Hierarchical Zn1.67Mn1.33O4/graphene nanoaggregates as new anode material for lithium-ion batteries

Abstract

Cubic spinel type Zn1.67Mn1.33O4 porous sub-micro spheres were synthesized by the calcination of solvothermally prepared ZnxMn1 - xCO3 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 Zn1.67Mn1.33O4 nanoaggregates is the combined conversion and alloying reaction, similar to that of ZnMn2O4 systems. In favor of the uniform porous sphere structure, these resulting Zn1.67Mn1.33O4 nanoaggregates enabled the mitigation of volume change upon cycling. In addition, graphene composites with Zn1.67Mn1.33O4 nanoaggregates were fabricated to improve electrical conductivity, simply by adding graphenes during solvothermal reaction for the formation of ZnxMn1 - xCO3 precursors. Zn1.67Mn1.33O4/graphene composites showed a capacity of 670 mA h g(-1) higher than that of pure Zn1.67Mn1.33O4 (518 mA h g(-1)) after 200 cycle at a current density of 100 mA g(-1).