WO2018047054A1

WO2018047054A1 - Method and device for applying magnetic fields to an object

Info

Publication number: WO2018047054A1
Application number: PCT/IB2017/055317
Authority: WO
Inventors: Martin Ebner; Felix GELDMACHER; Max KORY; Deniz BOZYIGIT
Original assignee: Battrion Ag
Priority date: 2016-09-06
Filing date: 2017-09-05
Publication date: 2018-03-15

Abstract

The invention relates to a method for applying magnetic fields to an object (020) which is, in particular, a layer or an object which is coated with a layer, and further particularly a coating which contains graphite particles, preferably for the purpose of producing a negative electrode with oriented graphite particles, for example for rapid-charging lithium-ion batteries. In particular, the application of the magnetic fields is intended to be performed continuously. A magnetic tool comprising permanent magnets (010) for applying magnetic fields is used for this purpose, wherein the object is moved relative to the magnetic tool. The magnetic field is applied, in particular, before a drying phase (30) is initiated and/or during the drying phase.

Description

Method and device for applying magnetic fields to an object

The invention relates to a method for applying magnetic fields to an object, with the aid of a magnetic tool, wherein the application of the magnetic fields is particularly continuous and in particular to a graphite coating, and further in particular for producing an article in the form of a negative electrode with vertically oriented graphite particles For example, for lithium-ion batteries with Schnelliade capability and / or high energy density. It furthermore relates to a negative electrode produced by the method according to the invention and having vertically oriented graphite particles.

Carbon-based materials, in particular graphite, find use as active material in Batferie electrodes, in particular negative electrodes. Graphite has a layered structure consisting of single carbon layers that can intercalate ions, such as lithium ions in a lithium-ion battery. The layer structure of the graphite is reflected by its occurrence in flake form.

When using flaky graphite as the active material in an electrode, the flake-shaped graphite particles typically come to lie parallel (horizontally) to an underlying current collector foil. This leads to tangled pore passages through the electrode. The lithium ions that diffuse from the positive electrode into the negative and vice versa must go through this tangled pore path. Particularly in the case of high charge rates, the lithium ions can not move sufficiently fast through the pore channels, resulting in a reduction in usable storage capacity can. By aligning the graphite particles, the path lengths that the lithium ions when charging and discharging, shortened and the charging and discharging properties of an electrochemical storage can be improved.

For the industrial production of negative graphite electrodes, the platelet-shaped graphite is often rounded off. However, up to 70% of the original material is lost in the mechanical rounding process.

The idea of using flake-form graphite and greatly reducing the tangled pore paths by aligning the graphite flakes perpendicular to the current collector foil and thereby achieving higher charge and discharge rates of the battery is known and was first disclosed in JP 3443227 B2. To achieve this alignment by a magnetic field is known. However, the practical implementation of this technology has so far been incompatible with cost-efficient, continuous production processes, in particular due to high magnetic fields and low packing densities.

EP 2793300 A1 discloses an application for the production of electrodes, wherein magnetic nanoparticles are applied to electrochemically active particles, which in turn are applied as a slurry ("suspension" or "paste") to a substrate and subsequently applied to the particles by a magnetic field Although the addition of magnetic nanoparticles in the production of graphite paste, which results in the decoration of graphite particles with nanoparticles, may increase the magnetic responsiveness of the graphite particles, it may complicate the process, but may also result in undesirable electrochemical processes due to the addition of magnetic nanoparticles A process for particularly continuous application of magnetic fields is not disclosed. The patent US 7326497 B2 describes a negative electrode and its manufacture for use in a rechargeable lithium-ion battery. A method is disclosed in which the graphite coating is aligned in a magnetic field having a flux density greater than 0.5 T between two magnets. The orientation of the graphite particles in the coating is based on the diamagnetic anisotropy of graphite. The diamagnetic susceptibility perpendicular to the (002) plane of the graphite is about 40-50 times as large as the diamagnetic susceptibility perpendicular to the (1 10) plane. To obtain good vertical orientations, flux densities of over 1 T and even 2.3 T are proposed. Flux densities in this area are technically difficult to implement, for example, superconducting magnets are required for such high flux density.

Another patent US 7976984 B2 describes a rechargeable battery in which mechanically rounded graphite particles are aligned in a magnetic field. Although the orientation of the rounded graphite particles in a magnetic field, the path length of the lithium ions can be slightly shortened and thereby the charging and discharging properties are improved, this improvement effect is further enhanced by the use of flaky graphite. However, as mentioned above, up to 70% of the original material is lost in the rounding process.

