Endowing Cu foil self-wettable in molten lithium: A roll-to-roll wet coating strategy to fabricate high-performance ultrathin lithium metal anodes

Abstract

The cost-effective mass production of high-performance ultrathin lithium metal anodes is a bottleneck hindering the commercialization of high-energy-density Li metal batteries. Compared to complex and expensive conventional fabrication techniques including sputtering, electrodeposition, and pressure-rolling, the wet coating of molten Li on a Cu sheet is a very promising strategy. Unfortunately, the wettability of molten Li on the Cu surface is very poor, creating difficulty in achieving a uniform Li film. Herein, a facile and efficient approach to the application of melt coatings is realized through the alloying reaction between molten Li and the heated Cu surface. An ultrathin and uniform Li film with a thickness of 5 − 50 µm is prepared via roll-to-roll fabrication. Remarkably, a three-dimensional LiCux solid-solution alloy skeleton is formed inside the ultrathin Li, achieving the dual purpose of lithiophilicity and high performance. The full cell with the N/P ratio of 3.2, consisting of a LiFePO4 cathode with an areal capacity of 1.58 mAh·cm−2 and a 25 µm thick LiCux/Li composite anode, exhibited stable cycling for more than 480 cycles at 1 C. This work provides a potential solution for the industrial production of high-performance and cost-effective ultrathin Li metal anodes.