SECONDARY BATTERY PROVIDED WITH ELECTRODE-INTEGRATED SEPARATOR

摘要

The objective of the present invention is to increase the resistance to stress of a separator that is formed of a fine particle layer. A secondary battery according to one embodiment of the present invention comprises a separator which is formed of a resin fine particle layer (20) that is arranged on an electrode active material layer (10). The separator contains 2% by mass or more of cellulose nanofibers (22). It is preferable for the separator to contain from 2% by mass to 10% by mass (inclusive) of the cellulose nanofibers (22). The resin fine particle layer (20) is obtained by applying a suspension over the electrode active material layer (10), and the suspension contains thermoplastic resin fine particles (21) and the cellulose nanofibers (22). The cellulose nanofibers (22) are formed of fibers of an unmodified cellulose having fiber diameters of from 10 nm to 100 nm (inclusive). It is preferable that the amount of the cellulose nanofibers (22) is 2% by mass or more of the composition of the suspension excluding the dispersion medium and the cellulose nanofibers (22) are dispersed in the resin fine particle layer (20).