Jm Energy Corporation

Kuniyasu Hiraiwa

Naoshi Yasuda

Takashi Chiba

Kazuyoshi Okada

Provided is a lithium ion capacitor that can maintain a high capacity retention rate and suppress an increase in internal resistance even after high-load charging-discharging is repeated many times and that has long service life because the occurrence of a short circuit due to precipitation of lithium on the negative electrode is prevented. The lithium ion capacitor comprises a positive electrode, a negative electrode, and an electrolyte solution, the negative electrode including a current collector and electrode layers that contain a negative electrode active material and are formed on front and back surfaces of the current collector, wherein, in the negative electrode, ratios of deviations of respective thicknesses of the electrode layers formed on the front and back surfaces of the current collector from an average of the thicknesses of the electrode layers to the average is &#x2212;10 to 10%.

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Hokuto, Japan

Kuniyasu Hiraiwa