KR101111210B1 - Thin film manganese dioxide battery - Google Patents

Abstract

According to an aspect of the present invention, a thin manganese battery is a thin manganese battery including a positive electrode layer, a negative electrode layer, and an electrolyte solution, and the electrolyte solution contains calcium hydroxide.

Thin battery

Description

Thin film manganese dioxide battery

TECHNICAL FIELD The present invention relates to a thin battery, and more particularly, to a thin manganese battery capable of suppressing the deterioration of battery performance by suppressing gas generation in the battery.

Batteries for converting chemical energy into electrical energy are classified into primary batteries that are discarded when energy stored in the batteries are depleted and secondary batteries that can be recharged according to their use characteristics. Recently, with the rapid development of RFID, smart card, transportation card, and iontophoresis patch technology, the demand for thin batteries as the power source of these products is increasing day by day. Commercialization of RFID is mainly focused on passive tags, but active technologies for attaching batteries to tags are being actively developed according to passive functional limitations. The iontophoresis device using the electric repulsive force has been mainly used in limited spaces such as hospitals, but with the development of thin battery technology, it has advanced to the patch technology attached to the human body.

In the technical fields such as RFID cards, IC cards, and ion photoresist patches, a thin battery having a low cost, sufficient durability, and a thickness of several hundred microns is required. It is called thin manganese battery. Specifically, the thin battery refers to a thin film battery, and includes a positive electrode, a negative electrode, and an electrolyte like a general battery. A thin battery may be manufactured by implementing a current collector, an electrode, and a polymer packaging material in a thin and flexible manner.

Thin batteries using polymer films instead of steel tubes or metal cans as packaging materials can be freely changed as well as easy to manufacture in a very thin form. However, there is a problem in the swelling phenomenon due to gas generation in the thin battery. That is, a thin battery without a mechanical support exhibits a sharp performance deterioration due to the expansion of the thickness of the battery and the separation of electrodes even when a small amount of gas is generated. Therefore, the key to developing a thin cell depends on how effectively the gas generated in the cell is suppressed.

A method for solving the gas problem occurring in a cell is disclosed in U.S. Patent No. 3901732 to Kis et al., Which discloses a selective permeable film that can discharge gas formed in the cell while preventing the cell from evaporating the electrolyte. Used as a battery packaging material. In these technologies, it is important to suppress electrolyte evaporation and selectively select and release unwanted gas, and if the gas permeation selectivity of the film is increased, the amount of gas permeating through the film may be extremely limited. If the gas generated inside the cell has a weak propulsion to move out, or if the amount of permeable gas allowed through the film does not follow the gas generation rate occurring in the cell, gas is likely to accumulate in the cell.

In addition, US Pat. No. 5811204 and N Pat. No. 10-0412626 to Nitzan et al. Disclose the manufacture of an open type battery using a hygroscopic substance as an electrolyte so that there is no accumulation of gas. In this case, the vapor pressure of the electrolyte changes according to the concentration of the humidity in the electrolyte, and the amount of evaporation of the electrolyte is thermodynamically correlated with the relative humidity in the atmosphere. Therefore, the electrolyte flows in and out of the battery packaging according to the change in the humidity of the air has a disadvantage that it is difficult to ensure the performance of the battery.

As described above, it can be seen that a series of technical developments have been made so far to exhaust gas generated in the battery. However, these technologies have limitations in solving battery expansion and performance deterioration due to gas generation or have problems due to changes in humidity. Therefore, there is a need for a new technical approach to commercialize thin batteries and broaden their applications.

One of the problems of the present invention is to provide a thin manganese battery in which the generation of gas in the thin battery is suppressed, thereby improving the performance of the manganese battery, in particular, its storage characteristics (permanence of performance, lifetime).

According to an aspect of the present invention, a thin manganese battery is a thin manganese battery including a positive electrode layer, a negative electrode layer, and an electrolyte solution, and the electrolyte solution contains calcium hydroxide. Calcium hydroxide may be contained in a saturated state in the electrolyte solution.

According to an embodiment of the present invention, the cathode layer may include a zinc alloy to which a gas suppression inhibitor is added, which is selected from the group consisting of bismuth (Bi), indium (In), and aluminum (Al). Can be. As the inhibitor, at least one of bismuth, indium, and aluminum may be contained in the zinc alloy in an amount of 10 to 1,000 ppm, respectively. The zinc alloy may be included in the negative electrode layer in the form of powder of the zinc alloy to which the inhibitor is added.

