KR20100056260A - Fabrication method of nickel/zinc secondary battery - Google Patents

Abstract

PURPOSE: A fabrication method of a nickel / zinc secondary battery is provided to prevent aggregation phenomenon when a cathode paste including active materials is formed and to prevent the production of a zinc dendrite and deformation of the cathode when the cathode is dissolved in alkaline electrolyte. CONSTITUTION: A fabrication method of a nickel / zinc secondary battery comprises: a step(S1) mixing cathode active materials, activated carbon, and graphite powder using a ball mill method; a step(S2) manufacturing slurry by adding a thickening agent after wetting the mixture which is manufactured in the previous step; a step(S3) manufacturing a cathode composition by adding a binder to the slurry; a step(S4) coating a current collector with the cathode composition; a step(S5) forming the cathode by drying the cathode composition which is coated on the current collector; a step(S6) drying coated materials after coating a separator with porous ceramic, silica, a binder, or a thickening agent; and a step(S7) compressing the separator on the cathode by applying heat and pressure.

Description

Manufacturing method of nickel / zinc secondary battery {FABRICATION METHOD OF NICKEL / ZINC SECONDARY BATTERY}

The present invention relates to a method for manufacturing a nickel / zinc secondary battery and to a nickel / zinc secondary battery manufactured using the same, and more particularly, to improve agglomeration when forming a paste including an active material in a process of forming a negative electrode, and to form a separator. A method of manufacturing a nickel / zinc secondary battery capable of preventing the shape deformation or the formation of dendrite of a zinc anode generated by dissolving the negative electrode in an alkaline electrolyte solution by pressing the negative electrode to prepare a negative electrode, and the nickel / produced using the same It relates to a zinc secondary battery.

In recent years, various environmental regulations have been implemented as a will to protect the environment of each country. With this movement, lead-acid batteries and nickel / cadmium batteries have already been replaced with nickel / hydrogen and lithium-ion batteries in small batteries, but lead-acid batteries and nickel / cadmium batteries are still used in the industrial large battery field because there are no alternative batteries. . Therefore, interest in environmentally friendly large-capacity storage batteries is increasing, and technology development is intensively progressed accordingly.

Among them, nickel (Ni) / zinc (Zn) secondary batteries, which can replace lead acid batteries, have an operating voltage of 1.6 [V / cell] or higher, high weight and bulk energy density, and specific power density. It is 875 [W / kg], which is superior to 535 [W / kg] of lead acid battery, and the cycle life that reaches 80% of the maximum discharge capacity is also 500 times or more. There is a relatively stable advantage compared to. In addition, since nickel / zinc secondary batteries using zinc as the negative electrode active material have an advantage of low cost, they may be widely used as secondary batteries for stationary power storage as well as for driving. However, in such an alkaline zinc secondary battery, since the zinc anode is dissolved in an alkaline solution and the elution and precipitation of zinc are repeated in the charging / discharging reaction, the shape of the electrode plate changes as the charging / discharging reaction proceeds, and the eluted zinc is charged. It has a disadvantage in that the life span is short because the dendritic zinc does not uniformly precipitate and grows dendritic and penetrates the separator to cause a short circuit of the battery.

The prior art for solving this problem will be described below.

Japanese Patent Laid-Open No. 1985-185372 discloses a nickel / zinc secondary battery in which oxides and hydrates of In and Ti are added to zinc electrodes to maintain high energy density in order to increase the number of charge / discharge cycles of the nickel / zinc secondary battery. Doing.

Japanese Patent Laid-Open No. 1987-108467 includes a zinc electrode in which an indium metal, an indium oxide, and thallium is added to a zinc electrode to increase the number of charges and discharges of an alkaline zinc battery, and the electrolyte is applied to an alkali zinc battery containing germanium ions. Is disclosed.

Japanese Patent Laid-Open No. 1986-061366 discloses an alkali zinc battery in which an inert, non-conductive organic compound is added to a zinc electrode in order to prevent deformation of the zinc electrode plate and increase the number of charge and discharge in the alkali zinc battery.

PCT / US2004 / 026859 discovered agglomeration of zinc oxide particles in the production of negative electrode slurry or paste of nickel / zinc secondary battery, which caused degradation of battery performance. . However, as long as the dispersant does not decompose, it can also have a negative effect on the cell reaction. Therefore, the zinc anode prepared using the dispersant should be heat-treated at 300 ° C. or higher in a vacuum and an inert gas atmosphere. However, such an increase in process leads to excessive process cost and process inefficiency, and the heat-treated electrode can close pores, making it difficult to guarantee battery performance. In addition, PCT / US2004 / 026859 describes a method for manufacturing a nickel / zinc secondary battery in which a separator layer is used to prevent the formation of dendritic crystals on the negative electrode of a nickel / zinc secondary battery and boric acid and a fluoride are included in the potassium hydroxide electrolyte. It is starting.

