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

In this work, novel rice-shaped porous ZnMn2O4 microparticles made of nanoparticles were successfully prepared for the first time by the calcination of Zn0.33Mn0.67CO3 precursors synthesized using a facile triethanolamine-assisted solvothermal method. The effect of solvothermal reaction time on the crystallinity and morphology of Zn0.33Mn0.67CO3 precursors is discussed. The obtained ZnMn2O4 microparticles have lengths of ca. 1.6 m and widths of ca. 0.9 m, 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.