System for measuring the shutdown temperature and the melting temperature of a partition

Abstract

This disclosure relates to a system for determining the shut-off temperature and melting temperature of a separator. The system includes a fixture with through-holes, a heating unit, a temperature sensor, a control unit, and a permeability determination unit. In this way, a novel system can be provided for determining the shut-off temperature and melting temperature of a separator by using its permeability (Gurley value).

Description

Technical Field

[0001] This disclosure relates to a system for determining the shutdown temperature and melting temperature of a separator. Specifically, this disclosure relates to a novel system that uses permeability to determine the temperature.

[0002] This application claims priority to Korean Patent Application No. 10-2020-0084323, filed in Korea on July 8, 2020, the disclosure of which is incorporated herein by reference. Background Technology

[0003] In recent years, energy storage technology has received increasing attention. As the application of energy storage technology expands to power mobile phones, cameras, laptops, and even electric vehicles, more and more efforts have been invested in the research and development of electrochemical devices.

[0004] Against this backdrop, electrochemical devices have received the most attention. Among these devices, the development of rechargeable secondary batteries has become a focal point. Recently, active research has been conducted on designing novel electrodes and batteries, aiming to improve capacity density and energy density in the development of such batteries.

[0005] Among commercially available rechargeable batteries, lithium-ion batteries, developed in the early 1990s, have attracted considerable attention because they offer higher operating voltages and significantly higher energy densities compared to conventional batteries such as Ni-MH batteries, Ni-Cd batteries, and lead sulfate batteries, which use aqueous electrolytes.

[0006] The separator used in lithium-ion secondary batteries physically isolates the positive and negative electrodes, preventing them from contacting each other and providing electrical insulation between them, while allowing lithium-ion transport. Specifically, the separator is known to have a significant impact on the characteristics and safety of the battery because it maintains insulation properties to prevent internal short circuits. More specifically, to improve the safety of lithium-ion secondary batteries, active research has been conducted on reducing the shutdown temperature and increasing the melting temperature of the separator. Therefore, accurately determining the shutdown and melting temperatures is crucial.

[0007] According to existing technology, the shrinkage behavior of the separator is observed by using thermomechanical analysis (TMA) while the temperature is increased. In addition, button-shaped monomers in which the separator is inserted are manufactured, and changes in ionic conductivity or resistance are determined while the temperature is increased.

[0008] However, when using this TMA instrument, the blockage of the pores that serve as lithium-ion transport channels is not directly determined, but rather indirectly determined by changes in the size of the separator, making it impossible to determine the accurate shutdown temperature. Furthermore, to determine the ionic conductivity, button-shaped monomers with the separator inserted must be prepared. Another problem is that the electrolyte evaporates when the temperature is increased for safety testing. Summary of the Invention

[0009] Technical issues

[0010] This disclosure is designed to address the problems of the prior art, and therefore aims to provide a novel system for directly determining the shutdown and melting temperatures of a separator by using the permeability of the separator. This system allows for more precise determination of the shutdown and melting temperatures. Furthermore, an operational advantage is that it eliminates the need to prepare separate button-type monomers to determine the shutdown or melting temperature of the separator. Another advantage is that no electrolyte is required during safety testing.

[0011] This disclosure is not limited to the technical problems described above. Other objectives of this disclosure may be understood from the following detailed description and will become more apparent in the exemplary embodiments of this disclosure.

[0012] Technical solutions

[0013] In one aspect of this disclosure, a system for determining the shutdown temperature and melting temperature of a separator is provided, according to any of the following embodiments.

[0014] According to the first embodiment,

[0015] A system is provided for determining the shutdown temperature and melting temperature of a separator, comprising:

[0016] Air permeability determining unit 170, which is configured to determine the air permeability (Gurley value) of the separator;

[0017] A first clamp 120 is configured to fix one side of the partition and has a first through hole through which air discharged from the permeability determination unit is introduced.

[0018] The second clamp 130 is arranged at a position relative to the first clamp based on the partition, is configured to fix the other side of the partition, and has a second through hole through which air passing through the first through hole and the pores in the partition is introduced.

[0019] Heating unit 140 is configured to heat either the first clamp or the second clamp;

[0020] Temperature sensor 150 is configured to measure the temperature of either the first or second clamp; and

[0021] Control unit 160 is configured to control the heating unit and temperature sensor.

[0022] The control unit calculates the shut-off temperature and melting temperature of the separator by using the temperature measured by the temperature sensor as a function of time and the air permeability (Gurley value) of the separator determined by the air permeability determination unit.

[0023] According to the second embodiment,

[0024] A system is provided for determining the shutdown temperature and melting temperature of the separator defined in the first embodiment.

[0025] The air permeability determination unit is linked to the first clamp, and the control unit is linked to the first clamp and the second clamp.

