CN114744151A - Negative pole piece containing binder PAA2, battery and preparation method - Google Patents
Negative pole piece containing binder PAA2, battery and preparation method Download PDFInfo
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- CN114744151A CN114744151A CN202210423245.XA CN202210423245A CN114744151A CN 114744151 A CN114744151 A CN 114744151A CN 202210423245 A CN202210423245 A CN 202210423245A CN 114744151 A CN114744151 A CN 114744151A
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Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a negative pole piece containing a binder PAA2, a battery and a preparation method, which relate to the field of lithium battery manufacture and comprise a current collector and a negative active material layer coated on the surface of the current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent and an additive; the adhesive PAA2 is also included, the adhesive PAA2 contains polyacrylic acid structural units, the molecular weight of the adhesive PAA2 is 80w-100w, and the adhesive PAA2 accounts for 1% -2.5% of the total mass. The invention can relieve the volume expansion of silicon-based materials, can effectively improve the stability of electrodes, and inhibit the expansion of the electrodes, thereby improving the thickness expansion of the battery in the charging and discharging processes, the molecular weight of the PAA2 used by the negative pole piece of the technical scheme is 80w-100w, the range not only ensures the caking property of the binding agent, but also does not influence the distribution of active substance particles in the negative pole, thereby obtaining better electrochemical performance.
Description
Technical Field
The invention relates to the technical field of lithium battery manufacturing, in particular to a negative pole piece containing a binder PAA2, a battery and a preparation method.
Background
The gram capacity of the silicon-based material is about 10 times of that of the graphite which is the most widely used cathode material at present, and the ultrahigh gram capacity is very suitable for a high energy density system. And the silicon-based material has the competitive advantage of easily obtained raw materials, is considered as the most promising cathode material of the next generation, and becomes the popular field of the most concerned and arranged in the industry. However, the silicon negative electrode material has low conductivity and large volume expansion in the circulation process, and the phenomena of crushing, slipping and the like of negative electrode particles are caused by the huge volume expansion, so that the pulverization, the capacity reduction, the cycle life reduction and the like of the electrode are finally caused. This hinders the further use of silicon-based anode materials in lithium ion batteries.
The binder is one of the important components of the lithium ion battery, and mainly has the functions of binding the active material and the conductive particles on a current collector, keeping the electrode structure relatively complete in the cyclic charge and discharge process and improving the cyclic stability. Although the proportion of the binder is small, the binder is a main source of mechanical properties in the electrode and plays an extremely important role in the production process and electrochemical properties of the electrode. If the binding power of the binding agent is weak, the silicon-based material can expand and contract continuously along with the insertion and the release of lithium, and a part of particles are separated from a current collector easily due to huge volume change, so that the electrical contact activity between the materials cannot be maintained, the first effect of the lithium ion battery is low, the capacity fading speed is too high, and the realization of the performance of the high-energy density battery is influenced.
Among binders for lithium batteries, PVDF, CMC, PAN, SBR, PAA, and the like are widely used. Wherein, polyacrylic acid (PAA) is a water-soluble high molecular polymer, which is also called acrylic acid homopolymer, is weakly acidic, has small swelling, stable electrode sheet structure in the charging and discharging process and relatively uniform coating; can form a compact film, increases the contact area of the active substance and the current collector, has high tensile mechanical strength, is beneficial to processing and the like. Research shows that the PAA has higher carboxyl content and is more suitable for the negative electrode of the silicon-containing material. PAA not only can form strong hydrogen bond action with Si, but also can form a coating layer similar to SEI film on the surface of Si, thereby inhibiting the decomposition of electrolyte and having better electrochemical performance in the aspect of Si electrode material. However, carboxyl groups are highly hydrophilic and are likely to react with residual moisture in the battery cell, and the carboxyl groups also react with LiPF6 in the electrolyte to decompose PF5, which affects the electrochemical performance of the battery cell.
