Unveiling the Potential of Ag2S Reference Electrode: Empowering Calcium Electrochemical Reactions

Abstract

With the escalating global energy demands, the quest for postlithium technologies, such as calcium batteries, has gained significant momentum. Nevertheless, a formidable hurdle in calcium research resides in the scarcity of suitable reference electrodes. This study introduces a silver(I) sulfide (Ag2S) reference electrode for use in calcium-ion battery research based on a silver wire coated with silver(I) sulfide crystals. Comprehensive structural characterization through Raman spectroscopy, coupled with a 48 h cyclic voltammetry electrochemical analysis, has been conducted. By utilizing three nonaqueous calcium-ion electrolytes, the standard reduction potential of Ag2S relative to the standard hydrogen electrode has been determined, along with the quantification of voltage drift over time. The Ag2S standard reduction potentials varied from −0.291 to −0.477 V vs SHE, and the drift followed a linear behavior with slopes between −0.28 and −2.45 mV/h. A side reaction between ferrocene and silver ions is also observed with voltages scanned above 0.65 V. Ag2S shows promise as a reference electrode material for future calcium-ion battery research.