JPH11191417A - Nonaqueous electrolytic secondary battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent characteristic degradation form being generated afterwards, even when temperature becomes temporarily high by including material produc ing water or carbon dioxide through temperature rise inside a battery. SOLUTION: Interface reaction between electrode active material and an electrolyte caused by temperature rise at the time of charging is impeded by water produced from contained material, so as to suppress degradation of active material. Carbon dioxide produced in temperature rise hinders contact between the active material and electrolyte for suppressing the progress of reaction at an interface. It is preferable that material producing water be one or more kinds of a hydroxide of Zn or the like, a hydroxide oxide of Fe or the like, or a compound containing boric acid or crystal water, contained at a specified ratio in a positive electrode, a negative electrode or the electrolyte so as to produce water at 60-300 deg.C, and it is preferable that material producing carbon dioxide at the time of temperature rise be a carbonate of Rb or the like, or a hydrogen carbonate salt of Na or the like contained at a specified ratio in the positive electrode, the negative electrode, a nonaqueous electrolyte or a separator to produce carbon dioxide at 80-300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-energy-density nonaqueous electrolyte secondary battery having improved high-temperature storage characteristics without deteriorating battery performance.

[0002]

2. Description of the Related Art A non-aqueous electrolyte secondary battery using an alkali metal such as lithium or sodium as a negative electrode has a high electromotive force,
Since high energy density can be expected compared to conventional nickel-cadmium storage batteries and lead storage batteries, research has been actively conducted. In particular, a nonaqueous electrolyte secondary battery using Li as a negative electrode has already been put to practical use as a power source for small consumer cordless devices such as information / communication devices and AV devices, and mass production has begun. In a non-aqueous electrolyte secondary battery currently in practical use, a carbon material is used for a negative electrode, and LiCoO _{2 is} used for a positive electrode.
Is used. Also, positive electrode materials and negative electrode materials have been actively studied for lower cost and higher energy density. As materials are developed and low-cost, high-performance materials are developed, applications of nonaqueous electrolyte secondary batteries are expected to be widespread, not only in current small portable devices. One example is application to electric vehicles. The operating temperature range of currently commercially available nonaqueous electrolyte secondary batteries is -20C to 60C. In a normal use, since the temperature used is around room temperature, there is no significant problem with respect to the temperature. However, there is a possibility that use under severe conditions will be required as the applications expand in the future.

[0003]

A lithium secondary battery, which is a non-aqueous electrolyte secondary battery currently used, generates heat internally during discharge. This is not a big problem because a small battery generates a small amount of heat and has good heat radiation from the battery surface. However, in the case of a large battery for an electric vehicle or the like, when a large current is taken out, heat dissipation cannot catch up with heat generation, and the inside of the battery may temporarily become hot. Also, when the battery is considered to be used for a device that generates heat, the battery may be exposed to high temperatures. When a lithium secondary battery is exposed to a high temperature in a charged state, its characteristics are greatly deteriorated by a reaction that is considered to involve the active material in the charged state and a non-aqueous electrolyte. The battery deteriorated due to the high temperature does not recover, and the battery becomes unusable.

Therefore, in order to use the non-aqueous electrolyte secondary battery in an application that may be exposed to a high temperature, it is necessary to suppress the characteristic deterioration due to the heat. An object of the present invention is to provide a non-aqueous electrolyte secondary battery that does not cause subsequent deterioration in characteristics even when the battery is temporarily exposed to a high temperature.

[0005]

The non-aqueous electrolyte secondary battery of the present invention is arranged inside a battery, that is, in a power generating element such as a positive electrode, a negative electrode, and a non-aqueous electrolyte, in a void portion in the battery, and inside the other battery. A member that generates water or carbon dioxide gas when the temperature rises. Here, the substance that generates water includes a compound that generates water by a chemical reaction, a substance that contains water as a compound, a substance that contains water by adsorption, and water that is contained inside a capsule or a bag-shaped structure. Any material that results in water, such as water, may be used. Carbonate or hydrogen carbonate can be used as the substance that generates carbon dioxide. The present invention also includes a chargeable / dischargeable positive electrode, a chargeable / dischargeable negative electrode, and a nonaqueous electrolyte, wherein the positive electrode, the negative electrode, or the nonaqueous electrolyte is selected from the group consisting of an aluminum compound, a nickel compound, and a cobalt compound. And a non-aqueous electrolyte secondary battery comprising at least one of the foregoing. According to the present invention, even when the battery is temporarily exposed to a high temperature, it is possible to obtain a nonaqueous electrolyte secondary battery with little subsequent characteristic deterioration.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in the present invention, a substance that generates water or carbon dioxide gas when a temperature rises is included in a battery. When the temperature of the battery in the charged state increases, the electrode active material in the charged state reacts with the electrolyte at the interface, and the active material deteriorates, so that the capacity of the subsequent battery decreases. Since this reaction is accompanied by heat generation, when the reaction starts to occur, the temperature of that portion increases, and the reaction is more likely to occur, and the reaction proceeds in a chain. If the battery contains a substance that generates water due to a rise in temperature, the above-described reaction occurs.
That is, a small amount of water is generated in the vicinity of the portion where the reaction in which the active material is degraded occurs, and this water inhibits the reaction. This suppresses the chain reaction of the degradation of the active material. By including a substance that generates water by a rise in temperature inside the battery in this manner, it is possible to suppress deterioration in battery characteristics after the battery temperature temporarily rises.

