Preparation and characterization of LiFePO4 thin films as cathode materials for lithium ion battery
(1.湖南省湘西土家族苗族自治州吉首市吉首大学化学与化学工程2.湖南省湘西土家族苗族自治州吉首市吉首大学化学化工学院)
Abstract: LiFePO4 thin films were prepared by sol-gel technique. The phase and surface morphology were characterized by X-ray diffraction and scanning electron microscopy. The electrochemical properties of the thin films were measured by cyclic voltammetry, galvanostatic charge-discharge experiments and electrochemical impedance spectroscopy in 1 mol/L LiPF6/EC-DMC solution using lithium metal as both counter and reference electrodes. The films prepared by this method are of pure LiFePO4 phase. The capacity of the film annealed at 700 ℃ for 30 min is 145 mA？h/g, and the capacity loss per cycle is 0.06% after being cycled 50 times. The electrochemical impedance spectroscopy shows that the diffusion rate of lithium ion in LiFePO4 thin film is 5.1×10？14cm2/s.
Key words: thin films; lithium iron phosphate; lithium-ion battery; sol-gel