Understanding the Positive Effect of LATP in Polymer Electrolytes in All-Solid-State Lithium Batteries

Composite solid electrolytes with ceramic particles dispersed in a polymer matrix are considered a correct choice for all-solid-state batteries. These electrolytes balance the high ionic conductivity of superionic-ceramic conductors and the elasticity of polymers. Here, Li||LiFePO₄ batteries with 30 wt% of LATP embedded in PEO₂₀:LiTFSI show superior performance at elevated temperature. After ∼150 cycles, cells retained 84% of their original capacity compared to only 51% for batteries with no additive. At 5 C cells demonstrate 43% higher capacity. In symmetric cells with blocking and non-blocking electrodes and all-solid-state batteries LATP lowers the impedance of the electrode-electrolyte interface ensuring cycling stability. LATP improves performance by stabilization of the cathode-electrolyte interface, apparently the major contributor to the cell impedance.