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The liquid‐phase synthesis (LS) of sulfide solid electrolytes (SEs) has promising potential for mass production of practical all‐solid‐state Li batteries (ASLBs). However, their accessible SE compositions are mostly metal‐free. Moreover, liquid‐phase‐synthesized‐SEs (LS‐SEs) suffer from high electronic conductivity due to carbon impurities, resulting in below‐par electrochemical performance of ASLBs. Here, the LS of highly deformable and air‐stable Li3+xP1‐xSnxS4 (0.19 mS cm−1) using 1,2‐ethylene diamine‐1,2‐ethanedithiol with tetrahydrofuran is reported. A low heat‐treatment temperature (260 °C) prevents the carbonization of organic residues. Importantly, a remarkable enhancement in the deformability of LS‐SEs compared to that of conventional solid‐state‐synthesized SEs (SS‐SEs) is identified for the first time. LiNi0.7Co0.15Mn0.15O2 electrodes employing LS‐SEs in ASLBs significantly outperform those using SS‐SEs, notably when assembled under a low fabricating pressure (148 vs 370 MPa, e.g., capacity loss: 2 vs 41 mA h g−1) or tested under a low operating pressure (12 or 3 MPa), which is attributed to reduced electrochemo‐mechanical effects. Finally, when employing SEs that are exposed to air (dew point of −20 °C), LiNi0.7Co0.15Mn0.15O2 electrodes employing SEs with Sn‐substituted composition or prepared by LS exhibit significantly better capacity retention than conventional SEs with Sn‐free composition or prepared by SS (e.g., 92.2% for LS‐Li3.2P0.8Sn0.2S4 vs 32.5% for SS‐Li3PS4). [ABSTRACT FROM AUTHOR]

Abstract: Owing to the ever‐increasing safety concerns about conventional lithium‐ion batteries, whose applications have expanded to include electric vehicles and grid‐scale energy storage, batteries with solidified electrolytes that utilize nonflammable inorganic materials are attracting considerable attention. In particular, owing to their superionic conductivities (as high as ≈10−2 S cm−1) and deformability, sulfide materials as the solid electrolytes (SEs) are considered the enabling material for high‐energy bulk‐type all‐solid‐state batteries. Herein the authors provide a brief review on recent progress in sulfide Li‐ and Na‐ion SEs for all‐solid‐state batteries. After the basic principles in designing SEs are considered, the experimental exploration of multicomponent systems and ab initio calculations that accelerate the search for stronger candidates are discussed. Next, other issues and challenges that are critical for practical applications, such as instability in air, electrochemical stability, and compatibility with active materials, are discussed. Then, an emerging progress in liquid‐phase synthesis and solution process of SEs and its relevant prospects in ensuring intimate ionic contacts and fabricating sheet‐type electrodes is highlighted. Finally, an outlook on the future research directions for all‐solid‐state batteries employing sulfide superionic conductors is provided. [ABSTRACT FROM AUTHOR]

Abstract: Sulfide Na‐ion solid electrolytes (SEs) are key to enable room‐temperature operable all‐solid‐state Na‐ion batteries that are attractive for large‐scale energy storage applications. To date, few sulfide Na‐ion SEs have been developed and most of the SEs developed contain P and suffer from poor chemical stability. Herein, discovery of a new structural class of tetragonal Na4−xSn1−xSbxS4 (0.02 ≤ x ≤ 0.33) with space group I41/acd is described. The evolution of a new phase, distinctly different from Na4SnS4 or Na3SbS4, allows fast ionic conduction in 3D pathways (0.2–0.5 mS cm−1 at 30 °C). Moreover, their excellent air stability and reversible dissolution in water and precipitation are highlighted. Specifically, TiS2/Na–Sn all‐solid‐state Na‐ion batteries using Na3.75Sn0.75Sb0.25S4 demonstrates high capacity (201 mA h (g of TiS2)−1) with excellent reversibility. [ABSTRACT FROM AUTHOR]

