JP3384632B2 - Non-aqueous electrolyte battery - 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, and particularly lithium or a lithium alloy as a negative electrode active material,
The present invention relates to a non-aqueous electrolyte battery having a practical voltage of about 1.5 V to 2.0 V, which uses cupric oxide, iron disulfide, bismuth trioxide, or the like as a positive electrode active material.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries having different practical voltages have been developed depending on the combination of a positive electrode material and a negative electrode material. The non-aqueous electrolyte battery has a practical voltage of about 3.0 V as a mainstream, but a non-aqueous electrolyte battery of about 1.5 V to 2.0 V has also been developed, and its practical value is compatible with a dry battery. high.

In a non-aqueous electrolyte battery, 1.5V-2.
In order to obtain a practical voltage of about 0 V, one using lithium or a lithium alloy as the negative electrode active material and using cupric oxide, iron disulfide, bismuth trioxide, etc. as the positive electrode active material has been put into practical use. As the water electrolyte, a solution obtained by dissolving an inorganic salt such as lithium perchlorate or lithium trifluoromethanesulfonate in an organic solvent such as propylene carbonate, ethylene carbonate or 1,2-dimethoxyethane is used.

By the way, the practical voltage is 1.5V to 2.0V.
In general, non-aqueous electrolyte batteries generally have an open circuit voltage higher than the practical voltage (around 3.0 V) due to the influence of water and impurities contained in the positive electrode and the non-aqueous electrolyte immediately after manufacturing. is doing. Therefore, the open circuit voltage is reduced to a practical voltage by performing preliminary discharge after manufacturing.

[0005]

The practical voltage is 1.
In a non-aqueous electrolyte battery of about 5 V to 2.0 V, there is a problem that the open circuit voltage rises again or the internal resistance rises even during long-term storage. It is considered that the increase in the open circuit voltage during the long-term storage is caused mainly by the intrusion of moisture or impurities from the outside, and a method of suppressing the increase in the open circuit voltage by removing the influence of moisture has been proposed.

For example, Japanese Unexamined Patent Publication No. 61-218070 describes a method of removing the influence of water and suppressing an increase in open circuit voltage by adding a magnesium salt or an indium salt to a non-aqueous electrolyte. There is. However, in such a method, sufficient effects have not been obtained in consideration of compatibility with dry batteries.

In view of the above problems, the present invention has a practical voltage of 1.
An object of the present invention is to provide a non-aqueous electrolyte battery capable of more effectively suppressing an increase in open circuit voltage and an increase in internal resistance during storage of a non-aqueous electrolyte battery of about 5 to 2.0 V than ever before. .

[0008]

In order to achieve the above object, the non-aqueous electrolyte battery according to claim 1 of the present invention comprises:
A non-aqueous electrolytic solution having a negative electrode containing lithium or a lithium alloy, a positive electrode containing a positive electrode active material, a separator separating the positive electrode and the negative electrode, and a non-aqueous electrolytic solution, and having a practical voltage of about 1.5V to 2.0V. The battery is characterized in that a phenol derivative or a hydroquinone derivative is added into the non-aqueous electrolyte battery.

Further, the non-aqueous electrolyte battery according to claim 2 is
In the non-aqueous electrolyte battery according to claim 1, the phenol derivative or the hydroquinone derivative is added to the positive electrode in an amount of 0.5 to 0.5.
It is characterized by being added at a concentration of 2.0% by weight and / or added at a concentration of 1 to 500 ppm with respect to the non-aqueous electrolyte. The non-aqueous electrolyte battery according to claim 3 is characterized in that, in the non-aqueous electrolyte battery according to claim 1, the positive electrode active material is cupric oxide, iron disulfide, or bismuth trioxide. I am trying.

The non-aqueous electrolyte battery according to claim 4 is
For the non-aqueous electrolyte battery according to claim 1, the hydroquinone derivative is selected from 2,5-di-tert-amylhydroquinone and 2,5-di-tert-butylhydroquinone, and the phenol derivative is 2,6. -Di-tert-
Butylphenol, 2,6-di-tert-butyl-4
-Characterized in that it is selected from methylphenol.

