Expanding the reversibility of graphite-Li metal hybrid anodes by interface and inner-structure modifications

Abstract

• Expanding the reversibility of graphite-Li metal hybrid anodes by chemical (SEI modifications) and physical (preset voids in electrodes) synergetic strategies are proposed. • High coulombic efficiency is achieved for the hybrid graphite-Li metal hybrid anodes. • We construct a high-energy-density hybrid graphite-Li metal anode in a carbonate-based electrolyte with lithiation up to 500 mAh/g. For high-specific energy Li batteries, hybrid anodes with graphite and Li metal are promising. However, the degradation of graphite-Li metal hybrid anodes during long cycles has been significantly fastened by dendritic Li growth and dead Li accumulation ascribed to the inferior solid electrolyte interphase (SEI). Efficient material construction strategies are highly demanded to inhibit the deactivation of graphite intercalation compounds (GICs: LiC 12 , LiC 6 , etc.) in graphite-Li metal hybrid anodes. Here, we introduced a physical-chemical modification strategy. Which is acted by a combination of a LiF-rich and elastic SEI and preset void in the composite electrodes, which was realized by Cu mesh current collectors, resulting in the retardant of the accumulation of dead Li and side reaction sediments on graphite surface and the retaining of the Li + insertion channels. The strategy ensured the long-term activity of both GICs and Li metal in graphite-Li metal hybrid anodes. Thus, the hybrid anodes obtain higher reversibility of both the lithium-ion insertion/deintercalation and Li metal deposition/dissolution processes. The batteries can maintain a specific capacity of up to 500 mAh/g, with an average CE of 98.5% for 85 cycles. This work presents a novel and effective methodology to realize the high reversibility of the high-capacity graphite-Li metal hybrid anodes.