Lithium ion battery

The utility model provides a lithium ion battery which comprises a battery cell, the battery cell comprises pole pieces, diaphragms and tabs, the tabs are welded on the corresponding pole pieces, the pole pieces and the diaphragms are alternately laminated, the pole pieces with opposite polarities are arranged on two sides of the diaphragms, the battery cell is prepared from the pole pieces and the diaphragms by adopting a laminated process method, the number of right-angle sides of each pole piece is more than or equal to 6, and the number of the right-angle sides of each pole piece is more than or equal to 6. An arc angle is formed at the intersection of every two adjacent right-angle sides; the number of the right-angle sides of the tab is greater than or equal to 4, and the intersection of every two adjacent right-angle sides is also an arc angle. According to the lithium ion battery, the pole pieces and the pole lugs with the arc angles are adopted, so that the lithium ion battery can adapt to electronic