Organic eutectic mixture incorporated with graphene oxide sheets as lithiophilic artificial protective layer for dendrite-free lithium metal batteries

For wide and safe applications of Li metal batteries, the suppression of Li dendrite growth during cycling is the most crucial yet challenging topic. In this work, an artificial protective interlayer of GO-BQ@LiTFSI (GBL) is designed to overcome this issue. The GBL interlayer is prepared by incorporating graphene-oxide sheets with a liquid organic eutectic mixture of 1,4-benzoquinone and bis (trifluoromethane) sulfonamide lithium salt. With the exceptional merits of these functional materials, the incorporation endows the GBL interlayer with rich lithiophilic active sites, good ionic conductivity, superior thermal stability and compatibility with the electrolyte, and the precursor supply stations for the formation of a compact and LiF-rich solid-electrolyte interface (SEI). Consequently, the GBL effectively promotes the uniform nucleation of Li at low over-potentials and regulates the Li-ion flux, leading to the formation of planar Li metal. After utilizing the GBL interlayer in the Li||Li symmetric cells, high electrochemical stability for 600 h is achieved at a current density of 3 mA cm⁻² and a capacity of 3 mAh cm⁻². Remarkably, this modification enables Li||LiFePO₄ full cells with 1600 cycles at 1C and a high-capacity retention of 95.23% with a cathode mass loading of ≈6 mg cm⁻².