PEO-Based Solid-State Electrolytes Reinforced by High Strength, Interconnected MOF Networks

Construction of polymer-based electrolytes with excellent mechanical properties and high ionic conductivity is highly desirable for solid-state lithium–metal batteries. Herein, a scalable strategy is suggested to achieve the high strength and high performance polymer-based solid-state electrolyte via filling polyethylene oxide (PEO)/Li-salt (LiTFSI) electrolyte into an interconnected metal–organic framework (MOF) network based on the typical hot-pressing process, in which the MOF network is grown on the polyacrylonitrile (PAN) electrospun fibrous membrane through an automated layer-by-layer (LbL) assembly spraying technique. The MOF network not only promises excellent mechanical properties and high thermal stability but also enhances ionic conductivity due to the resulting interconnected Li+ transport paths. In addition, such electrolyte also demonstrates a high Li+ transference number (0.68) and a wide electrochemical stability window (5.2 V). As a result, the assembled Li//Li symmetrical cell shows an ultrastable cycling performance even after cycling for 1800 h. Furthermore, its LiFePO4//Li full cell exhibits a high capacity of up to 120 mAh g–1 at 1 C and 30 °C and can maintain a rather high capacity retention of 95% after 160 cycles. This study provides some inspirations for the fabrication of high performance polymer-based solid-state electrolytes in a large scale.