric energy and power densities, contrasting the real device values obtained in scale-up with those of the active materials often reported and those predicted from coin cell results. Figure 1

Application of a carbon nanotube (CNT) sheet as a current collector for all-solid-state lithium batteries

Binder materials play an increasingly important role in battery technology; they have a substantial influence on the batteries performance and lifetime behavior. However, it is widely noticed that deficiencies in binder performance, as well as aging-related issues, significantly affected the resultant shortened life cycle of batteries.Established systems utilizing carboxymethyl cellulose (CMC) and polyvinylidene fluoride (PVDF) have fallen short of meeting the increasing requirements regarding poor elasticity and polarity, which are of importance for accommodating volume expansion and ensure adhesion. The adhesion plays a crucial role for the connection and conductivity not only within the electrode materials but also towards the current collectors and therefore is significant for battery performance. Different influencing factors on the polymer structure like mechanical shear stress during the dispersion process or the crosslinking behavior of the binder with the active material depending on the functional groups have an impact on the binder-material-interaction and therefore on adhesion and performance of the battery cell.The mechanical and electro physical tasks of the binder are very diverse and grow with the increase of new materials, as active materials e.g., and processing methods. However, the property profile of the binder is rarely adapted, ever through it contributes significantly to the performance of the binder cell. This research deals with sustainable battery processing by using e.g. biodegradable polymeric binder materials and the application in energy storage systems. The investigation of adhesion and cohesion characteristics of new binder systems were characterized with a combination of electrochemical impedance spectroscopy (EIS) to study the binder influence on the battery cell. Especially the aging of a battery connected to the binder is evaluated by EIS. The results lead to further interpretations on the adhesion ability and the failure patterns.Consequently, a comprehensive knowledge about binder behavior within a battery system and associated optimization of binder properties, which is imperative for achieving sustainable battery materials, is the goal for sustainable energy materials.

Lithium (Li) has been widely studied as a promising anode material for secondary batteries because of its excellent performance. However, the severe issue of dendrites must be solved for manufacturing safe and sustainable batteries. The proper selection and design of three-dimensional (3D) current collectors are of great significance for regulating the formation of Li dendrites. Here, 3D stable lithium metal anodes were prepared by growing N-doped carbon nanotubes on the surface of carbon cloth (CC). Experimental results reveal that the presence of carbon nanotubes increases the specific surface area of carbon cloth, and the local current density is effectively reduced. Nitrogen doping significantly enhances the lithiophilicity of CC, which is conducive to reversible Li plating and stripping. The formation of dendrite can be greatly inhibited on the 3D Li composite electrodes, thus leading to steady voltage curves at current densities of 10 mA cm–2 and 3 mAh cm–2 for 300 h. Furthermore, a full cell assembled with this electrode and a commercial high-load (120 g m–2) LiFePO4 exhibits excellent cycle stability with a capacity retention rate of 83.4% after 650 cycles at 1 C and excellent rate performance. These results prove the potential for the commercialization of Li metal anodes.

Energy Storage Options for Self-powering Devices

A comprehensive understanding of aging phenomena in lithiumion batteries requires advanced analytical tools. This study applies a multi-method post-mortem approach to characterize structural and chemical changes in graphite anodes from cells cycled under conditions designed to induce lithium plating. The work is part of the SUSTAIN project, which supports the development of a catalog of battery damages to enable reliable diagnostics for second-life and recycling applications. Samples from aged and reference 18650-type cells were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), and laser-induced breakdown spectroscopy (LIBS). This combination enabled cross-validation of findings and a deeper insight into surface morphology, elemental composition, chemical bonding, and lithium distribution. The analysis revealed two distinct degradation features on the aged anodes—a porous carbon-rich surface and a localized mossy structure—each with unique signatures across the applied methods. The results highlight how different techniques complement each other in identifying electrolyte breakdown products, structural disorders, and lithium-related changes. This study demonstrates the value of a multi-method strategy for building a structured catalog of degradation modes, supporting condition diagnostics, and sustainable battery use.

