Safety coating, positive pole piece and application

Abstract

The invention provides a safety coating, a positive pole piece and application. The safety coating comprises 5-25 parts of a lithium salt, 1-20 parts of a pore forming agent, 25-75 parts of a binder and 5-25 parts of a conductive agent. The lithium salt is added into the safety coating, so that the number of movable lithium ions in the safety coating is increased, the ionic conductivity of the safety coating is improved, the impedance of the safety coating in a normal-temperature state is reduced, and the rate capability of the battery can be improved; meanwhile, a pore-forming agent is added into the safety coating to construct a porous structure, the wettability of an electrolyte is improved, and when the temperature rises, the volume of a binder expands, the distance between conductive agent particles is increased, and the porous structure is filled, so that the resistance of the safety coating is increased, and the effect of protecting the lithium ion battery is achieved.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and relates to a safety coating, in particular to a safety coating, a positive pole piece and an application thereof. Background technique [0002] Lithium-ion batteries have been widely used in various electronic products and automobiles. However, when lithium-ion batteries are subjected to abnormal conditions such as high temperature, extrusion, collision or puncture, they are prone to fire or even explosion and other safety accidents. Therefore, the safety problems of lithium-ion batteries limit the further application of lithium-ion batteries to a great extent. [0003] CN 109755466A discloses a positive electrode sheet, an electrochemical device and a safety coating, the positive electrode sheet includes a current collector, a positive active material layer and a safety coating disposed between the current collector and the positive active material layer, the The safety coating comprise...

AI Technical Summary

Problems solved by technology

[0002] Lithium-ion batteries have been widely used in various electronic products and automobiles. However, when lithium-ion batteries are subjected to abnormal conditions such as high temperature, extrusion, collision or puncture, they are prone to fire, even explosion and other safety accidents.

Therefore, the safety problems of lithium-ion batteries have largely limited the further application of lithium-ion batteries.

[0003] CN 109755466A discloses a positive electrode sheet, an electrochemical device and a safety coating, the positive electrode sheet includes a current collector, a positive active material layer and a safety coating disposed between the current collector and the positive active material layer, the The safety coating comprises polyvinylidene fluoride and / or polyvinylidene chloride polymer matrix, conductive materials and inorganic fillers; although the safety coating disclosed by it can improve the safety problems of lithium-ion batteries, due to the coating of the safety coating, Increase the impedance of the battery at room temperature and reduce the electrochemical performance of lithium-ion batteries

[0004] CN 205900697U discloses a high-safety and high-power lithium-ion battery positive pole piece, which includes a current collector aluminum foil, a conductive carbon layer, a PTC coating, and an active material coating. The current collector aluminum foil is located between two conductive carbon layers, and the two layers The conductive carbon layer is respectively located between the current collector aluminum foil and a layer of PTC coating, and the two layers of PTC coating are respectively located between a conductive carbon layer and a layer of active material coating, and the two layers of active material coating are respectively located between the two layers of PTC The outer side of the coating; although the disclosed positive electrode sheet has an overcurrent protection effect, lithium-ion batteries still have major safety issues under high temperature or extrusion conditions

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