TWI511352B - Ion polymer film material and its preparation method and lithium secondary battery - Google Patents

Description

Ionic polymer film material, preparation method thereof and lithium secondary battery

The invention relates to a separator material for an energy storage device such as a lithium ion secondary battery and a preparation method thereof, and belongs to the field of manufacturing lithium secondary batteries.

The battery is composed of a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is one of the important components in the battery. Its function in the battery is to act as a separator between the positive and negative electrodes inside the battery. In addition to preventing internal short circuit caused by direct contact between the positive and negative electrodes, it is necessary to isolate the electrons and ensure electrolysis. The ions in the liquid can pass smoothly to facilitate the electrochemical reaction of the battery.

The microporous structure, physical properties, chemical properties, thermal properties, etc. of the separator are closely related to the performance of the battery. For the isolation membrane of a lithium ion battery, since the lithium ion battery has a high working voltage, and the oxidation property of the positive electrode material and the reduction property of the negative electrode material are high, the lithium ion battery separator material and the highly electrochemically active positive and negative electrodes are used. In addition to excellent compatibility, the material should also have good stability, good solvent resistance, good ionic conductivity, good electrical insulation, good mechanical strength, high heat resistance and Fuse isolation. In other words, the physical and chemical properties of the separator are not only dependent on the substrate of the separator material, but also the separators of different materials have different physical and chemical properties, thus exhibiting a large difference in battery performance in the battery.

Commercially available lithium ion batteries, such as metal lithium secondary batteries or lithium sulfur batteries, are mostly made of polyolefin microporous membranes. The function of the microporous membrane in the battery is as a separator between the positive and negative electrodes inside the battery. In addition to preventing the internal short circuit caused by the direct contact between the positive and negative electrodes, it is necessary to isolate the electrons and ensure that the ions in the electrolyte can smoothly pass through, so as to facilitate the smooth passage of the ions in the electrolyte. Conduct an electrochemical reaction of the battery. There are two methods for preparing such a polyolefin microporous membrane: a dry process and a wet process.

In the dry process, a polyolefin resin is melted, extruded, and blown into a film to form a crystalline polymer film, which is subjected to crystallization treatment and annealing treatment to obtain a highly oriented multilayer structure; and then, after further stretching at a high temperature. The crystal interface is peeled off to form a porous structure, which can increase the pore diameter of the film. Among them, the dry method can be divided into a dry uniaxial stretching process and a dry two-way stretching process depending on the direction of stretching.

The dry uniaxial stretching process produces a low-crystallinity high-orientation polyethylene (PE) or polypropylene (PP) separator by hardening an elastic fiber, and then high-temperature annealing to obtain a highly crystalline film having high crystallinity. Such a film is first stretched at a low temperature to form defects such as silver streaks, and then the defects are pulled apart at a high temperature to form micropores. At present, Celgard Company of Japan and Ube Corporation of Japan use this process to produce single-layer PE, PP and 3-layer PP/PE/PP composite film. The separator produced by the process has a flat long microporous structure, and since the uniaxial stretching is performed only, the lateral strength of the separator is relatively poor, but the problem that the transverse direction of the separator is hardly caused by heat shrinkage is ensured.

The dry two-way stretching process is a process method developed by the Institute of Chemistry of the Chinese Academy of Sciences in the early 1990s. By using a β-crystal nucleating agent with nucleation in PP, the difference in density between different phases of PP is utilized. Different, a crystal transformation occurs during stretching to form micropores. Compared with the dry uniaxial stretching process, the dry biaxial stretching process has an increased strength in the transverse direction, and the stretching ratio in the transverse direction and the longitudinal direction can be appropriately changed according to the strength requirement of the separator to obtain the desired Performance.

Dry stretching is a common method for preparing lithium ion battery separators because of its simple process and no pollution. However, the process has difficulty in controlling the pore size and porosity, and the stretching is relatively small (only about 1 to 3). At low temperatures, it is easy to cause defects such as perforation of the separator, so it is impossible to make a very thin product by such a process.

The wet process is also called phase separation or thermal phase separation. It is a method of mixing liquid hydrocarbons or some small molecules with a polyolefin resin, heating and melting to form a homogeneous mixture, then cooling to phase separation, and pressing the film. Then, the membrane is heated to a temperature close to the melting point, biaxially stretched to orient the molecular chain, and finally, after maintaining the temperature for a period of time, the residual solvent is eluted by using a volatile substance to prepare a microporous membrane material which communicates with each other. This method is applicable to a wide range of materials. The pore size of the separator produced by the wet biaxial stretching process is on the order of the size of the phase micro interface, which is relatively small and uniform, and the stretching ratio of the wet biaxial stretching process can reach 5 to 7, so the performance of the separator is presented. The same is true, the transverse tensile strength is high, and the puncture strength is large. Therefore, the general wet biaxial stretching process does not cause perforation of the separator, so that the product can be made thinner and the battery energy density is higher.

It can be seen from the production process of the polyolefin microporous membrane that whether it is a dry process or a wet process, mechanical stretching is performed before the hole is formed, and the polyolefin resin used is a non-polar material of PP or PE. Due to the inherent chemical and physical properties of non-polar materials such as PP or PE and the production of microporous membranes For reasons such as the process, the polyolefin microporous membrane prepared by the above process has the defects of safety and service life in the lithium ion battery.

The main problems with polyolefin microporous membranes: (1) The microporous membrane has poor liquid absorption and liquid retention ability: since PP or PE is a non-polar material, it has poor affinity with a highly polar electrolyte, and the affinity of the electrolyte with the polyolefin microporous membrane is low. The ability of the pore membrane to absorb and maintain the electrolyte is deteriorated, and the liquid absorption and liquid retention ability of the microporous membrane are closely related to the charge and discharge cycle life of the battery; (2) Poor thermal stability of the membrane of the microporous membrane: the microporous membrane obtained by heat setting is obtained because the polyolefin microporous membrane is subjected to mechanical stretching to cause pores, or after mechanical stretching, and then organic solvent is used to extract the pores. This production process causes residual stress in the microporous membrane, so that the microporous membrane has a shape memory effect. When the temperature of the polyolefin resin is close to the softening point, the microporous membrane tends to restore the shape before stretching and produces a larger shape. Shrinkage, microporous membrane heat shrinkage must accompany the phenomenon of volume shrinkage and membrane area shrinkage, so that the microporous membrane loses the barrier between the positive and negative electrodes, so that the positive and negative electrodes inside the battery are short-circuited, causing the battery to burn, explode, etc. Sexual problems.

Based on the performance defects of the polyolefin microporous membrane and the causes of the occurrence of these performance defects, the inventors of the present invention have proposed a lithium ion battery separator having a thermal expansion and fusion closing effect. Chinese Patent Application No. 102280605A, the lithium The ion battery separator includes a microporous polyolefin separator and a surface coated with a polymer colloidal particle coating having a particle size of 10 nanometers (nm) to 1000 nm. The polymer colloidal particle coating is a polymer formed by polymerizing acrylonitrile in an organic solvent of ethylene vinyl acetate (EVA). The colloidal emulsion is applied to the surface of the microporous polyolefin separator and formed after it is dried. The modified separator has the thermal expansion and fusion closing effect, has good thermal stability, and has low shrinkage rate after heating, thereby avoiding the occurrence of burning and explosion of the battery, thereby improving the safety and reliability of the battery; The lithium ion battery separator has good liquid absorption and liquid retention ability for the electrolyte solution, so it can give the lithium ion battery excellent cycle life.

However, the inventors of the present invention believe that the lithium ion battery separator provided by the aforementioned patent document has good battery performance and safety, but is obtained from a modified microporous polyolefin separator, which is inevitable. It will increase the cost of the battery separator and make it limited by the price of the separator. In addition, this lithium ion battery separator needs to use a large amount of toluene as a solvent in the preparation process, which has environmental pollution problems. Increasing the manufacturing cost of such a lithium ion battery separator.

