Patent ID: 8551652

Claim:
An electricity storage device comprising: a positive electrode; a negative electrode; and an electrolyte solution interposed between the positive electrode and the negative electrode, wherein: at least one of the positive electrode and the negative electrode includes: an electrically conductive support; and an electricity storage layer provided on the electrically conductive support, the electricity storage layer including an electricity storage material, the electricity storage material contains a copolymer compound of first units and second units, each first unit having a side chain which includes an oxidation-reduction site having a π conjugate electron cloud and being of a structure represented by general formula (1′) below, and each second unit having no oxidation-reduction reaction site as a side chain, the electricity storage material reversibly undergoes redox reaction, and in general formula (1′), X 1 to X 4 are, independently, a sulfur atom, an oxygen atom, a selenium atom, or a tellurium atom; a selected one among Ra to Rd is a bonding hand for binding to another portion which is a main chain or a side chain of the copolymer compound, and the other three of Ra to Rd are, independently, an acyclic aliphatic group, a cyclic aliphatic group, a hydrogen atom, a hydroxyl group, a cyano group, an amino group, a nitro group, a nitroso group, or an alkylthio group: the second unit includes a side chain which is a functional group having affinity with a nonaqueous solvent, the second unit includes a side chain which is at least one kind selected from the group consisting of an ester group, an ether group, a carbonyl group, a cyano group, a nitro group, a nitroxyl group, an alkyl group, a phenyl group, an alkylthio group, a sulfone group, and a sulfoxide group, the copolymer compound has a structure represented by general formula (4) below, in general formula (4), R 9 and R 10 constitute a main chain of the copolymer compound, and R 9 and R 10 are trivalent residues containing, independently: at least one selected from the group consisting of a carbon atom, an oxygen atom, a nitrogen atom, and a sulfur atom; and at least one substituent selected from the group consisting of saturated aliphatic groups and unsaturated aliphatic groups having a carbon number from 1 to 10 or at least one hydrogen atom, L 1 is an ester group, an ether group, a carbonyl group, a cyano group, a nitro group, a nitroxyl group, an alkyl group, a phenyl group, an alkylthio group, a sulfone group, or a sulfoxide group that is bound to R 9 , R 12 is a divalent residue including at least one selected from the group consisting of a substituted or unsubstituted alkylene, alkenylene, arylene, ester, amide, and ether having a carbon number from 1 to 4 that are bound to R 10 and M 1 , M 1 is general formula (1′), and is bound to R 12 via the bonding hand, and a constituent ratio m/n of a number n of first units composing the copolymer compound and a number m of second units is greater than 0 and equal to or less than 5, where n and m are integers: