The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Jie Li - One of the best experts on this subject based on the ideXlab platform.
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lipf6 and lithium oxalyldifluoroborate blend salts electrolyte for lifepo4 Artificial Graphite lithium ion cells
Journal of Power Sources, 2010Co-Authors: Zhian Zhang, Jie Li, Fanqun Li, Xujie Chen, Xinyu WangAbstract:Abstract The electrochemical behaviors of LiPF 6 and lithium oxalyldifluoroborate (LiODFB) blend salts in ethylene carbonate + propylene carbonate + dimethyl carbonate (EC + PC + DMC, 1:1:3, v/v/v) for LiFePO 4 /Artificial Graphite (AG) lithium-ion cells have been investigated in this work. It is demonstrated by conductivity test that LiPF 6 and LiODFB blend salts electrolytes have superior conductivity to pure LiODFB-based electrolyte. The results show that the performances of LiFePO 4 /Li half cells with LiPF 6 and LiODFB blend salts electrolytes are inferior to pure LiPF 6 -based electrolyte, the capacity and cycling efficiency of Li/AG half cells are distinctly improved by blend salts electrolytes, and the optimum LiODFB/LiPF 6 molar ratio is around 4:1. A reduction peak is observed around 1.5 V in LiODFB containing electrolyte systems by means of CV tests for Li/AG cells. Excellent capacity and cycling performance are obtained on LiFePO 4 /AG 063048-type cells tests with blend salts electrolytes. A plateau near 1.7–2.0 V is shown in electrolytes containing LiODFB salt, and extends with increasing LiODFB concentration in charge curve of LiFePO 4 /AG cells. At 1 C discharge current rate, the initial discharge capacity of 063048-type cell with the optimum electrolyte is 376.0 mAh, and the capacity retention is 90.8% after 100 cycles at 25 °C. When at 65 °C, the capacity and capacity retention after 100 cycles are 351.3 mAh and 88.7%, respectively. The performances of LiFePO 4 /AG cells are remarkably improved by blending LiODFB and LiPF 6 salts compared to those of pure LiPF 6 -based electrolyte system, especially at elevated temperature to 65 °C.
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LiPF6 and lithium oxalyldifluoroborate blend salts electrolyte for LiFePO4/Artificial Graphite lithium-ion cells
Journal of Power Sources, 2010Co-Authors: Zhian Zhang, Jie Li, Fanqun Li, Xujie Chen, Xinyu WangAbstract:Abstract The electrochemical behaviors of LiPF 6 and lithium oxalyldifluoroborate (LiODFB) blend salts in ethylene carbonate + propylene carbonate + dimethyl carbonate (EC + PC + DMC, 1:1:3, v/v/v) for LiFePO 4 /Artificial Graphite (AG) lithium-ion cells have been investigated in this work. It is demonstrated by conductivity test that LiPF 6 and LiODFB blend salts electrolytes have superior conductivity to pure LiODFB-based electrolyte. The results show that the performances of LiFePO 4 /Li half cells with LiPF 6 and LiODFB blend salts electrolytes are inferior to pure LiPF 6 -based electrolyte, the capacity and cycling efficiency of Li/AG half cells are distinctly improved by blend salts electrolytes, and the optimum LiODFB/LiPF 6 molar ratio is around 4:1. A reduction peak is observed around 1.5 V in LiODFB containing electrolyte systems by means of CV tests for Li/AG cells. Excellent capacity and cycling performance are obtained on LiFePO 4 /AG 063048-type cells tests with blend salts electrolytes. A plateau near 1.7–2.0 V is shown in electrolytes containing LiODFB salt, and extends with increasing LiODFB concentration in charge curve of LiFePO 4 /AG cells. At 1 C discharge current rate, the initial discharge capacity of 063048-type cell with the optimum electrolyte is 376.0 mAh, and the capacity retention is 90.8% after 100 cycles at 25 °C. When at 65 °C, the capacity and capacity retention after 100 cycles are 351.3 mAh and 88.7%, respectively. The performances of LiFePO 4 /AG cells are remarkably improved by blending LiODFB and LiPF 6 salts compared to those of pure LiPF 6 -based electrolyte system, especially at elevated temperature to 65 °C.
