Non-aqueous electrolyte secondary battery

A non-aqueous electrolyte secondary battery comprising:

• an electrode element having a positive electrode, a negative electrode, and a separator;
• and
• a non-aqueous electrolyte, wherein
• the separator comprises a porous base member, and a filler layer placed over the base member, the filler layer includes phosphate particles and inorganic particles having a higher thermal endurance than the phosphate particles,
• a volume-based 10% particle size (D10) of the phosphate particles is greater than or equal to 0.02 μm and less than or equal to 0.5 μm, and is smaller than an average pore size of the base member,
• a BET specific surface area of the phosphate particles is greater than or equal to 5 m2/g and less than or equal to 100 m2/g, and is greater than a BET specific surface area of the inorganic particles, and
• a volume-based 50% particle size (D50) of the inorganic particles is greater than a volume-based 50% particle size (D50) of the phosphate particles.