A Lightweight 3D Cu Nanowire Network with Phosphidation Gradient as Current Collector for High-Density Nucleation and Stable Deposition of Lithium.

Abstract

Lithium metal anodes with high energy density are important for further development of next-generation batteries. However, inhomogeneous Li deposition and dendrite growth hinder their practical utilization. 3D current collectors are widely investigated to suppress dendrite growth, but they usually occupy a large volume and increase the weight of the system, hence decreasing the energy density. Additionally, the nonuniform distribution of Li ions results in low utilization of the porous structure. A lightweight, 3D Cu nanowire current collector with a phosphidation gradient is reported to balance the lithiophilicity with conductivity of the electrode. The phosphide gradient with good lithiophilicity and high ionic conductivity enables dense nucleation of Li and its steady deposition in the porous structure, realizing a high pore utilization. Specifically, the homogenous deposition of Li leads to the formation of an oriented texture on the electrode surface at high capacities. A high mass loading (≈44 wt%) of Li with a capacity of 3 mAh cm-2 and a high average Coulombic efficiency of 97.3% are achieved. A lifespan of 300 h in a symmetrical cell is obtained at 2 mA cm-2 , implying great potential to stabilize lithium metal.