Hierarchical porous ZnMn2O4 microspheres architectured with sub-nanoparticles as a high performance anode for lithium ion batteries

Abstract

A simple two-step procedure, which involves the synthesis of the Zn0.33Mn0.67CO3 microspheres through a hydrothermal process and the subsequent calcination, has been used to synthesize the ZnMn2O4 microspheres with a hierarchical porous morphology consisting of the ZnMn2O4 sub-nanoparticles. When evaluated as anode materials for lithium ion batteries (LIBs), these hierarchical porous ZnMn2O4 microspheres could exhibit a stable reversible capability of ∼723.7 mAh g−1 at the current density of 400 mA g−1, which is much higher than those of the ZnMn2O4 based materials reported previously, indicating the great potential of using them as the anode for the LIBs. This is further supported by their better rate capability and higher cycling stability. Careful analysis has shown that the unique porous structure of the hierarchical porous ZnMn2O4 microspheres which consists of the ZnMn2O4 sub-nanoparticles plays an important role in their higher electrochemical performance, since it allows the accommodation of the volume expansion during the repeated discharge–charge cycles, preventing them from the structural destruction, and increase the accessibility of the electrode material to the Li+ storage, making a better utilization of active materials and an easy diffusion of electrolytes in and out of the electrode material.