Development of High Areal Capacity Electrolytic MnO 2 –Zn Battery via an Iodine Mediator

The commercialization of electrolytic MnO 2 –Zn batteries is highly applauded owing to the advantages of cost‐effectiveness, high safety, high energy density, and durable working performance. However, due to the low reversibility of the cathode MnO 2 /Mn 2+ chemistry at high areal capacities and the severe Zn anode corrosion, the practical application of MnO 2 –Zn batteries is hampered by inadequate lifespan. Leveraging the full advantage of an iodine redox mediator, here we design a highly rechargeable electrolytic MnO 2 –Zn battery with a high areal capacity. The MnO 2 –Zn battery coupled with an iodine mediator in a mild electrolyte shows a high discharge voltage of 1.85 V and a robust areal capacity of 10 mAh cm −2 under a substantial discharge current density of 160 mA cm −2 . The MnO 2 /I 2 –Zn battery with an areal capacity of 10 mAh cm −2 exhibits prolonged stability of over 950 cycles under a high‐capacity retention of ~94%. The scaled‐up MnO 2 /I 2 –Zn battery reveals a stable cycle life under a cell capacity of ~600 mAh. Moreover, our constructed MnO 2 /I 2 –Zn battery demonstrates a practical energy density of ~37 Wh kg −1 and a competitive energy cost of <18 US$ kWh −1 by taking into account the cathode, anode, and electrolyte. The MnO 2 /I 2 –Zn battery, with its remarkable reversibility and reasonable energy density, enlightens a new arena of large‐scale energy storage devices.