KR102617202B1 - Secondary battery to cause defects and Method for evaluating the characteristics of the Secondary battery - Google Patents

Abstract

The purpose of the present invention is to provide a secondary battery for causing defects and a method for evaluating the characteristics of the secondary battery, which can specifically observe the battery's deterioration and ignition according to defect factors without deforming the battery.
In order to achieve the above object, a secondary battery for causing defects according to the present invention includes an electrode assembly including a negative electrode, a positive electrode, and a separator stacked between the negative electrode and the positive electrode, an exterior material surrounding the electrode assembly, and a defect factor contained therein. It may include a capsule disposed inside the electrode assembly or inside the exterior material, and the capsule may be opened by physical stimulation.

Description

Secondary battery to cause defects and Method for evaluating the characteristics of the secondary battery}

The present invention relates to secondary batteries, and more specifically, to secondary batteries for causing defects that are physically open and capable of simulating defects in a battery, including factors that cause defects.

A secondary battery is a battery that converts chemical energy into electrical energy to supply power to an external circuit, and when discharged, receives external power and converts electrical energy into chemical energy to store electricity. It is also commonly called a storage battery. .

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has increased. Among rechargeable secondary batteries, lithium secondary batteries, which are attracting attention as a next-generation power source, have high energy density, no memory effect, and can be used even when not in use. The degree of spontaneous discharge is small and it is very light, so it is widely used in portable electronic devices such as laptops, cameras, and cell phones. In addition, due to its high energy density characteristics, its use is increasingly being used in the defense industry, automation systems, and automobile and aviation industries. In particular, it is widely used as a motor drive source for electric vehicles and hybrid vehicles.

With the recent growth of the electric vehicle and energy storage system (ESS) markets, issues of reliability and safety of secondary batteries are becoming important. Therefore, there is a need to identify the causes of safety accidents such as battery ignition and energy storage device fire. In order to identify various causes of ignition, analysis of deteriorated and ignited batteries and electrochemical evaluation of similar batteries are performed, but not only does it take a lot of time and manpower, but it is not easy to identify the exact cause of ignition because various defect factors are complexly intertwined.

In order to solve the above problem, referring to Republic of Korea Patent Publication No. 10-2019-0088763, as shown in FIG. 1, a lithium secondary battery including a conventional short circuit trigger device includes a short circuit trigger device that generates an internal short circuit. The short-circuit inducing device includes a positive electrode active material layer 10, a conductive paste layer 20, a separator 50 located between the positive electrode active material layer 10 and the conductive paste layer 20, and a positive electrode active material layer 10. It includes a first wax layer 40 located between the separator 50 and a second wax layer 40 located between the conductive paste layer 20 and the separator 50, and a metal foil portion 60 within the separator 50. ) is inserted and the temperature inside the battery exceeds 60 degrees Celsius during battery operation, the first and second wax layers (30, 40) are liquefied and flow out, resulting in the positive electrode active material layer (10) and the conductive paste layer. As the metal foil portion 60 between (20) is in direct contact with the positive electrode active material layer 10 and the conductive paste layer 20, current may flow through the metal foil portion 60, causing an internal short circuit.

However, the conventional technology can only observe the thermal runaway pattern of the battery, and the battery after thermal runaway is physically damaged, making it difficult to directly analyze the phenomenon inside the battery due to defects.

Republic of Korea Patent Publication No. 10-2019-0088763 (publication date 2019.07.29.)

The present invention was developed to solve the above-mentioned problems, and the secondary battery and its characteristics for causing defects can specifically observe the battery's deterioration and ignition due to defect factors without deforming the battery. The purpose is to provide an evaluation method.

A secondary battery for causing defects according to the present invention includes an electrode assembly including a cathode, an anode, and a separator stacked between the cathode and the anode, an exterior material surrounding the electrode assembly, and a defect factor accommodated therein, and inside the electrode assembly. Alternatively, it may include a capsule disposed inside the exterior material, and the capsule may be opened by physical stimulation.

Furthermore, the electrode assembly further includes a hole formed in at least one of the cathode, the separator, and the anode, and the capsule can be inserted into the hole.

At this time, the perforation may be formed across the cathode and the separator, between the separator and the anode, or across all of the cathode, the separator, and the anode.

