First-principles study on haeckelite hexagonal monolayer with high specific capacity for sodium-ion battery

Abstract

Sodium ion batteries are considered to be promising energy storage devices due to the vast earth abundance and low cost of sodium-containing precursors. The suitable anode for sodium ion batteries is required to have a large pore size to facilitate the insertion of sodium ions. We investigate the properties of haeckelite hexagonal monolayer as anode in sodium ion batteries by first-principles calculations. The existence of large radius heptagon ring induces the sodium ions to be adsorbed on the monolayer easily. Low diffusion barrier (0.30 eV) and small open circuit voltage ranges (0.37–0.16 V) indicate that the haeckelite hexagonal monolayer has excellent mobility properties and a large driving force for Na-ion diffusion in the charge/discharge process. Most remarkably, the storage capacity of hexagonal monolayer can be up to 1116.71 mA h g−1. The above properties demonstrate that the haeckelite hexagonal monolayer is an excellent anode material for rechargeable sodium ion batteries. Our research provides guidance for further application of haeckelite structure in the battery field.