Rational design of oxygen-vacancy-rich manganese dioxide nanowires with conductive poly(3,4-ethylenedioxythiophene) skin for high-performance flexible aqueous zinc-ion batteries

Manganese dioxide (MnO₂) nanowires represent attractive materials for flexible energy storage, yet they remain hampered by structural instability during cycling and poor electronic conductivity. Here, we develop a synergistic multiscale engineering strategy via a single-step process that concurrently introduces oxygen vacancies and applies a conformal conductive poly(3,4-ethylenedioxythiophene) (PEDOT) coating, thereby creating O_v-MnO₂@PEDOT core–shell heterostructures. This rational design harnesses the mechanical integrity of nanowires, the metallic conductivity of PEDOT, and vacancy-facilitated ion diffusion and charge storage. When implemented as binder- and substrate-free electrodes for aqueous zinc-ion batteries (ZIBs), the material delivers a high specific capacity of 296.8 mAh g⁻¹ at 0.1 A g⁻¹, favorable rate performance (113.3 mAh g⁻¹ at 5.0 A g⁻¹), and unprecedented cycling stability—retaining 91.3% capacity of its capacity after 10,000 cycles under 3 A g⁻¹. A notable capacity of 237.4 mAh g⁻¹ is achieved relative to the total electrode mass. Mechanistic analysis reveals that oxygen vacancies significantly enhance electrical conduction and Zn²⁺ storage kinetics. Flexible devices maintain operational performance under mechanical deformation, confirming their applicability in wearable electronics. This work establishes a generalizable materials design paradigm that is extendable to other metal oxides for advanced flexible energy storage.