Rice-shaped porous ZnMn2O4 microparticles as advanced anode materials for lithium-ion batteries

Abstract

In this work, novel rice-shaped porous ZnMn₂O₄ microparticles made of nanoparticles were successfully prepared for the first time by the calcination of Zn_0.33Mn_0.67CO₃ precursors synthesized using a facile triethanolamine-assisted solvothermal method. The effect of solvothermal reaction time on the crystallinity and morphology of Zn_0.33Mn_0.67CO₃ precursors is discussed. The obtained ZnMn₂O₄ microparticles have lengths of ca. 1.6 μm and widths of ca. 0.9 μm, while the primary nanoparticles are in sizes of ca. 25–70 nm. As a potential anode material for lithium-ion batteries, the ZnMn₂O₄ microparticles give a large reversible discharge capacity of 892 mA h g⁻¹ at 0.2 A g⁻¹, superior cyclability (95% capacity retention after 550 cycles at 2 A g⁻¹), and excellent rate capability (571 mA h g⁻¹ at 5 A g⁻¹). The outstanding electrochemical performances of the microparticle materials benefit from the suitable micro-/nanoparticle sizes, hierarchical porous structures, and strong interconnected 3D frameworks, which shorten the path lengths for ionic transport, accommodate volume expansion/contraction, and maintain the structural integrity of electrodes during the cycling process.