通过电解液添加剂构筑富含LiF/Li_(2)CO_(3)异质结构的电极-电解质界面以实现4.5V锂金属电池的稳定循环

Constructing LiF/Li2CO3-rich heterostructured electrode electrolyte interphases by electrolyte additive for 4.5 V well-cycled lithium metal batteries

高压Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)电池的循环性能取决于电极和电解质之间的界面稳定性.然而,在高电压下实现它们是具有挑战性的本文以五氟苯乙烯(PFBE)为添加剂,通过电解液工程稳定了4.5VLi||NCM811电池.添加剂PFBE有助于在NCM811阴极和锂金属阳极表面形成高导锂和机械坚固的富含无机组分LiF/Li_(2)CO_(3)的异质结构界面.这种电极-电解质界面(EEIs)明显缓解了富镍层状阴极中不可逆相变、应力积累引起的微裂纹和过渡金属溶解.同时,有效地控制了锂金属阳极表面锂枝晶的生长,结果表明,4.5VLi||NCM811电池在0.5C(100mAg)下循环600次后,容量保持率为61.27%.此外,在含有这种电解质添加剂中循环的Li||NCM811软包电池可以实现稳定的、高达~485Whkg^(-1)的能量密度.

The cycling performance of promising high-voltage Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)batteries is determined by the interfacial stability between electrodes and electrolyte.However,it is challenging to achieve them under high voltage.Herein,we stabilized 4.5 V Li||NCM811 batteries via electrolyte engineering with pentafluorostyrene(PFBE)as the additive.PFBE contributes to the formation of highly Li^(+) conductive and mechanically robust LiF/Li_(2)CO_(3)-rich heterostructured interphases on NCM811 cathode and Li metal anode(LMA)surfaces.Such electrode-electrolyte interphases(EEIs)obviously alleviate irreversible phase transition,microcracks induced by stress accumulation and transition metal dissolution in the Ni-rich layered cathode.Meanwhile,the growth of Li dendrites on the LMA surface is effectively controlled.As expected,4.5 V Li||NCM811 batteries sustain a capacity retention rate of 61.27%after 600 cycles at 0.5 C(100 mA g^(-1)).More importantly,~6.69 Ah Li||NCM811 pouch cells with such electrolytes could represent a stable energy density of ~485 Wh kg^(-1) based on all cell components.