JP3475488B2 - Non-aqueous electrolyte battery and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery which can be reused by charging and a manufacturing method thereof.

[0002]

2. Description of the Related Art With the background of energy and environmental problems, there is a need for a technique for more effectively utilizing electric power. For the above purposes, a good means of storing electricity is needed,
In this case, it is optimal to use a high performance storage battery as the storage means. A high-performance storage battery means that a lighter battery and a battery with a smaller volume have a larger capacity.

On the other hand, conventionally, a non-aqueous electrolyte battery using a positive electrode and a negative electrode capable of occluding lithium etc. has been utilized as a power source for small electronic devices and the like. The non-aqueous electrolyte battery has advantages that it can be easily miniaturized and has high energy density. Therefore, the non-aqueous electrolyte battery that is made into a secondary battery is optimal as the above-mentioned high-performance storage battery.

[0004]

However, the above non-aqueous electrolyte battery has the following problems. That is, in the above non-aqueous electrolyte battery, by repeating charging and discharging, lithium metal and compound dendrites are deposited on the surface of the negative electrode. With the deposition of the lithium metal and compound, the electrical properties of the negative electrode surface change, and the cycle characteristics of the non-aqueous electrolyte battery deteriorate. Also, the lithium metal and the compound grow largely on the surface of the negative electrode with the lapse of time, and finally penetrate the separator to short-circuit between the positive electrode and the negative electrode. The non-aqueous electrolyte battery becomes unusable due to the occurrence of the short circuit. It also poses a problem in terms of safety. Therefore, the non-aqueous electrolyte battery has a relatively short life.

The non-aqueous electrolyte battery uses lithium. Since lithium easily reacts with water, it is conventionally said that it is necessary to completely prevent moisture from adhering to each component before assembling a non-aqueous electrolyte battery. For this reason, it is necessary to provide a drying step in manufacturing each part and to assemble the above parts in a dry box or the like. Therefore, the manufacturing cost of the non-aqueous electrolyte battery is high. In view of such problems, the present invention aims to provide a non-aqueous electrolyte battery having excellent cycle characteristics, low cost, and long life, and a method for manufacturing the same.

[0006]

The present invention is directed to a positive electrode capable of occluding and releasing lithium, a negative electrode comprising at least one of a lithium metal, a lithium alloy, a substance capable of occluding and releasing lithium, or a conductor, a separator, and a non-aqueous electrolyte. And a non-aqueous electrolyte battery having a battery container, wherein the non-aqueous electrolyte is
A non-aqueous electrolyte battery is characterized by containing hydrogen fluoride having a lower limit of 1200 and an upper limit of 2000 ppm .

Next, as the negative electrode of the non-aqueous electrolyte battery, lithium metal, Li-Al, Li-Zn and Li-P are used.
It is preferable to use a lithium alloy such as d, Li-Sn, carbon, a substance capable of inserting and extracting lithium such as polyacene, or a conductor such as nickel, stainless steel, or titanium. Next, regarding the inclusion of the above-mentioned hydrogen fluoride, as will be described later, a method of containing a substance that produces hydrogen fluoride by decomposition in the non-aqueous electrolyte solution, and adding hydrogen fluoride to the electrolyte solution in advance. There are ways.

Next, the content of hydrogen fluoride is 3100.
If it is more than ppm, hydrogen fluoride may decompose the positive electrode, the non-aqueous electrolyte solution and the like. Therefore, the life of the non-aqueous electrolyte battery is shortened. Next, the non-aqueous electrolyte solution preferably contains 10 ppm or more of hydrogen fluoride. If the hydrogen fluoride content is less than 10 ppm, a lithium fluoride film may not be formed on the negative electrode. The content of hydrogen fluoride is more preferably 500 ppm for the lower limit and 2600 p for the upper limit.
pm. More preferably, the lower limit is 1200 ppm,
The upper limit is 2000 ppm.

