Pristine and coated LiNi1/3Mn1/3Co1/3O2 as positive electrode materials for Li-ion batteries

Layered LiNi_1/3Mn_1/3Co_1/3O₂ (NMC) positive materials were synthesized by efficient, low-cost, and easily manageable methods such as oxalate co-precipitation and sol-gel processes. Preliminary electrochemical results show that sol-gel samples provide better results than co-precipitated samples.With the aim of improving the properties of the co-precipitated samples, these were coated with carbon and alumina, considering the co-precipitation method’s suitability for large-scale production. The subsequently performed local structure investigations revealed well-crystallized layered cathode materials with an αNaFeO₂-type structure (R-3m space group).Sample tests using both the scanning electron microscope (SEM) and the transmission electron microscope (TEM) showed submicron particles with a slight tendency to agglomerate and the existence of a thin film encapsulating the oxide particles. ⁷Li magic angle spinning nuclear magnetic resonance (⁷Li MAS NMR) measurements were carried out for pristine and coated samples to compare the cation arrangement in the transition metal layers.Finally, electrochemical tests revealed a remarkable improvement in capacity retention of the coated oxides compared to the parent compounds.