Disclosed are a separator for a lithium ion secondary battery, a method for producing the same, and a secondary battery using the same. A separator structure includes a support disposed inside a secondary battery. The support includes a porous polymer matrix, cellulose nano fibers dispersed in the matrix, and inorganic additives dispersed in the matrix, wherein at least some of the inorganic additives are attached to the cellulose nano fibers and are distributed in the matrix.