Solid-state synthesis of spherical hierarchical LiNi0.5Mn1.5O4 through an improved calcination method and its cyclic performance for 5 V lithium ion batteries

• LiNi0.5Mn1.5O4 was prepared by an improved solid-state synthesis calcination process.
• Spherical hierarchical particles with uniform size distribution were obtained.
• The spherical material reduces Mn dissolution and exhibits good cycle performance.
• This method is suitable for industrial production.

Spherical hierarchical LiNi0.5Mn1.5O4 was synthesized by traditional solid-state reaction method using an improved calcination process. The improvement of the process was reflected by adding another calcination step after the traditional continuous one-step calcination and just-to-fine grinding. Compared with the one-step calcined product, the two-step calcined product had more uniform particle size distribution and spherical hierarchical structure. Electrochemical performance tests showed that the improved material exhibited greatly enhanced cycle performance at both normal and high temperatures and a high rate of 5 C. Overall, the cycle performance of the material was more than 50% higher than that of the one-step calcined product. Mn content analysis and EIS measurement of the electrodes further indicated that the improved calcination process optimized the particle size and morphology of the material, which resulted in improved electrochemical stability.