bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding and Controlling Stack Pressure Inhomogeneity in Anode-Free Solid-State Batteries
Authors: Thorpe Micah , Zhang Mengyao , Liao Daniel W. , Kim Younggyu , Sandoval Stephanie Elizabeth , Nelson Douglas Lars , Shevchenko Pavel , McDowell Matthew Todd , Thouless M.D. , Dasgupta Neil P.
Published: December 2024

Lithium (Li) metal anodes are widely studied as replacements for current graphite anodes as they have projected higher energy density. However, Li-metal batteries face issues with dendrite propagation and the eventual formation of dead Li. Solid-state batteries (SSBs) are a promising pathway to realize Li-metal batteries, which is attributed to their ability to improve safety and stability through the use of solid-state electrolytes. In particular, “anode-free” SSBs can enable high energy densities by forming a Li metal anode in situ. The initial Li nucleation, plating, and stripping behaviors in anode-free SSBs is influenced not only by the interfacial electrochemistry, but also by the mechanical stresses present along the current collector interface. Mechanical stress also plays a key role in Li metal anode deformation, where creep is the dominant deformation mechanism. However, to date, stack pressure is typically reported as a singular value, rather than considering the temporal and spatial variations in interfacial stress as the battery cycles.

This work investigates the role of inhomogeneous stack pressure on Li anode formation and dissolution against a sulfide solid electrolyte. To compensate for this inhomogeneous stack pressure, elastomeric interlayers are used to increase the uniformity of stress along the interface, and thus improve electrochemical cyclability. To analyze the impact of elastomeric interlayers on areal Li plating coverage, post-mortem optical microscopy images of the current collector are captured, showing an improvement in areal coverage from 49% to 70%. The reversible capacity also increases from 89% to 94% with inclusion of an elastomer layer. To confirm the trends in an elastomer layer on increasing stack pressure homogeneity, the mechanical stress at the anode-free interface is modeled using finite-element simulations under different stack pressure geometries. System-level simulations illustrate tradeoffs with respect to the uniformity of mechanical stress and energy density. This work demonstrates the importance of studying external auxiliary components and packaging in SSBs to optimize anode-free SSB performance.
Relating Capacity Loss to Crack Propagation in All-Solid-State Batteries - a 3D Imaging Study
Authors: Lindner Adrian , Kiyek Vivien , Mail Matthias , Menesklou Wolfgang , Finsterbusch Martin , Scherer Torsten , Kübel Christian , Fattakhova-Rohlfing Dina , Guillon Olivier , Krewer Ulrike
Published: December 2024

In an attempt to find energy storage systems able to overcome the challenges of traditional lithium-ion-batteries, solid-state batteries are one of the most sought-after technologies in recent years. The possibility to eliminate safety concerns of organic electrolytes as well as the utilization of lithium metal as a high energy anode material have pushed their development in academia and industry alike. Garnet type oxides like Li7La3Zr2O12 (LLZO) are promising candidates due to their relatively high ionic conductivity and electrochemical stability. However, LLZO can be susceptible to the formation of secondary phases and cracks during operation, leading to severe capacity loss. Therefore, present work tackles the challenge of crack formation through high-resolution 3D-imaging. FIB-SEM tomography of LCO-LLZO composite cathodes reveals the spatial and temporal distribution of cracks during electrochemical cycling. Additionally, quantitative image analysis reveals a connection between crack formation and electrode properties, e.g., impeding three-dimensional electronic and ionic transport. Based on structural simulations (GeoDict), ionic transport in the electrolyte drops by 50 % after crack formation. In summary, we show how high-resolution FIB-SEM tomography can be applied to solid-state battery research.

Acknowledgements

This work was funded by the German Ministry for Education and Research (BMBF) in the project CatSE2 under the reference number 03XP0510C. This work was carried out with the support of the Karlsruhe Nano Micro Facility (KNMF) a Helmholtz Research Infrastructure at Karlsruhe Institute of Technology (KIT).

Figure 1: Development of pore size distribution (PSD) in garnet type solid state composite cathodes during cycling. Initially (0 cycles), pores are distributed homogeneously throughout the cathode. After cycling (EoL), we find that cracks form close to the separator, leading to an accumulation of inactive regions.

Figure 1
Elucidating Ion Transport Phenomena in Sulfide/Polymer Composite Electrolytes for Practical Solid-State Batteries
Authors: Oh Kyeong-Seok , Lee Ji Eun , Lee Yong-Hyeok , Jeong Yi-Su , Kristanto Imanuel , Min Hong-Seok , Kwak Sang Kyu , Lee Sang-Young
Published: December 2024

Solid-state batteries (SSBs) are emerging as a safer, higher-energy alternative to traditional lithium-ion batteries, driven by the demand for advanced energy storage solutions. Despite the potential of inorganic/polymer composite solid-state electrolytes (CSEs) to enhance SSB performance, the mechanisms of ion transport in these systems remain poorly understood. This study aims to elucidate these mechanisms by exploring the formation of bi-percolating ion channels and ion conduction at the interfaces between inorganic and polymer electrolytes in CSEs.

We selected a model CSE composed of argyrodite-type Li6PS5Cl (LPSCl) and a gel polymer electrolyte (GPE) containing a Li+-glyme complex for ion conduction and a crosslinked ethoxylated trimethylolpropane triacrylate (ETPTA) polymer for structural support. Our findings reveal that the percolation threshold of the LPSCl phase within the CSE is significantly influenced by the elasticity of the GPE phase. Moreover, by modulating the solvation/desolvation dynamics of the Li+-glyme complex within the GPE, we achieved enhanced ion conduction across the LPSCl-GPE interface.

