CN111969181A - Lithium ion battery negative plate based on film forming additive and preparation method and application thereof - Google Patents
Lithium ion battery negative plate based on film forming additive and preparation method and application thereof Download PDFInfo
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- H01M4/00—Electrodes
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- H—ELECTRICITY
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- H01M4/00—Electrodes
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Abstract
The invention relates to a lithium ion battery negative plate based on a film forming additive, and a preparation method and application thereof. The lithium ion battery negative plate based on the film forming additive can reduce the consumption of active lithium ions by first charge and discharge, improves the first efficiency of the negative electrode, is easy to be soaked by electrolyte, effectively reduces the time consumption of a liquid injection process, and is simple in preparation method operation, easy in raw material obtaining, low in cost and suitable for large-scale industrial production.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery negative plate based on a film forming additive, and a preparation method and application thereof.
Background
With the continuous popularization and subdivision of the application market of the lithium battery, the reduction of cost by prolonging the life cycle of the battery through improving the performance of the battery and prolonging the cycle life of the battery becomes a trend. The current influencing factors influencing the cycle life of the battery are interface stability, electrolyte retaining amount and the like, wherein the electrolyte retaining amount is particularly important and is an important way for stably transmitting lithium ions in the battery cell. In the process of charging the battery cell, the electrolyte inevitably undergoes certain reductive decomposition with the negative active material particles, and along with the continuous cyclic charge and discharge of the battery cell, the electrolyte is dried up gradually, so that the ion transmission is disabled, and the battery cell finally undergoes rapid capacity degradation due to lithium precipitation.
In addition, lithium ions are deintercalated from the positive electrode and enter the negative electrode during the first charge of the battery, and then are deintercalated from the negative electrode and enter the positive electrode during the discharge, and a certain amount of lithium ions are consumed due to the formation of a solid electrolyte film (SEI film) during this process, thereby decreasing the capacity of the battery, resulting in a decrease in the first efficiency of the battery.
In the prior art, in order to solve the problem that electrolyte consumption and lithium ion consumption caused by first charge and discharge are caused by reduction of the electrolyte on the surface of a negative electrode active material, a functional additive is generally added into the electrolyte, and the improvement effect of the method needs to be realized on the basis of full contact between the electrolyte and negative electrode active material particles, but the electrolyte is usually infiltrated from porous coatings at two sides of a negative electrode sheet to a middle copper foil, the middle copper foil enables gas not to be conducted on two sides, and meanwhile, when the electrolyte is coated on a negative electrode film layer, more than 10% of gas is always left in pores of the porous coatings, so that the electrolyte is prevented from infiltrating the active material, namely the electrolyte cannot be fully contacted with the negative electrode active material, and the improvement effect is limited.
Chinese patent CN 201610984197.6 discloses a high energy density lithium iron phosphate battery, which comprises a positive electrode, a diaphragm, a negative electrode, an electrolyte and a housing, wherein the negative electrode slurry comprises a negative electrode active material, a negative electrode conductive agent, a negative electrode binder and a solvent, and a multifunctional electrolyte additive is added into the electrolyte.
Chinese patent CN201610975186.1 discloses a preparation method of a lithium manganate battery cathode, wherein the cathode is prepared by uniformly coating a lithium ion battery cathode slurry on a cathode-based fluid electrolytic copper foil, drying, rolling by using a mirror-surface rolling machine and carrying out heat treatment; the negative electrode slurry is prepared by mixing an active substance, a conductive agent, a binder, a thickening agent, a film-forming agent, a pore-forming agent and deionized water, wherein the film-forming agent is a mixture of one or two of ethylene sulfite and propylene sulfite and diphenyl octyl phosphate. The organic esters such as ethylene sulfite are easily affected by high temperature in the mixing process of the negative electrode slurry, the requirement on temperature control in the mixing process is high, the ester film forming additive in the patent can be lost due to volatilization in a high vacuum baking process of about 100 ℃ before the liquid injection of the battery cell, only a small part of the electrode sheet can be stored, and the electrical property of the lithium ion battery is reduced.
Disclosure of Invention
The invention aims to provide a lithium ion battery negative plate based on a film forming additive, which can reduce the consumption of active lithium ions caused by initial charge and discharge, improve the initial efficiency of a negative electrode, and effectively reduce the time consumption of a liquid injection process because the negative plate is easily soaked by electrolyte.