The molecular weight and modification of PAA have great influence on the expansion of the lithium ion battery in the charging and discharging process, and the expansion of the pole piece is not facilitated by the overlarge or undersize molecular weight of the PAA. When the molecular weight is too small, the adhesive strength is insufficient. When the molecular weight of the binder is too large, the mechanical strength and the binding strength are high, but the uniformity of the distribution of active material particles in the electrode is also inhibited, thereby adversely affecting the electrochemical performance of the battery.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a negative pole piece containing a binder PAA2, a battery and a preparation method, which can relieve the volume expansion of a silicon-based material, effectively improve the stability of an electrode, inhibit the expansion of the electrode and further improve the thickness expansion of the battery in the charging and discharging process.
In order to achieve the above object, the present invention provides a negative electrode plate, comprising a current collector and a negative active material layer coated on the surface of the current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent and an additive; the adhesive PAA2 is also included, the adhesive PAA2 contains polyacrylic acid structural units, the molecular weight of the adhesive PAA2 is 80w-100w, and the adhesive PAA2 accounts for 1% -2.5% of the total mass.
In the technical scheme, the binder further comprises at least one of styrene butadiene rubber and modified materials thereof, styrene-acrylic emulsion and polyacrylate copolymer, and the binder accounts for 1-5% of the total mass.
In the above technical scheme, the negative active material is a carbon-based material, and the carbon-based material is at least one of graphite, carbon nanoparticles, graphene, and hard carbon.
In the above technical scheme, the negative electrode active material is a silicon-based material, and the silicon-based material is at least one of Si crystal grains, silicon oxide (SiOx), nano silicon, micro silicon, and porous silicon.
In the technical scheme, the proportion of the silicon-based material and the binder is 8-30%, wherein the proportion of the silicon-based material is 5-30%.
In the above technical solution, the negative active material includes a silicon-based material and a carbon-based material.
In the above technical solution, the negative electrode conductive agent is at least one of graphite, conductive carbon black, graphene, and carbon nanotubes.
The technical scheme also provides a preparation method of the negative pole piece, which is used for preparing the negative pole piece of any one of claims 1 to 7 and comprises the following steps:
s1: stirring sodium carboxymethylcellulose and deionized water to prepare uniform glue solution, adding a negative electrode conductive agent, and quickly stirring to uniformly disperse the negative electrode conductive agent in the glue solution;
s2: when the negative electrode conductive agent is uniformly dispersed in the glue solution, sequentially adding the silicon-based material, the carbon-based material and the additive, stirring and fully mixing, adding the binder, and stirring;
s3: after the materials are uniformly mixed, adding deionized water to adjust the viscosity, and then vacuumizing the slurry;
s4: uniformly coating the negative electrode slurry on the surface of a copper current collector, and drying at the temperature of 95-100 ℃ at the speed of 3-5M;
s5: and rolling the dried pole piece under the weight of 60-70 tons, and cutting the rolled negative pole piece into required width.
The technical scheme also provides a battery adopting the negative plate.
Compared with the prior art, the invention has the beneficial effects that:
10. the binder PAA2 adopted by the negative pole piece in the technical scheme comprises polyacrylic acid structural units, the molecular weight is 80W-100W, the stripping force is 0.6 +/-0.1N, the molecular weight control range of the PAA2 binder in the technical scheme is smaller, the binding force strength of the prepared negative pole piece is higher, and when silica expands greatly, the expansion of the silica can be inhibited through stronger binding property, so the cyclic expansion of the silica is lower; the battery adopting the negative pole piece made of the binder PAA2 can improve about 6.5% of the cycle expansion at normal temperature and about 5% of the cycle expansion at high temperature. Therefore, PAA2 with the molecular weight of 80W-100W is used, the cohesive strength is higher, and the thickness expansion of the silicon negative electrode lithium ion battery during long circulation can be improved to a certain extent. And the dynamic performance of the full cell containing the PAA2 negative pole piece is also obviously improved.
