Mao Zhifei, Wang Huanwen, Zhang Taoqiu, Wang Yifeng, Zhou Wanhai, Chao Dongliang
Faculty of Material and Chemistry, China University of Geosciences, Wuhan 430074, China.
Laboratory of Advanced Materials, Aqueous Battery Center, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Shanghai Wusong Laboratory of Materials Science, College of Smart Materials and Future Energy, Fudan University, Shanghai 200433, China.
J Am Chem Soc. 2025 Sep 17;147(37):34059-34069. doi: 10.1021/jacs.5c11948. Epub 2025 Sep 5.
Potassium-ion batteries (PIBs) have emerged as an appealing, sustainable and cost-effective candidate for grid-scale energy storage due to abundant K resources and reversible K de/intercalation in graphite anodes (KC, 279 mAh g). However, their practical operation suffers from sluggish kinetics and severe capacity deterioration in traditional carbonate electrolytes. Herein, ethoxy (pentafluoro) cyclotriphosphazene (PFPN) and methyl (2,2,2-trifluoroethyl) carbonate (FEMC) are introduced as cosolvents to rejuvenate conventionally low-concentration (1 M) 1,2-dimethoxyethane (DME)-based electrolytes. In the resultant 1 M KFSI-DME/PFPN/FEMC (3 vol %) electrolyte, the cyclotriphosphazene group of PFPN is revealed to not only mitigate the flammability of DME but also diminish the K-DME interaction through steric hindrance. While FEMC preempts the DME-induced corrosion of the potassium anode by facilitating the formation of a KF-enriched interface. Consequently, ether cointercalation into graphite is successfully suppressed in K||graphite cells, exhibiting 96% capacity retention over 1800 cycles (a running time of 402 days). When the temperature drops from 50 to -20 °C, the K-ion full device retains a capacity as high as 89%. The study introduces a novel electrolyte regulation strategy that harmonizes intrinsic safety, rapid kinetics at subzero temperatures, and enduring cycle stability at the same time, thereby advancing the practical implementation of PIBs for the future.
