KR20200085949A - Separator coating material for secondary battery of electric vehicle or energy storage system and coating separator manufacturing method using the same, middle or large sized secondary battery of electric vehicle or energy storage system - Google Patents

Abstract

The present invention relates to a separator coating material for a middle or large electric vehicle (EV) or energy storage system (ESS) secondary battery to realize production of a high power battery and a high capacity battery, a middle or large EV or ESS secondary battery separator manufacturing method using the same, and a middle or large EV or ESS secondary battery thereof. According to the present invention, the coating material is an applicable liquid slurry type polymer composite which comprises, with respect to 100 parts by weight of a polymer binder resin: 30 to 100 parts by weight of inorganic particles to increase mechanical strength and thermal transmissivity characteristics; 1 to 30 parts by weight of composite inorganic nanoparticles to increase the mechanical strength and thermal transmissivity characteristics; 1 to 10 parts by weight of a dispersant for dispersing the inorganic particles and the composite inorganic nanoparticles; and 1 to 70 parts by weight of a dispersion solvent for dissolving the polymer binder resin into an applicable liquid state.

Description

Separator coatings for medium and large-sized secondary batteries of EV or ESS and methods of manufacturing coating separators for medium-sized and secondary batteries of EV or ESS using the same, and medium-sized and large-sized secondary batteries of EV or ESS. USING THE SAME, MIDDLE OR LARGE SIZED SECONDARY BATTERY OF ELECTRIC VEHICLE OR ENERGY STORAGE SYSTEM}

The present invention relates to a method for manufacturing a separator for a medium- or large-sized secondary battery of EV or ESS and a method for manufacturing a separator for a medium-sized or large-sized secondary battery of EV or ESS and a secondary battery using the same, and more specifically, to secure thermal properties and safety at high temperature and at the same time, an electrolyte solution EV, which improves the wettability of the product and improves the performance of the battery by improving the thermal characteristics and safety, improves the compatibility with the electrolyte, and improves the impregnation ability. The present invention relates to a separator coating agent for medium-to-large-sized secondary batteries, a method for manufacturing a separator for a medium-sized secondary battery of EV or ESS using the same, and a medium-sized secondary battery of EV or ESS.

The secondary battery market has been in a sluggish state as the small IT market has reached maturity, but the secondary battery market is gradually growing as demand in mid-to-large-sized markets such as electric vehicles (EVs) and energy storage devices (ESSs) is increasing. .

Accordingly, in the secondary battery field, as the mid-to-large-sized battery market is expected to grow larger than the small-sized battery market, the electric vehicle (EV) and energy storage (ESS) markets are driving the future growth of the secondary battery.

However, as the scope of application of lithium secondary batteries, such as electric vehicles and energy storage devices, expands, there is a demand for high-capacity/high-power/high-safety and is intensifying. It is actively progressing.

In general, the secondary battery is composed of a positive electrode material and a negative electrode material, a separator and an electrolyte.

Of these, the separator plays a key role in preventing electrical shorts between the positive electrode and the negative electrode, and is a very important component that facilitates the movement of lithium ions while ensuring the safety of the secondary battery.

The separator may be representative of polyolefine-based materials having various advantages such as mechanical strength and chemical safety. In particular, polyethylene (PE) and polypropylene (PP) among polyolefine-based materials can be used. It is mainly used, and the separator for secondary batteries has numerous micro pores that can smoothly move lithium therein, so the performance and stability of the secondary battery depends on the pore size and distribution structure. .

However, the polyolefin-based material, which is mainly used as a separator material for a secondary battery, has a problem in that thermal safety is generally insufficient, resulting in significant heat shrinkage at high temperatures of 120°C or higher, and physical strength is weak, so that a short circuit is easily generated by an external impact. have. In addition, since it has a hydrophobic property itself, there is a disadvantage that it takes a lot of time for the electrolyte impregnation process due to its low wettability due to lack of mutual compatibility with the electrolyte. The ceramic coating method is a technique applied to compensate for these problems. .

