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

Large interfacial impedance, severe spontaneous reaction and poor ion transport efficiency between Li_1.3Al_0.3Ti_1.7(PO₄)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 Li₂O/Li_xIn is constructed on LATP through an in situ electrochemical reaction of In₂O₃ with Li metal. Li₂O with low Li⁺ migration energy barrier and electron-blocking injection can accelerates Li⁺ diffusion and suppresses dendrite growth at the interface. Li_xIn 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/In₂O₃@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/In₂O₃@LATP/LiFePO₄ 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_1.2Mn_0.6Ni_0.2O₂ cathode, the full battery also has good compatibility with 4.8 V and high capacity.