Energy efficiency of platinum-free alkaline direct formate fuel cells

•Alkaline Platinum-free formate fuel cells top 42% efficiency @ 60°C.•Palladium efficiently oxidizes formate.•Power density exceeding 250mWcm−2 @ 60°C has been achieved.•Performance exceeds that of Alkaline Direct Alcohol Fuel Cell. We report the energy performance of a new platinum-free alkaline direct formate fuel cell, equipped with a commercial anion exchange membrane, a nanostructured Pd/C anode and a Fe–Co/C cathode. The cell was investigated both at room temperature and at 60°C for the determination of the following parameters: (i) maximum power density, (ii) delivered energy, (iii) faradic (fuel conversion) and energy efficiency. These parameters show a dramatic dependence on fuel composition. The highest energy efficiency is obtained using high energy density fuel (4M KCOOH and 4M KOH) and with a maximum operating temperature of 60°C. This represents a key step in the progress of alkaline platinum-free DFFC technology, demonstrating their potential as power sources for portable electronic devices and remote power generation systems. For example, a fuel load of 750ml in a DFFC device operating at 60°C would be able to produce 90Wh of energy, that required to fully charge the battery of a laptop computer.