CN113471627B - Modified diaphragm and preparation method and application thereof - Google Patents

Modified diaphragm and preparation method and application thereof Download PDF

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Publication number
CN113471627B
CN113471627B CN202110560062.8A CN202110560062A CN113471627B CN 113471627 B CN113471627 B CN 113471627B CN 202110560062 A CN202110560062 A CN 202110560062A CN 113471627 B CN113471627 B CN 113471627B
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manganese dioxide
modified
diaphragm
modified layer
coating
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CN113471627A (en
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余津福
符宽
黄继兵
谢才兴
甘婷
赵云龙
杨山
陈杰
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Huizhou Liwinon Energy Technology Co Ltd
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Huizhou Liwinon Energy Technology 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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
    • G01B11/0683—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating measurement during deposition or removal of the layer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
    • G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means
    • 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
    • H01M50/403—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
    • 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
    • H01M50/431—Inorganic material
    • 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
    • H01M50/443—Particulate material
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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 provides a modified diaphragm, a preparation method and application thereof, comprising a base film and a modified layer; the modified layer is coated on at least one surface of the base film; wherein the modified layer comprises a transparent modifier and manganese dioxide, and the content of the manganese dioxide is 0.5 mg/mL-5 mg/mL. Compared with the prior art, the modified diaphragm provided by the invention has the advantages that a certain amount of manganese dioxide is added, the color of the modified diaphragm is brown yellow, the brown manganese dioxide is mixed with the transparent modifier, the problem that the coating uniformity of the transparent modifier cannot be judged because the transparent modifier is strong in light transmittance and thin in coating layer can be effectively solved, and after the manganese dioxide is added, the CCD camera can detect the coating uniformity through the color difference, so that the problem that the coating uniformity of a modified layer is difficult to detect at present is solved.

Description

Modified diaphragm and preparation method and application thereof
Technical Field
The invention relates to the field of lithium batteries, in particular to a modified diaphragm and a preparation method and application thereof.
Background
In the construction of lithium batteries, the separator is one of the critical inner layer components. The performance of the diaphragm determines the interface structure, internal resistance and the like of the battery, directly influences the capacity, circulation, safety performance and other characteristics of the battery, and the diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery. The separator has the main function of separating the positive electrode from the negative electrode of the battery, preventing the two electrodes from being contacted and short-circuited, and also has the function of passing electrolyte ions. In the lithium battery system, since the electrolyte is an organic solvent system, a separator material resistant to an organic solvent is required, and a polyolefin porous film having a high strength and a thin film is generally used.
However, the existing polyolefin diaphragm has high crystallinity, low surface energy, small polarity, poor affinity with electrolyte, poor wettability and poor liquid retention, and poor contact with the surfaces of positive and negative plates, thus easily causing the increase of internal resistance of the lithium ion battery. Therefore, the membrane needs to be modified, and a layer of polymethyl methacrylate (PMMA) or polyvinylidene fluoride (PVDF) is coated on the surface of the polyolefin membrane by a plurality of factories so as to achieve the aim of improving the affinity of the polyolefin membrane and electrolyte and the interface adhesion of the polyolefin membrane and a pole piece. However, the existing PMMA or PVDF is coated with a thin layer, so that the existing detection means are difficult to monitor the uniformity of the coating and whether the coating is successful or not in the coating process.
In view of the foregoing, it is necessary to provide a solution to the above-mentioned problems.
Disclosure of Invention
One of the objects of the present invention is: the invention provides a modified diaphragm to solve the problem that whether the coating on the surface of the diaphragm is uniform cannot be judged at present, the modified diaphragm can be accurately characterized in terms of the uniformity of the coating on the surface of the diaphragm, and the affinity of the diaphragm to electrolyte can be increased.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a modified separator comprising:
a base film;
a modifying layer coated on at least one surface of the base film;
wherein the modified layer comprises a transparent modifier and manganese dioxide, and the content of the manganese dioxide is 0.5 mg/mL-5 mg/mL.
According to the modified diaphragm provided by the invention, a certain amount of manganese dioxide is added, the color of the modified diaphragm is brown yellow, the brown-yellow manganese dioxide is mixed with the transparent modifier, the problem that the coating uniformity of the transparent modifier cannot be judged because the transparent modifier is strong in light transmittance and thin in coating layer can be effectively solved, and after the manganese dioxide is added, the CCD camera can detect the coating uniformity through the color difference, so that the problem that the coating uniformity of a modified layer is difficult to detect at present is solved.