[0011]

The reason why the above structure can suppress the increase of the open circuit voltage is considered as follows. According to the non-aqueous electrolyte battery of claim 1, the water that has entered from the outside is
Before reacting with the positive electrode to generate an oxide, it reacts with the phenol derivative or hydroquinone derivative added in the non-aqueous electrolyte battery.

Therefore, it is possible to suppress the generation of oxides at the positive electrode due to the influence of moisture invading from the outside. The effect of suppressing the oxide formation suppresses an increase in open circuit voltage and an increase in internal resistance. Further, according to the non-aqueous electrolyte battery of claim 2, since the phenol derivative or the hydroquinone derivative is added to the positive electrode or the non-aqueous electrolyte at an appropriate concentration, the influence of water on the positive electrode is suppressed, and the open circuit is prevented. It has a great effect of suppressing an increase in voltage and an increase in internal resistance.

When added to the positive electrode, the effect of water on the positive electrode can be suppressed more directly than when added to the non-aqueous electrolyte, so that it is more effective. Further, in the non-aqueous electrolyte battery according to claim 3, the negative electrode active material is lithium or a lithium alloy, and the positive electrode active material is cupric oxide, iron disulfide, or bismuth trioxide. The open circuit voltage is about 1.5 V to 2.0 V depending on the combination of the active materials.

[0014]

EXAMPLES Examples of the present invention will be described in detail below. (Embodiment 1) FIG. 1 is a sectional view of a non-aqueous electrolyte battery according to an embodiment of the present invention. As shown in the figure, the non-aqueous electrolyte battery A is a coin-shaped battery having an outer diameter of 9.5 mm and a height of 2.7 mm, and a circular positive electrode 1 using cupric oxide as an active material, A negative electrode 2 made of a circular lithium plate, a separator 3 having a circular polypropylene microporous membrane impregnated with a non-aqueous electrolyte, a positive electrode current collector 4 and a negative electrode current collector made of a circular stainless net. Body 5, positive electrode outer can 6 made of a cylindrical stainless steel plate, and negative electrode outer can 7 made of a circular stainless plate covering the opening of positive electrode outer can 6.
And a ring-shaped polyolefin insulating packing 8 for insulating the positive electrode outer can 6 and the negative electrode outer can 7 from each other.

The outer periphery of the negative electrode outer can 7 enters the inside of the positive electrode outer can 6 through the opening of the positive electrode outer can 6, and the insulating packing 8 is interposed between the outer peripheral surface of the positive electrode outer can 6 and the outer surface of the positive electrode outer can 6. The positive electrode outer can 6 and the negative electrode can 7 are fixed while being insulated from each other. Then, the positive electrode 1, the negative electrode 2, the separator 3, the positive electrode current collector 4, and the negative electrode current collector 5 are housed in a space sealed by the positive electrode outer can 6, the negative electrode outer can 7, and the insulating packing 8.

The positive electrode 1 is in pressure contact with the inner bottom surface of the positive electrode outer can 6 via the positive electrode current collector 4, and the negative electrode 2 is in pressure contact with the inner bottom surface of the negative electrode outer can 7 via the negative electrode current collector 5. Is inserted between the positive electrode 1 and the negative electrode 2 in a crimped state.
The positive electrode 1 includes cupric oxide (84% by weight) as a positive electrode active material, graphite (10% by weight) as a conductive agent, fluororesin powder (5% by weight) as a binder, and 2. 5-di-
tert-Butylhydroquinone (Formula 1 below) (1% by weight) was mixed thoroughly and the mixture was mixed at about 2 t / cm.
By pressure molding at a pressure of 2, a cylindrical molded body having a diameter of 8 mm and a thickness of 0.4 mm is obtained.
It was heat-treated at 300 ° C.

[0017]

[Chemical 1]

The negative electrode 2 is formed by punching a rolled plate obtained by rolling lithium metal to a thickness of 0.6 mm into a circular shape having a diameter of 6 mm. As the non-aqueous electrolyte, a solution prepared by dissolving lithium perchlorate at a concentration of 1.0 mol / l in a mixed solvent of equal volume of propylene carbonate and 1,2-dimethoxyethane was used.

