WO2014121978A1

WO2014121978A1 - Electrode for a galvanic element and method for producing the electrode

Info

Publication number: WO2014121978A1
Application number: PCT/EP2014/050456
Authority: WO
Inventors: Markus Kohlberger
Original assignee: Robert Bosch Gmbh; Samsung Sdi Co., Ltd.
Priority date: 2013-02-05
Filing date: 2014-01-13
Publication date: 2014-08-14
Also published as: DE102013201853A1

Abstract

The invention relates to an electrode (2) for a galvanic element, said electrode having a porous collector matrix (4) into which at least one lithium layer or one lithium alloy layer (14, 34) is laminated. In addition, a galvanic element and a method for producing an electrode (2) for a galvanic element are provided.

Description

Description Electrode for a galvanic element and method for producing the electrode. Prior art

The invention relates to an electrode for a galvanic element and to a method for producing the electrode. Furthermore, a galvanic element is included with the electrode.

In the field of electrochemical energy storage, research has focused on lithium-based battery cells, which are currently the largest available

Have energy density at the lowest weight, especially in comparison to nickel or lead based batteries. Lithium-ion batteries can be used both in electrically powered vehicles, electric vehicles or hybrid vehicles, as well as in computer technology, especially in notebooks, smartphones or tablet PCs. DE 197 09 783 A1 shows a laminated lithium-ion cell, which consists of flexible layers, wherein the negative electrode is a metallic non-woven or a foam containing a lithium-intercalating material as an active component. As a current conductor, an electrically-chemically stable metallic grid or network is laminated. EP 0 864 389 B1 shows a process for producing a porous metal sheet, which is known as

Electrode substrate of a lithium secondary battery is used. In the production of the porous metal sheet, first, a metal powder is spread on a continuously transported conveyor belt and sintered in a sintering furnace so that the spaces between the metal powder particles become fine pores. In the pores, an active substance, for example, lithium or lithium oxides, introduced.

DE 102 01 936 A1 shows a rechargeable electrochemical battery cell, wherein the negative electrode has an electronically conductive substrate, on which an active mass is electrodeposited during charging of the cell. The cell has, in contact with the substrate of the negative electrode, a porous structure formed of solid particles, which is not generated by sintering. The solid particles forming the structure consist, for example, of a ceramic powder or of amorphous materials.

Disclosure of the invention

The invention is defined by the subject matter specified in the independent main claims, with advantageous embodiments being specified in the dependent claims. According to a first aspect, an electrode for a galvanic element comprises a porous collector matrix in which a lithium layer or lithium alloy layer is laminated. It is advantageously utilized that the lithium metal is firmly embedded in the porous collector matrix by the lamination, remains stable there and does not participate in the reaction during the charging / discharging cycle of the galvanic element.

Preferably, the porous collector matrix is made as a grid, a foam or a fabric. Foams, meshes and fabrics offer a high surface area at low weight, at which the lithium metal can deposit during charging. According to a preferred embodiment, the porous collector matrix is made of copper, nickel, aluminum, zinc or mixtures thereof. The porous collector matrix may also be made of alloys containing copper, nickel, aluminum and / or zinc. Alternatively it can be provided that the porous collector matrix is coated with copper, nickel, aluminum, zinc, or alloys containing copper, nickel, aluminum and / or zinc.

In order to improve the cyclability, the electrode may contain other metals, preferably indium, tin, gallium or thallium, with indium being particularly preferred. These may be added in the manufacture of the collector matrix or in the production of the lithium metal mass. Alternatively it can be provided to bring the other metals later. During the first discharge and charge process, the stable alloy forms from the lithium and the lithium stabilizing material, preferably indium.

Accordingly, it can be provided that the lithium alloy layer comprises an alloy with lithium and at least one metal from the following list: indium, tin, gallium or Thallium, with indium being preferred. Preferably, the further metal is in one

Concentration of 0 to 20%, typically 5%, wherein the percentage may refer to the total weight or volume of the lithium alloy layer. Alternatively, or in addition thereto, the porous collector matrix may comprise another metal from the following list: indium, tin, gallium or thallium, with indium being preferred. The further metal can be added to the porous collector matrix during production, for example by alloying, wherein preferably a concentration of 0 to 20%, particularly preferably 5% is present, the percentage being based on the

Total weight of the collector matrix or the volume of the collector matrix can relate. Alternatively or additionally, it may be provided to coat the porous collector matrix with at least one further metal from the following list: indium, tin, gallium or thallium, with indium being preferred. The coating can take place, for example, by means of a PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) method, PVD being preferred.