Next, the non-aqueous electrolytic solution preferably contains a supporting electrolyte which produces hydrogen fluoride by decomposition. Examples of the supporting electrolyte include LiPF ₆ , L
iBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF
₃ CO ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃
One or two or more of SO ₂ ) ₃ are used. The supporting electrolyte reacts with water to produce hydrogen fluoride. For this reason,
The non-aqueous electrolyte battery of the present invention does not have to have water removed as strictly as the conventional product. Rather, as will be described later, it is preferable to contain a certain amount of water. In addition, since the conductivity of the non-aqueous electrolyte does not decrease and the reactivity with water is excellent, LiPF ₆ , LiBF ₄ , Li
It is particularly preferable to use AsF ₆ , LiCF ₃ SO ₃ as the supporting electrolyte.

Other supporting electrolytes include, for example, L
iClO ₄ , Li ₂ B ₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl ₁₂ , L
iBPh ₄ and LiAlCl ₄ are used. Although they do not generate hydrogen fluoride, they can be used because they have excellent conductivity and have low reactivity with hydrogen fluoride and are stable even if hydrogen fluoride is present inside the battery. .

[0011] Next, the method of manufacturing a non-aqueous electrolyte batteries, absorbs lithium, a positive electrode capable of emitting, and lithium metal, lithium alloys, lithium absorption, negative electrode comprising at least one release can substance or conductors, In manufacturing a non-aqueous electrolyte battery having a separator, a non-aqueous electrolyte containing a supporting electrolyte that produces hydrogen fluoride by decomposition, and a battery container, water is added to the battery, and then the battery is assembled. Is preferably performed.

When assembling the above-mentioned battery, it is preferable to add water corresponding to 1400 ppm or less to the non-aqueous electrolyte, and then to assemble the battery. If it is higher than 1400 ppm, water may react with lithium of both electrodes to shorten the life of the battery. Next, it is preferable that the addition of the water content be 5 ppm or more. If the water content is less than 5 ppm, the amount of hydrogen fluoride produced may be small.

Next, the water may be added by any method or means as long as the water content of the non-aqueous electrolyte solution is within the above range. For example, there is a method of simplifying the drying of each battery component as compared with the conventional method. As a result, the water attached to each component naturally mixes into the non-aqueous electrolyte due to the battery assembly. In this case, the drying of each component in the battery manufacturing process can be simplified more than ever before. Therefore, the manufacturing cost can be reduced.

As a method different from the above, in advance,
It is also possible to add water of 1400 ppm or less to the above non-aqueous electrolyte and then assemble the battery. On the other hand, 5
It is also possible to add water of ppm or more and then assemble the battery. In these cases, it is possible to efficiently obtain hydrogen fluoride, and to obtain an electrolytic solution containing optimum water in which reaction with lithium hardly occurs. Therefore, a non-aqueous electrolyte battery having a long life can be obtained.

Next, as a supporting electrolyte for producing hydrogen fluoride by the above decomposition, for example, LiPF ₆ , LiB
F ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ C
O ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO
₂ ) Use one or more selected from the group of ₃ . As a result, the same effect as described above can be obtained.

Next, as the manufacturing method of the present invention, a positive electrode capable of absorbing and desorbing lithium, a negative electrode comprising at least one of lithium metal, lithium alloy, a substance capable of absorbing and desorbing lithium or a conductor, and a separator. In producing a non-aqueous electrolyte battery having a non-aqueous electrolyte solution containing a supporting electrolyte that generates hydrogen fluoride by decomposition and a battery container, the lower limit of the non-aqueous electrolyte solution is 1200 ppm or more in advance.
Limit is added hydrogen fluoride below 2000 ppm, there is a method of manufacturing a nonaqueous electrolyte battery, characterized in that subsequently perform the assembly of the battery.

In the inside of the battery, 1 for the non-aqueous electrolyte.
It is preferable to add hydrogen fluoride corresponding to 0 ppm or more. In this case, a desired amount of hydrogen fluoride is added to the inside of the battery so that it is naturally mixed into the non-aqueous electrolyte. As a result, hydrogen fluoride can be added in the required amount, so there is no risk that hydrogen fluoride will decompose the positive electrode, the non-aqueous electrolyte, and the like.

