Energy storage device

An energy storage device comprising an electrolyte solution including a compound represented by the general formula (1), a compound represented by the general formula (2), and a compound represented by the general formula (3):

• wherein G represents a transition metal, or an element of Group 13, Group 14, or Group 15 of a periodic table, Aa+ represents a metal ion, a proton or an onium ion, a represents an integer of 1 to 3, b represents an integer of 1 to 3, p represents b/a, m represents an integer of 1 to 4, n represents an integer of 0 to 8, q represents 0 or 1, R1 represents an alkylene group having 1 to 10 carbon atoms, a halogenated alkylene group having 1 to 10 carbon atoms, an arylene group having 6 to 20 carbon atoms or a halogenated arylene group having 6 to 20 carbon atoms (these alkylene group and arylene group may have a substituent or a heteroatom in their structure), R2 represents halogen, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms, or E3R3 (these alkyl group and aryl group may have a substituent or a heteroatom in their structure), E1, E2 and E3 independently represent O, S or NR4, and R3 and R4 independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, or a halogenated aryl group having 6 to 20 carbon atoms (these alkyl group and aryl group may have a substituent or a heteroatom in their structure);
• wherein R5, R6, R7, and R8 independently represent hydrogen or an alkyl group having 1 to 3 carbon atoms;
• and
• wherein R9 to R12 represent independently hydrogen, fluorine, or an alkyl group having 1 to 12 carbon atoms which optionally includes fluorine, and v represents an integer of 1 to 3.