Composite electrolyte comprising hydroxyapatite (HAp) filler and 1-butyl-3-methyl-imidazolium bis-(fluoromethane sulfonyl)imide (BMImTFSI) room temperature ionic liquid (RTIL) in poly(vinyl alcohol) (PVA) combined with Nafion matrix has been prepared. The polymer matrix was composed of PVA and Nafion providing the proton conductivity, BMImTFSI was used as both ionic source and plasticizer; HAp filler enhanced the ionic conductivity and thermal stability in this system. The electrolyte with HAp at the 20 wt.% showed the highest ionic conductivity of 1.2×10-3 S cm-1 at room temperature and 96% relative humidity.