When a battery contains a substance that generates carbon dioxide gas, which is an inert gas due to a rise in temperature, when the active material in a charged state and the electrolyte begin to react due to the rise in temperature, the temperature rises due to the reaction. The carbon dioxide gas is generated from a carbon dioxide gas-producing substance present in the vicinity. Since the carbon dioxide gas prevents contact between the active material and the electrolytic solution, further reaction hardly occurs, and deterioration of battery characteristics can be suppressed. The temperature at which water is generated from the substance that generates water is preferably 60 ° C. or higher. A substance that generates water at a low temperature of less than 60 ° C. is not suitable because water is generated in a drying step at the time of manufacturing an electrode and does not generate water when the battery is actually heated. Further, even if the temperature of the drying step for producing the battery is lowered, the water production reaction occurs in a normal use temperature range, and thus the battery characteristics may be adversely affected, which is not preferable. On the other hand, when the temperature exceeds 300 ° C., the battery is deteriorated before the effect appears, and a sufficient effect cannot be obtained. The upper limit of the water-forming temperature of the water-forming substance is preferably 250 ° C. or lower, particularly preferably 150 ° C. or lower.

[0008] As a substance which produces water by a rise in temperature, hydroxide, boric acid containing OH in the compound as well as hydroxide, and a compound having water of crystallization are suitable. As the hydroxide, zinc hydroxide, aluminum hydroxide, cadmium hydroxide, chromium hydroxide, cobalt hydroxide, nickel hydroxide, manganese hydroxide, calcium hydroxide, magnesium hydroxide, zirconium hydroxide, iron hydroxide hydroxide And nickel oxyhydroxide are preferably used. Examples of the compound having water of crystallization include aluminum oxide hydrate, barium nitrate hydrate, calcium sulfate hydrate, cobalt phosphate hydrate, antimony oxide hydrate, tin oxide hydrate, and titanium oxide water. A hydrate, bismuth oxide hydrate, and tungsten oxide hydrate are preferably used. When a substance that generates water by a temperature rise is contained in the positive electrode or the negative electrode, the content ratio is preferably 0.5 to 20 parts by weight per 100 parts by weight of the active material of the electrode. Further, when the non-aqueous electrolyte contains a substance that generates water due to a temperature rise, its content is 0.5 to 100 parts by weight of the non-aqueous electrolyte.
30 parts by weight are preferred.

The temperature at which the carbon dioxide-generating substance generates carbon dioxide is preferably 80 ° C. or higher. If the temperature is lower than 80 ° C., the temperature is too low, and carbon dioxide gas may be generated under normal use conditions, which is not preferable. When the temperature exceeds 300 ° C., the battery is deteriorated before the effect appears, and a sufficient effect cannot be obtained. The upper limit of the temperature at which the carbon dioxide is generated is 250 ° C. or less,
Particularly, the temperature is preferably 150 ° C. or lower. Substances that generate carbon dioxide gas when the temperature rises include carbonates and bicarbonates.
Among them, rubidium carbonate, barium carbonate, cobalt carbonate, iron carbonate, nickel carbonate, zinc carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, rubidium hydrogen carbonate, cesium hydrogen carbonate, and the like are suitable. When the positive electrode or the negative electrode contains a substance that generates carbon dioxide gas due to a rise in temperature, the content is preferably 0.5 to 25 parts by weight per 100 parts by weight of the active material of the electrode. When a substance that generates carbon dioxide gas due to a temperature rise is contained in the nonaqueous electrolyte or the separator, the content ratio is preferably 0.5 to 30 parts by weight per 100 parts by weight of the nonaqueous electrolyte.

Further, the present inventors do not produce water or carbon dioxide gas, but a compound of aluminum, nickel or cobalt has an effect of suppressing a reaction between a charged active material and an electrolytic solution. Was found. As the aluminum compound, aluminum oxide, aluminum sulfate, aluminum phosphate, and aluminum chloride are preferable. Nickel compounds include nickel oxide,
Nickel sulfate, nickel phosphate, and nickel carbonate are preferred. Further, as the cobalt compound, cobalt oxide, cobalt sulfate, cobalt phosphate, cobalt carbonate,
And cobalt oxalate are preferred. The above aluminum compound, nickel compound, and cobalt compound,
Suitable for adding to the positive or negative electrode. When the compound is contained in the positive electrode or the negative electrode, the content ratio is preferably 0.5 to 20 parts by weight per 100 parts by weight of the active material of the electrode. When added to the electrolyte, aluminum acetate, aluminum oxalate, nickel perchlorate, nickel nitrate, nickel acetate, cobalt acetate, and cobalt perchlorate are used in addition to the above compounds. When the compound is contained in the non-aqueous electrolyte, the content is preferably 0.5 to 30 parts by weight per 100 parts by weight of the non-aqueous electrolyte.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. It goes without saying that the present invention is not limited to these examples.

Embodiment 1 In this embodiment, an example will be described in which a hydroxide and boric acid are used as substances that generate water by increasing the temperature, and these are added to a positive electrode mixture. The evaluation was performed using the cylindrical battery shown in FIG. The method for manufacturing the battery is described below. The positive electrode active materials include LiNO ₃ and Ni (O
H) ₂ and 650 in an oxygen atmosphere.
LiNiO ₂ synthesized by heating at ° C. was used. This active material was classified to 45 μm or less. To 100 g of the positive electrode active material, 10 g of carbon powder as a conductive agent, 8 g of polytetrafluoroethylene as a binder, and a petroleum-based solvent were added to form a paste, and 5 g of the compound shown in Table 1 was further added.
Added and mixed. The obtained paste was applied to a titanium core material, dried at 95 ° C., rolled, and then cut into a predetermined size to obtain a positive electrode plate. The weight of the positive electrode active material in the electrode is 3 g
And In addition, a positive electrode plate manufactured similarly without adding a hydroxide or the like was used as a comparative example.

