AgF-PEO Composite Interfacial Layer for Electrolyte-Free LAGP-based Lithium Metal Batteries

NASICON-type LAGP solid state electrolyte has become one of the most promising solid-state electrolytes due to its superior performance such as favorable room-temperature ionic conductivity, high stability in air, wide electrochemically stable window, and low cost. The key constraint to the development of LAGP electrolyte is the LAGP/Li interface problem. In this paper, a composite interfacial layer (AgF@Li-PEO@LAGP) is introduced between LAGP electrolyte and electrode material. The LiF and Ag nanoparticles are generated on the Li surface by utilizing the substitution reaction to uniform lithium flux and prevent the side reaction, while the flexible PEO polymer buffer layer on the LAGP will improve the interface wettability. The Li/LAGP/Li symmetric cell modified with composite interfacial layer can maintain a low polarization voltage of 0.11 V at 0.1 mA cm−2 for stable cycling for more than 1200 h. The full cell also shows excellent cycling stability with the capacity retention of 93.6 % after 100 cycles. The composite interface layer can realize the elimination of liquid electrolyte and greatly reduce interface resistance. This broadens the road for the realization of all-solid-state batteries.