Plasma-assisted reduced graphene oxide-wrapped Ni-rich cathode materials for Li-ion batteries

Ni-rich layered oxides such as Li Ni 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) offer high specific capacity for lithium-ion batteries but exhibit limited rate performance and structural degradation at high voltages. In this study, we present a plasma-assisted strategy to reduce graphene oxide (GO), forming a uniform reduced graphene oxide (rGO) coating on NMC811 particles. The optimized 7 wt% rGO wrapping significantly improves electrochemical performance, delivering an initial discharge capacity of 212 mAh g −1 and retaining 82 % capacity after 100 cycles at 1C. In contrast, pristine NMC811 demonstrates 196 mAh g −1 with 73 % retention under the same conditions. Structural and surface analyses confirm that the rGO wrapping maintains the layered crystal structure and preserves the original oxidation states of transition metals in NMC811. This conformal rGO wrapping also enhances rate capability and high-voltage cycling stability by facilitating lithium-ion diffusion and improving electrode integrity. The surface modification does not significantly alter the bulk properties of NMC811, highlighting the efficiency and scalability of this technique. Our results demonstrate that rGO-based surface engineering offers a promising route to address the intrinsic limitations of Ni-rich cathodes, paving the way for more durable and high-performing lithium-ion batteries. • Nitrogen plasma enables reduction of GO on NMC811 surface without toxic chemical reductants. • Uniform rGO shell enhances conductivity and protects cathode–electrolyte interface. • NMC811/rGO-7 delivers 212 mAh g −1 and 82 % capacity retention after 100 cycles at 1C. • rGO layer suppresses Ni 2+ /Li + cation mixing and phase degradation under high voltage. • Demonstrates a scalable, low-temperature, and sustainable coating strategy for LIBs.