KR20190131211A - Method for manufacturing lithium electrode of lithium battery using lithium metal as cathode - Google Patents

Abstract

The present invention relates to a method for manufacturing an electrode of a lithium battery using a lithium metal as a negative electrode to be easily manufactured and improve productivity through manufacture of aligning a lithium foil and a metal foam sheet to be overlapped and heating the same using an induction heating method. The method comprises the following steps: aligning the lithium foil and the metal foam sheet to be overlapped; after the lithium foil and the metal foam sheet are aligned, heating the metal foam sheet using the induction heating method, melting the lithium foil through surface modification of the metal foam sheet and impregnating the melted lithium in the metal foam sheet; and after the melted lithium is impregnated in the metal foam sheet, cooling the same and manufacturing a lithium electrode.

Description

Method for manufacturing lithium electrode of lithium battery using lithium metal as cathode}

The present invention relates to a method of manufacturing an electrode of a lithium battery using lithium metal as a negative electrode, and in particular, the surface of the current collector is modified by preferentially and directly heating only a magnetic electrode current collector using a lithium foil and a metal foam by an induction heating method. In the lithium metal electrode, a method of manufacturing an electrode of a lithium battery using lithium metal having a uniform composition as a cathode by minimizing volatilization of lithium by melting lithium by heat generated from a heated metal foam. will be.

The lithium secondary battery includes a positive electrode, a negative electrode, an electrolyte and a separator. The negative electrode current collector of the lithium secondary battery may be manufactured using Sus mesh, Ni mesh, Cu mesh, Cu foil, and metal foam. A related technique for producing an electrode is disclosed in Korean Patent Publication No. 10-1353262 (Patent Document 1).

Korean Patent Publication No. 10-1353262 relates to a metal foam for a lithium secondary battery electrode, a method for manufacturing a metal foam, and a lithium secondary battery including a metal foam. The metal foam for lithium secondary battery electrodes disclosed in Korean Patent Publication No. 10-1353262 is a metal foam for lithium secondary battery electrodes in which part or all of the surface and internal pore walls are coated with an active material, and the active material is a binder or a conductive material. It is coated to directly contact the surface of the metal foam and the inner pore wall without involvement. As the negative electrode active material, carbon, such as graphite, is used.

In order to improve the charging speed in the lithium secondary battery, the improvement of the performance of the negative electrode active material is the key, and the charging speed depends on the microstructure and inherent physical properties of the negative electrode material. In recent years, new high-capacity anode materials have been actively researched, and among them, lithium metal anodes have been actively studied because they have excellent characteristics in terms of energy density determined by capacity and operating voltage.

 In the electrode manufacturing method of a battery using lithium metal as a negative electrode, a lithium foil is used as an active material and a metal mesh or a metal foam is physically compressed as an electrode current collector to form an electrode. There is a way.

The method for manufacturing an electrode of a lithium secondary battery using the metal foam disclosed in Korean Patent Publication No. 10-1353262 is formed by coating an active material on the metal foam. Conventional methods for manufacturing electrodes of lithium secondary batteries, that is, lithium batteries using the metal foam disclosed in Korean Patent Publication No. 10-1353262, use an electrode current collector and an electrode active material by using a coating method when forming an active material on a metal foam. There is a problem that the adhesion or binding force of the liver may be lowered.

In the heat-activated non-storage type battery including the lithium-impregnated metal foam disclosed in Korean Patent Publication No. 10-1449597, the energy density and high output characteristics may be improved by impregnating the lithium metal foam, but due to the low wettability of lithium. The molten eutectic salt is coated on the metal foam, and the molten lithium is impregnated by raising the temperature to 400-600 ° C. in an inert gas atmosphere.

However, this method requires a step of coating the eutectic salt for electrode production, and thus the productivity is low. Since the melting point of lithium is approximately 180 ° C., a large amount of lithium is volatilized in the temperature range of 400 to 600 ° C., thereby controlling the electrode composition. Is difficult. In order to solve such a problem, when the impregnation temperature is lowered, since the surface modification of the electrode current collector for impregnating the molten lithium into the metal current collector takes a lot of time, the productivity is greatly reduced.

