CN114039166A - Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery - Google Patents

Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery Download PDF

Info

Publication number
CN114039166A
CN114039166A CN202111319056.XA CN202111319056A CN114039166A CN 114039166 A CN114039166 A CN 114039166A CN 202111319056 A CN202111319056 A CN 202111319056A CN 114039166 A CN114039166 A CN 114039166A
Authority
CN
China
Prior art keywords
modified polymer
polymer wax
lithium ion
ion battery
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111319056.XA
Other languages
Chinese (zh)
Inventor
余康
方超
方园
郑君
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Xuran Electronic Co ltd
Original Assignee
Shenzhen Xuran Electronic Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Xuran Electronic Co ltd filed Critical Shenzhen Xuran Electronic Co ltd
Priority to CN202111319056.XA priority Critical patent/CN114039166A/en
Publication of CN114039166A publication Critical patent/CN114039166A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
  • Cell Separators (AREA)

Abstract

The application relates to the technical field of lithium ion battery processing, and particularly discloses a diaphragm for a lithium ion battery, a preparation method of the diaphragm and the lithium ion battery, wherein the diaphragm comprises a porous base material, an organic modified polymer wax coating and an inorganic ceramic coating; the raw material of the organic modified polymer wax coating is modified polymer wax emulsion, and the modified polymer wax emulsion is prepared from the following raw materials in terms of dry materials: modified polymer wax particles with the surfaces containing grafted modified polar functional groups, an aqueous solution type adhesive and an aqueous solution type macromolecular thickening agent; the raw material of the inorganic ceramic coating is ceramic slurry, and the ceramic slurry is prepared from the following raw materials in terms of dry materials: ceramic particles, a water-soluble polymer thickener, a water-soluble adhesive, and an emulsion-type binder. The diaphragm for the lithium ion battery not only keeps good lithium ion conductivity and wettability, but also has good thermal stability, so that the lithium ion battery has the advantages of good safety, discharge rate and long-term cycle stability.

