Core-shell Ni-rich NMC-Nanocarbon cathode from scalable solvent-free mechanofusion for high-performance 18650 Li-ion batteries

ABSTRACT Although the Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode can store high electrical energy suitable for powering long-range electric vehicles, its poor cycling stability still hinders the practical application. Herein, a surface coating approach using a green scalable solvent-free mechanofusion process is introduced to prepare an infusing thin layer carbon nanosphere shell to improve the intrinsic drawbacks of NMC811 including poor electrical conductivity, Li+/Ni2+ cation mixing, parasitic reactions with electrolytes, and micro-crack formation. The in operando XRD of NMC811@carbon core@shell so-called NMC811cs reveals the smooth and fast phase transition through H1-H2-H3 with higher Li utilization and better stability even though it shows larger abrupt change in c lattice parameter compared to the pristine NMC811. In addition, the onset potential of CO2 and H2 evolution is found to be extended by the carbon coating as observed by an online Differential Electrochemical Mass Spectrometry. Finally, the practical application of the NMC811cs is demonstrated by the 18650 battery prototype which shows higher specific capacity and energy as well as excellent cycling stability compared to the pristine NMC811. This work provides both fundamental understanding and economical strategy towards highly stable and practical high-energy Li-ion batteries.