KR20190134179A - Evaluation Method and Apparatus for Swelling Characteristics of Electrolyte - Google Patents

Abstract

The present invention relates to an apparatus and a method for effectively evaluating swelling characteristics of an electrolyte by simplifying a method for measuring the generation amount of internal gas which causes a swelling phenomenon as an electrolyte side of a battery cell development step into a mono cell unit, and measuring the generation amount of gas in real time. According to the present invention, the apparatus for evaluating swelling characteristics of an electrolyte comprises: a chamber in which a mono cell mounting unit is formed therein; a punching unit disposed on the chamber to punch mono cells mounted in the chamber; a vent unit including a vent hole connected to the mono cell mounting unit from a lower side of the chamber; and a sensing unit connected to the vent unit and including an in-situ gas pressure sensor.

Description

Evaluation and Apparatus for Swelling Characteristics of Electrolyte

The present invention relates to an swelling characteristic evaluation apparatus and an evaluation method 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 of wireless mobile devices. In addition, secondary batteries are attracting attention as energy sources such as electric vehicles and hybrid electric vehicles, which are proposed as a way to solve air pollution of conventional gasoline and diesel vehicles using fossil fuel. Therefore, the type of applications using the secondary battery is very diversified due to the advantages of the secondary battery, and it is expected that the secondary battery will be applied to many fields and products in the future.

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

In general, while the secondary battery is operated in an abnormal state due to overcharge, overdischarge, overheat, external shock, etc., gas may be generated inside. For example, an overheated cell generates gas, and the pressurized gas in the case further accelerates the decomposition reaction of the cell element, causing continuous overheating and gas generation, and swelling may occur. This phenomenon occurs even when the secondary battery gradually deteriorates due to prolonged use. Therefore, a screening evaluation method for a new material for improving swelling in terms of electrolytes is needed in the material development stage, which is a stage before product development.

In general, a secondary battery swelling test uses a small cell formed by forming an electrode assembly with a positive electrode, a negative electrode, and a separator, then storing the electrode assembly in a pouch and injecting an electrolyte solution. The small cell is exposed to a high temperature environment to evaluate the degree of gas generation. FIG. 1 is a diagram illustrating a thickness meter 100 for measuring an amount of change in thickness of a small cell during the swelling test. As shown in FIG. 1, the thickness measuring device 100 includes a seating portion 111 on which the small cell 101 is mounted and a measuring device 112 for measuring the thickness of the small cell 101. It is provided at the top, and comprises a weight 113 for applying a constant pressure to the small cell 101 seated on the seating portion (111).

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

This takes a long time to swell test all candidate groups of the electrolyte, so a method that can simply check the performance in a short period of time is required.

The present invention aims to solve the problems of the prior art as described above 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 to simplify the method of measuring the internal gas generation amount, which is the cause of the swelling phenomenon in the side of the electrolyte at the stage of battery cell development, in monocell units, It is to provide an apparatus and method for effectively evaluating the swelling characteristics of the electrolyte by measuring in real time.

Swelling characteristic evaluation apparatus of the electrolyte solution according to the present invention for achieving this object comprises a chamber in which a monocell seating portion is formed; A punching unit disposed on the chamber to punch the monocell seated in the chamber; A vent part including a vent hole communicating with the monocell seating part from a 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, the vacuum pump is connected to the outside of the swelling characteristic evaluation apparatus of the electrolyte.

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

In the present invention, the chamber is characterized in that the lower part and the upper part is completely sealed by the O-ring.

In the present invention, the punching portion is characterized in that it comprises a punch, a punch head formed on the punch upper portion, and a spring located around the punch.

In the present invention, the punching portion is characterized in that it is arranged closed with the chamber.

In the present invention is characterized in that it comprises a temperature control device that can adjust 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 characteristic evaluation device 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.