A first object of the present invention is to provide a non-porous dense membrane having a colloidal particle structure, i.e., an ionic polymer membrane material. According to the present invention, the ionic polymer film material is composed of a plurality of polymer colloidal particles whose surface is modified with a sulfonate group. Since the ionic polymer film material of the present invention is a non-porous dense film, when it is assembled in a battery as a separator, the separator does not cause significant heat shrinkage even after the battery is overheated.

Preferably, the polymer colloidal particles modified by the sulfonate groups are acrylate polymer colloidal particles modified with a sulfonate group on the surface, which can ensure that the ionic polymer membrane material and the electrolyte are more Good compatibility, and thus better liquid absorption and liquid retention.

In the polymerization process of the ionic polymer film material of the present invention, a reactive sulfonate surfactant is used as an emulsifier to synthesize a polymer colloidal emulsion modified with a sulfonate group. The reactive sulfonate surfactant may be a salt formed by a monosulfonate group and a cation, the sulfonate group being a vinyl sulfonate group, an allyl sulfonate group, Methylallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group, 2-acrylamido-2-methylpropane sulfonic acid a salt group, a styrene sulfonate group, or a combination thereof; and the cation can be a lithium ion, a sodium ion, or a potassium ion.

Accordingly, in the obtained ionic polymer film material, the sulfonate group is at least one selected from the group consisting of a vinyl sulfonate group and an allyl sulfonate group. Group, methallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group, 2-acrylamido-2-methylpropane a sulfonate group and a styrene sulfonate group.

After the polymer colloidal emulsion is cast into a film, an ionic polymer film material having a colloidal particle structure is formed. When a battery containing the ionic polymer film material (as a separator for a battery) is overheated, the separator does not substantially undergo heat shrinkage. In addition, since the ionic polymer membrane material absorbs the electrolyte, a colloidal ion conduction path is formed between the colloidal particles and the colloidal particles; and after the ionic polymer membrane material of the present invention absorbs the electrolyte or the solvent, the ionic polymer membrane material can The colloidal particle structure is still preserved, and the spherical colloidal particle structure is closely packed, which increases the tortuosity of the ion conduction path and further improves the electronic insulation performance of the polyanion electrolyte membrane.

Polymer colloidal emulsion modified with sulfonate groups on the surface After the film formation, the particle size of the colloidal particles was observed by a scanning electron microscope, and the average particle diameter obtained after the observation was in the range of 10 nm to 1.0 μm; preferably 20 nm to 200 nm. The ionic polymer film material has a thickness of from 10 μm to 40 μm.

A second object of the present invention is to form an ionic polymer/ceramic filler composite film by adding a ceramic filler to the aforementioned ionic polymer film to improve the rigidity of the ionic polymer/ceramic filler composite film material and reduce the rigidity. Deformation of ionic polymer/ceramic filler composite membrane materials. According to the present invention, the ionic polymer/ceramic filler composite film material is composed of a plurality of polymer colloidal particles modified with a sulfonate group on the surface and a plurality of ceramic filler particles dispersed in the colloidal particles of the polymer, and the The ionic polymer/ceramic filler composite membrane material is still a non-porous dense membrane.

Preferably, the polymer colloidal particles modified by the sulfonate groups are acrylate polymer colloidal particles modified with a sulfonate group on the surface, which can ensure that the ionic polymer membrane material and the electrolyte are more Good compatibility, and thus better liquid absorption and liquid retention.

In the polymerization process of the ionic polymer/ceramic filler composite membrane material of the invention, a reactive sulfonate surfactant is used as an emulsifier to synthesize a polymer colloidal emulsion modified with a sulfonate group on the surface. Thereafter, a ceramic filler slurry is added to the polymer colloidal emulsion, uniformly dispersed, and then cast into a film to form an ionic polymer/ceramic filler composite film. Since the ionic polymer/ceramic filler composite film absorbs the electrolyte, a colloidal ion conduction path is formed between the colloidal particles and the colloidal particles; and the ionic polymer/ceramic filler composite film material of the present invention absorbs the electrolyte or the solvent, The ionic polymer/ceramic filler composite film material can still retain a colloidal particle structure. again The tightly packed structure of spherical colloidal particles and the ceramic filler particles uniformly dispersed in the ionic polymer film can increase the tortuosity of the ion conduction path and improve the electronic insulation performance of the polyanion electrolyte membrane. At the same time, the presence of ceramic filler particles is more conducive to improving the rigidity of the ionic polymer/ceramic filler composite film, thereby reducing the deformation of the ionic polymer/ceramic filler composite film.

The reactive sulfonate surfactant may be a salt formed by a monosulfonate group and a cation, the sulfonate group being a vinyl sulfonate group, an allyl sulfonate group, Methylallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group, 2-acrylamido-2-methylpropane sulfonic acid a salt group, a styrene sulfonate group, or a combination thereof; and the cation can be a lithium ion, a sodium ion, or a potassium ion.

Accordingly, in the obtained ionic polymer/ceramic filler composite, the sulfonate group is at least one selected from the group consisting of vinyl sulfonate groups and allyl sulfonate. Acid salt group, methallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group, 2-propenyl amide group-2- a methylpropane sulfonate group and a styrene sulfonate group.

In the ionic polymer/ceramic filler composite membrane material whose surface is modified by a sulfonate group, the average particle diameter of the polymer colloidal particles may range from 10 nm to 1.0 μm, and the average particle size range of the ceramic filler particles is 10 nm. Up to 5.00 μm; preferably, the average particle size of the colloidal particles ranges from 20 nm to 200 nm, and the average particle size of the ceramic filler particles ranges from 20 nm to 0.5 μm; more preferably, the average particle size range of the ceramic filler particles is 20 nm to 200 nm.

Ceramic filler particles in ionic polymer/ceramic filler composite film The weight percentage (wt%) in the material is from 10% to 60%, preferably from 15% to 50%, more preferably from 25% to 30%. The ionic polymer/ceramic filler composite film has a thickness of 10 to 40 μm.

The following is a preparation method: the present invention further provides a method for preparing an ionic polymer film material, which comprises: adding a reactive sulfonate surfactant as an emulsifier during the polymerization to form a plurality of polymer colloidal particles, and synthesizing the surface One of the sulfonate groups is modified with a polymer colloidal emulsion; and the polymer colloidal emulsion is filmed and dried to obtain the ionic polymer film material.

Preferably, the preparation method further comprises: a. synthesis of a polymer colloidal emulsion: adding a colloidal protective agent and distilled water to the reaction flask, heating and stirring until completely dissolved, adding a reactive sulfonate surfactant, a polymerization reaction sheet And the cross-linking agent (the order of addition of the foregoing three kinds of reagents is not particularly limited), and the mixture is uniformly mixed, and then the starter is added to start the polymerization reaction to obtain the polymer colloidal emulsion; and b. The polymerization obtained by the foregoing steps is obtained. The ionic polymer film material is obtained by coating the colloidal emulsion on a plastic substrate and peeling it off after drying.

According to a preferred embodiment of the invention, the polymerization monomer is methyl acrylate.

In the above method, the reactive sulfonate surfactant is a salt formed by a monosulfonate group and a cation, the sulfonate group being a vinyl sulfonate group, allyl sulfonic acid. Salt group, methallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl methacrylate a sulfonate group, a 2-propenylguanidino-2-methylpropane sulfonate group, a styrene sulfonate group, or a combination thereof, and the cation is a lithium ion, a sodium ion, or a potassium ion.

In order to adjust the heat shrinkability of the ionic polymer film material, the liquid absorption and liquid retention ability of the electrolyte, and the flexibility of the polymer, etc., preferably, the present invention is further added to the polymerization system of the step a. The two polymerization monomers CH ₂ =CR ¹ R ^{2 are} subjected to a polymerization reaction.

Wherein R ¹ is -H or -CH ₃ ; R ² is -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ or -COO(CH ₂ ) _n CH ₃ , n is an integer between 0 and 14. Where -C ₄ H ₆ ON is , -C ₂ H ₃ CO ₃ is .