Description

Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery
Technical Field
The application relates to the technical field of lithium ion battery processing, in particular to a diaphragm for a lithium ion battery, a preparation method of the diaphragm and the lithium ion battery.
Background
Since the commercial application of lithium ion batteries, lithium ion batteries have advantages of high energy density, high power density, high operating voltage, long cycle life, no memory effect, environmental protection, and convenience in flexibly designing the shape and size according to actual requirements, and are widely applied to power supplies of various consumer electronics products, electric tool products, and electric vehicles. With the development of green circular economy, the chemical energy storage field has good development prospect and promotes the rapid development of lithium ion batteries.
The lithium ion battery generally comprises a positive electrode material, a negative electrode material, a diaphragm and electrolyte, wherein the diaphragm is arranged between the positive electrode material and the negative electrode material, and the positive electrode material, the negative electrode material and the diaphragm are all immersed in the electrolyte. The diaphragm is a porous polymer film and is one of the most key main materials of the lithium ion battery, and the diaphragm has direct influence on the safety, discharge multiplying power and cyclicity of the lithium ion battery. The diaphragm is mainly used for isolating the anode material and the cathode material, electrons in the electrolyte cannot freely pass through the diaphragm, and the diaphragm plays a role in electronic insulation between the anode material and the cathode material; the diaphragm can also enable ions in the electrolyte to freely pass through, and a rapid ion transmission channel is provided between the anode material and the cathode material. Therefore, the performance of the diaphragm determines the interface structure, internal resistance and the like of the lithium ion battery, the capacity, the circulation and the safety performance of the lithium ion battery are directly influenced, and the diaphragm with excellent performance plays an important role in improving the comprehensive performance of the lithium ion battery.
Currently, in the existing lithium ion battery, a polyethylene or polypropylene polyolefin porous membrane is generally adopted as a separator, and the surface of the polyolefin porous membrane does not contain any polar chemical functional group, has very low surface energy and shows surface chemical inertness. When the polyolefin porous membrane is used in a lithium ion battery, the wettability of the polyolefin porous membrane to electrolyte is poor, a large amount of time is consumed to wait for the sufficient wetting of the electrolyte to the polyolefin porous membrane in a lithium ion battery assembly process, the conductivity of the polyolefin porous membrane to lithium ions is low, and the electrochemical impedance is high. In addition, the melting point of the polyolefin porous membrane is lower than 170 ℃, when the temperature of the lithium ion battery is increased due to internal or external factors, the polyolefin porous membrane may shrink or melt, and at this time, direct contact between the positive electrode material and the negative electrode material is caused, so that the lithium ion battery is short-circuited, and accidents such as combustion and explosion of the lithium ion battery are caused.
In order to improve the wettability and thermal stability of the polyolefin porous membrane to the electrolyte, in the related art, a porous active layer composed of inorganic ceramic particles and a polymer binder is generally coated on one side or both sides of the polyolefin porous membrane, the inorganic ceramic particles are attached to the surface of the polyolefin porous membrane through the polymer binder, and the wettability and thermal stability of the porous active layer are utilized to improve the wettability of the polyolefin porous membrane, inhibit the thermal shrinkage of the polyolefin porous membrane and improve the performance and safety of the lithium ion battery.
However, the interface bonding force between the inorganic ceramic particles and the polyolefin porous membrane in the porous active layer is weak, the inorganic ceramic particles are easy to fall off from the surface of the polyolefin porous membrane, the use effect of the inorganic ceramic particles is reduced, and when the temperature of the lithium ion battery is increased due to internal or external factors, the bonding force between the inorganic ceramic particles and the polyolefin porous membrane is not enough to resist the shrinkage stress generated when the polyolefin porous membrane is heated, so that the high temperature resistance of the inorganic ceramic particles reinforced polyolefin porous membrane is limited, and the polyolefin porous membrane has a shrinkage rate of more than 30% at 160 ℃. If the adhesion of the inorganic ceramic particles is to be improved, the addition amount of the polymer binder is generally increased, and the increase of the addition amount of the polymer binder reduces the conductivity of the polyolefin-based porous membrane to lithium ions, thereby affecting the exertion of the dynamic performance of the lithium ion battery. Therefore, there is an urgent need to develop a separator for a lithium ion battery, which can improve the thermal stability of the separator while maintaining good lithium ion conductivity and wettability, thereby improving the safety, discharge rate and long-term cycle stability of the lithium ion battery.
Disclosure of Invention
In order to improve the thermal stability of the diaphragm on the basis of keeping good lithium ion conductivity and wettability of the diaphragm, the application provides the diaphragm for the lithium ion battery, a preparation method of the diaphragm and the lithium ion battery.
In a first aspect, the present application provides a lithium ion battery separator, which adopts the following technical scheme:
a diaphragm for a lithium ion battery comprises a porous base material and an organic modified polymer wax coating fixedly arranged on one side or two sides of the porous base material, wherein an inorganic ceramic coating is fixedly arranged on the side surface of the organic modified polymer wax coating, which is far away from the porous base material;
the raw materials of the organic modified polymer wax coating are modified polymer wax emulsion, water is used as a dispersing solvent, the solid content of the modified polymer wax emulsion is 10-40wt%, and the modified polymer wax emulsion is prepared from the following raw materials in percentage by weight: 80-96% of modified polymer wax particles with surfaces containing grafted modified polar functional groups, 3-18% of aqueous solution type adhesive and 1-2% of aqueous solution type macromolecular thickening agent;
the inorganic ceramic coating is prepared from the following raw materials in percentage by weight, wherein the raw materials of the inorganic ceramic coating are ceramic slurry, water is used as a dispersing solvent, the solid content of the ceramic slurry is 30-45 wt%, and the ceramic slurry is prepared from the following raw materials in percentage by weight: 90-98.5% of ceramic particles, 0.5-4.5% of emulsion type binder, 0.5-4.5% of aqueous solution type binder and 0.5-1% of water-soluble polymer thickener.
By adopting the technical scheme, the diaphragm has good lithium ion conductivity and good wettability, the contact angle of the electrolyte is 35-37 degrees, the thermal stability of the diaphragm is improved, the thermal shrinkage rate of the diaphragm is below 20 percent at 160 ℃/30min, the shrinkage stress of the diaphragm at high temperature is effectively resisted, the safety and the service life of the lithium ion battery are improved, and in addition, the discharge multiplying power and the 1000-time cycle capacity retention rate of the lithium ion battery are also improved, so that the market demand is met.
The organic modified polymer wax coating and the inorganic ceramic coating are arranged on one side or two sides of the porous base material, the inorganic ceramic coating is used for increasing the thermal stability and the wettability of the porous base material, and the organic modified polymer wax coating is used for increasing the affinity of the diaphragm to electrolyte and the interfacial adhesion between the diaphragm and the inorganic ceramic coating. Because the addition amount of the polymer adhesive is not increased to improve the interfacial adhesion between the inorganic ceramic particles and the porous base material, the influence of the separator on the lithium ion conductivity caused by introducing excessive polymer adhesive is reduced.
The organic modified polymer wax coating and the inorganic ceramic coating are arranged on one side or both sides of the porous base material, so that the interface roughness is increased, and more mechanical anchoring effects can be generated; on the other hand, the surface of the organic modified polymer wax coating contains grafting modified polar functional groups, so that the surface chemical polarity of the porous base material is increased, and the interaction force among polar groups can be effectively improved; meanwhile, the organic modified polymer wax coating changes the contact interface of the inorganic ceramic coating and the porous base material, the adhesive force of the inorganic ceramic coating is greatly improved, a more stable interface bonding layer is constructed by mechanical anchoring, intermolecular acting force and hydrogen bond force which are generated among the organic modified polymer wax coating and the porous base material, the shrinkage stress of the diaphragm under the high-temperature condition can be resisted, the dimensional stability of the diaphragm under the high temperature is kept, the synergistic effect of the organic modified polymer wax coating and the inorganic ceramic coating is fully exerted, the practicability of the diaphragm is improved, and the use safety of the lithium ion battery is improved.
In the modified polymer wax emulsion, the surfaces of polymer wax particles contain graft-modified polar functional groups, and the polar functional groups can increase the hydrophilicity of the surfaces of the modified polymer wax particles and can be effectively and stably dispersed in water to form a modified polymer wax particle dispersion liquid. The modified polymer wax particle material has higher chemical and electrical stability, and the surface of the modified polymer wax particle material is grafted with modified polar functional groups, so that the modified polymer wax particle material has specific chemical activity, and the bonding strength of the organic modified polymer wax coating and the inorganic ceramic coating can be increased. The thermal stability of the diaphragm is improved by utilizing the synergistic effect between the organic modified polymer wax coating and the inorganic ceramic coating, and the practicability of the diaphragm is also improved.