The swelling characteristic evaluation method of the electrolyte according to the present invention for achieving this object is a method for evaluating the swelling characteristic of the electrolyte by the swelling characteristic evaluation device of the electrolyte, one anode, one separator and Monocell manufacturing step (S10) for producing a monocell comprising one cathode; An electrolyte injection step (S20) of injecting an electrolyte to be evaluated into the monocell; Monocell preparation step (S30) of aging, forming and degassing the monocell into which the electrolyte is injected at room temperature;

A monocell full filling step (S40) for filling the monocell; A monocell seating step (S50) of seating the monocell on the monocell seating unit of the device and sealingly coupling the chamber of the device to create a vacuum environment inside the chamber; Punching monocell punching step (S60) for the movement of the gas generated in the monocell; And a gas pressure measuring step (S70) of heating, hot storing and lowering the monocell, and measuring in-situ the gas generated in the monocell in each process by a pressure sensor. .

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

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

In the present invention, the monocell heating step of heating the monocell to generate a gas inside the monocell (S71); A monocell storage step (S72) for storing in a high temperature environment reached through the temperature raising step; And a monocell lowering step (S73) for cooling the monocell in the monocell storage step.

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

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

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

The swelling characteristic evaluation apparatus and evaluation method of the electrolyte according to the present invention uses a monocell that can be easily manufactured by using one sheet of anode / cathode / separation membrane in order to use an environment similar to an actual battery, and the evaluation method is simplified in a short time. Therefore, there is an effect that can quickly screen the swelling characteristics at high temperatures of the new materials for the development of the electrolyte solution in a small amount.

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

1 is a schematic diagram showing a state of measuring the thickness of a small cell using a conventional thickness meter;
2 is a perspective view showing an electrolyte swelling characteristic evaluation apparatus according to an 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;
4 is a plan view showing a position where perforations are generated with a monocell and a punch portion used in the present invention;
5 is a side view illustrating the lower chamber, the vent part, and the sensing part of FIGS. 2 and 3;
FIG. 6 is a plan view illustrating the lower chamber, the vent part, and the sensing part of FIGS. 2 and 3;
FIG. 7 is a side view of the upper chamber, punching portion of FIGS. 2 and 3;
8 is a graph showing test results of monocells injected with evaluation electrolytes according to an embodiment of the present invention;
9 is a flowchart showing the procedure of the electrolyte swelling characteristic evaluation method of the present invention.

Hereinafter, although described with reference to the drawings according to an embodiment of the present invention, this is for easier understanding of the present invention, 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 the other component may be directly connected to or in between.

2 and 3, the electrolyte swelling characteristic evaluation apparatus 200 according to the present invention includes a chamber 210 in which a monocell seating unit 201 is formed therein; A punching unit 220 disposed on the chamber 210 to punch the monocell seated in the chamber 210; A vent part 230 including a vent hole 231 communicating with the monocell seating part 201 from a lower side surface of the chamber 210; And a sensing unit 240 connected to the vent unit 230 and including an in-situ gas pressure sensor 241. 2 and 3, the chamber is composed of an upper portion and a lower portion, and the lower portion of the chamber is in a shape in which a space is indented to accommodate a monocell, and the upper portion is plate-shaped. Alternatively, both top and bottom may have a shape indented therein.

The electrolyte swelling characteristic evaluation apparatus 200 may be connected to a vacuum pump outside the device. By using the vacuum pump, the internal air of the chamber 210 may be removed to create a vacuum environment in the monocell seating unit 201. The vacuum pump may be controlled in a variety of ways, and may be controlled using the on / off valve 232 by connecting through the on / off valve 232 of the vent part 230.

First, as shown in FIGS. 5 and 6, the monocell seating portion 201 of the present invention serves to accommodate the monocell 1 into which the electrolyte solution to be evaluated is injected. Although the planar shape and size of the monocell seating portion 201 are not limited, it is illustrated as an example of a quadrangle on the plane. The monocell seating unit 201 provides a space in which the monocell 1 into which the electrolyte to be evaluated is injected is seated. At this time, the monocell seating portion 201 is sufficient size to accommodate the monocell (1). The monocell 1 is manufactured by stacking one positive electrode, one separator, and one negative electrode, injecting and sealing an electrolyte to be evaluated.

