Electrochemical characterization of hollow urchin-like MnO2 as high-performance cathode for aqueous zinc ion batteries

Aqueous zinc-ion batteries (AZIBs) based on MnO 2 cathode and Zn anode has attracted an increased attention for energy storage for their low cost, high safety and environmental friendliness . However, the essentially poor conductivity and unstable structure change of MnO 2 cathode during electrochemical reaction usually lead to low discharge capacity and rapid fading for AZIBs. To alleviate these problems, a hollow urchin-like MnO 2 was synthesized by a modified one-step hydrothermal method . The as-proposed unique morphology with large surface can effectively shorten the ion diffusion distance and alleviate the collapse of the structure. The urchin-like MnO 2 cathode shows a high reversible specific capacity of 324.9 mAh g −1 at 0.1 A g −1 (0.32C). Meanwhile, a long-term stability up to 5000 cycles with a retained capacity of 124 mAh g −1 at a high current density of 1.5 A g −1 (5C) is obtained, which is obviously superior to a common spherical MnO 2 . Ex-situ analysis reveals a H + and Zn 2+ co-insertion reaction mechanism for the as-obtained cathode. The remarkably electrochemical performance suggests the hollow urchin-like MnO 2 a promising cathode for AZIBs.