WO2018050313A1

WO2018050313A1 - Method for producing an active material for an electrode of a battery cell, arrangement for producing an active material for an electrode of a battery cell and battery cell

Info

Publication number: WO2018050313A1
Application number: PCT/EP2017/067805
Authority: WO
Inventors: Herbert Gruhn; Harald Bauer
Original assignee: Robert Bosch Gmbh
Priority date: 2016-09-13
Filing date: 2017-07-14
Publication date: 2018-03-22
Also published as: DE102016217367A1

Abstract

The invention relates to a method for producing an active material (41, 42) for an electrode of a battery cell, wherein a binder (70) is introduced into a reaction chamber (60) by means of thermal spraying in a spraying direction (S), and wherein a charge-coupled memory material (72) is introduced into the reaction chamber (60) in a feeding direction (Z) differing from the spraying direction (S) such that the binder (70) and the charge-coupled memory material (72) form a bond in the reaction chamber (60), thus forming the active material (41, 42). The invention also relates to an arrangement for producing an active material (41, 42) for an electrode of a battery cell, comprising a housing unit (62), which has an at least approximately circular-cylindrical reaction chamber (60) formed around a central axis (A), and a thermal spray gun (64), which projects into the reaction chamber (60) such that a binder (70) can be introduced into the reaction chamber (60) by means of thermal spraying in a spraying direction (S), the spraying direction (S) running along the central axis (A). The invention also relates to a battery cell which comprises at least one electrode with an active material (41, 42) that is produced in accordance with the claimed method.

Description

description

title

Process for producing an active material for an electrode of a

Battery cell, arrangement for producing an active material for an electrode of a battery cell and battery cell

The invention relates to a method for producing an active material for an electrode of a battery cell, wherein a binder is introduced into a reaction space, and wherein a charge storage material is introduced into the reaction space, and wherein the binder and the charge storage material in the reaction space form a compound, which Active material forms. The invention also relates to an arrangement for producing an active material for an electrode of a battery cell, as well as a battery cell comprising an electrode, which is produced by the method according to the invention.

State of the art

Electrical energy can be stored by means of batteries. Batteries convert chemical reaction energy into electrical energy. Here are

Primary batteries and secondary batteries distinguished. Primary batteries are only functional once, while secondary batteries, also referred to as accumulators, are rechargeable. A battery comprises one or more battery cells.

In particular, so-called lithium-ion battery cells are used in an accumulator. These are characterized among other things by high energy densities, thermal stability and extremely low self-discharge. Lithium-ion battery cells are used, inter alia, in motor vehicles, in particular in electric vehicles (EV), hybrid vehicles (HEV) and plug-in hybrid electric vehicles (PHEV). Lithium-ion battery cells have a positive electrode, also referred to as a cathode, and a negative electrode, also referred to as an anode. The cathode and the anode each include one

Current conductor, on which an active material is applied. The active material for the cathode contains, for example, a metal oxide such as Ι_ΐ2Μηθ3 and an NCM alloy, ie an alloy of nickel, cobalt and manganese. The

Active material for the anode contains, for example, silicon or graphite.

In the active material of the anode lithium atoms are embedded. During operation of the battery cell, ie during a discharge process, electrons flow in an external circuit from the anode to the cathode. Within the battery cell, lithium ions migrate from the anode to the cathode during a discharge process. The lithium ions from the active material of the anode store reversibly, which is also referred to as delithiation. When charging the

Battery cell, the lithium ions migrate from the cathode to the anode. In this case, the lithium ions reversibly store back into the active material of the anode, which is also referred to as lithiation.

The active material of the electrodes often comprises a plurality of materials, in particular a charge storage material which itself may be less conductive, such as oxides or NMC, an electronic conductive component such as Leitruß or graphite and an ionic conductive component such as a liquid or solid electrolyte. To mechanically stabilize the active material, a binder, for example a polymer, may be used. The individual components of the

Each active material will form a network of its own and be interconnected and interlocked with one another at the same time

To ensure mechanical strength and electronic and ionic conductivity. The active material is fixed on a metallic current collector.

