Dry-method positive pole piece of lithium ion secondary battery and preparation method of dry-method positive pole piece

Abstract

The invention belongs to the technical field of preparation of positive pole pieces of lithium batteries, and particularly relates to a dry-method positive pole piece of a lithium ion secondary battery and a preparation method of the dry-method positive pole piece. The positive pole piece of the lithium ion secondary battery provided by the invention is of a sandwich structure and sequentially comprises an electrode coating, a metal foil and an electrode coating, wherein the electrode coating comprises a carrier as well as a positive electrode main material and a conductive agent which are loaded inside or on the surface of the carrier; and the carrier is a PTFE non-woven fabric. By changing the compounding mode of the positive pole piece, the loading capacity of an active substance in the pole piece and the dispersion uniformity of the active substance and PTFE in the pole piece are improved, so that the resistance of the pole piece is remarkably reduced, and the electrical property of the pole piece is improved; meanwhile, no organic solvent is involved, so that no NMP waste gas is discharged, and the material cost of the battery is saved by 5-10%; and as a drying process is omitted, the manufacturing cost is saved by 40-60%.

Description

technical field [0001] The invention belongs to the technical field of lithium battery positive pole piece preparation, and in particular relates to a dry-process positive pole piece of a lithium ion secondary battery and a preparation method thereof. Background technique [0002] The preparation process of the positive electrode sheet of the lithium-ion secondary battery is: batching→slurry mixing→coating→hot pressing→slitting; the key steps are the slurry mixing and coating processes. At present, the slurry is mainly completed through the wet preparation process, that is, the ingredients are mixed by adding an organic solvent; Chlorovinylidene fluoride) is evenly mixed, and the organic solvent NMP (N-methylpyrrolidone) is gradually added to it to prepare a slurry with a certain solid content. The resulting slurry is squeezed and sprayed on the surface of the metal current collector by a coating machine, dried, and then enters the next process. [0003] However, the probl...

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Problems solved by technology

[0004] (1) The amount of organic solvent NMP is large, the unit price is high, and the recovered NMP cannot be reused, resulting in high battery manufacturing costs;

[0005] (2) During the drying process, a part of the organic solvent NMP will be discharged in the form of waste gas, which may pollute the environment;

[0006] (3) After drying, there will be a small amount of organic solvent NMP remaining in the positive electrode sheet, cracking the performance of the battery;

[0007] (4) With the recovery of the organic solvent, the binder will float up during the drying process, which increases the battery resistivity and reduces the battery performance;

[0008] (5) The drying process accounts for 40-55% of the total energy consumption in the battery manufacturing process, resulting in high battery manufacturing costs

However, the production cost of the dry material of this method is relatively high, and the preparation method of the dry material of this layer structure and the metal foil to form a pole piece is not given; due to the adhesive coating form adopted in this method, Based on the current preparation technology of positive pole pieces, it is still difficult for those skilled in the art to obtain positive pole pieces with lower resistance