CN113410421A - Positive electrode plate, manufacturing method thereof and lithium ion battery - Google Patents

Positive electrode plate, manufacturing method thereof and lithium ion battery Download PDF

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Publication number
CN113410421A
CN113410421A CN202110631512.8A CN202110631512A CN113410421A CN 113410421 A CN113410421 A CN 113410421A CN 202110631512 A CN202110631512 A CN 202110631512A CN 113410421 A CN113410421 A CN 113410421A
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insulating coating
pole piece
coating
inorganic filler
slurry
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孟宪伟
马子朋
李凡群
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Wanxiang A123 Systems Asia Co Ltd
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Wanxiang Group Corp
Wanxiang A123 Systems Asia Co Ltd
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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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • 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
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention relates to the field of lithium ion batteries, and discloses a positive pole piece, a manufacturing method thereof and a lithium ion battery in order to overcome the defects that the consistency of a ceramic insulating coating of the conventional positive pole piece is poor, the pole piece is easy to damage, and the service life of a slitting die is easy to reduce. The insulating coating slurry is prepared by using the high molecular polymer, the inorganic filler and the dispersing agent, and the insulating coating obtained by coating the insulating coating slurry on the positive pole piece has the advantages of good cohesiveness, high toughness, strong corrosion resistance, good consistency, low hardness, friendliness to the positive pole piece and small damage to a cutting die.

Description

Positive electrode plate, manufacturing method thereof and lithium ion battery
Technical Field
The invention relates to the field of lithium electronic batteries, in particular to a positive pole piece, a manufacturing method thereof and a lithium electronic battery.
Background
In the lithium battery manufacturing process, for reducing battery short circuit potential safety hazard, main technical scheme has: firstly, in the production process of the battery, an insulating tape is pasted at a tab and used for preventing the cross contact short circuit of a positive electrode tab, a negative electrode tab and a positive electrode active coating close to the tab end caused by diaphragm shrinkage or electrode piece dislocation in the battery; secondly, ceramic materials with good insulativity are coated at the pole lugs in the production process of the battery. The adhesive property of the insulating tape is not controllable, and once the insulating tape falls off and enters the electrolyte, the insulating tape loses the protection function and pollutes the electrolyte to influence the cycle performance and the safety performance of the battery. The ceramic material has high hardness and high rigidity, and is easy to damage the pole piece.
Chinese patent publication No. CN109148888B discloses a lithium battery electrode plate and a preparation method thereof, which is characterized by comprising the steps of preparing an active material layer and preparing a ceramic coating, wherein the step of preparing the active material layer comprises the steps of coating active slurry on a current collector and drying the current collector so as to enable the surface of the current collector to have the active material layer; preparing a ceramic coating, namely coating ceramic slurry on one side of an active material layer of the current collector and drying; the raw materials for preparing the ceramic slurry comprise ceramic powder, a binder, a thickening agent, a dispersing agent and a solvent; the preparation method of the ceramic slurry comprises the steps of mixing the binder and the solvent, and carrying out first stirring to prepare a glue solution with the viscosity of 200-400mpa & s; adding a thickening agent and a dispersing agent into the glue solution, and carrying out second stirring to obtain a premixed glue solution; adding ceramic powder into the premixed glue solution to carry out third stirring to obtain ceramic premixed slurry; sanding the ceramic pre-mixed slurry; adding the ceramic powder into the premixed glue solution for three times; controlling the vacuum degree to be less than or equal to-0.08 MPa during third stirring; controlling the viscosity of the ceramic premixed slurry to 2000-3500mpa & s; sanding is performed 3 or 4 times; the viscosity of the ceramic slurry is 1500-3000mpa · s. The defects are that the ceramic powder has poor dispersibility, and the consistency of the prepared insulating coating is poor; the ceramic coating has the characteristics of high hardness and high rigidity, and the ceramic can damage the rolling roller and the slitting die in the rolling and die cutting processes, so that the service lives of the rolling roller and the slitting die are shortened; because the ceramic coating has high hardness, stress concentration is easily generated at the joint of the insulating coating and the active substance coating, the strength of the tab is reduced, the tab is cracked, and the yield of the electrode plate is reduced.
