JP2012069320A - Lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery suitable for deterioration diagnosis without adding a reagent into the electrolyte in the battery.SOLUTION: A lithium ion secondary battery 1 includes: a positive electrode; a negative electrode; and electrolyte inside an exterior case 3. Outside the exterior case 3 is disposed a sealed reagent container 10 containing a reagent that undergoes coloration by selectively reacting with lithium ions in the electrolyte. The electrolyte in the exterior case 3 is configured to be introduced into the reagent container 10 via valves 13 as communication blockage means during deterioration diagnosis.

Description

  The present invention relates to a lithium ion secondary battery, and more particularly to a lithium ion secondary battery suitable for deterioration diagnosis.

  Conventionally, there is a lead storage battery including an electrolyte concentration sensor that detects a charge / discharge state of the battery (see Patent Document 1).

  This is characterized by including an optical fiber sensor that contains calcium ions in the electrolytic solution and detects the specific gravity of sulfuric acid through the calcium ions, and can measure the electrolytic solution concentration with a small size and high accuracy.

Japanese Patent Application Laid-Open No. 6-119942

  However, in the above conventional example, a reagent that reacts with the electrolyte solution is added to detect the state of the electrolyte solution. However, since the electrolyte solution and the reagent in the battery coexist, the side reaction caused by the reagent and the accompanying battery performance There was a problem of causing a drop.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a lithium ion secondary battery suitable for diagnosing deterioration without introducing a reagent into the electrolytic solution in the battery.

  The present invention is a lithium ion secondary battery in which a positive electrode, a negative electrode, and an electrolytic solution are incorporated in an outer case. And the reagent container which enclosed the reagent which selectively reacts with the lithium ion in electrolyte solution and colors is arrange | positioned out of an exterior case. Then, the electrolytic solution in the outer case can be introduced into the reagent container at the time of deterioration diagnosis through the communication blocking means.

  Therefore, in the present invention, since the electrolyte solution in the outer case is introduced into the reagent container via the communication blocking means at the time of deterioration diagnosis, the electrolyte solution remaining in the outer case and the color reagent do not react. . For this reason, the color reaction material reacts on the surface of the positive and negative active materials of the positive electrode layer and the negative electrode layer and adheres to and covers the surface to prevent battery performance deterioration due to side reactions such as inhibiting the function as the active material. Can do.

The schematic block diagram of the lithium ion secondary battery which shows one Embodiment of this invention. Sectional drawing of the lithium ion secondary battery which follows the AA line in FIG. Sectional drawing of a reagent container and a valve apparatus. Sectional drawing of a replenishment container and a valve apparatus. Explanatory drawing explaining operation | movement (A)-(D) of the reagent container at the time of deterioration diagnosis. The reaction diagram which shows the color reaction of the 1,10-phenanthroline derivative as a reagent. The figure explaining the chemical formula of the azophenol dye crown ether as a reagent. The figure explaining the chemical formula of the calixarene derivative as a reagent. The figure explaining the chemical formula of the ion-responsive dye as a reagent.

  Hereinafter, a lithium ion secondary battery of the present invention will be described based on an embodiment.

  1 and 2 are schematic views of the lithium ion secondary battery according to the present embodiment. FIG. 1 is a plan view of a lithium ion secondary battery, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  As shown in FIGS. 1 and 2, the lithium ion secondary battery 1 includes a battery element 2 and an outer case 3 that houses the battery element 2. In addition, the lithium ion secondary battery 1 of the present embodiment includes a plurality of reagent containers 10 enclosing a color reagent and a plurality of replenishing containers 11 enclosing an electrolyte solution. The containers 10 and 11 and the inside of the outer case 3 are normally provided with valve devices 12 and 13 as communication / blocking means that are normally in a cut-off state but can communicate with each other as necessary.

  The battery element 2 is configured as a laminate in which a positive electrode 4, a separator 5 as an electrolyte layer, and a negative electrode 6 are sequentially laminated.

  The positive electrode 4 has a positive electrode layer 4b on both sides of a plate-like positive electrode current collector 4a, and the negative electrode 6 has a negative electrode layer 6b on both sides of a plate-like negative electrode current collector 6a. In the positive electrode 4 disposed in the outermost layer of the battery element 2, the positive electrode layer 4b is formed only on one surface of the positive electrode current collector 4a.

  The adjacent positive electrode 4, separator 5, and negative electrode 6 constitute one unit cell 7, and the lithium ion battery 1 is configured by electrically connecting a plurality of stacked unit cells 7 in parallel.

