Abstract: A lithium ion capacitor having high energy density, high output density, high capacity and high safety includes a positive electrode made of a material capable of being reversibly doped with lithium ions and/or anions, a negative electrode made of a material capable of being reversively doped with lithium ions, and an aprotic organic solution of a lithium salt as an electrolytic solution. Wherein, the positive electrode and the negative electrode are laminated or wound with a separator interposed between them, the area of the positive electrode is smaller than the area of the negative electrode. The face of the positive electrode is substantially covered by the face of the negative electrode when they are laminated or wound.

Abstract: A lithium ion capacitor having a high capacity retention at the time of continuous charge at a high temperature and excellent durability. The lithium ion capacitor includes a positive electrode, a negative electrode and an aprotic organic solvent electrolyte solution of a lithium salt as an electrolytic solution. The positive electrode active material is a material capable of reversibly supporting lithium ions and/or anions, a negative electrode active material is a material capable of reversibly supporting lithium ions, the negative electrode and/or the positive electrode is doped with lithium ions so that the potential of the positive electrode is at most 2.0 V after the positive electrode and the negative electrode are short-circuited, and the electrolytic solution contains vinylene carbonate or its derivative.

Abstract: It is to provide a lithium ion capacitor having a high capacity retention at the time of continuous charge at a high temperature and excellent in durability. A lithium ion capacitor comprising a positive electrode, a negative electrode and an aprotic organic solvent electrolyte solution of a lithium salt as an electrolytic solution, characterized in that a positive electrode active material is a material capable of reversibly supporting lithium ions and/or anions, a negative electrode active material is a material capable of reversibly supporting lithium ions, the negative electrode and/or the positive electrode is doped with lithium ions so that the potential of the positive electrode is at most 2.0 V after the positive electrode and the negative electrode are short-circuited, and the electrolytic solution contains vinylene carbonate or its derivative.

Abstract: A lithium ion capacitor having high energy density, high output density, high capacity and high safety is provided. A lithium ion capacitor comprising a positive electrode 1 made of a material capable of being reversibly doped with lithium ions and/or anions, a negative electrode 2 made of a material capable of being reversively doped with lithium ions, and an aprotic organic solution of a lithium salt as an electrolytic solution, wherein the positive electrode 1 and the negative electrode 2 are laminated or wound with a separator interposed between them, the area of the positive electrode 1 is smaller than the area of the negative electrode 2, and the face of the positive electrode 1 is substantially covered by the face of the negative electrode 2 when they are laminated or wound.