Hierarchical Zn _1.67 Mn _1.33 O ₄ /graphene nanoaggregates as new anode material for lithium-ion batteries

Cubic spinel type Zn _1.67 Mn _1.33 O ₄ porous sub-micro spheres were synthesized by the calcination of solvothermally prepared Zn _x Mn _1 − x CO ₃ precursor powders and evaluated as new anode materials for Li-ion batteries for the first time. Each sphere exhibited aggregated morphology, constructed entirely from nanoparticles with a primary particle size of 11 nm. Electrochemical investigations and ex-situ transmission electron microscopy analyses revealed that the reaction mechanism of obtained Zn _1.67 Mn _1.33 O ₄ nanoaggregates is the combined conversion and alloying reaction, similar to that of ZnMn ₂ O ₄ systems. In favor of the uniform porous sphere structure, these resulting Zn _1.67 Mn _1.33 O ₄ nanoaggregates enabled the mitigation of volume change upon cycling. In addition, graphene composites with Zn _1.67 Mn _1.33 O ₄ nanoaggregates were fabricated to improve electrical conductivity, simply by adding graphenes during solvothermal reaction for the formation of Zn _x Mn _1 − x CO ₃ precursors. Zn _1.67 Mn _1.33 O ₄ /graphene composites showed a capacity of 670 mA h g ⁻¹ higher than that of pure Zn _1.67 Mn _1.33 O ₄ (518 mA h g ⁻¹ ) after 200 cycle at a current density of 100 mA g ⁻¹ .