The optimized CSE, incorporating a balance of material chemistry and composition, was integrated with an aramid nonwoven porous substrate to achieve scalability and flexibility in manufacturing. The resultant CSE, with dimensions of 8 × 6 (cm × cm) and a thickness of approximately 40 μm, was paired with a high-mass-loading LiNi0.7Co0.15Mn0.15O2 cathode and a graphite anode to construct an SSB full cell. This assembly, characterized by a bi-cell configuration and a negative (N)/positive (P) capacity ratio of 1.1, exhibited a remarkable volumetric energy density of 480 Wh Lcell
-1 and stable cyclability at 25 °C.

This study not only advances our understanding of ion transport phenomena in CSEs but also presents a pragmatic approach to the design and fabrication of SSBs with superior performance metrics. By integrating insights into ion channel formation and interfacial conduction with innovative materials engineering, we present a scalable and effective strategy for the development of high-performance SSBs. This research underscores the critical role of CSE design in overcoming the limitations associated with both inorganic and polymer electrolytes, paving the way for the next generation of energy storage technologies.

Figure 1
(Invited) Towards Automated Materials Discovery for Next-Generation Batteries with Solid-State Electrolytes
Authors: Wang Yan
Published: December 2024

Solid-state batteries are increasingly seen as essential for next-generation energy applications in consumer electronics and electric vehicles. The key component of solid-state batteries is the solid-state electrolytes with high ionic conductivity and great interfacial stability against battery electrodes. Traditional discovery of solid-state electrolyte materials for high ionic conductivity often proceeds based on trial-and-error without an understanding of underlying structure-composition-property relationships, and so far only a handful of lithium and sodium conductors have been discovered with desired conductivity.

Computational modeling based on density functional theory has become a cornerstone of materials design, by providing insights into fundamental processes that are not easily accessible in experiments, and enabling fast and efficient prediction even before material synthesis [1-2]. Such predictive power has made computational modeling a critical tool to design new solid-state ionic conducting materials with desired properties and accelerate the development of next-generation batteries with solid-state electrolytes.

In this talk, I will present our recent findings in the physical and chemical design principles for solid-state materials with high ionic conductivity and stability [3]. More specifically, I will discuss crystallographic features which would enable fast ionic transport in inorganic solids, such as body-centered-cubic in sulfides [1] and corner-shared-polyhedron frameworks in oxides [4], and demonstrate how high-throughput calculations can be applied with such features in the design and discovery of new ionic conductors. I will also discuss our most recent efforts at Samsung Advanced Materials Lab, where we are developing an automation platform for inorganic battery materials discovery by combining high-throughput computation and robotic synthesis [5].

[1] Y. Wang et al., “Design principles for solid-state lithium superionic conductors,” Nature Materials, 14, 1026-1031, (2015).

[2] G. Ceder, S. Ong, Y. Wang, “Predictive modeling and design rules for solid electrolytes.” MRS Bulletin, 43(10), 746-751 (2018).

[3] Y. Xiao, Y. Wang, G. Ceder, et. al., “Understanding interface stability in solid-state batteries”, Nature Review Materials, 5, 105 (2020).

[4] K. Jun, Y. Wang, G. Ceder, et. al., “Lithium superionic conductors with corner-sharing frameworks”, Nature Materials 21, 924 (2022)

[5] J. Chen, S. R. Cross, Y. Wang, W. Sun, et. al., “Navigating phase diagram complexity to guide robotic inorganic materials synthesis”, Nature Synthesis, 1-9, 2024
Strategies for Mixed Ionic-Electronic Conductivity in Co-Doped Li-Garnet Based Electrolytes
Authors: Pachulska Klaudia , Cuper Aleksandra , Winkowska-Struzik Magdalena , Michalski Przemyslaw , Struzik Michal
Published: December 2024

Solid-state electrolytes based on lithium garnet frameworks, such as Li7La3Zr2O12 (LLZO), brings a promise for enhanced safety and performance of next-generation lithium-ion batteries. Despite the promise of higher energy and power density than liquid electrolyte-based cells, superiority of their solid-state counterparts has not yet been demonstrated in working systems. One of the explanations can be attributed to the mismatch of the design and composition of the currently used battery electrodes to work with the solid electrolyte. One possible scenario for improving the electrochemical performance of solid-state electrolyte cells could be the use of composite electrodes, one component of which would be LLZO-based material modified to conduct both lithium ions and electrons to serve as a medium between the solid electrolyte and the electrochemically active material.

In this study, we explore impact of the simultaneous doping with transition metals on the garnet framework of LLZO with perspective to introduce mixed ionic-electronic conductivity with enhanced overall conductivity. We investigate the crystal structure using X-ray diffraction (XRD) and elucidate the local structural changes through Raman spectroscopy. The electric transport properties, crucial for battery performance, are thoroughly characterized via impedance spectroscopy and DC measurements.

Our results reveal a systematic enhancement in the electronic contribution to total conductivity. These findings not only advance the fundamental understanding of LLZO doping mechanisms but also offer practical insights into tailoring solid electrolytes for high-performance lithium-ion batteries.

