Porous LiMn2O4 Nano-Microspheres as Durable High Power Cathode Materials for Lithium Ion Batteries

Abstract

Porous LiMn2O4 spheres was easily fabricated with MnCO3 spheres and MnO2 as precursors and characterized in terms of structure and performance as the cathode of a lithium ion battery. The presence of pores with the average size of about 50 nm throughout the whole LiMn2O4 microspheres was confirmed by scanning electron microscope (SEM) and N2 adsorption-desorption measurements. The electrochemical tests show that the synthesized product has smaller electrochemical polarization, faster Li-ion intercalation kinetics and higher electrochemical stability. It exhibits excellent rate capability and cyclic stability: delivering a reversible discharge capacity of 71 mA h g−1 at a 5 C rate and yielding a capacity retention of over 92% at a rate of 0.5 C after 100 cycles. The superior performance of the synthesized product is attributed to its special structure: porous secondary spheres particles consisting of primary single-crystalline nanoparticles. The nanoparticle reduces the path of Li-ion diffusion and increases the reaction sites for lithium insertion/extraction, the pores provide room to buffer the volume changes during charge-discharge and the single crystalline nanoparticle endows the spinel with the best stability. Taking the excellent electrochemical performance and facile synthesis into consideration, the presented porous LiMn2O4 spheres could be a competitive candidate cathode material for high-performance lithium-ion batteries.