High stability rGO@MnO2 heterostructure cathodes for shape memory fibrous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) face critical challenges such as rapid cathode capacity fading and structural instability, which hinder their long-term applications. In this study, we address these issues by constructing a reduced graphene oxide (rGO)-coated MnO₂ heterostructure cathode integrated with NiTi shape memory alloy to realize a shape memory fibrous zinc-ion battery (SFZIB). Manganese oxide (MnO₂) is widely used in AZIBs because of its crystal structure, which is conducive to ion diffusion and storage. However, rapid capacity fading and materials dissolution limit its development as a positive electrode for AZIBs. Herein, (rGO layers are coated on MnO₂ to improve the performance as the cathode for AZIBs. Meanwhile, using NiTi memory alloy wire as the flexible substrate, the SFZIB with shape memory function is prepared. Coating rGO layers effectively inhibit the dissolution of MnO₂, while providing more ion adsorption sites and charge transfer channels, thereby enhancing ion transfer kinetics. After 1000 cycles charge and discharge, Zn//rGO@MnO₂-20 has a capacity retention rate of 83.8%. It is worth noting that when assembled into a quasi-solid-state SFZIB, it showed good flexibility and unique shape memory properties, with a 90.6% capacity retention rate after 200 bending shape recovery. We also demonstrate the application of SFZIB in road traffic. For instance, it can be used in combination with solar panels on highway sections. When there is sufficient ultraviolet light during the daytime, the solar panels power the warning lights, while at night, the warning lights are powered by SFZIB.