Electrolyte membrane, fuel cell including same, battery module including fuel cell, and method for manufacturing electrolyte membrane

An electrolyte membrane which comprises a lanthanum-gallium-based composite metal oxide, and has a color region of 0.39≤x≤0.40 and 0.35≤y≤0.36 based on the CIE (Commission Internationale de l'Eclairage) x, y chromaticity distribution table,

• wherein the electrolyte membrane manufactured by a method comprising:
• preparing a mixture comprising a precursor of a lanthanum-gallium-based composite metal oxide comprising evaporating moisture and heating to induce a combustion reaction;
• warming the mixture to a temperature of 800° C. or more and less than 950° C., thereby synthesizing the precursor in the mixture into lanthanum-gallium-based composite metal oxide particles;
• and
• forming the electrolyte membrane by using a slurry comprising the lanthanum-gallium-based composite metal oxide particles,
• the synthesized composite metal oxide particles comprise lanthanum-gallium-based composite metal oxide particles which are represented by the following Chemical Formula 1, and secondary phase particles,
• a content of the secondary phase particles is 5 wt % or more and 30 wt % or less based on the total weight of the synthesized composite metal oxide particles,
• wherein the lanthanum-gallium-based composite metal oxide of the electrolyte membrane is represented by the following Chemical Formula 1:
• La1-xQxGa1-yZyO3-δ [Chemical Formula 1]
• in Chemical Formula 1,
• Q is strontium, Z is magnesium, and 0<x<0.25, 0<y<0.25, and 0<δ<0.5.