Computational discovery of superior vanadium-niobate-based cathode materials for next-generation all-solid-state lithium-ion battery applications

Abstract

All-solid-state lithium-ion batteries (ASSLIBs) are at the forefront of green and sustainable energy development research. One of the key challenges in the development of ASSLIBs for commercial applications is to find cathode materials that have high capacity, voltage and power density. Using a combination of first-principles calculations and various crystal structure prediction algorithms, we explore the LiVO₂–Li₃NbO₄ pseudobinary tieline to identify novel stoichiometries with improved properties as cathode materials for ASSLIB applications. Based on more than 10 000 Density Functional Theory (DFT) calculations using crystal structures obtained from ab initio random structure searching (AIRSS), genetic algorithm, and configuration enumeration procedures, we predict five novel stoichiometries, Li₂₃Nb₇V₂O₃₂, Li₁₀Nb₃VO₁₄, Li₇Nb₂VO₁₀, Li₁₁Nb₃V₂O₁₆, Li₄NbVO₆, along with an experimentally known stoichiometry, Li₅NbV₂O₈. All the novel stoichiometries are found to have cation-disordered rock-salt crystal structures and fall within 30 meV per atom from the convex hull of the parent compositions. These new phases are predicted to have superior properties compared to the current vanadium-niobate-based electrode materials, including a higher theoretical capacity, lower band gap, higher average Li intercalation voltage, minor volume change upon full Li delithiation, good mechanical and dynamical stability, improved Li-conduction activation barrier and high-temperature stability. Our results are anticipated to inspire further experiments to synthesise and test these specific vanadium-niobate-based materials for their actual performance as Li-ion cathode materials.