Optionally, the organic modified polymer wax coating is obtained by drying and surface functional treatment after the modified polymer wax emulsion is coated on one side or both sides of the porous base material; the surface functional treatment is one of corona, plasma and ultraviolet irradiation.
By adopting the technical scheme, the hydrophilicity of the porous base material can be effectively increased by the organic modified polymer wax coating, but when the modified polymer wax emulsion is coated on the surface of the porous base material, the effective polar group content of the surface is limited.
At this time, in order to further improve the polar strength of the separator and increase the interfacial adhesion strength between the separator and the inorganic ceramic material, a surface function treatment is performed after the modified polymer wax emulsion is coated and dried, the surface function treatment is one of corona, plasma and ultraviolet irradiation, ions can be generated by air ionization in high-voltage discharge, the modified polymer wax particles are attacked under the action of a strong electric field, polymer molecules in the modified polymer wax particles are activated to increase the polarity, the surface roughness and the surface energy of the organic modified polymer wax coating are improved, and the number of polar functional groups and the reaction activity of the organic polymer wax coating are activated and improved.
Air ionization generates strong ozone oxidant, the strong ozone oxidant can oxidize polymer molecules to generate polar groups such as carbonyl and carboxyl, the surface energy of the organic modified polymer wax coating is improved, the wettability and the liquid retention of electrolyte are enhanced, and the lithium ion mobility is also improved. In addition, the interface adhesion with the inorganic ceramic coating is effectively improved through the enhancement of the surface polarity of the organic modified polymer wax coating.
Treat among this application behind the coating modified polymer wax emulsion, carry out surface function and handle, it carries out surface function to the porotic substrate among the prior art and handles then coat the thick liquids and carry out the contrast. In the present application, the surface of the porous substrate is coated with the modified polymer wax particles before the surface functional treatment. The modified polymer wax particles can protect the porous base material, and reduce the influence of the porous base material on the reduction of the insulation of the diaphragm caused by the structural defect of the weak area of the porous base material due to high-voltage discharge. In this application, kept the good electronic insulation characteristic of porous substrate itself, simultaneously, organic modified polymer wax coating has more efficient activation under the high strong electric field effect, has the advantage of protection porous substrate, still has the advantage that increases diaphragm infiltration nature, interfacial adhesion intensity.
Optionally, the modified polymer wax particles are one of modified polyethylene wax particles and modified polypropylene wax particles.
By adopting the technical scheme, the modified polymer wax particles are convenient to select, and when the porous base material is the polyethylene polyolefin porous membrane, the modified polyethylene wax particles are selected; when the porous base material is a polypropylene polyolefin porous membrane, the modified polypropylene wax particles are selected, so that the interface bonding strength of the organic modified polymer wax coating and the porous base material is effectively increased, and the safety of the diaphragm is improved.
Optionally, the modified polymer wax particle surface graft modified polar functional group includes one or more of amino, imino, carboxyl, hydroxyl and amino.
By adopting the technical scheme, the selection of the polar functional group for grafting modification on the surface of the modified polymer wax particle is facilitated, and the surface of the modified polymer wax particle contains amino, imino, carboxyl, hydroxyl and amino polar groups. The polar groups on the surfaces of the modified polymer wax particles are utilized to increase the interface bonding strength of the organic modified polymer wax coating, the inorganic ceramic coating and the porous base material, and improve the safety of the diaphragm.
Optionally, the modified polymeric wax particles have an average particle size of 0.1 to 10 μm and the ceramic particulate has an average particle size of 0.1 to 5.0 μm.
By adopting the technical scheme, the average particle size of the modified polymer wax particles is 0.1-10 μm, and the average particle size of the modified polymer wax particles is preferably 0.2-1.0 μm. When the particle size of the modified polymer wax particles is too small, tight particle packing and excessive use of an aqueous solution type adhesive are caused, and the air permeability of the separator and the electrochemical impedance inside the lithium ion battery are adversely affected; when the particle size of the modified polymer wax particles is too large, the thickness of the organic modified polymer wax coating is increased, and the energy density of the lithium ion battery is reduced. The granularity of the modified polymer wax particles is optimized, and the stability and the performance of the diaphragm are improved.
Further, the modified polymer wax particles have a weight average molecular weight of 2000-100000g/mol, preferably of 2000-50000g/mol, and when the molecular weight of the modified polymer wax particles is too small, the mechanical strength, chemical and thermal stability are poor; when the molecular weight of the modified polymer wax particles is too large, the crystallinity of the modified polymer wax particles is high, the chemical functional modification on the surface of the modified polymer wax particles is not facilitated, the molecular weight of the modified polymer wax particles is optimized, and the bonding strength and the stability of the organic modified polymer wax coating and the porous base material are improved.
The average particle size of the ceramic fine particles is 0.1 to 5.0. mu.m, and preferably the average particle size of the ceramic fine particles is 0.2 to 1.0. mu.m. The undersize of the ceramic particles can also cause close particle packing and excessive use of aqueous solution type adhesives and emulsion type adhesives, and agglomeration can also occur, and the dispersibility of the ceramic particles in the ceramic slurry is influenced; when the size of the ceramic particles is too large, the thickness of the inorganic ceramic coating layer may be increased, and deposition may occur due to the heavy weight of the ceramic particles, which may also affect the dispersibility of the ceramic particles in the ceramic slurry.
Optionally, the ceramic particles are one or more of alumina, boehmite, silica, zirconia, magnesia and titania.
By adopting the technical scheme, ceramic particles are convenient to select, and the surfaces of the alumina, the boehmite, the silica, the zirconia, the magnesia and the titania contain active groups, so that the effects of increasing the wettability and the thermal stability of the diaphragm can be achieved, and the inorganic ceramic coating and the organic modified polymer wax coating can keep good bonding strength. Experiments are selected in the range of alumina, boehmite, silica, zirconia, magnesia and titania, and the detection results of the contact angle of the electrolyte, the thermal shrinkage rate at 160 ℃/30min, the current discharge multiplying power and the battery cyclicity are basically not influenced.
Optionally, the aqueous solution type adhesive is one or more of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, calcium polyacrylate, polyvinyl alcohol and polyacrylamide;
the water solution type high molecular thickening agent is one or more of sodium carboxymethylcellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and sodium alginate;
the emulsion type binder is one or more of styrene-acrylic emulsion, butylbenzene emulsion, vinyl acetate copolymer emulsion and acrylate copolymer emulsion.
By adopting the technical scheme, the aqueous solution type adhesive is further optimized, the aqueous solution type adhesive is convenient to select, and the functional group of the aqueous solution type adhesive in the inorganic ceramic coating raw material is matched with the functional group in the organic modified polymer wax coating, so that the bonding strength of the inorganic ceramic coating and the organic modified polymer wax coating is effectively improved, and the practicability of the diaphragm is improved.
Furthermore, the weight average molecular weight of the aqueous solution type adhesive is 10000-200000g/mol, preferably 10000-100000g/mol, the adhesive effect of the aqueous solution type adhesive is influenced due to the fact that the molecular weight of the aqueous solution type adhesive is too low, the dispersibility of the aqueous solution type adhesive in the modified polymer wax emulsion or the ceramic slurry is influenced due to the fact that the molecular weight of the aqueous solution type adhesive is too high, the aqueous solution type adhesive is uniformly dispersed in the modified polymer wax emulsion or the ceramic slurry by limiting the weight average molecular weight of the aqueous solution type adhesive, the coating of the modified polymer wax emulsion or the ceramic slurry is facilitated, and the uniformity and the performance of the diaphragm are improved.
The viscosity of the modified polymer wax emulsion or the ceramic slurry can be effectively increased by the sodium carboxymethyl cellulose, the hydroxymethyl cellulose, the hydroxyethyl cellulose and the sodium alginate. And experiments are selected in the ranges of sodium carboxymethylcellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and sodium alginate, and the detection results of the contact angle of the electrolyte, the thermal shrinkage rate at 160 ℃/30min, the current discharge multiplying power and the battery cyclicity are basically not influenced.
The styrene-acrylic emulsion, the styrene-butadiene emulsion, the vinyl acetate copolymer emulsion and the acrylate copolymer emulsion can provide a good dispersion system for the ceramic particles, and the ceramic particles are uniformly dispersed in the ceramic slurry. Experiments are selected in the range of styrene-acrylic emulsion, styrene-butadiene emulsion, vinyl acetate copolymer emulsion and acrylate copolymer emulsion, and the detection results of the contact angle of the electrolyte, the thermal shrinkage rate at 160 ℃/30min, the current discharge multiplying power and the battery cyclicity are basically not influenced.