According to an embodiment of the present invention, the thin manganese battery may be a closed thin battery. In this case, the thin manganese battery may further include a film having a moisture barrier property to prevent evaporation of the electrolyte as a packaging material for packaging the positive electrode layer, the negative electrode layer and the electrolyte. The moisture barrier film may be a polymer film such as polyethylene terephthalate or polyacrylonitrile or a metal laminate film such as aluminum.

The anode layer may include a binder containing at least one binder component selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone, and polymethyl methacrylate, and manganese dioxide powder. Can be.

The negative electrode layer is a binder containing one or more binder components selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone and polymethyl methacrylate, and zinc or zinc alloy. It may include a powder.

In particular, it is preferable that the anode layer and the cathode layer include a multicomponent binder in which at least two or more of polyethylene oxide, polyvinylpyrrolidone, and polymethyl methacrylate are dissolved in an organic solvent.

The electrolyte may be a gel electrolyte to which a polymer material selected from the group consisting of polyethylene oxide, polyvinyl alcohol, and carbonyl methyl cellulose is added.

According to the present invention, it is possible to effectively suppress the generation of gas such as hydrogen in the thin manganese battery, thereby preventing the thickness expansion of the thin manganese battery due to the gas generation, electrode spacing, abrupt performance degradation, and the like. In particular, it is possible to introduce a packaging material such as a metal laminate film having excellent sealing properties by suppressing gas generation itself in a closed thin battery, in which case the storage performance of the battery is greatly improved. In addition, regardless of the ambient humidity changes, it is possible to improve the storage characteristics and life of the battery with the stable maintenance of the electrolyte.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. The shape and the size of the elements in the drawings may be exaggerated for clarity and the same elements are denoted by the same reference numerals in the drawings.

The present inventors have been able to improve performance, especially storage characteristics, of a thin manganese battery by adding a specific substance capable of suppressing gas generation to an electrolyte or a negative electrode. The gas generating mechanism (2Zn + 2H ₂ O-> 2ZnO + 2H ₂ ↑) in a thin manganese battery is known to be produced in hydrogen gas by mainly reacting zinc, which is an aqueous electrolyte, and a cathode during storage or discharge of the battery. The present inventors were able to solve the problems caused by gas generation by adding a specific substance capable of suppressing such gas generation into the battery, and at the same time, introduce a packaging material with excellent sealing property to greatly improve the storage performance of the thin battery.

1 is a perspective view showing main parts of a thin manganese battery according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the thin manganese battery of FIG. 1. As shown in FIGS. 1 and 2, the thin manganese battery includes a positive electrode layer 1, a negative electrode layer 2, and an electrolyte 10, and additionally a packaging material 8 and a sealing material 9 for sealing. It includes. The packaging material 8 may serve as a substrate on which the positive electrode current collector 4 or the negative electrode current collector 5 is applied, and at the same time, serve to package basic members such as a positive electrode, a negative electrode, and an electrolyte. A sealing material 9 made of a double-sided adhesive tape or the like may be attached between the upper and lower packaging materials 8 to seal the entire battery structure. Instead of using the sealing material 9, the entire battery structure can be sealed by applying heat to both the upper and lower packaging materials 8 and fusing them together. The packaging material 8 is a film having moisture barrier properties (i.e., the film does not penetrate water vapor in the battery) and this thin manganese cell basically belongs to the closed type. Since it is a closed type, it is possible to prevent a decrease or exhaustion of the electrolyte due to the vaporization of water vapor.

An electrolyte 10 in contact with each electrode is disposed between the positive electrode layer 1 and the negative electrode layer 2 to structurally separate the positive electrode structure (anode layer and positive electrode current collector) and the negative electrode structure (negative electrode layer and negative electrode current collector). The separator 3 is arranged in the middle for that purpose. Such an electrolyte 10 and the separator 3 can be easily implemented, for example, by arranging kraft paper soaked in a previously prepared electrolyte in the middle of a thin cell structure. Each current collector 4, 5 is connected to terminals 6, 7, which protrude outwardly from a portion of the current collectors 4, 5 as shown in FIG. Or withdrawn) form. These terminals 6 and 7 are used to electrically connect the battery to an external load.

The packaging material 8 may be a polymer film or a metal laminate film such as aluminum. Examples of the polymer film used as the packaging material 8 include a polyacrylonitrile film or a polyethylene terephthalate film. In addition, a metal laminate film may be further introduced on the polymer film such as polyacrylonitrile or polyethylene terephthalate as the packaging material 8.

