Pure Phase Disordered LiMn_(1.45)Cr_(0.1)Ni_(0.45)O_4 by a Post-Annealing Treatment

摘要

A new post-annealing treatment at ca. 600 °C was used to modify the oxygen deficiency during the synthesis of the spinel LiMn_(1.45)Cr_(0.1)Ni_(0.45)O_4 cathode 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 LiMn_(1.5)Ni_(0.5)O_4. LiMn_(1.45)Cr_(0.1)Ni_(0.45)O_4 delivered a reversible capacity of 104 mAh g~(-1) at 1C rate. After 125 cycles, about 99% of reversible capacity was retained for the LiMn_(1.45)Cr_(0.1)Ni_(0.45)O_4 in contrast with 6% capacity loss for the commercial LiMn_(1.5)Ni_(0.5)O_4. Electrochemical impedance spectroscopy measurements revealed that the LiMn_(1.45)Cr_(0.1)Ni_(0.45)O_4 had a smaller surface resistance, which may be due to the segregation of Ni from the surface to the bulk.