3D hierarchical porous current collector via deposition-dealloying method for lithium metal anode

Abstract

In order to inhibit dendritic growth and improve the cycle stability of lithium metal anodes (LMAs), a 3D Nanoporous Nickel Foam (NP-NF) collector with hierarchical porous structure is designed through a simple modification strategy of Ni Foam (NF). The strategy only involves two steps, i.e. electrodeposition of metal zinc and chemical dealloying to evolve nanoporous structure. The obtained NP-NF possesses hierarchical pores. The large pores of several hundreds of micrometers from Ni foam could facilitate fast Li⁺ transport in dynamics. The mesopores on the surface of 100 nm to 1 μm could provide spatial confinement for Li deposition. The increased specific surface area could also reduce the local current density of electrode and consequently suppress the growth of dendrites. In addition, the in-situ formed lithophilic NiO on the 3D NP-NF surface can uniformly induce Li⁺ deposition. Compared to the Ni foam skeleton, 3D NP-NF in LMAs presents a significantly improved Li plating/string stability with a high Coulombic efficiency of 95 % after 350 cycles with plating capacity of 1 mAh cm⁻² at a current density of 1 mA cm⁻². 3D NP-NF@Li|Li cell shows an ultra-low overpotential of 18 mV during the 500 cycles (1000 h) at a current density of 1 mA cm⁻². The 3D NP-NF@Li|LiFePO₄ can stably cycle for 300 times with the capacity retention of above 80 % at 1C. This work demonstrates that constructing a micro-nano 3D porous structure collector can inhibit dendritic growth and improve lifespan of LMAs.