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 <i>et al.</i> (<i>Phys. Chem. Chem. Phys.</i>, 2021, <b>23</b>, 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.