Power storage element and electric double layer capacitor
AssigneeMasaki Yoshio
InventorsMasaki Yoshio, Hitoshi Nakamura
Life of this patent
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Abstract
To provide electric double layer capacitors which have large electrostatic capacitances. Graphite with a BET surface area of from 10 to 300 m2/g, wherein the graphite has an energy storing ability of 10 to 200 mAh at a voltage of 1 V or more based on the oxidation-reduction potential of lithium.
Claims10
An electric double layer capacitor comprising a carbonaceous positive electrode comprising graphite and a carbonaceous negative electrode, immersed in an electrolytic solution obtained by making a solute dissolved in a nonaqueous solvent, wherein
- the electrolytic solution includes no lithium ion, and
- the graphite has a rhombohedral crystal-to-hexagonal crystal ratio (lb/la ratio) determined by X-ray diffractometry of 0.3 or more.
An electric double layer capacitor, wherein at least one electrode comprises graphite of which changing rate in voltage turns smaller than a voltage changing curve based on a time constant through intake of ions in the electrolytic solution into the graphite in the course of charging at the time of charging with a constant current, and wherein charging/discharging is performed through adsorption and desorption of the ions, wherein
- the electrolytic solution includes no lithium ion, and
- the graphite has a rhombohedral crystal-to-hexagonal crystal ratio (lb/la ratio) determined by X-ray diffractometry of 0.3 or more.
An electric double layer capacitor, wherein at least one electrode is composed of an electrode made of graphite of which changing rate in voltage turns smaller than a voltage changing curve based on a time constant through intake of ions in the electrolytic solution into the graphite in the course of charging at the time of charging with a constant current, and the counter electrode comprises activated carbon, wherein
- the electrolytic solution includes no lithium ion, and
- the graphite has a rhombohedral crystal-to-hexagonal crystal ratio (lb/la ratio) determined by X-ray diffractometry of 0.3 or more.
Dependencies are inferred from the claim text.