High Energy Research Articles

Challenges and Opportunities for 2D Materials in Energy Storage Technologies

Efficient energy storage systems represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Arguably, the most important advance in energy storage over the past three decades is the lithium-ion battery, which was recognized with the Nobel Prize in Chemistry. However, despite its many successes, issues related to safety, energy density, charging time, and operating temperature range have hindered the realization of the full potential of lithium-ion battery technology, particularly in large-scale applications such as grid-level storage and full electrification of transportation networks. Nanostructured materials were once thought to present compelling opportunities for next-generation lithium-ion batteries, but inherent problems related to high surface area to volume ratios at the nanometer-scale (e.g., undesirable surface chemical interactions between electrodes and electrolytes) have impeded their adoption for commercial applications. This talk will explore how chemically inert two-dimensional (2D) materials are driving a resurgence in nanostructured lithium-ion battery materials [1,2]. For example, conformal graphene coatings on battery anode and cathode powders mitigate surface degradation and minimize the formation of the solid electrolyte interphase, thus improving cycling stability [3,4]. In addition, the high electrical conductivity of graphene reduces cell impedance, resulting in enhanced kinetics that enable high-rate capability and low-temperature performance down to –20 °C [5]. On the other hand, ionogel electrolytes based on ionic liquids and hexagonal boron nitride (hBN) nanoplatelets provide safe, high-rate operation at high temperatures up to 175 °C, which represents the highest operating temperature to date for solid-state lithium-ion batteries [6,7]. The strong interfacial interactions between hBN and ionic liquids further enable novel electrolyte architectures based on layered heterostructure ionogels that result in unprecedently high energy densities and rate performance for solid-state batteries [8]. Since hBN ionogels can be formulated into printable inks and slurries, these electrolytes also present promising opportunities for additive manufacturing of solid-state batteries, supercapacitors, and related energy storage technologies [9-11].[1] D. Lam, et al., ACS Nano, 16, 7144 (2022).[2] N. S. Luu, et al., Accounts of Materials Research, 3, 511 (2022).[3] J.-M. Lim, et al., Matter, 3, 522 (2020).[4] K.-Y. Park, et al., Advanced Energy Materials, 10, 2001216 (2020).[5] K.-Y. Park, et al., Advanced Materials, 34, 2106402 (2022).[6] W. J. Hyun, et al., ACS Nano, 13, 9664 (2019).[7] W. J. Hyun, et al., Advanced Energy Materials, 10, 2002135 (2020).[8] W. J. Hyun, et al., Advanced Materials, 33, 2007864 (2021).[9] C. M. Thomas, et al., ACS Energy Letters, 7, 1558 (2022).[10] W. J. Hyun, et al., Nano Letters, 22, 5372 (2022).[11] L. E. Chaney, et al., Advanced Materials, DOI: 10.1002/adma.202305161 (2023).

Solid-State Lithium-Ion Superionic Electrolytes with Reduced Moisture Sensitivity

The remarkable safety and high energy density of solid-state batteries (SSBs) created significant advantages in the development of next-generation energy storage. The properties of these batteries are highly dependent on the characteristics of solid-state electrolytes (SSEs), making them a crucial material in the development of such batteries. Following diverse principles of material design, lithium halide SSEs, particularly Li3InCl6, open new opportunities in the development of SSBs due to their unique properties including broad electrochemical stability window, high lithium-ion conductivity, and excellent deformability. Through a mechano-thermal synthesis approach, Li3InCl6 demonstrates substantial ionic conductivity at room temperature. We studied the temperature-dependent behavior of Li3InCl6 by using in-situ/operando techniques such as XRD and XPS. However, its susceptibility to moisture poses a significant challenge for practical implementation in SSBs. To overcome this limitation, this research is focused on a novel solution: hafnium doping of Li3InCl6. Integrating hafnium into the Li3InCl6 structure results in a substantial improvement in electrochemical performance. The Li2.6In0.6Hf0.4Cl6 solid-state electrolyte not only showcases heightened ionic conductivity but also demonstrates improved resistance to moisture. The achieved ionic conductivity reaches approximately 1 mS cm-1, marking a significant 3.5-fold increase compared to Li3InCl6. Noteworthy is the fact that, after 5 hours of exposure to air with 15% humidity, the observed reduction in ionic conductivity for Li2.6In0.6Hf0.4Cl6 is 37%, a notably lower decrease compared to the 57% reduction seen in Li3InCl6.The efficacy of hafnium doping provides a crucial advancement in the field of solid-state electrolytes, promising a transformative impact on next-generation energy storage systems.

A New High-Valent Fe Redox Couple in Intercalation Electrodes

The overwhelming majority of layered oxide cathode materials are based on the redox activity of expensive and scarce transition metals like Co and Ni. While the Fe-redox based material LiFePO4 has become increasingly attractive due to its low cost, its low gravimetric energy density and relatively low operating voltage limit its use cases. A high-voltage Fe-based layered oxide cathode would provide high energy density utilizing the redox-activity of the most abundant transition metal in Earth’s crust, but such a material that provides stable and reversible electrochemical performance remains elusive. Indeed, high-voltage Fe-redox in oxides is plagued by cation disorder and oxygen dimerization, which leads to capacity fading and large voltage hysteresis (> 1 V).[1]In contrast, the layered oxide cathode Li4FeSbO6 (equivalently, Li[Li1/3Fe1/3Sb1/3]O2, abbreviated LFSO) exhibits <0.2 V of hysteresis, and a discharge plateau at 4.2 V versus Li/Li+ with two-electron capacity.[2] Both the exceptional electrochemical reversibility of this material and its phase separating nature upon (de)intercalation raise questions about the origin of these properties that are unusual for layered Fe oxide cathodes. In this work, we will discuss our efforts to probe the electronic structure of LFSO with Fe L–edge x–ray absorption (XAS) and 57Fe Mössbauer spectroscopy, as well as O K–edge resonant inelastic x–ray scattering spectroscopy (RIXS). The combination of these element-specific and valence-state sensitive techniques, in conjunction with charge-transfer multiplet and density functional theory calculations, allows us to reveal the electronic structure changes at Fe and O as a function of state of charge for the first time. Correlating these electronic structure changes with synchrotron diffraction measurements, we reveal a unique redox compensation mechanism that readily rationalizes the exceptional electrochemical reversibility, unlocking a new direction for high-voltage, Fe-based redox systems.