The positive electrode current collector 4 and the negative electrode current collector 5 may be obtained by, for example, coating a carbon ink composed of carbon powder and a binder on a packaging material 8 with a thickness of 15 μm and drying at 60 ° C. for 2 hours. . The carbon ink used as the electrode current collector may be prepared by mixing a suitable binder with a solvent and fine carbon powder, or may be purchased and used as a finished product. Instead of the carbon powder, a metal ink in which conductive metal powders such as silver powder, copper powder, and nickel powder are mixed may be used, or a mixture of these and carbon inks may be used. In the case of carbon ink, the viscosity is about 36,000 to 50,000 cps, but the viscosity may be adjusted in consideration of manufacturing processability.

The positive electrode layer 1 may be prepared by mixing manganese dioxide powder, a conductive agent, and a binder dissolved in a solvent to form a slurry and then coating the positive electrode current collector 4 on a positive electrode. A slurry may be prepared by dry mixing powdered manganese dioxide having a particle size of about 40 μm or less and carbon black as a conductive agent and adding a binder solution thereto. The binder solution may be a multicomponent binder in which two or more types of binder components are mixed with an organic solvent. Polyethylene oxide, polyvinyl pyrrolidone, polymethyl methacrylate, and the like may be used as the binder component. In the conventional thin manganese batteries, a single water-soluble binder (a binder in which water is dissolved in water as a solvent) was used, but in this embodiment, a multicomponent binder dissolved in an organic solvent rather than an aqueous solution may be introduced. It is more advantageous in terms of occurrence suppression. In particular, a multicomponent binder containing at least two of polyethylene oxide, polyvinylpinolidone, and polymethylmethacrylate dissolved in an organic solvent is preferable in terms of suppressing gas generation.

In order to manufacture the negative electrode layer 2, a zinc powder having a particle size of 10 to 70 μm and carbon black as a conductive material are mixed with each other, and a binder solution prepared in advance is added to prepare a slurry for preparing a negative electrode. As the zinc powder used as the negative electrode active material, pure zinc powder or zinc powder in the form of an alloy may be used.

In particular, the zinc powder (zinc alloy powder) in the form of an alloy used for the cathode layer 2 contains an inhibitor component that suppresses a gas generated during storage or discharge of a battery, and is an inhibitor for gas generation. At least one of aluminum (Al), bismuth (Bi), and indium (In) is added to zinc.

As the inhibitor, at least one of bismuth, indium, and aluminum may be contained in the zinc alloy in an amount of 10 to 1,000 ppm, respectively. In particular, when the content of bismuth added to zinc is 10ppm to 200ppm, the gas generation suppression effect is large, and the gas generation suppression effect is hardly changed at a higher content. However, if the bismuth content exceeds 1000ppm, when the battery is exposed to an over discharge state, the increase of bismuth content decreases the gas generation inhibitory effect, and the apparent density of zinc decreases, thereby reducing the battery capacity at the same volume. have. Therefore, the content of bismuth added to zinc is preferably 10 to 1000 ppmn, more preferably 100 to 800 ppm, even more preferably 100 to 200 ppm. When the amount of indium added to zinc is 10 to 500ppm, the amount of gas generated is drastically reduced, but at higher contents, the difference in amount of gas is not large. In consideration of the zinc apparent density due to the added indium and the cost of addition, the content of indium in zinc is preferably 10 to 1000 ppm. More preferably, the content of indium is 10 to 500 ppm, even more preferably 200 to 300 ppm. Increasing the amount of aluminum added gas tends to decrease accordingly. In order to obtain a sufficiently high gas generation suppression effect, the aluminum content is preferably 10 ppm or more. However, if the aluminum exceeds 1000ppm, the production cost of the battery increases and the amount of zinc, a source of energy, decreases, leading to a decrease in battery capacity. More preferably, the aluminum content is 100 to 200 ppm.

Similar to the anode layer 1, the cathode layer 2 also has a multi-component binder system such as polyethylene oxide, polyvinyl pyrrolidone, and polymethyl methacrylate, together with an organic solvent. Can be applied. The negative electrode slurry is coated on the negative electrode current collector 5 with a coater and dried in a drying furnace set at 60 ° C. for at least 2 hours to prepare a negative electrode layer 2.

