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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.
This work was supported by the National Natural Science Foundation of China (No. 51703241), the Fundamental Research Funds for the Central Universities (No. 020514380183), the Key Research Program of Frontier Science of Chinese Academy of Sciences (No. QYZDB-SSW-SLH031), and the Science and Technology Project of Nanchang (No. 2017-SJSYS-008).