Alternatively, or in addition thereto, it may be provided that in the porous

At least one further metal layer or metal alloy layer is laminated to the collector matrix, wherein the metal or metal alloy comprises at least one metal from the following list: indium, tin, gallium or thallium, with indium being preferred. The

Concentration of the further metal may be between 0 and 20%, in particular 5%, wherein the percentage may refer to the total weight or the total volume of the porous collector matrix. According to a further aspect, the invention comprises a galvanic element with at least one of the described electrodes. The electrode can be used in the galvanic element both as an anode and as a cathode.

In particular, the electrode can be used in a lithium-air cell. In a lithium-air battery is compared to conventional lithium-ion technology, the

Cathode replaced by air. Metallic lithium is used as the negative electrode, and the positive electrode is oxygen (0 ₂ ) -based, whereby the oxygen can be supplied from the ambient air or added by machine. The electrode described above, serves as the anode, wherein only that metallic lithium can participate in the reaction, which does not interfere with the lithium-stabilizing metal in the porous collector matrix is involved. The use of the electrode according to the invention as metallic lithium anode can successfully counteract the so-called dendrite formation, ie a growth of lithium metal through the separator, whereby a higher number of cycles is achieved and security risks are reduced. The fact that the lithium is deposited on the porous collector matrix and not on a metal foil, forms a less spongy and porous structure of the lithium, especially an ordered structure. This prevents the lithium during the

Charging sponge-like or porous separates or reacts with the electrolyte. According to a further embodiment, the electrode can be used in a lithium-sulfur cell, wherein preferably an insert is provided on the sulfur side. In a lithium-sulfur battery, lithium is decomposed during the discharge at the anode and connected with sulfur. During the charging process, the resulting compound is released again and deposited at the anode lithium. The reaction corresponds to that of sodium-sulfur accumulators, with lithium assuming the function of sodium. The laminated lithium foil on the porous collector matrix ensures that an orderly growth of the lithium takes place on the sulfur side, which in practice is less sponge-like, which prevents dendrite formation. In another aspect, there is provided a method of making an electrode for a galvanic cell, comprising the steps of: a) providing a porous collector array;

b) providing a foil containing lithium;

c) laminating the foil containing lithium into the collector matrix so that the porous collector matrix is coated with lithium.

It can be provided that the collector matrix contains a lithium-stabilizing metal, or it can be provided that step a) comprises the further step: d) coating the collector matrix with a lithium-stabilizing metal. Alternatively, further steps may be provided, namely: e) providing a film with a lithium-stabilizing metal; f) laminating the foil with the lithium stabilizing metal into the collector matrix to form an alloy of the lithium with the lithium stabilizing metal.

Step f) can be carried out before or after step c) or simultaneously with step c). In a first charge / discharge cycle of the battery, the fusion of the lithium-stabilizing metal with the lithium occurs to a stable lithium-containing alloy.

According to a further embodiment it can be provided that step a) comprises the following steps: g) admixing a lithium-stabilizing metal into a lithium-containing metal, and

h) extruding as a lithium-containing film. Advantages of the invention

The invention provides electrodes that are particularly suitable for use in lithium-air batteries and lithium-sulfur batteries, the latter in particular on the sulfur side, since they cause a reduced dendrite growth. By

Lamination of a lithium foil on a porous collector matrix, possibly with a lithium-stabilizing metal, embedded a stable lithium layer in the porous collector matrix, which does not participate in the reaction. Due to the good electrical

Conductivity, the lithium deposits on this structure less porous and sponge-like, as would be the case with a metal foil. In particular, a larger number of charging / discharging cycles of the batteries can be achieved.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. Show it

1 shows an embodiment of a porous collector matrix with embedded therein

Lithium, FIG. 2 shows a schematic representation of a step of a production method of the electrode,

Figure 3 is a schematic representation of a further step of

Manufacturing method of the electrode,

Figure 4 is a schematic representation of a step of an alternative

Manufacturing process of the electrode, and

Figure 5 is a schematic representation of a manufacturing process of the porous

Collector array.

