Secondary battery electrode

A secondary battery electrode is provided that may achieve a non-aqueous electrolyte secondary battery having a high energy output density with a small amount of a conductive aid. The secondary battery electrode has a mixture layer containing graphene and a secondary battery active substance. The secondary battery electrode has a mean aspect ratio of 2.0 or greater in an electric conductive material portion from a cross section of the secondary battery electrode, as specified by the method described below. The method for specifying the electric conductive material portion comprises: (1) acquiring, by scanning spreading resistance microscopy, a mapping image and a histogram of spreading resistance values for a mixture layer portion; and (2), defining R1 as the lowest resistance value in the histogram, accumulating sequentially from R1 the frequency, defining R2 as the spreading resistance value when the cumulative frequency has exceeded 3% relative to the cumulative frequency over the entire data, further defining R3 as a spreading resistance value of ten times R2, and, with R3 serving as the threshold value, binarizing the mapping image to define as the electric conductive material portion the portion having a resistance value of R3 or lower.