WO2019162314A1

WO2019162314A1 - Coating for a tool for handling lithium metal, tool and method for producing such a tool

Info

Publication number: WO2019162314A1
Application number: PCT/EP2019/054192
Authority: WO
Inventors: Dominik Alexander WEBER
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2018-02-26
Filing date: 2019-02-20
Publication date: 2019-08-29
Also published as: CN111770907A; DE102018104291A1

Abstract

The invention relates to a coating (2) for tools (1, 4, 5) for handling lithium metal (3), containing a lithium-repelling material. The invention also relates to a tool (1, 4, 5) having such a coating (2) and to a method (6, 7) for producing such a tool (1, 4, 5).

Description

description

"Coating for a tool for handling lithium metal, tool and method of making such a tool"

The invention relates to a coating for tools for handling lithium metal, which are preferably used in the development and manufacture of rechargeable lithium cells and lithium-based supercapacitors, for example for hybrid or electric vehicles. Furthermore, the invention relates to a tool for handling lithium metal and a method for producing such a tool. Due to the increasing interest in efficient batteries and supercapacitors, especially efficient high-voltage batteries, in the automotive industry, the importance of lithium metal is also increasing. However, lithium metal, whether in the form of particles or films, adheres to almost any material surface, even on conventional coatings, as described in DE 10 2005

017 459 A1, DE 10 2010 011 185 A1 and DE 10 2010 040 430 A1. For this reason, the handling, especially the processing designed

For example, by rolling, embossing, punching and the like, difficult.

In order to facilitate the handling of lithium metal, additives have hitherto been added to the lithium metal or the lithium metal itself is chemically modified, for example fluorinated, as described in US 2007/0006680 A1. In addition, lubricants are used in particular during rolling. In addition, as described in EP 0 692 831 B1,

Rolling cylinders are used made of polyacetal, where the adhesion of the lithium occurs only to a lesser extent. Other solutions provide for laminating (bonding) the lithium onto paper or resin or polymer substrates to improve processability and, for example, facilitate punching.

All previously known solutions include the use of auxiliaries or additives which have to be laboriously dried or even first refined to a sufficient degree of purity. In addition, significant amounts of dead material (as in the case of lamination) are sometimes generated, which must be disposed of after the introduction of lithium in the Bateriezellbau. With a view to future use of very thin lithium metal foils in battery and supercapacitor types of the next generation, a methodology for their production and processing is desired which reduces or completely eliminates this problem.

Object of the present invention is to provide a coating for a tool for

Handling of lithium metal, a tool and a method for producing the

To provide tools that at least partially overcome the above-mentioned disadvantages.

This object is achieved by the coating according to the invention for a tool for

Handling of Uthiummetall according to claim 1, the tool according to the invention according to claim 5 and the method for producing a tool according to claim 10,

According to a first aspect, the present invention relates to a coating for tools for handling lithium metal containing a lithium-repellent material.

According to a second aspect, the present invention relates to a tool for handling of Uthiummetall, wherein a tool surface of the tool is provided with a coating according to the first aspect.

According to a third aspect, the present invention relates to a method of manufacturing a tool for handling metal of the second aspect of the invention, comprising;

Conditioning the lithium repellent material;

Applying the refurbished lithium repellent material to a tool surface of the tool; and

Heat treating the tool with the applied lithium repellent material,

Further advantageous embodiments of the invention will become apparent from the subclaims and the following description of preferred embodiments of the present invention.

The present invention relates to a coating for tools for handling lithium metal which are preferably used in the development and manufacture of rechargeable lithium cells, for example lithium metal, lithium ion, lithium sulfur, lithium oxygen, lithium air , Lithium-graphene, lithium-carbon, lithium-carbon nanotube, solid-liquid electrolyte hybrid and / or solid state batteries, and / or

lithium-based supercapacitors, for example for hybrid or electric vehicles. The tools may, for example, be tools for transporting, Processing and / or storage of lithium metal. The lithium metal may be in the form of a film, liquid, powder or other form when handled.

The lithium metal may be derived from lithium chloride. For example, that can

Lithium metal may be obtained by fused-salt electrolysis of a eutectic mixture of lithium chloride and potassium chloride or by electrolysis of lithium chloride. After

Recovery, the lithium metal may be further processed, for example, formed into a film, liquefied or pulverized.

