Facile synthesis of crack-free single-crystalline Al-doped Co-free Ni-rich cathode material for lithium-ion batteries

Co-free, Ni-rich cathode materials have aroused enormous attentions for the low cost, sustainable development of lithium-ion batteries. However, it is not easy to fabricate single-crystalline Ni-rich cathode materials from the hierarchical structured precursors via coprecipitation method. Furthermore, it is difficult to introduce Al dopant during the coprecipitation process to obtain high quality Ni-rich cathode material owing to the rapid sediment of Al³⁺. Herein, we developed a one-step stirring-assisted cation chelation and reassembly route for fabricating crack-free single-crystalline, Al-doped Co-free Ni-rich cathode material. The fabricated LiNi_0.8Mn_0.16Al_0.04O₂ shows a high capacity of 204 mAh g⁻¹ at 0.1C, excellent rate capability (143 mAh g⁻¹ at 10C), and good cycling stability (an initial specific capacity of 178 mAh g⁻¹ with capacity retention of 82.2% at 1C over 200 cycles). Furthermore, when tested at a raised temperature of 55 °C, it exhibited an initial capacity of 194.7 mAh g⁻¹ with capacity retention of 82.1% at 1C over 100 cycles. The outstanding electrochemical performance can be ascribed to the synergistic effect of single crystalline structure and successful doping of Al element in the cathode, which enable fast ion and electron transport, suppress Li/Ni mixing and maintain the structural stability.