Among these, the crystal structure of manganese dioxide is generally divided into three categories: pore channel structure, layered structure, and spinel structure. The basic unit of manganese dioxide is [ MnO ] 6 ]The octahedron structure is formed by coordinating six oxygen atoms and one manganese atom, so that a hexagonal close-packed structure or a cubic close-packed structure is formed. Among them, the most common composition is [ MnO ] 6 ]The octahedron shares edges or apex angles with similar octahedrons, thereby forming a tunnel structure with gaps, and the complex and changeable combination mode not only can store various ions and compounds, but also can be used as a place for storing lithium ions. Therefore, the manganese dioxide and the transparent modifier are mixed, so that the affinity of the diaphragm to electrolyte can be effectively improved, and the liquid retention of the diaphragm can be improved.
Preferably, the manganese dioxide is prepared by a hydrothermal method, the reaction temperature is 100-180 ℃, and the reaction time is 5-20 h. More preferably, the reaction temperature may be 100 to 110 ℃, 110 to 120 ℃, 120 to 130 ℃, 130 to 140 ℃, 140 to 150 ℃, 150 to 160 ℃, or 170 to 180 ℃; the reaction time can be 5 to 6 hours, 6 to 8 hours, 8 to 10 hours, 10 to 12 hours, 12 to 14 hours, 14 to 16 hours or 16 to 20 hours. In the hydrothermal preparation, the temperature and time of the hydrothermal reaction have great influence on the morphology and particle size of manganese dioxide, and the excessively high reaction temperature accelerates the formation of the morphology of the manganese dioxide nano-sheet and shortens the reaction time, but is not beneficial to the control of the size of the manganese dioxide nano-sheet, so that manganese dioxide powder with large particle size and poor morphology uniformity is easily obtained. And at the excessively low reaction temperature, the formation of the morphology of the manganese dioxide nano-sheet is slow, the reaction time is long, and the purity of the obtained manganese dioxide is not high.
Preferably, the method for preparing the manganese dioxide by the hydrothermal method comprises the following steps:
dissolving manganese acetate in absolute ethyl alcohol, adding furfural, continuously stirring, transferring to a reaction kettle, heating at 100-180 ℃ for 5-20 h for reaction, cooling, centrifuging, washing and drying to obtain a carbon composite manganese oxide precursor;
annealing the obtained carbon composite manganese oxide precursor for 2-6 hours at 400-500 ℃ to obtain the platy manganese dioxide.
Preferably, the reaction temperature in the reaction kettle is 130-150 ℃ and the reaction time is 8-12 h. The inventor of the invention has found that, through a large number of experiments and repeated verification, the structure of the manganese dioxide layer can be slowly formed at the reaction temperature of 150 ℃, the manganese dioxide layer is basically molded for about 8 hours, the manganese dioxide powder with uniform morphology and particle size of about 20 μm can be prepared and obtained under the reaction condition, and the manganese dioxide powder and PMMA slurry can be mixed and coated on a base film more uniformly.
Preferably, the manganese dioxide may have a particle size of 1 to 5 μm, 5 to 10 μm, 10 to 15 μm, 15 to 20 μm, 20 to 25 μm, or 25 to 30 μm. Manganese dioxide of a suitable particle size is not only more advantageous for its mixing with PMMA syrup, but also for uniform coating on the base film after mixing of both.
The method for synthesizing manganese dioxide comprises a hydrothermal method, a sol-gel method, a solid-phase synthesis method, an electrochemical deposition method, a coprecipitation method and the like, but different preparation methods have great influence on the crystal form, the size, the morphology and the like of manganese dioxide, for example, manganese oxide can be obtained by using high-temperature carbonized manganate, but the purity of the oxide prepared by the method is low, the granularity is large, and the morphology uniformity is poor; in addition, even though the preparation method is the same, different reaction conditions can have great influence on the crystal form, size and morphology of manganese dioxide. The invention prepares manganese dioxide by adopting a hydrothermal method, and the manganese dioxide powder with high purity, good dispersibility, uniform morphology and proper particle size is obtained by regulating and controlling various reaction conditions such as temperature, time and the like, and the modified layer slurry obtained by mixing the manganese dioxide powder with the transparent modifier can be more uniformly coated on a base film, so that the coating uniformity of the transparent modifier is further ensured, and meanwhile, the coating uniformity of the transparent modifier is monitored in real time by adding the brown yellow manganese dioxide.
