A LiFePO4/（C＋Fe2P） composite cathode material was prepared by a sol-gel method using Fe（NO3）3.9H20, LiAc·H2O）, NHaH2PO4 and citric acid as raw materials, and the physical properties and electrochemical perf...A LiFePO4/（C＋Fe2P） composite cathode material was prepared by a sol-gel method using Fe（NO3）3.9H20, LiAc·H2O）, NHaH2PO4 and citric acid as raw materials, and the physical properties and electrochemical performance of the composite cathode material were investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and electrochemical tests. The Fe2P content, morphology and electrochemical performance of LiFePOa/（C＋Fe2P） composite depend on the calcination temperature. The optimized LiFePO4/（C＋FeeP） composite is prepared at 650 ~C and the optimized composite exhibits sphere-like morphology with porous structure and Fe2P content of about 3.2% （mass fraction）. The discharge capacity of the optimized LiFePO4/（C＋FeRP） at 0.1C is 156 and 161 mA.h/g at 25 and 55 ℃, respectively, and the corresponding capacity retentions are 96% after 30 cycles; while the capacity at 1C is 142 and 149 mA.h/g at 25 and 55 ℃, respectively, and the capacity still remains 135 and 142 mA-h/g after 30 cycles at 25 and 55℃, respectively.展开更多
In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying....In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying. The discharge capacity of the fast cooled was 83 mAh·g-1 and the slow cooled 121 mAh·g-1. The particle size of the synthesized powder was examined by transmission electron microscopy and distribution of Fe2P was characterized using scanning electron microscopy (SEM). In addition, two-step heat treatment was carried out for better distribution of Fe2P. X-ray diffraction (XRD) and Rietveld refinement reveal that LiFePO4/Fe2P composite consists of 95.77% LiFePO4 and 4.33% of Fe2P.展开更多
Co2＋-doped LiFePO4/C composite material was prepared by solid-state synthesis method using Fe2O3,Li2CO3 and NH4H2PO4 as the starting materials.The structures and elec-trochemical performance of samples were studied b...Co2＋-doped LiFePO4/C composite material was prepared by solid-state synthesis method using Fe2O3,Li2CO3 and NH4H2PO4 as the starting materials.The structures and elec-trochemical performance of samples were studied by XRD,SEM and constant current charge-discharge method.The results showed that the Co2＋ doping did not change the crystal structure of LiFePO4.The unit cell volume changed with the increase of Co2＋,and reached the maximum at x = 0.04.The LiFe0.96Co0.04PO4/C sample proved the best electrochemical properties.Its initial discharge capacity was 138.5 mA·h /g at 1 C rate.After 30 cycles,the capacity remained 127.7 mA·h /g,and the capacity retention rate was 92.2%.展开更多
In order to obtain a new precursor for LiFePO4, Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃ using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere. Using the as-prepare...In order to obtain a new precursor for LiFePO4, Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃ using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere. Using the as-prepared Fe2P2O7, Li2CO3 and glucose as raw materials, pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃ in an argon atmosphere. X-ray diffractometry and scanning electron microscopy（SEM） were employed to characterize the as-prepared Fe2P2O7, LiFePO4 and LiFePO4/C. The as-prepared Fe2P2O7 crystallizes in the Cl space group and belongs to β-Fe2P2O7 for crystal phase. The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0 μm. During the Li^＋ ion chemical intercalation, radical P2O7^4- is disrupted into two PO4^3- ions in the presence of O^2-, thus providing a feasible technique to dispose this poor dissolvable pyrophosphate. LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA·h/g, respectively.展开更多
以磷铁废渣(Fe1.5P)和温室效应气体CO_2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO_4)的前驱体Fe_2P_2O_7,并研究了其合成过程对LiFePO_4正极材料储能性能的影响。采用SEM观察了LiFePO_4的表面形貌,采用XRD分析了LiFePO_4和Fe_2P_2O_...以磷铁废渣(Fe1.5P)和温室效应气体CO_2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO_4)的前驱体Fe_2P_2O_7,并研究了其合成过程对LiFePO_4正极材料储能性能的影响。采用SEM观察了LiFePO_4的表面形貌,采用XRD分析了LiFePO_4和Fe_2P_2O_7的晶体结构。进一步对该方法进行优化,发现Fe1.5P与磷酸混合物(nFe1.5P∶nH3PO4=1∶1)在800℃热处理6 h合成的Fe_2P_2O_7对应的LiFePO_4/C电化学性能最好,在0.1C,0.2C,0.5C和1C倍率下的容量分别可达130,126,117和108 m Ah·g^(-1)。展开更多
基金Project(50571091) supported by the National Natural Science Foundation of ChinaProject(09C947) supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘A LiFePO4/（C＋Fe2P） composite cathode material was prepared by a sol-gel method using Fe（NO3）3.9H20, LiAc·H2O）, NHaH2PO4 and citric acid as raw materials, and the physical properties and electrochemical performance of the composite cathode material were investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and electrochemical tests. The Fe2P content, morphology and electrochemical performance of LiFePOa/（C＋Fe2P） composite depend on the calcination temperature. The optimized LiFePO4/（C＋FeeP） composite is prepared at 650 ~C and the optimized composite exhibits sphere-like morphology with porous structure and Fe2P content of about 3.2% （mass fraction）. The discharge capacity of the optimized LiFePO4/（C＋FeRP） at 0.1C is 156 and 161 mA.h/g at 25 and 55 ℃, respectively, and the corresponding capacity retentions are 96% after 30 cycles; while the capacity at 1C is 142 and 149 mA.h/g at 25 and 55 ℃, respectively, and the capacity still remains 135 and 142 mA-h/g after 30 cycles at 25 and 55℃, respectively.
