Dry basal plane graphene wrappings on spherical nickel-rich oxide layered particles for lithium-ion batteries

Particle-to-particle dry graphene coatings on Ni-rich layered oxide materials are proposed for high-energy lithium-ion batteries (LIBs) to mitigate the inherent and engineering challenges related to the electrochemically fragile surfaces, as well as limiting electrode thickness and density. Utilizing a shear stress-based coating process without supplementary solvent or heat treatment, graphene sheets derived from graphene powder are applied onto the surface of spherical LiNi_0.89Co_0.055Mn_0.055O₂ (NCM) material. This process achieves a coating thickness equivalent to or fewer than 10 layers of graphene and exposes the basal plane. The graphene-coated material increases particle hardness and mitigates degradation caused by inter-particle pressure, enabling the formation of high-density electrodes without pulverization. In the absence of additional carbon-conducting agents for the high-density composite electrode with a density of 4.0 g cm⁻³, it significantly enhances rate capability, demonstrating more than 5 times improvement by achieving 149.4 mAh g⁻¹ at 2 C compared to the bare sample (28.9 mAh g⁻¹). Furthermore, the dry graphene coating enables the high areal capacity of 6.98 mAh cm⁻². By exposing the basal plane of the graphene coating, the process enhances chemical stability, effectively inhibiting side reactions at the interface and mitigating cycle degradation.