CN113594626A - Preparation method of battery composite diaphragm for lithium ion battery - Google Patents

Preparation method of battery composite diaphragm for lithium ion battery Download PDF

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CN113594626A
CN113594626A CN202110870504.9A CN202110870504A CN113594626A CN 113594626 A CN113594626 A CN 113594626A CN 202110870504 A CN202110870504 A CN 202110870504A CN 113594626 A CN113594626 A CN 113594626A
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hours
solution
stirring
drying
electrophoresis
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付绍永
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Guangdong Haiyue New Material Co ltd
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Guangdong Haiyue New Material 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/426—Fluorocarbon 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

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
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  • Materials Engineering (AREA)
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Abstract

The invention discloses a preparation method of a battery composite diaphragm for a lithium ion battery, which comprises the steps of adding diatomite into a sulfuric acid solution, stirring for 20-30 hours at normal temperature, filtering, washing to be neutral by using deionized water in a centrifugal mode, drying for 25-35 hours in a freeze dryer, adding the diatomite obtained in the step S1 into a lithium hydroxide solution, stirring for 20-30 hours at normal temperature, washing to be neutral by using deionized water in a centrifugal mode, drying for 20-25 hours in a freeze mode, performing ball milling for 6-10 hours by using a ball mill, drying at 80-90 ℃, adding a polyvinylidene fluoride-tetrafluoroethylene copolymer into an acetone solution, heating to 45-60 ℃, stirring to be transparent, continuously heating to 85-90 ℃, stirring for 3-6 hours, adding a product obtained in the step S2, and stirring to be uniform; washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode sheets with an electrophoresis apparatus, carrying out electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material.