The negative electrode active material is 300 mAh / g.
Was used. This carbon powder 1
Then, styrene-butadiene rubber was mixed as a binder with 00 g, a petroleum-based solvent was further added, and the mixture was sufficiently stirred to obtain a paste-like mixture. The mixing ratio of the carbon powder and the binder was 100: 5 by weight of the solids. The paste was applied to a copper core material, dried at 95 ° C., rolled, and cut to obtain a negative electrode plate. The weight of carbon in the electrode was 2 g. As the non-aqueous electrolyte, an equivolume mixed solution of ethylene carbonate and dimethoxyethane in which 1 mol / l of lithium perchlorate was dissolved was used. A microporous polypropylene film was used as a separator. The battery was assembled as follows.
A positive electrode plate 1 and a negative electrode plate 2 each having a positive electrode lead 4 and a negative electrode lead made of the same material as the core material, respectively, are attached by spot welding, and a band-shaped porous polypropylene separator 3 wider than the both electrode plates is interposed therebetween. The whole was spirally wound to form an electrode group. Next, polypropylene insulating plates 6 and 7 are arranged on the upper and lower sides of the electrode group, respectively.
To form a step at the top of the battery case 8, and then a non-aqueous electrolyte was injected. The injection amount of the electrolyte was 2.6 ml.
The opening of the battery case was sealed with a sealing plate 9 having a positive electrode terminal 10 to obtain a battery.

A high-temperature durability test was performed on the battery assembled as described above. That is, at 20.degree.
The battery was charged to 4.2 volts at a constant current of 5 mA and then discharged to 3 volts.
After the completion of the charge in the cycle, the temperature was kept at 150 ° C. for 2 minutes. Thereafter, the temperature was returned to 20 ° C., and discharge was performed under the same conditions. Here, the capacity retention rate was defined as follows. Capacity retention rate = 100 × (discharged electricity amount at eleventh cycle /
(Electricity Discharge at 10th Cycle) After completion of the discharge at the 11th cycle, charging was performed, and the discharge capacity after that was evaluated. Here, the capacity recovery rate was defined as follows. Capacity recovery rate = 100 × (discharged electricity amount at 12th cycle /
Table 1 shows the capacity retention rate and the capacity recovery rate after the high-temperature durability test of each battery.

[0015]

[Table 1]

In the battery of the comparative example in which no hydroxide or boric acid was added to the positive electrode mixture, a large capacity decrease was observed after the test, and the capacity retention ratio was low. In addition, the capacity remained low and the capacity recovery rate was low even after charging and discharging. On the other hand, the battery of this example in which hydroxide was added to the positive electrode had high values for both the capacity retention rate and the capacity recovery rate. From this, the addition of a compound that generates water by a rise in temperature, particularly a hydroxide having OH in the compound, to the positive electrode mixture suppresses a decrease in capacity due to exposure of the battery to high temperatures. I found that there was. This effect
It is considered that the reaction that generates water suppresses a degradation reaction that is considered to involve the active material in the charged state, the electrolyte, and the like.

Embodiment 2 In this embodiment, an example in which a hydroxide or boric acid is added to the negative electrode mixture as a substance that generates water by increasing the temperature will be described. The method for manufacturing the battery is described below. As the positive electrode active material, 45 as in Example 1 was used.
LiNiO ₂ classified to μm or less was used. To 100 g of the positive electrode active material, 10 g of carbon powder, 8 g of polytetrafluoroethylene, and a petroleum-based solvent were added to form a paste.
The obtained paste was applied to a titanium core material, dried at 95 ° C., and rolled to a predetermined size to obtain a positive electrode plate. The weight of the positive electrode active material in the electrode was 3 g. The same carbon material as in Example 1 was used for the negative electrode. A styrene-butadiene rubber was mixed with 100 g of the carbon powder, a petroleum solvent was added, and the mixture was sufficiently stirred to obtain a paste-like mixture. To this mixture, 5 g of the compound shown in Table 2 was added and mixed. The mixing ratio of the carbon powder and the binder was 100: 5 by weight of the solids. This paste is applied to a copper core,
It was dried at 95 ° C., rolled and cut to obtain a negative electrode plate. The weight of carbon in the electrode was 2 g. A battery was assembled and subjected to a high-temperature durability test in the same manner as in Example 1 except for the positive and negative electrodes described above. Table 2 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test.

[0018]

[Table 2]

In the battery of this embodiment in which hydroxide or the like was added to the negative electrode, high values were obtained for both the capacity retention rate and the capacity recovery rate. This indicates that the addition of a compound that generates water by raising the temperature into the negative electrode, particularly a hydroxide having OH in the compound, has the effect of suppressing a decrease in capacity due to exposure of the battery to high temperatures. I understood. This effect is considered to be due to the fact that a reaction that generates water suppresses a deterioration reaction that is considered to involve the charged active material and the electrolyte.

Embodiment 3 This embodiment shows an example in which a compound having water of crystallization is added to the positive electrode mixture as a substance that generates water by increasing the temperature. A battery was assembled in the same manner as in Example 1 except that a positive electrode was prepared using a compound having water of crystallization shown in Table 3 instead of the hydroxide. Table 3 shows the capacity retention rate and the capacity recovery rate after the high-temperature durability test of each battery. The battery of this example has a high value for both the capacity retention rate and the capacity recovery rate. This effect
It is considered that the reaction that generates water suppresses a degradation reaction that is considered to involve the active material in the charged state, the electrolyte, and the like.

[0021]

[Table 3]

Embodiment 4 This embodiment shows an example in which a compound having water of crystallization is added to the negative electrode mixture.
A battery was assembled in the same manner as in Example 2, except that a negative electrode was produced using a compound having water of crystallization shown in Table 4 instead of the hydroxide. Table 4 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test. The battery of this embodiment is
Both the capacity retention rate and the capacity recovery rate have high values.

[0023]

[Table 4]

Embodiment 5 In the present embodiment, in the electrolyte,
An example in which a substance that generates water by a rise in temperature is added will be described. A hydroxide was used as a compound that generates water by increasing the temperature. As an electrolyte, an equivolume mixed solution of ethylene carbonate and dimethoxyethane in which 1 mol / l of lithium perchlorate was dissolved was used. The electrolyte was prepared by adding a hydroxide shown in Table 5 at a ratio of 3 parts by weight per 100 parts by weight of the electrolyte. In this case, the compound to be added is
It does not need to be dissolved in the electrolyte. A battery was assembled using the same positive electrode and negative electrode as in the comparative example, and evaluated under the same conditions as in Example 1. Table 5 shows the capacity retention rate and capacity recovery rate after the high-temperature durability test of each battery.

