Ultra-high ionic conductivity electrolytes for low-temperature lithium compound electrode ceramic fuel cells

Aiming at the problem that traditional solid oxide electrolytes cannot meet the needs of high-performance ceramic fuel cells due to their low ionic conductivity (10 −2 S cm −1 ) at low temperatures (<600 °C), we propose a novel design strategy for a new semi-solid electrolytes. At 550 °C, in a ceramic fuel cell using lithium compounds as electrodes, the ionic conductivity of the "MgO–Li,Na compounds" semi-solid composite electrolyte generated by the in-situ reaction of the molten lithium compounds generated by H 2 reduction lithium compound electrode with the MgO–NaFeO 2 electrolyte membrane is up to 0.7 S cm −1 , and the cell achieves a maximum power density of 780 mW cm −2 . Analysis reveals that the space charge layer at the phase interface of MgO with lithium and sodium compounds has proton conductivity, which should be the main reason for the high ionic conductivity of semi-solid composite electrolytes. This work provides a new approach for the development of high-performance ceramic fuel cells at low temperatures. • A novel design strategy for a semi-solid electrolyte by H 2 reduction. • The ionic conductivity of the semi-solid electrolyte reached 0.7 S cm −1 at 550 °C. • "MgO–Li,Na compounds" composite electrolyte can improve the durability of the cell. • Proton conduction at the interface between MgO and Li, Na compounds.