Studies On One-step To Prepare The Li_xFe_1-xPO₄and Its Properties

LiFeP04with olivine structure demonstrates a variety of advantages, such as wide sources of raw materials, good thermal stability, relatively reliable safety, excellent cycle performance, theoratically high specific capacity, ect. LiFePO4has been quickly widely recognized around the world due to its compatability to the pursuit of new energy resources and environmental benign, which was consequently assumed most significance and promising anode material for lithium ion batteries. However, low Li+diffusion rate and poor conductive performance seriously limit its commercialization process.LiFePO4/C and Na1-xLixFePO4/C were synthesised by hyperthermal solid-state reduction.Microstructure and morphology of the sample were characterized by means of SEM, EDS, XRD, TEM etc. Initial discharge capacity under constant current and cycle performances were also measuresd to test the electro-chemical performance of the samples.Using FePO4as the iron source, Li2CO3as lithium source, and different carbon sources such as glucose, citric acid, Poly propulene (PP) were applied to synthesised LiFePO4/C composite materials.. The optimal ball milling time (12h), calcination time (11h) and calcination temperature (700C°)were determined. Two dispersants, water and ethanol, were tried and found that ethanol showed better cycle performance and rate performance. Sodium polyacrylate (ASAP) was emploied both carbon source and Sodium source to to achieve the LiFePO4carbon coating and metal doped simutinously. Results suggested that carbon-coated LiFePO4with ASAP as a carbon source displayed a better olivine structure and a more uniform particle size distribution than with PP. Electrochemical test results exhibited better electrochemical performance with an initial discharge capacity of168mAh/g at0.1C. The sample also showed a favourable cycling stability that the discharge retention specific capacity was155m Ah/g or equivalent to92.3%of the initial discharge capacity. These results indicate that the proposed method is an efficient and practical technology to prepare LiFePO4.