US Patent 9005820 Lithium secondary battery using ionic liquid

The lithium secondary battery of the present invention is a lithium secondary battery including a positive electrode, a negative electrode, a separator provided between the positive electrode and the negative electrode, and a non-aqueous electrolyte containing a lithium salt, wherein the non-aqueous electrolyte includes, as a solvent, an ionic liquid containing a bis(fluorosulfonyl)imide anion as an anion component; and the separator is a nonwoven fabric comprising at least one member selected from an organic fiber and a glass fiber and has a porosity of 70% or more.