KR20070041972A - Electrochemical device with high stability at high temperature and overvoltage - Google Patents

Abstract

The present invention is characterized in that an electrode and a method for producing the same are characterized in that a foaming agent which releases a gas other than oxygen at a temperature (T) above the normal operating temperature range of the cell is coated on the electrode surface or mixed with the electrode material. It provides an electrochemical device provided.

In the present invention, by using a blowing agent that emits a large amount of inert gas in the temperature range above the normal operating temperature of the battery as one component or coating component of the electrode, the safety of the battery during overcharge and high temperature storage Can be improved.

Foaming agent, electrode, safety, overcharge, azo system, azobiscarroxamide (ADA)

Description

ELECTROCHEMICAL DEVICE WITH HIGH STABILITY AT HIGH TEMPERATURE AND OVERVOLTAGE}

1 is a graph showing a change in resistance according to the temperature change of the electrodes prepared in Example 1 and Comparative Example 1.

The present invention relates to an electrode and an electrochemical device having the electrode that can provide excellent safety even if the internal temperature of the battery is abnormally increased due to external or internal factors, and more particularly, to release a large amount of inert gas at high temperature. By using a blowing agent to the electrode to prevent contact with oxygen necessary for ignition, and to increase the resistance to block the high current flow to prevent explosion and / or ignition in the event of overcharge and high temperature storage, and the method for producing the same, the The present invention relates to an electrochemical device having an electrode having improved safety.

In general, a lithium secondary battery using a flammable non-aqueous electrolyte is short-circuited due to dendrites grown by lithium ions at a negative electrode during overcharging, and as a result, the internal temperature of the battery rises, the decomposition reaction of the electrolyte, and the electrolyte There is a problem that an explosion or fire occurs due to the generation of flammable gas due to the reaction of the electrode and the electrode. In addition, polyethylene used as a separator between the positive electrode and the negative electrode starts to melt in the range of 120 to 130 ° C. when the temperature of the battery rises. Accordingly, short circuit occurs due to contact between the negative electrode and the positive electrode at the corner due to shrinkage of the separator. The heat flows through the current flow, causing the temperature to rise and eventually causing the battery to ignite.

In order to solve this problem, US Patent No. 6,074,776 discloses a method of controlling the flow of current through the increase of electrode resistance by making an insulating layer on the surface of the anode at a high temperature, wherein the aromatic monomer additive introduced is a polymerization reaction in a high voltage state It was used to cause. However, there is still a risk of ignition of the battery due to electrolyte decomposition when the temperature rises.

In Japanese Patent Laid-Open No. 2002-157979, it is excellent in thermal stability and a flame retardant magnesium alloy having a ignition temperature of 550 ° C. or higher is added to a nonaqueous electrolyte to prevent battery from igniting and burning even when the battery temperature rises. The method is disclosed. However, even in this case, even though the magnesium alloy can absorb some heat, it is not possible to absorb all the heat inflows due to the continuous temperature rise, so there is a risk of ignition.

In Japanese Patent Laid-Open No. 194-150975, a method of pressurizing and charging an electrolyte solution with carbon dioxide is used to easily release the electrolyte solution together with carbon dioxide when the temperature of the battery rises abnormally. However, when the electrolyte is sucked into the inner pores of the separator or the inside of the electrode, the gas ignition alone is not easily released to the outside, so the risk of battery ignition due to decomposition of the electrolyte is still not solved.

Japanese Patent Laid-Open No. 1999-317232 proposes a method of flame retarding an electrolyte solution for a lithium secondary battery by adding a phosphate flame retardant such as trialkyl phosphate, trimethyl phosphate, or dimethyl phosphate to the electrolyte solution. However, phosphate-based flame retardants are ignited and melted by their heat, which encapsulates the surface and serves to extinguish the effect of preventing contact with oxygen. Therefore, a large amount of flame retardants must be added to the electrolyte. Therefore, the use of a large amount of phosphate-based flame retardant inevitably leads to deterioration of battery characteristics. In addition, in the case of a highly flammable electrolyte, it is easily propagated once it catches fire, so it is insufficient to be digested only by using a phosphate-based flame retardant.

