Positive and negative electrode plates and positive and negative electrode plate covering structure during winding for improving safety of power battery

Abstract

The invention provides positive and negative electrode plates and a positive and negative electrode plate covering structure during winding for improving safety of a power battery. Through a width design of positive and negative electrode plate covering gummed paper, blank foil exposure parts of the positive and negative electrode plates are ensured to fall into a covering gummed paper region for polarity pairing; and through a dislocated coating mode of the head of the positive electrode plate and a length design of a copper foil at the head of the negative electrode plate, roll core inner ring negative tabs are preferentially enabled to fall into a dislocated coating region of the positive electrode plate. According to the positive and negative electrode plates and the positive and negative electrode plate covering structure during the winding, under the condition that inner space design capacity of a cylinder is brought into full play, the short-circuit probability of the foil exposure parts of the positive and negative electrode plates and the safety risk caused by relatively large curvature of the inner ring negative tabs in dual-tab design of a negative electrode are lowered, high-safety design requirements of a cylindrical power battery are met, and a great practical significance is achieved.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a lifting lithium-ion cylindrical power battery positive and negative electrode sheets and a winding coating structure. Background technique [0002] With the rapid development of new energy vehicles, it is particularly important to choose an electric energy storage system that matches electric vehicles. Cylindrical lithium-ion power battery cells and their systems are widely used in the field of new energy vehicles due to their high operating voltage, high specific energy, and good economic benefits. In order to meet the demand for high-power discharge, the traditional power battery follows the design idea of ​​the consumer battery, simply moving the positive tab from the head of the pole piece to the middle of the pole piece, and changing the negative single-pole tab to a bipolar tab structure with one head and one tail. , but the safety issues in terms of gluing the pole ...

AI Technical Summary

Problems solved by technology

In order to meet the demand for high-power discharge, the traditional power battery follows the design idea of ​​the consumer battery, simply moving the positive tab from the head of the pole piece to the middle of the pole piece, and changing the negative single-pole tab to a bipolar tab structure with one head and one tail. , but the safety issues in the aspects of gluing the pole piece, the relative position of the positive and negative pole pieces during the winding process, and the bending stress buffering method of the inner circle and the negative lug are not considered comprehensively, which leads to some safety hazards in the battery

For example, during the production process of lithium-ion batteries, when the exposed aluminum foil of the positive electrode or the exposed copper foil of the negative electrode passes through the guide wheel of the equipment that adheres to foreign matter or dust particles, the foil is easily squeezed by the foreign matter under the action of tension to produce pits or damage, resulting in coil failure. If the cell short-circuit test fails or the cell is fully charged and aging, it is short-circuited or low-voltage, especially when the exposed aluminum foil and the exposed copper foil are short-circuited, it is very likely to cause the risk of thermal runaway of the cell

In addition, for a power battery with a high-power negative double-tab structure, the curvature of the negative tab of the inner ring is relatively large during the winding and bending process, and the stress generated by the tab exerts a large extrusion force on the adjacent outer ring diaphragm and positive electrode sheet , the higher the security risk

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