How uniform particle size of NMC90 boosts lithium ion mobility for faster charging and discharging in a cylindrical lithium ion battery cell

Abstract

The pursuit of high-performing cathode materials for next-generation lithium ion batteries has focused on increasing the nickel content of the material. However, this study reveals that particle size uniformity is a more decisive factor in battery performance than the nickel content alone. Using in operando X-ray diffraction, in situ gas evolution, and Atlung intercalant diffusion, we compared two promising cathode materials: LiNi_0.8Mn_0.1Co_0.1O₂ (NMC80) and LiNi_0.9Mn_0.05Co_0.05O₂ (NMC90). We found that the NMC90 cell, with its more uniform particle size, exhibits a remarkable accumulation energy density of 558 kW h kg_NMC⁻¹, which is 22% higher than that of the NMC80 cell. Also, the NMC90 cell unexpectedly has a 20% better capacity retention, a 50-fold higher discharge capacity at the 5C rate, and an Atlung lithium diffusion coefficient that is one order of magnitude higher after 1000 cycles. In situ gas analysis at a high voltage of 4.5 V reveals that the NMC80 cell generates 1.75 times more CO₂ than the NMC90 cell. These findings illuminate the intricate relationship between the nickel content, particle size uniformity, and battery performance. They offer vital insights for optimizing cathode materials in future lithium ion batteries.