Processes for the production of active material and of electrodes are known inter alia from documents US 2005/0057888 A1, US 2015/0061176 A1, US Pat. No. 7,087,348 B2 and DE 10 2015 106 879 A1. From the document US 4153661 A is a method for producing a flat

Composite material. For producing closed as well as porous layers, thermal spraying methods can also be used. During thermal spraying, particles are shot at high speed in a gas or liquid abrasive jet onto the surface to be coated. In addition, it is possible to ignite a burner flame or a plasma and combine it with the particle beam. According to the state of the art, these processes are distinguished according to DIN EN 657 according to temperature, type of flame, kinetic energy of the particles, whether chemical reactions take place in the flame, etc.

A description of the basic procedure for the production of layers by means of "cold gas spray" (CGS) method can be found inter alia in the documents US 2004/0037954 AI and US 2006/0027687 AI. An advantage of the cold gas spray method lies in the avoidance of oxidation of sprayed material and substrate.

During thermal spraying, the particles strike the surface to be coated under a combination of kinetic energy and temperature in such a way that the particle bursts almost flush onto the surface, where it solidifies and digests with both the surface and the neighboring particles. By suitable process control, the surface to be coated can be protected against inadmissible heating. So can even at high

Temperatures melting metals are coated on polymers.

Furthermore, by thermal spraying, polymers can also be processed into closed coatings, as for example from Progress in Organic Coatings 49 (2004) 69-73, properties of thermally sprayed fluoropolymer PVDF, ECTFE, PFA and FEP coatings, E. Leivo, T. Wilenius, T. Kinos, P. Vuoristo !, T. Mäntylä, Surface Engineering Laboratory, Institute of Materials Science, Tampere University of Technology, PO Box 589, FIN-33101 Tampere, Finland, Accepted 21 August 2003, is known.

From US 5285967 A a thermal spray gun is known by means of which a "high velocity oxygen fuel" (HVOF) method is feasible. By means of thermal spray gun, for example, thermoplastic, metallic and ceramic composites can be coated on a substrate.

From US 4840859 A a thermal battery is known which comprises an anode with alkali metal and / or alkaline earth metal, an electrolyte and a polymer and means for heating and melting the polymer.

From the manual process engineering and plant construction, ISBN 978-642-63550- 0 agglomeration processes are known in which water is sprayed on carbon to form defined beads. The goal is the subsequent process-technically more favorable processing. A method for forming waste into a material in the form of beads is known from DE 38 32 771 AI.

Disclosure of the invention

A method for producing an active material for an electrode of a battery cell is proposed. In this case, a binder is introduced by means of thermal spraying in a spray direction in a reaction space, and a charge storage material is in a feed direction, which of the

Injection direction deviates, introduced into the reaction space such that the binder and the charge storage material in the reaction space form a compound which forms the active material.

The binder is preferably a polymer, in particular PVDF, PTFE, PE or PP. The charge storage material is, for example, a metal oxide or NMC for a cathodic active material. The charge storage material is, for example, silicon or graphite for an anodic active material. Others too

Charge storage materials are conceivable.

The binder is preferably in the form of particles having a size of about 1 to 15 μηι, more preferably introduced with a size of about 3 to 5 μηι, in the reaction space. The charge storage material is

preferably in the form of particles with a size of about 10 to 40 μηι, particularly preferably with a size of about 10 to 15 μηι, in the Reaction space introduced. This results in collisions of the particles of the binder with the particles of the charge storage material and optionally with particles of additionally introduced into the reaction chamber components. The particles of the binder burst almost liquid onto the particles of the charge storage material, solidify there and become entangled with the particles of the charge storage material and with further particles of the binder and optionally with particles of additionally introduced into the reaction chamber components. This results in agglomerates of the active material, which have a size between 50 μηι and 300 μηι, in particular between 60 μηι and 100 μηι.

In subsequent process steps, the agglomerates of the active material thus produced are removed from the reaction space. Advantageously, the agglomerates of the active material thereby fall by gravity

Direction of gravity out of the reaction chamber, whereby the removal is relatively easy. Subsequently, a current conductor, the

is preferably made of a metallic material coated with the generated active material. According to an advantageous embodiment of the invention, an electronic conductive component in the feed direction is additionally introduced into the reaction space in such a way that the binder and the charge storage material and the electronic conductive component in the reaction space form a compound which forms the active material. The electronic conductive component is, for example, conductive carbon black or graphite.