In view of the above problems, the present inventors use a method of preventing contact with oxygen necessary for ignition before reaching the ignition point even if the temperature rises due to an abnormal problem caused by external or internal factors in the battery and / or (2) Even if a short circuit occurs due to the membrane shrinkage caused by the temperature rise, the method of increasing the electrode resistance and restraining a large amount of current flow by increasing the interval between the electrode active material particles instantaneously improves the safety of the battery. Was first discovered.

Indeed, the use of a blowing agent as one component or coating component of the electrode increases the spacing between the particles that make up the electrode and thereby increases the resistance of the electrode by releasing a large amount of inert gas at temperatures above the normal operating temperature of the cell, such as around 130 ° C. It prevents the rapid flow of current and increases the internal pressure to open the vents, which not only lowers the temperature to prevent ignition, but also prevents contact with oxygen, the ignition-causing element, due to the released inert gas. It was confirmed that the battery ignition suppression by the gas and thereby the effect of improving the safety of the battery is excellent.

Accordingly, an object of the present invention is to provide an electrode containing a blowing agent capable of achieving the above-mentioned safety improvement effect, a method for manufacturing the same, and an electrochemical device having the electrode.

The present invention provides an electrode and an electrochemistry comprising the electrode, wherein the blowing agent that releases a gas other than oxygen at a temperature T above the normal operating temperature range of the cell is coated on or mixed with the electrode material. Device, preferably a lithium secondary battery.

In addition, the present invention comprises the steps of (a) mixing the blowing agent with the electrode material and then applying on the current collector or coated on the surface of the electrode prepared; And (b) provides a method for producing an electrode containing a blowing agent comprising the step of drying the electrode.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention is characterized by using a blowing agent (제) used as an auxiliary component or coating component of the electrode even if it is not applied to the conventional battery or is applied to form a pore structure by thermal decomposition.

Conventional blowing agents have been used for the purpose of reducing the amount of raw materials used in impact or by adding a rubber, polyurethane, EVA and the like to decompose at the processing temperature during extrusion or injection processing to release a large amount of gas to form bubbles. However, in the present invention, the blowing agent is used for the purpose of instantaneously decomposing in a narrow temperature range to eject a large amount of inert gas and to raise the pressure inside the battery.

When the blowing agent having the above characteristics is used as a component and / or coating component of the electrode, it can exhibit an effect of improving the safety of the battery.

In other words, when the temperature of the battery rises abnormally due to internal or external factors such as high temperature storage or overcharging, the decomposition reaction of the electrolyte, the generation of flammable gas by the reaction between the electrolyte and the electrode, the internal short circuit caused by the shrinkage of the separator, etc. This causes the battery to ignite and explode. In order to solve such a problem, an electrolyte additive such as a monomer additive and a flame retardant to form an insulating layer was used, but the problem of deterioration of fundamental safety of the battery was not solved, and this resulted in deterioration of battery characteristics.

In contrast, the present invention uses a blowing agent that releases a large amount of a gas, for example, an inert gas, except for oxygen (O ₂ ), which is one of the ignition elements, at a temperature higher than the normal operating temperature range of the battery, thereby preventing contact with oxygen It can fundamentally solve the occurrence of ignition.

In addition, when the blowing agent is used as one component of the electrode, the gap between the electrode active material particles in the electrode is instantaneously increased due to the volume expansion caused by a large amount of gas ejection pressure, and thus the edge of the edge portion is caused by the membrane shrinkage caused by the temperature rise. Even if an internal short circuit occurs due to the contact of the positive electrode, high current flow can be suppressed through an increase in resistance due to the increase in distance between the electrode active material particles described above. Indeed, the experimental example of the present invention showed that the electrode resistance containing the blowing agent increased significantly at a temperature higher than the normal operating temperature range of the battery (see FIG. 1).