Furthermore, the electrode assembly further includes a negative electrode tab connected to the negative electrode and a positive electrode tab connected to the positive electrode, and the capsule is between the area where the negative electrode and the negative electrode tab overlap each other and the exterior material, and the positive electrode and the positive electrode tab. It may be disposed in at least one of the areas where the positive electrode tab overlaps and the exterior material.

Additionally, the capsule may be disposed in a surplus space between the exterior of the electrode assembly and the exterior material.

In addition, the defect factors include deteriorated electrode particles, metal particles, dendritic lithium, solids consisting of lithium powder, water, hydrogen fluoride (HF), metal ions, Dimethyl Ether, Triphenyl Phosphate, vinylen carbonate, Fluorinated carbonate, and Lithium Difluorophosphate. Containing at least one selected from the group consisting of an electrolyte solution containing a high concentration of electrolyte additives, a fire extinguishing agent containing at least one of sodium bicarbonate, potassium bicarbonate, and ammonium phosphate, a flame retardant, a gas generator, and an interface stabilizer. It may be made of at least one of an electrolyte, an electrolyte with a lower concentration than the electrolyte contained in the electrode assembly, a liquid consisting of an electrolyte with a higher concentration than the electrolyte contained in the electrode assembly, and a gas consisting of any one of hydrogen, methane, ethane, and carbon dioxide.

Furthermore, the capsule is made of PVdF (Polyvinylidene fluoride), SBR (Styrene-butadiene), polyimide, polyisobutylene, Sodium Carboxymethyl Cellulose, polyacrylic acid, It may include a capsule exterior material of either polyvinyl alcohol or wax.

Furthermore, the physical stimulus that opens the capsule may be at least one of a certain pressure, a certain temperature, a magnetic field of a certain magnitude, an electromagnetic wave of a certain intensity, and an X-ray of a certain intensity.

The method for evaluating the characteristics of a secondary battery according to the present invention includes (1) an electrode assembly including a negative electrode, a positive electrode, and a separator laminated between the negative electrode and the positive electrode, an exterior material surrounding the electrode assembly, and a defect factor contained therein; , providing a secondary battery including a capsule disposed inside the electrode assembly or inside the exterior material, (2) applying a physical stimulus capable of releasing defective factors by opening the capsule to the secondary battery, and ( 3) It may be characterized by comprising the step of analyzing the behavior of the secondary battery in which a defect has occurred.

At this time, step (2) may apply at least one physical stimulus among pressure, temperature, magnetic field, electromagnetic waves, and X-rays to the capsule.

In addition, step (3) is at least one of a change in the voltage profile during charging and discharging of the secondary battery due to the release of the defect agent, a change in temperature at the site of the release of the defect agent, deterioration, ignition, and expansion of the thickness of the secondary battery compared to before the release of the defect agent. At least one behavior may be analyzed among analysis before disassembly of the battery and analysis after disassembly of the battery including at least one of observation of anode and cathode surface changes, observation of surface composition changes, changes in crystal structure, and changes in electrode cohesion.

In the secondary battery for causing defects according to the present invention through the above configuration, the capsule disposed on the inside of the electrode assembly or the exterior material surrounding the electrode assembly is opened, and defect factors are leaked, thereby preventing deterioration and ignition of the battery. It can be observed in-situ.

In addition, since the capsule is installed within the battery, deterioration and ignition of the battery due to defective factors can be checked without external physical damage or deformation of the battery, and the installation location can be freely adjusted by adjusting the size of the capsule. Deterioration and ignition phenomena can be confirmed in various locations.

In addition, since the type and content of defect factors within the capsule can be freely adjusted, the behavior of the battery can be analyzed in various environments for defect factors, and a database on deterioration and ignition patterns can be established.

In addition, since the capsule opening timing can be adjusted, electrochemical signals of defective factors can be directly observed according to battery operating conditions, and since defective factors are expressed without deformation of the battery, analysis after battery deterioration is possible. .