Optionally, the modified polymeric wax particles are prepared by the following method:
s1, stirring and uniformly mixing the polymer wax particles, epichlorohydrin and hydrochloric acid solution, heating to 55-65 ℃, carrying out heat preservation treatment for 0.5-1.5h, filtering, and drying to obtain chloro-esterified polymer wax particles;
s2, adding the chloro-esterified polymer wax particles obtained in the step S1 into 1, 4-dioxane, stirring for 1.5-2.5h, adding sodium hydroxide, tetrabutylammonium bromide and a polar group modifier, heating to 55-65 ℃, preserving heat for 4.5-5.5h, filtering, and drying to obtain modified polymer wax particles.
By adopting the technical scheme, firstly, epichlorohydrin is utilized to obtain chloridized polymer wax particles, and then a polar group modifier is utilized to obtain modified polymer wax particles with the surfaces containing grafting modified polar functional groups, so that the modified polymer wax particles have the advantages of mild and simple preparation conditions.
Optionally, the weight ratio of the polymer wax particles, the epichlorohydrin, the hydrochloric acid solution, the 1, 4-dioxane, the sodium hydroxide, the tetrabutylammonium bromide and the polar group modifier is (90-110): (450-; the concentration of the hydrochloric acid solution is 0.5-1.5 mol/L.
By adopting the technical scheme, the raw material proportion of the modified polymer wax particles is optimized, and the preparation of the modified polymer wax particles is facilitated.
In a second aspect, the present application provides a preparation method of the above lithium ion battery separator, which adopts the following technical scheme:
the preparation method of the diaphragm for the lithium ion battery comprises the following steps:
preparation of modified Polymer wax emulsions
Uniformly mixing the modified polymer wax particles with water to obtain a modified polymer wax aqueous dispersion liquid;
stirring and uniformly mixing the modified polymer wax aqueous dispersion liquid, the aqueous solution type adhesive and the aqueous solution type high-molecular thickening agent, and adding water to adjust the solid content to obtain a modified polymer wax emulsion;
preparation of ceramic slurry
Stirring and uniformly mixing ceramic particles, an aqueous solution type high-molecular thickening agent, an aqueous solution type adhesive and an emulsion type adhesive, and adding water to adjust the solid content to obtain ceramic slurry;
preparation of organically modified polymer wax coatings
Coating the modified polymer wax emulsion on one side or two sides of a porous base material, drying, then performing surface function treatment, and forming an organic modified polymer wax coating on the surface of the porous base material by the modified polymer wax emulsion to obtain the porous base material with the organic modified polymer wax coating;
preparation of inorganic ceramic coatings
And coating the ceramic slurry on the surface of the organic modified polymer wax coating after surface function treatment, drying, and forming an inorganic ceramic coating on the surface of the organic modified polymer wax coating by the ceramic slurry to obtain the diaphragm.
By adopting the technical scheme, the preparation of the diaphragm is simple, convenient and stable.
In a third aspect, the present application provides a lithium ion battery, which adopts the following technical scheme:
a lithium ion battery comprises a positive pole piece, a negative pole piece, a porous diaphragm arranged between the positive pole piece and the negative pole piece, and electrolyte, wherein the porous diaphragm is the diaphragm for the lithium ion battery.
By adopting the technical scheme, the diaphragm is convenient to use, the battery has good discharge rate and 1000-time circulation capacity retention rate, and the market demand is met.
In summary, the present application has the following beneficial effects:
1. the diaphragm for the lithium ion battery is provided with the organic modified polymer wax coating and the inorganic ceramic coating on one side or two sides of the porous base material, utilizes the synergistic interaction between the organic modified polymer wax coating and the inorganic ceramic coating, not only increases the interface bonding strength of the diaphragm, but also improves the thermal stability of the diaphragm, and simultaneously has good lithium ion conductivity and wettability, and ensures that the lithium ion battery has the advantages of good safety, discharge rate capability and long-term circulation stability.
2. After the organic modified polymer wax coating is coated with the modified polymer wax emulsion, drying and surface functional treatment are carried out. Carry out surface function to porous substrate among the prior art and handle then coat the thick liquids and contrast, the technical scheme of this application utilizes modified polymer wax granule to protect porous substrate, reduces the influence that surface function handles to cause structural defect to porous substrate. The surface function treatment is also utilized to increase the surface energy of the organic modified polymer wax coating, improve the wettability and the liquid retention of the diaphragm, facilitate the improvement of the conductivity of the lithium ion and the improvement of the discharge rate, increase the adhesive force of the inorganic ceramic coating, more effectively resist the shrinkage stress of the diaphragm at high temperature, reduce the shrinkage rate of the diaphragm at high temperature and improve the safety of the lithium ion battery.
3. The preparation method of the diaphragm for the lithium ion battery has the advantages of simplicity and convenience in preparation and stability; and the diaphragm for the lithium ion battery is used for the lithium ion battery, so that the diaphragm is convenient to use.
Detailed Description
The present application will be described in further detail with reference to examples.
Preparation example
Preparation example 1
The modified polyethylene wax particles are prepared by the following method:
s1, stirring and uniformly mixing 100g of polyethylene wax particles, 500g of epichlorohydrin and 5000g of 1mol/L hydrochloric acid solution, heating to 60 ℃, carrying out heat preservation treatment for 1h, filtering and drying to obtain the chlorinated polyethylene wax particles.
S2, adding the chloridized polyethylene wax particles obtained in the step S1 into 2000g of 1, 4-dioxane, stirring for 2 hours, then adding 300g of sodium hydroxide, 5g of tetrabutylammonium bromide and 1000g of 3-aminopiperidine, heating to 60 ℃, preserving heat for 5 hours, filtering and drying to obtain modified polyethylene wax particles, wherein the polar functional groups grafted and modified on the surfaces of the modified polyethylene wax particles mainly comprise amino groups.
The weight-average molecular weight of the modified polyethylene wax particles is 10000g/mol, and the average particle size is 0.5 mu m.
Preparation example 2
The functionalized polyethylene wax particles with the surfaces containing the grafting modified polar functional groups are prepared by the following method:
s1, stirring and uniformly mixing 90g of polyethylene wax particles, 450g of epichlorohydrin and 4500g of 0.5mol/L hydrochloric acid solution, heating to 55 ℃, carrying out heat preservation treatment for 1.5h, filtering, and drying to obtain the chlorinated polyethylene wax particles.
S2, adding the chlorinated polyethylene wax obtained in the step S1 into 1500g of 1, 4-dioxane, stirring for 1.5h, then adding 250g of sodium hydroxide, 4g of tetrabutylammonium bromide and 900g of 2-hydroxyethylamine, heating to 55 ℃, preserving heat for 5.5h, filtering and drying to obtain modified polyethylene wax particles, wherein the polar functional groups grafted and modified on the surfaces of the modified polyethylene wax particles mainly comprise hydroxyl groups.
The weight-average molecular weight of the modified polyethylene wax particles is 10000g/mol, and the average particle size is 0.5 mu m.
Preparation example 3
The functionalized polyethylene wax particles with the surfaces containing the grafting modified polar functional groups are prepared by the following method:
s1, stirring and uniformly mixing 110g of polyethylene wax, 550g of epichlorohydrin and 5500g of 1.5mol/L hydrochloric acid solution, heating to 65 ℃, carrying out heat preservation treatment for 0.5h, filtering, and drying to obtain the chlorinated polyethylene wax particles.
S2, adding the chlorinated polyethylene wax obtained in the step S1 into 2500g of 1, 4-dioxane, stirring for 2.5 hours, then adding 350g of sodium hydroxide, 6g of tetrabutylammonium bromide and 1100g of beta-alanine, heating to 65 ℃, preserving heat for 4.5 hours, filtering and drying to obtain modified polyethylene wax particles, wherein the polar functional groups grafted and modified on the surfaces of the modified polyethylene wax particles mainly comprise carboxyl.
The weight-average molecular weight of the modified polyethylene wax particles is 10000g/mol, and the average particle size is 0.5 mu m.
Preparation example 4
Modified polyethylene wax particles which are different from preparation example 1 in that the average particle size of the modified polymer wax particles is 0.2 μm, and the rest is the same as preparation example 1.
Preparation example 5
Modified polyethylene wax particles which are different from preparation example 1 in that the average particle size of the modified polymer wax particles is 0.6. mu.m, and the rest is the same as preparation example 1.
Examples
Example 1
A diaphragm for a lithium ion battery comprises a porous base material and organic modified polymer wax coatings fixedly arranged on both sides of the porous base material, wherein inorganic ceramic coatings are fixedly arranged on the side surfaces, far away from the porous base material, of the organic modified polymer wax coatings, namely the inorganic ceramic coatings are two in number and are positioned on both sides of the porous base material.
A preparation method of a diaphragm for a lithium ion battery comprises the following steps:
preparation of modified Polymer wax emulsions
Uniformly mixing the modified polymer wax particles with water to obtain a modified polymer wax aqueous dispersion liquid;
stirring and uniformly mixing the modified polymer wax aqueous dispersion liquid, the aqueous solution type adhesive and the aqueous solution type high-molecular thickening agent, and adding water to adjust the solid content to obtain the modified polymer wax emulsion.
The modified polymer wax emulsion takes water as a dispersing solvent, the solid content of the modified polymer wax emulsion is 30 wt%, and the raw materials of the modified polymer wax emulsion comprise 92 wt% of modified polymer wax particles with surfaces containing grafted modified polar functional groups, 7 wt% of aqueous solution type adhesive and 1 wt% of aqueous solution type macromolecular thickening agent in terms of dry material weight percentage;
