ZHANG Jun 1,4, LUO Shaohua 2,3,4, ZHAI Yuchun 1,3, WANG Yingling 1,3,4, HUANG Hongbo 1,4,
LIU Cailing 1,4,LI Xian 3,HAO Aimin 2,3,4
(1.School of Metallurgy, Northeastern University, Shenyang 110004, Liaoning, China; 2.School of Materials Science and
Engineering, Northeastern University, Shenyang 110004, Liaoning, China; 3.School of Resources and Materials, Northeastern
University at Qinhuangdao, Qinhuangdao 066004, Heibei, China;4.Key Laboratory of Dielectric and Electrolyte Functional Material
Hebei Province, Qinhuangdao 066004, Heibei, China)
Abstract: The olivine-type LiMn1-xNixPO4/C cathode materials have been synthesized by hydrothermal method using PEG-400 as solvent and carbon source. The effects of Ni doping contents LiMnPO4/C are investigated systematically by experimental research including XRD, SEM,charge-discharge tests and CV analysis on the crystal structure, micromorphology and electrochemical properties. The results indicate that the sample has spherical-like particles with the primary particles size ranging from 50-100 nm. At 0.05 C rate, the initial discharge capacities of LiMn1-xNixPO4/C (x=0, x=0.04, x=0.08, x=0.12) are 123.7 mAh/g,138.6 mAh/g, 145.1 mAh/g and 129.1 mAh/g, respectively. After 20 cycles,the capacities decrease to 111.3 mAh/g, 128.3 mAh/g, 138.9 mAh/g and 121.8 mAh/g with the capacities retention of 89.98%, 92.57%, 95.72% and 94.35%. Among all the doped samples, LiMn0.92Ni0.08PO4/C shows better cyclic performance and rate capability with the discharge capacity of 145.1 mAh/g,143.8 mAh/g, 140.2 mAh/g and 136.9 mAh/g at 0.05 C, 0.1 C, 0.5 C and 1 C in order. The cycle reversibility of doped samples improve, and restrain the polarization phenomenon in the lithium ions intercalation/deintercalation process.
Key words: Lithium-ion battery; LiMnPO4; Ni ion doping; hydrothermal method; Rate performance