Qiao Fan, Wang Junjun, Yu Ruohan, Pi Yuqiang, Huang Meng, Cui Lianmeng, Liu Ziang, An Qinyou
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, P. R. China.
School of Chemistry and Materials Science, Hubei Engineering University, Xiaogan, 432000, P. R. China.
Small Methods. 2024 Jan;8(1):e2300865. doi: 10.1002/smtd.202300865. Epub 2023 Oct 6.
Aqueous Ca-ion batteries (ACIBs) attract immense attention due to its high safety and the high abundance of calcium. However, the development of ACIBs is hindered by the lack of high voltage cathode materials to host the large radius and divalent Ca . Herein, polyanionic phosphate K V (PO ) /C (KVP/C) is provided as a new cathode material for ACIBs. Due to the robust structure of polyanion material and the wide electrochemical window of water-in-salt electrolyte, KVP/C delivers a high working voltage of 3.74 V versus Ca /Ca with a specific capacity of 102.4 mAh g and a long-life of 6000 cycles at 500 mA g . Furthermore, the calcium storage mechanism of KVP/C is shown to be the coexistence of solid solution and two-phase reaction by in situ X-ray diffraction, ex situ transmission electron microscope, and X-ray photoelectron spectroscopy. Finally, an aqueous calcium-ion full cell, based on an organic compound as anode and KVP/C as cathode, is constructed and it shows good stability for 200 cycles and a specific capacity of 80.2 mAh g . This work demonstrates that vanadium-based phosphate materials are promising high-voltage cathode materials for ACIBs and renew the prospects for ACIBs.
水系钙离子电池（ACIBs）因其高安全性和钙的高丰度而备受关注。然而，由于缺乏能够容纳大半径二价钙离子的高电压阴极材料，ACIBs的发展受到了阻碍。在此，提供了聚阴离子磷酸盐K V (PO ) /C（KVP/C）作为ACIBs的新型阴极材料。由于聚阴离子材料的坚固结构和盐水电解质的宽电化学窗口，KVP/C相对于Ca /Ca具有3.74 V的高工作电压，比容量为102.4 mAh g ，在500 mA g 下具有6000次循环的长寿命。此外，通过原位X射线衍射、非原位透射电子显微镜和X射线光电子能谱表明，KVP/C的钙存储机制是固溶体和两相反应的共存。最后，构建了一种以有机化合物为阳极、KVP/C为阴极的水系钙离子全电池，其在200次循环中表现出良好的稳定性，比容量为80.2 mAh g 。这项工作表明，钒基磷酸盐材料是有前景的ACIBs高电压阴极材料，并为ACIBs带来了新的前景。