According to another advantageous embodiment of the invention, an ionic conductive component in the feed direction is additionally introduced into the reaction space in such a way that the binder and the charge storage material and the ionic conductive component in the reaction space enter into a connection, which

Active material forms. The ionic conducting component is, for example, an electrolyte.

According to a further advantageous embodiment of the invention, an additional electronic control component and an ionic conductive component introduced into the reaction space in the feed direction such that the binder and the charge storage material and the electronic conductive component and the ionic conductive component in the reaction space form a compound which forms the active material.

The injection direction is preferably at least approximately

Opposite to gravitational direction. The binder is thus introduced into the reaction space counter to the direction of gravity, ie upwards and against gravity.

According to an advantageous development of the invention, the feed direction with the injection direction forms an angle between 90 ° and 180 °. In particular, therefore, the binder and the charge storage material are not introduced into the reaction space in the same direction. The feed direction and the injection direction, under which the binder and the charge storage material are introduced into the reaction space, preferably also form no acute angle with one another. The feeding direction and the spraying direction can nevertheless form an acute angle.

Particularly preferably, the feed direction is opposite to the injection direction. The binder and the charge storage material are thus in

introduced opposite directions in the reaction space. If the spraying direction is thus opposite to the gravitational direction, then the feed direction corresponds to the gravitational direction. The charge storage material is thus introduced in this case with gravity into the reaction space and falls down.

According to a preferred embodiment of the invention, the reaction space is formed at least approximately circular cylindrical about a central axis. The injection direction runs along the central axis of the reaction space. The reaction space is formed beispielswiese of a housing unit which is hollow cylindrical, in the form of a tube designed.

An arrangement for producing an active material for an electrode of a battery cell is also proposed. The arrangement for producing the Active material in this case comprises a housing unit, which has an at least approximately circular-cylindrical reaction space formed around a central axis, and a thermal spray gun. The thermal spray gun protrudes into the reaction space in such a way that a binder can be introduced into the reaction space by means of thermal spraying in an injection direction which runs along the central axis.

In operation, the said arrangement for producing an active material is preferably positioned such that the central axis of the reaction space along the gravitational direction, ie perpendicular to the ground, and that the injection direction against the gravitational direction, ie upwards, is directed.

It is also proposed a battery cell, which comprises at least one electrode with an active material, which after the

process according to the invention is produced.

A battery cell according to the invention advantageously finds use in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PH EV), or in a consumer electronics product. Consumer electronics products are in particular mobile phones, tablet PCs or notebooks.

Advantages of the invention

In the method according to the invention binders can be used which can not be dissolved in solvents. Furthermore, binders can be used that do not form classical fibrils in a mill process. The result is an approximately uniform size of the agglomerates of the active material for further processing, in particular for the production of a film for coating a Stromableiters. The use of available equipment technology of thermal spraying is readily possible because the delivery rates of the powder conveyors and spray guns generously cover the parameter range for the preferred manufacturing process. Powder conveyors during thermal spraying are state of the art with delivery rates from about 0.lg / min to about 300 g / min at a conveying accuracy of ± 1% relative to the maximum

Delivery rate. A powder delivery by means of liquid, suspension or solution is feasible. An overspray of thermal spraying, that is, spraying past the current conductor to be coated, does not matter. By means of the parameters pressure, delivery rate of propellant gas, delivery rate of

Liquid, suspension or solution, particle fraction, temperature and

Removal of the particle streams to the next obstacle can be the

Agglomeration process defined as a prerequisite for controlling the size of the agglomerates in the film production process.

Brief description of the drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below.

Show it:

Figure 1 is a schematic representation of a battery cell and Figure 2 is a schematic sectional view of an arrangement for

Production of an active material.

EMBODIMENTS OF THE INVENTION In the following description of embodiments of the invention, the same or similar elements will be denoted by the same reference numerals, and a repeated description of these elements will be omitted in individual cases. The figures illustrate the subject matter of the invention only schematically.

