CATALYTICALLY ACTIVE ADDITIVES FOR COKE ORIGINATING FROM PETROL OR COAL

Abstract

The invention relates to a method for producing graphite materials as well as the use thereof in lithium ion batteries

Claims

1-11. (canceled)

12. A method for producing graphite materials, comprising the following steps: a) adding of at least one catalyst which is effective for catalytic graphitisation and is selected from at least one compound of oxides and carbides from the group including the elements iron, nickel, titanium, silicon, and boron to petroleum residues, coal tar pitch, and/or residues from coal gasification, Fischer-Tropsch synthesis, or coal hydrogenation in a delayed coker; b) producing of the doped green coke in the delayed coker; c) calcination of the doped green coke obtained in step b) at 1100-1400 C. to form a doped and calcinated coke; d) mechanical comminution of the doped and calcinated coke; e) shaping a green body made of the doped and calcinated coke from step d) along with a binder additive followed by carbonisation of the green body; f) graphitisation of the carbonised green body from step d) at temperatures of greater than 2600 C., preferably greater than 2800 C., and particularly preferably greater than 3000 C. using the Acheson or the Castner graphitising process or by means of either continuous or batch powder graphitisation of the powder from step d); g) grinding of the body from step e).

13. The method for producing graphite materials according to claim 12, wherein at least one compound selected from the group including SiC, SiO2, Fe2O3, or TiO2 is selected as the catalyst in step a).

14. The method for producing graphite materials according to claim 12, wherein the calcinated and doped coke from step b) contains a maximum of 15 wt. % catalyst.

15. The method for producing graphite materials according to claim 12, wherein during the production of the green body in step e), the doped and calcinated coke has a grain size larger than 100 m.

16. The method for producing graphite materials according to claim 12, wherein in the event of shaped body graphitisation, the graphitisation in step f) is the Castner method and, in the event of powder graphitisation, it is continuous powder graphitisation.

17. The method for producing graphite materials according to claim 12, wherein the powder from step d) is additionally mixed with less than 50 wt. % natural graphite prior to shaping.

18. The method for producing graphite materials according to claim 12, wherein the binder used for producing the shaped green body in step e) is selected from the group comprising coal tar pitch, bitumen, phenolic resin, furan resin, or any desired mixtures thereof.

19. The method for producing graphite materials according to claim 12, wherein a catalyst is additionally mixed into the binder used in step d).

20. The method for producing graphite materials according to claim 19, wherein the additional catalyst is selected from at least one compound of oxides and carbides from the group including the elements iron, nickel, titanium, silicon, and boron and constitutes, based on the binder portion, a maximum of 15 wt. %.

21. The method for producing graphite materials according to claim 12, wherein following graphitisation, the graphite material has a specific discharge capacity of from 345 to 365 mAh/g.

22. Use of the graphite material produced according to claim 12 as anode material in lithium ion batteries.

23. The method for producing graphite materials according to claim 18, wherein the additional catalyst is selected from at least one compound of oxides and carbides from the group including the elements iron, nickel, titanium, silicon, and boron and constitutes, based on the binder portion, a maximum of 15 wt. %.

24. The method for producing graphite materials according to claim 13, wherein the calcinated and doped coke from step b) contains a maximum of 15 wt. % catalyst.

Description

EMBODIMENT 1

[0045] Coal tar pitch with a softening point of 60 C. is heated to 150 C., thus transforming into a liquid state. SiC powder having a d.sub.50 value of 50 m is added to this molten mass. Having been mixed with the catalyst, this dispersion is continuously added into the delayer coker from above.

[0046] In terms of procedure, it is simplest for the base substance (in this case the coal tar pitch) of the dispersion into which the catalyst has been mixed to be a portion of the flow of feedstock entering the delayed coker.

[0047] Following the delayed coking process, the material is broken up and calcinated at 1300 C.

[0048] Having been doped with SiC and calcinated, the coke was subjected to an ash analysis and measured an SiC content of approximately 5 wt. %.

[0049] The doped and calcinated coke, which had a maximum granulation of 3 mm, was mixed with 20 wt. % coal tar pitch (binder) having a softening point of 90 C. and shaped by means of extrusion (90 mm diameter).

[0050] The rod-shaped material was subsequently carbonised and graphitised in a Castner furnace at 2800 C. The graphite material was then further processed into an anode material powder having a d50 grain size of 20 m.

