| 摘要 |
<p>Provided is a lithium ion capacitor that is safe and has a high energy density and a high output. Specifically provided is a lithium ion capacitor comprising, accommodated within an outer casing: an electrode stack obtained by stacking a negative electrode in which a negative-electrode active material layer including a carbon material as the negative-electrode active material is disposed on a negative-electrode collector, a separator comprising a polyethylene-containing polyolefin resin, and a positive electrode in which a positive-electrode active material layer including a positive-electrode active material layer comprising a carbon material or a carbonaceous material is disposed on a positive-electrode collector; and a non-aqueous electrolyte solution including a a lithium ion-containing electrolyte. The lithium ion capacitor is characterized in that the thermal contraction/expansion rate of the separator falls within a prescribed range, the surface area of the separator is greater than the surface area of the positive-electrode active material layer of the positive electrode or the surface area of the negative-electrode active material layer of the negative electrode, and the length of a section where the electrode surface and the separator do not overlap has a prescribed relationship to the size of the separator.</p> |