[0025]

[Table 5]

The battery of this embodiment has a high capacity retention rate and a high capacity recovery rate. From this, it can be seen that even when a substance that generates water due to a rise in temperature is added to the electrolyte, the same effect as when it is added to the electrode can be obtained. Similarly, Table 6 shows the results obtained when a compound containing water of crystallization was used as the compound that generates water by increasing the temperature. By adding the compound containing water of crystallization to the electrolyte, high values were obtained for both the capacity retention rate and the capacity recovery rate.

[0027]

[Table 6]

Example 6 In this example, the addition ratio of a substance that generates water due to a rise in temperature was examined. First, the positive electrode will be described. A battery similar to that of Example 1 was manufactured using cobalt hydroxide as a substance that generates water by heating and changing the ratio of addition to the positive electrode active material. FIG. 2 shows the relationship between the addition ratio of cobalt hydroxide and the initial capacity and capacity retention of the battery. When the addition ratio exceeded 20 parts by weight per 100 parts by weight of the active material, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that, in addition to the decrease in the amount of the active material in the electrode, the conductivity between the active materials is inhibited. On the other hand, as for the capacity retention rate after heating, the addition rate was as follows.
Good values were shown at 0.5 parts by weight or more per 100 parts by weight. From these results, it is understood that the appropriate addition ratio is 0.5 to 20 parts by weight per 100 parts by weight of the active material.
Although cobalt hydroxide was used here, similar results were obtained when other hydroxides, boric acid, and compounds having water of crystallization were used.

Next, the rate of addition of a substance that generates water due to a rise in temperature to the negative electrode was examined. A battery similar to that of Example 2 was manufactured by using nickel hydroxide as a substance that generates water by heating and changing the addition ratio. FIG. 3 shows the relationship between the proportion of nickel hydroxide added to the negative electrode active material and the initial capacity and capacity retention of the battery. Addition ratio of active material 1
Above 20 parts by weight per 00 parts by weight, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that, in addition to the decrease in the amount of the active material in the electrode, the conductivity between the active materials is inhibited. On the other hand, the capacity retention ratio after heating showed a good value when the addition ratio was 0.5 parts by weight or more per 100 parts by weight of the active material. From these results, the addition ratio was 10
It is understood that 0.5 to 20 parts by weight per 0 parts by weight is suitable. Although cobalt hydroxide was used here, similar results were obtained when other hydroxides, boric acid, and compounds having water of crystallization were used.

Next, the rate of addition of a substance that produces water by increasing the temperature to the electrolyte was examined. Aluminum oxide hydrate (Al ₂ O _3.
A battery similar to that of Example 5 was produced using 3H ₂ O) and changing the addition ratio. FIG. 4 shows the relationship between the ratio of addition to the electrolyte and the initial capacity and capacity retention of the battery. When the addition ratio of aluminum oxide hydrate exceeded 30 parts by weight per 100 parts by weight of the electrolyte, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that the additive lowers the ionic conductivity of the electrolyte or inhibits the reaction of the electrode. On the other hand, the capacity retention ratio after heating showed a good value when the addition ratio was 0.5 parts by weight or more per 100 parts by weight of the active material. From these results, it is understood that the suitable addition ratio is 0.5 to 30 parts by weight per 100 parts by weight of the electrolyte. Although Al ₂ O ₃ .3H ₂ O was used here, similar results were obtained when other hydroxides, boric acid, and compounds having water of crystallization were used.

Example 7 Here, a case was examined in which a substance that generates water due to a rise in temperature was disposed in a part of the battery other than the positive electrode mixture, the negative electrode mixture, and the electrolyte. The positive electrode, the negative electrode, and the electrolyte were the same as in the comparative example described in Example 1. Then, nickel hydroxide is applied to the space in the center of the electrode group formed by spirally winding the positive / negative electrode and the separator, between the electrode group and the battery case, and between the sealing plate at the top of the electrode group. A battery to which 0.5 g was added was prepared. A comparative example was prepared as usual without any addition. Table 7 shows the results of the same evaluation as in Example 1.

[0032]

[Table 7]

As shown in Table 7, by including a substance that generates water by increasing the temperature inside the battery other than in the electrode mixture and the electrolyte, high values of both the capacity retention rate and the capacity recovery rate can be obtained. Was. It has been found that if the substance that generates water due to the temperature rise is inside the battery even in the electrode mixture or the electrolyte, deterioration of the characteristics when the battery temporarily becomes high temperature can be suppressed. This effect is considered to be due to the fact that the generation of water suppresses a deterioration reaction that is considered to involve the charged active material and the electrolyte. Here, nickel hydroxide was used as a compound that generates water by increasing the temperature, but other than this, zinc hydroxide, aluminum hydroxide, cadmium hydroxide, chromium hydroxide, cobalt hydroxide, nickel hydroxide, water Compounds containing OH in compounds such as hydroxides and boric acid such as manganese oxide, calcium hydroxide, magnesium hydroxide, zirconium hydroxide and iron oxide hydroxide, aluminum oxide hydrate, barium nitrate hydrate, calcium sulfate Hydrate, cobalt phosphate hydrate,
Performed similar tests with various compounds such as antimony oxide hydrate, tin oxide hydrate, titanium oxide hydrate, bismuth oxide hydrate, compounds having water of crystallization such as hydrated tungsten oxide, and similar results. was gotten.

