Intagliated Cu substrate containing multifunctional lithiophilic trenches for Li metal anodes

Abstract

Lithiophilic 3D substrates for lithium metal anodes (LMAs) are attracting considerable attention because they can provide an extensive active surface area and electrolyte reservoir for reversible lithium metal storage. However, the introduction of additional 3D-structured electrode materials on a typical Cu foil substrate decreases the specific/volumetric capacities of LMA. Herein, we report an alternative intagliated Cu foil (I-Cu) substrate with lithiophilic trenches that can be prepared through a mass-scalable photoresist process followed by simple chemical treatments. The patterned trenches are covered with nanocrevices, including numerous oxygen functional groups (O/Cu ratio of 1.00) and nanopores, extensively widening the electrochemical active surface area (EASA) of the I-Cu substrate by > 30 times that of a typical 2D Cu foil. The nanostructure, high surface area, lithiophilic surface properties, and intagliated trenches of the I-Cu substrate serve to guide preferred lithium metal nucleation and growth behavior on the controlled active surfaces. Accordingly, highly efficient and stable cycling performances were accomplished for the LMA composed of the I-Cu substrate over 500 cycles with an average Coulombic efficiency of ∼ 99%. Moreover, the feasibility of the I-Cu-based LMA was demonstrated in the full cell tests with typical cathode materials, NCM622 and a sulfur copolymer.