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lithium oxalyldifluoroborate carbonate electrolytes for lifepo4 Artificial Graphite lithium ion cells
Journal of Power Sources, 2010Co-Authors: Jie Li, Zhian Zhang, Fanqun Li, Xujie ChenAbstract:Abstract The electrolytes based on lithium oxalyldifluoroborate (LiODFB) and carbonates have been systematically investigated for LiFePO 4 /Artificial Graphite (AG) cells, by ionic conductivity test and various electrochemical tests, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge test. The conductivity of nine electrolytes as a function of solvent composition and LiODFB salt concentration has been studied. The coulombic efficiency of LiFePO 4 /Li and AG/Li half cells with these electrolytes have also been compared. The results show that 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte has a relatively higher conductivity (8.25 mS cm −1 ) at 25 °C, with high coulombic efficiency, good kinetics characteristics and low interface resistance. With 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte, LiFePO 4 /AG cells exhibit excellent capacity retention ∼92% and ∼88% after 100 cycles at 25 °C and at elevated temperatures up to 65 °C, respectively; The LiFePO 4 /AG cells also have good rate capability, the discharge capacity is 324.8 mAh at 4 C, which is about 89% of the discharge capacity at 0.5 C. However, at −10 °C, the capacity is relatively lower. Compared with 1 M LiPF 6 EC/PC/DMC (1:1:3, v/v), LiFePO 4 /AG cells with 1 M LiODFB EC/PC/DMC (1:1:3, v/v) exhibited better capacity utilization at both room temperature and 65 °C. The capacity retention of the cells with LiODFB-based electrolyte was much higher than that of LiPF 6 -based electrolyte at 65 °C, while the capacity retention and the rate capacity of the cells is closed to that of LiPF 6 -based electrolyte at 25 °C. In summary, 1 M LiODFB EC/PC/DMC (1:1:3, v/v) is a promising electrolyte for LiFePO 4 /AG cells.
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Lithium oxalyldifluoroborate/carbonate electrolytes for LiFePO4/Artificial Graphite lithium-ion cells
Journal of Power Sources, 2010Co-Authors: Jie Li, Zhian Zhang, Fanqun Li, Xujie ChenAbstract:Abstract The electrolytes based on lithium oxalyldifluoroborate (LiODFB) and carbonates have been systematically investigated for LiFePO 4 /Artificial Graphite (AG) cells, by ionic conductivity test and various electrochemical tests, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge test. The conductivity of nine electrolytes as a function of solvent composition and LiODFB salt concentration has been studied. The coulombic efficiency of LiFePO 4 /Li and AG/Li half cells with these electrolytes have also been compared. The results show that 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte has a relatively higher conductivity (8.25 mS cm −1 ) at 25 °C, with high coulombic efficiency, good kinetics characteristics and low interface resistance. With 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte, LiFePO 4 /AG cells exhibit excellent capacity retention ∼92% and ∼88% after 100 cycles at 25 °C and at elevated temperatures up to 65 °C, respectively; The LiFePO 4 /AG cells also have good rate capability, the discharge capacity is 324.8 mAh at 4 C, which is about 89% of the discharge capacity at 0.5 C. However, at −10 °C, the capacity is relatively lower. Compared with 1 M LiPF 6 EC/PC/DMC (1:1:3, v/v), LiFePO 4 /AG cells with 1 M LiODFB EC/PC/DMC (1:1:3, v/v) exhibited better capacity utilization at both room temperature and 65 °C. The capacity retention of the cells with LiODFB-based electrolyte was much higher than that of LiPF 6 -based electrolyte at 65 °C, while the capacity retention and the rate capacity of the cells is closed to that of LiPF 6 -based electrolyte at 25 °C. In summary, 1 M LiODFB EC/PC/DMC (1:1:3, v/v) is a promising electrolyte for LiFePO 4 /AG cells.
