LITHIUM ION SECONDARY BATTERY NEGATIVE ELECTRODE AND LITHIUM ION SECONDARY BATTERY

摘要

Provided is a high capacity lithium ion secondary battery in which the deterioration of cycle characteristics are suppressed by reducing cracks caused by repeating charges and discharges. A lithium ion secondary battery negative electrode comprises a collector sheet and a negative electrode active material layer supported on the collector sheet. The collector sheet has protruding portions arranged along a regular pattern and a flat portion present between the protruding portions. The negative electrode active material layer includes substantially spindle-shaped columnar bodies supported by the respective protruding portions and raised bodies supported by the flat portion, both the columnar bodies and raised bodies being formed of an alloy-based negative electrode active material. In the lithium ion secondary battery negative electrode, the height of the raised bodies is lower than the height at the nearest position of the adjacent columnar bodies, and, in a vertical section taken by virtually cutting from the virtual line passing through the center portions of the adjacent two columnar bodies and the raised body sandwiched between the columnar bodies toward the surface of the collector sheet, the proportion of the section area of the raised body to the section area of a space is 25% or more on average, the space being specified by the line segment connecting the nearest positions of the adjacent two columnar bodies, the surface of the flat portion, and the side surfaces of the two columnar bodies.