阅读说明：本技术 一种用于锂离子电池的碳材料负极的制备方法 (Preparation method of carbon material cathode for lithium ion battery ) 是由 王现思 于 2019-09-12 设计创作，主要内容包括：本发明提供了一种用于锂离子电池的碳材料负极的制备方法,所述负极包括集流体、位于集流体表面的活性物质层以及位于活性物质层表面无机钝化层,所述活性物质层中,至少含有具有第一粒径的碳颗粒和具有第二粒径的碳颗粒,且在沿着集流体表面朝向无机钝化层的方向,具有第一粒径的碳颗粒的分布密度减小,具有第二粒径的碳颗粒的分布密度增大；所述第一粒径小于第二粒径；所述负极由以下方法制备得到,将第一浆料,第二浆料,第三浆料和第四浆料依次涂布在所述集流体表面得到所述活性物质层,然后在所述活性物质层上涂布无机氧化物浆料,干燥得到所述负极。由本发明的制备方法得到的负极浸润性好,稳定性高,具有较高的倍率性能和循环寿命。(The invention provides a preparation method of a carbon material negative electrode for a lithium ion battery, which comprises a current collector, an active material layer positioned on the surface of the current collector and an inorganic passivation layer positioned on the surface of the active material layer, wherein the active material layer at least contains carbon particles with a first particle size and carbon particles with a second particle size, and in the direction from the surface of the current collector to the inorganic passivation layer, the distribution density of the carbon particles with the first particle size is reduced, and the distribution density of the carbon particles with the second particle size is increased; the first particle size is smaller than the second particle size; the negative electrode is prepared by sequentially coating a first slurry, a second slurry, a third slurry and a fourth slurry on the surface of the current collector to obtain the active substance layer, then coating inorganic oxide slurry on the active substance layer, and drying to obtain the negative electrode. The cathode prepared by the preparation method provided by the invention has the advantages of good wettability, high stability, higher rate performance and longer cycle life.)

1. a preparation method of a carbon material negative electrode for a lithium ion battery comprises a current collector, an active material layer and an inorganic passivation layer, wherein the active material layer is positioned on the surface of the current collector, the active material layer at least contains carbon particles with a first particle size and carbon particles with a second particle size, the distribution density of the carbon particles with the first particle size is reduced, the distribution density of the carbon particles with the second particle size is increased along the surface of the current collector towards the inorganic passivation layer, the first particle size is 0.1-1 micron, the second particle size is 1-3 microns, and the first particle size is smaller than the second particle size; the inorganic passivation layer contains nano inorganic oxide particles, the particle size of the inorganic oxide particles is 50-200 nm, and the inorganic passivation layer is characterized in that: the preparation method comprises the following steps:

1) Adding a binder into a solvent, stirring and dispersing to obtain a glue solution, then ball-milling and mixing carbon particles with a first particle size and a conductive agent, and then adding the mixture into the glue solution in batches to obtain a first slurry, wherein in the first slurry, the carbon particles with the first particle size: conductive agent: binder 100:3-8: 3-8;

2) adding a binder into a solvent, stirring and dispersing to obtain a glue solution, then ball-milling and mixing carbon particles with a second particle size, a conductive agent and nano inorganic oxide particles, and then adding the mixture into the glue solution in batches to obtain a fourth slurry, wherein in the fourth slurry, the carbon particles with the second particle size: conductive agent: adhesive: nano inorganic oxide particles are 100:3-8:3-8: 5-12;

3) and (3) mixing part of the first slurry and part of the fourth slurry, and uniformly stirring and dispersing to obtain a second slurry, wherein in the second slurry, the carbon particles with the first particle size are as follows according to the weight ratio: the carbon particles of the second particle size are 9:1 to 6: 4;

4) And (3) mixing part of the first slurry and part of the fourth slurry, and uniformly stirring and dispersing to obtain a third slurry, wherein in the third slurry, the carbon particles with the first particle size are as follows according to the weight ratio: the carbon particles of the second particle size are 4:6 to 1: 9;

5) Adding a binder into a solvent, stirring and dispersing to obtain a glue solution, and then putting nano inorganic oxide particles into the glue solution in batches to obtain inorganic oxide slurry;

6) Coating the first slurry on a current collector, and drying; continuously coating the second slurry and drying; continuously coating the third slurry and drying; continuously coating the fourth slurry and drying; and finally, coating the inorganic oxide slurry on an active material layer, and drying, wherein the thickness of the active material layer is 20-60 microns, and the thickness of the inorganic passivation layer is 0.5-2 microns.

