Advanced flame-retardant electrolyte for highly stabilized K-ion storage in graphite anode

钾离子电池先进阻燃电解质:石墨负极的高稳定储钾

Although graphite anodes operated with representative de/intercalation patterns at low potentials are considered highly desirable for K-ion batteries,the severe capacity fading caused by consecutive reduction reactions on the aggressively reactive surface is inevitable given the scarcity of effective protecting layers.Herein,by introducing a flame-retardant localized high-concentration electrolyte with retentive solvation configuration and relatively weakened anion-coordination and non-solvating fluorinated ether,the rational solid electrolyte interphase characterized by well-balanced inorganic/organic components is tailored in situ.This effectively prevented solvents from excessively decomposing and simultaneously improved the resistance against K-ion transport.Consequently,the graphite anode retained a prolonged cycling capability of up to 1400 cycles(245 mA h g,remaining above 12 mon)with an excellent capacity retention of as high as 92.4%.This is superior to those of conventional and high-concentration electrolytes.Thus,the optimized electrolyte with moderate salt concentration is perfectly compatible with graphite,providing a potential application prospect for K-storage evolution.

在钾离子电池石墨负极中,钾离子在石墨层间嵌入/脱出的模式能够实现储能,且具有较低工作电位和廉价等优势,表现出巨大的吸引力.然而,在缺乏足够界面保护等条件下,石墨负极在传统碳酸酯类电解液中容易发生连续的副反应,充放电容量会面临严重的持续衰减.本文从电解液设计的角度出发,针对石墨负极的钾离子存储问题,配制了阻燃的局部高浓度电解液,其特有的溶剂化结构可调控石墨表面固体电解质界面相,改善界面的结构稳定性和离子传导特性,从而实现石墨负极储钾的高稳定循环.同时,电解液的高阻燃特性也为钾离子电池的高安全性提供了保障.