  The outer case 3 is made of a sheet material of a polymer-metal composite laminate film in which a metal such as aluminum is covered with an insulator such as a polypropylene film. The outer case 3 is joined to the outer periphery of the case by thermal fusion in a state in which the battery element 2 is housed. The outer case 3 is provided with a positive electrode tab 8 and a negative electrode tab 9 as external terminals in order to extract the electric power from the battery element 2 to the outside.

  One end of the positive electrode tab 8 is on the outer side of the outer case 3, and the other end of the positive electrode tab 8 is connected to an assembly portion of each positive electrode current collector 4 a inside the outer case 3. One end of the negative electrode tab 9 is on the outer side of the outer case 3, and the other end of the negative electrode tab 9 is connected to the collecting portion of each negative electrode current collector 6 a inside the outer case 3.

  As shown in FIG. 3, the plurality of reagent containers 10 enclosing the color reagent are made of a transparent resin material containing the color reagent. One side of the reagent container 10 is connected with a valve device 12 as communication blocking means. The reagent container 10 containing the color reagent is formed of a cylindrical resin having elasticity that is open on the side opposite to the side connected to the valve device 12. The thickness dimension of the space in the reagent container 10 is set to be 2 mm, for example. Then, with the valve device 12 closed, a color reagent is inserted from the opening of the reagent container 10 and decompressed by a vacuum sealer using the opening, thereby elastically deforming along the outer shape of the color reagent ( The opening is sealed and formed. For this reason, the inside of the reagent container 10 is kept in a vacuum state.

  In the above description, a transparent resin material is described as the reagent container 10, but a translucent resin material may be used as long as the color reaction of the color reagent can be determined. .

  In the above description, the inside of the reagent container 10 is depressurized to a vacuum state. However, for example, if the pressure inside the outer case 3 is higher than the atmospheric pressure, the inside of the reagent container 10 is reduced to the atmospheric pressure state without depressurizing. You may do. That is, what is necessary is just to adjust the pressure in the reagent container 10 to be lower than the pressure in the outer case 3. In the following, for simplification of description, the case where the pressure in the reagent container 10 is reduced will be described.

  The edge of the outer case 3 of the lithium ion secondary battery 1 is fixed by fusion to the outer periphery of the valve device 12 opposite to the side to which the reagent container 10 is connected. The valve device 12 blocks the inside. For this reason, the inside of the exterior case 3 and the inside of the reagent container 10 communicate with each other by opening the valve device 12 and are elastically deformed in a state where the inside of the reagent container 10 is decompressed. For this reason, as the reagent container 10 is returned to the normal shape, the electrolytic solution in the outer case 3 is introduced into the reagent container 10.

  The valve device 12 may be any device as long as the inside of the reagent container 10 and the exterior case 3 are shut off and can communicate with each other as necessary. For example, the opening / closing cock, stop valve, stop valve, and reverse valve shown in FIG. A stop valve can be used.

  Examples of the color reagent incorporated in the reagent container 10 include a 1,10-phenanthroline derivative, an azophenol dye crown ether, a calixarene derivative, and an ion-responsive dye.

  As shown in FIG. 6, the 1,10-phenanthroline derivative is a compound having a derivative of 1,10-phenanthroline as a portion that selectively interacts with lithium ions and a picrylamino group as a chromophore. This compound changes its visible absorption spectrum only in the presence of lithium ions and changes from yellow to brown. That is, the lithium concentration can be measured by the color change.

  The azophenol dye crown ether has the structure shown in FIG. 7 and is a crown ether having an azo dye group, in which a phenolic hydroxyl group is oriented toward the vacancies of the crown ether ring. In the presence of an appropriate solvent and base, it forms a complex with alkali metal ions and alkaline earth metal ions, and exhibits a color and absorption spectrum peculiar to metal ions.

  The calixarene derivative has the structure shown in FIG. 8, has a coloration property longer than 600 nm in the presence of metal ions, particularly sodium ions, and is used as a highly selective and highly sensitive colorimetric reagent for these ions. Is done.

  The ion-responsive dye has the structure shown in FIG. 9 and can easily measure ions such as lithium ions in an aqueous solution with high sensitivity.

  As shown in FIG. 4, the plurality of replenishing containers 11 enclosing the electrolytic solution are formed of containers made of a resin material enclosing the electrolytic solution. One side of the replenishing container 11 is connected to a valve device 13 as communication blocking means. The amount of the electrolytic solution sealed in the replenishing container 11 is about 0.2 mL, for example, corresponding to the amount of the electrolytic solution used for the deterioration diagnosis introduced into the reagent container 10.

