bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Kinetic Origins of Voltage Relaxation and Low-Frequency EIS Measurements in Porous Electrodes
Authors: Kapate Nidhi , Kang Stephen D. , Kuo Jimmy J. , Zhao Hongbo , Chueh William C. 
Published: December 2024

Overpotentials in porous electrodes lead to undesirable behavior during battery cycling and understanding the origins of these overpotentials is crucial. In Li-ion batteries, a significant fraction of the electrode overpotentials in layered cathodes like NMC's arise from low-frequency sources. These low-frequency overpotential sources and the impedances they lead to are traditionally analyzed in the time domain using galvanostatic intermittent titration technique (GITT) or the frequency domain using electrochemical impedance spectroscopy (EIS). Currently in the standard porous electrode model, solid-state diffusion of Li in the cathode material is the only mechanism that is considered to lead to the electrochemical behavior seen at low frequencies and longer timescales. However, there are various experimental inconsistencies that emerge when attributing voltage relaxation behavior and low-frequency impedance behavior solely to solid-state Li diffusion. Thus, it is necessary to further investigate and understand the true nature of the impedances that arise in these timescale and frequency regimes.
In this work, we investigate the origins of the voltage relaxation behavior and low-frequency impedance in porous electrodes. Using a 3-electrode coin cell system, we vary the kinetics of the electrode/electrolyte interface by systematically changing the salt concentration of the electrolyte used. We perform GITT and EIS measurements and find that the relaxation behavior and low-frequency impedance changes as the kinetics of the electrode/electrolyte interface changes. These results contradict the experimental dependencies that are expected to arise from a system that is only diffusion controlled. Instead of a solid-state diffusion limitation, we propose an alternative mechanism that could also contribute to the observed GITT and EIS behavior: a distribution of reaction constants. We demonstrate the validity of this hypothesis with a multi-particle simulation. Furthermore, we characterize the hierarchical morphology of porous electrodes through particle physisorption and nano-computed tomography and investigate how their complex structures could lead to inherently broad distributions of electrochemical reaction times.

Figure 1
Understanding Temperature Effects in Silicon-Containing Lithium-Ion Batteries
Authors: Bae Ji-Youn , Yu Seung-Ho 
Published: December 2024

Silicon holds promise as a material for high-energy-density lithium-ion batteries (LIBs). Although graphite, commonly used in commercial LIBs, has excellent cycling stability, its energy density is limited by a specific capacity of only 372 mAh g-1. To address this limitation, silicon has garnered attention with its high specific capacity of 3,579 mAh g-1 and low operating voltage. Despite its advantages, silicon faces challenges such as significant volume changes during cycling and poor cyclability performance. One solution is to incorporate silicon into a graphite anode. However, many issues with silicon remain unresolved, particularly regarding cycle performance and aging under various temperature.
In this study, we investigate the effects of temperature on the phenomenon occurring in silicon/graphite composite anodes. Increasing the operating temperature significantly alters the cell performance. As temperature rises, not only does cycle performance deteriorate, but degradation due to self-discharge also intensifies. We observed differences in color change and open circuit voltage (OCV) of the composite anode due to the degradation using operando optical microscopy. Furthermore, we conducted energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis of the solid electrolyte interphase (SEI) component, confirming variations in composition and ratio depending on temperature. Additionally, we examined differences in degradation tendency at high temperatures based on the graphite-to-silicon ratio in the anode and the type of electrolyte additive.
A deeper understanding of the phenomena in graphite/silicon composite electrodes will aid in extending the lifespan of silicon-containing LIBs under real operating conditions.
Figure 1. Cycle performance of graphite/Si full cell cycled at high temperature with 1.0 M LiPF6 in EC/EMC with various additives

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Investigation of the Passivation Reaction of Li Metal in Liquid Electrolytes Using Microcalorimetry
Authors: Berg Sascha , Fonck Ferdinand , Figgemeier Egbert 
Published: December 2024

