Patent ID: 7736808

Claim:
A non-aqueous electrolyte secondary battery including: a positive electrode including a positive electrode material mixture; a negative electrode including a negative electrode material mixture; and a non-aqueous electrolyte including a non-aqueous solvent, and a first lithium salt and a second lithium salt dissolved in said non-aqueous solvent, wherein said negative electrode material mixture includes a material capable of absorbing and desorbing lithium ions, and carbon nanofibers, said material capable of absorbing and desorbing lithium ions has a ratio A/B of a volume A in a charged state to a volume B in a discharged state of 1.2 or more, said first lithium salt is at least one selected from the group consisting of LiBF 4 and LiB(C 2 O 4 ) 2 , said second lithium salt is a salt other than said first lithium salt, said first lithium salt is included in said non-aqueous electrolyte at a weight ratio of 10 −4 or more relative to said carbon nanofibers, and said first lithium salt included in said non-aqueous electrolyte has a concentration of 0.05 mol/dm 3 or less.