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

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.