Sariyer Selin, Keppetipola Nilanka M, Sel Ozlem, Demir-Cakan Rezan
Chemical Engineering, Gebze Technical University, 41400, Gebze, Kocaeli, Turkey.
Chimie du Solide et de l'Energie UMR 8260, CNRS, Collège de France, 75231, Paris Cedex 05, France.
ChemSusChem. 2025 May 19;18(10):e202402445. doi: 10.1002/cssc.202402445. Epub 2025 Feb 11.
This contribution uses a rapid microwave-assisted hydrothermal synthesis method to produce a vanadium-based KMnVO ⋅ HO cathode material (quoted as KMnVOH). The electrochemical performance of KMnVOH is tested in an aqueous electrolyte, which exhibits a remarkable specific capacity of 260 mAh g at 5 C and retains 94 % of its capacity over 2000 cycles. In contrast to the aqueous electrolyte, the KMnVOH electrode tested in the organic electrolyte provides a modest discharge capacity of 60 mAh g at C/10, and the electrogravimetric analysis indicates that the charge storage mechanism is solely due to non-solvated Zn intercalation. In aqueous electrolyte tests, Zn species insertion, interfacial pH increase, and subsequent formation of Zn(OH)(CFSO) ⋅ nHO (ZHT) are supported by in-situ EQCM. Ex-situ XRD measurements also confirm the ZHT formation and its characteristic plate-like structure is observed by SEM. The ion diffusion coefficient values in aqueous and non-aqueous electrolytes are very similar according to the GITT analysis, while it is expected to be higher in aqueous electrolytes. These results may further emphasize the complex redox dynamics in the aqueous electrolyte, namely the difficulty of intercalation of bare Zn, strong Zn solvation in the bulk electrolyte, solvent or proton intercalation, and ZHT formation.
本研究采用快速微波辅助水热合成法制备了钒基KMnVO₄·H₂O正极材料（简称KMnVOH）。在水性电解质中测试了KMnVOH的电化学性能，其在5C下展现出260 mAh g的显著比容量，并在2000次循环后仍保留其容量的94%。与水性电解质不同，在有机电解质中测试的KMnVOH电极在C/10下提供了60 mAh g的适度放电容量，并且电重量分析表明电荷存储机制仅归因于非溶剂化的Zn嵌入。在水性电解质测试中，原位石英晶体微天平（EQCM）证实了Zn物种的嵌入、界面pH值的增加以及随后Zn(OH)(CF₃SO₃)·nH₂O（ZHT）的形成。非原位X射线衍射（XRD）测量也证实了ZHT的形成，并且扫描电子显微镜（SEM）观察到了其特征性的板状结构。根据恒电流间歇滴定技术（GITT）分析，水性和非水性电解质中的离子扩散系数值非常相似，而预计在水性电解质中该值会更高。这些结果可能进一步强调了水性电解质中复杂的氧化还原动力学，即裸Zn嵌入的困难、本体电解质中强烈的Zn溶剂化、溶剂或质子嵌入以及ZHT的形成。
