US Patent 7342769 Electric double-layer capacitor

In an electrical double-layer capacitor having a pair of polarizable electrodes, a separator between the polarizable electrodes and a liquid electrolyte, the polarizable electrodes contain as a main component an activated carbon having micropores with a pore radius distribution peak as determined by the MP method within a range of 4.0×10−10 to 8.0×10−10 m, and the liquid electrolyte includes an electrolyte salt which is an ionic liquid. Such electrical double-layer capacitors have excellent low-temperature characteristics and a high electrostatic capacitance.