Solid-state electrochemical CO 2 sensor by coupling lithium ion conductor (Li 2CO 3-Li 3PO 4-Asl 2O 3) with oxide ion-electron mixed conductor (La 0.9Sr 0.1MnO 3)

Abstract

A solid-state electrochemical cell of the type O 2(air), PtLa 0.9Sr 0.1MnO 3 Li 2CO 3(+5 mol% Li 3PO 4 + 6 mol% Al 2O 3)/ Au, CO 2, O 2 was composed to determine CO 2 concentration, where Li 2CO 3, a lithium ion conductor, was used as an electrolyte, and the perovskite-type oxide (La 0.9Sr 0.1MnO 3) O 2 -electrode as a reference electrode. The electromotive force (EMF) of the cell was found to be proportional to the logarithm of CO 2 partial pressure in CO 2/O 2/N 2 gas mixtures at temperatures between 300 and 400 °C. The EMF responded to changes of CO 2 partial pressure within 1 min at 400 °C. The sensitivity to CO 2 of this cell was not affected by coexistence of O 2, and the EMF remained constant after the first 15 days. The mechanism for sensing CO 2 is discussed.