Three-dimensional nitrogen-doped graphene aerogel toward dendrite-free lithium-metal anode

Abstract

Lithium metal, with the highest specific capacity (3860 mAh g−1) and the lowest reduction potential (− 3.04 V vs. standard hydrogen electrode), is considered as an ideal anode for the next-generation lithium-metal batteries with high energy density. However, the poor cycling performance and safety problems seriously restrict the commercial application of lithium-metal batteries. Herein, a three-dimensional (3D) porous nitrogen-doped graphene aerogel (NGA) was prepared by a hydrothermal method followed with lyophilization and high-temperature treatment to guide the uniform and dendrite-free Li deposition. On the one hand, the 3D porous structure with a large specific surface area can reduce the effective current density of the electrode, decrease the Li nucleation overpotential, and provide large spaces for Li deposition. On the other hand, the doped nitrogen atoms could provide strong affinity between Li and the NGA substrate for uniform Li deposition. Based on the synergistic effect of the above-mentioned two reasons, the Coulombic efficiency of Li deposition on NGA electrode can remain as high as 99% for over 150 cycles at a constant current density of 0.5 mA cm−2 with a fixed capacity of 1 mAh cm−2. The LiFePO4 (LFP) full cells with Li-NGA anode also exhibit excellent cycling performance and rate performance, indicating NGA has a good application prospect toward high-performance lithium-metal anode.