Li+ Interstitial Flow in Composite State Electrolyte for Solid-State Lithium Batteries with High-Loading Cathode

Abstract

Solid-state lithium metal batteries (SSLMBs) hold high energy density and are safe and reliable. However, the polymer-based solid electrolyte possesses low ionic conductivity at ambient conditions and is incompatible with the lithium anode, which seriously hinders their practical application. Solid composite electrolyte (SCE) was prepared by fixing a fast-ion conductor of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) within the P (VDF-ctfe) skeleton. The “Lewis base” effect of LLZTO can be used to construct a fast ion transport layer, realize the fast coordination/decoupling of lithium ions, form a fast ion jump, and improve the density of lithium carriers. The doped SCEs hold a high ionic conductivity of 1.2×10−3 S/cm at ambient temperature and a high migration number of 0.82. In addition, SCE-3% shows intimate compatibility with the lithium anode and LiFePO4 cathode. The assembled Li//SCE-3%/Li battery can be stably tested for 1200h at 0.1 mA/cm2, and the LiFePO4//SCE-3%//Li can charge and discharge for 70 times at 0.5 C, corresponding to 70.1% capacity retention rate, showing excellent electrochemical performance. This work gives a strategy for the design philosophy of SCE with high ion conductivity in SSLMBs.