A positive pole piece and electrochemical device

Abstract

The invention relates to a positive pole piece and an electrochemical device. The positive electrode sheet includes a metal current collector, a positive electrode active material layer, and a safety coating disposed between the metal current collector and the positive electrode active material layer, the safety coating includes a polymer matrix, a conductive material and an inorganic filler, and the high The molecular matrix is ​​polyvinylidene fluoride and / or polyvinylidene chloride polymer matrix, based on the total weight of the safety coating, the weight percentage of the polymer matrix is ​​35wt%-75wt%, and the weight percentage of the conductive material is 5wt%-25wt%, the weight percentage of the inorganic filler is 10wt%-60wt%, and the breaking elongation δ of the metal current collector satisfies 0.8%≤δ≤4%. The positive electrode sheet can quickly disconnect the circuit when the electrochemical device (such as a capacitor, a primary battery or a secondary battery, etc.) is under high temperature conditions or an internal short circuit occurs due to nail penetration, thereby improving the high temperature safety of the electrochemical device.

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 metal current collector, thereby losing the effect of improving safety performance.

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