# US 7,411,777 B2 · Electrolytic solution for electric double layer capacitor and electric double layer capacitor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,411,777 B2 - Document ID: US7411777B2 - Status: Granted - Kind: B2 - Application number: 10/569,733 - Filed: 2004-07-27 - Published: 2006-12-07 - Granted: 2008-08-12 - Earliest claimed: 2003-08-29 - Assignees: The Japan Carlit Co., Ltd. - Inventors: Kazumi Chiba - Web page: https://patentgrep.com/patent/US7411777B2 ## CPC - H01G 11/58: Liquid electrolytes - H01G 11/82: Fixing or assembling a capacitive element in a housing, e.g. mounting electrodes, current collectors or terminals in containers or encapsulations - Y02E 60/13: Energy storage using capacitors - H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract An electrolytic solution for an electric double layer capacitor is provided. A spiro compound of formula (1) is provided as an electrolyte in an aprotic solvent. The electric conductivity of the solution at −40° C. is 0.85 mS/cm or higher. This electrolytic solution provides a high dissolution of electrolyte in solvent and exhibits excellent conductivity and electrostatic capacity over a wide range of temperatures Further, the electrolytic solution exhibits high resistance to voltage, even under long-term high voltage load, and exhibits suppressed lowering of electrostatic capacity allowing the solution to excel in long-term stability. ## Claims ### Claim 1 An electrolytic solution for an electrical double layer capacitor comprising a spiro compound of the formula (1) as an electrolyte dissolved in an aprotic solvent and having a conductivity of 0.85mS/cm or more at −40° C, wherein m and n individually represent a natural number from 3-7 and X- represents a tetrafluoroborate anion. ### Claim 2 (depends on 1) The electrolytic solution for electrical double layer capacitor according to claim 1, wherein the electrostatic capacity of the electrical double layer capacitor when used at −20° C. decreases by 5% or less from the electrostatic capacity when used at 20° C. ### Claim 3 (depends on 1, 2) The electrolytic solution for electrical double layer capacitor according to claim 1 or 2, wherein the spiro compound shown by the formula (1) is spiro-(1,1)-bipyrrolidinium tetrafluoroborate or piperidine-1-spiro-1′-pyrrolidinium tetrafluoroborate. ### Claim 4 (depends on 1) The electrolytic solution for electrical double layer capacitor according to claim 1, wherein the aprotic solvent is propylene carbonate and/or γ-butyrolactone. ### Claim 5 (depends on 1) The electrolytic solution for an electrical double layer capacitor according to claim 1, comprising a mixture of an electrolyte and an aprotic solvent having a saturated electrolyte concentration of 2 mol/l or more at 40° C. ### Claim 6 (depends on 1) The electrolytic solution for an electrical double layer capacitor according to claim 1, which can be stably used at −20 C. ### Claim 7 (depends on 1) The electrolytic solution for an electrical double layer capacitor according to claim 1, wherein the spiro-(1,1)-bipyrrolidinium tetrafluoroborate is dissolved in the aprotic solvent at a concentration in a range of 2-3.5 mol/l. ### Claim 8 (depends on 1) The electrolytic solution for an electrical double layer capacitor according to claim 1, wherein the piperidine-1-spiro-1′-pyrrolidinium tetrafluoroborate is dissolved in the aprotic solvent at a concentration in a range of 0.5-3 mol/l. ### Claim 9 (depends on 1) The electrolytic solution for an electrical double layer capacitor according to claim 1 for use in cold regions. ### Claim 10 (depends on 1) An electrical double layer capacitor manufactured using the electrolytic solution according to claim 1. ### Claim 11 (depends on 10) The electrical double layer capacitor according to claim 10 comprising a first container, a first electrode electrically connected to the first container, a second container, a second electrode electrically connected to the second container, and a separator separating the first electrode and the second electrode, wherein the space inside the first container and the second container is filled with the electrolytic solution and the first container and the second container are sealed with a nonconductive material which prevents electrical connection between the containers. ### Claim 12 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) The electrical double layer capacitor according to claim 10, manufactured using the electrolytic solution according to any one of claims 1-9 for use in cold regions. ### Claim 13 A method for lowering the temperature dependence of the electrostatic capacity and/or internal resistance of an electrical double layer capacitor comprising filling the inside of the electrical double layer capacitor with an electrolytic solution comprising spiro-(1,1)-bipyrrolidinium tetrafluoroborate or piperidine-1-spiro-1′-pyrrolidinium tetrafluoroborate dissolved in an aprotic solvent.