Extensively Reducing Interfacial Resistance by the Ultrathin Pt Layer between the Garnet-Type Solid-State Electrolyte...

All-solid-state Li-ion batteries (ASSLIBs), also known as next-generation batteries, have attracted much attention due to their high energy density and safety. The best advantage of ASSLIBs is the Li-metal anodes that could be used without safety issues. In this study, a highly conductive garnet solid electrolyte (Li_6.75La₃Zr_1.75Ta_0.25O₁₂, LLZTO) was used in the ASSLIB, and a Pt film was used to modify the surface of LLZTO to prove the solution of the Li-metal anode for LLZTO. Li-Pt alloy was synthesized to improve the wettability and contact of the interface. The interfacial resistance was reduced by 21 times, at only 9 Ω cm². The symmetric cell could stably cycle over 3500 h at a current density of 0.1 mA cm^-2. The full cell of Li|Li-Pt|LLZTO|LiFePO₄ and Li|Li-Pt|LLZTO|LiMn_0.8Fe_0.2PO₄ achieved high stability in terms of battery performance. Point-to-point contact transformed into homogeneous surface contact made the Li-ion flux faster and more stable. This surface modification method could provide researchers with a new choice for fixing interface issues and promoting the application of high-performance ASSLIBs in the future.