  The edge of the outer case 3 of the lithium ion secondary battery 1 is fixed to the outer periphery of the valve device 13 on the side opposite to the side to which the replenishing container 11 is connected. The inside is shut off by the valve device 13. For this reason, the exterior case 3 and the replenishment container 11 communicate with each other by opening the valve device 13, and the replenishment container 11 is deformed by picking, etc. The electrolyte solution can be replenished into the outer case 3 by extrusion. Thereafter, by closing the valve device 13, the inside of the outer case 3 and the inside of the replenishing container 11 can be shut off. The valve device 13 used here may also be any one that makes the inside of the replenishing container 11 and the inside of the outer case 3 in a shut-off state, and allows both to communicate as necessary. For example, the open / close cock, stop valve, A stop valve or a check valve can be used.

  In the lithium ion secondary battery 1 having the above-described configuration, the color reagent corresponding to the lithium ion concentration in the electrolyte solution in the reagent container 10 and the electrolyte solution sealed in the outer case 3 are separated. (See FIG. 5A). For this reason, a color reagent and the electrolyte solution in the exterior case 3 do not react.

  When diagnosing the deterioration state of the electrolytic solution sealed in the outer case 3, that is, when measuring the lithium ion concentration in the electrolytic solution, the valve device 12 attached to the reagent container 10 is opened (FIG. 5B). reference).

  By opening the valve device 12, the exterior case 3 and the reagent container 10 communicate with each other, and the reagent container 10 is restored to its normal shape because it is elastically deformed while the pressure inside the reagent container 10 is reduced. Accordingly, the electrolytic solution in the outer case 3 is introduced into the reagent container 10. As described above, since the reagent container 10 enclosing the color reagent is in a depressurized state in advance, the electrolytic solution in the outer case 3 can be moved to the container enclosing the color reagent using a pressure difference, and bubbles are generated. It does not occur in the outer case 3.

  The colored reagent sealed in the reagent container 10 is dissolved by the introduced electrolytic solution, and a color reaction is performed according to the lithium ion concentration contained in the introduced electrolytic solution (see FIG. 5C).

  In this state, by closing the valve device 12, the communication between the exterior case 3 and the reagent container 10 is blocked, thereby preventing the color-reacted electrolytic solution and the color reagent from entering the exterior case 3. it can. That is, the color reaction occurs only in the reagent container 10 in which the color reagent is sealed, and the electrolytic solution and the color reagent do not flow back into the outer case 3. For this reason, when the electrolytic solution and the color reagent flow back into the outer case 3, the color reaction material reacts on the surface of the positive and negative active materials of the positive electrode layer and the negative electrode layer and adheres to and covers the surface. It is possible to prevent battery performance deterioration due to side reactions such as inhibiting the function of the battery.

  In addition, since the reagent container 10 for enclosing the color reagent is transparent or translucent, the coloration state can be judged from the outside, and the absorbance is measured by using an ultraviolet / visible spectrometer (UV / vis). Thus, the lithium ion concentration can be measured (see FIG. 5D). When a 1,10-phenanthroline derivative is used as the color reagent, the color changes from yellow to brown according to the lithium ion concentration. Moreover, since the thickness is made constant when the electrolyte is introduced into the reagent container 10 in which the color reagent is sealed, the lithium ion concentration can be quantitatively determined from the measured absorbance with high accuracy.

  The amount of the electrolyte solution enclosed in the outer case 3 is reduced by the amount consumed for the color reaction. When the valve device 13 attached to the replenishing container 11 is opened to replenish the consumed amount of the electrolyte, the replenishing container 11 and the outer case 3 are in communication with each other. In this state, the electrolytic solution in the elastic container can be pushed into the outer case 3 by deforming it by picking the replenishing container 11 and the electrolytic solution can be replenished into the outer case 3. By closing the valve device 13 in this state, the inside of the exterior case 3 can be sealed, and the amount of electric field liquid in the exterior case 3 can be maintained at a predetermined amount.

  Since a plurality of reagent containers 10 filled with the color reagent are installed, the lithium ion concentration can be measured a plurality of times, and the deterioration diagnosis can be repeated. Moreover, since a plurality of electrolytic solution replenishing containers 11 are provided, the electrolytic solution can be supplemented for each color reaction.

  In the present embodiment, the following effects can be achieved.

