Thermal power generation technologies that convert heat into electricity, such as reuse of industrial waste heat, power generation using the solar heat on the building surface, and mobile power generation using body temperature, are attracting attention.

　So far, the research group has proposed to replace the positive and negative electrode materials in lithium-ion secondary batteries with materials with high thermoelectromotive force in order to realize low-cost thermal power generation.In this research, a lithium-ion secondary battery was constructed with an ethylene carbonate / diethyl carbonate solution in which the positive electrode was a cobalt-Pulsian blue analog thin film, the negative electrode was metallic lithium, and the electrolyte was 1MLiClO4, and the temperature and electromotive force of the electrolyte were constructed. I investigated the relationship between.

　As a result, it was observed that the electromotive force changes in proportion to the temperature, and that the thermoelectromotive force changes positively and negatively by controlling the lithium concentration and the iron concentration in the cobalt-Pulsian blue analog.Since this change to positive and negative can be quantitatively reproduced by a point charge model that takes into account the coefficient of thermal expansion of the material, it can be explained that the coefficient of thermal expansion determines the magnitude of thermoelectromotive force.

　According to this research, the promising potential as a thermoelectric power generation material of the cobalt Pulchamp blue analog has been clarified, and the company aims to develop a material showing a larger thermoelectromotive force and realize a low-cost thermoelectric power generation element.

Paper information: [AIP Advance] Temperature effect on redox voltage in LixCo [Fe (CN) 6] y