WO2018050314A1

WO2018050314A1 - Method for producing an electrode film

Info

Publication number: WO2018050314A1
Application number: PCT/EP2017/067806
Authority: WO
Inventors: Harald Bauer; Lutz Baumgaertner
Original assignee: Robert Bosch Gmbh
Priority date: 2016-09-13
Filing date: 2017-07-14
Publication date: 2018-03-22
Also published as: DE102016217404A1; CN109690831A

Abstract

The invention relates to a method for producing an electrode film (10), wherein a particle mixture is produced from particles of a polymer binder (31) and particles of conductive carbon black (32) by pre-mixing (101), agglomerates are produced from the particle mixture by compacting (103), and, after the addition (102) of an electrochemical active material (33), the electrode film (10) is produced from the agglomerates by rolling (106) or extrusion (107).

Description

description

title

Method for producing an electrode fil ms

The invention relates to a method for producing an electrode film, wherein from particles of a polymer binder and particles of Leitruß by premixing a particle mixture is produced, and wherein after addition of a

electrochemical active material by rolling or extruding the

Electrode film is generated.

PRIOR 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 known as

Cathode is called, and a negative electrode, which is also referred to as anode on. The cathode and the anode each include one

Current conductor, on which an electrode film is applied, which a

having electrochemical active material. The active material for the cathode contains, for example, a metal oxide such as Li 2 MnO 3 and an NCM alloy, So 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.

In addition to the active material, the electrode material of the electrode film often comprises further materials, in particular an electronic conductive component such as carbon black or graphite, and an ionic conductive component such as, for example, a liquid or solid electrolyte. To the mechanical

Stabilization of the electrode material can be used, for example, a polymer binder.

The electrode film can be produced in a wet process. For this purpose, the electrode material is first produced as a slurry and applied to the current conductor as a thin layer. After drying the electrode material, the electrode film is formed directly on the current conductor.

The electrode film can also be produced in a dry process. For this purpose, the electrode film is produced from the prepared electrode material by rolling or extrusion. Subsequently, the electrode film is applied to the current collector by lamination.

Methods for the production of electrode material as well as electrode films are inter alia from the documents US 2015/0061176 AI,

US 2015/0303481 A1, WO 2005/008807 A2, EP 1 644 136 A2,

US 2015/0062779 AI, US 4153661 A, US 4976904 A and DE 43 45 168 AI and from the article: "The agglomeration of particulate solids in Matrizenpressen "by Claas-Jürgen Klasen, Progress Reports VDI, Series 3: Process Engineering, No. 220, VDI-Verlag Dusseldorf 1990 known.

From the article "Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries by Brandon Ludwig, Zhangfeng Zheng, Wan Shou, Yan Wang and

Heng Pan (Scientific Reports | 6: 23150 | DOI: 10.1038 / srep23150) describes a process for the solvent-free production of electrodes. In this case, the electrode material is mixed from dry particles and in a

Hot rolling process rolled into an electrode film.

Disclosure of the invention

A process is proposed for producing an electrode film, wherein particles of a polymer binder and particles of conductive carbon black by premixing a particle mixture is generated, from the particle mixture through

Compaction agglomerates are produced, and wherein after addition of an electrochemical active material from the agglomerates by rolling or extrusion of the electrode film is produced. As the polymer binder, PVDF (polyvinylidene fluoride) is preferably used.

The method is suitable for the production of electrode films for anodes as well as for cathodes. The correspondingly suitable electrochemical active material is selected according to the type of electrode film to be produced. For producing an electrode film for an anode, the

electrochemical active material such as graphite and / or silicon. to

Production of an electrode film for a cathode contains the electrochemical active material, for example NCM, ie an alloy of nickel, cobalt and manganese. The electrochemical active material can be added at various stages of the process.

The compaction of the particle mixture corresponds to a pressing of the particles. This process can be carried out for example in a press or in a roll mill. For carrying out the method according to the invention, for example, one from Hosokawa Micron B.V. developed

Continuous mixer, which is sold under the name "Modulomix". It has been shown that such a continuous mixer, which for the

Pharmaceutical industry has been developed, can also be advantageously used for the production of electrode films by the method according to the invention.

According to an advantageous embodiment of the method, the active material to the particle mixture in a stage prior to the compaction of

Particle mixture added. The active material is thus already in the

Contain particle mixture before passing out of the particle mixture

Compaction agglomerates are generated.

According to one possible variant, the active material is added to the

Particle mixture added during premixing of the particles. The active material is thus added simultaneously with the particles of the polymer binder and with the particles of conductive carbon black, and the particle mixture is generated from the particles of the polymer binder, the particles of conductive carbon black and the active material.