Preferably, the mass ratio of the transparent modifier to the manganese dioxide is (92-97): (1-8). More preferably, the mass ratio of the transparent modifier to the manganese dioxide may be 92:8, 93:7, 94:6, 95:5, 95.5:4.5, 96:4, or 97:3.
Wherein the transparent modifier is polymethyl methacrylate (PMMA) or polyvinylidene fluoride (PVDF). PMMA is the best polymer transparent material at present, the light transmittance can reach 92 percent, and is higher than that of glass, and when the PMMA is applied to a modified layer, the adhesive force between a diaphragm and a pole piece can be greatly increased, and the problem that the internal resistance of a lithium ion battery is easily increased due to the fact that the conventional polyolefin diaphragm is in poor contact with the surfaces of positive and negative pole pieces is solved. The mass ratio of PMMA to transparent modifier is set by combining the content of manganese dioxide, on one hand, the content of the PMMA to the transparent modifier cannot be too low to avoid the unobvious color characterization of the modified layer and the uniformity of the coating of the modified layer cannot be accurately characterized; on the other hand, the content of the polyolefin-based film cannot be too high, so that the blocking of holes of the polyolefin-based film caused by the too high content is avoided.
Preferably, the modified layer further comprises a dispersing auxiliary, and the mass ratio of the transparent modifier to the manganese dioxide to the dispersing auxiliary is (92-97): (1-5): (1-5). When PMMA and manganese dioxide are mixed, the dispersing auxiliary is added, so that the wettability of the slurry to the diaphragm and the viscosity of the slurry are increased, and the dispersion and subsequent coating of PMMA and manganese dioxide are facilitated. More preferably, the mass ratio of the transparent modifier, the manganese dioxide and the dispersing aid may be 92:3.5:4.5, 93:3:4, 94:2.5:3.5, 95.5:2:2.5, or 96:2:2.
Preferably, the dispersing aid includes carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyacrylic acid. Wherein the mass of CMC is 0.5-2 wt% of the mass of the dispersing auxiliary, the mass of PVA is 0.1-1 wt% of the mass of the dispersing auxiliary, and the mass of polyacrylic acid is 2-6 wt% of the mass of the dispersing auxiliary.
Preferably, the modified separator further comprises a ceramic layer coated between the base film and the modified layer. The ceramic layer comprises SiO 2 、Al2O 3 、TiO 2 By introducing the ceramic layer, the ceramic particles have excellent high temperature resistance and are very stable at 100-300 ℃, so that the thermal stability and mechanical property of the diaphragm can be effectively enhanced.
Preferably, the coating thickness of the modified layer is 0.1 μm to 3 μm. The modified layer is mainly used for improving the adhesion between the diaphragm and the pole piece, and the too thick coating layer easily causes the blockage of a porous structure of the base film so as to influence the transmission of lithium ions, and particularly, the diaphragm added with manganese dioxide is a substance which is not easy to coat, so that the coating thickness of the modified layer is controlled so as not to influence the performance of the lithium ion battery. More preferably, the coating thickness of the modified layer is 0.1 to 0.5 μm, 0.5 to 1 μm, 1 to 1.5 μm, 1.5 to 2 μm, 2 to 2.5 μm, or 2.5 to 3 μm.
The second object of the invention is to provide a method for preparing a modified diaphragm, comprising the following steps:
mixing manganese dioxide solution with a transparent modifier to obtain modified layer slurry; wherein the manganese dioxide content in the manganese dioxide solution is 0.5 mg/mL-5 mg/mL;
and coating the modified layer slurry on at least one surface of the base film, and drying to obtain the modified diaphragm.
Preferably, the preparation method comprises the following steps:
firstly mixing the manganese dioxide solution with a dispersing auxiliary, and then mixing the mixture with the transparent modifier to obtain modified layer slurry;
and coating the modified layer slurry on at least one surface of the base film, and drying to obtain the modified diaphragm.
It is a further object of the present invention to provide applications of the modified separator including, but not limited to, the following two:
1. a method for characterizing the coating uniformity of a diaphragm, wherein a CCD camera is used for detecting the modified diaphragm according to any one of the above, and the uniformity of the coating of a modified layer in the modified diaphragm is characterized by detecting the difference of colors.
2. A lithium ion battery comprises a positive plate, a negative plate and a diaphragm which is arranged between the positive plate and the negative plate, wherein the diaphragm is the modified diaphragm of any one of the above.