[0026] According to the third embodiment,

[0027] A system is provided for determining the shutdown temperature and melting temperature of a separator as defined in a first or second embodiment, wherein a heating unit and a temperature sensor are linked to at least one of a first fixture and a second fixture.

[0028] According to the fourth embodiment,

[0029] A system is provided for determining the shutdown temperature and melting temperature of a separator defined in any one of the first to third embodiments, wherein the separator is inserted between a first clamp and a second clamp.

[0030] According to the fifth embodiment,

[0031] A system is provided for determining the shut-off temperature and melting temperature of a separator defined in any of the first to fourth embodiments, the system further comprising a display unit configured to display the temperature as a function of time on an X-axis and the air permeability (Gurley value) of the separator as a function of time on a Y-axis.

[0032] According to the sixth embodiment,

[0033] A system is provided for determining the shut-off temperature and melting temperature of a separator defined in any of the first to fifth embodiments, wherein the shut-off temperature (A) is a temperature corresponding to a permeability (Gurley value) of 100,000 sec / 100 cc as the temperature increases as a function of time.

[0034] According to the seventh embodiment,

[0035] A system is provided for determining the shutdown temperature and melting temperature of a separator defined in any of the first to sixth embodiments.

[0036] The melting temperature (B) is the temperature at which the separator is damaged and the permeability (Gurley value) of the separator begins to decrease after the shutdown temperature, and the melting temperature is the temperature corresponding to the permeability (Gurley value) of 100,000 sec / 100cc after the shutdown temperature.

[0037] According to the eighth embodiment,

[0038] A system is provided for determining the shut-off temperature and melting temperature of a separator defined in any of the first to seventh embodiments, wherein the average diameter of the holes in the first through hole and the holes in the second through hole is 2-15 mm.

[0039] According to the ninth embodiment,

[0040] A system is provided for determining the shutdown temperature and melting temperature of a separator defined in any one of the first to eighth embodiments, the system further comprising a storage unit configured to record the calculated shutdown temperature and melting temperature of the separator.

[0041] According to the tenth embodiment,

[0042] A system is provided for determining the shutdown temperature and melting temperature of a separator defined in any of the first to ninth embodiments, the system further comprising a display unit configured to display the calculated shutdown temperature and melting temperature of the separator.

[0043] Beneficial effects

[0044] According to embodiments of this disclosure, a novel system can be provided that directly determines the shut-off temperature and melting temperature of the separator by using the air permeability of the separator.

[0045] Compared to traditional systems, this system requires a shorter determination time and allows for more precise determination of shutdown and melting temperatures.

[0046] Furthermore, it has the advantage of eliminating the need to prepare separate button-shaped monomers to determine the shut-off or melting temperature of the separator. Another advantage is that no electrolyte is required during safety testing. Attached Figure Description

[0047] The accompanying drawings illustrate preferred embodiments of the present disclosure and are used together with the foregoing disclosure to provide a further understanding of the technical features of the present disclosure, and therefore the present disclosure is not to be construed as limited to the drawings.

[0048] Figure 1 This is a schematic block diagram illustrating the functional configuration of a system for determining the shutdown temperature and melting temperature of a separator according to an embodiment of the present disclosure.

[0049] Figure 2This is a schematic diagram illustrating the configuration of a system for determining the shutdown temperature and melting temperature of a separator according to an embodiment of the present disclosure.

[0050] Figure 3 This is a flowchart illustrating a method for determining the shutdown temperature and melting temperature of the separator.

[0051] Figure 4 This is a graph showing the shut-off temperature and melting temperature of the separator, plotted using the temperature and permeability (Gurley value) of the separator as a function of time, for test objects prepared according to Examples 1 and 2 and Comparative Examples 1 and 2. Detailed Implementation

[0052] Preferred embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general or dictionary meaning, but rather is interpreted based on the principle of allowing the inventors to properly define the terminology for the best explanation, and on the meanings and concepts corresponding to the technical solutions of the present disclosure.

[0053] Therefore, the description given herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of this disclosure. It should be understood that other equivalents and modifications may be made thereto without departing from the scope of this disclosure.

[0054] First refer to Figure 1 The overall configuration of a system for determining the shutdown temperature and melting temperature of a separator, according to an embodiment of this disclosure, is described.

[0055] Figure 1 This is a schematic diagram illustrating the configuration of a system for determining the shutdown temperature and melting temperature of a separator according to an embodiment of the present disclosure.

[0056] Reference Figure 1 The system 100 for determining the shut-off temperature and melting temperature of the separator according to an embodiment of the present disclosure is a system capable of evaluating the safety of the test object 110, and includes fixtures 120 and 130, a heating unit 140, a temperature sensor 150, a control unit 160, and an air permeability determination unit 170. Furthermore, the system 100 for determining the shut-off temperature and melting temperature of the separator according to an embodiment of the present disclosure may optionally further include a storage unit 180 and a display unit 190 (not shown).

