NOVELTY - An electrolytic solution comprises a cyano cyclic ester carbonate; and at least one of hydrocarbyl-containing carbonic acid compounds.    USE - As electrolytic solution in secondary battery such as lithium ion secondary battery; in battery pack; in electric power storage system; in electric power tool; and in electronic devices (claimed) such as mobile phone and personal digital assistance (PDA) and electric vehicle such as electric automobile, electric power storage system such as home electric power server and electric power tool such as electric drill.    ADVANTAGE - The solution when used in electronic devices allows reduction in size and weight of electronic devices and achieves their long life. The solution provides high performance and multi-functions of the electronic devices and the like to which the secondary battery is applied. The solution allows further improvement of the battery characteristics. The secondary battery including the solution exhibits improved increased cycle retention ratio and increased conservation retention ratio.    DETAILED DESCRIPTION - An electrolytic solution comprises a cyano cyclic ester carbonate of formula (I); and at least one of compounds of formulae R4-O-C(O)-O-R5-O-C(O)-O-R6 (II), R7-C(O)-O-(R8-O)n-C(O)-R9 (III), R10-SO2-O-R11-O-SO2-R12 (IV), Li2PFO3 (V) and LiPF2O2 (VI).    R1-R3=H, halo, a cyano, a monovalent hydrocarbyl, monovalent halogenated hydrocarbyl, monovalent oxygen-containing hydrocarbyl, or monovalent halogenated oxygen-containing hydrocarbyl;    R4 and R6=monovalent hydrocarbyl, a monovalent halogenated hydrocarbyl, a monovalent oxygen-containing hydrocarbyl, or a monovalent halogenated oxygen-containing hydrocarbyl;    R5=one of a divalent hydrocarbyl, a divalent halogenated hydrocarbyl, a divalent oxygen-containing hydrocarbyl, or a divalent halogenated oxygen-containing hydrocarbyl;    R7 and R9=one of a monovalent hydrocarbyl, a monovalent halogenated hydrocarbyl, a monovalent oxygen-containing hydrocarbyl, or a monovalent halogenated oxygen-containing hydrocarbyl;    R8=one of a divalent hydrocarbyl, a divalent halogenated hydrocarbyl, a divalent oxygen-containing hydrocarbyl, or a divalent halogenated oxygen-containing hydrocarbyl;    n= greater than or equal to 1;    R10 and R12=one of a monovalent hydrocarbyl, a monovalent halogenated hydrocarbyl, a monovalent oxygen-containing hydrocarbyl, or monovalent halogenated oxygen-containing hydrocarbyl;    R11=one of a divalent hydrocarbyl, a divalent halogenated hydrocarbyl, a divalent oxygen-containing hydrocarbyl, or a divalent halogenated oxygen-containing hydrocarbyl.    At least two of the R1-R3, are allowed to be bonded to each other. INDEPENDENT CLAIMS are included for the following:    (1) a secondary battery comprising: a cathode; an anode; and the electrolytic solution;    (2) a battery pack comprising: a secondary battery; a control section controlling a usage state of the secondary battery; and a switch section switching the usage state of the secondary battery according to an instruction of the control section, where the secondary battery includes a cathode, an anode, and the electrolytic solution;    (3) an electric vehicle comprising: a secondary battery; a conversion section converting electric power supplied from the secondary battery to drive power; a drive section operating according to the drive power; and a control section controlling a usage state of the secondary battery, where the secondary battery includes a cathode, an anode, and the electrolytic solution;    (4) an electric power storage system comprising: a secondary battery; at least one or two electric devices supplied with electric power from the secondary battery; and a control section controlling the supplying of the electric power from the secondary battery to the electric device, where the secondary battery includes a cathode, an anode, and the electrolytic solution;    (5) an electric power tool comprising: a secondary battery; and a movable section being supplied with electric power from the secondary battery, where the secondary battery includes a cathode, an anode, and the electrolytic solution; and    (6) an electronic device comprising a secondary battery as an electric power supply source, where the secondary battery includes a cathode, an anode, and the electrolytic solution.