Rechargeable calcium-ion batteries are intriguing alternatives for use as post-lithium-ion batteries. However, the high charge density of divalent Ca²⁺ establishes a strong electrostatic interaction with the hosting lattice, which results in low-capacity Ca-ion storage. The ionic radius of Ca²⁺ further leads to sluggish ionic diffusion, hindering high-rate capability performances. Here, we report 5,7,12,14-pentacenetetrone (PT) as an organic crystal electrode active material for aqueous Ca-ion storage. The weak π-π stacked layers of the PT molecules render a flexible and robust structure suitable for Ca-ion storage. In addition, the channels within the PT crystal provide efficient pathways for fast ionic diffusion. The PT anode exhibits large specific capacity (150.5 mAh g^-1 at 5 A g^-1), high-rate capability (86.1 mAh g^-1 at 100 A g^-1) and favorable low-temperature performances. A mechanistic study identifies proton-assisted uptake/removal of Ca²⁺ in PT during cycling. First principle calculations suggest that the Ca ions tend to stay in the interstitial space of the PT channels and are stabilized by carbonyls from adjacent PT molecules. Finally, pairing with a high-voltage positive electrode, a full aqueous Ca-ion cell is assembled and tested.

可充电钙离子电池是用作后锂离子电池的有趣替代品。但是，二价Ca ²⁺的高电荷密度与主体晶格建立了强大的静电相互作用，导致低容量的Ca离子存储。Ca ²⁺的离子半径进一步导致缓慢的离子扩散，从而阻碍了高倍率性能。在这里，我们报告了5,7,12,14-戊烯酮（PT）作为用于含水Ca离子存储的有机晶体电极活性材料。PT分子的弱π-π堆叠层提供了适用于Ca离​​子存储的灵活而坚固的结构。此外，PT晶体内的通道为快速的离子扩散提供了有效的途径。PT阳极具有大比容量（150.5 mAh g^-1在5 A G ^-1），高倍率性能（86.1毫安克^-1在100克^-1）和良好的低温性能。一项机械研究确定了骑自行车过程中质子辅助摄取/清除了PT中的Ca ²⁺。第一原理计算表明，Ca离子倾向于保留在PT通道的间隙中，并被来自相邻PT分子的羰基稳定。最后，与高压正极配对，组装并测试完整的含水Ca离子电池。