New 1D Nickel-Rich Ncm Cathode Materials for the Lithium-Ion Battery: Synthesis and Cyclic Stability Improvement

Lithium-ion batteries (LIBs) are considered the most promising energy system due to their low cost, high energy density, excellent performance, and long service life, implemented in several consumer devices such as cell phones, laptops, cameras, and electric vehicles [1]. In general, the chemical properties of LIA are constantly evolving, and from the point of view of cathode materials, layered LiMO2 oxides, in which M is a combination of Ni, Mn, and Co – the so-called NCM are attracting more and more attention and is considered a potential next-generation cathode material for LIA, due to their increased specific capacity (more than 150 mAh g-1) and thermal stability [2]. In addition, NCM-based cathodes can outperform the popular lithium-iron-phosphate LiFePO4 (LFP) cathodes in many areas, especially in terms of operating voltage, in which LFP-based LIBs can produce voltages below 3.4 V and suffer from high self-discharge rates. The composition of Ni, Mn, and Co can be significantly changed to optimize the capacity, performance, structural stability, and cost of lithium-ion batteries [3]. The data indicate that the B-doped NCM811 cathodes offer notable benefits, including higher capacity retention, improved rate capability, and lower mechanical strain in their charged state [4].In this study, we focus on synthesizing 1D LiNi0.8Co0.1Mn0.1O2 (NCM811) material by electrospinning method and its enhancement upon doping with Boron and morphological modifications. The electrospinning technique has already been used to obtain NCM material [5]. B-doped and undoped NCM811 nanofibers with the 1D structure were obtained by electrospinning method and characterized. The morphology and nanofiber structure of the resulting NCM811 samples (doped, un-doped) were studied using scanning electron microscope (SEM) and transmission electron microscope (TEM). X-ray phase analysis (XRD) studied the samples, and a series of peaks that entirely corresponded to the diffraction pattern of NCM811 were recorded. It is highly expected that the results may introduce some new ideas in the field of morphology modification and doping, which will be helpful for the rational design and manufacture of highly efficient cathode materials. Acknowledgments This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP19679855).

Next-Generation Batteries through Advanced 3D Electrode and Material Concepts

With the rise of renewable energy sources, energy storage solutions become increasingly important as they represent a key feature for secure and constant power supply. In this regard, battery systems play a crucial role in accelerating the transition towards sustainable and green energy sources. To meet the rising global demand, further advancement of the battery technology is imperative. One optimization pathway is to use battery materials that are more sustainable while also yielding improved electrochemical performance, contributing to both environmental and functional advancements. However, innovation must go beyond the material level, and new electrode design approaches for an efficient combination of high power and high energy systems are necessary.In this context, the three-dimensional (3D) battery concept with its increased exposed electrode surface, shows a great promise for enhanced electrochemical performance compared to the conventional flat designs of state-of-the-art electrodes. Targeting at the bottleneck of high power/high energy density systems, the incorporation of micro-structured channels within the electrodes improves lithium-ion diffusion pathways and minimize strain from volume expansion during electrochemical cycling.Our focus is the investigation of 3D electrode architectures generated by laser-processing techniques such as ultrafast laser ablation and laser-assisted printing. Working with ultrafast lasers offers the possibility to process materials while reducing thermal impact and allows the creation of well-designed and controllable electrode surface topographies. The adoption of this concept has already shown great impact in enhancing the high-rate capability and lifetime of conventional electrodes in lithium-ion batteries.[1-3] Expanding the scope, this work explores the applicability of laser-generated 3D electrode architectures to next-generation battery active materials such as high-voltage lithium nickel manganese oxide (LNMO) composites. On anode side, silicon/graphite and amorphous carbon is extensively investigated for lithium-ion batteries and sodium-ion batteries, respectively. To understand the impact of the manufacturing process, electrochemical evaluations are complemented by findings from laser-induced breakdown spectroscopy, SEM-EDX, Raman measurements, and Auger electron spectroscopy.In conclusion, this contribution highlights the promising advancements achieved by applying laser-generated 3D electrode architectures to next-generation battery materials and aims to provide valuable insights into this exciting frontier of battery research.[1] W. Pfleging, Nanophotonics 7 (2018) 549–573.[2] W. Pfleging, Int. J. Extrem. Manuf. 3 (2021) 012002.[3] M. Zaeh, Appl. Energy 303 (2021), 117693.

(Invited) There’s More to a Probabilistic Neuromorphic Computing System Than Noisy Devices

A range of computing problems require understanding uncertainty, such as climate modeling, or use statistics to model problems that are otherwise difficult to solve, such as high energy particle collisions. Currently, these computations are handled by hardware where significant energy is spent to suppress stochasticity in materials and devices, and then significant computational resources are expended to re-introduce stochasticisty in algorithms. Instead, we take inspiration from the brain, which features 1015 stochastic synapses. This talk focuses on understanding how to leverage fluctuations in devices to do efficient sampling, which is a fundamental operation in many statistical approaches to computation [1]. In the first part of this talk, we use bitstreams generated by magnetic tunnel junction and tunnel diode devices to generate samples from different distributions, an elementary operation in statistical approaches to modeling. We show how to use elementary operations on multiple bits to improve both the accuracy and complexity of sampling. While intuition motivates the asking which of the two devices is more efficient at generating a random bitstream, in the second part of this talk, we show that this consideration is a small contribution to the overall circuit required to do a complete calculation. To significantly accelerate applications requires devices that minimize the energy and area cost of the CMOS parts of the design, as the true challenge lies in holistic codesign [2].At the heart of statistical approaches to computation is sampling. Typically, a uniform random sample is generated using a pseudo-random number generator (PRNG), followed by a mathematical operation to sample an application-relevant distribution. This sample is then plugged into a sequence of deterministic calculations that comprise a model. We use magnetic tunnel junctions and tunnel diodes to generate a fair coinflip, having equal probability of each of two outscomes, from which we create a uniform random sample. We show how to relate the quality of the device bitstreams to the quality of random samples [3]. While these devices consume significantly less energy than the PRNG, the energy consumed by the PRNG is a fraction of the energy consumed by a complete calculation. We next focus on moving the entire process of sampling non-uniform distributions into hardware. We show that weighted coinflips can be used to sample any distribution with a well-defined probability distribution function using a tree. Simple logic operations can be used to combine many inaccurate fair physical coinflips to produce a single high-accuracy weighted logical coinflip, and high quality samples from non-uniform distributions. Overall, a simple implementation uses a few hundred physical coinflips, some simple logic operations (shift register, comparison, XOR extractor), and memory access to produce a sample. This success points to the potential for moving more of the model into increasingly sophisticated sampling schemes.Having established how the basic element of the computation are connected, we are now ready to examine its efficiency compared to a PRNG, whose cost is roughly nJ/operation. Thus far, we have ignored the analog signal transduction attached to the coinflip devices and the logic operations that tie them together. Coinflip devices which cannot be directly integrated with logic will suffer from a von Neumann bottleneck. Thus, the coinflip devices need to be intimately integrated with logic, requiring paying a per-device transduction penalty. We find the energy cost for even the simplest signal transduction – a stimulating pulse and a latching output – is in the 100 fJ – 1 pJ per device range, which is larger than the energy consumed by either magnetic tunnel junctions or tunnel diodes. Meanwhile, the most expensive component of the logic operations stem from the fine-grained integration of memory. While only 32 weighted coinflips are needed to draw a 32-bit non-uniform sample, there are ~232 possible weights needed. We discuss schemes to prune the values needed to avoid the situation where the weights occupy all of a 1 cm2 die. In sum, the energy and area cost of the coinflip device are less important than the energy cost of signal transduction, and the area taken by memory for storing weights of a sampling tree.We emphasize that none of our estimates represents a tight optimization of any part of an imagined probabilistic computer. Still, in a full-system implementation, the efficient management of signal transduction and memory clearly outweight the energy or space consumed by the coinflip devices themselves. These factors comprise the key variables for stochastic devices that need to be accounted for in holistic codesign for probabilistic computing.SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Regulated Interfacial Proton and Water Activity Enhances Mn2+/MnO2 Platform Voltage and Energy Efficiency