In the conventional ceramic coating separator technology for secondary batteries, an active layer composed of inorganic particles and a binder polymer is coated on the surface of a polyolefin pin-based porous film, and the binder polymer includes an acrylic copolymer, a methacrylic copolymer, and (meth)acrylic-styrene. Copolymer, (meth)acryl-acrylonitrile copolymer, silicone-acrylic copolymer, epoxy-acrylic copolymer, polybutadiene, polyisoprene, butadiene-styrene random copolymer, isoprene-styrene random copolymer, acrylonitrile- Preparation of a ceramic coating separator using a resin selected from butadiene copolymer, acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene block copolymer, and styrene-butadiene-styrene-block copolymer Methods are disclosed.

However, when the acrylic resin is used as the main component of the binder polymer, the effect of improving the adhesiveness of the ceramic coating layer can be seen, but only such a binder polymer resin does not solve the problem of thermal stability at high temperature. On the contrary, there is a possibility that another problem may occur, and thus it is necessary to continuously improve.

In addition, in the case of a separator for a porous secondary battery made of a conventional polyolefin-based material, when the internal and external short circuits rapidly increase the current in the secondary battery and the temperature rises rapidly, the resistance to deformation of the separator becomes weak and it is difficult to maintain the stability of the secondary battery, Due to this, there is an unsuitable problem for use as a secondary battery of high power and high capacity.

[Document 1] Republic of Korea Patent Publication No. 10-1536560 [Document 2] Republic of Korea Patent Registration No. 10-1125013

The present invention has been devised in consideration of the above-described problems and the like, and it is possible to improve thermal properties and safety at high temperatures, which is a fundamental problem of polyolefin pin-based porous separators having electrochemical stability, through which EV or ESS Provides a separator coating agent for medium and large-sized secondary batteries of EV or ESS and a method of manufacturing a separator for medium and large-sized secondary batteries of EV or ESS, and a medium-sized secondary battery of EV or ESS to increase performance and extend the lifespan of There is a purpose.

The present invention allows the thermal characteristics and safety to be secured without damaging the pores of the separator, and at the same time improves the wettability to the electrolyte, and improves the impregnation ability by increasing the compatibility with the electrolyte for the separator. The purpose is to provide a medium- or large-sized secondary battery separation membrane coating agent for EV or ESS and a method for manufacturing a medium-sized secondary battery separation membrane for EV or ESS using the same, and to provide a medium-sized secondary battery for EV or ESS. .

The separator coating agent for medium and large-sized secondary batteries of EV or ESS according to the present invention for achieving the above object, 30 to 100 parts by weight of inorganic particles and mechanical strength for improving mechanical strength and heat transfer properties with respect to 100 parts by weight of the binder polymer resin 1 to 30 parts by weight of composite nano-inorganic powder particles to increase heat transfer properties, 1 to 10 parts by weight of dispersing agent for dispersing inorganic particles and composite nano-inorganic powder particles, dispersion for dissolving binder polymer resin in a liquid state that can be applied It is made of a polymer composite in the form of a liquid slurry that can be applied by mixing 1 to 70 parts by weight of a solvent; The dispersion solvent has a low boiling point and toluene, methanol, ethanol, cyclohexane, dimethylformamide, and trichloro to increase the solubility in the binder polymer resin. One or more solvents selected from Trichloro ethane, Chloroform, Methylene chloride, Tetrahydro furan, and Water; The inorganic particles are boehmite (Bohemite) or alumina (nano Aluminum oxide) is used, it is characterized in that the average particle size is 1.4㎛ or less.

Here, the composite nano-inorganic powder particles may be an alumina/boehmite composite.

In addition, the separator coating agent for medium and large-sized secondary batteries of EV or ESS according to the present invention for achieving the above object is stirred and mixed and dispersed inorganic particles and composite nano-inorganic powder particles and dispersant for improving and increasing mechanical strength and heat transfer characteristics After this, a binder polymer resin and a dispersing solvent are added thereto, and the mixture is stirred and mixed to prepare a polymer composite in the form of a liquid slurry that can be applied; The inorganic particles are Bohemite or alumina (nano Aluminum oxide) having an average particle diameter of 1.4 μm or less; The dispersion solvent has a low boiling point and toluene, methanol, ethanol, cyclohexane, dimethylformamide, and trichloro to increase the solubility in the binder polymer resin. One or more solvents selected from Trichloro ethane, Chloroform, Methylene chloride, Tetrahydro furan, and Water; It characterized in that it consists of 30 to 100 parts by weight of inorganic particles, 1 to 30 parts by weight of composite nano-inorganic powder particles, 1 to 10 parts by weight of dispersant, and 1 to 70 parts by weight of dispersing solvent relative to 100 parts by weight of the binder polymer resin.

