JP4499607B2 - Positive electrode for ultra-thin manganese battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to an ultra-thin manganese battery, and relates to a positive electrode for an ultra-thin manganese battery having excellent high rate characteristics and realizing a high energy density, and a method for manufacturing the same.

  In recent years, with the rapid development of electronic, communication, and computer industries, new technologies using radio wave technology such as electronic tags using radio frequency identification devices have appeared. Therefore, in addition to the existing standard shape, various shapes of batteries are required.

  Furthermore, in the fields of beauty and medicine, new technologies such as so-called iontophoresis (Iontophoresis) for effectively penetrating target substances into the skin are attracting attention. There is an urgent need for high-performance thin batteries that can be made thinner.

  Currently, batteries that meet these requirements are being developed, and as a battery that meets these needs, much attention and attention have been paid to ultra thin batteries, which are called paper batteries or sheet batteries. Gathered.

  An ultra-thin battery is a sheet-like thin battery, and is composed of an electrolyte, a positive electrode, a negative electrode, and a separator as essential basic elements as in a normal battery. Then, using a sheet-like solid electrolyte instead of the liquid electrolyte, and applying a flexible collector and electrode and a polymer packaging material, a flexible ultra-thin battery is produced. Can do.

Furthermore, in order to produce the ultrathin battery as described above, a gel electrolyte is required.
However, although this gel electrolyte is advantageous in terms of liquid leakage and electrolyte depletion, the low conductivity causes a decrease in capacity and output during high rate discharge, and an extremely restrictive environment. It is used only for specific applications because it only works.

  In addition to the ultra-thin characteristics, the battery is required to have excellent performance storage characteristics and leakage resistance in addition to being extremely thin and soft. In addition, a polymer sheet that is vulnerable to impacts is mainly used as an exterior material, so that the sealing between the inside of the battery and the atmosphere should be secured, and separation of the electrode plate due to the generation of internal gas should be avoided. Characteristics are required.

  Many specific technologies related to ultra-thin batteries are disclosed in patents or prior documents of utility models. A technique relating to a thin battery covered with a double insulating film is disclosed as an initial one (see, for example, Patent Document 1). Moreover, the technique regarding the thin battery produced by adding a water-soluble polymer thickener to electrolyte is disclosed (for example, refer patent document 2).

  However, most of these prior art batteries are still inferior in high rate performance. In addition, since the technology for effectively controlling hydrogen gas generated during charging or discharging is not supported, in the case of an ultra-thin battery without a mechanical support, the pressure due to the accumulated gas is the cause. The positive electrode and the negative electrode are separated from each other, and as a result, there is a risk that a rapid performance deterioration occurs.

In order to solve such problems, a method of improving the mechanical support by adding an adhesive polymer, a method of adding hydrogen to increase hydrogen overvoltage, and fundamentally suppressing gas generation, Has been proposed.
However, the method of adding a polymer is extremely limited in terms of its effectiveness, and the method of adding mercury has a problem that it is extremely harmful in terms of environmental protection.

In addition, in order to suppress gas accumulation, a technique related to an open battery using a humidity-controlling substance as an electrolyte is disclosed (see, for example, Patent Documents 3 and 4).
However, since the battery according to these technologies has an extremely short operation period, it is practically impossible to apply it to an application device. In addition, even if possible, there is a risk of equipment damage because the electrolyte is corrosive. Furthermore, because the electrolyte concentration in the electrolyte and the constant relative humidity in the atmosphere are kept thermodynamically balanced, the electrolyte enters and exits in response to changes in atmospheric humidity, maintaining battery performance. There is a disadvantage that it becomes difficult.

  Therefore, it is actually very difficult to apply and implement the prior art based on the above-mentioned patent or utility model in the field of ultra-thin battery. Therefore, it overcomes various disadvantages, that is, high-rate characteristics are not sufficient, and overcomes the problems inherent in ultra-thin batteries, such as performance degradation due to electrolyte depletion during long-term charging or discharging, and can be implemented in practice. Development of thin batteries is strongly desired.

U.S. Pat. No. 4,623,598 JP-A 61-55866 US Pat. No. 5,811,204 Republic of Korea No. 10-041626 (Pamphlet of International Publication No. 97/22466)

  The present invention has been made in view of the above circumstances, and its purpose is to have excellent high-rate characteristics, prevent performance deterioration due to electrolyte depletion during long-term charging or discharging, and at the time of using a solid electrolyte. Provided is a positive electrode used for an ultra-thin manganese battery and a method of manufacturing the same, which suppresses a decrease in capacity and output, has a wide range of operating environment, and can prevent separation between the positive electrode and the negative electrode due to gas generation inside the battery. There is.