According to another possible variant, the active material is added to the particle mixture after premixing the particles. The

Particulate mixture is thus first generated from the particles of the polymer binder and the particles of conductive soot, and then the active material is added to the particle mixture and mixed with the particle mixture.

According to a further advantageous embodiment of the method, the active material is added to the agglomerates at a stage after compaction of the particle mixture. The particle mixture is thus first produced from the particles of the polymer binder and the particles of conductive carbon black, and agglomerates are produced from the particle mixture by compaction. The active material is then added to the agglomerates and mixed with the agglomerates.

According to yet another advantageous embodiment of the method, the

Active material to the particle mixture in a stage during the

Compaction of the particle mixture added. The active material is thus in of the particle mixture while passing out of the particle mixture

Compaction agglomerates are generated.

According to a possible variant, the particle mixture is generated before the compaction. The active material is thus simultaneously with the

Added particle mixture, and during the compaction is the

Active material mixed with the particle mixture.

According to another possible variant, the particle mixture is generated during compaction. The active material is thus added simultaneously with the particles of the polymer binder and the particles of conductive carbon black, and during compaction the particles of the polymer binder, the particles of conductive carbon black and the active material are mixed to the particle mixture.

According to an advantageous development of the method, agglomerates whose size exceeds a predetermined upper limit are comminuted at a stage prior to rolling or extrusion.

According to yet another advantageous embodiment of the method

Agglomerates whose size is a predetermined lower limit

undershot, screened at a stage prior to rolling or extruding.

According to a further advantageous development of the method, additives and / or a further polymer binder are fed to the particle mixture. The said additives are in particular a

Polymer electrolyte, expanded graphite or carbon nanotubes. As a further polymer binder, for example PTFE (polytetrafluoroethylene) can be used. In addition, for example, a solvent may also be added.

Advantages of the invention

The use of PTFE as polymer binder for the production of agglomerates (precursors) for further processing is possible, but not necessary. It has surprisingly been found that it is sufficient to compact the particle mixtures or to compress them, in particular if the particle mixtures are not to contain PTFE, as is conventional in the press agglomeration. The compressed particle mixtures correspond to classic press agglomerates. By suitable manufacturing processes such as described for example in DE 43 45 168 A, or by classifying the agglomerates can be targeted set size distributions of the agglomerates. These agglomerates can be rolled in a nip of a rolling mill under heating to an electrode film.

The damage of core-shell particles can be avoided in the compaction by a pressing process of the prior art, for example, in pharmacy is well controlled. During the compaction of the particle mixture, a fibrillation process also takes place, through which an ideally homogenized mixture and suitable fibrils and / or nanoparticles are formed in a continuous process. This process comes with very little cleaning effort and thus without significant

Production shutdown off.

In contrast to the statistical residence time in a jet mill, where the

Residence time depends on the particle size and the particle density, the residence time of the particle mixture can be adjusted during compaction. The result is low quality fluctuations in the agglomerates produced. In particular, an independent of the particle state used materials, grinding pressure and injector pressure results. Long residence times of polymers in jet mills lead to deposits and sticking, which is caused by the

inventive method is advantageously avoided.

The setting and regulation of a stable operating point is particularly in the use of annular gap mills or tablet presses in the

Compaction to produce the agglomerates much easier. Also, starting up the process to a stable operating point is after

Downtimes made easier.

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:

1 shows a schematic representation of a method for producing an electrode film according to a first embodiment,

FIG. 2 shows a schematic representation of a method for producing an electrode film according to a second exemplary embodiment,

FIG. 3 shows a schematic representation of a method for producing an electrode film according to a third exemplary embodiment,

4 shows a schematic representation of a method for producing an electrode film according to a fourth exemplary embodiment,

Figure 5 is a schematic representation of a method for producing an electrode film according to a fifth embodiment and

Figure 6 is a schematic representation of a method for producing an electrode film according to a sixth embodiment.

Embodiments of the invention

In the following description of the embodiments of the invention, the same or similar elements are denoted by the same reference numerals, wherein a repeated description of these elements is dispensed with in individual cases. The figures illustrate the subject matter of the invention only schematically.

Figure 1 shows a schematic representation of a method for producing an electrode film 10 according to a first embodiment. First, pre-mixing 101 of particles of a polymer binder 31 and particles takes place of conductive carbon black 32. Polymer binder 31 is PVDF (polyvinylidene fluoride) in the present case.