If graphite is oriented in a homogeneous magnetic field as described in US 7976984 B and US Pat. No. 7,326,497 B2, the particles are oriented such that the layers of the graphite come to lie parallel to the magnetic field. For asymmetric, z. B. leaflet-shaped graphite particles that is vertical to their longest axis. In the case of almost spherical particles, the influence on the packing behavior is small, but for non-spherical particles, this leads to a disadvantageous packing behavior, in which the individual graphite particles in one random order along its second longest axis. This results in low particle packing densities.

The invention is therefore based on the object, a method for applying magnetic fields, in particular for the continuous application of magnetic fields on an object, which is in particular a layer or a coated object with a layer, and further in particular on a graphite coating for producing an article in Form a negative electrode.

Continuous is defined here as meaning "in a continuous production process" such as "roll-to-roll processing" and not as "continuous".

The article, which may also be a single layer, may include, for example, graphite particles, a binder, and a drying-volatile component. The graphite particles may be of natural or synthetic origin and contain all particle shapes.

The object is solved with the features of claim 1.

In the method according to the invention, a magnetic field is applied in particular to a layer or to a layer-coated object, in particular during production and / or processing of the object. The object is exposed to a changing magnetic field.

To apply magnetic fields, a magnetic tool incorporating an array of at least one permanent magnet is used.

The invention further relates to a tool according to the invention and a manufactured electrode. Preferred embodiments are disclosed in the respective dependent claims. For application in batteries with high energy density, the above-described packing density of the active material graphite is of crucial importance. The invention solves this problem by aligning the graphite particles not only along one direction but along two directions.

The aim of the method according to the invention is to enable a particularly continuous application of magnetic fields, for example during a production and / or processing process of negative electrodes with vertically aligned graphite particles for, for example, fast-charging lithium-ion batteries.

At the beginning of the inventive method, the ingredients, for. B. graphite particles in a coating mobile and are aligned by the influence of a changing magnetic field of a magnetic tool according to the invention according to two preferred directions. Both preferred directions are given by the configuration of the magnetic tool and the relative direction of movement of the object and tool. During or after the alignment of the ingredients with the aid of the magnetic tool, the ingredients must be immobilized to complete the process to obtain the alignment in the longer term.

The immobilization of the aligned components can take place, for example, by drying. Drying is characterized in that a volatile component contained in the coating leaves the coating. In the case of water-based graphite pastes, this volatile component is water. The drying leads to the immobilization of the vertically oriented components. The drying can be both passive, z. B. due to the ambient temperature, ie not take place supported, as well as active, ie by the targeted drying for example, with a blower. Alternatively, the immobilization of the constituents of the layer / coating can also take place by targeted solidification / gelling of the moist layer / coating. A method of consolidating / gelling the wet layer / coating, for example using a thermoresponsive component as part of the layer / coating, is disclosed as part of this invention.

In the following, the problem which solves the invention is illustrated by the example of a graphite coating for the production of lithium-ion battery.

The drying process in which the volatile component is removed can cause the oriented graphite particles to lose their orientation. In particular, the air drying in the oven by blowers can have a significant influence on the orientation of the oriented particles, in particular, the orientation of the graphite particles, which was achieved by the magnetic tool, lost during drying. In turn, the loss of alignment of the graphite particles may limit the electrochemical performance of the electrode during charging and discharging. Solution variant A:

A solution to obtain the alignment of the graphite particles during drying is disclosed according to the invention. In order to ensure the orientation of the graphite particles during drying, the magnetic tool described here is also used during drying. As a result, the aligned graphite particles remain aligned during drying.

Solution variant B:

In the context of this invention, this problem can also be solved by the use of a solidifying / gelling component, such as a thermoresponsive component, contained in the paste to be coated. This component, for example, methyl cellulose, leads under the Heat causes the applied wet coating / layer to solidify without removing the volatile component at the same time. The LCST (Lower Critical Solution Temperature), the lower critical solution temperature, plays an important role here. An LCST is frequently observed when polymers such as methylcellulose, hydroxypropylcellulose containing substituted and unsubstituted anhydroglucose rings, or even polymers such as poly (N-isopropylacrylamides) are components of the mixtures. In this case, a transition of the polymer chains from an open-chain helix conformation to a compact globule conformation can be observed. Above the LCST there is a miscibility gap which can lead to the solidification of the coating / layer. The heat required to reach above the LCST can take place, for example, through a heated fan, heated rollers or an IR emitter. Even small mass fractions of the thermoresponsive component such as 0.25wt% in the layer to be coated (equivalent to 0.5wt% in the resulting dry coating at a solids content of 50wt% of the layer to be coated) are sufficient to bring about the solidification of the paste with temperature increase above the LCST ,