FIG. 1 schematically shows an electrode 2 with a collector matrix 4 and therein

embedded electrode mass 6. The collector matrix 4 is preferably made of or coated with copper, nickel, aluminum, zinc or alloys thereof. The

Collector 4 is here as a grid 3, but may also have a porous structure or a fabric structure. It may also contain another metal, wherein the further metal may also be present as a coating, wherein the further metal is preferably selected from the following list: indium, tin, gallium or thallium, preferably indium.

The electrode mass 6 comprises a lithium alloy or a lithium alloy with a lithium-stabilizing metal, wherein the lithium-stabilizing metal is preferably selected from the following list: indium, tin, gallium or thallium, preferably indium. The represented electrode 2 with the collector matrix 4 and the embedded electrode mass 6 is installed in a galvanic element, in particular as an anode in a lithium-air cell or in a lithium-sulfur cell on the sulfur side.

FIG. 2 shows a schematic representation of a process step for producing the electrode. A metallic foam, fleece or fabric 8 is preferably in a thickness of 50 to 200 μηι ago. Particularly preferred is a thickness of 100 to 150 μηι. The metallic foam, nonwoven or fabric 8 is the input product, and a laminated metallic foam, nonwoven or fabric 10 is the starting product of the illustrated process. The metallic foam, the fleece or the fabric 8 is for this purpose passed through a pair of rollers 12a, 12b, wherein between the metallic foam, non-woven or fabric 8 and the top roller 12a, a lithium foil 14 is guided and laminated into the metallic foam, the fleece or the fabric 8. The lithium foil 14 is shown in the

Embodiment initially wound on a coil 16a before. The lithium foil 14 is preferably in a thickness of 50 to 100 μηι, in particular 70 to 90 μηι, more preferably 80 μηι ago. Instead of the coil 16 could also be provided an extruding, which lithium foil 14 provides. On the underside, between the metallic foam, a further foil 18 is guided with a metal, for example an indium foil 18, and laminated into the metallic foam, fleece or fabric 8. The further film 18 is also wound on a spool 16b, from which it is provided to the process. Preferably, the process shown in Figure 2 takes place at temperatures below the melting point of lithium, i. below 180 ° C, more preferably at temperatures between 150 and 170 ° C, instead, so that the lithium can be plastically deformed.

Figure 3 shows a schematic representation of a further step of a

Production method of the electrode. A metallic fleece, foam or fabric 20 is introduced into a coating device 24, which in the illustrated embodiment has a substrate 24a arranged on the top side and a substrate 24b arranged on the bottom, which passes through a suitable evaporation method, for example thermal evaporation, electron beam evaporation, laser beam evaporation, arc evaporation or molecular beam epitaxy Sputtering or by ion plating into a gas phase in which they are applied to the metallic nonwoven, the foam or the fabric 20. On the output side, there is a coated metallic fleece, foam or fabric 22. The coated metallic nonwoven, foam or fabric 22 may hereafter be used, for example, as the input material 8 for the process described with reference to FIG. 2 or FIG. Alternatively, instead of the

physical also be provided a chemical coating process

for example, CVD.

FIG. 4 shows a further embodiment of a step for producing a

electrode according to the invention, wherein the input side, a metallic nonwoven, foam or

Tissue 26 is fed to a processing device and the output side, a laminated metallic nonwoven, foam or fabric 28 is provided. In contrast to the exemplary embodiment illustrated in FIG. 2, in a first process section 31, a lithium-containing film 34 is first unrolled from a spindle 36, guided through a first pair of rollers 30a, 30b, and laminated. In a second process section 33, which In particular, can take place in a separate process chamber, another

Rolled metal foil 38 from a spindle 40 and passed through a second pair of rollers 32a, 32b and laminated on the underside of the metallic fleece, the foam or the fabric 26. If the two process sections 31, 33 take place in different process chambers, different process conditions with regard to the temperature and the pressure can be set. For example, indium has a melting temperature of about 156 ° C, so that it is advantageous to separate the lamination processes of the lithium foil and the indium foil from each other. It can therefore be provided to carry out the process of lithium-lamination below the melting temperature of the lithium, for example between 150 and 170 ° C, preferably at about 150 ° C, and the process of indium-lamination below the melting temperature of the indium, for example between 120 and 145 ° C. In general, it is advantageous to carry out the process of lamination between 10% and 30% below the melting temperature of the metal or alloy used.