At the same time, that is to say during premixing 101 of the said particles, an addition 102 of an active material 33 takes place. To produce an electrode film 10 for an anode, the active material 33 contains graphite and / or silicon. To produce an electrode film 10 for a cathode, the active material 33 contains NCM, ie an alloy of nickel, cobalt and manganese. Thus, a particle mixture is produced which contains particles of polymer binder 31, particles of conductive carbon 32 and active material 33.

From the particle mixture 103 agglomerates are then produced by compaction. The agglomerates thus contain polymer binder 31, conductive black 32 and active material 33. Addition of the active material 33 to the particle mixture thus takes place prior to compaction 103 of the particle mixture.

The agglomerates can have different sizes. Agglomerates of a defined size are especially suitable for the subsequent processing. Therefore, a classification of the agglomerates produced according to their size.

First, crushing 104 of agglomerates whose size exceeds a predetermined upper limit is carried out. This is followed by a screening 105 of agglomerates whose size falls below a predetermined lower limit.

From the remaining agglomerates whose size is between the lower limit and the upper limit, the electrode film 10 is then produced by rolling 106 or extrusion 107. The electrode film 10 is brought by cutting 108 to a size suitable for further processing.

Agglomerates, which are removed during the screening 105 and waste of the electrode film 10, which is formed during cutting 108, are recycled and with the agglomerates produced by compaction 103 mixed. Thus, a recycling 109 of the agglomerates removed during the screening 105 and of the cutting of the electrode film 10 resulting from cutting 108 takes place. The cut electrode film 10 is subsequently metallized

Current conductor 12 connected to an electrode 14. For example, in the manufacture of an anode, the current collector 12 is a copper foil. In the manufacture of a cathode, the current conductor 12 is, for example, an aluminum foil. The connection of the cut electrode film 10 to the current conductor 12 takes place here by means of

Lamination 110.

Figure 2 shows a schematic representation of a method for producing an electrode film 10 according to a second embodiment. in the

The following is merely the differences between the second

Embodiment and the first embodiment described above received.

During premixing 101, the particles of polymer binder 31 and the particles of conductive black 32 and the addition 102 of active material 33 become

Additive 40 supplied to the particle mixture. The said additives are in the present case a polymer electrolyte, expanded graphite and carbon nanotubes.

Likewise, during premixing 101, the particles of polymer binder 31 and the particles of conductive black 32 and the addition 102 of active material 33 are fed to another polymer binder 41 of the particle mixture. The further polymer binder 41 is in the present case PTFE

(Polytetrafluoroethylene).

Thus, a particle mixture is produced which contains particles of polymer binder 31, particles of conductive carbon black 32, active material 33, additives 40 and a further polymer binder 41. The additives 40 and the further polymer binder 41 can also be supplied to a later stage of the particle mixture or else the agglomerates. The generated by compaction 103 Agglomerates thus contain polymer binder 31, conductive black 32, active material 33, additives 40 and a further polymer binder 41.

The remaining steps of comminution 104, screening 105 and rolling 106 or extruding 107 agglomerates, cutting 108 of

Electrode film 10, the recycling 109 of the agglomerates removed during the screening 105 and the cutting of the electrode film 10 resulting from cutting 108 and the connection of the cut electrode film 10 to the current conductor 12 by means of lamination 110 to produce the electrode 14 then take place as in the first exemplary embodiment above described.

FIG. 3 shows a schematic representation of a method for producing an electrode film 10 according to a third exemplary embodiment. in the

The following is merely the differences between the third

Embodiment and the first embodiment described above received.

The addition 102 of the active material 33 takes place only after the compaction 103 of the particle mixture to the agglomerates. The active material 33 is therefore not added to the particle mixture but to the agglomerates. The particle mixture produced by premixing 101 thus contains no active material 33 prior to compacting 103. The remaining steps of comminution 104, the screening 105 and the

Rolling 106 or extruding 107 agglomerates, cutting 108 of the electrode film 10, recycling 109 of the agglomerates removed during screening 105 and the cutting of the electrode film 10 resulting from cutting 108 and the connection of the cut electrode film 10 to the current conductor 12 by means of lamination 110 Production of the electrode

14 are then carried out as described above in the first embodiment.

FIG. 4 shows a schematic representation of a method for producing an electrode film 10 according to a fourth exemplary embodiment. in the In the following, only the differences between the fourth exemplary embodiment and the first exemplary embodiment described above will be discussed. The addition 102 of the active material 33 takes place only after premixing

101 of the particles of the polymer binder 31 and the particles of Leitruß 32 to the particle mixture. However, the addition 102 of the active material 33 takes place before the compaction 103 of the particle mixture to the agglomerates. Thus, the agglomerates produced by compaction 103 contain polymer binder 31, conductive black 32, and active material 33.

