JP2014216304A - Gas absorption material for power storage device and power storage device including the same, and electrical apparatus and electronic apparatus including the power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a gas absorption material capable of reducing corrosion of a case made of a material having alkaline corrosive properties while maintaining a gas absorption ability; a power storage device including the gas absorption material; and an electrical apparatus and an electronic apparatus including the power storage device.SOLUTION: A gas absorption material 5 is used for a lithium ion battery (power storage device) 10 including a battery case 3 made of a material having alkaline corrosive properties. The gas absorption material contains a material A exhibiting alkaline properties by being brought into contact with water and a material B having water absorption properties.

Description

  The present invention relates to a gas absorbent material for an electricity storage device for absorbing gas generated by using the electricity storage device for a long period of time, an electricity storage device using the same, and an electric device and an electronic device using the electricity storage device. is there.

In an electricity storage device using a non-aqueous electrolyte, gas is generated by evaporating or decomposing the electrolytic solution due to repeated charging and discharging accompanying long-term use, and gas such as CO ₂ and water are generated inside. When the internal pressure of the case of the electricity storage device increases due to the generation of these gases and the like, the performance deteriorates due to the deformation of the case and the operation of the explosion-proof valve, and the electricity storage device reaches the end of its life.

  In order to solve such problems, various methods for suppressing decomposition of the electrolytic solution by adding various substances to the electrolytic solution have been proposed. For example, as an example of an electric double layer capacitor, a method of adding γ-butyrolactone, fluorobenzene, diphenyl compound, or the like to an electrolytic solution in order to make electrolysis difficult to occur has been proposed (see Patent Documents 1 to 3).

For example, an electric double layer capacitor with a CO ₂ absorption layer mainly composed of lithium hydroxide has been proposed as a method for preventing the deformation of the case by absorbing the gas generated inside the electricity storage device with various absorbent materials. (See Patent Document 4).

JP 2001-217150 A JP 2004-006803 A JP 2004-146610 A JP 2003-197487 A

  However, the method of adding an additive to an electrolytic solution as shown in Patent Documents 1 to 3 has a problem that the effect of suppressing gas generation is insufficient.

On the other hand, as shown in Patent Document 4, in the method of absorbing CO ₂ generated in the case with lithium hydroxide, water comes into contact with moisture generated in the case due to decomposition of the electrolytic solution or intrusion of outside air. Lithium oxide shows alkalinity. For this reason, an alkali-corrosive case such as an aluminum case is corroded, and as a result, the case is deformed. As a result, there is a problem that a long life cannot be realized.

  The present invention has been made in view of the above problems, and can maintain corrosion of a gas and can reduce corrosion of a case made of a material having alkali corrosiveness, and an electricity storage using the same. It is an object to provide a device, and an electric device and an electronic device using the power storage device.

  In order to achieve the above object, first, the present invention is a gas absorbing material for use in an electricity storage device having a case made of a material having alkali corrosiveness, and exhibits alkalinity when in contact with water. Provided is a gas absorbent comprising a substance A and a substance B having moisture absorption (Invention 1).

The substance A that exhibits alkalinity by contact with water can efficiently absorb CO ₂ based on the acid-base reaction, but corrodes a case made of a material having alkali corrosivity. However, in the gas absorbent according to the above invention (Invention 1), the substance B exhibiting the ability to absorb CO ₂ while exhibiting the ability to absorb CO ₂ by including the substance A that exhibits alkalinity by contacting with water is also included. Since it contains, the contact with the substance A and water is suppressed. For this reason, even if a case made of a material having alkali corrosivity is used, the corrosion of the material can be reduced, and thereby the life of the electricity storage device can be extended.

  In the said invention (invention 1), it is preferable that content ratio of the said substance A and the said substance B is 1: 4-4: 1 (invention 2).

  The gas absorbent according to the above inventions (Inventions 1 and 2) is preferably subjected to a drying treatment (Invention 3).

  2ndly, this invention provides the electrical storage device characterized by including the case which consists of a material which has alkali corrosivity, and the gas absorption material of the invention 1-3 accommodated in the said case (invention 4). ). In this invention (invention 4), it is preferable that the said electrical storage device is a lithium ion battery or an electric double layer capacitor (invention 5).

  Thirdly, the present invention provides an electric device comprising the electricity storage device according to the invention 4 or 5 (invention 6). Fourthly, the present invention provides an electronic device comprising the electricity storage device according to the fourth or fifth aspect (Invention 7).

According to the gas-absorbing material of the present invention, by including the substance A that exhibits alkalinity by being in contact with water, the substance B having water absorbability can be obtained while exhibiting the ability to absorb CO ₂ based on the acid-base reaction. Since it contains, the contact with the substance A and water can be suppressed. For this reason, even when a case made of a material having alkali corrosivity is used, the corrosion of the material can be reduced, and thereby the life of the electricity storage device can be extended. Such an electricity storage device using the gas absorbing material of the present invention can be suitably used for various electric devices and electronic devices.

It is the schematic which shows the lithium ion battery which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, each embodiment is only an example, and the present invention is not limited to these.