Compared with the prior art, the invention has the beneficial effects that:
1) According to the modified diaphragm provided by the invention, a certain amount of manganese dioxide is added, the color of the modified diaphragm is brown yellow, the brown-yellow manganese dioxide is mixed with the transparent modifier, the problem that the coating uniformity of the transparent modifier cannot be judged because the transparent modifier is strong in light transmittance and thin in coating layer can be effectively solved, and after the manganese dioxide is added, the CCD camera can detect the coating uniformity through the color difference, so that the problem that the coating uniformity of a modified layer is difficult to detect at present is solved.
Drawings
FIG. 1 is a schematic structural view of a modified separator of the present invention.
Fig. 2 is a contact angle of the modified separator of example 1 of the present invention with an electrolyte.
Fig. 3 is a contact angle of the separator of comparative example 2 of the present invention with an electrolyte.
FIG. 4 is a graph showing the comparison of the barrier liquid absorption rates of the barrier films of example 1 and comparative examples 1 to 2 of the present invention.
In the figure: 1-a base film; 2-modified layer.
Detailed Description
In order to make the technical scheme and advantages of the present invention more apparent, the present invention and its advantageous effects will be described in further detail below with reference to the detailed description and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
As shown in fig. 1, a modified separator includes a base film 1 and a modified layer 2; the modified layer 2 is coated on at least one surface of the base film 1; wherein the modified layer 2 comprises a transparent modifier and manganese dioxide, and the content of the manganese dioxide is 0.5 mg/mL-5 mg/mL.
Further, the manganese dioxide is prepared by a hydrothermal method, the reaction temperature is 100-180 ℃, and the reaction time is 5-20 h. More preferably, the reaction temperature may be 100 to 110 ℃, 110 to 120 ℃, 120 to 130 ℃, 130 to 140 ℃, 140 to 150 ℃, 150 to 160 ℃, or 170 to 180 ℃; the reaction time can be 5 to 6 hours, 6 to 8 hours, 8 to 10 hours, 10 to 12 hours, 12 to 14 hours, 14 to 16 hours or 16 to 20 hours. In the hydrothermal preparation, the temperature and time of the hydrothermal reaction have great influence on the morphology and particle size of manganese dioxide, and the excessively high reaction temperature accelerates the formation of the morphology of the manganese dioxide nano-sheet and shortens the reaction time, but is not beneficial to the control of the size of the manganese dioxide nano-sheet, so that manganese dioxide powder with large particle size and poor morphology uniformity is easily obtained. And at the excessively low reaction temperature, the formation of the morphology of the manganese dioxide nano-sheet is slow, the reaction time is long, and the purity of the obtained manganese dioxide is not high.
Further, the method for preparing the manganese dioxide by the hydrothermal method comprises the following steps:
dissolving manganese acetate in absolute ethyl alcohol, adding furfural, continuously stirring, transferring to a reaction kettle, heating at 100-180 ℃ for 5-20 h for reaction, cooling, centrifuging, washing and drying to obtain a carbon composite manganese oxide precursor;
annealing the obtained carbon composite manganese oxide precursor for 2-6 hours at 400-500 ℃ to obtain the platy manganese dioxide.
Further, the reaction temperature in the reaction kettle is 130-150 ℃ and the reaction time is 8-12 h. The inventors have found that the structure of the manganese dioxide layer can be formed slowly at a reaction temperature of 150 ℃ and is basically molded for about 8 hours to reach a stable state, and that manganese dioxide powder with a uniform morphology and a particle size of about 20 μm can be prepared under the reaction condition, and the manganese dioxide powder can be mixed with PMMA slurry to be coated on the base film 1 more uniformly.
Further, the manganese dioxide may have a particle size of 1 to 5 μm, 5 to 10 μm, 10 to 15 μm, 15 to 20 μm, 20 to 25 μm, or 25 to 30 μm. Manganese dioxide of suitable particle size not only facilitates its mixing with PMMA syrup but also facilitates uniform coating of both after mixing on the base film 1.
Specifically, the preparation method of the manganese dioxide in the embodiment comprises the following steps:
s1, dissolving 0.8653g of manganese acetate in 70mL of absolute ethyl alcohol, and stirring for 30min;
s2, adding 2g of furfural, continuously stirring for 1h, transferring to a 100mL polytetrafluoroethylene reaction kettle, and heating at 150 ℃ for 10h for reaction;
s3, cooling after the reaction is finished, centrifuging the product by adopting a high-speed centrifuge, washing the product by using ionized water and absolute ethyl alcohol to obtain a centrifugal solid product, drying the centrifugal solid product at 60 ℃ for 12 hours, and grinding the centrifugal solid product to obtain a carbon composite manganese oxide precursor;
and S4, placing the obtained carbon composite manganese oxide precursor in a muffle furnace, and annealing for 4 hours at 450 ℃, wherein the heating rate is 2 ℃ and min, so as to obtain the flaky manganese dioxide.