The remaining steps of comminution 104, screening 105 and rolling 106 or extruding 107 agglomerates, cutting 108 of the electrode film 10, recycling 109 of the agglomerates removed during screening 105 and the cutting of the electrode film 10 and the connection resulting from cutting 108 of the cut electrode film 10 with the current collector 12 by means of lamination 110 for producing the electrode 14 are then carried out as described above in the first embodiment.

FIG. 5 shows a schematic representation of a method for producing an electrode film 10 according to a fifth exemplary embodiment. in the

In the following, only the differences between the fifth exemplary embodiment and the first exemplary embodiment described above will be discussed.

The addition 102 of the active material 33 takes place during the compaction 103 of the particle mixture to the agglomerates. The active material 33 is thus added simultaneously with the compaction 103 of the particle mixture. The particle mixture produced by premixing 101 thus contains before

Compaction 103 no active material 33. However, the agglomerates contain polymer binder 31, conductive black 32 and active material 33.

The remaining steps of comminution 104, screening 105 and rolling 106 or extruding 107 agglomerates, cutting 108 of Electrode film 10, the recycling 109 of the agglomerates removed during the screening 105 and the cutting of the electrode film 10 resulting from cutting 108 and the connection of the cut electrode film 10 to the current conductor 12 by means of lamination 110 to produce the electrode 14 then take place as in the first embodiment above described.

FIG. 6 shows a schematic representation of a method for producing an electrode film 10 according to a sixth exemplary embodiment. The following is only the differences between the sixth

Embodiment and the first embodiment described above received.

The pre-mixing 101 of particles of the polymer binder 31 and particles of conductive black 32 and the addition 102 of the active material 33 take place simultaneously and simultaneously with compaction 103. The particle mixture is thus generated during the compaction 103, and the particles of the polymer binder 31, the particles of Leitruß 32 and the active material 33 are during the

Compaction 103 mixed to the particle mixture.

Thus, a particle mixture is produced which contains particles of polymer binder 31, particles of conductive carbon 32 and active material 33. The agglomerates produced by the compaction 103 thus also contain polymer binder 31, conductive black 32 and active material 33.

The remaining steps of comminution 104, screening 105 and rolling 106 or extruding 107 agglomerates, cutting 108 of the electrode film 10, recycling 109 of the agglomerates removed during screening 105 and the cutting of the electrode film 10 and the connection resulting from cutting 108 of the cut electrode film 10 with the current collector 12 by means of lamination 110 for producing the electrode 14 are then carried out as described above in the first embodiment. In the first, second, third, fourth and fifth embodiments, the production of the agglomerates takes place in two stages. In this case, the particle mixture is first produced by the premixing 101 of the particles, and in a time-sequential step, the compacting 103 of FIG

Particle mixture which produces agglomerates.

In the sixth embodiment, the production of agglomerates takes place in one stage. In this case, the pre-mixing 101 of the particles for producing the particle mixture and the compaction 103 of the particle mixture take place

Generation of agglomerates simultaneously.

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

A process for producing an electrode film (10), wherein

from particles of a polymer binder (31) and particles of Leitruß (32) by premixing (101) a particle mixture is generated from the particle mixture by compaction (103) agglomerates are generated, and wherein

after adding (102) an electrochemical active material (33) from the agglomerates by rolling (106) or extruding (107)

Electrode film (10) is generated.

2. The method of claim 1, wherein

adding (102) the active material (33) to the particle mixture prior to compaction (103) of the particle mixture.

3. The method of claim 2, wherein

adding (102) the active material (33) to the particle mixture during premixing (101) of the particles.

4. The method of claim 2, wherein

adding (102) the active material (33) to the particle mixture after premixing (101) the particles.

5. The method of claim 1, wherein

adding (102) the active material (33) to the agglomerates after compaction (103) of the particle mixture.

6. The method of claim 1, wherein

adding (102) the active material (33) to the particle mixture during compaction (103) of the particle mixture.

7. The method of claim 6, wherein

the particle mixture is generated prior to compaction (103).

8. The method of claim 6, wherein

the particle mixture is generated during compaction (103).

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

comminution (104) of agglomerates whose size exceeds a predetermined upper limit occurs.

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

a sieving (105) of agglomerates, whose size falls below a predetermined lower limit takes place.

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

Additives (40), in particular a polymer electrolyte, expanded graphite, carbon nanotubes and / or another polymer binder (41) are supplied to the particle mixture.