The dynamic-state effects of sodium ion contamination on the solid polymer electrolyte water electrolysis

• Published in: Journal of power sources 2013-11, Vol.241, p.341-348
• Main Authors: Zhang, Linsong, Jie, Xiao, Shao, Zhi-Gang, Wang, Xunying, Yi, Baolian
• Format: Article
• Language: English
• Subjects: Anodes; Cathodes; Chemistry; Deionization; Electric potential; Electrochemistry; Electrolysis; Electrolytic cells; Exact sciences and technology; General and physical chemistry; Impurities; Poisoning; Reference electrode; Single electrode potential; Sodium ion impurity; Solid polymer electrolyte water electrolysis
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2013.04.049

Na+ is a likely intrinsic impurity in water and is a potential cation impurity in the solid polymer electrolyte water electrolysis. In this paper, the dynamic-state effect of low concentration of Na+ is studied by adding Na+ into the deionized water fed in the SPE water electrolyser. The dynamic variation of cell voltage results show that the cell performance degraded more severely in the presence of Na+ impurity by anode poisoning than by cathode poisoning. The severity and poisoning rate of the cell depend on the Na+ concentration, water flow rate and cell temperature. However, the current density does not impact the extent of the cell voltage increase. In the meantime, an external reference electrode is used to measure the anode and cathode potentials. The performance degradation is mainly ascribed to the increase in cathode overpotential by anode poisoning. EIS measurements show that the performance difference primarily comes from the kinetics loss rather than the ohmic loss. The decrease of available protons in the three phase boundaries may lead to the increase in charge transfer resistance. The electron probe microanalysis tests show that Na+ remains in CCM even recovered with deionized water, which results in only partially recovered cell performance. •The dynamic-state effect of Na+ on the SPE water electrolysis is studied.•Operation conditions significantly affect the degradation.•Anode poisoning causes more severe degradation than cathode poisoning.•The degradation is mainly attributes to the increase in cathode overpotential.•The reaction 2H2O + 2e− → H2 + 2OH− takes place at cathode.