Super lithiophilic SEI derived from quinones electrolyte to guide Li uniform deposition

Abstract

Metallic lithium with high theoretical specific capacity is usually regarded as an attractive electrode material for high-energy-density batteries. However, the wide practical applications of lithium metal batteries are severely limited by the random metallic lithium accumulation on a working lithium anode. Here, tetrachloro-1,4-benzoquinone (TCBQ) was adapted as an electrolyte additive, which possesses the relatively low lowest unoccupied molecular orbital and can generate quinone lithium salt (Li2TCBQ) in SEI layer during cycling. According to the molecular dynamics simulations, Li2TCBQ is lithiophilic that can serve as the lithium plating guidance to regulate uniform lithium deposition relying on the high lithium-ion affinity. The cell with TCBQ-added electrolyte can be deeply cycled at a high capacity of 5 mAh cm−2 without formation of isolated lithium, and decomposition of organic solvents during cycling in carbonate electrolyte is suppressed effectively. The use of TCBQ additive offers a new approach to realize high energy-density lithium metal batteries.