Facile synthesis and electrochemical properties of spherical LiNi_0.85−xCo_0.15Al_xO₂ with sodium aluminate via co-precipitation

Spherical nickel rich layer cathode materials (LiNi_0.85−xCo_0.15Al_xO₂ (x = 0.02, 0.05 and 0.10), NCA) with excellent electrochemical performance for high energy densities lithium-ion batteries are successfully synthesized by a continuous co-precipitation method. An elaborate design of Al solution with sodium aluminate is successfully adopted, which can efficiently prevent rapid precipitation of Al(OH)₃ and obtain the precipitated precursors. The thermodynamic model is established in the Ni—Co—Al—NH₃—H₂O system and investigation of precipitation mechanism is carried out systematically, and the results demonstrate that the spherical LiNi_0.85−xCo_0.15Al_xO₂ can be obtained through this route. Charge and discharge tests show that LiNi_0.85−xCo_0.15Al_xO₂ synthesized has a high initial discharge specific capacity of 208 mAh/g at 0.1 C and a good capacity retention of 90.2% after 200 cycles at 0.5 C between 2.5 and 4.3 V. It is expected that performance of NCA electrodes for advancing lithium-ion batteries could be improved with the new process proposed in this study.