[0057] Test object 110 may be a separator. Any separator may be used without particular limitations, as long as it physically isolates the contact between the negative and positive electrodes and has electrical insulating properties. An insulating film with high ion permeability and mechanical strength, inserted between the positive and negative electrodes, may be used as the separator. The separator has pores, typically with a pore size of 0.01-10 μm and a thickness of 5-300 μm. Non-limiting examples of separators may include sheets or nonwovens made of chemically resistant and hydrophobic olefin polymers (such as polyethylene or polypropylene), glass fibers, polyethylene, etc. In some cases, the separator may further include an organic / inorganic porous coating comprising inorganic particles and a binder polymer on its outermost surface to enhance the separator's heat resistance and stability. The separator may be a solid electrolyte. Here, any porous polymer substrate, binder polymer, and inorganic particles may be used without particular limitations, as long as they are conventionally used in the art. In variations, the separator may include a porous polymer substrate, such as a cross-linked polyolefin comprising polyolefins, alkoxy-containing vinylsilanes, and a cross-linking catalyst.

[0058] The separator used in lithium-ion secondary batteries physically isolates the positive and negative electrodes, preventing them from contacting each other and providing electrical insulation between them, while allowing lithium-ion transport. Specifically, the separator is known to have a significant impact on the characteristics and safety of the battery because it maintains insulation properties to prevent internal short circuits. More specifically, to improve the safety of lithium-ion secondary batteries, active research has been conducted on reducing the shutdown temperature and increasing the melting temperature of the separator. Therefore, accurately determining the shutdown and melting temperatures is crucial.

[0059] According to existing technology, the shrinkage behavior of the separator is observed by using thermomechanical analysis (TMA) while the temperature is increased. In addition, button-shaped monomers in which the separator is inserted are manufactured, and changes in ionic conductivity or resistance are determined while the temperature is increased.

[0060] However, when using this TMA instrument, the blockage of the pores that serve as lithium-ion transport channels is not directly determined, but rather indirectly determined by changes in the size of the separator, making it impossible to determine the accurate shutdown temperature. Furthermore, to determine the ionic conductivity, button-shaped monomers with the separator inserted must be prepared. Another problem is that the electrolyte evaporates when the temperature is increased for safety testing.

[0061] Conversely, according to embodiments of this disclosure, the shut-off and melting temperatures of the separator are directly determined by using changes in the permeability (Gurley value) of the separator, which depends on temperature variations. Therefore, compared to conventional systems, this provides a shorter determination time and allows for more precise determination of the shut-off and melting temperatures.

[0062] As used herein, the term "shut-down temperature" refers to a specific temperature point in the region where the permeability (Gurley value) of the separator increases rapidly. Specifically, the shutdown temperature can be calculated from experimental values. More specifically, the shutdown temperature can be calculated using the control unit 160 described below.

[0063] For example, as temperature increases as a function of time, the shutdown temperature can be determined as the temperature at which the increase in permeability decreases within the temperature range corresponding to permeability (Gurley value) of 10000 sec / 100cc or higher.

[0064] According to embodiments of this disclosure, the shut-off temperature can be determined as the temperature (A) at a specific point in a region with a permeability of 10,000 sec / 100cc to 100,000 sec / 100cc. According to a particular embodiment, the shut-off temperature can be the temperature at a point corresponding to a permeability of 10,000 sec / 100cc or 100,000 sec / 100cc.

[0065] Reference Figure 4 The diagram shows that after the permeability rapidly increases from 10,000 sec / 100cc to 100,000 sec / 100cc, it no longer increases above 100,000 sec / 100cc but remains constant. Therefore, it can be seen that even when the shut-off temperature is defined as a specific point A, in such a region, it does not show a significant deviation from the point where the permeability increment actually decreases.

[0066] As used herein, the term "melt-down temperature" refers to the temperature at which the separator breaks down as a function of time. In other words, the melt-down temperature is the temperature at which the separator breaks down after the shutdown temperature and the separator's permeability (Gurley value) begins to decrease. Specifically, the melt-down temperature can be calculated from experimental values. More specifically, the melt-down temperature can be calculated using the control unit 160 described below.

[0067] According to embodiments of this disclosure, the melting temperature can be determined as the temperature (B) at a specific point in a region with an air permeability of 100,000 sec / 100 cc to 1,000 sec / 100 cc. According to a particular embodiment, the melting temperature can be the temperature at a point corresponding to an air permeability of 10,000 sec / 100 cc.

[0068] Reference Figure 4 The figure shows that after the increase in breathability was maintained, the breathability rapidly decreased from 100,000 sec / 100cc to 10,000 sec / 100cc.

[0069] Therefore, it can be seen that even when the melting temperature is determined to be a specific point B, in such a region, it does not show a significant deviation from the point where permeability actually begins to decrease.