The technical scheme adopted by the invention for solving the problems is as follows: the utility model provides a lithium ion battery negative pole piece based on film forming additive, the negative pole piece includes the copper foil and is located the negative pole thick liquids layer on copper foil both sides, the negative pole thick liquids layer is prepared by negative pole thick liquids, the negative pole thick liquids include active material, conductive agent, binder, SEI film forming additive, thickener, pH regulator, pH stabilizer, coating plasticizer, solvent, SEI film forming additive is lithium difluorophosphate.
Preferably, the active substance is one of artificial graphite, silicon monoxide, pure silicon, silicon/carbon composite, hard carbon and soft carbon, and the amount of the active substance is 90wt% to 300wt% of the amount of the solvent.
Preferably, the conductive agent is one or more of carbon black, carbon nanotubes and graphene, and the dosage of the conductive agent is 0.1wt% -50wt% of the dosage of the solvent.
Preferably, the binder is a polyacrylic acid aqueous solution with 25% solid content, and the amount of the polyacrylic acid aqueous solution is 5-50 wt% of the amount of the solvent.
Preferably, the amount of the lithium difluorophosphate is 1wt% to 10wt% of the amount of the solvent.
Preferably, the thickening agent is sodium carboxymethylcellulose, and the using amount of the thickening agent is 0.5-7 wt% of that of the solvent; the pH regulator is lithium hydroxide, and the dosage of the pH regulator is 0.02-5 wt% of the dosage of the solvent; the pH stabilizer is lithium carbonate, and the dosage of the pH stabilizer is 0.1-5 wt% of the dosage of the solvent; the coating plasticizer is ethylene carbonate, and the dosage of the ethylene carbonate is 0.1-2 wt% of the dosage of the solvent.
Preferably, the solvent is water.
The invention also aims to provide a preparation method of the lithium ion battery negative plate based on the film forming additive, which comprises the following steps:
(1) preparation of kneading solution
a. Adding the binder and the pH regulator into a stirring tank for stirring.
b. And c, adding a pH stabilizer into the solution in the step a for stirring.
c. And c, adding an SEI film forming additive into the solution obtained in the step b, and stirring to obtain a kneaded solution.
(2) Preparation of suspension glue solution
a. Adding the thickening agent and the solvent into a stirring tank for stirring, and scraping the wall after uniformly stirring.
b. And dispersing at high speed to obtain suspended glue solution.
(3) Negative electrode slurry preparation
a. The active material and the conductive agent are added into a stirring tank for dry mixing.
b. And (3) adding the kneaded solution obtained in the step (1) and a part of the suspension glue solution obtained in the step (2) for kneading.
c. And (3) adding the suspension glue solution obtained in the rest step (2) for dispersing.
d. And then adding a coating plasticizer for dispersion to obtain the negative electrode slurry.
(4) Preparation of pole piece
And (4) coating the negative electrode slurry obtained in the step (3) on two sides of the copper foil by using a slit extrusion coating machine, and drying to form a negative electrode sheet.
When the conductive agent is added in the form of a dispersion liquid, the steps a and b in the preparation of the negative electrode slurry in the step (3) are as follows: a. adding an active substance into a stirring tank, and b, adding the kneading solution obtained in the step (1), the conductive agent dispersion liquid and a part of the suspension glue solution obtained in the step (2) for kneading; the other steps are the same.
Preferably, the preparation method of the lithium ion battery negative electrode sheet based on the film forming additive specifically comprises the following steps:
(1) preparation of kneading solution
a. Adding 25% solid content binder water solution and pH regulator into stirring tank, and stirring for 30min with revolution at 25rpm/min and dispersion at 500 rpm/min.
b. And (b) adding a pH stabilizer into the solution in the step (a), and stirring for 120min by using the parameters of revolution at 25rpm/min and dispersion at 1500 rpm/min.
c. And c, adding an SEI film forming additive into the solution obtained in the step b, and stirring for 30min by using the parameters of revolution at 25rpm/min and dispersion at 500rpm/min to obtain a kneaded solution.