US 6,649,305 B1 points out that the conductivity of zinc oxide is very low and suggests the use of conductive ceramics as a way to improve it. However, when the conductive ceramic is used, there is a problem in that the aggregation of the active materials may not be improved when the slurry or the paste is prepared.

The above-mentioned prior art has proposed various methods for solving the problems of the nickel / zinc secondary battery, but did not obtain satisfactory results such as the effect is insignificant and the production cost is increased.

While the present inventors are studying a more effective method for solving such a problem, in the formation of a zinc anode of a nickel / zinc secondary battery, an active carbon or graphite powder such as acetylene black is mixed with a cathode active material, such as a ball milling method, or the like. It was confirmed that the conductivity can be improved and the agglomeration phenomenon in the paste can be improved. In addition, when the lamination method of laminating a separator on the cathode and applying heat and pressure to the cathode instead of the conventional envelope when forming the cathode separator is used, a dense interface is formed between the cathode and the separator so that the charge / discharge reaction is performed. It has been found that the solubility in alkaline electrolyte solution can be increased to increase battery life and charge / discharge efficiency, thereby completing the present invention.

An object of the present invention is to improve the agglomeration phenomenon when forming a paste containing an active material during the formation of the negative electrode, and also to prevent the deformation of the negative electrode or the formation of dendritic crystals generated by dissolving the negative electrode in the alkaline electrolyte solution, and the battery life and charge / discharge The present invention provides a method for manufacturing a nickel / zinc secondary battery capable of improving efficiency and a nickel / zinc secondary battery manufactured using the same.

In order to achieve the above object, the present invention comprises the steps of mixing the (S1) negative electrode active material and activated carbon or graphite powder by a ball mill method; (S2) after wetting the mixture prepared in step (S1), preparing a slurry by adding a thickener; (S3) preparing a composition for forming a negative electrode by adding a binder to the slurry; (S4) coating the negative electrode forming composition on a current collector; (S5) drying the composition for forming a negative electrode coated on the current collector to form a negative electrode; (S6) the separator is a porous ceramic or silica; bookbinder; Or coating with a dispersion in which the thickener is dispersed, followed by drying; And (S7) provides a method for producing a nickel / zinc secondary battery comprising the step of pressing the separator by applying heat and pressure to the negative electrode formed in step S5.

The anode active material may be one or more selected from the group consisting of zinc oxide, calcium zincate, and zinc (Zn) powder.

The activated carbon may be used one or more selected from the group consisting of acetylene black and Ketjen black.

The thickener may be used one or more selected from the group consisting of CMC, HEC and acrylic acid esters, the thickener may be substituted with K +, Na + ions.

The binder may include PTFE, PE, SBR, and the like.

The content ratio of the negative electrode active material and the activated carbon in the mixture prepared in step (S1) is 95 to 99% by weight and 1 to 5% by weight, respectively.

The porous ceramic or silica may be included in the dispersion in an amount of 1 to 10 parts by weight based on the average active material per sheet of negative electrode.

The dispersion may further comprise PE powder and calcium hydroxide.

The calcium hydroxide may be included in the dispersion in an amount of 1 to 10 parts by weight based on the average active material per sheet of negative electrode.

According to the manufacturing method of the nickel / zinc secondary battery of the present invention, it is possible to improve the agglomeration phenomenon when forming the paste containing the active material in the negative electrode formation process, and to form a dense interface by pressing the separator and the negative electrode by lamination method to form a negative interface It is possible to provide a nickel / zinc secondary battery capable of improving the lifespan and charging / discharging efficiency of a battery by preventing form deformation or dendritic crystal formation of a negative electrode generated by dissolving in an alkaline electrolyte solution.