Here, the composite nano-inorganic powder particles are alumina/boehmite composites; The binder polymer resin is an acrylic copolymer, a methacrylic copolymer, (meth)acrylic-styrene copolymer, (meth)acrylic-acrylonitrile copolymer, silicone-acrylic copolymer, epoxy-acrylic copolymer, polybutadiene, Polyisoprene, butadiene-styrene random copolymer, isoprene-styrene random copolymer, acrylonitrile-butadiene copolymer, acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene block copolymer, It may be any one or more selected from styrene-butadiene-styrene-block copolymer.

Here, by maintaining the solid content of 25 to 40% in the polymer composite in the form of the liquid slurry, it can be configured to increase the coating efficiency while securing the safety of the secondary battery.

In addition, the method of manufacturing a separator for a medium- or large-sized secondary battery of EV or ESS according to the present invention for achieving the above object, (A) Medium-to-large-sized secondary of EV or ESS made of a polymer composite in the form of a liquid slurry by the above-described composition components and composition ratio Providing a separator coating agent for a battery; (B) providing a polyolefin-based film having a microporous structure as a substrate; (C) forming a coating layer by applying a separator coating agent for medium or large-sized secondary batteries of EV or ESS made of a polymer composite in the form of a liquid slurry on one or both surfaces of a polyolefin-based film as a base material; (D) removing the dispersant component from the coating layer through a drying treatment and forming micropores on the coating layer.

Here, in step (A), after using a dispersion solvent to prepare a coating layer by applying a separator coating agent to the substrate through step (C) by providing a separator coating agent using a complex solvent having a different affinity. When the drying process is performed through step (D), the relatively high affinity solvent is first removed from the complex solvents having different affinity, and then the low affinity solvent is later removed, so that the binder polymer resin is first affinity. It can be processed to form fine pores on the coating layer formed by the membrane coating agent by being driven toward the high solvent to form phases to form fine pores, and then to form fine pores on the place where the low affinity solvent was located.

Here, the polyolefin-based film may be polyethylene (Polyethylene; PE) or polypropylene (Polypropylene; PP).

Here, the coating separation membrane may be manufactured to maintain a size of 0.05 to 0.01 μm and an air permeability of 50 to 90 cc/m 2, and a shrinkage of 3% or less with respect to micro pores formed on the coating layer.

In addition, the medium- or large-sized secondary battery of EV or ESS according to the present invention for achieving the above object is composed of a positive electrode material and a negative electrode material, including a separator and an electrolyte, and the separator is a coating separator for the medium and large-sized secondary battery described above. It is characterized in that it is composed of a coating separator for medium and large secondary batteries of EV or ESS manufactured by the method.

According to the present invention, it is possible to improve the thermal properties and safety at high temperature, which is a fundamental problem of the polyolefin pin-based porous separator having electrochemical stability, thereby improving the performance of EV or ESS for medium-to-large-sized secondary batteries and improving the service life. It can provide useful effects that can be extended.

The present invention can provide a separator that can improve the wettability of the electrolyte through the formation of a coating layer of excellent quality, while ensuring thermal properties and safety without damaging the pores of the separator, and the electrolyte for the separator It is possible to improve the impregnation ability by increasing the compatibility of the fruit while providing a useful effect to produce a high-power battery and a high-capacity battery.

1 is a schematic process diagram for explaining the manufacturing technology for a separator coating agent for a medium- or large-sized secondary battery of EV or ESS according to an embodiment of the present invention.
2 is a schematic manufacturing process diagram for explaining a method of manufacturing a coating separator for a medium-large size secondary battery of EV or ESS according to an embodiment of the present invention.
3 is a magnified SEM photograph showing a fabric used as a substrate for a separator in the present invention.
4 is a magnified SEM photograph showing the surface of a coating separator for a medium-to-large size secondary battery manufactured by the manufacturing method according to the present invention.
5 is a magnified SEM photograph showing a cross section having a coating layer forming structure of a coating separator for a medium-to-large size secondary battery manufactured by the manufacturing method according to the present invention.
6 is a magnified SEM photograph showing an enlarged detailed configuration of a coating layer for a coating separator for a medium-to-large size secondary battery manufactured by the manufacturing method according to the present invention.
7 is a graph showing the charging and discharging characteristics of a secondary battery having a coating separator for a medium-to-large size secondary battery manufactured by the manufacturing method according to the present invention.