(2) Preparation of suspension glue solution
a. Adding the thickening agent and the solvent into a stirring tank, stirring for 30min at revolution speed of 25rpm/min and dispersion speed of 500rpm/min, and scraping the wall.
b. And then dispersing at high speed for 180min by using the parameters of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain the suspension glue solution.
(3) Negative electrode slurry preparation
a. The active material and the conductive agent are added into a stirring tank and dry-mixed for 30min by revolving at 25rpm/min and dispersing at 800 rpm/min.
b. And (3) adding the kneaded solution obtained in the step (1) and the suspension glue solution obtained in the step (2) from 1/3-1/2, and kneading for 60min by revolving at 15rpm/min and dispersing at 500 rpm/min.
c. And (3) adding the suspension glue solution obtained in the rest step (2), and dispersing at a high speed for 120min according to the revolution speed of 25rpm/min and the dispersion speed of 2500 rpm/min.
d. And adding a coating plasticizer, and dispersing at a high speed for 60min by using the parameters of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain the cathode slurry.
(4) Preparation of pole piece
a. And (3) coating the negative electrode slurry obtained in the step (3) on two sides of the copper foil by using a slit extrusion coating machine, and drying at 40-65 ℃ to obtain a negative electrode coating layer.
b. And (4) sequentially carrying out cold pressing and stripping on the dried copper foil containing the negative electrode coating layer to obtain the negative electrode plate.
The invention also aims to provide application of the lithium ion battery negative electrode sheet based on the film-forming additive, and the lithium ion battery negative electrode sheet is used for preparing a lithium ion battery.
Compared with the prior art, the invention has the advantages that:
(1) according to the invention, the film-forming additive lithium difluorophosphate is added in the material mixing process in the preparation process of the cathode slurry, the lithium difluorophosphate dissolved in water completely soaks the active material in a single-particle dispersion state, and each active material particle is coated by the lithium difluorophosphate, so that the uniformity and the integrity of the lithium difluorophosphate distributed on the surface of the cathode active material particle are greatly improved.
(2) In the prior art, a film forming additive lithium difluorophosphate is generally added in a form of dissolving in an electrolyte, but the solubility of the film forming additive lithium difluorophosphate in the electrolyte is only about 1 percent, and the addition amount of the film forming additive lithium difluorophosphate is limited by the using amount.
(3) According to the invention, the film-forming additive lithium difluorophosphate is added in the preparation process of the cathode slurry, and the surface of the pores of the cathode plate is modified, so that the infiltration effect of the organic electrolyte for infiltrating the cathode plate can be obviously improved, the time consumption of the liquid injection process is reduced, and the effective transmission capability of lithium ions is obviously improved.
(4) Lithium difluorophosphate is adopted as a film forming additive, and the lithium difluorophosphate contains lithium ions, so that the defect that a large amount of active lithium ions are consumed during film forming of film forming additives such as carbonates and the like which do not contain lithium ions is overcome, and the first charge-discharge efficiency of a battery cell is improved while the SEI film is promoted to be formed; in addition, the battery core needs to be baked in high vacuum (the temperature is about 100 ℃) before liquid injection, lithium difluorophosphate cannot volatilize, and the lithium difluorophosphate can be well stored in the negative plate.
Detailed Description
The present invention will be described in further detail with reference to examples.
Example 1
The utility model provides a lithium ion battery negative pole piece based on film forming additive, the negative pole piece includes the copper foil and is located the negative pole thick liquids layer on the copper foil both sides, the negative pole thick liquids layer is prepared by negative pole thick liquids, the negative pole thick liquids include artificial graphite, carbon black, the polyacrylic acid aqueous solution of 25% solid content, lithium difluorophosphate, sodium carboxymethylcellulose, lithium hydroxide, lithium carbonate, ethylene carbonate, water.
The adding amount of the artificial graphite is 114wt% of the using amount of water, the adding amount of the carbon black is 1.19wt% of the using amount of water, the adding amount of a 25% solid content polyacrylic acid aqueous solution is 9.56wt% of the using amount of water, the adding amount of lithium difluorophosphate is 2.27wt% of the using amount of water, the adding amount of sodium carboxymethylcellulose is 1.79wt% of the using amount of water, the adding amount of lithium hydroxide is 1.17wt% of the using amount of water, the adding amount of lithium carbonate is 0.5wt% of the using amount of water, and the adding amount of ethylene carbonate is 1.13wt% of the using amount of water.
