Positive pole piece and electrochemical device including the positive pole piece

Abstract

The invention provides a positive pole piece and an electrochemical device comprising the positive pole piece. The positive pole piece includes: a positive current collector, a positive active material layer placed on at least one surface of the positive current collector, and a safety layer placed between the positive active material layer and the positive current collector. Wherein, the safety layer includes adhesive substances, conductive substances and special sensitive substances; the special sensitive substances are at least one polysaccharide esterification product, wherein the esterification degree of monosaccharide units is 35%-98%. The electrochemical device prepared by using the positive electrode sheet of the present invention has obviously improved safety and electrical performance (such as cycle performance).

Description

technical field [0001] The invention relates to electrochemistry, in particular 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, safety problems such as fire and explosion sometimes occur in lithium-ion batteries during overcharging, which poses a great threat to people's lives and property safety. In addition, the cycle rate of lithium-ion batteries has also been questioned. [0003] Overcharging of lithium-ion batteries usually leads to the deterioration of its electrical properties, resulting in the deposition of lithium at the negative electrode, a significant decrease in electrical properties such as cycle and capacity, and in severe cases, it will cause a short circuit in the battery. A...

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Problems solved by technology

However, according to this improvement 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, which not only makes The PTC layer loses the PTC effect and deteriorates the electrical performance of the lithium-ion battery

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

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