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Lithium argyrodite-type electrolytes are regarded as promising electrolytes due to their high ionic conductivity and good processability. Chemical modifications to increase ionic conductivity have already been demonstrated, but the influence of these modifications on interfacial stability remains so far unknown. In this work, we study Li 6 PS 5 Cl and Li 5.5 PS 4.5 Cl 1.5 to investigate the influence of halogenation on the electrochemical decomposition of the solid electrolyte and the chemical degradation mechanism at the cathode interface in depth. Electrochemical measurements, gas analysis and time-of-flight secondary ion mass spectrometry indicate that the Li 5.5 PS 4.5 Cl 1.5 shows pronounced electrochemical decomposition at lower potentials. The chemical reaction at higher voltages leads to more gaseous degradation products, but a lower fraction of solid oxygenated phosphorous and sulfur species. This in turn leads to a decreased interfacial resistance and thus a higher cell performance.

All-inorganic solid-state batteries (SSBs) currently attract much attention as next-generation high-density energy-storage technology. However, to make SSBs competitive with conventional Li-ion batteries, several obstacles and challenges must be overcome, many of which are related to interface stability issues. Protective coatings can be applied to the electrode materials to mitigate side reactions with the solid electrolyte, with lithium transition metal oxides, such as LiNbO3 or Li2ZrO3, being well established in research. In addition, it has been recognized lately that carbonates incorporated into the coating may also positively affect the interface stability. In this work, we studied the effect that surface carbonates in case of Li2ZrO3-coated Li1+x(Ni0.6Co0.2Mn0.2)1-xO2 (NCM622) cathode material have on the cyclability of pellet stack SSB cells with Li6PS5Cl and Li4Ti5O12 as a solid electrolyte and an anode, respectively. Both carbonate-rich and carbonate-poor hybrid coatings were produced by altering the synthesis conditions. The best cycling performance was achieved for carbonate-deficient Li2ZrO3-coated NCM622 due to decreased degradation of the argyrodite solid electrolyte at the interfaces, as determined by ex situ X-ray photoelectron spectroscopy and in situ differential electrochemical mass spectrometry. The results emphasize the importance of tailoring the composition and nature of protective coatings to improve the cyclability of bulk SSBs.

Gas evolution in conventional lithium-ion batteries using Ni-rich layered oxide cathode materials presents a serious issue that is responsible for performance decay and safety concerns, among others. Recent findings revealed that gas evolution also occurred in bulk-type solid-state batteries. To further clarify the effect that the electrolyte has on gassing, we report in this work-to the best of our knowledge-the first study comparing gas evolution in lithium-ion batteries with NCM622 cathode material and different electrolyte types, specifically solid (β-Li3PS4 and Li6PS5Cl) versus liquid (LP57). Using isotopic labeling, acid titration, and in situ gas analysis, we show the presence of O2 and CO2 evolution in both systems, albeit with different cumulative amounts, and possible SO2 evolution for the lithium thiophosphate-based cells. Our results demonstrate the importance of considering gas evolution in solid-state batteries, especially the formation and release of highly corrosive SO2, due to side reactions with the electrolyte.

Lithium-thiophosphate-based all-solid-state batteries (ASSBs) are increasingly attracting attention for high-density electrochemical energy storage. In this work, the cycling performance of single and polycrystalline forms of LiNi$_{x}$Co$_{y}$Mn$_{z}$O$_{2}$ (NCM, with ≥83% Ni content) cathode active materials in ASSB cells with an Li$_{4}$Ti$_{5}$O$_{12}$ composite anode is explored, and the advantages and disadvantages of both morphologies are discussed. The virtual lack of grain boundaries in the quasi-single-crystalline material is found to contribute to improved stability by eliminating the tendency of Ni-rich NCM particles to crack during cycling, due to volume differences between the lithiated and delithiated phases. Although the higher crack resistance mitigates effects of chemical oxidation of the lithium thiophosphate solid electrolyte, the cells suffer from electrochemical side reactions occurring at the cathode interfaces. However, coating the single-crystal particles with a protective LiNbO$_{3}$ overlayer helps to stabilize the interface between cathode active material and solid electrolyte, leading to a capacity retention of 93% after 200 cycles (with q$_{dis}$ ≈ 160 mAh g$_{NCM}$$^{-1}$ or 1.7 mAh cm$^{-2}$ at C/5 rate and 45 °C). Overall, this work highlights the importance of addressing electro-chemo-mechanical phenomena in ASSB electrodes.