In Examples 1 to 7, it was clarified that the deterioration of characteristics when the battery was temporarily exposed to a high temperature could be suppressed by including a compound that generates water by increasing the temperature inside the battery. . As described above, this effect is due to the fact that the generation of water suppresses the degradation reaction of the battery at high temperatures. From this, other than the compounds having a hydroxide or water of crystallization shown so far, any substance that results in water due to a rise in temperature may be used, such as a substance that releases adsorbed water, It is needless to say that the same effect can be obtained even in a capsule-like or pack-like structure containing. The temperature at which water is generated is preferably 60 ° C. or higher. A substance that generates water at a low temperature of less than 60 ° C. is not suitable because water is generated by drying during electrode fabrication and cannot react when the battery is actually heated. Even if the drying temperature is lowered, a water-forming reaction occurs in a normal use temperature range, which may adversely affect the characteristics of the battery, which is not preferable.

Embodiment 8 This embodiment shows an example in which a substance that generates carbon dioxide gas when the temperature rises is added to the positive electrode mixture. Carbonate and bicarbonate were used as substances that generate carbon dioxide when the temperature rises. A battery was assembled in the same manner as in Example 1 except that the compounds shown in Table 8 were used instead of the hydroxide. Table 8 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test.

[0036]

[Table 8]

In the battery of the present example in which carbonate or bicarbonate was added to the positive electrode, high values were obtained for both the capacity retention rate and the capacity recovery rate. This indicates that the addition of carbonate or bicarbonate to the positive electrode mixture has an effect of suppressing a decrease in capacity due to exposure of the battery to high temperatures. It is considered that this effect is due to the fact that the degradation reaction considered to involve the charged active material and the electrolyte is suppressed by these materials.

Embodiment 9 This embodiment shows an example in which a compound that generates carbon dioxide gas when the temperature rises is added to the negative electrode mixture. Carbonates and bicarbonates were used as compounds that generate carbon dioxide gas when the temperature rises. Example 2 except that the compounds shown in Table 9 were used instead of the hydroxides
A battery was assembled in the same manner. Table 9 shows the capacity retention rate and the capacity recovery rate after the high-temperature durability test of each battery.

[0039]

[Table 9]

In the battery of this example in which a carbonate or a hydrogen carbonate was added to the negative electrode, high values were obtained for both the capacity retention rate and the capacity recovery rate as in the battery of Example 8.

Example 10 This example shows an example in which a compound that generates carbon dioxide gas when the temperature rises is added to a metal lithium anode. As compounds that generate carbon dioxide gas when the temperature rises, carbonates other than lithium carbonate and hydrogen carbonates were used. As the metal lithium negative electrode, one obtained by cutting a lithium foil having a thickness of 600 μm and attaching a lead terminal was used. Carbonates or bicarbonates shown in Table 10 were dispersed in a petroleum-based solvent, sprayed on the surface of the negative electrode, and the solvent was evaporated and dried. From the weight difference before and after this operation, the weight of the carbonate or bicarbonate attached to the negative electrode was determined, and the ratio was adjusted to about 10 parts by weight with respect to 100 parts by weight of metallic lithium. A battery similar to that of Example 2 was assembled except for the negative electrode. The battery was evaluated in the same manner as in Example 1 except that the heating temperature after the completion of the eleventh charge was set to 100 ° C. Table 10 shows the capacity retention rate and the capacity recovery rate after the high-temperature durability test of each battery.

[0042]

[Table 10]

In the battery of this example, high values were obtained for both the capacity retention rate and the capacity recovery rate. This indicates that, even when the negative electrode is metallic lithium, the addition of carbonate or bicarbonate has an effect of suppressing a decrease in capacity due to exposure of the battery to high temperatures.

Embodiment 11 This embodiment shows an example in which a compound that generates carbon dioxide gas by a rise in temperature is added to a nonaqueous electrolyte. Carbonates and bicarbonates were used as compounds that generate carbon dioxide when the temperature rises. A battery was assembled in the same manner as in Example 5 except that the compounds shown in Table 11 were used as additives to the electrolyte, and evaluated under the same conditions as in Example 1. Table 11 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test. The battery according to the present embodiment has high values for both the capacity retention rate and the capacity recovery rate.

[0045]

[Table 11]

Embodiment 12 In this embodiment, an example will be described in which a compound that generates carbon dioxide gas when the temperature rises is added to the separator. Carbonate and bicarbonate were used as compounds that generate carbon dioxide when the temperature rises. Table 12
Was dispersed in dimethoxyethane, applied to a separator made of a microporous polypropylene film, and dried to adhere the compound to the surface of the separator. A battery was assembled in the same manner as in the comparative example described in Example 1, except that this separator was used. Table 12 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test. The battery according to the present embodiment has high values for both the capacity retention rate and the capacity recovery rate. It can be seen that the same effect as in the example in which the compound that generates carbon dioxide gas at the time of temperature rise is added to the separator can be obtained.

[0047]

[Table 12]

Example 13 In this example, the addition ratio of a substance that generates carbon dioxide gas by a rise in temperature was examined. A battery similar to that of Example 1 was manufactured using cobalt carbonate as a substance that generates carbon dioxide gas by heating, and changing the ratio of addition to the positive electrode active material. FIG. 5 shows the relationship between the addition ratio of cobalt carbonate and the initial capacity and capacity retention of the battery.
When the addition ratio exceeded 25 parts by weight per 100 parts by weight of the active material, the initial capacity decreased sharply. This is considered to be due to the fact that, in addition to the decrease in the amount of the active material in the electrode, the conductivity between the active materials is inhibited. On the other hand, the capacity retention ratio after heating showed a good value at an addition ratio of 0.5 part by weight or more per 100 parts by weight of the active material. From these results, it is understood that the appropriate addition ratio is 0.5 to 25 parts by weight per 100 parts by weight of the active material. Here, cobalt carbonate was used, but similar results are obtained when other carbonates or bicarbonates used in Example 8 are used.

