JP2014220126A - Lithium ion battery and electronic apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion battery having a function to suppress blowout of gas and nonaqueous electrolyte vapor generated inside the battery in case of abnormality.SOLUTION: A nonaqueous electrolyte lithium ion battery E includes a positive electrode terminal 1 and a negative electrode terminal 2, a battery case 3, and an explosion-proof valve formed on the outer peripheral surface of the battery case 3, and accommodates an electrode body 10 inside the battery case 3. The electrode body 10 has a positive electrode collector 11 and an electrode plate 12 for a positive electrode, as well as a negative electrode collector 13 and an electrode plate 14 for a negative electrode. Each of the electrode plate 12 for a positive electrode and the electrode plate 14 for a negative electrode has a structure where the electrode plate is wound via a separator 15. A gas absorption material is disposed in the battery case (housing) 3 of the lithium ion battery E. Sodium aluminate is used as the gas absorption material.

Description

  The present invention relates to a lithium ion battery impregnated with a nonaqueous electrolytic solution, and more particularly to a lithium ion battery having a function of suppressing ejection of gas components generated inside the battery to the outside. The present invention also relates to an electronic device using the lithium ion battery.

  In recent years, large-capacity, high-output type lithium ion batteries have been put into practical use, and such lithium ion batteries are required to have higher safety and stability than conventional secondary batteries.

  In this lithium ion battery, generally, a positive electrode body and a negative electrode body are enclosed in a battery container together with an electrolyte solution, and lithium ions in the electrolyte solution are responsible for electrical conduction. A laminate of an electrode sheet and a separator is formed into a square shape. In this case, it is formed in a sandwich shape, and in the case of a cylindrical shape, it is formed in a roll shape, and the positive electrode body and negative electrode body lead portions as current collectors are connected to the respective terminals. And after accommodating the laminated body of various forms as mentioned above in the battery container of each corresponding shape, electrolyte solution is inject | poured from the opening part of a battery container, an electrolyte solution is impregnated into a laminated body, and a positive electrode body and a negative electrode It has a structure in which a battery container is enclosed with the body tip exposed to the outside.

  As the electrolytic solution used in the lithium ion battery, a nonaqueous electrolytic solution containing ethylene carbonate or the like is used. In order to improve the energy density of the lithium ion battery, it is effective to increase the usable voltage. Therefore, carbonate-based electrolytes that can be charged and discharged at a particularly high voltage are widely used.

In a lithium ion battery using such a carbonate-based electrolyte, the carbonate contained in the carbonate-based electrolyte is charged and discharged repeatedly over a long period of time, or overcharged or short-circuited. Causes degradation and electrolysis due to temperature rise. As a result, gas such as CO or CO ₂ is generated inside the battery, the internal pressure rises, the battery container is deformed, and there is a risk of causing problems such as an increase in internal resistance. Therefore, various techniques for absorbing or suppressing these gases have been developed.

As a technique for absorbing and suppressing such a gas, Patent Documents 1 to 3 disclose a technique of adding an additive for reducing the generation of gas in an electrolytic solution. Patent Document 4 proposes an electric double layer capacitor having a structure in which CO ₂ is absorbed by an absorbent mainly composed of a hydroxide such as lithium hydroxide.

JP-A-2005-235591 Japanese Patent Laid-Open No. 06-267593 Table 2010/147236 JP 2003-197487 A

However, the technique of adding an additive to the electrolytic solution described in Patent Documents 1 to 3 has a problem that the effect of suppressing the generation of gases such as CO and CO ₂ is not sufficient. In addition, the technique described in Patent Document 4 has an absorption effect to some extent such as CO _2, but when a hydroxide such as lithium hydroxide comes into contact with a non-aqueous electrolyte, the hydroxide dissolves in the non-aqueous electrolyte. There is a problem that it will. Further, when the hydroxide reacts with CO ₂ , moisture is generated and the corrosivity may be increased.

  The present invention has been made in view of the above problems, and provides a lithium ion battery having a function of suppressing the gas generated inside the battery during abnormal use or long-term use and the non-aqueous electrolyte vapor from being ejected to the outside. The purpose is to provide. Moreover, an object of this invention is to provide the electronic device excellent in safety incorporating this lithium ion.

  In order to solve the above problems, first, the present invention is a lithium ion battery in which a positive electrode and a negative electrode are enclosed in a battery container together with a non-aqueous electrolyte, and lithium ions in the non-aqueous electrolyte are responsible for electrical conduction. In addition, a lithium ion battery is provided in which the battery container is filled with sodium aluminate (Invention 1).

According to this invention (invention 1), the sodium aluminate filled in the battery container is absorbed by reacting with CO, CO ₂ or the like to form a compound. The amount of gas generated by the decomposition of the non-aqueous electrolyte can be reduced. Thereby, a deformation | transformation of a battery container can be suppressed and the lifetime improvement of a lithium ion battery can be aimed at.

