Patent ID: 8003253

Claim:
A non-aqueous electrolyte secondary battery comprising: a positive electrode capable of electrochemically absorbing and desorbing Li; a negative electrode; and a non-aqueous electrolyte, wherein said negative electrode comprises an oxide being represented by the formula SiO x where 0<x<2 and having a SiO 2 layer on a surface thereof, as a negative electrode active material and has a vapor-deposited Li film formed on a surface thereof before battery assembling to add Li in an amount corresponding to the irreversible capacity, the thickness of said vapor-deposited Li film being 8 to 12 μm, said non-aqueous electrolyte comprises lithium hexafluorophosphate as a main supporting electrolyte and has an acid content of not less than 50 ppm and not more than 200 ppm, and said negative electrode has a potential of not less than 0.6 V and not more than 1.5 V relative to a Li electrode at an end-of-discharge voltage of said battery.