Spatial Control of Lithium Deposition by Controlling the Lithiophilicity with Copper(I) Oxide Boundaries

Spatial control of lithium deposition is the most important issue in lithium-metal batteries because of the considerable control of lithium dendrite suppression via the uniform distribution of Li⁺ flux. Although seed materials are crucial for the behavior of lithium deposition, in-depth studies on their physical and chemical control have not been conducted. Here, we describe a new design of seed structure comprising a wrinkled Cu/graphene substrate surrounded by copper(I) oxide (Cu₂O) on a graphene grain boundary over a large area, which is fabricated by the oxidation of the Cu surface via graphene boundary defects by using chemical vapor deposition (CVD). Scanning and transmission electron microscopy results reveal that Cu₂O on the graphene boundary can render a preferential reaction with lithium during the first deposition and assist in the uniform deposition of lithium by preventing the agglomeration of lithium clusters during the second deposition. This two-step process is attributed to the degree of selectivity due to the difference in lithium affinity, which allows long-term electrochemical stability and a high rate capability via boundary effects. This study highlights the significance of the boundary effect, which can open new avenues for the formation of a large family of seed structures in lithium-metal batteries.