120 and the second jig 130 which may face each other. The jigs 120, 130 may include any material, as long as the material fixes the test object 110.

Each of the heating unit 140 and the temperature sensor 150 may be disposed on at least one of the first jig and the second jig. In addition, the separator 110 may be interposed between the first jig 120 and the second jig 130. Meanwhile, the through-hole formed in the first jig or the second jig may penetrate from the lateral side of the first jig or the second jig to the top and bottom surfaces of the first jig or the second jig.

Referring to FIG. 1 and FIG. 2, the heating unit 140 may be provided in at least one of the first jig and the second jig. For example, the heating unit may be linked to at least one of the first jig and the second jig. The heating unit 140 heats the test object 110 by heating the jigs. The controlling unit 160 may be electrically connected with the heating unit 140 and may control the operation of the heating unit 140. Therefore, the heating unit 140 heats the test object 110 to a predetermined temperature according to the control command input from the controlling unit 160. Finally, a graph illustrating the shut-down temperature and melt-down temperature may be plotted by the display unit 190.

Preferably, the heating unit 140 may be a hot wire installed in the second jig 130. The hot wire may be installed in the first jig 120, not the second jig 130, or may be installed in both the first jig 120 and the second jig 130. In a variant, the hot wire may be installed on the other surface where the first jig 120 or the second jig 130 is in contact with the test object. Particularly, the heating unit 140 may increase the temperature gradually as a function of time. Herein, the heating unit 140 may be electrically connected with the controlling unit 160, and may supply heat to the first jig or the second jig under the control of the controlling unit 160. In this manner, it is possible to observe the thermal properties of the separator interposed between the first jig and the second jig. The heating unit 140 may be electrically connected with the temperature sensor 150.

The temperature sensor 150 may be electrically connected with each of the first jig 120 and the second jig 130. In other words, the temperature sensor 150 may be connected to both ends of each jig. For example, the temperature sensor 150 may be directly connected with each of the first jig 120 and the second jig 130. For example, the temperature sensor 150 may be provided in the first jig 120 or the second jig 130.

The temperature sensor 150 measures the temperature of the separator heated by the heating unit 140.

According to the present disclosure, when the temperature sensor 150 measures the temperature of the separator, the temperature of the separator is room temperature, before the temperature is increased by the heating unit 140. However, when heat is supplied to the separator by the heating unit 140, the temperature of the separator is increased with the lapse of a predetermined time. The temperature sensor 150 measures the temperature increased in this case.

According to the present disclosure, the air permeability-determining unit 170 is directly linked to at least one of the first jig and the second jig. For example, the air permeability-determining unit 170 may be directly linked to the first jig or the second jig. For example, the air permeability-determining unit may be linked to the first jig.

Particularly, the air permeability (Gurley value)-determining unit 170 determines the air permeability (Gurley value) based on the following principle. The air permeability-determining unit is directly linked to the first jig 120 or the second jig 130. In addition, when air is injected to the test object 110 combined with the first and the second jigs 120, 130 under a predetermined pressure, the injected air undergoes a change in pressure depending on the properties of the separator as the test object 110. It is possible to determine the air permeability (Gurley value), which is a time required for a unit volume of air to pass through the separator, by using the changed air pressure. For example, determination of the air permeability may be carried out by the Oken air permeability tester (Asahi Seiko Co.). For example, determination of the air permeability may be carried out by measuring the time required for 100 cc of air to pass through the separator with the Oken air permeability tester.

According to the present disclosure, the controlling unit 160 controls the heating unit 140 and the temperature sensor 150. In addition, the controlling unit 160 calculates the shut-down temperature and melt-down 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-determining unit 170.

The controlling unit 160 may be electrically connected to each of the heating unit 140, temperature sensor 150, air permeability-determining unit 170, first jig 120 and the second jig 130. For example, the controlling unit 160 may be directly linked to the heating unit 140, temperature sensor 150 and the air permeability-determining unit 170. For example, the controlling unit may be linked to the first jig 120 and the second jig 130.

The controlling 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 determined by the air permeability-determining unit 170 as a function of time, while heat is supplied to the separator by the heating unit 140 to an extent increasing with time, and the temperature and the air permeability may be taken as X axis and Y axis, respectively, to calculate the shut-down temperature and melt-down temperature of the separator. Herein, X axis means the temperature (° C.) as a function of time, and Y axis means a change in air permeability (sec/100 cc) (Gurley value) of the separator as a function of time.

The controlling unit 160 can calculate the shut-down temperature and melt-down temperature of the separator from the temperature and the air permeability (Gurley value) received from the temperature sensor 150 and the air permeability-determining unit 170.

The controlling unit 160 can store the calculated shut-down temperature and melt-down temperature of the separator in the storage unit 180. Then, the temperature corresponding to an air permeability (Gurley value) of 100,000 sec/100 cc, when the temperature is increased as a function of time, is defined as the shut-down temperature, and the temperature at a point where the air permeability (Gurley value) starts to be decreased from 100,000 sec/100 cc after the shut-down temperature is defined as the melt-down temperature.