Next, the rate of addition of a substance that generates carbon dioxide gas due to an increase in temperature to the negative electrode was examined. Sodium bicarbonate is used as a substance that generates water by heating,
A battery similar to that of Example 2 was produced by changing the addition ratio. FIG. 6 shows the relationship between the ratio of sodium hydrogen carbonate added to the negative electrode active material and the initial capacity and capacity retention of the battery. When the addition ratio exceeded 25 parts by weight per 100 parts by weight of the active material, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that, in addition to the decrease in the amount of the active material in the electrode, the conductivity between the active materials is inhibited. On the other hand, the capacity retention ratio after heating showed a good value when the addition ratio was 0.5 parts by weight or more per 100 parts by weight of the active material. From these results, it is understood that the appropriate addition ratio is 0.5 to 25 parts by weight per 100 parts by weight of the active material. Although sodium bicarbonate was used here, similar results can be obtained when other carbonates or bicarbonates used in Example 9 were used.

Next, the rate of addition of a substance that produces water by increasing the temperature to the electrolyte was examined. A battery similar to that of Example 5 was manufactured by using zinc carbonate as a substance that generates water by heating and changing the addition ratio. FIG. 7 shows the relationship between the ratio of addition to the electrolyte and the initial capacity and capacity retention of the battery.
Shown in When the addition ratio of zinc carbonate exceeded 30 parts by weight per 100 parts by weight of the electrolyte, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that the additive lowers the ionic conductivity of the electrolyte or inhibits the reaction of the electrode. On the other hand, the capacity retention ratio after heating showed a good value when the addition ratio was 0.5 parts by weight or more per 100 parts by weight of the active material. From these results, it is understood that the suitable addition ratio is 0.5 to 30 parts by weight per 100 parts by weight of the electrolyte.
Here, zinc carbonate was used, but similar results can be obtained when other carbonates or bicarbonates used in Example 11 are used.

Embodiment 14 In this embodiment, a positive electrode mixture,
An example in which a compound that generates carbon dioxide gas when the temperature rises was disposed in a part of the battery other than the negative electrode mixture and the electrolyte was examined. The positive electrode, the negative electrode, and the electrolyte were the same as in the comparative example described in Example 1. Then, barium carbonate was added to the space at the center of the electrode group formed by spirally winding the positive / negative electrode and the separator, between the electrode group and the battery container, and between the sealing plate above the electrode group. A battery to which 0.5 g was added was produced. Table 1 shows the results of the evaluation under the same conditions as in Example 1.
3 is shown.

[0052]

[Table 13]

As shown in Table 13, by arranging a substance that generates carbon dioxide gas due to a temperature rise inside the battery other than in the mixture or the electrolyte, a high capacity retention rate and a high capacity recovery rate can be obtained. Was. It was found that if the substance that generates carbon dioxide gas due to the temperature rise is inside the battery other than in the mixture or the electrolyte, it is possible to suppress the characteristic deterioration when the battery temporarily becomes high temperature. Here, barium carbonate is used as a compound that generates carbon dioxide gas when the temperature rises. However, the same effects can be obtained with the compounds listed above as compounds that generate carbon dioxide gas when the temperature rises.

<< Embodiment 15 >> In Embodiments 8 and 9,
Although an example in which a compound that generates carbon dioxide gas when the temperature rises is mixed in the positive electrode mixture and the negative electrode mixture has been described, this embodiment describes a case where the compound is attached to the surface of the positive electrode or the negative electrode. A positive electrode plate and a negative electrode plate were manufactured in the same manner as in the comparative example described in Example 1. Mix water or petroleum solvent with a compound that generates carbon dioxide when the temperature rises,
This was applied to the electrode surface, and the water or petroleum solvent of the medium was evaporated and dried. At this time, the compound may be dissolved in a medium or may be in a suspended state without being dissolved. In addition, as a method of attaching the compound to the electrode surface, the following method is also available. That is, the above-mentioned compound generating carbon dioxide is mixed with the same petroleum solvent used in the preparation of the mixture paste. Then, before applying the mixture paste to the core material and drying the mixture, the mixture is sprayed onto a portion where the mixture paste is applied, and then dried at 95 ° C. and rolled. According to this method, the compound to be added and the electrode mixture have good adhesion, and the compound added during battery fabrication does not fall off. A battery was prepared in the same manner as in the comparative example except that the above positive electrode was used, and evaluated in the same manner as in Example 1. Table 14 shows the results. Table 15 shows the evaluation results of the batteries manufactured in the same manner as the comparative example except that the above-described negative electrode was used. As is clear from Tables 14 and 15, the same results as in the case where the compound was added to the mixture were obtained in the example where the compound was added to the electrode surface.

[0055]

[Table 14]

[0056]

[Table 15]

Embodiment 16 This embodiment shows an example in which a positive electrode mixture contains a compound of aluminum, nickel, or cobalt. Table 16 instead of 5 g of hydroxide
A battery was prepared in the same manner as in Example 1 except that 7 g of the compound shown in Table 1 was used, and evaluated under the same conditions as in Example 1. Table 16 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test.

[0058]

[Table 16]

The battery of this example has a high capacity retention rate and a high capacity recovery rate. From this, it was found that the compound used here had an effect of suppressing a decrease in capacity due to exposure of the battery to high temperatures. This effect is considered to be due to the presence of the element of aluminum, nickel, or cobalt, which suppresses a deterioration reaction considered to involve the active material and the electrolyte in a charged state at a high temperature.

Example 17 This example shows an example in which a negative electrode mixture contains a compound of aluminum, nickel, or cobalt. A battery was prepared and evaluated in the same manner as in Example 2 except that the compounds shown in Table 17 were used instead of the hydroxide. Table 17 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test.

[0061]

[Table 17]

It has been found that even when a compound of aluminum, nickel or cobalt is added to the negative electrode, there is an effect of suppressing a decrease in capacity due to exposure of the battery to high temperatures.

Example 18 In this example, an example in which a compound of aluminum, nickel, or cobalt was added to the electrolyte was examined. 1 mol /
An equi-specific volume mixed solution of ethylene carbonate and dimethoxyethane in which 1 liter of lithium perchlorate was dissolved was used. This electrolyte was prepared by adding a compound shown in Table 18 to the electrolyte by 2 parts by weight per 100 parts by weight of the electrolyte. The compound to be added may or may not be dissolved in the electrolyte. A battery was prepared and evaluated in the same manner as in the comparative example except for the electrolyte. Table 18 shows the capacity retention rate and capacity recovery rate of each battery after the high-temperature durability test.

