Regulating Incompatible Interfaces and Electron/Ion Transport in Lithium Metal Solid State Batteries

Abstract Large interfacial impedance, severe spontaneous reaction and poor ion transport efficiency between Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ (LATP) and Li metal interface are the main bottlenecks restricting the development of LATP‐based solid‐state batteries. Herein, a fast Li ⁺ transfer and electron‐blocking interface composed of Li ₂ O/Li _x In is constructed on LATP through an in situ electrochemical reaction of In ₂ O ₃ with Li metal. Li ₂ O with low Li ⁺ migration energy barrier and electron‐blocking injection can accelerates Li ⁺ diffusion and suppresses dendrite growth at the interface. Li _x In has a high bilateral affinity with Li metal and LATP, which significantly enhances the contact between LATP and Li metal. The initial resistance of the Li/In ₂ O ₃ @LATP/Li symmetric battery is reduced from 1211.4 to 106.5 Ω cm ⁻² , and the critical current density is significantly increased to 1.9 mA cm ⁻² . At high current density and discharge depth, it can stably cycle without dendrites for over 3700 h at 0.2 mA cm ⁻² /0.2 mAh cm ⁻² , and 1800 h at 0.4 mA cm ⁻² /0.4 mAh cm ⁻² . The Li/In ₂ O ₃ @LATP/LiFePO ₄ full battery shows excellent electrochemical performance, after 600 cycles, each cycle decay rate of ≈0.015% at 0.8 C and 25 °C. When matched with Li _1.2 Mn _0.6 Ni _0.2 O ₂ cathode, the full battery also has good compatibility with 4.8 V and high capacity.