A preparation method of a lithium ion battery negative plate based on a film forming additive specifically comprises the following steps:
(1) preparation of kneading solution
a. 4.64Kg of an aqueous solution of 25% polyacrylic acid having a solid content and 0.57Kg of lithium hydroxide were put into a stirring tank and stirred for 30min under the conditions of revolution at 25rpm/min and dispersion at 500 rpm/min.
b. And (b) adding 0.24Kg of nano lithium carbonate into the solution in the step (a), and stirring for 120min by using the parameters of revolution at 25rpm/min and dispersion at 1500 rpm/min.
c. And c, adding 1.1Kg of lithium difluorophosphate into the solution in the step b, and stirring for 30min under the parameters of revolution at 25rpm/min and dispersion at 500rpm/min to obtain a kneaded solution.
(2) Preparation of suspension glue solution
a. 0.87Kg of sodium carboxymethylcellulose and 48.52Kg of water were added to a stirring tank, and stirred for 30min with a revolution of 25rpm/min and a dispersion of 500rpm/min, followed by wall scraping.
b. Dispersing at high speed for 180min under the condition of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain suspended glue solution.
(3) Negative electrode slurry preparation
a. 55.39Kg of artificial graphite and 0.58Kg of carbon black were added to a stirring tank and dry-blended for 30min with the parameters of revolution at 25rpm/min and dispersion at 800 rpm/min.
b. 6.55Kg of the kneaded solution obtained in step (1) was added, and 30.44Kg of the suspension gum solution obtained in step (2) was added and kneaded under the conditions of revolution at 15rpm/min and dispersion at 500rpm/min for 60 min.
c. And (3) adding 19.95Kg of the suspension glue solution obtained in the step (2), and dispersing at a high speed for 120min according to the revolution speed of 25rpm/min and the dispersion speed of 2500 rpm/min.
d. And then 0.548Kg of ethylene carbonate is added, and the mixture is dispersed for 60min at a high speed by the parameters of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain the cathode slurry.
(4) Preparation of pole piece
a. And (3) coating the negative electrode slurry obtained in the step (3) on two sides of the copper foil by using a slit extrusion coating machine, and drying at 40-65 ℃ to obtain a negative electrode coating layer.
b. And (4) sequentially carrying out cold pressing and stripping on the dried copper foil containing the negative electrode coating layer to obtain the negative electrode plate.
A lithium ion battery is prepared by winding a positive plate, a negative plate obtained in the embodiment and a lithium battery diaphragm into a battery cell, placing the battery cell in an aluminum plastic film for baking, injecting electrolyte into the battery cell, sealing and standing, and then forming and aging the battery cell to obtain the lithium ion battery.
Wherein, lithium battery diaphragm: a polyethylene separator supplied by Celgard corporation having a thickness of 14 microns; electrolyte solution: lithium hexafluorophosphate (LiPF) containing 1M6) The solvent is a mixed solvent of diethyl carbonate, dimethyl carbonate and ethylene carbonate in a volume ratio of 2: 5; positive plate: adding a positive electrode active material LFP, a positive electrode binder PVDF and a positive electrode conductive agent carbon black into NMP, uniformly mixing to prepare a positive electrode slurry, and then adding a positive electrode into the positive electrode slurryAnd uniformly coating the anode slurry on an aluminum foil, drying at 90-115 ℃, and then sequentially rolling and slitting to obtain the anode sheet, wherein the weight ratio of the anode active material, the anode binder and the anode and cathode conductive agents is LFP: PVDF: carbon black of 95: 3: 2.
Example 2
The negative electrode sheet comprises a copper foil and negative electrode slurry layers positioned on two sides of the copper foil, wherein the negative electrode slurry layers are prepared from negative electrode slurry, and the negative electrode slurry comprises silicon monoxide, 5wt% of carbon nanotube water dispersion, 25% of solid content polyacrylic acid aqueous solution, lithium difluorophosphate, sodium carboxymethylcellulose, lithium hydroxide, lithium carbonate, ethylene carbonate and water.
