Bifunctional Current Collectors for Lean‐Lithium Metal Batteries

Abstract Lithium metal batteries offer great promise toward realizing high energy density devices. However, several issues such as lithium metal degradation, dendrite growth, etc., still remain a challenge, particularly with lean lithium metal anode. Here, the fabrication of a ‘bifunctional current collector’ and its related electrochemical studies for a lean lithium metal battery are demonstrated. A thin layer of copper selenide (Cu 2 Se) grown on the surface of commercial Cu foil, via the chemical vapor deposition (CVD) method, is further lithiated to form a layer of Li 2 Se with Cu particles interspersed in the matrix. This matrix encapsulates the electrodeposited lithium, providing improved stability for the Li metal anode over cycling. Based on our experimental observations and the density functional theory (DFT) calculations, the mechanism of lithium metal encapsulation on the modified current collector is proposed. Further, the same modified current collector (lithiated Cu/Cu 2 Se) is explored as a promising cathode in lithium metal batteries, and a full cell is fabricated by electrochemical‐tuning of Cu/Cu 2 Se for both anode and cathode. In essence, such a ‘bifunctional current collector’ could be a potential concept, effectively alleviating the concerns on multi‐material dependency and self‐reliability in energy storage applications.