Controllable construction of a “rigid-flexible integrated” solid electrolyte interphase to enhance the stability of lithium metal anodes

Abstract

The repeated and significant volume changes occurring in lithium metal during charge-discharge processes exacerbate the rupture of the solid electrolyte interphase (SEI), which constitutes one of the key factors responsible for the diminished stability of lithium metal anodes. Regulating the mechanical flexibility of the SEI layer represents an effective strategy to mitigate the volume expansion effect. Here, a controllable Li3N/LiCl electrolyte interphase layer (SEI) on the lithium anode surface is in-situ formed with molecule 3-chloro-1,2,4-triazole. Through the moderation of Li3N's rigidity by LiCl's flexibility, after 500 cycles of the Li||Li symmetric battery, the thickness growth rate of the SEI layer at the lithium metal interface decreases from 2.1 times to 1.2 times. Under a current density of 1 mA cm−2 and a capacity of 1 mA h cm−2, the Li||Li symmetric battery with a Li3N/LiCl-Li anode achieves a cycle life of 750 h, while the voltage polarization remains stable at around 24 mV. The Li-S battery with Li3N/LiCl-Li anode shows a capacity decay rate of only 0.139 % after 110 cycles at 0.2C, and maintains excellent cycling performance even under high sulfur loading/low electrolyte/sulfur ratio and high current density of 1C.