The non-aqueous electrolyte battery B has the same structure as the non-aqueous electrolyte battery A, but in the positive electrode 1, 2,5-
2,6 instead of di-tert-butylhydroquinone
-Di-tert-butyl-4-methylphenol (Formula 2 below) is added at a concentration of 1% by weight.

[0020]

[Chemical 2]

The non-aqueous electrolyte battery C has the same structure as the non-aqueous electrolyte battery A, except that the positive electrode 1 has 2,5-di-
Instead of tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone (Formula 3 below) is added at a concentration of 1% by weight.

[0022]

[Chemical 3]

(Comparative Example 1) The non-aqueous electrolyte battery X has the same structure as the non-aqueous electrolyte battery A, but in the positive electrode 1,
No 2,5-di-tert-butylhydroquinone was added, and the amount of cupric oxide mixed was 85% by weight. (Example 2) The non-aqueous electrolyte batteries A1 to A6 were the same as those in the non-aqueous electrolyte battery A of Example 1 except that the concentration of 2,5-di-tert-butylhydroquinone added to the positive electrode 1 was 0.1 to 3. .0
The concentration added to the positive electrode 1 was 0.1 wt% for A1, 0.25 wt% for A2, and A3 for A3.
Is 0.5% by weight, A4 is 1.5% by weight, A5 is 2.0% by weight, and A6 is 3.0% by weight. In the positive electrode 1, the amount of cupric oxide mixed corresponding to the increase (decrease) in the addition concentration of 2,5-di-tert-butylhydroquinone is decreased (increased).

(Example 3) Non-aqueous electrolyte battery D of this example
And E have the same configuration as the non-aqueous electrolyte battery A of Example 1, but in the positive electrode 1, 2,5-di-tert-butylhydroquinone is not added, and the mixed amount of cupric oxide is Is 85 wt%, but instead, 2,5-di-tert-amylhydroquinone (Chemical Formula 3) and 2,6-di-tert-butylphenol (Chemical Formula 4) in the non-aqueous electrolyte solution are 10 ppm. Is added at a concentration of.

[0025]

[Chemical 4]

(Comparative Example 2) Non-aqueous electrolyte batteries Y and Z
Has the same configuration as the non-aqueous electrolyte battery D, except that 2,5-di-tert-butylhydroquinone is added to the non-aqueous electrolyte at a concentration of 10 ppm instead of magnesium perchlorate and chloride. Indium is added at a concentration of 0.01 mol / liter. This concentration is considered to be preferable for adding magnesium perchlorate and indium chloride to the non-aqueous electrolyte.

(Embodiment 4) The non-aqueous electrolyte batteries D1 to D5 are
In the non-aqueous electrolyte battery D of Example 3, 2,5-di-t
The addition concentration of ert-amylhydroquinone to the non-aqueous electrolyte was varied over the range of 0.01 to 1000 ppm, and the addition concentration in each non-aqueous electrolyte battery was 0.01 ppm for D1 and 0 for D2. 1 ppm, D3 is 1 ppm, D4 is 100 ppm, D5 is 500 ppm, D
6 is 1000 ppm.

Table 1 shows the types and concentrations of the phenol derivative or hydroquinone derivative used in the nonaqueous electrolyte batteries of Examples 1 to 4 and Comparative Examples 1 and 2 described above.

[0029]

[Table 1]

The following experiment was conducted using such a non-aqueous electrolytic battery. (Experiment 1) With respect to the non-aqueous electrolyte batteries A and B and the non-aqueous electrolyte battery X, changes in open circuit voltage due to storage at room temperature were measured.
The open circuit voltage was measured every 30 days after assembling each non-aqueous electrolyte battery and pre-discharging 4% of the theoretical capacity, and the measurement period was 120 days. The measurement result is shown in the graph of FIG.

