Power storage device

1. A power storage device comprising a positive electrode, a negative electrode, and an electrolyte, wherein:

at least one of said positive electrode and said negative electrode includes an organic compound as an active material having a portion contributing to an oxidation-reduction reaction,

said organic compound is crystalline in both a charged state and a discharged state,

said organic compound has conjugated π-electron cloud or a radical, and has a structure represented by general formula (3):

in the general formula (3), X 1 to X 4 are independently selected from a sulfur atom, an oxygen atom, a selenium atom, and a tellurium atom; R 1 to R 2 are independently selected from a chain aliphatic group and a cyclic aliphatic group; and the chain or cyclic aliphatic group can include at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a phosphorus atom, a boron atom, and a halogen atom,

said electrolyte comprises an organic solvent and a supporting salt dissolved in said organic solvent,

said organic solvent includes propylene carbonate, and

said organic solvent has a relative dielectric constant of 10 or more and 30 or less.

2. The power storage device in accordance with claim 1 , wherein said organic compound has a molecular weight of 10,000 or less.

3. The power storage device in accordance with claim 1 , wherein the molecular structure of said organic compound is a planar structure, and said conjugated π-electron cloud is present in the direction vertical to the plane of said planar structure.

4. The power storage device in accordance with claim 1 , wherein:

said supporting salt includes an anion and a cation, and

said anion has a three-dimensionally symmetric structure.

5. The power storage device in accordance with claim 4 , wherein said anion includes at least one selected from the group consisting of a tetrafluoroborate anion, a hexafluorophosphate anion, and a perchlorate anion.

6. The power storage device in accordance with claim 1 , wherein said supporting salt has an association constant of three of less.

7. The power storage device in accordance with claim 1 , wherein said supporting salt is at least one selected from the group consisting of lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide and lithium bis(perfluoroethylsulfonyl)imide.

8. The power storage device in accordance with claim 1 , wherein said organic solvent comprises a mixed solvent of a first solvent having a relative dielectric constant of 10 or less and a second solvent having a relative dielectric constant of 30 or more, and said second solvent includes the propylene carbonate.

9. The power storage device in accordance with claim 8 , wherein

said first solvent is at least one selected from the group consisting of chain carbonic acid esters, chain esters, and chain ethers, and

said second solvent is at least one selected from the group consisting of cyclic carbonic acid esters, cyclic esters, and cyclic ethers.

10. The power storage device in accordance with claim 1 , wherein the number of reaction electrons per one molecule of said organic compound during charging and discharging is 2.0 or less.

11. The power storage device in accordance with claim 1 , wherein in at least one of the charged state and the discharged state, said organic compound included in at least one of said positive electrode and said negative electrode is positively or negatively charged, and said organic compound charged positively or negatively forms a crystalline salt with an ion contained in said electrolyte, the ion having a polarity opposite to the polarity of said organic compound.

12. The power storage device in accordance with claim 1 , wherein said organic compound has a structure represented by general formula (20):

the number of reaction electrons per one molecule of said organic compound during charging and discharging is 1.8 to 3.7.

13. The power storage device in accordance with claim 1 , wherein said organic compound has a structure represented by general formula (16):

the number of reaction electrons per one molecule of said organic compound during charging and discharging is 1.3 to 2.6.

14. The power storage device in accordance with claim 1 , wherein:

said supporting salt includes an anion and a cation, and

the number of reaction electrons per one molecule of said organic compound during charging and discharging is 2.0 or less, provided that the number of reaction electrons is 0.5 or less when said anion is CF 3 SO 3− or CF 3 (CF 2 ) 3 SO 3− , and the number of reaction electrons is 1.2 or less when said organic solvent is polypropylene carbonate.

15. The power storage device in accordance with claim 1 , wherein the number of reaction electrons per one molecule of said organic compound during charging and discharging is 3.7 or less.

16. The power storage device in accordance with claim 1 , wherein the number of reaction electrons per one molecule of said organic compound during charging and discharging is 2.6 or less.

17. The power storage device in accordance with claim 1 , wherein the ratio of a capacity of the negative electrode to a capacity of the positive electrode is more than 30% and 90% or less.

18. The power storage device in accordance with claim 1 , wherein the ratio of a capacity of the negative electrode to a capacity of the positive electrode is 50% or more and 90% or less.