Drawings
In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the embodiments or technical solutions in the prior art are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a TG and DSC test chart of pole pieces respectively made of an adhesive PAA1 and an adhesive PAA 2;
FIG. 2 is a FTIR test chart of the electrode sheet made of the binder PAA1 and the binder PAA2 respectively;
FIG. 3 is a test chart of the peeling force of the pole pieces made of the binder PAA1 and the binder PAA2 respectively;
fig. 4 is a graph of test data of cyclic thickness expansion at normal temperature of full cells respectively made of a negative electrode tab comprising binder PAA1 and a negative electrode tab comprising binder PAA 2;
fig. 5 is a graph of test data for cyclic thickness expansion at 45 ℃ for full cells made with a negative electrode sheet comprising binder PAA1 and a negative electrode sheet comprising binder PAA2, respectively;
fig. 6 is an EIS test chart of a full cell made of a negative electrode sheet containing a binder PAA1 and a negative electrode sheet containing a binder PAA2, respectively;
fig. 7 is a graph of ac internal resistance test data for an all-cell made with a negative electrode tab comprising binder PAA1 and a negative electrode tab comprising binder PAA2, respectively;
fig. 8 is a graph of dc internal resistance test data for an all-cell made separately for a negative electrode tab comprising binder PAA1 and a negative electrode tab comprising binder PAA 2;
FIG. 9 is a TG, DSC test chart of PAA1 glue film;
FIG. 10 is a TG, DSC test chart of PAA2 adhesive film;
FIG. 11 is a tensile strength test chart of PAA1 adhesive film and PAA2 adhesive film;
FIG. 12 is a FIIR test chart of PAA1 adhesive film;
FIG. 13 is a FIIR test chart of PAA2 adhesive film.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. In addition, the terms "comprising," "including," "containing," and "having" are intended to be non-limiting, i.e., that other steps and other ingredients can be added that do not affect the results. Materials, equipment and reagents are commercially available unless otherwise specified. In addition, although the invention has described the forms of S1, S2, S3 and the like for each step in the preparation, the description is only for ease of understanding, and the forms of S1, S2, S3 and the like do not represent the limitation of the sequence of each step.
The embodiment provides a negative electrode plate, which comprises a current collector and a negative active material layer coated on the surface of the current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent, a binder and an additive; the adhesive comprises polyacrylic acid, wherein the molecular weight of the polyacrylic acid is 80w-100w, and the polyacrylic acid accounts for 1% -2.5% of the total mass. The adhesive also preferably comprises at least one of styrene-butadiene rubber and modified materials thereof, styrene-acrylic emulsion, polyacrylic acid and polyacrylate copolymer, and accounts for 1-5% of the total mass.
Among the conventional binders for lithium ion batteries, PVDF, CMC, PAN, SBR, PAA, etc. are widely used.
PVDF (polyvinylidene fluoride) was the earliest binder applied to lithium ion batteries. However, the defects of poor electronic and ionic conductivity, easy swelling by electrolyte, poor mechanical property and elasticity, high requirement on environment and the like affect the cycle life and the safety performance of the lithium ion battery.
CMC (sodium carboxymethylcellulose) is also a cellulose binder which has been studied more frequently, and is an ionic chain polymer aqueous binder, and a linear polymerization derivative of cellulose contains a large amount of carboxyl groups. The CMC has better electrochemical stability and can be suitable for a high-voltage anode material system. The transparent sticky glue solution is formed after the water absorption and swelling, and has the advantages of difficult fermentation, good stability, low price, safety and environmental protection. However, CMC has the disadvantages of poor flexibility and high brittleness, and the defects can be improved by blending CMC with high-elasticity high-molecular polymer (such as styrene-butadiene rubber).
PAN (polyacrylonitrile) contains a strong polar nitrile functional group, can form hydrogen bond acting force and dipole force with surrounding materials, and is used as a binder to be beneficial to improving the stability of the electrode plate structure and the wettability of electrolyte.
SBR (styrene butadiene rubber) is a high polymer formed by copolymerizing 1, 3-butadiene and styrene, has a simple molecular structure, is easy to synthesize, and is soluble in water and some organic solvents. The adhesive has excellent performance and is one of the most widely used adhesives of the lithium ion battery at present. Styrene (Styrene) and Butadiene (Butadiene) monomers are added into an aqueous emulsion which is generated by emulsion polymerization copolymerization of an emulsifier initiator and the like by taking water as a medium. The SBR latex particle unit is a core-shell structure, a cross-linked structure of a copolymer molecular chain is arranged in the shell, and a hydrophilic polar group and a surfactant are arranged on the shell. Is easy to dissolve in water and polar solvent, and has high adhesive strength, good mechanical stability and operability.
