Lithium ion secondary battery and negative pole piece thereof

Abstract

The invention provides a lithium ion secondary battery and a negative pole piece thereof. The negative pole piece of the lithium ion secondary battery comprises a negative pole current collector, a negative pole active material layer and a gas generating coating, wherein the negative pole active material layer is formed on the negative pole current collector; and the gas generating coating is formed on the negative pole active material layer. The lithium ion secondary battery comprises a positive pole piece, the negative pole piece, an isolating membrane and electrolyte, wherein the isolating membrane is arranged between the positive pole piece and the negative pole piece which are adjacent to each other. When the lithium ion secondary battery is in improper use, such as acupuncture (comprising burr piercing) and extrusion, gas generated by the gas generating coating can isolate the positive pole piece from the negative pole piece well, so that fire and even explosion caused by internal short circuit of the lithium ion secondary battery are effectively avoided; and when the lithium ion secondary battery is overcharged, the gas generated by the gas generating coating can isolate the positive pole piece from the negative pole piece well and can isolate a lithium ion conveying channel in the lithium ion battery, so that fire and even explosion caused by the lithium ion secondary battery are effectively avoided.

Description

technical field [0001] The invention relates to a secondary battery, in particular to a lithium ion secondary battery and its negative pole piece. Background technique [0002] With the development of science and technology, lithium-ion secondary batteries, which have the advantages of high energy, high reliability, and good processing performance, are gradually being favored. As green and environmentally friendly batteries, they are widely used in various portable electronic devices. [0003] When the lithium-ion secondary battery is charging, Li + Deintercalation from the positive electrode, embedded in the negative electrode through the electrolyte and diaphragm, the negative electrode is in a lithium-rich state, the positive electrode is in a lithium-poor state, and the electronic compensation charge is supplied from the external circuit to the negative electrode to ensure the charge balance of the negative electrode; when the lithium-ion secondary battery is discharged ...

AI Technical Summary

Problems solved by technology

[0007] However, in the normal use of lithium-ion secondary batteries in the prior art, it is difficult for lithium-ion secondary batteries to avoid collisions with sharp objects (such as tweezers, scissors, and edges and corners of hard objects). In extreme cases, sharp objects sometimes It will pierce the shell of the lithium-ion secondary battery and penetrate the insulating diaphragm between the positive and negative pole pieces, causing the aluminum foil to contact with the negative active material layer and cause a short circuit, thus causing the flammable organic electrolyte to catch fire , and even cause the battery to explode; in addition, when the lithium-ion secondary battery is squeezed and improperly used, it may cause the positive and negative pole pieces to deform and penetrate the separator to contact, resulting in the positive and negative pole pieces being phased out. A short circuit occurs due to contact, which causes the flammable organic electrolyte to catch fire, and even causes the battery to explode; in addition, during the normal charging process, the charger or the charging circuit has a certain probability of failure, resulting in the battery being overcharged, and the positive electrode Oxidation reaction occurs between the material and the organic electrolyte, and a large amount of heat release causes the battery to catch fire, which affects the safety performance of the lithium-ion secondary battery

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