1): Korea Patent Publication No. 10-1353262 : Korean Registered Patent Publication No. 10-1449597

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, by modifying the surface of the current collector by preferentially and directly heating only the magnetic electrode current collector of the lithium foil and the metal foam by the induction heating method, and occurs in the heated metal foam The molten lithium can be easily impregnated by the molten lithium by the heat generated, and to minimize the volatilization of the negative electrode active material to provide an electrode manufacturing method of a lithium battery using a lithium metal having a uniform composition as a negative electrode.

Another object of the present invention is easy to manufacture and improve productivity by heating by using an induction heating method in a state in which the lithium foil and the metal foam sheet are aligned to overlap each other. The present invention provides a method for manufacturing an electrode of a lithium battery using lithium metal as a negative electrode.

Still another object of the present invention is to provide a uniform formation of lithium in the metal foam by using an induction heating method electrode of a lithium battery using lithium metal as a negative electrode that can improve the ESR (equivalent series resistance) characteristics of the lithium electrode To provide a manufacturing method.

Electrode manufacturing method of a lithium battery using a lithium metal of the present invention as a negative electrode comprising the steps of aligning the lithium foil (lithium foil) and the metal foam sheet (metal foam sheet) overlap each other; When the lithium foil and the metal foam sheet are aligned, heating the metal foam sheet by an induction heating method to melt the lithium foil through surface modification of the metal foam sheet so that molten lithium is impregnated into the metal foam sheet; And cooling the molten lithium when the metal foam sheet is impregnated to produce a lithium electrode.

In the method of manufacturing an electrode of a lithium battery using the lithium metal of the present invention as a negative electrode, the surface of the current collector is modified by directly and directly heating only the magnetic electrode current collector using the induction heating method of the lithium foil and the metal foam, and the heated metal Lithium is melted by the heat generated in the foam, so that molten lithium can be easily impregnated, and minimization of volatilization of the negative electrode active material can produce electrodes of a lithium battery having a uniform composition, and a lithium foil and a metal foam sheet. Is manufactured by heating using an induction heating method in a state in which they are arranged so as to overlap each other, and there is an advantage in that it is easy to manufacture and improves productivity.The lithium can be uniformly formed in the metal foam using the induction heating method. The advantage of improving the equivalent series resistance (ESR) characteristics of the electrode have.

1 is a process chart showing the flow of the electrode manufacturing method of a lithium battery using the lithium metal of the present invention as a negative electrode,
FIG. 2 is a cross-sectional view of a lithium foil and a metal foam sheet used in a method of manufacturing an electrode of a lithium battery using the lithium metal shown in FIG. 1 as a negative electrode;
3 is a cross-sectional view of a metal foam sheet showing a method of pressing the metal foam sheet shown in FIG. 2 by a rolling method;
4 is a cross-sectional view illustrating a state in which the lithium foil and the metal foam sheet illustrated in FIG. 2 are aligned to overlap each other;
FIG. 5 is a cross-sectional view illustrating a schematic configuration of an induction heating apparatus used to melt the lithium foil and the metal foam sheet shown in FIG. 4. FIG.

Hereinafter, an embodiment of an electrode manufacturing method of a lithium battery using the lithium metal of the present invention as a negative electrode will be described with reference to the accompanying drawings.

1 and 2, the electrode manufacturing method of the lithium battery using the lithium metal of the present invention as a negative electrode, first, the pressing process to reduce the particle diameter (D1), that is, the pore 21 of the metal foam, The process will be described later. The lithium foil 10 and the metal foam sheet 20 are aligned to overlap each other (S10). When the lithium foil 10 and the metal foam sheet 20 are aligned, the metal foam sheet 20 is heated by an induction heating method to melt the lithium foil 10 through surface modification of the metal foam sheet 20, thereby melting molten lithium metal To be impregnated in the foam sheet 20 (S20). When the molten lithium is impregnated in the metal foam sheet 20 to cool to produce a lithium electrode (not shown) (S30).

An embodiment of an electrode manufacturing method of a lithium battery using the lithium metal of the present invention as a negative electrode will be described in detail.