Further, as a manufacturing method different from the above,
A positive electrode capable of occluding and releasing lithium, a negative electrode comprising at least one of lithium metal, a lithium alloy, a substance capable of occluding and releasing lithium or a conductor, and a separator,
In producing a non-aqueous electrolyte battery having a non-aqueous electrolyte containing a supporting electrolyte that produces hydrogen fluoride by decomposition and a battery container, hydrogen fluoride of 3100 ppm or less is added to the non-aqueous electrolyte in advance. There is a method for manufacturing a non-aqueous electrolyte battery, which is characterized by assembling the battery after that.

It is preferable to add 10 ppm or more of hydrogen fluoride to the non-aqueous electrolyte in advance. In this case, hydrogen fluoride is directly added to the non-aqueous electrolyte in a desired amount. As a result, similarly to the above-described manufacturing method, there is no risk of decomposition of the positive electrode, the electrolytic solution and the like due to hydrogen fluoride.

[0020]

[Operation and effect] In the non-aqueous electrolyte battery of the present invention,
The non-aqueous electrolyte has a lower limit of 1200 ppm and an upper limit of 200.
It contains 0 ppm hydrogen fluoride.

The hydrogen fluoride reacts with the lithium metal and the compound on the surface of the negative electrode, and instead forms a LiF film. Therefore, formation of lithium metal and compound is suppressed. Further, the content of hydrogen fluoride is within the above specified range. Therefore, there is no possibility that hydrogen fluoride will decompose the positive electrode, the nonaqueous electrolytic solution, or the like. Therefore, a battery having excellent cycle characteristics and a long life can be obtained.

The hydrogen fluoride is generated by the reaction between the supporting electrolyte and a small amount of water as described above. Therefore, in the present invention, a small amount of water may remain in the battery before the battery is assembled. Therefore, unlike the conventional method, equipment for completely removing water is not required. Therefore, the battery is easy to assemble and the cost is low.
Further, according to the above manufacturing method, the excellent non-aqueous electrolyte battery as described above can be obtained. As described above, according to the present invention, it has excellent cycle characteristics, low cost, and
A non-aqueous electrolyte battery having a long life and a method for manufacturing the same can be provided.

[0023]

【Example】

Example 1 A non-aqueous electrolyte battery according to an example of the present invention will be described with reference to FIG. As shown in FIG. 1, the non-aqueous electrolyte battery 1 of this example includes a positive electrode 11, a negative electrode 12, and a separator 13.
And a non-aqueous electrolyte solution 14 and a button type battery container 15. The non-aqueous electrolyte solution 14 contains hydrogen fluoride. The non-aqueous electrolyte solution 14 is impregnated in the separator 13.

As the positive electrode 11, the active material is Li
Mn ₂ O ₄ , Ketjen black as a conductor, and PTFE (polytetrafluoroethylene) as an adhesive are used, and these are molded into a desired shape by pressing. Metallic lithium is used as the negative electrode 12.
Next, as the non-aqueous electrolyte solution 14, a solution obtained by adding LiPF ₆ at a concentration of 1 mol / liter to a mixed solution of propylene carbonate and dimethoxyethane mixed in equal volumes by volume is used. Further, 800 ppm of water is added to the non-aqueous electrolyte solution 14.

The separator 13 is made of a polypropylene porous film and is impregnated with the non-aqueous electrolyte 14 in advance. In addition, the positive electrode side current collector 110
Is an aluminum plate, and the negative electrode side current collector 120 is a copper plate. The battery container 15 comprises a positive electrode can and a negative electrode can, and a polypropylene gasket 16 for fixing the both. Both the positive electrode can and the negative electrode can are made of stainless steel (SUS30
4).

Next, the function and effect of this example will be described. In the non-aqueous electrolyte battery of this example, the non-aqueous electrolyte contains a specific amount of LiPF ₆ . The LiPF ₆ produces hydrogen fluoride by the reaction of the following chemical formula 1 in a non-aqueous electrolyte solution to which water is added.

[0027]

[Chemical 1]

The above hydrogen fluoride reacts with the lithium metal and the compound on the surface of the negative electrode, and instead forms a LiF film. By depositing or occluding lithium ions on the surface of the negative electrode through the LiF coating, the deposition of lithium metal and compound is suppressed. Further, the content of hydrogen fluoride is within the above specified range. Therefore, there is no possibility that hydrogen fluoride will decompose the positive electrode, the non-aqueous electrolyte, and the like. Therefore, a battery having excellent cycle characteristics and a long life can be obtained.

