KR102518227B1 - Evaluation Method and Apparatus for Swelling Characteristics of Electrolyte - Google Patents

Abstract

The present invention simplifies the internal gas generation amount measurement method, which is the cause of the swelling phenomenon on the side of the electrolyte in the battery cell development stage, in units of monocells, and measures the gas generation amount in real time to effectively evaluate the swelling characteristics of the electrolyte. And it relates to providing a method, the swelling (Swelling) characteristic evaluation apparatus of the electrolyte according to the present invention is a chamber formed with a mono-cell seating portion therein; a punching unit disposed on the chamber and punching the monocell seated in the chamber; a vent portion including a vent hole communicating with the monocell mounting portion from the lower side of the chamber; and a sensing unit connected to the vent unit and including an in-situ gas pressure sensor.

Description

Swelling characteristics evaluation device and evaluation method of electrolyte {Evaluation Method and Apparatus for Swelling Characteristics of Electrolyte}

The present invention relates to an apparatus and method for evaluating swelling characteristics of an electrolyte solution using a lithium secondary battery monocell.

Recently, secondary batteries capable of charging and discharging have been widely used as energy sources for wireless mobile devices. In addition, secondary batteries are attracting attention as an energy source for electric vehicles, hybrid electric vehicles, etc., which are proposed as a solution to air pollution such as existing gasoline vehicles and diesel vehicles using fossil fuels. Therefore, the types of applications using secondary batteries are diversifying due to the advantages of secondary batteries, and it is expected that secondary batteries will be applied to more fields and products than now.

Such a secondary battery is formed by storing an electrode assembly including a cathode, a separator, and a cathode in a pouch and then injecting an electrolyte into the pouch. The positive and negative electrodes constituting the electrode assembly of the secondary battery are formed by coating a positive electrode material and a negative electrode material on an electrode sheet. Secondary batteries require various performances according to the device to which they are applied. Accordingly, it is necessary to develop secondary batteries using various cathode and anode materials and electrolytes.

In general, when a secondary battery operates in an abnormal state due to overcharging, overdischarging, overheating, external shock, etc., gas may be generated inside. For example, an overheated battery generates gas, and the gas pressurized in the case further accelerates the decomposition reaction of battery elements, causing continuous overheating and gas generation, and swelling may occur. This phenomenon also appears in the process of gradually deteriorating the secondary battery due to long-term use. Therefore, a screening evaluation method for new materials to improve swelling in terms of electrolyte solution is needed in the material development stage, which is the stage before product development.

In general, a secondary battery swelling test uses a small cell formed by configuring an electrode assembly with a positive electrode, a negative electrode, and a separator, storing the electrode assembly in a pouch, and injecting an electrolyte solution. Exposing the small cell to a high-temperature environment evaluates the degree to which gas is generated. 1 is a diagram illustrating a thickness measuring device 100 for measuring a thickness variation of a small cell during such a swelling test. As shown in Figure 1, the thickness measuring instrument 100 is a small cell 101 is seated portion 111 and the measuring device 112 for measuring the thickness of the small cell 101 to be seated portion 111 ) Is provided at the top, and includes a weight 113 for constantly applying pressure to the small cell 101 seated on the seating portion 111.

The secondary battery swelling test using the small cell takes one month or more from material preparation of the small cell to the cell evaluation step.

Therefore, since it takes a lot of time to perform a swelling test for all candidates of the electrolyte, a method for simply checking performance in a short period of time is required.

An object of the present invention is to solve the problems of the prior art and the technical problems that have been requested from the past.

Specifically, an object of the present invention is to evaluate the swelling characteristics of the electrolyte, and simplify the method of measuring the amount of internal gas generation, which is the cause of the swelling phenomenon on the side of the electrolyte in the battery cell development stage, in units of monocells, and the amount of gas generation It is to provide a device and method for effectively evaluating swelling characteristics of an electrolyte by measuring in real time.

An apparatus for evaluating swelling (Swelling) characteristics of an electrolyte according to the present invention for achieving this object includes a chamber having a mono-cell seating portion formed therein; a punching unit disposed on the chamber and punching the monocell seated in the chamber; a vent portion including a vent hole communicating with the monocell mounting portion from the lower side of the chamber; and a sensing unit connected to the vent unit and including an in-situ gas pressure sensor.

