Positive pole piece and electrochemical device

Abstract

The invention relates to a positive pole piece and an electrochemical device. The positive pole piece comprises a current collector, a positive active material layer and a safety coating arranged between the current collector and the positive active material layer, wherein the safety coating comprises a polymer matrix, a conductive material and an inorganic filler; the polymer matrix comprises atleast two types of polymer materials; the first type of polymer material is polyvinylidene fluoride and / or polyvinylidene chloride; the solubility of the second type of polymer material in an oily solvent is less than that of the first type of polymer material; and the weight percentage of the first type of polymer material relative to the total weight of the polymer matrix, the conductive material and the inorganic filler is greater than or equal to 17.5%. The positive pole piece can quickly disconnect a circuit when an electrochemical device (such as a capacitor, a primary battery or a secondary battery) is in a high-temperature condition or an internal short circuit occurs, so that the high-temperature safety of the electrochemical device is improved.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and more specifically, the invention relates to a positive pole piece and an electrochemical device comprising the positive pole piece. Background technique [0002] Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life and low environmental pollution. However, when lithium-ion batteries are subjected to abnormal conditions such as extrusion, collision or puncture, they are prone to fire and explosion, causing serious hazards. Therefore, the safety problems of lithium-ion batteries have largely limited the application and popularization of lithium-ion batteries. [0003] A large number of experimental results show that the short circuit in the battery is the root cause of the safety hazard of lithium-ion batteries. In order to avoid the short circuit in the battery, res...

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Problems solved by technology

However, in this improved mode, when the active material slurry is coated on the surface of the PTC material layer, the solvent in the slurry (such as NMP, etc.) will dissolve the PTC material in the PTC layer and enter the upper active material layer, not only Make the PTC layer lose the PTC effect, and it will deteriorate the electrical performance

In addition, during the compaction step in the pole piece manufacturing process, the PTC material layer is easily squeezed to the edge, resulting in direct contact between the electrode active material layer and the current collector, thus losing the effect of improving safety performance

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