Controlled lithium plating in three-dimensional hosts through nucleation overpotential regulation toward high-areal-capacity lithium metal anode

Three-dimensional (3D) porous hosts with abundant space inside can accommodate volume variation during lithium (Li) plating/stripping and promote reversibility of Li anode; however, the porous structure in 3D hosts usually induces uneven Li-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 scanning electron microscopy (SEM) characterization confirms that this two-step coating strategy by coating Au and polymer blend (polyacrylonitrile and poly(vinylidene fluoride-co-hexafluoropropylene)) on the bottom and top sides 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 predeposited Li as the anode and lithium iron phosphate as the cathode (N/P ratio of ~4) can cycle steadily at 2.0 C with a capacity retention ratio of 96.4% after 150 cycles. The modification strategy proposed in this work is considered as a promising approach for designing a 3D conductive host for long-life and safe Li metal batteries.