ELECTRODE PLATE AND PREPARATION METHOD THEREFOR, AND BATTERY

Abstract

The present application provides an electrode plate and a preparation method therefor, and a battery. The preparation method comprises the following steps: (1) mixing and granulating an active substance, a conductive agent, a solvent and a binder to obtain mixed particles; and (2) performing lamination on the mixed particles in step (1) and a current collector in a laminator to obtain an electrode plate, wherein the laminator has three or more rollers.

Claims

1. A preparation method of an electrode sheet, comprising the following steps: (1) mixing and granulating an active material, a conductive agent, a solvent and a binder to obtain mixed particles; and (2) performing diaphragm forming on the mixed particles described in step (1) and a current collector in a laminating machine to obtain the electrode sheet, wherein the number of rolls of the laminating machine is 3 or more.

2. The preparation method according to claim 1, wherein a roll spacing of the laminating machine described in step (2) is 0.05-0.5 mm.

3. The preparation method according to claim 1, wherein a rotation speed of the rollers of the laminating machine described in step (2) is 1-10 r/min.

4. The preparation method according claim 1, wherein the electrode sheet is a positive electrode sheet or a negative electrode sheet.

5. The preparation method according to claim 1, wherein a mass ratio of the active material, the conductive agent, the solvent and the binder described in step (1) is (58-88):(1-6):(10-30):(1-6).

6. The preparation method according to claim 1, wherein the mixing and granulating of step (1) is performed with a granulator.

7. The preparation method according to claim 1, wherein the current collector described in step (2) comprises any one or a combination of at least two of steel mesh, aluminum mesh, copper mesh, nickel mesh, aluminum foil and copper foil combination.

8. The preparation method according to claim 1, wherein a temperature of the diaphragm forming described in step (2) is 15-35 C.

9. The preparation method according to claim 1, wherein step (2) further comprises baking the product obtained after the diaphragm forming.

10. The preparation method according to claim 1, wherein the method comprises the following steps: (1) mixing and granulating an active material, a conductive agent and a binder in a granulator for 1-10 min to obtain mixed particles; (2) performing diaphragm forming on the mixed particles described in step (1) and a current collector in a laminating machine, and after the diaphragm forming, an obtained product is baked at 100-300 C. for 5-28 h to obtain the electrode sheet, wherein the laminating machine is a three-roll laminating machine or a four-roll laminating machine; wherein the electrode sheet is a positive electrode sheet or a negative electrode sheet; the active material described in step (1) including any one or a combination of at least two of manganese dioxide, lithium manganate, lithium cobaltate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, graphite and silicon carbon materials; the conductive agent described in step (1) including any one or a combination of at least two of carbon black, graphite, graphene and carbon nanotubes; the binder described in step (1) including any one or a combination of at least two of styrene-butadiene rubber, polytetrafluoroethylene, polyvinyl fluoride, sodium carboxymethyl cellulose, polyvinylidene fluoride and lithium polyacrylate; the solvent described in step (1) is any one or a combination of at least two of water, ethanol, ethylene glycol, glycerol, isopropanol, n-butanol, 1-methyl pyrrolidone and N,N-dimethylformamide; a mass ratio of the active material, the conductive agent, the solvent and the binder described in step (1) is (58-88):(1-6):(10-30):(1-6); the current collector described in step (2) including any one or a combination of at least two of steel mesh, aluminum mesh, copper mesh, nickel mesh, aluminum foil and copper foil; and a roller spacing of the laminating machine described in step (2) is 0.05-0.25 mm; a rolling speed of the laminating machine described in step (2) is 1-10 r/min.

11. An electrode sheet prepared by the preparation method according to claim 1.

12. A battery comprising the electrode sheet of claim 11.

13. The preparation method according to claim 1, wherein the active material described in step (1) comprising any one or a combination of at least two of manganese dioxide, lithium manganate, lithium cobaltate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, graphite and silicon carbon material,

14. The preparation method according to claim 1, wherein the conductive agent described in step (1) comprising any one or a combination of at least two of carbon black, graphite, graphene and carbon nanotubes.

15. The preparation method according to claim 1, wherein the binder described in step (1) comprising any one or a combination of at least two of styrene-butadiene rubber, polytetrafluoroethylene, polyvinyl fluoride, sodium carboxymethyl cellulose, polyvinylidene fluoride and lithium polyacrylate.