  In the said invention (invention 1), it is preferable to fill a water absorbent together with the sodium aluminate (invention 2).

  According to this invention (invention 2), it is possible to prevent the battery container from being corroded by the alkali component generated by the reaction between sodium aluminate and the moisture.

  In the said invention (invention 1 and 2), it is preferable that the said non-aqueous electrolyte and sodium aluminate are isolated by the gas-liquid separation membrane (invention 3).

According to this invention (Invention 3), gas components such as CO and CO ₂ are separated by separating the gas component generated from the lithium ion battery and the non-aqueous electrolyte and disposing sodium aluminate on the gas component side. Can be selectively absorbed, and the decrease in the non-aqueous electrolyte can be kept to a minimum. As a result, a decrease in the capacity of the lithium ion battery can be suppressed. Furthermore, since the non-aqueous electrolyte and sodium aluminate are not in direct contact, the gas absorption performance of sodium aluminate can be maintained.

  Secondly, the present invention provides an electronic device comprising the lithium ion battery according to any one of the first to third aspects (Invention 4).

  According to this invention (Invention 4), while suppressing the capacity reduction of the lithium ion battery, the amount of gas generated by the decomposition of the non-aqueous electrolyte is reduced to suppress the deformation of the battery container, and the adverse effect of the lithium ion battery is eliminated. Electronic device.

According to the present invention, since the sodium aluminate is filled in the battery container of the lithium ion battery, the sodium aluminate filled in the battery container absorbs CO, CO _{2 and the} like, so that the capacity of the battery is reduced. It is possible to reduce the amount of gas generated by the decomposition of the non-aqueous electrolyte while suppressing the above. At this time, no moisture is generated. Thereby, a deformation | transformation of a battery container can be suppressed and the lifetime improvement of a lithium ion battery can be aimed at.

It is sectional drawing which shows schematically the internal structure of the non-aqueous electrolyte solution type 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 accompanying drawings. However, this embodiment is only an example, and the present invention is not limited to this.

  FIG. 1 is a longitudinal sectional view showing a lithium ion battery according to this embodiment. In FIG. 1, a lithium ion battery E includes a positive electrode terminal 1 and a negative electrode terminal 2, a battery case (housing) 3, and an explosion-proof valve (not shown) formed on the outer peripheral surface of the battery case 3 as required. The electrode body 10 is housed inside the battery case 3. The electrode body 10 has a positive electrode current collector 11 and a positive electrode plate 12, and a negative electrode current collector 13 and a negative electrode plate 14. The positive electrode plate 12 and the negative electrode plate 14 are separators, respectively. 15 is wound around. The positive terminal 1 is electrically connected to the positive electrode plate 12, and the negative terminal 2 is electrically connected to the negative electrode plate 14. The battery case 3 as a housing is, for example, a square battery tank can made of aluminum or stainless steel.

The positive electrode plate 12 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. The positive electrode plate 12 is obtained by applying this paste-like positive electrode mixture on both sides of the aluminum foil, followed by drying, rolling, and cutting into a strip.

  The negative electrode plate 14 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 10 μm, and the paste-like negative electrode mixture is obtained by kneading after adding polyvinylidene fluoride as a binder to graphite powder. The negative electrode plate 14 is obtained by applying the 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 15. For example, the separator 15 can be a polyethylene microporous film. Further, as the non-aqueous electrolytic solution impregnated in the separator, a non-aqueous organic electrolytic solution having lithium ion conductivity is preferable. For example, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) 1 A mixture obtained by adding 1 mol / L lithium hexafluorophosphate to a mixed solution mixed at a ratio of 1: 1 can be used.

A gas absorbing material is installed in the gap in the battery case (housing) 3 of the lithium ion battery E. As the gas absorbing material, sodium aluminate is used. Since this sodium aluminate reacts with CO and CO ₂ to form a compound and absorbs it, CO and CO _{2 and the} like are not re-released even if the partial pressure of the atmosphere changes. The amount of gas generated by the decomposition of the aqueous electrolyte can be reliably reduced and maintained. In addition, since no moisture is generated by the reaction with CO ₂ , there is no possibility that the performance of the gas absorbent is lowered or the corrosivity is increased. The gas absorbing material as described above can be used in various forms such as powder, granule, block, and tablet.

  In addition, what mixed about 25-75 volume% of water absorption materials with respect to 100 volume% of sodium aluminate can also be used for the purpose of suppressing that the performance of a gas absorption material falls with a water | moisture content. As the water absorbent, zeolite such as molecular sieve, silica gel, activated alumina, calcium chloride, diphosphorus pentoxide, and the like can be used, but molecular sieve is preferable because it is porous and has a large amount of absorption.

