Poly(3,4-ethylenedioxythiophene)-Coated Vanadium-Doped MnO₂ Nanorods for High-Performance Flexible Aqueous Zinc-Ion Battery Cathode

Manganese-based aqueous zinc-ion batteries (AZIBs) are considered promising cathode materials for large-scale energy storage applications due to their low cost and high safety. However, the primary constraints on achieving high specific capacity and cycling stability are the inherent low conductivity and suboptimal structural stability of the AZIB cathodes. Herein, we report a high-performance poly(3,4-ethylenedioxythiophene) (PEDOT)-coated vanadium-doped MnO₂ nanorod (NR) electrode for AZIBs. First, vanadium-doped MnO₂ (V-MnO₂) NRs were synthesized by a simple hydrothermal synthesis method. The V-MnO₂ NRs were further encapsulated with a nanolayer of PEDOT through an <i>in situ</i> polymerization process, which was subsequently treated with sulfuric acid to achieve a smooth surface. The V doping creates oxygen vacancies within the MnO₂, allowing for the rapid embedding and diffusion of Zn²⁺. The PEDOT nanolayer greatly enhances the conductivity and structural stability of the V-MnO₂. Benefiting from the unique features, an optimal composite NRs electrode exhibits a high specific capacity of 250 mAh g^-1 at 0.4 A g^-1, a high energy density (388 Wh kg^-1 at 151 W kg^-1), and excellent stability over 5000 cycles at 3 A g^-1. In addition, the flexible pouch cell assembled with the electrode shows good stability under bending. Given the positive outcomes, the material holds great potential for use as a cathode in next-generation flexible energy storage systems.