The solidification of the paste, induced by the thermoresponsive component, fixes the graphite particles, so that the alignment, which was previously achieved in the magnetic field of the magnetic tool, is retained in the longer term. This allows drying to take place subsequently without the application of a magnetic field, since movement within the coating, e.g. B. by convection, is suppressed and the ingredients, eg. B. graphite particles can not change their orientation. This allows to reduce the required amount of magnets needed to maintain vertical alignment. This is particularly advantageous if it is possible in this way to dispense with the installation of expensive high-temperature-resistant magnets in the dryer. For the production of long-lasting rechargeable lithium-ion batteries, the adhesion of the coating to a current collector, preferably a current collector foil, for example a copper foil, plays a special role. For electrodes that have low adhesion, it may over time peel off the active material coating, e.g. B. graphite of current collector foil come due to stresses at the boundary layer. In particular, the expansion and contraction of the graphite particles, which takes place during the loading and unloading process, can lead to this. This can result in a reduction in the charge and discharge capacity of the battery. Possible causes for low adhesion in water-based, negative graphite electrodes are the migration of SBR binder particles during the drying process and a small contact area between graphite particles and the current collector field.

The orientation of the graphite particles in the liquid paste in the preparation of water-based graphite electrodes and the associated shortened paths can lead to increased binder migration during drying. In the process, the SBR binder particles can increasingly separate from the interface between coating and straw receiver film, which in turn can lead to poor adhesion.

Further, the vertical orientation of the graphite particles on the straw receiver sheet during the loading and unloading operation and the concomitant expansion and contraction of the graphite particles can lead to increased formation of stresses at the interface between the coating and the current collector foil. The vertical arrangement of the graphite particles leads to the fact that when charging the expansion of the graphite particles takes place in the same direction. This graphite particles that are next to each other, displace each other. The associated stresses may over time lead to a reduction of the adhesion from the coating to the current collector foil. Solutions for improved adhesion between coating and current collector foil are disclosed in the invention. Solution variant A:

In order to reduce the stresses during expansion and contraction of the aligned graphite particles that may arise during charging and discharging, the angle of inclination of the graphite particles relative to the stent receiver film may be adjusted through the use of the corresponding magnetic tool during the manufacturing process. Preferably, the angle of inclination of the graphite particles is between 45 ° and 85 °. In this way, a significant portion of the expansion of the graphite particles may take place in the direction away from the current collector foil so that less stress builds up between the graphite coating and the current collector foil, thereby increasing the adhesion to the current collector foil.

Solution variant B:

Furthermore, the invention discloses a solution to the problem of reduced adhesion due to binder migration, by the use of a thermoresponsive component contained in the paste to be coated. This component, for example methylcellulose, under the action of heat causes the applied wet paste to solidify. The solidification can thereby reduce the migration of the SBR binder (styrene-butadiene-rubber) particles during the drying phase. This ensures that the concentration of SBR binder particles at the interface between graphite coating and Stromaufnehmerfoiie remains sufficiently high and in this way a higher adhesion is achieved. The reduced binder migration due to the use of a solidifying component may also allow for higher drying temperatures. Higher drying temperatures are usually avoided because they lead to a stronger binder migration and thus lower adhesion. Higher temperatures, however, allow an accelerated drying of the layer / coating and thus ensure a shortening of the drying time or a higher web speed. Both can lead to cost savings.

The mechanical processing of coated films, such as graphite coatings on Stromnehmernehmerfoüen, may lead to stresses at the interface between the coating and film under certain circumstances. Especially in processes such as calendering and rolling up of coated films, such as negative electrodes for the production of rechargeable lithium-ion batteries, it can lead to delamination and formation of breakages in the coating (production of so-called electrode coils, engl. Jelly Rolls).