  (A) A lithium ion secondary battery 1 in which a positive electrode, a negative electrode, and an electrolytic solution are incorporated in an outer case 3. And the reagent container 10 which enclosed the reagent which selectively reacts with the lithium ion in electrolyte solution and colors is arrange | positioned out of the exterior case 3. FIG. Then, the electrolyte solution in the outer case 3 can be introduced into the reagent container 10 at the time of deterioration diagnosis through the valve device 13 serving as a communication blocking means. Therefore, since the electrolytic solution in the outer case 3 is introduced into the reagent container 10 through the communication blocking means at the time of deterioration diagnosis, the electrolytic solution remaining in the outer case 3 does not react with the color reagent. For this reason, the color reaction material reacts on the surface of the positive and negative active materials of the positive electrode layer and the negative electrode layer and adheres to and covers the surface to prevent battery performance deterioration due to side reactions such as inhibiting the function as the active material. Can do.

  (A) A plurality of reagent containers 10 are individually connected to the inside of the outer case 3 via valve devices 12 as communication blocking means. For this reason, the measurement of the lithium ion concentration can be performed a plurality of times, and the deterioration diagnosis can be repeatedly performed.

  (C) The reagent container 10 is formed of a transparent or translucent material. For this reason, the coloration state can be judged from the outside, and the lithium ion concentration can be quantitatively measured by measuring the absorbance using an ultraviolet / visible spectrometer.

  (D) The communication blocking means is normally in a blocking state, and is formed by a valve device 12 that is opened when the electrolyte solution in the outer case 3 is introduced into the reagent container 10. For this reason, the color reaction can be caused only in the reagent container 10 in which the color reagent is enclosed, and the electrolytic solution and the color reagent do not flow back into the outer case 3.

  (E) The internal pressure of the reagent container 10 is adjusted in advance so as to be lower than the pressure in the outer case 3. For this reason, the electrolytic solution in the outer case 3 can be moved to the reagent container 10 in which the color reagent is sealed by using a pressure difference, and bubbles are not generated in the electrolytic solution in the outer case 3.

  (F) The reagent container 10 has a dimension set in advance when the electrolyte in the outer case 3 is introduced. For this reason, the lithium ion concentration can be obtained quantitatively from the measured absorbance.

  (G) In the lithium ion secondary battery 1, the replenishment container 11 enclosing the electrolyte is disposed outside the outer case 3, and the electrolyte in the replenishment container 11 is supplied to the outer case 3 via the valve device 13 as a communication blocking means. It was possible to supply it inside. For this reason, the electrolytic solution consumed for the color reaction can be newly replenished, and the amount of the electrolytic solution in the outer case 3 can be made constant.

  (H) A plurality of replenishing containers 11 are individually connected to the inside of the outer case 3 via valve devices 13 as communication blocking means. For this reason, the electrolytic solution can be replenished for each color reaction.

  (G) The communication blocking means is normally in a blocking state, and is formed by a valve device 13 that is opened when the electrolyte in the replenishing container 11 is supplied into the outer case 3. For this reason, since the electrolytic solution does not flow backward from the inside of the outer case 3 to the electrolyte replenishing container 11, the amount of the electrolytic solution in the outer case 3 does not decrease.

  Hereinafter, the deterioration diagnosis method of the lithium ion secondary battery 1 of the present invention will be described using each example. However, the present invention is not limited at all by the embodiments.

Example 1
As shown in FIG. 1, a reagent container 10 in which a reagent that colors in accordance with a lithium ion concentration in an electrolytic solution is enclosed is installed in a lithium ion secondary battery 1 including a laminate-type outer case 3. As the electrolytic solution, a solution in which lithium PF6, which is a lithium salt, was dissolved in a concentration of 1M in a mixed solution in which the ratio of ethylene carbonate (EC) to diethyl carbonate (DEC) was 1: 1 was used. Three reagent containers 10 enclosing the color reagent were installed, and the reagent container 10 enclosing the color reagent was designed to have a thickness of 2 mm when the electrolyte flowed in. A 1,10-phenanthroline derivative was sealed in a 20 mg reagent container 10 as a color reagent.

  As shown in FIG. 3, when the 1,10-phenanthroline derivative was sealed in the reagent container 10, a vacuum sealer was used so that the pressure was reduced. The inside of the outer case 3 of the lithium ion secondary battery 1 and the reagent container 10 in which the color reagent is sealed are connected as a valve device 12 by a cock, and are closed except when the color reaction is performed. Three replenishing containers 11 for replenishing the electrolytic solution were installed, and 0.2 mL of the electrolytic solution was sealed in each replenishing container 11. The inside of the outer case 3 of the lithium ion secondary battery 1 and the replenishment container 11 for replenishing the electrolyte solution were connected by a cock, and were kept in a closed state except when the color reaction was performed.

(Example 2)
Open the cock between the outer case 3 of the lithium ion secondary battery 1 and the reagent container 10 enclosing the color reagent, and let the electrolyte flow into the reagent container 10 enclosing the reduced color reagent. It was.