Description

Preparation method of battery composite diaphragm for lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion battery diaphragms, and particularly relates to a preparation method of a battery composite diaphragm for a lithium ion battery.
Background
The separator is an important component of the lithium ion battery, and directly influences the performance of the battery. The polyolefin diaphragm has the defects of low porosity, poor thermal stability, poor wettability and the like due to the characteristics and the manufacturing process, so that the further application of commercial diaphragms is limited, and the realization of the diaphragm with a large number of lithium ion transmission channels is the key point for developing long-life and large-capacity batteries. In order to solve the disadvantages of the commercial separator, polyvinylidene fluoride-hexafluoropropylene materials have been widely studied because crystalline VDF units and amorphous HFP units thereof can exhibit excellent chemical stability and wettability. The traditional film making process such as wet method and dry method only carries out one-way stretching, the prepared diaphragm has a slit-shaped microporous structure, the transverse strength of the diaphragm is poor, and the problems of pressure loss or lithium dendrite puncture and the like are easy to occur in the preparation and use of the battery to cause the short circuit of the battery. Similarly, the PVDF-HFP separator cannot support stable operation of the battery due to strength variation of the PVDF-HFP separator at the interface between the separator and the electrode, and development of the PVDF-HFP separator is hindered by the mechanical strength difference between the PVDF-HFP separator and the lithium anode and formation of LiF. Therefore, the PVDF-HFP diaphragm needs to be further applied after being modified, the diaphragm modification method is more, common methods such as manufacturing a double-layer or multi-layer diaphragm, introducing an additive to prepare a composite diaphragm and the like, wherein a ceramic material is used as the additive to prepare the polymer composite diaphragm, so that the diaphragm can obtain excellent thermal stability and good wettability to an electrolyte, and in addition, the resistance of the polymer diaphragm to lithium dendrites is enhanced due to the addition of the ceramic material, and the short-circuit risk of the diaphragm is greatly reduced.
Disclosure of Invention
The invention aims to provide a preparation method of a battery composite diaphragm for a lithium ion battery, which comprises the following steps:
s1: adding diatomite into a sulfuric acid solution, stirring for 20-30 h at normal temperature, filtering, washing to be neutral by using deionized water centrifugation, and drying for 25-35 h in a freeze dryer for later use.
S2: and (4) adding the diatomite obtained in the step (S1) into a lithium hydroxide solution, stirring at normal temperature for 20-30 hours, then carrying out centrifugal washing by using deionized water until the solution is neutral, carrying out freeze drying for 20-25 hours, then carrying out ball milling for 6-10 hours by using a ball mill, and then drying at 80-90 ℃ for later use.
S3: adding the polyvinylidene fluoride-tetrafluoroethylene copolymer into an acetone solution, heating to 45-60 ℃, stirring until the mixture is transparent, then continuously heating to 85-90 ℃, stirring for 3-6 hours, adding the product obtained in the step S2, and stirring until the mixture is uniform.
S4: and washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode plates with an electrophoresis apparatus, performing electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material.
Preferably, the concentration of the sulfuric acid solution in the step S1 is 1-1.2 mol/L.
Preferably, the mass ratio of the diatomite to the sulfuric acid solution in the step S1 is (1-1.6): (6.5-12.5).
Preferably, the concentration of the lithium hydroxide solution in the step S2 is 1.5-2 mol/L.
Preferably, the mass ratio of the diatomite to the lithium hydroxide solution in the step S2 is (1-1.5): (5.5-8.5).
Preferably, the mass ratio of the polyvinylidene fluoride-tetrafluoroethylene copolymer in the step S3, the acetone and the product obtained in the step S2 is (1-2): (8-15): (0.16-0.35).
Preferably, the voltage for electrophoresis in step S4 is 72-76V, and the electrophoresis time is 60-80S.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the prepared lithium ion battery diaphragm material realizes rapid transfer of lithium ions, eliminates lithium dendrite generated by uncontrolled lithium ion deposition in the de-intercalation/de-intercalation process, and simultaneously the composite diaphragm also shows excellent thermal stability and thermal shrinkage performance.
Drawings
FIG. 1 is an SEM image of a separator material prepared in example 1 of the present invention;
Detailed Description
The following embodiments of the present invention are described in detail, and the embodiments are implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, it should be noted that, for those skilled in the art, a plurality of modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Example 1
A preparation method of a battery composite diaphragm for a lithium ion battery specifically comprises the following steps:
s1: adding diatomite into a sulfuric acid solution with the concentration of 1mol/L, stirring for 20 hours at normal temperature, filtering, washing to be neutral by using deionized water centrifugation, and drying for 25 hours in a freeze dryer for later use; wherein the mass ratio of the diatomite to the sulfuric acid solution is 1: 6.5.
S2: adding the diatomite obtained in the step S1 into a lithium hydroxide solution with the concentration of 1.5mol/L, stirring at normal temperature for 20 hours, then using deionized water to centrifugally wash the solution to be neutral, freeze-drying the solution for 20 hours, then using a ball mill to ball-mill the solution for 6 hours, and then drying the ball-milled solution at 80 ℃ for later use; wherein the mass ratio of the diatomite to the lithium hydroxide solution in the step S2 is 1: 5.5.
s3: adding the polyvinylidene fluoride-tetrafluoroethylene copolymer into the acetone solution, heating to 45 ℃, stirring until the mixture is transparent, then continuously heating to 85 ℃, stirring for 3 hours, adding the product obtained in the step S2, and stirring until the mixture is uniform; wherein the mass ratio of the polyvinylidene fluoride-tetrafluoroethylene copolymer to the acetone to the product obtained in the step S2 is 1:8: 0.16.
