CN115241409A - Gel-resistant anode slurry and preparation of porous electrode - Google Patents

Gel-resistant anode slurry and preparation of porous electrode Download PDF

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CN115241409A
CN115241409A CN202211022633.3A CN202211022633A CN115241409A CN 115241409 A CN115241409 A CN 115241409A CN 202211022633 A CN202211022633 A CN 202211022633A CN 115241409 A CN115241409 A CN 115241409A
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slurry
stirring
pore
porous electrode
gel
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曾培源
卫丹丹
晏子聪
窦元运
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Tianjie Energy Technology Co ltd
Wuhu Etc Battery Ltd
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Wuhu Etc Battery 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention discloses an anti-gel anode slurry and a porous electrode preparation method. According to the method, glycolic acid, acetic acid, anhydrous oxalic acid and anhydrous citric acid are used as pore-forming agents, and the pore-forming agents are added after part of organic solvent is added into a stirring tank, so that corrosion of the acidic pore-forming agents to the tank body can be avoided. The pore-forming agent can be mutually soluble with the N-methyl pyrrolidone, and the dispersion uniformity of the pore-forming agent in the slurry is ensured. By controlling the drying temperature of the pole piece, the volatilization speed of glycolic acid and acetic acid and the decomposition speed of anhydrous oxalic acid and anhydrous citric acid are controlled, the porosity of the pole piece is improved, and the structure of the pole piece is not damaged. The pore-forming agent used in the invention is a weakly acidic substance, can neutralize residual alkali on the surface of the anode material, adjusts the pH value of the slurry and has the function of relieving slurry gel.

Description

Gel-resistant anode slurry and preparation of porous electrode
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an anti-gel anode slurry and a preparation method of a porous electrode.
Background
Two methods are mainly used for improving the energy density of the battery cell, on one hand, an active material with higher gram capacity can be used, on the other hand, the coating weight of the pole piece is increased, and the compaction density of the pole piece is improved. The compaction density of the pole piece is strongly correlated with the performance of the battery cell, and the reasonable compaction density is beneficial to reducing the contact impedance and the alternating current impedance of the electrode and improving the electrochemical performance of the battery cell. However, when the compaction density is too high, the processability, the liquid retention and the wettability of the pole piece are affected. The high-rate performance and the cycle life of the battery cell can be worsened, and the temperature rise on the surface of the battery cell is increased. How to develop a high-energy-density long-cycle-life battery cell becomes an urgent problem to be solved in the industry.
Patent nos. CN108417777B and CN105633350A report that a porous electrode is obtained by mixing a pore-forming agent with a positive electrode material, homogenizing the mixture, coating the slurry and drying the slurry using a salt easily decomposed by heating, a low-boiling organic solvent, or the like as the pore-forming agent. The method utilizes gas generation and pore formation in the processes of salt decomposition and organic solvent volatilization, has the advantage of uniform pore structure distribution, but inorganic salts such as ammonium bicarbonate, uric acid, ammonium chloride and the like can raise the pH value of the slurry, accelerate slurry gelation, cause the problems of soft particles, scratches and the like in coating.
Patent CN111490225B uses the sulphur granule that size is homogeneous as pore-forming agent, adds the sulphur powder when the compounding, and the inside sulphur granule is got rid of to the pole piece drying back high temperature, has the controllable advantage of aperture, but need divide twice coating, and the temperature of removing sulphur is higher (200 ℃ C. The highest), and the duration is >6h, does not have guiding meaning in the actual production.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: the invention provides an anti-gel positive electrode slurry and a preparation method of a porous electrode.
According to the invention, the quantity and the type of the pore-forming agent are changed, the number of pole piece pores and the structural stability of the pole piece are balanced, the phenomena of demoulding and powder dropping are avoided, and the liquid retention capacity and the electrical property of the pole piece can be improved.