Aiming to improve the sustainability of materials for lithium‐ion batteries (LIBs), this work reports on the development of novel membranes based on iota‐carrageenan biopolymer and their suitability as separator in LIBs applications. The membranes are prepared by freeze‐drying and its morphology, thermal, mechanical, and electrochemical properties are evaluated as a function of polymer concentration in the solution. Porous membranes with a degree of porosity above 90% and different interconnected pore sizes between 50 and 70 µm for both polymer concentrations are obtained. The electrochemical parameters of the membranes are influenced by the carrageenan polymer concentration, being 1.34 mS cm‐1, 3, 7, and 0.48 for ionic conductivity, tortuosity, MacMullin number, and lithium transference number, respectively, for the membrane prepared from the 4 wt% carrageenan content solution. The half‐cells cathodic prepared with the developed membranes show good cyclability and rate capability. The discharge capacity values obtained with the membrane prepared from 4 wt% carrageenan content are 145 and 25 mAh g‐1 at C/10‐ and 1C‐rates, respectively, demonstrating excellent battery cycling performance and long‐term stability. Thus, this work demonstrates that iota‐carrageenan biopolymer membranes developed by freeze‐drying can be used as separators for a next generation of more sustainable batteries.

The growing population and increasing demands for energy are overwhelming our supply of fossil fuels and limiting the availability for future generations. Technologies for energy storage devices are emerging to replace conventional fuel-based technologies to meet emissions goals set by world governments and the rapid electrification of the transportation sector. Lithium-ion batteries (LIBs) are widely used for energy storage in devices across many commercial applications. LIB electrodes are continuously evolving due to demands for higher energy density and long cycling life. Among the recent developments in anode electrode materials, silicon (Si) is regarded as the most promising replacement for graphite due to its high theoretical specific capacity (~4200 mAh g-1), which is over 10 times greater than that of conventional graphite anodes (~372 mAh g-1). Despite the advancements, persisting challenges hinder the commercialization of Si for LIB anodes. Si-based electrodes are susceptible to rapid degradation due to the large volume change (approx. 400%) of Si particles during lithium insertion and extraction. The repeated volume change leads to the pulverization of the Si material, ultimately leading to decreased cycling stability from the loss of contact with the current collector. To overcome this obstacle, 3-dimensional porous and hollow nanostructures have been employed to provide sufficient void space to accommodate the volume change during electrochemical cycling. However, with the demands for material cost-reduction from industry, Si structures' strategic engineering must be cost-effective for commercial viability.Our team has developed a patent-pending cost-effective, scalable, and green methodology to use bio-renewable templates to synthesize a 3-dimensional Si architecture, called Si nano-quills (SiNQs). We innovated a two-step, cost-effective process that yields SiNQs with a porous morphology and hollow interior structure. First, in a scalable sol-gel process, silica gel particles were prepared using commonly available low-cost chemicals. The unique mesoporous SiNQ morphology was engineered using surfactant-modified cellulose nanocrystals as a bio-renewable sacrificial template. The templates were removed via thermal treatment to form silica nanoparticles. These particles, called silica nano-quills (SilicaNQs), possess a 3-dimensional bulk structure comprised of hollow quill-like arms and a high degree of porosity. In the second step, we employed a low-temperature magnesiothermic reduction method to convert SilicaNQs into SiNQs with a relatively large surface area. Anode electrodes were fabricated using SiNQs as the active material for electrochemical testing. The slurry was prepared using the active material, carbon black, and PVDF with a mass ratio of 60:20:20 coated onto an ion-permeable Bucky Paper (BP, a flexible and conductive paper made of carbon nanotubes). The 2032-type coin cells were assembled for battery testing using SiNQ electrodes (with an active mass loading of 1 mg cm-2) and a lithium metal chip as the counter electrode. The coin cells were cycled at a current rate of 0.1C (420 mA g-1) over the potential range of 0.01 – 1.0 V at room temperature. The SiNQ anode offered superior battery capacity retention of 73% of the initial reversible capacity of 963 mAh g-1 after 220 cycles. In comparison, batteries fabricated from the Mg reduction of commercially available mesoporous silica, SBA-15, offer capacity retention of only 52.6% after 100 cycles. The SiNQ precursor is engineered to possess porous walls with a superior BET surface area (1265 m2 g-1) compared to SBA-15 (550 m2 g-1). After Mg reduction, the SiNQs retain a BET surface area of 232 m2 g-1, whereas the surface area of reduced SBA-15 is 74 m2 g-1. The superior performance of SiNQs is due to their unique morphology that offers high surface area and porosity for effective diffusion of lithium ions and more sites for interactions with lithium ions, leading to a higher reversible capacity. Moreover, the porous architecture of SiNQs can effectively mitigate the volume change issue during lithiation and delithiation processes, thus providing a good cycling performance.