Solid-state batteries (SSBs) are a promising next step in electrochemical energy storage but are plagued by a number of problems. In this study, we demonstrate the recurring issue of mechanical degradation because of volume changes in layered Ni-rich oxide cathode materials in thiophosphate-based SSBs. Specifically, we explore superionic solid electrolytes (SEs) of different crystallinity, namely glassy 1.5Li2S-0.5P2S5-LiI and argyrodite Li6PS5Cl, with emphasis on how they affect the cyclability of slurry-cast cathodes with NCM622 (60% Ni) or NCM851005 (85% Ni). The application of a combination of ex situ and in situ analytical techniques helped to reveal the benefits of using a SE with a low Young’s modulus. Through a synergistic interplay of (electro)chemical and (chemo)mechanical effects, the glassy SE employed in this work was able to achieve robust and stable interfaces, enabling intimate contact with the cathode material while at the same time mitigating volume changes. Our results emphasize the importance of considering chemical, electrochemical, and mechanical properties to realize long-term cycling performance in high-loading SSBs.

Bulk-type solid-state batteries (SSBs) composed of lithium thiophosphate superionic solid electrolytes (SEs) and high-capacity cathode active materials (CAMs) have recently attracted much attention for their potential application in next-generation electrochemical energy storage. However, compatibility issues between the key components in this kind of battery system are difficult to overcome. Here, we report on a protective cathode coating that strongly reduces the prevalence of detrimental side reactions between CAM and SE during battery operation. This is demonstrated using preformed HfO

Lithium‐ion batteries (LIBs), which utilize a liquid electrolyte, have established prominence among energy storage devices by offering unparalleled energy and power densities coupled with reliable electrochemical behavior. The development of solid‐state batteries (SSBs), utilizing a solid electrolyte layer for ionic conduction between the electrodes, could potentially offer further performance improvements in key areas such as energy density and safety. However, to date, SSBs remain unable to match the performance of their liquid counterparts. In light of renewed interest in accelerating the development of alternative energy storage devices, herein, a current overview of operando characterization techniques applied to solid‐state cells and related experimental setups is presented. Operando techniques, which allow materials to be studied as part of a dynamic system, have significantly advanced understanding of LIBs, and they offer the same potential for SSBs. To address this, a selection of analytical tools for probing interfacial/bulk electrochemical processes is highlighted and their advantages and challenges for studying various aspects of SSB chemistry are described. Finally, a perspective on how different techniques could support the future development of advanced SSBs is provided.

Bulk-type all-solid-state batteries (SSBs) are receiving much attention as next-generation energy storage technology with potentially improved safety and higher power and energy densities (over a w...

All-inorganic solid-state batteries (SSBs) currently attract much attention as next-generation high-density energy-storage technology. However, to make SSBs competitive with conventional Li-ion batteries, several obstacles and challenges must be overcome, many of which are related to interface stability issues. Protective coatings can be applied to the electrode materials to mitigate side reactions with the solid electrolyte, with lithium transition metal oxides, such as LiNbO

While still premature as an energy storage technology, bulk solid-state batteries are attracting much attention in the academic and industrial communities lately. In particular, layered lithium metal oxides and lithium thiophosphates hold promise as cathode materials and superionic solid electrolytes, respectively. However, interfacial side reactions between the individual components during battery operation usually result in accelerated performance degradation. Hence, effective surface coatings are required to mitigate or ideally prevent detrimental reactions from occurring and having an impact on the cyclability. In the present work, we examine how surface carbonates incorporated into the sol–gel-derived LiNbO3 protective coating on NCM622 [Li1+x(Ni0.6Co0.2Mn0.2)1–xO2] cathode material affect the efficiency and rate capability of pellet-stack solid-state battery cells with β-Li3PS4 or argyrodite Li6PS5Cl solid electrolyte and a Li4Ti5O12 anode. Our research data indicate that a hybrid coating may in fact be beneficial to the kinetics and the cycling performance strongly depends on the solid electrolyte used.