[0070] According to embodiments of this disclosure, the shutdown temperature can be specifically determined as the temperature at a point corresponding to 100,000 sec / 100cc of air permeability, and the melting temperature can be specifically determined as the temperature at a point corresponding to 100,000 sec / 100cc of air permeability or the temperature at a point corresponding to 10,000 sec / 100cc of air permeability.

[0071] Figure 4 This is a schematic diagram illustrating the shutdown temperature and melting temperature defined in this paper. (Refer to...) Figure 4 The X-axis represents temperature (°C) as a function of time. (See reference...) Figure 4 The Y-axis represents the air permeability (Gurley value) of the separator as a function of time (sec / 100cc). Figure 4 In this context, as temperature increases as a function of time, the shutdown temperature is the temperature at a specific point in the region corresponding to permeability (Gurley value) from 10000 sec / 100 cc to 100000 sec / 100 cc, or the temperature at the point where the permeability increment decreases, and can be denoted by "A". Figure 4 In this context, melting temperature is the temperature at a specific point in the region corresponding to permeability (Gurley value) from 100,000 sec / 100 cc to 1,000 sec / 100 cc after the shutdown temperature, or the temperature at which permeability begins to decrease, and can be represented by "B".

[0072] Reference Figure 1 and Figure 2The system includes a first clamp 120 configured to secure one side of a separator serving as the test object 110, and having a first through-hole through which air exhausted from the permeability determination unit is introduced. Furthermore, the system includes a second clamp 130 disposed at a position relative to the separator and the first clamp, configured to secure the other side of the separator, and having a second through-hole through which air passing through the first through-hole and the pores in the separator is introduced.

[0073] Fixtures 120 and 130 are used to hold the test object 110 to be evaluated in terms of safety features. The fixtures may include a first fixture 120 and a second fixture 130 facing each other. The fixtures 120 and 130 may be made of any material, as long as the material secures the test object 110.

[0074] Each of the heating unit 140 and the temperature sensor 150 can be arranged on at least one of the first clamp and the second clamp. Furthermore, a separator 110 can be inserted between the first clamp 120 and the second clamp 130. Simultaneously, a through hole formed in the first clamp or the second clamp allows penetration from the side of the first clamp or the second clamp to the top and bottom surfaces of the first clamp or the second clamp.

[0075] Reference Figure 1 and Figure 2 The heating unit 140 can be installed in at least one of the first and second clamps. For example, the heating unit can be linked to at least one of the first and second clamps. The heating unit 140 heats the test object 110 through the heating clamps. The control unit 160 can be electrically connected to the heating unit 140 and can control the operation of the heating unit 140. Therefore, according to the control command input from the control unit 160, the heating unit 140 heats the test object 110 to a predetermined temperature. Finally, a graph showing the shutdown temperature and melting temperature can be plotted by the display unit 190.

[0076] Preferably, the heating unit 140 can be a heat wire installed in the second clamp 130. The heat wire can be installed in the first clamp 120 instead of the second clamp 130, or it can be installed in both the first clamp 120 and the second clamp 130. In a variation, the heat wire can be installed on another surface of the first clamp 120 or the second clamp 130 that contacts the test object. Specifically, the heating unit 140 can gradually increase the temperature as a function of time. Here, the heating unit 140 can be electrically connected to the control unit 160 and can provide heat to the first clamp or the second clamp under the control of the control unit 160. In this way, the thermal characteristics of the spacer inserted between the first clamp and the second clamp can be observed. The heating unit 140 can be electrically connected to the temperature sensor 150.

[0077] Temperature sensor 150 can be electrically connected to each of the first clamp 120 and the second clamp 130. In other words, temperature sensor 150 can be connected to both ends of each clamp. For example, temperature sensor 150 can be directly connected to each of the first clamp 120 and the second clamp 130. For example, temperature sensor 150 can be disposed in the first clamp 120 or the second clamp 130.

[0078] Temperature sensor 150 measures the temperature of the partition heated by heating unit 140.

[0079] According to this disclosure, when the temperature sensor 150 measures the temperature of the partition, the partition is at room temperature before the heated unit 140 raises its temperature. However, when the heating unit 140 supplies heat to the partition, the temperature of the partition rises over a predetermined period of time. The temperature sensor 150 measures the temperature rise under these conditions.

[0080] According to this disclosure, the air permeability determining unit 170 is directly linked to at least one of the first clamp and the second clamp. For example, the air permeability determining unit 170 may be directly linked to either the first clamp or the second clamp. For example, the air permeability determining unit may be linked to the first clamp.