Lithium-ion batteries (LIBs) have profoundly advanced the development of electric vehicles (EV). However, one of the remaining bottlenecks in their widespread deployment is the long charging time typically required for commercial LIBs. There is a global push towards extreme fast charging (XFC) of EV batteries to reduce their charging times to 10-15 minutes.1 However, XFC causes severe degradation in the electrochemical performance of LIBs, which is mainly attributed to irreversible Li plating on the surface of the graphite anode rather than intercalation of Li ions inside the graphite as the battery is fast-charged.2 Since Li plating has been identified as one of the major XFC degradation mechanisms Bs, understanding its origin and spatial heterogeneity across three dimensions (3D) on porous graphite anodes as a function of time necessitates a non-destructive characterization platform to differentiate between graphite and Li.Neutron-based imaging provides the sensitivity to differentiate graphite from Li due to the large difference in their total neutron cross-sections (Li:C ~ 73:11 barns). However, high energy X-rays enable penetrating the metallic battery components. e.g., Cu, Al. We tested the feasibility of simultaneous neutron and X-ray tomography (NeXT) on the BT-2 imaging beamline at National Institute of Standards and Technology Center for Neutron Research.4 Our spatial resolution for both X-rays and neutrons was ~15-20 μm. For ex-situ Li plating detection, we imaged 1) pristine, and 2) a cycled graphite anode.5 For cycled anode, we disassembled the battery pouch cells in their fully discharged condition and harvested the anode after 450 cycles of 9C charging and C/2 discharging. For data analysis, we used 2D bivariate histogram phase segmentation to differentiate different battery materials such as Cu, graphite, etc. However, low X-ray energy (40keV) combined with the flat sample geometry of the graphite strips made it challenging to remove beam hardening artifacts from copper and, therefore, to segment lithium from graphite. In addition, to determine NeXT feasibility for in-situ imaging, we also characterized a fully assembled, uncycled single-layer battery pouch cell. However, the high neutron attenuation by the hydrogen in EC: EMC (3:7) electrolyte and hydrogenous polymeric materials in the Celgard separator made it particularly difficult to segment graphite anode from the separator and positively identify interfaces.In this presentation, we will outline the design and characterization of a neutron-friendly LIB coin cell for extreme fast-charging. Our design is based on a standard 2032 format coin cell with custom modifications to address the dual criteria of electrochemistry and neutron imaging, i.e., good neutron transmission and relative contrast from a functional LIB at 6-C charging rate. We will present three advantages of coin cell geometry: 1) it provides more uniform attenuation throughout the entire tomography scan thus, reducing artifacts; 2) multiple coin cells can be stacked on top of each other for high throughput battery imaging; 3) it reduces the amount of expensive deuterated materials needed while developing the optimum cell configurations. In addition, we will address the need of a deuterated EC: DMC electrolyte in a fluorinated separator for the neutron-friendly battery design (Figure 1). Since the total neutron cross-section of deuterium and fluorine are on the orders of magnitude lower than that of hydrogen, we anticipate that these modifications will increase neutron transmission through the battery, thus improving signal-to-noise ratio and reducing acquisition time especially at low neutron flux facilities. Secondly, they will result in a cleaner electrolyte-separator-anode interface for the detection of plated lithium because of absence of hydrogen. Finally, we will show how these modifications affect the electrochemical performance of our LIB coin cells to determine the onset of Li plating at 6-C charging rate. i-e., capacity fade vs. number of cycles.