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tetraethylammonium tetrafluoroborate as additive to improve the performance of lifepo4 Artificial Graphite cells
Electrochemical and Solid State Letters, 2010Co-Authors: Zhian Zhang, Xinyu Wang, Jie LiAbstract:Tetraethylammonium tetrafluoroborate (TEABF 4 ) is investigated as a functional additive to 1.0 M LiPF 6 /ethylene carbonatedimethyl carbonate-ethyl methyl carbonate (1:1:1 w/w/w) electrolyte for LiFePO 4 /Artificial Graphite (AG) lithium-ion battery. TEABF 4 -containing electrolytes have lower ionic conductivity than TEABF 4 -free electrolyte, but the interface impedance of Graphite/electrolyte is reduced by adding TEABF 4 . The rate capability and cycle stability of LiFePO 4 /AG cells are improved significantly by adding a certain concentration of TEABF 4 to the electrolyte, especially 0.1 M. Therefore, TEABF 4 is a promising additive for high performance lithium-ion batteries.
Yushiang Wu - One of the best experts on this subject based on the ideXlab platform.
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Electrochemical characterization with homopolymer of 2-propen-1-amine coating on Artificial Graphite/carbon/silicon composites as anode materials for lithium ion batteries
Journal of Alloys and Compounds, 2012Co-Authors: Yushiang WuAbstract:Abstract This study reports the coating of spherical Artificial Graphite/disordered carbon/silicon (AG/C/Si) with a homopolymer of 2-propen-1-amine (PAA) layer. Transmission electron microscopy (TEM) observations clearly showed that the surface of the particle was coated with an amorphous layer of PAA-coated AG/C/Si composites. The resulting PAA-coated AG/C/Si electrode structure did not destroy locally because of large volume change. For both charge and discharge at 0.1 C, the PAA-coated AG/C/Si yielded the first columbic efficiency of approximately 89.1% and the first irreversible capacity decreased from 95.1 to 55.0 mAh g−1. Moreover, the discharge capacity was 410.1 mAh g−1 after 50 cycles, and its capacity retention increased to 91.5%. The addition of PAA decreased the specific surface area (BET) of the AG/C/Si composites and reduced the direct contact between the anode electrode surface and the electrolyte. These results indicate that PAA-coated AG/C/Si composites have relatively lower electrochemical resistance and favorable cycling stability.
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electrochemical characterization with homopolymer of 2 propen 1 amine coating on Artificial Graphite carbon silicon composites as anode materials for lithium ion batteries
Journal of Alloys and Compounds, 2012Co-Authors: Yushiang WuAbstract:Abstract This study reports the coating of spherical Artificial Graphite/disordered carbon/silicon (AG/C/Si) with a homopolymer of 2-propen-1-amine (PAA) layer. Transmission electron microscopy (TEM) observations clearly showed that the surface of the particle was coated with an amorphous layer of PAA-coated AG/C/Si composites. The resulting PAA-coated AG/C/Si electrode structure did not destroy locally because of large volume change. For both charge and discharge at 0.1 C, the PAA-coated AG/C/Si yielded the first columbic efficiency of approximately 89.1% and the first irreversible capacity decreased from 95.1 to 55.0 mAh g−1. Moreover, the discharge capacity was 410.1 mAh g−1 after 50 cycles, and its capacity retention increased to 91.5%. The addition of PAA decreased the specific surface area (BET) of the AG/C/Si composites and reduced the direct contact between the anode electrode surface and the electrolyte. These results indicate that PAA-coated AG/C/Si composites have relatively lower electrochemical resistance and favorable cycling stability.