The invention discloses a solution to this problem by the controlled orientation of the graphite particles in relation to the loading or processing direction, which is typically a direction parallel to the film. In this way, for example, vertically oriented graphite particles can be aligned by the use of the corresponding magnetic tool to an angle of up to 60 °, for example 45 °, with respect to the loading or processing direction of the moving object. This may be particularly advantageous when the manufacture and subsequent working (e.g., calendering or rolling up of the article) takes place in the same direction, as this can avoid breakages during processing.

For alignment of graphite particles along two directions, a strong changing magnetic field (eg 0.4 Tesla), eg a rotating magnetic field, has to be applied to the graphite paste. Therefore, according to the invention, a magnetic field is applied directly to the object by means of a magnetic tool. in particular a graphite coating which contains graphite particles, a binder and, in the case of a volatile component during drying, is applied with a preferably flat or cuboidal design. A device corresponding to such a magnetic tool will be disclosed below.

Magnetic fields with a flux density of over 100 mT are technically difficult to produce with electromagnets over large areas (10 cm ² to 1 m ² ) and are most easily produced with permanent magnets, in particular with rare earth magnets. Therefore, the magnetic field of the magnetic tool is generated by one or a plurality of permanent magnets.

The inventive magnetic tool has a surface which faces the moving object. The movement of the object is tangential to this surface, the surface of the magnetic tool may have various shapes, preferably planar, cylindrical, or curved.

On the surface of the magnetic tool three main directions are distinguished, which in Fig. 6, the "magnetic-change direction (x)" goes along the surface of the magnetic tool so that the magnetic field changes as it moves in that direction. Orthogonal to the magnetic change direction (x) shows the "constant field direction (y)" along the surface of the magnetic tool, so that the magnetic field does not change along this direction. The third direction is the normal to the surface of the magnetic tool (z) that is orthogonal to both the magnetic change direction (x) and the constant field direction (y).

The following describes the orientation and change of the magnetic field along the surface of the magnetic tool. As shown in FIG. 6, at a point A on the surface of the magnetic tool, the magnetic field vector is a component along the y direction and the z direction, but no component along the x direction. The direction of the magnetic field at this point A is described by the directional vector MO. The angle between MO and the y-direction is the tilt angle of the magnetic field (alpha) and is between 0 degrees and 180 degrees.

As an example of a periodic field change, a rotation is described here. During a movement from point A along the magnetic change direction (x), the magnetic field vector first points in the MO direction, then against the x direction, then against the MO direction, then in the x direction and then to Completion of a full rotation at point B back to the M0 direction. The distance between point A and point B is the "magnetic change period (P)" and is 1 mm and 2 m, preferably 5 mm to 20 cm, particularly preferably 60 mm.

In order to produce in the article, in particular a graphite coating, a changing magnetic field, for example rotating or periodic, the graphite coating is moved relative to the surface of the magnetic tool. The distance between the object and the surface is preferably 0-50 mm, particularly preferably 1-5 mm. It is possible that the object and the surface are in contact, ie have a distance of 0mm.

The relative movement between the object and the magnetic tool can be achieved in a planar tool surface by a displacement of the object, a displacement of the tool, or a combination of both displacements. In a cylindrical tool surface, the relative movement, for example, rotation or oscillation of the cylindrical tool surface, can be achieved in opposite or parallel to the direction of movement of the object, as shown in Fig. 8. In the continuous production process of an article, especially a film with graphite coating, this article is typically in a uniform motion. In order to control the orientation of the graphite particles relative to the direction of movement, the magnetic change direction (x) of the magnetic tool is set relative to the direction of movement. For example, when the magnetic-change direction (x) of the magnetic tool is parallel to the moving direction of the object, the graphite particles are aligned along the moving direction. In another example, the magnetic change direction (x) of the magnetic tool may be set at an angle of 45 degrees to the moving direction of the object, so that the graphite particles are oriented at an angle of 45 degrees to the moving direction. The inclination angle of the particles relative to the surface of the article is given by the inclination angle (alpha) of the magnetic field of the magnetic tool and can be controlled by this.

The realization of a magnetic tool that corresponds to the preceding description can also be achieved approximately. Possible implementations of a magnetic tool that corresponds approximately to the preceding description are disclosed below.

A simple implementation of a single magnetic tool that corresponds to the previous description is a Halbach array FIG. 7. Here, a Halbach array is an array of permanent magnets. The magnetization direction of the magnets in the x direction of the magnetic tool changes stepwise. For example, in a Halbach array with a period of 4 magnets, the magnetic field orientation changes 90 ° per magnet as shown in FIG. Halbach arrays with more steps per period are possible. Of the Angle of inclination of the magnetic field in the Halbach array is typically 90

Degree.