the modified polymer wax particles are modified polyethylene wax particles and are prepared by adopting preparation example 1, and the polar functional groups grafted and modified on the surfaces of the modified polyethylene wax particles are mainly amino; the aqueous solution type adhesive is polyacrylic acid, and the weight-average molecular weight of the polyacrylic acid is 20000 g/mol; the water solution type high molecular thickening agent is sodium carboxymethyl cellulose.
Preparation of ceramic slurry
The ceramic particles, the water solution type high molecular thickening agent, the water solution type adhesive and the emulsion type adhesive are stirred and mixed uniformly, and water is added to adjust the solid content, so that the ceramic slurry is obtained.
The ceramic slurry takes water as a dispersing solvent, the solid content of the ceramic slurry is 40wt%, and the raw materials of the ceramic slurry comprise 96 wt% of ceramic particles, 2 wt% of emulsion type binder, 1 wt% of aqueous solution type adhesive and 1 wt% of aqueous solution type macromolecular thickener in terms of dry material weight percentage;
the ceramic particles are alumina, and the average particle size of the alumina is 0.5 mu m; the emulsion type binder is styrene-acrylic emulsion, and the weight-average molecular weight of the styrene-acrylic emulsion is 500000 g/mol; the aqueous solution type adhesive is polyacrylic acid, and the weight average molecular weight of the polyacrylic acid is 300000 g/mol; the water-soluble macromolecular thickener is sodium carboxymethylcellulose.
Preparation of organically modified polymer wax coatings
Coating the modified polymer wax emulsion on the two sides of the porous base material, drying, and then performing surface function treatment, wherein the modified polymer wax emulsion forms an organic modified polymer wax coating on the surface of the porous base material, and the thickness of the organic modified polymer wax coating is 1 mu m, so as to obtain the porous base material with the organic modified polymer wax coating;
the surface functional treatment adopts corona irradiation modification treatment, and the irradiation power is 20kw and the irradiation time is 1 s;
the porous base material is a polyethylene porous base film, the thickness of the polyethylene porous base film is 12 mu m, and the porosity is 40%.
Preparation of inorganic ceramic coatings
And coating the ceramic slurry on the surface of the organic modified polymer wax coating subjected to surface function treatment, drying, and forming an inorganic ceramic coating on the surface of the organic modified polymer wax coating by the ceramic slurry, wherein the thickness of the inorganic ceramic coating is 2 microns, so as to obtain the diaphragm.
Example 2
A separator for a lithium ion battery, which is different from example 1 in that modified polymer wax particles are modified polyethylene wax particles and are prepared by using preparation example 4, and at this time, polar functional groups, which are graft-modified on the surfaces of the modified polyethylene wax particles, are mainly amine groups, and the rest is the same as example 1.
Example 3
A lithium ion battery separator is distinguished from example 1 in that modified polymer wax particles are modified polyethylene wax particles and are prepared by preparation example 2, and the polar functional groups grafted and modified on the surfaces of the modified polymer wax particles are mainly hydroxyl groups; the aqueous adhesive in the modified polymer wax emulsion was polyvinyl alcohol, the weight average molecular weight of which was 20000g/mol, and the remainder was the same as in example 1.
Example 4
A separator for a lithium ion battery, which is different from example 3 in that the aqueous solution type binder in the modified polymer wax emulsion is polyacrylamide, and the weight average molecular weight of the polyacrylamide is 20000 g/mol; the aqueous solution type binder in the ceramic slurry was polyvinyl alcohol having a weight average molecular weight of 300000g/mol, and the rest was the same as in example 3.
Example 5
A separator for a lithium ion battery, which is different from example 4 in that modified polymer wax particles are modified polyethylene wax particles and are prepared by the preparation example 3, wherein polar functional groups grafted and modified on the surfaces of the modified polymer wax particles are mainly carboxyl groups, and the rest is the same as example 4.
Example 6
A separator for a lithium ion battery, which is different from example 5 in that modified polymer wax particles are modified polyethylene wax particles and prepared by using preparation example 1, at this time, polar functional groups, which are graft-modified on the surfaces of the modified polymer wax particles, are mainly amine groups, and an aqueous solution type binder in a ceramic slurry is polyacrylic acid, the weight average molecular weight of the polyacrylic acid is 300000g/mol, and the irradiation power is 25kw, and the rest is the same as example 5.
Example 7
The diaphragm for the lithium ion battery is different from the diaphragm used in the embodiment 1 in the ratio of the modified polymer wax emulsion to the ceramic slurry, the plasma irradiation is adopted in the preparation method, the irradiation power is 20kw, the irradiation time is 1s, and the rest is the same as the diaphragm used in the embodiment 1.
The solid content of the modified polymer wax emulsion is 10 wt%, and the raw materials of the modified polymer wax emulsion comprise 80 wt% of modified polymer wax particles with surfaces containing grafting modified polar functional groups, 18 wt% of aqueous solution type adhesive and 2 wt% of aqueous solution type macromolecular thickening agent in terms of dry material weight percentage.
The solid content of the ceramic slurry is 30 wt%, and the raw materials of the ceramic slurry comprise, by weight percentage of dry materials, 98.5 wt% of ceramic particles, 0.5 wt% of emulsion type binder, 0.5 wt% of aqueous solution type binder and 0.5 wt% of water-soluble polymer thickener.
Example 8
The diaphragm for the lithium ion battery is different from the diaphragm used in the embodiment 1 in the ratio of the modified polymer wax emulsion to the ceramic slurry, ultraviolet irradiation is adopted in the preparation method, the irradiation power is 20kw, the irradiation time is 1s, and the rest parts are the same as the diaphragm used in the embodiment 1.
The solid content of the modified polymer wax emulsion is 40wt%, and the raw materials of the modified polymer wax emulsion comprise 96 wt% of modified polymer wax particles with surfaces containing grafting modified polar functional groups, 3 wt% of aqueous solution type adhesive and 1 wt% of aqueous solution type macromolecular thickening agent in terms of dry material weight percentage.
The solid content of the ceramic slurry is 45 wt%, and the raw materials of the ceramic slurry comprise 90 wt% of ceramic particles, 4.5 wt% of emulsion type binder, 4.5 wt% of aqueous solution type binder and 1 wt% of aqueous solution type high polymer thickener in terms of dry material weight percentage.
Comparative example
Comparative example 1
A separator for a lithium ion battery, which is different from example 1 in that modified polymer wax particles are modified polyethylene wax particles and are prepared by using preparation example 3, and polar functional groups grafted and modified on the surfaces of the modified polyethylene wax particles are mainly carboxyl groups; and the inorganic ceramic coating is not arranged in the diaphragm, namely the inorganic ceramic coating is not arranged on the surface of the organic modified polyethylene wax coating, and the rest parts are the same as the embodiment 1.
Comparative example 2
The separator for the lithium ion battery is different from the separator of the embodiment 1 in that the separator has no organic modified polyethylene wax coating, namely, an inorganic ceramic coating is directly arranged on the surface of a porous substrate, and the rest is the same as the separator of the embodiment 1.
Comparative example 3
A separator for a lithium ion battery, which is different from example 1 in that the surface of polyethylene wax particles is not graft-modified with polar functional groups, and the raw material polyethylene wax particles of preparation example 1S1 are used, and the rest is the same as example 1.
Comparative example 4
A separator for a lithium ion battery, which is different from example 1 in that modified polymer wax particles are modified polyethylene wax particles and are prepared by using preparation example 5, and at this time, polar functional groups, which are graft-modified on the surfaces of the modified polyethylene wax particles, are mainly amine groups, and the rest is the same as example 1.
Comparative example 5
The diaphragm for the lithium ion battery is different from the diaphragm of the comparative example 4 in that the organic modified polyethylene wax coating is obtained by drying after the modified polymer wax emulsion is coated on the two sides of the porous base material, namely, the diaphragm is not subjected to corona irradiation modification treatment, and the rest part of the diaphragm is the same as the comparative example 4.
Comparative example 6
A separator for a lithium ion battery is different from comparative example 4 in that an organic modified polyethylene wax coating is not provided, only a porous base material is subjected to corona irradiation modification treatment, and the rest is the same as comparative example 4.
Application example
A lithium ion battery comprises a negative pole piece, a positive pole piece, a porous diaphragm arranged between the positive pole piece and the negative pole piece, and electrolyte.
A preparation method of a lithium ion battery comprises the following steps:
preparation of cathode slurry
Stirring and uniformly mixing water, sodium carboxymethylcellulose thickener and styrene butadiene rubber binder, adding conductive carbon black, continuously stirring and uniformly mixing, grinding to below 5 mu m, adding graphite cathode active substance, continuously stirring and uniformly mixing, removing bubbles in vacuum, and sieving by a 150-mesh sieve to obtain cathode slurry.
The negative electrode slurry takes water as a dispersing solvent, the solid content of the negative electrode slurry is 42 wt%, and the raw materials of the negative electrode slurry comprise 94 wt% of graphite negative electrode active material, 3 wt% of styrene butadiene rubber binder, 1 wt% of sodium carboxymethylcellulose thickening agent and 2 wt% of conductive carbon black in terms of dry material weight percentage.
Preparation of negative pole piece
