Reference electrode assembly and its use in the study of fluorohydrogenate ionic liquid silicon electrochemistry

Abstract

Silicon electrochemistry in fluorohydrogenate ionic liquids is partly hampered owing to the incapability of producing an accurate and reproducible potential measurement due to a lack of appropriate reference electrodes. This research work describes a simple assembly of a stable external reference electrode enabling accurate studies of silicon electrochemistry in fluorohydrogenate ionic liquids. The electrode configuration is based on the ferrocene/ferrocenium (Fc|Fc(+)) couple dissolved in the EMIm(HF)(2.3)F (1-ethyl-3-methyl-imidazolium fluorohydrogenate)/Carbopol 941 gel. A stable potential of 2.5 wt% Carbopol-based electrode was measured versus a calomel reference electrode at 250 ± 3 mV. By utilizing the constructed electrode, an intensive electrochemical investigation on n-type silicon in EMIm(HF)(2.3)F was conducted. Flat-band and open circuit potentials were measured, along with Si-air half- and full-cell electrochemical measurements. A suggested mechanism for the n-type Si dissolution process in the EMIm(HF)(2.3)F electrolyte, without illumination, is discussed as well.

New insight into the discharge mechanism of silicon–air batteries using electrochemical impedance spectroscopy

“…More details about the reference electrode preparation procedure and testing can be found in ref. 25.…”

Analysis on discharge behavior and performance of As- and B-doped silicon anodes in non-aqueous Si–air batteries under pulsed discharge operation

“…The setup provides a geometric surface area of 0.44 cm 2 for both anode and cathode electrodes with an electrolyte volume of 0.6 ml. A three electrode setup used for the half-cell experiments was assembled by the same components with a silicon wafer or an air-electrode as working electrode, a platinum wire as counter electrode, and a self-prepared FeCp 2 /FeCp 2 + gel-based reference electrode (see [27] for further details on reference electrode). All experiments were carried out in a climate chamber (Binder KMF115) at 25 °C and 50% relative humidity.…”

A lithium iron phosphate reference electrode for ionic liquid electrolytes

“…The main advantage of such a pseudo-reference electrode is its simplicity, but its potential depends upon surface or electrolyte impurities and is therefore not well defined [4]. This leads to potential drifts over time and hampers reproducibility and comparability between different experiments [5][6][7][8]. Ferrocene can be added at the end of an experiment for calibration purposes [3,8,9], but its relative low solubility [9], moderate volatility [10] and non-innocent nature in the presence of analyte species [8] must also be considered.…”

“…To solve this problem, several groups have developed stable reference electrodes for RTILs utilizing redox couples like Ag/AgCl [11], Ag/Ag + [12][13][14], Ag/Ag2S [15] and ferrocene/ferrocenium (Fc/Fc + ) [7].…”

“…In most of these designs, the reference electrode is placed in a separate compartment which is ionically connected with the sample solution by a salt bridge (e.g. glass-fiber filter [7] or glass frit [12,13,15]).…”