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

Two-dimensional (2D) materials with a penta-atomic-configuration, such as penta-graphene and penta-B 2 C, 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 Li 3 BCN. 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 Li 2 BCN 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.