Ab-initio study of short-range ordering in vanadium-based disordered rocksalt structures

TL;DR

This study uses first-principles calculations and cluster-expansion methods to analyze short-range ordering and delithiation behavior in vanadium-based disordered rocksalt cathodes, offering insights to optimize battery performance.

Contribution

It introduces a detailed modeling approach to understand cation ordering and delithiation sequence in V-based DRX cathodes, guiding material design.

Findings

V nearest neighbors influence delithiation order

V oxidation minimizes electrostatic repulsions

Short-range order affects energy density

Abstract

Disordered rocksalt Li-excess (DRX) compounds are attractive new cathode materials for Li-ion batteries as they contain resource-abundant metals and do not require the use of cobalt or nickel. Understanding the delithiation process and cation short-range ordering (SRO) in DRX compounds is essential to improving these promising cathode materials. Herein, we use first-principles calculations along with the cluster-expansion approach to model the disorder in DRX Li2-xVO3, 0 < x < 1. We discuss the SRO of Li in tetrahedral and octahedral sites, and the order in which Li delithiates and V oxidizes with respect to local environments. We reveal that the number of nearest-neighbor V dictates the order of delithiation from octahedral sites and that V are oxidized in a manner that minimizes the electrostatic interactions among V. Our results provide valuable insight for tailoring the performance of V-based DRX cathode materials in general by controlling the SRO features that reduce energy density.