PAA (polyacrylic acid) is a water-soluble high-molecular polymer, also known as an acrylic acid homopolymer, and exhibits weak acidity. The electrode plate has small swelling, stable structure and relatively uniform coating in the charging and discharging processes; can form a compact film, increases the contact area of the active substance and the current collector, has high tensile mechanical strength, is beneficial to processing and the like. Research shows that the PAA has higher carboxyl content and is more suitable for the negative electrode of the silicon-containing material. PAA not only can form strong hydrogen bond action with Si, but also can form a coating layer similar to SEI film on the surface of Si, thereby inhibiting the decomposition of electrolyte and having better electrochemical performance in the aspect of Si electrode material. However, carboxyl groups are highly hydrophilic and are likely to react with residual moisture in the battery cell, and the carboxyl groups also react with LiPF6 in the electrolyte to decompose PF5, which affects the electrochemical performance of the battery cell.
However, the molecular weight and modification of PAA have a great influence on the expansion of the lithium ion battery in the charging and discharging processes, and the too large or too small molecular weight is not beneficial to the expansion of the pole piece. When the molecular weight is too small, the adhesive strength is insufficient. When the molecular weight of the binder is too large, the mechanical strength and the binding strength are high, but the uniformity of the distribution of active material particles in the electrode is also inhibited, thereby adversely affecting the electrochemical performance of the battery. Furthermore, by controlling the structure and molecular weight of the polymeric binder, the ductility and strength of the binder within the lithium ion battery can be controlled. Hydroxyl and carboxyl on the surface of the PAA interact with silicon oxide, a current collector and the like to form stable hydrogen bonds, so that the good cohesiveness is shown, meanwhile, the volume expansion of the silicon-based material is relieved to a certain extent, the stability of the electrode can be effectively improved, the expansion of the electrode is inhibited, and the thickness expansion of the battery in the charging and discharging process is improved.
The molecular weight of the PAA2 used in the negative electrode plate of the embodiment is 80w-100w, which not only ensures the cohesiveness of the binder, but also does not affect the distribution of active material particles in the negative electrode, thereby obtaining better electrochemical performance.
This example provides two negative electrode sheets using a PAA binder, where the binder used in the first negative electrode sheet is PAA1, and the molecular weight of PAA1 is about 110 w; the second kind of negative pole piece uses PAA2 as the adhesive, wherein the molecular weight of PAA2 is 80W-100W, because the molecular weight control range of PAA2 adhesive is smaller, the binding strength of the negative pole piece is higher, when silica expands greatly, the expansion of silica can be inhibited by stronger adhesive property, so the cycle expansion is lower.
Referring to fig. 1-3, compared with PAA1, the IR spectrum of the negative electrode sheet made of PAA2 is evident at 1600 and 1450, the DSC curve of PAA2 is evident at 1140, and the FTIR spectrum of the sheet of PAA2 shows an evident characteristic peak at 2851, which is caused by the stretching vibration of the C-H bond. Referring to fig. 3, the peeling force of the negative electrode sheet made of PAA2 is significantly greater than that of the negative electrode sheet made of PAA1, and the peeling force of the negative electrode sheet made of PAA2 is 0.6 ± 0.1N.
