Flexible 3D porous MnOx/rGO hydrogel with fiber reinforced effect for enhancing mechanical and zinc storage performances

Abstract

3D Porous MnOx/rGO hydrogel (3DP MnOx/rGO hydrogel) as cathode material for aqueous zinc ion batteries (AZIBs) is synthesized by polyvinyl alcohol (PVA), nanowires of MnOx (NW MnOx) and reduced graphene oxide (rGO) via repeated freeze-thaw method, which has a high flexibility and puncture resistance. The 3D self-supporting hydrogel presented complex 3D cross-linking system and excellent flexibility through hydrogen bonding and reinforcement of inorganic nano wires. The electrochemical and mechanical properties of the 3DP MnOx/rGO hydrogel are optimized by adjusting the respective percentages of NW MnOx (30%), rGO (5%), PVA (25%), and H2O (40%) in the total mass. The flexible hydrogel cathode exhibits a high capacity of 297.6 mA h g−1 and good cyclic stability after 500 cycles at 1 A g−1. Finite element method confirms that the hydrogel material can alleviate the stress distribution caused by zincification process. The soft-packaged AZIBs, which utilize 3DP MnOx/rGO hydrogel as the cathode and Zn foil as the anode, exhibit excellent cycling performance (152.2 mA h g−1 at 1 A g−1 after 500 cycles under an angle of 180°) and provide a stable power supply across different bending angles.