To achieve other angles of inclination between 0 and 180 degrees, preferably between 10 and 170 degrees, of the magnetic field in the magnetic tool, a Halbach-like array can be constructed. For this purpose, permanent magnets are used with a magnetization which is not orthogonal to one of the mechanical surfaces. The angle of inclination corresponds to the angle alpha in FIG. 6. For continuous production methods, it may be helpful to choose the outer edges of the magnetic tool parallel to the direction of movement of the object, wherein the magnetic change direction (x) is not parallel to these directions. A possible realization of such a magnetic tool can be seen in Fig. 9 and is achieved by a Halbach-like configuration in which the permanent magnets are rotated by an angle 077.

Another implementation may be a permanent magnet imprinted with a rotating magnetic field similar to the Halbach configuration along the x-direction during its magnetization (Figure 7 below). In the magnetization of such a magnet, angles of inclination of the magnetic field between 0 and 180 degrees, preferably between 10 and 170 degrees, relative to the surface of the tool can be achieved.

Another implementation of a cylindrical magnetic tool may be a Halbach cylinder such as shown in FIG. 8. Like a Halbach array, a Haibach cylinder can have multiple magnets per period, for example four as shown in FIG. 8 (center). In the Halbach cylinder, the inclination angle of the magnetic field is 90 ° and the magnetization change direction (x) is orthogonal to the cylinder axis. Another cylindrical magnetic tool can be constructed as a Halbach-like cylinder, wherein the inclination angle alpha of the magnetic field, magnetic change direction, and composition correspond to the Halbach-like array. Preferably, the circumference of each cylindrical magnetic tool is an integer multiple of the magnetic period length.

A magnetic tool of greater width along the y-direction can be achieved by lining up several magnetic tools along their y-direction. Also, a magnetic tool can be extended along the x-direction by juxtaposing a plurality of magnetic tools along its x-direction. Also, a magnetic tool with higher magnetic flux density can be generated by arranging two magnetic tools so that their surfaces face each other. This applies to all examples of magnetic tools listed below (the extensibility is therefore not repeated in detail).

With a juxtaposition of magnetic tools along the y-direction, distances to the mechanical stabilization between the tools may be necessary. These distances are preferably 0-10 mm, preferably 0-2 mm. These distances can lead to inhomogeneities in the magnetic field, which lead to inhomogeneities in the processed object, which in turn can lead to negative effects in the final product, for example a battery. To avoid these effects, these distances can be offset along the y-direction, so that they are distributed uniformly over the width of the magnetic tool and thereby an approximately constant field along the y-direction is achieved.

Areas of application of the method and tool according to the invention:

Roll diameter: 1mm-10m, 1cm-1m, 1cm-50cm

Roll length: 1 cm-100m, 10cm-10m, 1m-5m

Wrap angle: 0 ° -360 °, 15 ° -275 °, 90 ° -180 °, preferably 150 °

Film thickness: 0.1 pm-10 cm, I pm-1 cm, 10ym-1 mm Magnetic field strength: 1 μΤ-10Τ, 10mT-1T, 100mT-500mT

Inclination angle of the magnetic field: 0-180 °, 45-135 °, 70-1 10 °

Length of magnetic tool (x): 1cm-100m, 10cm-10m

Width of magnetic tool (y): 1 cm-10m, 30cm-3m

Rotation speed: 1 / ps-1 / h, 1 / ms-1 / min, 10 / s-0.1 / s

Film speed: 1 mm / min-1000m / min, 1 cm / min-100m / min, 5m / min-50m / min

The invention will be further described below in two embodiments with reference to a drawing. In the drawing show the

Fig.: General representation of the inventive method under

Use of a magnetic tool;

FIG. 2: Method using a planar surface magnetic tool according to the invention; FIG.

Fig. 3: Method using a bent-type magnetic tool

Surface;

Fig. 4: Method using a magnetic tool, as

rotatable roller is formed;

Fig. 5: Method using a magnetic tool, as

rotatable roller with wrapping of the object

is trained;

Fig. 6: Magnetic tool with magnetic surface and magnetic orientation directions;

Fig. 7: Examples of the construction of a magnetic tool with planar

Surface;

Fig. 8: Examples of the construction of a magnetic tool with a cylindrical surface;

Fig. 9: embodiments of the inventive magnet arrangement;

FIG. 10: a scanning electron micrograph of a graphite coating in FIG Cross section, without the use of a changing

Magnetic field was produced;

Fig. 1 1: a histogram for orientation of layer planes of

Graphite coating in cross-section, which was made without the application of a changing magnetic field;

FIG. 12: a scanning electron micrograph of a graphite coating in FIG

Cross section using a changing

Magnetic field was produced;

FIG. 13: a histogram for orientation of layer planes of FIG

Graphite coating in cross-section, which was made with the application of a changing magnetic field.