The present invention,

(S1) mixing the negative electrode active material and activated carbon or graphite powder by a ball mill method;

(S2) after wetting the mixture prepared in step (S1), preparing a slurry by adding a thickener;

(S3) preparing a composition for forming a negative electrode by adding a binder to the slurry;

(S4) coating the negative electrode forming composition on a current collector;

(S5) drying the composition for forming a negative electrode coated on the current collector to form a negative electrode;

(S6) the separator is a porous ceramic or silica; bookbinder; Or coating with a dispersion in which the thickener is dispersed, followed by drying; And

(S7) compressing the separator by applying heat and pressure to the cathode formed in the step S5;

It provides a method of manufacturing a nickel / zinc secondary battery comprising a.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

A method of manufacturing a nickel / zinc secondary battery will be briefly described with reference to FIGS. 1 and 2. 1 is a view schematically illustrating a structure of a nickel / zinc secondary battery manufactured by compressing a separator according to an embodiment of the present invention to a negative electrode. FIG. 2 is a view schematically showing a state in which a cathode and a separator in which a cathode is compressed are stacked in a nickel / zinc secondary battery according to an embodiment of the present invention.

First, an electrode is manufactured. An electrode can be manufactured by forming a composition for electrode formation using a negative electrode or a positive electrode active material, a thickener, and a binder, apply | coating this composition for electrode formation to a collector, and drying. When the electrode is formed as described above, the separator is pressed by applying heat and pressure to the electrode to expose the terminal. Subsequently, nickel / zinc secondary batteries can be manufactured by mounting these electrodes in a case, injecting electrolyte, and sealing the same. In this case, as illustrated in FIG. 2, the capacity of the battery may be increased by alternately stacking the negative electrode and the positive electrode.

Next, a method of manufacturing the nickel / zinc secondary battery of the present invention will be described with reference to FIGS. 3 to 4. 3 is a process diagram illustrating a process of manufacturing a nickel / zinc secondary battery according to a method of manufacturing a nickel / zinc secondary battery according to an embodiment of the present invention. 4 is a view schematically showing a process of compressing the separator on the cathode in step (S6).

Referring to FIG. 3, first, an anode active material and activated carbon or graphite powder are mixed by a ball mill method (S1).

As the negative electrode active material, for example, one or more selected from the group consisting of zinc oxide, calcium zincate, and zinc (Zn) powder may be used.

As the activated carbon, for example, one or more selected from the group consisting of acetylene black and Ketjen black may be used. Activated carbon and graphite are preferably used in the form of a powder having an average particle diameter of less than 10 ㎛.

In the method of manufacturing a nickel / zinc secondary battery of the present invention, the conductivity of an electrode may be improved by mixing activated carbon or graphite with an active material by using a ball mill method, and the active material may be prevented from aggregating in a slurry or paste during electrode production. . Activated carbon, such as acetylene and Ketjen black, has a very large volume, which leads to a decrease in tap density when used as a conductive agent. Decreasing the tap density reduces the energy density of the cell, so the tap density must be maintained to the maximum. When the ball mill method is used, the active material and the activated carbon may be physically strongly bonded and the aggregation may be prevented while maintaining the maximum tap density.

The content ratio of the negative electrode active material and the activated carbon in the mixture prepared in step (S1) is preferably 95 to 99% by weight and 1 to 5% by weight, respectively. If the content of activated carbon exceeds 5% by weight, the energy density of the electrode is reduced, and if it is less than 1% by weight, the conductivity of the electrode decreases, which is not preferable.

In this step, an additive may be added and mixed with the negative electrode active material and the activated carbon. Examples of the additive include a metal oxide represented by Ca (OH) ₂ , Bi ₂ O ₃ , Tl ₂ O ₃ , In ₂ O _3, and SnO. Can be used. Ca (OH) ₂ may be used to prevent the phenomena of melting zinc ions into the electrolyte, and metal oxides such as Bi ₂ O ₃ may be used to reduce the amount of gas generated by increasing hydrogen overvoltage.

Next, after wetting the mixture prepared in step (S1), a thickener is added to prepare a slurry (S2).

As the thickener, for example, one or more selected from the group consisting of CMC, HEC and acrylic acid esters can be used.

The method of manufacturing the nickel / zinc secondary battery may further include replacing the thickener with K + and Na + ions.

In the case of Ca (OH) ₂ , an additive used to prevent the melting of the zinc ions after charging, it is rapidly agglomerated by reacting with an aqueous binder, but this phenomenon can be solved by using the method of manufacturing the secondary battery of the present invention. It can be improved. However, the aggregation of a small amount of Ca (OH) ₂ may also affect the performance of the battery, it can be solved by replacing the thickener with K +, Na + ions. This step can be done by adding potassium hydroxide, sodium hydroxide solution, etc. to the thickener.

The amount of the thickener added in this step is preferably 0.5 to 5% by weight based on the mixture consisting of the negative electrode active material and activated carbon. If the amount of the thickener is more than 5% by weight, the viscosity of the slurry becomes high, so that it is difficult to coat the current collector, the electrode resistance is increased, and the battery performance is deteriorated. It is not desirable.

