Power storage element and electric double layer capacitor
First Claim
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1. 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, whereinthe electrolytic solution includes no lithium ion, andthe graphite has a rhombohedral crystal-to-hexagonal crystal ratio (lb/la ratio) determined by X-ray diffractometry of 0.3 or more.
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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.
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Citations
10 Claims
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1. 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.
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7. 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.
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10. 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.
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