Potassium-ion batteries are an emerging energy storage technology that could be a promising alternative to lithium-ion batteries due to the abundance and low cost of potassium. Research on potassium-ion batteries has received considerable attention in recent years. With the progress that has been made, it is important yet challenging to discover electrode materials for potassium-ion batteries. Here, we report pyrrhotite Fe_1−xS microcubes as a new anode material for this exciting energy storage technology. The anode delivers a reversible capacity of 418 mAh g⁻¹ with an initial coulombic efficiency of ~70% at 50 mA g⁻¹ and a great rate capability of 123 mAh g⁻¹ at 6 A g⁻¹ as well as good cyclability. Our analysis shows the structural stability of the anode after cycling and reveals surface-dominated K storage at high rates. These merits contribute to the obtained electrochemical performance. Our work may lead to a new class of anode materials based on sulfide chemistry for potassium storage and shed light on the development of new electrochemically active materials for ion storage in a wider range of energy applications.

钾离子电池是一种新兴的储能技术，由于钾含量丰富且成本低，它可能成为锂离子电池的有前途的替代品。近年来，钾离子电池的研究备受关注。随着已经取得的进展，发现钾离子电池的电极材料既重要又具有挑战性。在这里，我们报告了磁黄铁矿 Fe _{1− x} S 微立方体作为这种令人兴奋的储能技术的新型负极材料。阳极提供 418 mAh g ^-1的可逆容量，在 50 mA g ^{-1 时}初始库仑效率约为 70%，在 6 A g ^-1时具有 123 mAh g ^-1的高倍率容量以及良好的循环性。我们的分析显示了循环后阳极的结构稳定性，并揭示了高速率下表面主导的 K 存储。这些优点有助于获得电化学性能。我们的工作可能会产生一种基于硫化物化学的新型负极材料，用于储存钾，并为在更广泛的能源应用中开发用于离子储存的新型电化学活性材料提供启示。