[0051] The d50 value indicates the median particle size, in which case 50% of the particles are smaller than the specified value. Diameters falling within this range are determined using laser light diffraction (ISO 13320-2009).

[0052] The powder was subjected to an ash analysis, and the Si content was determined to be less than 100 ppm.

[0053] X-ray analysis of the powder returned a do02 value of 0.3359 nm, and the apparent crystallite size had an Lc value of 170 nm. The degree of graphitisation is surprisingly high at 0.94.

[0054] The anode powder was subsequently tested in a battery cell test using a half-cell configuration, meaning that metallic lithium was used as the counter electrode. Following the formation cycle, the discharge capacity at a cycling rate of C/10 was determined to be 360 mAh/g. This represented a very good result and one close to the theoretical capacity of 372 mAh/g.

EMBODIMENT 2

[0055] Coal tar pitch with a softening point of 60 C. is heated to 150 C., thus transforming into a liquid state. SiC powder having a d50 value of 50 m is added to this molten mass. Having been mixed with the catalyst, this dispersion is continuously added into the delayer coker from above.

[0056] In terms of procedure, it is simplest for the base substance (in this case the coal tar pitch) of the dispersion into which the catalyst has been mixed to be a portion of the flow of feedstock entering the delayed coker.

[0057] Following the delayed coking process, the material was broken up and calcinated at 1300 C.

[0058] Having been doped with SiC and calcinated, the coke was subjected to an ash analysis and measured an SiC content of approximately 5 wt. %.

[0059] The doped and calcinated coke, which had a maximum granulation of 3 mm, was mixed with 20 wt. % coal tar pitch (binder) having a softening point of 90 C., with 5 wt. % catalyst (SiC) being mixed into the binder and shaped by means of extrusion (90 mm diameter).

[0060] The rod-shaped material was subsequently carbonised and graphitised in a Castner furnace at 2800 C. The graphite material was then further processed into anode material powder having a d50 grain size of 20 m. The d50 value indicates the median particle size, in which case 50% of the particles are smaller than the specified value.

[0061] Diameters falling within this range are determined using laser light diffraction (ISO 13320-2009).

[0062] The powder was subjected to an ash analysis, and the Si content was determined to be less than 100 ppm.

[0063] X-ray analysis of the powder returned a d.sub.002 value of 0.3357 nm, and the apparent crystallite size had an Lc value of 200 nm. The degree of graphitisation is surprisingly high at 0.95.

[0064] The anode powder was subsequently tested in a battery cell test using a half-cell configuration, meaning that metallic lithium was used as the counter electrode. Following the formation cycle, the discharge capacity at a cycling rate of C/10 was determined to be 362 mAh/g. This represented a very good result and one close to the theoretical capacity of 372 mAh/g.

COMPARATIVE EXAMPLE A (PRIOR ART)

[0065] In this example, graphite was produced in a way similar to embodiment 1. The difference consisted mainly of no catalyst (SiC) having been added while producing the coke.

[0066] X-ray analysis of the powder returned a d.sub.002 value of 0.3365 nm and an Lc value of 100 nm. The degree of graphitisation thus measured 0.87. The median discharge capacity in the lithium ion cell test, similarly to example 1, was 337 mAh/g.

COMPARATIVE EXAMPLE B (PRIOR ART)

[0067] Similarly to comparative example A, no catalyst was added in the coke production process for this comparative example. In the green recipe, however, only SiC powder was added to the binder pitch. Three mixtures were tested in this case, the ratios of which are summarised in table 1.

TABLE-US-00001 TABLE 1 Discharge capacity Mixtures in mAh/g 5 wt. % SiC/75 wt. % coke/20 wt. % pitch 345 10 wt. % SiC/70 wt. % coke/20 wt. % pitch 350 15 wt. % SiC/64 wt. % coke/21 wt. % pitch 360

[0068] All of these recipes were processed and analysed in a way similar to example 1. The discharge capacities indicated in table 1 were determined in the cell test.

[0069] As a comparison of the results from embodiment 1 and comparative example B shows, good discharge capacities are obtained in comparative example B only when the catalyst content is very high.

[0070] By adding the graphitisation catalyst both to the coke and to the binder pitch (see embodiment 2), a homogeneous distribution of catalyst is achieved throughout the entire material, as a result of which the discharge capacity is further increased.

[0071] Therefore, graphite production using the doped coke exhibits surprising advantages with respect to both performance and cost which are achieved by a more efficient introduction of the graphitisation catalyst material and a higher process speed for carbonisation and graphitisation.