Calcium-ion batteries (CIBs) are attractive candidates for energy storage because Ca²⁺ has low polarization and a reduction potential (−2.87 V versus standard hydrogen electrode, SHE) close to that of Li⁺ (−3.04 V versus SHE), promising a wide voltage window for a full battery. However, their development is limited by difficulties such as the lack of proper cathode/anode materials for reversible Ca²⁺ intercalation/de-intercalation, low working voltages (<2 V), low cycling stability, and especially poor room-temperature performance. Here, we report a CIB that can work stably at room temperature in a new cell configuration using graphite as the cathode and tin foils as the anode as well as the current collector. This CIB operates on a highly reversible electrochemical reaction that combines hexafluorophosphate intercalation/de-intercalation at the cathode and a Ca-involved alloying/de-alloying reaction at the anode. An optimized CIB exhibits a working voltage of up to 4.45 V with capacity retention of 95% after 350 cycles.

钙离子电池（CIB）是能量存储的有吸引力的候选人，因为Ca ²⁺具有低极化和还原电势（相对于标准氢电极，SHE为-2.87 V），接近Li ⁺（相对于SHE为-3.04 V），这是有希望的充满电的宽电压窗口。然而，它们的发展受到困难的限制，例如缺乏用于可逆Ca ²⁺的适当阴极/阳极材料。嵌入/脱嵌，低工作电压（<2 V），循环稳定性低，尤其是室温性能较差。在这里，我们报告了一种CIB，它在新的电池配置中可以稳定地在室温下工作，这种配置使用石墨作为阴极，锡箔作为阳极以及集电器。此CIB在高度可逆的电化学反应上运行，该反应将六氟磷酸盐在阴极的嵌入/脱嵌与在阳极处的涉及Ca的合金化/脱合金反应结合在一起。经过优化的CIB表现出的工作电压最高为4.45 V，经过350个循环后，容量保持率为95％。