KR101640889B1 - Lithium ion secondary battery cell and module comprising phase change material - Google Patents

Abstract

The present invention relates to a lithium ion secondary battery cell and module comprising a phase change material. According to an embodiment of the present invention there is provided an electrode-separator assembly having an anode, a cathode, a separator interposed between the anode and the cathode, and a pouch surrounding the outer surface of the electrode-separator assembly, A lithium ion secondary battery cell having a phase change material applied on at least one surface of the inside or the outside; And at least one electrode-separator assembly having an anode, a cathode, and a separator interposed between the anode and the cathode, and a pouch surrounding the outer front of each of the electrode-separator assemblies, Wherein the phase change material is applied to at least one of the pouches and between the pouch and the cover. The lithium ion secondary battery to which the phase change material is applied according to the present invention absorbs heat and maintains an insulation state between the electrodes or between the electrode and the through object when the temperature of the lithium ion secondary battery increases sharply or the object penetrates from the outside, The safety of the battery can be improved by suppressing ignition and explosion.

Description

[0001] The present invention relates to a lithium ion secondary battery cell and a module comprising a phase change material,

The present invention relates to a lithium ion secondary battery cell and module comprising a phase change material (PCM).

BACKGROUND ART [0002] With the recent development of the information communication industry, as electronic devices have become smaller, lighter, thinner, and portable, there is a growing demand for higher energy density of batteries used as power sources for such electronic devices. Lithium ion secondary batteries are the ones that can best meet these demands, and researches thereon are actively under way.

However, when the lithium ion secondary battery is overcharged due to a failure such as a misuse and a charger, or when an internal short circuit occurs due to design defects, penetration, external impact, or the like of the battery itself, have. When the temperature of the battery rises sharply, the battery becomes very unstable due to the reaction of the electrolyte with lithium or the oxidation of the anode, and the solvent of the electrolyte is decomposed to generate gas. The decomposition gas of the solvent may be ignited and lead to explosion of the battery.

As a means for solving such a problem of stability, there are a method of forcibly discharging an electrolyte, a method of protecting a battery in a control PTC (Positive Temperature Coefficient) circuit of a pack connected with a battery, and the like. However, in such a method, there is a great limitation in the probability of causing a malfunction if a circuit problem occurs. In addition, there is an attempt to apply a device that cuts off the current by using the force of the cell expanding like the current interrupting element, but there is still a need to make it operate faster.

As a result, there is still a need for efforts to suppress sudden temperature rise in abnormal behavior of the battery cells and modules, and to improve the stability by blocking current flow.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a lithium ion secondary battery and a lithium ion secondary battery which are capable of absorbing heat and interfering with an electric current flowing through the lithium ion secondary battery when the temperature of the lithium ion secondary battery rises sharply, Ion secondary battery module.

According to an aspect of the present invention, there is provided an electrode-separator assembly having an anode, a cathode, a separator interposed between the anode and the cathode, and a pouch surrounding the outer front surface of the electrode- and a phase change material is applied to at least one surface of the pouch inside or outside the pouch.

According to another aspect of the present invention there is provided a battery pack comprising at least one electrode-separator assembly having an anode, a cathode, and a separator interposed between the anode and the cathode, and a pouch surrounding the outer front of each of the electrode- There is provided a lithium ion secondary battery module having a cover surrounding the entire outer surface of the pouches and at least one of the pouches and between the pouches and the cover.

The lithium ion secondary battery to which the phase change material is applied according to the present invention absorbs heat and maintains an insulation state between the electrodes or between the electrode and the through object when the temperature of the lithium ion secondary battery increases sharply or the object penetrates from the outside, The safety of the battery can be improved by suppressing ignition and explosion.