Aqueous zinc battery (AZB) is one of the most promising energy storage systems for large-scale applications due to its high safety, low cost, and environmental friendliness. To match the high capacity of zinc metal (~820 mAh g-1), various cathode materials, such as oxides, open structure analogues, chalcogens, and halogens, have been explored for AZBs. Among them, manganese dioxide (MnO2) has been considered to be one of the most attractive candidates due to its high capacity (~308 mAh g-1 for one-electron transfer) and adequate redox potential (~0.70 V vs. SHE). Recently, the MnO2 dissolution/deposition charge storage mechanism has been demonstrated to further increase the voltage and capacity of Mn-based AZBs. The dissolution/deposition (Mn2+/MnO2) is a two-electron transfer process, which doubles the theoretical capacity of MnO2 cathode to ~616 mAh g-1 and considerably increases the redox potential (~1.229 V vs. SHE). The charge storage via the dissolution/deposition mechanism pushes the aqueous-based energy density even higher, to over 1000 Wh kg-1.However, this charge storage mechanism involves liquid-solid transition, as well as the thermodynamics and kinetics of this reaction are highly dependent on the acidity and interfacial environment. Yet, the opposite effect of interfacial H+ on the dissolution/deposition processes and the role of interfacial H2O are rarely discussed. Here we introduce tetrafluoroborate anion (BF4 -) into the sulfate-based electrolyte to regulate the interfacial H+ and H2O activity. First, BF4 - hydrolysis increases the electrolyte’s acidity, promoting MnO2 dissolution. Second, BF4 - forms an H-bond network with interfacial H2O that assists H+ diffusion while retaining sufficient H2O supply to facilitate MnO2 deposition. As a result, the cathode-free Zn//MnO2 electrolytic cell achieves a high plateau of ~1.92 V and energy efficiency of ~84.23 % in the BF4 - containing electrolyte. Significantly, the cell delivers 1000 cycles at 1 C with ~100 % Coulombic efficiency and a high energy efficiency retention of 93.65 %. Our findings disclose a new strategy to promote Mn2+/MnO2 platform voltage and energy efficiency for future large-scale energy storage systems.

(Battery Division Postdoctoral Associate Research Award Sponsored by MTI Corporation and the Jiang Family Foundation) Science of Multiphysics Behavior of Si/C Composite Anodes in High-Energy-Density Lithium-Ion Batteries

The rapidly growing demands on energy storage technologies over the last decade have imposed further requirements for the high energy/power density, safety, and durability of lithium-ion batteries (LIBs). Si/C composite materials have attracted enormous research interest as the most promising candidates for the anodes of next-generation lithium-ion batteries, owing to their high energy density and mechanical buffering property. However, the major disadvantage of materials with ultra-high capacities, such as Si-based materials, is the significant volume change during cycling, which further leads to mechanical and electrochemical degradation. However, a sophisticated and quantitative understanding of the highly electrochemical-mechanical coupling behaviors is still lacking.A comprehensive computational model is indispensable in the developing process of the excellent performance of anode material due to the low-realizability, inconvenience, and high-cost of experiments, which also provides powerful tools for fabrication guidance of novel Si/C composites designs. Hence, a multiphysics modeling framework is established with a detailed geometric description to quantitatively reveal the underlying governing mechanisms of Si/C composite anode behaviors. We studied the effects of the Si weight percentage, the Si-related particle distribution, the Si-related particle size, the mechanical constraint, and the binder domain gradient on the battery performance regarding the potential behavior, capacity delivery, mechanical stress/strain, Li plating, and polarization evolution. In our study, we used silicon monoxide (SiO) as the Si element source and graphite (Gr) as the C element source. Results discover that an 8-10 wt% of SiO would be an optimal choice regarding capacity delivery and minimizing Li plating under 1C constant current charging condition. Positioning SiO particles near the separator and reducing the sizes of SiO particles are also demonstrated to be beneficial for electrochemical performance with trivial influence on mechanical mismatch. In addition, the mechanical constraint demonstrates a balanced effect on the overall performance of cells and the local behaviors of particles. Our findings also indicate that reducing the proportion of carbon-binder domain (CBD) in the upper domain (near the anode surface) compared to the lower domain (near the current collector) positively influences electrochemical performance, particularly in terms of capacity and Li plating. However, such an arrangement introduces potential risks of mechanical failures and we recommend to incorporate a higher proportion of CBD alongside the SiO particles. Finally, an anode design with a lower CBD proportion in the upper domain exhibits superior rate performance.This study explores the multiphysics behavior of Si/C anodes material using a comprehensive methodology combining experimental and FEA techniques, systematically revealing the coupling mechanism among various physical fields, as well as providing efficient and powerful tools in the design, development, and evaluation of high energy density lithium-ion batteries.

(Invited) Three Decades of Polymer Electrolyte Based DMFC: A Perspective

Direct Methanol Fuel Cell, where liquid Methanol is used as fuel and directly oxidized electrochemically to generate power, enables energy generation devices with high energy density. Hence these systems have been developed and evaluated for applications where remote and distributed generation of electrical energy are desired1. While methanol electro oxidation can in fact be achieved at temperatures in the range of 60 to 80 C, it faced two key challenges: a) The intermediate species formed during the electrooxidation poisoning the catalyst2 and b) The crossover of methanol to cathode resulting in mixed potential situation on the cathode and thus reducing the cell voltage realized3. These have been addressed and mitigated through both materials4 and engineering solutions5. In this talk, we will traverse the three decades of scientific and development journey and along the way we will cover the key contributions by S.R. Narayanan to this important technological pathway for achieving net zero CO2 emission. Dillon, R., Srinivasan, S., Aricò, A.S. and Antonucci, V. (2004) J. Power Sources, 127 (1–2), 112–126.Parsons, R. and VanderNoot, T. (1998) J. Electroanal.Chem., 257 (1–2), 9–45.Heinzel, V.M.Barragan, J. Power. Sources, 84 (1), 70-74F. Whitacare, T. Valdez, and S. R. Narayanan, J. Electrochem. Soc., 152 (9), A1780-A1789 Halpert, S. Surampudi, H. Frank, S.R. Narayanan, A. Kindler, G. Ganapathi, P. Seshanand S. Krauthamer, ECS Proceedings Volumes, Volume 1995-23, 311