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

As shown in Figures 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 mutually disassembled. The material of the lower chamber 212 is used in the art and is not particularly limited as long as it is an insulator having no electrical conductivity, but is preferably selected from the group consisting of PTFE (Polytetrafluoroethylene) resin, PEEK (Polyetheretherketon) resin, and Teflon resin It can be made of either. The lower part 212 and the upper part 211 of the chamber are connected to each other and connected to each other, thereby completely sealing the inside of the chamber 210. In this case, 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 Teflon coating.

2, 3 and 7, the punching part 220 of the present invention may be disposed on the chamber 210 and the monocell 1 seated on the monocell seating part 201. It can be placed above the punching position of. As shown in FIG. 4, the position of the perforations 2 generated in the monocell 1 by the punching portion is a free space between the battery case and the electrode assembly, between the positive electrode tab and the negative electrode tab. It can be the centerpiece. In drilling the battery case of the monocell, of course, the position of the puncture should be adjusted so that the electrode assembly is not damaged.

In addition, as illustrated in FIG. 7, the punching part 210 may include a punch 221, a punch head 222 formed on the punch, and a spring 223 positioned around the punch. By applying pressure to the punch head 222 of the punch unit 210, the punch 221 is punched into the monocell 1 seated on the monocell seat 201, 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 part 220, a perforation 2 is generated in the monocell 1. The gas generated in the monocell 1 diffuses through the perforation 2 to the monocell seating portion 201.

In addition, the punching part 220 may be disposed to be closed 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. If not, air is introduced into the space between the chamber 210 and the punching part 220 to create a vacuum environment or maintain the vacuum environment inside the chamber 220. In addition, when the punching unit 220 is not disposed to be closed in the chamber 210, gas generated inside the monocell 1 seated on the monocell seating unit 201 is discharged from the chamber 210 and the chamber. It is diffused to the outside through the space between the punching unit 220 is impossible to accurately measure. Even when the punch 221 of the punching part 220 moves up and down for punching, the sealing property of the punching part 220 and the chamber 210 is maintained. Since the punching unit 220 is disposed to be closed on the chamber 210, the monocell seating unit 210 maintains a vacuum environment, and the gas generated in the monocell 1 is generated in the punching unit 220. And prevents leakage through the coupling portion of the chamber 210.

As shown in FIGS. 2, 3, and 5, the vent part 230 may include the vent hole 231 and the open / close valve 232. The vent hole 232 may communicate with the monocell seat 201 from a lower side surface of the chamber 210. The gas generated inside the monocell 1 diffuses into the monocell seating part, and then diffuses into the vent part 230 through the vent hole 231. The open / close valve 232 may be connected to a vacuum pump to adjust a vacuum environment inside the chamber 210.

As illustrated 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 open / close valve 232, so that the gas generated in the monocell 1 is in the monocell seating unit 201. ), The pressure of the gas generated inside the monocell 1 is measured as the vent hole 231 and the in-situ gas pressure sensor 241 of the sensing unit 240 are diffused in the order.

The electrolyte swelling characteristic evaluation apparatus 200 of the present invention has an internal temperature of the chamber 210 in a range of 10 ° C to 100 ° C, preferably 15 ° C to 90 ° C, more preferably 20 ° C to 80 ° C. It may include an adjustable thermostat. Heat is transferred to the monocell 1 seated on the monocell seating unit 201 by applying heat to the chamber 210 with the temperature controller. As the monocell 1 is exposed to a high temperature environment, the superheated monocell 1 generates a gas therein, and the generated gas is seated through the perforations 2 generated by the punching unit 220. It spreads to the part 201.

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 of the present invention may further include a controller for calculating a pressure change and gas generation amount according to the signal from the signals received from the pressure sensor 241. The controller may effectively measure the swelling characteristic of the electrolyte by visualizing the calculation of the pressure change and the gas generation amount.