Furthermore, since the vent may be operated early due to an increase in the gas pressure inside the battery due to a large amount of gas emitted by the blowing agent, heat inside the battery may be dissipated to the outside in advance, causing a decrease in the internal temperature.

Through such a complex action, it is possible to achieve an excellent safety improvement effect of the battery.

A blowing agent capable of achieving the above-described action may be used as one component of the electrode, mixed or used as a coating component of the prepared electrode. At this time, the blowing agent can be used without limitation, conventional blowing agents known in the art that can instantly decompose in a specific temperature range to release a large amount of gases other than oxygen.

The temperature at which the blowing agent is decomposed to release a large amount of gas is not particularly limited as long as it is higher than the normal operating temperature of the battery, and is particularly higher than the normal operating temperature range of the battery, and a temperature at which the decomposition reaction of the electrolyte solution provided in the battery occurs. Lower temperature ranges are preferred. In one example, the temperature ranges from 130 to 150 ° C.

In addition, there is no particular restriction as to the gas component to be released by the thermal decomposition of the blowing agent as long as it is not an oxygen ignition element, but preferably an inert gas such as N ₂ , He, Ne, Ar, Kr, Xe or a mixture thereof. Do.

Non-limiting examples of the blowing agent that can be used are azo (azo, -N = N-)-based compounds, and the like, preferably azobiscaroxamide (ADA) -based compounds represented by the formula (1).

Since the ADA-based blowing agent rapidly releases a large amount of nitrogen in a range of 130 to 150 ° C., preferably about 25 ml to 350 ml / g, preferably about 220 ml / g, the above-described safety improvement effect of the battery may be sufficiently satisfied. In addition to the foaming agent of the above components, as long as the above conditions can be satisfied to improve the safety of the battery, the components, forms, and the like thereof are not particularly limited.

The content of the blowing agent to be introduced into the electrode is not particularly limited as long as it shows the effect of improving the safety of the battery, but if possible, the range of 0.05 to 10 parts by weight per 100 parts by weight of the electrode active material is preferred. If the blowing agent is used less than 0.05 parts by weight, the desired safety improvement effect may be insignificant. If it exceeds 10 parts by weight, the amount of the electrode active material due to the use of the blowing agent is relatively reduced, leading to a decrease in the overall battery capacity and other performance degradation.

The method for producing an electrode including the foaming agent as a constituent of the electrode according to the present invention is not particularly limited, but a preferred embodiment thereof includes (a) a foaming agent as an electrode material, such as an electrode active material, a conductive agent and a binder, if necessary. Preparing an electrode slurry by mixing the same or the like and then applying the same on a current collector or coating the prepared electrode surface; And (b) may comprise the step of drying the electrode.

Hereinafter, an example of a method for dispersing the blowing agent in the electrode will be described in detail.

First, 1) a binder (eg, polyvinylidene fluoride (PVDF)) is added to a solvent or a dispersion medium (eg, NMP (N-methyl pyrroridone) to prepare a binder solution.

At this time, the binder is appropriately added in 5 to 20 parts by weight (weight ratio) based on 100 parts by weight of the solvent or dispersion medium, but is not limited thereto. In addition, the solvent or dispersion medium used to prepare the binder solution may be any conventional solvent used in the art, including, but not limited to, N-methylpyrrolidone, acetone, dimethylacetamide, or Organic solvents such as dimethylformaldehyde, inorganic solvents such as water, and mixtures thereof. The amount of the solvent used is sufficient to dissolve and disperse the active material, the conductive material, the electrode binder, and the adhesion enhancing additive in consideration of the coating thickness of the electrode slurry and the production yield. The solvents are removed by drying after coating the electrode slurry on a current collector.

2) The preparation of the electrode is completed by adding the electrode active material and the blowing agent to the prepared binder solution, mixing and completely dispersing it, and then applying it to a current collector and drying it.

The blowing agent is appropriate to add 0.5 to 50 parts by weight relative to the binder, but is not limited thereto. As such, the electrode active material and the conductive agent are added together to the binder solution containing the blowing agent to prepare an electrode slurry in a mixer. The electrode drying process may also be carried out according to conventional methods known in the art, and one example may be hot air drying.