In the present invention, it is characterized in that a vacuum pump is connected to the outside of the swelling property evaluation device of the electrolyte.

In the present invention, the vacuum pump is characterized in that connected through the opening and closing valve of the vent unit.

In the present invention, the chamber is characterized in that the lower and upper parts are completely hermetically coupled by an O-ring.

In the present invention, the punching unit is characterized in that it includes a punch, a punch head formed on the upper part of the punch, and a spring positioned around the punch.

In the present invention, it is characterized in that the punching unit is disposed to be sealed with the chamber.

In the present invention, it is characterized in that it includes a temperature control device capable of adjusting the internal temperature of the chamber in the range of 10 ℃ to 100 ℃.

In the present invention, the gas pressure measurement range of the sensing unit is characterized in that -10 to 20 Bar.

In the present invention, the swelling property evaluation apparatus of the electrolyte is characterized in that it further comprises a control unit for calculating the pressure change and gas generation amount according to the signal from the signals received from the pressure sensor.

To achieve this object, the swelling property evaluation method of the electrolyte solution according to the present invention is a method for evaluating the swelling property of the electrolyte solution by the swelling property evaluation device of the electrolyte solution, and includes one anode, one separator and A mono-cell manufacturing step of manufacturing a mono-cell including one negative electrode (S10); An electrolyte injection step of injecting an electrolyte to be evaluated into the monocell (S20); A monocell preparation step (S30) of aging, forming, and degassing the monocell injected with the electrolyte at room temperature;

A mono-cell full filling step (S40) of fully filling the mono-cell; A monocell seating step (S50) of seating the monocell on the monocell seating portion of the device, sealingly coupling the chamber of the device, and creating a vacuum environment inside the chamber; A mono-cell punching step (S60) to perforate the movement of gas generated inside the mono-cell; And a gas pressure measuring step (S70) of heating, storing and lowering the monocell at a high temperature, and measuring in-situ the gas generated inside the monocell in each process with a pressure sensor. .

In the present invention, it is characterized in that the electrolyte is injected into the monocell in the range of 500 μl or less in the electrolyte injection step (S20).

In the present invention, it is characterized in that it further comprises the step of stabilizing the monocell at 0 ℃ to 30 ℃ for 1 hour or more before the gas pressure measuring step (S70).

In the present invention, the mono-cell temperature raising step (S71) of heating the mono-cell to generate gas inside the mono-cell; A mono-cell storage step (S72) of storing in a high-temperature environment reached through the temperature-raising step; And characterized in that it comprises a mono-cell heating step (S73) of cooling the mono-cell of the mono-cell storage step.

In the present invention, in the monocell temperature raising step (S71), it is characterized in that the monocell is heated for 30 minutes or more in the range of 50 ℃ to 100 ℃.

In the present invention, in the monocell storage step (S72), it is characterized in that the monocell is stored for 12 hours to 48 hours in the range of 50 ℃ to 100 ℃.

In the present invention, the monocell heating step (S73) is characterized in that the monocell is cooled for 30 minutes or more in the range of 0 ℃ to 30 ℃.

The swelling property evaluation device and evaluation method of the electrolyte according to the present invention uses a monocell that can be simply manufactured using one anode/cathode/separator sheet in order to achieve an environment similar to that of an actual battery, and simplifies the evaluation method in a short period of time. Thus, there is an effect of quickly screening the swelling characteristics at high temperatures of new materials for the development of an electrolyte solution in a small amount.

In addition, the swelling property evaluation apparatus and evaluation method of the electrolyte solution according to the present invention uses a newly manufactured device for the purpose of measuring the gas generated under high temperature inside the battery as a pressure sensor, thereby evaluating the characteristics of the battery in an actual high temperature storage environment. There is an effect that can be reflected.

1 is a schematic diagram showing how to measure the thickness of a small cell using a conventional thickness meter;
Figure 2 is a perspective view showing an electrolyte swelling characteristic evaluation apparatus according to one embodiment of the present invention;
3 is a side view showing an electrolyte swelling characteristic evaluation apparatus according to an embodiment of the present invention;
Figure 4 is a plan view showing a position where perforations are created with a monocell and a punch unit used in the present invention;
5 is a side view illustrating a lower part of the chamber, a vent part, and a sensing part of FIGS. 2 and 3;
6 is a plan view illustrating a lower part of the chamber, a vent part, and a sensing part of FIGS. 2 and 3;
Fig. 7 is a side view showing the punching part of the upper part of the chamber of Figs. 2 and 3;
8 is a graph showing test results of monocells injected with electrolytes to be evaluated according to an embodiment of the present invention;
9 is a flowchart showing the sequence of the electrolyte swelling property evaluation method of the present invention.

