LITHIUM ION CAPACITOR

摘要

A lithium ion capacitor which comprises a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator arranged between the positive electrode and the negative electrode, and an electrolyte. The positive electrode active material contains at least a material that reversibly supports anions. The negative electrode active material contains a carbonaceous material having a graphite-type crystal structure. The ratio of the capacitance (Cn) per unit projected area of the negative electrode to the capacitance (Cp) per unit projected area of the positive electrode, namely Cn/Cp is 20 or more.