The positive electrode active material may be a conventional positive electrode active material that can be used for the positive electrode of the conventional electrochemical device, non-limiting examples thereof, such as LiM _x O _y (M = Co, Ni, Mn, Co _a Ni _b Mn _c ) Lithium transition metal composite oxides (for example, lithium manganese composite oxides such as LiMn ₂ O ₄ , lithium nickel oxides such as LiNiO ₂ , lithium cobalt oxides such as LiCoO ₂ , and some of manganese, nickel, and cobalt oxides thereof Or a vanadium oxide containing lithium or the like, or a chalcogen compound (for example, manganese dioxide, titanium disulfide, molybdenum disulfide, or the like). Preferably 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, 0 <c <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, 0 <c <2, a + b + c = 2), LiMn _2-z Ni _z O ₄ , LiMn _2-z Co _z O ₄ ( Here, 0 <Z <2), LiCoPO ₄ , LiFePO _4, or a mixture thereof is mentioned. More preferably, it is a lithium transition metal composite oxide represented by the following formula (2).

Li _x MO ₂

Wherein M is Ni, Co, or Mn, and x is 0.05 ≦ x ≦ 1.10.

The negative electrode active material may be a conventional negative electrode active material that can be used for the negative electrode of the conventional electrochemical device, non-limiting examples of lithium metal or lithium alloy, carbon, petroleum coke, activated carbon, Lithium adsorbents such as graphite or other carbons. Non-limiting examples of the positive electrode current collector is a foil made by aluminum, nickel or a combination thereof, and non-limiting examples of the negative electrode current collector by copper, gold, nickel or copper alloy or a combination thereof Foils produced.

Conventional binders may be used, and non-limiting examples thereof include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), teflon, or mixtures thereof.

The conductive agent is not particularly limited as long as it can improve conductivity, and non-limiting examples thereof include acetylene black or graphite.

The weight ratio of the components constituting the electrode of the present invention is not particularly limited, but (a) 80 to 99 parts by weight, preferably 90 to 96 parts by weight of the positive electrode active material or the negative electrode active material; (b) 1 to 15 parts by weight of the binder, preferably 1 to 7 parts by weight; And (c) 0.05 to 10 parts by weight of blowing agent, preferably 1 to 5 parts by weight. In addition, it may further comprise 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight of the conductive agent for the purpose of increasing the conductivity of the electrode.

A method of preparing an electrode using the blowing agent as a coating component of the electrode may also be prepared according to a conventional method known in the art. For example, a blowing agent-containing dispersion is prepared by dispersing the blowing agent in a binder solution or a solvent. After that, it may be coated and dried on the prepared electrode surface.

The present invention provides an electrochemical device comprising an anode, a cathode, a separator and an electrolyte, wherein the anode, the cathode, or the positive electrode is an electrode containing a blowing agent.

Electrochemical devices include all devices that undergo an electrochemical reaction, and specific examples thereof include all kinds of primary, secondary cells, fuel cells, solar cells, or capacitors. In particular, a lithium secondary battery is preferable among the secondary batteries, and non-limiting examples thereof include a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.

The electrochemical device of the present invention may be prepared by inserting a porous separator between a positive electrode and a negative electrode in a conventional manner known in the art and adding the electrolyte solution.

The battery electrolyte includes conventional electrolyte components known in the art, such as electrolyte salts and organic solvents.

Using the electrolyte salts 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 ^- is a salt containing an anion ion or a combination thereof, such as. In particular, a lithium salt is preferable.

Organic solvents may be used conventional solvents known in the art, such as cyclic carbonates and / or linear carbonates, non-limiting examples of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl Carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC) Gamma butyrolactone (GBL), fluoroethylene carbonate (FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate, butyl propionate or these And mixtures thereof. Moreover, the halogen derivative of the said organic solvent can be used, and it can also be used for the battery using water.

The separator is not particularly limited, but a porous separator may be used, for example, a polypropylene-based, polyethylene-based, or polyolefin-based porous separator.

