Hydrous Molybdenum Oxide Coating of Zinc Metal Anode via the Facile Electrodeposition Strategy and Its Performance Improvement Mechanisms for Aqueous Zinc−Ion Batteries

Abstract

Aqueous zinc−ion batteries (ZIBs) are widely recognized as highly promising energy storage devices because of their inherent characteristics, including superior safety, affordability, eco−friendliness, and various other benefits. However, the significant corrosion of the zinc metal anode, side reactions occurring between the anode and electrolyte, and the formation of zinc dendrites significantly hinder the practical utilization of ZIBs. Herein, we utilized an electrodeposition method to apply a unique hydrous molybdenum oxide (HMoOx) layer onto the surface of the zinc metal anode, aiming to mitigate its corrosion and side reactions during the process of zinc deposition and stripping. In addition, the HMoOx layer not only improved the hydrophilicity of the zinc anode, but also adjusted the migration of Zn2+, thus facilitating the uniform deposition of Zn2+ to reduce dendrite formation. A symmetrical cell with the HMoOx−Zn anode displayed reduced−voltage hysteresis (80 mV at 2.5 mA/cm2) and outstanding cycle stability after 3000 cycles, surpassing the performance of the uncoated Zn anode. Moreover, the HMoOx−Zn anode coupled with a γ−MnO2 cathode created a considerably more stable rechargeable full battery compared to the bare Zn anode. The HMoOx−Zn||γ−MnO2 full cell also displayed excellent cycling stability with a charge/discharge−specific capacity of 129/133 mAh g−1 after 300 cycles. In summary, this research offers a straightforward and advantageous approach that can significantly contribute to the future advancements in rechargeable ZIBs.