[0081] Specifically, the air permeability (Gurley value) determination unit 170 determines the air permeability (Gurley value) based on the following principles. The air permeability determination unit is directly linked to either the first clamp 120 or the second clamp 130. Furthermore, when air is injected at a predetermined pressure into the test object 110 combined with the first clamp 120 and the second clamp 130, the injected air undergoes pressure variations depending on the characteristics of the separator serving as the test object 110. The air permeability (Gurley value), i.e., the time required for a unit volume of air to pass through the separator, can be determined using the varying air pressure. For example, air permeability can be determined using an Oken air permeability tester (Asahi Seiko Co., Ltd.). For example, air permeability can be determined by measuring the time required for 100cc of air to pass through the separator using an Oken air permeability tester.

[0082] According to this disclosure, the control unit 160 controls the heating unit 140 and the temperature sensor 150. Furthermore, the control unit 160 calculates the shut-off temperature and melting temperature of the separator by using the temperature measured by the temperature sensor 150 as a function of time and the air permeability (Gurley value) of the separator determined by the air permeability determination unit 170.

[0083] The control unit 160 can be electrically connected to each of the heating unit 140, temperature sensor 150, air permeability determination unit 170, first clamp 120, and second clamp 130. For example, the control unit 160 can be directly linked to the heating unit 140, temperature sensor 150, and air permeability determination unit 170. For example, the control unit can be linked to the first clamp 120 and second clamp 130.

[0084] The control unit 160 receives the temperature measured by the temperature sensor 150 as a function of time, and the air permeability (Gurley value) of the separator as a function of time, determined by the air permeability determination unit 170. Simultaneously, the heating unit 140 supplies heat to the separator at a rate that increases with time. The temperature and air permeability can be represented by the X-axis and Y-axis, respectively, to calculate the shut-off temperature and melting temperature of the separator. Here, the X-axis represents the temperature (°C) as a function of time, and the Y-axis represents the air permeability of the separator (sec / 100cc) (Gurley value) as a function of time.

[0085] The control unit 160 can calculate the shut-off temperature and melting temperature of the separator based on the temperature and permeability (Gurley value) received from the temperature sensor 150 and the permeability determination unit 170.

[0086] The control unit 160 can store the calculated shut-off temperature and melting temperature of the separator in the storage unit 180. Then, as the temperature increases as a function of time, the temperature corresponding to the permeability (Gurley value) at 100,000 sec / 100 cc is defined as the shut-off temperature, and the temperature at the point where the permeability (Gurley value) begins to decrease from 100,000 sec / 100 cc after the shut-off temperature is defined as the melting temperature.

[0087] Storage unit 180 is not limited to any particular type, as long as it is a storage medium capable of recording and erasing information. For example, storage unit 180 can be RAM, ROM, EEPROM, DRAM, SDRAM, a resistor, a hard disk, an optical recording medium, or a magnetic recording medium. Storage unit 180 can be electrically connected to control unit 160 via a data bus, etc., and thus be accessible by control unit 160. Storage unit 180 can store, update, erase, and / or transmit data generated during the execution of programs and / or control logic including various control logics executed by control unit 160. Storage unit 180 can be logically divided into two or more units. Storage unit 180 can be included in control unit 160, but is not limited thereto.

[0088] The control unit 160 can display the calculated shut-off temperature and melting temperature of the separator on the display unit 190.

[0089] The display unit 190 can output the shut-off temperature and melting temperature of the separator determined by the control unit 160 for the test object 110 via an external display. For example, the calculated results of the shut-off temperature and melting temperature of the separator can be output to the display in the form of letters, numbers, images, etc. The calculated results of the shut-off temperature and melting temperature of the separator may include the shut-off temperature of the separator, the shut-off temperature change curve, the melting temperature, the melting temperature change curve, or a combination thereof.

[0090] The display unit 190 can be electrically connected to the control unit 160, and the control unit 160 can output the shutdown temperature, melting temperature, or their variation curves through the display unit 190. The display unit 190 may include a liquid crystal display, an organic light-emitting diode display, or a light-emitting diode display, but the scope of this disclosure is not limited thereto.

[0091] Figure 2 This is a schematic diagram illustrating the configuration of a system for determining the shutdown temperature and melting temperature of a separator according to an embodiment of the present disclosure.

[0092] Reference Figure 2 The system 100 for determining the shut-off temperature and melting temperature of the separator may include two clamps 120 and 130 facing each other, a heating unit 140 linked to the two clamps 120 and 130, a temperature sensor 150, a control unit 160, and an air permeability determination unit 170. The system may further include a storage unit 180 and a display unit 190.

[0093] Reference Figure 2 The system 100 for determining the shut-off temperature and melting temperature of the separator can clamp the test object 110 between the first clamp 120 and the second clamp 130.

[0094] Figure 3 This is a flowchart illustrating a method for determining the shutdown temperature and melting temperature of a separator according to an embodiment of the present disclosure.

[0095] Reference Figure 1 and Figure 3 In the method for determining the shut-off temperature and melting temperature of a separator according to an embodiment of the present disclosure, the test object 110—that is, the separator—is first inserted between a first clamp and a second clamp facing each other (S110). Therefore, the test object 110 is fixed between clamps 120 and 130, and the fixing method is not particularly limited.

