Engineering functional groups of ZnMn2O4/GO composite nanofibers for efficient and stable supercapacitors

Abstract

Spinel ZnMn₂O₄ (ZMO) is a promising supercapacitor materials due to its high theoretical capacity, non-toxic, and more environmental benefits. However, traditional ZMO suffers from poor conductivity and instability, limiting its performance. To address these issues, we incorporated graphene oxide (GO) into ZMO, forming mesoporous ZMO/GO nanofibers (NFs) with a large specific surface area via electrospinning and further annealing. GO doping introduces oxygen-containing functional groups that add active sites for ion adsorption and increase electrode conductivity, as confirmed by COMSOL simulations, showing a rise in maximum current density from 6976 A m⁻² to 15705 A m⁻². The NF structure also prevents GO aggregation, enhancing ion transport and stabilizing ZMO. Consequently, the ZMO/GO3 electrode achieves a high specific capacitance (1489.5 F g⁻¹ at 1 A g⁻¹ with 0.3 wt% GO) and excellent electrochemical performance. The asymmetric supercapacitor (ZMO/GO3//AC) with activated carbon achieves an energy density of 22.04 Wh kg⁻¹ at 799.84 W kg⁻¹ and retains 91.3 % capacitance after 5000 cycles at 5 A g⁻¹, capable of powering an LED. This approach underscores ZMO's potential for high-power supercapacitor applications.