Layer-by-Layer Assembly Strategy for Reinforcing the Mechanical Strength of an Ionogel Electrolyte without Affecting Ionic Conductivity

The simultaneous boosting of the ionic conductivity and the mechanical strength of an ionogel electrolyte is hindered by its entrapped electrolyte. Herein, we report a promising strategy to boost the mechanical strength of an ionogel by coating it with an ultrathin layer of polyanions and polycations via layer-by-layer (LbL) assembly. The essence of our strategy is to make use of the intrinsic ionic structure of an ionogel membrane for facile LbL construction of a membrane electrolyte interface. The resulting ultrathin LbL coating enhanced the mechanical strength of the electrolyte 5-fold while maintaining its high ionic conductivity (∼10^–4 S cm^–1 at 10 °C). The preliminary Li||LbL-LiNaf||LFP cell experiments exhibit promising electrochemical performance. This result is a significant development that will lead to the fabrication of robust membranes with liquid-like conductivity for lithium metal batteries.