  In order to achieve the above object, the present invention further uses carboxymethylcellulose, which is a kind of water-soluble binder, as a third binder, and a solvent for polyvinylpyrrolidone, which is an organic solvent-soluble binder. By using dimethylformamide (DMF) as an organic solvent, it is possible to combine an organic solvent-soluble binder and a water-soluble binder, which have been difficult due to severe layer separation phenomenon.

  The present invention relates to a positive electrode of an ultra-thin manganese battery having excellent high rate characteristics and realizing a high energy density, and a method for manufacturing the same. Specifically, in the production of ultra-thin manganese battery positive electrodes, various binders are mixed and used to solve the problems that occur when using a single binder, and the discharge capacity and heavy load of the battery are solved. The present invention relates to a positive electrode used for an ultra-thin manganese battery capable of remarkably improving characteristics and a method for producing the same.

  More specifically, the present invention relates to a combination of an organic solvent-soluble binder and a water-soluble binder, which has been difficult due to a layer separation phenomenon, and a third binder is added. The present invention relates to a positive electrode used for an electrode for an ultrathin manganese battery that can be mixed without separating layers by using an appropriate solvent useful for the combination of the above and a method for producing the same.

  In general, in a battery, the state of an electrode such as its constituent material and composition and the manufacturing method are considered to have a great influence on the performance of the battery.

  Binders, one of the electrode components, are mainly divided into water-soluble binders and organic solvent-soluble binders, taking into account the type and processability of the electrolyte in the battery. Adopted.

  Water-soluble binders are mainly used for manganese batteries and manganese alkaline batteries, which are typical primary batteries. In addition, for lithium ion batteries using an organic solvent as an electrolyte, an organic solvent such as polyvinylidene fluoride is considered after considering various matters such as reactivity with the active material and safety of the electrode shape. A soluble binder is employed.

  On the other hand, an ultra-thin battery without a mechanical support requires a relatively large amount of binder compared to an existing cylindrical battery. As a result, although the manufacturing process is improved, the internal resistance increases. Therefore, the discharge performance is inferior. Therefore, conventional electrode manufacturing methods for ultra-thin manganese batteries adopt a method in which the amount added to a single component binder is optimized in consideration of such processability and battery performance. .

In such a method for producing an electrode of an ultra-thin battery, when a water-soluble binder is applied, the adhesive force with the gel electrolyte can be improved, and the period required for the activity of the battery can be shortened.
However, in this case, uniform mixing with the hydrophobic conductive agent is difficult, and a phenomenon occurs in which the electrode is detached from the current collector when the battery is left for a long time or during discharge. Such fragile electrode durability is considered to be one of the main causes for deteriorating the performance of a thin manganese battery having no mechanical support.

  On the other hand, some organic solvent-soluble binders have been applied as part of efforts to solve such problems, but in this case, severe shrinkage occurs during drying after electrode application, and carbon There is a problem that a peeling phenomenon occurs between the current collector and the electrode.

  Therefore, the present inventor further mixes the third binder at the time of mixing, and selects an appropriate solvent so that it can be combined for a severe layer separation phenomenon while having complementary advantages and disadvantages as described above. The best combination capable of mixing the organic solvent-soluble binder and the water-soluble binder that was not found was discovered, and the present invention was completed.

  The inventor has specified the composition and the kind of the binder in the examples and claims, and as a result of analyzing the discharge characteristics of the battery, it has been found that excellent output characteristics and active material utilization can be achieved. Therefore, finally, components and compositions that make use of only the advantages of the applied binder were set.