Hereinafter, description will be made with reference to drawings according to embodiments of the present invention, but this is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

In the present invention, when a component is referred to as being “connected” to another component, it should be understood that it may be directly connected to the other component or another component may exist in the middle.

As shown in Figures 2 and 3, the electrolyte swelling (Swelling) characteristic evaluation apparatus 200 according to the present invention is a chamber 210, the mono-cell mounting portion 201 is formed therein; a punching unit 220 disposed on the chamber 210 and punching the monocell seated in the chamber 210; A vent part 230 including a vent hole (Vent Hole, 231) communicating with the monocell seating part 201 from the lower side of the chamber 210; and a sensing unit 240 connected to the vent unit 230 and including an in-situ gas pressure sensor 241 . Referring to Figures 2 and 3, the chamber is composed of an upper and lower portion, and the lower portion of the chamber has a shape in which a space is recessed inward to accommodate the monocell, and the upper portion is plate-shaped. Unlike this, both the upper and lower parts may have a recessed shape.

The electrolyte swelling property evaluation device 200 may be connected to a vacuum pump outside the device. Using the vacuum pump, it is possible to create a vacuum environment in the mono-cell mounting portion 201 by removing the air inside the chamber 210. The vacuum pump can be controlled in various ways, and preferably, it can be controlled using the on-off valve 232 by connecting it through the on-off valve 232 of the vent unit 230 .

First, as shown in FIGS. 5 and 6, the monocell mounting portion 201 of the present invention serves to accommodate the monocell 1 into which the electrolyte to be evaluated is injected. The planar shape and size of the monocell mounting portion 201 is not limited, but is shown as an example of a rectangle on a plane. The monocell seating portion 201 provides a space in which the monocell 1 injected with the electrolyte to be evaluated is seated. At this time, the mono-cell mounting portion 201 is sufficient if it is large enough to accommodate the mono-cell (1). The monocell 1 is manufactured by stacking one anode, one separator, and one cathode, injecting an electrolyte solution to be evaluated, and sealing it.

In addition, as shown in FIGS. 2 and 3 , the monocell mounting portion 201 is sealed and separated from the external environment by a chamber 210 to be described later. The gas generated inside the monocell 1 is diffused into the sealed monocell mounting portion.

As shown in FIGS. 2 and 3 , the chamber 210 of the present invention may be composed of an upper part 211 and a lower part 212 that can be disassembled and assembled with each other. The material of the lower chamber 212 is not particularly limited as long as it is an insulator that is not electrically conductive as used in the industry, but is preferably selected from the group consisting of PTFE (Polytetrafluoroethylene) resin, PEEK (Polyetheretherketone) resin, Teflon resin, and the like can be made of either one. The lower part 212 and the upper part 211 of the chamber are connected to each other, and through this, the inside of the chamber 210 can be completely sealed. At this time, the lower part 212 and the upper part 211 may be mechanically coupled by an O-ring, and may be completely hermetically coupled to form a vacuum environment. The material of the O-ring is not particularly limited, but may be preferably made of an elastomer such as viton or a Teflon coating.

2, 3 and 7, the punching portion 220 of the present invention may be disposed above the chamber 210, the monocell 1 seated on the monocell seating portion 201 It can be placed above the punching position of. As shown in FIG. 4, the position of the perforation 2 created in the monocell 1 by the punching unit is the free space between the battery case and the electrode assembly, between the positive electrode tab and the negative electrode tab. It can be the central part. In perforating the battery case of the monocell, it will of course be necessary to adjust the position of the perforation so as not to damage the electrode assembly.

In addition, as shown in FIG. 7, the punching unit 210 may include a punch 221, a punch head 222 formed above the punch, and a spring 223 positioned around the punch. By applying pressure to the punch head 222 of the punch unit 210, punching is performed on the monocell 1 seated on the monocell seating portion 201 by the punch 221, and the spring 223 serves to return the punch head 222 to a state before pressure is applied after punching.

