NOVELTY - The secondary battery (10) has a negative electrode compound material layer (90) containing negative electrode active materials formed on a negative electrode collector (82). The perpendicularity of the negative electrode materials is set so that the number of the negative electrode materials whose inclination with respect to the negative electrode collector is 0 to 30 degrees, per unit area of the negative electrode compound material layer, differs from the number of the negative electrode materials whose inclination with respect to the negative electrode collector is 60 to 90 degrees.    USE - Secondary battery, e.g., lithium ion battery, used as cell of assembled battery (claimed) mounted in vehicle.    ADVANTAGE - Diffusion of the electric charge carrier between positive and negative electrodes is smooth since porosity ratio of the positive electrode compound material layer and the negative electrode compound material layer is 0.74 or more, thus increase in the resistance at the time of charging/discharging is suppressed and the output performance of the secondary battery is excellent. Occlusion and discharge of an electric charge carrier is made smooth at the time of charging/discharging since more negative electrode active materials are inclining with respect to the surface of a negative electrode collector in angle of 60 to 90 degrees.    DETAILED DESCRIPTION - The secondary battery also has a positive electrode compound material layer (66) containing positive electrode active materials formed on a positive electrode collector (62). The porosity ratio of the positive electrode compound material layer and the negative electrode compound material layer is 0.74 or more. The aspect-ratio of the negative electrode active materials is two or more. The compound-material density of the negative electrode compound material layer is less than 1.5 grams per cubic centimeter.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a lithium ion battery.    Secondary battery (10)    Positive electrode collector (62)    Positive electrode compound material layer (66)    Negative electrode collector (82)    Negative electrode compound material layer (90)