Gallium-based liquid metals (GLMs) are promising anode materials for lithium-ion batteries due to their low-melting point, fluidity, high-electrical and -thermal conductivity, and high-theoretical capacity for Li (769 mAh/g, Li2Ga). Notably, GLMs undergo a reversible liquid-to-solid-to-liquid transition during lithiation and delithiation, enabling a self-healing mechanism that mitigates surface defects. This mechanism extends the cycle life of anodes utilizing GLMs either as active materials( 1–6 ) or in combination with high-volume expansion materials such as silicon (~400%)( 7–9 ).Fundamental studies on the self-healing mechanism of GLMs are limited. Previous investigations have primarily relied on macroscopic characterizations such as X-ray diffraction (XRD) in bulk electrodes( 3,10 ) or in situ transmission electron microscopy (TEM) on individual GLM nanoparticles (NPs) in solid-state cells open to the environment( 6,11 ). In this work, we adopt a multi-scale approach to gain insights into the (de)lithiation mechanism. We conducted: (1) in situ TEM observations of GLM NPs on a TEM grid current collector to simultaneously track lithiation/delithiation dynamics across multiple nanoparticles; (2) cryogenic TEM where GLM NPs on a TEM grid are cycled in a lithium-ion battery electrolyte, and the grid is subsequently transferred to a cryo-TEM for high-resolution interfacial characterization of the GLM NPs; and (3) cryogenic focused-ion beam tomography to analyze structural changes in a composite electrode comprised of GLM NPs, Super P carbon, and PVDF binder on a Cu current collector over continuous cycles within a coin or pouch cell. By investigating GLMs at multiple length scales, this study advances the understanding of how the lithiation/delithiation mechanism of GLM NPs influences capacity fade in lithium-ion batteries. In a broader context, this study establishes a framework for future multi-length scale investigations into battery materials.References Jin, X. et al. Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability-Tuning Technology for Lithium-Metal Anodes. Adv. Mater. 34, 2200181 (2022).Zhu, M., Li, S., Li, B. & Yang, S. A liquid metal-based self-adaptive sulfur–gallium composite for long-cycling lithium–sulfur batteries. Nanoscale 11, 412–417 (2019).Guo, X. et al. A Self-Healing Room-Temperature Liquid-Metal Anode for Alkali-Ion Batteries. Adv. Funct. Mater. 28, 1804649 (2018).Pu, J. et al. Liquid Metal-Based Stable and Stretchable Zn-Ion Battery for Electronic Textiles. Adv. Mater. 36, 2305812 (2024).Liu, G. et al. Soft, Highly Elastic, and Discharge-Current-Controllable Eutectic Gallium–Indium Liquid Metal–Air Battery Operated at Room Temperature. Adv. Energy Mater. 8, 1703652 (2018).Huang, C. et al. Alkali-ion Batteries by Carbon Encapsulation of Liquid Metal Anode. Adv. Mater. n/a, 2309732.Hapuarachchi, S. N. S. et al. Utilizing Room Temperature Liquid Metals for Mechanically Robust Silicon Anodes in Lithium-Ion Batteries. Batter. Supercaps 1, 122–128 (2018).Ju, Z. et al. Assembled MXene–Liquid Metal Cages on Silicon Microparticles as Self-Healing Battery Anodes. Nano Lett. 24, 6610–6616 (2024).Zhao, Z. et al. Liquid Metal Remedies Silicon Microparticulates Toward Highly Stable and Superior Volumetric Lithium Storage. Adv. Energy Mater. 12, 2103565 (2022).Wang, K. et al. Core-shell GaSn@rGO nanoparticles as high-performance cathodes for room-temperature liquid metal batteries. Scr. Mater. 217, 114792 (2022).Liang, W. et al. Nanovoid Formation and Annihilation in Gallium Nanodroplets under Lithiation–Delithiation Cycling. Nano Lett. 13, 5212–5217 (2013).

