METHOD FOR PRODUCING A POLYMER COMPOSITE MATERIAL FOR AN ELECTROCHEMICAL CELL BY MEANS OF A SWOLLEN POLYMER

Abstract

The present invention relates to a method for producing a polymer composite material, particularly an electrode (10) and/or a separator, for an electrochemical cell, particularly for a battery cell and/or fuel cell and/or electrolysis cell. In order to improve the production of polymer composite materials, in the form of electrodes and/or separators, for example, particularly for electrochemical cells, and the properties and/or functionality thereof, such as the specific energy density and/or electrical conductivity thereof, at least one swellable polymer (1) is mixed with a solvent quantity of at least one solvent (2), which can be absorbed completely in the at least one swellable polymer (1) by swelling the at least one swellable polymer (1) and which swells the at least one swellable polymer (1), and with at least one particulate material (3, 4). A polymer composite material, particularly an electrode (10) and/or a separator, for an electrochemical cell, particularly for a battery cell and/or fuel cell and/or electrolysis cell, is then formed from the mixture (1, 2, 3, 4).

Claims

1. A process for producing a polymer composite material, the method comprising mixing at least one swellable polymer (1) is mixed with such an amount of at least one swelling solvent (2) which swells the at least one swellable polymer (1) that the amount of solvent can be taken up completely in the at least one swellable polymer (1) by swelling of the at least one swellable polymer (1) and with at least one particulate material (3, 4), and forming a polymer composite material from the mixture (1, 2, 3, 4).

2. The process as claimed in claim 1, wherein the process is configured for producing an electrode (10) and/or a separator for an electrochemical cell and the at least one particulate material (3, 4) comprises at least one electrode material (3, 4), in particular at least one active electrode material (3), and/or at least one particulate electrode additive (4), in particular at least one electric conductor (4), or at least one particulate separator additive, in particular at least one particulate, electrically insulating inorganic compound, and an electrode (10) and/or a separator for an electrochemical cell is formed from the mixture (1, 2).

3. The process as claimed in claim 1, wherein the at least one swellable polymer (1), the at least one swelling solvent (2) and the at least one particulate material (3, 4) are additionally mixed with at least one further polymer (5).

4. The process as claimed in claim 1, wherein the at least one swelling solvent (2) is firstly mixed with the at least one particulate material (3, 4), in particular with the at least one electrode material (3), in particular with the at least one active electrode material (3), and the at least one swellable polymer (1) and optionally the at least one further polymer (5) are then mixed in.

5. The process as claimed in claim 1, wherein the at least one swelling solvent (1) is firstly mixed with the at least one particulate material, in particular with the at least one electrode material (3, 4), in particular with the at least one active electrode material (3), and the at least one further polymer (5) is then mixed in and at least partially fibrillated by means of a mixing process, and the at least one swellable polymer (1) is then mixed in, in particular with the at least one swelling solvent (2) being taken up completely in the at least one swellable polymer (1), and the polymer composite material, in particular the electrode (10) and/or the separator, is formed from the mixture (1, 2, 3, 4, 5), in particular by rolling-out and/or by pressing and/or by extrusion and/or by printing.

6. The process as claimed in claim 1, wherein the at least one swellable polymer (1) and the at least one swelling solvent (2) are firstly mixed with the at least one particulate electrode additive (4), in particular carbon black, in particular with the at least one swelling solvent (2) being taken up completely in the at least one swellable polymer (1), the at least one active electrode material (3) and optionally the at least one further polymer (5) are then mixed in, and the polymer composite material, in particular the electrode (10) and/or the separator, is formed from the mixture (1, 2, 3, 4, 5), in particular by rolling-out, in particular by means of a calender, and/or by pressing and/or by extrusion and/or by printing.

7. The process as claimed in claim 1, wherein the mixture (1, 2, 3, 4, 5) is firstly pressed to give a granular material, and the polymer composite material, in particular the electrode (10) and/or the separator, is formed from the granular material (1, 2, 3, 4, 5), in particular by extrusion and/or by pressing and/or by rolling-out, in particular by means of a calender, and/or by printing.

8. The process as claimed in claim 1, wherein the at least one swelling solvent has a boiling point of ≥100° C., in particular ≥150° C.

9. The process as claimed in claim 1, wherein the amount of the at least one swelling solvent (2) which can be taken up completely in the at least one swellable polymer (1) by swelling of the at least one swellable polymer (1) is, based on the total weight of the at least one swellable polymer (1), in a range from ≥2% by weight to ≤20% by weight and/or is, based on the total weight of the in particular pseudo-dry polymer composite material, in particular electrode and/or separator, formed from the mixture, in a range from ≥0.005% by weight to ≤5% by weight, in particular in a range from ≥0.01% by weight to ≤2% by weight.

