Exploring the Phase Stability of Li₂Mn_1-x TM _x O₃ (TM = Ni, Co, Cr, Ru) Cathode Materials in Lithium-Ion Batteries...

Li₂MnO₃ has garnered significant interest as a potential cathode material due to its high electrochemical capacity, cost-effectiveness, and eco-friendliness. Nonetheless, its practical utilization is hindered by structural deterioration, which results in rapid capacity and voltage decay during cycling. To mitigate these challenges, cationic dopants have been incorporated to minimize structural collapse and enhance cathode material performance. Consequently, there is a strong desire to identify novel doped configurations as a remedial strategy for optimizing Li₂MnO₃ properties. In this study, the stability of the Li₂Mn_1-x TM _x O₃ system (TM = Ni, Co, Cr, Ru) was explored using cluster expansion and Monte Carlo simulations. By employing cluster expansion, binary ground state diagrams were generated, revealing 73, 65, 90, and 83 newly stable phases in Li₂Mn_1-x Ni _x O_3, Li₂Mn_1-x Co _x O₃, Li₂Mn_1-x Cr _x O₃, and Li₂Mn_1-x Ru _x O₃, respectively. The outcomes indicated that Li₂Mn_0.83Ni_0.17O₃, Li₂Mn_0.5Co_0.5O_3, Li₂Mn_0.5Cr_0.5O₃, and Li₂Mn_0.5Ru_0.5O₃ represent the most stable doped phases within the Li₂MnO₃ system. The application of Monte Carlo simulations enabled the assessment of high-temperature characteristics across the entire range of TM concentrations (0 ≤ x ≤ 1), facilitating the construction of phase diagrams. The Li₂Mn_1-x Ni _x O_3, Li₂Mn_1-x Co _x O₃, Li₂Mn_1-x Cr _x O₃, and Li₂Mn_1-x Ru _x O₃ systems exhibited favorable mixing at temperatures of 850, 700, 1700, and 1300 K, respectively. These discoveries present a clear trajectory for optimizing the properties of Li₂MnO₃, offering valuable insights into conceptualizing innovative cathode materials characterized by enhanced stability and performance.