Wherein the addition amount of the silicon oxide is 162.68wt% of the water amount, the addition amount of the 5% solid content carbon nano tube water dispersion liquid is 45wt% of the water amount, the addition amount of the 25% solid content polyacrylic acid water solution is 24.23wt% of the water amount, the addition amount of the lithium difluorophosphate is 4.88wt% of the water amount, the addition amount of the sodium carboxymethylcellulose is 2.08wt% of the water amount, the addition amount of the lithium hydroxide is 3wt% of the water amount, the addition amount of the lithium carbonate is 0.98wt% of the water amount, and the addition amount of the vinyl carbonate is 1.66wt% of the water amount.
A preparation method of a lithium ion battery negative plate based on a film forming additive specifically comprises the following steps:
(1) preparation of kneading solution
a. 7.98Kg of an aqueous solution of 25% polyacrylic acid with a solid content and 0.985Kg of lithium hydroxide were put into a stirring tank and stirred for 30min with the parameters of revolution at 25rpm/min and dispersion at 500 rpm/min.
b. And (b) adding 0.322Kg of nano lithium carbonate into the solution in the step (a), and stirring for 120min by using the parameters of revolution at 25rpm/min and dispersion at 1500 rpm/min.
c. And (c) adding 1.607Kg of lithium difluorophosphate to the solution in the step b, and stirring for 30min under the conditions of revolution at 25rpm/min and dispersion at 500rpm/min to obtain a kneaded solution.
(2) Preparation of suspension glue solution
a. 0.684Kg of sodium carboxymethylcellulose and 32.936Kg of water were added to a stirring tank, and stirred for 30min with a revolution of 25rpm/min and a dispersion of 500rpm/min, followed by wall scraping.
b. Dispersing at high speed for 180min under the condition of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain suspended glue solution.
(3) Negative electrode slurry preparation
a. 53.58Kg of silica was added to the stirred tank.
b. Then adding all the above kneaded solution, adding 14.82Kg of 5% solid content carbon nanotube aqueous dispersion and 23.62Kg of suspension glue solution obtained in step (2), and kneading for 60min under the condition of revolution at 15rpm and dispersion at 500 rpm.
c. Then 10Kg of the suspension glue solution obtained in the step (2) is added, and the suspension glue solution is dispersed for 120min at a high speed by the revolution of 25rpm and the dispersion of 2500 rpm.
d. Then 0.548Kg of ethylene carbonate is added, and the mixture is dispersed for 60min at a high speed according to the revolution speed of 25rpm and the dispersion speed of 2500rpm, so as to obtain the cathode slurry.
(4) Preparation of pole piece
a. And (3) coating the negative electrode slurry obtained in the step (3) on two sides of the copper foil by using a slit extrusion coating machine, and drying at 40-65 ℃ to obtain a negative electrode coating layer.
b. And (4) sequentially carrying out cold pressing and stripping on the dried copper foil containing the negative electrode coating layer to obtain the negative electrode plate.
A lithium ion battery is prepared by winding a positive plate, a negative plate obtained in the embodiment and a lithium battery diaphragm into a battery cell, placing the battery cell in an aluminum plastic film for baking, injecting electrolyte into the battery cell, sealing and standing, and then forming and aging the battery cell to obtain the lithium ion battery.
Wherein, lithium battery diaphragm: a polyethylene separator supplied by Celgard corporation having a thickness of 14 microns; electrolyte solution: lithium hexafluorophosphate (LiPF) containing 1M6) The solvent is a mixed solvent of diethyl carbonate, dimethyl carbonate and ethylene carbonate in a volume ratio of 2: 5; positive plate: adding a positive electrode active material LFP, a positive electrode binder PVDF and a positive electrode conductive agent carbon black into NMP, uniformly mixing to prepare a positive electrode slurry, uniformly coating the positive electrode slurry on an aluminum foil, and performing surface treatment at 90-115 DEG CAnd drying, rolling and cutting in sequence to obtain the positive plate, wherein the weight ratio of the positive active material, the positive binder and the positive and negative conductive agents is LFP, PVDF and carbon black is 95: 3: 2.
In order to embody the beneficial effects of the high-first-efficiency negative electrode based on the artificial SEI film of lithium difluorophosphate, a reference control group is provided in each of the examples 1 and 2, and the reference control group is different from the examples only in that lithium difluorophosphate and lithium carbonate are not added.
