Fabrication of Oxide-Based All-Solid-State Batteries by a Sintering Process Based on Function Sharing of Solid Electrolytes

Abstract

Garnet-type Li 7 La 3 Zr 2 O 12 (LLZ) has advantages of stability with Li metal and high Li + ionic conductivity, achieving 1 × 10 −3 S cm −1 , but it is prone to react with electrode active materials during the sintering process. LISICON-type Li 3.5 Ge 0.5 V 0.5 O 4 (LGVO) has the advantage of less reactivity with the electrode active material during the sintering process, but its ionic conductivity is on the order of 10 −5 S cm −1 . In this study, these two solid electrolytes are combined as a multilayer solid electrolyte sheet, where 2 μm thick LGVO films are coated on LLZ sheets to utilize the advantages of these two solid electrolytes. These two solid electrolytes adhere well through Ge diffusion without significant interfacial resistance. The LLZ−LGVO multilayer is combined with a LiCoO 2 positive electrode and a lithium metal anode through annealing at 700 °C. The resultant all-solid-state battery can undergo repeated charge−discharge reactions for over 100 cycles at 25 or 60 °C. The LGVO coating suppresses the increases in the resistance from the solid electrolyte and interfacial resistance induced by annealing by ca. 1/40. As with sulfide-based all-solid-state batteries, function sharing of solid electrolytes will be a promising method for developing advanced oxide-based all-solid-state batteries through a sintering process.

A Roadmap for Solid‐State Batteries

“…To obtain reasonable effective ionic conductivities, cost‐inefficient sintering steps are often required for oxide SE, causing also a challenge for co‐processing with high‐temperature instable CAM. [ 133 ] Because a few promising oxides are (electro‐)chemically stable toward lithium metal and mitigate dendrite formation, but exhibit too low RT ionic conductivities, they are considered as SE separator rather than SE catholyte (Figure 2c, cf. quantitative limits for catholyte and separator in Figure 3).…”

In-Situ-Polymerized 1,3-Dioxolane Solid-State Electrolyte with Space-Confined Plasticizers for High-Voltage and Robust Li/LiCoO2 Batteries

“…6,7 High interface resistances caused by insufficient contact between SSEs and electrodes retard Li-ion transportation and degrade the battery's performance. 8−10 Compared to inorganic ceramic electrolytes 11,12 and polymer film electrolytes, 13−15 the novel in-situ-polymerized SSE can effectively solve the interface contact problem between SSEs and electrodes. 16−18 Typically, during an in situ polymerization procedure, the precursor solution containing a certain amount of polymer monomer is injected into the cell package, which is flowable and wettable to effectively penetrate the entire region of the cell, and the following polymerization with a thermal or ultraviolet (UV) treatment will result in an integrated three-dimensional solid-state network.…”

“…Compared to inorganic ceramic electrolytes , and polymer film electrolytes, − the novel in-situ-polymerized SSE can effectively solve the interface contact problem between SSEs and electrodes. − Typically, during an in situ polymerization procedure, the precursor solution containing a certain amount of polymer monomer is injected into the cell package, which is flowable and wettable to effectively penetrate the entire region of the cell, and the following polymerization with a thermal or ultraviolet (UV) treatment will result in an integrated three-dimensional solid-state network . The in situ polymerization could significantly reduce the interfacial resistance and promote the interface performance; meanwhile, it could enable compatibility of commercial devices of LIB production …”

Additive-Derived Surface Modification of Cathodes in All-Solid-State Batteries: The Effect of Lithium Difluorophosphate- and Lithium Difluoro(oxalato)borate-Derived Coating Layers

“…Various materials, including oxides, polymers, halides, and sulfides, are used as solid-state electrolytes in ASSBs. − Among these materials, sulfide-based solid electrolytes exhibit the highest ionic conductivity − and excellent formability, which enables efficient electrolyte–electrode contact. Consequently, among all the all-solid-state cells (ASSCs) reported to date, the performance of ASSCs utilizing sulfide-based solid electrolytes is the closest to that of commercially available LIBs. − However, sulfide-based solid electrolytes exhibit high reactivity and a relatively narrow voltage window of stability, resulting in electrolyte decomposition during cycling.…”

“…All-solid-state batteries (ASSBs), which contain nonflammable or flame-retardant solid electrolytes, comprise a new generation of rechargeable battery systems that exhibit a significantly lower risk of fire and explosion than commercial lithium-ion batteries (LIBs), which contain flammable organic-liquid electrolytes. − The enhanced safety features of ASSBs are expected to make them highly desirable for commercial use. Beyond their enhanced safety profile, ASSBs demonstrate great potential for maintaining high levels of performance even at extreme temperatures, both high and low. − These advantages also imply the possibility of simplifying the cooling and battery management systems, thereby increasing the energy density per ASSB pack.…”