NOVELTY - A secondary battery comprises an electrolyte solution provided with a positive electrode and a negative electrode, where the negative electrode contains an active material that is capable of occlude and discharge lithium. The active material contains lithium titanium containing oxides.    USE - Secondary battery for use in a battery pack that is utilized in an electric vehicle, electric power storage system, electric tool and an electronic device (all claimed) such as video camera, digital still camera, mobile telephone, notebook computer, cordless telephone apparatus, headphone stereo cassette tape recorder, portable radio, portable TV, portable information terminal, portable lifestyle instrument such as electric shaver, backup power supply, memory card, electrically-driven drill, electrically-driven saw, notebook computer, medical electronic devices such as pacemaker and hearing aid, hybrid vehicle and domestic-use battery system.    ADVANTAGE - The secondary battery reduces operating voltage.    DETAILED DESCRIPTION - A secondary battery comprises an electrolyte solution provided with a positive electrode and a negative electrode, where the negative electrode contains an active material that is capable of occlude and discharge lithium. The active material contains lithium titanium containing oxides (Li2+n1Na2-x1kx1Ti6O14, Li2+n2Na2-x2-y2kx2Rby2Ti6O14 and Li2+n3Na2-x3-y3-z3kx3Rby3Csz3Ti6O14), where n1, n2, n3 is 0-2, x1, x2 is greater than 0 but less than or equal to 1.2, y2 is greater than 0 but less than or equal to 0.5, y3, z3 is greater than 0 but less than or equal to 0.05, 5x2+12y2 is greater than 0 but less than or equal to 6 and y3+z3 is greater than 0 but less than or equal to 0.05. INDEPENDENT CLAIMS are also included for the following:    (1) a battery pack    (2) an electric vehicle    (3) an electric power storage system    (4) an electric tool.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a cylindrical shape secondary battery. '(Drawing includes non-English language text)'    Battery can (11)    Winding electrode body (20)    Positive electrode (21)    Negative electrode (22)    Separator (23,35)