The crystal phase structure of cathode material plays an important role in the cell performance. During cycling, the cathode material experiences immense stress due to phase transformation, resulting in capacity degradation. Here, we show phase-engineered VO₂ as an improved potassium-ion battery cathode; specifically, the amorphous VO₂ exhibits superior K storage ability, while the crystalline M phase VO₂ cannot even store K⁺ ions stably. In contrast to other crystal phases, amorphous VO₂ exhibits alleviated volume variation and improved electrochemical performance, leading to a maximum capacity of 111 mAh g⁻¹ delivered at 20 mA g⁻¹ and over 8 months of operation with good coulombic efficiency at 100 mA g⁻¹. The capacity retention reaches 80% after 8500 cycles at 500 mA g⁻¹. This work illustrates the effectiveness and superiority of phase engineering and provides meaningful insights into material optimization for rechargeable batteries.

正极材料的晶相结构对电池性能起着重要作用。在循环过程中，正极材料由于相变而承受巨大的应力，导致容量下降。在这里，我们展示了相工程 VO ₂作为改进的钾离子电池阴极；具体地，非晶VO ₂表现出优异的K存储能力，而结晶M相VO ₂甚至不能稳定地存储K ⁺离子。与其他晶相相比，非晶态 VO ₂表现出较小的体积变化和改进的电化学性能，在 20 mA g ^-1下的最大容量为 111 mAh g ^-1 ，并且在 100 mA 下具有良好的库仑效率，可运行超过 8 个月。 g ^-1 。在500 mA g ^-1下循环8500次后容量保持率达到80%。这项工作说明了相工程的有效性和优越性，并为可充电电池的材料优化提供了有意义的见解。