Synthesis of porous Mg2MnO4 spinel microspheres and enhanced lithium storage properties

Abstract

Porous Mg₂MnO₄ spinel microspheres were synthesized by a facile solvothermal method. Various techniques such as X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, were used to characterize the phase composition, morphology and electronic structure of materials. The results show that Mg₂MnO₄ spinel material was obtained at the temperature of 600–800 °C and has a microsphere structure. The microspheres were assembled by nanoparticles, and the particle size increases with the increase of annealing temperature. Analyses of XPS spectra reveal that Mn exists in multiple valence states (+2, +3, +4) in Mg₂MnO₄ materials, and all the materials are mixed spinel with Mg²⁺ and Mn^2+/3+/4+ ions occupy both tetrahedral and octahedral sites of spinel structure, and the degree of inversion decreases with increasing annealing temperature. Mg₂MnO₄ microspheres exhibit excellent lithium storage performance, the first discharge specific capacity of M2MO-8 is 835.3 mAh g⁻¹ under a voltage window of 0–3 V and with a current density of 100 mA g⁻¹, and after 100 cycles the discharge capacity of the material is as high as 406.5 mAh g⁻¹. In addition, this material shows high cyclic reversibility. The enhanced lithium storage properties of the material can be attributed to its porous structure, which promote the transport of lithium ions and reduce the damage to the structure caused by the volume change during the charge and discharge process.