[0096] The test object can be a separator. For example, the test object—that is, the separator—can be the porous polymer substrate itself, and can have a porous coating comprising inorganic particles and a binder polymer on at least one surface of the separator.

[0097] For example, when the test object has a porous coating, the test object 110 can be prepared as follows. First, a slurry containing inorganic particles, a binder polymer, and an organic solvent is prepared.

[0098] There is no particular limitation on the inorganic particles as long as they are electrochemically stable. In other words, there is no particular limitation on the inorganic particles that can be used herein as long as they do not cause oxidation and / or reduction within the operating voltage range of the applicable electrochemical device (e.g., 0 - 5V based on Li / Li+). Specifically, when inorganic particles having a high dielectric constant are used as the inorganic particles, the ionic conductivity of the electrolyte can be improved by increasing the dissociation degree of electrolyte salts such as lithium salts in the liquid electrolyte.

[0099] For the above reasons, the inorganic particles can be inorganic particles having a dielectric constant of 5 or more, inorganic particles having lithium ion transport ability, or a combination thereof.

[0100] The inorganic particles having a dielectric constant of 5 or more can include any one selected from the group consisting of: Al2O3, SiO2, ZrO2, AlO(OH), TiO2, BaTiO3, Pb(Zr x Ti 1-x )O3 (PZT, where 0 < x < 1), Pb 1-x La x Zr 1-y Ti y O3 (PLZT, where 0 < x < 1, 0 < y < 1), (1 - x)Pb(Mg 1 / 2 Nb 2 / 3 )O 3-x PbTiO3 (PMN - PT, where 0 < x < 1), hafnium dioxide (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZO3, and SiC, or a mixture of two or more thereof.

[0101] The inorganic particles having lithium ion transport ability can be any one selected from the group consisting of: lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) x O y - based glass (1 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La yTiO3, where 0 < x < 2 and 0 < y < 3), lithium thiophosphate germanium (Li x Ge y P z S w , where 0 < x < 4, 0 < y < 1, 0 < z < 1, and 0 < w < 5), lithium nitride (Li x N y , where 0 < x < 4 and 0 < y < 2), SiS2-based glass (Li x Si y S z , where 0 < x < 3, 0 < y < 2, and 0 < z < 4) and P2S5-based glass (Li x P y S z , where 0 < x < 3, 0 < y < 3, and 0 < z < 7), or a mixture of two or more of them.

[0102] In addition, there is no special limitation on the average particle size of the inorganic particles. However, the inorganic particles preferably have an average particle size of 0.001 - 10 μm in order to form a coating with a uniform thickness and provide appropriate porosity. Specifically, the average particle size of the inorganic particles can preferably be 100 nm or more, 150 nm or more, or 200 nm or more, and 1000 nm or less, 900 nm or less, 800 nm or less, or 700 nm or less.

[0103] There is no special limitation on the binder polymer as long as it can bind the inorganic particles to each other. Non-limiting examples of the binder polymer may include: polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - trichloroethylene, polymethyl methacrylate, butyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene - vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, etc.

[0104] The organic solvent preferably has a solubility parameter similar to that of the binder polymer to be used and has a low boiling point. This is because such a solvent helps with uniform mixing and subsequent solvent removal. Non-limiting examples of the solvents that can be used include any one selected from the following: water, acetone, tetrahydrofuran, dichloromethane, chloroform, dimethylformamide, N-methyl-2-pyrrolidone, methyl ethyl ketone, and cyclohexane, or a mixture of two or more of them.

[0105] Next, a slurry containing multiple inorganic particles, a binder polymer, and an organic solvent is applied to the test object 110—that is, the separator—and then dried to obtain a separator with a porous coating comprising inorganic particles bonded together by the binder polymer. While there are no particular limitations on the process for applying the slurry to form the porous coating, a slot coating process or an immersion coating process is preferred. The slot coating process involves coating the entire surface of the separator with a slurry supplied through a slot die, and the coating thickness can be controlled according to the flux supplied by a metering pump. Furthermore, the immersion coating process involves immersing the substrate in a tank containing the slurry for coating, and the coating thickness can be controlled according to the slurry concentration and the rate at which the substrate is removed from the tank. Additionally, for more precise control of the coating thickness, post-metering can be performed after immersion using a Mayer rod or similar method.

[0106] The slurry-coated separator can then be dried in a dryer, such as an oven, to form a porous coating on at least one surface of the separator.

[0107] Reference Figure 1 and Figure 3 The test object 110 is inserted between the first clamp 120 and the second clamp 130. Then, while heating the test object 110, the air permeation time of the separator as a function of time—that is, the air permeability (Gurley value)—and the temperature change of the separator as a function of time (S120) are measured.

