COATING MATERIAL OF KILN FOR PRODUCTION OF ACTIVE MATERIAL AND KILN COMPRISING SAME

Abstract

Disclosed is a coating material for coating a surface of a kiln for preparing an active material, the coating material being represented by the following Formula 1:

Ni.sub.aX.sub.z  (1) wherein an equation of a+z=1 is satisfied, with the proviso that 0.2≤a<1.0 and 0<z≤0.8 are satisfied, and X is at least one element selected from the group consisting of W, Cr, Co, Fe, Cu, Na, Al, Mg, Si, Zn, K, Ti, Mo, N, B, P, C, Ta, Nb, O, Mn, Sn, Ag and Zr, or an alloy or compound of two or more elements selected therefrom.

Claims

1. A coating material for coating a surface of a kiln for preparing an active material, the coating material being represented by the following Formula 1:
Ni.sub.aX.sub.z  (1) wherein an equation of a+z=1 is satisfied, with the proviso that 0.2≤a<1.0 and 0<z≤0.8 are satisfied; and X is at least one element selected from the group consisting of W, Cr, Co, Fe, Cu, Na, Al, Mg, Si, Zn, K, Ti, Mo, N, B, P, C, Ta, Nb, O, Mn, Sn, Ag and Zr, or an alloy or compound of two or more elements selected therefrom.

2. A coating material for coating a surface of a kiln for preparing an active material, the coating material being represented by the following Formula 2:
Ni.sub.aW.sub.bCr.sub.eCo.sub.dM.sub.e  (2) wherein an equation of a+b+c+d+e=1 is satisfied, with the proviso that 0.2≤a<1.0, 0≤b≤0.8, 0≤c≤0.7, 0≤d≤0.7, and 0≤e≤0.8 are satisfied; and M is at least one element selected from the group consisting of Fe, Cu, Na, Al, Mg, Si, Zn, K, W, Ti, Mo, N, B, P, C, Ta, Nb, O, Mn, Sn, Ag and Zr, or an alloy or compound of two or more elements selected therefrom.

3. The coating material according to claim 2, wherein a, b, c, d, and e satisfy 0.5≤a<1.0, 0≤b≤0.5, 0≤c≤0.2, 0≤d≤0.2, and 0≤e≤0.5, respectively.

4. The coating material according to claim 2, wherein a, b, c, d, and e satisfy 0.5≤a<1.0, 0≤b≤0.5, 0≤c≤0.15, 0≤d≤0.15, and 0≤e≤0.2, respectively.

5. The coating material according to claim 2, wherein a, b, c, d, and e satisfy 0.75≤a<0.95, 0.05≤b≤0.3, 0≤c≤0.1, 0≤d≤0.1, and 0≤e≤0.2, respectively.

6. The coating material according to claim 2, wherein the alloy or compound comprises at least one selected from the group consisting of TiC, SiC, VC, ZrC, NbC, TaC, B.sub.4C, Mo.sub.2C, TiN, BN, Si.sub.3N.sub.4, ZrN, VN, TaN, NbC, NbN, HfN and MoN.

7. A coating material for coating a surface of a kiln for preparing an active material, the coating material being an alloy based on Ni and WC, represented by the following Formula 3:
Ni.sub.aWC.sub.bCr.sub.eCo.sub.dM.sub.e  (3) wherein an equation of a+b+c+d+e=1 is satisfied, with the proviso that 0.2≤a<1.0, 0<b≤0.8, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.5 are satisfied; and M is at least one element selected from the group consisting of Fe, Cu, Na, Al, Mg, Si, Zn, K, W, Ti, Mo, N, B, P, Ta, Nb, 0, Mn, Sn, Ag and Zr, or an alloy or compound of two or more elements selected therefrom.

8. The coating material according to claim 7, wherein a, b, c, d, and e satisfy 0.2≤a<1.0, 0.05≤b≤0.8, 0≤c≤0.1, 0≤d≤0.1, and 0≤e≤0.2, respectively.

9. The coating material according to claim 7, wherein a, b, c, d, and e satisfy 0.5≤a<1.0, 0.05≤b≤0.5, 0≤c≤0.1, 0≤d≤0.1, and 0≤e≤0.2, respectively.

