Vertical & lateral ion-flux modulated ion-conductive SEI for high-performance Li-metal batteries

Abstract

Ideal solid electrolyte interphase (SEI) is required for non-dendrite lithium (Li) deposition of lithium metal batteries (LMBs). However, the spontaneously-formed SEI is non-homogenous in the composition and structure and thus cause oriented distribution of Li⁺ flux, which leads to the detrimental formation of lithium dendrites and poor cyclability of batteries. Here we propose a vertical & lateral ion-flux modulated ion-conductive SEI for high-voltage Li-metal batteries. A fluorinated MCM-41 (FMCM-41) modified LiPF₆ electrolyte is designed to construct the SEI film, which consists of homogenously distributed LiF and Li_xSiO_y, to regulate Li⁺ transport paths in the lateral and the vertical direction, respectively, achieving uniform lithium plating. With the FMCM-41 modified electrolyte, the prepared Li||Li cell presents a long-term stability over 1000 h, and the Li||NCM622 full cell exhibits outstanding cycling performance with a high specific capacity of 169.9 mAh g^-1 and a high-capacity retention of 93.3 % over 100 cycles at 0.5 C. This lateral-vertical concept provides a promising strategy for designing a desired SEI with uniform Li⁺ transport paths to achieve ultra-long and high-rates lithium metal batteries.