Flexibly-packaged lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries and particularly relates to a flexibly-packaged lithium ion battery, which has high energy density and excellent power performance. The flexibly-packaged lithium ion battery comprises a cell, a package bag and electrolyte, wherein the package bag is used for holding the cell and the electrolyte is filled into the package bag. The cell consists of a positive plate, a negative plate and a membrane which are wound, two ends of the positive plate are provided with an inner positive tag and an outer positive tag respectively, and the inner positive tag and the outer positive tag are connected electrically through a tag adapter terminal after being wound. Compared with the prior art, the inner positive tag and the outer positive tag at two ends of the positive plate are packaged in parallel, internal resistance of the battery can be reduced more, flow distribution can be realized during large-current battery charging, the integral thickness and the body length of the lithium ion battery cannot be affected by parallel package of the inner positive tag and the outer positive tag, and accordingly, the energy density of the lithium ion battery can be guaranteed while power performance can be improved.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, in particular to a soft-pack lithium-ion battery with high energy density and good power performance. Background technique [0002] As an environmentally friendly secondary battery, lithium-ion batteries have been widely used in portable devices such as mobile phones, cameras, and notebook computers. However, with the development of modern society, many portable devices are moving towards intelligence and multi-function. In order to ensure their sufficient use time and high current discharge capacity, the batteries equipped with them must have higher energy density and power performance. . [0003] In order to ensure the low internal resistance and high power of the battery, this type of battery is often designed with the following four schemes at this stage: [0004] One is the stacked sheet structure, that is, punching out many positive and negative electrodes with tabs, and the...

AI Technical Summary

Problems solved by technology

[0008] However, none of the above four design schemes can guarantee that the battery has both high energy density and good power performance, and all of them have design defects:

[0009] Although the laminated structure reduces the internal resistance of the battery to a large extent, it is very difficult to align the positive and negative electrodes, and the production efficiency is low, and the laminated structure needs to ensure that the area of ​​the negative electrode around the electrode is larger than the area of ​​the positive electrode, so that loss of energy density;

[0010] The winding structure in which multiple tabs are extended from the current collector on a single pole piece will bring difficulties to the winding process, especially when the winding method of automatic production is adopted, the problem of tab wrinkling often occurs, which will seriously affect the The safety of the battery, and the length space of the battery will be wasted when multiple tabs are transferred, and the energy density will be lost;

[0011] The winding structure with multiple lugs welded on a single pole piece is mainly used on steel and aluminum shell batteries. This type of battery has poor safety and is prone to explosion when an internal short circuit occurs. It is difficult to use on flexible packaging batteries, and the tabs are welded on the membrane. The area not only affects the energy density of the battery, but also brings troubles to automated production;

[0012] The parallel connection technology of multiple wound cells requires high consistency of each wound cell, and the welding efficiency is very low, which is difficult to achieve with the existing technology in the industry.

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