This work has been financed by National Science Centre, UMO-2019/33/B/ST5/02134.
Interface Properties of Artificial Solid Electrolyte Layer on Li-Metal Anode for Quasi-Solid-State Battery
Authors: Kim Daeil , Jang Boyun , Han Byeol , Joo Junwoo , Kim Joon-soo
Published: December 2024

Lithium (Li)-metal anodes have received much attention because of their high theoretical specific capacity of 3,800 mAh/g and low density of 0.53 g/cm3. However, the high reactivity, which is a disadvantage of Li-metal anodes, causes unwanted Li-dendrites to grow and an unstable SEI layer to form on the Li-metal surface. Due to this phenomenon, it is difficult to develop Li-ion batteries using Li-metal anodes. To solve this problem, an artificial SEI (Solid Electrolyte Interface) layer mainly containing LiF was formed on the Li-metal foil using an existing electrochemical process before applying it to cell assembly. The properties of this artificial SEI were strongly dependent on electrochemical process conditions such as voltage ranges and time. Additionally, the interface properties between a quasi-solid electrolyte, one of the promising next-generation electrolytes, and a Li -metal anode were also investigated. To artificially form LiF, a gel-type electrolyte was prepared with various amount of FEC (Fluoroethylene carbonate) additive, and a LiF film was formed on the surface of Li-metal through the CV (Cyclic Voltammetry) process with various voltage ranges and scan rates. To study microstructure of artificial SEI layers, XRD, EDX, and XPS analysis were performed, and it was confirmed that LiF was uniformly distributed on the lithium metal surface after the process. To investigate the interface properties, EIS (Electrochemical Impedance Spectroscopy) before and after the CV process was obtained, and their interfacial resistance were precisely analyzed with various process conditions. Finally, with gel polymer, a polarization test under symmetrical cell conditions and cell performance with Ni-rich cathodes were measured to evaluate the performance of the artificial SEI layer on Li-metal anode. Li-metal with artificial SEI shows stable polarization behaviors for longer than 200 hrs at a current density of 0.2 mAh/cm2. All the results show that the semi-solid-state Li-metal battery with the artificial SEI layer has excellent cycle performances for the next generation Li-ion battery to guarantee the safety.
Design of Composite Cathode Electrodes for All-Solid-State Batteries
Authors: Kim Dong-Gyu , Kim Hyun-Kyung
Published: December 2024

Li-ion batteries (LIBs) have high energy density and long-cycle energy storage; hence, they are widely used as power sources in electric devices. However, safety remains a major issue. Conventional LIBs developed using organic, liquid electrolytes may exhibit issues such as combustion and explosion. To address these issues, all-solid-state batteries (ASSBs) are considered promising candidates for advanced LIBs, offering high electrochemical stability and excellent safety owing to the non-flammability of the intrinsic inorganic solid electrolyte used1. The deployment of solid-state electrolytes (SSEs) into all-solid-state Li batteries is a promising approach due to the non-flammability and compatibility of SSEs with Li metal; thus, they have the potential to meet the increasing demands for high energy density and enhanced safety. Among the various SSEs, Li7La3Zr2O12 (LLZO) can be doped with Al, Ga, Ta, etc., to stabilize its cubic structure. LLZO exhibits high ionic conductivities (in the range of 10−4–10−3 S·cm−1), a wide operating voltage window, and excellent elastic and shear moduli. However, all ASSBs have solid-state electrode structures consisting solely of solid materials. As a result, Li-ion diffusion primarily occurs at the interfaces between the cathode-active material and solid electrolyte. Composite cathodes within ASSBs often exhibit numerous voids and high interfacial resistance. The limited ion conduction paths have constrained the electrochemical performance of ASSBs because of the inadequate contact areas between the active materials and solid electrolytes in the composite cathode2. To improve the electrochemical performance of ASSBs, some design issues of the composite cathode electrode need to be solved.

The aim of this study is to enhance the performance of ASSBs using a bimodal garnet-type solid electrolyte, Li7La3Zr2O12 (LLZO), composed of electrolytes of two different sizes. The bimodal electrolyte composite cathode exhibits a higher density and fewer voids compared to the monomodal electrolyte, as the small powder particles fill the voids between the large ones.3 Finally, ASSBs prepared using the bimodal electrolyte achieve a low interface resistance and a large contact area between the solid electrolyte and the cathode material, resulting in enhanced electrochemical performance. Further details regarding the electrochemical and structural properties will be presented in the meeting.
Low-Cost Synthesis of Garnet-Type Electrolytes through the Study of Formation Mechanism
Authors: Garman Kaitlin , Thomas Charlotte Michele , Wang Yangyang , Ban Chunmei
Published: December 2024

Li7La3Zr2O12 (LLZO) has emerged as a highly promising solid-state electrolyte material in recent years, with researchers exploring its potential for use in all-solid-state batteries (ASSBs) that offer safe, scalable, and high-energy-density energy storage solutions. By replacing conventional liquid electrolytes with a solid-state electrolyte such as LLZO, ASSBs can overcome the limitations of traditional batteries, such as the risks of leakage and flammability. LLZO is mainly synthesized through solid-state methods, but the reaction pathway remains poorly understood. This work will discuss the formation mechanism of LLZO during the course of a conventional solid-state synthesis, in order to suggest an optimized synthesis with reduced synthesis time and temperature. This work utilizes a combination of operando and ex-situ X-ray diffraction (XRD) to track the formation of the intermediate phases during the reaction. By using the various ratios of precursors, our research investigated the role of lithium-containing precursors in forming the LLZO compound. Results suggest that LLZO starts forming at a temperature as low as 450 °C, and commonly found impurities such as La2Zr2O7 and La2O3 form later as Li-deficient phases as lithium becomes volatile. Additionally, the poster will discuss the impact of synthesis and sintering processes on electrochemical properties. We believe that these findings indicate a possibility of a simple solid-state reaction that could be performed at much lower temperatures, leading to a significant reduction in cost and making advanced ASSBs more accessible for large-scale production.
Electrochemical Properties of Garnet-Type Ta and Ga Co-Doped Li7La3Zr2O12 for Solid-State Li Batteries
Authors: Inada Ryoji , Hori Akio , Muramoto Yuta , Tojo Tomohiro
Published: December 2024

