METHOD OF MANUFACTURING SECONDARY BATTERY ELECTRODE CONTAINING PTC MATERIAL AND ELECTRODE MANUFACTURED THEREBY

Abstract

Disclosed herein is a method of manufacturing a secondary battery electrode containing a positive temperature coefficient (PTC) material, the method including (a) applying first slurry including a first mixture and a solvent mixed with each other to one surface of a planar current collector to generate a PTC material after drying, (b) applying second slurry including a second mixture, including an electrode active material, and a solvent mixed with each other to the first slurry applied to the current collector, which is in a non-dried state, and (c) drying the first slurry and the second slurry applied to the current collector.

Claims

1. A method of manufacturing a secondary battery electrode containing a positive temperature coefficient (PTC) material, the method comprising: (a) applying first slurry comprising a first mixture and a solvent mixed with each other to one surface of a planar current collector to generate a PTC material after drying; (b) applying second slurry comprising a second mixture, comprising an electrode active material, and a solvent mixed with each other to the first slurry applied to the current collector, which is in a non-dried state; and (c) drying the first slurry and the second slurry applied to the current collector.

2. The method according to claim 1, wherein the first mixture comprises a polymer material, conductive particles, and a first binder.

3. The method according to claim 1, wherein the second mixture comprises an electrode active material, a conducting agent, and a second binder.

4. The method according to claim 2, wherein the first binder and the second binder have different compositions.

5. The method according to claim 2, wherein the first binder and the second binder have a same composition.

6. The method according to claim 2, wherein the polymer material has a content of 1 to 60 weight % based on a total weight of the first mixture.

7. The method according to claim 2, wherein the conductive particles have a content of 1 to 60 weight % based on a total weight of the first mixture.

8. The method according to claim 1, wherein the PTC material generated after drying the first slurry has an effective operating temperature of 80 to 140° C.

9. The method according to claim 2, wherein the binder has a content of 1 to 60 weight % based on a total weight of the first mixture.

10. The method according to claim 1, wherein, at step (a), the first slurry is applied using gravure coating or die coating.

11. The method according to claim 1, wherein, at step (b), the second slurry is applied using die coating.

12. The method according to claim 1, wherein, at step (a), the first slurry is applied to have a thickness of 0.1 to 20 μm.

13. The method according to claim 1, wherein, at step (b), the second slurry is applied to have a thickness of 5 to 300 μm within a range greater than a thickness of the first slurry.

14. The method according to claim 1, wherein, at step (b), the second slurry starts to be applied before completion of application of the first slurry over the one surface of the current collector.

15. The method according to claim 1, wherein, at step (b), the first slurry is applied to at least a portion of the current collector, and the second slurry starts to be applied within 0.01 seconds to 5 minutes thereafter.

16. A secondary battery electrode manufactured by the method according to claim 1.

17. The secondary battery electrode according to claim 16, wherein the secondary battery electrode comprises: a planar current collector; a first mixture layer and a second mixture layer formed on the current collector, the first mixture layer containing a PTC material, the second mixture layer containing an electrode active material; and a mixed layer located between the first mixture layer and the second mixture layer, the first mixture layer and the second mixture layer being mixed with each other in the mixed layer.

18. An electrode assembly comprising the secondary battery electrode according to claim 16.

19. A secondary battery having the electrode assembly according to claim 18 received in a battery case together with an electrolytic solution.

20. A battery pack comprising the secondary battery according to claim 19 as a unit cell.

21. A device comprising the battery pack according to claim 20 as a power source.

22. The device according to claim 21, wherein the device is selected from a group consisting of a mobile phone, a portable computer, a smartphone, a smart pad, a tablet PC, a netbook computer, a wearable electronic device, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a power storage apparatus.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0077] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0078] FIG. 1 is a schematic view showing a secondary battery electrode containing a positive temperature coefficient (PTC) material according to an embodiment of the present invention.

BEST MODE

[0079] Now, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted, however, that the scope of the present invention is not limited by the illustrated embodiments.

[0080] FIG. 1 is a schematic view showing a secondary battery electrode containing a positive temperature coefficient (PTC) material according to an embodiment of the present invention.

[0081] Referring to FIG. 1, an electrode 100 includes a current collector 110, a first mixture layer 120, and a second mixture layer 130.

[0082] Specifically, the first mixture layer 120, which contains a PTC material, is formed at the upper surface of the current collector 110, and the second mixture layer 130, which contains an electrode active material, is formed at the upper surface of the first mixture layer 120. The electrode active material, which is contained in the second mixture layer 130, may be a positive electrode active material or a negative electrode active material. The current collector 110 may be appropriately selected based on the electrode active material.

[0083] In FIG. 1, the interface between the first mixture layer 120 and the second mixture layer 130 is shown in the form of a plane. However, the figure shows the structure of the electrode 100 schematically. In actuality, second slurry is applied to first slurry, which is in a non-dried state. As a result, a region in which the first slurry and the second slurry are mixed with each other may be present at the interface between the first mixture layer and the second mixture layer. For this reason, the interface between the first mixture layer and the second mixture layer may not be clearly defined. In addition, since a region in which the first slurry and the second slurry are partially mixed with each other is present, the binding force between the first mixture layer 120 and the second mixture layer 130 after the slurries are dried is higher than in an electrode manufactured through a conventional electrode manufacturing method.

[0084] The thickness of the first mixture layer 120, which contains the PCT material and which is applied to the current collector 110, is less than that of the second mixture layer 130, which contains the electrode active material, in order to secure the capacity of a battery while securing the safety of the battery owing to the presence of the PCT material contained in the first mixture layer 120.

[0085] Meanwhile, electrons smoothly move between the electrode active material contained in the second mixture layer 130 and the current collector 110 at the general operating temperature of the battery. The reason for this is that the PTC material contained in the first mixture layer 120 has uniform conductivity at the operating temperature of the battery.

[0086] In the case in which the temperature of the battery is increased, however, the resistance of the PTC material contained in the first mixture layer 120 is abruptly increased. Consequently, the electrons cannot move between the second mixture layer 130 and the current collector 110 via the first mixture layer 120, whereby the flow of current is interrupted. As a result, it is possible to prevent the occurrence of a thermal runaway phenomenon in the battery.

[0087] In order to prevent the occurrence of such a thermal runaway phenomenon in the battery, the effective operating temperature of the PTC material contained in the first mixture layer 120 may range from 80° C. to 150° C.

[0088] Meanwhile, the electrode 100 shown in FIG. 1 is a single-sided electrode, in which the first mixture layer 120 and the second mixture layer 130 are formed only at the upper surface of the current collector 110. In the manufacturing method according to the present invention, however, a mixture layer containing a PTC material and a mixture layer containing an electrode active material may be sequentially formed at the lower surface of the current collector 110, in the same manner as at the upper surface of the current collector 110, in order to manufacture a double-sided electrode, the upper surface and the lower surface of which are symmetrical with respect to the current collector 110.

[0089] Although the exemplary 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.

INDUSTRIAL APPLICABILITY

[0090] As is apparent from the above description, a method of manufacturing a secondary battery electrode according to the present invention includes a step of applying second slurry to first slurry, which is in a non-dried state, whereby it is possible to reasonably reduce the cost of manufacturing an electrode containing a PTC material and to secure binding force between a PTC material layer and an electrode active material layer.