  After the reagent container 10 was filled with the electrolytic solution, the cock was closed to prevent the color reagent from flowing back into the outer case 3 of the lithium ion secondary battery 1. The color reagent was completely dissolved in the electrolytic solution and waited for 5 minutes until it became uniform. A color reaction as shown in FIG. 6 occurred, and the electrolytic solution turned brown.

  After the color reaction, in order to replenish the electrolyte, a cock between the exterior case 3 of the lithium ion secondary battery 1 and the replenishment container 11 for replenishing the electrolyte is opened, and the electrolyte flows into the exterior case 3. The electrolyte was replenished. After replenishing the electrolyte, the cock was closed to prevent the electrolyte from flowing back.

(Example 3)
After the lithium ion secondary battery 1 used in Example 2 was subjected to 300 cycles of charge and discharge, the second color test was similarly performed.

  The absorbance of the reaction solution was measured using an ultraviolet / visible spectrometer (UV / vis), and the lithium ion concentration was calculated to be 0.94 M. The change in lithium ion concentration due to deterioration was measured.

  In order to replenish the electrolytic solution after the color reaction, the cock between the inside of the outer case 3 of the lithium ion secondary battery 1 and the second replenishing container 11 for replenishing the electrolytic solution is opened, and the electrolytic solution is removed from the outer case 3. The electrolyte was replenished. After replenishing the electrolyte, the cock was closed to prevent the electrolyte from flowing back.

Example 4
The lithium ion secondary battery 1 used in Example 2 was subjected to 500 charge / discharge cycle tests, and then the third color test was performed in the same manner.

  The absorbance of the reaction solution was measured using an ultraviolet / visible spectrometer (UV / vis), and the lithium ion concentration was calculated to be 0.90 M. The change in lithium ion concentration due to deterioration was measured.

  After the color reaction, in order to replenish the electrolytic solution, the cock between the exterior case 3 of the lithium ion secondary battery 1 and the third replenishing container 11 for replenishing the electrolytic solution is opened, and the electrolytic solution is removed from the exterior case 3. The electrolyte was replenished. After replenishing the electrolyte, the cock was closed to prevent the electrolyte from flowing back.

  As described above, the lithium ion concentration measurement of the lithium ion secondary battery 1 could be easily and repeatedly performed.

  In addition, since the color reagent is not mixed in the outer case 3, the color reaction material reacts on the surface of the positive and negative active materials of the positive electrode layer and the negative electrode layer to cover and cover the surface, and functions as an active material. Side reactions and performance degradation, such as hindering, were negligible.

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery 2 Battery element 3 Exterior case 4 Positive electrode 5 Separator 6 Negative electrode 7 Single battery 8 Positive electrode tab 9 Negative electrode tab 10 Reagent container 11 Replenishment container 12, 13 Valve apparatus

Claims (9)

It is a lithium ion secondary battery in which a positive electrode, a negative electrode, and an electrolytic solution are built in an outer case,
A reagent container enclosing a reagent that selectively reacts with lithium ions in the electrolyte and colors is placed outside the outer case,
A lithium ion secondary battery characterized in that the electrolyte in the outer case can be introduced into the reagent container at the time of deterioration diagnosis through the communication blocking means.   2. The lithium ion secondary battery according to claim 1, wherein a plurality of the reagent containers are individually connected to the inside of the outer case through communication blocking means.   The lithium ion secondary battery according to claim 1 or 2, wherein the reagent container is formed of a transparent or translucent material.   4. The communication device according to claim 1, wherein the communication blocking means is normally in a blocking state and is formed by a valve device that is opened when the electrolyte in the outer case is introduced into the reagent container. The lithium ion secondary battery as described in any one.   The lithium ion secondary battery according to any one of claims 1 to 4, wherein an internal pressure of the reagent container is adjusted in advance so as to be lower than a pressure in the outer case.   The lithium ion secondary battery according to any one of claims 1 to 5, wherein the reagent container has a thickness set in advance when the electrolytic solution in the outer case is introduced. The lithium ion secondary battery has a replenishment container filled with an electrolyte solution disposed outside the outer case,
The lithium ion secondary battery according to any one of claims 1 to 6, wherein the electrolytic solution in the replenishing container can be supplied into the outer case through the communication blocking means.   The lithium ion secondary battery according to claim 7, wherein a plurality of the replenishing containers are individually connected to the inside of the outer case through communication blocking means.   9. The communication shut-off means is formed by a valve device that is normally in a shut-off state and opens when the electrolyte in the replenishing container is supplied into the outer case. Lithium ion secondary battery.

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