Rather than filling the battery case (casing) 3 as it is, this gas absorbing material is separated and installed by a gas-liquid separation membrane so that the non-aqueous electrolyte and sodium aluminate do not directly contact each other. Is preferred. In this way, by separating the non-aqueous electrolyte, sodium aluminate, and gas-liquid separation membrane, gas components such as CO and CO ₂ generated from the lithium ion battery permeate the gas-liquid separation membrane. Since the aqueous electrolyte does not permeate, the gas component can be selectively absorbed, and the reduction of the non-aqueous electrolyte can be minimized.

The effect | action is demonstrated about the lithium ion battery which has the structure mentioned above. When the lithium ion battery E is used for a long period of time, the non-aqueous electrolytic solution contained in the lithium ion battery E is decomposed and gas components such as CO ₂ are generated. This gas component such as CO ₂ may cause an increase in the internal pressure of the battery case (housing) 3. In this embodiment, sodium aluminate is disposed as a gas absorbent in the battery case (housing) 3. Therefore, the internal pressure of the battery case (housing) 3 is not excessively increased in order to absorb CO ₂ . In particular, since sodium aluminate forms a compound with CO ₂ , there is an effect that CO and CO ₂ are not re-released even when the partial pressure of the atmosphere changes. In addition, since no moisture is generated, the sodium aluminate dissolves in the moisture and becomes alkaline, and the battery case (housing) 3 is not corroded. As a result, it is possible to improve the safety and extend the life of the lithium ion battery.

  The present invention has been described above with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the lithium ion battery E may have a cylindrical shape, and further, a lithium ion battery may be further accommodated in a battery case that can accommodate the lithium ion battery, and a gas absorbing material may be provided in the battery case 3. .

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

Example 1
When 5 g of dried sodium aluminate was placed in a test vessel having a volume of 10 L and exposed to a carbon dioxide atmosphere for 2 hours, a decrease in carbon dioxide was confirmed. Furthermore, the moisture of sodium aluminate before and after exposure was measured by Karl Fischer. The results are shown in Table 1.

(Comparative Example 1)
When 5 g of dried sodium hydroxide was placed in a test vessel having a volume of 10 L and exposed to a carbon dioxide atmosphere for 2 hours, a decrease in carbon dioxide was confirmed. Furthermore, the moisture of sodium hydroxide before and after exposure was measured by Karl Fischer. The results are shown in Table 1.

  As is apparent from Table 1, in Example 1 using sodium aluminate as the absorbent, the amount of water did not change before and after exposure in a carbon dioxide atmosphere, whereas sodium hydroxide was used as the absorbent. In Comparative Example 1, an increase in water content was observed. In addition, although both the absorbers of Example 1 and Comparative Example 1 were left in the air and the carbon dioxide partial pressure in the atmosphere was drastically reduced, no re-emission of carbon dioxide was confirmed.

This is presumably because sodium aluminate reacts with carbon dioxide according to the following formula (1) to produce sodium carbonate, thereby absorbing carbon dioxide and not producing water as a by-product.
NaAlO ₂ + CO ₂ → NaCO ₃ + Al ₂ O ₃ (1)

On the other hand, sodium hydroxide reacts with carbon dioxide according to the following formulas (2) and (3) to produce sodium carbonate and sodium hydrogen carbonate, thereby absorbing carbon dioxide. At this time, water is produced as a by-product. it is conceivable that.
2NaOH + CO ₂ → Na ₂ CO ₃ + H ₂ O (2)
NaOH + CO ₂ → NaHCO ₃ (3)

Since the lithium ion battery of the present invention as described above absorbs gas such as CO and CO ₂ generated in the battery container of the lithium ion battery and does not release it again, the safety of the lithium ion battery is greatly increased. And its industrial applicability is extremely large. Also, an electronic device incorporating such a lithium ion battery is excellent in safety.

1 ... Positive terminal (positive electrode)
2 ... Negative terminal (negative electrode)
3. Battery case (housing)
4 ... Explosion-proof valve 11 ... Positive electrode current collector (positive electrode)
13 ... Negative electrode current collector (negative electrode)
E ... Lithium ion battery

Claims (4)

A positive electrode and a negative electrode are enclosed in a battery container together with a non-aqueous electrolyte solution, and lithium ions in the non-aqueous electrolyte solution are responsible for electrical conduction,
A lithium ion battery, wherein the battery container is filled with sodium aluminate.   The lithium ion battery according to claim 1, wherein a water absorbent is filled together with the sodium aluminate.   The lithium ion battery according to claim 1 or 2, wherein the non-aqueous electrolyte and sodium aluminate are separated by a gas-liquid separation membrane.   An electronic apparatus comprising the lithium ion battery according to any one of claims 1 to 3.

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