2. the method of claim 1, wherein the inorganic oxide particles are selected from the group consisting of alumina, magnesia, silica, titania and zirconia.

3. the method of claims 1-2, wherein the carbon particles are selected from natural graphite or artificial graphite.

4. a method according to any one of claims 1 to 3, wherein the conductive agent is selected from acetylene black, ketjen black, furnace black.

5. The method of claims 1-4, wherein the ball milling mixing time in step 1 is 30-60 minutes and the ball milling mixing time in step 2 is 3-10 hours.

6. A carbon material negative electrode for a lithium ion battery, which is produced by the production method according to any one of claims 1 to 5.

Technical Field

The invention relates to the technical field of lithium ion battery production, in particular to a preparation method of a carbon material cathode for a lithium ion battery.

Background

The lithium ion battery has the characteristics of high specific capacity, small self-discharge, wide working temperature range, high voltage platform, long cycle life, no memory effect, environmental friendliness and the like, and is widely applied to the fields of electric automobiles, energy storage and the like.

In the field, in order to pursue energy density, the compaction density is set to be high, especially for a battery cathode, and research finds that the energy density of the cathode is improved, and meanwhile, the wetting effect of electrolyte on a cathode sheet is reduced, the internal resistance is increased, and the cycle life is deteriorated after high-rate discharge; and the electrode polarization is obvious under the condition of high-rate charge and discharge, and the electrolyte is decomposed on the surface of the negative electrode after long-term use, so that the cycle performance of the battery is further deteriorated.

Disclosure of Invention

on the basis, the invention provides a preparation method of a carbon material negative electrode for a lithium ion battery, wherein the negative electrode comprises a current collector, an active material layer positioned on the surface of the current collector and an inorganic passivation layer positioned on the surface of the active material layer, the active material layer at least contains carbon particles with a first particle size and carbon particles with a second particle size, and in the direction along the surface of the current collector towards the inorganic passivation layer, the distribution density of the carbon particles with the first particle size is reduced, and the distribution density of the carbon particles with the second particle size is increased; the first particle size is smaller than the second particle size; the negative electrode is prepared by sequentially coating a first slurry, a second slurry, a third slurry and a fourth slurry on the surface of the current collector to obtain the active substance layer, then coating inorganic oxide slurry on the active substance layer, and drying to obtain the negative electrode. The cathode prepared by the preparation method provided by the invention has the advantages of good wettability, high stability, higher rate performance and longer cycle life.

The specific scheme is as follows:

A preparation method of a carbon material negative electrode for a lithium ion battery comprises a current collector, an active material layer and an inorganic passivation layer, wherein the active material layer is positioned on the surface of the current collector, the active material layer at least contains carbon particles with a first particle size and carbon particles with a second particle size, the distribution density of the carbon particles with the first particle size is reduced, the distribution density of the carbon particles with the second particle size is increased along the surface of the current collector towards the inorganic passivation layer, the first particle size is 0.1-1 micron, the second particle size is 1-3 microns, and the first particle size is smaller than the second particle size; the inorganic passivation layer contains nano inorganic oxide particles, the particle size of the inorganic oxide particles is 50-200 nm, and the inorganic passivation layer is characterized in that: the preparation method comprises the following steps:

1) Adding a binder into a solvent, stirring and dispersing to obtain a glue solution, then ball-milling and mixing carbon particles with a first particle size and a conductive agent, and then adding the mixture into the glue solution in batches to obtain a first slurry, wherein in the first slurry, the carbon particles with the first particle size: conductive agent: binder 100:3-8: 3-8;