Disclosure of Invention
The invention discloses a positive pole piece with an insulating coating which has the advantages of good cohesiveness, high toughness, strong corrosion resistance, good consistency, low hardness, friendliness to the pole piece and small damage to a slitting die, and a manufacturing method thereof, aiming at overcoming the defects that the consistency of the ceramic insulating coating of the conventional positive pole piece is poor, the pole piece is easy to damage and the service life of the slitting die is easy to reduce;
another object of the present invention is to provide a lithium ion battery.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
the utility model provides a positive pole piece, includes the mass flow body, and the mass flow body surface coating has active material coating, insulating coating, and insulating coating comprises high molecular polymer, inorganic filler, dispersant three component, and its content range is:
58 to 100% by weight of a high-molecular polymer
0 to 40% by weight of an inorganic filler
0 to 2% by weight of a dispersant.
The high molecular polymer has good insulativity and consistency, and simultaneously can resist impact extrusion without damaging the electrode pole piece coated by the high molecular polymer because the high molecular polymer is soft in material and low in hardness, and has correspondingly small damage to a slitting die; the inorganic filler can enhance the mechanical property of the insulating coating and prolong the service life of the insulating coating; the dispersant can improve the dispersion uniformity of the inorganic filler because the inorganic filler has poor dispersibility in most of solvents.
Further, the high molecular polymer is one or more of aramid fiber and derivatives thereof, PVDF (polyvinylidene fluoride), PVDF-HFP [ poly (vinylidene fluoride-co-hexafluoropropylene) ], PAN (polyacrylonitrile), PA (polyamide), acrylic acid-acrylamide copolymer, acrylonitrile-acrylamide copolymer, acrylic acid-acrylonitrile-acrylamide terpolymer, PI (polyimide) and derivatives thereof.
In order to provide good adhesion performance and corrosion resistance of the insulating coating, the inventor selects several types of high molecular polymers with excellent performance from various high molecular polymers to be used as the components of the insulating coating slurry.
Further, the inorganic filler is one or more of alumina, boehmite, silica, barium sulfate, magnesium oxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide and barium oxide.
Further, the particle diameter D50 of the inorganic filler is 0.2 to 5 μm.
Furthermore, the dispersing agent is PVP, and the using amount of the dispersing agent is 0-5 wt% of the inorganic filler.
A manufacturing method of a positive pole piece comprises the following steps:
(1) adding a high molecular polymer into a solvent, stirring and dissolving to obtain a polymer solution;
(2) dispersing inorganic filler and a dispersing agent into a solvent to obtain an inorganic filler dispersion liquid, adding the inorganic filler dispersion liquid into the polymer solution obtained in the step (1), and further dispersing to obtain a mixed dispersion liquid;
(3) and (3) respectively coating the mixed dispersion liquid obtained in the step (2) and the electrode active substance on a current collector, and drying to obtain the positive pole piece comprising the insulating coating and the electrode active substance coating.
Further, in the step (1), the solid content of the high molecular polymer in the polymer solution is 5-40 wt%.
Further, in the step (3), the mixed dispersion liquid is coated on the two sides of the current collector, and the obtained insulating coating has the thickness of 5-30 micrometers and the width of 3-10 mm.
Further, in the step (3), the gap between the insulating coating and the electrode active material coating is 0-2 mm.
A lithium ion battery comprises the positive pole piece. The insulating coating with the high molecular polymer does not deform and shrink or fall off from the pole piece when the battery is heated, so that the safety performance of the battery is ensured. The polymer insulating coating provided by the invention has lower density and thinner thickness, and has smaller influence on the increase of the energy density of the battery.
Due to the adoption of the technical scheme, the invention has the following beneficial effects: the high molecular polymer is used as a manufacturing material of the insulating coating, and the insulating coating has the characteristics of good cohesiveness, high toughness, strong corrosion resistance, good consistency and low hardness, so that the occurrence of the cracking condition of the tab is greatly reduced, the impact between a cutter and a pole piece can be reduced in the slitting process by using the slitting die, the damage to the slitting die is reduced, and the service life of the slitting die is prolonged; the prepared lithium ion battery is more stable, and the insulating property is improved.
Drawings
Fig. 1 is a schematic view of a positive electrode sheet of the present invention.
In the figure: 1. a tab; 2. an insulating coating; 3. and coating the active substance.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings.
A positive pole piece comprises a current collector, wherein the surface of the current collector is coated with an active substance coating and an insulating coating, and the insulating coating consists of three components, namely a high-molecular polymer, an inorganic filler and a dispersing agent.
