NONAQUEOUS ELECTROLYTE SECONDARY CELL

摘要

The present invention provides a nonaqueous electrolyte secondary cell having high capacity and energy density, and moreover improved cycle life. The nonaqueous electrolyte secondary cell is equipped with: an electrode group in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are wound or stacked; and a nonaqueous electrolyte. The positive electrode includes a positive electrode current collector, and, deposited onto the surface of the positive electrode current collector, a positive electrode active material layer of a positive electrode active material capable of occluding and releasing lithium ions. The negative electrode includes a negative electrode current collector, and, deposited onto the surface of the negative electrode current collector, a negative electrode active material layer of a negative electrode active material capable of occluding and releasing lithium ions. The negative electrode active material layer includes a film formed on the surface of the negative electrode active material, at least a portion of the film including an inorganic lithium compound. When the negative electrode active material layer is divided at a thickness ratio of 7:3 into a layer (A) nearer the negative electrode current collector and a layer (B) nearer the surface of the negative electrode active material layer, the inorganic lithium compound content included in the layer (B) is greater than the inorganic lithium compound content included in the layer (A).