Abstract: A lithium ion capacitor includes a positive electrode, a negative electrode, and a non-protonic organic solvent electrolytic solution of a lithium salt. A positive electrode active material is a material capable of reversibly doping a lithium ion and/or an anion. A negative electrode active material is a material capable of reversibly doping a lithium ion. The lithium ion is doped in advance to either one or both of the negative electrode and the positive electrode so that a positive electrode potential after the positive electrode and the negative electrode are short-circuited is 2.0 V (relative to Li/Li+) or less when capacitance per unit weight of the positive electrode is C+(F/g), weight of the positive electrode active material is W+(g), capacitance per unit weight of negative electrode is C?(F/g), and weight of the negative electrode active material is W?(g), a value of (C?×W?)/(C+×W+) is 5 or more.

Abstract: To provide an electric storage device whose negative electrode can be doped with lithium ions in a short time and whose resistance can be lowered. An electric storage device including a unit that is obtained by alternately stacking a positive-electrode sheet 9 and a negative-electrode sheet 10 with a separator 3 interposed therebetween, the positive electrode sheet 9 including a positive-electrode active material layer 1 and a positive-electrode charge collector 4, and the negative electrode sheet 10 including a negative-electrode active material layer 2 and a negative-electrode charge collector 5, in which a foil, an etching foil, or a porous lath foil is used as the positive-electrode charge collector 4 and the negative-electrode charge collector 5, a cut is made in a coating area of the positive-electrode active material layer 1 and the negative-electrode active material layer 2, and a lithium supply source is disposed so as to be opposed to the negative electrode sheet 10 of the unit.

Abstract: A lithium ion capacitor includes 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. When the negative electrode and/or positive electrode and a lithium ion supply source are electrochemically brought into contact, lithium ions are doped in a negative electrode and/or positive electrode. A positive electrode potential after the positive electrode and negative electrode are short-circuited is 2.0 V (vs. Li/Li+) or less. The positive electrode and/or negative electrode has a current collector made of a metal foil that has many holes that penetrate through both sides and have an average diameter of inscribed circles of the through-holes of 100 ?m or less.

Abstract: A lithium ion capacitor includes 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. When the negative electrode and/or positive electrode and a lithium ion supply source are electrochemically brought into contact, lithium ions are doped in a negative electrode and/or positive electrode. A positive electrode potential after the positive electrode and negative electrode are short-circuited is 2.0 V (vs. Li/Li+) or less. The positive electrode and/or negative electrode has a current collector made of a metal foil that has many holes that penetrate through both sides and have an average diameter of inscribed circles of the through-holes of 100 ?m or less.

Abstract: A lithium ion capacitor includes a positive electrode, a negative electrode, and a non-protonic organic solvent electrolytic solution of a lithium salt. A positive electrode active material is a material capable of reversibly doping a lithium ion and/or an anion. A negative electrode active material is a material capable of reversibly doping a lithium ion. The lithium ion is doped in advance to either one or both of the negative electrode and the positive electrode so that a positive electrode potential after the positive electrode and the negative electrode are short-circuited is 2.0 V (relative to Li/Li+) or less when capacitance per unit weight of the positive electrode is C+(F/g), weight of the positive electrode active material is W+(g), capacitance per unit weight of negative electrode is C?(F/g), and weight of the negative electrode active material is W?(g), a value of (C?×W?)/(C+×W+) is 5 or more.