That is, the present invention is a positive electrode for an ultrathin manganese battery characterized by containing a mixture of an organic solvent-soluble binder and a water-soluble binder.
The organic solvent-soluble binder is preferably at least one selected from the group consisting of polyvinylpyrrolidone, polyvinylidene fluoride, polymethyl methacrylate, and styrene butyl rubber. Further, the water-soluble binder is preferably polyvinyl alcohol, polyethylene oxide, cross-linked polyethylene oxide, or 2-hydroxyethyl cellulose to which carboxymethyl cellulose is added.
Further, in the present invention, acetylene black as a conductive agent is put in a ball mill and pulverized for 1 to 7 days, and then primary-dried in a drying furnace at 105 ° C. for 12 hours or more, and then secondary in an vacuum dryer for 1 hour. Dry;
60 to 98% by weight of manganese dioxide and 0.1 to 20% by weight of acetylene black previously pulverized and dried are mixed with a high-speed mixer for 1 to 24 hours, based on the positive electrode mixture for positive electrode production;
A water-soluble binder is dissolved in an aqueous solvent so as to be 0.01 to 5% by weight on the basis of the mixture, and an organic solvent-soluble binder is dissolved therein so that it becomes 0.1 to 5% by weight on the basis of the mixture Mixing the agent to prepare a binder solution;
The mixed manganese dioxide and acetylene black powder were bound so that the organic solvent-soluble binder was 0.1 to 5% by weight and the water-soluble binder was 0.01 to 5% by weight based on the final positive electrode plate. Adding and stirring the adsorbent solution to prepare a positive electrode mixture slurry for positive electrode production;
The prepared positive electrode mixture slurry is applied to a current collector of a polymer film for packaging material to a thickness of 50 to 300 μm with a doctor blade, and dried in a drying oven at 60 ° C. for 2 hours or more;
This is a method for producing a positive electrode for an ultrathin manganese battery.

  According to the present invention, carboxymethylcellulose, which is a kind of water-soluble binder, is further used as the third binder, and dimethylformamide is used as a solvent for polyvinylpyrrolidone, which is an organic solvent-soluble binder, A combination of an organic solvent-soluble binder and a water-soluble binder, which has been difficult due to severe layer separation, is possible.

  In addition, according to the present invention, it has excellent high rate characteristics, prevents performance degradation due to electrolyte depletion during long-term charging or discharging, and suppresses capacity and output reduction when using solid electrolyte, and operates It is possible to provide a positive electrode used in an ultra-thin manganese battery and a method for manufacturing the same, which has a wide environment range and can prevent separation between the positive electrode and the negative electrode due to gas generation inside the battery.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing the basic structure of an ultra-thin manganese battery according to the present invention, FIG. 2 is a cross-sectional view showing the basic structure of the ultra-thin manganese battery according to the present invention, and FIG. It is a graph which shows the discharge capacity of 13 kohm of the thin manganese battery manufactured by the Example and comparative example of this invention.

  When manufacturing electrodes for ultra-thin batteries, the electrode density can be increased by using only organic solvent-soluble binders such as polyvinyl pyrrolidone among the materials that are frequently used as conventional binders. However, there are problems such as deterioration in processability due to severe deformation of the electrode itself after drying, and occurrence of a peeling phenomenon between the current collector and the electrode.

  In addition, if only typical water-soluble binders such as polyethylene oxide and polyvinyl alcohol are used, the binder will be dissolved in the water-soluble electrolyte, so it will be charged during long-term charging. Durability problems such as electrode shape deformation occurred.

  In particular, in the case of polyvinyl alcohol, the durability of the electrode is extremely inferior and the electrode composition is not uniform, resulting in large variations in battery capacity.

  In order to improve this, an attempt was made to mix an organic solvent-soluble binder with polyethylene oxide, which is a typical water-soluble binder, but the electrode could not be produced due to a layer separation phenomenon. Further, when polyvinylpyrrolidone and polyvinyl alcohol were mixed, the layer separation phenomenon disappeared, but the desired capacity increase and output improvement effects could not be obtained.

  In the ultrathin battery of the present invention, manganese dioxide is used as the positive electrode active material, zinc is used as the negative electrode active material, polyvinylpyrrolidone is used as the organic solvent-soluble binder, and polyvinyl alcohol is used as the water-soluble binder. By using carboxymethyl cellulose, which is a kind of water-soluble binder, as the binder of dimethylformamide as the solvent of polyvinylpyrrolidone as the organic solvent-soluble binder, it was difficult due to severe layer separation phenomenon. Combinations of organic solvent soluble binders and water soluble binders are now possible.

  Among these, dimethylformamide as a solvent for organic solvent-soluble binder polyvinylpyrrolidone is a kind of polar aprotic solvent, which is a colorless water-soluble liquid having a molecular formula of (CH) NCHO, originally a urethane. Not only used in fiber and acrylic fiber spinning, artificial leather manufacturing, and fiber coating processing industries, but also in dyes and pigments for fiber dyeing, paint removal solvents, coating solutions, printing solutions, and adhesives It is a substance that has been.

  Such dimethylformamide is a solvent that is useful for organic ion reaction because it has a certain degree of polarity while being an excellent polymer solvent. This shows that dimethylformamide plays an important role in the mixing of the organic solvent-soluble binder and the water-soluble binder in the combination of the binder of the present invention.