10. The process as claimed in claim 1, wherein the polymer composite material, in particular electrode and/or separator, formed from the mixture or from the granular material comprises, based on the total weight thereof: from ≥80% by weight to ≤99% by weight, in particular from ≥90% by weight to ≤99% by weight, of the at least one particulate material (3, 4), in particular active electrode material (3), in particular of at least one nickel and/or cobalt and/or manganese oxide, and/or graphite, or of the at least one separator additive, and from ≥0.01% by weight to ≤5% by weight, in particular from ≥0.01% by weight to ≤3% by weight, of the at least one swellable polymer (1), in particular polyethylene oxide and/or polyvinylidene fluoride, and from ≥0.005% by weight to ≤5% by weight, in particular from ≥0.01% by weight to ≤2% by weight, of the at least one swelling solvent (2), and optionally from ≥0.01% by weight to ≤3% by weight, in particular from ≥0.01% by weight to ≤2% by weight, of the at least one particulate electrode additive (5), in particular of the at least one electric conductor, in particular carbon black, and/or optionally from ≥0.01% by weight to ≤5% by weight, in particular from ≥0.01% by weight to ≤3% by weight, of the at least one further polymer (5), in particular polytetrafluoroethylene.

11. The process as claimed in claim 1, wherein the at least one swellable polymer (1) comprises or is at least one halogenated and/or unhalogenated polyolefin, in particular polyvinylidene fluoride and/or poly(vinylidene fluoride-hexafluoropropylene) and/or polyethylene and/or polypropylene, and/or at least one polyalkylene oxide, in particular polyethylene oxide, and/or at least one polyacrylate and/or polymethacrylate, in particular polymethyl methacrylate, and/or at least one polyacrylonitrile and/or at least one styrene-butadiene rubber and/or at least one alginate and/or at least one malonate and/or polyvinylpyrrolidone and/or carboxymethyl cellulose and/or polystyrene and/or a copolymer thereof, in particular a polyethylene oxide-polystyrene copolymer and/or a polyethylene oxide-polyacrylate copolymer, and/or a mixture thereof, and/or wherein the at least one swelling solvent (2) comprises or is formed by at least one organic electrolyte solvent, in particular at least one lactone, in particular gamma-butyrolactone, and/or at least one organic carbonate, in particular ethylene carbonate and/or ethyl methyl carbonate and/or dimethyl carbonate and/or diethyl carbonate and/or vinylene carbonate, and/or at least one monofluorinated, polyfluorinated or perfluorinated lactone and/or at least one monofluorinated, polyfluorinated or perfluorinated organic carbonate and/or at least one unfluorinated or fluorinated oligoalkylene oxide and/or polyalkylene oxide, in particular oligoethylene oxide and/or polyethylene oxide, in particular having ≤50 repeating units, and/or at least one ionic liquid, in particular comprising imide anions, in particular bis(trifluoromethanesulfonyl)imide anions and/or bis(fluorosulfonyl)imide anions and/or bis(perfluoroethanesulfonyl)imide anions, and/or tosylate anions and/or triflate anions and/or pyrrolidinium cations, in particular N-methyl-N-propylpyrrolidinium cations.

12. The process as claimed in claim 1, wherein the at least one swellable polymer (1), the at least one swelling solvent (2) and the at least one particulate material (3, 4) are additionally mixed with at least one electrolyte salt, in particular with at least one lithium electrolyte salt, and/or wherein the at least one swelling solvent (2) contains at least one electrolyte salt, in particular lithium electrolyte salt.

13. The process as claimed in claim 1, wherein the polymer composite material, in particular the electrode (10) and/or the separator, in particular in the form of a self-supporting film and/or a coating, is formed from the mixture (1, 2, 3, 4, 5) or from the granular material by a dry production process, in particular without addition of liquid, in particular by dry coating and/or by dry printing and/or by a dry pressing operation and/or by dry rolling-out, in particular by means of a calender, and/or by dry extrusion.

14. The process as claimed in claim 1, wherein the process is configured for producing an electrochemical cell, in particular a battery cell and/or a fuel cell and/or an electrolysis cell, and the polymer composite material, in particular the electrode (10) and/or the separator, is installed in a cell, in particular with the cell being a polymer electrolyte cell or the cell being filled with at least one liquid electrolyte and being a liquid electrolyte cell.

15. A polymer composite material, in particular electrode (10) and/or separator, for an electrochemical cell, in particular for a battery cell and/or fuel cell and/or electrolysis cell, produced by a process as claimed in claim 1.

16. An electrochemical cell produced as claimed in claim 14.

17. The use of a mixture of at least one swellable polymer (1) and at least one swelling solvent (2) which swells the at least one swellable polymer (1) and at least one particulate material (3, 4), wherein the mixture comprises the at least one swelling solvent (2) in an amount which is taken up completely in the at least one swellable polymer (1) by swelling of the at least one swellable polymer (1), for, in particular dry, printing of a particle-filled polymer composite material (10).

18. A process for producing a polymer composite material, in particular an electrode (10) and/or a separator, for an electrochemical cell, in particular for a battery cell and/or fuel cell and/or electrolysis cell, the method comprising mixing at least one swellable polymer (1) with such an amount of at least one swelling solvent (2) which swells the at least one swellable polymer (1) that the amount of solvent can be taken up completely in the at least one swellable polymer (1) by swelling of the at least one swellable polymer (1) and with at least one particulate material (3, 4), and forming a polymer composite material, in particular an electrode (10) or a separator, for an electrochemical cell, from the mixture (1, 2, 3, 4).