Comparing Effects of Back Diffusion and Membrane Resistance on the Performance of a Low Temperature Electrochemical Hydrogen Pump

“Green” hydrogen produced via electrolysis using electricity from renewable energy sources is seen as a promising energy carrier to aid in the transition from fossil fuels because its production emits no carbon and consumes only water as a reactant. However, the high energy demand required to compress hydrogen to higher energy densities required for efficient transport and storage remains a bottleneck for its deployment1-4. Electrochemical hydrogen pumps (EHPs) are an attractive solution since they operate via isothermal compression and are thus more efficient than typical mechanical compressors which operate adiabatically1,2,5. EHPs also have the advantage of low noise, absence of moving parts, and ability to simultaneously purify hydrogen during compression1-4.In this study, an in-house built EHP test cell with an active geometric area of 25 cm2 was constructed using membrane electrode assemblies (MEA) based on a proton exchange membrane (PEM) and a platinum catalyst. The cell was used to pressurize hydrogen from atmospheric pressure to 10 barg. The net performance of EHPs is a result of the tradeoff between the two major losses that is, back diffusion of H2 and membrane resistance3-5. Thus, we compared the effect of varying temperature, in the range of 30-75°C, on cell performance. Current densities reaching 1.0 A cm-2 (corresponding to a specific hydrogen flow rate of 7.45 mLs min-1 cm-²) were achieved during testing. Linear sweep voltammetry was used to quantify the back diffusion of hydrogen with temperature, see Figure 1(a). Electrochemical impedance spectroscopy was used to determine the series resistance of the EHP. Figure 1(b) shows the increase in voltage with increasing high frequency resistance, whose largest contribution comes from the membrane, with reducing cell temperatures. Stepped chronopotentiometry measurements were used to characterize the overall cell performance. Figure 1 (c) and (d) show the effect of temperature on the polarization curves at a cathode pressure of 5 and 10 barg, respectively, of the EHP operating with an Aquivion E98-09S membrane with 0.25 mg cm-2 Pt per electrode. At 0.5 A cm-2, an applied voltage of 195 mV was required to compress hydrogen at atmospheric pressure in one step to 10 barg operating at 30°C, corresponding to an overall efficiency of 16%. When the cell temperature is raised to 75°C, a lower voltage of 132 mV is required at 0.5 A cm-2 due to the stronger effect of the reduced series resistance that leads to a higher cell efficiency of 27%. This work shows that membrane resistance has a greater effect than back diffusion on the overall EHP performance to pressures of 10 barg.Future work is focused on coupling this EHP with a photovoltaic driven electrolyser and further decreasing the energy demand required to compress hydrogen. References J. Zou, N. Han, J. Yan, Q. Feng, Y. Wang, Z. Zhai, J. Fan, L. Zeng, H. Li, H. Wang., Electrochemical Energy Reviews 2020, 3, 690–729.G. Sdanghi, J. Dillet, S. Didierjean, V. Fierro, G. Maranzana., Fuel Cells 2020, 3, 370-380Y. Hao, H. Nakajima, H. Yoshizumi, A. Inada, K. Sasaki, K. Ito., International Journal of Hydrogen Energy 2016, 41, 13879-13887.M. Ivanova, R. Peters, M. Müller, S. Haas, M. Seidler, G. Mutschke, K. Eckert, P. Röse, S. Calnan, R. Bagacki, R. Schlatmann, C. Grosselindemann, L. Schäfer, N. Menzler, A. Weber, R. Van de Krol, F. Liang, F. Abdi, S. Brendelberger, N. Neumann, J. Grobbel, M. Roeb, C. Sattler, I. Duran, B. Dietrich, C. Hofberger, L. Stoppel, N. Uhlenbruck, T. Wetzel, D. Rauner, A. Hecimovic, U. Fantz, N. Kulyk, J. Harting, O. Guillon., Angewandte Chemie, 2023, 62, e202218850B. Kee, D. Curran, H. Zhu, R. Braun, S. DeCaluwe, R. Kee, S. Ricote., Membranes 2019, 9,77. Figure 1

(Invited) Lyten’s High Energy Li-S Batteries for a Sustainable and Circular EV Economy

Li-ion batteries (LIB), though widely used in EV batteries will be unable to meet the demands of the rapidly expanding vehicular market, mainly due to the challenges of cost and availability of key materials globally with limited resources, complicated by geopolitical factors. Li-S batteries promise significant advantages over Li-ion batteries with potentially higher specific energy, lower cost, and enhanced safety. However, their implementation has been hampered by poor cycle life due mainly to polysulfide shuttle caused by the soluble polysulfide intermediates. Lyten, an advanced materials company, has developed a family of new 3D Graphene™ materials for various applications including lithium-sulfur batteries. The mechanically flexible and electrically conductive framework of 3D graphene and its hierarchical porous structure make it an ideal host for potentially confining sulfur intermediates and mitigate the polysulfide shuttle. Lyten 3D Graphene™ materials have already shown enhanced sulfur utilization in Li-S cells far superior to the commercial nanocarbons (Fig. 1), even while their further fine-tuning is on-going. Lyten has established environmentally friendly 3D graphene-sulfur cathode fabrication methodology with high sulfur loadings using an aqueous binder.In parallel, Lyten has been developing new protected Li anodes, advanced stable electrolytes that can function at low quantities (electrolyte/sulfur ratio), and multi-functional separators with an ability to block polysulfide crossover. Integration of these cell components resulted in Li-S cells with specific energy comparable to current Li-ion cells (250-275 Wh/kg). The cycle life is, however, relatively modest with 300 cycles @ 100% DOD, C/3 in coin cells, and ~150 cycles@100% DOD and over one thousand cycles @ 50% DOD in multi-layer pouch cells and 18650 cylindrical cells. There is a steady growth in both these categories enabled by further tuning of 3D graphene and advances in other materials.Recently, Lyten has set up semi-automatic assembly lines for both multi-layer pouch and 18650 cylindrical cells, targeting an annual capacity of 2.4 MWh. These cells have started showing excellent consistency in specific energy in both cell formats. Fig.2 shows the narrow variability in the performance of 35 pouch and 18650 cells made recently for a customer.Finally, preliminary safety tests performed on the recent prototype cells have yielded surprisingly good results for the Li-S cells containing Li metal anode. Tolerance to usual abuse conditions, e.g., internal and external shorts, overcharge and overdischarge, as demonstrated in our ARC tests will be an additive advantage of Lyten Li-S cells. Figure 1

