A Dilute Fluorinated Phosphate Electrolyte Enables 4.9 V-Class Potassium Ion Full Batteries,Advanced Functional Materials

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A Dilute Fluorinated Phosphate Electrolyte Enables 4.9 V-Class Potassium Ion Full Batteries
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-07-10 , DOI: 10.1002/adfm.202305829
Yueteng Gao ₁ , Wei Li ₁ , Boning Ou ₁ , Shuhua Zhang ₁ , Huwei Wang ₁ , Junyang Hu ₁ , Feiyu Kang ₁ , Dengyun Zhai ₁

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Potassium ion batteries using graphite anode and high-voltage cathodes are considered to be optimizing candidates for large-scale energy storage. However, the lack of suitable electrolytes significantly hinders the development of high-voltage potassium ion batteries. Herein, a dilute (0.8 m) fluorinated phosphate electrolyte is proposed, which exhibits extraordinary compatibility with both graphite anode and high-voltage cathodes. The phosphate solvent, tris(2,2,2-trifluoroethyl) phosphate (TFP), has weak solvating ability, which not only allows the formation of robust anion-derived solid electrolyte interphase on graphite anode but also effectively suppresses the corrosion of Al current collector at high voltage. Meanwhile, the high oxidative stability of fluorinated TFP solvent enables stable ultrahigh-voltage (4.95 V) cycling of a potassium vanadium fluorophosphate (KVPO₄F) cathode. Using TFP-based electrolyte, the 4.9 V-class potassium ion full cell based on graphite anode and KVPO₄F cathode shows rather remarkable cycling performance with a high capacity retention of 87.2% after 200 cycles. This study provides a route to develop dilute electrolytes for high-voltage potassium ion batteries, by utilizing solvents with both weak solvating ability and high oxidative stability.

中文翻译：

稀氟化磷酸盐电解质可用于 4.9 V 级钾离子全电池

使用石墨阳极和高压阴极的钾离子电池被认为是大规模储能的优化候选者。然而，缺乏合适的电解质严重阻碍了高压钾离子电池的发展。在此，提出了一种稀（0.8 m）氟化磷酸盐电解质，它与石墨阳极和高压阴极都表现出非凡的相容性。磷酸盐溶剂磷酸三(2,2,2-三氟乙基)酯(TFP)具有弱溶剂化能力，不仅可以在石墨阳极上形成牢固的阴离子衍生固体电解质界面，而且可以有效抑制Al电流的腐蚀集电极处于高电压。_{同时，氟化TFP溶剂的高氧化稳定性使得氟磷酸钒钾（KVPO 4} F ）阴极能够稳定的超高压（4.95 V）循环。采用TFP基电解液，基于石墨阳极和KVPO ₄ F阴极的4.9V级钾离子全电池表现出相当出色的循环性能，200次循环后容量保持率高达87.2%。该研究提供了一种利用弱溶剂化能力和高氧化稳定性的溶剂开发高压钾离子电池稀电解质的途径。

更新日期：2023-07-10

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