In addition, as shown in FIG. 4 , through the punching of the punching unit 220 , a hole 2 is formed in the monocell 1 . Gas generated inside the monocell 1 diffuses into the monocell mounting portion 201 through the perforation 2 .

Also, the punching part 220 may be disposed to be sealed with the chamber 210 . As shown in FIG. 7, since the punch 221 of the punching part 220 penetrates the upper part 211 of the chamber, the punching part 220 is not disposed in the chamber 210 in a closed manner. Otherwise, air is introduced into the space between the chamber 210 and the punching part 220, so that a vacuum environment cannot be created or maintained inside the chamber 220. In addition, when the punching part 220 is not disposed in the chamber 210 in a sealed manner, the gas generated inside the monocell 1 seated on the monocell seating part 201 passes through the chamber 210 and the chamber 210. It is diffused to the outside through the space between the punching parts 220, making accurate measurement impossible. Even if the punch 221 of the punching part 220 moves up and down for punching, airtightness between the punching part 220 and the chamber 210 is maintained. Since the punching part 220 is sealed and disposed above the chamber 210, the vacuum environment of the monocell mounting part 210 is maintained, and the gas generated inside the monocell 1 passes through the punching part 220 and through the coupling part of the chamber 210 to prevent outflow.

As shown in FIGS. 2 , 3 and 5 , the vent part 230 may include the vent hole 231 and the opening/closing valve 232 . The vent hole 232 may communicate with the monocell mounting portion 201 from the lower side of the chamber 210 . The gas generated inside the monocell 1 is diffused into the monocell mounting portion, and then diffused into the vent portion 230 through the vent hole 231 . The opening/closing valve 232 is connected to a vacuum pump to adjust the vacuum environment inside the chamber 210 .

As shown in FIGS. 2 , 3 and 5 , the sensing unit 240 may be connected to the vent unit 230 . The sensing unit 240 is connected between the vent hole 231 of the vent unit 230 and the opening/closing valve 232, so that the gas generated inside the monocell 1 is transferred to the monocell mounting unit 201. ), the vent hole 231 and the in-situ gas pressure sensor 241 of the sensing unit 240 measure the pressure of the gas generated inside the monocell 1 as it diffuses in that order.

The electrolyte swelling characteristic evaluation apparatus 200 of the present invention sets the internal temperature of the chamber 210 to 10 ° C to 100 ° C, preferably 15 ° C to 90 ° C, more preferably 20 ° C to 80 ° C, in the range An adjustable thermostat may be included. By applying heat to the chamber 210 with the temperature controller, heat is transferred to the monocell 1 seated on the monocell mounting portion 201 . As the monocell 1 is exposed to a high-temperature environment, the overheated monocell 1 generates gas inside, and the generated gas is seated in the monocell through the perforation 2 created by the punching part 220 Diffuses to section 201.

The gas pressure measurement range of the pressure sensor 241 of the sensing unit 240 of the present invention may be -10 to 20 bar, preferably -5 to 15 bar, more preferably -1 to 10 bar.

The swelling characteristic evaluation apparatus of the electrolyte solution of the present invention may further include a control unit that calculates a pressure change and gas generation amount according to signals from signals received from the pressure sensor 241 . The control unit can effectively measure the swelling characteristics of the electrolyte solution by visualizing the calculation details of pressure change and gas generation amount.

Hereinafter, with reference to FIG. 9, a method for evaluating swelling characteristics of an electrolyte using the evaluation apparatus 200 of the present invention will be described.

As shown in FIG. 9, the electrolyte swelling property evaluation method according to the present invention includes a monocell manufacturing step (S10) of manufacturing a monocell including one anode, one separator and one cathode; An electrolyte injection step of injecting an electrolyte to be evaluated into the monocell (S20); A monocell preparation step (S30) of aging, forming, and degassing the monocell injected with the electrolyte at room temperature; A mono-cell full filling step (S40) of fully filling the mono-cell; A monocell seating step (S50) of seating the monocell on the monocell seating portion of the device, sealingly coupling the chamber of the device, and creating a vacuum environment inside the chamber; A mono-cell punching step (S60) to perforate the movement of gas generated inside the mono-cell; And a gas pressure measurement step (S70) of heating, storing at a high temperature, and lowering the temperature of the monocell, and in-situ measuring the gas generated inside the monocell in each process with a pressure sensor.

