High-Performance Li-Ion Batteries Using Nickel-Rich Lithium Nickel Cobalt Aluminium Oxide-Nanocarbon Core-Shell Cathode: In Operando X-ray Diffraction.

Nickel-rich layered, mixed lithium transition-metal oxides have been pursued as a propitious cathode material for the future-generation lithium-ion batteries due to their high energy density and low cost. Nevertheless, acute side reactions between Ni and carbonate electrolyte lead to poor cycling as well as rate performance, which limits their large-scale applications. Here, core-shell like LiNiCoAlO (NCA)-carbon composite synthesized by a solvent-free mechanofusion method is reported to solve this issue. Such a core-shell structure exhibits a splendid rate as well as stable cycling when compared to the physically blended NCA. X-ray diffraction studies show that both materials experience anisotropic structural change, i.e., stacking -axis undergoes a gradual expansion followed by an abrupt shrinkage; meanwhile, the -axis contracts during the charging process and vice versa. Interestingly, the core-shell material displays a significantly high reversible capacity of 91% in the formation cycle at 0.1C and a retention of 84% at 0.5C after 250 cycles, whereas pristine NCA retains 71%. The robust mechanical force assisted dry coating obtained by the mechanofusion method shows improved electrochemical performance and demonstrates its practical feasibility.