In order to arrange the lithium foil 10 and the metal foam sheet 20 so as to overlap each other (S10), first, the lithium foil 10 is prepared as shown in FIGS. 1 and 2. (S11). In step S11 of preparing the lithium foil 10, a material of the lithium foil 10 is lithium (Li). That is, the lithium foil 10 is manufactured and prepared in a foil shape using lithium (Li).

When the lithium foil 10 is prepared, as shown in FIGS. 1 and 2, the metal foam sheet 20 is prepared (S12). In the step of preparing the metal foam sheet 20 (S12), the metal foam sheet 20 is formed with a plurality of pores (21) having an average particle diameter of 50 to 500㎛, the material is stainless (Sus), nickel One of (Ni) and iron (Fe) is selected and used, or two or more are mixed and used. For example, the metal foam sheet 20 is mixed with one or two or more of stainless (Sus), nickel (Ni) and iron (Fe) so that the plurality of pores 21 has an average particle diameter (D1) of 50 to 500㎛ Formed to be, the manufacturing method of the metal foam sheet 20 is omitted because the known method is applied.

When the lithium foil 10 and the metal foam sheet 20 are prepared, the metal foam sheet 20 is pressed using a rolling method as shown in FIGS. 1 and 3 (S13). That is, in step S13, pressing is performed using a rolling method so that the average particle diameter D1 of the plurality of pores 21 formed in the metal foam sheet 20 is reduced. For example, in step S13, the thickness T2 of the metal foam sheet 20 is greater than the thickness T1 of the lithium foil 10 or the average of the plurality of pores 21 formed in the metal foam sheet 20. It is performed when the particle diameter (D1) is 50 to 500㎛, on the contrary, the thickness T2 of the metal foam sheet 20 is smaller than the thickness T1 of the lithium foil 10 or the average particle diameter D2 is 20 to 45 In the case of 占 퐉, this step S13 can be omitted. In the method of performing the step S13, the metal foam sheet 20 has a thickness T2 greater than the thickness T1 of the lithium foil 10 or an average particle diameter D1 of the plurality of pores 21 is 50 to 500 μm. In the case of using a rolling method, the thickness is smaller than the thickness T1 of the lithium foil 10 and is pressed so that the particle diameters D2 of the plurality of pores 21 are 20 to 45 µm or less.

The rolling method uses the rolling device 110 shown in FIG. Rolling apparatus 110 comprises a pair of rollers (111, 112), the thickness (T2) of the metal foam sheet 20 by passing the metal foam sheet 20 between a pair of rollers (111, 112) The thickness T3 or the particle diameter D2 of the pore 21 is 20 to 45 µm. The thickness T3 of the metal foam sheet 20 is set to be smaller than the thickness T1 of the lithium foil 10, and forming the particle diameter D2 of the pore 21 to be 20 to 45 μm may include a lithium foil ( This is to prevent the lithium (Li) from leaving the metal foam particle diameter (D1) after 10) is melted, and to be evenly mixed with the metal constituting the metal foam sheet 20. That is, since the thickness T3 of the metal foam sheet 20 is formed to be smaller than the thickness T1 of the lithium foil 10, the metal foam sheet 20 may be melted evenly and rapidly melted, and the pores 21 may be melted. By pressing the rolling method so that the particle diameter (D2) of 20) is 20 to 45㎛, the lithium foil 10 is melted in each of the pores 21 so that the lithium foil 10 is not uniformly mixed in one part when mixing. That is, the lithium foil 10 and the metal foam sheet 20 may be uniformly melted and mixed with each other.

The metal foam sheet 20 to which the rolling method is applied is aligned with the lithium foil 10 and melted to compress the metal foam sheet 20 at the time of mixing, and then, within 1 hour, the metal foam sheet 20 by the induction heating method. 20 is heated to modify the surface of the metal foam sheet 20, and then the high temperature metal foam sheet 20 causes the lithium foil 10 to be melted, and then the lithium foil 10 is formed of the metal foam sheet ( 20) impregnated and mixed.