First, the monocell 1 manufacturing step (S10) is a step of preparing a monocell 1 in which one anode, one separator, and one cathode are stacked. Since such a monocell has a small number of layers of the positive electrode, the separator, and the negative electrode, and can be manufactured by simply manually stacking the monocell, it can be manufactured in a simpler method than the prior art. Accordingly, while the conventional small cell to be evaluated for swelling characteristics requires about one month, the mono cell 1 can be shortened to one day. Accordingly, since the preparation of the monocell 1 is easier than in the prior art, it is possible to evaluate the swelling characteristics of various lithium secondary battery electrolytes by reducing the burden on the manufacturing period.

Next, the electrolyte injection step (S20) of the present invention is a step of injecting an electrolyte solution to be evaluated into the monocell 1 prepared in the monocell manufacturing step (S10). The electrolyte solution includes an organic solvent and a lithium salt mixed with the organic solvent.

The organic solvent is ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) ), Fluoroethylene carbonate (FEC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Methyl Ethyl Carbonate (MEC), Butylene Carbonate (BC), Ethyl Acetate, Methyl Acetate, Propyl Acetate, Ethyl Propionate (EP), Methyl Propionate, Propyl Propionate (PP) , It may be any one selected from the group consisting of vinylene carbonate (Vinylene Varbonate, VC) and mixtures thereof.

The lithium salt is LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN(SO ₂ CF ₃ ) ₂ , LiN(SO ₂ C ₂ F ₅ ) ₂ , LiC(SO ₂ CF ₃ ) ₃ , LiN(SO ₃ CF ₃ ) ₂ , LiC ₄ F ₉ SO ₃ , LiAlO ₄ , LiAlCl ₄ , LiCl and LiI.

Then, the electrolyte solution is injected into the monocell 1 of the present invention and the monocell 1 is sealed. At this time, the electrolyte solution is injected in a range of 500 μl or less, preferably 450 μl or less, and more preferably 400 μl or less.

Next, the monocell preparation step 30 of the present invention may include aging, formation, and degassing of the monocell 1 injected with the electrolyte at room temperature. . Each process of the monocell preparation step 30 uses a method used in the art, and there is no particular limitation, but preferably, the monocell 1 is first aged at room temperature for one day, and at room temperature After the formation process, the second aging is carried out at room temperature for one day. The formation process is not particularly limited as using a method used in the art, but may preferably be made to a state of charge (SOC) 16.6 level.

Then, in the monocell full charging step (S40) of the present invention, there is no particular limitation as using the full charging range used in the art, but the monocell is (1) 3V to 5V, preferably 4V to 4.5V. range can be filled.

Then, in the monocell seating step (S50) of the present invention, the monocell 1 is seated on the monocell seating portion 201 inside the chamber 210, and the upper portion 211 of the chamber 210 are completely sealed and combined. A vacuum environment is created inside the chamber 210 by opening the opening/closing valve 232 of the vent part 230 communicating with the inner monocell seating part 201 and operating the vacuum pump. When a vacuum environment is created, the opening/closing valve 232 may be closed to maintain the vacuum environment.

By maintaining the vacuum environment, the gas generated inside the monocell 1 can be diffused into the monocell mounting portion 201 through the perforation 2 created in the monocell punching step described later, and the monocell The gas diffused in the seating part 201 may move to the pressure sensor 241 of the sensor part 240 through the vent part 230 .

Then, in the mono-cell punching step (S60) of the present invention, through the punching of the punching unit 220, to create a hole (2) in the mono-cell. The perforation 2 of the mono cell 1 allows the gas generated inside the mono cell 1 to move to the outside of the mono cell 1. Gas generated inside the monocell 1 diffuses into the monocell mounting portion 201 through the perforation 2 .

At this time, before the gas pressure measuring step (S70) to be described later, the monocell 1 is 0 ° C to 30 ° C, preferably 10 ° C to 28 ° C, more preferably 22 ° C in the mono cell seating part 201 to 27° C. for 1 hour or longer.

Then, the gas pressure measuring step (S70) of the present invention includes a monocell temperature raising step (S71) of heating the monocell to generate gas in the monocell; A mono-cell storage step (S72) of storing in a high-temperature environment reached through the temperature-raising step; And a monocell heating step (S73) of cooling the monocell of the monocell storage step, and the gas generated in each step is measured in-situ with the pressure sensor 241.