Next, a binder is added to the slurry to prepare a composition for forming a negative electrode (S3).

PTFE, PE, SBR, etc. may be used as the binder.

The amount of the binder added in this step is preferably 0.5 to 5% by weight based on the mixture consisting of the negative electrode active material and activated carbon. If the amount of the binder is more than 5% by weight, the viscosity of the slurry becomes high, the electrode resistance is increased, and the battery performance is deteriorated. If the amount of the binder is less than 0.5% by weight, the binding performance between the current collector and the other negative electrode active material decreases, thereby deteriorating the battery performance. There is a problem of dissolving in electrolyte solution, which is not preferable.

Next, the negative electrode forming composition is coated on a current collector (S4), and the negative electrode forming composition coated on the current collector is dried to form a negative electrode (S5).

After coating and drying the composition for forming a cathode, the prepared electrode may be subjected to roll pressing. Through the roll pressing step, the active material, the activated carbon, and the like may be more tightly bonded. As the current collector, a metal sheet, an expanded metal, a punched metal, a metal foam, or the like may be used.

Next, the porous ceramic or silica in the separator; After coating with a dispersion in which the binder or thickener is dispersed (S6). More specifically, in the present invention, in order to prevent dendrite formation due to dissolution of the negative electrode, the separator is applied to the negative electrode by applying heat and pressure, and at least one sheet is preferably used as the negative electrode separator. At this time, the separation membrane is composed of a fine porous membrane and the pores may be closed by heat when pressed to the cathode. In the present invention, in order to maintain the porosity of the separator (porosity), the porous ceramic or silica is uniformly dispersed in a binder including PTFE, PE, SBR, etc. and thickeners such as CMC, HEC and acrylic esters, and then on the surface of the separator After coating, dry it. As described above, when the dispersion is coated on the surface of the separator, the pore water closed by heat and pressure may be considerably reduced to about 5 to 20% of the pore water of the separator before applying heat. The porous ceramic or silica is preferably contained in an amount of 1 to 10 parts by weight based on the average active material per sheet of negative electrode.

In addition, the dispersion is a calcium hydroxide (Ca (OH) ₂ ), etc. to prevent the dissolution in the alkaline solution by chemically bonding to the filling product of the zinc powder and PE powder binding ability increases when the heat is applied to the separator to better adhere to the negative electrode This may be added and then coated on the separator. The calcium hydroxide is preferably contained in an amount of 1 to 10 parts by weight based on the average active material per sheet of negative electrode.

Finally, the separator is pressed by applying heat and pressure to the cathode prepared in step S5 (S7). Referring to FIG. 4, in step S5, the separator 107 is positioned on both surfaces of the cathode 103, and then compressed by applying heat and pressure. The pressing process may be performed using a heating roll press, a heating plate press, or the like. The pressing process is preferably carried out under the conditions of the temperature of 70 ~ 120 ℃, 50 ~ 500 kgf / cm ² applied pressure, heat bonding time for 5 ~ 180 seconds.

As such, the membrane is pressed to the cathode by a lamination method to form a dense interface, so that the solubility in the alkaline solution is reduced during the charge / discharge reaction than the cathode using the separator having a conventional envelope-type structure, and thus the battery life and charge / The discharge efficiency can be greatly improved.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

< Example >

Example  One

1764 g of ZnO, 40 g of AB, 44 g of Ca (OH) ₂ , and 72 g of Bi ₂ O ₃ were placed in a vessel and ball milled at 180 rpm for 3 hours, and then passed through a sieve to separate the negative electrode material and the ball. The prepared negative electrode material was wetted using distilled water, and then substituted CMC was added to form a viscous slurry. Thereafter, the binder was added and stirred in the order of PTFE, PE, and SBR, and the prepared negative electrode composition was coated on a foam current collector. The coated electrode was dried in an oven at 90 ° C. for 2 hours, and then roll-pressed to reach 30% of the initial thickness to form a cathode. Thereafter, the separator Celgard 3407 surface was coated with a dispersion in which porous ceramics, calcium hydroxide, PTFE and CMC were uniformly dispersed, and then dried. The negative electrode formed above was placed between the separators prepared as described above, and the negative electrode was formed by pressing for 10 seconds at a temperature of 90 ° C. and 100 kgf / cm ² using a heating roll press. The content ratio of the materials used in the preparation of the negative electrode is shown in Table 1 below.