As the electrolyte solution 10, a water-soluble electrolyte solution in which zinc chloride (ZnCl ₂ ) or ammonium chloride (NH ₄ Cl) is mixed with purified water is used. The introduction of a mixture of zinc chloride and ammonium chloride has the advantage of pursuing both heavy load performance and intermittent discharge performance. In order to suppress the gas which generate | occur | produces in a battery, calcium hydroxide is previously added to the purified water for electrolyte solution manufacture. In this case, calcium hydroxide is added in the content of saturated concentration in electrolyte solution in order to especially increase gas suppression effect. When calcium hydroxide in the electrolyte is added above the saturation concentration, calcium hydroxide is deposited at the bottom of the electrolyte. When precipitation of calcium hydroxide in the supersaturated state flows into the battery, the resistance of the battery may be increased and a capacity deviation may be caused.

In addition, in the thin manganese battery, the electrolyte evaporation may cause a sudden drop in the performance of the battery, so that the polymer may be dissolved in the electrolyte to prevent the vapor pressure drop of the electrolyte. In this case, the polymer may be polyethylene oxide, polyvinyl alcohol, carbonyl methyl cellulose, or the like.

Hereinafter, the present invention will be described in more detail with examples, comparative examples and test examples using these. Such invention is not limited to the following examples.

Example 1

A thin manganese battery was prepared as Example 1 using the following composition and preparation method.

To form the anode layer (1) material, 10 g of carbon black was placed in a ball mill, pulverized for 3 days, placed in a dryer set at 105 ° C., left for at least 12 hours, and then dried for 2 hours in a vacuum dryer. do. Manganese dioxide, a cathode active material, and pre-pulverized carbon black are mixed and then mixed for 1 to 24 hours using a high speed mixer. The mixture is mixed with the binder solution to prepare a slurry. The binder includes multiple components of polyethylene oxide, polyvinylpyrrolidone, and polymethyl methacrylate dissolved in an organic solvent.

The prepared slurry for positive electrode was coated on a polyethylene terephthalate film (packaging material) with a carbon ink coated current collector so as to have a rectangle of 4 cm and 4 cm, and dried in a drier set at 60 ° C. for at least 2 hours to give a positive electrode layer. To prepare. The thickness of the anode layer after drying is about 100㎛ and the composition is 90% by weight manganese dioxide, 4.7% by weight carbon black, 5.3% by weight binder.

The negative electrode layer 2 is mixed with pure zinc powder having a particle size of 45 μm or less, carbon black, and a binder solution dissolved in an organic solvent to form a slurry, and then a square having the same size as the positive electrode is prepared on the prepared negative electrode current collector 5. After coating to make it dry. As the binder, a multi-component binder of polyethylene oxide and polymethyl methacrylate dissolved in an organic solvent was used. After drying, the thickness of the negative electrode was about 65 μm, and the composition of the negative electrode was 92 wt% zinc, 4.5 wt% conductive material, and 3.5 wt% binder.

To prepare the electrolyte solution 10, 20 g of calcium hydroxide (Ca (OH) ₂ ) was added to 1,000 ml of purified water, stirred for 12 hours or more, and allowed to stand for 5 hours to precipitate calcium hydroxide in the lower layer. Only the solution saturated with calcium hydroxide in the upper part is collected and transferred to a 500 ml beaker and used for preparing the electrolyte solution. 52 ml of calcium hydroxide saturated water is collected, poured into a 200 ml beaker, and stirred by addition of 48 g of ZnCl ₂ , followed by 38.3 ml of saturated calcium hydroxide saturated water, followed by stirring until complete melting, thereby making an aqueous ZnCl ₂ solution. 5g of polyethylene oxide was added to the prepared aqueous solution, stirred for 24 hours, and then sieving with powder (sieve 325mesh) to prepare a gel electrolyte having a viscosity of 9,000 ± 1000 cps.

A thin battery was assembled by laminating a kraft paper soaked in gel electrolyte between the cathode layer 1 and the anode layer 2 prepared as described above, and then sealing it with a double-sided adhesive. At this time, in order to closely adhere the positive electrode and the negative electrode, the vacuum state is maintained for 1 to 3 minutes and then sealed to maintain the negative pressure in the battery.

[Example 2]

A negative electrode layer was manufactured in the same manner as in Example 1 except for using zinc powder mixed with 200 ppm aluminum, bismuth 200 ppm, and indium 300 ppm instead of pure zinc powder.

Example 3

A negative electrode layer was manufactured in the same manner as in Example 1, except that bismuth 200 ppm and indium 200 ppm were mixed in place of pure zinc powder.

[Comparative Example]

A battery was manufactured in the same manner as in Example 1, except that the purified water was saturated with calcium hydroxide. That is, the comparative example omitted the addition of calcium hydroxide in Example 1.