Figure 1 is a cross-sectional view of a Ritschoon secondary battery including a conventional short circuit inducing device.
Figure 2 is a front view of a secondary battery for causing defects according to the present invention.
Figure 3 is an exploded view of the electrode assembly according to the present invention
Figure 4 is a capsule opening implementation diagram according to the present invention.
5 is a cross-sectional view of first to third examples of secondary batteries for causing defects according to the present invention.
Figure 6 is a perspective view of a fourth embodiment of a secondary battery for causing defects according to the present invention.
Figure 7 is a perspective view of a fifth embodiment of a secondary battery for causing defects according to the present invention.
8 is a flowchart of a method for evaluating characteristics of a secondary battery according to the present invention.
Figure 9 shows the voltage profile before and after expression of the defective factor according to Example 1.
Figure 10 is a photograph confirming that the battery swelled due to the generation of gas, which is an electrolyte side-reactant, after the defect factors of Comparative Example 1 and Example 2 were expressed.

Hereinafter, the technical idea of the present invention will be described in more detail using the attached drawings. Prior to this, the terms or words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor should appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle of definability.

Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent the entire technical idea of the present invention, so at the time of filing this application, various alternatives are available to replace them. It should be understood that variations may exist.

Hereinafter, the technical idea of the present invention will be described in more detail using the attached drawings. The attached drawings are merely examples to illustrate the technical idea of the present invention in more detail, so the technical idea of the present invention is not limited to the form of the attached drawings.

Referring to FIGS. 2 to 4, the secondary battery 1000 for causing defects according to the present invention includes a cathode 110, an anode 120, and a separator stacked between the cathode 110 and the anode 120. An electrode assembly 100 including an electrode assembly 100 (130), an exterior material 200 surrounding the electrode assembly 100, and a defect factor 310 accommodated therein, inside the electrode assembly 100 or inside the exterior material 200. It may include a capsule 300 disposed, and the capsule 300 may be opened by physical stimulation.

As shown in FIG. 3, the electrode assembly 100 is formed by stacking a separator 130 between the cathode 110 and the anode 120.

The exterior material 200 covers the entire outer surface of the electrode assembly 100, and the electrode assembly 100 is wrapped in the exterior material 200 and maintained in a laminated state.

As shown in FIG. 4, the defective factor 310 is accommodated inside the capsule 300. The capsule 300 is disposed inside the electrode assembly 100 or inside the exterior material 200, and the capsule 300 is opened by physical stimulation to remove the defect factor 310 inside the capsule 300. flows out inside the electrode assembly 100 or inside the exterior material 200.

The capsule 300 may be placed inside the electrode assembly 100, may be placed between the electrode assembly 100 and the exterior material 200, and may be disposed between the upper and lower surfaces of the exterior material 200. It may be deployed.

In the secondary battery 1000 for causing defects according to the present invention through the above configuration, the capsule 300 disposed inside the electrode assembly 100 or the exterior material 200 surrounding the electrode assembly 100 is opened and the defect occurs. As the agent 310 flows out, deterioration and ignition of the battery 1000 can be observed in-situ where the capsule 300 was placed.

In addition, the defect factor 310 is a solid made of any one of deteriorated electrode particles, metal particles, dendritic lithium, lithium powder, water, hydrogen fluoride (HF), metal ion, Dimethyl Ether, Triphenyl Phosphate, vinylen carbonate, and Fluorinated carbonate. At least one selected from the group consisting of an electrolyte containing a high concentration of electrolyte additives such as Lithium Difluorophosphate, a fire extinguishing agent containing at least one of sodium bicarbonate, potassium bicarbonate, and ammonium phosphate, a flame retardant, a gas generator, and an interface stabilizer. A liquid consisting of any one of the electrolyte solution contained therein, an electrolyte solution with a lower concentration than the electrolyte solution contained in the electrode assembly 100, an electrolyte solution with a higher concentration than the electrolyte solution contained in the electrode assembly 100, and any of hydrogen, methane, ethane, and carbon dioxide. It may be composed of at least one of the gases composed of one.

That is, the defective factor 310 may be composed of at least one of solid, liquid, and gas, and a complex of defective factors 310 having different material forms may be accommodated in the capsule 300.

In addition, the capsule 300 is made of polyvinylidene fluoride (PVdF), styrene-butadiene (SBR), polyimide, polyisobutylene, sodium carboxymethyl cellulose, and polyacrylic acid. ), polyvinyl alcohol, and wax, the capsule 300 may include an exterior material 200.

