Atomic Welding Enhancing the Electromechanical Performance of Li1.3Al0.3Ti1.7(PO4)3 (LATP) Solid Electrolyte

Practical application of solid-state electrolyte (SSE) is currently impeded by the ongoing growth and erosion from Li metal dendrites during cycling in solid-state batteries (SSBs) mainly due to the presence of abundant grain boundaries and low fracture toughness of SSE film. To address this issue, an atomic welding strategy bridged by Ni doping is proposed to enhance the ionic conductivity, the density, and fracture toughness of Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) SSE. The fracture toughness of the SSE can be improved from 1.01±0.2 MPa·m^1/2 to 1.88±0.2 MPa·m^1/2, which is proved necessary to inhibit the penetration of Li dendrite and maintain stable interface between LATP and Li metal during long cycling. As a result, the Li/LATP-Ni/Li symmetric cell succeeds in the galvanostatic cycling for 400 h at 0.1 mA/cm² while a high capacity retention of 90.8% is achieved with the LFP-Li full cell cycled at 1.5 C after 200 cycles. These findings not only provide an atomic-welding method for densifying SSE films, but also enlighten to competing with Li metal anode for achieving high-energy SSBs.