In the late 1930s, a Swiss scientist Emil Baur and his colleague H. Preis started to make experiments about Solid Oxide Fuel Cells. They used several different electrolytes like zirconium, yttrium, cerium, lanthanum, and tungsten. However, they could not reach the best result because of the chosen electrolytes were not good enough to transmit the electric. In addition to that, the techniques in the process were wrong too. In the 1940s O.K Davtyon tried to improve the conductivity level by using sodium carbonate, tungsten trioxide, and soda glass. Yet, these trials could not improve electrical conductivity too. In 1962, the scientist at Westinghouse attempted to use zirconium oxide and calcium oxide, those met worked well. After that year SOFCs are started to become more popular. (, 2018)