NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY

A separator for use in a non-aqueous electrolyte secondary battery according to the present invention comprises a porous substrate and a filler layer disposed upon the substrate. The filler layer includes phosphate particles and a reticulated polyvinylidene fluoride resin. The filler layer has a polyvinylidene fluoride resin content of 15 mass % to 40 mass %, inclusive. The D10 particle size (D) of the phosphate particles on a volume basis is 0.02 μm to 0.5 μm, inclusive, and is smaller than the average pore size of the pores in the substrate. The BET specific surface area of the phosphate particles is 5 m/g to 100 m/g, inclusive.