In order to solve the technical problems, the invention provides the following technical scheme:
a method for preparing a porous electrode by adopting anti-gel anode slurry comprises the following specific steps:
s1: mixing and stirring a positive electrode active material, a conductive agent and a binder; the positive active material is one of lithium iron phosphate, lithium cobaltate, lithium manganate and ternary materials;
s2: adding part of organic solvent into the S1 mixed material and stirring, wherein the solid content of the slurry is 70-75wt%;
s3: adding a pore-forming agent and the residual organic solvent, and stirring and dispersing, wherein the solid content of the slurry is 62-70wt%;
s4: the stirring dispersion rotating speed is increased;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, baking at 90-150 ℃, and cooling to obtain the porous electrode.
Preferably, the proportion of the positive electrode active material, the conductive agent and the binder is 96-98: 1 to 2:1 to 2.
Preferably, the conductive agent is one or more of conductive carbon black, acetylene black, carbon nanotubes, graphene and ketjen black.
Preferably, the binder is polyvinylidene fluoride; the organic solvent is N-methyl pyrrolidone.
Preferably, the pore-forming agent is one or more of glycolic acid, acetic acid, anhydrous oxalic acid and anhydrous citric acid, and the usage amount of the pore-forming agent is 0.5-2% of the total weight of the pole piece material;
preferably, the stirring revolution speed in the S1 is 25-35rpm, the rotation speed is 500-800rpm, and the dispersion time is 30-60min; in the S2, the stirring revolution speed is 10-25rpm, the rotation speed is 100-200rpm, and the dispersion time is 20-45min; in the S3, the stirring revolution speed is 25-40rpm, the rotation speed is 500-800rpm, and the dispersion time is 40-60min; in the S4, the stirring revolution speed is increased to 30-40rpm, the rotation speed is increased to 1500-1800rpm, and the dispersion time is 150-180min.
Preferably, the primary drying temperature of the surface A in the S6 is 90-105 ℃, and the secondary drying temperature is 115-130 ℃; the primary drying temperature of the surface B is 90-105 ℃, and the secondary drying temperature is 125-150 ℃.
The invention has the following beneficial effects:
according to the invention, glycolic acid, acetic acid, anhydrous oxalic acid and anhydrous citric acid are used as pore-forming agents, and the pore-forming agents are added after part of organic solvent is added into a stirring tank, so that the corrosion of the acidic pore-forming agents to the tank body can be avoided, and the machine loss is reduced.
Glycolic acid and acetic acid can be mutually soluble with N-methyl pyrrolidone, and anhydrous oxalic acid and anhydrous citric acid are easily soluble in N-methyl pyrrolidone, so that the dispersion uniformity of the pore-forming agent in the slurry is ensured. The glycolic acid and the acetic acid have low boiling points, and generate a large amount of bubbles when volatilized at high temperature, thereby realizing pore-forming. The anhydrous oxalic acid and the anhydrous citric acid are decomposed to generate gas to realize pore forming. By controlling the drying temperature of the pole piece, the volatilization speeds of glycolic acid and acetic acid and the decomposition speeds of anhydrous oxalic acid and anhydrous citric acid are controlled, the porosity of the pole piece is improved, and the structure of the pole piece is not damaged. The pore-forming agent does not react with the electrode material chemically and does not affect the electrical property.
The pore-forming agent used in the invention is a weakly acidic substance, can neutralize residual alkali on the surface of the anode material, adjusts the pH value of the slurry and has the function of relieving slurry gel. Soft particles and scratches in the slurry are effectively reduced, and the yield and the excellent rate are improved. The pore-forming agent absorbed into the material by capillary action in the homogenizing process cannot be completely volatilized after being dried at normal pressure for a short time, and the residual acidic substance can effectively inhibit Fe in the lithium iron phosphate 2+ When oxidized, the lithium iron phosphate electrode exhibits less impedance, higher reversible capacity and better cycling stability.
The porosity of the obtained pole piece is 29-49%, the pore structure is uniformly distributed, the liquid retention capacity of the pole piece can be improved, sufficient electrolyte exists in the battery cell circulating process, and the multiplying power performance and the circulating life of the battery cell are ensured.
