NOVELTY - A non-aqueous electrolyte secondary battery comprises positive electrode containing positive electrode active material, negative electrode containing negative electrode active material, and non-aqueous electrolyte which contains organic solvent with lithium salt dissolved in organic solvent and an additive. Negative electrode active material contains silicon (Si) and/or tin (Sn), oxide of metal and/or alloy containing the metal, and carbonaceous matter.    USE - A non-aqueous electrolyte secondary battery for battery pack (claimed). Uses include but not limited to power sources for smartphones and digital cameras and automotive batteries for two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, and electrically assisted bicycles.    ADVANTAGE - The expansion or contraction due to insertion or desorption of a large amount of lithium into and from the silicon phase is reduced by dispersing the silicon phase into the other 2 phases, preventing active material particles from being finely divided, and the carbonaceous matter phase ensures important conductivity as a negative electrode active material, while the silicon oxide phase binds to silicon tightly to hold the finely-divided Si, which has a significant effect in maintaining the particle structure. The formation of films which differ in composition on the silicon particle and on the carbon particle can achieve a stable charge/discharge efficiency for the cell, improving the cycle characteristics. The prevention of film cracking improves the charge-discharge efficiency and cycle characteristics of the non-aqueous secondary battery during the cycle. The non-aqueous electrolyte secondary batteries have excellent charge-discharge cycle performance, which results in a battery pack with excellent charge-discharge cycle characteristics.    DETAILED DESCRIPTION - A non-aqueous electrolyte secondary battery comprises positive electrode containing positive electrode active material, negative electrode containing negative electrode active material, and non-aqueous electrolyte which contains organic solvent with lithium salt dissolved in organic solvent and an additive. Negative electrode active material contains silicon (Si) and/or tin (Sn), oxide of metal and/or alloy containing the metal, and carbonaceous matter. Fluorine concentration of film (A) formed on metal, oxide of metal, or alloy containing the metal in negative electrode active material is higher than fluorine concentration of film (B) formed on carbonaceous matter. Additive includes greater than or equal to 1 compound containing fluorine and greater than or equal to 1 compound not containing fluorine, or electrolyte after initial charge has greater than or equal to 1 fluorine-containing additive. An INDEPENDENT CLAIM is included for battery pack comprising non-aqueous electrolyte secondary battery as a cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional diagram of a flat non-aqueous electrolyte battery.    Battery active material (100)    Electrode group (101)    Exterior component (102)    Negative terminal (106)    Positive terminal (107)