FIG. 5 schematically shows some steps of a manufacturing process of a porous one

Collector matrix, which is known as slurry reaction foam sintering (SRSS) method. As starting materials, a metal powder 42, preferably copper, nickel, aluminum, zinc or alloys thereof, particularly preferably nickel, a dispersant 44 and a blowing agent 46 are mixed. In a first step, the metal powder 42, the dispersant 44 and the blowing agent 46 are mixed with solvent 48 and acid 50 to form a slip 52. The slip 52 is dried below room temperature and forms a so-called green body 54. The green body 54 is sintered in a further step 56 and forms the metal foam 58. The porosity of the metal foam 58 is between 50% and 95%, preferably between 80% and 90 %.

Examples

EXAMPLE 1 A nickel foam with a thickness of 100 μm is produced by means of the slurry reaction foam sintering process (SRSS process) shown in FIG. The

Porosity is 90%. In a subsequent step, a lithium foil of about 80 μηι at a temperature of 150 ° C is laminated into the foam. An approximately 10 μηι thick indium film is laminated on the other side of the nickel foam. The recovered electrode is a lithium-air or a lithium-sulfur battery as a lithium electrode, ie as anode, installed during discharge. During the first charge and discharge process, a stable lithium-indium alloy is formed.

Example 2: By means of the slurry reaction foam sintering process (SRSS process), a nickel foam with a thickness of 100 μm is produced. The porosity here is 90%. In a subsequent step, the pores are vacuum-impregnated with molten sulfur. In a further step, the now obtained sulfur electrode is installed in a lithium-sulfur battery as a cathode. The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

Claims

Claims 1. An electrode (2) for a galvanic element, with a porous collector matrix (4), in which at least one lithium layer or a lithium alloy layer (14, 34) is laminated.

2. electrode (2) according to claim 1, characterized in that the porous

Collector matrix (4) as a grid (3), a foam (58) or a fabric is made.

3. electrode (2) according to any one of the preceding claims, characterized in that the porous collector matrix (4) made of copper, nickel, aluminum, zinc or alloys containing copper, nickel, aluminum and / or zinc, is made or with copper , Nickel, aluminum, zinc, or alloys containing copper, nickel, aluminum and / or zinc.

4. electrode (2) according to any one of the preceding claims, characterized in that the lithium alloy layer (14, 34) comprises an alloy with lithium and at least one metal from the following list: indium, tin, gallium or thallium, preferably indium.

5. Electrode (2) according to one of the preceding claims, characterized in that at least one further metal layer or metal alloy layer (18, 38) is laminated in the porous collector matrix (4), wherein the metal is one of the following metals or the metal alloy at least one of the following metals: indium, tin, gallium or thallium, preferably indium.

6. Galvanic element with at least one electrode (2) according to one of claims 1 to 5.

7. A process for producing an electrode (2) for a galvanic element, comprising the steps of:

a) providing a porous collector matrix (4);

b) providing a foil (14, 34) containing lithium;

c) laminating the foil (14, 34) containing lithium into the porous collector matrix (4).

8. The method according to claim 7, wherein step a) comprises the further step:

d) coating the collector matrix (4) with a lithium-stabilizing metal.

Method according to claim 7, comprising the further steps:

e) providing a film (18, 38) with a lithium-stabilizing metal;

f) laminating the foil (18, 38) with the lithium-stabilizing metal into the collector matrix (4) to form an alloy of the lithium with the lithium-stabilizing metal.

The method of claim 7, wherein step a) comprises the steps of:

g) admixing a lithium-stabilizing metal into a lithium-containing material;

h) extruding as a lithium-containing film (14, 34).