A battery cell including an electrode assembly including a plurality of electrode plates and at least one separator interposed between the plurality of electrode plates, a case configured to receive the electrode assembly, electrode tabs formed at the electrode plates so as to protrude and extend therefrom, and an electrode lead joined to the electrode tabs while being electrically connected to the outside is provided. Each of the electrode tabs includes a first tab portion connected to a corresponding one of the electrode plates and a second tab portion extending from the first tab portion, the electrode lead being joined to the second tab portion, and the first tab portion is provided with a stress relief portion configured to reduce stress in the electrode tab.