Method for improving surface lithium coating of negative electrode, lithium-supplemented negative electrode and lithium ion secondary battery

A negative electrode and lithium replenishment technology, applied in the field of energy storage, can solve the problems of small gaps in negative electrode material particles, negative electrode sheet crushing and deformation, and transfer to the negative electrode surface, etc., to achieve the effect of simple process and improved first effect.

Pending Publication Date: 2022-03-11
CHINA ENERGY LITHIUM
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Problems solved by technology

At present, ultra-thin lithium foil / lithium alloy foil can be used for negative electrode lithium supplementation, and the ultra-thin lithium foil / lithium alloy foil can be transferred to the negative electrode surface for lithium supplementation by pressure lamination, but there is a problem at present, because the negative electrode is compacted The negative electrode, the gap between the negative electrode material particles becomes very small, and it is difficult to transfer metal lithium to the surface of the negative electrode through pressure recombination: when using high pressure during recombination, the metal lithium can be fully transferred to the negative electrode, but the negative electrode sheet is partially crushed and deformed The problem; composite use of small pressure, metal lithium can only be partially transferred to the surface of the negative electrode

Method used

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  • Method for improving surface lithium coating of negative electrode, lithium-supplemented negative electrode and lithium ion secondary battery
  • Method for improving surface lithium coating of negative electrode, lithium-supplemented negative electrode and lithium ion secondary battery
  • Method for improving surface lithium coating of negative electrode, lithium-supplemented negative electrode and lithium ion secondary battery

Examples

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Effect test

Embodiment 1

[0051] Preparation of surface roughened negative electrode 1: use 8000 mesh sandpaper to grind and polish the surface of the original negative electrode (negative electrode doped with silicon oxide, thickness 110um) to obtain surface roughened negative electrode 1, the average roughness of the surface of roughened negative electrode 1 is 390nm.

[0052] Lithium-supplementing negative electrode 1 preparation: In a dry workshop with a dew point of -45°C, use a 5um thick ultra-thin lithium foil as a lithium supplementing source, use the above-mentioned surface roughened negative electrode 1 as the negative electrode, and put the upper and lower rolls of lithium foil and the dried surface The roughened negative electrode 1 is composited into a lithium-supplementing negative electrode under a pressure of 5 MPa, such as figure 1 As shown, the metal lithium is all transferred to the surface of the negative electrode, and the surface of the lithium supplemented negative electrode is re...

Embodiment 2

[0054]Preparation of surface roughening negative electrode 2: 30 grams of acetylene black (Shenzhen Kejing Zhida Technology Co., Ltd., average particle size 30nm), 5 grams of polyvinylidene fluoride (PVDF) (Shenzhen Kejing Zhida Technology Co., Ltd.), solvent N-Methylpyrrolidone (NMP) (Shanghai Aladdin Biochemical Technology Co., Ltd.) 1000 grams, obtain uniform slurry by mechanical mixing, by means of dimple coater, on the original negative electrode (negative electrode doped with silicon oxide, thickness 110um ) surface coating to obtain roughened negative electrode 2 (roughened layer thickness 3um), the average roughness of the roughened negative electrode surface is 450nm; dry the roughened negative electrode in a vacuum oven at 80°C for 24 hours, and take it out for use.

[0055] Preparation of lithium-supplementing negative electrode 2: In a dry workshop with a dew point of -45°C, use a 5um thick ultra-thin lithium foil as a lithium supplementing source, use the above-men...

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Abstract

The invention discloses a method for improving lithium coating on the surface of a negative electrode, a lithium-supplemented negative electrode and a lithium ion secondary battery. The method for improving lithium covering on the surface of the negative electrode comprises the steps that a coarsening layer is formed on the surface of a negative electrode active material layer of the negative electrode, the coarsening layer has evenly-distributed nanoscale roughness, ultra-thin metal lithium or a lithium alloy film with the thickness of 1-50 microns is compounded to the coarsening layer through pressure, and the lithium supplementing negative electrode is obtained. The process is simple and easy to operate, and can be used for batch production and application.

Description

technical field [0001] The invention belongs to the technical field of energy storage, and in particular relates to the improvement of lithium-ion secondary battery negative electrode lithium coating process. Background technique [0002] In 2025, the energy density of power batteries should reach 400wh / kg. In order to achieve high energy density, it is necessary to improve the positive and negative electrodes of the battery. For example, the negative electrode adopts the technology of doping silicon to supplement lithium, and the positive electrode uses ternary materials (NCM, NCA) or lithium iron phosphate to form a battery. The negative electrode doped with silicon or silicon oxide has the problem of low first efficiency, and an additional lithium source is needed to improve the first efficiency of the battery and increase the energy density at the same time. At present, ultra-thin lithium foil / lithium alloy foil can be used for negative electrode lithium supplementation...

Claims

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Application Information

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IPC IPC(8): H01M10/058H01M4/13H01M4/139H01M10/0525
CPCH01M4/139H01M4/13H01M10/0525H01M10/058Y02E60/10Y02P70/50
Inventor 郇庆娜孙兆勇孔德钰陈强牟瀚波
Owner CHINA ENERGY LITHIUM
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