The mono-cell temperature raising step (S71) provides a situation similar to an overheating situation in using a secondary battery so that gas generated inside the mono-cell can be measured in the process of overheating the electrolyte to be evaluated.

In addition, in the mono-cell temperature raising step (S71), the mono-cell may be heated in the range of 50 ° C to 100 ° C, preferably 60 ° C to 90 ° C, more preferably 65 ° C to 75 ° C, and the mono-cell The heating time may be 30 minutes or more, preferably 45 minutes or more, and more preferably 1 hour.

The monocell storage step (S72) provides a situation similar to a situation in which the overheated secondary battery is maintained at a high temperature, so that gas generated inside the monocell can be measured while the electrolyte to be evaluated is maintained at a high temperature.

In addition, in the monocell storage step (S72), the monocell is stored at a high temperature in the range of 50 ° C to 100 ° C, preferably 60 ° C to 90 ° C, more preferably 65 ° C to 75 ° C, and the mono cell is stored at a high temperature The storage time may be 12 hours to 48 hours, preferably 18 hours to 36 hours, and more preferably 20 hours to 28 hours.

In addition, in the monocell heating step (S73), the monocell of the monocell storage step can be cooled to a range of 0 ° C to 30 ° C, preferably 10 ° C to 29 ° C, more preferably 15 ° C to 27 ° C, , The time for heating the monocell may be 30 minutes or more, preferably 45 minutes or more, and more preferably 1 hour.

The step of lowering the temperature of the monocell (S73) makes it possible to measure the change in the gas generated inside the monocell while being cooled to room temperature in a high temperature environment.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited by the following examples.

Example 1 to 6

<Manufacture of monocell>

A LiCoO ₂ cathode active material was prepared. Then, a slurry was prepared by mixing cathode active material: carbon for conductive material: polyvinylidene fluorite (PVDF) as a binder in a weight ratio of 96: 2: 2, and then coated on an aluminum (Al) foil current collector in a conventional manner, , and dried to prepare a positive electrode.

An anode active material slurry was prepared by mixing artificial graphite:SBR-based binder:carboxymethyl cellulose as a thickener at a weight ratio of 98:1:1, and then coated on a copper (Cu) foil current collector in a conventional manner to prepare a negative electrode. .

A monocell was prepared by inserting the stacked electrode assembly made by interposing a polyethylene porous membrane between the prepared positive electrode and the negative electrode into a pouch-type battery case, and injecting an electrolyte solution to be evaluated according to the composition of Table 1 below.

An electrolyte solution was prepared by mixing organic solvents according to the weight ratios shown in Table 1 below and adding lithium hexafluorophosphate (LiPF6) 1M as a lithium salt thereto. 400 μl of the electrolyte was injected into the monocell and sealed.

lithium salt organic solvent weight ratio Example 1 (EC) LiPF ₆ 1M EC 7 EMC 3 Example 2 (FEC) LiPF ₆ 1M EC 2 EMC 3 FEC 5 Example 3 (VC) LiPF ₆ 1M EC 2 EMC 3 VC 5 Example 4 (DEC) LiPF ₆ 1M EC 2 EMC 3 DEC 5 Example 5 (PP) LiPF ₆ 1M EC 2 EMC 3 PP 5 Example 6 (EP) LiPF ₆ 1M EC 2 EMC 3 EP 5

<Preparation of monocell and full filling of monocell>

The monocell into which the electrolyte was injected was subjected to primary aging at room temperature for one day. Thereafter, a formation process was performed on the monocell into which the electrolyte solution was injected at room temperature to a state of charge (SOC) of 16.6. After the formation process was completed, the monocell was subjected to secondary aging at room temperature for one day, degassed, and then fully charged to 4.45V.

<Mono cell mounting and punching>

The fully-filled monocell was seated on the monocell seating part located inside the chamber of the electrolyte swelling characteristic evaluation apparatus shown in FIG. 2, and the upper part of the chamber was completely sealed and coupled. After opening the opening/closing valve of the device vent part communicating with the inner monocell seating part and operating the vacuum pump to create a vacuum environment inside the chamber, the opening/closing valve was closed to maintain the vacuum environment.

After the vacuum environment was created, a sealing portion of the monocell was punched in the middle between the positive electrode tab and the negative electrode tab on the upper portion of the monocell by applying pressure to the punch head of the punching unit to create a hole.

