Stability of new Ag/AgCl reference electrode with NZSP ceramic membrane in low-temperature sodium ion molten salt

Abstract

The development of reference electrode with long-term service, reliable potential and good reproducibility is an important basis for molten-salt electrochemical research. In order to solve the issues, the traditional Ag/AgCl reference electrodes with glasses as membranes are difficult to realize the ionic conduction and stable liquid contact potential in low-temperature molten salt system, a new type of Ag/AgCl reference electrode with Na+ ion conductive ceramic Na3Zr2Si2PO12 (NZSP) as membrane was innovatively designed and developed, which was especially suitable for low-temperature Na+ ion molten salt system. The stability and potential reproducibility of the Ag/AgCl reference electrode were systematically studied by the electrochemical measurements. The results show that the NZSP membrane can effectively prevent the mutual diffusion between the liquid phases at both ends of the membrane. The resistance of the Ag/AgCl reference electrode is as low as 300 Ω, which shows a superior ionic transport ability. After repeated usage, the potential difference is only ±5 mV, confirming the excellent electrode stability and reusability. In general, the novel Ag/AgCl reference electrode based on NZSP ceramic membrane possesses the characteristics of stable potential, fast response and good reproducibility for long-term service in low-temperature Na+ ion molten salt system.