When describing a preferred embodiment with reference to the accompanying drawings for the present invention is as follows, through the detailed description will be able to better understand the object and configuration of the present invention and features accordingly.

When explaining the separation coating agent for a medium or large-sized secondary battery of EV or ESS according to an embodiment of the present invention, and a method for manufacturing a coating separation film for a medium or large-sized secondary battery of EV or ESS using the same, and a medium or large-sized secondary battery of EV or ESS, with reference to FIGS. 1 to 7 As follows.

Separator coating agent for medium and large-sized secondary batteries of EV or ESS according to an embodiment of the present invention, 30 to 100 parts by weight of inorganic particles for improving mechanical strength and heat transfer properties for a separator for secondary batteries with respect to 100 parts by weight of a binder polymer resin, separator for secondary batteries 1 to 30 parts by weight of the composite nano-inorganic powder particles for increasing the mechanical strength and heat transfer properties, 1 to 10 parts by weight of the dispersing agent for dispersing the inorganic particles and the composite nano-inorganic powder particles, in a liquid state capable of applying a binder polymer resin It consists of a polymer complex in the form of a liquid slurry that is mixed with 1 to 70 parts by weight of a dispersion solvent to dissolve and slurried into a stable dispersion.

The binder polymer resin is an acrylic copolymer, a methacrylic copolymer, (meth)acrylic-styrene copolymer, (meth)acrylic- so as to improve adhesion when a ceramic coating layer is formed on the base material of a separator for a secondary battery. Acrylonitrile copolymer, silicone-acrylic copolymer, epoxy-acrylic copolymer, polybutadiene, polyisoprene, butadiene-styrene random copolymer, isoprene-styrene random copolymer, acrylonitrile-butadiene copolymer, acrylate copolymer Copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene block copolymer, styrene-butadiene-styrene-block copolymer may be used alone or in combination of two or more.

The inorganic particles are boehmite (Bohemite) or alumina (nano Aluminum oxide) is used, it is preferable to use an average particle size of 1.4㎛ or less.

Here, the boehmite or alumina has a small amount of moisture in the particles and excellent thermal characteristics, thereby minimizing heat shrinkage and maintaining the safety of the thermal deformation of the separator even if the temperature inside the battery rises rapidly due to a short circuit of the secondary battery. In charge, it can exert a function to ensure the safety of the secondary battery, it may be more preferable to use boehmite to further increase the functionality and battery safety according to the use of inorganic particles.

The composite nano-inorganic powder particles are preferably alumina/boehmite composites in which alumina and boehmite are mixed.

The dispersant is methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxymethyl ethylcellulose, hydroxypropylmethyl in order to increase the dispersing power in the membrane coating agent comprising the inorganic particles and the composite nano-inorganic powder particles Any one or more selected from cellulose, carboxymethyl cellulose, cellulose acetate, cellulose ether, and cellulose ester can be used.

Here, the dispersant is to have dispersibility with respect to the content of the inorganic particles and the composite nano-inorganic powder particles, when less than 1 part by weight, the viscosity of the separator coating agent is lowered and the problem that the components of the coating layer cannot be uniformly distributed When it is caused, and when it exceeds 10 parts by weight, the viscosity of the separator coating agent is too high, resulting in uneven coating thickness and problems in the manufacturing process of the entire separator.

The dispersion solvent has a low boiling point and toluene, methanol () methanol, ethanol, cyclohexane, dimethylformamide, and trichloro to increase the solubility in the binder polymer resin. Any one or more solvents selected from trichloro ethane, chloroform, methylene chloride, tetrahydrofuran, and water can be used.

Here, in the case of using water as a dispersion solvent in the selective application of the dispersion solvent, a coating layer is formed by applying a separator coating agent on the substrate of the separator for a secondary battery, and then there is a fear that volatile toxic substances are generated when the drying process is performed. Since there is no environment-friendly work, the separator for coating the secondary battery is removed by drying after forming the coating layer by applying a separator coating agent on the substrate of the separator for secondary batteries, so the components of the dispersion solvent remain on the ceramic coating layer. Will not be there.