2) adding a binder into a solvent, stirring and dispersing to obtain a glue solution, then ball-milling and mixing carbon particles with a second particle size, a conductive agent and nano inorganic oxide particles, and then adding the mixture into the glue solution in batches to obtain a fourth slurry, wherein in the fourth slurry, the carbon particles with the second particle size: conductive agent: adhesive: nano inorganic oxide particles are 100:3-8:3-8: 5-12;

3) And (3) mixing part of the first slurry and part of the fourth slurry, and uniformly stirring and dispersing to obtain a second slurry, wherein in the second slurry, the carbon particles with the first particle size are as follows according to the weight ratio: the carbon particles of the second particle size are 9:1 to 6: 4;

4) and (3) mixing part of the first slurry and part of the fourth slurry, and uniformly stirring and dispersing to obtain a third slurry, wherein in the third slurry, the carbon particles with the first particle size are as follows according to the weight ratio: the carbon particles of the second particle size are 4:6 to 1: 9;

5) adding a binder into a solvent, stirring and dispersing to obtain a glue solution, and then putting nano inorganic oxide particles into the glue solution in batches to obtain inorganic oxide slurry;

6) coating the first slurry on a current collector, and drying; continuously coating the second slurry and drying; continuously coating the third slurry and drying; continuously coating the fourth slurry and drying; and finally, coating the inorganic oxide slurry on an active material layer, and drying, wherein the thickness of the active material layer is 20-60 microns, and the thickness of the inorganic passivation layer is 0.5-2 microns. As for the number of layers of the active material layer, a larger number of layers can be selected so that particles of two kinds of particle diameters exhibit more stepwise concentration changes, and the thickness of each layer can be adjusted according to the battery performance requirements.

Further, the inorganic oxide particles are selected from aluminum oxide, magnesium oxide, silicon dioxide, titanium dioxide or zirconium dioxide. The choice of the inorganic oxide is not particularly limited, and any nano metal oxide having conductivity and electrolyte inertness can be used in the present invention.

Further, the carbon particles are selected from natural graphite or artificial graphite. For the carbon particles, mesocarbon microbeads, silicon carbon composites and composites of carbon with other metals may also be selected.

further, the conductive agent is selected from acetylene black, ketjen black and furnace black. For the conductive agent, carbon nanofibers or carbon nanotubes may also be selected.

Further, the ball milling and mixing time in the step 1 is 30-60 minutes, and the ball milling and mixing time in the step 2 is 3-10 hours.

Further, the carbon material negative electrode for the lithium ion battery is prepared by the preparation method.

The invention has the following beneficial effects:

1) The particle size of the carbon particles is increased along with the distance away from the current collector, and the larger the particle size is, the larger the pores in the active material are, so that the infiltration of the electrolyte is facilitated.

2) The carbon particles closer to the current collector have smaller particle size and larger specific surface area, so that the paths for lithium ions to be embedded are increased, the conductivity is enhanced, and the rate capability of the electrode is improved.

3) the active material with the particle size distribution can improve the binding force between carbon particles and a current collector and avoid pulverization and separation of the carbon material;

4) The large particles are distributed on the surface of the current collector, the specific surface area is relatively low, the decomposition of electrolyte on the surface of the electrode is reduced, and the service life performance of the electrode is improved;

5) The nano-scale oxide has good conductivity, and the long-time ball milling mixing of the large-particle carbon material, the conductive agent and the nano-oxide particles can lead part of the conductive agent and the nano-oxide particles to be coated on the surface of the large-particle carbon material, so that the conductivity of the carbon material is further improved, meanwhile, the contact between the carbon material and the electrolyte can be isolated, and the service life performance is improved;

6) The nano oxide layer is arranged on the surface of the electrode, so that the contact between the electrode and electrolyte is further isolated, and the service life performance of the electrode is improved.

Detailed Description

The present invention will be described in more detail below with reference to specific examples, but the scope of the present invention is not limited to these examples.