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

A flexible hydrogel cathode constructed by polyvinyl alcohol, MnO2 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 MnO2 (30 %) and H2O (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 MnO2 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.

Automated summary

A flexible hydrogel cathode with high capacity and excellent cyclic stability was prepared using a freeze-thaw method. The material has a complex 3D cross-linking structure and reinforcement effect, which effectively prevents volume expansion and pulverization. Electrochemical kinetics show that the material has good ion transport properties.