As described above, the LiPF ₆ decomposes water and produces hydrogen fluoride. Therefore,
In the non-aqueous electrolyte battery of this example, water may be present inside the battery. Therefore, the manufacturing process can be simplified and the manufacturing cost can be reduced.

Example 2 In this example, the same non-aqueous electrolyte battery as in Example 1 was used to compare and explain the relationship between the type of supporting electrolyte and the cycle characteristics in the non-aqueous electrolyte. First, the cycle characteristics are measured under the following conditions. That is, a constant current with a current density of ² mA / cm ² and a voltage of 4.1 V was charged for 5 hours at a constant voltage, and then a current density of ² mA / cm ² and a voltage of 2.
The above cycle is continuously repeated with a constant current discharge of up to 0 V as one cycle. And the battery capacity is 7
The experiment is terminated when it falls below 0%. The cycle characteristics are evaluated depending on how many times the above cycle can be repeated until the end.

Next, a non-aqueous electrolyte battery in which the supporting electrolyte LiPF ₆ which produces hydrogen fluoride by decomposition is contained in the non-aqueous electrolyte under the same conditions as in Example 1 is used.
In addition, the supporting electrolyte LiClO _{4 which} does not generate hydrogen fluoride
A non-aqueous electrolyte battery in which is contained in a non-aqueous electrolyte is used.

Next, the measurement results will be described. That is, the cycle characteristics of the non-aqueous electrolyte battery using LiPF ₆ as the supporting electrolyte were 59 cycles, while those using LiClO ₄ were 50 cycles. The amount of hydrogen fluoride in the electrolytic solution was 170 pp when LiPF ₆ was used.
m, LiClO ₄ was 0. This shows that the supporting electrolyte LiPF ₆ produces hydrogen fluoride in the electrolytic solution and improves the cycle characteristics of the non-aqueous electrolytic solution battery.

Example 3 In this example, the same non-aqueous electrolyte battery as in Example 1 was used to compare and explain the relationship between the presence or absence of water and the cycle characteristics in the non-aqueous electrolyte. The cycle characteristics are measured under the same conditions as in Example 2.

Next, as a sample containing water,
A non-aqueous electrolyte battery in which 400 ppm of water is added to the non-aqueous electrolyte is used. A non-aqueous electrolyte battery containing no water is used as the sample containing no water.
The above sample uses a non-aqueous electrolyte battery in which the amount of water brought in from other than the electrolyte is 10 ppm or less as measured by the Karl Fischer method.

Next, the measurement results will be described. That is, the cycle characteristics of the non-aqueous electrolyte battery containing water is 7
The number of cycles was 4 cycles, while the number of cycles of the non-aqueous electrolyte battery without addition of water was 59 cycles. The amount of hydrogen fluoride in the electrolytic solution is 86 in a non-aqueous electrolytic battery containing water.
It was 0 ppm and 170 ppm in a non-aqueous electrolyte battery containing no added water. From this, it can be seen that hydrogen fluoride is produced more by adding water.

Example 4 In this example, in the non-aqueous electrolyte battery shown in Example 1, the relationship between the amount of water added in the electrolyte and the cycle characteristics was
This will be described with reference to the diagram shown in FIG. That is, in the figure, the horizontal axis is the water content, and the vertical axis is the number of cycles by the above-mentioned measurement method. Further, the range indicated by the symbol a is the water content according to the present invention. The addition of the above-mentioned water content is performed by adding a desired amount of water to the non-aqueous electrolytic solution, as in the third embodiment.

From the figure, the added water content is 800 ppm.
If the amount is below, the cycle characteristics improve as the amount of water added increases, as compared with the case where no water is added. However, 8
If more than 00 ppm is added, the cycle characteristics will gradually deteriorate, and if more than 1400 ppm is added, the cycle characteristics will be worse than if no water was added. Therefore, 1400 pp which is within the range according to the present invention
It can be seen that a non-aqueous electrolyte battery having excellent cycle characteristics can be obtained by adding a water content of m or less. Further, it can be seen that the addition of 5 ppm or more of water can clearly improve the cycle characteristics as compared with the case where no water is added.