FIG. 2 is a graph showing the change in open circuit voltage of a non-aqueous electrolyte battery during storage at room temperature. In this graph, the open circuit voltage of the non-aqueous electrolyte battery X gradually increases, but that of the non-aqueous electrolyte batteries A and B hardly increases.
Therefore, adding an appropriate amount of 2,5-di-tert-butylhydroquinone or 2,6-di-tert-butyl-4-methylphenol to the positive electrode 1 is effective for suppressing the open circuit voltage during storage. It is recognized that there is.

In this case, 2,5-di-tert-
Although an example of adding butylhydroquinone and 2,6-di-tert-butyl-4-methylphenol to the positive electrode 1 has been shown, generally, the same effect can be obtained by adding a hydroquinone derivative or a phenol derivative to the positive electrode 1. It is supposed to occur. (Experiment 2) For the non-aqueous electrolyte batteries A, A1 to A6 and the non-aqueous electrolyte battery X, 4% of the theoretical capacity was pre-discharged after assembly, and then the initial open circuit voltage and the open circuit after storage at room temperature for 60 days The voltage was measured. Table 2 shows the measurement results.

[0033]

[Table 2]

From the results shown in Table 2, 2,5-di-t
The addition concentration of ert-butylhydroquinone is 0.5% by weight.
For the above, there is almost no increase in open circuit voltage after storage for 60 days. Therefore, it is understood that when the concentration of 2,5-di-tert-butylhydroquinone added to the positive electrode 1 is 0.5% by weight or more, it is sufficiently effective in suppressing the increase in open circuit voltage.

Further, the concentration of 2,5-di-tert-butylhydroquinone added to the positive electrode 1 is in the range of 0 to 3.5% by weight, that is, the nonaqueous electrolyte battery A (1). ．
0% by weight), A3 (0.5% by weight), A5 (2.0% by weight) and non-aqueous electrolyte battery X (0% by weight), and addition concentrations of 2.5% by weight and 3.5% by weight. %, The internal resistance value of the non-aqueous electrolyte battery after storage at 60 ° C. for 20 days was measured. The measurement result is as shown in FIG. The initial value of the internal resistance value was about 50Ω.

FIG. 3 shows that 2,5-di-tert-
3 is a graph showing the relationship between the concentration of butylhydroquinone added and the internal resistance value after storage at 60 ° C. for 20 days. As shown in the figure, when the addition concentration of 2,5-di-tert-butylhydroquinone is in the range of 0.5 to 2.0% by weight, the internal resistance value is about 50Ω, which is almost the same as the initial value. In the range where the added concentration is lower than 0.5% by weight or higher than 2.0% by weight, the internal resistance value is higher. this is,
It is considered that when the concentration of 2,5-di-tert-butylhydroquinone added to the positive electrode 1 is in the range of 0.5 to 2.0% by weight, the effect of removing the influence of water on the positive electrode 1 is large.

From the above results, 2,5-di-tert-
The concentration of butylhydroquinone added to the positive electrode 1 is
It can be seen that the range of 0.5 to 2.0% by weight is preferable.
Here, an example in which 2,5-di-tert-butylhydroquinone is added to the positive electrode 1 is shown, but generally, the concentration of the hydroquinone derivative or the phenol derivative added to the positive electrode 1 is 0.5. It is estimated that a range of up to 2.0% by weight is suitable.

(Experiment 3) With respect to the non-aqueous electrolyte batteries D and E and the non-aqueous electrolyte battery X, the change in open circuit voltage due to storage at room temperature was measured as in Experiment 1. FIG. 4 is a graph showing the measurement result. As a result, the open circuit voltage of the non-aqueous electrolyte battery X gradually increases, but the non-aqueous electrolyte batteries D and E
Has hardly risen.

Therefore, adding an appropriate amount of 2,5-di-tert-amylhydroquinone or 2,6-di-tert-butylphenol to the non-aqueous electrolyte is sufficiently effective in suppressing the open circuit voltage during storage. It is recognized that In addition, although the case where 2,5-di-tert-amylhydroquinone and 2,6-di-tert-butylphenol are added to the non-aqueous electrolyte is shown here,
Generally, it is presumed that the same effect will be produced by adding an appropriate amount of the hydroquinone derivative or the phenol derivative to the non-aqueous electrolyte.

