Lithium ion battery cathode and preparation method thereof and lithium ion battery

A lithium-ion battery, negative electrode technology, applied in battery electrodes, electrode manufacturing, secondary batteries and other directions, can solve the problems of internal short circuit, poor battery cycle performance, battery short circuit, etc.

Inactive Publication Date: 2009-05-20
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the shortcomings of the existing lithium-ion secondary battery negative electrode volume expansion that contains non-carbon materials that cause poor cycle performance of the battery or the continuous generation of lithium dendrites that cause internal short circuits in the battery, and provide a battery that can avoid volume Swelling and formation of lithium dendrites to improve the cycle performance of the battery and avoid short-circuiting the negative electrode of lithium-ion secondary batteries

Method used

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  • Lithium ion battery cathode and preparation method thereof and lithium ion battery

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preparation example Construction

[0020] The preparation method of the lithium ion battery negative electrode provided by the present invention comprises that the slurry containing the negative electrode material is continuously loaded on the negative electrode current collector, and then dried to form a continuous layer on the negative electrode current collector; the slurry containing the negative electrode material is loaded at intervals on the continuous layer, followed by drying to form a discontinuous layer on the continuous layer; and then rolling to obtain a negative electrode.

[0021] The negative electrode collector may be a conventional negative electrode collector in lithium ion batteries, for example, copper foil may be used as the negative electrode collector.

[0022] The slurry containing the negative electrode material can be continuously supported on the negative electrode current collector by conventional methods, for example, various existing coating methods for preparing lithium ion batter...

Embodiment 1

[0038] This example is used to illustrate the preparation of the lithium ion battery negative electrode of the present invention.

[0039] (1) After mixing 30 grams of micron-sized silicon powder (purity 99.99%) and 60 grams of micron-sized conductive copper powder (purity 90%) as the negative electrode active material, add to the solution containing 10 grams of polyvinylidene fluoride (PVDF) In a solution of 200 g of N-methylpyrrolidone (NMP) of the binder, stir evenly under a dry atmosphere to prepare negative electrode slurry.

[0040] (2) Coating the negative electrode slurry obtained in step (1) on the rough electrolytic copper foil current collector, the coating thickness is 80 microns.

[0041] (3) After the pole piece is dried, place it on the vacuum adsorption platform of the screen printing machine, and cover the screen printing plate (100 mesh nylon mesh, the thickness of the screen printing plate is 80 microns) on the coated continuous layer On, the slurry obtaine...

Embodiment 2

[0044] This example is used to illustrate the preparation of the lithium ion battery negative electrode of the present invention.

[0045] (1) 90 grams of micron-sized tin dioxide powder (purity 90%) as the negative electrode active material are added to 200 grams of N-methylpyrrolidone (NMP) dissolved in 10 grams of polyvinylidene fluoride (PVDF) binder solution, stirred evenly under a dry atmosphere to prepare negative electrode slurry.

[0046] (2) Coating the slurry obtained in step (1) on the rough electrolytic copper foil current collector with a coating thickness of 100 microns.

[0047] (3) Using the same method as in step (3) of Example 1, the difference is that the thickness of the discontinuous layer is 40 microns, and the coverage is 32%.

[0048] (4) Calendering after drying, so that the thickness of the continuous layer is 50 microns, and the thickness of the discontinuous layer is 20 microns, and the product is designated as A2.

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Abstract

The invention relates to a negative pole of a lithium ion cell, which comprises a negative pole current collection body and a negative pole material loaded on the current collection body, wherein the negative pole material is divided into two layers, wherein one layer is a continuous layer positioned on the current collection body, while the other layer is a discontinuous layer positioned on the continuous layer. A method for manufacturing the negative pole comprises the following steps: loading slurry containing the negative pole material on the negative pole current collection body continuously, and drying the slurry; loading the slurry containing the negative pole material on the continuous layer at intervals, and drying the slurry to form the discontinuous layer on the continuous layer; and then performing calendering to obtain the negative pole. The structure not only can provide adequate space for the volume change of an active material and effectively inhibit the damage to the current collection performance in an electrode caused by the volume change in the charging and discharging processes of the active material, but also can prevent the current collection body from being exposed directly to deposit lithium dendritic crystals. A lithium ion secondary cell prepared by using the negative pole can keep high capacity, and the cycle performance thereof is greatly improved simultaneously.

Description

technical field [0001] The invention relates to a negative pole of a lithium ion battery, a preparation method thereof and a lithium ion battery made of the negative pole. Background technique [0002] In recent years, as mobile devices have become more sophisticated and multifunctional, secondary batteries serving as power sources for mobile devices have been required to have higher capacities. The most widely used secondary battery meeting this requirement is a lithium ion secondary battery. However, in the current typical lithium secondary batteries with lithium cobalt oxide as the positive electrode and graphite as the negative electrode, the battery capacity has reached the saturation point, and it is difficult to significantly improve it. [0003] The current research on non-carbon negative electrode materials shows that many materials with high lithium storage performance, such as silicon, tin, aluminum, etc., can form alloys with lithium, and their reversible capaci...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/02H01M4/36H01M4/04H01M10/40
CPCY02E60/122Y02E60/10
Inventor 梁康群
Owner BYD CO LTD
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