Another limitation of hydrogen fuel cell is its feasibility to be mass produced, efficiency in energy conversion, and cost. For these reasons, a team of scientists from University of California, Los Angeles (UCLA) developed a palm-sized, solar-cell-powered supercapacitor that both produces electricity and stores energy.
“People need fuel to run their vehicles and electricity to run their devices. Now you can make both fuel and electricity with a single device,” explains Richard Kener, senior author of the study and a professor at UCLA in chemistry, biochemistry, and materials science and engineering. The newly developed device is succinctly a hybrid of a supercapacitor, which stores energy, and a hydrogen fuel cell, which generates electricity.
Aside from the two electrodes (positive and negative terminals) of the supercapacitor part, the device has a third electrode which can either store the harvested solar energy electrically or use it chemically to split water molecules, and thus generate hydrogen. The electrodes are nanostructured in order to increase their surface area or the area that is in contact with water, and thus increasing the energy conversion or hydrogen generation efficiency. The nanostructured electrodes also allow a higher amount of energy stored in the capacitor.
Since the device is made up of nickel, iron, and cobalt – raw materials that are more abundant than commonly used precious metals such as platinum– it offers a cheaper price for a hydrogen-fuel-cell – supercapacitor hybrid. The researchers also expect that the device could lower the cost of hydrogen-powered cars, which costs more than combustion engine or electric cars. “Hydrogen is a great fuel for vehicles: It is the cleanest fuel known, it’s cheap and it puts no pollutants into the air – just water. And this could dramatically lower the cost of hydrogen cars,” said Kaner.
The supercapacitor finds its application in energy storages in computers, smartphones, hydrogen-powered cars, and power grids.