S4: washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode sheets with an electrophoresis apparatus, carrying out electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material; the voltage for electrophoresis is 72V, and the electrophoresis time is 60 s.
Example 2
A preparation method of a battery composite diaphragm for a lithium ion battery specifically comprises the following steps:
s1: adding diatomite into a sulfuric acid solution with the concentration of 1.2mol/L, stirring for 30 hours at normal temperature, filtering, washing to be neutral by using deionized water centrifugation, and drying for 35 hours in a freeze dryer for later use; wherein the mass ratio of the diatomite to the sulfuric acid solution is 1.6: 12.5.
S2: adding the diatomite obtained in the step S1 into a lithium hydroxide solution with the concentration of 2mol/L, stirring at normal temperature for 30h, then using deionized water to centrifugally wash the solution to be neutral, freeze-drying the solution for 25h, then using a ball mill to ball-mill the solution for 10h, and then drying the ball-milled solution at 90 ℃ for later use; wherein the mass ratio of the diatomite to the lithium hydroxide solution in the step S2 is 1.5: 8.5.
s3: adding the polyvinylidene fluoride-tetrafluoroethylene copolymer into an acetone solution, heating to 60 ℃, stirring until the mixture is transparent, then continuously heating to 90 ℃, stirring for 6 hours, adding the product obtained in the step S2, and stirring until the mixture is uniform; wherein the mass ratio of the polyvinylidene fluoride-tetrafluoroethylene copolymer to the acetone to the product obtained in the step S2 is 2:15: 0.35.
S4: washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode sheets with an electrophoresis apparatus, carrying out electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material; the electrophoresis voltage is 76V, and the electrophoresis time is 80 s.
Example 3
A preparation method of a battery composite diaphragm for a lithium ion battery specifically comprises the following steps:
s1: adding diatomite into a sulfuric acid solution with the concentration of 1.1mol/L, stirring for 25 hours at normal temperature, filtering, washing to be neutral by using deionized water centrifugation, and drying for 30 hours in a freeze dryer for later use; wherein the mass ratio of the diatomite to the sulfuric acid solution is 1.2: 8.6.
S2: adding the diatomite obtained in the step S1 into a lithium hydroxide solution with the concentration of 1.7mol/L, stirring at normal temperature for 25 hours, then using deionized water to centrifugally wash the solution to be neutral, freeze-drying the solution for 22 hours, then using a ball mill to ball-mill the solution for 8 hours, and then drying the ball-milled solution at 85 ℃ for later use; wherein the mass ratio of the diatomite to the lithium hydroxide solution in the step S2 is 1.2: 6.4.
s3: adding the polyvinylidene fluoride-tetrafluoroethylene copolymer into an acetone solution, heating to 50 ℃, stirring until the mixture is transparent, then continuously heating to 87 ℃, stirring for 4 hours, adding the product obtained in the step S2, and stirring until the mixture is uniform; wherein the mass ratio of the polyvinylidene fluoride-tetrafluoroethylene copolymer to the acetone to the product obtained in the step S2 is 1.4:10: 0.22.
S4: washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode sheets with an electrophoresis apparatus, carrying out electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material; the voltage for electrophoresis was 74V, and the electrophoresis time was 68 s.
Example 4
A preparation method of a battery composite diaphragm for a lithium ion battery specifically comprises the following steps:
s1: adding diatomite into a sulfuric acid solution with the concentration of 1.2mol/L, stirring for 28h at normal temperature, filtering, washing to be neutral by using deionized water centrifugation, and drying for 32h in a freeze dryer for later use; wherein the mass ratio of the diatomite to the sulfuric acid solution is 1.4: 10.8.
S2: adding the diatomite obtained in the step S1 into a lithium hydroxide solution with the concentration of 1.8mol/L, stirring at normal temperature for 28 hours, then using deionized water to centrifugally wash the solution to be neutral, freeze-drying the solution for 24 hours, then using a ball mill to ball-mill the solution for 9 hours, and then drying the ball-milled solution at 88 ℃ for later use; wherein the mass ratio of the diatomite to the lithium hydroxide solution in the step S2 is 1.4: 8.2.
s3: adding the polyvinylidene fluoride-tetrafluoroethylene copolymer into an acetone solution, heating to 55 ℃, stirring until the mixture is transparent, then continuously heating to 88 ℃, stirring for 5 hours, adding the product obtained in the step S2, and stirring until the mixture is uniform; wherein the mass ratio of the polyvinylidene fluoride-tetrafluoroethylene copolymer to the acetone to the product obtained in the step S2 is 1.8:13: 0.32.
S4: washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode sheets with an electrophoresis apparatus, carrying out electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material; the electrophoresis voltage is 75V, and the electrophoresis time is 75 s.
Examples of the experiments
Testing the transverse and longitudinal tensile strength and elongation of the diaphragm material prepared in the embodiment 1-4 by using a GH-949C tensile testing machine; the Theta Lite contact angle measuring instrument is used, the state of the liquid drop is intercepted after the liquid drop falls for t 2s, and the contact angle is calculated; the liquid absorption rate can be measured by calculating the formula W ═ W0-W1)/W0% of the total amount of the components in the composition, wherein W% is the liquid absorption rate of the separator, W0Is the initial mass of the diaphragm, W1The soaking time of the diaphragm is 6 hours for the quality of the diaphragm soaked in the electrolyte, the diaphragm is placed on filter paper after being taken out to absorb the electrolyte with surplus surface and then weighed, the test results are shown in table 1,
table 1. test results:
Figure BDA0003188730930000051
as can be seen from Table 1, the separator materials prepared in examples 1-4 have good tensile strength and elongation, and also have excellent liquid absorption.

