Negative electrode including microcapsule and lithium ion secondary battery including the negative electrode

A lithium ion secondary battery comprising a negative electrode having a resistance that increases as a result of heat generation due to an internal short-circuit, the negative electrode including a negative electrode mixture layer that comprises:

• a negative electrode active material;
• a conductive auxiliary;
• a binder;
• a polymer particle having a softening point of from 70° C. to 150° C.;
• and
• a thermally expandable microcapsule having a volume expansion start temperature that is higher than the softening point of the polymer particle,
• wherein the negative electrode mixture layer contains each of the polymer particle and the thermally expandable microcapsule at a content necessary for increasing the resistance of the negative electrode continuously or stepwise in a case in which a temperature of the negative electrode mixture layer rises above the softening point of the polymer particle as a result of the heat generation.