Example 1
Preparing a positive pole piece containing a PI, acrylonitrile-acrylamide copolymer insulating coating: respectively dissolving PI and an acrylonitrile-acrylamide copolymer in NMP solvent to prepare NMP solution with the PI concentration of 40wt% and NMP solution with the acrylonitrile-acrylamide copolymer concentration of 40wt%, and mixing the two solutions according to the mass ratio of 8: 1 to obtain a mixed solution with a solid content of 40wt%, namely insulating coating slurry. As shown in fig. 1, the insulating coating paste is coated along the edge of the active material coating 3 near the tab 1, the thickness of the insulating coating paste is 10 μm, the width of the insulating coating paste is 5mm, the insulating coating 2 is formed by drying the paste, and the edge of the insulating coating 2 is cut and peeled in parallel along the edge 1mm of the active material coating 3. And obtaining an active substance coating and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Example 2
Preparing a positive pole piece containing an aramid fiber and acrylonitrile-acrylamide copolymer insulating coating: dissolving a para-aramid polymer in an NMP solvent to obtain an NMP solution with the aramid concentration of 12 wt%, dissolving an acrylonitrile-acrylamide copolymer in the NMP solvent to obtain an NMP solution with the acrylonitrile-acrylamide copolymer concentration of 40wt%, wherein the mass ratio of the aramid polymer solution to the acrylonitrile-acrylamide copolymer solution is 40: 3 (namely the ratio of the aramid fiber to the acrylonitrile-acrylamide copolymer is 8: 2), adding a proper amount of NMP to adjust the viscosity to make the solid content reach 10%, and preparing the insulating coating slurry. Coating insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 10 micrometers, the width of the insulating coating slurry is 7mm, drying the slurry to form an insulating coating 2, and cutting and stripping the edge of the insulating coating 2 in parallel along the 1mm position of the edge of the active substance coating 3. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Example 3
Preparing a positive pole piece containing PVDF, acrylonitrile-acrylamide copolymer, PVP and boehmite filler insulating coating: completely dissolving PVDF and an acrylonitrile-acrylamide copolymer in an NMP solvent according to the mass ratio of 12:7 to obtain a polymer mixed solution with the concentration of 24 wt% of PVDF and the concentration of 14% of the acrylonitrile-acrylamide copolymer, mixing boehmite powder with the particle size of 3 mu m of D50 and PVP according to the weight ratio of 20: 1 into NMP solvent, and stirring and dispersing at high speed to obtain boehmite dispersion liquid with the boehmite powder concentration of 4 wt% and the PVP concentration of 0.2 wt%; then, mixing the polymer mixed solution and the boehmite dispersion liquid according to the mass ratio of 2: 1, uniformly mixing, wherein the mass ratio of PVDF, acrylonitrile-acrylamide copolymer and boehmite is 6: 3.5: 0.5, adding NMP solvent to make the solid content of the slurry be 12%, and preparing the insulating coating slurry. Coating insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 15 micrometers, the width of the insulating coating slurry is 4mm, drying the slurry to form an insulating coating 2, and cutting and stripping the edge of the insulating coating 2 along the 1mm position of the edge of the active substance coating 3 in parallel. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Example 4
Preparing a positive pole piece containing an aramid fiber, PVDF, PVP and magnesium oxide insulating coating: aramid fiber and PVDF are mixed according to the mass ratio of 5: 4, completely dissolving in NMP solvent to obtain a polymer mixed solution with 20 wt% of aramid fiber and 16 wt% of PVDF, mixing the magnesium oxide powder with the particle size of D50 being 5 mu m with PVP according to the weight ratio of 40: 1 into NMP solvent, and stirring at high speed to obtain magnesium oxide dispersion liquid with 10 wt% of magnesium oxide concentration and 0.25 wt% of PVP concentration; and then mixing the polymer mixed solution with the magnesium oxide powder dispersion liquid according to the ratio of 5: 2, wherein the mass ratio of the PVDF, the aramid fiber and the magnesium oxide is 5: 4: adding NMP to adjust the viscosity to ensure that the solid content of the slurry is 12 percent, and preparing the insulating material slurry. Coating insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 15 micrometers, the width of the insulating coating slurry is 3mm, drying the slurry to form an insulating coating 2, and cutting and stripping the edge of the insulating coating 2 in parallel along the 1mm position of the edge of the active substance coating 3. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Example 5