Here, the dispersion solvent can increase the solubility in the binder polymer resin, thereby adjusting the content of the binder polymer resin, and to maintain a stable dispersion state for the separator coating agent, which is a polymer composite in the form of liquid slurry.

As shown in Fig. 1, a separator coating agent for a medium or large-sized secondary battery of EV or ESS according to the present invention comprising such a composition component and a composition ratio, inorganic particles and composite nanoparticles for improving and increasing mechanical strength and heat transfer characteristics in the manufacturing method thereof Each of the inorganic powder particles and the dispersant is weighed and provided (S10).

At this time, the inorganic particles and the composite nano-inorganic powder particles and dispersants are 30 to 100 parts by weight of inorganic particles, 1 to 30 parts by weight of the composite nano-inorganic powder particles, 1 to 10 dispersants, based on 100 parts by weight of the binder polymer resin mixed thereafter. It can be weighed to add by weight.

For the inorganic particles, bohemite or alumina (nano aluminum oxide) having an average particle diameter of 1.4 μm or less may be used, and boehmite is more preferably used.

The composite nano-inorganic powder particles are preferably alumina/boehmite composites in which alumina and boehmite are mixed.

The dispersant is methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxymethyl ethylcellulose, hydroxypropylmethyl in order to increase the dispersing power in the membrane coating agent comprising the inorganic particles and the composite nano-inorganic powder particles Any one or more selected from cellulose, carboxymethyl cellulose, cellulose acetate, cellulose ether, and cellulose ester can be used.

Here, the binder polymer resin to be added later and the dispersion solvent may also be weighed and provided, and the dispersion solvent may be weighed at 1 to 70 parts by weight with respect to 100 parts by weight of the binder polymer resin.

The inorganic particles and the composite nano-inorganic powder particles and the dispersant are weighed by a predetermined amount, respectively, and then put into a stirrer to stir and mix well with each other (S20).

After stirring and mixing the inorganic particles and the composite nano-inorganic powder particles and a dispersing agent, they are put into a dispersing device to disperse each component uniformly to be dispersed.

At this time, as a dispersing device, a bead mill, ball mill, roll mill, sand mill, ultrasonic disperser, homogenizer, or planetary mixer may be used. .

After the inorganic particles and the composite nano-inorganic powder particles and a dispersant are stirred and dispersed, a binder polymer resin to have adhesive strength upon coating and a dispersing solvent for stably dispersing it are added and stirred (S40). .

In this case, a stirrer or a dispersing device may be used, and 1 to 70 parts by weight of a dispersion solvent is added to 100 parts by weight of the binder polymer resin.

Here, the binder polymer resin is an acrylic copolymer, a methacrylic copolymer, a (meth)acrylic-styrene copolymer, a (meth)acryl-acrylonitrile copolymer, a silicone-acrylic copolymer, an epoxy-acrylic copolymer, Polybutadiene, polyisoprene, butadiene-styrene random copolymer, isoprene-styrene random copolymer, acrylonitrile-butadiene copolymer, acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene block Any one or more selected from copolymers and styrene-butadiene-styrene-block copolymers can be used.

The dispersion solvent is toluene, methanol, ethanol, cyclohexane, dimethylformamide, trichloro ethane, chloroform, methylene chloride chloride), tetrahydrofuran, or water (Weter).

Accordingly, it is possible to manufacture a polymer composite of a medium-sized secondary battery that can be coated by coating on a substrate of a separator for a secondary battery that can be stably dispersed and slurried by a composition ratio of the above-described composition and composition. can do.

At this time, the membrane coating agent for the medium-to-large-sized secondary battery is manufactured to maintain 25-40% solid content in the polymer composite in the form of a liquid slurry produced within the range of the composition ratio using the above-described composition components while increasing the coating efficiency on the substrate for the separator. It is preferable to configure to ensure the safety of the medium-to-large secondary battery manufactured by including such a coating separator.

