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 La3+ doping strategy guided by Bayesian optimization has been employed to prepare the high-performance O3-NaNi0.39Mn0.50Cu0.06La0.05O2 (NMCL) cathode material. Density functional theory calculations reveal that the O2p orbital overlaps with the t2g 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 La3+ doping that promotes oxidation of O2- to peroxide O2 n- (n<2) during charge.
Published Version
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