Rational Design of Hybrid Electrolyte for All-Solid-State Lithium Battery Based on Investigation of Lithium-Ion Transport Mechanism

Lithium-ion batteries (LIBs) are widely used in various applications, including personal electronic devices, electric vehicles, and energy storage systems. Given the increasing demand for LIBs, there is need to develop rechargeable batteries with high energy densities, long cycle life, and enhanced safety. Lithium all-solid-state batteries (ASSBs) could improve operational safety by eliminating flammable liquid electrolytes and using non-flammable solid electrolytes. Among the various types of solid electrolytes explored, solid polymer electrolytes (SPEs) have garnered significant attention owing to their desirable properties, such as good processability, light weight, flexibility, and favorable interfacial contact with the electrodes. To develop practical battery systems using SPEs, improving the ionic conductivity mechanism of lithium-ion (Li+) in SPEs is crucial. Li+ transport mechanism of SPE is typically known as segmentation motion and ion hopping. In SPE, crystalline and amorphous phases coexist, and movement of Li+ occurs mainly in the amorphous phase. Therefore, the use of SPE at high temperatures improves ionic conductivity, but still that have limitation by low ionic conductivity (10-7~ 10-8 S cm-1) at ambient temperatures, low Li+ transference numbers, a restricted electrochemical window, and low mechanical strength. Hybrid polymer electrolytes (HPEs) combine an inorganic ceramic electrolyte (ICE) and SPE to create a ceramic-in-polymer or a polymer-in-ceramic hybrid and have improved ionic conductivity and mechanical stability compared to SPE. Ceramic materials of HPE can be classified into oxide-based materials and NASICON-type materials. Oxide-based materials such as SiO2, Al2O3, etc. induce an increase in the amorphous area of PEO and improve segmental mobility by preventing recrystallization of the polymer, thereby increasing ionic conductivity. NASICON-type materials, such as Li7La3Zr2O12 (LLZO), Li1+xAlxTi2-x(PO4)3 (LATP), etc. are promising candidates for improving ionic conductivity by increasing the mobility of Li+ because they form ionic conductive channels within the ceramic bulk. However, despite the observed improvements in performance, the Li+ ion transport mechanism in HPEs and its correlation with the electrochemical cell results remain unclear.In this study, we present a new approach to improve the performance of ASSB by establishing the Li+ transport mechanism through a designed HPE system proven through experimental results and density functional theory (DFT) calculations. To achieve high energy density ASSB, LiNi0.8Co0.1Mn0.1O2 (NCM811) Li ASSB cell was applied, and through a combination of experiment and DFT calculation, HPE was manufactured by PEO-based semi-interpenetrating polymer network (semi-IPN) SPE and Li1+xAlxTi2-x(PO4)3 (LATP) of NASICON-type. As a result, we confirmed that Li+ migrates through the interface of SPE and LATP, which has a significant effect on the improved ionic conductivity (7.23 × 10-4 S cm-1 at 45 ℃). In addition, it was confirmed that Li dendrites were suppressed and cycle performance were improved due to the improved physical strength of the electrolyte with the addition of ceramics. This suggests a promising design strategy for high-performance Li ASSB.

Understanding Electrode-Electrolyte Interfaces in Gel Polymer Electrolytes Using in-Operando Raman Spectroscopy

Gel polymer electrolytes hold enormous potential for advancing battery performance and technology, promising high energy densities and safe, rechargeable quasi solid-state batteries. GPEs offer higher ionic conductivities than solid electrolytes and enhanced safety in comparison to liquid electrolytes. A particular advantage of these electrolytes has been their ability to create robust electrode electrolyte interfaces that guide uniform deposition and stripping of lithium via their mechanical strength from the polymer and interface species that form during initial cycling.Herein we report that 1:1 dimethoxyethane (DME) and dioxolane (DOL) with lithium bistrifluoromethanosulfonyl imide (LiTFSI) and lithium nitrate entrapped in Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) gel polymer electrolytes have shown stability for up to 500 hours in lithium metal symmetric cells at 1 mAh/cm2 and performs at 5mAh/cm2 in dynamic symmetric cell cycling. To understand the fundamental interfacial phenomenon governing lithium deposition and growth in this system in-operando Raman was conducted on an anodeless Cu|PVDF-HFP|Li cell. Copper was sputtered onto the polymer electrolyte before assembly with a thickness of 20nm, providing an optically transparent electrode through which the Raman laser could pass through to detect interfacial species. We observe that PVDF-HFP acted as a chemically stable polymer electrolyte while Raman shifts associated with TFSI anions disappear near the electrode surface. The spectral and electrochemical data allow us to build a model for the growth and evolution of interfaces in an anodeless lithium metal battery cell with a GPE.Acknowledgement: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under contract number DE‐SC0014664. Figure 1

Synthesis Strategies for Highly Stable Sodium and Potassium Manganese Hexacyanoferrates

Sodium- and potassium-ion batteries (NIBs and KIBs) have been recognized as a promising alternative to lithium-ion batteries (LIBs), especially for stationary grid-scale applications that favor inexpensive storage over high energy density.1 NASICON-structured phosphates and alluaudite sulfates offer cheap synthesis routes but demonstrate low energy density2,3. Layered oxides can provide a higher energy density but require complex synthesis routes and degrade quickly4. Prussian Blue Analogues (PBAs) benefit from facile precipitation synthesis, flat voltage plateaus, and specific capacities greater than 150 mAh g-1.5 However, capacity fading due to Jahn-Teller distortion, manganese dissolution, and residual interstitial water limit their cycle life6,7. In this study, synthesis parameters and post-synthesis treatment of Na2Mn[Fe(CN)6] and K2Mn[Fe(CN)6] are discussed. Furthermore, the addition of solubilized conductive carbon additives to synthesis solutions, both to enhance electronic conductivity and provide a flexible framework to reduce strain during cycling, is explored. Na2Mn[Fe(CN)6] electrodes demonstrate a specific capacity of 149.6 mAh g-1 and surpass 250 cycles at 1C before dipping below 80% capacity retention. K2Mn[Fe(CN)6] electrodes demonstrate a specific capacity of 155.1 mAh g-1 with negligible capacity fading over the first 50 cycles at 0.1C. Our results indicate that lowering the temperature during synthesis improves morphology and cycling performance even when a chelating agent is used to control the reaction speed. References (1) Liu, J. Addressing the Grand Challenges in Energy Storage. Advanced Functional Materials. February 25, 2013, pp 924–928. https://doi.org/10.1002/adfm.201203058.(2) Zhang, X.; Rui, X.; Chen, D.; Tan, H.; Yang, D.; Huang, S.; Yu, Y. Na 3 V 2 (PO 4 ) 3 : An Advanced Cathode for Sodium-Ion Batteries. Nanoscale. Royal Society of Chemistry February 14, 2019, pp 2556–2576. https://doi.org/10.1039/c8nr09391a.(3) Niu, Y.; Zhao, Y.; Xu, M. Manganese‐based Polyanionic Cathodes for Sodium‐ion Batteries. Carbon Neutralization 2023, 2 (2), 150–168. https://doi.org/10.1002/cnl2.48.(4) Xiao, J.; Li, X.; Tang, K.; Wang, D.; Long, M.; Gao, H.; Chen, W.; Liu, C.; Liu, H.; Wang, G. Recent Progress of Emerging Cathode Materials for Sodium Ion Batteries. Materials Chemistry Frontiers. Royal Society of Chemistry May 21, 2021, pp 3735–3764. https://doi.org/10.1039/d1qm00179e.(5) Wang, Q.; Li, J.; Jin, H.; Xin, S.; Gao, H. Prussian-Blue Materials: Revealing New Opportunities for Rechargeable Batteries. InfoMat. John Wiley and Sons Inc June 1, 2022. https://doi.org/10.1002/inf2.12311.(6) Shang, Y.; Li, X.; Song, J.; Huang, S.; Yang, Z.; Xu, Z. J.; Yang, H. Y. Unconventional Mn Vacancies in Mn–Fe Prussian Blue Analogs: Suppressing Jahn-Teller Distortion for Ultrastable Sodium Storage. Chem 2020, 6 (7), 1804–1818. https://doi.org/10.1016/j.chempr.2020.05.004.(7) Ge, J.; Fan, L.; Rao, A. M.; Zhou, J.; Lu, B. Surface-Substituted Prussian Blue Analogue Cathode for Sustainable Potassium-Ion Batteries. Nat Sustain 2022, 5 (3), 225–234. https://doi.org/10.1038/s41893-021-00810-7.