The coating for tools of the invention for handling lithium metal contains a lithium-repellent material. In particular, the coating consists of the

lithium-repellent material or from a mixture containing the lithium-repellent material. The lithium repellent material is preferably a so-called lithiophobic material that does not mix with lithium and avoid contact with lithium. The lithium-repellent material therefore tries to dissolve this contact as soon as possible on contact with lithium. The ratio between lithium metal and the lithiophobic material is comparable to the ratio between water and a hydrophobic material, with the water typically beading off and not adhering to the hydrophobic material.

The coating according to the invention thus prevents lithium metal from adhering to the respective tool and thus allows lithium metal to be processed even without high pressure using additives or other auxiliaries.

In some embodiments, the lithium repellent material may include or be lithium-conducting ceramic, ceramics in general, and lithium-conducting ceramics in particular may be processed to form very smooth surfaces, thereby further reducing adhesion of lithium metal, for example.

In some embodiments, the lithium-conductive ceramic may include or be a group lithium-conducting garnet ceramic. Lithium-conducting garnets are known to form after a certain residence time in the atmosphere superficially lithium carbonate, which induces a strong lithiophobic, so lithium-repellent arrest. The result is that lithium metal no longer adheres In some embodiments, the ceramic may be or may be of the group of lithium-conducting garnets lithium lanthanum zirconate (UrLaaZraOia). Lithium lanthanum zirconate is temperature resistant up to 1200 ° C and very hard and forms superficially in the atmosphere of lithium carbonate. Lithium lanthanum zirconate thus enables processing of lithium metal even under high pressure and at high temperatures.

Examples of other lithium-conducting garnets include, but are not limited to, a U ₃ -phase lithium garnet (eg L ^' bCTezO) where C is a lanthanoid such as Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, He, Tm, Yb, Lu, Zr, Ta, or a combination of the foregoing, and / or Lis- NdaTez-x O, where x = 0.05 to 1.5), a Li-phase lithium garnet ( For example, U ₅ La ₃ Af ₂ 0i ₂ where ^j y ¹ = Nb, Zr, Ta, Sb or combinations of the previously mentioned, cation-substituted UsLaaM ^ O, such as UeALa.iM'aO, where A = Mg, Ca, Sr, Ba or combinations of the above apply, and / or Li _T LaaßiO «, where B = Zr, Sn or combinations of the aforementioned apply), a Li-phase lithium garnet (eg LteDLa _ü M ^ O, where D = Mg, Ca, Sr, Ba or combinations of the abovementioned and M ³ = Nb, Ta or combinations of the aforementioned, cation-doped Li ₆ La ₂ BaTa ₂ o 12 and / or cation-doped UeBaY ₂ M ¹ ₂ 0i ₂ , wherein the yolk cations barium, yttrium, zinc or Kombinatio one of the abovementioned ones), a LiT phase lithium garnet (eg cubic LiLasZrsOu and / or LtrYsZriO,), cation-doped Li? La3Zr ₂ Oi2, Lts ^ LajTa ^ O, where x = 0.1 to 1, LMLaz .GsCao.osMZrusNbü.asP «(LLCZN), Ü6,4Y3Zno, 4Tao, eOi2, Li5, sLa2.5Baa, sT aZrOi ₂₎ LieBaYzM'jOii, LbYsZrjOlZ,

Lis.TsBaLazNbusZno.aBO «and / or üe.zsBaLazTai? 5Zn _0l2 sOi2 · Other examples for

Lithium-conducting garnets include cubic compounds such as 3 mol% YSZ-doped

Li?, O6La3Zroj4Yo.o60i2 and 8 mol% of YSZ-doped Lh.ieLaaZro.aiYo.oeO «·

Other examples of possible lithium grenades include, but are not limited to,

Alternatively, the lithium-repellent material of the coating may contain or be lithium carbonate. As mentioned above, lithium carbonate is highly lithiophobic and effectively prevents adhesion of lithium metal. However, when producing the lithium carbonate coating, sintering should be avoided since the lithium carbonate would release CO at typical sintering temperatures and reduce its lithiophobic properties. Instead of sintering, a heat treatment may be carried out at lower temperatures. Alternatively, the lithium-repellent material of the coating may comprise or consist of uncoated carbon fibers and / or copper. Both uncoated carbon fibers and copper have lithiophobic properties.

