Oxygen Framework Mechanism of Layered Lithium-rich Manganese-based Materials Stabilized by High-valent Element Mo Based on First-principles Calculations
Density functional theory(DFT)first-principles calculations were employed to elucidate the stabilization mechanism of lithium-rich manganese-based materials through Mo substitution for Mn.Mo doping mitigated the volume change rate,decreasing it from ‒2.95%to ‒0.53%and improved lattice distortion both before and after lithia-tion.Results from vacancy formation energy and Bader charge analysis revealed a marked increase in the formation energy of seven oxygen vacancies,and the average Bader charge of the first-coordination oxygen escalated from 1.13 e to 1.18 e,which effectively suppressed unstable oxygen precipitation.The change in Bader charge of oxygen atoms before and after lithiation decreased from 0.51 e to 0.11 e,which was indicative of the robust stability of the oxygen framework during cycling.Differential charge density calculations illustrated that Mo can compensate for charge after the removal of Li.Furthermore,Mo doping enhanced lithium ion migration rates,reducing the minimum barrier from 0.55 eV to 0.42 eV.This study provides a rigorous theoretical foundation for the doping of high-valence elements in lithium-ion battery cathode materials.
Lithium-ion batteryLithium-rich cathode materialElectronic propertyLattice oxygenDensity functional theory
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