Papers by Keyword: LiFePO4/C

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Authors: Wen Qin Wang, Jun Jie Hao, Zhi Meng Guo, Qing Ye
Abstract: LiFePO4/C cathode material with particle size of 5~6 μm and tap density of 1.67 g•cm-3 was prepared based on spherical crystal FePO4•2H2O powders. The spherical crystal FePO4•2H2O powders were first prepared by a simple hydrothermal synthesis via the amorphous FePO4•2H2O solution maintained at 150°C for 12 h without any supplementary equipment. The produced LiFePO4/C powders exhibited the initial discharge capacity of 137 and 118 mAh•g-1 at 0.1 C and 0.5 C, respectively. The volumetric capacity of the spherical LiFePO4/C powders corresponded to 230 and 197 mAh•cm-3, which are remarkably higher than irregularity powders. The high-density spherical LiFePO4/C powders produced by this novel method can be considered as a very promising candidate in the high-power batteries.
Authors: Feng Wu, Hua Quan Lu, Yue Feng Su, Shi Chen, Yi Biao Guan
Abstract: A simple strategy of pre-doping lithium ion into carbon negative electrode for lithium ion capacitor was introduced. In this strategy, a kind of Li-containing compound was added directly into the positive electrode of the lithium ion capacitor (LIC). When the lithium ion capacitor was charging first time, the Li-containing compound releases Li+, and the pre-doping of lithium ion into the negative electrode was performed. Here, we developed a lithium ion capacitor using Meso-carbon microbeads (MCMB)/activated carbon (AC) as the negative and positive electrode materials, respectively and use the lithium iron phosphate (LiFePO4) as the Li-containing compound, which supply the Li+ ions for pre-doping. The results demonstrated that, by adding 20 percent of LiFePO4 into the positive electrode, the efficiency of the capacitor increases from lower than 60% up to higher than 90%, and the capacitor shows good capacitance characteristics and high capacity.
Authors: Zhi Feng Zeng, Hai Yan Zhang, Xi Duo Hu
Abstract: The LiFePO4/MWCNTs composite used as cathode was synthesized by ball milling. XRD and SEM experiments demonstrated that MWCNTs didn’t change the olivine structure of LiFePO4 and that MWCNTs decentralized into the grains of LiFePO4 and working as electric bridge improving the electrochemical properties of LiFePO4. The electrochemical performance of the composite electrodes with different MWNTs in diameter were studied by button cell. The result indicated that the composite with largest diameter MWNTs exhibited best electrochemical performance. The first charge-discharge specific capacity of the composite with MWNTs of 60-100nm in diameter were 136mAh/g-1 and 129 mAh/g-1 respectively at 0.1C rate under room temperature. The difference between charge-discharge platforms of the composite electrode was the least compared to the others. This phenomenon showed that the material had the largest chemical diffusion coefficient of lithium. At the same time, the capacity of the composite only lost 4.0% after 10 cycles and kept constant after 20 cycles.
Authors: D. Jugović, N. Cvjetićanin, M. Mitrić, S. Mentus
Abstract: Olivine-type lithium iron phosphate (LiFePO4) powders were synthesized applying three different methods: solid state reaction at high temperature, ultrasonic spray pyrolysis, and sonochemical treatment. The samples were characterized by X-ray powder diffraction (XRPD). Particle morphologies of the obtained powders were determined by scanning electron microscopy (SEM). It was found that structural and microstructural parameters of this material were strongly dependent on the synthesis conditions. We present here the results obtained upon optimization of each procedure for designing this cathode material.
Authors: Hal Bon Gu, Dae Kyoo Jun
Abstract: The cycle behavior and rate performance of C-LiFePO4/SPE/Li cell have been investigated at 25 °C. Carbon coated LiFePO4 (C-LiFePO4) was employed as cathode and 25PVDFLiClO4EC10PC10 was used as solid polymer electrolyte (SPE). The C-LiFePO4/SPE/Li cell exhibited above 140 mAh/g of discharge capacity at 0.1 mA/cm2 and excellent reversible cyclability with a stable capacity on cycling. In addition, the discharge capacity of C-LiFePO4/SPE/Li cell was 150 mAh/g at 0.1 C (0.02 mA/cm2) and 130 mAh/g at 1 C (0.2 mA/cm2), respectively.
