Study on Mg²⁺/F^--doped Li-Mn-O Spinel as the Cathode for Power Plastic Li-ion Batteries

Guan Yonghui, Zhao Xinbing^*, Cao Gaoshao, Zhong Yaodong
(Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027)

Abstract A 10kg-level isotropically cubic spinel of the Mg²⁺ or F^--doped Li-Mn-O, as the cathode for power plastic Li-ion batteries(PPLIB), was synthesized by solid state reaction method at 750℃ in air and characterized by XRD and electrochemical performance testing. It was found that PPLIB based on Li_0.98Mn_1.94Mg_0.06O₄/MCMB(Mesocarbon Microbeads) had good electrochemical performance. Its discharge capacity was about 75% of the first discharge capacity 90mAh/g(vs.Li:106 mAh/g) for the cathode after running for 300 cycles at 0.5C charge and discharge rate. PPLIB based on Li_0.98Mn_1.96Mg_0.06O₄/MCMB also had good cyclability and a large increase of capacity, its discharge capacities in the 1^st and 200^th cycles were 98 mAh/g(vs.Li:115 mAh/g) and 73 mAh/g for the cathode, respectively. A great improvement of capacity having first discharge capacity 106mAh/g(vs.Li:120 mAh/g) for the cathode was achieved using LiMn_1.96Mg_0.04O_3.96F_0.04, however its cyclability became poor.
Key words LiMn₂O₄, Mg²⁺ and F ^- dopants, Plastic Li-ion batteries, Electrochemical property