Detailed Description
The following examples are included to provide further detailed description of the present invention and to provide those skilled in the art with a more complete, concise, and exact understanding of the principles and spirit of the invention.
Example 1: the porous electrode plate is prepared by the following method:
s1: mixing 97 parts of lithium iron phosphate, 1 part of conductive carbon black and 2 parts of polyvinylidene fluoride, stirring, revolving at 25rpm, rotating at 800rpm, and dispersing for 30min; wherein polyvinylidene fluoride is used as a binder. The stirring devices used in the embodiment of the invention are double-dispersion-shaft double-planet stirrers.
S2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: adding 0.5 part of glycolic acid and the rest of N-methyl pyrrolidone, stirring and dispersing, wherein the revolution is 40rpm, the rotation is 600rpm, and the dispersion time is 40min, and the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 95 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 95 ℃, and the secondary drying temperature is 135 ℃, so that the porous electrode is obtained.
Example 2: the porous electrode plate is prepared by the following method:
s1: mixing 97.5 parts of lithium iron phosphate, 1 part of acetylene black and 1.5 parts of polyvinylidene fluoride, stirring, revolving at 25rpm, rotating at 800rpm, and dispersing for 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: adding 1 part of acetic acid and the rest N-methyl pyrrolidone, stirring and dispersing, wherein the revolution is 25rpm, the rotation is 600rpm, and the dispersion time is 60min, so that the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 40rpm, the rotation speed is increased to 1800rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 95 ℃, and the secondary drying temperature is 126 ℃; and the primary drying temperature of the surface B is 100 ℃, and the secondary drying temperature is 135 ℃ to obtain the porous electrode.
Example 3: the porous electrode plate is prepared by the following method:
s1: mixing 96 parts of lithium iron phosphate, 2 parts of Ketjen black and 2 parts of polyvinylidene fluoride, stirring, revolving at 25rpm, rotating at 800rpm, and dispersing for 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: adding 1 part of anhydrous oxalic acid and the rest N-methylpyrrolidone, stirring and dispersing, wherein the revolution is 25rpm, the rotation is 800rpm, and the dispersion time is 40min, so that the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the autorotation speed is increased to 1500rpm, and the dispersion time is 180min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 100 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 105 ℃, and the secondary drying temperature is 145 ℃, so that the porous electrode is obtained.
Example 4: the porous electrode plate is prepared by the following method:
s1: mixing 97 parts of lithium iron phosphate, 1 part of conductive carbon black and 2 parts of polyvinylidene fluoride, stirring, revolving at 25rpm, rotating at 800rpm, and dispersing for 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: 0.5 part of anhydrous citric acid and the rest of N-methylpyrrolidone are added, stirring and dispersing are carried out, the revolution is 25rpm, the rotation is 600rpm, and the dispersing time is 40min, wherein the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 100 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 105 ℃, and the secondary drying temperature is 150 ℃ to obtain the porous electrode.
Example 5: the porous electrode plate is prepared by the following method:
s1: mixing 98 parts of lithium cobaltate, 1 part of conductive carbon black and 1 part of polyvinylidene fluoride, stirring, revolving at 35rpm, rotating at 500rpm, and dispersing for 60min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 10rpm, the rotation is 200rpm, the dispersion time is 30min, and the solid content of the slurry is 70-75wt%;
s3: adding 0.5 part of glycolic acid and the rest of N-methyl pyrrolidone, stirring and dispersing, wherein the revolution is 35rpm, the rotation is 500rpm, and the dispersion time is 40min, and the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 95 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 95 ℃, and the secondary drying temperature is 135 ℃ to obtain the porous electrode.
Example 6: the porous electrode plate is prepared by the following method:
s1: mixing 97.5 parts of lithium cobaltate, 0.8 part of carbon nano tube and 1.7 parts of polyvinylidene fluoride, stirring, revolving at 25rpm, rotating at 800rpm, and dispersing for 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: adding 1 part of acetic acid and the rest N-methylpyrrolidone, stirring and dispersing, wherein the revolution is 25rpm, the rotation is 600rpm, and the dispersion time is 60min, so that the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1800rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 95 ℃, and the secondary drying temperature is 126 ℃; and the primary drying temperature of the surface B is 100 ℃, and the secondary drying temperature is 135 ℃ to obtain the porous electrode.
