SOLID-STATE BATTERY CELLS, ELECTROLYTE SHEETS AND THEIR PREPARATION METHODS, BATTERY DEVICES AND ELECTRICAL DEVICES
The electrolyte sheet is divided into a solid electrolyte base layer and a thin electron blocking layer facing the negative electrode. The blocking layer conducts Li+ but not electrons, preventing lithium ions from being reduced to metal within the electrolyte and nucleating dendrites there.
The blocking layer comprises CsxMy[Moa(CN)b(NO)c]·nH2O, in which M is a divalent metal (here Fe), the cyanide- and nitrosyl-coordinated molybdenum anion forms the host framework, and n is the lattice water content. Cs1.1Fe0.95[Mo(CN)5(NO)]·4H2O was precipitated from aqueous Cs[Mo(CN)5(NO)], CsCl and FeCl2·4H2O at 80°C. The powder was dispersed in n-hexane and electrodeposited (0.5 mA cm-2, 25°C, 4 h) onto a 60 μm base layer of Li6PS5Cl and styrene-butadiene rubber (SBR) (98 : 2), forming a 10 μm blocking layer.
The blocking layer exhibits an electronic conductivity of 1 × 10-10 S/cm, an ionic conductivity of 7.45 × 10-3 S/cm at 45°C, and an elastic modulus of 49.8 GPa against 20 GPa for the base layer. Cells with Li1.2Ni0.13Co0.13Mn0.54O2/InCl3 (1 : 1) positive electrodes and silicon-carbon negative electrodes exhibit a first-cycle coulombic efficiency of 94.2% and a 200-cycle capacity retention of 87.4% (0.33 C, 2.0–4.8 V, 15 MPa), compared to 79.5% and 73.8% for cells whose electrolyte sheet is the Li6PS5Cl–SBR layer alone. Dendrite penetration after 200 cycles occurred in 4% of cells, versus 40% without the blocking layer.
