Improved performance of Cu ion implanted δ-MnO2 cathode material for aqueous Zn-ion batteries

Aqueous Zn-ion batteries (ZIBs) are considered as a potential large-scale renewable energy storage system. Herein, Cu ion implantation is used to improve the electrochemical performance of δ-MnO2, resulting in a mixed layer-tunnel material δ-MnO2 (Cu@δ-MnO2) with high capacity, excellent cycle performance, and rate performance as cathode for aqueous ZIBs. The as-obtained Cu@δ-MnO2 cathode shows a high specific capacity of 470 mAhg−1 at 0.1 Ag−1 and maintains a higher specific capacity during long-term cycles of up to 300 times. Meanwhile, the first-principles theoretical simulations suggest the easier migration of Zn2+ and more Zn2+ adsorption on Cu@δ-MnO2 cathode. The theoretical and experimental results show that Cu ion implantation may be an effective strategy to improve the device performance of the Mn-based layer-tunnel hybrid cathode.