Electrochemical device

Abstract

The invention relates to an electrochemical device. The electrochemical device comprises a positive pole piece, a negative pole piece and an electrolyte, wherein 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; the safety coating comprises a polymer matrix, a conductive material and an inorganic filler; and relative to the total weight of the polymer matrix, the conductive material and the inorganic filler, the weight percentage of the polymer matrix is 35wt%-75wt%, the weight percentage of the conductive material is 5wt%-25wt%, the weight percentage of the inorganic filler is 10wt-60wt%, the inorganic filler is an electrochemical active material or a conductive carbon-coated modified, conductive metal-coated modified or conductive polymer-coated modified material of the electrochemical active material, and the normal-temperature viscosity of the electrolyte is less than or equal to 4cp. The electrochemical device (e.g., a capacitor, a primary battery or a secondary battery, etc.) has improved safety performance and electrical performance.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and more specifically, the invention relates to an electrochemical device, especially a battery. 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, researchers have tried to improve it in ma...

AI Technical Summary

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, thus losing the effect of improving safety performance

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