A comparative analysis between isotropic and optimization binary diagram influenced by nickel-doping on the LiMn₂O₄ spinel type

¹ Materials Modelling Centre, University of Limpopo, South Africa
² Next Generation Enterprises and Institutions, Council for Scientific and Industrial Research, South Africa
³ National Institute for Theoretical and Computational Sciences, South Africa

^* Corresponding author: kemeridge.malatji@ul.ac.za

Abstract

The study explores the Ni-rich transition metal as a dopant on the Mn (16d) site of the LiMn_1-xNi_xO₄ cathode material. However, lithium manganese oxide is hindered by a limited cycle life, caused by the dissolution of manganese into the electrolyte during electrochemical cycling. Doping lithium-ion battery materials with TM generally enhances their ability to maintain electrochemical capacity over many cycles without compromising the initial reversible capacity at room temperature. This study utilised the genetic algorithm approach and first-principles calculations to investigate the LiMn2O4 spinel structure. This method identified the most stable phases by simplifying atomic interactions in the LiMn₂O₄-LiNi₂O₄ system using a series of clusters, which facilitated the corresponding thermodynamic analysis. The comparison and exploration between the full optimized and volume optimized binary calculation was to observe the % difference of the two binary diagrams yielding 13 meV and 1.1 meV, respectively. The two binary ground state diagrams depict the miscibility constituent’s behaviour, producing new phases (62 and 77) with different coordinates. The study revealed the five most stable phases at the ground state line, one of which is the opposite (LiMn_0.5Ni_1.5O₄) at X = 0.75 of the high-potential cathode material LiMn_0.5Ni_1.5O₄.