  Next, the manufacturing method of the positive electrode of the ultra-thin manganese battery of this invention using the combination of the binder mentioned above is demonstrated.

.
First, acetylene black as a conductive agent is put in a ball mill and pulverized for 1 to 7 days, and then primary dried in a drying furnace at 105 ° C. for 12 hours or more, and then secondarily dried in a vacuum dryer for 1 hour.

  60 to 98% by weight of manganese dioxide and 0.1 to 20% by weight of acetylene black preliminarily pulverized and dried are mixed with a high speed blender mixer for 1 to 24 hours. To do.

  Polyvinyl pyrrolidone is dissolved in a dimethylformamide solvent so that it becomes 0.2 to 10% by weight on the basis of the mixture, and polyvinyl alcohol is dissolved in distilled water so that it becomes 0.05 to 10% by weight on the basis of the mixture. Carboxymethylcellulose is dissolved in distilled water so as to be 0.01 to 5% by weight on the basis of the agent.

  Next, the mixed manganese dioxide and acetylene black powder is mixed with a binder solution so as to contain 0.1 to 20% by weight of the binder on the basis of the mixture, and stirred, so that the positive electrode composite for positive electrode production is mixed. An agent slurry is prepared. In this case, preferably, the organic solvent-soluble binder is finally 0.1 to 5% by weight and the water-soluble binder is 0.01 to 5% by weight based on the positive electrode mixture.

  Next, the mixed slurry of the positive electrode mixture is applied on a current collector of a polymer film for packaging material to a thickness of about 50 to 300 μm with a doctor blade, and dried at 60 ° C. or higher. Dry in an oven for 2 hours or more to produce a positive electrode.

  Then, the manufacturing method of a negative electrode is demonstrated. First, zinc powder and conductive agent acetylene black are mixed in a weight ratio of 20: 1. A negative electrode manufacturing slurry is prepared by mixing a binder solution prepared in advance so as to contain 0.01 to 20% by weight of the binder.

  Next, the prepared negative electrode mixture slurry was applied to a current collector of a polymer film for packaging material to a thickness of about 10 to 200 μm with a doctor blade, and this was applied in a drying oven at 60 ° C. or higher for 2 hours or longer. A negative electrode is produced by drying.

  A separator impregnated with a gel electrolyte is placed between the manufactured positive electrode and negative electrode, and then sealed together to produce a battery.

  At this time, in order to strongly adhere the positive electrode and the negative electrode, after maintaining a vacuum state for 1 to 3 minutes, sealing is performed to maintain a negative pressure in the battery.

The electrolyte was prepared by mixing 10% by weight of zinc chloride (ZnCl ₂ ) and 1% by weight of ammonium chloride (NH ₄ Cl) with water to prepare a liquid phase electrolyte, and adding polyethylene oxide to the electrolyte. A gel electrolyte was prepared by dissolving to 5 wt%.

  In the present invention described above, the organic solvent-soluble binder is selected from the group consisting of polyvinylpyrrolidone, polyvinylidene fluoride, polymethylmethacrylate, and styrene butyl rubber. One or more of them can be used.

  Examples of the water-soluble binder include polyvinyl alcohol, polyethylene oxide, cross-linked polyethylene oxide or 2-hydroxy ethyl cellulose and carboxymethyl cellulose (Carbonyl methyl cellulose). ) Can be used.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, and test examples using these. However, this does not limit the invention.

[Example 1]
An electrode was prepared based on the following composition and method, and an ultrathin manganese battery was assembled using the electrode.

  Polyethylene oxide (5.26 g) was added to 98.5 g of an electrolytic solution in which zinc chloride and ammonium chloride were mixed, and the mixture was dissolved with a stirrer for 20 hours to prepare a gel electrolyte.

  The slurry in which the carbon powder and the binder are mixed is applied on the polymer film 8 of the packaging material to a thickness of 20 μm, and dried at 60 ° C. for 2 hours to obtain the positive electrode current collector 4 and the negative electrode current collector. Body 5 was obtained.

  After 10 g of acetylene black for positive electrode production was put into a ball mill and subjected to a crushing process for 3 days, it was primarily dried for 12 hours or more with a 105 ° C. dryer, and then secondary dried for 1 hour with a vacuum dryer at 80 ° C. An agent was obtained.

  Polyvinylpyrrolidone is dissolved in dimethylformamide so as to be 1.5% by weight based on the positive electrode mixture, and polyvinyl alcohol is dissolved in distilled water so as to be 2% by weight based on the positive electrode mixture. Carboxymethylcellulose was dissolved in distilled water so as to be 0.5% by weight, and these solutions were mixed. 200 ml of this binder solution was poured into a beaker and stirred for 30 minutes to prepare a three-component binder solution.