Further, the mass ratio of the transparent modifier to the manganese dioxide is (92-97): (1-8). More preferably, the mass ratio of the transparent modifier to the manganese dioxide may be 92:8, 93:7, 94:6, 95:5, 95.5:4.5, 96:4, or 97:3.
Wherein the transparent modifier is polymethyl methacrylate (PMMA) or polyvinylidene fluoride (PVDF). PMMA is the best polymer transparent material at present, the light transmittance can reach 92 percent, and is higher than that of glass, and when the PMMA is applied to the modified layer 2, the adhesive force between a diaphragm and a pole piece can be greatly increased, and the problem that the internal resistance of a lithium ion battery is easily increased due to the fact that the conventional polyolefin diaphragm is in poor contact with the surfaces of positive and negative pole pieces is solved. The mass ratio of PMMA to transparent modifier is set by combining the content of manganese dioxide, on one hand, the content of the PMMA to transparent modifier cannot be too low to avoid the unobvious color characterization of the modified layer 2, and the uniformity of the coating of the modified layer 2 cannot be accurately characterized; on the other hand, the content thereof should not be too high, so that clogging of the pores of the polyolefin-based film 1 due to excessive high content is avoided.
Further, the modified layer 2 further comprises a dispersing auxiliary, and the mass ratio of the transparent modifier to the manganese dioxide to the dispersing auxiliary is (92-97): (1-5): (1-5). When PMMA and manganese dioxide are mixed, the dispersing auxiliary is added, so that the wettability of the slurry to the diaphragm and the viscosity of the slurry are increased, and the dispersion and subsequent coating of PMMA and manganese dioxide are facilitated. More preferably, the mass ratio of the transparent modifier, the manganese dioxide and the dispersing aid may be 92:3.5:4.5, 93:3:4, 94:2.5:3.5, 95.5:2:2.5, or 96:2:2.
Further, the dispersing aid includes carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyacrylic acid. Wherein the mass of CMC is 0.5-2 wt% of the mass of the dispersing auxiliary, the mass of PVA is 0.1-1 wt% of the mass of the dispersing auxiliary, and the mass of polyacrylic acid is 2-6 wt% of the mass of the dispersing auxiliary.
Further, the modified separator further comprises a ceramic layer coated between the base film 1 and the modified layer 2. The ceramic layer comprises SiO 2 、Al2O 3 、TiO 2 By introducing the ceramic layer, the ceramic particles have excellent high temperature resistance and are very stable at 100-300 ℃, so that the thermal stability and mechanical property of the diaphragm can be effectively enhanced.
Further, the coating thickness of the modified layer 2 is 0.1 μm to 3 μm. The modified layer 2 is mainly used for improving the adhesion between the diaphragm and the pole piece, and an excessively thick coating layer easily causes the blockage of the porous structure of the base film 1 so as to influence the transmission of lithium ions, and particularly, the diaphragm added with manganese dioxide is a substance which is particularly easy to form a film, so that the coating thickness of the modified layer 2 is controlled so as not to influence the performance of the lithium ion battery. More preferably, the coating thickness of the modified layer 2 is 0.1 to 0.5 μm, 0.5 to 1 μm, 1 to 1.5 μm, 1.5 to 2 μm, 2 to 2.5 μm, or 2.5 to 3 μm. The control of the coating thickness of the modified layer 2 is also related to the total solid content, and according to the current coating technology, the total solid content can be designed to be 3-10%, and the solid content range can control the coating thickness more flexibly, for example, the solid content is too low or too high, which can cause the difficult control of the coating thickness and the uneven coating.
The preparation method of the modified diaphragm comprises the following steps:
mixing manganese dioxide solution with a transparent modifier to obtain modified layer 2 slurry; wherein the manganese dioxide content in the manganese dioxide solution is 0.5 mg/mL-5 mg/mL;
and coating the modified layer 2 slurry on at least one surface of the base film 1, and drying to obtain the modified diaphragm.
Further, the preparation method comprises the following steps:
firstly, mixing manganese dioxide solution with a dispersing auxiliary, and then mixing with a transparent modifier to obtain modified layer 2 slurry;
and (3) coating the modified layer 2 slurry on at least one surface of the base film 1, and drying to obtain the modified diaphragm.
