Zinc-ion batteries (ZIBs) have emerged as a promising candidate due to the abundance, low cost and high energy density. However, the performance of ZIBs needs to be improved to meet the practical requirements of energy storage systems. This work probes the efficacy of co-intercalation as a strategy for enhancing the electrochemical performance of ZIBs through the fabrication of sodium and copper co-intercalated birnessite manganese oxide (NCMO) cathodes. The results show that the co-intercalation of sodium and copper ions catalyzes the activation of copper cations on the surface Mn2+/Mn4+ redox pair, leading to improved specific capacity and cycling stability. The NCMO cathode exhibits a remarkable specific capacity of 576 mA h g−1 after 100 cycles at a low loading of around ∼1 mg cm−2 and a high areal capacity of 2.10 mA h cm−2 at a high loading of ∼10.9 mg cm−2. The mechanism of copper ions to promote the manganese-based cathode conversion reaction is thoroughly investigated. These findings suggest that developing catalytic effects is a promising approach for developing high-performance cathode materials for ZIBs with practical and efficient energy storage systems.

Xuan Gao thanks University College London and China Scholarship Council for the joint PhD scholarship. The authors acknowledge the Engineering and Physical Sciences Research Council (EPSRC, EP/V027433/3) and UK Research and Innovation (UKRI) under the UK government's Horizon Europe funding guarantee (101077226; EP/Y008707/1) for funding support.