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

Layered LiNi1/3Mn1/3Co1/3O2 (NMC) positive materials were synthesized by efficient, low cost and easy manageable methods such as oxalate co-precipitation and sol-gel processes. Preliminary electrochemical results show that sol-gel sample provide better results than co-precipitated samples. With the aim to improve the properties of the co-precipitated samples these were coated with carbon and alumina bearing in mind the co-precipitated method is suitable for large scale production. The subsequently performed local structure investigations revealed well crystallized layered cathode materials with α-NaFeO2-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 furthermore the existence of a thin film that encapsulates the oxide particles. 7Li magic angle spinning nuclear magnetic resonance (7LiMAS 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.