The invention further relates to a tool for handling lithium metal, wherein a tool surface of the tool is provided with a coating, which

contains lithium-repellent material, in particular a lithium-conductive ceramic such

for example, lithium lanthanum zirconate, or lithium carbonate. The tool has in particular a coating. as described above. The handling of lithium metal may involve gripping, processing, storing tithium metal and / or other handling of lithium metal. Preferably, in the region in which the coating is applied, the tool has a metallic material, for example steel, in particular austenitic steel, or another alloy. Alternatively, the tool in this area may also comprise a non-metallic material which is temperature resistant, since the coating with the coating preferably comprises a sintering step.

The tool according to the invention allows easy handling of lithium metal, since its coating effectively prevents adhesion of the lithium metal. The tool according to the invention is thus suitable for all production lines that process lithium metal, in particular for production lines for all products that use a battery or a

Use supercapacitor with lithium metal anode, as well as in research and

D facilities.

In some embodiments, the tool may be a gripping tool, for example, tweezers, forceps, or the like. Alternatively, the tool may be a tool for processing, for example a roller, a punching tool, an embossing tool, a press, a knife, a blade, a stirring tool, a funnel, a syringe, an extruder or the like. The coating of the tools can reduce or even prevent the adhesion of lithium and, for example, when gripping or processing a lithium foil, in particular a lithium foil with a thickness in the range from 10 μm to 35 μm, reduce the formation of grooves and holes, completely dispensing with the use of lubricants, additives and the like. Alternatively, the tool may be a tool for storing, for example, a container, a storage board, a vacuum suction device for stacking battery cells, or the like. Alternatively, the tool can also be members of a Include conveyor belts or a calender. Again, the coating can reduce or even avoid sticking to the tool

In some embodiments, all of the tool surfaces that come in contact with the lithium metal during handling may be provided with the coating. In the case of tweezers or forceps, preferably, tips of both legs can be provided with the coating on their inner sides aligned with one another and optionally on their outer sides. In the case of a roll, at least one lateral surface of a rolling cylinder, which can preferably be made of austenitic steel, and optionally two end faces of the rolling cylinder, can be coated with the coating. In a stamping tool, a stamp may be coated with the coating. Analogously, surfaces of others

Tools which come into contact with the lithium metal during handling are to be coated with the coating.

In some embodiments, the coating may have a thickness in a range of 0.5 μm to 10 μm, in particular in a range of 1 μm to 5 μm. A coating of this thickness is resistant and optimally reduces the adhesion of lithium metail.

In some embodiments, the tool surface provided with the coating may have an average roughness depth that is less than 2 pm, in particular less than 1 pm, preferably less than 0.5 pm. is. Due to the low roughness of the coating or the tool surface, the adhesion of the lithium metal can be further reduced. In addition, the risk can be reduced that the lithium, in particular the lithium foil is damaged. In particular, a roll with a coating of low roughness makes it possible to produce thin lithium foils, in particular lithium foils having a thickness in the range from 5 μm to 50 μm, preferably in a range from 10 μm to 35 μm.

The tool according to the invention allows a simplified handling of lithium metal and dispenses with the known from previous technologies use of lubricants, substrates or chemical modification.

The present invention further relates to a method for producing a tool for handling lithium metal, a tool surface of which is provided with a coating containing a lithium-repellent material, in particular for producing the tool described above, The production method according to the invention comprises the treatment of the lithium-repellent material, in particular a lithium-conducting ceramic such as lithium lanthanum zirconate or lithium carbonate. In this case, the lithium-repellent material can be suspended in a solution, for example, for a later T-coating or for a later one

Powder coating to be pulverized and mixed with a binder.

Furthermore, the manufacturing method comprises the application of the processed

lithium-repellent material on a tool surface of the tool. For this purpose, a dip coating can be used, in which the surface of the tool, in particular the tool surfaces, which come into contact with the lithium metal during handling thereof, are immersed in the solution with suspended lithium-repellent material.

For example, the tips of tweezers, the rolling cylinder of a roller or the punch of an embossing tool can be dipped into the solution. Alternatively, a

Powder coating can be performed, in which the surface of the tool, in particular the tool surfaces, which come into contact with the handling of the lithium metatl, are sprayed with the mixture of lithium-repellent material and binder. For example, the tips of the legs of a pair of tweezers, the rolling cylinder of a roller or the punch of an embossing tool can be sprayed with the mixture.

