全钒液流电池用碳纸电极掺氮改性的研究

doi:10.15541/jim20140656

摘要/Abstract

摘要：

采用在氨气氛下加热(NCP-600: 600℃下处理, NCP-900: 900℃下处理)对全钒液流电池碳纸电极进行掺氮改性处理。通过此改性处理, 含氮官能团成功地引入到碳纸表面。掺氮处理改善了碳纸表面的亲水性, NCP-900的接触角相比于空白碳纸由120.5°降到99.7°, 且对表面形貌没有明显影响, 不会影响其机械性能。同时, 掺氮处理能明显地增强碳纸的电化学活性, 循环伏安测试中, NCP-900的V(IV)/V(V)电对氧化峰为92.1 mA, 远高于空白碳纸(68.9 mA)。由NCP-900和空白碳纸组装成电池考察了其充放电性能, 在20 mA/cm²下进行充放电, 由NCP-900组装的电池其能量效率为83.73%, 较空白电池高2.59%。掺氮改性处理提高碳纸的电化学性能主要是由于钒电对活性位点的增加和亲水性能的增强。

关键词: 全钒液流电池, 掺氮, 碳纸, 动力学

Abstract:

To improve the electrochemical activity of carbon paper (CP) for vanadium redox flow batteries, CP was modified by heat treatment in atmosphere of NH₃ at 600 (NCP-600) and 900℃ (NCP-900), respectively. The FTIR results indicate that the nitrogenous groups have been introduced on the surface of CP by modification successfully. Compared with the pristine sample, the water contact angle of NCP-900 decreases from 120.5° to 99.7°, indicating the improved hydrophilicity of CP by nitrogen doping. The SEM results show that there is no obvious morphology change on the surface of CP after nitrogen doping, which do not affect the mechanical property. The electrochemical activity of CP is enhanced significantly by nitrogen doping. The oxidation current peak of V(Ⅳ)/V(Ⅴ) couple on NCP-900 is 92.1 mA, much higher than that of pristine sample (68.9 mA). The cells with NCP-900 and pristine sample as electrodes were assembled and the charge-discharge performance was evaluated. The energy efficiency of cell with NCP-900 as electrode at a current density of 20 mA/cm² is 83.73%, 2.59% larger than that with the pristine sample. The improved electrochemical performance of nitrogen-doped carbon paper is due to the increased active sites and the enhanced hydrophilicity provided by the introduced nitrogenous groups.

Key words: vanadium redox flow batteries, nitrogen doping, carbon paper, kinetics

中图分类号:

TQ174

何章兴, 刘剑蕾, 何震, 刘素琴. 全钒液流电池用碳纸电极掺氮改性的研究[J]. 无机材料学报, 2015, 30(7): 779-784.

HE Zhang-Xing, LIU Jian-Lei, HE Zhen, LIU Su-Qin. Nitrogen-doped Carbon Paper as Electrodes for Vanadium Redox Flow Batteries[J]. Journal of Inorganic Materials, 2015, 30(7): 779-784.

图/表 7

Fig. 1 Surface morphologies of different carbon paper (a) CP; (b) NCP-600; (c) NCP-900

Fig. 2 FTIR spectra of different carbon paper (a) CP; (b) NCP-600; (c) NCP-900

Fig. 3 Cross-sectional views of water droplets on different carbon paper (a) CP; (b) NCP-600; (c) NCP-900

Fig. 4 Cyclic voltammograms of 1.0 mol/L V(IV) in 3.0 mol/L H2SO4 solution with different carbon paper as working electrode

Table 1 Relevant data obtained from cyclic voltammetry for 1.0 mol/L V(IV) solution with different carbon paper

Sample	Anodic peak, I_pc/mA	Cathodic peak, I_pc/mA	Peak potential interval, ΔE_p/mV	I_pa/I_pc
CP	68.9	43.1	329	0.626
NCP-600	83.8	55.3	290	0.660
NCP-900	92.1	62.4	297	0.678

Fig. 5 The 10th charge-discharge curves of the cells employing different carbon papers as electrodes at a current density of 20 mA/cm2

Fig. 6 Efficiencies of cells employing CP and NCP-900 as electrodes at a current density of 20 mA/cm2

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