Authors: Xiao Ling Ma, You Xiang Zhang
Abstract: FePO4·2H2O nanoplates are synthesized by a hydrothermal method, using Fe (III) compound as the iron source and are lithiated to LiFePO4/C by a simple rheological phase mathod. The structure, morphology and electrochemical properties of the FePO4·2H2O nanoplates and LiFePO4/C composites synthesized by changing the concentration of the reactants were characterized in detail by X-ray (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope and electrochemical measurement. The LiFePO4/C nanoparticles lithiated from the FePO4·2H2O nanoplates when there were about 10 mmol Fe3+ in 20 ml water solution demonstrates excellent cyclic performance.
Authors: Yu Li Zhang, Zhi Jian Liu, Jian Hua Xia, Xi Lin, Lu Xing Chen
Abstract: LiFePO4/C composite with different types of organic carbon sources has been synthesized by carbon thermal reduction technique. The physical characteristics and electrochemical properties of LiFePO4/C composite have been studied compared with commercial products. It is shown that good carbon-coated LiFePO4/C composite can be obtained with 13wt.% glucose as carbon source, which has effected on the good processing performance due to its suitable specific surface area of 26.3m2/g and high tap density of 1.3g/cm3. Furthermore, it has contributed to the high-rate electrochemical property with discharge capacity of 128mAh/g at 1C (1C=170 mAh/g).
Authors: Guang Chuan Liang, Xiao Ke Zhi, Xiu Qin Ou, Li Wang
Abstract: Mg2+ doped LiFePO4 was synthesized from Li3PO4, FeSO4 and MgSO4 by a hydrothermal synthesis at 150 °C(Li1-xMgxPO4, x=0.00, 0.01,0.02,0.04,0.06). The samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and charge-discharge test. The results showed that Mg2+ dissolved in the LiFePO4 lattice. When the content is in the range of 0 to 6 mol%, Mg2+ caused the shrinkage of LiFePO4 cell volume. The capacity of doped and undoped samples at low discharging rate was similar, about 145mAhg-1 for 0.2C. But the sample doped with 2-4 mol% Mg2+ has higher capacity and longer cycle lifetime than the undoped one at 5C.
Authors: Yan Wen Lu, Yu Ge, Yue Feng Tang
Abstract: A one-step carbon thermal method was used to prepare LiFePO4/C particles by using normal Fe2O3, LiH2PO4 and sucrose as raw materials. The effect of H2 content in the sintering atmosphere of N2 on the morphology and the electrochemical performance were investigated. LiFePO4/C materials were characterized by X-ray diffraction, scanning electron microscopy and the elemental analyzer. The results show that the precursor sintering under the atmosphere of 8%H2+N2 exhibits the highest electrochemical capacity (162.3 mAh/g at 0.1C) .
Authors: Wen Qiang Gong, Yi Feng Chen, Bing Sun, Han Chen
Abstract: Aniline was polymerized on the surface of LiFePO4 particles by in-situ polymerization technique, forming LiFePO4/polyaniline composites. The composites were characterized by Thermo gravimetric analysis, specific surface area tests, high resolution transmission electron microscopy observation. The specific capacity, rate capability and cycling stability of composites were studied by charge-discharge tests. The experimental results show that the LiFePO4/polyaniline composite containing 6.75% polyaniline possesses the best electrochemical properties. Its initial capacity reaches 151.97 mAh.g-1 at C/10 rate, its cycling stability is excellent, its specific capacity is 124.89 mAh.g-1 at 1 C rate, its capacity loss is only 17.82% when rate increased from C/10 to 1 C.
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