Microwave rapid synthesis of LiNi0.85Mn0.10Co0.05O2 positive electrode materials for lithium-ion batteries

Abstract

Ni-rich (Ni ≥80 atom%) layered oxides are promising candidates of positive electrode materials for lithium-ion batteries because of high specific capacity, and reducing energy consumption during synthesis is important for mass production to reduce environmental impact. Microwave heating of Ni-rich layered oxide is anticipated to enable much faster and more effective synthesis than conventional method; however, only a few studies have been reported. In this study, LiNi_0.85Mn_0.10Co_0.05O₂ (NMC85) positive electrode materials were prepared by preheating the mixture of Ni_0.85Mn_0.10Co_0.05(OH)₂ precursor and LiOH, followed by microwave heating at a rate of 28.3°C min⁻¹ and holding at 850°C for 1 h. The specific discharge capacity in half-cell of NMC85 synthesized by microwave heating was 190.0 mAh g⁻¹. Although the capacity was still inferior to that of NMC85 synthesized by conventional heating method, which was one of the highest values among Ni-rich layered oxide by microwave synthesis, owing to high crystallinity. Furthermore, much improvement of the electrochemical properties is expected by increasing uniformity during the microwave heating, because inhomogeneous crystal growth and cation mixing were observed. This study indicates the possibility to apply microwave heating for the synthesis of Ni-rich layered oxide and improve the energy efficiency considerably.