ZnO AB Ca (OH) ₂ Bi ₂ O ₃ PTFE PE SBR CMC Furtherance(%) 88.2 2.0 2.2 3.6 0.6 2.0 0.4 1.0

On the other hand, 3657 g of Ni (OH) ₂ , 116 g of Ni powder, and 116 g of CoO were put into a mixer, and CMC was added to form a viscous slurry. Here, a binder was added and stirred in the order of PTFE and PE to prepare a composition for forming an anode, which was coated on a current collector. The coated electrode was dried in an oven at 90 ° C. for 2 hours, roll-rolled to 30% of the initial thickness, and an anode was formed by covering an envelope-type separator. In this case, two separator sheets of NKK non-woven were used. The content ratio of the materials used in the production of the positive electrode is shown in Table 2 below.

Ni (OH) ₂ Ni powder CoO PTFE PE CMC Furtherance(%) 91.43 2.9 2.9 0.6 1.97 0.2

The produced positive electrode and negative electrode were laminated alternately to constitute a battery having a desired capacity. A battery having a capacity of 50 Ah could be manufactured by stacking 11 positive electrodes and 12 negative electrodes. Subsequently, the stacked electrode plates were placed in a battery case, covered, and then alkaline electrolyte was injected, aged for 1 hour in a vacuum state and 6 hours at room temperature, and then the battery was activated to complete an alkali nickel / zinc secondary battery. .

1 is a view schematically illustrating a structure of a nickel / zinc secondary battery manufactured by compressing a separator according to an embodiment of the present invention to a negative electrode.

FIG. 2 is a view schematically showing a state in which a cathode and a separator in which a cathode is compressed are stacked in a nickel / zinc secondary battery according to an embodiment of the present invention.

3 is a process diagram illustrating a process of manufacturing a nickel / zinc secondary battery according to a method of manufacturing a nickel / zinc secondary battery according to an embodiment of the present invention.

4 is a view schematically illustrating a process of compressing a separator on a cathode.

Explanation of symbols on the main parts of the drawings

101: case 103: cathode

105: anode 107: separator

     109: negative terminal 111: positive terminal

Claims (11)

(S1) mixing the negative electrode active material and activated carbon or graphite powder by a ball mill method; (S2) after wetting the mixture prepared in step (S1), preparing a slurry by adding a thickener; (S3) preparing a composition for forming a negative electrode by adding a binder to the slurry; (S4) coating the negative electrode forming composition on a current collector; (S5) drying the composition for forming a negative electrode coated on the current collector to form a negative electrode; (S6) the separator is a porous ceramic or silica; bookbinder; Or coating with a dispersion in which the thickener is dispersed, followed by drying; And (S7) compressing the separator by applying heat and pressure to the cathode formed in the step S5; Method for producing a nickel / zinc secondary battery comprising a. The method of claim 1, The anode active material is a method of manufacturing a nickel / zinc secondary battery, characterized in that at least one member selected from the group consisting of zinc oxide, calcium zincate and zinc (Zn) powder. The method of claim 1, The activated carbon is a method for producing a nickel / zinc secondary battery, characterized in that at least one selected from the group consisting of acetylene black and Ketjen black. The method of claim 1, The thickener is a method for producing a nickel / zinc secondary battery, characterized in that at least one selected from the group consisting of CMC, HEC and acrylic acid ester. The method of claim 4, wherein Method of manufacturing a nickel / zinc secondary battery, characterized in that the thickener is substituted with K +, Na + ions. The method of claim 1, The binder is a method for producing a nickel / zinc secondary battery, characterized in that it comprises at least one selected from the group consisting of PTFE, PE and SBR. The method of claim 1, Content ratio of the negative electrode active material and activated carbon in the mixture prepared in the step (S1) is 95 to 99% by weight and 1 to 5% by weight of the manufacturing method of the secondary battery. The method of claim 1, The porous ceramic or silica is a nickel / zinc secondary battery manufacturing method, characterized in that included in the dispersion in an amount of 1 to 10 parts by weight based on the average active material per sheet. The method of claim 1, The dispersion is a method of producing a nickel / zinc secondary battery, characterized in that it further comprises a PE powder and calcium hydroxide. 10. The method of claim 9, The calcium hydroxide is a nickel / zinc secondary battery manufacturing method, characterized in that included in the dispersion in an amount of 1 to 10 parts by weight based on the average active material per sheet negative electrode. A nickel / zinc secondary battery manufactured using a method of manufacturing a nickel / zinc secondary battery selected from claims 1 to 10.

Images