Towards a new packing pattern of Li adsorption in two-dimensional pentagonal BCN

Abstract

Two-dimensional (2D) materials with a penta-atomic-configuration, such as penta-graphene and penta-B₂C, have received great attention as anodes in Li-ion batteries (LIBs). Recently, penta-BCN has been demonstrated to exhibit the highest theoretical capacity to date of 2183 mA h g⁻¹, corresponding to the composition Li₃BCN. Herein, we study the layer-by-layer Li adsorption on penta-BCN by explicitly and comprehensively considering its structure. We discover a new, more energetically favorable Li adsorption site that is distinct from the latest report by Chen et al. (Phys. Chem. Chem. Phys., 2021, 23, 17693). The possible migration pathway and the accompanying activation energy are also investigated. Full lithium adsorption leads to the formula Li₂BCN and the reduced theoretical capacity of 1455 mA h g⁻¹. Still, penta-BCN exhibits metallic conductivity during Li adsorption, and has a low open-circuit voltage, and a low ion-diffusion barrier, all being beneficial for anode materials. These observations imply that penta-BCN remains one of the most effective anode materials for LIBs with a quick charge/discharge rate.