| dc.description.abstract | In order to meet the demand of higher energy density and higher power for modern portable electronics and for automobile applications, efforts are devoted to the development of lithium battery with higher energy and power density. This work use LiMnPO4 as cathode material, which was synthesized by Sol-gel synthesis. LiMnPO4 has higher working potential (4.0V) than LiFePO4, and is expected to deliver better electrical performance than LiFePO4. However, due to poorer electron conductivity, slower lithium ion intercalation rate, and the fact that Jahn-Teller effect in MnPO4 octahedral affects Mn ion during charging (reduction) and discharging (oxidation) cycling, LiMnPO4 shows lower capacity and cycle life than LiFePO4. To circumvent these defects, we proposed to dope the cathode material with small amount of Fe ion and Eu ion respectively in LiMnPO4 . The results shows pristine LiMnPO4 prepared by sol-gel method has a discharging capacity of 40 mAh/g at 0.01C, but the discharging capacity, battery impedance, and cycle life are all substantially improved after doping with small amount of Fe. In the most pronounced case with 6wt% doping, an increase of 50% discharging capacity is observed compared to that in pristine sample, and maintains a high working potential at 4.0V. The absence of two-steps working plateau suggested that Fe ion was distributed homogeneously in LiMnPO4 , preclude the formation of LiFePO4 phase. In the case of Eu doping, a pronounced improvement in discharging capacity and battery impedance was found with only 0.33% Eu addition in LiMnPO4. At 0.01 C charge rate this sample yield 60 mAh/g of discharging capacity which is equal to that achieved by 6% of Fe doping. | en_US |