In situ synthesis of a self-supported MnO2-based cathode for high-performance zinc-ion batteries by K+ pre-intercalation

Abstract

Aqueous zinc-ion batteries (ZIBs) have attracted extensive research interest due to their multiple advantages, such as high safety, low cost, environmental friendliness, and suitability for large-scale energy storage systems. However, the further development and application of ZIBs is hindered by the sluggish reaction kinetics, low electrical conductivity, and unstable crystal structure of cathode materials. Here, a self-supporting cathode of K+ intercalated MnO2 on three-dimensional layered carbon-based conductive substrate (LGP) (LGP@K0.15MnO2) without binder and conductive agent was synthesized by two simple steps. The synergistic effect of the three-dimensional layered carbon conductive network and pre-intercalated K+ ions in LGP@K0.15MnO2 can effectively stabilize the material structure, promote electrical conductivity, and facilitate ion diffusion. Therefore, the obtained LGP@K0.15MnO2 exhibited a high specific capacity and excellent cycling stability, which delivered 358.9 mAh/g for the first cycle at a current density of 200 mA/g, and maintained 92.5% of the capacity after 100 cycles. In addition, a capacity retention rate of 83.3% after 1000 cycles at 1000 mA/g was obtained. It was also found that the pre-intercalation of excess K+ ions would adversely affect the crystal structure and electrochemical performance of cathode materials.