Hereinafter, a swelling characteristic evaluation method of the electrolyte solution using the evaluation apparatus 200 of the present invention will be described with reference to FIG. 9.

As shown in Figure 9, the electrolyte swelling (swelling) characteristic evaluation method according to the present invention is a monocell manufacturing step (S10) for producing a monocell comprising one anode, one separator and one cathode; An electrolyte injection step (S20) of injecting an electrolyte to be evaluated into the monocell; Monocell preparation step (S30) of aging, forming and degassing the monocell into which the electrolyte is injected at room temperature; A monocell full filling step (S40) for filling the monocell; A monocell seating step (S50) of seating the monocell on the monocell seating unit of the device and sealingly coupling the chamber of the device to create a vacuum environment inside the chamber; Punching monocell punching step (S60) for the movement of the gas generated in the monocell; And a gas pressure measuring step (S70) of heating, hot storing, and lowering the monocell, and measuring in-situ a gas generated in the monocell in each process by 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. Such a monocell has a small stacking number of the positive electrode, the separator, and the negative electrode, and can be easily manufactured by a worker by hand. Thus, the monocell can be manufactured by a simple method. Accordingly, the conventional small cell, which is the target of swelling characteristic evaluation, is required for about one month, while the monocell 1 can be shortened to one day. Accordingly, since the preparation of the monocell 1 is easier than in the related art, the swelling characteristics of various lithium secondary battery electrolytes can be evaluated by reducing the burden on the production period.

Then, the electrolyte injection step (S20) of the present invention is a step of injecting the electrolyte solution to be evaluated in 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 (Ethylene Carbonate, EC), propylene carbonate (Propylene Carbonate, PC), ethyl methyl carbonate (Ethyl Methyl Carbonate, EMC), dimethyl carbonate (Dimethyl Carbonate, DMC), diethyl carbonate (Diethyl Carbonate, DEC) ), Fluoroethylene carbonate (FEC), methyl propyl carbonate (MPC), ethyl propyl carbonate (Ethyl Propyl Carbonate, EPC), methyl ethyl carbonate (MEC), butylene carbonate (BC), ethyl Acetyl 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 at least one selected from the group consisting of.

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

Then, the monocell preparation step 30 of the present invention may include a process of aging, forming and degassing the monocell 1 into which the electrolyte is injected at room temperature. . Each process of the monocell preparatory step (30) is a method used in the art, there is no particular limitation, but preferably the monocell (1) is the first aging for 1 day at room temperature, and at room temperature After the formation process, the second ripening for one day at room temperature again. The formation process uses a method used in the art, but there is no particular limitation, but the formation process may be preferably performed at a level of state of charge (SOC) of 16.6.

Next, in the monocell full filling step (S40) of the present invention, there is no particular limitation as to the full range used in the art, but the monocell may be (1) 3V to 5V, preferably 4V to 4.5V. It can be filled with a range.

Next, 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. Combine in a completely hermetic seal. The on / off valve 232 of the vent part 230 connected to the inner monocell seating part 201 is opened and the vacuum pump is operated to create a vacuum environment in the chamber 210. When the vacuum environment is established, the on / off valve 232 may be closed to maintain the vacuum environment.

By maintaining the vacuum environment, the gas generated in the monocell 1 can be diffused into the monocell seating unit 201 through the perforations 2 generated in the monocell punching step, which will be described later. 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.

Next, in the monocell punching step (S60) of the present invention, through the punching of the punching unit 220, a perforation 2 is generated in the monocell. The perforation 2 of the monocell 1 allows the gas generated inside the monocell 1 to move out of the monocell 1. The gas generated in the monocell 1 diffuses through the perforation 2 to the monocell seating portion 201.

At this time, before the gas pressure measuring step (S70) to be described later, the monocell (1) in the monocell seating portion 201 0 ℃ to 30 ℃, preferably 10 ℃ to 28 ℃, more preferably 22 ℃ It may further comprise the step of stabilizing at least 27 hours at 27 ℃.