10. A coating material for coating a surface of a kiln for preparing an active material, wherein the coating material satisfies the following requirement (a), (b) or (c) at a temperature not less than 800° C. and less than 900° C. when ICP-MS analysis is performed on the active material heat-treated under the following conditions, (a) the content of Fe is less than 517 ppm; (b) the content of Cr is less than 8450 ppm, or (c) both of (a) and (b) are satisfied. [Conditions] Specimen type: SUS 310S Specimen size: 100 mm×100 mm×20 mm (width×length×height) Coating method: High-velocity oxy-fuel spraying method Coating material: Ni-containing material Active material firing: 10 g of a cathode active material is uniformly loaded on the surface of the specimen, the specimen is fed into a kiln, heated in an oxygen atmosphere at a rate of 5° C./min to a temperature of not less than 800° C. and less than 900° C., fired for 8 hours and then cooled slowly to room temperature.

11. A kiln in which a coating layer comprising the coating material according to claim 1 is formed in a portion of the kiln contacting an active material.

12. The kiln according to claim 11, wherein the coating layer is formed on an inner surface of a core tube.

13. The kiln according to claim 11, wherein the coating layer has a thickness of 0.1 mm to 2.0 mm.

14. The kiln according to claim 12, wherein the inner surface of the core tube comprises an Iconel or SUS-based material.

Description

BEST MODE

[0055] Now, the present invention will be described in more detail with reference to the following examples. These examples should not be construed as limiting the scope of the present invention.

Comparative Example 1

[0056] An SUS 310S specimen, one of the materials for a rotary kiln, was prepared in a size of 100 mm×100 mm×20 mm (width×length×height), 10 g of a cathode active material (Li.sub.1.03Ni.sub.0.70Co.sub.0.15Mn.sub.0.15O.sub.2) was uniformly loaded to the entire surface of the specimen, and the resulting specimen was fed into a kiln, heated to a temperature of 600° C. at a rate of 5° C./min in an oxygen atmosphere and was then fired for 8 hours.

[0057] When the firing was completed, the specimen was slowly cooled to room temperature, the active material was collected, and ICP-MS (inductively coupled plasma mass spectroscopy) analysis was performed.

[0058] 10 g of a fresh cathode active material (Li.sub.1.03Ni.sub.0.70Co.sub.0.15Mn.sub.0.15O.sub.2) was uniformly loaded on the surface of the specimen, fed into a kiln, heated to a temperature to 675° C. at a rate of 5° C./min in an oxygen atmosphere and then fired for 8 hours.

[0059] When the firing was completed, the specimen was cooled to room temperature and was taken out, the active material was collected, and ICP-MS analysis was performed.

[0060] This process was repeatedly performed at 600° C., 675° C., 700° C., 725° C., 775° C., 800° C., 825° C., and 900° C.

Comparative Example 2

[0061] Firing and analysis were performed under the same conditions as in Comparative Example 1, except that the type of specimen was changed to an Inconel specimen.

Example 1

[0062] An SUS 310S specimen, one of the materials for a rotary kiln, was prepared in a size of 100 mm×100 mm×20 mm (width×length×height), and the surface of the specimen was uniformly coated with a coating material containing 20 mol % of nickel (Ni) and 80 mol % of tungsten carbide (WC) using high-velocity oxy-fuel spraying. 10 g of a cathode active material (Li.sub.1.03Ni.sub.0.70Co.sub.0.15Mn.sub.0.15O.sub.2) was uniformly loaded to the entire surface of the coated specimen, and the resulting specimen was fed into a kiln, heated to a temperature of 600° C. at a rate of 5° C./min in an oxygen atmosphere and was then fired for 8 hours.

[0063] When the firing was completed, the specimen was slowly cooled to room temperature, the active material was collected, and ICP-MS (inductively coupled plasma mass spectroscopy) analysis was performed.

[0064] 10 g of a fresh cathode active material (Li.sub.1.03Ni.sub.0.70Co.sub.0.15Mn.sub.0.15O.sub.2) was uniformly loaded on the surface of the specimen, fed into a kiln, heated to a temperature to 675° C. at a rate of 5° C./min in an oxygen atmosphere and then fired for 8 hours.

[0065] When the firing was completed, the specimen was cooled to room temperature and was taken out, the active material was collected, and ICP-MS analysis was performed.

[0066] This process was repeatedly performed at 600° C., 675° C., 700° C., 725° C., 775° C., 800° C., 825° C., and 900° C.

Example 2

[0067] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 50 mol % of nickel (Ni) and 50 mol % of tungsten carbide (WC).

Example 3

[0068] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 60 mol % of nickel (Ni) and 40 mol % of tungsten carbide (WC).

Example 4

[0069] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 75 mol % of nickel (Ni) and 25 mol % of tungsten carbide (WC).

Example 5

[0070] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 80 mol % of nickel (Ni) and 20 mol % of tungsten carbide (WC).

