Patent ID: 8654508

Claim:
An electrochemical capacitor, comprising: an element including: a negative electrode having a collector and a negative electrode layer formed on a surface of the collector, the negative electrode layer including a carbon material occluding lithium ions; a positive electrode having a collector and a positive electrode layer formed on a surface of the collector, the positive electrode layer adsorbing ions; and a separator interposed between the negative electrode and the positive electrode; an electrolyte containing a lithium ion; and an outer case housing the element and the electrolyte, wherein a coating containing lithium carbonate is formed on a surface of the carbon material included in the negative electrode layer, and wherein, regarding an F1s spectrum and a C1s spectrum measured by X-ray photoelectron spectroscopy (XPS), the negative electrode layer is represented by that an intensity ratio A1/A2 in the F1s spectrum is 0.01≦(A1/A2)≦0.8, where A1 is an intensity showing a bonding state between fluorine and lithium and A2 is an intensity showing a bonding state between fluorine and phosphorus, and by that an intensity ratio B1/B2 in the C1s spectrum is 0.25≦(B1/B2)≦0.9, where B1 is an intensity showing a bonding state between carbon and oxygen and B2 is an intensity showing a bonding state between carbon and carbon.