EXAMPLE 1 (Coating with Halbach Array and Without Thermo-Resistant Component) 97 g of platelet-shaped graphite are kneaded with 25 g of carboxymethylcellulose (CMC) solution (2% by weight) and 41 g of de-ionized water for 1 h and subsequently with a further 25 g of CMC Solution (2 wt%) and 30 g de-ionized water with stirring diluted. 5 g of an SBR latex (40% by weight) are then added to this mixture and stirred for 2 minutes. The resulting graphite paste is then applied as a liquid film with a doctor blade onto a Stromaufnehmerfolie025 (copper foil 15 μιτι), which was previously clamped between two rubber rollers, not shown. Subsequently, these two rubber rollers are brought to rotate by means of an electric motor so that the current collector foil 025 moves with the coating thereon, in the example at a speed of 3 m / min, in the direction of movement 045 (see, for example, FIG ).

Thereupon, a magnetic tool having a magnetic surface 013 and in the form of a rigid, planar magnetic tool 010, comprising a package having a plurality of permanent magnets 075 (FIG. 7) in the arrangement of FIG Halbach arrays led to the object 020, in the example under the moving object 020.

Provided is a distance 071 between the magnetic tool 010 and the object 020. The magnetic field of the tool 010 has a side with a strong magnetic field 072 and a side with a weak magnetic field 073. FIG. 7 furthermore shows a permanent magnet 074 with continuously changing magnetization. The strong magnetic field 072 is in each case preferably facing the object 020. The magnetic field of the tool 010 acts on the moving, coated current collector foil 025, which in this example represents the moving object 020. The relative movement between the moving object 020 (the coated current collector foil 025) and the magnetic tool 01 O generates a time-varying magnetic field in the object 020, which leads to the vertical alignment of the graphite particles.

Next, the current collector foil 025, which is moving together with the liquid graphite coating, is blown with hot air guns 030 and thus the graphite coating is dried. The volatile component (water) is removed and immobilized the vertically oriented graphite particles.

Example 2 (Coating with Halbach Array and Thermoresponsive Gelation):

97 g of platelet-shaped graphite are kneaded with 7.5 g of carboxymethylcellulose (CMC) solution (2 wt%), 23.3 g of a methylcellulose (MC) solution (1 .5 wt%, thermoresponsive component) and 34.7 g of de-ionized water for 1 h and then with further 7.5 g of carboxymethylcellulose (CMC) solution (2 wt%), 23.3 g of a methylcellulose (MC) solution (1 .5 wt%) and 10 g de-ionized water with stirring diluted. 5 g of an SBR latex (40% by weight) are then added to this mixture and stirred for 2 minutes.

The resulting graphite paste is then applied as a liquid film with a squeegee in a thickness of 200 microns on a current collector foil 025 (copper foil 15 pm), which was previously clamped between two rubber rollers, not shown. Subsequently, these two rubber rollers are brought to rotate by means of an electric motor so that the current collector foil 025 moves with the coating thereon, in the example at a speed of 3 m / min, in the direction of movement 045 (see, for example, FIG ).

Thereafter, a magnetic tool having a magnetic surface 013 and in the form of a rigid planar magnetic tool 010 comprising a package of multiple permanent magnets 075 (FIG. 7) in the arrangement of a Halbach array is guided to the object 02, in the example below the moving one Coated current collector foil 025. Provided is a gap 071 between the magnetic tool 010 and the object 020. The magnetic field of the tool 010 has a side with a strong magnetic field 072 and a side with a weak magnetic field 073. FIGS. 7 and 8 furthermore show a permanent magnet 074 with continuously changing magnetization.

The strong magnetic field 072 is in each case preferably facing the object 020.