The performance test results of the prepared lithium ion battery negative electrode sheets of examples 1-2 and the corresponding reference control group are shown in table 1:
table 1 lithium ion battery negative plate performance test result table
The results of the performance tests on the prepared lithium ion batteries of examples 1-2 and the corresponding reference control are shown in table 2:
table 2 table of performance test results of lithium ion battery
As can be seen from table 1, the lithium ion battery negative electrode sheet has a lower electrolyte contact angle and excellent electrolyte affinity, and the soaking time required for equal amount of electrolyte absorption is shorter, which significantly reduces the time consumption of the electrolyte injection process of the battery cell; as can be seen from table 2, compared with a reference control group, the lithium ion battery of the present invention can significantly improve the first charge-discharge efficiency of the battery, and the prepared lithium ion battery has low dc impedance, excellent charge-discharge performance and excellent cycle performance.
In addition to the above embodiments, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of the claims of the present invention.
Claims (10)
1. A lithium ion battery negative plate based on film forming additive is characterized in that: the negative plate comprises a copper foil and negative slurry layers positioned on two sides of the copper foil, the negative slurry layers are prepared from negative slurry, the negative slurry comprises an active substance, a conductive agent, a binder, an SEI (solid electrolyte interphase) film forming additive, a thickening agent, a pH regulator, a pH stabilizer, a film coating plasticizer and a solvent, and the SEI film forming additive is lithium difluorophosphate.
2. The film-forming additive-based negative electrode sheet for lithium ion batteries according to claim 1, wherein: the active substance is one of artificial graphite, silicon monoxide, pure silicon, silicon/carbon composite, hard carbon and soft carbon, and the dosage of the active substance is 90-300 wt% of the dosage of the solvent.
3. The film-forming additive-based negative electrode sheet for lithium ion batteries according to claim 1, wherein: the conductive agent is one or more of carbon black, carbon nano tubes and graphene, and the dosage of the conductive agent is 0.1-50 wt% of that of the solvent.
4. The film-forming additive-based negative electrode sheet for lithium ion batteries according to claim 1, wherein: the binder is a polyacrylic acid aqueous solution with the solid content of 25%, and the using amount of the binder is 5-50 wt% of the using amount of the solvent.
5. The film-forming additive-based negative electrode sheet for lithium ion batteries according to claim 1, wherein: the dosage of the lithium difluorophosphate accounts for 1-10 wt% of the dosage of the solvent.
6. The film-forming additive-based negative electrode sheet for lithium ion batteries according to claim 1, wherein: the thickening agent is sodium carboxymethyl cellulose, and the dosage of the thickening agent is 0.5wt% -7wt% of that of the solvent; the pH regulator is lithium hydroxide, and the dosage of the pH regulator is 0.02-5 wt% of the dosage of the solvent; the pH stabilizer is nano lithium carbonate, and the dosage of the pH stabilizer is 0.1-5 wt% of the dosage of the solvent; the coating plasticizer is ethylene carbonate, and the dosage of the ethylene carbonate is 0.1-2 wt% of the dosage of the solvent.
7. The film-forming additive-based negative electrode sheet for lithium ion batteries according to claim 1, wherein: the solvent is water.
8. A preparation method of a lithium ion battery negative plate based on a film forming additive is characterized by comprising the following steps: the method comprises the following steps:
(1) preparation of kneading solution
a. Adding the binder and the pH regulator into a stirring tank for stirring;
b. adding a pH stabilizer into the solution obtained in the step a and stirring;
c. adding an SEI film forming additive into the solution obtained in the step b, and stirring to obtain a kneaded solution;
(2) preparation of suspension glue solution
a. Adding the thickening agent and the solvent into a stirring tank for stirring, and scraping the wall after uniformly stirring;
b. then dispersing at high speed to obtain a suspension glue solution;
(3) negative electrode slurry preparation
a. Adding an active substance and a conductive agent into a stirring tank for dry mixing;
b. adding the kneading solution obtained in the step (1) and part of the suspension glue solution obtained in the step (2) for kneading;
c. then adding the suspension glue solution obtained in the rest step (2) for dispersion;
d. then adding a coating plasticizer for dispersion to obtain negative electrode slurry;
(4) preparation of pole piece
Coating the negative electrode slurry obtained in the step (3) on two surfaces of a copper foil by using a slit extrusion coating machine, and drying to obtain a negative electrode coating layer;
b. and (4) sequentially carrying out cold pressing and stripping on the dried copper foil containing the negative electrode coating layer to obtain the positive plate.