On the other hand, it is possible to manufacture a coating separator for a medium- or large-sized secondary battery of EV or ESS by using a separator coating agent for a medium or large-sized secondary battery of EV or ESS manufactured by the above-described manufacturing method. As shown in FIG. 2, the method comprises a configuration including a separator coating agent providing step (S100), a substrate providing step for the separator (S200), a coating step (S300), and a drying step (S400).

The separation membrane coating agent providing step (S100) is a step of preparing and providing a separation membrane coating agent made of a polymer composite in the form of a liquid slurry according to the composition components and composition ratios described above with reference to FIG. 1.

This is to apply the separation membrane coating agent described above with reference to Figure 1, detailed description thereof will be omitted.

In addition, in the step of providing the separator coating agent (S100), in using a dispersion solvent, a separator coating agent may be provided using a composite solvent having different affinity, through which a separator coating agent is applied to a substrate to form a coating layer and then dried. In the process, it is possible to manufacture a coating separator having better quality, such as being able to form fine pores on the coating layer as a whole.

For example, methanol and cyclohexane having different affinity among dispersion solvents can be used as a composite solvent, and toluene and water having different affinity can be used as a composite solvent.

The step of providing a substrate for the separation membrane (S200) is a step of providing a polyolefin-based film having a microporous structure as a substrate for the separation membrane.

At this time, the polyolefin-based film is preferably used polyethylene (Polyethylene; PE) or polypropylene (Polypropylene; PP) in order to exhibit the properties of mechanical strength and chemical safety, but other materials in the polyolefin-based without being particularly limited thereto Can be used.

Here, the polyolefin-based film has a microporous structure in the tissue in the form of a fabric.

The polyolefin-based film used as the substrate for the separator shows that the fabric forms a microporous structure, as shown in the SEM (scanning electron microscope) picture shown in FIG. 3.

The coating step (S300) is a step of forming a ceramic coating layer by applying a separator coating agent made of a polymer composite in the form of a liquid slurry on one or both sides of a polyolefin-based film that is a substrate for the separator.

The drying step (S400) is a step of removing the dispersion solvent component from the coating layer and drying the pores on the coating layer through a drying treatment on the substrate for the separation membrane forming the ceramic coating layer by the separation membrane coating agent.

At this time, the drying step (S400) may be dried in various forms such as a natural drying method, a hot air drying method, and a far infrared drying method. The size of the pores formed on the coating layer is 0.05 to 0.01 μm and the air permeability is 50 to 90 cc. It is desirable to dry the /m 2 and maintain a shrinkage rate of 3% or less, thereby making it possible to manufacture a good quality medium-to-large secondary battery coating separator.

Here, when a composite solvent having different affinity is used when applying a dispersion solvent in the separation membrane coating agent providing step (S100), in the drying step (S400), a solvent having a relatively high affinity among the composite solvents having different affinity is relatively high. Is removed first, and the solvent with low affinity is removed later, and the binder polymer resin is first driven toward the solvent with high affinity, becomes phase change, forms fine pores, and then moves to the place where the solvent with low affinity is located, and then fine pores. To form.

Accordingly, by utilizing the action of a complex solvent having different affinity, it is possible to form fine pores evenly on the coating layer formed by the separator coating agent.

FIG. 4 shows the surface state by a SEM (scanning electron microscope) photograph scaled with respect to the coating separator for a medium-to-large size secondary battery manufactured by the above-described manufacturing method, and FIG. 5 shows a medium-to-large size secondary produced by the above-described manufacturing method. A cross-section having a coating layer formation structure by a SEM (scanning electron microscope) photograph scaled with respect to a coating separator for a battery is shown, and FIG. 6 shows a SEM scaled with respect to a coating separator for a medium-to-large size secondary battery manufactured by the above-described manufacturing method. (Scanning electron microscope) It shows an enlarged detailed configuration with a coating layer by photo.

On the other hand, the middle or large secondary battery of EV or ESS according to the present invention comprises a positive electrode material and a negative electrode material, a separator and an electrolyte.

At this time, the separation membrane is composed of a coating separation membrane for medium and large-sized secondary batteries of EV or ESS manufactured by the method of manufacturing a coating separation membrane for medium and large-sized secondary batteries as described above.

7 shows a graph showing charge and discharge characteristics for a secondary battery including a separator to which a coating separator for a medium-to-large size secondary battery manufactured by the above-described manufacturing method is applied, showing stable charging and discharging characteristics.