Li-stuffed garnet-type oxide Li7La3Zr2O12 (LLZ) has attracted much attention because of the high ionic conductivity at room temperature, excellent thermal performance, and good chemical stability against Li metal.1,2 However, poor interfacial connection causes non-uniform Li plating and intergranular penetration of Li dendrite in polycrystalline LLZ when the cell is cycled particularly at high current densities, resulting in internal short-circuit failure.3,4 The tolerance for Li dendrite growth into LLZ is influenced by many factors such as the interfacial resistance between LLZ and Li anode, cell stacking pressure and microstructure (density and grain size) of LLZ. In this study, we fabricated Ga and Ta co-doped LLZ (Li6.55-3xGaxLa3Zr1.55Ta0.45O12, LGLZT) ceramic electrolyte and investigated the effects on the Ga amounts on the microstructure, ionic conductivity, and the tolerance for Li dendrite growth.

LGLZT with Ga amounts x = 0.025, 0.05 and 0.10 were synthesized via a conventional solid-state reaction process. Sintering condition was set to 1150 °C for 2 hours in air. Relative densities for all sintered samples were ranged from 93-95 %. From XRD analysis, each sintered sample has a cubic garnet phase and diffraction peaks from other phases were not detected. Calculated lattice parameter was decreased with increasing Ga amounts x, due to the Ga3+ incorporation in the crystal lattice. In SEM observation, microstructure of sintered LGLZT was strongly influenced by x, because the amounts of liquid Li-Ga-O phase formed during high temperature sintering is also changed by x.5,6 When x increases, grain growth in sintered LGLZT is promoted and the segregation for Ga and O elements becomes more remarkable. Ionic conductivity of LGLZT at room temperature also enhanced with x, and maximum value of 0.84 mS/cm, which is much superior to the value for the sample without Ga (= 0.64 mS/cm). The effect of Ga amounts in LGLZT on the tolerance for Li dendrite growth will be discussed in the presentation.

This work was supported by Grant-in-Aid for Scientific Research (JSPS KAKENHI) Grant Number 22H01468 from the Japan Society for the promotion of Science (JSPS).

References

R. Murugan et al., Angew. Chem., Int. Ed. 46, 7778−7781 (2007).

A.J. Samson et al., Energy Environ. Sci. 12, 2957−2975 (2019).

R. Inada et al., Batteries 4, 26 (2018).

Y. Matsuki et al., J. Electrochem. Soc. 166, A5470−A5473 (2019)

Y. Matsuda et al., Solid State Ionics 311, 69−74 (2017).

Y. Yamazaki et al., Batteries 8, 158 (2022).
Digital-Twin Sulfide-Based Semi-Solid-State Batteries: Unveiling Structural and Electrochemical Properties
Authors: Lee Hyobin , Lee Jongjun , Lim Jaejin , Kim Suhwan , Oh Kyeong-Seok , Kim Won-Yeong , Ryu Seokhyeon , Lee Sang-Young , Lee Yong Min
Published: December 2024

Solid-state batteries incorporating sulfide electrolytes with high ionic conductivity and good deformability are widely researched due to excellent safety and theoretically high energy density. However, achieving performance comparable to lithium-ion batteries remains challenging due to inherent limitations such as inevitable pores and poor interparticle connections within electrodes. In this study, through multiscale digital-twin simulations, we demonstrated the superiority of sulfide-based semi-solid-state batteries with enhanced ion pathways and interparticle connectivity by injecting liquid electrolyte. Multidimensional structures were created based on actual cross-sectional SEM images of sulfide-based electrodes and electrolytes, allowing in-situ visualization and quantification of lithium concentration, current density, overpotential, and dendrite growth that are difficult to analyze through experiments alone. Digital-twin simulation not only shed light on veiled properties, but also provides insights into the future development directions of semi-solid-state batteries.
A Comparative Safety Analysis of Lithium-Ion and Solid-State Lithium-Metal Pouch Cells
Authors: Fakkema Jonathan , Sapra Harsh , Kazyak Eric
Published: December 2024

Solid-state batteries (SSBs) have become a promising candidate for the next step in lithium battery evolution. SSBs have the potential to provide larger gravimetric and volumetric energy densities, while many researchers believe they will also have an intrinsically higher safety profile. SSBs may not pose the same fire risk as conventional lithium-ion batteries (LiBs) since they lack a flammable liquid electrolyte [1]. However, recent developments have called this common belief into question. Not only do solid-state electrolytes (SSEs) fail to prevent lithium filaments from propagating and causing short-circuit events, but the higher energy density and presence of metallic lithium in SSBs create unique avenues for thermal runaway compared to LiBs [2-3]. Furthermore, there exists no comprehensive assessment of the overall safety of SSBs relative to current LiB technology.