Example 7: the porous electrode plate is prepared by the following method:
s1: mixing and stirring 98 parts of ternary material, 0.5 part of graphene and 1.5 parts of polyvinylidene fluoride, wherein the revolution is 25rpm, the rotation is 800rpm, and the dispersion time is 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 25rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: adding 1 part of anhydrous oxalic acid and the rest N-methyl pyrrolidone, stirring and dispersing, wherein the revolution is 25rpm, the rotation is 600rpm, and the dispersion time is 40min, and the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 100 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 105 ℃, and the secondary drying temperature is 145 ℃, so that the porous electrode is obtained.
Example 8: the porous electrode plate is prepared by the following method:
s1: mixing 98 parts of lithium manganate, 1 part of conductive carbon black and 1 part of polyvinylidene fluoride, stirring, wherein the revolution is 25rpm, the rotation is 800rpm, and the dispersion time is 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: 0.5 part of anhydrous citric acid and the rest of N-methylpyrrolidone are added, stirring and dispersing are carried out, the revolution is 25rpm, the rotation is 600rpm, and the dispersing time is 40min, wherein the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 100 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 105 ℃, and the secondary drying temperature is 150 ℃ to obtain the porous electrode.
Comparative example 1: the porous electrode plate is prepared by the following method:
s1: mixing 97 parts of lithium iron phosphate, 1 part of conductive carbon black and 2 parts of polyvinylidene fluoride, stirring, wherein the revolution is 25rpm, the rotation is 800rpm, and the dispersion time is 30min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 15rpm, the rotation is 100rpm, the dispersion time is 20min, and the solid content of the slurry is 70-75wt%;
s3: adding the rest N-methyl pyrrolidone, stirring and dispersing, wherein the revolution is 25rpm, the rotation is 600rpm, and the dispersion time is 40min, and the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 95 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 95 ℃, and the secondary drying temperature is 135 ℃, so that the porous electrode is obtained.
Comparative example 2: the porous electrode plate is prepared by the following method:
s1: mixing 98 parts of lithium cobaltate, 1 part of conductive carbon black and 1 part of polyvinylidene fluoride, stirring, wherein the revolution is 35rpm, the rotation is 500rpm, and the dispersion time is 60min;
s2: adding part of N-methyl pyrrolidone into the S1 mixed material and stirring, wherein the revolution is 10rpm, the rotation is 200rpm, the dispersion time is 30min, and the solid content of the slurry is 70-75wt%;
s3: adding the rest N-methyl pyrrolidone, stirring and dispersing, wherein the revolution is 35rpm, the rotation is 500rpm, and the dispersion time is 40min, so that the solid content of the slurry is 62-70wt%.
S4: the revolution speed is increased to 30rpm, the rotation speed is increased to 1500rpm, and the dispersion time is 150min;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, wherein the primary drying temperature of the surface A is 95 ℃, and the secondary drying temperature is 130 ℃; and the primary drying temperature of the surface B is 95 ℃, and the secondary drying temperature is 135 ℃ to obtain the porous electrode.
Setting the compaction density to 2.5g/cm 3 The pole pieces obtained in examples 1 to 4 and comparative example 1 were rolled and tested for porosity and liquid absorption, the results of which are given in the following table.
TABLE 1 determination of pole piece porosity and liquid uptake at lower compaction Density
Figure BDA0003814629610000061
Figure BDA0003814629610000071
Setting the compaction density to 4.2g/cm 3 The results of examples 5 to 8 and comparative example 2 were combinedThe pole pieces were rolled and tested for porosity and liquid absorption, with the results shown in the table below.