When the metal foam sheet 20 is compressed, the lithium foil 10 and the metal foam sheet 20 are aligned to overlap each other as shown in FIGS. 1, 3, and 4 (S14). In the step S14 of aligning the lithium foil 10 and the metal foam sheet 20 to overlap each other, a pair of metal foam sheets 20 is provided, and the pair of metal foam sheets 20 is a lithium foil 10 Lithium foil 10 is disposed between the pair of metal foam sheets 20 by being positioned on one side of the surface and the other side of the side) so that the lithium foil 10 and the pair of metal foam sheets 20 Aligned to overlap.

When the lithium foil 10 and the metal foam sheet 20 are aligned, the metal foam sheet 20 is first heated by the induction heating method as shown in FIGS. 1, 4, and 5 to surface modification. Proceeding thereafter, the lithium foil 10 is melted by the heated metal foam sheet 20 so that the molten lithium is impregnated into the metal foam sheet 20 and mixed. That is, the lithium foil 10 is melted through the surface modification of the metal foam sheet 20 by induction heating, so that the molten lithium is impregnated in the metal foam sheet 20 (S20). The step S20 of impregnating the molten lithium into the metal foam sheet 20 through surface modification of the metal foam sheet 20 may be performed such that the lithium foil 10 and the compressed metal foam sheet 20 overlap each other. In the induction heating method using the induction heating apparatus 120 in the heated state, the metal foam sheet 20 is directly heated and melted, and the molten lithium is generated in the lithium foil 10 by heat generated from the heated metal foam sheet 20. The molten lithium is impregnated with the metal foam sheet 20 to be uniformly mixed (S21). For example, the method of uniformly mixing the lithium foil 10 and the metal foam sheet 20 is the induction heating method using the induction heating device 120 to directly heat the metal foam sheet 20 to modify the surface Heat conduction, that is, the lithium foil 10 is melted by the heat generated from the heated metal foam sheet 20 so that the lithium foil 10 may be uniformly impregnated in the metal foam sheet 20, and the lithium foil 10 By eliminating the time difference between the melting of the metal foam sheet and the metal foam sheet 20 by improving the wettability of lithium (Li) by surface modification through heating the metal foam sheet 20, it is possible to easily impregnate lithium (Li), The lithium foil 10 and the metal foam sheet 20 may be uniformly mixed by easily impregnating lithium (Li) by surface modification by melting the metal foam sheet 20. That is, the lithium foil 10 has a melting point at 180 ° C., and when the iron (Fe) is used as the metal foam sheet 20, for example, the metal foam sheet 20, the metal foam sheet 20 is 400 ° C. By having the melting point above, the lithium foil 10 and the metal foam sheet 20 are introduced into the induction heating apparatus 120 having an argon (Ar) atmosphere, and then the induction heating apparatus 120 is operated to operate the lithium foil 10. ), The metal foam sheet 20 can be made uniformly impregnated. When the molten lithium is uniformly mixed with the metal foam sheet 20, the metal foam sheet 20 and the lithium foil 10 mixed with molten lithium are pressed using a press 130 (S22).

In the step S22 of pressing the metal foam sheet 20 and the lithium foil 10 in which the molten lithium is mixed, the press 130 is disposed above the induction heating apparatus 120 and induction using the induction heating apparatus 120. The metal foam sheet 20 is directly heated to 180 to 350 ° C. by a heating method to modify the surface modification of the metal foam sheet 20, and the metal foam sheet 20 heated through the surface modification of the metal foam sheet 20. The molten lithium is mixed in a state in which molten lithium is uniformly mixed with the metal foam sheet 20 by improving the wettability of the molten lithium by melting the lithium foil 10 by the heat conduction of heat generated in the molten lithium to generate molten lithium. The metal foam sheet 20 is pressed. For example, the press 130 is disposed above the induction heating apparatus 120 so that the metal foam sheet 20 is preferentially heated by the induction heating apparatus 120 so that the surface of the metal foam sheet 20 may be lithium. The foil 10 is melted and pressed so that molten lithium is uniformly impregnated so that a lithium electrode 10 may be manufactured in a state in which the lithium foil 10 is uniformly impregnated in the metal foam sheet 20.