Specific:
1. weighing 100mg of the obtained flaky manganese dioxide, adding 100mL of deionized water, and performing ultrasonic treatment for 3 hours by using a cell pulverizer to obtain a uniform manganese dioxide aqueous solution;
2. taking 2g of 2mg/mL manganese dioxide aqueous solution, adding 358.5g of deionized water, stirring at a high speed for 30min, and uniformly mixing to obtain solution A;
3. adding 2.5g of dispersing auxiliary into the solution A, wherein the adding aims to increase the wettability of the slurry to the diaphragm and increase the viscosity of the slurry, so that the dispersion and subsequent coating of PMMA-manganese dioxide are facilitated, and a solution B is obtained;
4. 637g PMMA mother liquor is added into the solution B, and high-speed stirring is carried out for 30min, thus obtaining MnO 2 -PMMA modified layer 2 paste;
5、MnO 2 carrying out gravure coating on the PMMA modified layer 2 slurry, wherein the coating thickness is about 0.5 um; and (3) preparing the modified diaphragm.
Example 2
A method for characterizing the coating uniformity of a diaphragm, the modified diaphragm described in example 1 is detected by using a CCD camera, and the coating uniformity of the modified layer 2 in the modified diaphragm is characterized by detecting the difference of colors.
Example 3
A lithium ion battery comprises a positive plate, a negative plate and a diaphragm which is arranged between the positive plate and the negative plate, wherein the diaphragm is the modified diaphragm in the embodiment 1.
Wherein the active material layer coated on the positive electrode sheet may be of the chemical formula such as Li a Ni x Co y M z O 2- b N b (wherein 0.95.ltoreq.a.ltoreq.1.2, x)>0, y is greater than or equal to 0, z is greater than or equal to 0, and x+y+z=1, 0 is greater than or equal to b is greater than or equal to 1, M is selected from a combination of one or more of Mn, al, N is selected from a combination of one or more of F, P, S), the positive electrode active material may also be a combination of one or more of compounds including but not limited to LiCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、Li 2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 And the like. The positive electrode active material may be further subjected to a modification treatment, and a method of modifying the positive electrode active material should be known to those skilled in the art, for example, the positive electrode active material may be modified by coating, doping, etc., and the material used for the modification treatment may be one or more combinations including but not limited to Al, B, P, zr, si, ti, ge, sn, mg, ce, W, etc.
The active material layer coated on the negative electrode sheet may be one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microsphere, silicon-based material, tin-based material, lithium titanate, or other metals capable of forming an alloy with lithium, etc. Wherein, the graphite can be selected from one or more of artificial graphite, natural graphite and modified graphite; the silicon-based material can be one or more selected from simple substance silicon, silicon oxygen compound, silicon carbon compound and silicon alloy; the tin-based material can be selected from one or more of elemental tin, tin oxide and tin alloy. The negative current collector is typically a structure or part that collects current, and may be any of a variety of materials suitable in the art for use as a negative current collector for a lithium ion battery, for example, the negative current collector may be a material including, but not limited to, a metal foil, etc., and more particularly may be a material including, but not limited to, a copper foil, etc.
The lithium ion battery also includes an electrolyte comprising an organic solvent, an electrolyte lithium salt, and an additive. Wherein the electrolyte lithium salt can be LiPF used in high-temperature electrolyte 6 And/or LiBOB; liBF used in the low-temperature electrolyte may be used 4 、LiBOB、LiPF 6 At least one of (a) and (b); liBF used in the overcharge-preventing electrolyte may also be used 4 、LiBOB、LiPF 6 At least one of LiTFSI; liClO may also be 4 、LiAsF 6 、LiCF 3 SO 3 、LiN(CF 3 SO 2 ) 2 At least one of them. And the organic solvent may be a cyclic carbonate, including PC, EC; chain carbonates, including DFC, DMC, or EMC; carboxylic esters, including MF, MA, EA, MP, and the like, are also contemplated. And additives include, but are not limited to, film forming additives, conductive additives, flame retardant additives, overcharge prevention additives, and control of H in electrolytes 2 At least one of an additive for O and HF content, an additive for improving low temperature performance, and a multifunctional additive.
Comparative example 1
A modified separator comprising a base film and a modifying layer; the modified layer is coated on at least one surface of the base film; wherein the modifying layer comprises a transparent modifier which is polymethyl methacrylate (PMMA).
Comparative example 2
The separator of this comparative example is a conventional polyolefin separator and does not include a modified layer.
Comparative example 3
A modified separator comprising a base film and a modifying layer; the modified layer is coated on at least one surface of the base film; wherein the modified layer comprises manganese dioxide, and the content of the manganese dioxide is 0.5 mg/mL-5 mg/mL.
