Introducing PANI\ninto a Manganese-Based Cathode Material\nto Improve the Energy Storage Performance of Aqueous Zinc-Ion Batteries\nby Generating Dual Redox Reactions

Rechargeable manganese dioxide (MnO<sub>2</sub>)-based\naqueous\nzinc-ion batteries (AZIBs) have emerged as potential next-generation\nlarge-scale energy storage devices due to their high theoretical specific\ncapacity, low cost, intrinsic safety, and environmental friendliness.\nHowever, the practical application of manganese-based cathodes is\nlimited by the insufficient utilization of the voltage window, resulting\nin a negligible capacity contribution in the voltage range of 0.8–1.2\nV. Herein, the CNs/PANI/MnO<sub>2</sub> cathode is rationally designed\nand synthesized by combining two redox active materials (PANI and\nMnO<sub>2</sub>) with complementary voltage windows using highly conductive\nand low-cost carbon nanospheres (CNs) as the substrate. The redox\nreactions of polyaniline (PANI) in the voltage range of 0.8–1.2\nV strengthen the diffusion-controlled process and make up the capacity\ncontribution to further improve the energy storage efficiency of AZIBs\nover the entire voltage window. After controllable structural and\ncomposition optimization, the CNs/PANI/MnO<sub>2</sub> cathode delivered\na maximum specific capacity of 363.4 mAh g<sup>–1</sup> at\n0.2 A g<sup>–1</sup>. Moreover, the presence of PANI protected\nMnO<sub>2</sub> from degradation during the charge–discharge\nprocess to achieve excellent cycling stability with 99.6% capacity\nretention after 10,000 cycles. This study provides a feasible approach\nfor designing high-performance AZIB electrodes by generating dual\nredox reactions.