A Mechanism of Resistance Switching in CNT Based Memory Devices

Carbon nanotubes (CNTs) show promise for high energy efficiency electronic devices due to their high electrical conductivity. One possible application is in the fabrication of resistance-change computer memory, where the application of an external electrical bias can use a CNT layer as the switching element in a RAM cell. Memory cells of this type have been extensively demonstrated, where the electrical resistance of a switching layer of CNTs can be reversibly controlled by the application of external bias [1].To better understand these devices, we have developed a nanoscale model of their electrical switching. Towards this end, first-principles calculations of the electrical conductivity of CNT-CNT junctions were performed using the Density Functional Tight Binding (DFTB) in combination with the Non-Equilibrium Greens functions (NEGF) approach, enabling an improved understanding of the tunnelling of electrons across a range of CNT junctions [2]. These results demonstrate that the conductivity of CNT contacts depends on the overlap area between nanotubes and exponentially on the distances between the carbon atoms of the interacting CNTs. Secondly, we employed coarse-grained molecular dynamics [3,4] to produce nanoscale dense CNT film models like those used in the devices. We devise a set of metrics for characterising the structural properties of CNT films, and apply them to a set of model films designed to mimic those used in microelectronics devices. In order to understand how the geometrical properties of CNTs affect the film structure, we analyse films with different CNT chirality and length distributions. Unlike previous studies that focused on relatively low-density systems below ∼0.4 g/cm3, we also consider films with density of ∼0.6 g/cm3, as employed in experimentally fabricated CNT-based NRAM devices. By adding amorphous carbon to the film models, in varying amounts, we are then able to assess its effects. Finally, these two elements were combined to produce electrical simulations of the conductivity of the CNT films connected to TiN electrodes. These electrodes are shown to be partially oxidized during the device fabrication. The electrical conductivity in a device is characterized by formation of conduction paths formed by CNTs between the electrodes and connected via the CNT junctions. The conductivity is modulated by charging of CNTs and amorphous carbon present in the film.Using these simulations, we propose a resistance switching mechanism in TiN/CNT/TiN devices based on the physical movement of CNTs. During the initial operation of the device, oxygen is released from the oxidized bottom electrode and this readily reacts with individual CNTs to form charge trapping sites. Once these sites have become charged, they enable controllable movement of CNTs at the bottom electrode under the application of electric field. By reversibly connecting and disconnecting such CNTs from the bottom electrode, the electrical conductivity through the CNT film as a whole can be controlled.

A Novel Multi-Stage Stochastic Estimation Algorithm for Estimating the Parameters of the Extended Single Particle Model of a Lithium-Ion Battery

Lithium-ion batteries (LiBs) are commonly used as energy storage for many applications due to LiBs’ high energy density, long cycle life, and reliable manufacturing processes. Hence, effective performance management of LiBs is important and is implemented via Battery Management Systems (BMS)[1]. A BMS also maximises the safety and lifetime of battery packs; and therefore, needs to estimate the internal battery states including State of Charge (SoC) and State of Safety (SoS). Accurate estimation of battery SoX can be realized with the use of an accurate battery model [2].From the different types of battery models, electrochemical models (EMs) are considered the most accurate type of cell-level model [2]. EMs are sets of coupled-partial differential equation systems, where each equation is derived from the physics occurring in the cell. Of the different EMs, the partial two-dimensional model (P2D) is considered the most accurate cell-level model. However, the P2D model is complex and has no analytical solution, thus requiring computationally expensive iterative solvers for implementation. This makes practical implementation of the P2D model on BMS platforms challenging. Hence, most approaches seen in the literature prefer the use of reduced order versions (ROM) of the P2D model, that require far less computational power for implementation [1].One such ROM is the extended Single Particle Model (eSPM) which differs from the P2D model in considering each electrode to be modelled by a single spherical particle and charge conservation in the electrolyte to follow a simplified linear relationship. These assumptions help the model be accurate up to a 2C operational current, and enable an analytical solution to be derived using direct solving of the eSPM equations [2]. Due to fast-forward computation and reasonable accuracy, we’ve chosen the eSPM model for parameter estimation (PE). For accurate measurements of the model parameters, expensive and invasive experimental techniques are typically required. Non-destructive PE methods have a growing interest in the literature as they are not only non-invasive but also enable real-time dynamic PE to be done on a BMS [3].PE of EMs can be categorized under two approaches: deterministic methods and stochastic methods. Deterministic methods require a form of gradient descent to be used, wherein partial derivatives of the parameters of the model need to be calculated. This approach tends to be computationally expensive and tends to converge to local minima instead of searching the parameter space thoroughly. Hence, stochastic approaches incorporate randomness, thus searching the entire parameter space for the global optima [3]. Multiple different stochastic approaches have been employed for PE of EMs [4]. In this work, we compare and contrast some of the commonly used approaches and propose a novel multi-stage approach based on a combination of different stochastic PE algorithms.The proposed algorithm (see Figure (1)) requires three sets of data as inputs: the cell chemistry, constant current discharge data and the parameter boundaries of the eSPM model. Using these definitions, the first stage of the algorithm estimates a parameter set that has a reasonable level of accuracy i.e. less than 4% root mean square error (RMSE). The second stage of the algorithm does region-by-region optimisation, where parameters sensitive to different regions of the discharge curve are varied until the overall error is reduced to less than 1% RMSE. The proposed approach significantly reduces the estimation processing time compared to the ‘brute-force’ approach and is flexible in selecting different algorithms for each stage.Thus, contributions of this paper are briefly explained as follows: A performance comparison of the proposed algorithm with different stochastic estimation algorithms including the genetic algorithm, the particle swarm optimisation algorithm and the simulated annealing algorithm.A fast and adaptable multi-stage PE algorithm for the LiB eSPM model, with average estimation speeds of less than fifteen minutes for a typical BMS processor, with accuracy of less than 1% RMSE error.Validation of the algorithm with dynamic drive-cycle test data. [1] L. Lu et al, “A review on the key issues for lithium-ion battery management in electric vehicles,” Journal of Power Sources, vol. 226. pp. 272–288, Mar. 15, 2013. doi: 10.1016/j.jpowsour.2012.10.060.[2] S. Abada et al, “Safety focused modeling of lithium-ion batteries: A review,” J Power Sources, vol. 306, pp. 178–192, Feb. 2016, doi: 10.1016/J.JPOWSOUR.2015.11.100.[3] E. Miguel et al, “Review of computational parameter estimation methods for electrochemical models,” Journal of Energy Storage, vol. 44. Elsevier Ltd, Dec. 15, 2021. doi: 10.1016/j.est.2021.103388.[4] A. Jokar et al, “An Inverse Method for Estimating the Electrochemical Parameters of Lithium-Ion Batteries,” J Electrochem Soc, vol. 163, no. 14, p. A2876, Oct. 2016, doi: 10.1149/2.0191614JES. Figure 1