The external shape of the electrochemical device manufactured by the above method is not limited, but cans are cylindrical, coin-shaped, square or pouch types.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Examples 1 to 3]

Example 1

(Cathode production)

Carbon powder as a negative electrode active material, polyvinylidene fluoride (PVDF) as a binder, a conductive agent, and a blowing agent AMBM were mixed in a weight ratio of 91: 4: 4: 1, and then dispersed in NMP to prepare a negative electrode mixture slurry. This negative electrode mixture slurry was uniformly applied to a cross section of a Cu foil having a thickness of 10 μm with a negative electrode current collector with a comma gap of 200 μm and then dried. The coating speed at this time was 3 m / min. Stability was measured by sampling the dried electrode, the results of which are shown in Table 1 below.

(Anode manufacturing)

A positive electrode mixture slurry was prepared by mixing lithium cobalt composite oxide as a positive electrode active material, carbon as a conductive agent, PVDF as a binder and blowing agent AMBM in a 92: 4: 3: 1 weight ratio, and then adding it to NMP as a solvent. The positive electrode mixture slurry was applied to an Al thin film of a positive electrode current collector having a thickness of 20 μm, and coated and dried in the same manner as the negative electrode.

(Battery manufacturing)

As a separator, a porous polyethylene film was used, and a jelly roll was manufactured by laminating a strip-shaped cathode and an anode and winding it several times. The length and width were adjusted so that it was properly embedded in a battery can having an outer diameter of 18 mm and a height of 65 mm. The manufactured jelly roll was accommodated in the battery can, and the insulating plates were disposed on both upper and lower surfaces of the electrode element. Then, a negative electrode lead made of nickel was drawn from the current collector and welded to the battery can, and a positive electrode lead made of aluminum was drawn from the positive electrode current collector, and welded to an aluminum pressure release valve mounted on the battery cover to manufacture a battery. An electrolyte was injected into the prepared battery, and LiPF ₆ was used as a solvent and an electrolyte in which EC and EMC were mixed in a volume ratio of 1: 2.

The battery prepared as described above was charged to 4.2V with a constant current. The standard capacity of the electrolyte secondary battery was 2200 mAh, and the efficiency was measured at a rate of 1 C (2200 mA / h) and 0.2 C (440 mA / h) with constant current from 4.2 V to 3 V, and then the safety test of the battery was conducted. .

Example 2

A battery was manufactured in the same manner as in Example 1, except that the foaming agent was changed to 3 parts by weight, respectively, to prepare a positive electrode and a negative electrode slurry.

Example 3

A battery was manufactured in the same manner as in Example 1, except that the foaming agent was changed to 7 parts by weight, respectively, to prepare a positive electrode and a negative electrode slurry.

Comparative Example 1

A battery was manufactured in the same manner as in Example 1, except that no blowing agent was added to prepare a cathode and an anode slurry.

Experimental Example 1. Evaluation of physical properties of the electrode

In order to evaluate the resistance change according to the temperature of the electrode containing the blowing agent according to the present invention, it was performed as follows.

In Example 1, an electrode containing a blowing agent was used, and the electrode of Comparative Example 1 prepared according to a conventional method in the art was used as a control thereof.

1 shows a change in the resistance of each electrode while increasing the temperature. It can be seen that the electrode of Comparative Example 1, which does not contain a blowing agent, also decreases in resistance as temperature increases. On the other hand, it was found that the electrode of Example 1 containing the foaming agent began to increase in resistance after 110 ° C. and showed a much higher resistance value than the electrode of Comparative Example 1 up to 140 ° C. (see FIG. 1). This means that the blowing agent as a component of the electrode increased the resistance of the electrode while discharging a large amount of nitrogen gas.

Therefore, the electrode containing the foaming agent of the present invention was confirmed that due to the volume expansion caused by a large amount of gas ejection pressure, the interval between the electrode active material particles in the electrode is instantaneously increased to suppress the high current flow through the increase in resistance.

