| CPC H01M 10/0525 (2013.01) [H01M 4/661 (2013.01); H01M 10/0459 (2013.01); H01M 10/0583 (2013.01); H01M 50/105 (2021.01); H01M 50/178 (2021.01); H01M 50/46 (2021.01); H01M 50/534 (2021.01); H01M 50/54 (2021.01); H01M 50/548 (2021.01); H01M 50/572 (2021.01); H01M 50/574 (2021.01); H01M 50/579 (2021.01); H01M 2220/30 (2013.01)] | 4 Claims |

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1. A lithium ion secondary battery comprising:
an electrode assembly including:
a plurality of unit cells that each include a pair of electrodes having a first electrode and a second electrode with a separator interposed therebetween,
wherein the first electrode in each of the plurality of unit cells includes a first electrode parallel connection tab protruding from the first electrode, the first electrode in each of the plurality of the unit cells being connected to each other by the first electrode parallel connection tab protruding from the first electrode in each of the plurality of the unit cells,
wherein the plurality of unit cells includes a first unit cell and one or more additional unit cells, and the first electrode in the first unit cell including the first electrode parallel connection tab and an electrode lead connection tab that each protrude from the first electrode in the first unit cell, and
wherein the first electrode in the first unit cell is in an outermost region of the electrode assembly, a current collector of the second electrode in the first unit cell has a lower Young's modulus than a current collector of the first electrode in the first unit cell, and the first electrode in the first unit cell is configured to be cut by repeated external bending of the electrode assembly of less than 5,000 times and prior to the second electrode in the first unit cell and the first electrode and the second electrode in each of the one or more additional unit cells; and
a case covering the electrode assembly,
wherein the case is equipped with upper stamped portions and lower stamped portions that are repeatedly stamped to cover an outside of the electrode assembly.
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