Double-network composite solid electrolyte with stable interface for dendrite-free Li metal anode

The application of solid polymer electrolytes for Li metal batteries (LMBs) is hindered by the Li/electrolyte interface instability and poor mechanical strength. Herein, a flexible composite solid electrolyte with a cross-linked double-network structure of inorganic particles and polymer was constructed by an in situ gel-sol method. The as-prepared electrolyte promoted the formation of a stable solid electrolyte interface on the Li metal surface and suppressed the formation of Li dendrites more than pure polymer electrolytes. Particularly, X-ray photoelectron spectroscopy results demonstrated the beneficial effect of inorganic particles for suppressing the side reactions between the Li metal and polymer. Additionally, the as-prepared electrolyte exhibited a reduction of polymer crystallinity, which can facilitate Li⁺ transport by weaking the interactions between Li⁺ and the polymer chains. The Li|Li symmetric batteries were stabilized to maintain successive electrodeposition over 1400 h of the plating/stripping process. Furthermore, the Li|LiFePO₄ batteries displayed excellent cycling performance at a rate of 0.3 C, revealing tremendous potential in promoting the large-scale application of future LMBs.