The magnetic field of the tool 010 acts on the moving, coated current collector foil 025, which in this example also represents the moving object 020. The relative motion between the moving object 020 (the coated current collector foil 025) and the magnetic tool 010 creates a time-varying magnetic field in the object 020 that results in the vertical alignment of the graphite particles. Subsequently, heat is applied to the moving coated current collector foil 025 by means of IR radiant heaters. The heat causes gelation of the coating. Thereafter, the magnetic tool 010 is removed below the current collector foil 025 and blown onto the coating with hot air guns 030, thereby drying the coating (Fig. 1).

Examples with a cylindrical magnetic tool 01 1 are shown in Figures 4, 5, and 8. This tool 01 1 in turn has a magnetic surface 013 and a rotating roller 012. The article 020 wraps around the tool 01 1 with a defined wrap angle 022 of, for example

160 °.

The permanent magnets 075 may be formed as segments 078 and / or arranged perpendicular or at an angle 077 to the axis of rotation.

Fig. 10 shows a scanning electron micrograph of a cross section of a graphite coating with flaky graphite obtained without the action of a magnetic field. The platelet-shaped graphite particles lie parallel to the underlying current collector foil 025.

FIG. 11 shows a histogram of the orientation distribution of the graphite particles in a graphite coating which was obtained without the action of a magnetic field.

Fig. 13 shows a histogram of the orientation distribution of the graphite particles in a graphite coating obtained by the method described in Example in a magnetic field. The lamellar graphite particles are mostly vertical (at 90 ^° angle) to the underlying copper foil, the current collector foil 025.

A scanning electron microscope analysis of a cross section of the graphite coating obtained by the example shows the vertical orientation of the graphite coating Fig. 12 is a scanning electron micrograph of a cross section of an oriented graphite coating with flaky graphite obtained by the method described in Examples in a magnetic field.

The lamellar graphite particles are mostly vertical (at 90 ° angle) to the underlying copper foil, the current collector foil 025.

The analysis of the coating by means of an X-ray diffraction apparatus (Riagaku Smart Lab) shows in Fig. 11 a significantly increased amount of graphite particles whose (1-10) plane, the plane which is parallel to the graphene layers of the graphite particles, vertical, i. 90 ° to the current collector foil 025, compared to a graphite coating which is not exposed to a rotating magnetic field (Figure 13). The graphite coating obtained according to the invention with the vertically oriented platelet-shaped particles contained therein is then calendered to a porosity of 30%.

Further subsequent analysis of the compressed graphite coating by means of an X-ray diffraction apparatus (Riagaku Smart Lab) results in a further significantly increased intensity for graphite particles whose (1 10) plane, the plane which is parallel to the graphene layers of the graphite particles, is oriented vertically to the current collector foil 025.

List of reference numbers:

010 magnetic tool

01 1 cylindrical magnetic tool

012 (fixed) center, around which a rotatable roller moves

013 magnetic surface of the magnetic tool

020 moving object on which the magnetic field acts

022 wrap angle

025 current collector foil

030 External influence, eg. B. hot air, Lichtbestrahiung, X-rays 045 direction of movement of the object

071 Distance between magnetic tool and object

072 strong magnetic field

073 weak magnetic field

074 Permanent magnet with continuously changing magnetization

075 permanent magnet

077 angle

078 permanent magnetic segment

Claims

claims

1 . Method for applying magnetic fields to an object (020), which is in particular a layer or a layer-coated object, in particular during manufacture and / or processing of the object (020), wherein a magnetic tool (010, US Pat. 01 1) including an array of at least one permanent magnet (74), characterized in that the article (020) is subjected to a changing magnetic field.

2. The method according to claim 1, characterized in that the application of magnetic fields takes place continuously.

3. The method according to claim 1 or 2, characterized in that the magnetic field is temporally and / or locally variable, in particular periodically changing, or rotating or oscillating.

4. The method according to any one of claims 1 to 3, characterized in that the layer or coating particles, in particular magnetically influenced

Components, particles, carbon particles and in particular graphite particles containing.

5. The method according to any one of claims 1 to 4, characterized in that the force acting on the article (020) flux density of the magnetic field is less than 2.0 T, preferably 0.1 - 0.5 T and particularly preferably 0.4 T.

6. The method according to any one of claims 1 to 5, characterized in that the distance from the surface of the magnetic tool (010, 01 1) to the object is 0-50 mm, preferably 3 mm.

7. The method according to any one of claims 1 to 6, characterized in that the layer or coating in the form of a paste which contains a volatile component, takes place and the application of the magnetic field before and / or during the removal of a volatile component of the paste.

