Electrochemical energy conversion is a field of energy technology concerned with electrochemical methods of energy conversion including fuel cells and photoelectrochemical. This field of technology also includes electrical storage devices like batteries and supercapacitors. It is increasingly important in context of automotive propulsion systems. There has been the creation of more powerful, longer running batteries allowing longer run times for electric vehicles. These systems would include the energy conversion fuel cells and photoelectrochemical mentioned above.