Energy-efficient microwave liquid phase flameless combustion facilitating the rapid synthesis of LiNi0.6Co0.2Mn0.2O2 cathode materials

Layered Ni-rich oxides LiNi x Co y Mn 1-x-y O 2 (x ≥ 0.6, x + y = 1) are considered the best promising cathode material for high-performance lithium-ion secondary batteries. However, the time-consuming and complicated preparation process of spherical precursors greatly increases the consumption of energy and time, whilst suffering the challenges of liquid waste and Li uniform distribution. Herein, a simple microwave liquid phase flameless combustion method with the advantages of time-saving and energy-conservation has been proposed to synthesize Ni-rich LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622 ). The NCM 622 powders with uniform element distribution are obtained by heating the liquid mixture of raw materials in a simple domestic microwave oven only for 5 minutes and without waste liquid production. Subsequently, the microwave-synthesized NCM 622 powders are further calcined in high-temperature with different temperatures and time in order to obtain the final products with high crystallinity and good electrochemical performances. As a result, the optimal NCM 622 cathode material calcined at 800 °C for 14 h exhibits excellent irregular polyhedral morphology and low degree of Li + /Ni + mixing, whilst displays high first discharge capacity of 179.1 mAh g −1 and 204.9 mAh g −1 with the capacity retention of 88.21 % and 81.36 % (100 cycles) in 3–4.3 V and 3–4.5 V (0.2 C), respectively.