Coating the negative electrode slurry on two sides of a copper foil, drying and tabletting, wherein the thickness of the copper foil is 10 mu m, the negative electrode slurry forms a negative electrode coating on the surface of the copper foil, the thickness of the negative electrode coating is 4 mu m, cutting pieces, and welding tabs to obtain a negative electrode piece.
Preparation of positive electrode slurry
Stirring and uniformly mixing N-methyl pyrrolidone and a polyvinylidene fluoride binder, then adding conductive carbon black, continuously stirring and uniformly mixing, grinding to below 5 mu m, then adding a lithium cobaltate positive electrode active substance, continuously stirring and uniformly mixing, removing bubbles in vacuum, and screening by a 150-mesh screen to obtain positive electrode slurry.
The positive electrode slurry takes N-methyl pyrrolidone as a dispersing solvent, the solid content of the positive electrode slurry is 45 wt%, and the raw materials of the positive electrode slurry comprise 92 wt% of lithium cobaltate positive electrode active material, 5 wt% of polyvinylidene fluoride binder and 3 wt% of conductive carbon black in terms of dry material weight percentage.
Preparation of positive pole piece
Coating the positive electrode slurry on two sides of a copper foil, drying and tabletting, wherein the thickness of the copper foil is 12 mu m, the positive electrode slurry forms a positive electrode coating on the surface of the copper foil, the thickness of the positive electrode coating is 3 mu m, cutting pieces, and welding lugs to obtain the positive electrode piece.
Preparation of the electrolyte
Stirring and uniformly mixing ethylene carbonate, propylene carbonate and dimethyl carbonate, then adding lithium hexafluorophosphate, and continuously stirring and uniformly mixing to obtain the electrolyte.
The volume ratio of the ethylene carbonate to the propylene carbonate to the dimethyl carbonate in the electrolyte is 3:3:4, and the concentration of lithium hexafluorophosphate in the electrolyte is 1 mol/L.
Assembly of lithium ion batteries
Winding the positive pole piece, the porous diaphragm and the negative pole piece into a battery cell, and then packaging the battery cell by using an aluminum-plastic composite film;
and (3) baking under a vacuum condition to remove water, and then injecting 5g of electrolyte to obtain the square flexible package lithium ion battery, wherein the size of the lithium ion battery is 3.6mm multiplied by 28mm multiplied by 86 mm.
The porous separator was a separator for a lithium ion battery according to any one of examples 1 to 8.
Performance detection
The separators obtained in examples 1 to 8 and comparative examples 1 to 6 were assembled into lithium ion batteries by the method of the application example, and the performance of the separator and the performance of the lithium ion battery were tested as follows, and the test results are shown in tables 1 and 2.
Wherein, the air permeability increase value of the diaphragm is based on the air permeability of the diaphragm obtained in the comparative example 6, namely, only the porous base material is subjected to the corona irradiation modification treatment, and the air permeability increase value of the diaphragm obtained in the comparative example 6 is 0.
TABLE 1 measurement of separator Performance
Figure BDA0003344564480000141
TABLE 2 lithium ion Battery Performance test results
Figure BDA0003344564480000142
As can be seen from tables 1 and 2, the separator of the present invention has good wettability because the organic modified polymer wax particles having a polar group on the surface and the inorganic ceramic coating are provided on the side surface of the porous base material, and the surface treatment is performed after the modified polymer wax emulsion is applied, and the contact angle of the electrolyte is 35 to 37 °. And the diaphragm has good lithium ion conductivity which is 0.45-0.52 mS/cm. More importantly, the thermal shrinkage rate of the diaphragm is below 20% at 160 ℃/30min, and the thermal shrinkage of the diaphragm is obviously inhibited. In particular, the separator obtained in example 6 has an MD thermal shrinkage of 9% and a TD thermal shrinkage of 7% at 160 ℃/30min, which can be controlled to be less than 10%, effectively resists the shrinkage stress of the separator at high temperature, improves the safety and the service life of the lithium ion battery, and further provides the lithium ion battery with good discharge rate and 1000 cycle capacity retention rate, so that the whole separator has good performance, and meets the market demand.
Comparing example 1 with comparative examples 1-2, in example 1, the organic modified polymer wax coating and the inorganic ceramic coating are provided on the side surface of the porous base material, in comparative example 1, the organic modified polymer wax coating is provided only on the side surface of the porous base material, and in comparative example 2, the inorganic ceramic coating is provided only on the side surface of the porous base material. Therefore, the diaphragm in the application obviously improves the air permeability increase value of the diaphragm by utilizing the mutual matching of the organic modified polymer wax coating and the inorganic ceramic coating, also obviously reduces the thermal shrinkage rate, and simultaneously improves the discharge rate of the lithium ion battery of 3.0C/0.2C and the cycle capacity retention rate of the lithium ion battery for 1000 times, so that the diaphragm keeps good wettability, the thermal stability of the diaphragm is also improved, the use safety and the service life of the lithium ion battery are further improved, and the market demand is met.
Comparative examples 4 to 6 were compared, in comparative example 4 the organic modified polymer wax coating was provided only on the side of the porous substrate, in comparative example 5 the corona radiation modification treatment was not performed, and in comparative example 6 only the porous substrate was subjected to the corona radiation modification treatment. Therefore, the modified polymer wax emulsion is coated on the side surface of the porous base material and then is subjected to corona irradiation modification treatment, so that the air permeability increase value and the lithium ion conductivity of the diaphragm are obviously improved, the discharge rate of the lithium ion battery is improved by 3.0C/0.2C, and the cycle capacity retention rate of the lithium ion battery is improved by 1000 times, the diaphragm has good lithium ion conductivity, and the performance of the lithium ion battery is also improved.
Comparing example 1 with example 2, the average particle size of the modified polyethylene wax particles in example 1 was 0.5 μm, and the average particle size of the modified polyethylene wax particles in example 2 was 0.2. mu.m. Therefore, the particle size of the modified polyethylene wax particles is reduced, the air permeability increase value of the diaphragm is obviously improved, and the discharge rate of the lithium ion battery is also reduced by 3.0C/0.2C, which is probably because the particle size of the modified polyethylene wax particles is smaller and blocks the channels of the porous base material, the path through which lithium ions pass is reduced, and the particle size is reduced, so that the total specific surface area of the modified polyethylene wax particles is increased, the distribution of the modified polyethylene wax particles in the organic modified polymer wax coating is changed, and the air permeability of the diaphragm is increased. Meanwhile, the granularity of the modified polyethylene wax particles is reduced, the thermal shrinkage rate of the diaphragm is also obviously reduced, and the peel strength of the inorganic ceramic coating is improved, which probably is because the modified polyethylene wax particles and the inorganic ceramic coating generate stronger bonding and anchoring effects after being subjected to corona irradiation modification treatment, so that the contractility generated by the diaphragm during high-temperature thermal shrinkage is controlled, the deformation of the diaphragm is reduced, the granularity of the modified polyethylene wax particles is reduced, the total specific surface area of the diaphragm is increased, the bonding strength between the diaphragm and the inorganic ceramic coating is further enhanced, and the performance of the diaphragm is improved.
Comparing example 4 with example 5, the polar functional group of the surface graft modification of the modified polymer wax particle in example 4 is mainly hydroxyl, and the polar functional group of the surface graft modification of the modified polymer wax particle in example 5 is mainly carboxyl. Therefore, the polar functional groups contained on the surfaces of the modified polymer wax particles have certain influence on the performance of the diaphragm and the lithium ion battery, which is probably due to the influence of van der waals and hydrogen bond interaction force between the polar functional groups contained on the surfaces of the modified polymer wax particles and the organic modified polymer wax coating, the inorganic ceramic coating and the porous substrate.
Comparing example 3 with example 4, the aqueous solution type binder in the modified polymer wax emulsion in example 3 is polyvinyl alcohol, the aqueous solution type binder in the ceramic slurry is polyacrylic acid, the aqueous solution type binder in the modified polymer wax emulsion in example 4 is polyacrylamide, and the aqueous solution type binder in the ceramic slurry is polyvinyl alcohol. Therefore, the aqueous solution type adhesive in the modified polymer wax emulsion and the aqueous solution type adhesive in the ceramic slurry have certain influence on the performances of the diaphragm and the lithium ion battery, and the influence of van der Waals and hydrogen bond interaction force among the aqueous solution type adhesive in the modified polymer wax emulsion, the aqueous solution type adhesive in the ceramic slurry, the organic modified polymer wax coating, the inorganic ceramic coating and the porous base material can be also considered.
By comparing with examples 3 to 5, it can be seen that the polar functional group contained on the surface of the modified polyethylene wax particle, the aqueous solution type adhesive in the modified polymer wax emulsion slurry, and the aqueous solution type adhesive in the ceramic slurry have a certain influence on the performance of the separator, and the interaction of the organic modified polymer wax coating and the inorganic ceramic coating can be maximally exerted by the function of the mutually matched functional groups, the affinity of the separator to the electrolyte can be improved, the adhesion strength of the inorganic ceramic coating on the porous substrate can be enhanced, the liquid retention amount can be improved, and the lithium ion conductivity can be improved.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (10)