This work presents an analysis of the comparative safety profiles of LiBs and SSBs. Thermal and mechanical testing is performed on full pouch cells with an industry-relevant combination of Li7La3Zr2O12 garnet-type SSE and gel-polymer catholyte. Time-synchronized captures of open-circuit voltage, surface and gas temperatures, gas species compositions, and high-speed imaging provide quantifiable metrics to compare the safety of SSBs against LiBs under identical conditions. Parameters such as heat generation rate, maximum temperature, and gas evolution are reported.

References:

[1] A. Manthiram, X. Yu, S. Wang, Lithium Battery Chemistries Enabled by Solid-State Electrolytes, Nature Reviews Materials, 2 (2017) 16103.

[2] J. Sastre et al., Blocking Lithium Dendrite Growth in Solid-State Batteries with an Ultrathin Amorphous Li-La-Zr-O Solid Electrolyte, Communications Materials, 2 (2021) 76.

[3] T. Inoue, K. Mukai, Are All-Solid-State Lithium-Ion Batteries Really Safe? – Verification by Differential Scanning Calorimetry with an All-Inclusive Microcell, ACS Appl. Mater. Interfaces, 9, 2 (2017) 1507-1515.
(Invited) Enhancing Electrochemical Performance of Fe-Mn Based Na Layered Oxides through Li Substitution: A Synchrotron X-Ray Analytical Study
Authors: Jung Young Hwa
Published: December 2024

Na-ion batteries, with their lower cost and earth abundance, are being actively researched for large-scale applications due to their similar intercalation chemistry to Li-ion batteries. The development of positive electrode materials is an important theme for achieving high-performance Na-ion batteries. Among these, Na layered materials have been studied for several decades, showing diverse crystal structures and high capacities. This presentation reports on the enhanced electrochemical performance achieved by substituting Li in the representative O3 and P2 structures of Fe-Mn based Na layered materials. Analysis of the crystal structure of materials, combining synchrotron X-ray diffraction and neutron diffraction techniques, revealed that Li can be located at the alkali site or transition metal site in the layered structure, depending on the composition of transition metals and the amount of Na. The redox behaviors of transition metals by Li substitution was also investigated using synchrotron X-ray absorption spectroscopy. The structural stability of Li-substituted layered materials during desodiation/sodiation was confirmed through in situ synchrotron X-ray diffraction analysis. Lastly, the improvements in electrochemical performance and structural stability were attributed to changes in Na ion diffusion behavior and honeycomb ordering, as elucidated by density functional theory calculations. These results indicate that Li substitution combined with appropriate structural design is a highly effective strategy for obtaining electrochemically stable electrode materials with layered structures for Na-ion batteries.
Fluoride-Ion Migration Mechanism in Fluoride Battery Electrolyte Material Cs2RbBiF6 with Double-Perovskite Structure
Authors: Moriwake Hiroki , Ogawa Takafumi , Kuwabara Akihide , Ikuhara Yuichi , Niwa Eiki , Sakakibara Kou , Mori Daisuke
Published: December 2024

Recently, fluoride-ion batteries have been extensively studied for next-generation rechargeable batteries. In this battery system, fluoride-ion electrolyte material with high fluoride-ion conduction is strongly desired. A limited number of the fluoride-ion electrolyte material were reported. Most of them have Fluorite structure or Tysonite structure and their related crystal structures. If we have new fluoride-ion electrolyte material in another crystal structure, we can expand our choice of material. In this study, we carried out theoretical studies using first-principles static and dynamic calculations for fluoride battery electrolyte material Cs2RbBiF6 with double-perovskite structure. first-principles static and dynamic calculations in this study were performed by projector augmented wave (PAW) methods based on density functional theory (DFT). The generalized gradient approximations parameterized for the solid system (GGA-PBE_sol) were used. Our calculations revealed this material, Cs2RbBiF6 consists of strong covalent bonding BiF6 octahedron and ionic Cs-F bonding. Phonon calculations showed instability of BiF6 octahedron rotations. This indicates that BiF6 octahedron rotations can occur in elevated temperature regions. The fluoride-ion conduction behavior was studied by first-principles molecular dynamics calculations. The fluoride-ion conduction trajectory recorded at 600 K is shown in Fig. 1. In this figure, fluoride-ion mainly migrates around the BiF6 octahedron. On the other hand, fluoride-ion mainly migrations between BiF6 octahedrons were not so often observed. Migration energies were determined using the nudged elastic band (NEB) method and were evaluated to be 0.089 eV for the path within the BiF6 octahedron and 0.212 eV for the path between BiF6 octahedron. Our calculation results indicate the potential of high fluoride-ion conduction of these materials.

Acknowledgments: This work was supported by the RISING3 (JPNP21006) projects from the New Energy and Industrial Technology Development Organization (NEDO), Japan.

Figure 1
State-of-the-Art Na-Ion Batteries: Electrolyte Approach to Address the Issues of Cycle-Life
Authors: LE Phung M-L , Tran Thanh-Nhan , Le Minh-Kha
Published: December 2024

With a worldwide trend towards the efficient use of renewable energies, the electricity supply sector has a pressing need for inexpensive energy storage. Sodium-ion batteries (NIBs) are an emerging battery technology with promising cost, safety, sustainability, and performance advantages over current commercialized lithium-ion batteries. Therefore, NIBs are attractive prospects for stationary storage application (utility scale and behind-the-meter), and transportation applications where energy density is less critical, and lifetime operational cost is the overriding factor.

