Boosting lithium storage of BaFe₁₂O₁₉ by element doping engineering

Ternary metal oxides have been considered a promising anode material for lithium-ion batteries (LIBs) based on their stable chemical compositions and abundant active sites. This work doped Mn into BaFe₁₂O₁₉ by a simple hydrothermal method and subsequent annealing treatment. By adjusting the ratio of raw materials, we obtained a Mn-doped BaFe₁₂O₁₉ electrode with an irregular hexagonal morphology. The doped Mn ions are in  + 2, + 3, and + 4 valence states. Due to the octahedral position preference, Mn²⁺ tends to occupy the tetrahedral position. At the same time, Mn⁴⁺ favors octahedral coordination, and most Mn resides in (distorted) octahedral coordination in the form of + 3 valence state. Employed as a LIB anode, the specific capacity of the electrode reached 782.57 mA h g⁻¹ after 150 cycles at a current density of 100 mA g⁻¹. Even at a high current of 1 A g⁻¹, the specific capacity remained at 439.99 mA h g⁻¹ after 450 cycles. Mn-doped BaFe₁₂O₁₉ exhibited better cycling stability and electrochemical performance compared with pure BaFe₁₂O₁₉, which may be attributed to significantly enhanced charge transport kinetics at the interface between electrodes and electrolytes by Mn doping.