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A new post-annealing treatment at ca. 600 °C was used to modify the oxygen deficiency during the synthesis of the spinel LiMn1.45Cr0.1Ni0.45O4cathode for Li-ion batteries. It is an effective way to eliminate the impurity phase without changing the crystal chemistry. Small amount of substituting Cr leads to better rate performance and cyclability at room temperature, compared to commercial LiMn1.5Ni0.5O4. LiMn1.45Cr0.1Ni0.45O4delivered a reversible capacity of 104 mAh g-1at 1C rate. After 125 cycles, about 99% of reversible capacity was retained for the LiMn1.45Cr0.1Ni0.45O4in contrast with 6% capacity loss for the commercial LiMn1.5Ni0.5O4. Electrochemical impedance spectroscopy measurements revealed that the LiMn1.45Cr0.1Ni0.45O4had a smaller surface resistance, which may be due to the segregation of Ni from the surface to the bulk.

LiFePO4 nano-particles have been prepared by grinding ingot synthesized in the molten state. Formatting 25-nanometer particles was obtained by subsequent jet and wet milling. These primary particles tend to segregate to form secondary particles of size ∼100 nm, for which surface effects become increasingly important. Study of the electrochemical properties of Li//LiFePO4 cells showed that the cell performance appeared to be strongly dependant of the synthetic route used. The best electrode material formed by wet milling followed by 2 wt.% carbon coating delivered discharge capacity of 157 mAh g-1 at C/10 rate without capacity fading after 60 cycles.