Electro-Chemo-Mechanical Modeling of Composite Cathodes in All-Solid-State Li-Ion Batteries

A model-based understanding can assist and accelerate developing all-solid-state batteries (ASSB). In addition to chemo-mechanical influences within electrode particles (e.g., NMC) [1-2], a solid electrolyte (e.g., argyrodites) introduces additional interfacial interactions between electrode and electrolyte phases [3-5]. The present research derives and implements a coupled multi-physics finite-element model that captures electrochemical, transport, and structural behaviors of composite electrode structures. The models incorporate concentration-dependent and anisotropic material properties that are based on previously published combinations of experiment and density functional theory (DFT). These include stiffness and fracture toughness, porosity and crystallographic orientation, and operating conditions such as charge/discharge rates and external pressure.Figure 1 illustrates predicted stresses developed during electrode manufacturing. The relatively complex cathode microstructure is based on replicating scanning electron microscopy (SEM) images [6]. The composite electrode consists of electrode, electrolyte, and pore phases (Fig. 1a). As illustrated in Fig. 1b, the ASSB synthesis process involves applying and removing high compressive pressure, which causes plastic deformation and introduces residual stresses. Figure 1c shows residual von Mises stresses near electrode-electrolyte interfaces that can be on the order of a gigapascal. The synthesis-generated residual stresses serve as initial conditions for modeling the chemo-mechanics during battery cycling.During cell operation, spatially varying Li concentrations cause material deformation and associated stresses. Figure 1d shows predicted crack nucleation and growth during operation. Depending on the stress levels, crack nucleation and growth leads to cell degradation and capacity fade. The models predict interfacial fracture and phase separations using phase-field fracture theory. In phase-field formulation, the sharp cracks are approximated as diffuse cracks using a process-zone. High values of the phase parameter ξ (Fig. 1d) represent cracked surfaces. The structural disintegration and loss of active surface areas increase the tortuous path for Li/Li-ion transport, which eventually manifests as capacity-fade.The simulations are validated using published experimental work. The modeling approach, which combines phase-field and finite-element algorithms, is implemented using the COMSOL Multiphysics software. The models are expected to inform microstructure/manufacturing design and optimal operating conditions that improve cycling performance and limit/prevent mechanical damage.[1] K. Taghikhani, P.J. Weddle, J.R. Berger, and R.J. Kee. Modeling coupled chemo-mechanical behavior of randomly oriented NMC811 polycrystalline Li-ion battery cathodes. J. Electrochem. Soc., 168(8):080511, 2021.[2] R. Xu, Y. Yang, F. Yin, P. Liu, P. Cloetens, Y. Liu, F. Lin, and K. Zhao, Heterogeneous damage in Li-ion batteries: experimental analysis and theoretical modeling. J. Mech. Phys. Solids, 129, 160, 2019.[3] K. Taghikhani, P.J. Weddle, R.M. Hoffman, J.R. Berger, and R.J. Kee. Electro-chemo-mechanical finite-element model of single-crystal and polycrystalline NMC cathode particles embedded in an argyrodite solid electrolyte. Electrochim. Acta, 460:142585, 2023.[4] A. Bielefeld, D.A. Weber, R. Rueß, V. Glavas, and J. Janek. Influence of lithium ion kinetics, particle morphology and voids on the electrochemical performance of composite cathodes for all-solid-state batteries. J. Electrochem. Soc., 169(2):020539, 2022.[5] P. Minnmann, F. Strauss, A. Bielefeld, R. Ruess, P. Adelhelm, S. Burkhardt, S.L. Dreyer, E. Trevisanello, H. Ehrenberg, T. Brezesinski, F.H. Richter, and J. Janek. Designing cathodes and cathode active materials for solid-state batteries. Adv. Energy Mater., 12(35):2201425, 2022.[6] C. Doerrer, I. Capone, S. Narayanan, J. Liu, C.R.M. Grovenor, M. Pasta, and P.S. Grant. High energy density single-crystal NMC/Li6PS5Cl cathodes for all-solid-state lithium-metal batteries. ACS Appl. Mater. & interfaces, 13(31):37809–37815, 2021. Figure 1

Impact of Pretension and Cycling Window on Degradation of Graphite/Silicon Composite Anodes

