Super Flexible Cathode Material with 3D Cross‐Linking System Based on Polyvinyl Alcohol Hydrogel for Boosting Aqueous Zinc Ion Batteries

Abstract A flexible hydrogel cathode constructed by polyvinyl alcohol, MnO 2 and graphene was successfully prepared through repeated freeze‐thaw method, which formed complex 3D cross‐linking system with hydrogen bonding and inorganic particle reinforcement. The superior mechanical and electrochemical performance were balanced and obtained by controlling the content of MnO 2 (30 %) and H 2 O (10 %) of the total mass, respectively. As a result, this flexible hydrogel cathode delivered a high capacity of 164.2 mA h g −1 at 1 A g −1 and an outstanding cyclic stability after 500 cycles at 1 A g −1 . Furthermore, hydrogel matrix and graphene conductive network could effectively prevent volume expansion and pulverization of MnO 2 nanoparticles. And the electrochemical kinetic revealed that the main process was capacitive control, which confirmed the excellent ion transport to enhance storage performance of ZIBs. The soft package ZIBs provided stable power supply at different bending angles.