METHOD FOR PRODUCING A PRECURSOR MATERIAL FOR AN ELECTROCHEMICAL CELL

Abstract

The present invention relates to a method for producing a precursor material (10) for an electrochemical cell. The method comprises the steps of adding a matrix material (18) to a fluidized bed (40), and adding a carrier medium (48) and a de-agglomerated carbon nanotube material (22) to the fluidized bed (40), so that the carbon nanotube material (22) and the carrier medium (48) is applied to the matrix material (18) and the latter is granulated therewith, wherein the carbon nanotube material (22) has been suspended and de-agglomerated prior to addition to the carrier medium (48), and/or the carbon nanotube material (22) present in de-agglomerated form in the fluidized bed (40) dissolving with the carrier medium (48) in the fluidized bed (40).

Claims

1. A process for producing a precursor material (10) for an electrochemical cell, wherein the process comprises the steps: introduction of a matrix material (18) into a fluidized bed (40), and introduction of a carrier medium (48) and a deagglomerated carbon nanotube material (22) into the fluidized bed (40) so that the carbon nanotube material (22) is applied together with the carrier medium (48) to the matrix material (18) and the latter is granulated therewith, where the carbon nanotube material (22) has been suspended and deagglomerated in the carrier medium (48) before introduction and/or the carbon nanotube material (22) present in deagglomerated form in the fluidized bed (40) dissolves with the carrier medium (48) in the fluidized bed (40).

2. The process as claimed in claim 1, characterized in that active material particles or solid particles are used as matrix material (18).

3. The process as claimed in claim 1, characterized in that at least one polymer and/or a binder is dissolved in the carrier medium (48) before introduction.

4. The process as claimed in claim 3, characterized in that an electrolyte salt is dissolved together with the at least one polymer in the carrier medium (48) before introduction.

5. The process as claimed in claim 3, characterized in that an electrolyte salt is added during or after granulation.

6. The process as claimed in claim 1, characterized in that a surface (30) of the carbon nanotube material (22) and of the matrix material (18) is modified before introduction into the fluidized bed (40).

7. The process as claimed in claim 1, characterized in that a further amount of polymer is added after granulation.

8. A precursor material (10) for an electrochemical cell, where the precursor material (10) comprises a matrix material (18) to which a carbon nanotube material (22) has been applied to a surface (30), characterized in that the carbon nanotube material (22) is distributed between particles (18a, 18b, 18c) of the matrix material (18) so homogeneously that an agglomerate- and/or clump-free surface structure is formed.

9. The precursor material (10) as claimed in claim 8, characterized in that the matrix material (18) is an active material or is made up of solid particles.

10. The precursor material (10) as claimed in claim 8, characterized in that at least one polymer has been applied to the surface (30) of the matrix material (18).

11. The precursor material (10) as claimed in claim 8, characterized in that an electrolyte salt has been applied to the surface (30) of the matrix material (18).

12. An electrochemical cell which comprises a precursor material (10) as claimed in claim 8.

13. The process as claimed in claim 1, where the carbon nanotube material (22) has been suspended and deagglomerated in the carrier medium (48) before introduction.

14. The process as claimed in claim 1, where the carbon nanotube material (22) present in deagglomerated form in the fluidized bed (40) dissolves with the carrier medium (48) in the fluidized bed (40).

15. The process as claimed in claim 1, where the carbon nanotube material (22) has been suspended and deagglomerated in the carrier medium (48) before introduction and the carbon nanotube material (22) present in deagglomerated form in the fluidized bed (40) dissolves with the carrier medium (48) in the fluidized bed (40).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] A working example of the invention is depicted in the drawing and explained in more detail in the following description. The drawing shows:

[0036] FIG. 1 enlarged section of the precursor material of the invention, with the carbon nanotube material distributed homogeneously between particles of the matrix material,

[0037] FIG. 2 a first working example of the process of the invention for producing the precursor material, and

[0038] FIG. 3 a second working example of the process of the invention for producing the precursor material.

