Corresponding Author

Xuan CHENG(xcheng@xmu.edu.cn)


The carbon coated 10% vanadium modified lithium iron silicate (Li2Fe0.9V0.1SiO4/C) composites were prepared by sol-gel method to form precursor and followed by solid state reaction. Effects of different carboxylic acids, namely, citric acid, acetic acid and oxalic acid, on the crystal structures, surface morphologies, interfacial characteristics and electrochemical properties of the composites were systematically investigated. It was found that a mixed P21 and Pmn21 phase was formed with the major impure phase of iron (Fe) and minor impurity of lithium silicate (Li2SiO3). The initial discharge capacities of 144.7, 140.3 and 168.7 mAh•g-1 were achieved at 0.1C and room temperature, while the maximum capacities of 155.9, 145.3 and 172.0 mAh•g-1 at the 7th, 15th and 2nd cycles with the capacity retention values of 68.2%, 76.7% and 59.4% were obtained upon 50 cycles for the uses of citric acid, acetic acid and oxalic acid, respectively. Consisting of three carboxyl functional groups, the citric acid based composite contained higher amount of 7.8% residual carbon, the formation of impure Fe phase was promoted, and the larger charge-transfer resistance of 147 Ω was obtained, leading to lower coulombic efficiency and poorer cycle performance. On the contrast, the acetic acid based composite containedone carboxyl functional group only, resulted in the least amount of Fe and the smaller charge-transfer resistance of 73 Ω ,which showed the best cycle performance with the largest capacity retention. However, carrying two carboxyl functional groups the oxalic acid based composite led to 6.0% residual carbon and larger flower-like morphology, which slightly improved the lithium ion diffusion coefficient, achieving more than one lithium ion (1.05) per formula unit intercalation.

Graphical Abstract


Vanadium modification, lithium iron silicate, carboxylic acid, cathode material, lithium ion battery

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[1] Li Y S, Cheng X, Zhang Y. Achieving High Capacity by Vanadium Substitution into Li2FeSiO4 [J]. Journal of the Electrochemical Society, 2012, 159(2): A69-A74.

[2] Li Y S, Cheng X, Zhang Y. On the delithiation mechanism of Li2FeSiO4ˆ’ySy compounds: A first-principles investigation [J]. Electrochimica Acta, 2013, 112(0): 670-677.

[3] Wei X X(魏雪霞), Yang H(杨洪), Cheng X(程璇), et al. Recent progress in vanadium modified polynionic compounds as cathode materials for lithium ion batteries[J]. Journal of Xiamen University: Natural Science(厦门大学学报:自然科学版), 2015, 54(5):643-651.

[4] Zhang L L, Sun H B, Yang X L, et al. Study on electrochemical performance and mechanism of V-doped Li2FeSiO4 cathode material for Li-ion batteries[J]. Electrochimica Acta, 2015, 152(0): 496-504.

[5] Zhang Z, Liu X, Wu Y, et al. Synthesis and Characterization of Spherical Li2Fe0.5V0.5SiO4/C Composite for High-Performance Cathode Material of Lithium-Ion Secondary Batteries [J]. Journal of the Electrochemical Society, 2015, 162(4): A737-A742.

[6] Yang H(杨洪), Zhang Y(张颖), Cheng X(程璇). Effect of vanadium substitution on structure of Li2FeSiO4/C composites [J]. Journal of electrochemistry(电化学), 2013, 19(6): 565-570.

[7] Kumar A, Jayakumar O D, Naik V M, et al. Improved electrochemical properties of solvothermally synthesized Li2FeSiO4/C nanocomposites: A comparison between solvothermal and sol-gel methods [J]. Solid State Ionics, 2016, 294:15-20.

[8] Feng Y, He T, Alonso-Vante N. Oxygen reduction reaction on carbon-supported CoSe2 nanoparticles in an acidic medium[J]. Electrochimica Acta, 2009, 54(22): 5252-5256.

[9] Fu R S, Li Y S, Yang H, et al. Improved Performance of Li2FeSiO4/C Composite with Highly Rough Mesoporous Morphology [J]. Journal of the Electrochemical Society, 2013, 160(5): A3048-A3053.

[10] Zhang B, Nieuwoudt M, Easteal A J. Sol-gel route to nanocrystalline lithium metasilicate particles [J]. Journal of the American Ceramic Society, 2008, 91(6): 1927-1932.

[11] Deng C, Zhang S, Gao Y, et al. Regeneration and characterization of air-exposed Li2FeSiO4 [J]. Electrochimica Acta, 2011, 56(21): 7327-7333.

[12] Ortiz-Landeros J, Gomez-Yanez C, Pfeiffer H. Surfactant-assisted hydrothermal crystallization of nanostructured lithium metasilicate (Li2SiO3) hollow spheres: II-Textural analysis and CO2-H2O sorption evaluation [J]. Journal of Solid State Chemistry, 2011, 184(8): 2257-2262.

[13] Lee S, Cha Y C, Hwang H J, et al. The effect of pH on the physicochemical properties of silica aerogels prepared by an ambient pressure drying method [J]. Materials Letters, 2007, 61(14-15):3130-3133.

[14] Zhuang Q C(庄全超), Chen Z F(陈作锋), Dong Q F(董全峰), et al. Studies of the first lithiation of graphite materials by electrochemical impedance spectroscopy[J]. Chinese Science Bulletin(科学通报), 2006, 51(9): 1055-1059.

[15] Itagaki M, Kobari N, Yotsuda S, et al. LiCoO2 electrode/electrolyte interface of Li-ion rechargeable batteries investigated by in situ electrochemical impedance spectroscopy [J]. Journal of Power Sources, 2005,148: 78-84.

[16] Liu H, Cao Q, Fu L J, et al. Doping effects of zinc on LiFePO4 cathode material for lithium ion batteries [J]. Electrochemistry Communications, 2006, 8(10): 1553-1557.

[17] Zhang S, Deng C, Fu B, et al. Doping effects of magnesium on the electrochemical performance of Li2FeSiO4 for lithium ion batteries [J]. Journal of Electroanalytical Chemistry, 2010, 644(2): 150-154.

[18] Biesinger M C, Payne B P, Grosvenor A P, et al. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni [J]. Applied Surface Science, 2011, 257(7): 2717-2730.

[19] Biesinger M C, Lau L W M, Gerson A R, et al. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn [J]. Applied Surface Science, 2010, 257(3): 887-898.



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