The second polymerizable monomer may be any one or a combination of the above-mentioned polymerizable monomers, and the second polymerizable monomer is used in an amount of 2% to 50%, preferably 2, based on the total weight of the polymerization monomers. % to 10%.

According to a preferred embodiment of the present invention, the raw materials for the polymerization include: a reactive sulfonate surfactant, a polymerization monomer, and a crosslinking agent, which can be polymerized by one-time addition, dropwise addition or batchwise addition. Here, the polymerization monomer is a combination of a methyl acrylate monomer or a methyl acrylate monomer and a second polymerization monomer.

More preferably, the present invention firstly adds 1/5 to 1/3 of the raw material (by weight) of the polymerization reaction, and after the polymerization reaction is carried out for a while, the remaining polymerization raw materials are added dropwise or in portions.

According to the present invention, the polymerization reaction time is preferably carried out by polymerization. In general, the polymerization time is from 4 hours to 36 hours, preferably from 8 hours to 24 hours.

According to the invention, the temperature of the polymerization is from 50 ° C to 90 ° C; preferably from 55 ° C to 70 ° C.

The invention further provides a preparation method of an ionic polymer/ceramic filler composite membrane material, which comprises: adding a reactive sulfonate surfactant as an emulsifier during the polymerization to form a plurality of polymer colloidal particles, and synthesizing the surface a polymer colloidal emulsion modified with a sulfonate group; a ceramic filler particle is added to the polymer colloidal emulsion and uniformly mixed to obtain a polymer colloid/ceramic filler composite emulsion, the ceramic filler particle being a metal oxide The ionic polymer/ceramic filler composite film material is obtained by forming a film or a metal composite oxide particle; and forming the polymer colloid/ceramic filler composite emulsion into a film and drying.

The preparation method further comprises: a. synthesizing the polymer colloidal emulsion: adding a colloidal protective agent and distilled water to the reaction flask, heating and stirring until completely dissolved, adding the reactive sulfonate surfactant, a polymerization monomer and a cross-linking agent (the order of addition of the foregoing three kinds of reagents is not particularly limited), and the mixture is uniformly mixed, and then the starter is added to start the polymerization reaction to obtain the polymer colloidal emulsion; b. Preparation of the ceramic filler slurry: in distilled water The ceramic filler and a dispersing agent are added, and the two are uniformly dispersed, and then further dispersed by a stirring ball mill, and then filtered by a 200-mesh screen to remove the unmilled larger particles, thereby obtaining a Ceramic filler slurry; c. adding the ceramic filler slurry to the polymer colloidal emulsion, uniformly dispersing and coating on a plastic substrate, such as a polyethylene terephthalate (PET) substrate, and peeling off after drying the moisture, that is, The ionic polymer/ceramic filler composite membrane material is available.

In the ionic polymer/ceramic filler composite film, the ceramic filler particles are present in an amount of 10% to 60% by weight, preferably 15% to 50%, based on the total mass of the ionic polymer/ceramic filler composite film.

According to a preferred embodiment of the present invention, the reactive sulfonate surfactant used in the method may be a vinyl sulfonate, an allyl sulfonate, a methallyl sulfonate or an allyloxy group. a hydroxypropyl sulfonate, hydroxypropyl sulfonate methacrylate, 2-propenyl guanidino-2-methylpropane sulfonate, a styrene sulfonate or a combination thereof; wherein the cation may be a lithium ion , sodium or potassium ions. The reactive sulfonate surfactant is used in an amount of 2% to 50%, preferably 2% to 10%, based on the total mass of the polymerization monomer.

According to a preferred embodiment of the present invention, in the aforementioned step a., the colloidal protective agent is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone, preferably polyvinyl alcohol. The colloidal protective agent is used in an amount of from 5% to 30%, preferably from 10% to 25%, based on the total mass of the polymerization monomers.

In the aforementioned step b., the dispersing agent is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone, preferably polyvinyl alcohol. In the ceramic filler slurry, the content of the ceramic filler particles is 80% to 95%, the content of the dispersant is 5% to 20%, and the solid content of the ceramic filler slurry is 20% to 50%.

According to a preferred embodiment of the present invention, a polymer colloidal milk The polymer reactive monomer methyl acrylate content is from 40% to 80% based on the total weight of the liquid.

In order to regulate the heat shrinkability of the ionic polymer/ceramic filler composite membrane material, the liquid absorption and liquid retention ability of the electrolyte, and the flexibility of the polymer, etc., the present invention preferably adds a second to the polymerization reaction system. Polymerization reaction of CH ₂ =CR ¹ R ² ; wherein R ¹ is -H or -CH ₃ ; R ² is -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ or -COO(CH ₂ ) _n CH ₃ , n is an integer between 0 and 14. Where -C ₄ H ₆ ON is , -C ₂ H ₃ CO ₃ is .

The second polymerizable monomer may be any one of the above-mentioned polymerizable monomers or a combination thereof, and the amount of the second polymerizable monomer is between 2% and 50%, based on the total weight of the polymerization monomer. Preferably, it is between 2% and 10%.

The crosslinking agent is a polymerizable monomer containing two double bonds or two or more double bonds, for example, divinylbenzene, trimethylolpropane triacrylate, dipropylene adipate, methylene double Acrylamide and the like. The amount of the crosslinking agent is from 2.0% to 10.0% based on the total weight of the polymerization monomer.

The initiator is a water-soluble initiator such as ammonium persulfate, potassium persulfate, hydrogen peroxide or 2,2'-azobis [2-methylpropionamidine] dihydrochloride, and the amount thereof is the weight of the monomer. 0.2 to 1.0%.

According to a preferred embodiment of the present invention, the original polymerization reaction Material: The reactive sulfonate surfactant, the polymerization monomer and the crosslinking agent may be added in one shot, dropwise or in batches. Here, the polymerization monomer is a combination of a methyl acrylate monomer or a methyl acrylate monomer and a second polymerization monomer.

More preferably, the present invention firstly adds 1/5 to 1/3 of the raw material (by weight) of the polymerization reaction, and after the polymerization reaction is carried out for a while, the raw materials of the remaining polymerization are added dropwise or in portions.

The polymerization reaction time is preferably such that the conversion ratio of the monomer polymerization reaction is 92% or more. In general, the polymerization time is from 4 hours to 36 hours; preferably from 8 hours to 24 hours.

The polymerization temperature is from 50 ° C to 90 ° C; preferably from 55 ° C to 70 ° C.

The ceramic filler is a metal oxide and a metal composite oxide, and has the general formula N _z M _x O _y , wherein N is an alkali metal or alkaline earth metal element, M is a metal element different from N, and Z is 0 to 5, x is from 1 to 6, and y is from 1 to 15. The ceramic filler particles have an average particle diameter (D50) of 10 nm to 5.0 μm, preferably 20 nm to 0.5 μm. Preferably, when the ceramic filler particles are metal oxides, the general formula is M _x O _y , wherein M is aluminum or bismuth, x is 1 to 6, and y is 1 to 15; when the ceramic filler particles are metal composite oxidation a compound of the formula N _z M _x O _y , wherein N is an alkali metal or alkaline earth metal element, but not aluminum, M is aluminum or bismuth, Z is between 0 and 5 but not equal to 0, and x is 1 to 6 , y is 1 to 15. Preferably, the ceramic filler particles are Al ₂ O ₃ and have an average particle diameter (D50) of from 20 nm to 200 nm.

The present invention further provides a lithium secondary battery comprising a separator, the material of the separator being the ionic polymer film material as described above or Prepared by the preparation method of the ionic polymer film material as described above; or the material of the separator is the ionic polymer/ceramic filler composite film material as described above or the ionic polymer/ceramic as described above The preparation method of the filler composite membrane material is prepared.

The invention provides a preparation method of a lithium secondary battery separator and a ionic polymer/ceramic filler composite membrane which are simple in process, low in manufacturing cost, water-dispersible medium, environmentally friendly, pollution-free and environmentally friendly.