  FIG. 1 shows an embodiment of an electricity storage device to which the gas absorbent material of the present invention can be applied. In FIG. 1, a lithium ion battery 10 as an example of an electricity storage device according to this embodiment includes a positive electrode terminal 1, a negative electrode terminal 2, and a battery case (case) 3. In the lithium ion battery 10, an electrode body 4 and a gas absorbing material 5 are housed inside the battery case 3. The electrode body 4 includes a positive electrode current collector (not shown), a positive electrode plate (not shown), a negative electrode current collector (not shown), and a negative electrode plate. The positive electrode plate and the negative electrode Each plate has a structure wound around a separator (not shown). The positive terminal 1 is electrically connected to the positive electrode plate via the lead wire 6a, and the negative terminal 2 is electrically connected to the negative electrode plate via the lead wire 6b. The battery case 3 is made of a material having alkali corrosivity, but such a material is preferably aluminum or an aluminum alloy because it is versatile, inexpensive and lightweight. Further, in the present embodiment, the case where the battery case 3 is formed in a square shape is shown as an example, but the present invention is not limited to this case, and an arbitrary shape can be adopted.

  In the lithium ion battery 10, a safety valve (not shown) formed of a substantially cross-shaped thin portion is formed on the outer peripheral surface of the battery case 3. This safety valve may be formed of a thin portion having various shapes such as a substantially K shape, a substantially Y shape, a substantially X shape, a substantially T shape, and a substantially V shape. The safety valve has a role of releasing gas to the outside when the pressure in the battery case 3 rises due to gas generation or the like. This safety valve is generally designed to open at about 0.5-1.0 MPa.

The positive electrode plate is a current collector in which a positive electrode mixture is held on both surfaces. For example, the current collector is an aluminum foil having a thickness of about 20 μm, and the paste-like positive electrode mixture is polyvinylidene fluoride as a binder to lithium cobalt oxide (LiCoO ₂ ), which is a lithium-containing oxide of a transition metal. And acetylene black as a conductive material are added and kneaded. And the electrode plate for positive electrodes is obtained by applying this paste-like positive electrode mixture on both surfaces of the aluminum foil, followed by drying, rolling, and cutting into strips.

  The negative electrode plate is a current collector in which a negative electrode mixture is held on both surfaces. For example, the current collector is a copper foil having a thickness of about 10 μm, and the paste-like negative electrode mixture is obtained by adding polyvinylidene fluoride as a binder to graphite powder and then kneading. And the electrode plate for negative electrodes is obtained by applying this paste-like negative electrode mixture on both sides of the copper foil, followed by drying, rolling, and cutting into strips.

  A porous film is used as the separator. For example, a polyethylene microporous film can be used as the separator. The electrolyte solution impregnated in the separator is, for example, 1 mol / L of six fluorine in a mixed solution in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed at a ratio of 1: 1: 1. What added the lithium phosphoric acid phosphate can be used.

  The gas absorbing material 5 according to the present embodiment includes a substance A that exhibits alkalinity by contact with water and a substance B that has moisture absorption, and is a mixture thereof. Alternatively, it is formed into a tablet or the like. The gas absorbing material 5 is disposed, for example, in the vicinity of the safety valve.

Substance A showing alkalinity upon contact with water, by its nature, is capable of efficiently absorbing CO ₂ based on the acid-base reaction. The material of the substance A is not particularly limited as long as it has the above properties, but an inorganic material is preferable. Specifically, alkaline hydroxides such as magnesium hydroxide, sodium hydroxide, and calcium hydroxide; metal carbonates such as potassium carbonate, sodium carbonate, and calcium carbonate; sodium bicarbonate, magnesium bicarbonate, calcium bicarbonate, etc. Metal bicarbonate; other alkaline minerals, organic substances, porous materials, etc. can be used. Among these, sodium hydroxide, sodium aluminate, and potassium hydroxide are preferable from the viewpoint of being inexpensive.

  In addition, the material of the substance B having moisture absorption is preferably an inorganic material, but does not include a material corresponding to the above-described substance A, that is, a material that exhibits alkalinity when contacted with water. Specific examples of the material that can be used as the substance B include zeolite such as molecular sieve, silica gel, activated alumina, calcium chloride, and diphosphorus pentoxide. Among these, molecular sieves and zeolites are preferable from the viewpoint of being porous and having a large amount of absorption.

Here, the content ratio of the substance A and the substance B in the gas absorbent 5 is not particularly limited as long as the CO ₂ absorption capacity and the water absorption capacity are effectively exhibited, but the content of the substance A: the substance The content of B is preferably 1: 4 to 4: 1, and more preferably 1: 4 to 2: 1. By containing the substance A and the substance B in such a range, both the CO ₂ absorption capacity and the water absorption capacity can be effectively exhibited, and the life of the electricity storage device can be extended.

  In addition, the gas absorbent 5 according to the present embodiment includes, in addition to the substances A and B described above, substances that absorb other gases such as carbon monoxide and hydrogen within a range that does not impair the effects of the present embodiment. You may mix | blend.