Example 6

[0071] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 90 mol % of nickel (Ni) and 10 mol % of tungsten carbide (WC).

Example 7

[0072] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 93 mol % of nickel (Ni) and 7 mol % of chromium (Cr).

Example 8

[0073] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 50 mol % of nickel (Ni) and 50 mol % of cobalt (Co).

Example 9

[0074] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 50 mol % of nickel (Ni), 40 mol % of tungsten carbide (WC) and 10 mol % of chromium (Cr).

Example 10

[0075] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 50 mol % of nickel (Ni), 40 mol % of tungsten carbide (WC) and 10 mol % of cobalt (Co).

Example 11

[0076] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 90 mol % of nickel (Ni), 5 mol % of tungsten carbide (WC) and 5 mol % of chromium (Cr).

Example 12

[0077] Firing and analysis were performed under the same conditions as in Example 1, except that the coating material was changed to a material containing 90 mol % of nickel (Ni), 5 mol % of tungsten carbide (WC) and 5 mol % of cobalt (Co).

Experimental Example 1

[0078] The results of the ICP-MS analysis performed in Comparative Examples 1 and 2 and Examples 1 to 12 are shown in Tables 1 and 2 below. Table 1 shows the result of ICP-MS analysis for the Fe content and Table 2 shows the result of ICP-MS analysis for the Cr content.

TABLE-US-00001 TABLE 1 Coating Type of material Fe (ppm) Item sample (mol) 600° C. 675° C. 700° C. 725° C. 775° C. 800° C. 825° C. 900° C. Comparative SUS310S — 0 0 8 66 232 507 953 4051 Example 1 Comparative Inconel — 0 0 1 33 81 692 996 2281 Example 2 Example 1 SUS310S Ni0.20 0 0 0 14 68 153 430 1448 WC0.80 Example 2 SUS310S Ni0.50 0 0 0 3 5 116 227 346 WC0.50 Example 3 SUS310S Ni0.60 0 0 0 1 3 81 125 190 WC0.40 Example 4 SUS310S Ni0.75 0 0 0 1 3 48 71 133 WC0.25 Example 5 SUS310S Ni0.80 0 0 0 0 0 0 0 2 WC0.20 Example 6 SUS310S Ni0.90 0 0 0 0 0 0 5 8 WC0.10 Example 7 SUS310S Ni0.93 0 0 0 0 0 19 46 273 Cr0.07 Example 8 SUS310S Ni0.50 0 0 0 3 31 151 280 517 Co0.50 Example 9 SUS310S Ni0.50 0 0 0 8 27 132 246 438 WC0.40 Cr0.10 Example 10 SUS310S Ni0.50 0 0 0 12 53 144 265 461 WC0.40 Co0.10 Example 11 SUS310S Ni0.90 0 0 0 0 0 17 41 183 WC0.05 Cr0.05 Example 12 SUS310S Ni0.90 0 0 0 0 0 19 45 201 WC0.05 Co0.05

TABLE-US-00002 TABLE 2 Coating Type of material Cr (ppm) Item sample (mol) 600° C. 675° C. 700° C. 725° C. 775° C. 800° C. 825° C. 900° C. Comparative SUS310S — 813 952 1020 3314 5101 6923 8346 11760 Example 1 Comparative Inconel — 498 633 767 1549 3015 4522 7191 13260 Example 2 Example 1 SUS310S Ni0.20 387 511 545 1251 2904 4315 6248 8450 WC0.80 Example 2 SUS310S Ni0.50 246 402 529 578 1223 2206 3504 4317 WC0.50 Example 3 SUS310S Ni0.60 132 283 338 440 941 1687 2570 3961 WC0.40 Example 4 SUS310S Ni0.75 49 70 86 148 179 312 444 3698 WC0.25 Example 5 SUS310S Ni0.80 8 15 24 28 39 58 197 1435 WC0.20 Example 6 SUS310S Ni0.90 13 22 35 41 66 92 289 2023 WC0.10 Example 7 SUS310S Ni0.93 16 31 21 69 80 95 361 3369 Cr0.07 Example 8 SUS310S Ni0.50 362 530 728 955 1714 3484 4705 5528 Co0.50 Example 9 SUS310S Ni0.50 285 443 642 723 1488 3017 3871 4825 WC0.40 Cr0.10 Example 10 SUS310S Ni0.50 310 456 804 910 1621 3262 4186 5133 WC0.40 Co0.10 Example 11 SUS310S Ni0.90 14 25 38 48 69 93 303 3068 WC0.05 Cr0.05 Example 12 SUS310S Ni0.90 16 26 38 55 72 95 325 3122 WC0.05 Co0.05

