Abstract: A negative electrode for a lithium ion secondary battery, which has high energy density and which can suppress a crease (form change) of a negative electrode active material layer and a negative electrode current collector caused by the expansion and contraction occurring along with the quick charging and discharging and also suppress the falloff of the negative electrode active material layer after the quick charging and discharging cycle, and a lithium ion secondary battery using the negative electrode. The negative electrode for a lithium ion secondary battery and the lithium ion secondary battery include: a negative electrode active material including 5% or more of silicon or silicon oxide; a binder that is polyacrylate whose carboxylic groups at terminals of side chains of polyacrylic acid are cross-linked with magnesium or alkaline earth metal; and a negative electrode current collector.

Abstract: An object of the present invention is to provide a negative electrode for a lithium ion secondary battery with the excellent high-temperature cycle characteristic, and a lithium ion secondary battery including the same. In the negative electrode active material for a lithium ion secondary battery according to the present invention, a surface of a negative electrode active material including silicon or silicon oxide is coated with a polymer compound, and the polymer compound includes a polyacrylic acid derivative whose carboxyl groups at ends of side chains are cross-linked with a divalent metal cation (Mg2+, Ca2+, Sr2+, Ba2+, Co2+, Ni2+, Cu2+, or Zn2+).

Abstract: A negative electrode for a lithium ion secondary battery, which has high energy density and which can suppress a crease (form change) of a negative electrode active material layer and a negative electrode current collector caused by the expansion and contraction occurring along with the quick charging and discharging and also suppress the falloff of the negative electrode active material layer after the quick charging and discharging cycle, and a lithium ion secondary battery using the negative electrode. The negative electrode for a lithium ion secondary battery and the lithium ion secondary battery include: a negative electrode active material including 5% or more of silicon or silicon oxide; a binder that is polyacrylate whose carboxylic groups at terminals of side chains of polyacrylic acid are cross-linked with magnesium or alkaline earth metal; and a negative electrode current collector.

Abstract: An object of the present invention is to provide a negative electrode for a lithium ion secondary battery with the excellent high-temperature cycle characteristic, and a lithium ion secondary battery including the same. In the negative electrode active material for a lithium ion secondary battery according to the present invention, a surface of a negative electrode active material including silicon or silicon oxide is coated with a polymer compound, and the polymer compound includes a polyacrylic acid derivative whose carboxyl groups at ends of side chains are cross-linked with a divalent metal cation (Mg2+, Ca2+, Sr2+, Ba2+, Co2+, Ni2+, Cu2+, or Zn2+).