Nonaqueous electrolyte secondary battery and battery module
A nonaqueous electrolyte secondary battery includes an electrode body and a nonaqueous electrolyte solution. An electrolyte solution passage is a flow passage through which the nonaqueous electrolyte solution flows between the inside and the outside of the electrode body. A region of a negative-electrode composite material layer in contact with the electrolyte solution passage is a damming portion and a region located on the center side relative to the damming portion is a liquid retaining portion. The damming portion contains a negative electrode active material of which an electrical potential relative to a positive electrode active material is high and a ratio of expansion or contraction due to an increase or decrease in SOC is high, when compared to a negative electrode active material contained in the liquid retaining portion. The electrolyte solution passage can be closed by the damming portion in a charge state where the damming portion expands.
1. A method of preparing a nonaqueous electrolyte secondary battery comprising:
forming a positive electrode by coating a surface of a band-shaped positive-electrode current collecting foil with a positive-electrode composite material layer that contains a positive electrode active material,
forming a negative electrode by coating a surface of a band-shaped negative-electrode current collecting foil with a negative-electrode composite material layer that contains a negative electrode active material,
forming a nonaqueous electrolyte solution by dissolving a supporting electrolyte in a nonaqueous solvent,
forming an electrode body by overlaying the positive electrode, the negative electrode, and a separator on each other,
wherein the electrode body includes an electrolyte solution passage that is a flow passage through which the nonaqueous electrolyte solution flows between an inside and an outside of the electrode body, so that the nonaqueous electrolyte solution infiltrates into the electrode body, and
a region of the negative-electrode composite material layer that is in contact with the electrolyte solution passage is referred to as a damming portion, and a region of the negative-electrode composite material layer that is located on a center side relative to the damming portion is referred to as a liquid retaining portion,
wherein the damming portion contains a negative electrode active material of which an electrical potential relative to the positive electrode active material is high and a ratio of expansion or contraction due to an increase or decrease in SOC is high, when compared to a negative electrode active material contained in the liquid retaining portion.
2. The method according to claim 1 , wherein
the positive-electrode composite material layer contains a positive electrode active material that contains lithium (Li).
3. The method according to claim 2 , wherein
the liquid retaining portion contains a carbon-based active material that contains carbon (C).
4. The method according to claim 3 , wherein
the damming portion contains a negative electrode active material that has an electrical potential of at least 0.1 V relative to lithium.
5. The method according to claim 3 , wherein
the damming portion contains a negative electrode active material of which the ratio of expansion or contraction due to an increase or decrease in SOC is at least 150%.
6. The method according to claim 3 , wherein
the damming portion contains a metal-based active material that contains at least one element selected from the group consisting of silicon (Si), tin (Sn), antimony (Sb), and bismuth (Bi).
7. The method according to claim 6 , wherein
the damming portion contains a negative electrode active material that is obtained by mixing a carbon-based active material containing carbon (C) and the metal-based active material.
8. The method according to claim 7 , wherein
an amount of the metal-based active material relative to a total amount of the negative electrode active material contained in the damming portion is at least 0.5 wt % and no greater than 3.0 wt %.
9. The method according to claim 1 , wherein
the electrode body is a wound electrode body that is obtained by layering and winding the positive electrode, the negative electrode, and the separator, and includes the electrolyte solution passage in each of both side surfaces in a winding axis direction, and
the damming portion is formed in each of both end portions of the negative-electrode composite material layer in the winding axis direction.