FEATURES OF ZnO APPLICATION IN THE STRUCTURE OF HYDROGEN FUEL CELL

Abstract

The work is devoted to zinc oxide and the prospects of its use for the needs of hydrogen energy. The influence of zinc oxide on electrolyte materials for ceramic fuel cells is determined. The properties of ceramics based on 8YSZ were investigated by adding 0.5 wt.% nanopowder of zinc oxide according to the me­thod of the research of zinc oxide ceramics. The electrical conductivity of 8YSZ in an oxy­gen atmosphere shows a better conductivity characteristic, but 8YSZ-ZnO ceramics have better mechanical properties and higher reactivity in real fuel cell conditions.
 It was found that zinc oxide has a positive effect on the open voltage of SOFC in the temperature range from 320 °C to 600 °C. The maximum value of the open voltage for the electrolyte 8YSZ-ZnO was obtained at a temperature of 520 °C with a value of 1.02 V, in turn for the electrolyte of pure 8YSZ the maximum value was 0.92 V at a temperature of 600 °C. The small amount of data on the use of pure zinc oxide as an electrolyte opens up opportunities for thorough analysis and determination of optimal technological parameters that will accelerate the introduction of hydrogen energy technologies with operating tempe­ratures below 600 ºC. From a brief overview of existing zinc oxide-based materials in fuel cells, materials with mixed conductivity and low sintering temperatures are the most promising and effective for implementation in real systems.
 Data on the effect of sintering temperature on the porosity of ceramics with 8YSZ-ZnO and 8YSZ determined that the porosity of samples of both types decreases significantly with increasing sintering temperature of powders, but the addition of zinc oxide to 8YSZ-ZnO composite allows to obtain dense ceramics at temperatures below 100 °C than for pure 8YSZ. Regarding the strength of 8YSZ-ZnO ceramics, it increases with increasing sintering temperature and has higher values ​​relative to pure 8YSZ. Both porosity and strength change rapidly in the range of 1200–1300 °C and slowly in the range of 1300–1400 °C, due to the sintering temperature of ceramics made of pure zinc oxide 1100–1200 °C. Improving the sintering conditions of ceramics and mechanical properties reveal its advantage in the addition of zinc oxide.