[0108] Then, the control unit 160 supplies heat that increases over time between the upper clamp 120 and the lower clamp 130 of the inserted test object 110 using the heating unit 140. Here, the control unit 150 measures the temperature continuously input from the heating unit 140 via the temperature sensor 150 and records the temperature in the storage unit 180. In addition, the control unit 160 stores the air permeability (Gurley value) received from the air permeability determination unit 170 in the storage unit 180.

[0109] Subsequently, the control unit 160 determines the melting temperature and shut-off temperature of the separator (S130) based on the temperature change as a function of time received from the temperature sensor 150 and the air permeability (Gurley value) of the separator received from the air permeability determination unit 170.

[0110] The control unit 160 can output the determined melting temperature and shutdown temperature via the display unit 190. Furthermore, the control unit can display the melting temperature and shutdown temperature variation curves of the separator on the display unit 190. Here, the control unit 160 can refer to data recorded in the storage unit 170.

[0111] According to this disclosure, any electrochemical device can be used without special restrictions, as long as it includes electrodes with inherent conductivity and porosity. For example, the system can be applied to secondary batteries, supercapacitors, storage batteries, fuel cells, etc.

[0112] According to embodiments of this disclosure, the secondary battery may include a lithium-ion secondary battery, a lithium polymer secondary battery, a lithium metal secondary battery, or a lithium-ion polymer secondary battery.

[0113] The following examples illustrate in more detail a method for evaluating the insulation properties of separators used in electrochemical devices, depending on the structure of the test object. However, the examples below are for illustrative purposes only, and the scope of this disclosure is not limited thereto.

[0114] Example 1

[0115] The following separator is prepared.

[0116] First, 10.5 kg of high-density polyethylene (Daehan Oil & Chem. VH035) with a weight average molecular weight of 600,000 was used as the polyolefin, 19.5 kg of liquid paraffin oil (Kukdong Oil & Chem. LP 350F, 68 cSt) was used as the diluent, 450 g of trimethoxyvinylsilane was used as the alkoxy-containing vinylsilane, 6 g of dibutyltin dilaurate was used as the crosslinking catalyst, and 6 g of 2,5-dimethyl-2,5-bis(peroxytert-butyl)hexane (DHBP) was used as the initiator. These were immediately introduced into the extruder and mixed therein.

[0117] Next, reactive extrusion is carried out at a temperature of 200°C to obtain a silane-grafted polyolefin composition.

[0118] The resulting silane-grafted polyolefin composition was molded into sheets using a T-die and cold casting rolls. Then, biaxial orientation was performed using a tenter frame sequential orientation machine. Both MD and TD orientations were performed at a ratio of 7.0. The orientation temperatures for MD and TD were 110°C and 125°C, respectively.

[0119] Subsequently, the oriented sheet was extracted with dichloromethane and heat-fixed at 126°C to obtain a porous membrane. The porous membrane was crosslinked at 85°C and 85% relative humidity for 24 hours to obtain a crosslinked polyolefin separator. The thickness of the obtained separator was 9.5 μm.

[0120] The thermal properties of the prepared separator were determined using the system according to this disclosure at a heating rate of 5 °C / min. The results are shown in Table 1 below.

[0121] Example 2

[0122] The separator is prepared as follows.

[0123] First, 9.45 kg of high-density polyethylene (Daehan Oil & Chem. VH035) with a weight average molecular weight of 600,000 was used as the polyolefin, 1.05 kg of polyethylene cooctene with a melt index (ASTM D1238) of 1.2 g / 10 min was used as the polyolefin elastomer, and 19.5 kg of liquid paraffin oil (Kukdong oil & Chem. LP 350F, 68 cSt) was used as the diluent. The mixture was then introduced into the extruder and mixed at a temperature of 200°C.

[0124] The prepared polyethylene composition was molded into sheet form using a T-die and cold casting rolls. Then, biaxial orientation was performed using a tenter frame sequential orientation machine, followed by MD orientation and then TD orientation. Both MD and TD orientations were performed at a ratio of 7.0. The orientation temperatures for MD and TD were 110°C and 125°C, respectively.

[0125] Subsequently, the first and second diluents in the oriented sheet were extracted with dichloromethane and then heat-fixed at 126°C to obtain a porous membrane. The thickness of the resulting separator was 9.3 μm.

[0126] The thermal properties of the prepared separator were determined using the system according to this disclosure at a heating rate of 5 °C / min. The results are shown in Table 1 below.

[0127] Comparison Example 1

[0128] The thermal properties of the separator according to Example 1 were determined using a thermomechanical analysis (TMA) system. The results are shown in Table 1 below.

[0129] Comparison Example 2

[0130] A separator according to Example 1 was inserted between the positive and negative electrodes to obtain a button-shaped monomer. The ionic conductivity of the separator was then determined at a heating rate of 5 °C / min. The results are shown in Table 1 below.

