Synergetic effect of TiO2 coating and oxygen vacancy boosting LiMn2O4 cathode for stable aqueous zinc-ion batteries

Abstract

LiMn₂O₄ cathode materials have been regarded as one of the promising candidates for aqueous zinc-ion batteries. However, their actual application is still hindered by the Mn²⁺ dissolution and structural transformation during the charge/discharge cycling. Herein, we synthesized LiMn₂O₄ cathode materials with octahedron morphologies and followed introducing oxygen vacancies by the calcination treatment in Ar. Octahedral shape is beneficial to the improvement of cycle stability of LiMn₂O₄ cathode materials. Oxygen vacancies contribute to the rate performance by improving the electronic conductivity. Nevertheless, the cycling stability of LiMn₂O₄ cathode materials with oxygen vacancies is not satisfactory. So, we proposed the synergistic strategy of TiO₂-coating LiMn₂O₄ and oxygen vacancies. TiO₂@(LMO-A0.5) sample with uniform thin TiO₂ coating was obtained by regulating the hydrolysis reaction of tetrabutyl titanate. Consequently, TiO₂@(LMO-A0.5) exhibits the impressive rate capability and cycling stability (as high as 85 mAh/g and 91.22% capacity retentions after 200 cycles at 0.1 A g⁻¹) as the cathode materials for aqueous zinc-ion batteries. The synergetic development of multiple strategies may endow LiMn₂O₄ cathode materials with magical perspectives in aqueous zinc-ion batteries.