[0079] As the Ni content of the cathode active material increases, the firing temperature decreases. Recently, the demand for a high-Ni cathode active material having a Ni content of 60% or more has increased. The firing temperature of the cathode active material having a high Ni content is less than 900° C., mainly at 850° C. or less. That is, when preparing a cathode active material with a high Ni content using a rotary kiln, the elution of impurities such as Fe and Cr should be suppressed at a temperature of less than 900° C. When preparing a cathode active material with a Ni content of less than 60%, impurity elution should be suppressed even at a temperature of 900° C. or higher.

[0080] As shown in Table 1 above, the Fe content of the SUS310S specimen having no coating layer was analyzed as 507 ppm at a firing temperature of 800° C., 953 ppm at a firing temperature of 825° C., and 4051 ppm at a firing temperature of 900° C., and as shown in Table 2, the Cr content of the SUS310S specimen was 6,923 ppm at 800° C., 8,346 ppm at 825° C., and 11,760 ppm at 900° C.

[0081] In addition, as shown in Table 1, the Fe content of the Inconel specimen having no coating layer was analyzed as 692 ppm at a firing temperature of 800° C., 996 ppm at a firing temperature of 825° C., and 2,281 ppm at a firing temperature of 900° C., and as shown in Table 2, the Cr content was analyzed at 4,522 ppm at a firing temperature of 800° C., 7,191 ppm at a firing temperature of 825° C., and 13,260 ppm at a firing temperature of 900° C.

[0082] These results indicate that, in the rotary kiln having no coating layer, great amounts of Fe and Cr are eluted and incorporated into the cathode active material. In particular, the results indicate that the increase in impurity elution is large within a temperature range of not less than 700° C. and less than 900° C., which is the firing temperature of the cathode active material with high Ni content, and the amount of impurity elution increases rapidly at 900° C. or higher, which is the firing temperature of the cathode active material with a low Ni content.

[0083] Meanwhile, the results of analysis of the samples 1 to 12 in which the coating layer according to the present invention is formed on the surface of the kiln showed that the total amount of elution of impurities is overall reduced compared to Comparative Examples 1 and 2 having no coating layer. In particular, it can be seen that, in Examples 2 to 7 and Examples 11 and 12, the amount of eluted impurities is greatly reduced to less than half at 800° C. or higher.

[0084] The impurity-inhibiting effect of Examples 3 to 7 to which the coating material containing nickel (Ni) and tungsten carbide (WC) is applied is particularly high, and in particular, the impurity elution-inhibiting effect thereof is excellent at 800° C. or higher when the Ni content is 80 mol % or more.

Experimental Example 2

[0085] As described above, Experimental Example 1 shows the results of ICP-MS analysis of specimens prepared in Comparative Examples and Examples. The analysis is measured based on a specimen with a size of 100 mm×100 mm×20 mm (width×length×height), and the result may be changed because the actual size of the kiln is much larger than this size.

[0086] Accordingly, the present inventors conducted simulations under the conditions shown in Table 3 using the following equation, and the results are shown in Tables 4 and 5 below.

[0087] The results of simulation are based on the prediction as to how the amount of detected impurities changes when the coating materials of Comparative Examples and Examples are applied to larger specimens and this enables prediction as to what effect the coating material according to the present invention will have when the area in contact with the active material and the amount of the active material are increased for application to the actual rotary kiln.

[00001]$\begin{array}{cc}Q\left(\mathrm{relative}\mathrm{amount}\mathrm{of}\mathrm{metal}\mathrm{impurity}\right)\propto \frac{\mathrm{Contact}\mathrm{Area}*\mathrm{Time}}{\mathrm{Sample}\mathrm{Mass}}=\frac{h*w*t}{a}& \left[\mathrm{Equation}\right]\end{array}$

h: transverse length of specimen (mm)
w: longitudinal length of specimen (mm)
t: firing time (hr)
a: amount of active material (g)

[0088] The relative amount of metal impurity based on the specimen of the example as described above was 8,000, which was set as a reference value of 1.