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spheroidization modification of Artificial Graphite applied as anode materials for high rate lithium ion batteries
Advanced Materials Research, 2011Co-Authors: Yushiang WuAbstract:Rate capability tests showed that Artificial Graphite after spheroidization treatment exhibited a higher capacity in the higher C-rate region (2~10C) at a 0.1 C rate charge and variable C-rates discharge. Artificial Graphite after spheroidization treatment exhibited a higher capacity in the higher C-rate region (0.5~9 C) at the same C-rate charge and discharge. These results show that Artificial Graphite after spheroidization treatment has a large amount of isotropic microstructures that lithium ions can intercalate into the graphene layers from all directions via edge-plane surfaces. Therefore, the Artificial Graphite is more suitable than natural Graphite for the anode materials of high rate batteries.
Liquan Chen - One of the best experts on this subject based on the ideXlab platform.
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storage behavior of lini1 3co1 3mn1 3o2 Artificial Graphite li ion cells
Electrochimica Acta, 2009Co-Authors: Chenghuan Huang, Kelong Huang, Yuqun Zeng, Liquan ChenAbstract:A series of Li-ion cells containing LiNi1/3Co1/3Mn1/3O2 and Artificial Graphite as the active materials, have been stored at various temperatures from 0 to 70 degrees C. The 3-electrode impedance study shows that both the solid electrolyte interphase (SEI) film resistance and charge-transfer resistance of the negative electrode first decrease and then increase during storage at 70 degrees C, while both resistances for the positive electrode increase under this condition. The reversible capacity loss of the 3-electrode cell, which is possibly attributed to dissolution of SEI film, accounts for over half of the total capacity loss after 5 weeks of storage. Gases generated from the swelling aged cell at 60 degrees C are mainly attributed to the reduction of the electrolyte on the negative electrode. A further study on the side-reaction has been done on Graphite electrodes and separators, indicating that SEI films may be rearranged and reformed on negative electrodes, and that some pores on the positive electrode side of separator are blocked due to the oxidation of electrolyte. resulting in poor Li-ion transfer and rise of the ohmic resistance during storage at elevated temperature. However, at 0 degrees C, this side-reaction is impeded. (C) 2009 Published by Elsevier Ltd.
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Storage behavior of LiNi1/3Co1/3Mn1/3O2/Artificial Graphite Li-ion cells
Electrochimica Acta, 2009Co-Authors: Chenghuan Huang, Kelong Huang, Yuqun Zeng, Liquan ChenAbstract:A series of Li-ion cells containing LiNi1/3Co1/3Mn1/3O2 and Artificial Graphite as the active materials, have been stored at various temperatures from 0 to 70 degrees C. The 3-electrode impedance study shows that both the solid electrolyte interphase (SEI) film resistance and charge-transfer resistance of the negative electrode first decrease and then increase during storage at 70 degrees C, while both resistances for the positive electrode increase under this condition. The reversible capacity loss of the 3-electrode cell, which is possibly attributed to dissolution of SEI film, accounts for over half of the total capacity loss after 5 weeks of storage. Gases generated from the swelling aged cell at 60 degrees C are mainly attributed to the reduction of the electrolyte on the negative electrode. A further study on the side-reaction has been done on Graphite electrodes and separators, indicating that SEI films may be rearranged and reformed on negative electrodes, and that some pores on the positive electrode side of separator are blocked due to the oxidation of electrolyte. resulting in poor Li-ion transfer and rise of the ohmic resistance during storage at elevated temperature. However, at 0 degrees C, this side-reaction is impeded. (C) 2009 Published by Elsevier Ltd.
Shaobai Sang - One of the best experts on this subject based on the ideXlab platform.