Preparing a positive pole piece containing an aramid fiber, PAN, PVP and barium sulfate particle insulating coating: aramid fiber and PAN are mixed according to the proportion of 5: 3 is completely dissolved in NMP solvent to obtain a polymer mixed solution with 25 wt% of aramid fiber concentration and 15 wt% of PAN concentration; mixing barium sulfate with D50 particle size of 2 μm and PVP according to the weight ratio of 30: 1 mass ratio is dispersed into NMP solvent, and barium sulfate dispersion liquid with the barium sulfate concentration of 20 wt% and the PVP concentration of 0.7 wt% is obtained through high-speed stirring and dispersion; then, the polymer mixed solution and the barium sulfate dispersion liquid are mixed according to the proportion of 2: 1, wherein the mass ratio of aramid fiber, PAN and barium sulfate is 5: 3: and 2, adding NMP to adjust the viscosity to ensure that the solid content of the slurry is 20 percent, and preparing the insulating material slurry. Coating insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 30 micrometers, the width of the insulating coating slurry is 3mm, drying the slurry to form an insulating coating 2, and cutting and stripping the edge of the insulating coating 2 in parallel along the 2mm position of the edge of the active substance coating 3. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Example 6
Preparing a positive pole piece containing PVDF, acrylonitrile-acrylamide copolymer, PVP and an alumina filler insulating coating: PVDF and acrylonitrile-acrylamide copolymer are mixed according to the weight ratio of 12:7 in the weight ratio of PVDF 24 wt%, acrylonitrile-acrylamide copolymer 14 wt% polymer mixed solution, mixing alumina with D50 grain size of 0.2 μm and PVP in a ratio of 20: 1 into NMP solvent, and stirring at high speed to obtain alumina dispersion liquid with alumina concentration of 4 wt% and PVP concentration of 0.2 wt%; then, mixing the polymer mixed solution and the alumina dispersion liquid according to the mass ratio of 2: 1, uniformly mixing, wherein the mass ratio of PVDF, acrylonitrile-acrylamide copolymer to alumina is 6: 3.5: 0.5, adding NMP solvent to make the solid content of the slurry be 12%, and preparing the insulating coating slurry. And (3) coating the insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 15 micrometers, the width of the insulating coating slurry is 10mm, drying the slurry to form an insulating coating 2, and the edge of the insulating coating is connected with the edge of the active substance coating. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Example 7
Preparing a positive pole piece containing PVDF, an acrylonitrile-acrylamide copolymer, PVP and a silica particle filler insulating coating: PVDF and acrylonitrile-acrylamide copolymer are mixed according to the weight ratio of 12:7 in a mass ratio of 24 wt% of PVDF and 14 wt% of acrylonitrile-acrylamide copolymer, and mixing silica particles having a particle size of D50 of 3 μm with PVP in a ratio of 50: 1 into NMP solvent, and stirring at high speed to obtain silica dispersion liquid with silica concentration of 4 wt% and PVP concentration of 0.08 wt%; then mixing the polymer mixed solution and the silicon dioxide dispersion liquid according to the mass ratio of 2: 1, uniformly mixing, wherein the mass ratio of PVDF, acrylonitrile-acrylamide copolymer to silicon dioxide is 6: 3.5: 0.5, adding NMP solvent to make the solid content of the slurry be 12%, and preparing the insulating coating slurry. Coating insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 15 micrometers, the width of the insulating coating slurry is 10mm, drying the slurry to form an insulating coating 2, and cutting and stripping the edge of the insulating coating 2 in parallel along the 2mm position of the edge of the active substance coating 3. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Comparative example 1
And (3) obtaining the lithium ion battery by using the anode plate without the insulating coating and adopting a conventional battery manufacturing method.