In addition, please refer to fig. 9-fig. 13, the characteristics of PAA1 and PAA2 adhesive films are also analyzed, wherein, referring to fig. 9-fig. 10, the TG test results show that: compared with PAA1, PAA2 has 88% of residual mass and 84% of PAA1 at about 210 ℃; at about 320 ℃, the residual mass of PAA2 is 85% and PAA1 is only 78%, so that the change of the mass of PAA2 is smaller and more stable than that of PAA 1. Referring to FIG. 10, the DSC curve of PAA2 adhesive film showed exothermic peaks around 220, 340 degC. Referring to fig. 11, when the tensile strength of the PAA1 glue film and the PAA2 glue film are tested under the same conditions, it can be seen that the tensile strength of the PAA2 is significantly higher than that of the PAA1 glue film, the tensile strength of the PAA2 glue film can reach 251N, and if the PAA2 binder is used in the negative electrode plate, the PAA2 will exhibit stronger adhesive force than the PAA1 when dispersed in the plate. In addition, referring to fig. 12 and fig. 13, the characteristic peak of the FIIR test of PAA1 glue film is obvious and substantially similar to that of PAA2 glue film, and the characteristic peak intensity of PAA2 at 2852 is higher. The FTIR of PAA2 has distinct absorption peaks at 3348 (hydroxyl), 2922 (methylene), 2851 (alkyl), 2242 (nitrile), 1667 (amide-CO-N), 1567 (amide N-H), C ═ C on the 1450 phenyl ring, 1409 (carboxylate COO-), 1338 (carboxylate COO-), 1119 (alcohol or lipid) wavenumbers.
Further, the negative active material of the present embodiment may be a silicon-based material, wherein the silicon-based material may be at least one of Si crystal grains, silicon oxide (SiOx), nano silicon, micro silicon, and porous silicon. The negative active material of the present embodiment may also be a carbon-based material, wherein the carbon-based material may be at least one of graphite, carbon nanoparticles, graphene, and hard carbon. Preferably, the anode active material of the present embodiment includes a silicon-based material and a carbon-based material.
In the production process of the negative pole piece, if the content of the binder of the negative pole slurry is too low, the binding power of the binder on the negative active material is insufficient, so that the binding power of the negative pole slurry on a negative current collector is insufficient, the negative pole piece is easy to decarbonize, and the dynamic performance of the battery cell is influenced; if the content of the binder is too large, the dispersion effect of the negative electrode slurry is poor, and the stirring efficiency is too low in the production process. The proportion of the silicon-based material and the binder in the negative pole piece is 8% -30%, wherein the proportion of the silicon-based material is 5% -30%. The polyacrylic acid in this example accounts for 1% to 2.5%. The proportion of the binder is 1 to 5 percent.
The negative electrode conductive agent is at least one of graphite, conductive carbon black (SP), graphene, carbon fiber (e.g., carbon fiber VGCF), and Carbon Nanotube (CNT).
Example two
The embodiment also provides a method for preparing the negative electrode plate of the first embodiment, which comprises the following steps:
s1: CMC (sodium carboxymethylcellulose) and deionized water are stirred and prepared into uniform glue solution, and then a negative electrode conductive agent is added and rapidly stirred to be uniformly dispersed in the glue solution;
s2: when the negative electrode conductive agent is uniformly dispersed in the glue solution, sequentially adding the silicon-based material, the carbon-based material and the additive, stirring and fully mixing, adding the binder, and stirring;
s3: after the materials are uniformly mixed, adding deionized water to adjust the viscosity, and then vacuumizing the slurry;
s4: uniformly coating the negative electrode slurry on the surface of a copper current collector, and drying at the temperature of 95-100 ℃ at the speed of 3-5M;
s5: the dried pole pieces are rolled under the weight of 60-70 tons, so that the contact among the negative active material, the conductive agent particles and the binder is tighter, the volume of the pole pieces is reduced, the energy density of the battery is improved, and finally the rolled negative pole pieces are cut into required widths to be manufactured into the negative pole pieces.
The embodiment also provides a battery using the negative pole piece of the embodiment, and the prepared negative pole piece, the positive pole piece, the diaphragm, the electrolyte, the aluminum plastic film and the like are assembled into the lithium ion battery.
