Through targeted and reproducible electrochemical treatment of glassy carbon electrodes, investigations have been carried out on the electrochemical behaviour of the oxidation of V2＋, VO2＋ and the reductions of VO2...Through targeted and reproducible electrochemical treatment of glassy carbon electrodes, investigations have been carried out on the electrochemical behaviour of the oxidation of V2＋, VO2＋ and the reductions of VO2＋, VO2＋ and V3＋ in order to pretreat electrodes specifically for use in vanadium redox flow batter- ies and, if possible, to treat them in situ. For this purpose, a glassy carbon electrode was treated poten- tiostatically for a period of 30 s at different potentials in the range of 500 mV-2000 mV vs. Hg/Hg_2SO_4 in 2 M H_2SO_4 and then linear sweep voltammograms were performed in the different vanadium-containing solutions. With this method, it could be shown that all reactions are extremely surface sensitive and the reaction speeds changed by several decades. The reaction rates increased significantly in all reac- tions compared to polished electrodes and had an optimum treatment potential of approx. 1600 mV vs. Hg/Hg_2SO_4, although the oxidation reaction of V2＋ and the reduction reactions of V3＋ and VO2＋ had opposite tendencies to oxidation of VO2＋ and the reduction of VO2＋ in the area of low treatment po- tentials. In the former, the kinetics increased and in the latter, they decreased. In addition, causes were investigated using confocal microscopy and XPS. No correlation was found to the roughness or size of the stretched surfaces, although these changed significantly as a result of the treatment. XPS measure- ments gave indications of a dependence on hydroxyl groups for the oxidation of VO2＋ and the reduction of VO2＋, while for the reactions of oxygen-free cations and the reduction of VO2＋ weak indications of a dependence on carboxyl groups were obtained.展开更多
Several acid compounds have been employed as additives of the V(V) electrolyte for vanadium redox flow battery(VRB) to improve its stability and electrochemical activity. Stability of the V(V) electrolyte with and wit...Several acid compounds have been employed as additives of the V(V) electrolyte for vanadium redox flow battery(VRB) to improve its stability and electrochemical activity. Stability of the V(V) electrolyte with and without additives was investigated with ex-situ heating/cooling treatment at a wide temperature range of-5 ?C to 60 ?C. It was observed that methanesulfonic acid, boric acid, hydrochloric acid, trifluoroacetic acid,polyacrylic acid, oxalic acid, methacrylic acid and phosphotungstic acid could improve the stability of the V(V) electrolyte at a certain range of temperature. Their electrochemical behaviors in the V(V) electrolyte were further studied by cyclic voltammetry(CV), steady state polarization and electrochemical impedance spectroscopy(EIS). The results showed that the electrochemical activity, including the reversibility of electrode reaction, the diffusivity of V(V) species, the polarization resistance and the flexibility of charge transfer for the V(V) electrolyte with these additives were all improved compared with the pristine solution.展开更多
氢氧化镍是碱性蓄电池的正极活性物质,为了改善镍系列电池的性能,合成了掺杂α Ni(OH)2,它具有较高的放电平台,且放电曲线平坦,放电容量高,在碱性溶液中结构稳定。对它进行了电极性能研究。通过循环伏安法,结合Ran dle Sevick方程,得出...氢氧化镍是碱性蓄电池的正极活性物质,为了改善镍系列电池的性能,合成了掺杂α Ni(OH)2,它具有较高的放电平台,且放电曲线平坦,放电容量高,在碱性溶液中结构稳定。对它进行了电极性能研究。通过循环伏安法,结合Ran dle Sevick方程,得出了质子扩散系数为2.35×10-10cm2/s;通过交流阻抗法发现它由电化学极化阻抗和Warburg阻抗组成。展开更多
基金the German Federal Ministry of Education and Research (BMBF) for funding the project under the number 01DR17027
文摘Through targeted and reproducible electrochemical treatment of glassy carbon electrodes, investigations have been carried out on the electrochemical behaviour of the oxidation of V2＋, VO2＋ and the reductions of VO2＋, VO2＋ and V3＋ in order to pretreat electrodes specifically for use in vanadium redox flow batter- ies and, if possible, to treat them in situ. For this purpose, a glassy carbon electrode was treated poten- tiostatically for a period of 30 s at different potentials in the range of 500 mV-2000 mV vs. Hg/Hg_2SO_4 in 2 M H_2SO_4 and then linear sweep voltammograms were performed in the different vanadium-containing solutions. With this method, it could be shown that all reactions are extremely surface sensitive and the reaction speeds changed by several decades. The reaction rates increased significantly in all reac- tions compared to polished electrodes and had an optimum treatment potential of approx. 1600 mV vs. Hg/Hg_2SO_4, although the oxidation reaction of V2＋ and the reduction reactions of V3＋ and VO2＋ had opposite tendencies to oxidation of VO2＋ and the reduction of VO2＋ in the area of low treatment po- tentials. In the former, the kinetics increased and in the latter, they decreased. In addition, causes were investigated using confocal microscopy and XPS. No correlation was found to the roughness or size of the stretched surfaces, although these changed significantly as a result of the treatment. XPS measure- ments gave indications of a dependence on hydroxyl groups for the oxidation of VO2＋ and the reduction of VO2＋, while for the reactions of oxygen-free cations and the reduction of VO2＋ weak indications of a dependence on carboxyl groups were obtained.
基金supported by the Doctoral Program of Higher Education(No.20110181110003)the Collaborative innovation fund by China Academyof Engineering Physics and Sichuan University(No.XTCX2011001)the Sichuan Provincial Department of Science and Technology R&D Program(No.2013FZ0034)
文摘Several acid compounds have been employed as additives of the V(V) electrolyte for vanadium redox flow battery(VRB) to improve its stability and electrochemical activity. Stability of the V(V) electrolyte with and without additives was investigated with ex-situ heating/cooling treatment at a wide temperature range of-5 ?C to 60 ?C. It was observed that methanesulfonic acid, boric acid, hydrochloric acid, trifluoroacetic acid,polyacrylic acid, oxalic acid, methacrylic acid and phosphotungstic acid could improve the stability of the V(V) electrolyte at a certain range of temperature. Their electrochemical behaviors in the V(V) electrolyte were further studied by cyclic voltammetry(CV), steady state polarization and electrochemical impedance spectroscopy(EIS). The results showed that the electrochemical activity, including the reversibility of electrode reaction, the diffusivity of V(V) species, the polarization resistance and the flexibility of charge transfer for the V(V) electrolyte with these additives were all improved compared with the pristine solution.
文摘氢氧化镍是碱性蓄电池的正极活性物质,为了改善镍系列电池的性能,合成了掺杂α Ni(OH)2,它具有较高的放电平台,且放电曲线平坦,放电容量高,在碱性溶液中结构稳定。对它进行了电极性能研究。通过循环伏安法,结合Ran dle Sevick方程,得出了质子扩散系数为2.35×10-10cm2/s;通过交流阻抗法发现它由电化学极化阻抗和Warburg阻抗组成。