Meanwhile, in the present invention, various tests were performed on the separator coating agent having the above-described configuration as follows.

division Inorganic particles Composite nano-inorganic powder particles Dispersant Solid content (%) Composition 1 40 25 12 30 Composition 2 50 25 11 25 Composition 3 30 30 6 20 Composition 4 20 40 8 15 Composition 5 60 15 5 25

The composition in Table 1 shows the composition added based on 100 parts by weight of the binder polymer resin, and in the case of composition 1, the ratio of the inorganic particles to the boehmite composite powder is not a problem, but the ratio of the dispersant is high, so the viscosity ratio of the coating This may increase the viscosity of the coating may be good, but agglomeration occurs during coating.

In the case of composition 2, the ratio of the inorganic particles to the boehmite composite powder particles is not a problem, but the ratio of the dispersant is high, which also increases the viscosity of the coating, so that the viscosity of the coating may be good, but the composition may occur during coating. Similar to 1.

In the case of composition 3, there is a problem in the ratio of the inorganic particles to the boehmite composite powder particles, and the ratio of the dispersant to the solid content is high, which may cause problems in the safety of the secondary battery.

In the case of composition 4, there was a problem in the ratio of the inorganic particles to the boehmite composite powder particles, and the ratio of the dispersant to the solid content was high, which was similar to that of composition 3.

In the case of composition 5, there is no problem in the ratio of the inorganic particles to the boehmite composite powder particles, the ratio of the dispersant to the solid content is appropriate, and no clumping occurs during coating, and there is no problem in the safety of the secondary battery.

division Solid content (%) Binder polymer resin Inorganic particles Test 1 40 120 50 Test 2 50 100 50 Test 3 35 100 50

As shown in Table 2, in Test 1, there are many components of the binder polymer resin, so coating agglomeration and pore formation may be difficult, and a problem may arise in the safety of the secondary battery. There may be problems in the generation and safety of the secondary battery, and Test 3 has no problem in mixing the components of the solid content and the binder polymer resin and the inorganic particles, so that there is no problem in the safety of the coating treatment and the secondary battery. Accordingly, in the present invention, excellent A coating separator having a quality can be produced, and thus an excellent coating layer having fine pores on the coated separator side can be formed, thereby maintaining a suitable air permeability, maintaining a stable shrinkage rate, and improving the thermal characteristics and battery safety of the secondary battery. It can provide an advantage that can be secured.

The embodiments described above are merely for explaining preferred embodiments of the present invention, and will not be extremely limited to these embodiments, and various modifications made by those skilled in the art within the technical spirit and claims of the present invention. Modification or substitution of steps will fall within the technical scope of the present invention.

S100: Step of providing a separator coating agent
S200: Step for preparing the substrate for the separation membrane
S300: coating step
S400: drying step

Claims (10)

