Li adsorption properties of monolayer Cu sheets

In this work we report the Li adsorption properties on 2 dimensional (2D) sheets of Cu, by means of density functional theory (DFT) calculations, for its potential applications in rechargeable Li-ion battery cells and other energy storage systems such as supercapacitors. Employing Generalized Gradient Approximation (GGA) in DFT with Perdew-Burke-Ernzerhoff (PBE) exchange correlation functional, we evaluate the prospect of Li storage on a monolayer 2D Cu sheet. The DFT calculations, inclusive of the Grimme’s DFT-D3 corrections were carried out with the Quantum ESPRESSO code implemented in Materials Square. Structure optimizations with a Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm were performed in order to minimize the Hellman-Feynmann forces below 0.01 eV/Å. Our calculations show that Li adsorbs on 2D Cu with specific capacity of upto 463.87 mAh/g and has very small diffusion barrier of about 0.13eV. However as Li adsorbs on monolayer Cu with average adsorption energies in the range of 0.93-0.33eV/atom, there exists a possibility of Li clustering at higher concentrations associated with 2D Cu electrodes in Li-ion batteries, which may be mitigated by defect engineering in the 2D Cu flakes.