Kinetically Controlled Synthesis of LiNi0.5Mn1.5O4 Micro- and Nanostructured Hollow Spheres as High-Rate Cathode Materials for Lithium Ion Batteries

Spinel LiNi0.5Mn1.5O4 hollow spheres with micro- and nanostructures have been successfully synthesized based on the coprecipitation method followed by postheat treatment. A uniform and spherical precursor was obtained by controlling the reaction kinetics in the nucleation crystallization process of forming nickel and manganese carbonates simply by employing NaHCO3 instead of Na2CO3 as precipitating agent. Single-shelled and double-shelled LiNi0.5Mn1.5O4 hollow spheres were derived of the spherical carbonate precursors via tuning the calcination kinetics. The as-prepared LiNi0.5Mn1.5O4 hollow spheres deliver a discharge capacity of 128.9 mAh g(-1) at 0.1 C rate and maintain a capacity retention of 95% at 0.5 C after 100 cycles. Importantly, even at high rate of 30 C, it can still exhibit a discharge capacity of 100 mAh g(-1). The excellent rate capability and cycling stability are mainly attributed to its hollow micro- and nanostructure, which could shorten Li+ ions' diffusion path and buffer the volume change during repeated Li+ insertion-extraction processes.