(Experiment 4) For the non-aqueous electrolyte batteries D, D1 to D6 and the non-aqueous electrolyte battery X, 4% of the theoretical capacity was pre-discharged after assembly, and then the initial open circuit voltage and room temperature 60
The open circuit voltage after storage for a day was measured. Table 3 shows the measurement results.

[0041]

[Table 3]

From the results shown in Table 3, 2,5-di-t
Regarding the addition concentration of ert-amylhydroquinone of 1 ppm or more, there is almost no increase in open circuit voltage after storage for 60 days. Therefore, it can be seen that when the concentration of 2,5-di-tert-amylhydroquinone added to the non-aqueous electrolyte is 1 ppm or more, it is sufficiently effective in suppressing the increase in open circuit voltage.

The concentration of 2,5-di-tert-amylhydroquinone added to the non-aqueous electrolyte is 0 to 1000 p.
Non-aqueous electrolyte battery in the range of pm, that is, non-aqueous electrolyte battery D
5 (500ppm), non-aqueous electrolyte battery D6 (1000pp
m), non-aqueous electrolyte battery X (0 ppm), concentration of 40
The discharge capacities of the 0 ppm and 600 ppm non-aqueous electrolyte batteries were measured.

The discharge capacity was measured at 20 ° C. with a discharge current of 0.04 mA until the battery voltage reached 1.2 V, and the discharge amount at that time was measured and used as the discharge capacity. FIG. 5 is a graph showing the relationship between the 2,5-di-tert-amylhydroquinone concentration in the non-aqueous electrolyte and the discharge capacity. As shown in FIG. 5, 2,5-di-tert-
The discharge capacity is almost constant up to the addition concentration of amylhydroquinone of about 0 to 500 ppm, but when it exceeds 500 ppm, the discharge capacity decreases.

Therefore, the concentration of 2,5-di-tert-amylhydroquinone added to the non-aqueous electrolyte is 1 to 5
The range of 00 ppm is considered appropriate. In addition, here, an example in which 2,5-di-tert-amylhydroquinone is added to the non-aqueous electrolytic solution is shown, but generally, the concentration of the hydroquinone derivative or the phenol derivative added to the non-aqueous electrolytic solution is , 1 to 500 ppm is considered to be appropriate.

(Experiment 5) With respect to the non-aqueous electrolyte battery C, the non-aqueous electrolyte battery D and the non-aqueous electrolyte battery X, changes in internal resistance due to storage at 60 ° C. were measured. The measurement was performed every 20 days, and the measurement period was 60 days. FIG. 6 is a graph showing changes in internal resistance of a non-aqueous electrolyte battery during storage at 60 ° C. As shown in the figure, the change in internal resistance due to room temperature storage increases in the order of non-aqueous electrolyte battery C, non-aqueous electrolyte battery D, and non-aqueous electrolyte battery X.

Therefore, addition of an appropriate amount of 2,5-di-tert-amylhydroquinone to the positive electrode 1 or the nonaqueous electrolytic solution is effective in preventing an increase in internal resistance, but the nonaqueous electrolytic solution is not effective. It can be seen that adding an appropriate amount to the positive electrode 1 is more effective than adding an appropriate amount to the liquid. This is 2,
By adding 5-di-tert-amylhydroquinone to the positive electrode 1, the positive electrode 1 can be used rather than being added to the non-aqueous electrolyte.
It is considered that the influence of water on the can be suppressed more effectively.

Although an example in which 2,5-di-tert-amylhydroquinone is added has been shown here, in general, if a hydroquinone derivative or a phenol derivative is added to the positive electrode 1 or the nonaqueous electrolytic solution in an appropriate amount. It is expected that similar results will be obtained. (Experiment 6) Non-aqueous electrolyte battery D and non-aqueous electrolyte batteries Y and Z
With respect to and, the change in open circuit voltage due to storage at 60 ° C was measured. To measure the open circuit voltage, assemble each non-aqueous electrolyte battery,
After pre-discharging 4% of theoretical capacity, every 20 days,
The measurement period was 100 days. The measurement result is shown in the graph of FIG. 7.

