|
Olivine phase LiFePO4 due to good security , circulatory , inexpensive and environmentally friendly raw materials , etc., are considered to be very promising new generation of lithium -ion secondary battery cathode materials by domestic and foreign scientists widespread concern . In this thesis, to Fe (NO3) 3.9 H2O, H3PO4, LiOH-H2O and PVP as raw materials, prepared by electrospinning fibers LiFePO4 , LiFePO4 LiFePO4 nanoribbons and arrays. Using TG-DTA, XRD, SEM, EDS and other modern means of testing the samples were analyzed to characterize the system . The results showed that: the fiber diameter of nano- 100m; nm band width of about 1μm, a thickness of about 150m. This article also prepared by sol-gel nanoparticles as a reference for the morphology and electrochemical properties . Select Ni and Fe S element as LiFePO4 material and P bits of doping elements , materials research doping on structure, morphology and electrochemical properties. Nanoparticles with LiFePO4 , LiFePO4 fiber , LiFePO4 array , LiFePO4 inner m band as a positive electrode active material assembly of the battery , the electrochemical performance of the test . The results show that : 1) LiFePO4 nanoparticles : in 0.1C rate , the initial discharge capacity of 143 mAh / g, 20 cycles, the capacity does not decay ; at 1C , the initial discharge capacity of 122.9 mAh / g, after 20 times cycle, the capacity drops than 105 mAh / g or so. 2) LiFePO4 fiber: at 0.1C rate , the initial discharge capacity of 160.1 mAh / g. Various magnifications showed good capacity retention . When in 2C after 20 cycles , the attenuation rate of less than 6.15% . 3) LiFePO4 Array: In O.1C magnification , the first discharge capacity 162.5 mAh / g. No apparent attenuation of the magnification . When in 2C after 20 cycles , the attenuation rate of less than 5%. 4) LiFePO4 nanoribbons : at 0.1C rate , the initial discharge capacity of 154.6 mAh / go each magnification showed a higher discharge capacity after 20 cycles , respectively, no attenuation. 2C when after 20 cycles, the attenuation rate of less than 1.5%.
|