Bulk-type all-solid-state lithium-ion batteries (ASLBs) for large-scale energy-storage applications have emerged as a promising alternative to conventional lithium-ion batteries (LIBs) owing to their superior safety. However, the electrochemical performance of bulk-type ASLBs is critically limited by the low ionic conductivity of solid electrolytes (SEs) and poor ionic contact between the active materials and SEs. Herein, highly conductive (0.14 mS cm−1) and dry-air-stable SEs (Li4SnS4) are reported, which are prepared using a scalable aqueous-solution process. An active material (LiCoO2) coated by solidified Li4SnS4 from aqueous solutions results in a significant improvement in the electrochemical performance of ASLBs. Side-effects of the exposure of LiCoO2 to aqueous solutions are minimized by using predissolved Li4SnS4 solution. [ABSTRACT FROM AUTHOR]

All-solid-state sodium-ion batteries that operate at room temperature are attractive candidates for use in large-scale energy storage systems. However, materials innovation in solid electrolytes is imperative to fulfill multiple requirements, including high conductivity, functional synthesis protocols for achieving intimate ionic contact with active materials, and air stability. A new, highly conductive (1.1 mS cm−1 at 25 °C, Ea=0.20 eV) and dry air stable sodium superionic conductor, tetragonal Na3SbS4, is described. Importantly, Na3SbS4 can be prepared by scalable solution processes using methanol or water, and it exhibits high conductivities of 0.1-0.3 mS cm−1. The solution-processed, highly conductive solidified Na3SbS4 electrolyte coated on an active material (NaCrO2) demonstrates dramatically improved electrochemical performance in all-solid-state batteries. [ABSTRACT FROM AUTHOR]

Development of new sulfide Li+ superionic conductors with mechanical sinterability is the key to the success of all-solid-state lithium batteries. While phosphorus-containing sulfide superionic conductor materials have been widely investigated, phosphorus-free materials showing good air-stability have been overlooked. Herein, the Li+ dynamics in Sb-substituted Li 4 SnS 4 showing a high Li+ conductivity of max. 0.85 mS cm−1 at 30 °C and excellent dry-air stability as well as negligible H 2 S evolution is described. Structural analysis with X-ray and neutron diffraction reveals that Sb-substitution renders an expansion of the lattice volume and formation of Li vacancies. Additionally, 1D-preferable 3D Li+ diffusion channels in Li 4-x Sn 1-x Sb x S 4 are disclosed. The fast Li+ diffusion in Li 4-x Sn 1-x Sb x S 4 is rationalized by complementary analysis using AC impedance measurements, bond valence energy landscape calculation, and 7Li nuclear magnetic resonance spectroscopy. Excellent electrochemical performances of TiS 2 electrodes employing Li 3.85 Sn 0.85 Sb 0.15 S 4 in all-solid-state batteries are demonstrated. Image 1 • Sb-substituted Li 4 SnS 4 shows a maximum Li+ conductivity of 0.85 mS cm−1 at 30 °C. • Excellent dry-air stability and negligible H 2 S evolution are confirmed. • 1D-preferable 3D Li+ diffusion channels disclosed by neutron diffraction analysis. • Performance of all-solid-state Li-ion batteries using Li 3.85 Sn 0.85 Sb 0.15 S 4. [ABSTRACT FROM AUTHOR]

For mass production of all‐solid‐state lithium‐ion batteries (ASLBs) employing highly Li+ conductive and mechanically sinterable sulfide solid electrolytes (SEs), the wet‐slurry process is imperative. Unfortunately, the poor chemical stability of sulfide SEs severely restrict available candidates for solvents and in turn polymeric binders. Moreover, the binders interrupt Li+‐ionic contacts at interfaces, resulting in the below par electrochemical performance. In this work, a new scalable slurry fabrication protocol for sheet‐type ASLB electrodes made of Li+‐conductive polymeric binders is reported. The use of intermediate‐polarity solvent (e.g., dibromomethane) for the slurry allows for accommodating Li6PS5Cl and solvate‐ionic‐liquid‐based polymeric binders (NBR‐Li(G3)TFSI, NBR: nitrile−butadiene rubber, G3: triethylene glycol dimethyl ether, LiTFSI: lithium bis(trifluoromethanesulfonyl)imide) together without suffering from undesirable side reactions or phase separation. The LiNi0.6Co0.2Mn0.2O2 and Li4Ti5O12 electrodes employing NBR‐Li(G3)TFSI show high capacities of 174 and 160 mA h g−1 at 30 °C, respectively, which are far superior to those using conventional NBR (144 and 76 mA h g−1). Moreover, high areal capacity of 7.4 mA h cm−2 is highlighted for the LiNi0.7Co0.15Mn0.15O2 electrodes with ultrahigh mass loading of 45 mg cm−2. The facilitated Li+‐ionic contacts at interfaces paved by NBR‐Li(G3)TFSI are evidenced by the complementary analysis from electrochemical and 7Li nuclear magnetic resonance measurements. [ABSTRACT FROM AUTHOR]