9. The preparation method of the film-forming additive-based lithium ion battery negative electrode sheet according to claim 8, wherein the film-forming additive-based lithium ion battery negative electrode sheet comprises the following steps: the method specifically comprises the following steps:
(1) preparation of kneading solution
a. Adding 25% solid content binder and pH regulator into a stirring tank, and stirring for 30min with the parameters of revolution at 25rpm/min and dispersion at 500 rpm/min;
b. adding a pH stabilizer into the solution in the step a, and stirring for 120min by using the parameters of revolution at 25rpm/min and dispersion at 1500 rpm/min;
c. adding an SEI film forming additive into the solution obtained in the step b, and stirring for 30min by using the parameters of revolution at 25rpm/min and dispersion at 500rpm/min to obtain a kneaded solution;
(2) preparation of suspension glue solution
a. Adding the thickening agent and the solvent into a stirring tank, stirring for 30min by using the parameters of revolution at 25rpm/min and dispersion at 500rpm/min, and scraping the wall;
b. then dispersing at high speed for 180min by using the parameters of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain suspended glue solution;
(3) negative electrode slurry preparation
a. Adding active substances and a conductive agent into a stirring tank, and dry-mixing for 30min by revolving at 25rpm/min and dispersing at 800 rpm/min;
b. adding the kneaded solution obtained in the step (1) and the suspension glue solution obtained in the step (2) from 1/3-1/2, and kneading for 60min by revolving at 15rpm/min and dispersing at 500 rpm/min;
c. then adding the suspension glue solution obtained in the rest step (2), and dispersing at high speed for 120min according to the revolution speed of 25rpm/min and the dispersion speed of 2500 rpm/min;
d. then adding a coating plasticizer, and dispersing at a high speed for 60min by using the parameters of revolution at 25rpm/min and dispersion at 2500rpm/min to obtain negative electrode slurry;
(4) preparation of pole piece
a. Coating the negative electrode slurry obtained in the step (3) on two sides of a copper foil by using a slit extrusion coating machine, and drying at 40-65 ℃ to obtain a negative electrode coating layer;
b. and (4) sequentially carrying out cold pressing and stripping on the dried copper foil containing the negative electrode coating layer to obtain the negative electrode plate.
10. The application of the lithium ion battery negative plate based on the film forming additive is characterized in that: the negative electrode sheet according to any one of claims 1 to 7 is used for preparing a lithium ion battery.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114005967A (en) * | 2021-09-29 | 2022-02-01 | 合肥国轩高科动力能源有限公司 | Lithium battery negative electrode material and preparation method thereof |
| CN114094102A (en) * | 2021-11-03 | 2022-02-25 | 珠海冠宇电池股份有限公司 | Secondary battery |
| CN115036463A (en) * | 2022-06-23 | 2022-09-09 | 多氟多新能源科技有限公司 | Negative electrode of sodium ion battery |
| CN117133859A (en) * | 2023-10-23 | 2023-11-28 | 宁德时代新能源科技股份有限公司 | Negative electrode plate, battery cell, battery and electricity utilization device |
-
2020
- 2020-08-31 CN CN202010893421.7A patent/CN111969181A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114005967A (en) * | 2021-09-29 | 2022-02-01 | 合肥国轩高科动力能源有限公司 | Lithium battery negative electrode material and preparation method thereof |
| CN114094102A (en) * | 2021-11-03 | 2022-02-25 | 珠海冠宇电池股份有限公司 | Secondary battery |
| CN115036463A (en) * | 2022-06-23 | 2022-09-09 | 多氟多新能源科技有限公司 | Negative electrode of sodium ion battery |
| CN117133859A (en) * | 2023-10-23 | 2023-11-28 | 宁德时代新能源科技股份有限公司 | Negative electrode plate, battery cell, battery and electricity utilization device |
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