Enhanced electrochemical properties of LiMnPO4/C via Li-site substitution with Mg

Li0.94Mg0.03MnPO4/C composite cathode materials for lithium ion battery with different carbon contents are synthesized by sol-gel method followed by heat treatment in the air. Environmental scanning electron microscopy measurements show that both firing temperature and carbon content affect the morphology of the end products. X-ray powder diffraction analysis indicates that the samples are olivine-structured. The galvanostatic charge-discharge results show that the optimal firing temperature registers 400 A degrees C and that the electrochemical performances of Li0.94Mg0.03MnPO4/C are improved by elevating its carbon amount. The sample with an initial conductive carbon content of 20 wt.% gives the best performances; when tested at the rate of 0.02C, 0.1C, and 1.0C between 2.8 and 4.4 V, its initial discharge capacity reaches 145.8, 103.0, and 72.8 mAhg(-1), respectively, and maintains at 100.1, 77.6, and 65.4 mAhg(-1), respectively, after 100 cycles.