Sodium-ion batteries have similar architecture/construction as state-of-the-art Li-ion batteries and can be a drop-in to the existing manufacturing infrastructure. The abundance of sodium alleviates some of the critical materials supply chains issues associated with lithium. Gravimetric energy densities are reported in the range of 100-200 Wh/kg making them a potential complementary/substitutional technology to lithium iron phosphate-based batteries. Sodium-ion batteries operate in a similar temperature regime as lithium-ion technologies but can be shipped uncharged (0% state of charge) for improved safety. However, before commercializing NIBs, R&D activities must be focusing on cost reduce by: (1) improving technical performance (increasing cycle life and energy density); (2) Establishing supply chains; (3) achieving economies of scales. Recently, some commercialization efforts have been demonstrating in pouch cells, 18650 cells, and/or modules showing very promising data, such as: Natron (US/Prussian blue), Faradion (UK/Layered Oxide), TIAMAT(FR/polyanionic), CATL (CN/Layered Oxide), and HiNa (CN/Layered Oxide).

Improving the lifespan as well as energy density of the NIB is one of main targets to support for the deployment if NIBs at scale in various market. In PNNL, we have been developing some advanced electrolytes which are nonflammable and help to resolve the issue of battery cycle life through enhancing/stabilizing the interfacial reaction and preventing the materials failure during long-term operation. In addition, the fundamental aspects and deep exploring on reaction kinetic helps to unveiling the mysteries of the battery degradation and operation failure.
Analysis of Commercial Na-Ion 18650 Cell Performance: Cell-to-Cell Variation and Long-Term Cycling
Authors: Wittman Reed M , Dubarry Matthieu , Rich Chaz , Langendorf Jill , Bates Alex Martin
Published: December 2024

The development of commercial Na-ion battery cells for various energy storage applications has ramped up rapidly in the last three years. Currently, 18650 format cells from several manufacturers have been released for purchase through wholesalers, indicating that Na-ion cells may soon be ready for adoption into the grid, electric vehicles, and various consumer electronics. The promise of Na-ion is lower cost and only moderately reduced power and energy density compared to Li-ion cells. Thus, they may work as a drop-in replacement for Li-ion technologies depending on the use case.

To be adopted for a wide range of energy storage applications, the commercial cell performance needs to be evaluated under a variety of conditions. Sandia National Labs has embarked on a long-term cycling study of Na-ion cells from two different manufacturers to help fill the gaps in performance evaluation. This study covers variations in performance based on temperature, state of charge, cycling rate, and various simulated duty cycles. Initial results from the first few months of testing of these new cells will be presented.

In addition to the long-term cycling study, we conducted materials characterization and cell-to-cell cycling variance analysis. This is to understand the fundamentals of the battery mechanics, operation, and manufacturing quality. Initial results showed that the two manufacturers are using similar electrode chemistries, with a positive electrode active material that is likely a sodium iron manganese nickel oxide (Na(FexMnyNiz)O) and a negative electrode that is composed of hard carbon. During initial cell variance analysis, we observed that the different manufacturers are producing cells with similar performance, with incremental capacity curves that match each other in feature location and amplitude. Manufacturer A’s cells have about 10% more capacity than manufacturer B’s cells, which is likely a product of cycling to a voltage limit 100 mV higher than manufacturer B’s. Both manufacturers have cell-to-cell variance of capacity of less than 1% which matches what is observed in Li-ion cell production. We will also detail more analysis of cell variations like temperature and rate-based capacity variations as well as internal resistance values, electrochemical impedance spectrums and voltage relaxation times.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
Polysaccharide-Based Hydrogel Electrolyte Membranes for Quasi-Solid-State Rechargeable Alkaline Zinc Batteries
Authors: Inoue Hiroshi , Chiku Masanobu , Higuchi Eiji , Zhen Cheng
Published: December 2024

Introduction

Rechargeable zinc battery is a promising energy device because of its advantages such as high safety, low cost, environmental friendliness etc. However, the reduction in discharge capacity due to hydrogen evolution reaction and short circuits caused by dendrite growth during charging hinder the practical application of rechargeable zinc battery. We have demonstrated the effectiveness of crosslinked polyacrylate-based hydrogel electrolytes (HEs) as an alternative to aqueous alkaline solutions to improve these issues.1 We have recently become interested in physical gels in which the host polymer is cross-linked by intermolecular interactions such as hydrogen bonding and ionic bonding, and prepared new HEs by mixing xanthan gum (XG), one of polysaccharides, as host polymer and aqueous KOH solutions. The XG-based HEs showed ionic conductivity comparable to the corresponding alkaline aqueous solutions. However, we have not succeeded in producing self-standing XG-based HE membranes under alkaline conditions yet. In this study, we have used another polysaccharide, starch, to prepare and characterize self-standing HE membranes under alkaline conditions. Moreover, we fabricated quasi-solid-state Zn/HE/positive electrode cell and evaluated charge-discharge performances.

Experimental

Commercial starch powder was mixed with (4 M KOH-0.3 M ZnO) aqueous solution with stirring to obtain a homogeneous sol, and then dried to prepare starch-based HE. The prepared starch-based HE membrane was soaked in the electrolyte solution before fabricating cells.

