溶胶-凝胶法制备xLiFePO_4·yLi_3V_2(PO_4)_3/C复合正极材料及其电化学性能研究（英文）
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摘要
采用溶胶-凝胶法制备出电化学性能优异的xLiFePO_4·yLi_3V_2(PO_4)_3/C复合正极材料。研究了复合比例对材料的组成、微观结构和电化学性能的影响。结果表明,当LiFePO_4和Li_3V_2(PO_4)_3的摩尔比为7:1,所得复合材料的颗粒尺寸在40~80nm之间,颗粒表面均匀地覆盖了一层无定形碳。在0.1C倍率下的首次放电容量为129.7mAh/g,充放电效率为96.0%;在1C、2C和5C倍率下,该材料的首次放电容量分别为104.6,89.3,71.6mAh/g,30次循环后的容量保持率为99.9%、95.1%和98.6%,表现出了良好的电化学稳定性。
The xLiFePO_4·y Li_3V_2(PO_4)_3/C composite cathode materials were prepared via a sol-gel method. Influence of the proportion on the composition, microstructure and electrochemical performance of the composites were studied. Results show that the obtained composites are composed of Li Fe PO4 with olivine structure, Li_3V_2(PO_4)_3 with monoclinic structure and slight Li_(0.6)V_(1.67)O_(3.67) impurity phases. The particles of the composites are uniformly coated with an amorphous carbon layer and exhibit fine crystal sizes between 40 and 80 nm. When molar ratio of LiFePO_4 and Li_3V_2(PO_4)_3 is 7:1, the first discharge capacity of the composites reaches 129.7 m Ah/g with a charge and discharge efficiency of 96.0% at 0.1 C rate. At 1 C, 2 C and 5 C rate, the first discharge capacities are 104.6, 89.3 and 71.6 m Ah/g, respectively. After 30 cycles, the capacity retentions are 99.9%, 95.1%, 98.6%, respectively, showing a good electrochemical stability.
The xLiFePO_4·y Li_3V_2(PO_4)_3/C composite cathode materials were prepared via a sol-gel method. Influence of the proportion on the composition, microstructure and electrochemical performance of the composites were studied. Results show that the obtained composites are composed of Li Fe PO4 with olivine structure, Li_3V_2(PO_4)_3 with monoclinic structure and slight Li_(0.6)V_(1.67)O_(3.67) impurity phases. The particles of the composites are uniformly coated with an amorphous carbon layer and exhibit fine crystal sizes between 40 and 80 nm. When molar ratio of LiFePO_4 and Li_3V_2(PO_4)_3 is 7:1, the first discharge capacity of the composites reaches 129.7 m Ah/g with a charge and discharge efficiency of 96.0% at 0.1 C rate. At 1 C, 2 C and 5 C rate, the first discharge capacities are 104.6, 89.3 and 71.6 m Ah/g, respectively. After 30 cycles, the capacity retentions are 99.9%, 95.1%, 98.6%, respectively, showing a good electrochemical stability.
引文
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2 Zhu W,Huang H,Zhang W et al.Mechanics of Materials[J],2012,46:11
3 Gao Pengzhao,Wang Ling,Li Dongyun et al.Ceramics International[J],2014,40:3009
4 Wang R H,Xiao S H,Li X H et al.J Alloys Compd[J],2013,575:268
5 Huang H,Faulkner T,Barker J et al.J Power Sources[J],2009,189(1):748
6 Zhong M E,Zhou Z H,Zhou Z T.The Chinese Journal of Nonferrous Metals[J],2009,19(8):1462(in Chinese)
7 Yao J h,Wei S S,Zhang P J et al.J Alloys Compd[J],2012,532:49
8 Park S B,Park C K,Hwang J T et al.Met Mater Int[J],2011,17(5):729
9 Ziolkowska D,Korona K P,Hamankiewicz B et al.Electrochim Acta[J],2013,108:532
10 Wang L N,Li Z C,Xu H J et al.J Phys Chem C[J],2008,112,308
11 Zhang X P,Guo H J,Li X H et al.Solid State Ionics[J],2012,212:106
12 Wang Ling,Gao Pengzhao,Li Dongyun et al.Key Engineering Materials[J],2014,602-603:893
13 Wang Yuhong,Mei Rui,Yang Xiaomin.Ceram Inter[J],2014,40:8439
14 Ramana C V,Ait-Salah A,Utsunomiya S et al.Chem Mater[J],2007,19:5319
15 Guo Yong,Huang Yudai,Jia Dianzeng et al.Journal of Power Sources[J],2014,246:912
16 Wang Ling.Synthesis and Study on Electrochemical Properties of xL iF eP O4×y Li3V2(PO4)3/C Cathode Materials[D].Changsha:Hunan University,2014(in Chinese)