Comparative example 2
Preparing a positive pole piece containing PVDF, PVP, boehmite and a ceramic filler insulating coating:
dissolving PVDF in NMP solvent to obtain polymer solution with PVDF concentration of 24 wt%, mixing ceramic powder with D50 grain size of 3 microns, boehmite powder with D50 grain size of 3 microns and PVP in the weight ratio of 28: 1: 1 into NMP solvent, and stirring and dispersing at high speed to obtain ceramic dispersion liquid with the ceramic concentration of 56 wt%, the boehmite powder concentration of 2 wt% and the PVP concentration of 2 wt%; then, mixing the polymer solution and the ceramic dispersion liquid according to the mass ratio of 1: 1, uniformly mixing, wherein the mass ratio of the ceramic to the PVDF to the boehmite is 28: 12: 1, adding NMP solvent to make the solid content of the slurry be 25%, and preparing the insulating coating slurry. And coating the insulating coating slurry along the edge of the active substance coating 3 close to the tab 1, wherein the thickness of the insulating coating slurry is 25 mu m, the width of the insulating coating slurry is 5mm, and drying the insulating coating slurry to form the insulating coating 2. And obtaining an active material layer and an insulating coating on the other side of the pole piece by the same method. The anode plate is used, a conventional battery manufacturing method is adopted, and electrolyte is injected to obtain the secondary lithium ion battery.
Cutting the positive pole pieces prepared in the embodiments 1-7 and the comparative examples 1 and 2, and counting the situations of pole ear cracking and pole piece yield; soaking the positive pole pieces of the embodiments 1-7 and the comparative examples 1 and 2 in electrolyte at normal temperature, and measuring the change condition of the adhesive force of the insulating coating before and after soaking; and the effect of the insulative coating on the service life of the cutting blade, the results are shown in table 1.
TABLE 1 Properties of the positive electrode sheets of examples 1 to 7 and comparative examples 1 and 2
Figure BDA0003103737810000061
As can be seen from the test results in table 1, compared with comparative example 1 without an insulating coating and comparative example 2 using a ceramic insulating coating, the positive electrode sheets of examples 1 to 7 of the present invention have significantly improved yield and greatly reduced proportion of cracking and degradation of the tab. The insulating coatings of the embodiments 1 to 7 mainly comprise high molecular polymers, so that the insulating coatings have good buffer performance and weaker rigidity, the pole pieces are almost not damaged in the slitting and rolling processes, and the yield of the pole pieces is improved; the inorganic filler is added into the high molecular polymer to enhance the toughness of the insulating coating, in the rolling process, the active material area extends, the edge of the active material is easy to generate stress concentration and crack, and the insulating coating added with the inorganic filler plays a certain role in buffering, dispersing stress and having weaker rigidity due to better toughness, so that destructive extrusion can not be carried out on the edge of the active material, the cracking of the tab is reduced, and the proportion of the cracking and degradation of the tab is reduced. In addition, the positive pole pieces of the embodiments 1 to 7 and the comparative examples 1 and 2 are completely soaked in the electrolyte for 48 hours, the adhesive force is reduced to a certain extent, and the adhesive force of the comparative example 2 is reduced most obviously, because the electrolyte system is very active and has a certain swelling erosion effect on PVDF in the insulating coating, so that the adhesive force is reduced, in the embodiments 1 to 7, the dispersibility of PVDF is improved through the combination of the components, the contact between PVDF and the electrolyte is reduced, the effect of inhibiting PVDF from being swelled and eroded is achieved, the swelling of the insulating coating is hindered, in the design of the lithium ion battery, the insulating coating is only soaked in the electrolyte for a short time, after the battery is activated, the residual electrolyte is reduced, the electrolyte is adsorbed in the pores of the positive and negative active coatings and the diaphragm, the swelling effect on the insulating coating is reduced, and the outer surface of the insulating coating reaches the swelling limit, the electrolyte can not enter the insulating coating to generate swelling effect on PVDF, and the falling of the insulating coating and the pollution to the electrolyte caused by long-term use are avoided. The pole pieces are cut by using the cutting die, and compared with a comparative example 1 without an insulating coating and a comparative example 2 with a ceramic insulating coating, the embodiments 1-7 with the high-molecular polymer insulating coating have obvious extension effect on the service life of the cutting die, and the comparative example 2 with the ceramic insulating coating has high rigidity because the ceramic filler has high hardness and can generate irregular stress action on a cutter during cutting to damage the cutter, while the comparative example 1 without the insulating coating has no buffering effect of the insulating coating, so that a small amount of influence can be caused on the service life of the cutting die.
Five samples of the lithium ion batteries of examples 1 to 7 and comparative examples 1 and 2 were each allowed to stand at 150 ℃ for 1 hour to perform a hot box test. The results of the experiment are shown in table 2.