Results and Discussion

The photos of prepared starch-based HE membrane are shown in Fig. 1. As can be seen from these figures, the HE membrane was able to stretch and contract without tearing, suggesting that it exhibited high physical strength. The ionic conductivity of the HE membrane was a little lower than that of electrolyte solution. Using a Cu/HE membrane/Zn cell, the redox waves due to Zn deposition/dissolution at a Cu electrode were observed by cyclic voltammetry. Charge-discharge measurements using a Zn/HE membrane/Zn symmetrical cell showed an overpotential of about 50 mV for Zn deposition/dissolution, which was almost the same as a cell using a (4 M KOH-0.3 M ZnO) aqueous solution. In charge-discharge test using a γ-MnO2/HE membrane/Zn cell at 2 C-rate between 0.8 and 1.8 V, the initial discharge capacity was 253 mAh g-1, which was ca. 82 % of the theoretical capacity. However, the discharge capacity decreased to ca. 70 mAh g-1 by the 50th cycle.

This work is based on results obtained from a project, JPNP21006, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

Reference

C. Iwakura, H. Murakami, S. Nohara, N. Furukawa, H. Inoue, J. Power Sources, 152, 291 (2005).

Figure 1
Ultrasmall α-MnO2 Cathodes for Multivalent Rechargeable Batteries
Authors: Iimura Reona , Kobayashi Hiroaki , Kawasaki Shiori , Mandai Toshihiko , Kisu Kazuaki , Orimo Shin-ichi , Yamaguchi Kazuya , Ichitsubo Tetsu , Honma Itaru
Published: December 2024

The energy density of lithium-ion batteries (LIBs), widely used today, is nearing its theoretical limits. This situation calls for a significant advancement in battery performance to meet the demands of an increasingly electrified society, which includes applications like electric vehicles and smart grids. Moreover, given the unstable global conditions, there is a growing demand for the creation of batteries with minimal susceptibility to price fluctuations. Multivalent rechargeable batteries, utilizing elements such as Mg, Ca, and Zn, emerge as promising alternatives to LIBs due to their cost-effectiveness, enhanced safety features, and higher volumetric energy density. However, despite their potential, designing cathode materials that balance high energy and high-rate capabilities remains challenging. Oxide-based cathodes have garnered attention for their ability to offer higher voltage operational capacities. Nevertheless, many cathodes materials face room-temperature capability issues, particularly in Mg and Ca battery cells, owing to sluggish multivalent cation diffusion rates.

In this work, we successfully synthesized ultrasmall α-MnO2 ( < 10 nm ) by newly developed alcohol reflux process as a common cathode material. Compared with α-MnO2 cathode synthesized by conventional hydrothermal method, the incorporation of ultrasmall α-MnO2 significantly enhanced the performance of all battery systems such as rate capabilities and reversibility. These findings open new avenues for the development of next-generation rechargeable battery cathode.
Promoting Homogeneous Zinc-Ion Transfer through Preferential Ion Coordination Effect in Gel Electrolyte for Stable Zinc Metal Batteries
Authors: Lee Sangyeop , Han Im Kyung , Kim Youn Soo , Park Soojin
Published: December 2024

In an era increasingly defined by climate change, the shift towards sustainable energy solutions has become a critical global imperative. This shift underscores the importance of developing eco-friendly electricity sources as viable alternatives to fossil fuels, addressing both environmental concerns and the issues of intermittency and instability that plague renewable energy sources. Electrochemical energy storage, exemplified by rechargeable batteries, has emerged as a key technology in this context, offering a means to store renewable energy efficiently. Notably, lithium-ion batteries (LIBs) have dominated the field due to their high energy density and application versatility. However, the safety risks associated with LIBs, particularly those related to thermal runaway, have prompted the search for safer alternatives.

Water-based aqueous batteries, and specifically aqueous zinc (Zn) metal batteries (AZMBs), have been identified as promising candidates in this regard. AZMBs, leveraging the advantages of zinc as an anode material and Zn2+ ions for charge transfer, offer a blend of high energy density, low environmental impact, and inherent safety. Yet, the commercial adoption of AZMBs faces challenges, notably the dendritic growth on zinc anodes during charge/discharge cycles, which undermines battery performance and safety.

Addressing this challenge, our research focuses on sulfobetaine methacrylate (SBMA) as a repeating unit for the zwitterionic polymer matrix and examine the improvement of anode reversibility through preferential ion coordination behavior. The abundant polar groups in SBMA interact favorably with internal ions and influence charge carrier migration during cell operation. Using two-dimensional (2D) correlation spectroscopy in conjunction with Raman spectroscopy, it has been found that the interaction priority order of SO3
- functional groups increases when the concentration of ZnSO4 salt in the gel electrolyte rises from 2 m (mol·kg-1) to 5 m. Preferential coordination stimulates the uniform distribution of Zn2+ ions within the structure and alleviate the tip effect, contributing to improved stability during electrodeposition. Additionally, the combined effect of a zwitterionic gel and an electrostatic interaction hinders the 2D diffusion of Zn atoms on the anode surface and enables a dendrite-free electrode morphology accordingly. As a result, a zwitterionic gel polymer electrolyte (ZGPE) with 5 m ZnSO4 supports durable aqueous zinc metal batteries through uniform Zn plating/stripping behavior, as demonstrated by long-term symmetrical cell results (>3600 h cycle life at an areal capacity of 0.5 mAh·cm-2 and a current density of 0.5 mA·cm-2). The feasibility of the proposed system was further validated by Zn|Zn0.25V2O5 full cells, which exhibited excellent cyclability as preferential ion coordination retains the anode sustainability and prevents performance degradation.
Probing Self-Discharge Behavior of Graphitic Cathodes for Rechargeable Aluminum Batteries
Authors: Li Chi , Patra Jagabandhu , Chang Jeng-Kuei
Published: December 2024