The exterior material 200 of the capsule 300 is a material that makes up the capsule 300 and may be formed of any of the above materials.

Additionally, the physical stimulus that opens the capsule 300 may be at least one of a certain pressure, a certain temperature, a magnetic field of a certain size, an electromagnetic wave of a certain intensity, and an X-ray of a certain intensity.

That is, the capsule 300 is opened by stimulation of any one of a certain pressure, a certain temperature, a magnetic field of a certain magnitude, an electromagnetic wave of a certain intensity, or an X-ray of a certain intensity, and the defect factor 310 is released into the capsule 300 It may leak out.

In addition, the shape of the capsule 300 may be cylindrical, capsule 300, rectangular, spherical, cuboid, micelle, etc., but is not limited to this and any shape that can be developed by a certain physical stimulus can be applied. possible.

Referring to FIG. 5(a), the electrode assembly 100 further includes a perforation 140 formed in at least one of the cathode 110, the separator 130, and the anode 120, and the Capsule 300 may be inserted into the hole 140. Since the capsule 300 must store the defective factor 310 inside, it has an internal accommodation space and forms a certain volume. Therefore, when the capsule 300 is placed inside the electrode assembly 100 or the exterior material 200, the overall size or thickness of the secondary battery increases. Accordingly, the perforation 140 is formed in at least one of the cathode 110, the separator 130, and the anode 120, and the capsule 300 is inserted into the perforation 140 to form a secondary battery. It can prevent the overall size or thickness from increasing.

The perforation 140 may be formed only in one of the cathode 110, the separator 130, and the anode 120.

In addition, the perforation 140 is formed across the cathode 110 and the separator 130, or between the separator 130 and the anode 120, or between the cathode 110 and the separator 130. ), can be formed across all of the anode 120.

A plurality of the perforations 140 may be formed at different positions, and the perforations 140 may be connected to the separator 130 or one of the separator 130 and the cathode 110 or the anode 120. When formed over, the capsule 300 is preferably inserted into the perforated hole 140 so that the anode 120 and the cathode 110 do not come into contact.

Referring to FIG. 5(b), the capsule 300 may be placed on the side of the electrode assembly 100 in which the cathode 110, the separator 130, and the anode 120 are stacked. The outer peripheral surface of the capsule 300 is preferably formed in contact with at least one of the cathode 110, the separator 130, and the anode 120.

Referring to FIG. 5(c), the capsule 300 is between the cathode 110 and the separator 130 in a state in which the cathode 110, the separator 130, and the anode 120 are stacked. It may be stacked and arranged between the separator 130 and the anode 120.

Referring to FIG. 6, the electrode assembly 100 further includes a cathode 110 tab connected to the cathode 110 and an anode 120 tab connected to the anode 120, and the capsule 300 Between the area where the negative electrode 110 and the negative electrode 110 tab overlap and the exterior material 200, and between the area where the positive electrode 120 and the positive electrode 120 tab overlap and the exterior material 200. It can be placed in at least one or more.

That is, with the capsule 300 disposed at the point where the negative electrode 110 tab and the negative electrode 110 are connected or the positive electrode 120 tab and the positive electrode 120, the exterior material 200 ) may surround the electrode assembly 100 and the capsule 300.

Referring to FIG. 7 , the capsule 300 may be disposed in the excess space between the exterior of the electrode assembly 100 and the exterior material 200. The surplus space refers to an area in which the electrode assembly 100 is not formed when the exterior material 200 surrounds the electrode assembly 100, and at least a portion of the capsule 300 disposed in the surplus space is It may be in contact with the electrode assembly 100 or may not be in contact with the electrode assembly 100 at all.

Referring to FIG. 8, the method for evaluating the characteristics of a secondary battery according to the present invention includes (1) a cathode 110, an anode 120, and a separator 130 laminated between the cathode 110 and the anode 120. An electrode assembly 100 including an exterior material 200 surrounding the electrode assembly 100, and a defective factor 310 accommodated therein, which is disposed inside the electrode assembly 100 or inside the exterior material 200. Providing a secondary battery 1000 including a capsule 300, (2) applying a physical stimulus to the secondary battery 1000 to open the capsule 300 and release a defect factor 310. and (3) analyzing the behavior of the defective secondary battery 1000.

