Porous LiMn2O4 Microspheres With Different Pore Size: Preparation and Application as Cathode Materials for Lithium Ion Batteries

Three types of LiMn2O4 (LMO) microspheres with different pore size are prepared by a facile method, using porous MnCO3–MnO2 and Mn2O3 microspheres as the self-supporting template, for lithium ion batteries (LIBs) cathode material. Briefly, Mn2O3 and MnO2 microspheres are heated in air at 600 °C for 10 h to synthesize porous Mn2O3 spheres. Then the mixture of as-prepared spherical Mn2O3 and LiNO3 is calcined to obtain the LMOs. The morphology and structure of LMOs are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption/desorption analyses. The result shows that the maximum pore diameters of LMOs are 17 nm, 19 nm, and 11 nm, respectively. All LMOs microspheres are composed of similar sized nanoparticles; however, the surface of these microspheres is strewed with dense tinier pores or sparse larger pores. Generally, the nanoparticles will reduce the path of Li+ ion diffusion and increases the reaction sites for lithium insertion/extraction. Moreover, the pores can provide buffer spaces for the volume changes during charge–discharge process. The electrochemical performances of LMOs are investigated and LMO2 exhibits extremely good electrochemical behavior, especially the rate capability. The as-prepared LMO2 delivers a discharge capacity of 124.3 mAh g−1 at 0.5 C, retaining 79.6 mAh g−1 even at 5 C. The LMO2 sample also shows good capacity retention of 96.9% after 100 cycles at 0.5 C.