[0064]

[Table 18]

It has been found that when a compound of aluminum, nickel or cobalt is added to the electrolyte, there is also an effect of suppressing a decrease in capacity due to exposure of the battery to high temperatures.

Example 19 In this example, the addition ratio of a compound of aluminum, nickel or cobalt was examined. Aluminum oxide was used as a compound to be added to the positive electrode. A battery was fabricated in the same manner as in Example 16, except that the addition ratio of aluminum oxide to the positive electrode active material was changed. FIG. 8 shows the relationship between the addition ratio of aluminum oxide and the initial capacity and capacity retention of the battery. When the addition ratio of aluminum oxide exceeded 20 parts by weight per 100 parts by weight of the active material, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that, in addition to the decrease in the amount of the active material in the electrode, the conductivity between the active materials is inhibited. On the other hand, the capacity retention rate after heating showed a good value by adding 0.5 parts by weight or more per 100 parts by weight of the active material. From these results, the addition ratio was 0.5 to 20 per 100 parts by weight of the active material.
It turns out that the weight part is suitable. Although aluminum oxide was used here, similar results can be obtained when other compounds used in Example 16 were used.

Next, the ratio of addition to the negative electrode was examined. Nickel sulfate was used as the compound to be added. A battery was fabricated in the same manner as in Example 17, except that the addition ratio of nickel sulfate to the negative electrode active material was changed. Fig. 9 shows the relationship between the addition ratio of nickel sulfate and the initial capacity and capacity retention rate of the battery.
Shown in When the addition ratio of nickel sulfate exceeded 20 parts by weight per 100 parts by weight of the active material, the initial capacity of the battery sharply decreased. This is considered to be due to the fact that, in addition to the decrease in the amount of the active material in the electrode, the conductivity between the active materials is inhibited. On the other hand, the capacity retention rate after heating showed a good value by adding 0.5 parts by weight or more per 100 parts by weight of the active material. From these results, it is understood that the appropriate addition ratio is 0.5 to 20 parts by weight per 100 parts by weight of the active material. Here, nickel sulfate was used, but similar results can be obtained when other compounds used in Example 17 were used.

Next, the ratio of addition to the electrolyte was examined. Cobalt acetate was used as a compound to be added. Example 1 except that the addition ratio of cobalt acetate to the electrolyte was changed.
A battery was prepared in the same manner as in No. 8. FIG. 10 shows the relationship between the addition ratio of cobalt acetate and the initial capacity and capacity retention of the battery. When the addition ratio of cobalt acetate exceeded 30 parts by weight per 100 parts by weight of the electrolyte, the initial capacity sharply decreased.
On the other hand, the capacity retention rate after heating showed a good value by adding 0.5 parts by weight or more per 100 parts by weight of the electrolyte. From these results, the addition ratio was 0.1% per 100 parts by weight of the electrolyte.
It turns out that 5 to 30 parts by weight are suitable. Here, cobalt acetate was used, but similar results can be obtained by using other compounds used in Example 18.

In the above examples, specific materials were used for the positive electrode active material, the negative electrode active material, and the electrolyte. However, the present invention is not limited to these, and materials known to be used for this type of non-aqueous electrolyte secondary battery can be used. For example, negative electrode active materials include graphite analogs, aluminum and aluminum alloys, and positive electrode active materials include LiCoO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , and LiMnO ₂ .
Similar effects can be obtained by using a material capable of inserting and extracting lithium, such as FeO ₂ , MnO ₂ , and V ₂ O ₅ . Also, as for the electrolyte, an organic solvent such as ethylene carbonate, diethyl carbonate, methyl ethyl carbonate, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, γ-butyrolactone, dioxolane, dimethyl sulfoxide as a solvent, a lithium hexafluorophosphate as a solute, Lithium salts such as lithium tetrafluoroborate and lithium trifluoromethanesulfonate can be used. Further, the form of the battery is not limited to the cylindrical type, and the same effects can be obtained in coin type and square type batteries.

[0070]

As described above, according to the present invention, even when the battery is temporarily exposed to a high temperature, it is possible to obtain a nonaqueous electrolyte secondary battery with little subsequent characteristic deterioration.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a non-aqueous electrolyte secondary battery according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the proportion of cobalt hydroxide added to a positive electrode and the initial capacity and capacity retention of the battery.

FIG. 3 is a graph showing the relationship between the ratio of nickel hydroxide added to the negative electrode and the initial capacity and capacity retention of the battery.

FIG. 4 is a graph showing the relationship between the proportion of aluminum oxide hydrate added to the electrolyte and the initial capacity and capacity retention of the battery.

FIG. 5 is a graph showing the relationship between the proportion of cobalt carbonate added to the positive electrode and the initial capacity and capacity retention of the battery.

FIG. 6 is a diagram showing the relationship between the ratio of sodium hydrogen carbonate added to a negative electrode and the initial capacity and capacity retention of the battery.

FIG. 7 is a graph showing the relationship between the ratio of zinc carbonate added to the electrolyte and the initial capacity and capacity retention of the battery.

FIG. 8 is a graph showing the relationship between the ratio of aluminum oxide added to the positive electrode and the initial capacity and capacity retention of the battery.

FIG. 9 is a diagram showing the relationship between the proportion of nickel sulfate added to the negative electrode and the initial capacity and capacity retention of the battery.

