Controlled Li Plating in 3D hosts through Nucleation Overpotential Regulation towards High-Areal-Capacity Li Metal Anode

Abstract 3D porous hosts with abundant space inside can accommodate volume variation during Li plating/stripping and promote reversibility of Li anode, however, the porous structure in 3D hosts usually induces uneven lithium ion/electron migration, giving rise to undesirable surface preferential Li nucleation and growth. A feasible coating strategy is developed herein to create gradient nucleation overpotentials on Cu mesh to realize the “bottom-up” Li plating mode on 3D host. The ex-situ SEM characterization confirms that this two-step coating strategy by coating Au and polymer blend (PAN and PVDF-HFP) on the bottom and top side of Cu mesh, respectively, successfully changes the nucleation overpotentials of this 3D host by altering Li affinity. As a result, stable Li plating/stripping and high Coulombic efficiency of 97.3% can be achieved under high areal capacity of 5.0 mAh/cm2. The full cell using the modified Cu mesh with pre-deposited Li as the anode and lithium iron phosphate as the cathode (N/P ratio of ∼4) can cycle steadily at 2.0 C with capacity retention ratio of 96.4% after 150 cycles. The modification strategy proposed in this work is considered as a promising approach for designing 3D conductive host for long-life and safe lithium metal batteries.