16. The preparation method according to claim 1, wherein the solvent is any one or a combination of at least two of water, ethanol, ethylene glycol, glycerol, isopropanol, n-butanol, 1-methyl pyrrolidone and N,N-dimethylformamide.

17. The preparation method according to claim 6, wherein a rotating speed of the granulator is 50-1200 rpm; optionally, a mixing and granulating time of step (1) is 1-10 min.

18. The preparation method according to claim 1, wherein the laminating machine described in step (2) is a three-roll laminating machine or a four-roll laminating machine.

19. The preparation method according to claim 9, wherein a baking temperature is 100-300 C.; optionally, a baking time is 5-28 h.

20. The electrode sheet according to claim 11, wherein on the electrode sheet, the thickness of the diaphragm is 0.2-1.0 mm: the compacted density of the electrode sheet is 1.5-3.0 g/cm.sup.3.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0052] FIG. 1 is a schematic flow sheet of the preparation method of Example 1;

[0053] FIG. 2 is a schematic diagram of the laminating machine in the preparation method of Example 1, and the numbers 1, 2 and 3 marked in the diagram represent the numbers of the rollers;

[0054] FIG. 3 is a schematic diagram of the laminating machine in the preparation method of Example 2, and the numbers 1, 2, 3 and 4 marked in the diagram represent the numbers of the rollers;

[0055] FIG. 4 is the schematic diagram of the laminating machine in the preparation method of Comparative Example 1.

DETAILED DESCRIPTION

[0056] In order to better illustrate the present disclosure and facilitate the understanding of the technical solutions of the present disclosure, the present disclosure will be described in further detail below. The following embodiments are only simple examples of the present disclosure, and do not represent or limit the protection scope of the present disclosure. The protection scope of the present disclosure is subject to the claims.

[0057] The following are typical but non-limiting examples of the present disclosure:

Example 1

[0058] This embodiment was prepared according to the following method: [0059] (1) mixing 78 wt % LiFePO.sub.4 with 2 wt % conductive carbon fully, and then mixing with 3% polytetrafluoroethylene binder and 17 wt % ethanol/water (1/2) mixed solvent fully, the mixed particles were prepared by a high-speed granulator at a roller speed of 1000 rpm for 5 min. [0060] (2) the mixed particles mentioned described in step (1) were formed with a three-roll laminating machine (the distance between roll 1 and roll 2 is 0.1 mm, and the distance between roll 2 and roll 3 is 0.08 mm), at the temperature of 25 C. to form a diaphragm with a current collector aluminum foil at a roller speed of 3 r/min, and then placed in the oven at 120 C. to bake for 8 h, and cut to obtain a positive electrode sheet.

[0061] The schematic flow diagram of the preparation method of this embodiment is shown in FIG. 1.

[0062] The schematic diagram of the laminating machine in this embodiment is shown in FIG. 2, the roll 1 and the roll 2 of the laminating machine preformed the mixed particles, and the roll 2 and the roll 3 formed the preformed mixed particles with the current collector into the diaphragm.

[0063] The test results of the positive electrode sheet prepared in this example are shown in Table 1

Example 2

[0064] This embodiment is prepared according to the following method: [0065] (1) same as step (1) of Example 1 [0066] (2) the mixed particles mentioned described in step (1) were formed with a four-roll laminating machine (the distance between roll 1 and roll 2 is 0.1 mm, and the distance between roll 3 and roll 4 is 0.1 mm, and the distance between roll 2 and roll 3 is 0.1 mm), at the temperature of 25 C. to form a diaphragm with a current collector aluminum foil at a roller speed of 3 r/min, and then placed in the oven at 120 C. to bake for 8 h to obtain the positive electrode sheet.

[0067] The schematic diagram of the laminating machine in this embodiment is shown in FIG. 3. The roll 1 and the roll 2 of the laminating machine preformed the mixed particles, and the roll 3 and the roll 4 also preformed the mixed particles, the roll 2 and roll 3 formed the preformed mixed particles with the current collector into the diaphragm.

[0068] The test results of the positive electrode sheet prepared in this example are shown in Table 1.

Example 3

[0069] This embodiment is prepared according to the following method: [0070] (1) mixing 95 wt % lithium iron phosphate with 2.5 wt % conductive carbon fully, and then mixing with 2.5% polytetrafluoroethylene binder fully, the mixed particles were prepared by using a high-speed granulator to mix and granulate at a speed of 200 rpm for 1 min; [0071] (2) the mixed particles described in step (1) were used with the same four-roll laminating machine as in Example 2 to form a positive electrode sheet with a current collector aluminum foil at a temperature of 15 C. with a roller speed of 1 r/min, and then placed in the oven at 200 C. to bake for 28 h to obtain the positive electrode sheet.

