Na3Fe2(SO4)2(SO3N) as a potential high capacity cathode material

Abstract

A novel sulfate material, Na2Fe2(SO4)3, was recently proposed as a high-density cathode material for sodium-based batteries (Barpanda et al., 2014). This study presents ab initio simulations describing the effect of partial oxygen-to-nitrogen substitution in this material with the aim of increasing the sodium capacity of the structure as well as its energy density. The considered structure with the most likely substitution configuration increases the theoretical energy density to 650Whkg−1, improving over the theoretical value of 480Whkg−1 for the original, nitrogen-free structure.