Lithium-ion batteries (LIBs) offering the highest energy density among the known battery chemistries are the major contenders for both transportation and stationary storage applications. In order to satisfy the demands of energy density for these applications, new full cell configuration with either improved working voltage or specific capacity is needed to further enlarge its energy density. One candidate that has received a great deal of attention is the spinel cathode LiMn2O4, which offers the advantages of a high operating voltage (4.0 V vs. Li+/Li) and an excellent rate capability. Nonetheless, the relatively low specific capacity of 125 mAh·g-1 is mainly due to the restricted operating voltage between 3 and 4.5 V. In theory, LiMn2O4 cathode can deliver a capacity of ∼297 mAh·g-1 when 2 mole of lithium ions are inserted/extracted into/from both 8a tetrahedral and 16c octahedral sites of the spinel lattice at the voltages of, respectively, ∼4.0 and ∼2.7 V.1 Phase transition related to 4.0 V plateau is highly reversible, involving only two similar cubic spinel phases. However, phase transition related to 2.7 V plateau is partly reversible because a cubic spinel transforms to a tetragonal spinel with Jahn-Teller distortion occurring as a result of Mn3+ formation. The increase in the axial ratio from c/a = 1.0 in the cubic phase to c/a = 1.6 in the tetragonal phase due to the cooperative Jahn-Teller distortion leads to a fracture of large particles, which induces a loss of electrical contact with the current collector upon cycles.2 These effects cause serious capacity fading. However, the dynamic process of this phase transition has never been fully understood due to a lack of characterization techniques. Based on the above considerations, we report an in operando neutron diffraction study to fully understand the ~2.7 V related phase transition in the Li1+xMn2O4 spinel upon electrochemical cycling. We found solid solution formation upon reversible discharge and charge process, although a first-order phase transition is widely believed. The solid solution formation is possibly due to a thick electrode configuration that we applied and a large overpotential it could generate, which is cosistent with the phenomenon that observed under high-rate charging/discharging of LiFePO4 using in situ synchrotron XRD.3 J. B. Goodenough, M. M. Thackeray, W. I. F. David, P. G. Bruce, Rev. Chim. Miner., 1984, 21, 435.S.-H. Kang, J. B. Goodenough, and L. K. Rabenberg, Chemistry of Materials, 2001, 13, 1758-1764.H. Liu, F. C. Strobridge, O. J. Borkiewicz, K. M. Wiaderek, K. W. Chapman, P. J. Chupas, C. P. Grey, Science 344, 7 (2014).

Alternative binder–free electrode based on facile deposition of carbon/graphene–TiO2 on the coin cell anode for a lithium–ion battery

Aluminium and copper foils constitute essential current collectors in lithium‐ion batteries (LIBs), critically influencing both battery performance and manufacturing costs. As LIB adoption grows exponentially, the sustainability and cost‐effectiveness of these current collectors have emerged as pivotal factors to establish circular economies in battery technologies. Although extensive research has prioritized recycling strategic cathode elements (e.g., Li, Co), spent LIBs also contain significant quantities of highly recyclable and valuable Al and Cu that can be directly reintroduced into existing supply chains to address resource scarcity, mitigate environmental impacts and enhance economic feasibility. This review first analyses the functional significance, criteria, historical evolution, and recycling imperatives of current collectors in LIBs, followed by a mechanistic discussion of fundamental recycling principles. A comprehensive evaluation of state‐of‐the‐art recycling technologies for Al and Cu current collectors is then presented, complemented by a critical assessment of conventional foil manufacturing processes to identify compatibility requirements for incorporating recycled materials. In summary, the discussion pinpoints persistent challenges and emerging opportunities in current collector recycling, offering strategic insights towards a fully circular future for LIB production systems. This work is expected to advance novel and sustainable technologies for recycling current collectors to promote sustainable development and circular economy.

Developing new and sustainable batteries is essential for modern society. Both cationic doping (e.g. transition metals) and anionic doping (F-, O2-, S2-, PO43-, etc.) can be employed to improve the electrochemical behaviour of electrode materials. Herein, the anion-doping, or multianion approach, is comprehensively reviewed and investigated. It is observed that the optimized compositions of some electrode materials can involve metastable or transient states. Going beyond the inductive effect, we propose that the simultaneous use of several kinds of anions in the framework of the same host material could create a sort of energized state in the electrode material, and this could be interpreted within the "entatic state" principle which is used in coordination chemistry, catalysis, and bioinorganic chemistry. In this new hypothesis, the coordination of a cation by several anions with different properties can modify the local structure and it could enhance the electrochemical performance; this could be particularly useful for the future post-lithium batteries. The multianion approach can also be applied to electrolytes and interfaces. Finally, new theoretical calculations on multianion-based materials (carbonophosphates, thiocarbonates and Mg8Mn16O32-zFz) are reported here, highlighting the need for further research in the coordination sphere of metal-ligand systems for tuning battery properties.