La³⁺ Doped Nickel‐Manganese Oxide as High‐Capacity Cathode for Sodium‐Ion Batteries Guided by Bayesian Optimization

Abstract In sodium‐ion batteries, the layered transition metal oxides used as cathode often experience interlayer sliding of interlayer spacing and lattice variations during charge/discharge, leading to structural damage and capacity degradation. To address this challenge, a La 3+ doping strategy guided by Bayesian optimization has been employed to prepare the high‐performance O3‐NaNi 0.39 Mn 0.50 Cu 0.06 La 0.05 O 2 (NMCL) cathode material. Density functional theory calculations reveal that the O 2p orbital overlaps with the t 2g orbital of transition metals in NMCL, facilitating the formation of Na−O−La bonds and promoting the oxygen redox reaction kinetics. During the Na + (de)intercalation process, NMCL exhibits significant negative lattice expansion, characterized by an increase in the c lattice parameter and exceptionally low volume expansion of 1.8 % and 3.1 %, respectively. Consequently, it delivers an excellent specific capacity of 243.3 mAh g −1 over a wide voltage range of 2.0 V to 4.5 V, which can be attributed to La 3+ doping that promotes oxidation of O 2− to peroxide O 2 n− ( n <2) during charge.