DETAILED DESCRIPTION

[0039] FIG. 1 shows an enlarged section of a precursor material 10 according to the invention with the carbon nanotube material 22 distributed homogeneously between particles 18a, 18b, 18c of the matrix material 18. The carbon nanotube material 22 is in the form of individual carbon nanotube particles 26 which extend between at least two particles 18a, 18b, 18c of the matrix material 18. The carbon nanotube particles 26 are thus, for example, joined by a first end 26a to a surface 30 of a first particle 18a and by a second end 26b to the surface 30 of a second particle 18b, so that the electrical conductivity of the electrode is increased and an agglomerate- and/or clump-free surface structure is formed.

[0040] FIG. 2 shows a first working example of the process of the invention for producing the precursor material 10. In this process, the matrix material 18 is introduced into a fluidized bed 40 of a fluidized-bed reactor 44 in a first step (not shown). Such a fluidized-bed reactor 44 can be a fluidized-bed reactor 44 known from the prior art. The fluidized-bed reactor 44 is formed essentially by a vessel 45 which is closed at the bottom by a perforated plate 46 on which the matrix material 18 has been placed.

[0041] In a second step, the deagglomerated carbon nanotube material 22 is introduced via a nozzle 52a and the carrier medium 48, which is preferably a solvent, is introduced via a nozzle 52b into the fluidized bed 40 at high speed through at least one of the nozzles 52a, 52b. In the fluidized bed 40, the matrix material 18 is picked up by the flows exiting from the nozzles 52a, 52b and circulates in normal circular movements 54 in the vessel 45. The carbon nanotube material 22 introduced is firstly picked up by the carrier medium 48 in the spatial vicinity of the nozzles 52a, 52b and forms a suspension 56. A multifluid nozzle through which carrier medium 48 and carbon nanotube material 22 are conveyed simultaneously, in particular concentrically, is particularly advantageously used. A suspension 56 is formed quickly and uniformly in this way.

[0042] Subsequently, repeated contact of carbon nanotube material 22 and carrier medium 48 with the matrix material 18 occurs. The liquid bridges of the carrier medium 48 lead to coalescence of the matrix materials 18. At the same time, the carrier medium 48 vaporizes while the materials travel along the flight paths. Granulation of precursor material 10 occurs here.

[0043] The composition of the suspension 56 can be finely adjusted and varied by variation of the mass flows of the carbon nanotube material 22 and of the carrier medium 48 relative to one another, even during the process. A variation can be implemented particularly advantageously when the carbon nanotube material 22 is present in deagglomerated form in a fluid without polymer binder and is transported through the nozzle 52a and additional solvent with a polymer binder can be additionally introduced through the second nozzle 52b. This makes it possible for the agglomerates/precursors at the commencement of the process, i.e. in the interior of the granules, to have a different polymer content than in the outer layer at the end of the process. This can be advantageous when, for example, an electrolyte salt added later is to dissolve quickly in the polymer.

[0044] (Dry) air or another gas can optionally be blown in through the perforated plate 46, so that the matrix material 18 present thereon is loosened and becomes suspended in the stream of air. The matrix material 18 swirls in the fluidized bed. The advantage here is that the nozzles 52a and 52b can now be operated with very small flows. In this way, it is possible to bring a high content of matrix material 18 and only very little carbon nanotube material 22 into contact with one another.

[0045] In a working example which is not shown, the carrier medium 48 and the carbon nanotube material 22 are injected from below by means of two nozzles which are arranged at an angle of 45°.

[0046] FIG. 3 shows a second working example of the process of the invention for producing the precursor material 10. This process differs from the process in the first working example in that the carbon nanotube material 22 has been suspended and deagglomerated in the carrier medium 48 before introduction into the fluidized bed 40; the concentration of the carbon nanotube material 22 in the carrier medium 48 is therefore fixed beforehand. This results in formation of a suspension 56 which is introduced through a single nozzle 52a into the fluidized bed 40. In the fluidized bed 40, the suspension 56 is applied to the matrix material 18 so that the latter is granulated. The precursor material 10 formed in this way can subsequently be taken from the fluidized-bed reactor 44.