8. The method according to any one of claims 1 to 7, characterized in that the article (020) is an electrode for an electrical energy storage, in particular an electrode for a lithium-ion battery and in particular a graphite-based negative electrode for a lithium-ion battery is.

9. A method for fixing constituents of a layer or coating according to a method for applying magnetic fields to an article (020) according to any one of claims 1 to 8, characterized in that the layer or coating contains a component which leads to a solidification / gelation the layer or coating leads.

10. The method according to claim 9, characterized in that the layer or coating contains a component which leads to an increase in the layer or coating temperature to solidification / gelation of the layer or coating.

1 1. A method according to claim 9 or 10, characterized in that the layer or coating has a Lower Critical Solution Temperature, called LCST, which is between 25 ° C and 80 ° C, preferably between 30 ° C and 60 ° C, more preferably between 35 ° C and 50 ° C.

12. The method according to any one of claims 9 to 1 1, characterized in that the layer or coating contains a thermoresponsive component with a mass fraction of 0.0001 t% - 8.0wt%, preferably 0.1 -0.4wt%.

13. The method according to any one of claims 9 to 12, characterized in that the layer or coating by increasing the coating or coating temperature by the use of heated rollers and / or I ER heaters and / or heated blowers for solidification / gelling is brought ,

14. The method according to any one of claims 9 to 13, characterized in that the layer or coating contains a volatile component which is removed during and / or after the solidification / gelling process.

A method according to claim 14, characterized in that less than 50% of the volatile component is removed from the layer or coating during the solidification ZGeliervorgangs, preferably less than 10%.

16. The method according to any one of claims 9 to 15, characterized in that the layer or coating contains particles, in particular magnetically influenced components, in particular magnetically influenced particles, in particular magnetically influenced carbon particles and particularly preferably magnetically influenced graphite particles.

17. The method according to any one of claims 9 to 16, characterized in that the layer or coating contains a thermoresponsive component containing substituted and / or unsubstituted anhydroglucose rings.

18. The method according to any one of claims 1 to 17, characterized in that the object (020) relative to the magnetic tool (010, 01 1) is movable, in particular tangentially / parallel to the surface of the magnetic tool (010,

01 1).

19. An article, in particular an electrode, and in particular a particle-coated electrode, preferably a coated with graphite particles negative electrode, which is prepared by a process according to claims 1 to 17.

20. A magnetic tool for in particular continuous application of magnetic fields to an object (020), which is in particular a layer or a layer-coated object, characterized in that the magnetic tool (010, 01 1) comprises at least one permanent magnet (074, 075) which generates in one direction a locally variable, in particular a rotating magnetic field, on the surface of the magnetic tool (010, 01 1) and generates an approximately constant magnetic field in a direction orthogonal thereto.

21. Magnetic tool according to claim 20, characterized in that it contains a plurality, at least two permanent magnets (074, 075).

22. Magnetic tool according to claim 20 or 21, characterized in that at least one or all permanent magnets (074, 075) in the magnetic tool (010, 0 1) part of a Halbach array or a Halbach-like array or a Halbach cylinder or are a Halbach-like cylinder.

23. Magnetic tool according to one of claims 20 to 22, characterized in that the magnetic rotation period (P) of the magnetic tool (010, 01 1) is 1 mm to 2m, preferably 5mm to 20cm, more preferably 60mm.

24. Magnetic tool according to one of claims 20 to 23, characterized in that the surface of the magnetic tool (010, 01 1) is planar, cylindrical or curved.

25. Magnetic tool according to one of claims 20 to 24, characterized in that the inclination angle (a) of the magnetic field of the magnetic tool (010, 01 1) is 45-135 °, preferably 80 ° -100 °.

26. Magnetic tool according to one of claims 20 to 25, characterized in that on the article (020) acting flux density of the magnetic field is less than 2.0 T, preferably 0.1- 0.5 T, more preferably 0.4

T.

27. Magnetic tool according to one of claims 20 to 26, characterized in that it comprises at least two tools (010, 01 1) according to one of claims 20 to 25, are lined up, wherein the juxtaposition in a direction parallel to the surface of the assembled Magnetic tool is done.

28. Magnetic tool according to one of claims 20 to 27, characterized in that the surface (013) of the magnetic tool (01 1) is cylindrical, so that object (020) and magnetic tool (01 1) by rotation of the cylindrical tool surface, in opposite directions or in the same direction to the direction of movement of the object (020), are movable.