Induction heating apparatus 120 used in the induction heating method includes a magnetic container 121, an insulating plate 122, a lower case 123 and a coil 124 as shown in FIG. The magnetic body 121 is formed in a cylindrical shape with an open top, a non-magnetic material is used, the lithium foil 10 and the metal foam sheet 20 is disposed inside, the press 130 is disposed on the upper side. The connection between the press 130 and the magnetic container 121 is omitted because the known technique is applied, the lifting movement of the press 130 is driven using a linear transfer mechanism (not shown). The insulating plate 122 is disposed between the magnetic container 121 and the lower case 123, and the coil 124 is disposed inside the lower case 123. The coil 124 generates a magnetic force line 124a when a current is applied from the outside, and the generated magnetic force line 124a directly heats the metal foam sheet 20 or the press 130 to form the lithium foil 10 and the metal foam sheet. By melting (20), the temperature gradient can be made uniform so that lithium (Li) and iron (Fe) can be uniformly mixed and melted. Herein, lithium (Li) is a material melted in the lithium foil 10, and iron (Fe) is a material melted in the metal foam sheet 20.

The molten lithium foil 10 is impregnated into the metal foam sheet 20 whose surface is modified by the induction heating apparatus 120 and the press 130 and mixed, that is, the lithium foil 10 is mixed with the metal foam sheet 20. When impregnated in and mixed to produce a lithium electrode (not shown) by cooling as shown in Figure 1 (S30). When the molten lithium foil 10 is impregnated and mixed in the surface-modified metal foam sheet 20 and cooled to prepare a lithium electrode (S30), the lithium electrode is melted in the surface-modified metal foam sheet 20. When the lithium foil 10 is impregnated, it is manufactured by cooling it using air.

In order to test the electrical test of the lithium electrode manufactured by the electrode manufacturing method of the lithium battery using the lithium metal of the present invention as a negative electrode, that is, the equivalent series resistance (ESR) characteristics of the lithium electrode, as shown in Table 1 The lithium secondary batteries according to 1 and 2 were prepared. In the lithium secondary battery according to the first embodiment, the particle diameter D2 of the formed pores 21 of the metal foam sheet 20 is 20 μm, and then the lithium foil 10 and the pair of metal foams are formed as shown in FIG. 4. After the sheet 20 was aligned, a lithium electrode was manufactured by heating to 180 ° C. using an induction heating apparatus 120 and a press 130, using the known method.

In the lithium secondary battery according to the second embodiment, the particle diameter D2 of the formed pores 21 of the metal foam sheet 20 is 45 μm, and then the lithium foil 10 and the pair of metal foams are formed as shown in FIG. 4. After the sheet 20 was aligned, a lithium electrode was manufactured by heating to 350 ° C. using an induction heating apparatus 120 and a press 130, using the known method.

Table 1 shows the results of testing the equivalent series resistance (ESR) characteristics of the lithium secondary batteries prepared after manufacturing the lithium secondary batteries according to Examples 1 and 2, respectively.

Heating temperature (℃) Pore average particle size (㎛) ESR (mΩ) Example 1 180 20 11 Example 2 350 45 13

As shown in Table 1, the lithium secondary battery according to Example 1 to which the lithium electrode manufactured by heating the particle diameter (D2) of the pore 21 to 20 μm and heated to 180 ° C., that is, the lithium battery was tested for the characteristics of the ESR. The lithium battery according to Example 1 to which the lithium electrode prepared by heating at 350 ° C. and having a particle diameter (D2) of the pore 21 having a diameter of 45 μm and heated to 350 ° C. was tested to have a characteristic of ESR and was measured to be 13 m ×. Lithium batteries to which the lithium electrodes prepared according to Examples 1 and 2 were applied, respectively, were tested for the characteristics of the ESR, it can be seen that it has excellent characteristics of the ESR.

That is, the electrode manufacturing method of the lithium battery of the present invention is manufactured by heating by using an induction heating method in a state in which the lithium foil 10 and the metal foam sheet 20 are aligned to overlap each other, thereby reducing the temperature rise time to manufacture the lithium electrode. It is easy to improve the productivity by reducing the resulting production cost and the surface modification through the preferential heating of the metal foam sheet 20 to improve the wettability of lithium (Li) to improve the lithium in the metal foam sheet 20 (Li) may be easily impregnated, and the lithium foil 10 and the metal foam sheet 20 may be easily impregnated with lithium (Li) by surface modification through preferential heating of the metal foam sheet 20. The uniform mixing allows lithium to be uniformly formed on the metal foam, thereby improving the ESR characteristics.

