The effects of high content Tin (Sn) doping on the layered LiMnO₂ cathode material for lithium-ion batteries

Materials Modelling Centre, University of Limpopo, Private Bag x1106, Sovenga 0727, South Africa.”

^* Corresponding author: bridgetmokgabudi02@gmail.com

Abstract

The search for advanced cathode materials is intensifying to meet the growing demand for high performance lithium-ion batteries from renewable energy and electric vehicle sectors. Lithium transition metal oxides (LiMO₂), especially LiMnO₂ are highly promising candidates due to their high capacity, energy density, thermal stability, and low cost. However, the practical use of LiMnO₂ is hindered by its structural instability and significant capacity fade, primarily caused by the Jahn-Teller distortion of Mn³⁺ ions. In this study, cluster expansion (CE) and density functional theory (DFT) were utilized to explore Sn-doped LiMnO₂ as a promising cathode material for lithium-ion batteries. A total of 29 Sn-doped configurations were generated, with three identified as lying on the binary ground state line. Among these, the phase Li₄MnSn₃O₈, corresponding to a 25:75 Mn-Sn ratio, was examined in detail. This phase crystallizes in a triclinic structure and exhibits thermodynamic stability, evidenced by its negative formation energy. Electronic structure calculations indicate semiconducting behaviour with a clear band gap and minimal contribution from Sn to the density of states. Additionally, mechanical analysis confirms the material’s ductile nature, implying good deformation tolerance. Overall, these results offer valuable insights into the stability, electronic properties, and mechanical behaviour of Sn-doped LiMnO2 for battery applications.