A kind of prismatic lithium ion battery and manufacturing method thereof

Abstract

The invention discloses a square lithium ion battery, comprising a first pole slice, a first tab disposed on the first pole slice and a second pole slice. The square lithium ion battery is characterized in that the first pole slice and the second pole slice are rolled up to make an electrical core; the first pole slice includes a conductive foil positioned on the inner ring of the electrical core, wherein the conductive foil comprises an end portion and a linear portion; the first tab is arranged on the end portion; a first tab protective device covers the first tab; and the linear portion is provided with an auxiliary film. According to the invention, the linear portion of the conductive foil on the inner ring of the electrical core in the square battery is provided with the auxiliary film, and nonuniform distribution of the cell thickness is minimized by the thickness of the auxiliary film, so as to improve the distortion phenomenon of the cell appearance due to local expansion of the square battery during the cell charge and discharge process, reduce appearance fraction defective of the square battery, decrease cell production cost and raise product yield.

Description

technical field [0001] The invention relates to the field of battery manufacturing, in particular to a square lithium ion battery and a manufacturing method thereof. Background technique [0002] During the manufacturing process of the square battery, it is necessary to weld the positive and negative tabs with a certain thickness on the positive and negative pole pieces at the appropriate positions, so as to meet the circuit connection between the inside of the battery and the external power supply or electronic products. However, because the thickness of the tab is relatively large (50-100 μm), and the hardness of the tab is relatively large, it is easy to pierce the diaphragm in the battery due to the hardness of the tab, resulting in the danger of short circuit heating inside the battery, so it is often used PI (polyimide: polyimide) high-temperature adhesive paper covers the tabs, and these adhesive papers also have a certain thickness (30-50 μm), so that the battery pos...

AI Technical Summary

Problems solved by technology

After the battery is charged or charged and discharged for dozens of cycles, due to the continuous expansion of the internal pole pieces of the battery and the uneven distribution of the internal thickness of the battery, the battery has a local protrusion and a bad appearance, resulting in serious distortion and degeneration , resulting in the scrapping of the battery, or constant complaints from customers asking for return and exchange of goods, the appearance defect rate caused by the battery production is as high as 50%, which leads to the high production cost of the battery and the seriously low production completion rate

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