Further, modified separators of examples 4 to 10 were prepared with reference to example 1 described above, and the reaction conditions of manganese dioxide are different from example 1, and specific conditions are shown in table 1.
TABLE 1
Figure BDA0003078605750000111
Figure BDA0003078605750000121
Performance tests, including tests of color, contact angle, and liquid absorption, were performed on the separators in examples 1, 4 to 10 and comparative examples 1 to 3 described above.
1) Color: the modified separator in comparative example 1 was almost the same in color as the separator in comparative example 2, and it could not be judged by naked eyes whether the base film was uniformly coated with the modified layer; the modified membrane in example 1 was pale brown yellow, and the naked eye could directly determine whether there was a uniform coating of the modified layer on the base membrane, and the color was detected by a CCD camera to characterize the uniformity of the coating in the modified layer.
2) Contact angle: as shown in fig. 2 to 3, the contact angle of the separator in comparative example 2 was 128 °, whereas the contact angle of the modified separator in example 1 of the present invention was 48 °. Therefore, the contact angle of the conventional diaphragm is 128 degrees, and the conventional diaphragm is not wetted, and compared with the conventional diaphragm or the modified diaphragm without the manganese dioxide, the contact angle of the conventional diaphragm and electrolyte is reduced, which indicates that the transparent modifier coating with single liquid absorption rate is better due to the addition of the manganese dioxide, and the affinity between the diaphragm and the electrolyte is increased.
3) Liquid absorption rate: as shown in fig. 4 and table 2 below, the modified separator of the present invention had an increase in liquid absorption compared to either the conventional separator or the conventional modified separator, which was also consistent with the previous contact angle test results. However, it can be seen from the comparison of examples 1 and 4 to 10 that a preferable membrane liquid absorption rate can be obtained by controlling the reaction conditions of manganese dioxide. The method is mainly characterized in that the reaction condition of manganese dioxide has a great influence on the morphology of the prepared manganese dioxide, and the conditions provided by the invention can obtain manganese dioxide powder with high purity, good dispersibility, uniform morphology and proper particle size, so that the manganese dioxide powder can be better mixed with PMMA to be more uniformly coated on a base film, and the liquid absorption rate of the diaphragm is further effectively improved.
Table 2 test results for modified separator
Figure BDA0003078605750000122
Figure BDA0003078605750000131
Therefore, the modified diaphragm solves the problem that whether the coating on the surface of the diaphragm is uniformly coated or not can not be judged at present, the coating uniformity of the surface coating of the modified diaphragm can be accurately represented, the affinity of the diaphragm to electrolyte can be increased, and the performance of a lithium ion battery is improved.
Variations and modifications of the above embodiments will occur to those skilled in the art to which the invention pertains from the foregoing disclosure and teachings. Therefore, the present invention is not limited to the above-described embodiments, but is intended to be capable of modification, substitution or variation in light thereof, which will be apparent to those skilled in the art in light of the present teachings. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present invention in any way.

Claims (7)

1. A modified separator, comprising:
a base film;
the modified layer is coated on at least one surface of the base film by modified layer slurry and is obtained by drying; wherein the modified layer slurry comprises a transparent modifier and a manganese dioxide solution, and the manganese dioxide content in the manganese dioxide solution is 0.5 mg/mL-5 mg/mL;
the method for preparing the manganese dioxide by adopting the hydrothermal method comprises the following steps: dissolving manganese acetate in absolute ethyl alcohol, adding furfural, continuously stirring, transferring to a reaction kettle, heating at 130-150 ℃ for 8-12 h for reaction, cooling, centrifuging, washing and drying to obtain a carbon composite manganese oxide precursor; annealing the obtained carbon composite manganese oxide precursor for 2-6 hours at 400-500 ℃ to obtain flaky manganese dioxide;
wherein the coating thickness of the modified layer is 0.1-3 mu m;
wherein the transparent modifier is polymethyl methacrylate or polyvinylidene fluoride;
wherein the mass ratio of the transparent modifier to the manganese dioxide is 92-97: 1 to 8.
2. The modified membrane of claim 1, wherein the manganese dioxide has a particle size of 1 to 30 μm.
3. The modified separator of claim 1, wherein the modified layer further comprises a dispersion aid, the mass ratio of the transparent modifier, the manganese dioxide, and the dispersion aid being (92-97): (1-5): (1-5).
4. The modified membrane of claim 1, further comprising a ceramic layer coated between the base membrane and the modified layer.
