A Flexible Semi-Interpenetrating Network-Enhanced Ionogel Polymer Electrolyte for Highly Stable and Safe Lithium Metal Batteries.

An ionogel polymer electrolyte (IGPE), which combines the merits of high ionic conductivity and excellent safety property of a liquid electrolyte and a solid electrolyte, respectively, has shown great prospects in the application of a new generation of lithium secondary batteries. However, the increase in the ionic conductivity of IGPE will inevitably be at the expense of reduced mechanical strength, and this dilemma limits its application and market promotion. Here, an IGPE with a semi-interpenetrating cross-linked network structure was synthesized by UV-cross-linking to tackle this plight. The optimal sample ME82 shows an excellent ionic conductivity of 1.19 mS cm-1 at room temperature and robust mechanical strength (breaking strength: 1.55 MPa, elongation at break: 259%). Therefore, the assembled LiFePO4/ME82/Li cion cell displays an outstanding initial specific discharge capacity of 160.9 mAh g-1 at 55 °C 0.5 C, with a capacity retention of 94.00% after 200 cycles. In addition, ME82-based flexible batteries can withstand bending, folding, and even shearing abuse, which indicates that ME82 has application potentials in flexible electronic devices.