FIG. 7 is a graph showing changes in open circuit voltage of a non-aqueous electrolyte battery when stored at 60 ° C. In this graph, in the non-aqueous electrolyte batteries Y and Z, the open circuit voltage exceeds 2.0 V after a storage period of about 20 days, whereas in the non-aqueous electrolyte battery D, the open circuit voltage exceeds about 2.0 V in 100 days. Reached and the increase in open circuit voltage is smaller. Therefore, 2,5-di-te
Adding an appropriate amount of rt-amylhydroquinone to the non-aqueous electrolyte is more effective in suppressing the open-circuit voltage during storage than adding an appropriate amount of magnesium perchlorate or indium chloride to the non-aqueous electrolyte. Is recognized.

Here, an example in which a non-aqueous electrolyte solution added with 2,5-di-tert-amylhydroquinone is compared with a non-aqueous electrolyte solution added with magnesium perchlorate or indium chloride is shown. Therefore, it is speculated that when an appropriate amount of hydroquinone derivative or phenol derivative is added to the non-aqueous electrolyte, the open circuit voltage can be suppressed more effectively than when an appropriate amount of magnesium salt or indium salt is added to the non-aqueous electrolyte. To be done.

In the above Examples 1 to 4, cupric oxide was used as the active material of the positive electrode 1, but the same applies when iron disulfide or bismuth trioxide is used as the active material. It is possible to carry out, and the same effect is produced.

[0052]

According to the present invention described above, the practical voltage is 1.
In a non-aqueous electrolyte battery of about 5 V to 2.0 V, by adding a hydroquinone derivative or a phenol derivative, an increase in open circuit voltage and an increase in internal resistance during storage are suppressed more effectively than conventional methods. Is possible,
Its practical value is great.

Further, by adding an appropriate amount of hydroquinone derivative or phenol derivative to the positive electrode, it is possible to more effectively suppress an increase in open circuit voltage and an increase in internal resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a non-aqueous electrolyte battery according to an example of the present invention.

FIG. 2 is a graph showing changes in open circuit voltage of a non-aqueous electrolyte battery during storage at room temperature.

FIG. 3 is a graph showing the relationship between the concentration of 2,5-di-tert-butylhydroquinone added to the positive electrode and the internal resistance value after storage at 60 ° C. for 20 days.

FIG. 4 is a graph showing changes in open circuit voltage of a non-aqueous electrolyte battery during storage at room temperature.

FIG. 5 is a graph showing the relationship between the concentration of 2,5-di-tert-amylhydroquinone in the non-aqueous electrolyte solution and the discharge capacity.

FIG. 6 is a graph showing changes in internal resistance of a non-aqueous electrolyte battery during storage at 60 ° C.

FIG. 7 is a graph showing changes in open circuit voltage of a non-aqueous electrolyte battery during storage at 60 ° C.

[Explanation of symbols]

1 positive electrode 2 Negative electrode 3 separator 6 Positive electrode can 7 Negative electrode exterior can

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-137669 (JP, A) JP-A-52-93924 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 6/16 H01M 4/06 H01M 4/58

Claims (4)

(57) [Claims] 1. A negative electrode containing lithium or a lithium alloy, a positive electrode containing a positive electrode active material, a separator for separating the positive electrode and the negative electrode, and a non-aqueous electrolyte, and a practical voltage of 1.5 V.
A non-aqueous electrolyte battery of approximately 2.0 V, wherein a phenol derivative or a hydroquinone derivative is added to the non-aqueous electrolyte battery. 2. The phenol derivative or hydroquinone derivative is added at a concentration of 0.5 to 2.0% by weight to the positive electrode, and / or 1 to the non-aqueous electrolyte.
The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery is added at a concentration of 500 ppm. 3. The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode active material is cupric oxide, iron disulfide or bismuth trioxide. 4. The hydroquinone derivative is 2,5-di-tert-amylhydroquinone, 2,5-di-ter.
selected from t-butylhydroquinone, wherein the phenol derivative is 2,6-di-tert-butylphenol,
The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery is selected from 2,6-di-tert-butyl-4-methylphenol.