| 摘要 |
A lithium ion secondary battery containing a negative electrode active material containing Si and O as constituent elements and exhibiting excellent charge-discharge cycle characteristics. The lithium ion secondary battery has a positive electrode having a positive electrode material mixture layer, a negative electrode, a separator and a nonaqueous electrolyte containing at least an electrolyte salt and an organic solvent, where the negative electrode has a negative electrode material mixture layer containing a negative electrode active material containing Si and O as constituent elements (the atomic ratio x of O to Si is 0.5@x@1.5). The nonaqueous electrolyte contains the electrolyte salt at a concentration exceeding a concentration at which conductivity in the nonaqueous electrolyte containing the electrolyte salt and the organic solvent is maximized, and the conductivity at 25° C. is 6.5 to 16 mS/cm2. |
