A direct borohydride fuel cell employing a sago gel polymer electrolyte

The electrochemistry of a direct borohydride fuel cell based on a gel polymer electrolyte was studied. Sago is a type of natural polymer, was employed as the polymer host for the electrolyte. An electrolyte with a composition of sago + 6 M KOH + 2 M NaBH4 was prepared and evaluated as a novel gel polymer electrolyte for a direct borohydride fuel cell system because it exhibited a high electrical conductivity of 0.270 S cm−1. The rate at which oxygen was consumed at the cathode can be related to the electric current by comparing the calculated number of electrons reacted per molecule of oxygen for different currents supplied to the fuel cell. From the oxygen consumption data, it was deduced that four electrons reacted per molecule of oxygen. The performance of the fuel cell was measured in terms of its current–voltage, discharge and open circuit voltage measurements. The maximum power density obtained was 8.818 mW cm−2 at a discharge performance of ∼230 mA h and nominal voltage of 0.806 V. The open circuit voltage of the cells was about 0.900 V and sustained for 23 h.