A preparation method of a porous lithium ion electrode sheet with high energy density and a lithium ion battery

Abstract

The invention provides a preparation method of a porous lithium ion electrode sheet with high energy density and a lithium ion battery. S1, A glue liquid is prepared by dissolving a binder in a N-methyl pyrrolidone solution, and the glue liquid is uniformly mixed with an active substance and a conductive agent to obtain a slurry; S2, respectively coating the mixed slurry on the current collector to obtain pole pieces; S3, cold pressing the coated pole piece, then coating the pore-forming agent on the surface of the cold-pressed pole piece, uniformly coating the pore-forming agent on the surface of the cold-pressed pole piece by means of a coating machine, drying while coating, and setting the drying temperature to be higher than the decomposition temperature of the pore-forming agent to obtain the porous lithium ion pole piece with high energy density. The invention improves the porosity of the thick electrode sheet and improves the electric performance by preparing a thick electrode with high surface density and coating a pore-forming agent on the surface of the electrode sheet after cold pressing.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a preparation method of a porous lithium ion pole piece with high energy density and a lithium ion battery. Background technique [0002] As a high-performance secondary battery, lithium-ion batteries are widely used in daily life due to their long cycle life and environmental friendliness, such as mobile phones, cameras, computers, electric bicycles, etc. [0003] In recent years, with the continuous expansion of its application range, especially in high-energy-consuming vehicles such as pure electric vehicles, plug-in hybrid vehicles, etc., the requirements for the energy density of lithium-ion batteries continue to increase. To improve the energy density of lithium-ion batteries, on the one hand, develop positive electrode materials with high capacity, such as lithium nickel manganese cobalt oxide (LiNi x CoyMn 1-x-y o 2 0.6<x<1, 0.3≤y≤1 / 3), lithium n...

AI Technical Summary

Problems solved by technology

However, through practical use, it has been found that thick electrodes also have disadvantages. The increase in the thickness of the pole piece increases the energy density of lithium ions to a certain extent, but the increase in energy density is not proportional to the increase in the thickness of the pole piece. Coated active material is not fully functioning

After research, it is found that this is because during the rolling process of the pole piece, the upper surface pole piece is stressed first to reach the design compaction density, resulting in a structure with small porosity in the upper layer and large porosity in the bottom layer of the pole piece, which is not conducive to the electrolyte. Infiltration, which is not conducive to the extraction and insertion of Li+, and the increase of the thickness of the pole piece makes the migration of Li+ more difficult, which eventually leads to the lithium ion capacity density not up to the standard, the battery electrical performance deteriorates, restricting its practical use, and improving the porosity of thick electrodes , Improving the energy density of thick electrodes is imminent

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