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Effect of Artificial Graphite and Nickel Nitrate on the Microstructure and Properties of Carbon Blocks for Blast Furnace
Key Engineering Materials, 2018Co-Authors: Tong Sheng Wang, Shaobai Sang, Yawei LiAbstract:Improving thermal conductivity of carbon blocks is one of the most important developing trends for carbon blocks. In this work, Artificial Graphite and nickel nitrate catalyst were introduced into carbon blocks with an attempt to improve thermal conductivity of carbon blocks and their effect on microstructure and properties of carbon blocks were systematically studied by means of X ray diffraction (XRD), scanning electron microscopy (SEM) and laser thermal conductivity meter. The results revealed that Artificial Graphite possessed lower oxidation activation energy than electrically calcined anthracite, and thus, higher reactivity, which could accelerate the formation of SiC whiskers in carbon blocks and have a positive effect on thermal conductivity of carbon blocks. Moreover, it was interestingly noted that one dimensional nano-carbon was catalytically formed at 1000 °C and lots of Sialon phases were formed at 1400 °C when nickel nitrate catalyst was further added in carbon blocks containing Artificial Graphite. These in-situ ceramic phases formed in carbon blocks constructed high thermal conductive network and reduced the interface thermal resistance, thus improving the thermal conductivity of carbon blocks significantly.
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a new approach to fabricate mgo c refractories with high thermal shock resistance by adding Artificial Graphite
Journal of The European Ceramic Society, 2017Co-Authors: Yawei Li, Shaobai SangAbstract:Abstract To lower the carbon content but to exhibit a better thermal shock resistance with MgO-C refractories containing 14 wt% flaky Graphite, a new approach, based on the addition of Artificial Graphite, is reported for enhancing the thermal shock resistance of such refractories with 10 wt% Graphite in the present work. The addition of Artificial Graphite (not more than 2 wt%) has a slight influence on the flexural strength of the specimens, but apparently enhances their thermal shock resistance. In particular, the specimen containing 2 wt% Artificial Graphite has a higher flexural strength after thermal shocks and a relatively closer residual strength ratio as compared to the reference specimen with 14 wt% flaky Graphite, as it is related with the formation of more AlN reinforced phases, decreased coefficient of thermal expansion as well as increased work of fracture.
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Preparation of Ceramic-Bonded Carbon Block for Blast Furnace
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: Li Yiwei, Yawei Li, Shaobai Sang, Xilai Chen, Lei Zhao, Yuanbing Li, Shujing LiAbstract:Traditional carbon blocks for blast furnaces are mainly produced with electrically calcined anthracite owing to its good hot metal corrosion resistance. However, this kind of material shows low thermal conductivity and does not meet the demands for cooling of the hearth and the bottom of blast furnaces. In this article, a new kind of a high-performance carbon block has been prepared via ceramic-bonded carbon (CBC) technology in a coke bed at 1673 K (1400 °C) using Artificial Graphite aggregate, alumina, metallic aluminum, and silicon powders as starting materials. The results showed that Artificial Graphite aggregates were strongly bonded by the three-dimensional network of ceramic phases in carbon blocks. In this case, the good resistance of the CBC blocks against erosion/corrosion by the hot metal is provided by the ceramic matrix and the high thermal conductivity by the Graphite aggregates. The microstructure of this carbon block resembles that of CBC composites with a mean pore size of less than 0.1 μm, and up to 90 pct of the porosity shows a pore size
Zhian Zhang - One of the best experts on this subject based on the ideXlab platform.
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lipf6 and lithium oxalyldifluoroborate blend salts electrolyte for lifepo4 Artificial Graphite lithium ion cells
Journal of Power Sources, 2010Co-Authors: Zhian Zhang, Jie Li, Fanqun Li, Xujie Chen, Xinyu WangAbstract:Abstract The electrochemical behaviors of LiPF 6 and lithium oxalyldifluoroborate (LiODFB) blend salts in ethylene carbonate + propylene carbonate + dimethyl carbonate (EC + PC + DMC, 1:1:3, v/v/v) for LiFePO 4 /Artificial Graphite (AG) lithium-ion cells have been investigated in this work. It is demonstrated by conductivity test that LiPF 6 and LiODFB blend salts electrolytes have superior conductivity to pure LiODFB-based electrolyte. The results show that the performances of LiFePO 4 /Li half cells with LiPF 6 and LiODFB blend salts electrolytes are inferior to pure LiPF 6 -based electrolyte, the capacity and cycling efficiency of Li/AG half cells are distinctly improved by blend salts electrolytes, and the optimum LiODFB/LiPF 6 molar ratio is around 4:1. A reduction peak is observed around 1.5 V in LiODFB containing electrolyte systems by means of CV tests for Li/AG cells. Excellent capacity and cycling performance are obtained on LiFePO 4 /AG 063048-type cells tests with blend salts electrolytes. A plateau near 1.7–2.0 V is shown in electrolytes containing LiODFB salt, and extends with increasing LiODFB concentration in charge curve of LiFePO 4 /AG cells. At 1 C discharge current rate, the initial discharge capacity of 063048-type cell with the optimum electrolyte is 376.0 mAh, and the capacity retention is 90.8% after 100 cycles at 25 °C. When at 65 °C, the capacity and capacity retention after 100 cycles are 351.3 mAh and 88.7%, respectively. The performances of LiFePO 4 /AG cells are remarkably improved by blending LiODFB and LiPF 6 salts compared to those of pure LiPF 6 -based electrolyte system, especially at elevated temperature to 65 °C.