FIG. 1 is a schematic view illustrating absorption of heat due to a temperature rise of an electrode-separator assembly by a phase change phenomenon of a phase change material. FIG.
FIG. 2 is a schematic view illustrating that, when a battery cell is penetrated, an object is surrounded by a phase change of a phase change material to interfere with an electrical flow of the through object.
Figure 3 illustrates one embodiment of a battery cell to which a phase change material is applied.
Figure 4 shows another aspect of a battery cell to which a phase change material is applied.
Figure 5 illustrates one embodiment of a battery module to which a phase change material is applied.
Figure 6 illustrates another aspect of a battery module to which a phase change material is applied.

The terms used in the specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may properly define the concept of a term to describe its invention in its best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It should be understood that various equivalents and modifications may be present.

1 illustrates an example of absorbing heat due to a temperature rise of the electrode-separator assembly 1 by a phase change phenomenon of the phase-change material 3 when an external short circuit and overcharge of the battery cell surrounded by the pouch 2 occur, for example. FIG. 2 illustrates that when the battery cell is penetrated, it surrounds an object due to a phase change of the phase change material 3, thereby interfering with the electrical flow of the through object 4. FIG.

In a secondary battery, a material such as a carbon material is usually used as a negative electrode (not shown), a material such as lithium oxide is used as a positive electrode (not shown), and a lithium salt is dissolved in an organic solvent When the battery is overcharged, the electrolytic solution is decomposed at the anode, the metal is precipitated at the cathode, deteriorating the battery characteristics, and there is a fear of generation of heat or ignition. In addition, since the polymer electrolyte is locally overheated during charging and discharging, the polymer electrolyte which is weak in heat may be partially dissolved or softened, resulting in non-uniformity of electric current and electric potential, resulting in a risk of short circuit, fire and explosion.

FIG. 3 shows one embodiment of a battery cell to which a phase change material is applied, and FIG. 4 shows another aspect of a battery cell to which a phase change material is applied.

3 and 4, the present invention provides a lithium ion secondary battery cell including a pouch 2 surrounding an outer front surface of an electrode-separator assembly 1, The present inventors have attempted to solve the problems of the lithium ion secondary battery described above by applying the phase change material 3 on at least one side. Here, the electrode-separator assembly 1 may have an anode (not shown), a cathode (not shown), and a separator (not shown) interposed between the anode and the cathode.

As an example, referring to FIG. 3, a phase change material 3 is applied on the upper surface of a pouch 2 surrounding the outer front surface of the electrode-separation membrane assembly 1. In this embodiment, the phase change material (3) having a certain range of phase change temperatures (T _PC ), as described in Figure 1 or Figure 2, in the event of a sudden temperature rise inside or outside the cell or through the penetration of an external object, The heat in the battery can be removed or the insulated state in the battery can be maintained. In addition, the phase change material 3 may be applied to one surface, for example, a bottom surface or a side surface, other than the top surface of the pouch 2 mentioned above.

4, a space between the pouch 2 and the electrode-separator assembly 1, specifically a top surface of the electrode-separator assembly 1 inside the pouch 2, 3) is applied. Similar to FIG. 3, in the case of sudden temperature rise inside or outside of the cell, or penetration of an external object, the phase change material having a certain range of phase change temperatures (T _PC ) 3 can remove heat in the battery or maintain the insulation state in the battery. In addition, the phase change material 3 can be formed in the space between the electrode-separator assembly 1 and the pouch 2 other than the upper surface of the electrode-separator assembly 1, for example, in the pouch 2 Or the like of the electrode-separator assembly 1 in the interior of the electrode-separator assembly 1.

A phase change material refers to a substance that is used for the purpose of storing energy or maintaining a constant temperature by taking advantage of the absorption or emission effect of the latent heat of the substance. Here, latent heat means heat absorbed or released at the same temperature when the material is phase-changed, that is, from solid to liquid or from liquid to solid, from liquid to gas or from gas to liquid, The amount of heat absorbed or released in the absence of change). As described above, the phase change material gradually increases the temperature when the ambient temperature is high, and gradually decreases when the ambient temperature is low. Specifically, if the phase-change material has its intrinsic phase-change temperature (T _PC ) or if it remembers a constant temperature for the material, the phase-change material will change the phase in that temperature range, Thereby increasing or decreasing the ambient temperature. Therefore, when transferred from a low-temperature place to a high-temperature place, the solid phase changes into a liquid phase and the surrounding heat is taken away to cool the surroundings. On the other hand, To increase the ambient temperature.