The demand for energy storages with high energy density and long lifetime is growing rapidly. Using lithium metal as an anode would maximize the energy density of lithium batteries by having an anode-free system in the discharged state. Lithium-ion batteries can undergo several thousand cycles using liquid electrolytes with low capacity losses and very low safety risks. Passivation of lithium metal and the uncontrolled formation of lithium dendrites has so far prevented the large-scale commercialization of lithium-metal batteries with liquid electrolytes. Understanding the passivation reactions and formation of the solid electrolyte interphase in of lithium metal in liquid electrolytes is crucial to increase the longevity and safety of this system. In this study, we present experimental results on the lithium metal liquid interfaces for next-generation lithium batteries utilizing isothermal microcalorimetry.
The experimental setup involved the investigation of coin cells at a symmetrical lithium metal cell and lithium-copper (Li-Cu) half-cell level. Two baseline electrolytes were employed, including a carbonate (EC:EMC 3:7 wt%, 1M LiPF6) and an ether-based- formulation (LiFSI:DME:TTE 1:1.2:3 molar), supplemented with fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives. Those coin cells were investigated at various current densities ranging from 0.5 to 5 mA/cm² at a constant cyclic capacity throughput of 5 mAh/cm².
Our results reveal insights into the thermodynamic behavior and stability of lithium metal interfaces in different electrolyte environments and for different current densities. The calorimetric measurements provide the additional information on the heat flow associated with plating and stripping processes, shedding light on the kinetics of lithium deposition and dissolution. Furthermore, we systematically investigated the influence of electrolyte composition, including the presence of FEC and VC additives, on the interfacial properties and passivation reactions of lithium metal. In symmetrical lithium metal cells, we observed distinct heat signatures corresponding to the coulombic efficiency (CE) in Li-Cu half cells. The addition of FEC and VC additives exhibited pronounced effects on the suppression of irreversible passivated lithium depositions and the enhancement of stability at high current rates.
Our results highlight the importance of electrolyte composition in the behavior of lithium metal/liquid electrolyte interfaces. The comprehensive understanding gained from these experiments provides a basis for testing new electrolyte compositions with additional insight over conventional testing methods.
(Invited) Long-Lifetime LiMnXFe1-XPO4/Graphite Cells Enabled By Advanced Electrolytes
Authors: Leslie Kate , Aishova Assylzat , Harlow Jessie , Rathore Divya , Tuul Kenneth , James Abraham Jeffin , Metzger Michael 
Published: December 2024

The increasing demand for clean energy storage and electric vehicles is highlighting the need to develop Li-ion battery materials with low cost and abundant elements.1
,
2 Positive electrode materials such as LiFePO4 (LFP) are good candidates to replace layered oxide materials due to the high relative abundance of Fe compared to other transition metals, such as Ni and Co.1 Unfortunately, LFP suffers from low energy density.2 LiMnxFe1-xPO4 (LMFP) has been proposed as an alternative to LFP. It shares the same crystal structure as LFP with a portion of Fe sites substituted with Mn. The Mn2+/3+ redox takes place at higher potential, improving the energy density.2

In this work, we set to decouple the contribution of the Fe and Mn to cell failure in order to better understand this class of olivine materials. LiMn0.8Fe0.2PO4/artificial graphite (AG) cells were cycled over varying voltage ranges to determine the capacity fade behaviour of each plateau, Fe (2.5-3.6 V) and Mn (3.6-4.2 V), as well as the full voltage range of the cell. The worst capacity fade was seen for cells cycled over the full voltage range, while very little capacity fade was seen for the Fe plateau and no capacity fade was seen for the Mn plateau, due to the Li reservoir from the negative electrode. In order to determine the capacity fade mechanism, differential voltage analysis was utilized.3 dV/dQ analysis shows no mass loss over any of the voltage ranges, large Li inventory loss for the full voltage range and Mn voltage region, and small Li inventory loss for the Fe region. X-ray fluorescence spectroscopy was used to determine the degree of Mn deposition on the negative electrode. The degree of Mn deposition was found to be well-correlated with the amount of Li inventory loss, demonstrating that the primary failure mode of LMFP/AG cells is Mn-catalyzed Li inventory loss. In order to fix that problem, we synthesized advanced LiMnxFe1-xPO4 with different values of x and optimized material properties. We also developed novel electrolytes that reduce Li inventory loss even at elevated temperature. Overall, our work shall enable long-lived LMFP/graphite cells for longer cost electric vehicles and stationary energy storage.
(1) Nitta, N.; Wu, F.; Lee, J. T.; Yushin, G. Li-Ion Battery Materials: Present and Future. Materials Today
2015, 18 (5), 252–264. https://doi.org/10.1016/j.mattod.2014.10.040.
(2) Ryu, H.-H.; Hohyun Sun, H.; Myung, S.-T.; S. Yoon, C.; Sun, Y.-K. Reducing Cobalt from Lithium-Ion Batteries for the Electric Vehicle Era. Energy & Environmental Science
2021, 14 (2), 844–852. https://doi.org/10.1039/D0EE03581E.
(3) Dahn, H. M.; Smith, A. J.; Burns, J. C.; Stevens, D. A.; Dahn, J. R. User-Friendly Differential Voltage Analysis Freeware for the Analysis of Degradation Mechanisms in Li-Ion Batteries. J. Electrochem. Soc.
2012, 159 (9), A1405. https://doi.org/10.1149/2.013209jes.
High-Capacity Fe-Rich Disordered Rock-Salt Li-Ion Cathode Materials Achieved via Redox Engineering
Authors: Fong Richie , Lee Jinhyuk 
Published: December 2024

