Dense Electrode Layers-Supported Microtubular Oxygen Pump

An oxygen pump is an electrochemical device that extracts oxygen from the air and has the potential to be used in medicine. The development and test results of a microtubular solid oxide oxygen pump with Ce_0.76Gd_0.24O_2-δ (GDC) electrolyte are presented. The supporting components of the oxygen pump are symmetrical dense electrode layers made of the La_0.8Sr_0.2Co_0.2Fe_0.8O_3-δ (LSCF)-GDC composite. Studies carried out by impedance spectroscopy on planar samples showed that the polarization resistance of the dense electrodes was greatly lower (by 2.5-5 times) than that of standard porous LSCF electrodes. Microtubular oxygen pumps were fabricated by the isostatic pressing of a stack of tapes rolled into a tube and subsequent co-sintering. The use of a nanosized GDC powder as the initial material for the tapes allowed their co-sintering at 1200 °C. In such a way, the chemical interaction between GDC and LSCF was prevented. Samples of the prepared cells had an outer diameter of 1.9 and 3.5 mm, and the thickness of the electrolyte and of the dense supporting electrodes was 20 and 130 µm, respectively. The specific oxygen productivity of the cells was 0.29 L∙h^-1∙cm^-2 at 800 °C and a current density of 1.26 A·cm^-2 (0.53 V). Thus, the energy consumption with the developed design for the production of 1 L of oxygen was 2.3 W∙h. The microtubular oxygen pumps appeared highly resistant to thermal shock.