At this time, step (2) is characterized by applying at least one physical stimulus among pressure, temperature, magnetic field, electromagnetic waves, and X-rays to the capsule 300.

In addition, step (3) is a change in the voltage profile during charging and discharging of the secondary battery 1000 due to the emission of the defect factor 310, a change in temperature at the emission site of the defect factor 310, deterioration, ignition, and defect factor. (310) Analysis before disassembly of the battery, including at least one of the following: expansion of the thickness of the secondary battery (1000) compared to before discharge, observation of surface changes of the anode (120) and cathode (110), observation of surface composition changes, crystal structure changes, and electrode binding force changes. At least one behavior may be analyzed during analysis after disassembly of a battery including at least one battery.

That is, in the method for evaluating the characteristics of a secondary battery according to the present invention, the behavior of the secondary battery 1000 including the capsule before or after disassembly can be analyzed after applying a physical stimulus to the capsule 300.

Referring to FIGS. 9 and 10, the experimental process and experimental results, including the characteristics of the secondary battery 1000 and the method for evaluating the characteristics of the secondary battery for causing defects according to the present invention, are as follows.

The electrode assembly 100 of Examples 1 and 2 includes the anode 120 containing 93% by weight of a transition metal oxide, Li(Ni _0.8 Mn _0.1 Co _0.1 )O ₂ (L&F, Korea), and a conductive material (Super P Li ^ㄾ , Imerys). ) 4% by weight, polyvinylidene fluoride (PVdF, KF-1300, Kureha) 3% by weight, the cathode (110) is 92% by weight of graphite, 4% by weight of conductive material (Super P Li ^ㄾ , Imerys), It was designed with 4% by weight of CMC/SBR. The electrolyte is an organic solvent mixture of ethylene carbonate/ethylmethyl carbonate (volume ratio 3/7) (ENCHEM, Korea) containing 1.15 M of LiPF ₆ , a lithium salt, and PE is used as the separator 130. did.

(Example 1)

In Example 1, when the defect factor 310 capsule 300 containing an electrolyte solution with a high concentration of HF was placed between the anode 120 and the separator 130 and a certain pressure was applied, the voltage profile of the secondary battery was A changed to B. As the defect factor (310) HF was expressed, abnormal signals were observed in the discharge section due to decomposition of lithium salt/solvent and formation of side reaction products, and a thick film was formed on the anode (120)/cathode (110), increasing resistance in the battery. It was confirmed that the CV section became longer due to this.

In addition, after 20 cycles starting from the expression of the defective factor 310, it was observed that the thickness of the battery increased about twice compared to the previous one. In particular, when the cell in which the defective factor 310 was expressed was driven at high temperature, Likewise, it was confirmed that the capacity maintenance rate decreased significantly.

When the battery was dismantled after operation and the lithium content of the electrolyte was quantitatively analyzed, it was confirmed that about 25% of the lithium was consumed compared to the original. This was determined to be due to lithium salt decomposition and side reactions due to the expression of the defect factor (310). .

(Example 2)

Referring to FIG. 10, Comparative Example 1 is a secondary battery manufactured based on the same battery information as Example 2 without a capsule containing a defect factor in the secondary battery, and in Example 2, transition metal ions (M ⁴⁺ , M = The defect factor (310) capsule (300) containing the electrolyte containing (Mn, Ni) was placed outside the jelly roll containing the electrode, and then a certain pressure was applied.

As the electrolyte defect factor 310 containing transition metal ions is expressed, it is expected that a resistance layer of the MF ₂ component will be created on the anode 120 and that the metal will be eluted and electrodeposited on the cathode 110, resulting in an increase in battery resistance and Capacitance reduction was observed in the voltage profile. In addition, after 20 cycles starting from the expression of the defect factor 310, it was observed that the thickness of the battery increased by about 3.5 times compared to the previous one, as shown in FIG. 10.

The present invention is not limited to the above-described embodiments, and the scope of application is diverse. Of course, various modifications and implementations are possible without departing from the gist of the present invention as claimed in the claims.

