| With the growing prominence of energy crisis and environmental pollution, lithium ion batteries now dominate the main market of motivation and portable devices as green energy storage, which are able to effectively relieve the problems derived from fossil fuels. As one of the core products of battery industry growing in the future, cathode material lithium iron phosphate ?LiFePO4? presents excellent performances. However, its inherent defects play an obstacle to the development and applications. Therefore the improvement in enhancing the electrochemical capabilities of materials makes a great difference in promotion of the battery.On the basis of previous research, four series of LiFe1-xMxPO4/C composites were designed and synthesized by solvothermal method coupled with calcination using amino metal phthalocyanines [MPcTa, M2?PcTa?2, M2?PcTa?2O and M2?PcTa?2C?CF3?2, M=Mn2+, Co2+, Ni2+, Cu+, Zn2+] as additives respectively. Physical performances of the composites were investigated in X-ray diffraction, infrared spectroscopy, scanning electron microscopy and transmission electron microscopy.The as-synthesized composites assembled into coin-type cells as cathode materials were studied on charge/discharge performance, AC impedance, cyclic voltammetry, rate properties and cycling stability by using charge/discharge instrument and electrochemical workstation. The results indicate that samples modified with binuclear metal phthalocyanines own the more improved electrochemical properties than mononuclear metal phthalocyanines. The composite using Mn2?PcTa?2C?CF3?2 as additive can achieve the highest initial specific discharge capacity of 154.2 mAh g-1 at 0.1 C-rate, which increases by 41.2% compared with pure LiFePO4, the capacity retention after 50 cycles reaching to 93.5%, the charge transfer resistance as low as 51.4 Q. The electrochemical performance is of great enhancement, which has got profound significance in applying and popularizing of power batteries. |
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