S-doped graphene-regional nucleation mechanism for dendrite-free lithium metal anodes

Abstract

Lithium metal is the most promising anode material for next-generation batteries, owing to its high theoretical specific capacity and low electrochemical potential. However, the practical application of lithium metal batteries (LMBs) has been plagued by the issues of uncontrollable lithium deposition. The multifunctional nanostructured anode can modulate the initial nucleation process of lithium before the extension of dendrites. By combing the theoretical design and experimental validation, a novel nucleation strategy is developed by introducing sulfur (S) to graphene. Through first-principles simulations, it is found that S atom doping can improve the Li adsorption ability on a large area around the S doping positions. Consequently, S-doped graphene with five lithiophilic sites rather than a single atomic site can serve as the pristine nucleation area, reducing the uneven Li deposition and improving the electrochemical performance. Modifying Li metal anodes by S-doped graphene enables an ultralow overpotential of 5.5 mV, a high average Coulombic efficiency of 99% over more than 180 cycles at a current density of 0.5 mA cm(-2) for 1.0 mAh cm(-2), and a high areal capacity of 3 mAh cm(-2). This work sheds new light on the rational design of nucleation area materials for dendrite-free LMB.