The quest for sustainable and cost-effective energy storage solutions has led to the exploration of iron (Fe)-rich disordered rock-salt (DRX) cathode materials for lithium-ion batteries (LIBs).[1-3] This study presents an approach to redox engineering in Fe-rich DRX cathodes, demonstrating the reversible Fe2+/Fe3+ redox in a Fe2+-based DRX cathode.[3] The innovative design minimizes reliance on oxygen (O) redox, yielding a high capacity of approximately 290 mAh/g and an energy density of about 700 Wh/kg. These figures surpass the performance of Fe3+-based DRX cathodes, which operate on limited Fe3+/Fe4+ redox and extensive O redox upon cycling.
The research introduces Li1.2Fe2+
0.6Nb0.2O1.4F0.6 (LFNOF), a novel Fe2+-DRX cathode material, contrasting it with Li1.2Fe3+
0.6Nb0.2O2 (LFNO), a Fe3+-DRX counterpart. LFNOF’s design leverages partial fluorine substitution for oxygen, enabling ample Fe2+/Fe3+ capacity before the onset of Fe3+/Fe4+ or O redox processes. This strategy results in reduced voltage hysteresis and improved voltage and capacity retention, leading to more stable cycling performance than LFNO. The study combines experimental and computational approaches to elucidate the redox mechanisms of LFNO and LFNOF. X-ray Photoelectron Spectroscopy (XPS), Electron Paramagnetic Resonance (EPR) spectroscopy, X-ray diffraction (XRD), and Density-Function Theory (DFT) calculations collectively confirm the accessibility of Fe2+/Fe3+ redox in LFNOF, which delays and reduces the participation of O redox, contributing to the material’s enhanced stability. Furthermore, the research highlights the potential of Fe-rich DRX cathodes in addressing the global shift towards electric vehicles and large-scale energy storage. By reducing reliance on critical mineral supply chains and leveraging Fe abundance and affordability, Fe-rich cathodes such as LFNOF can significantly enhance the economic viability of LIBs. The findings suggest that redox engineering can play a pivotal role in developing low-cost, high-performing Fe-rich cathode materials, paving the way for more sustainable and resilient energy storage technologies.
This study not only provides a novel approach to designing Fe-rich DRX cathodes but also opens new avenues for further research in battery materials. The insights gained from LFNOF’s performance could inform future developments in LIB cathode design, potentially leading to the widespread adoption of Fe-rich cathodes in commercial applications.