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

The monocell heating step S71 provides a situation similar to that of overheating in the use of a secondary battery so that the gas generated in the monocell in the process of overheating the electrolyte to be evaluated may be measured.

In addition, in the monocell heating step (S71), the monocell may be heated to a range of 50 ° C to 100 ° C, preferably 60 ° C to 90 ° C, more preferably 65 ° C to 75 ° C, and the monocell The heating time may be at least 30 minutes, preferably at least 45 minutes, 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 the gas generated inside the monocell can be measured while the electrolyte to be evaluated is maintained at a high temperature.

In addition, the monocell storage step (S72) stores the monocell 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 monocell at high temperature. The time to store may be 12 hours to 48 hours, preferably 18 hours to 36 hours, more preferably 20 hours to 28 hours.

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

The monocell lower temperature step (S73) allows to measure the change in gas generated inside the monocell while cooling to room temperature in a high temperature environment.

Hereinafter, the present invention will be described in detail with reference to the following Examples. However, the following Examples are only for illustrating the present invention, and the present invention is not limited by the following Examples.

Example  1 to 6

Monocell manufacturing

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

Artificial graphite: SBR binder: Carboxymethyl cellulose as a thickener was mixed in a weight ratio of 98: 1: 1 to prepare a negative electrode active material slurry, and then coated on a copper (Cu) foil current collector in a conventional manner, to prepare a negative electrode. .

A stack-type electrode assembly prepared by interposing a polyethylene porous membrane between the prepared positive electrode and the negative electrode was introduced into a pouch-type battery case, and an electrolyte to be evaluated according to the composition of Table 1 was injected to prepare a monocell.

The organic solvent was mixed according to the weight ratio shown in Table 1 below, and lithium hexafluorophosphate (LiPF6) 1M was added thereto as a lithium salt to prepare an electrolyte solution. 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 cell monocell>

The monocell injected with the electrolyte was subjected to primary aging for 1 day at room temperature. Subsequently, the monocell into which the electrolyte was injected was formed at a room temperature at a state of charge (SOC) of 16.6. The monocells having completed the formation process were again matured and degassed for one day at room temperature to 4.45V.

Monocell seating and punching

The full monocell was seated on a monocell seating unit 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 combined. After opening and closing the opening and closing valve of the apparatus vane communicating with the inner monocell seating unit, the vacuum pump was operated to create a vacuum environment in the chamber, and the opening and closing valve was closed to maintain the vacuum environment.

After the vacuum environment was established, a punch was generated by punching the monocell sealing portion in the middle between the positive and negative electrode tabs on the monocell by applying pressure to the punch head of the punching portion.

Stabilization and Gas Pressure Measurement

The perforated monocells were stabilized for 25 to 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 environment of 70 ° C reached at this time. The monocell was then warmed to 25 ° C. for 1 hour. While heating, storing and lowering the monocell, gas generated inside the monocell was measured by a pressure sensor capable of in-situ measurement and a measuring 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 line shown by the dotted line represents the temperature change with time. The solid lines represent the change in pressure caused by the gas generated inside the monocell over time. The solid lines are shown in order from the top, in order of Example 1 (EC), Example 3 (VC), Example 2 (FEC), Example 6 (EP), Example 4 (DEC) and Example 5 (PP ).

Referring to FIG. 8, an electrolyte solution containing a large amount of EC and VC corresponding to cyclic carbonates, which actually causes a swelling phenomenon of a secondary battery due to a large gas generation reaction at high temperatures among the electrolytes to be evaluated. It was confirmed that gas generation was large.

As described above, the electrolyte swelling characteristics evaluation apparatus and the evaluation method using the apparatus according to an embodiment of the present invention is a method for measuring the internal gas generation amount that causes the swelling phenomenon in the electrolyte side in the battery cell development step monocell By simplifying units and measuring the amount of gas generated in real time, it is possible to effectively evaluate the swelling characteristics of the electrolyte.

Those skilled in the art 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 contents.