Various phase change materials can be used for the lithium ion secondary battery cell and module of the present invention. The phase change material (T _PC ) is not limited because it uses a phase change material to remove heat generated in the battery due to abnormal operation or penetration of an external object. For example, a phase change material that is present in a solid phase at ambient temperatures, such as less than about 60 DEG C, or less than about 25 to about 50 DEG C, is phase shifted to a liquid phase at a phase change temperature (T _PC ) Modifying materials may be used, but are not limited thereto. Basically, the operating temperature range of the battery is at most about 60 DEG C, the range of maintaining the solid phase is about 25 DEG C to about 50 DEG C, and the temperature at which the liquid phase is maintained is about 50 DEG C to about 95 DEG C. Further, since the degree of heat generation varies slightly depending on the type of the battery, it is preferable to use a battery having a phase change temperature (T _PC ) of about 50 캜 or higher, preferably about 50 to about 90 캜, more preferably about 50 to about 70 캜 Phase change materials may be used.

2, when the external object 4 penetrates the cell, particularly the electrode-separator assembly 1, when the external object 4 is conductive, the conductive object 4 is brought into contact with the electrode The phase change material 3 is a phase change material having the above-mentioned property (for example, the phase change temperature T _PC ) If the ambient temperature is raised to at least about 50 ° C or more, the solid phase of the phase change material will turn into a liquid phase and deprive the surrounding heat. That is, excessive heat generated in the battery can be removed.

Examples of such phase change material is a paraffin, such as C ₂₀ -C ₄₅ paraffin, inorganic salts, salt hydrates, and mixtures thereof, may be alone or in combination of two or more thereof selected from the group consisting of carboxylic acids and sugar alcohols including, but not limited to, not. Preferably, the phase change material is selected from the group consisting of tetracosan (melting point about 53 占 폚), hexaconic acid (melting point about 56 占 폚), nonanoic acid (melting point about 63 占 폚), sodium acetate trihydrate A mixture of lithium nitrate and magnesium nitrate hexahydrate (melting point: about 75 ° C), trisodium phosphate dodecahydrate (melting point: about 75 ° C), magnesium nitrate hexahydrate And a mixture of two or more selected from myristic acid (melting point of about 52 DEG C), stearic acid (melting point of about 69 DEG C), xylitol (melting point of about 93 to 95 DEG C) It does not.

Further, in order to enhance the thermal conductivity of such phase change material, one or more auxiliary materials having excellent thermal conductivity may be further applied to the lithium ion secondary battery cell or module together with the phase change material described above. The one or more adjuvants may be materials or compositions with good thermal conductivity, especially metal powders, metal granules or graphite.

As a method of applying the phase change material on the inner and outer surfaces of the pouch of the lithium ion secondary battery cell, a conventional coating method known in the art can be used. For example, the phase change material is melted at a melting point or higher, May be applied by various methods such as dip coating, die coating, roll coating, comma coating, or a combination thereof.

The application amount of the phase change material can be greatly changed depending on the type of the battery to be used, for example, a cell used for a mobile phone, an HEV, a PHEV, an EV, or the like. For example, the application amount of the phase change material may vary depending on the area of the pouch facing the electrode-separation membrane assembly, the amount of heat generated by the battery, and the like. Since the area of the pouch and the calorific value vary depending on the battery to be used, the application amount of the phase change material of the present invention can be largely changed depending on the area of the pouch and the calorific value of the battery depending on the battery used. In addition, the calorific value of a battery greatly varies depending on the capacity of a battery to be used. When the capacity of the battery is large, the calorific value of the battery is increased accordingly, and the amount of application can be also increased. In addition, the coating amount can be increased in proportion to the thickness of the battery to be used. For example, the application range of the phase change material may be the same as the pouch area, and the applied thickness of the phase change material may be equal to the thickness of the cell.