The ionic polymer film material of the present invention is composed of a plurality of acrylate-based polymer colloidal particles, and the ionic polymer/ceramic filler composite film material is composed of a plurality of acrylate-based polymer colloidal particles and a plurality of ceramic filler particles. Herein, the solubility of the selected acrylate polymer is similar to the solubility of the organic solvent of the electrolyte, so that the ionic polymer/ceramic filler composite film can be ensured to have good compatibility with the electrolyte, and a good liquid absorption is achieved. And liquid retention capacity, which in turn can improve battery cycle life.

The invention adopts a polymer colloidal emulsion casting film forming process to form a non-porous dense film to ensure its stress-free residue. When a battery containing the dense film (as a separator for a battery) is overheated, the separator does not undergo significant heat shrinkage, thereby preventing short-circuiting of the positive and negative electrodes inside the battery. In particular, after the ionic polymer/ceramic filler composite membrane material absorbs the electrolyte, a colloidal ion conduction path is formed between the colloidal particles and the colloidal particles; further, after the ionic polymer/ceramic filler composite membrane material absorbs the electrolyte or the solvent, The ionic polymer/ceramic filler composite film material is capable of maintaining a colloidal particle structure. Furthermore, the spherical colloidal particles are closely packed and the ceramic filler uniformly dispersed in the ionic polymer film/ceramic filler composite film The particles can increase the tortuosity of the ion conduction path and improve the electronic insulation performance of the polyelectrolyte film. At the same time, the presence of ceramic filler particles increases the rigidity of the ionic polymer/ceramic filler composite film, thereby reducing the deformation of the ionic polymer/ceramic filler composite film.

A‧‧‧sulfonate group

B‧‧‧ polymer colloidal particles modified with sulfonate groups

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a polymer colloidal particle modified with a sulfonate group on a single surface, a represents a sulfonate group, and b represents a polymer colloidal particle having a surface modified with a sulfonate group.

Figure 2 is a schematic illustration of a polymer colloidal emulsion modified with a sulfonate group on the surface.

Figure 3 is a schematic illustration of an ionic polymer film composed of polymer colloidal particles modified with a sulfonate group on the surface.

4 is a scanning electron microscope (SEM) photograph of the ionic polymer membrane electrolyte of the present invention after immersion.

Fig. 5 is a graph showing the charge and discharge characteristics of a lithium secondary battery using the ionomer membrane of the present invention as a separator, wherein the ordinate is voltage (V) and the abscissa is gram capacity (mAh/g).

6 is a graph showing a change rate of a capacity retention ratio with a number of charge and discharge cycles during a charge and discharge cycle of a lithium secondary battery using an ionomer membrane as a separator, and an ordinate thereof is a capacity retention ratio (%), and an abscissa The number of cycles (times).

7 is a comparison chart of discharge curves of lithium secondary batteries of the ionic polymer film and the ionic polymer/Al ₂ O ₃ composite film prepared in Example 1 and Example 13, wherein the ordinate is voltage (V) and the abscissa is The electric capacity (mAh/g), a represents a battery containing an ionic polymer/Al ₂ O ₃ composite film, and b represents a battery containing an ionic polymer film.

8 is a fifth and 100th charge-discharge curve of a lithium secondary battery of the ionic polymer/Al ₂ O ₃ composite film prepared in Example 13, wherein the ordinate is voltage (V) and the abscissa is gram capacity ( mAh/g), A is the 5th charge and discharge curve, and B is the 100th charge and discharge curve.

9 is a scanning electron micrograph of an ionic polymer/Al ₂ O ₃ composite film prepared in Example 13.

In the following, the embodiments of the present invention will be described by way of specific examples, and those skilled in the art can readily understand the advantages and functions of the present invention, and can carry out various kinds without departing from the spirit of the present invention. Modifications and variations are made to implement or apply the subject matter of the invention.

The ionic polymer film material of the present invention is composed of a plurality of acrylate-based polymer colloidal particles whose surface is modified with a sulfonate group. The material of the polymer colloidal particles is preferably an acrylate-based polymer, the solubility of the acrylate-based polymer is similar to the solubility of the organic solvent used in the electrolyte, and the strong polar group on the surface of the polymer colloidal particle can be The chemical association with the solvent of the non-aqueous electrolyte (ie, the electrolyte without water) ensures that the ionic polymer membrane material of the present invention has good compatibility with the electrolyte, and achieves good liquid absorption and liquid retention capabilities.

The ionic polymer membrane material of the invention is in the polymerization process The acrylate polymer colloidal emulsion modified with a sulfonate group is synthesized by using a reactive sulfonate surfactant as an emulsifier. After the acrylate-based polymer colloidal emulsion is cast into a film, a polymer film having a colloidal particle structure can be formed. When the polymer film having the colloidal particle structure absorbs the electrolyte, a conductive ion conduction path can be formed between the colloidal particles; and after the polymer film having the colloidal particle structure absorbs the electrolyte or the solvent, the ionic polymer The membrane material can still retain the colloidal particle structure, so that the spherical colloidal particle structure is closely packed, the tortuosity of the ion conduction path is increased, and the electronic insulating property of the polyanion electrolyte membrane is improved.

According to a preferred embodiment of the present invention, after forming a film of a polymer colloidal emulsion modified with a sulfonate group, the particle size of the formed polymer colloidal particles is observed by a scanning electron microscope, and the obtained particle size is observed. The average particle size ranges from 10 nm to 1.0 μm, preferably from 20 nm to 200 nm. The ionic polymer film has a thickness of from 10 μm to 40 μm.

The reactive sulfonate surfactant is vinyl sulfonate, allyl sulfonate, methallyl sulfonate, allyloxy hydroxypropyl sulfonate, hydroxypropyl sulfonate methacrylate An acid salt, 2-acrylamido-2-methylpropane sulfonate, styrene sulfonate or a combination thereof; the cation is a lithium ion, a sodium ion or a potassium ion.

The ionic polymer film is prepared by the following method: a. Synthesis of a polymer colloidal emulsion: a colloidal protective agent and distilled water are added to a reaction flask, and the mixture is heated and stirred until completely dissolved, and a reactive sulfonate surfactant is added. The polymerization monomer and the crosslinking agent (the order of addition of the foregoing three reagents is not particularly limited), and the mixture is uniformly mixed, and then the initiator is added. Polymerization to obtain a polymer colloidal emulsion; and b. coating the polymer colloidal emulsion obtained in the foregoing step on a plastic substrate, and drying it and peeling off to obtain the ionic polymer film.

According to a preferred embodiment of the invention, the polymerization monomer is methyl acrylate.

In order to adjust the heat shrinkability of the ionic polymer film material, the liquid absorption and liquid retention ability of the electrolyte, and the flexibility of the polymer, etc., it is preferred that the present invention further comprises a second polymerization monomer in the polymerization reaction system. The polymerization was carried out with CH ₂ =CR ¹ R ² .

Wherein R ¹ is -H or -CH ₃ ; R ² is -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ or -COO(CH ₂ ) _n CH ₃ , n is an integer between 0 and 14. Where -C ₄ H ₆ ON is , -C ₂ H ₃ CO ₃ is .

The second polymerizable monomer may be any one or a combination of the above-mentioned polymerizable monomers, and the second polymerizable monomer is used in an amount of 2% to 50%, preferably 2, based on the total weight of the polymerization monomers. % to 10%.

According to a preferred embodiment of the present invention, the raw materials for the polymerization include: a reactive sulfonate surfactant, a polymerization monomer, and a crosslinking agent, which may be added in a single addition, dropwise addition or batchwise to carry out a polymerization reaction. Here, the polymerization monomer is a combination of a methyl acrylate monomer or a methyl acrylate monomer and a second polymerization monomer.

More preferably, the present invention firstly adds 1/5 to 1/3 of the raw material of the polymerization reaction (by weight), and after the polymerization reaction is carried out for a while, The raw materials of the remaining polymerization are added dropwise or in portions.

