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A novel synthesis of LiFePO_4/C from Fe_2O_3 without extra carbon or carbon-containing reductant 被引量:5
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作者 肖政伟 胡国荣 《Journal of Central South University》 SCIE EI CAS 2014年第6期2143-2149,共7页
A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced: Fe2O3 (+NH4H2PO4)→Fe2P2O7(+Li2CO3+glucose)→LiFePO4/C. X-ray diffractometry (XRD), Fourier trans... A novel synthesis of LiFePO4/C from Fe2O3 with no extra carbon or carbon-containing reductant was introduced: Fe2O3 (+NH4H2PO4)→Fe2P2O7(+Li2CO3+glucose)→LiFePO4/C. X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were utilized to characterize relevant products obtained in the synthetic procedure. The reaction of Fe2P2O7 and Li2CO3 was investigated by thermo-gravimetric and differential thermal analysis (TGA-DTA). Fe2O3 is completely reduced to Fe2P2O7 by NH4H2PO4 at 700 ℃ and Fe2P2O7 fully reacts with Li2CO3 to form LiFePO4 in the temperature range of 663.4-890 ℃. The primary particles of LiFePO4/C samples prepared at 670, 700 and 750 ℃ respectively exhibit uniform morphology and narrow size distribution, 0.5-3 μm for those obtained at 670 and 700 ℃ and 0.5-5 μm for those obtained at 750 ℃. LiFePO4/C (carbon content of 5.49%, mass fraction) made at 670 ℃ shows an appreciable average capacity of 153.2 mA·h/g at 0.1C in the first 50 cycles. 展开更多
关键词 lithium ion phosphate ferric oxide ferrous pyrophosphate lithium ion cells
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Nanocomposite LiFePO_4·Li_3V_2(PO_4)_3/C synthesized by freeze-drying assisted sol-gel method and its magnetic and electrochemical properties 被引量:3
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作者 刘丽英 肖文学 +7 位作者 郭剑峰 崔艳艳 柯曦 蔡伟通 刘军 陈易明 施志聪 侴术雷 《Science China Materials》 SCIE EI CSCD 2018年第1期39-47,共9页
Nano-sized LiFePO_4·Li_3V_2(PO_4)_3/C was synthesized via a sol-gel route combining with freeze-drying. X-ray diffraction results show that this composite mainly consists of olivine Li Fe PO4 and monoclinic Li3... Nano-sized LiFePO_4·Li_3V_2(PO_4)_3/C was synthesized via a sol-gel route combining with freeze-drying. X-ray diffraction results show that this composite mainly consists of olivine Li Fe PO4 and monoclinic Li3 V2(PO4)3 phases with small amounts of V-doped LiFePO_4 and Fe-doped Li_3V_2(PO_4)_3. The magnetic properties of LiFePO_4·Li_3V_2(PO_4)_3/C are significantly different from LiFePO_4/C. Trace quantities of ferromagnetic impurities and Fe_2P are verified in LiFePO_4/C and LiFePO_4·Li_3V_2(PO_4)_3/C by magnetic tests, respectively. LiFePO_4·Li_3 V_2(PO_4)_3/C possesses relatively better rate capacities and cyclic stabilities, especially at high charge-discharge rates.The initial discharge capacities are 136.4 and 130.0 mA h g^(-1),and the capacity retentions are more than 98% after 100 cycles at 2C and 5C, respectively, remarkably better than those of LiFePO_4/C. The excellent electrochemical performances are ascribed to the mutual doping of V^(3+)and Fe^(2+), complementary advantages of LiFePO_4 and Li_3V_2(PO_4)_3 phases, the residual high-ordered carbon and Fe_2P with outstanding electric conductivity in the nanocomposite. 展开更多
关键词 lithium ion battery cathode material lithium iron phosphate lithium vanadium phosphate magnetic property
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