[0072] The test results of the positive electrode sheet prepared in this example are shown in Table 1.

Example 4

[0073] This embodiment was prepared according to the following method: [0074] (1) mixing 85 wt % MnO.sub.2 with 7.5 wt % conductive carbon fully, and then mixing with 7.5% polytetrafluoroethylene binder fully, the mixed particles were prepared by using a high-speed granulator at a speed of 1200 rpm for 10 min; [0075] (2) The mixed particles described in step (1) were used with the same four-roll laminating machine as in Example 2 to form the negative electrode sheet with a current collector aluminum foil at a temperature of 35 C. with a roller speed of 10 r/min, and then placed in the oven at 240 C. to bake for 20 h to obtain the negative electrode sheet.

[0076] The test results of the negative electrode sheets prepared in this example are shown in Table 1.

Comparative Example 1

[0077] The preparation method of the electrode sheet of this comparative example was the same as that of Example 1 in other aspects, except that the three-roll laminating machine was not used described in step (2), but two-roll laminating machine (2 rolls) was used.

[0078] The schematic diagram of the laminating machine of this comparative example is shown in FIG. 4.

[0079] The test results of the positive electrode sheet prepared in this comparative example are shown in Table 1.

Comparative Example 2

[0080] The preparation method of the electrode sheet of this comparative example was the same as that of Example 4 in other aspects, except that described in step (2), a three-roll laminating machine was not used instead of a two-roll laminating machine (2 rolls) was used.

[0081] The test results of the positive electrode sheet prepared in this comparative example are shown in Table 1.

[0082] Testing Method

[0083] The electrode sheets provided in each example and comparative example were tested.

[0084] A micrometer was used to test the consistency of the thickness of the electrode sheet (characterized by the overall standard deviation of the thickness of three electrode sheets prepared in a certain Example or Comparative Example).

[0085] The electrolyte was used to test the liquid absorption under dry conditions (dew point45 C.). At 10 C. and normal temperature (25 C.) the 1 C capacity retention rate of the battery was tested with the Neware test cabinet using standard steps.

[0086] Test Standard Steps: [0087] Standard charging: when the battery was charged to 3.65 V with a constant current of 1 C (A), it was transferred to constant voltage charging, and the cut-off current was 0.05 C; [0088] Standard discharge: the battery was discharged to 2.50 V at a constant current of 1 C (A); [0089] Standard cycle: standard charge.fwdarw.standby for 0.5 h.fwdarw.standard discharge.fwdarw.standby for 0.5 h;

[0090] The electrolyte of Examples 1-3, Comparative Example 1 was composed of solvents (EC, PC, EMC, FB), additives (VC, MMDS), and lithium salt (LiPF.sub.6), and the electrolyte of Example 4 was: ethylene glycol dimethyl ether and propylene carbonate solution of lithium perchlorate; the negative electrode sheets of Examples 1-3 is graphite, and the negative electrode sheet of Example 4 is lithium metal.

[0091] The test results are shown in the following table:

TABLE-US-00001 TABLE 1 Electrode Overall standard Compared with sheets liquid deviation of normal temperature absorption/ electrode sheets capacity retention at 10 weight (%) thickness (mm) C., 1 C rate (%) Example 1 .sup.12% 0.005 88% Example 2 .sup.13% 0.003 90% Example 3 12.8% 0.004 89% Example 4 12.5% 0.005 88% Comparative .sup.10% 0.008 85% Example 1 Comparative 10.5% 0.007 82% Example 2

[0092] Combining the above examples and comparative examples, it can be seen that the preparation method of the example can obtain the electrode sheet with relatively good porosity under the condition of maintaining a relatively high compaction density (1.5-3.0 g/cm.sup.3) by using a suitable laminating machine cooperating with a granulation process. So that the battery has a better discharge capacity, especially under the conditions of large current and low temperature, and the thickness consistency of the electrode sheet is good.

[0093] In Comparative Example 1, because the diaphragm lamination equipment used was not suitable, particles were generated on both sides of the current collector, the uniformity was poor, and the pores formed after rolling were not uniform. Moreover, the diaphragm lamination equipment has a high requirement on the strength of the current collector.

[0094] The applicant declares that the above is only the specific implementation of the present disclosure, but the scope of protection of the present disclosure is not limited to this.