TABLE-US-00003 TABLE 3 Example Simulation h: Transverse length of specimen (mm), 100 500 w: Longitudinal length of specimen (mm), 100 1,000 Number of surfaces contacting active material 1 1 Contact area (mm.sup.2) 10,000 500,000 a: Amount of active material (g) 10 100,000 t: firing time (hr) 8 8 Q: Relative amount of metal impurity 8,000 40 Relative value 1.0 0.0050 Fold 1 200

[0089] As can be seen from Table 3, the result of simulation is a value predicted under the assumption that 100,000 g of the cathode active material was loaded on the surface of a core tube formed of SUS 310S having a size of 500 mm×1000 mm×20 mm (width×length×height) and fired for 8 hours, and the relative amount of metal impurity was obtained as 40. That is, a 200-fold difference occurs compared to the relative amount of the metal impurity of Examples.

[0090] Based on these results, when the amounts of detected impurities in Tables 1 and 2 analyzed in Comparative Examples and Examples are divided by the corresponding fold, the amounts of detected impurities when applied to the kiln having the above specifications can be predicted, and the results are shown in Tables 4 and 5 below.

TABLE-US-00004 TABLE 4 Coating Type of material Fe (ppm) Item sample (mol) 600° C. 675° C. 700° C. 725° C. 775° C. 800° C. 825° C. 900° C. Comparative SUSS10S — 0 0 0 0 1 3 5 20 Example 1 Comparative Inconel — 0 0 0 0 0 3 5 11 Example 2 Example 1 SUS310S Ni0.20 0 0 0 0 0 1 2 7 WC0.80 Example 2 SUS310S Ni0.50 0 0 0 0 0 1 1 2 WC0.50 Example 3 SUS310S Ni0.60 0 0 0 0 0 0 1 1 WC0.40 Example 4 SUS310S Ni0.75 0 0 0 0 0 0 0 1 WC0.25 Example 5 SUS310S Ni0.80 0 0 0 0 0 0 0 0 WC0.20 Example 6 SUS310S Ni0.90 0 0 0 0 0 0 0 0 WC0.10 Example 7 SUS310S Ni0.93 0 0 0 0 0 0 0 1 Cr0.07 Example 8 SUS310S Ni0.50 0 0 0 0 0 1 1 3 Co0.50 Example 9 SUS310S Ni0.50 0 0 0 0 0 1 1 2 WC0.40 Cr0.10 Example 10 SUS310S Ni0.50 0 0 0 0 0 1 1 2 WC0.40 Co0.10 Example 11 SUS310S Ni0.90 0 0 0 0 0 0 0 1 WC0.05 Cr0.05 Example 12 SUS310S Ni0.90 0 0 0 0 0 0 0 1 WC0.05 Co0.05

TABLE-US-00005 TABLE 5 Coating Type of material Cr (ppm) Item sample (mol) 600° C. 675° C. 700° C. 725° C. 775° C. 800° C. 825° C. 900° C. Comparative SUS310S — 4 5 5 17 26 35 42 59 Example 1 Comparative Inconel — 2 3 4 8 15 23 36 66 Example 2 Example 1 SUS310S Ni0.20 2 3 3 6 15 22 31 42 WC0.80 Example 2 SUS310S Ni0.50 1 2 3 3 6 11 18 22 WC0.50 Example 3 SUS310S Ni0.60 1 1 2 2 5 8 13 20 WC0.40 Example 4 SUS310S Ni0.75 0 0 0 1 1 2 2 18 WC0.25 Example 5 SUS310S Ni0.80 0 0 0 0 0 0 1 7 WC0.20 Example 6 SUS310S Ni0.90 0 0 0 0 0 0 1 10 WC0.10 Example 7 SUS310S Ni0.93 0 0 0 0 0 0 2 17 Cr0.07 Example 8 SUS310S Ni0.50 2 3 4 5 9 17 24 28 Co0.50 Example 9 SUS310S Ni0.50 1 2 3 4 7 15 19 24 WC0.40 Cr0.10 Example 10 SUS310S Ni0.50 2 2 4 5 8 16 21 26 WC0.40 Co0.10 Example 11 SUS310S Ni0.90 0 0 0 0 0 0 2 15 WC0.05 Cr0.05 Example 12 SUS310S Ni0.90 0 0 0 0 0 0 2 16 WC0.05 Co0.05

[0091] As can be seen from Tables 4 and 5, the results of simulation of Examples 1 to 12 are much better than those of Comparative Examples 1 and 2, and in particular, the results of simulation of Examples 2 to 7 and Examples 11 and 12 are excellent.

[0092] Although the rotation of the core tube is not considered in the above equation to predict the change in the amount of impurity detected during continuous contact between the active material and the inner surface of the core tube, various simulations are possible if the equation is appropriately changed by calculating the contact area according to the shape of the inner surface of the core tube.

[0093] Although preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the invention as disclosed in the accompanying claims.