Boron-doping induced lithophilic transition of graphene for dendrite-free lithium growth

Abstract

Applications of lithium mental batteries (LMB) were severely hindered by dendritic growth problem. In this article, boron atoms were doped in graphene (BG) to induce the lithophilic transition of substrate. The battery tests of BG were conducted and the inherent principle was studied through DFT calculations. Li metal, possessing advantages of high theoretical specific capacity and low electrochemical potential, is regarded as the most promising anode material for next-generation batteries. However, despite decades of intensive research, its practical application is still hindered by safety hazard and low Coulombic efficiency, which is primarily caused by dendritic Li deposition. To address this issue, restraining dendrite growth at the nucleation stage is deemed as the most effective method. By utilizing the difference of electronegativity between boron atoms and carbon atoms, carbon atoms around boron atoms in boron-doped graphene (BG) turn into lithiophilic sites, which can enhance the adsorption capacity to Li + at the nucleation stage. Consequently, an ultralow overpotential of 10 mV at a current density of 0.5 mA/cm 2 and a high average Coulombic efficiency of 98.54% over more than 140 cycles with an areal capacity of 2 mAh/cm 2 at a current density of 1 mA/cm 2 were achieved. BG-Li|LiFePO 4 full cells delivered a long lifespan of 480 cycles at 0.5 C and excellent rate capability. This work provides a novel method for rational design of dendrite-free Li metal batteries by regulating nucleation process.