According to the present invention, the polymerization reaction time is preferably carried out by polymerization. In general, the polymerization time is from 4 hours to 36 hours, preferably from 8 hours to 24 hours.

According to the invention, the temperature of the polymerization is from 50 ° C to 90 ° C; preferably from 55 ° C to 70 ° C.

According to a preferred embodiment of the present invention, distilled water and polyvinyl alcohol are added to the reaction flask and heated to 85 ° C to 95 ° C. After the polyvinyl alcohol is completely dissolved, it is cooled to 55 ° C to 70 ° C, and then the polymerization raw material is added. Polymerization.

The colloidal protective agent of the present invention is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone; preferably, the colloidal protective agent is polyvinyl alcohol. The amount of the colloidal protective agent is from 5% to 30%, preferably from 10% to 25%, based on the total weight of the polymerization monomers.

The crosslinking agent is a polymerizable monomer containing two or more double bonds, for example, divinylbenzene, trimethylolpropane triacrylate, dipropylene adipate, methylenebis acrylamide The crosslinking agent is used in an amount of from 2.0% to 10.0%, preferably from 5.0% to 7.0%, based on the total weight of the polymerization monomers.

The initiator may be a commonly used initiator in the polymerization reaction, for example, a water-soluble initiator such as ammonium persulfate, potassium persulfate, hydrogen peroxide or azobisisobutylphosphonate, based on the total weight of the polymerization monomer. The starting agent is used in an amount of from 0.1% to 2.0%, preferably from 0.5% to 1.0%.

In addition, the ionic polymer/ceramic filler composite membrane material of the present invention is a plurality of acrylate polymer gels modified by surface sulfonate groups. The body particles are composed of a plurality of ceramic filler particles. Preferably, the material of the polymer colloidal particles is an acrylate polymer, the solubility of the acrylate polymer is similar to the solubility of the solvent used in the electrolyte, and the surface of the plasma polymer/ceramic filler composite colloidal particles The strong polar group can be chemically associated with the solvent of the non-aqueous electrolyte (ie, the electrolyte without water), thereby ensuring that the ionic polymer/ceramic filler composite membrane material of the present invention has good compatibility with the electrolyte. Achieve good liquid absorption and fluid retention.

According to a preferred embodiment of the present invention, the polymer colloidal particles modified with a sulfonate group have an average particle diameter ranging from 10 nm to 1.0 μm, and the ceramic filler particles have a particle diameter ranging from 10 nm to 5.00 μm; preferably. The average particle size of the polymer colloidal particles ranges from 20 nm to 200 nm, and the average particle size of the ceramic filler particles ranges from 20 nm to 0.5 μm; more preferably from 20 nm to 200 nm.

The aforementioned ionic polymer/ceramic filler composite film is prepared by the following method:

a. Synthetic polymer colloidal emulsion containing anionic group on the surface: adding colloidal protective agent and distilled water to the reaction flask, heating and stirring until completely dissolved; and then adjusting the temperature of the reactor to 50 ° C to 90 ° C (wherein, preferably 60 to 70 ° C), one time adding a reactive sulfonate surfactant, methyl acrylate, a second polymerization monomer and a crosslinking agent, and then adding a starter for polymerization up to 4 Up to 36 hours (of which 8 to 24 hours is better). In this step, after the temperature of the reactor is constant to the desired temperature, 1/5 to 1/3 of the reactive sulfonate surfactant and methyl acrylate are added first, followed by dropping or batching. Adding the remaining reactive sulfonate surfactant, methyl acrylate, second polymerization monomer and crosslinking agent, The starter is then added to initiate the polymerization.

b. Pre-dispersed ceramic filler slurry: ceramic filler particles and dispersant are added in distilled water, the two are stirred uniformly and dispersed in distilled water, and then further milled and dispersed by agitating ball mill, and the milling dispersion time is between 2 hours. Between 10 hours, it is preferred to carry out the slurry after 3 hours to 5 hours of milling, and then filter through a 200-mesh sieve to remove the unmilled larger particles to obtain a pre-dispersed product. Ceramic filler slurry.

c. adding a predetermined amount of the pre-dispersed ceramic filler slurry to the synthesized polymer colloidal emulsion, and thoroughly stirring and uniformly dispersing the mixture of the polymer colloidal emulsion and the ceramic filler slurry with a stirring and dispersing device, and then adopting The cast coating method is coated on a plastic substrate, such as a polyethylene terephthalate (PET) substrate, and after being dried and then peeled off, the ionic polymer/ceramic filler composite film can be obtained.

The reactive sulfonate surfactant is vinyl sulfonate, allyl sulfonate, methallyl sulfonate, allyloxy hydroxypropyl sulfonate, hydroxypropyl methacrylate a sulfonate, 2-propenylguanidino-2-methylpropane sulfonate, a styrene sulfonate or a combination thereof; wherein the cation may be a lithium ion, a sodium ion or a potassium ion, and the total of the polymerization monomer The reactive sulfonate surfactant is used in an amount of 2% to 50%, preferably 2% to 10% by weight.

In the foregoing step a., the colloidal protective agent is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone; preferably, the colloidal protective agent is polyvinyl alcohol. The colloidal protective agent is used in an amount of from 5% to 30%, preferably from 10% to 25%, based on the total mass of the polymerization monomers.

In the foregoing step b., the dispersing agent is polyvinyl alcohol, polyoxygen One of ethylene, polyacrylate, and polyvinylpyrrolidone is preferably polyvinyl alcohol. In the ceramic filler slurry, the content of the ceramic filler particles is 80% to 95%, the content of the dispersant is 5% to 20%, and the solid content of the ceramic filler slurry is 20% to 50%.

According to a preferred embodiment of the present invention, the content of the polymer reactive monomer methyl acrylate is from 40% to 80% based on the total weight of the polymer colloidal emulsion.

The second polymerizable monomer is CH ₂ =CR ¹ R ² , wherein R ¹ is -H or -CH ₃ ; R ² is -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON , -C ₂ H ₃ CO ₃ , -COO(CH ₂ ) _n CH ₃ , n is an integer between 0 and 14. Where -C ₄ H ₆ ON is , -C ₂ H ₃ CO ₃ is .

The second polymerizable monomer is any one or a combination of the above-mentioned polymerizable monomers, and the second polymerizable monomer is used in an amount of 2 to 50%, preferably 2%, based on the total weight of the polymerization monomers. Up to 10%.

The crosslinking agent is a polymerizable monomer containing two or more double bonds, for example, divinylbenzene, trimethylolpropane triacrylate, dipropylene adipate, methylenebis acrylamide The amount of the crosslinking agent is between 2.0% and 10.0% based on the total weight of the polymerization monomer.

The initiator may be a water-soluble initiator such as ammonium persulfate, potassium persulfate, hydrogen peroxide or azobisisobutylphosphonium, based on the total weight of the polymerization monomer, and the amount of the initiator is 0.2. % to 1.0%.

According to a preferred embodiment of the present invention, the raw materials for the polymerization reaction include: a reactive sulfonate surfactant, a polymerization monomer, and a crosslinking agent. It can be added in one portion, dropwise or in portions. Here, the polymerization monomer is a combination of a methyl acrylate monomer or a methyl acrylate monomer and a second polymerization monomer.

More preferably, the present invention firstly adds 1/5 to 1/3 of the raw material of the polymerization reaction (by weight), and after the polymerization reaction is carried out for a period of time, the remaining polymerization reaction is added dropwise or in batches. raw material.

The ceramic filler particles are metal oxides and metal composite oxides, and have the general formula N _z M _x O _y , wherein N is an alkali metal or alkaline earth metal element, M is a metal element different from N, and Z is 0 to 5 , x is 1 to 6, and y is 1 to 15. Preferably, when the ceramic filler particles are metal oxides, the general formula is M _x O _y , wherein M is aluminum or bismuth, x is 1 to 6, and y is 1 to 15; when the ceramic filler particles are metal composite oxidation a compound of the formula N _z M _x O _y , wherein N is an alkali metal or alkaline earth metal element, but not aluminum, M is aluminum or bismuth, Z is between 0 and 5 but not equal to 0, and x is 1 to 6 , y is 1 to 15. The ceramic filler particles are, for example, Al ₂ O ₃ , SiO ₂ or Li ₄ Ti ₅ O ₁₂ .

