Patent ID: 8004823

Claim:
A lithium ion capacitor, comprising: a positive electrode made of a material capable of reversibly doping and dedoping lithium ions and/or anions; a negative electrode made of a material capable of reversibly doping and dedoping lithium ions; and an electrolytic solution made of an aprotonic organic solvent electrolyte solution of a lithium salt, wherein (1) lithium ions are doped in a negative electrode and/or a positive electrode due to an electrochemical contact between the negative electrode and/or positive electrode and a lithium ion supply source, (2) a positive electrode potential after the positive electrode and the negative electrode are short-circuited is 2.0 V (vs. Li/Li + ) or less, and (3) the positive electrode and/or negative electrode has a current collector made of a metal foil that has a number of holes that penetrate through both sides thereof and have an average diameter of inscribed circles of the through-holes of 100 μm or less.