5. A method for producing the modified separator according to any one of claims 1 to 4, comprising the steps of: mixing manganese dioxide solution with a transparent modifier to obtain modified layer slurry; wherein the manganese dioxide content in the manganese dioxide solution is 0.5 mg/mL-5 mg/mL; and coating the modified layer slurry on at least one surface of the base film, and drying to obtain the modified diaphragm.
6. A method for characterizing the uniformity of coating of a diaphragm, characterized in that the modified diaphragm according to any one of claims 1 to 4 is detected by a CCD camera, and the uniformity of coating of a modified layer in the modified diaphragm is characterized by detecting the difference in color.
7. A lithium ion battery comprising a positive electrode sheet, a negative electrode sheet and a separator interposed between the positive electrode sheet and the negative electrode sheet, wherein the separator is the modified separator of any one of claims 1 to 4.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101759232A (en) * 2010-01-12 2010-06-30 浙江大学 Porous manganese dioxide of nanofibre texture and preparation method thereof
CN103172119A (en) * 2013-04-17 2013-06-26 湖南化工研究院 Preparation method of layered chemical manganese dioxide
CN103618053A (en) * 2013-11-08 2014-03-05 青岛中科华联新材料有限公司 Novel coloring diaphragm of lithium ion battery and preparation process of novel coloring diaphragm
CN109959781A (en) * 2019-03-20 2019-07-02 浙江大学 Based on manganese dioxide nano-plates oxalic acid detection kit and its application
WO2020085859A1 (en) * 2018-10-26 2020-04-30 주식회사 엘지화학 Functional separator, manufacturing method therefor, and lithium secondary battery comprising same

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08268779A (en) * 1995-03-29 1996-10-15 Kyocera Corp Translucent ceramic member
CA2574435C (en) * 1999-10-01 2009-03-24 Ppg Industries Ohio, Inc. Coating with optical taggent
JP5756525B2 (en) * 2010-12-20 2015-07-29 ▲海▼洋王照明科技股▲ふん▼有限公司 Manufacturing method and use of manganese dioxide nanorods
CN103618071A (en) * 2013-11-14 2014-03-05 中国科学院广州能源研究所 Carbon-silicon composite negative electrode material of lithium ion battery and preparation method thereof
CN105000598B (en) * 2015-05-08 2017-01-18 青岛科技大学 Method for preparing manganese carbonate hollow spheres
CN106082345A (en) * 2016-06-14 2016-11-09 中山大学 A kind of preparation method of nano-manganese dioxide line
CN106848156A (en) * 2017-03-07 2017-06-13 南京航空航天大学 Lithium-sulfur cell diaphragm material and its application
CN106971856B (en) * 2017-05-05 2019-01-08 商洛学院 A kind of preparation method of carbon coating amorphous nickel cobalt oxide nano-sheet electrode material
CN109285985A (en) * 2017-07-20 2019-01-29 天津凯普瑞特新能源科技有限公司 A kind of PVDP lithium battery diaphragm
CN108258334B (en) * 2018-01-19 2020-11-24 北京大学深圳研究生院 Composite flexible electrode, preparation method and application thereof
CN108711603A (en) * 2018-04-27 2018-10-26 青岛蓝科途膜材料有限公司 Coloured ceramic coated film of a kind of aramid fiber polymeric compound coating and preparation method thereof
CN111540868A (en) * 2020-01-21 2020-08-14 武汉船用电力推进装置研究所（中国船舶重工集团公司第七一二研究所） Preparation method and application of two-dimensional manganese dioxide modified polypropylene diaphragm
CN112551590B (en) * 2021-01-21 2022-04-01 福州大学 Synthesis of porous manganese dioxide and desulfurization application thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101759232A (en) * 2010-01-12 2010-06-30 浙江大学 Porous manganese dioxide of nanofibre texture and preparation method thereof
CN103172119A (en) * 2013-04-17 2013-06-26 湖南化工研究院 Preparation method of layered chemical manganese dioxide
CN103618053A (en) * 2013-11-08 2014-03-05 青岛中科华联新材料有限公司 Novel coloring diaphragm of lithium ion battery and preparation process of novel coloring diaphragm
WO2020085859A1 (en) * 2018-10-26 2020-04-30 주식회사 엘지화학 Functional separator, manufacturing method therefor, and lithium secondary battery comprising same
CN109959781A (en) * 2019-03-20 2019-07-02 浙江大学 Based on manganese dioxide nano-plates oxalic acid detection kit and its application

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