| abstract |
Providing a separator that has both a desirable air permeability capable of highly preventing internal short circuits and a high retention rate in the electrolyte solution of such air permeability, and has improved uniformity of air permeability. As a separator comprising a porous sheet and cellulose nanofibers, the porous sheet contains a binder component having an SP value of 11 to 16 (cal/cm 3) 1/2 , and the porous sheet contains cellulose nanofibers on the inside and the surface thereof. And the cellulose nanofibers are bound to a porous sheet by fusion of a binder component. |