Challenges such as mechanical degradation and limited cycle life persist for high energy density lithium-ion batteries with silicon/graphite composite anodes. In this research work, the patterns of degradation of cells with silicon/graphite composite and NMC622 cathode are examined at varied cycling conditions and applied external pressure or pretension. The most notable outcome of this analysis is that cells cycled between 0 and 100 State-of-Charge (SoC) exhibit the most accelerated aging process. Increasing the pretension force effectively restrains the irreversible expansion of the cells, and has a positive effect on capacity retention.In this research, a comprehensive experiment was conducted involving 46 cells subjected to diverse cycling conditions, voltage windows, pretension forces, and temperatures. Reference performance tests (e.g. HPPC and 1/20 C-rate charge tests) are conducted regularly for analysis of degradation mechanisms. The capacity fade, resistance growth, and thickness increase are correspondingly shown in Figures 1, 2, and 3 with ampere hour throughput as the x-axis. The legend columns indicate test conditions, including C-rate, SoC window during cycling, temperature (in degrees Celsius), and pretension force (in psi). As is shown in all figures, there is a substantial dependence on the SoC window for cycling. To be specific, a rapid rate of capacity loss, resistance increase, and thickness increase occurs in the cell group cycled over the full SoC window (plotted in blue). Cells cycled under full SoC windows also exhibit an early accelerated fading (knee [1]) of capacity and accelerated increase (elbows [2]) of resistance and thickness. According to [3], this accelerated aging could be a consequence of side reactions and increased mechanical stress within the silicon particle when operating across a broad potential range.Meanwhile, for the cell group with restrained cycle windows (plotted in gray) the cells have not yet reached any knee, and have a relatively linear capacity loss. It should be noted that, within the range of partial cycling windows examined, cells subjected to a cycling range of 50-100 exhibit the most rapid degradation, which aligns with the conclusions presented in [4] due to the time at elevated potential. In Figure 2, the elevated temperature (depicted in red) exhibits a significant influence on the increase in resistance, potentially attributed to the growth of the solid electrolyte interface (SEI), but minimal impact on capacity loss. Maintaining other conditions constant and comparing cells under 25 psi and 15 psi (marked with hollow circles and filled circles, respectively), it is evident that a higher pretension force has a positive effect on cell capacity loss. Simultaneously, in Figure 3, the pretension force at 25 psi (marked with hollow circles) effectively restrains the irreversible expansion of the cells. The results are similar to the degradation pattern outlined in [5], it is observed that employing a high pretension force facilitates the mitigation of both degradation and expansion. As highlighted in [6], heightened temperatures lead to accelerated resistance growth. Nevertheless, the impact of various C-rates on degradation remains inconclusive [6].This research systematically analyzed cell-level degradation through an extensive array of experiments, providing valuable insights into the intricate dynamics of capacity fade, resistance increase, and thickness growth. The study's revelation that the cycle window exerts a pronounced impact on battery health could offer crucial guidance for the design of Battery Management Systems (BMS). Moreover, the work establishes a foundational basis for future research, particularly in exploring electrode-level degradation patterns. These contributions collectively enhance the understanding of energy storage systems, offering practical implications for optimizing battery performance and longevity in various applications.[1]Attia, Peter M., et al. "“Knees” in lithium-ion battery aging trajectories." Journal of The Electrochemical Society 169.6 (2022): 060517.[2] Strange, Calum, et al. "Elbows of internal resistance rise curves in Li-ion cells." Energies 14.4 (2021): 1206.[3] Verbrugge, Mark, et al. "Fabrication and characterization of lithium-silicon thick-film electrodes for high-energy-density batteries." Journal of The Electrochemical Society 164.2 (2016): A156.[4] Xu, Bolun, et al. "Modeling of lithium-ion battery degradation for cell life assessment." IEEE Transactions on Smart Grid 9.2 (2016): 1131-1140.[5] Mohtat, Peyman, et al. "Reversible and irreversible expansion of lithium-ion batteries under a wide range of stress factors." Journal of The Electrochemical Society 168.10 (2021): 100520.[6] Pannala, Sravan, et al. "An Experimental Correlation of Degradation with Cell Reversible and Irreversible Expansion Measurement in Pouch Cells." Electrochemical Society Meeting s 243. No. 2. The Electrochemical Society, Inc., 2023. Figure 1

Understanding the Mechanical Behavior of Sulfide Solid Electrolyte Membranes for Practical Applications in All-Solid-State Batteries

All-solid-state batteries (ASSBs) hold great promise as next-generation energy storage systems due to their enhanced stability and high energy density compared to traditional lithium-ion batteries. This improvement stems from the use of a solid electrolyte (SE) instead of a highly volatile liquid electrolyte and the incorporation of a lithium metal anode. In general, sulfide-based SSBs require adequate pressurization conditions to establish an intimate interface between the solid particles, ensuring a continuous electron/ion conduction path. At the cell level, maintaining external stack pressure during operation is crucial to preserve conformal solid-solid contact. Furthermore, when scaling up, fabrication pressure should be carefully considered to enhance electrode densification without causing damage. In particular, the fabrication of thin, robust, and scalable SE membranes faces practical challenges due to a limited amount of polymeric binder and the low intrinsic ductility of SEs after densification. Understanding the mechanical behavior of these SE membranes is essential to ensure their structural stability during manufacturing.In this study, we systematically examined the mechanical properties of SE and SE membranes. The deformability of various types of sulfide SEs was assessed using a powder compaction test, departing from the commonly used indentation method. The yield pressure, which indicates the deformability of the SE powder, is influenced by the composition and synthesis conditions of the SEs. The stress-strain behaviors of the SE membranes were obtained through tensile and flexural tests for both as-prepared and pressed samples, respectively. The tensile and bending behaviors of the SE membranes strongly depend on the combination of the SE and polymeric binder. The utilization of a ductile SE and a rubbery polymer binder can enhance the flexibility and ductility of the membrane, leading to increased densification degree and low interfacial resistance even under lower fabrication pressure. The details of cell configuration, fabrication procedure, and the resulting performances of the cell will be discussed in this talk.

One-Dimensional Van Der Waals V2Se9 As a Conversion-Type Anode Material for Advanced Li Rechargeable Batteries

Volume expansion of active materials during lithium storage is one of the main issues in Li-ion batteries (LIBs) that should be addressed. In particular, large volume changes and particle cracking are problematic for electrode materials based on conversion reaction, which are considered attractive anode materials with high energy densities. In this study, a one-dimensional van der Waals (1D vdW) material, V2Se9, is proposed as a conversion-type anode material for LIBs. The V2Se9 electrode material has a 1D chain molecular structure with vdW interactions between chains to form a bulk crystal structure. The spaces between the 1D chains act as structural buffers and provide short Li+ diffusion paths that can improve the electrochemical performance of the electrode materials. The V2Se9 electrode exhibits a high reversible capacity of 563.3 mAh g-1 at 100 mA g-1 and a high rate capability of 109.1 mAh g-1 at 3200 mA g-1. The capacity retention of V2Se9 electrodes is 83.72 % after 100 cycles. Synchrotron X-ray diffraction and X-ray absorption spectroscopy reveal the formation of Li2Se and V metal, indicating that Li ion storage occurs via the conversion reaction. The structural stability of V2Se9 is demonstrated using SEM measurements of the discharged and charged V2Se9 electrodes during cycling. These results demonstrate the reaction mechanism of V2Se9 and highlight the potential of 1D vdW materials as high-performance anode materials in LIBs.