Electrolyte, electrochemical device, secondary cell, and module

An electrolyte solution comprising a fluorine-containing acyclic carbonate represented by the formula (1), a fluorine-containing maleic anhydride represented by the formula (2), and an electrolyte salt,

• the electrolyte solution containing not less than 0.001 mass % but less than 90 vol % of the fluorine-containing acyclic carbonate,
• the electrolyte solution containing 0.001 to 20 mass % of the fluorine-containing maleic anhydride, the formula (1) being:
• Rf1OCOORf2 (1)
• wherein Rf1 and Rf2 are the same as or different from each other and individually represent a C1-C4 alkyl group or a C1-C4 fluorine-containing alkyl group, but at least one of Rf1 and Rf2 is C1-C4 fluorine-containing alkyl group, the formula (2) being:
• wherein Rf3 and Rf4 are the same as or different from each other and individually represent a hydrogen atom, a fluorine atom, or a C1-C10 fluorine-containing alkyl group, but both of Rf3 and Rf4 are not hydrogen atoms.