Claims (16)

An apparatus for evaluating swelling characteristics of a lithium secondary battery electrolyte, comprising: a chamber in which a monocell seating portion is formed;
A punching unit disposed on the chamber to punch the monocell seated in the chamber;
A vent part including a vent hole communicating with the monocell seating part from a lower side of the chamber; And
And a sensing unit connected to the vent unit and including an in-situ gas pressure sensor.
The method of claim 1,
Swelling characteristic evaluation apparatus of the electrolyte, characterized in that the vacuum pump is connected to the outside of the swelling characteristic evaluation apparatus of the electrolyte.
The method of claim 2,
The vacuum pump is the swelling characteristic evaluation device of the electrolyte, characterized in that connected via the opening and closing valve of the vent.
The method of claim 1,
The chamber is a swelling characteristic evaluation device of the electrolyte, characterized in that the lower part and the upper part is completely hermetically coupled by the O-ring.
The method of claim 1,
And said punching part comprises a punch, a punch head formed on the punch upper portion, and a spring positioned at the punch circumference.
The method of claim 5,
The punching unit is a swelling characteristic evaluation device of the electrolyte, characterized in that the chamber is disposed closed.
The method of claim 1,
Electrolyte swelling characteristic evaluation device comprising a temperature control device that can adjust the internal temperature of the chamber in the range of 10 ℃ to 100 ℃.
The method of claim 1,
The gas pressure measurement range of the sensing unit is -10 to 20 Bar swelling characteristic evaluation apparatus characterized in that the.
The method of claim 1,
Apparatus for evaluating the swelling characteristic of the electrolyte further comprises a control unit for calculating a pressure change and gas generation amount according to the signal from the signals received from the pressure sensor.
In the method for evaluating the swelling characteristics of the electrolyte by the swelling characteristic evaluation apparatus of the electrolyte according to claim 1,
Monocell manufacturing step (S10) for producing a monocell comprising one anode, one separator and one cathode;
An electrolyte injection step (S20) of injecting an electrolyte to be evaluated into the monocell;
Monocell preparation step (S30) of aging, forming and degassing the monocell into which the electrolyte is injected at room temperature;
A monocell full filling step (S40) for filling the monocell;
A monocell seating step (S50) for seating the monocell on the monocell seating unit of the device and sealingly coupling the chamber of the device to create a vacuum environment inside the chamber;
Punching monocell punching step (S60) for the movement of the gas generated in the monocell; And
An electrolytic solution comprising a gas pressure measuring step (S70) of heating, storing at high temperature and lowering the monocell, and measuring in-situ the gas generated in the monocell in each process by a pressure sensor. Swelling property evaluation method.
The method of claim 10,
In the electrolyte injection step (S20), the swelling characteristic evaluation method of the electrolyte solution, characterized in that to inject the electrolyte solution in the range of 500μl or less.
The method of claim 10,
The method of evaluating swelling characteristics of an electrolyte solution, further comprising stabilizing the monocell at 0 ° C. to 30 ° C. for at least 1 hour before the gas pressure measuring step (S70).
The method of claim 10,
The gas pressure measuring step (S70) includes a monocell heating step (S71) of heating the monocell to generate gas in the monocell; A monocell storage step (S72) for storing in a high temperature environment reached through the temperature raising step; And a monocell lowering step (S73) for cooling the monocell in the monocell storage step.
The method of claim 13,
In the monocell heating step (S71), the swelling characteristic evaluation method of the electrolyte solution, characterized in that for heating for 30 minutes or more in the range of 50 ℃ to 100 ℃.
The method of claim 13,
In the monocell storage step (S72), the swelling characteristic evaluation method of the electrolyte solution, characterized in that for storing the monocell 12 hours to 48 hours in the range of 50 ℃ to 100 ℃.
The method of claim 13,
In the monocell lower temperature step (S73), the swelling characteristic evaluation method of an electrolyte solution, characterized in that the monocell is cooled in the range of 0 ° C to 30 ° C for at least 30 minutes.

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