Enhancing the Supercapacitor Performance of Graphene/MnO₂ Nanostructured Electrodes by Conductive Wrapping

TLDR

MnO₂ is a promising pseudocapacitive material with high theoretical capacitance, yet its performance is limited by poor electronic and ionic conductivities. The study aimed to develop a conductive‑wrapping strategy to enhance the performance of graphene/MnO₂ nanostructured electrodes. The authors applied a 3‑D conductive wrapping of graphene/MnO₂ with carbon nanotubes or conducting polymer to improve charge transport. The wrapped electrodes reached up to ~380 F g⁻¹ specific capacitance, ~20–45 % higher than unwrapped, retained >95 % capacitance after 3000 cycles, demonstrating a promising route for high‑performance supercapacitors.

Abstract

MnO2 is considered one of the most promising pseudocapactive materials for high-performance supercapacitors given its high theoretical specific capacitance, low-cost, environmental benignity, and natural abundance. However, MnO2 electrodes often suffer from poor electronic and ionic conductivities, resulting in their limited performance in power density and cycling. Here we developed a "conductive wrapping" method to greatly improve the supercapacitor performance of graphene/MnO2-based nanostructured electrodes. By three-dimensional (3D) conductive wrapping of graphene/MnO2 nanostructures with carbon nanotubes or conducting polymer, specific capacitance of the electrodes (considering total mass of active materials) has substantially increased by ∼20% and ∼45%, respectively, with values as high as ∼380 F/g achieved. Moreover, these ternary composite electrodes have also exhibited excellent cycling performance with >95% capacitance retention over 3000 cycles. This 3D conductive wrapping approach represents an exciting direction for enhancing the device performance of metal oxide-based electrochemical supercapacitors and can be generalized for designing next-generation high-performance energy storage devices.