Typically, the phase change material is present in a variety of spaces in which the phase change material is applied, such as the top surface of the aforementioned electrode-separator assembly, the space between the pouch and the electrode-separator assembly, When the battery is restored to a normal state after the heat radiation is completed, the phase change material present inside the battery can be absorbed at a room temperature For example, less than about 50 < 0 > C, resulting in reuse of the battery.

Therefore, the phase change material of the present invention can improve the safety of a battery by absorbing heat alone or in combination with a thermally conductive auxiliary agent when the temperature of the battery rises rapidly during overcharging or internal shorting of the lithium ion secondary battery .

Meanwhile, the positive electrode, the negative electrode, the separator, the electrolyte, the pouch, the cover, etc. used in the present invention can be easily manufactured by a process and / or a method known in the art. The positive electrode, the negative electrode and the separator constituting the electrode-separator assembly can be all those conventionally used for manufacturing a lithium ion secondary battery.

Specifically, the anode is manufactured by binding a cathode active material to a cathode current collector according to a conventional method known in the art, and plays a role of intercalating and deintercalating lithium ions. As the cathode active material, a conventional cathode active material that can be used for a cathode of a conventional secondary battery can be used, and examples thereof include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _{c) O 2 (0 <a} <1, 0 <b <1, a + b + c = 1), LiNi 1 - Y Co Y O 2, LiCo 1 - Y Mn Y O 2, LiNi 1 -Y Mn Y O ₂ (where, 0≤Y <1), Li ( Ni a Co b Mn c) O 4 (0 <a <2, 0 <b <2, a + b + c = 2), LiMn 2 - Z Ni _Z O ₄ , LiMn _{2 -Z} Co _Z O ₄ (where 0 <Z <2), LiCoPO ₄ , LiFePO _4, and mixtures thereof. As the positive electrode collector, aluminum, nickel, or a foil produced by a combination of these may be used.

The negative electrode is manufactured by binding an anode active material to an anode current collector according to a conventional method known in the art, and performs a function of intercalating and deintercalating lithium ions in the same manner as the anode. At this time, the negative electrode active material may be carbon such as non-graphitized carbon or graphite carbon; Li _x Fe ₂ O ₃ (0? _X? 1), Li _x WO ₂ (0? _X? 1), Sn _x Me _{1 -x} Me _y O _z (Me: Mn, Fe, Pb, : Metal complex oxides of Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 &lt; x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used. On the other hand, as the negative electrode collector, stainless steel, nickel, copper, titanium or an alloy thereof can be used.

A separator is provided between the anode and the cathode to maintain an insulated state to prevent a short circuit. The separator may be a polymer membrane such as polyolefin, polypropylene, or polyethylene, or a multilayer thereof, a microporous film, a woven fabric, or a nonwoven fabric. Further, an organic / inorganic particle coating layer may be formed on the separation membrane as is known in the art.

Electrolyte solution is A ⁺ B ^- A salt of the structure, such as, A ⁺ is Li ^+, Na ^+, K ⁺ comprises an alkaline metal cation or an ion composed of a combination thereof, such as, and B ^- is PF ₆ ^-, BF ₄ ^{-, Cl -, Br -, I -} , ClO 4 -, AsF 6 -, CH 3 CO 2 -, CF 3 SO 3 -, N (CF 3 SO 2) 2 -, C (CF 2 SO 2) 3 - , such as Anion, or a combination thereof, is preferably selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC) (NMP), ethylmethyl carbonate (EMC), gamma-butyrolactone (gamma -butyrolactone), or a mixture thereof, in the presence of a base such as sodium hydride, potassium hydride, But are not limited to, those dissolved or dissociated in an organic solvent.