[0131] [Table 1]

[0132]

[0133] In Table 1, “accuracy” refers to how accurately the shutdown temperature and melting temperature are determined. Specifically, accuracy can be defined as being within ±3°C of the average of five values ​​of each of the shutdown temperature and melting temperature determined using the system according to this disclosure.

[0134] In Table 1, “Time Required” refers to the time required to determine the shutdown temperature and melting temperature.

[0135] In Table 1, "reproducibility" refers to obtaining results without problems when continuously determining the shutdown and melting temperatures of the same sample. A result can be defined as highly reproducible if all five determinations of the shutdown and melting temperatures are successful.

[0136] In the description of the various embodiments of this disclosure, it should be understood that the component elements referred to as "units" are not physically distinct elements, but functionally distinct elements. Therefore, each component element may be selectively integrated with another component element, or each component element may be divided into sub-elements to efficiently perform one or more control logics. However, it will be apparent to those skilled in the art that even when these component elements are integrated or separated, the integrated or separated component elements should be interpreted as falling within the scope of this disclosure.

[0137] This disclosure has been described in detail with reference to preferred embodiments and accompanying drawings. However, it should be understood that various changes and modifications falling within the scope of this disclosure will become apparent to those skilled in the art from the detailed description, and therefore the detailed description and specific examples are given by way of illustration only.

[0138] [Figure Labels]

[0139] 100: A system for determining the shut-off temperature and melting temperature of the separator.

[0140] 110: Separator

[0141] 120: First clamp

[0142] 130: Second clamp

[0143] 140: Heating unit

[0144] 150: Temperature sensor

[0145] 160: Control Unit

[0146] 170: Air permeability determination unit

[0147] 180: Storage unit

[0148] 190: Display Unit

Claims

1. A system for determining the shut-off temperature and melting temperature of a separator, comprising: A breathability determination unit (170) is configured to determine the breathability of the separator, the breathability being expressed as a Gurley value; A first clamp (120) is configured to fix one side of the separator and has a first through hole through which air discharged from the permeability determination unit is introduced. A second clamp (130) is arranged at a position relative to the first clamp based on the partition, is configured to fix the other side of the partition, and has a second through hole through which air passing through the first through hole and the pores in the partition is introduced; A heating unit (140) configured to heat the first clamp or the second clamp; Temperature sensor (150), the temperature sensor being configured to measure the temperature of the first clamp or the second clamp; and A control unit (160) is configured to control the heating unit and the temperature sensor. The control unit calculates the shut-off temperature and the melting temperature of the separator by using the temperature measured by the temperature sensor as a function of time and the air permeability of the separator determined by the air permeability determination unit. The air permeability determination unit is linked to the first clamp. The heating unit is mounted on the surface of the first or second clamp that contacts the separator. Wherein, the first through-hole is configured such that the cross-sectional area of ​​the first opening through which air is introduced is smaller than the cross-sectional area of ​​the second opening through which air is discharged; and The second through hole is configured such that the cross-sectional area of ​​the third opening through which air is introduced is greater than the cross-sectional area of ​​the fourth opening through which air is discharged.

2. The system for determining the shut-off temperature and melting temperature of the separator according to claim 1, wherein, The control unit is linked to the first clamp and the second clamp.

3. The system for determining the shut-off temperature and melting temperature of the separator according to claim 1, wherein, The temperature sensor is linked to at least one of the first clamp and the second clamp.

4. The system for determining the shut-off temperature and melting temperature of the separator according to claim 1, wherein, The separator is inserted between the first clamp and the second clamp.

5. The system for determining the shut-off temperature and melting temperature of a separator according to claim 1, the system further comprising a display unit configured to display the temperature as a function of time on an X-axis and the air permeability of the separator as a function of time on a Y-axis.

6. The system for determining the shut-off temperature and melting temperature of the separator according to claim 1, wherein, As the temperature increases as a function of time, the shutdown temperature (A) is the temperature corresponding to 100,000 sec / 100 cc of permeability.

7. The system for determining the shut-off temperature and melting temperature of the separator according to claim 1, wherein, The melting temperature (B) is the temperature at which the separator is destroyed and the permeability of the separator begins to decrease after the shutdown temperature, and the melting temperature is the temperature corresponding to 100,000 sec / 100cc of permeability after the shutdown temperature.

8. The system for determining the shut-off temperature and melting temperature of the separator according to claim 1, wherein, The average diameter of the holes in the first through hole and the second through hole is 2-15 mm.

9. The system for determining the shutdown temperature and melting temperature of a separator according to claim 1, the system further comprising a storage unit configured to record the calculated shutdown temperature and melting temperature of the separator.

10. The system for determining the shut-off temperature and melting temperature of a separator according to claim 1, the system further comprising a display unit configured to display the calculated shut-off temperature and melting temperature of the separator.

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