FIG. 1 shows a schematic representation of a battery cell 2

Battery cell 2 comprises a cell housing 3, which is prismatic, in the present cuboid, is formed. In the present case, the cell housing 3 is designed to be electrically conductive and, for example, made of aluminum. The Cell housing 3 may also be made of an electrically insulating material, such as plastic.

The battery cell 2 comprises a negative terminal 11 and a positive terminal 12. Via the terminals 11, 12, a voltage provided by the battery cell 2 can be tapped off. Furthermore, the battery cell 2 can also be charged via the terminals 11, 12.

Within the cell housing 3 of the battery cell 2, an electrode unit 10 is arranged, which, for example, as an electrode stack or as

Electrode winding is performed. The electrode unit 10 has two electrodes, namely an anode 21 and a cathode 22. The anode 21 and the cathode 22 are each designed like a film and separated by a separator 18 from each other. The separator 18 is likewise designed like a film and is ionically conductive, that is permeable to lithium ions.

The anode 21 comprises a layer of anodic active material 41 and a current conductor 31. The current conductor 31 of the anode 21 is made electrically conductive and made of a metal, for example of copper. The current conductor 31 of the anode 21 is electrically connected to the negative terminal 11 of the battery cell 2.

The cathode 22 comprises a layer of cathodic active material 42 and a current collector 32. The current collector 32 of the cathode 22 is made electrically conductive and made of a metal, for example

Aluminum. The current collector 32 of the cathode 22 is electrically connected to the positive terminal 12 of the battery cell 2.

Figure 2 shows a schematic sectional view of an arrangement for

Production of an active material 41, 42 for an electrode 21, 22 a

Battery cell 2. By means of the arrangement shown here, the inventive method for producing an active material 41, 42 for an electrode 21, 22 of a battery cell 2 is feasible. The arrangement shown comprises a housing unit 62. The housing unit 62 has an approximately circular-cylindrical reaction space 60 formed around a central axis A. The housing unit 62 is positioned such that the central axis A of the reaction space 60 is perpendicular to the ground. Into the reaction space 60, a thermal spray gun 64 protrudes. The thermal spray gun 64 can be configured, for example, to carry out a "high velocity oxygen fuel" (HVOF) process, a "cold gas spray" (CGS) process, a suspension plasma spraying process or a flame spraying process.

In suspension plasma spraying, especially when relatively small polymer particles are to be suspended or dissolved, the

Polymer particles are promoted for example as a suspension. Also, the polymer particles can be conveyed dissolved in solvent, so that the solvent evaporates on the way and allows a fine distribution of the polymer.

When carrying out the method according to the invention, the thermal spray gun 64 is fed with a binder 70 in the form of particles having a size of about 1 to 15 μm, particularly preferably having a size of about 3 to 5 μm. The thermal spray gun 64 protrudes into the reaction chamber 60 in such a way that the binder 70 is injected into the reaction space 60 during thermal spraying in an injection direction S which runs along the center axis A of the reaction space 60. In particular, the spray direction S runs counter to the direction of gravitational movement G. The particles of the binder 70 are thus introduced into the reaction space 60 against the force of gravity, ie, upwards.

In carrying out the method according to the invention will be further

Charge storage material 72, an electronic conductive component 74 and an ionic conductive component 76 with a size of about 10 to 40 μηι, more preferably with a size of about 10 to 15 μηι, in one

Feed direction Z also introduced into the reaction chamber 60 of the housing unit 62. The feeding direction Z deviates from the spraying direction S and is in particular opposite to the spraying direction S. The feed direction Z thus corresponds to the gravitational direction G and likewise runs along the central axis A of the reaction space 60. When carrying out the method according to the invention, the particles of the binder 70 collide with the particles of the charge storage material 72, the particles of the electronic conductive component 74 and the particles of the ionic conductive component 76. In this case, the particles of the binder 70 burst almost flush onto the particles of the charge storage material 72 , the conductive electron component 74 and the ionic conductive component 76, solidify there and become entangled with the particles of the charge storage material 72 of the electronic conductive component 74 and the ionic conductive component 76 as well as with further particles of the binder 70.