Example 5 This example will be described with reference to the diagram shown in FIG. 3 regarding the relationship between the amount of hydrogen fluoride in the non-aqueous electrolyte and the cycle characteristics. That is, in the figure, the horizontal axis represents the amount of hydrogen fluoride, and the vertical axis represents the number of cycles by the above-mentioned measurement method. The range indicated by the symbol b is the amount of hydrogen fluoride according to the present invention. In this example, the same non-aqueous electrolyte battery as in Example 1 was used,
The amount of hydrogen fluoride produced by adding water, not the amount of water, was measured and plotted on a diagram for the relationship with cycle characteristics.

From the figure, the amount of hydrogen fluoride is 1600 ppm.
If the following, compared to the case without hydrogen fluoride,
The cycle amount is improved as the amount of hydrogen fluoride is increased. However, if it exceeds 1600 ppm, the cycle characteristics gradually deteriorate. And, when the content exceeds 3100 ppm, the cycle characteristics become worse than in the case where hydrogen fluoride does not exist. Therefore, by containing hydrogen fluoride within the range according to the present invention, a non-aqueous electrolyte battery having excellent cycle characteristics can be obtained. Further, it can be seen that when the amount of hydrogen fluoride is 10 ppm or more, the cycle characteristics are clearly improved as compared with the case where hydrogen fluoride does not exist.

Further, in this example, as described in Example 1, hydrogen fluoride is produced by adding water to the non-aqueous electrolytic solution containing the supporting electrolyte. However, the same effect as this example can be obtained by generating or adding hydrogen fluoride in the non-aqueous electrolyte by other means.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a non-aqueous electrolyte battery in Example 1.

FIG. 2 is a diagram showing the relationship between water content and cycle characteristics in Example 4.

FIG. 3 is a diagram showing the relationship between the amount of hydrogen fluoride and cycle characteristics in Example 5.

[Explanation of symbols]

1. ． ． Non-aqueous electrolyte battery, 11. ． ． Positive electrode, 12. ． ． Negative electrode, 13. ． ． separator, 14. ． ． Non-aqueous electrolyte, 15. ． ． Battery container,

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/40

Claims (5)

(57) [Claims] 1. A positive electrode capable of occluding and releasing lithium, a negative electrode comprising at least one of a lithium metal, a lithium alloy, a substance capable of occluding and releasing lithium, or a conductor, a separator, a non-aqueous electrolytic solution, and a battery container. In the non-aqueous electrolyte battery having the above, the non-aqueous electrolyte has a lower limit of 1200 ppm and an upper limit of 200.
A non-aqueous electrolyte battery containing 0 ppm of hydrogen fluoride. 2. The non-aqueous electrolyte according to claim 1,
A non-aqueous electrolyte battery comprising a supporting electrolyte that produces hydrogen fluoride by decomposition. 3. The supporting electrolyte according to claim 2, wherein the supporting electrolyte is L.
_{iPF 6, LiBF 4, LiAsF 6} , LiCF 3 SO
₃ , LiCF ₃ CO ₂ , LiN (CF ₃ SO ₂ ) ₂ , L
A non-aqueous electrolyte battery comprising one or more selected from the group of iC (CF ₃ SO ₂ ) ₃ . 4. Oite to claim 1, said non-aqueous electrolyte,
It contains a supporting electrolyte that does not generate hydrogen fluoride by decomposition, and the supporting electrolyte is LiClO ₄ , Li ₂ B
₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl ₁₂ , LiBPh ₄ ,
A non-aqueous electrolyte battery comprising one or more selected from the group consisting of LiAlCl ₄ . 5. A positive electrode capable of occluding and releasing lithium, a negative electrode comprising at least one of a lithium metal, a lithium alloy, a substance capable of occluding and releasing lithium, or a conductor, a separator, and a support for generating hydrogen fluoride by decomposition. When manufacturing a non-aqueous electrolyte battery having a non-aqueous electrolyte solution containing an electrolyte and a battery container, the non-aqueous electrolyte solution has a lower limit of 1200 ppm or more and an upper limit of
A method for producing a non-aqueous electrolyte battery, which comprises adding hydrogen fluoride of 2000 ppm or less and then assembling the battery.