Double-Network Ionogel Electrolyte with Superior Mechanical Performance and High Safety for Flexible Lithium-Ion Batteries

The development of high-performance solid-state electrolytes to replace conventional liquid organic electrolytes has received intensive attention because of the improvements in the safety, flexibility, reliability, and cycling stability of lithium-ion batteries (LIBs). In this work, we present a double-network ionogel electrolyte (DNIE) through the preparation of interpenetrating polymer networks (IPNs). This DNIE exhibits good mechanical properties, excellent flexibility, nonflammability, high ionic conductivity (4.13x10(-4) S cm(-1) at room temperature), electrochemical stability (>4.8 V), and the ability to suppress Li dendrite formation. The Li/LiFePO4 cell assembled with the DNIE exhibits superior cycling performance while also delivering a steady high discharge capacity of 133.7 mAh g(-1) and a Coulombic efficiency of 99.8 % after 220 cycles at a charge/discharge rate of 0.2 C. Importantly, the DNIE(200 %)-20 % electrolytes can be prepared on the surface of graphite anodes through in situ gelling, which can improve the stability of the active layer and the adhesion between the active layer and current collector in mechanical bending at different angles. After assembling into soft-packed batteries in the configuration of LiCoO2|DNIE(200 %)-20 %|graphite via the in situ gelling of DNIE(200 %)-20 % on the surface of the graphite electrode, the flexible batteries showed excellent cycling stability (capacity retention >98 %) even when folded more than 100 times.

Automated summary

A double-network ionogel electrolyte (DNIE) with good mechanical properties, high ionic conductivity, and electrochemical stability has been developed for use in lithium-ion batteries. The DNIE can also suppress Li dendrite formation. The Li/LiFePO4 cell assembled with the DNIE exhibits excellent cycling performance and high discharge capacity. Furthermore, the electrolyte can improve the stability of the active layer and adhesion between the active layer and current collector.