19. An electrochemical cell comprising at least one polymer composite material as claimed in claim 15.

20. An electrochemical cell comprising at least one polymer composite material produced as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Further advantages and advantageous embodiments of the subject matter of the invention are illustrated by the drawings and explained in the following description. Here, it should be noted that the drawings have only a descriptive character and are not intended to restrict the invention in any way. The drawings show:

[0089] FIG. 1 a schematic flow diagram to illustrate a first embodiment of the process of the invention; and

[0090] FIG. 2 a schematic flow diagram to illustrate a second embodiment of the process of the invention.

DETAILED DESCRIPTION

[0091] In the embodiment shown in FIG. 1, at least one swellable polymer 1, for example polyvinylidene fluoride and/or polyethylene oxide, is firstly mixed with at least one swelling solvent 2, for example gamma-butyrolactone, and with at least one particulate electrode additive 4, for example conductive carbon black, in a process step A1). Here, the at least one swelling solvent 2 is used in an amount which can be taken up completely in the at least one swellable polymer 1 by swelling of the latter.

[0092] In a process step A2), at least one active electrode material 3 and optionally at least one further polymer (not shown) is then mixed in.

[0093] In a process step b), a polymer composite material 10, in particular in the form of an electrode, for an electrochemical cell is then formed from the mixture 1, 2, 3, 4 by a dry production process, for example by dry rolling-out and/or by dry pressing and/or by dry extrusion and/or by dry printing.

[0094] The process can optionally also comprise a process step A3) (not shown), in which the mixture 1, 2, 3, 4 from process step A2) is firstly pressed to give a granular material, after process step A2) and before process step b), and the polymer composite material, in particular the electrode (10), is then formed from the granular material 1, 2, 3, 4 in process step b), in particular by extrusion and/or by pressing and/or by rolling-out, in particular by means of a calender, and/or by printing.

[0095] In the embodiment shown in FIG. 2, at least one swelling solvent 2, for example gamma-butyrolactone, is firstly mixed with at least one active electrode material 3 in a process step a1). Here, the at least one swelling solvent 2 is used in an amount which can be completely taken up in at least one swellable polymer 1 added in a later process step a3) by swelling of this polymer 1.

[0096] In a process step a2), at least one further polymer 5, for example polytetrafluoroethylene, which is, for example, stable in the at least one swelling solvent 2 and/or does not swell in 2 is then mixed in and at least partially fibrillated by the mixing process.

[0097] In a process step a3), at least one swellable polymer 1, for example polyvinylidene fluoride and/or polyethylene oxide, is then mixed in. Here, the at least one swellable polymer 1 swells with uptake of the entire amount of the at least one swelling solvent 2.

[0098] In a process step b), a polymer composite material 10, in particular in the form of an electrode 10 for an electrochemical cell, is then formed from the mixture 1, 2, 3, 5 by a dry production process, for example by dry rolling-out and/or by dry pressing and/or by dry extrusion and/or by dry printing.

PRELIMINARY EXPERIMENTS

[0099] 500 mg of nanosize polyvinylidene fluoride (PVDF) powder (HSV900 from ARKEMA having an average particle size of about 200 nm) were mixed with 100 mg of gamma-butyrolactone and the mixture was dry on the surface or macroscopically (pseudo-dry) after 30 s.

[0100] 500 mg of micron-size polyvinylidene fluoride (PVDF) powder (Solev 5130 from Solvey) were mixed with 100 mg of gamma-butyrolactone and the mixture was dry on the surface or macroscopically (pseudo-dry) only after some hours.

[0101] 100% strength gamma-butyrolactone does not vaporize under atmospheric pressure at room temperature and up to 60° C. because of its boiling point of about 205° C. and its vapor pressure. A sample of the liquid in a Petri dish did not lose any weight over the same period of time.

Working Example 1

[0102] 94% by weight of 111-nickel cobalt manganese oxide, 2.5% by weight of polyvinylidene fluoride, premixed or preswollen with 0.5% by weight of gamma-butyrolactone, and 3% by weight of conductive carbon black are mixed and rolled out by means of a heated calender to give a self-supporting film.

Working Example 2

[0103] 97% by weight of 111-nickel cobalt manganese oxide, 0.42% by weight of polyvinylidene fluoride, premixed or preswollen with 0.08% by weight of gamma-butyrolactone, 1% by weight of polytetrafluoroethylene and 1.5% by weight of conductive carbon black are mixed and rolled out by means of a heated calender to give a self-supporting film.

Working Example 3

[0104] 96% by weight of 111-nickel cobalt manganese oxide, 0.84% by weight of polyvinylidene fluoride premixed or preswollen with 0.16% by weight of gamma-butyrolactone, 1% by weight of polytetrafluoroethylene and 2% by weight of conductive carbon black are mixed and rolled out by means of a heated calender to give a self-supporting film.