With the purpose to develop the low-cost and effective low-temperature electrochemical energy storage devices, beta alumina based ceramic and green powder ionic conductors with cationic conductivity were studied including hydrogen (proton or hydronium) conductors.
Ceramic technologies including stages of waterless homogenization, complicated heat treatments, cold isostatic pressing, and ionic modification in the sintered condition have been developed to produce the electrolytes in the shape of thin membranes from boehmite and soda as precursors. High levels of electrophysical properties adequate for sodium-sulfur storage batteries were reached. High levels of ionic conductivity in non-sintered powder compacts of the hydrogen beta alumina were demonstrated, which can be used as the basis for development of composite electrolytes suitable for mass production.
Based on experimental studies of the beta alumina cationic conductors structure and performance, two new methods of post processing the sintered membranes are proposed raising the ionic conductivity up to 0.03 S/cm at room temperature or up to 0.8 S/cm at 300°C, room electronic conductivity being negligible low.
A room direct methanol fuel cell (DMFC) based on the beta-alumina membrane was assembled and tested. It was revealed that such cell can work with higher methanol concentrations as compared with polymeric cells. Open-circuit voltage was about 0.3 V. As compared with world-famous prototypes of cells with polymeric electrolytes, the model is characterized by high efficiency attaining 75 %.
The planar model of aluminum-air battery with the ceramic separator between anode and cathode sections was assembled and tested in order for studying possible efficiency enhancement by utilizing the hydrogen liberating in the parasitic reaction. It is shown that such design enables to obtain an additional energy.
Keywords: clear energy, beta alumina, solid electrolytes, DMFC, aluminum-air battery