The self-discharge loss of rechargeable aluminum batteries (RABs) is much higher than that of Li-ion batteries. Therefore, this is a critical issue that hinders the applications of RABs. Self-discharge results in a spontaneous reduction in the electrical energy stored when a battery rests in an open-circuit condition. The self-discharge problem of RABs is often overlooked, and the self-discharge behavior and mechanism have not been fully investigated. In this work, the self-discharge properties of two commonly used RAB electrodes, natural graphite and expanded graphite, are for the first time characterized in detail. Synchrotron operando X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy mapping are employed to explore the self-discharge mechanism. In addition, the effects of the lattice size and surface area of the electrode materials on the self-discharge rate and those of the charging rate, depth of charge, and electrolyte composition on the self-discharge properties are systematically studied.
VO2 Polymorphic Cathodes and Dual-Salt Aqueous Electrolyte for Zn-Ion Batteries
Authors: Rath Purna Chandra , Teng Li-Tao , Chang Jeng-Kuei
Published: December 2024

Three VO2 polymorphic cathodes, namely monoclinic VO2 (B), monoclinic VO2 (M), and tetragonal VO2 (A), are synthesized and their morphologies and electrochemical performances are examined for Zn-ion battery (ZIB) applications. It is found that VO2 (B) outperforms VO2 (M) and VO2 (A) in terms of the specific capacity and rate capability due to its relatively large number of charge storage sites, high electronic conductivity, and wide structural tunnels that can facilitate Zn2+ transport. Further, a cost-effective ZnSO4-based aqueous electrolyte with various LiTFSI concentrations (3−7 m) is formulated. To obtain superior Zn//VO2 battery performance, the optimal ZnSO4/LiTFSI ratio in the electrolyte is explored. Wide-angle X-ray scattering (WAXS) is used to examine the solvation structures of various electrolytes to find the correlation between the solution coordination status and electrolyte properties (such as the electrochemical potential window, ionic conductivity, and Zn(OH)2)3(ZnSO4)·xH2O byproduct formation tendency). According to the WAXS data, the incorporation of LiTFSI greatly alters the solution structures and 1 m ZnSO4/5 m LiTFSI electrolyte has reduced water activity. Thus, the anodic limit (that related to oxygen evolution from the decomposition of water) of the electrolyte is extended, and the Zn(OH)2)3(ZnSO4)·xH2O byproduct formation tendency is suppressed. The thinner byproduct layer, which reduces the blocking of ion/proton intercalation reactions, is responsible for the superior charge-discharge properties of the VO2 (B) electrode obtained in the 1 m ZnSO4/5 m LiTFSI dual-salt electrolyte. The unique solution structure of this electrolyte also alleviates the hydrogen evolution side reaction, leads to the flat and compact Zn deposits, and reduces the amount of dead Zn on the electrode after cycling. The VO2 (B) electrode has great dimensional reversibility and stability during cycling in the 1 m ZnSO4/5 m LiTFSI electrolyte, as verified via operando transmission X-ray microscopy (TXM). The proposed electrode/electrolyte design strategies are expected to be applicable for further development of ZIBs.
Water Content Gradient Electrolyte for Highly Stable Aqueous Zinc Metal Batteries
Authors: Wang Ziqing , Mullins Charles Buddie
Published: December 2024

Recent interest focuses on aqueous zinc metal batteries (AZMBs) for large-scale energy storage systems due to their affordability and safety.1 However, the dendrite growth and parasitic reactions on the Zn anode and the dissolution on the cathode harm the sustainability of AZMBs.2 Several strategies have been proposed to stabilize zinc anode and protect oxide-based cathodes by decreasing the water content in the electrolytes.3-5 However, the actual performance of these low water-content electrolytes is unsatisfactory because of their high viscosity and low ionic conductivity. In contrast, high water-content electrolytes (i.e., conventional aqueous electrolytes) provide promising physicochemical properties, whereas water decomposition on the electrode surface is inevitable, further negatively impacting electrochemical performance. In this study, we design a unique gradient electrolyte where a water content gradient is achieved from electrode to separator. Specifically, a molecular crowding electrolyte with less water content and suppressed water activity is coated on the electrode surface, and a conventional aqueous electrolyte with high water content is dropped on the separator. By assembling the battery, the MCE on both electrodes and the AqE on the separator form a sandwich-like gradient electrolyte (GE). Due to the AqE in between, the ionic conductivity within GE is significantly improved than MCE. Meanwhile, the MCE on the electrode surface regulates uniform zinc deposition and reduces parasitic reactions related to water decomposition. As a result, the highly reversible zinc plating/stripping occurs in Zn/Cu asymmetric cells with an average Coulombic efficiency of 99.1% for over 1000 cycles. Moreover, the Zn/Zn symmetric cells can stably cycle with reduced overpotential than MCE for over 1000 hours at different current densities. Full cell batteries employing MnO2 exhibit excellent capacity retention after 1000 cycles at 2 A g–1 due to the suppressed cathodic dissolution. This gradient electrolyte offers a facile strategy to protect electrodes and prevent side reactions without sacrificing ionic conductivity and viscosity.

References:

1. F. Wan et al. ACS Energy Lett.
2020, 5 (11), 3569-3590.

2. M. Zhang et al. Adv. Energy Mater.
2024, 14 (9), 2303737.

3. H. Ren et al. Adv. Mater.
2023, 35 (1), 2208237.

4. L. Qian et al. Adv. Funct. Mater.
2023, 33 (23), 2301118.

5. Y. Zhong et al. Angew. Chem. Int. Ed.
2023, 62 (40), e202310577.

Figure 1