A highly compressible hydrogel electrolyte for flexible Zn-MnO2 battery

Compressibility of zinc-manganese oxide (Zn-MnO2) batteries is an essential element of modern flexible electronics. Hydrogel electrolytes with superior elasticity and compressibility are highly demand to guarantee a stable energy output of the flexible Zn-MnO2 battery. Herein, a highly compressible hydrogel electrolyte was developed by introducing soybean protein isolate nanoparticles (SPI) into covalently cross-linked polyacrylamide (PAAM) polymer networks. The SPI/PAAM hydrogel electrolyte for Zn-MnO2 battery possessed outstanding reversible compressibility due to the aggregation of SPI nanoparticles on the PAAM chains through the weak electrostatic interaction, which could dissipate energy effectively. Consequently, the Zn-MnO2 battery based on the compressible hydrogel electrolyte displayed a decent specific capacity (299.3 mA h g-1) and desirable capacity retention rate (78.2%) after 500 charge/discharge cycles. Notably, the device could maintain stable power output under 96% compress strain and light the bulb even under severe mechanical stimulation like being-bent and hammered. It's believed that the compressible Zn-MnO2 batteries hold enormous potential as the energy storage devices in the field of flexible wearable electronics.