A coating by means of physical deposition methods is also conceivable.

For example, the lithium-repellent material can be applied to a tool surface by means of vapor deposition, spin coating or sputtering.

For lithium-conducting garnets, the pulsed laser deposition has been found to be suitable. Here, the material is preferably pressed to a target and then deposited with a laser in a vacuum chamber on the tool surface.

Furthermore, the manufacturing method comprises heat treating the tool with the applied lithium repellent material. If the lithium-repellent material is a lithium-conducting ceramic, in particular lithium lanthanum zirconate, the

Heat treatment be a sintering process. If the lithium-repellent material

Lithium carbonate, a gentle heat treatment at temperatures below 400 ° C can be performed.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings. It shows; Fig. 1 shows schematically a first embodiment of a tool according to the invention in the form of a roller;

Fig. 2 shows schematically a second embodiment of a tool according to the invention in the form of tweezers;

3 schematically shows a third embodiment of a tool according to the invention in the form of a punching tool;

4 shows a flow chart of a first method for producing a tool according to the invention in the form of a roller; and

5 shows a flow chart of a second method for producing a tool according to the invention in the form of a roller,

Fig. 1 shows a schematic representation of a rolling apparatus 1 for producing films of lithium metal (thin lithium foil 3 ') having a thickness of 10 pm to 35 pm. The

Rolling device 1 comprises two rolling cylinders 10 made of austenitic steel, whose

Jacket surfaces 11 are coated with a coating 2 of lithium lanthanum zirconate.

As a result of the contact with the atmosphere, a film of lithium carbonate (not shown) forms on the surface of the coating 2 and has a lithium-repelling effect. The surface of the lithium carbonate film forms the rolling surfaces 12, which come in direct contact with the lithium metal during rolling, and a surrounding region which is light

accidentally get in contact with the lithium metal.

The rolling cylinders 10 are aligned with their longitudinal axes 13 parallel to each other. A distance A between the longitudinal axes 13 of the rolling cylinder 10 is adjustable so that the smallest distance B between the rolling surfaces 12 is suitable, from a thick lithium foil 3 with a thickness of about 200 pm a thin lithium foil 3 'with a Thickness in the range of 10 pm to 35 pm to waizen.

The coating 2 prevents the thin lithium foil 3 'from adhering to one of the rolling surfaces 13. Thus, the thin lithium foil can be easily removed from the rolling surfaces directly after rolling. The roller 1 can conventional Use rolling cylinders which are subsequently provided only with a coating of lithium lanthanum zirconate.

Fig. 2 shows on the left a punching tool 4 for punching a lithium foil 3 before punching and right after punching. The punching tool 4 comprises a punch 40 with two dome-shaped punching tips 41 and a holder 42 which carries the punch 40. The surfaces of the punching tips 41 are coated with a coating 2 of lithium lanthanum zirconate. As a result of the contact with the atmosphere, a film of lithium carbonate (not shown) forms on the surface of the coating 2 and has a lithium-repelling effect. The surface of the lithium carbonate film forms the punching surfaces 43, which directly contact the lithium metal during punching, and a surrounding region that may easily inadvertently come into contact with the lithium metal.

For punching the lithium foil 3, the punching tool 4 moves perpendicular to a flat spread lithium foil 3 (arrow C) and tips 44 of the coated mandrel-like

Projections 41 cut into the lithium foil 3. Subsequently, the punching tool 4 is removed in the opposite direction (arrow D) from the lithium foil 3 and leaves a punching pattern 30 in the lithium foil 3.

By the coating 2 of the mandrel-like projections 41 can be prevented that the lithium foil adheres to the mandrel-like projections 41 and the removal of the

Punching tool 4 damaged the lithium foil. The punch 40 may be a conventional punch, which is subsequently provided with a coating of lithium lanthanum zirconate.

