NOVELTY - A secondary battery comprises: a cathode; anode; and electrolytic solution. The anode includes a material including silicon and/or tin as constituent elements. The electrolytic solution includes an unsaturated cyclic ester carbonate compound.    USE - In battery pack, electric vehicle, electric power storage system, electric power tool or electronic apparatus (all claimed) e.g. mobile phone and personal digital assistant (PDA); for a machine, device, instrument, apparatus, system (collective entity of several devices), or as a driving electric power source, electric power storage source for electric power storage; mobile electronic apparatus such as a video cam-coder, digital still camera, mobile phone, notebook personal computer, cordless phone, headphone stereo, portable radio, portable television or personal digital assistant; in mobile lifestyle electric appliance such as an electric shaver; memory device such as a backup electric power source and a memory card; electric power tool such as an electric drill and an electric saw; battery pack used as an electric power source of a notebook personal computer; medical electronic apparatus such as a pacemaker and a hearing aid; electric vehicle such as an electric automobile (including a hybrid automobile); and electric power storage system such as a home battery system for storing electric power for emergency.    ADVANTAGE - The secondary battery is capable of providing superior battery characteristics in battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus.    DETAILED DESCRIPTION - A secondary battery comprises: a cathode; anode; and electrolytic solution. The anode includes a material including silicon (Si) and/or tin (Sn) as constituent elements. The electrolytic solution includes an unsaturated cyclic ester carbonate compound of formula (I).    X=divalent group in which m-number of greater than C=CR1-R2 and n-number of greater than CR3R4 are bonded in any order;    R1-R4=H, halo, monovalent hydrocarbyl group, monovalent halogenated hydrocarbyl group, monovalent oxygen-containing hydrocarbyl group, and monovalent halogenated oxygen-containing hydrocarbyl group;    m= greater than or equal to 1;    n=0.    At least two of the R1-R4 are bonded to one another. INDEPENDENT CLAIMS are included for the following:    (1) a battery pack comprising: the secondary battery; a control section controlling a used state of the secondary battery; and switch section switching the used state of the secondary battery according to an instruction of the control section;    (2) an electric vehicle comprising: the secondary battery; conversion section converting electric power supplied from the secondary battery into drive power; drive section operating according to the drive power; and control section controlling a used state of the secondary battery;    (3) an electric power storage system comprising: the secondary battery; at least one electric device supplied with electric power from the secondary battery; and control section controlling the supplying of the electric power from the secondary battery to the electric device;    (4) an electric power tool comprising: the secondary battery; and movable section being supplied with electric power from the secondary battery; and    (5) an electronic apparatus comprising the secondary battery as an electric power supply source.