Bulk-type all-solid-state lithium-ion batteries (ASLBs) have the potential to be superior to conventional lithium-ion batteries (LIBs) in terms of safety and energy density. Sulfide SE materials are key to the development of bulk-type ASLBs because of their high ionic conductivity (max of 10-2 S cm-1) and deformability. However, the severe reactivity of sulfide materials toward common polar solvents and the particulate nature of these electrolytes pose serious complications for the wet-slurry process used to fabricate ASLB electrodes, such as the availability of solvent and polymeric binders and the formation of ionic contacts and networks. In this work, we report a new scalable fabrication protocol for ASLB electrodes using conventional composite LIB electrodes and homogeneous SE solutions (Li6PS5Cl (LPSCl) in ethanol or 0.4LiI-0.6Li4SnS4 in methanol). The liquefied LPSCl is infiltrated into the tortuous porous structures of LIB electrodes and solidified, providing intimate ionic contacts and favorable ionic percolation. The LPSCl-infiltrated LiCoO2 and graphite electrodes show high reversible capacities (141 and 364 mA h g-1) at 0.14 mA cm-2 (0.1 C) and 30 °C, which are not only superior to those for conventional dry-mixed and slurry-mixed ASLB electrodes but also comparable to those for liquid electrolyte cells. Good electrochemical performance of ASLBs employing the LPSCl-infiltrated LiCoO2 and graphite electrodes at 100 °C is also presented, highlighting the excellent thermal stability and safety of ASLBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesis process is customized for single-particle Ni-rich layered cathode materials. • Morphological engineering of cathode materials enhances the rate-capability and cycling stability. • Microcrack formation and particle fracture can be effectively suppressed during cycling. • All-solid-state-battery shows a high capacity retention of 84.9% at 0.5C after 150 cycles. A single-crystalline Ni-rich cathode material is synthesized for high-performance all-solid-state batteries (ASSBs). We customize the morphology and microstructure of the material by optimizing the synthesis process (particle size control and post-heat treatment) and demonstrate the advantages of single-crystalline cathode materials for practical use in ASSBs. The particle density and particle hardness of single-crystalline cathode materials with a particle size of 5 μm are considerably higher than those of the conventional polycrystalline cathode materials that are composed of spherical aggregates of submicron-scale primary particles. These structural features of the single-crystalline cathode materials improve the long-term cycling performance and rate capability of an ASSB configured with an argyrodite–Li 6 PS 5 Cl solid electrolyte. This is mainly attributed to the intimate interfacial solid–solid contacts and enhanced diffusion kinetics induced by the monolithic morphology of the single-crystalline cathode materials in the electrode. Moreover, undesirable microcrack formation and particle fracture in cathode materials are effectively suppressed during cycling. The feasibility of ASSBs configured with single-crystalline Ni-rich cathode materials is examined in detail. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemo-mechanical effects for all-solid-state batteries are categorized. • The mechanical properties of solid electrolytes are considered. • Stress sources, resulting cell failures, and stress cross-talks are discussed. All-solid-state batteries (ASSBs) using inorganic solid electrolytes (SEs) are in the spotlight for next-generation energy storage devices because of their potential for outstanding safety and high energy density. Recent progress in this field has been primarily based on advances in materials, such as the discovery of SEs with high ionic conductivities and the improvement of interfacial stability in electrodes. However, the use of inelastic SEs causes severe electrochemo-mechanical failures, such as cathode active material (CAM) disintegration, CAM/SE contact loss, and stress build-up during cycling, deteriorating the Li+ and e− transport pathways. Although these concerns have been addressed previously, they have not been contextualized systematically in terms of the mechanical interactions among the components and their impacts on electrochemical performance. Here, we categorize the electrochemo-mechanical effect in ASSBs and its ramifications in terms of stress sources, active materials, composite electrodes, and cell stacks. [ABSTRACT FROM AUTHOR]