NOVELTY - Secondary battery comprises a cathode (21), an anode (22), and an electrolytic solution, where the electrolytic solution includes an allene compound (I).    USE - The secondary battery, preferably a lithium ion secondary battery is useful in a battery pack, an electric vehicle, an electric power storage system, an electric power tool and an electronic device (claimed). The secondary battery is useful as an electric power source, as a main electric power source or an auxiliary electric power source for e.g. mobile electronic devices such as a video camcorder, a digital still camera, a mobile phone, a notebook personal computer, a cordless phone, a headphone stereo, a portable radio, a portable television, and a personal digital assistant, a backup electric power source and a memory card, an electric drill and an electric saw, a battery pack used as an electric power source of a notebook personal computer; as a medical electronic device such as a pacemaker and a hearing aid, an electric vehicle such as an electric automobile (including a hybrid automobile), and an electric power storage system such as a home battery system for storing electric power for emergency or home electric appliances such as a fridge, an air conditioner, a television, and a water heater, and electric automobile, an electric motorcycle and a hybrid automobile.    ADVANTAGE - The electrolytic solution exhibits superior battery capacity, superior cycle characteristics, superior conservation characteristics.    DETAILED DESCRIPTION - Secondary battery comprises a cathode (21), an anode (22), and an electrolytic solution, where the electrolytic solution includes an allene compound (I) having a tetravalent skeleton of formula (-C=C=C-). INDEPENDENT CLAIMS are included for:    (1) the electrolytic solution comprising the allene compound having the tetravalent skeleton;    (2) a battery pack comprising the secondary battery, a control section for controlling a usage state of the secondary battery, and a switch section for switching the usage state of the secondary battery to an instruction of the control section;    (3) an electric vehicle comprising the secondary battery, a conversion section for converting electric power supplied from the secondary battery to drive power, a drive section operating to the drive power and a control section for controlling a usage state of the secondary battery;    (4) an electric power storage system comprising the secondary battery, one, or two or more electric devices, and a control section for controlling electric power supply from the secondary battery to the electric device;    (5) an electric power tool comprising the secondary battery, and a movable section being supplied with electric power from the secondary battery; and    (6) an electronic device being supplied with electric power from the secondary battery.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of the secondary battery.    Electrode body (20)    Cathode (21)    Anode (22)    Separator (23)    Center pin. (24)