Table 2 hot box experiments of lithium ion batteries of examples 1 to 7 and comparative examples 1 and 2
Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative example 1 Comparative example 2
Sample 1 √ √ √ √ √ √ √ √ √
Sample 2 √ √ √ √ √ √ √ × √
Sample 3 √ √ √ √ √ √ √ × √
Sample No. 4 √ √ √ √ √ √ √ √ √
Sample No. 5 √ √ √ √ √ √ √ × ×
As can be seen from Table 2, all of the samples of examples 1 to 7 passed the hot box test. And short-circuit ignition occurred in three of the five samples of comparative example 1. Short-circuit ignition occurred in one of the five samples of comparative example 2. It can be seen that the lithium ion batteries of examples 1 to 7 of the present invention have good stability and insulating properties compared to the lithium ion batteries of comparative examples 1 and 2.

Claims (10)

1. The positive pole piece comprises a current collector, wherein the surface of the current collector is coated with an active substance coating and an insulating coating, and is characterized in that the insulating coating consists of three components, namely a high molecular polymer, an inorganic filler and a dispersing agent, and the weight percentages of the components are as follows:
58 to 100 percent of high molecular polymer
0 to 40 percent of inorganic filler
0-2% of a dispersant.
2. The positive electrode plate as claimed in claim 1, wherein the high molecular polymer is one or more of aramid fiber and its derivatives, polyvinylidene fluoride PVDF, poly (vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP, polyacrylonitrile PAN, polyamide PA, acrylic acid-acrylamide copolymer, acrylonitrile-acrylamide copolymer, acrylic acid-acrylonitrile-acrylamide terpolymer, polyimide PI and its derivatives.
3. The positive electrode sheet according to claim 1, wherein the inorganic filler is one or more of alumina, boehmite, silica, barium sulfate, magnesium oxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, and barium oxide.
4. The positive electrode sheet according to claim 1 or 3, wherein the inorganic filler has a particle size D50 of 0.2-5 μm.
5. The positive electrode plate as claimed in claim 1, wherein the dispersant is polyvinylpyrrolidone PVP, and the dispersant is used in an amount of 0-5 wt% of the inorganic filler.
6. The method for manufacturing the positive pole piece according to the claims 1 to 5, characterized by comprising the following steps:
(1) adding a high molecular polymer into a solvent, stirring and dissolving to obtain a polymer solution;
(2) dispersing inorganic filler and a dispersing agent into a solvent to obtain an inorganic filler dispersion liquid, adding the inorganic filler dispersion liquid into the polymer solution obtained in the step (1), and further dispersing to obtain insulating coating slurry;
(3) and (3) respectively coating the insulating coating slurry and the electrode active material obtained in the step (2) on a current collector, and drying to obtain the electrode piece containing the insulating coating and the electrode active material coating.
7. The method for manufacturing the positive electrode plate according to claim 6, wherein in the step (1), the solid content of the polymer in the polymer solution is 5-40 wt%.
8. The method for manufacturing the positive pole piece according to claim 6, wherein in the step (3), the insulating coating slurry is coated on the current collector on two sides, and the obtained insulating coating has a thickness of 5-30 μm and a width of 3-10 mm.
9. The method for manufacturing the positive pole piece according to claim 6, wherein in the step (3), the gap between the insulating coating and the electrode active material coating is 0-2 mm.
10. A lithium ion battery comprising the positive electrode sheet according to claims 1 to 5.
CN202110631512.8A 2021-06-07 2021-06-07 Positive electrode plate, manufacturing method thereof and lithium ion battery Pending CN113410421A (en)

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CN114156431A (en) * 2021-11-30 2022-03-08 蜂巢能源科技有限公司 Positive electrode homogenizing method, positive electrode slurry and application thereof
CN114171718A (en) * 2021-11-01 2022-03-11 浙江锋锂新能源科技有限公司 Pole piece preparation method of composite foil current collector, pole piece and soft package battery
CN115377609A (en) * 2022-08-11 2022-11-22 浙江大象新能源科技有限公司 Polymer insulating coating and preparation method thereof
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CN115663112A (en) * 2022-11-17 2023-01-31 湖北亿纬动力有限公司 Electrode slice comprising colored insulating coating, preparation method of electrode slice and lithium ion battery

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