Investigation of local environments in Nafion-SiO<sub>2sub> composite membranes used in vanadium redox flow batteries
- 作者：M. Vijayakumar <sup>vijay@pnnl.govsup> ; Birgit Schwenzer ; Soowhan Kim ; Zhenguo Yang ; S. Thevuthasan ; Jun Liu ; Gordon L. Graff ; Jianzhi Hu<sup> ; sup><sup>Jianzhi.Hu@pnnl.govsup>
- 关键词：Vanadium redox flow battery ; Nafion&ndash ; SiO2 membrane ; 1H and 29Si NMR and FTIR spectroscopy
- 刊名：Solid State Nuclear Magnetic Resonance
- 出版年：2012
- 期刊代码：83_09262040
- 类别：ce
- 出版时间：April, 2012
- 卷：42
- 期：Complete
- 页码：71-80
- 文件大小：639 K
摘要
Proton conducting polymer composite membranes are of technological interest in many energy devices such as fuel cells and redox flow batteries. In particular, polymer composite membranes, such as SiO<sub>2sub> incorporated Nafion membranes, are recently reported as highly promising for the use in redox flow batteries. However, there is conflicting reports regarding the performance of this type of Nafion-SiO<sub>2sub> composite membrane in the redox flow cell. This paper presents results of the analysis of the Nafion-SiO<sub>2sub> composite membrane used in a vanadium redox flow battery by nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infra Red (FTIR) spectroscopy, and ultraviolet-visible spectroscopy. The XPS study reveals the chemical identity and environment of vanadium cations accumulated at the surface. On the other hand, the <sup>19sup>F and <sup>29sup>Si NMR measurement explores the nature of the interaction between the silica particles, Nafion side chains and diffused vanadium cations. The <sup>29sup>Si NMR shows that the silica particles interact via hydrogen bonds with the sulfonic groups of Nafion and the diffused vanadium cations. Based on these spectroscopic studies, the chemical environment of the silica particles inside the Nafion membrane and their interaction with diffusing vanadium cations during flow cell operations are discussed. This study discusses the origin of performance degradation of the Nafion-SiO<sub>2sub> composite membrane materials in vanadium redox flow batteries.