1000: Secondary battery to cause defects
100: electrode assembly 110: cathode
111: negative tab 120: positive electrode
121: anode tab 130: separator
140: perforation
200: Exterior material
300: Capsule 310: Defect factor

Claims (11)

An electrode assembly including a cathode, an anode, and a separator stacked between the cathode and the anode;
An exterior material surrounding the electrode assembly; and
It includes a capsule containing a defective factor therein and disposed inside the electrode assembly or inside the exterior material,
A secondary battery for evaluating battery characteristics by causing defects, wherein the capsule is opened by physical stimulation.
According to clause 1,
The electrode assembly is,
It further includes a perforation formed in at least one of the cathode, the separator, and the anode,
A secondary battery for evaluating battery characteristics by causing defects in which the capsule is inserted into the hole.
According to clause 2,
The perforation is,
A secondary battery for evaluating battery characteristics by causing defects, which is formed across the cathode and the separator, between the separator and the anode, or across all of the cathode, the separator, and the anode.
According to clause 1,
The electrode assembly is,
a negative electrode tab connected to the negative electrode; and
It further includes a positive electrode tab connected to the positive electrode,
The capsule is,
A secondary battery for evaluating battery characteristics by causing defects, which is disposed between at least one of the area where the negative electrode and the negative electrode tab overlap and the exterior material, and between the area where the positive electrode and the positive electrode tab overlap and the exterior material.
According to clause 1,
The capsule is,
A secondary battery for evaluating battery characteristics by causing defects, which is disposed in the surplus space between the outside of the electrode assembly and the exterior material.
According to clause 1,
The defect factor is,
A solid consisting of any one of deteriorated electrode particles, metal particles, dendritic lithium, and lithium powder,
Electrolyte containing a high concentration of electrolyte additives such as water, hydrogen fluoride (HF), metal ions, Dimethyl Ether, Triphenyl Phosphate, vinylen carbonate, Fluorinated carbonate, Lithium Difluorophosphate, or any one or more of sodium bicarbonate, potassium bicarbonate, and ammonium phosphate. An electrolyte solution containing at least one selected from the group consisting of extinguishing substances, flame retardants, gas generators, and interface stabilizers, an electrolyte solution with a lower concentration than the electrolyte solution included in the electrode assembly, and an electrolyte solution with a higher concentration than the electrolyte solution included in the electrode assembly. A liquid consisting of any of the following, and
A secondary battery for evaluating battery characteristics by causing defects made of at least one of the following gases: hydrogen, methane, ethane, or carbon dioxide.
According to clause 1,
The capsule is,
PVdF (Polyvinylidene fluoride), SBR (Styrene-butadiene), Polyimide, Polyisobutylene, Sodium Carboxymethyl Cellulose, Polyacrylic Acid, Polyvinyl Alcohol ) and wax for evaluating battery characteristics by causing defects, including a capsule exterior material.
According to clause 1,
The physical stimulus that opens the capsule is,
A secondary battery for evaluating battery characteristics by causing defects to which at least one of a certain pressure, a certain temperature, a magnetic field of a certain size, electromagnetic waves of a certain intensity, and X-rays of a certain intensity is applied.
(1) an electrode assembly including a cathode, an anode, and a separator stacked between the cathode and the anode, an exterior material surrounding the electrode assembly, and a defective factor accommodated therein, and disposed inside the electrode assembly or inside the exterior material. Providing a secondary battery including a capsule;
(2) applying a physical stimulus to the secondary battery to open the capsule and release defective factors; and
(3) analyzing the behavior of a defective secondary battery;
Method for evaluating characteristics of secondary batteries including.
According to clause 9,
In step (2),
A method for evaluating the characteristics of a secondary battery, comprising applying at least one physical stimulus of pressure, temperature, magnetic field, electromagnetic waves, and X-rays to the capsule.
According to clause 9,
In step (3),
of the secondary battery due to the release of the defective factor.
Analysis before disassembly of the battery, including at least one of the following: voltage profile change during charging and discharging, temperature change at the defect factor release site, deterioration, ignition, and secondary battery thickness expansion compared to before defect factor release; and
Analysis after disassembly of the battery, including at least one of observation of changes in anode and cathode surfaces, changes in surface composition, changes in crystal structure, and changes in electrode cohesion.
A method for evaluating the characteristics of secondary batteries that analyzes the behavior of at least one of the following:

Images