Referring to fig. 4-8, in this embodiment, lithium ion batteries respectively prepared from a negative electrode sheet containing a PAA1 binder and a negative electrode sheet containing PAA2 are shown, where, referring to fig. 4, the lithium ion battery prepared from the negative electrode sheet containing PAA2 has smaller cycle expansion, and compared with PAA1, the normal temperature cycle expansion of the PAA2 battery can be improved by about 6.5%, and the high temperature cycle expansion can be improved by about 5%. Therefore, the use of PAA2 with higher cohesive strength can improve the thickness expansion of silicon anode lithium ion batteries to some extent during long cycling. Referring to fig. 5-7, all the full cells containing the negative electrode sheet of PAA2 have smaller EIS, dc internal resistance, and ac internal resistance than all the full cells containing PAA1, so that when PAA2 has stronger binding power than PAA1, the dynamic performance of the lithium ion cells prepared from the negative electrode sheet containing the PAA1 binder is significantly improved compared with the lithium ion cells prepared from the negative electrode sheets containing PAA 2.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (9)
1. The negative pole piece comprises a current collector and a negative active material layer coated on the surface of the current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent and an additive; the adhesive is characterized by also comprising a binder PAA2, wherein the binder PAA2 comprises polyacrylic acid structural units, the molecular weight of the binder PAA2 is 80w-100w, and the binder PAA2 accounts for 1% -2.5% of the total mass.
2. The negative electrode plate as claimed in claim 1, wherein the binder further comprises at least one of styrene-butadiene rubber and modified materials thereof, styrene-acrylic emulsion, and polyacrylate copolymer, and the binder accounts for 1-5% of the total mass.
3. The negative electrode sheet of claim 1, wherein the negative active material is a carbon-based material, and the carbon-based material is at least one of graphite, carbon nanoparticles, graphene and hard carbon.
4. The negative electrode plate as claimed in claim 1, wherein the negative active material is a silicon-based material, and the silicon-based material is at least one of Si crystal grains, silicon oxide (SiOx), nano-silicon, micro-silicon, and porous silicon.
5. The negative electrode plate as claimed in claim 4, wherein the silicon-based material and the binder account for 8-30%, and the silicon-based material accounts for 5-30%.
6. The negative electrode plate as claimed in claim 1, wherein the negative active material comprises a silicon-based material and a carbon-based material.
7. The negative electrode plate as claimed in claim 1, wherein the negative conductive agent is at least one of graphite, conductive carbon black, graphene, and carbon nanotubes.
8. A preparation method of a negative pole piece is characterized by being used for preparing the negative pole piece of any one of claims 1 to 7 and comprising the following steps:
s1: stirring sodium carboxymethylcellulose and deionized water to prepare uniform glue solution, adding a negative electrode conductive agent, and quickly stirring to uniformly disperse the negative electrode conductive agent in the glue solution;
s2: when the negative electrode conductive agent is uniformly dispersed in the glue solution, sequentially adding the silicon-based material, the carbon-based material and the additive, stirring and fully mixing, adding the binder, and stirring;
s3: after the materials are uniformly mixed, adding deionized water to adjust the viscosity, and then vacuumizing the slurry;
s4: uniformly coating the negative electrode slurry on the surface of a copper current collector, and drying at the temperature of 95-100 ℃ at the speed of 3-5M;
s5: and rolling the dried pole piece under the weight of 60-70 tons, and cutting the rolled negative pole piece into required width.
9. A battery comprising the negative electrode sheet according to any one of claims 1 to 7.
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| CN103779536A (en) * | 2013-11-06 | 2014-05-07 | 南京安普瑞斯有限公司 | Silicon-containing negative electrode of lithium ion battery and preparation method of silicon-containing negative electrode |
| CN104508873A (en) * | 2013-03-27 | 2015-04-08 | 株式会社Lg化学 | Anode active material slurry, anode using same slurry, and electrochemical device comprising same |
| JP2016046151A (en) * | 2014-08-25 | 2016-04-04 | 株式会社豊田自動織機 | Binding agent for negative electrode for secondary battery, negative electrode for secondary battery, manufacturing method thereof, and nonaqueous electrolyte secondary battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104508873A (en) * | 2013-03-27 | 2015-04-08 | 株式会社Lg化学 | Anode active material slurry, anode using same slurry, and electrochemical device comprising same |
| CN103779536A (en) * | 2013-11-06 | 2014-05-07 | 南京安普瑞斯有限公司 | Silicon-containing negative electrode of lithium ion battery and preparation method of silicon-containing negative electrode |
| JP2016046151A (en) * | 2014-08-25 | 2016-04-04 | 株式会社豊田自動織機 | Binding agent for negative electrode for secondary battery, negative electrode for secondary battery, manufacturing method thereof, and nonaqueous electrolyte secondary battery |
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