The storage unit 180 is not limited to any particular type, as long as it is a storage medium capable of recording and eliminating information. For example, the storage unit 180 may be RAM, ROM, EEPROM, DRAM, SDRAM, a resistor, a hard disc, an optical recording medium or a magnetic recording medium. The storage unit 180 may be electrically connected to the controlling unit 160 through a data bus, or the like, so that it may be approached by the controlling unit 160. The storage unit 180 may storage, update, eliminate and/or transmit data generated when programs and/or controlling logics, including various controlling logics performed by the controlling unit 160, are carried out. The storage unit 180 may be divided into two or more units logically. The storage unit 180 may be included in the controlling unit 160, but is not limited thereto.

The controlling unit 160 may display the calculated shut-down temperature and melt-down temperature of the separator on the display unit 190.

The display unit 190 may output the shut-down temperature and melt-down temperature of the separator determined for the test object 110 by the controlling unit 160 through an external display. For example, the results of calculation of the shut-down temperature and melt-down temperature of the separator may be output through a display in the form of letters, numbers, images, or the like. The results of calculation of the shut-down temperature and melt-down temperature of the separator may include the shut-down temperature of the separator, shut-down change profile, melt-down temperature, melt-down temperature change profile, or a combination thereof.

The display unit 190 may be electrically connected to the controlling unit 160, and the controlling unit 160 may output the results of the shut-down temperature, melt-down temperature or change profiles thereof 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 the present disclosure is not limited thereto.

FIG. 2 is a schematic view illustrating the constitution of the system for determining the shut-down temperature and melt-down temperature of a separator according to an embodiment of the present disclosure.

Referring to FIG. 2, the system 100 for determining the shut-down temperature and melt-down temperature of a separator may include two jigs 120, 130 facing each other, a heating unit 140 linked to the two jigs 120, 130, a temperature sensor 150, a controlling unit 160 and an air permeability-determining unit 170. The system may further include a storage unit 180 and a display unit 190.

Referring to FIG. 2, the system 100 for determining the shut-down temperature and melt-down temperature of a separator may hold a test object 110 between the first jig 120 and the second jig 130.

FIG. 3 is a flow chart illustrating the method for determining the shut-down temperature and melt-down temperature of a separator according to an embodiment of the present disclosure.

Referring to FIG. 1 and FIG. 3, in the method for determining the shut-down temperature and melt-down temperature of a separator according to an embodiment of the present disclosure, the test object 110, i.e. separator, is interposed first between the first jig and the second jig facing each other (S110). Thus, the test object 110 is fixed between the jigs 120, 130, and the fixing method is not particularly limited.

The test object may be a separator. For example, the test object, i.e. separator, may be a porous polymer substrate itself, and may have a porous coating layer including inorganic particles and a binder polymer on at least one surface of the separator.

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

There is no particular limitation in the inorganic particles, as long as they are electrochemically stable. In other words, there is no particular limitation in the inorganic particles that may be used herein, as long as they cause no oxidation and/or reduction in the range (e.g. 0-5 V based on Li/Li⁺) of operating voltage of an applicable electrochemical device. Particularly, when using inorganic particles having a high dielectric constant as the inorganic particles, it is possible to improve the ion conductivity of an electrolyte by increasing the dissociation degree of an electrolyte salt, such as a lithium salt, in a liquid electrolyte.

For the above-mentioned reasons, the inorganic particles may be inorganic particles having a dielectric constant of 5 or more, inorganic particles having lithium-ion transportability or a combination thereof.

The inorganic particles having a dielectric constant of 5 or more may include any one selected from the group consisting of Al₂O₃, SiO₂, ZrO₂, AlO(OH), TiO₂, BaTiO₃, Pb(Zr_xTi_1-x)O₃(PZT, wherein 0<x<1), Pb_1-xLa_xZr_1-yTi_yO₃(PLZT, wherein 0<x<1, 0<y<1), (1-x)Pb(Mg_1/2Nb_2/3)O_3-xPbTiO₃(PMN-PT, wherein 0<x<1), hafnia (HfO₂), SrTiO₃, SnO₂, CeO₂, MgO, NiO, CaO, ZnO, ZO₃and SiC, or a mixture of two or more of them.

The inorganic particles having lithium-ion transportability may be any one selected from the group consisting of include lithium phosphate (Li₃PO₄), lithium titanium phosphate (Li_xTi_y(PO₄)₃, 0<x<2, 0<y<3), lithium aluminum titanium phosphate (Li_xAl_yTi_z(PO₄)₃, 0<x<2, 0<y<1, 0<<<3), (LiAlTiP)_xO_y-based glass (1<x<4, 0<y<13), lithium lanthanum titanate (Li_xLa_yTiO₃, 0<x<2, 0<y<3), lithium germanium thiophosphate (Li_xGe_yP_zS_w, 0<x<4, 0<y<1, 0<z<1, 0<w<5), lithium nitride (Li_xN_y, 0<x<4, 0<y<2), SiS₂-based glass (Li_xSi_yS_z, 0<x<3, 0<y<2, 0<z<4) and P₂S₅-based glass (Li_xP_yS_z, 0<x<3, 0<y<3, 0<z<7), or a mixture of two or more of them.

In addition, there is no particular limitation in the average particle diameter of the inorganic particles. However, the inorganic particles preferably have an average particle diameter of 0.001-10 μm in order to form a coating layer with a uniform thickness and to provide suitable porosity. Particularly, the average particle diameter of the inorganic particles may be preferably 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.

The binder polymer is not particularly limited, as long as it can bind the inorganic particles among themselves. Non-limiting examples of the binder polymer may include polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polybutyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, or the like.