30 to 100 parts by weight of inorganic particles to improve mechanical strength and heat transfer properties, 100 to 1 part by weight of binder polymer resin, composite nanoparticles to increase mechanical strength and heat transfer properties 1 to 30 parts by weight of inorganic powder particles, inorganic particles and composite nanoparticles 1-10 parts by weight of a dispersant for dispersing the inorganic powder particles, 1 to 70 parts by weight of a dispersing solvent for dissolving the binder polymer resin in a liquid state that can be applied, is made of a polymer composite in the form of a liquid slurry that can be applied;
The dispersion solvent has a low boiling point and toluene, methanol, ethanol, cyclohexane, dimethylformamide, trichloro to increase the solubility in the binder polymer resin. One or more solvents selected from Trichloro ethane, Chloroform, Methylene chloride, Tetrahydro furan, and Water;
The inorganic particles are boehmite (Bohemite) or alumina (nano Aluminum oxide) is used, the average particle size of 1.4㎛ or less, characterized in that the separator coating agent for medium and large secondary batteries of ESS or EV. According to claim 1,
The composite nano-inorganic powder particles are alumina / boehmite composite EV or ESS separator coating agent for medium and large secondary batteries, characterized in that. After mixing and dispersing the inorganic particles and the composite nano-inorganic powder particles and dispersant to improve and increase the mechanical strength and heat transfer properties, a binder polymer resin and a dispersing solvent are added thereto, followed by stirring and mixing to form a polymer composite in the form of liquid slurry. Manufactured by;
The inorganic particles are Bohemite or alumina (nano Aluminum oxide) having an average particle diameter of 1.4 μm or less;
The dispersion solvent has a low boiling point and toluene, methanol, ethanol, cyclohexane, dimethylformamide, trichloro to increase the solubility in the binder polymer resin. One or more solvents selected from Trichloro ethane, Chloroform, Methylene chloride, Tetrahydro furan, and Water;
EV or ESS, characterized by consisting of 30 to 100 parts by weight of inorganic particles, 1 to 30 parts by weight of composite nano-inorganic powder particles, 1 to 10 parts by weight of dispersant, and 1 to 70 parts by weight of dispersion solvent relative to 100 parts by weight of the binder polymer resin Membrane coating agent for medium and large secondary batteries. The method of claim 1 or 3,
The composite nano-inorganic powder particles are alumina/boehmite composites;
The binder polymer resin is an acrylic copolymer, a methacrylic copolymer, (meth)acrylic-styrene copolymer, (meth)acrylic-acrylonitrile copolymer, silicone-acrylic copolymer, epoxy-acrylic copolymer, polybutadiene, Polyisoprene, butadiene-styrene random copolymer, isoprene-styrene random copolymer, acrylonitrile-butadiene copolymer, acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, butadiene-styrene block copolymer, Medium or large-sized secondary battery separator coating agent, characterized in that at least one selected from styrene-butadiene-styrene-block copolymer. The method of claim 1 or 3,
Separator coating agent for medium and large-sized secondary batteries of EV or ESS, characterized in that it is configured to secure the safety of the secondary battery while increasing the coating efficiency by maintaining the solid content of 25 to 40% in the liquid slurry-type polymer composite. In the method of manufacturing a separator for a medium or large-sized secondary battery of EV or ESS for producing a separator for a medium-sized or large-sized secondary battery of an electric vehicle (EV) or energy storage device (ESS)
(A) providing a separator coating agent for a medium or large-sized secondary battery of EV or ESS made of a polymer composite in the form of liquid slurry according to any one of claims 1 to 5;
(B) providing a polyolefin-based film having a microporous structure as a substrate;
(C) forming a coating layer by applying a separator coating agent for medium or large-sized secondary batteries of EV or ESS made of a polymer composite in the form of a liquid slurry on one or both surfaces of a polyolefin-based film as a base material;
(D) removing the dispersion solvent component from the coating layer through a drying treatment and forming fine pores on the coating layer; Method of manufacturing a coating separator for medium and large secondary batteries of EV or ESS, characterized in that it is manufactured, including. The method of claim 6,
In the step (A), the use of a dispersing solvent provides a separator coating agent by using a composite solvent having different affinity, and thus, after forming a coating layer by applying a separator coating agent to the substrate through step (C), the ( During the drying process through step D), the relatively high affinity solvent is first removed from the complex solvents having different affinity, and then the low affinity solvent is removed later, so that the binder polymer resin is the first high affinity solvent. EV or ESS, characterized in that micropores are formed on the coating layer formed by the separation membrane coating agent by forming a micropore in a place where a solvent with low affinity is formed again while being driven toward the phase. Method of manufacturing a coating separator for medium and large secondary batteries. The method of claim 6,
The polyolefin-based film is polyethylene (Polyethylene; PE) or polypropylene (Polypropylene; PP) characterized in that the EV or ESS coating separator manufacturing method for medium and large secondary batteries. The method of claim 6 or 7,
The coating separator is a coating separator for medium or large-sized secondary batteries of EV or ESS, characterized in that it is manufactured to maintain a size of 0.05 to 0.01 µm, an air permeability of 50 to 90 cc/m 2, and a shrinkage rate of 3% or less with respect to fine pores formed on the coating layer. Manufacturing method. In a medium- or large-sized secondary battery of EV or ESS comprising a positive electrode material and a negative electrode material, a separator and an electrolyte,
The separator is composed of a coating separator for a medium or large-sized secondary battery of EV or ESS manufactured by any one of claims 6 to 9, wherein the medium or large-sized secondary battery of EV or ESS.

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