基金supported by the Fund for Young Scientists of Sichuan University, China (2011SCU11081)Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20120181120103)~~
文摘In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying. The discharge capacity of the fast cooled was 83 mAh·g-1 and the slow cooled 121 mAh·g-1. The particle size of the synthesized powder was examined by transmission electron microscopy and distribution of Fe2P was characterized using scanning electron microscopy (SEM). In addition, two-step heat treatment was carried out for better distribution of Fe2P. X-ray diffraction (XRD) and Rietveld refinement reveal that LiFePO4/Fe2P composite consists of 95.77% LiFePO4 and 4.33% of Fe2P.
基金Sponsored by the Graduate Innovation Fund of Shaanxi University of Science and Technology
文摘Co2＋-doped LiFePO4/C composite material was prepared by solid-state synthesis method using Fe2O3,Li2CO3 and NH4H2PO4 as the starting materials.The structures and elec-trochemical performance of samples were studied by XRD,SEM and constant current charge-discharge method.The results showed that the Co2＋ doping did not change the crystal structure of LiFePO4.The unit cell volume changed with the increase of Co2＋,and reached the maximum at x = 0.04.The LiFe0.96Co0.04PO4/C sample proved the best electrochemical properties.Its initial discharge capacity was 138.5 mA·h /g at 1 C rate.After 30 cycles,the capacity remained 127.7 mA·h /g,and the capacity retention rate was 92.2%.
基金Project(50604018)supported by the National Natural Science Foundation of China
文摘In order to obtain a new precursor for LiFePO4, Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃ using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere. Using the as-prepared Fe2P2O7, Li2CO3 and glucose as raw materials, pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃ in an argon atmosphere. X-ray diffractometry and scanning electron microscopy（SEM） were employed to characterize the as-prepared Fe2P2O7, LiFePO4 and LiFePO4/C. The as-prepared Fe2P2O7 crystallizes in the Cl space group and belongs to β-Fe2P2O7 for crystal phase. The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0 μm. During the Li^＋ ion chemical intercalation, radical P2O7^4- is disrupted into two PO4^3- ions in the presence of O^2-, thus providing a feasible technique to dispose this poor dissolvable pyrophosphate. LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA·h/g, respectively.
基金financially supported by the National Science Foundation of China (Grant No.21576170)the Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan province (Grant No.2017CL19)~~
文摘以磷铁废渣(Fe1.5P)和温室效应气体CO_2为原料,以磷酸为补充磷源合成磷酸铁锂(LiFePO_4)的前驱体Fe_2P_2O_7,并研究了其合成过程对LiFePO_4正极材料储能性能的影响。采用SEM观察了LiFePO_4的表面形貌,采用XRD分析了LiFePO_4和Fe_2P_2O_7的晶体结构。进一步对该方法进行优化,发现Fe1.5P与磷酸混合物(nFe1.5P∶nH3PO4=1∶1)在800℃热处理6 h合成的Fe_2P_2O_7对应的LiFePO_4/C电化学性能最好,在0.1C,0.2C,0.5C和1C倍率下的容量分别可达130,126,117和108 m Ah·g^(-1)。