1. A separator for a lithium ion battery, characterized in that: the coating comprises a porous base material and an organic modified polymer wax coating fixedly arranged on one side or two sides of the porous base material, wherein an inorganic ceramic coating is fixedly arranged on the side surface of the organic modified polymer wax coating far away from the porous base material;
the raw materials of the organic modified polymer wax coating are modified polymer wax emulsion, water is used as a dispersing solvent, the solid content of the modified polymer wax emulsion is 10-40wt%, and the modified polymer wax emulsion is prepared from the following raw materials in percentage by weight: 80-96% of modified polymer wax particles with surfaces containing grafted modified polar functional groups, 3-18% of aqueous solution type adhesive and 1-2% of aqueous solution type macromolecular thickening agent;
the inorganic ceramic coating is prepared from the following raw materials in percentage by weight, wherein the raw materials of the inorganic ceramic coating are ceramic slurry, water is used as a dispersing solvent, the solid content of the ceramic slurry is 30-45 wt%, and the ceramic slurry is prepared from the following raw materials in percentage by weight: 90-98.5% of ceramic particles, 0.5-4.5% of emulsion type binder, 0.5-4.5% of aqueous solution type binder and 0.5-1% of water-soluble polymer thickener.
2. The separator for a lithium ion battery according to claim 1, characterized in that: the organic modified polymer wax coating is obtained by drying and surface functional treatment after the modified polymer wax emulsion is coated on one side or two sides of the porous base material; the surface functional treatment is one of corona, plasma and ultraviolet irradiation.
3. The separator for a lithium ion battery according to claim 1, characterized in that: the modified polymer wax particles are one of modified polyethylene wax particles and modified polypropylene wax particles.
4. The separator for a lithium ion battery according to claim 1, characterized in that: the modified polymer wax particle surface grafting modified polar functional group comprises one or more of amino, imino, carboxyl, hydroxyl and amino.
5. The separator for a lithium ion battery according to claim 1, characterized in that: the modified polymer wax particles have an average particle size of 0.1 to 10 μm and the ceramic microparticles have an average particle size of 0.1 to 5.0 μm.
6. The separator for a lithium ion battery according to claim 1, characterized in that: the water solution type adhesive is one or more of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, calcium polyacrylate, polyvinyl alcohol and polyacrylamide;
the water solution type high molecular thickening agent is one or more of sodium carboxymethylcellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and sodium alginate;
the emulsion type binder is one or more of styrene-acrylic emulsion, butylbenzene emulsion, vinyl acetate copolymer emulsion and acrylate copolymer emulsion.
7. The separator for a lithium ion battery according to claim 1, characterized in that: the modified polymeric wax particles were prepared using the following method:
s1, stirring and uniformly mixing the polymer wax particles, epichlorohydrin and hydrochloric acid solution, heating to 55-65 ℃, carrying out heat preservation treatment for 0.5-1.5h, filtering, and drying to obtain chloro-esterified polymer wax particles;
s2, adding the chloro-esterified polymer wax particles obtained in the step S1 into 1, 4-dioxane, stirring for 1.5-2.5h, adding sodium hydroxide, tetrabutylammonium bromide and a polar group modifier, heating to 55-65 ℃, preserving heat for 4.5-5.5h, filtering, and drying to obtain modified polymer wax particles.
8. The separator for a lithium ion battery according to claim 7, wherein: the weight ratio of the polymer wax particles, the epichlorohydrin, the hydrochloric acid solution, the 1, 4-dioxane, the sodium hydroxide, the tetrabutylammonium bromide and the polar group modifier is (90-110), (450-;
the concentration of the hydrochloric acid solution is 0.5-1.5 mol/L.
9. A method for preparing the separator for lithium ion batteries according to any one of claims 1 to 8, characterized in that: the method comprises the following steps:
preparation of modified Polymer wax emulsions
Uniformly mixing the modified polymer wax particles with water to obtain a modified polymer wax aqueous dispersion liquid;
stirring and uniformly mixing the modified polymer wax aqueous dispersion liquid, the aqueous solution type adhesive and the aqueous solution type high-molecular thickening agent, and adding water to adjust the solid content to obtain a modified polymer wax emulsion;
preparation of ceramic slurry
Stirring and uniformly mixing ceramic particles, an aqueous solution type high-molecular thickening agent, an aqueous solution type adhesive and an emulsion type adhesive, and adding water to adjust the solid content to obtain ceramic slurry;
preparation of organically modified polymer wax coatings
Coating the modified polymer wax emulsion on one side or two sides of a porous base material, drying, then performing surface function treatment, and forming an organic modified polymer wax coating on the surface of the porous base material by the modified polymer wax emulsion to obtain the porous base material with the organic modified polymer wax coating;
preparation of inorganic ceramic coatings
And coating the ceramic slurry on the surface of the organic modified polymer wax coating after surface function treatment, drying, and forming an inorganic ceramic coating on the surface of the organic modified polymer wax coating by the ceramic slurry to obtain the diaphragm.
10. The utility model provides a lithium ion battery, includes positive pole piece, negative pole piece, sets up porous diaphragm, electrolyte between positive pole piece and negative pole piece, its characterized in that: the porous separator is the lithium ion battery separator according to any one of claims 1 to 8.
CN202111319056.XA 2021-11-09 2021-11-09 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery Pending CN114039166A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111319056.XA CN114039166A (en) 2021-11-09 2021-11-09 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111319056.XA CN114039166A (en) 2021-11-09 2021-11-09 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery

