Polyvinyl alcohol chemical hydrogel electrode binder for direct borohydride fuel cells

A novel and cost-effective electrode binder consisting of polyvinyl alcohol (PVA) chemical hydrogel is reported for direct borohydride fuel cells (DBFCs). In this work, DBFCs have been assembled with Misch-metal-based AB₅ alloy as anode, carbon-supported palladium (Pd/C) as cathode, and PVA hydrogel membrane electrolyte (PHME) as well as Nafion-117 membrane electrolyte (NME) as separators. All the DBFCs reported here were studied using an aqueous alkaline solution of sodium borohydride as fuel and an aqueous acidified solution of hydrogen peroxide as oxidant in passive mode and under ambient conditions of temperature as well as pressure. PVA chemical hydrogel (PCH) binder-based electrodes and MEAs have been fabricated using a novel, simple, and time-effective technique. Effectiveness of PCH as electrode binder in comparison to commercial Nafion electrode binder has been evaluated by studying electrochemical performances of DBFCs employing PCH as well as Nafion as electrode binders. The DBFCs employing PCH binder-based electrodes and PHME as well as NME as electrolytes exhibited peak power density values of about 69 and 75 mW cm^-2 at corresponding current density values of about 71 and 75 mA cm^-2, respectively. PCH electrode binder is a less expensive alternative to the Nafion electrode binder, which is traditionally used in fuel cells.