NOVELTY - A lithium-ion secondary battery has electrode element in which positive electrode (c) and negative electrode (a) are disposed facing one another, electrolyte solution, and outer package for encapsulating the electrode element and the electrolyte solution. The negative electrode is prepared by negative electrode active material (a1) in which lithium is doped into negative electrode active material (b1) containing metal alloyed with lithium, metal oxide which absorbs and releases lithium ions, and carbon material which absorbs and releases lithium ions.    USE - Lithium-ion secondary battery. Uses include but are not limited to mobile telephone, notebook personal computer, electric train, satellite, electric vehicle, hybrid car, electric motorcycle, electric power-assisted bicycle, uninterruptible power supply, submarine, etc.    ADVANTAGE - The lithium-ion secondary battery has high energy density and high-temperature cycling characteristics.    DETAILED DESCRIPTION - A lithium-ion secondary battery has electrode element in which positive electrode and negative electrode are disposed facing one another, electrolyte solution, and outer package for encapsulating the electrode element and the electrolyte solution. The negative electrode is prepared by negative electrode active material (a1) in which lithium is doped into negative electrode active material (b1) containing metal alloyed with lithium, metal oxide which absorbs and releases lithium ions, and carbon material which absorbs and releases lithium ions. The electrolyte solution contains fluorinated ether compound of formula: Ra-O-Rb (I).    Ra,Rb=alkyl or fluoro-substituted alkyl, in which at least one of Ra and Rb is fluoro-substituted alkyl.    An INDEPENDENT CLAIM is included for manufacture of lithium-ion secondary battery.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the structure of lithium-ion secondary battery.    Negative electrode (a)    Separator (b)    Positive electrode (c)    Negative electrode electrical power collector (d)    Positive electrode electrical power collector (e)