Publications (1)

Publication Number Publication Date
CN114039166A true CN114039166A (en) 2022-02-11

Family

ID=80136846

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111319056.XA Pending CN114039166A (en) 2021-11-09 2021-11-09 Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery

Country Status (1)

Country Link
CN (1) CN114039166A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116169428A (en) * 2023-04-06 2023-05-26 宁德新能源科技有限公司 Separator, electrochemical device and electronic device comprising same
CN117878529A (en) * 2024-03-13 2024-04-12 宁波长阳科技股份有限公司 Low-moisture high-heat-resistance ceramic coating diaphragm and preparation method thereof

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1499658A (en) * 2002-11-01 2004-05-26 1 Anti-explosion membrane for lithium ion secondary cell
US20080118827A1 (en) * 2006-11-17 2008-05-22 Call Ronald W Co-extruded, multi-layered battery separator
CN102883885A (en) * 2010-09-30 2013-01-16 三菱树脂株式会社 Laminated porous film, separator for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery
CN103247770A (en) * 2013-04-25 2013-08-14 东莞新能源科技有限公司 Lithium-ion battery separator and manufacturing method thereof
CN107078253A (en) * 2014-07-18 2017-08-18 米尔泰克紫光国际有限公司 Ceramic particle lithium secondary battery spacer of the polymer bonding of ultraviolet or electronic beam curing and preparation method thereof
CN108963164A (en) * 2018-06-28 2018-12-07 深圳市旭然电子有限公司 Inorganic ceramic coating functions lithium ion battery isolation film, preparation method and its lithium ion battery
CN111192996A (en) * 2019-12-17 2020-05-22 山东海科创新研究院有限公司 Organic coating/polyethylene composite diaphragm, preparation method thereof and lithium ion battery
US20200388808A1 (en) * 2019-06-07 2020-12-10 Samsung Sdi Co., Ltd. Separator for rechargeable lithium battery and rechargeable lithium battery including the same
CN113078414A (en) * 2019-12-17 2021-07-06 山东海科创新研究院有限公司 Polypropylene composite diaphragm with low-temperature thermal closed-cell mechanism, preparation method thereof and lithium ion battery

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1499658A (en) * 2002-11-01 2004-05-26 1 Anti-explosion membrane for lithium ion secondary cell
US20080118827A1 (en) * 2006-11-17 2008-05-22 Call Ronald W Co-extruded, multi-layered battery separator
CN102883885A (en) * 2010-09-30 2013-01-16 三菱树脂株式会社 Laminated porous film, separator for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery
CN103247770A (en) * 2013-04-25 2013-08-14 东莞新能源科技有限公司 Lithium-ion battery separator and manufacturing method thereof
CN107078253A (en) * 2014-07-18 2017-08-18 米尔泰克紫光国际有限公司 Ceramic particle lithium secondary battery spacer of the polymer bonding of ultraviolet or electronic beam curing and preparation method thereof
CN108963164A (en) * 2018-06-28 2018-12-07 深圳市旭然电子有限公司 Inorganic ceramic coating functions lithium ion battery isolation film, preparation method and its lithium ion battery
US20200388808A1 (en) * 2019-06-07 2020-12-10 Samsung Sdi Co., Ltd. Separator for rechargeable lithium battery and rechargeable lithium battery including the same
CN111192996A (en) * 2019-12-17 2020-05-22 山东海科创新研究院有限公司 Organic coating/polyethylene composite diaphragm, preparation method thereof and lithium ion battery
CN113078414A (en) * 2019-12-17 2021-07-06 山东海科创新研究院有限公司 Polypropylene composite diaphragm with low-temperature thermal closed-cell mechanism, preparation method thereof and lithium ion battery

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116169428A (en) * 2023-04-06 2023-05-26 宁德新能源科技有限公司 Separator, electrochemical device and electronic device comprising same
CN116169428B (en) * 2023-04-06 2023-06-20 宁德新能源科技有限公司 Separator, electrochemical device and electronic device comprising same
CN117878529A (en) * 2024-03-13 2024-04-12 宁波长阳科技股份有限公司 Low-moisture high-heat-resistance ceramic coating diaphragm and preparation method thereof

Similar Documents

Publication Publication Date Title
CN107768625B (en) Silicon-carbon composite negative electrode material and preparation method thereof
JP5280313B2 (en) Lithium ion polymer battery comprising a polyolefin microporous membrane surface-modified with a hydrophilic polymer, a surface modification method thereof, and a surface-modified polyolefin microporous membrane as a separator
CN109346653B (en) Lithium battery diaphragm containing composite coating and preparation method thereof
CN114039166A (en) Diaphragm for lithium ion battery, preparation method of diaphragm and lithium ion battery
CN111554879A (en) Positive plate, manufacturing method of positive plate and battery
CN105161661A (en) Composite diaphragm for lithium ion battery, preparation method of composite diaphragm, and lithium ion battery
Ju et al. Unique core–shell structured SiO 2 (Li+) nanoparticles for high-performance composite polymer electrolytes
CN106654165A (en) Lithium ion battery pole piece, preparation method thereof, and lithium ion battery
CN114039167B (en) Porous lithium ion battery diaphragm, preparation method and lithium ion battery
CN107546391B (en) Polydopamine and graphene composite coating
CN110911612B (en) Cellulose acetate-based cross-linked composite lithium ion battery diaphragm and preparation method and application thereof
CN109950461A (en) A kind of diaphragm and preparation method thereof and battery
CN111540868A (en) Preparation method and application of two-dimensional manganese dioxide modified polypropylene diaphragm
JP2009110883A (en) Binder for electrochemical cell
CN107069043A (en) Lithium ion battery and preparation method thereof
CN112615111A (en) High-liquid-retention self-repairing diaphragm, preparation method thereof and lithium ion battery
CN113451703B (en) High-ion-conductivity composite gel polymer diaphragm and preparation method thereof
JP2002117860A (en) Electrode and lithium secondary battery
TW201904113A (en) Sulfur-carbon material composite, cathode material for lithium sulfur secondary battery, and lithium sulfur secondary battery
CN109411758B (en) Preparation method of aqueous conductive adhesive for lithium ion battery cathode
CN108767193B (en) Positive electrode containing low-swelling graphite coating and lithium battery
CN115275524B (en) Battery diaphragm and battery
CN114400297A (en) Lithium ion battery composite pole piece containing aerogel coating and preparation method thereof
CN108110197A (en) A kind of lithium battery selective membrane and preparation method thereof
CN109786620B (en) Coating film and preparation method and application thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination