Impact of Carbon Coating on Ni-Rich, LiNi₀.₈Mn₀.₁Co₀.₁O₂ (NMC811) Cathode Materials and Their Electrochemical Performance

Abstract

This study explores the influence of graphene-based carbon coatings on Ni-rich LiNi₀.₈Mn₀.₁Co₀.₁O₂ (NMC811) cathode materials and their electrochemical performance in lithium-ion batteries. Two coating methods were employed: a homogenizer-assisted dispersion technique (Plan A) and a solid-state method (Plan B). Structural analysis via X-ray Diffraction (XRD) revealed that all coated samples maintained a pure layered structure, with the 2.0k rpm homogenizer-coated sample exhibiting the highest Reference Intensity Ratio (RIR = 1.18), indicating reduced cation mixing. Morphological characterization using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDX) confirmed improved coating uniformity at higher homogenizer speeds and with the solid-state method. Electrochemical testing showed that the 2.0k rpm sample achieved the highest initial discharge capacity of 252.48 mAh/g, outperforming pristine NMC811 by 38.42%. However, it displayed poor cycle stability, retaining only 0.93% of its capacity after 30 cycles. In contrast, the solid-state sample retained 65.78% of its capacity, demonstrating superior long-term performance despite a lower initial capacity. These findings highlight a trade-off between energy density and cycling stability, emphasizing the importance of optimizing coating techniques to enhance the commercial viability of Ni-rich cathodes for next-generation lithium-ion batteries.