Preferably, the ceramic filler particles have an average particle diameter (D50) of from 10 nm to 5.0 μm; more preferably, from 20 nm to 0.5 μm. Preferably, the ceramic filler particles are Al ₂ O ₃ and have an average particle diameter (D50) of from 20 nm to 200 nm.

Example 1

In a four-necked reaction flask with condensed water, 1000 g of distilled water and 51 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C, and stirred to dissolve. After the polyvinyl alcohol was completely dissolved, it was cooled to 60 ° C, and then 156 g of methyl acrylate (MA) monomer, 10 g of sodium allyloxyhydroxypropyl sulfonate (AHPS) and 10 g of methylene bis acrylamide were added. Crosslinker, stirring for 1 hour Thereafter, 2 g of ammonium persulfate was added to start the polymerization reaction. After the reaction was carried out for 6 hours, 100 g of MA monomer and 5 g of AHPS were further added, and 1.5 g of ammonium persulfate was further added to continue the polymerization for 10 hours to obtain a solid content. It is a 23.9% white polymer colloidal emulsion with a monomer conversion rate of 96%.

Here, the synthesized polymer colloidal emulsion was measured for the average particle diameter (D50) of the polymer colloidal particles by a laser particle size analyzer, and the detection result was 1.62 μm.

Thereafter, the obtained polymer colloidal emulsion is coated on the PET substrate, and after drying the moisture, an ionic polymer film having a thickness of 20 μm to 25 μm is obtained. The prepared ionic polymer film was additionally observed by a scanning electron microscope to have a particle diameter of the polymer colloidal particles ranging from 80 nm to 100 nm.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of polymer colloidal particles modified with a sulfonate group on a single surface. Referring to Figure 1, a represents a sulfonate group and b represents a polymer colloidal particle having a surface modified with a sulfonate group. 2 is a schematic illustration of a polymer colloidal emulsion composed of a plurality of polymer colloidal particles modified with a sulfonate group on the surface. Figure 3 is a schematic illustration of an ionic polymer film consisting of polymer colloidal particles modified with sulfonate groups on the surface.

Example 2

In a four-necked reaction flask with condensed water, 1000 g of distilled water and 51 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C, and stirred to dissolve. After the polyvinyl alcohol is completely dissolved, it is cooled to 60 ° C, and then 156 g of methyl acrylate (MA) monomer, 10 g of 2-acrylamido-2-methylpropane sulfonate (AMPS) and 10 g of methylene are added. Cross-linking agent of bis-acrylamide After mixing for 1 hour, 2 g of ammonium persulfate was added to start the polymerization reaction. After the reaction was carried out for 6 hours, 100 g of MA monomer and 5 g of AMPS were further added, and 1.5 g of ammonium persulfate was further added to continue the polymerization for 10 hours. A white polymer colloidal emulsion was obtained.

Thereafter, the obtained polymer colloidal emulsion is coated on the PET substrate, and after drying the moisture, an ionic polymer film having a thickness of 20 μm to 25 μm is obtained. The prepared ionic polymer film was additionally observed by a scanning electron microscope to have a particle diameter of the polymer colloidal particles ranging from 80 nm to 100 nm.

Example 3

In a four-neck reaction flask with condensed water, 1000 g of distilled water and 51 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C, and stirred and dissolved. After the polyvinyl alcohol was completely dissolved, it was cooled to 60 ° C, and then 156 g of acrylic acid was added. A crosslinking agent of methyl ester (MA) monomer, 8 g of allyl sulfonate (SAS) and 10 g of methylene bis acrylamide is stirred for 1 hour, and 2 g of ammonium persulfate is added to start polymerization, and the reaction is carried out. After 6 hours, another 100 grams of MA monomer and 4 grams of SAS were added, and 1.5 grams of ammonium persulfate was added to continue the polymerization for up to 10 hours to obtain a white polymer colloidal emulsion.

Thereafter, the prepared polymer colloidal emulsion was coated on a PET substrate, and after drying the moisture, an ionic polymer film having a thickness of 20 μm to 25 μm was obtained. The prepared ionic polymer film was additionally observed by a scanning electron microscope to have a particle size ranging from 40 nm to 60 nm.

Example 4

In a four-neck reaction flask with condensed water, 1000 g of distilled water and 51 g of polyvinyl alcohol were added, and then the temperature was raised to 92 ° C to stir. Dissolved, after the polyvinyl alcohol was completely dissolved, cooled to 60 ° C, and then crosslinked with 156 g of methyl acrylate (MA) monomer, 8 g of allyl sulfonate (SAS) and 10 g of dipropylene adipate. The mixture was stirred for 1 hour, and 2 g of ammonium persulfate was added to start the polymerization reaction. After the reaction was carried out for 6 hours, 100 g of MA monomer and 4 g of SAS were further added, and 1.5 g of ammonium persulfate was further added to continue the polymerization for 10 hours. A white polymer colloidal emulsion was obtained.

Thereafter, the prepared polymer colloidal emulsion was coated on a PET substrate, and after drying the moisture, an ionic polymer film having a thickness of 20 μm to 25 μm was obtained. The prepared ionic polymer film was additionally observed by a scanning electron microscope to have a particle diameter of the polymer colloidal particles ranging from 40 nm to 60 nm.

Example 5

The polymer colloidal emulsion and the ionic polymer film of this example were prepared in the same manner as in Example 4 except that this example further added 25 g of the second polymerizable monomer: acrylamide (CH ₂ CHCONH ₂ ).

Example 6

The polymer colloidal emulsion and the ionic polymer film of this example were prepared in the same manner as in Example 4 except that this example further added 25 g of the second polymerizable monomer: acrylonitrile (CH ₂ CHCN).

Example 7

The polymer colloidal emulsion and the ionic polymer membrane of this example were prepared in the same manner as in Example 4, except that this example further added 25 g of the second polymerizable monomer: butyl acrylate (CH ₂ CHCOOCH ₂ CH _{2 ).} CH ₂ CH ₃ ).

Example 8

The polymer colloidal emulsion and the ionic polymer film of this example were prepared in the same manner as in Example 4, except that this example further added 25 g of the second polymerizable monomer: vinyl ethylene carbonate (CH ₂ CHC _{2 ).} H ₃ CO ₃ ).

The ceramic filler slurry used in the following examples was prepared by the following method: preparation of an Al ₂ O ₃ slurry: 20 parts by weight of polyvinyl alcohol having a degree of polymerization of 1700 and a hydrolysis degree of 99% was added to 1000 parts by weight of distilled water, and then Heating to 90 ° C to 94 ° C, dissolving polyvinyl alcohol under stirring for 3 hours, then cooling to room temperature, and then adding 200 parts by weight of Al ₂ O ₃ having an average particle diameter (D50) of 36 nm, stirring and dispersing evenly, and then The dispersion was further milled using a stirring ball mill, and the milling dispersion time was 4 hours. The milled slurry was then filtered through a 200-mesh screen to remove unmilled larger particles.

Al ₂ O ₃ in the slurry process, the loss of water due to evaporation, the resulting slurry Al ₂ O ₃ Al ₂ O ₃ content of 21.5 weight percent (wt%).

Example 9: Preparation of ionic polymer/ceramic filler composite film

100 g of the polymer colloidal emulsion prepared in Example 1 and 12.4 g of an Al ₂ O ₃ slurry were placed in a three-necked flask and stirred for 10 hours to obtain a uniformly dispersed polymer colloidal emulsion and an Al ₂ O ₃ slurry mixture slurry. Then, the mixture slurry is coated on a polyethylene terephthalate (PET) substrate by a cast coating method, and after drying the moisture, it is peeled off to obtain an ionic polymer having a thickness of 20 μm to 25 μm/ Al ₂ O ₃ composite film. Wherein, the weight percentage of Al ₂ O ₃ in the polymer/Al ₂ O ₃ composite film is 10%.