Experimental Example 2. Evaluation of Safety of Battery

In order to evaluate the safety of the lithium secondary battery having an electrode containing a blowing agent according to the present invention, it was performed as follows.

The lithium secondary batteries prepared in Examples 1 to 3 were used, and the lithium secondary batteries of Comparative Example 1 prepared in accordance with conventional methods known in the art were used without using a blowing agent as a control.

1-1. Hot box experiment

Each cell was stored for 4 hours at a high temperature of 160 ° C., respectively, after which the state of the cell is shown in Table 1 below.

As a result of the experiment, the lithium secondary battery of Comparative Example 1 having an electrode prepared according to a conventional method without using a foaming agent caused a decrease in safety of the battery by about 50%, whereas the batteries of Examples 1 to 3 containing the foaming agent were It showed an excellent safety improvement effect, in particular, the battery of Example 3 prepared by using the content of the blowing agent in 7 parts by weight was confirmed that the fire and explosion does not occur at all has an excellent safety improvement effect (see Table 1) .

1-2. Overcharge Experiment

Each battery was charged under the condition of 12V / 1C, and then the state of the battery is shown in Table 1 below.

Similar to the hot box test results, the battery of Examples 1 to 3 containing the blowing agent has an excellent safety improvement effect compared to the lithium secondary battery of Comparative Example 1 having an electrode prepared according to a conventional method without using a blowing agent. It was confirmed that the (see Table 1).

1-3. Penetration Experiment

Nail penetration test was performed using each cell, and then the state of the cell is described in Table 1 below.

Similar to the results of the hot box test and the overcharge test, the batteries of Examples 1 to 3 containing the foaming agent have excellent safety compared to the lithium secondary battery of Comparative Example 1 having the electrode prepared according to a conventional method without using the foaming agent. It was confirmed again that the improvement effect was shown (refer Table 1).

The present invention can significantly improve the safety that has been pointed out as a problem of a conventional lithium secondary battery by using a blowing agent as a coating component or an electrode additive of an electrode.

Claims (14)

An electrode characterized in that a blowing agent is released on the electrode surface or mixed with the electrode material at a temperature T above the normal operating temperature range of the cell. The electrode of claim 1, wherein the temperature (T) is higher than a normal operating temperature of the battery and lower than a temperature at which decomposition reaction of the electrolyte solution provided in the battery occurs. The electrode of claim 1, wherein the temperature (T) is in the range of 130 to 150 ° C. 3. The electrode of claim 1, wherein the gas is at least one inert gas selected from the group consisting of N ₂ , He, Ne, Ar, Kr, and Xe. The electrode of claim 1, wherein the electrode is blocked from contact with oxygen due to a gas other than oxygen generated from a blowing agent in a temperature T range above a normal operating temperature of the battery. The electrode according to claim 1, wherein the electrode extends the distance between the electrode active material particles in the electrode through volume expansion by the gas ejection pressure generated from the blowing agent in a temperature (T) range above the normal operating temperature of the battery. The electrode of claim 1, wherein the electrode operates the vent through an increase in internal pressure inside the cell by a gas generated from a blowing agent in a temperature (T) range above a normal operating temperature. The electrode of claim 1, wherein the blowing agent is an azo (-N = N-)-based compound. The electrode of claim 8, wherein the azo compound is a compound represented by Formula 1 below. [Formula 1]

The electrode according to claim 1, wherein the content of the blowing agent is 0.05 to 10 parts by weight per 100 parts by weight of the electrode active material. An electrochemical device comprising an anode, a cathode, a separator and an electrolyte, wherein the anode, the cathode, or the positive electrode is an electrode according to any one of claims 1 to 10. The electrochemical device of claim 11, wherein the electrochemical device is a lithium secondary battery. (a) mixing the blowing agent with the electrode material and then applying it on the current collector or coating the surface of the electrode prepared; And (b) drying the electrode Method for producing an electrode containing a blowing agent comprising a. The method of claim 13, wherein the mixing of the blowing agent with the electrode material (a) comprises preparing an electrode slurry by dispersing an electrode active material, a binder, and a blowing agent in a solvent.

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