Boosting Zn-ion storage capability of self-standing Zn-doped Co₃O₄ nanowire array as advanced cathodes for high-performance wearable aqueous rechargeable Co//Zn batteries

Neutral aqueous rechargeable Co₃O₄//Zn batteries with high-output voltage and outstanding cycling stability have yielded new insights into wearable energy-storage devices. To meet the increasing demand for a means of powering wearable and portable devices, the development of a high-performance fiber-shaped Co//Zn battery would be highly desirable. However, the intrinsically poor conductivity of Co₃O₄ significantly restricts the application of these high-capacity and high-rate aqueous rechargeable battery. Encouragingly, density functional theory (DFT) calculations demonstrate that the substitution of Zn for Co³⁺ leads to an insulator-metal transition in the Zn-doped Co₃O₄ (Zn-Co₃O₄). In this study, we used metallic Zn-Co₃O₄ nanowire arrays (NWAs) as a novel binder-free cathode to successfully fabricate an all-solid-state fiber-shaped aqueous rechargeable (AFAR) Co//Zn battery. The resulting fiber-shaped Co//Zn battery takes advantage of the enhanced conductivity, increased capacity, and improved rate capability of Zn-Co₃O₄ NWAs to yield a remarkable capacity of 1.25 mAh·cm⁻² at a current density of 0.5 mA·cm⁻², extraordinary rate capability (60.8% capacity retention at a high current density of 20 mA·cm⁻²) and an admirable energy density of 772.6 mWh·cm⁻³. Thus, the successful construction of Zn-Co₃O₄ NWAs provides valuable insights into the design of high-capacity and high-rate cathode materials for aqueous rechargeable high-voltage batteries.[Figure not available: see fulltext.]