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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]

All-solid-state batteries (ASSBs) with inorganic solid electrolytes (SEs) have received much attention as future energy storage systems owing to their high energy densities and excellent safety. Sulfide-based SEs are considered promising because they exhibit greater ionic conductivities and mechanical softness than oxide-based SEs. In particular, argyrodite-type Li6PS5Cl with a high ionic conductivity of 3.0 × 10−3 S cm−1 offers new possibilities for realizing high-performance ASSBs. However, contact with moisture results in the evolution of H2S from Li6PS5Cl, which has hindered the scalable fabrication and practical application of Li6PS5Cl. To avoid this issue, we propose incorporating a zeolite, which can act as a scavenger for both toxic H2S gas and moisture, as a functional additive in Li6PS5Cl. We demonstrate that zeolite-embedded Li6PS5Cl exhibits greatly improved chemical stability and reduced H2S evolution upon storage in humid air (RH 50%), leading to a noticeable improvement in the cycle performance of ASSBs. This approach could resolve the technical issues associated with sulfide-based SEs toward commercial-scale implementation. [ABSTRACT FROM AUTHOR]

Bulk-type all-solid-state Na-ion batteries (ASNBs) employing inorganic Na-ion conductors and operating at room temperature are considered as promising candidates for large-scale energy storage systems. However, their realization has been impeded by low ionic conductivity, instability in air of the solid electrolytes, and poor ionic contacts among the constituents of the electrodes. Here, we report novel glass-ceramic xNaI·(1 −x)Na3SbS4 superionic conductors (maximum Na+ conductivity of 0.74 mS cm−1 at 30 °C, for x = 0.10) obtained from scalable methanol solutions. Comprehensive spectroscopic evidence, density functional theory calculations, and electrochemical analysis suggest the decisive role of I− incorporated in the disordered domains at the nanoscale in the overall Na+ transport. Furthermore, the solution-derived NaI·Na3SbS4 forms uniform coating layers on the surface of the active material FeS2, providing unobstructed ionic transport pathways in the electrodes. The good electrochemical performance of FeS2/Na–Sn ASNBs at 30 °C is demonstrated. [ABSTRACT FROM AUTHOR]

Bulk-type all-solid-state Li-ion batteries have emerged as the enabler to achieve better safety and to use Li metal negative electrodes for higher energy density. However, all-solid-state half-cells fabricated using In or Li–In counter electrodes (CEs) have been routinely tested to assess working electrodes (WEs) without any verification. Moreover, there have been few reports on the in-depth analysis of all-solid-state full-cells, which is imperative for practical applications. In this work, for the first time, we report novel bulk-type all-solid-state three-electrode cells that enable successful deconvolution and diagnosis of the voltages of positive and negative electrodes even for cells having thin solid electrolyte (SE) layers. In the first case study, that of Sn/Li–In half-cells, earlier termination of Li–In CEs than Sn WEs, which results in unexpectedly low capacity, is measured. This problem is solved by percolating Li–In with SEs. For the second case, namely, that of LiNi0.6Co0.2Mn0.2O2/graphite full-cells having only 50–60 μm-thick SE layers (which are fabricated by a scalable wet-slurry process), internal short circuits by penetrating growth of Li metal during charging at high C-rates are revealed for the first time. Further, a unique dischargeability to 0 V for LiNi0.6Co0.2Mn0.2O2/graphite or LiNi0.6Co0.2Mn0.2O2/Si–C full-cells is described. [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]

Room-temperature-operable all-solid-state Na-ion batteries (ASNBs) using sulfide Na-ion solid electrolytes (SEs) are promising because of their potential for greater safety, lower cost, and acceptable performance. Despite extensive developments in the area of sulfide Na-ion SEs, their poor chemical stability and prospects for wet-chemical synthesis have been overlooked to date. Herein, the scalable synthesis of Na3SbS4via aqueous-solution routes using precursors of Na2S, Sb2S3, and elemental sulfur for ASNBs is described. With no concerns about the evolution of toxic H2S gas, the aqueous-solution-synthesized Na3SbS4 exhibits high ionic conductivities (0.1–0.2 mS cm−1 at 25 °C). Importantly, the homogeneity of the aqueous solutions enables the creation of uniform Na3SbS4 coatings on FeS2. Fe2S/Na–Sn ASNBs, employing the aqueous-solution-synthesized Na3SbS4 and the Na3SbS4-coated FeS2 for the SE layer and positive electrode, respectively, demonstrate a high charge capacity of 256 or 346 mA h g−1 with good reversibility at 30 °C, highlighting their potential for practical applications. [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]

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]

Developing high-performance all-solid-state batteries is contingent on finding solid electrolyte materials with high ionic conductivity and ductility. Here we report new halide-rich solid solution phases in the argyrodite Li 6 PS 5 Cl family, Li 6-x PS 5-x Cl 1+x , and combine electrochemical impedance spectroscopy, neutron diffraction, and 7 Li NMR MAS and PFG spectroscopy to show that increasing the Cl - /S 2- ratio has a systematic, and remarkable impact on Li-ion diffusivity in the lattice. The phase at the limit of the solid solution regime, Li 5.5 PS 4.5 Cl 1.5 , exhibits a cold-pressed conductivity of 9.4±0.1 mS cm -1 at 298 K (and 12.0±0.2 mS cm -1 on sintering)-almost four-fold greater than Li 6 PS 5 Cl under identical processing conditions and comparable to metastable superionic Li 7 P 3 S 11 . Weakened interactions between the mobile Li-ions and surrounding framework anions incurred by substitution of divalent S 2- for monovalent Cl - play a major role in enhancing Li + -ion diffusivity, along with increased site disorder and a higher lithium vacancy population., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 (Li 4 SnS 4 ) are reported, which are prepared using a scalable aqueous-solution process. An active material (LiCoO 2 ) coated by solidified Li 4 SnS 4 from aqueous solutions results in a significant improvement in the electrochemical performance of ASLBs. Side-effects of the exposure of LiCoO 2 to aqueous solutions are minimized by using predissolved Li 4 SnS 4 solution., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)