  Moreover, it is preferable that the gas absorption material 5 containing the substance A and the substance B performs a drying process. Thereby, the water absorption ability of the substance B can be more effectively exhibited, and the life of the electricity storage device can be further extended. Here, the drying treatment may be performed before mixing the substance A and the substance B, or may be performed after the gas absorbing material 5 is mixed and formed into a block shape. Such a drying treatment is preferably performed, for example, at 140 to 200 ° C. for 60 to 180 minutes while reducing the pressure with a vacuum pump.

The effect | action is demonstrated about the electrical storage device which has the structure mentioned above. When the lithium ion battery 10 is used for a long time, the driving electrolyte contained in the electrode body 4 is decomposed to generate CO ₂ . In addition, moisture from the outside air enters the case after long-term use.

Although CO ₂ may cause an increase in the internal pressure of the battery case 3, according to the electricity storage device according to the present embodiment, CO ₂ is absorbed by the substance A contained in the gas absorbent 5, so that the internal pressure of the case is excessive. Do not raise. In addition, substance A is alkaline by contact with water and may corrode battery case 3, but moisture is absorbed by substance B contained in gas absorbent 5, so that substance A comes into contact with water. So that the case is not corroded.

Therefore, even when a material having alkali corrosivity such as aluminum is used for the battery case 3 and the substance A showing alkalinity by contact with water is used as the CO ₂ absorbent, the battery case 3 is not corroded. As a result, the deformation of the battery case 3 due to corrosion can be suppressed, and as a result, the life of the power storage device can be extended.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  In the above-described embodiment, the power storage device has been described as a lithium ion battery. However, the power storage device according to the present invention can be applied to other nonaqueous electrolyte power storage devices such as electric double layer capacitors such as lithium ion capacitors. Applicable.

  The present invention will be described in more detail based on the following examples, but the present invention is not limited to the following examples.

[Examples 1 to 3, Comparative Example 1]
Sodium hydroxide as a substance A (a substance capable of absorbing CO ₂ ) that exhibits alkalinity by contact with water, and zeolite (a product of Union Showa Co., Molecular Sieve 5A) as a substance B having a water absorption property, Mixing was performed at a content ratio shown in Table 1 to obtain gas absorbents (Examples 1 to 3, Comparative Example 1).

[Examples 4 to 6, Comparative Example 2]
Sodium hydroxide as a substance A (a substance capable of absorbing CO ₂ ) that exhibits alkalinity by contact with water, and zeolite (a molecular sieve 5A manufactured by Showa Union Co., Ltd.) as a substance B having a water absorption property, After mixing at the content ratio shown in Table 2, drying treatment was performed at 200 ° C. for 180 minutes to obtain gas absorbents (Examples 4 to 6, Comparative Example 2).

These gas absorbents are placed and sealed in a battery case (made of aluminum) of a lithium ion battery, stored in a thermostatic bath at 125 ° C. for one week, then taken out from the thermostatic bath, the battery case is disassembled, and the battery case The inner wall was observed.
The results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1, and the results of Examples 4 to 6 and Comparative Example 2 are shown in Table 2, respectively.

  As shown in Table 1, the gas absorbing material of Comparative Example 1 that does not contain zeolite as the substance B had the formation of precipitates and deformation of the case, whereas the gases of Examples 1 to 3 containing zeolite. These did not occur in the absorbent material. In particular, in Examples 2 and 3 in which the content ratio of sodium hydroxide as the substance A and zeolite as the substance B was in the range of 1: 4 to 2: 1, corrosion of the aluminum case was not observed.

  In addition, as shown in Table 2, by placing the gas absorbent in the battery case after drying, the reaction between the battery case and the gas absorbent is suppressed even in Comparative Example 2 that does not contain zeolite. However, the gas absorbents of Examples 4 to 6 containing zeolite did not show corrosion of the battery case.

  Since the gas absorbing material of the present invention and the electricity storage device using the same as described above can achieve a long life, the industrial applicability is extremely large as being usable for various electric devices and electronic devices.

DESCRIPTION OF SYMBOLS 1 ... Positive electrode terminal 2 ... Negative electrode terminal 3 ... Battery case 4 ... Electrode body 5 ... Gas absorption material 6a, 6b ... Lead wire 10 ... Lithium ion battery (electric storage device)

Claims (7)

A gas absorbing material for use in an electricity storage device having a case made of a material having alkali corrosivity,
A gas absorbent comprising a substance A that exhibits alkalinity when in contact with water, and a substance B that has moisture absorption.   2. The gas absorbent according to claim 1, wherein the content ratio of the substance A and the substance B is 1: 4 to 4: 1.   The gas absorbent according to claim 1 or 2, wherein a drying process is performed.   An electricity storage device comprising: a case made of a material having alkali corrosivity; and the gas absorbing material according to any one of claims 1 to 3 housed in the case.   The power storage device according to claim 4, wherein the power storage device is a lithium ion battery or an electric double layer capacitor.   An electrical apparatus comprising the electricity storage device according to claim 4.   An electronic apparatus comprising the electricity storage device according to claim 4.

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