Example 10: Preparation of ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the Al ₂ O ₃ slurry was added in an amount of 19.6 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage of the ₂ O ₃ composite film is 15%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film is 20 μm to 25 μm.

Example 11: Preparation of ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the Al ₂ O ₃ slurry was added in an amount of 27.8 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage in the ₂ O ₃ composite film was 20%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film was 20 to 25 μm.

Example 12: Preparation of ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the Al ₂ O ₃ slurry was added in an amount of 37.1 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage of the ₂ O ₃ composite film is 25%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film is 20 μm to 25 μm.

Example 13: Preparation of ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the addition amount of the Al ₂ O ₃ slurry was 47.6 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage of the ₂ O ₃ composite film is 30%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film is 20 μm to 25 μm.

Example 14: Preparation of ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the addition amount of the Al ₂ O ₃ slurry was 74.1 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage of the ₂ O ₃ composite film is 40%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film is 20 μm to 25 μm.

Example 15: Preparation of ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the Al ₂ O ₃ slurry was added in an amount of 111.2 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage of the ₂ O ₃ composite film is 50%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film is 20 μm to 25 μm.

Example 16: Preparation of an ionic polymer/ceramic filler composite film

The ionic polymer/Al ₂ O ₃ composite film of this embodiment was prepared in the same manner as in Example 9, except that the addition amount of the Al ₂ O ₃ slurry was 166.7 g, wherein Al ₂ O _{3 was} in the polymer/Al. The weight percentage of the ₂ O ₃ composite film is 60%, and the thickness of the ionic polymer/Al ₂ O ₃ composite film is 20 μm to 25 μm.

Test example 1

The ionic polymer membranes prepared in Examples 1 to 8 were immersed in an electrolyte composed of ethylene carbonate/diethyl carbonate/dimethyl carbonate and LiPF ₆ to be used after the ionic polymer film sufficiently absorbed the electrolyte. The impedance meter was used to measure the ionic conductivity and the amount of electrolyte absorption. The ionic conductivity and electrolyte absorption of commercial polypropylene and polypropylene microporous membranes were also compared under the same conditions. Listed in Table 1.

After the ionic polymer film is immersed in the electrolyte, the typical microscopic morphology of the ionic polymer film is observed by a scanning electron microscope. As shown in FIG. 4, the microscopic structure of the ionic polymer film of the present invention remains in the form of colloidal particles after being impregnated with the electrolyte.

Test example 2

The ionic polymer films prepared in Examples 1 to 8 and commercial polypropylene and polypropylene microporous films were heated to 130 ° C and 150 ° C, and their heat shrinkage ratios were measured. The test results are also shown in Table 1.

From the comparison results of Table 1, it was revealed that the ionic polymer film of the present invention has a small heat shrinkage rate, and the polyethylene and polypropylene microporous films have been severely shrunk or melted at the same temperature such as 150 °C.

Test Example 3

The ionic polymer film prepared in Example 5 was assembled into a 2032 button type battery according to a button cell preparation process familiar to those skilled in the art, and the battery comprises LiMn ₂ O ₄ as a positive electrode material and metallic lithium as a negative electrode material. And an electrolyte composed of ethylene carbonate / diethyl carbonate / dimethyl carbonate / LiPF ₆ . The assembled 2032 button lithium secondary battery was tested for charge and discharge performance under the charge and discharge rate of 0.2C.

Fig. 5 is a charge and discharge curve of a lithium secondary battery of an ionic polymer film, which shows that an ionomer membrane is used as a separator for a battery, and the battery can have good charge and discharge performance.

Fig. 6 is a graph showing the capacity retention ratio of the lithium secondary battery in the charge and discharge cycle of the ionic polymer film as a function of the number of charge and discharge cycles. It was confirmed by Fig. 6 that the battery of the ionic polymer film did have good charge and discharge cycle performance.

Test Example 4

The ionic polymer/Al ₂ O ₃ composite film prepared in Examples 9 to 16 was immersed in an electrolyte composed of ethylene carbonate/diethyl carbonate/dimethyl carbonate and LiPF6 to be ionic polymer/Al ₂ O _{3 After the} composite membrane fully absorbed the electrolyte, the amount of electrolyte absorption was measured, and the ionic conductivity was measured using an electrochemical impedance meter. The test results are shown in Table 2.

Test Example 5

The ionic polymer/Al ₂ O ₃ composite film obtained in Examples 9 to 16 was heated to 130 ° C, and the heat shrinkage ratio thereof was measured, and the test results are also shown in Table 2.

The experimental results of Table 2 show that the ionic polymer/Al ₂ O ₃ composite film of the present invention gradually decreases in thermal shrinkage rate with the increase of Al ₂ O ₃ , and the electrical conductivity exhibits an optimum value of about 30% of the ceramic filler particles. When the content of the ceramic filler particles exceeds 50%, the electrical conductivity decreases. Therefore, the results of the above experiments show that the content of the ceramic filler particles should not exceed 60%. Preferably, the ceramic filler is present in an amount between 15% and 50%, more preferably between 25% and 30%.

Test Example 6

The ionic polymer and ionic polymer/Al ₂ O ₃ composite film prepared in Example 1 and Example 13 were assembled into a 2032 button battery according to a button cell preparation process familiar to those skilled in the art, the battery comprising LiMn ₂ O _{4 was used} as a positive electrode material, metallic lithium was used as a negative electrode material, and an electrolytic solution composed of ethylene carbonate/diethyl carbonate/dimethyl carbonate/LiPF _{6 was used} . The assembled 2032 button lithium secondary battery was tested for charge and discharge performance under the charge and discharge rate of 0.2C.

7 is a lithium secondary battery discharge curve of the ionic polymer film and the ionic polymer/Al ₂ O ₃ composite film prepared in Example 1 and Example 13, which shows that the ionic polymer/Al ₂ O ₃ composite film is ion-polymerized. The film has better charge and discharge performance. Under the same conditions, the ionic polymer film of the battery lithium manganate material has a gram capacity of only 107 mAh/g, while the ionic polymer/Al ₂ O ₃ composite film of the battery is manganic acid. The lithium material has a gram capacity of 115 mAh/g. The reason for the increase in the gram capacity of the lithium manganate material is that there is a heterophase interface between the Al ₂ O ₃ and the polymer colloid, and the heterophase interface can help to increase the ion of the ionic polymer/Al ₂ O ₃ composite film. Conductivity.

Fig. 8 is a graph showing the fifth and 100th charge and discharge curves of the lithium secondary battery of the ionic polymer/Al ₂ O ₃ composite film prepared in Example 13. As shown in FIG. 8, after the lithium secondary battery was subjected to 100 charge and discharge cycles, the capacity retention rate was still 98% of the initial capacity, indicating that the lithium secondary battery can have excellent charge and discharge cycle performance.

9 is a scanning electron micrograph of the ionic polymer/Al ₂ O ₃ composite film prepared in Example 13, and the picture shows that the ionic polymer/Al ₂ O ₃ composite film is still impregnated with colloidal particles after being immersed in the electrolyte. The ceramic filler particles constitute the microstructure of the ionic polymer/Al ₂ O ₃ composite film.