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LiPF6 and lithium oxalyldifluoroborate blend salts electrolyte for LiFePO4/Artificial Graphite lithium-ion cells
Journal of Power Sources, 2010Co-Authors: Zhian Zhang, Jie Li, Fanqun Li, Xujie Chen, Xinyu WangAbstract:Abstract The electrochemical behaviors of LiPF 6 and lithium oxalyldifluoroborate (LiODFB) blend salts in ethylene carbonate + propylene carbonate + dimethyl carbonate (EC + PC + DMC, 1:1:3, v/v/v) for LiFePO 4 /Artificial Graphite (AG) lithium-ion cells have been investigated in this work. It is demonstrated by conductivity test that LiPF 6 and LiODFB blend salts electrolytes have superior conductivity to pure LiODFB-based electrolyte. The results show that the performances of LiFePO 4 /Li half cells with LiPF 6 and LiODFB blend salts electrolytes are inferior to pure LiPF 6 -based electrolyte, the capacity and cycling efficiency of Li/AG half cells are distinctly improved by blend salts electrolytes, and the optimum LiODFB/LiPF 6 molar ratio is around 4:1. A reduction peak is observed around 1.5 V in LiODFB containing electrolyte systems by means of CV tests for Li/AG cells. Excellent capacity and cycling performance are obtained on LiFePO 4 /AG 063048-type cells tests with blend salts electrolytes. A plateau near 1.7–2.0 V is shown in electrolytes containing LiODFB salt, and extends with increasing LiODFB concentration in charge curve of LiFePO 4 /AG cells. At 1 C discharge current rate, the initial discharge capacity of 063048-type cell with the optimum electrolyte is 376.0 mAh, and the capacity retention is 90.8% after 100 cycles at 25 °C. When at 65 °C, the capacity and capacity retention after 100 cycles are 351.3 mAh and 88.7%, respectively. The performances of LiFePO 4 /AG cells are remarkably improved by blending LiODFB and LiPF 6 salts compared to those of pure LiPF 6 -based electrolyte system, especially at elevated temperature to 65 °C.
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lithium oxalyldifluoroborate carbonate electrolytes for lifepo4 Artificial Graphite lithium ion cells
Journal of Power Sources, 2010Co-Authors: Jie Li, Zhian Zhang, Fanqun Li, Xujie ChenAbstract:Abstract The electrolytes based on lithium oxalyldifluoroborate (LiODFB) and carbonates have been systematically investigated for LiFePO 4 /Artificial Graphite (AG) cells, by ionic conductivity test and various electrochemical tests, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge test. The conductivity of nine electrolytes as a function of solvent composition and LiODFB salt concentration has been studied. The coulombic efficiency of LiFePO 4 /Li and AG/Li half cells with these electrolytes have also been compared. The results show that 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte has a relatively higher conductivity (8.25 mS cm −1 ) at 25 °C, with high coulombic efficiency, good kinetics characteristics and low interface resistance. With 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte, LiFePO 4 /AG cells exhibit excellent capacity retention ∼92% and ∼88% after 100 cycles at 25 °C and at elevated temperatures up to 65 °C, respectively; The LiFePO 4 /AG cells also have good rate capability, the discharge capacity is 324.8 mAh at 4 C, which is about 89% of the discharge capacity at 0.5 C. However, at −10 °C, the capacity is relatively lower. Compared with 1 M LiPF 6 EC/PC/DMC (1:1:3, v/v), LiFePO 4 /AG cells with 1 M LiODFB EC/PC/DMC (1:1:3, v/v) exhibited better capacity utilization at both room temperature and 65 °C. The capacity retention of the cells with LiODFB-based electrolyte was much higher than that of LiPF 6 -based electrolyte at 65 °C, while the capacity retention and the rate capacity of the cells is closed to that of LiPF 6 -based electrolyte at 25 °C. In summary, 1 M LiODFB EC/PC/DMC (1:1:3, v/v) is a promising electrolyte for LiFePO 4 /AG cells.
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Lithium oxalyldifluoroborate/carbonate electrolytes for LiFePO4/Artificial Graphite lithium-ion cells
Journal of Power Sources, 2010Co-Authors: Jie Li, Zhian Zhang, Fanqun Li, Xujie ChenAbstract:Abstract The electrolytes based on lithium oxalyldifluoroborate (LiODFB) and carbonates have been systematically investigated for LiFePO 4 /Artificial Graphite (AG) cells, by ionic conductivity test and various electrochemical tests, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge test. The conductivity of nine electrolytes as a function of solvent composition and LiODFB salt concentration has been studied. The coulombic efficiency of LiFePO 4 /Li and AG/Li half cells with these electrolytes have also been compared. The results show that 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte has a relatively higher conductivity (8.25 mS cm −1 ) at 25 °C, with high coulombic efficiency, good kinetics characteristics and low interface resistance. With 1 M LiODFB EC/PC/DMC (1:1:3, v/v) electrolyte, LiFePO 4 /AG cells exhibit excellent capacity retention ∼92% and ∼88% after 100 cycles at 25 °C and at elevated temperatures up to 65 °C, respectively; The LiFePO 4 /AG cells also have good rate capability, the discharge capacity is 324.8 mAh at 4 C, which is about 89% of the discharge capacity at 0.5 C. However, at −10 °C, the capacity is relatively lower. Compared with 1 M LiPF 6 EC/PC/DMC (1:1:3, v/v), LiFePO 4 /AG cells with 1 M LiODFB EC/PC/DMC (1:1:3, v/v) exhibited better capacity utilization at both room temperature and 65 °C. The capacity retention of the cells with LiODFB-based electrolyte was much higher than that of LiPF 6 -based electrolyte at 65 °C, while the capacity retention and the rate capacity of the cells is closed to that of LiPF 6 -based electrolyte at 25 °C. In summary, 1 M LiODFB EC/PC/DMC (1:1:3, v/v) is a promising electrolyte for LiFePO 4 /AG cells.
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tetraethylammonium tetrafluoroborate as additive to improve the performance of lifepo4 Artificial Graphite cells
Electrochemical and Solid State Letters, 2010Co-Authors: Zhian Zhang, Xinyu Wang, Jie LiAbstract:Tetraethylammonium tetrafluoroborate (TEABF 4 ) is investigated as a functional additive to 1.0 M LiPF 6 /ethylene carbonatedimethyl carbonate-ethyl methyl carbonate (1:1:1 w/w/w) electrolyte for LiFePO 4 /Artificial Graphite (AG) lithium-ion battery. TEABF 4 -containing electrolytes have lower ionic conductivity than TEABF 4 -free electrolyte, but the interface impedance of Graphite/electrolyte is reduced by adding TEABF 4 . The rate capability and cycle stability of LiFePO 4 /AG cells are improved significantly by adding a certain concentration of TEABF 4 to the electrolyte, especially 0.1 M. Therefore, TEABF 4 is a promising additive for high performance lithium-ion batteries.