In recent years, investigations into improving the performance of bulk-type solid-state batteries (SSBs) have attracted much attention. This is due, in part, to the fact that they offer an opportunity to outperform the present Li-ion battery technology in terms of energy density. Ni-rich Li$_{1+x}$(Ni$_{1-y-z}$Co$_{y}$Mn$_{z}$)$_{1-x}$O$_{2}$ (NCM) and lithium-thiophosphate-based solid electrolytes appear to be a promising material combination for application at the cathode side. Here, we report about exploratory investigations into the 1.5Li$_{2}$S/0.5P$_{2}$S$_{5}$/LiI phase system and demonstrate that a glassy solid electrolyte has more than an order of magnitude higher room-temperature ionic conductivity than the crystalline counterpart, tetragonal Li$_{4}$PS$_{4}$I with the P4/nmm space group (∼1.3 versus ∼0.2 mS cm$^{-1}$). In addition, preliminary results show that usage of the glassy 1.5Li$_{2}$S–0.5P$_{2}$S$_{5}$–LiI in pellet stack SSB cells with an NCM622 (60% Ni content) cathode and a Li$_{4}$Ti$_{5}$O$_{12}$ anode leads to enhanced capacity retention when compared to the frequently employed argyrodite Li$_{6}$PS$_{5}$Cl solid electrolyte. This indicates that, apart from interfacial instabilities, the stiffness (modulus) of the solid electrolyte and associated mechanical effects may also impact significantly the long-term performance. Moreover, SSB cells with the glassy 1.5Li$_{2}$S–0.5P$_{2}$S$_{5}$–LiI and high-loading cathode (∼22 mg$_{NCM622}$ cm$^{-2}$) manufactured using a slurry-casting process are found to cycle stably for 200 cycles at C/5 rate and 45 °C, with areal capacities in excess of 3 mA h cm$^{-2}$.

Cell reports 2(6), 100465 (2021). doi:10.1016/j.xcrp.2021.100465, Laboratory research into bulk-type solid-state batteries (SSBs) has been focused predominantly on powder-based, pelletized cells and has been sufficient to evaluate fundamental limitations and tailor the constituents to some degree. However, to improve experimental reliability and for commercial implementation of this technology, competitive slurry-cast electrodes are required. Here, we report on the application of an approach guided by design of experiments (DoE) to evaluate the influence of the type/content of polymer binder and conductive carbon additive on the cyclability and processability of Li$_{1+x}$(Ni$_{0.6}$Co$_{0.2}$Mn$_{0.2}$)$_{1−x}$O$_2$ (NCM622) cathodes in SSB cells using lithium thiophosphate solid electrolytes. The predictions are verified by charge-discharge and impedance spectroscopy measurements. Furthermore, structural changes and gas evolution are monitored via X-ray diffraction and differential electrochemical mass spectrometry, respectively, in an attempt to rationalize and support the DoE results. In summary, the optimized combination of polymer binder and conductive carbon additive leads to high electrochemical performance and good processability., Published by Elsevier, [New York, NY]

Chemical communications 55(75), 11223 - 11226 (2019). doi:10.1039/C9CC04453A, Determining the state-of-charge of all-solid-state batteries via bothex situ and operando X-ray diffraction, rather than by electrochemicaltesting (may be strongly affected by electrically isolated/inactivematerial, irreversible side reactions, etc.), is reported. Specifically,we focus on bulk-type cells and use X-ray diffraction data obtainedon a liquid electrolyte-based Li-ion cell as the reference standardfor changes in lattice parameters with (de)lithiation., Published by Soc., Cambridge

All-solid-state batteries (SSBs) are considered as next-generation energy storage technology with the possibility of higher energy and power densities as well as safety compared to conventional lithium-ion batteries [1]. SSBs with sulfidic solid electrolytes (SEs) as a component are thought to be the closest towards practical implementation [2] despite widely reported side reactions at the cathode active material (CAM)/SE interface. Advances in coating technology have helped suppress these detrimental reactions to a certain extent [3]. We demonstrate the use of differential electrochemical mass spectrometry (DEMS) on evaluating the stability of a protective surface coating [4]. Analysis of the gas evolved provides insights into possible reaction mechanisms at the CAM/SE interface. DEMS was also used to investigate the practical safety performance of sulfide-based SSBs with respect to possible harmful gas evolution such as H2S and SO2 [5]. Key Words: All-solid-state battery, differential electrochemical mass spectrometry, electrochemical energy storage References Janek, W. Zeier, Nat. Energy, 1 (2016) 16141. J. Nam, D. Y. Oh, S. H. Jung, Y. S. Jung, J. Power Sources, 375 (2018) 93–101. -Y. Kim, F. Strauss, T. Bartsch, J. H. Teo, T. Hatsukade, A. Mazilkin, J. Janek, P. Hartmann, T. Brezesinski, Chem. Mater., 31 (2019) 9664 – 9672. Bartsch, F. Strauss, T. Hatsukade, A. Schiele, A-Y. Kim, P. Hartmann, J. Janek, T. Brezesinski, ACS Energy Lett., 3 (2018) 2539–2543. Strauss, J. H. Teo, A. Schiele, T. Bartsch, T. Hatsukade, P. Hartmann, J. Janek, T. Brezesinski, ACS Appl. Mater. Interfaces, 12 (2020), 20462–20468.