  After crushing 0.5 g of crushed acetylene black and 9.5 g of manganese dioxide with a high-speed mixer for 2 hours, this was mixed with a binder solution prepared in advance so as to be 5% by weight based on the positive electrode mixture. Thus, a positive electrode mixture slurry for positive electrode production was prepared.

  Next, a 10 mm diameter molded film with a circular hole is placed on the positive electrode current collector 4 of the polymer film 8, and after pouring the positive electrode slurry onto this, it is applied with a doctor blade, and is dried at 60 ° C. And dried for 2 hours or more to prepare a positive electrode plate 1.

  0.5 g of crushed acetylene black and 10 g of zinc powder were mixed, and a binder solution prepared in advance so as to be 5% by weight based on the negative electrode mixture was added to prepare a slurry for negative electrode production. .

Next, the negative electrode plate 2 was prepared on the negative electrode current collector 5 of the polymer film 8 in the same manner as the positive electrode manufacturing step using the negative electrode manufacturing slurry. A double-sided adhesive 9 having a width of 3.6 mm is attached to the edge of the negative electrode plate 2, and the separator 3 impregnated with the gel electrolyte 10 is disposed on the positive electrode plate 1, and then 10 ⁻⁵ to 10 ⁻¹ torr vacuum. An ultra-thin manganese battery was assembled by sealing under conditions.

[Comparative Example 1]
In producing the positive electrode, the positive electrode and the battery were prepared in the same manner as in Example 1 except that polyvinyl alcohol was mixed as a single binder instead of the multicomponent binder solution so that the amount was 5% by weight based on the positive electrode mixture. Was made.

[Comparative Example 2]
In producing the positive electrode, the positive electrode and the battery were treated in the same manner as in Example 1 except that polyvinylpyrrolidone was mixed as a single binder instead of the multicomponent binder solution so as to be 5% by weight based on the positive electrode mixture. Was made.

[Comparative Example 3]
In producing the positive electrode, the positive electrode and the battery were treated in the same manner as in Example 1 except that polyethylene oxide was mixed as a single binder instead of the multi-component binder solution so as to be 5% by weight based on the positive electrode mixture. Was made.

[Test example]
Using the batteries obtained from the examples and comparative examples, the battery capacity up to the end voltage was tested, and the utilization rate of the positive electrode active material was measured based on the mixture amount at the time of manufacturing the positive electrode and the negative electrode.

  In the test, the batteries according to Examples and Comparative Examples were left at room temperature for 1 day, and then discharged under a 13 μΩ constant resistance condition using a discharger. At this time, the flowing current was about 0.1 mA, and the end voltage was 0.9V.

  Tests were conducted on Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, and the results are shown in FIG. Table 1 shows the utilization ratio of the positive electrode active material.

  As a result of the test, as shown in FIG. 3, the battery using the positive electrode according to Example 1 of the present invention has an electric capacity of 3.46 mAh and a high output characteristic in which an operating voltage of about 1.3 V is maintained until the end voltage. showed that. On the other hand, it was found that the discharge capacities of the batteries according to Comparative Example 1, Comparative Example 2 and Comparative Example 3 using a single component binder were significantly reduced.

  From the aspect of utilization rate of the positive electrode active material, manganese dioxide utilization rate was 81.5% in Example 1 of the present invention, whereas it was 75% or less in the comparative example. Considering such a result considering that the battery is a very thin thin battery, the method of the example is superior to the method of the comparative example in terms of energy charging when provided in the same space. Recognize.

It is a perspective view which shows the basic structure of the ultra-thin manganese battery which concerns on this invention. It is sectional drawing which shows the basic structure of the ultra-thin manganese battery which concerns on this invention. 5 is a graph showing 13 kΩ discharge capacity of thin manganese batteries manufactured according to examples and comparative examples of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Positive electrode collector 5 Negative electrode collector 6 Positive electrode tap 7 Negative electrode tap
8 Polymer film 9 Double-sided adhesive 10 Gel electrolyte

Claims (1)

  Polyvinylpyrrolidone as an organic solvent degradable binder dissolved in dimethylformamide solvent and polyethylene oxide as a water-soluble binder dissolved in distilled water are mixed and used as a water-soluble binder dissolved in distilled water. A positive electrode for an ultra-thin manganese battery, characterized in that a mixture of polyvinyl alcohol, carboxymethyl cellulose, and a combination thereof is contained in a binder.

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