Three-Dimensional Conductive Interface and Tip Structure of MnO₂ Electrode Facilitate Superior Zinc Ion Batteries

Manganese dioxide has been significantly utilized in zinc ion batteries (ZIBs). However, in the rechargeable battery system, the manganese dioxide cathode suffers from poor conductivity, volume expansion, and substance dissolution, resulting in low capacity and poor stability. Herein, a 3D frame structure MnO₂@CNTs cathode is proposed. In this system, the electrodeposited spherical MnO₂ is anchored and interlinked via the in-situ growth carbon nanotubes (CNTs) onto the carbon cloth. Benefiting the unique 3D frame structure, the MnO₂ structure crush problem and the pathway of the electrons and ions are dramatically improved. The optimized MnO₂@CNTs cathode demonstrate a high capacity of 256.35 mAh g⁻¹ at 0.1 A g⁻¹ and exceptional cycling stability. Furthermore, in-situ Raman spectroscopy elucidates the energy storage mechanism of aqueous ZIBs (AZIBs). Moreover, COMSOL finite elements analysis demonstrates that the petal edge-rich nanostructures of MnO₂@CNTs generate a localized high electric field under constant current, accelerating ion/electron transfer. This work explains the rationale for CNTs to improve the properties of MnO₂ cathodes, providing a new perspective for the design of high-performance batteries.