References

[1] J. Lee et al., Science 2014, 343, 519.
[2] H. Li, R. Fong, J. Lee et al., Joule 2022, 6, 53.
[3] R. Fong, J. Lee et al., Advanced Energy Materials 2024, 10.1002/aenm.202400402.
Unraveling the Degradation Mechanisms in Composite Solid Polymer Electrolyte through in-Situ Impedance and Ex-Situ SEM
Authors: Rusly Cindy , Chen Hsun-Yi 
Published: December 2024

The increasing demand for batteries with higher energy density and enhanced safety has spurred the advancement of solid-state batteries (SSBs). While SSBs offer promising pathways to surmount the limitations of conventional batteries, their widespread adoption faces hurdles, notably due to the degradation mechanisms that impair their durability and efficacy. Among these, Li metal as anode materials acclaimed for its high energy density still encounter significant challenges related to safety and stability, primarily due to its reactive nature and formation of dendrites. Although solid-state electrolytes (SSEs) are expected to inhibit Li dendrite growth, issues with interface compatibility and dendrite penetration through SSEs remain critical barriers, underscoring the complex interplay of material properties that must be addressed to realize the full potential of SSB technologies. In this study, we delve into the failure mechanisms prevalent in SSBs by analyzing the morphology of SSEs and their interactions with electrode materials over successive cycling. Employing a combination of cycling tests, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS), we investigate the degradation patterns in lithium iron phosphate (LFP) electrodes, lithium metal, and SSEs.
The composite solid polymer electrolyte (CSPE) is synthesized by dissolving PVDF-HFP, PPC, and LiTFSi in DMF solvent, enriched with 10 wt% LLZO, and formed by slurry casting. Through our preliminary study, development of cracks in LFP electrodes was found mainly due to uneven Li stripping/plating. The aggregate formation of Li dendrite was also observed in the early charge/discharge cycles through ex-situ SEM. Significant increase in SSE porosity suggests Li formation and penetration into the CSPE for its low mechanical strength. The EDS analysis of CSPE at the end-of-life stage further reveals a notable shift towards carbon presence, likely indicating the formation of Li₂CO₃ after exposure of during transfer. This result signals high concentration of Li on the surface of CSPE. Further interphase information is revealed by analyzing the solid-electrolyte interphase (SEI) formation through in-situ impedance study. Our study offers critical insights into the mechanisms underlying the degradation of each component in the SSBs providing a foundational understanding necessary for the failure analysis of SSBs.
Strategies for Design and Synthesis Novel Sulfide-Type Na-Ion Conductors
Authors: Wang Hui , Guo Xiaolin , Halacoglu Selim 
Published: December 2024

Solid-state superionic conductors play a significant role to achieve the high potential of all-solid-state batteries with high energy density and enhanced safety. Sulfide-type solid electrolytes have attracted strong interest in the past decade due to their advantages of high ionic conductivity and favorable mechanical properties. The ion transport in sulfide-type solid electrolytes is influenced by several factors, including crystal structure, synthesis approach, annealing temperature, as well as chemical doping. Specifically, anion or cation doping may cause the crystal structure changes and thus affect the conductive properties of sulfide solid electrolytes.
In this talk, we will discuss the strategies and doping chemistry in Na3MCh4 (M: P or Sb; Ch: S or Se) family conductors. For these sulfide-type Na-ion conductors, different anion or cation dopants will be introduced, and the doping effects on the synthetic process, crystal structures, as well as ionic conductivity will be systematically discussed. Moreover, the isovalent and aniovalent dopants will be compared to understand the doping strategy to design and realizer highly conductive sulfide-type solid electrolytes for solid-state Na batteries.
Understanding Degradation Behavior in All-Solid-State Batteries through Scanning Spreading Resistance Microscopy
Authors: Gamo Hirotada , Maeda Yasushi , Kiyobayashi Tetsu , Siroma Zyun , Takeichi Nobuhiko , Sano Hikaru 
Published: December 2024