<Stabilization and gas pressure measurement>

The perforated monocell was stabilized at 25 °C for 1 hour.

In order to measure the internally generated gas in the high-temperature environment of the monocell, the monocell was heated to 70 ° C for 1 hour, and the monocell was stored for 24 hours while maintaining the 70 ° C environment reached at this time. Then, the monocell was warmed to 25° C. for 1 hour. While heating, storing, and warming the monocell, the gas generated inside the monocell was measured with a pressure sensor capable of in-situ measurement and having a measurement range of -1 to 10 bar.

8 is a graph showing the test results of the electrolyte solution injected into the monocell according to each embodiment.

The dotted line represents the temperature change with time. Lines shown as solid lines represent pressure changes due to gas generated inside the monocell according to time changes. The lines shown as solid lines are Example 1 (EC), Example 3 (VC), Example 2 (FEC), Example 6 (EP), Example 4 (DEC), and Example 5 (PP) in order from the top. ) was shown.

Referring to FIG. 8, among the electrolytes to be evaluated, an electrolyte containing a large amount of EC and VC corresponding to cyclic carbonates that have a large gas generation reaction at a high temperature and cause swelling of a secondary battery It was confirmed that the generation of gas was large.

As described above, the electrolyte swelling characteristic evaluation device and the evaluation method using the device according to an embodiment of the present invention is a method for measuring the amount of internal gas generation, which is the cause of the swelling phenomenon on the side of the electrolyte in the battery cell development stage. It is simplified into units, and the amount of gas generated is measured in real time so that the swelling characteristics of the electrolyte can be effectively evaluated.

Those skilled in the art in the field to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above information.

Claims (16)

As a method of evaluating the swelling characteristics of the electrolyte by the swelling characteristics evaluation device of the electrolyte,
A monocell manufacturing step (S10) of manufacturing a monocell including one anode, one separator and one cathode;
An electrolyte injection step of injecting an electrolyte to be evaluated into the monocell (S20);
A monocell preparation step (S30) of aging, forming, and degassing the monocell injected with the electrolyte at room temperature;
A mono-cell full filling step (S40) of fully filling the mono-cell;
A monocell seating step (S50) of seating the monocell on the monocell seating portion of the device, sealingly coupling the chamber of the device, and creating a vacuum environment inside the chamber;
A mono-cell punching step (S60) to perforate the movement of gas generated inside the mono-cell; and
A gas pressure measuring step (S70) of heating, storing at a high temperature, and warming the monocell, and in-situ measuring the gas generated inside the monocell in each process with a pressure sensor,
The swelling property evaluation device of the electrolyte solution,
A chamber having a monocell mounting portion formed therein;
a punching unit disposed on the chamber and punching the monocell seated in the chamber;
a vent portion including a vent hole communicating with the monocell mounting portion from the lower side of the chamber; and
The swelling characteristic evaluation method of the electrolyte, characterized in that it comprises a sensing unit connected to the vent unit and including a real-time (in-situ) gas pressure sensor.
According to claim 1,
In the electrolyte injection step (S20), the swelling property evaluation method of the electrolyte, characterized in that the electrolyte solution is injected into the monocell in a range of 500 μl or less.
According to claim 1,
The swelling property evaluation method of the electrolyte, characterized in that it further comprises the step of stabilizing the monocell at 0 ℃ to 30 ℃ for 1 hour or more before the gas pressure measuring step (S70).
According to claim 1,
The gas pressure measuring step (S70) includes a monocell temperature raising step (S71) of heating the monocell to generate gas in the monocell; A mono-cell storage step (S72) of storing in a high-temperature environment reached through the temperature-raising step; and a monocell heating step (S73) of cooling the monocell of the monocell storage step.
According to claim 4,
In the monocell temperature raising step (S71), the swelling property evaluation method of the electrolyte, characterized in that for heating the monocell in the range of 50 ℃ to 100 ℃ for 30 minutes or more.
According to claim 4,
In the monocell storage step (S72), the swelling property evaluation method of the electrolyte, characterized in that for storing the monocell in the range of 50 ℃ to 100 ℃ 12 hours to 48 hours.
According to claim 4,
In the monocell warming step (S73), the swelling property evaluation method of the electrolyte, characterized in that for cooling the monocell in the range of 0 ℃ to 30 ℃ for 30 minutes or more.
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