A direct borohydride fuel cell based on poly(vinyl alcohol)/hydroxyapatite composite polymer electrolyte membrane

A new poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) composite polymer membrane was synthesized using a solution casting method. Alkaline direct borohydride fuel cells (DBFCs), consisting of an air cathode based on MnO2/C inks on Ni-foam, anodes based on PtRu black and Au catalysts on Ni-foam, and the PVA/HAP composite polymer membrane, were assembled and investigated for the first time. It was demonstrated that the alkaline direct borohydride fuel cell comprised of this low-cost PVA/HAP composite polymer membrane showed good electrochemical performance. As a result, the maximum power density of the alkaline DBFC based on the PtRu anode (45 mW cm−2) proved higher than that of the DBFC based on the Au anode (33 mW cm−2) in a 4 M KOH + 1 M KBH4 solution at ambient conditions. This novel PVA/HAP composite polymer electrolyte membrane with high ionic conductivity at the order of 10−2 S cm−1 has great potential for alkaline DBFC applications.