Structural features and electrochemical properties of nanostructured ZnCo₂O₄ synthesized by an oxalate precursor method

As a Li-ion battery anode, the active substance with a porous nanostructure can be endowed with a high electrochemical performance because of its porosity and remarkable surface area. In this paper, the thermal decomposition of zinc–cobalt binary oxalate precursors, precipitated from a solvothermal medium of ethanol and water (75/25, v/v) at 100 °C, has been performed to synthesize phase-pure ZnCo₂O₄ spinels, thoroughly giving porous and rod-like configurations with an average length of a few micrometers. Interestingly, each of the as-obtained porous microrods has been well characterized to consist of ~35.2-nm single-crystalline nanoparticles with polydisperse interspaces. More interestingly, porous ZnCo₂O₄ microrods can deliver an initial specific discharge capacity of 1,293.7 mAh g⁻¹ with the coulombic efficiency of 76.8 % at 0.2 A g⁻¹, reaching a value of 937.3 mAh g⁻¹ over 100 discharge–charge cycles. Even at a high current density of 2.0 A g⁻¹, the porous ZnCo₂O₄ nanostructures can still possess a reversible discharge capacity of ~925.0 mAh g⁻¹, further assigned to the synergistic effect of Zn- and Co-based oxide components. Anyway, the facile oxalate precursor method can realize the controlling synthesis of porous and rod-like ZnCo₂O₄ nanostructures with a high electrochemical performance.