Experimental evidence of long life lead-free oxygen galvanic sensors

In this work we present an experimental study of the lifetime of O₂ galvanic sensors in KOH aqueous solution, considering bismuth, copper and antimony as the candidates for lead anode replacement in present devices. An initial accelerated ageing test in 100% O₂ suggested antimony for the next stage. Further experiments have shown an accelerated ageing factor of 18, which allowed the estimation of a lifetime of more than five years for an O₂ galvanic sensor based on Sb anode of large surface area. A scaling law in lifetime as a function surface area (or anode current density) was found, which agreed with electrochemical passivation studies of Sb in alkaline solutions.