US 12,074,293 B2
Secondary battery including electrode with slit along winding direction in non-formation portion
Masafumi Kadoi, Chita (JP); Takahiro Sakurai, Nagoya (JP); and Kosuke Suzuki, Toyota (JP)
Assigned to PRIME PLANET ENERGY & SOLUTIONS, INC., Tokyo (JP)
Filed by Prime Planet Energy & Solutions, Inc., Tokyo (JP)
Filed on Sep. 9, 2021, as Appl. No. 17/470,215.
Claims priority of application No. 2020-156475 (JP), filed on Sep. 17, 2020.
Prior Publication US 2022/0085417 A1, Mar. 17, 2022
Int. Cl. H01M 10/0585 (2010.01); H01M 4/13 (2010.01); H01M 4/36 (2006.01); H01M 10/0525 (2010.01); H01M 10/0587 (2010.01); H01M 50/103 (2021.01)
CPC H01M 10/0585 (2013.01) [H01M 4/13 (2013.01); H01M 4/36 (2013.01); H01M 10/0587 (2013.01); H01M 50/103 (2021.01); H01M 10/0525 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A secondary battery, comprising:
a flat wound electrode body in which an electrode sheet of a positive electrode or a negative electrode is wound about a winding axis in a predetermined winding direction;
a battery case which accommodates the wound electrode body; and
an electrode terminal which has an external terminal portion disposed outside the battery case and an internal terminal portion disposed inside the battery case, wherein
the electrode sheet has:
a current collector;
an electrode active material layer which extends in the winding direction, is formed on a surface of the current collector, and contains an electrode active material; and
a non-formation portion which extends in the winding direction and is disposed at a position adjacent to the electrode active material layer in a winding axis direction and in which the electrode active material layer is not formed on the surface of the current collector,
the wound electrode body has:
a flat portion which has two flat surfaces extending in a longitudinal direction orthogonal to the winding axis direction;
a first end portion which is provided on one side in the longitudinal direction in the flat portion and in which a rounded portion is formed; and
a second end portion which is provided on another side in the longitudinal direction in the flat portion and in which the rounded portion is formed,
a first slit is formed along the winding direction in a portion of the non-formation portion positioned at the first end portion,
a flat surface portion to which the internal terminal portion of the electrode terminal is joined is provided in a portion positioned further toward opposite than the first slit from the electrode active material layer in the portion of the non-formation portion positioned at the first end portion,
a length of the first slit along the winding direction decreases with increasing approach to the winding axis,
the flat surface portion is provided on an outer surface of the non-formation portion, the outer surface of the non-formation portion being adjacent to an outer side of the battery case, and
the length of the first slit along the winding direction is longer than another length of the first slit along the winding axis direction.