The pouch can be used without limitation as long as it is a substance that is not dissolved in the electrolytic solution. The pouch may be formed in the form of a metal thin film, for example, an aluminum thin film interposed therebetween to complement the electrochemical properties of the battery cell and to improve heat dissipation. In order to ensure the insulation between the battery cell and the outside, the aluminum thin film may include an insulating layer (not shown) coated with an insulating material such as polyethylene terephthalate (PET) resin or nylon resin Can be formed on the outside. For sealing, the inner surface of the pouch can form an adhesive layer (not shown) made of a thermally adhesive resin. Accordingly, the pouch can form an adhesive layer on the inner surface of the metal foil and an insulating layer on the outer surface, and the thermally adhesive resin coated on the inner surface can be sealed by fusing by heating and pressing.

FIG. 5 illustrates one embodiment of a battery module to which a phase change material is applied, and FIG. 6 illustrates another aspect of a battery module to which a phase change material is applied.

5 and 6, according to another embodiment of the present invention, a separator (not shown) interposed between the anode and the cathode (not shown), a cathode (not shown) (1), and a cover (5) surrounding the outer front of both of the pouches (2), both of the one or more pouches (2) , Characterized in that the phase change material (3) is applied to at least one of the pouches (2) and between the pouch (2) and the cover (5) .

Here, the materials and configurations of the positive electrode, the negative electrode, the separator, the electrode-separator assembly, and the pouch are as described above.

The cover 5 may have the same material and construction as the pouch 2 described above in one embodiment. In another embodiment, the cover 5 may not have an electrolytic solution therein, so that the example of the substance may be wide. Further, the cover 5 is formed by forming an insulating layer (not shown) on the outside similar to the above-described pouch 2 and forming an adhesive layer (not shown) made of a thermally adhesive resin on the inner surface for sealing can do.

1-electrode-membrane assembly
2 - Pouch
3-phase change material
4 - Through object
5 - Cover

Claims (11)

An electrode-separator assembly having an anode, a cathode, and a separator interposed between the anode and the cathode, and a pouch surrounding the outer surface of the electrode-separator assembly,
A phase change material (PCM) is applied to at least one side of the inside or the outside of the pouch,
Wherein the phase change material is selected from the group consisting of inorganic salts, salt hydrates, carboxylic acids, sugar alcohols, tetracholic acid, hexanoic acid, nonanoic acid, sodium acetate trihydrate, sodium thiosulfate pentahydrate, sodium hydroxide monohydrate, lithium nitrate And a mixture of magnesium nitrate hexahydrate, trisodium phosphate dodecahydrate, magnesium nitrate hexahydrate, myristic acid, stearic acid, and xylitol.
Wherein at least one auxiliary agent having an excellent thermal conductivity is further applied together with the phase change material.
The method according to claim 1,
Wherein the phase change material has a phase change temperature (T _PC ) of 50 ° C or higher. delete delete delete The method according to claim 1,
Wherein the auxiliary agent is a metal powder, a metal granule, or graphite. The method according to claim 1,
Wherein the application amount of the phase change material is adjusted according to an area of the pouch facing the electrode-separation membrane assembly, a capacity of the battery, or a calorific value. A cover surrounding the outer front surface of both the pouch and the pouch surrounding the outer front surface of each of the electrode-separation membrane assemblies, Respectively,
A phase change material is applied to at least one of the pouches and between the pouches and the cover,
Wherein one or more auxiliary agents having excellent thermal conductivity are further applied together with the phase change material. 9. The method of claim 8,
Wherein the phase change material has a phase change temperature (T _PC ) of 50 캜 or more. 9. The method of claim 8,
Wherein the phase change material is one or a mixture of two or more selected from the group consisting of paraffin, inorganic salt, salt hydrate, carboxylic acid, and sugar alcohol. 9. The method of claim 8,
Wherein the application amount of the phase change material is adjusted according to an area of the pouch facing the electrode-separation membrane assembly, a capacity of the battery, or a calorific value.

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