Claims (6)

1. A preparation method of a battery composite diaphragm for a lithium ion battery is characterized by comprising the following steps:
s1: adding diatomite into a sulfuric acid solution, stirring for 20-30 h at normal temperature, filtering, washing to be neutral by using deionized water centrifugation, and drying for 25-35 h in a freeze dryer for later use;
s2: adding the diatomite obtained in the step S1 into a lithium hydroxide solution, stirring at normal temperature for 20-30 hours, then using deionized water to carry out centrifugal washing until the solution is neutral, carrying out freeze drying for 20-25 hours, then using a ball mill to carry out ball milling for 6-10 hours, and then drying at 80-90 ℃ for later use;
s3: adding the polyvinylidene fluoride-tetrafluoroethylene copolymer into an acetone solution, heating to 45-60 ℃, stirring until the mixture is transparent, then continuously heating to 85-90 ℃, stirring for 3-6 hours, adding the product obtained in the step S2, and stirring uniformly;
s4: and washing the copper sheet and the graphite sheet by using an absolute ethyl alcohol solution, vertically inserting the washed copper sheet and the graphite sheet into the transparent solution in the step S3, correspondingly connecting the two electrode plates with an electrophoresis apparatus, performing electrophoresis, drying the copper sheet substrate at room temperature after the electrophoresis is finished, and uncovering the film to obtain the diaphragm material.
2. The method for preparing the battery composite separator for the lithium ion battery according to claim 1, wherein the concentration of the sulfuric acid solution in the step S1 is 1-1.2 mol/L.
3. The method of claim 1, wherein the mass ratio of the diatomite to the sulfuric acid solution in step S1 is (1-1.6): (6.5-12.5).
4. The method for preparing the battery composite separator for the lithium ion battery according to claim 1, wherein the mass ratio of the diatomite to the lithium hydroxide solution in the step S2 is (1-1.5): (5.5-8.5).
5. The method of claim 1, wherein the mass ratio of the polyvinylidene fluoride-tetrafluoroethylene copolymer in step S3, the acetone and the product obtained in step S2 is (1-2): (8-15): (0.16-0.35).
6. The method for preparing the battery composite membrane for the lithium ion battery according to claim 1, wherein the voltage of electrophoresis in the step S4 is 72-76V, and the electrophoresis time is 60-80S.
CN202110870504.9A 2021-07-30 2021-07-30 Preparation method of battery composite diaphragm for lithium ion battery Withdrawn CN113594626A (en)

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