All-solid-state lithium-ion batteries (ASSLIBs) are promising candidates as the next generation battery because of inherently high safety and high energy density. The practical application of high-performance ASSLIBs is to be achieved by the development of solid electrolytes (SEs) with high ionic conductivity. So far, many SEs with high ionic conductivity over 10−3 S cm−1 have been discovered. However, ASSLIBs still face challenges arising from solid/solid interfaces. ASSLIBs using sulfide SEs involve chemical and mechanical degradations at the interface between cathode materials and solid electrolytes in cathode composites during the charge/discharge process. These degradations increase total resistance in ASSLIBs, leading to cycle deterioration. Therefore, understanding the degradation behavior is important for realizing long-life ASSLIBs. Scanning spreading resistance microscopy (SSRM) is a type of atomic force microscopy technique, which provides current distribution with high spatial resolution at the sample surface. An SSRM study by Otoyama et al. reported that a part of the cathode materials in the electrode shows insufficient electron conduction paths after the charging and involves high local resistance in the domains of the cathode materials.1 The local resistance analysis using SSRM is a useful technique for unveiling the degradation behavior in ASSLIBs.
Herein, we investigate the local resistance of cathode composites with LiNbO3-coated LiNi0.5Co0.2Mn0.3O2 (NCM) and argyrodite-type SEs for ASSLIBs after charging and elucidate the degradation behaviors through ex-situ SSRM. The local resistance analysis reveals the intrinsic resistance changes of NCM particles involving lithium deintercalation. Topography and local resistance mapping obtained by ex-situ SSRM study show that a part of NCM particles in cathode composites is electrically isolated after the charging to a high potential.2 Our work demonstrates that the ASSLIBs after the charging to a high potential cause mechanical degradation due to the volume change of NCM particles.

Acknowledgments

This study is based on the results obtained in the ‘Evaluation of All-Solid-State Battery Material and Foundational Technology Development for Next Generation (SOLiD-Next, JPNP23005)’ project, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

References

M. Otoyama et al., J. Phys. Chem. C,
125, 2841 (2021).

H. Gamo et al., J. Mater. Chem. A, submitted.
Degradation Analysis of Composite Electrodes for Sulfide-Based All-Solid-State Batteries during Long-Term Storage
Authors: Kang Junhee , Kim Beomsu , Yun Jonghyeok , Lee Jong-Won 
Published: December 2024

In the realm of energy storage technologies, lithium-ion batteries (LIBs) have marked a significant milestone, especially in powering portable electronic devices. Nonetheless, the quest for batteries with longer life spans and higher energy densities is ever-present, driven by the demand for more durable energy solutions (i.e., electric vehicles and energy storage systems). This pursuit, however, is challenged by the inherent limitations of LIBs including their capacity limit and the safety hazards posed by flammable liquid electrolytes. These issues have encouraged the exploration of next-generation energy storage solutions, and all-solid-state batteries (ASSBs) employing solid-state electrolytes (SEs) is regarded as one of the most prominent solutions, due to their potential for high safety and energy density.
Among the various SEs, sulfide-based ASSBs have emerged as leading contenders, owing to their high ionic conductivity and excellent processability. While significant attention has been dedicated to exploring electrochemical degradation at electrode interfaces by numerous studies, little has been investigated regarding durability of sulfide-based ASSBs after long-term storage under various conditions. Given that batteries inevitably undergo a storage period prior to dispatch after manufacturing, investigating the degradation mechanism during this phase and determining the ideal storage conditions are essential for ensuring the performance of ASSBs.
Herein, we investigate the degradation of Li6PS5Cl (LPSCl)-based composite cathodes employing conventional layered oxide cathodes during extended calendar aging under various states of charge (SOCs) and temperatures. Cells consisting of a composite cathode, LPSCl separator layer, and a Li-In alloy anode are fabricated. Following an initial pre-conditioning cycle of 0.1C, each cell is subjected to a two-week storage, showing a significant decline in discharge capacity compared to the fresh one. Notably, the cell stored at high-SOC and at an elevated temperature of 60°C exhibits extremely severe degradation after storage, underscoring the critical impact of aging conditions on battery longevity.
In-depth chemical and structural analyses, coupled with impedance decoupling, reveal that the storage at high-SOC facilitates detrimental interfacial side reactions between Ni-rich cathode material and LPSCl, which are accelerated at high temperatures. In addition to the oxidative decomposition of LPSCl, the irreversible phase transition of cathode active materials is also caused by calendar aging at high-SOC, as verified by the X-ray diffraction analysis and differential capacity curves. The resulting heterogeneity of the composite cathode also undermines the long-term cyclability of cells. These findings offer a deeper understanding of the performance decay of Ni-rich cathodes in sulfide-based ASSBs during storage and provides new guidelines for the development of cathode-compatible sulfide SEs.