TABLE 2 measurement results of porosity and liquid absorption of pole pieces at higher compaction density
Group of Porosity of the pole piece% Liquid absorption amount/g
Example 5 21.9 2.5
Example 6 21.3 2.4
Example 7 19.5 2.1
Example 8 18.8 1.9
Comparative example 2 14.5 1.5
The result shows that the porosity of the pole piece can be improved by adding the pore-forming agent, the liquid retention amount is improved, the pole piece infiltration is facilitated, and the rate performance and the cycle life of the battery cell are favorably improved.
The method can obtain similar benefit effect when being applied to lithium manganate and ternary materials, and has the effect of improving the porosity and the liquid absorption amount of lithium manganate pole pieces and ternary material pole pieces.
The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical scheme according to the technical idea proposed by the present invention falls within the protection scope of the present invention; the technology not related to the invention can be realized by the prior art.

Claims (7)

1. A method for preparing a porous electrode by adopting gel-resistant anode slurry is characterized by comprising the following specific steps:
s1: mixing and stirring a positive electrode active material, a conductive agent and a binder; the positive active material is one of lithium iron phosphate, lithium cobaltate, lithium manganate and ternary materials;
s2: adding part of organic solvent into the S1 mixed material and stirring, wherein the solid content of the slurry is 70-75wt%;
s3: adding a pore-forming agent and the residual organic solvent, and stirring and dispersing, wherein the solid content of the slurry is 62-70wt%;
s4: the stirring dispersion rotating speed is increased;
s5: reversely rotating to remove bubbles, and pumping the slurry into a buffer tank to be slowly stirred and coated;
s6: coating the slurry on an aluminum foil, baking at 90-150 ℃, and cooling to obtain the porous electrode.
2. A method of preparing a porous electrode using a gel-resistant positive electrode slurry according to claim 1, wherein: the proportion of the positive active material, the conductive agent and the binder is 96-98: 1 to 2:1 to 2.
3. A method of preparing a porous electrode using a gel-resistant positive electrode slurry according to claim 1, wherein: the conductive agent is one or more of conductive carbon black, acetylene black, carbon nanotubes, graphene and Ketjen black.
4. A method of preparing a porous electrode using a gel-resistant positive electrode slurry according to claim 1, wherein: the binder is polyvinylidene fluoride; the organic solvent is N-methyl pyrrolidone.
5. A method of preparing a porous electrode using a gel-resistant positive electrode slurry according to claim 1, wherein: the pore-forming agent is one or more of glycolic acid, acetic acid, anhydrous oxalic acid and anhydrous citric acid, and the usage amount of the pore-forming agent is 0.5-2 percent of the total weight of the pole piece material.
6. A method of preparing a porous electrode using a gel-resistant positive electrode slurry according to claim 1, wherein: in the S1, the stirring revolution speed is 25-35rpm, the rotation speed is 500-800rpm, and the dispersion time is 30-60min; in the S2, the stirring revolution speed is 10-25rpm, the rotation speed is 100-200rpm, and the dispersion time is 20-45min; in the S3, the stirring revolution speed is 25-40rpm, the rotation speed is 500-800rpm, and the dispersion time is 40-60min; in the step S4, the stirring revolution speed is increased to 30-40rpm, the rotation speed is increased to 1500-1800rpm, and the dispersion time is 150-180min.
7. The method for preparing a porous electrode using the gel-resistant positive electrode slurry as set forth in claim 1, wherein: in the S6, the primary drying temperature of the surface A is 90-105 ℃, and the secondary drying temperature is 115-130 ℃; the primary drying temperature of the surface B is 90-105 ℃, and the secondary drying temperature is 125-150 ℃.
CN202211022633.3A 2022-08-25 2022-08-25 Gel-resistant anode slurry and preparation of porous electrode Pending CN115241409A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118522897A (en) * 2024-07-25 2024-08-20 江苏众钠能源科技有限公司 Positive electrode slurry, positive electrode plate, preparation method and application of positive electrode slurry and positive electrode plate

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118522897A (en) * 2024-07-25 2024-08-20 江苏众钠能源科技有限公司 Positive electrode slurry, positive electrode plate, preparation method and application of positive electrode slurry and positive electrode plate

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