The electrode manufacturing method of a lithium battery using the lithium metal of the present invention as a negative electrode can be applied to the secondary battery manufacturing industry.

10: lithium foil
20: metal foam sheet
21: Fore
110: rolling apparatus
120: induction heater
130: press

Claims (7)

Aligning the lithium foil and the metal foam sheet to overlap each other;
When the lithium foil and the metal foam sheet are aligned, heating the metal foam sheet by an induction heating method to melt the lithium foil through surface modification of the metal foam sheet so that molten lithium is impregnated into the metal foam sheet; And
When the molten lithium is impregnated in the metal foam sheet, the method for producing a lithium battery using a lithium metal as a negative electrode comprising the step of cooling to produce a lithium electrode. The method of claim 1,
Aligning the lithium foil and the metal foam sheet to overlap each other may include preparing a lithium foil;
Preparing a metal foam sheet;
Pressing the metal foam sheet using a rolling method; And
Aligning the lithium foil and the compressed metal foam sheet to overlap each other;
In preparing the lithium foil, a material of the lithium foil is lithium (Li), and in preparing the metal foam sheet, the metal foam sheet has a plurality of pores having an average particle diameter of 50 to 500 μm. The material is selected from one of stainless steel (Sus), nickel (Ni) and iron (Fe) or used in combination of two or more, the metal foam sheet in the step of pressing the metal foam sheet using a rolling method A method of manufacturing an electrode of a lithium battery using lithium metal, which is pressed using a rolling method, as a negative electrode so that an average particle diameter of a plurality of pores becomes small. The method of claim 1,
In the step of arranging the lithium foil and the metal foam sheet to overlap each other, the metal foam sheet is provided with a pair, and the pair of metal foam sheets are positioned on one side and the other side of the lithium foil, respectively. A method of manufacturing an electrode of a lithium battery, wherein lithium metal is disposed between a pair of metal foam sheets so that the lithium foil and the pair of metal foam sheets are aligned to overlap each other. The method of claim 2,
In the step of pressing the metal foam sheet using a rolling method, the metal foam sheet is a negative electrode of lithium metal that is pressed to have a thickness smaller than the thickness of the lithium foil and a particle size of the plurality of pores is 20 to 45 μm using a press. Electrode manufacturing method of a lithium battery to be used as. The method of claim 1,
Melting the lithium foil through surface modification of the metal foam sheet so that the molten lithium is impregnated into the metal foam sheet
In the state in which the lithium foil and the pressed metal foam sheet are aligned to overlap each other, the metal foam sheet is directly heated by surface induction by an induction heating method using an induction heating apparatus, and the lithium foil is formed by heat generated from the heated metal foam sheet. Melting to generate molten lithium and allowing molten lithium to be impregnated into the metal foam sheet to be uniformly mixed; And
When the molten lithium is uniformly mixed to the metal foam sheet, a method of manufacturing an electrode of a lithium battery using a lithium metal as a negative electrode comprising the step of pressing a metal foam sheet mixed with a mixed molten lithium using a press (press). The method of claim 5,
The pressing of the molten lithium mixed metal foam sheet may include pressing the mixed metal foam sheet and the lithium foil using a press, and the press may be disposed on an upper side of the induction heating apparatus to use an induction heating apparatus. By heating the metal foam sheet to 180 to 350 ℃ to generate molten lithium through surface modification of the metal foam sheet to improve the wettability of the molten lithium, the molten lithium is uniformly mixed with the molten lithium in the metal foam sheet Electrode manufacturing method of a lithium battery using a lithium metal to press the mixed metal foam sheet as a negative electrode. The method of claim 1,
When the lithium foil is impregnated and mixed in the metal foam sheet to cool the lithium electrode to prepare a lithium electrode in the step of melting and mixing the lithium foil and the metal foam sheet using a lithium metal produced by cooling it using air as a cathode Electrode manufacturing method of a lithium battery.

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