A‧‧‧sulfonate group

B‧‧‧ polymer colloidal particles modified with sulfonate groups

Claims (28)

An ionic polymer film material consisting of a plurality of methyl acrylate-based polymer colloidal particles whose surface is modified with a sulfonate group. The ionic polymer film material according to claim 1, wherein the sulfonate group is at least one selected from the group consisting of a vinyl sulfonate group and an allyl sulfonate group. Group, methallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group, 2-acrylamido-2-methylpropane a sulfonate group and a styrene sulfonate group. The ionic polymer film material according to claim 1 or 2, wherein the polymer colloidal particles have a particle diameter of from 10 nm to 1.0 μm. The ionic polymer film material of claim 3, wherein the ionic polymer film material has a thickness of from 10 micrometers (μm) to 40 μm. A method for preparing an ionic polymer film material, comprising: adding a reactive sulfonate surfactant as an emulsifier in the process of polymerizing a polymerization reaction monomer methyl acrylate to form a plurality of polymer colloidal particles; One of the acid salt groups is modified by a salt acid ester emulsion; and the polymer colloidal emulsion is filmed and dried to obtain the ionic polymer film material. The method for preparing an ionic polymer film material according to claim 5, wherein the reactive sulfonate surfactant is a salt formed by a monosulfonate group and a cation, and the sulfonate group is ethylene. Sulfonate group, allyl sulfonate group, methallyl sulfonate group, allyloxy hydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group 2-propenylamine a -2-methylpropane sulfonate group, a styrene sulfonate group, or a combination thereof, and the cation is a lithium ion, a sodium ion, or a potassium ion. The method for preparing an ionic polymer film material according to claim 6, wherein the preparation method further comprises: a. synthesizing a polymer colloidal emulsion: adding a colloidal protective agent and distilled water to the reaction bottle, heating and stirring until completely dissolved, Adding the reactive sulfonate surfactant, methyl acrylate and a crosslinking agent to mix uniformly, adding a starter to carry out polymerization to obtain the polymer colloidal emulsion; and b. coating the polymer colloidal emulsion on the polymer The ionic polymer film material is obtained by peeling off on a plastic substrate after drying. The method for preparing an ionic polymer film material according to claim 7, wherein in the step a., the preparation method further comprises adding a second polymerization monomer CH ₂ =CR ¹ R ² for polymerization; wherein R ¹ Is -H or -CH ₃ ; R ² is -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ , -COO(CH ₂ ) _n CH ₃ ,n An integer between 0 and 14. The method for producing an ionic polymer film material according to claim 8, wherein the second monomer is used in an amount of from 2% to 50% based on the total mass of the polymerization monomer. The method for producing an ionic polymer film material according to any one of claims 7 to 9, wherein the colloidal protective agent is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone. The method for producing an ionic polymer film material according to claim 10, wherein the amount of the colloidal protective agent is from 5% to 30% based on the total weight of the polymerization monomer. The method for producing an ionic polymer film material according to any one of claims 7 to 9, wherein the crosslinking agent is a polymerizable monomer having two or more double bonds. The method for preparing an ionic polymer film material according to claim 12, wherein the crosslinking agent is divinylbenzene, trimethylolpropane triacrylate, dipropylene adipate or methylenebis acrylamide. The crosslinking agent is used in an amount of from 2.0% to 10.0% based on the total weight of the polymerization monomers. A lithium secondary battery comprising a separator, which is prepared according to any one of claims 1 to 4, or the ionic polymer film material according to any one of claims 1 to Made by the method. An ionic polymer/ceramic filler composite membrane material comprising a plurality of polymer colloidal particles modified with a sulfonate group on a plurality of surfaces and a plurality of ceramic filler particles dispersed in the colloidal particles of the polymer. The ionic polymer/ceramic filler composite membrane material according to claim 15, wherein the polymer colloidal particles are methyl acrylate-based polymer colloidal particles, and the ceramic filler particles are metal oxides or metal composite oxide particles. . The ionic polymer/ceramic filler composite membrane material of claim 16, wherein the ceramic filler particles comprise from 10% to 60% by weight of the ionic polymer/ceramic filler composite membrane material. The ionic polymer film material according to claim 16, wherein the sulfonate group is at least one selected from the group consisting of a vinyl sulfonate group and an allyl sulfonate group. Group, methallyl sulfonate group, allyloxyhydroxypropyl sulfonate group, hydroxypropyl sulfonate methacrylate group, 2-acrylamido-2-methylpropane Sulfonate group and styrene sulfonate group group. The ionic polymer/ceramic filler composite membrane material according to any one of claims 15 to 17, wherein the polymer colloidal particles have an average particle diameter ranging from 10 nm to 1.0 μm, and the average particle diameter of the ceramic filler particles. The range is from 10 nm to 5.00 μm. The ionic polymer/ceramic filler composite film material according to claim 18, wherein the ionic polymer/ceramic filler composite film has a thickness of from 10 μm to 40 μm. The invention relates to a method for preparing an ionic polymer/ceramic filler composite membrane material, which comprises: adding a reactive sulfonate surfactant as an emulsifier during the polymerization to form a plurality of polymer colloidal particles, and synthesizing a surface of a sulfonate One polymer modified colloidal emulsion; a ceramic filler is added to the polymer colloidal emulsion and uniformly mixed to obtain a polymer colloid/ceramic filler composite emulsion, which is a metal oxide particle or a metal composite oxidation The ionic polymer/ceramic filler composite film material is obtained by forming the polymer colloid/ceramic filler composite emulsion into a film and drying. The method for preparing an ionic polymer/ceramic filler composite membrane material according to claim 21, wherein the reactive sulfonate surfactant is a salt formed by a monosulfonate group and a cation, the sulfonate The group is a vinyl sulfonate group, an allyl sulfonate group, a methallyl sulfonate group, an allyloxy hydroxypropyl sulfonate group, a hydroxypropyl methacrylate group a sulfonate group, a 2-propenylguanidino-2-methylpropane sulfonate group, a styrene sulfonate group, or a combination thereof, and the cation is a lithium ion, a sodium ion, or a potassium ion. The method for preparing an ionic polymer/ceramic filler composite membrane material according to claim 22, wherein the preparation method comprises: a. synthesizing a polymer colloidal emulsion: adding a colloidal protective agent and distilled water to the reaction flask, and heating and stirring until Completely dissolved, adding the reactive sulfonate surfactant, a polymerization monomer and a crosslinking agent to be uniformly mixed, and then adding a starter to carry out polymerization to obtain the polymer colloidal emulsion; b. ceramic filler slurry Preparation: adding the ceramic filler particles and a dispersing agent in distilled water, dispersing uniformly, grinding and dispersing with a ball mill, and filtering through a 200-mesh sieve to obtain a ceramic filler slurry; c. in the polymer colloid The ceramic filler slurry is added into the emulsion, and after dispersing uniformly, the polymer colloid/ceramic filler composite emulsion is obtained, and the polymer colloid/ceramic filler composite emulsion is coated on the plastic substrate, and after drying, the ion polymerization is obtained. Material/ceramic filler composite film material. The method for preparing an ionic polymer/ceramic filler composite membrane material according to claim 23, wherein the polymerization reaction single system is methyl acrylate. The method for preparing an ionic polymer/ceramic filler composite membrane material according to claim 24, wherein in the step a., the preparation method further comprises adding a second polymerization monomer CH ₂ =CR ¹ R ² for polymerization; Wherein R ¹ is -H or -CH ₃ ; R ² is -C ₆ H ₅ , -OCOCH ₃ , -CN, -C ₄ H ₆ ON, -C ₂ H ₃ CO ₃ , -COO(CH ₂ ) _n CH ₃ , n is an integer between 0 and 14. The method for producing an ionic polymer/ceramic filler composite membrane material according to claim 25, wherein the second monomer is used in an amount of from 2% to 50% based on the total weight of the polymerization monomers. The method for preparing an ionic polymer/ceramic filler composite film material according to any one of claims 23 to 26, wherein the colloidal protective agent is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone; The colloidal protective agent is used in an amount of 5% to 30% based on the total weight of the polymerization monomer; the dispersing agent is polyvinyl alcohol, polyethylene oxide, polyacrylate or polyvinylpyrrolidone; In the material, the ceramic filler is contained in an amount of 80% to 95%, and the dispersant is contained in an amount of 5% to 20%; and the ceramic filler slurry has a solid content of 20% to 50%. A lithium secondary battery comprising an isolating film, the ionomer/ceramic filler composite film material according to any one of claims 15 to 20, or any one of claims 21 to 27 The preparation method is prepared.