[Measuring Gas Generation in Thin Battery]

In the oven set at 45 ° C., the thin batteries prepared according to Examples 1 to 3 and Comparative Examples were taken out at regular intervals while being stored (stored) to measure volume change and thickness change of the battery. The volumetric method was used to track the volume change and the gas generated in the cell per unit weight of zinc was calculated from the amount of zinc (g) incorporated into the negative electrode during cell manufacture. The gas generation amount thus calculated (per unit zinc weight) is shown in the graph of FIG. 3. As shown in FIG. 3, compared with Comparative Example 1, Examples 1 to 3 significantly reduced the amount of gas accumulated in the battery (after 20 days, the amount of accumulated gas was reduced by half or less than that of Comparative Example 1).

In addition, as can be seen in the thickness change graph shown in Figure 4, Examples 1 to 3, as compared with the comparative example, the gas generation amount itself is reduced, the thickness of the battery over time is significantly reduced. On the contrary, in Comparative Example 1, it can be seen that the thickness increases relatively due to the gas accumulation in the battery.

In addition, as can be seen from the battery capacity change graph shown in Figure 4, Examples 1 to 3 it can be seen that the battery capacity decrease phenomenon with time is significantly improved compared to the comparative example. Accordingly, it can be seen that Examples 1 to 3 are superior in the storage characteristics of the battery compared to the comparative example, and its life can be prolonged much.

The present invention is not limited by the above-described embodiment and the accompanying drawings. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims, .

1 is a perspective view showing main parts of a thin manganese battery according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the thin manganese battery of FIG. 1.

Figure 3 is a graph showing the gas accumulation amount (generation amount) in the battery according to the storage period of the thin manganese battery of the Examples and Comparative Examples of the present invention.

4 is a graph showing the change in battery thickness according to the storage period of the thin manganese battery of the Examples and Comparative Examples of the present invention.

5 is a graph showing a change in battery capacity according to the storage period of the thin manganese battery of the Examples and Comparative Examples of the present invention.

<Description of the symbols for the main parts of the drawings>

1: anode layer 2: cathode layer

3: separator 4: positive electrode current collector

5: negative electrode current collector 6: positive terminal

7: negative terminal 8: packing material

9: sealing material 10: electrolyte

Claims (13)

A thin manganese battery having a closed structure including an anode layer, a cathode layer, and an electrolyte solution, The electrolyte solution contains calcium hydroxide, The negative electrode layer is a thin manganese battery, characterized in that it comprises a zinc alloy to which at least one inhibitor (inhibitor) is selected from the group consisting of bismuth (Bi), indium (In) and aluminum (Al) is added. The method of claim 1, Thin manganese battery, characterized in that the calcium hydroxide contained in a saturated state in the electrolyte solution. delete The method of claim 1, Thin manganese battery, characterized in that at least one of bismuth, indium and aluminum as the inhibitor is contained in the zinc alloy in a content of 10 ~ 1,000ppm each. The method of claim 1, The zinc alloy is a thin manganese battery, characterized in that included in the negative electrode layer in the form of a powder of zinc alloy to which the inhibitor is added. The method of claim 1, The thin manganese battery is a closed thin battery, A thin manganese battery further comprising a film having a moisture barrier property to prevent evaporation of the electrolyte as a packaging material for packaging the anode layer, the cathode layer and the electrolyte solution. The method of claim 6, The film having the moisture barrier property is a thin manganese battery, characterized in that the polyethylene terephthalate or polyacrylonitrile film. The method of claim 6, The film having the moisture barrier property is a thin manganese battery, characterized in that the metal laminate film. The method of claim 1, The anode layer includes a binder containing at least one binder component selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone, and polymethyl methacrylate, and manganese dioxide powder. Thin manganese battery, characterized in that. The method of claim 1, The negative electrode layer further comprises a binder containing at least one binder component selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone and polymethyl methacrylate. Thin manganese batteries. The method of claim 1, The positive electrode layer and the negative electrode layer is a thin manganese battery further comprises a multi-component binder in which at least two or more of polyethylene oxide, polyvinylpyrrolidone and polymethyl methacrylate dissolved in an organic solvent. The method of claim 1, The electrolyte is a thin manganese battery, characterized in that the gel (gel type) electrolyte. The method of claim 12, The electrolyte is a thin manganese battery, characterized in that the gel electrolyte is added to the polymer material selected from the group consisting of polyethylene oxide, polyvinyl alcohol and carbonyl methyl cellulose.

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