Preparation, Characterization and Lithium Storage Performance of Agglomerated ZnMn₂O₄ Nanoparticles

Agglomerated ZnMn₂O₄ nanoparticles with average particle sizes of 90-130 nm are synthesized by a facile chemical co-precipitation method. It is found that the consumption of precipitant ammonia has an important impact on the morphology and lithium storage property of the prepared ZnMn₂O₄ nanomaterials. With increasing ammonia consumption (molar ratios of Zn²⁺ to the precipitant ammonia of 1:10, 1:15, 1:20 and 1:25, respectively), the particle size of the prepared ZnMn₂O₄ nanomaterials becomes smaller, the porous morphology formed by the primary nanoparticles agglomeration becomes more obvious, and the lithium storage performance is improved. When Zn²⁺/ammonia mole ratio is 1:25, the prepared ZnMn₂O₄ material presents a reversible capacity of 780 mAh g^-1 after 200 cycles at a current density of 0.5 A g^-1. At a very high current density of 5 A g^-1, the sample still retains a reversible capacity of 250 mAh g^-1. This superior lithium storage performance of the sample is associated with its porous structure, which benefits the penetration of the electrolyte and enhances the electrochemical reaction activity of the active materials in the electrode. These results suggest that agglomerated ZnMn₂O₄ nanoparticles prepared by chemical coprecipitation method have potential as anode electroactive materials for next-generation lithium-ion batteries.