摘要 |
A lithium-ion secondary battery includes a positive electrode, a negative electrode containing an active material, and an electrolytic solution, in which the active material includes a core portion capable of occluding and releasing lithium ions, and a covering portion arranged on at least part of a surface of the core portion, in which the covering portion contains, as constituent elements, Si, O, and at least one element M1 selected from Li, C, Mg, Al, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Ge, Zr, Mo, Ag, Sn, Ba, W, Ta, Na, and K, and the atomic ratio y (O/Si) of O to Si is 0.5≦̸y≦̸1.8.
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