Design of LiF-rich solid electrolyte interface layer through salt-additive chemistry for boosting fast-charging phosphorus-based lithium ion batteries performance

Lithium ion battery using phosphorus as an anode is considered as a promising energy storage system because of its high energy density and safe lithiation voltage (ca. 0.7 V vs. Li+/Li). However, high volumetric expansion associated with unstable phosphorus/electrolyte interface along with limited cycle life, especially at high current densities, hinder its practical uses. Here we report that an amount (3 wt.%) of fluoroethylene carbonate as an additive in 4.5 M lithium bis(fluorosulfonyl) imide-DME electrolytes significantly improves the fast-charging capacity and cycling stability of phosphorus anode, such as a high fast-charging retention of 74.5% from the 10th to 450th cycle and a high reversible capacity of 450 mA h g‒1 after 450 cycles with a high charging current density of 8 A g‒1 (about 3 min) and a discharging current density of 0.15 A g‒1. The fast charging and stable cycling performances are attributed to the generation of a robust and conductive LiF-rich solid electrolyte interphase at the phosphorus surface and the stabilization of the interface between phosphorus and electrolyte.