The particles of the binder 70, the particles of the

Charge storage material 72, the particles of the electronic control component 74 and the particles of the ionic conductive component 76 in the reaction space 60, a compound which forms the active material 41, 42. Thereby arise

Agglomerates of the active material 41, 42, which have a size between 50 μηι and 300 μηι, in particular between 60 μηι and 100 μηι.

The resulting agglomerates of the active material 41, 42 fall by gravity in the direction of gravity G from the reaction space 60 of the

Housing unit 62 out. The removal of the agglomerates of the active material 41, 42 from the reaction space 60 of the housing unit 62 is thus

relatively easy. The agglomerates of the active material 41, 42 can be additionally fractionated or broken if necessary.

Fine dust is entrained by the gas and particle beam of the thermal spray gun 64 and led upwards, so that the fine fraction is also incorporated into the agglomerates of the active material 41, 42. This corresponds to the principle of agglomeration in a fluidized bed.

This allows, as described above, to use a relatively small amount of binder 70, in particular PVDF, for fibrillation. The kinetic energy from the injection process is thereby used simultaneously for intensive mixing with the falling particles of the charge storage material 72, the electronic conductive component 74 and the ionic conductive component 76. One correspondingly acting free-fall mixer is also described in "CONTINUO ERLICHES MISCHEN FEIN ER FIXING MATERIALS IN FLUIDDYNAMIC FALLROH RMISCHERN, OLAF EICHSTÄDT, Diss. Zürich 1997".

The thermal spraying of polymers as binder 70 is used so that 100% of the spray is in the reaction space 60. In particular, there is no overspray. Resultant turbulences additionally assist in mixing together the particles of binder 70, charge storage material 72, electronic control component 74 and ionic conductive component 76.

The thus formed agglomerates of the active material 41, 42 can be conveyed and further processed into films by extrusion or rolling. In particular, to produce an electrode 21, 22, a current conductor 31, 32 which is made of a metallic material, in particular aluminum or copper, is then coated with the further processed active material 41, 42.

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. A process for producing an active material (41, 42) for a

Electrode (21, 22) of a battery cell (2), wherein

a binder (70) by thermal spraying

in one spraying direction (S)

is introduced into a reaction space (60), and wherein

a charge storage material (72) in a feed direction (Z) deviating from the injection direction (S)

is introduced into the reaction space (60) such that

the binder (70) and the charge storage material (72) in the

Reaction space (60) enter a connection which the

Active material (41, 42) forms.

2. The method of claim 1, wherein

an electronic control component (74)

in the feeding direction (Z)

is introduced into the reaction space (60) such that

the binder (70) and the charge storage material (72) and the electronic control component (74) in the reaction space (60) form a connection which forms the active material (41, 42).

3. The method according to any one of the preceding claims, wherein

an ionic conducting component (76)

in the feeding direction (Z)

is introduced into the reaction space (60) such that

the binder (70) and the charge storage material (72) and the ionic conduction component (76) in the reaction space (60) form a compound which forms the active material (41, 42). Method according to one of the preceding claims, wherein

the injection direction (S) is at least approximately opposite to the direction of gravitation (G).

Method according to one of the preceding claims, wherein

the feed direction (Z) with the injection direction (S) an angle between

90 ° and 180 ° forms.

Method according to one of the preceding claims, wherein

the feed direction (Z) is opposite to the injection direction (S).

Method according to one of the preceding claims, wherein

the reaction space (60) is formed at least approximately circularly about a center axis (A), the center axis (A) running along the injection direction (S).

Arrangement for producing an active material (41, 42) for an electrode (21, 22) of a battery cell (2), comprising

a housing unit (62), which has an at least approximately circular-cylindrical about a central axis (A) formed reaction space (60), and

a thermal spray gun (64) protruding into the reaction space (60) such that

a binder (70) by thermal spraying in an injection direction (S), which runs along the central axis (A),

in the reaction space (60) can be introduced.

Battery cell (2), comprising at least one electrode (21, 22) with an active material (41, 42), which is produced by the method according to one of claims 1 to 7.

Use of the battery cell (2) according to claim 9 in one

Electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product.