Single-Crystal, Highly Ni-Rich LiNi0.9Co0.055Mn0.045O2 Cathode Material: Spray Pyrolysis Synthesis and Grain Size Regulation

Highly Ni-rich layered oxide cathode materials are promising candidates for high-performance lithium-ion batteries (LIBs) due to their high capacity and low cost. However, traditional methods for preparing single-crystal, highly Ni-rich cathode materials (LiNi_xCo_yMn_zO₂, x ≥ 0.9), such as coprecipitation and sol-gel processes, are complex and environmentally detrimental and present challenges, including difficulty in continuous production, poor uniformity, and performance instability. In this study, we report the synthesis of single-crystal, highly Ni-rich LiNi_0.9Co_0.055Mn_0.045O₂ (NCM90) cathode materials via a novel spray pyrolysis method. To overcome the issue of small particle sizes in materials prepared by spray pyrolysis followed by sintering, we introduced an annealing process, increasing the particle size of NCM90 from 0.31 to 0.81 μm. A comprehensive analysis of the morphology, structure, and electrochemical performance of NCM90 materials was conducted during spray pyrolysis, high-temperature sintering, and annealing. Under optimized conditions: spray pyrolysis at 800 °C, sintering at 800 °C, and annealing at 650 °C, high-performance NCM90 with an initial discharge capacity of 225.7 mAh g^-1 and a 50-cycle capacity retention of 84.5% was achieved. This study clarifies the impact of synthesis conditions on the performance of single-crystal, highly Ni-rich cathode materials prepared by spray pyrolysis, providing new insights for the development of high-performance LIBs.