Fig. 3 shows a pair of tweezers 5 for gripping a lithium foil 3. The tweezers 5 comprises two legs 50 made of stainless steel and a connecting element 51 which connects the two legs 50 at one leg end. The surfaces of holding tips 52, which are located on a side opposite to the connecting element 51 leg end, are provided with a

Coating 2 of lithium lanthanum zirconate coated. As a result of the contact with the atmosphere, a film of lithium carbonate (not shown) forms on the surface of the coating 2 and has a lithium-repelling effect. The surface of the film of lithium carbonate forms the holding surfaces 53, which come into direct contact with the lithium metal when gripping, and a surrounding area, which easily inadvertently with the

Lithium metal can come into contact. The coating 2 prevents the lithium metal from adhering to the holding surfaces of the tweezers during the lasso cups. The tweezers 5 may be a conventional tweezers, which are subsequently provided only with a coating of lithium lanthanum zirconate.

The coating of the rolling cylinders, the punch and the tweezers may include or consist of a lithium-repellent material other than lithium lanthanum zirconate.

FIG. 4 shows a flowchart of a method 6 for producing a rolling cylinder as used in the rolling apparatus described with reference to FIG.

At 60, the lithium-repellent material of the coating, here lithium lanthanum zirconate, processed. For this purpose, the lithium lanthanum zirconate is suspended in a solution.

At 61, a blank of an austenitic steel rolling cylinder is immersed in the suspension containing the suspended lithium lanthanum zirconate so that the lithium lanthanum zirconate completely wets the shell surfaces of the blank {dip coating).

At 62, the rolling cylinder wetted with the suspended lithium lanthanum zirconate is sintered to render the coating durable and resistant.

FIG. 5 shows a flowchart of a further method 7 for producing a

Walzylinders used in the rolling apparatus described with reference to FIG.

At 70, the lithium-repellent material of the coating, here lithium lanthanum zirconate, processed. For this purpose, the lithium lanthanum zirconate is pulverized and mixed with a binder.

At 71, the shell surface of the rolling cylinder with the mixture of lithium-repellent material and binder sprayed (powder coating), so that the lateral surface is uniformly covered with the mixture.

At 72, the wetted with the mixture of lithium lanthanum zirconate and binder

Sintered rolling cylinder to burn the binder and to make the coating durable and resistant. The described methods 8, 7 can also be used analogously in the manufacture of another tool, for example a punch, as shown in FIG. 2, or a pair of tweezers, as shown in FIG. 3. Instead of the lithium lanthanum zirconate, another lithium-conducting ceramic can be used as a lithium-repellent material.

In addition, the described methods 6, 7 can be modified such that

Lithium carbonate is used as a coating material. In this case, the step of sintering 63, 73 is replaced by a gentle temperature treatment at temperatures below 400 ° C.

Claims

claims

A coating (2) for tools (1, 4, 5) for handling lithium metal (3) containing a lithium repellent material.

2. Coating (2) according to claim 1, wherein the lithium-repellent material a

lithium conductive ceramic or lithium carbonate.

3. Coating (2) according to claim 2, wherein the lithium-conducting ceramic is a group of lithium-conducting garnets.

4. coating (2) according to claim 3, wherein the ceramic of the group lithiumleitender

Grenade is lithium lanthanum zirconate.

5. Tool (1, 4, 5) for handling lithium metal (3), wherein a

Tool surface (11) of the tool (1) with a coating (2) according to one of claims 1 to 4 is provided.

6. Tool (1 _» 4, 5) according to claim 5, wherein all tool surfaces, the

Handling of the lithium metal (3) come into contact with this, are provided with the coating (2).

7. Tool (1, 4, 5) according to claim 5 or 8, wherein the tool is a roller (1), tweezers (5), a punching tool (4), a syringe, a stirring tool, a funnel or a container,

8. Tool (1, 4, 5) according to any one of claims 5 to 7, wherein the coating (2) has a thickness in the range of 0.05 pm to 5 pm.

9. Tool (1, 4, 5) according to any one of claims 5 to 8, wherein the coating (2) provided with the tool surface (11) has an average roughness depth, which is less than 2 pm comprises. Method (6, 7) for producing a tool (1, 4, 5) for handling lithium metal (3) according to any one of claims 5 to 9, comprising;

Processing (60, 70) the lithium repellent material;

Applying (61, 71) the treated lithium repellent material to a tool surface (11) of the tool (1, 4, 5); and

Heat treating (62, 72) the tool (1, 4, 5) with the applied lithium repellent material.