FIG. 10 is a graph showing the relationship between the proportion of cobalt acetate added to the electrolyte and the initial capacity and capacity retention of the battery.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Toyoguchi ▲ Yoshitoku 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. In company

Claims (22)

[Claims] A chargeable / dischargeable positive electrode, a chargeable / dischargeable negative electrode,
And a non-aqueous electrolyte, wherein the inside of the battery contains a substance that generates water or carbon dioxide gas when the temperature rises. 2. The method according to claim 1, wherein a substance that generates water by increasing the temperature is contained in the positive electrode or the negative electrode, and the content thereof is 0.5 to 20 parts by weight per 100 parts by weight of the active material of the electrode. Non-aqueous electrolyte secondary battery. 3. The non-aqueous electrolyte according to claim 1, wherein the non-aqueous electrolyte contains a substance that generates water when the temperature rises, and the content thereof is 0.5 to 30 parts by weight per 100 parts by weight of the non-aqueous electrolyte. Electrolyte secondary battery. 4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the temperature at which water is generated from the substance that generates water by increasing the temperature is 60 ° C. to 300 ° C. 5. The non-aqueous electrolyte secondary battery according to claim 1, wherein the substance that generates water when the temperature rises is a hydroxide. 6. The hydroxide is zinc hydroxide, aluminum hydroxide, cadmium hydroxide, chromium hydroxide, cobalt hydroxide, nickel hydroxide, manganese hydroxide, calcium hydroxide, magnesium hydroxide, zirconium hydroxide. ,
The nonaqueous electrolyte secondary battery according to claim 5, wherein the secondary battery is at least one selected from the group consisting of iron oxide hydroxide and nickel oxide hydroxide. 7. The non-aqueous electrolyte secondary battery according to claim 1, wherein the substance that generates water when the temperature rises is boric acid. 8. The non-aqueous electrolyte secondary battery according to claim 1, wherein the substance that generates water when the temperature rises is a compound having water of crystallization. 9. The compound having water of crystallization includes aluminum oxide hydrate, barium nitrate hydrate, calcium sulfate hydrate, cobalt phosphate hydrate, antimony oxide hydrate, tin oxide hydrate, The nonaqueous electrolyte secondary battery according to claim 8, wherein the nonaqueous electrolyte secondary battery is at least one selected from the group consisting of titanium oxide hydrate, bismuth oxide hydrate, and tungsten oxide hydrate. 10. A substance which produces water when its temperature rises,
The non-aqueous electrolyte secondary battery according to claim 4, wherein a temperature at which water is generated is 60C to 150C. 11. The material according to claim 1, wherein the positive electrode or the negative electrode contains a substance that generates carbon dioxide gas due to a rise in temperature, and the content thereof is 0.5 to 25 parts by weight per 100 parts by weight of the active material of the electrode. Non-aqueous electrolyte secondary battery. 12. The non-aqueous electrolyte or the separator contains a substance that generates carbon dioxide gas when the temperature rises, and the content thereof is 0.5 to 30 parts by weight per 100 parts by weight of the non-aqueous electrolyte. Non-aqueous electrolyte secondary battery. 13. The substance for producing carbon dioxide gas, wherein the temperature for producing carbon dioxide gas is from 80 ° C. to 300 ° C.
The non-aqueous electrolyte secondary battery according to 1. 14. The non-aqueous electrolyte secondary battery according to claim 1, wherein the substance that generates carbon dioxide gas when the temperature rises is at least one selected from the group consisting of carbonates and hydrogen carbonates. 15. The group consisting of rubidium carbonate, barium carbonate, cobalt carbonate, iron carbonate, nickel carbonate, zinc carbonate, sodium bicarbonate, potassium bicarbonate, rubidium bicarbonate, and cesium bicarbonate. The non-aqueous electrolyte secondary battery according to claim 14, which is selected from the group consisting of: 16. The carbon dioxide-generating substance has a carbon dioxide-generating temperature of 80 ° C. to 150 ° C.
4. The non-aqueous electrolyte secondary battery according to 3. 17. A chargeable and dischargeable positive electrode, a chargeable and dischargeable negative electrode, and a nonaqueous electrolyte, wherein the positive electrode, the negative electrode, or the nonaqueous electrolyte is selected from the group consisting of an aluminum compound, a nickel compound, and a cobalt compound. A non-aqueous electrolyte secondary battery comprising at least one compound. 18. The method according to claim 18, wherein the compound is contained in a positive electrode or a negative electrode, and aluminum oxide, aluminum sulfate, aluminum phosphate, aluminum chloride, nickel oxide, nickel sulfate, nickel phosphate, nickel carbonate cobalt oxide, cobalt sulfate, cobalt phosphate 2. The composition of claim 1, wherein the compound is selected from the group consisting of, cobalt carbonate, and cobalt oxalate.
8. The non-aqueous electrolyte secondary battery according to 7. 19. The ratio of the compound contained in the positive electrode or the negative electrode is 0.5 to 100 parts by weight of the active material of the electrode.
The non-aqueous electrolyte secondary battery according to claim 18, wherein the amount is from 20 to 20 parts by weight. 20. The compound is contained in a non-aqueous electrolyte,
And aluminum oxide, aluminum sulfate, aluminum phosphate, aluminum chloride, aluminum acetate, aluminum oxalate, nickel oxide, nickel sulfate, nickel phosphate, nickel carbonate, nickel perchlorate, nickel nitrate, nickel acetate, cobalt oxide, cobalt sulfate ,
The non-aqueous electrolyte secondary battery according to claim 17, which is selected from the group consisting of cobalt phosphate, cobalt carbonate, cobalt oxalate, cobalt acetate, and cobalt perchlorate. 21. The content of the compound in the non-aqueous electrolyte is 0.5 to 100 parts by weight of the electrolyte.
The non-aqueous electrolyte secondary battery according to claim 20, which is 30 parts by weight. 22. A method for manufacturing a non-aqueous electrolyte secondary battery comprising a chargeable / dischargeable positive electrode, a chargeable / dischargeable negative electrode, a nonaqueous electrolyte, and a separator, wherein at least one surface of the positive electrode and the negative electrode has carbonic acid when the temperature rises. A method for producing a non-aqueous electrolyte secondary battery, comprising a step of applying or spraying a liquid in which a compound generating a gas is dissolved or dispersed to apply the compound.