Electrode assembly having improved safety of use by means of outermost electrode structure and current collector material, and lithium-ion secondary battery having same

Abstract

An electrode assembly according to the present disclosure includes: one or more unit cells each equipped with a pair of electrodes including a first electrode and a second electrode and having different polarities with a separator interposed therebetween; an electrode mixture coated on one or both surfaces of the pair of electrodes; and electrode tabs protruded from the respective electrodes and not coated with the electrode mixture, and the electrode tabs include an electrode parallel connection tab and an electrode lead connection tab, and any one or more of the electrode parallel connection tab and the electrode lead connection tab are formed on the electrodes, and a current collector of the first electrode among the electrodes is made of a different material from a current collector of the second electrode having the different polarity in order for the first electrode including an electrode lead connection tab to be physically cut earlier than the second electrode during bending and distortion.

Description

TECHNICAL FIELD[0001]The present disclosure relates to a technique for inducing cutting of an outermost electrode including an electrode lead connection tab before the breakage of a case included in a battery and an internal short circuit occur by using the structure of the outermost electrode and a material of a current collector and thus for securing the safety in use in order to prevent the risk of ignition or explosion caused by the breakage of the case and the internal short circuit which are mechanical problems of the battery and may occur due to bending and distortion, which is a repeated external force, in a flexible environment.BACKGROUND[0002]A secondary battery refers to a battery which can be charged and discharged, as opposed to a primary battery which cannot be charged, and has been widely used in the field of advanced electronic device fields such as cellular phone, notebook computer, camcorder, and the like. As the portable electronic devices are manufactured lighter...

AI Technical Summary

Benefits of technology

The present disclosure describes a battery structure that prevents external bending or distortion from causing damage to the battery and ensures safety. This is achieved by cutting off the outermost electrode with the electrode lead connection tab first, so the current is cut off and the function of the battery is lost. The battery includes a flexible electrode assembly with a shape and structure that allows for inducing the cutting of the outermost electrode and securing the safety of the battery. Additionally, this design improves the flexibility of the battery.

Problems solved by technology

Meanwhile, in a conventional pouch type lithium secondary battery, a case forming an outer side of the lithium secondary battery is damaged by an intentional force applied from the outside, and, thus, an electrolyte accommodated in the case leaks out and outside air flows into the case.

The leakage of the electrolyte inhibits normal operations of peripheral components such as a battery protection circuit by, for example, corroding the peripheral components.

Also, the inflow of the outside air causes big safety problems such as ignition.

Meanwhile, in a flexible environment, the case may be broken by repeated bending and distortion and a short circuit may occur due to the misalignment and deviation of internal electrodes, which may cause the risk of ignition or explosion.

The internal short circuit causes excessive current flow in proportion to a contact area between a cathode and an anode, and, thus, a lot of heat is generated.

In this case, a secondary short circuit may additionally occur, and, thus, there is the risk of ignition and explosion.

In general, all electrodes in a winding type battery or a general stacked type battery are connected to the outside, and, thus, an internal short circuit occurs when the electrodes and a separator are damaged due to an external impact.

When the internal short circuit occurs as described above, even if an internal electrode or the outermost electrode, which may be a part of an electrode assembly, is broken, there may be a problem that the capacity is reduced.

However, when the battery is continuously used during the internal short circuit, there may be a problem of safety.

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