Method of manufacturing secondary battery

Abstract

Disclosed is a method of manufacturing a secondary battery wherein an electrode assembly impregnated with an electrolytic solution is embedded in a battery case, wherein interfacial contact properties (i.e. wetting) of the electrode assembly and the electrolytic solution are improved through a process including: (a) impregnating an electrode assembly having a separator interposed between a cathode and an anode with an electrolytic solution; and (b) applying vibration having a frequency of 20 to 100 kHz to an electrolytic solution with which the electrode assembly is impregnated. A secondary battery manufactured according to the method may have improved ionic conductivity, electronic conductivity and the like and, as such, may have improved electrochemical performance.

Claims

1. A method of manufacturing a secondary battery where an electrode assembly impregnated with an electrolytic solution is embedded in a battery case, wherein interfacial contact properties (i.e. wetting) of the electrode assembly and the electrolytic solution are improved through a process comprising: forming an electrode assembly by interposing a separator between a cathode and an anode; impregnating the formed electrode assembly with an electrolytic solution; and after impregnating the formed electrode assembly with the electrolytic solution, applying vibration having a frequency of 20 to 100 kHz to the electrolytic solution with which the electrode assembly has been impregnated, wherein the vibration is a periodic physical movement applied by ultrasonic waves having the frequency of 20 to 100 kHz.

2. The method according to claim 1, wherein, in the applying, the vibration has an amplitude of 2 to 30 μm.

3. The method according to claim 1, wherein the vibration is applied once, or periodically or aperiodically twice or more.

4. The method according to claim 1, wherein the electrolytic solution comprises a lithium salt and a non-aqueous solvent.

5. The method according to claim 4, wherein the lithium salt is at least one selected from the group consisting of LiCl, LiBr, LiI, LiClO.sub.4, LiBF.sub.4, LiB.sub.10Cl.sub.10, LiPF.sub.6, LiCF.sub.3SO.sub.3, LiCF.sub.3CO.sub.2, LiAsF.sub.6, LiSbF.sub.6, LiAlCl.sub.4, CH.sub.3SO.sub.3Li, CF.sub.3SO.sub.3Li, (CF.sub.3SO.sub.2).sub.2NLi, chloroborane lithium, 4 phenylboronic acid lithium and imides.

6. The method according to claim 4, wherein the electrolytic solution comprises 1 to 80 wt % of a cyclic carbonate and 20 to 99 wt % of a linear carbonate based on a total weight of a non-aqueous solvent.

7. The method according to claim 6, wherein the cyclic carbonate is at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

8. The method according to claim 6, wherein the linear carbonate is at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), and methyl propionate (MP).

9. The method according to claim 1, wherein viscosity of the electrolytic solution is 0.1 cP or more and 5 cP or less.

10. The method according to claim 1, wherein viscosity of the electrolytic solution is 1 cP or more and 4 cP or less.

11. A secondary battery manufactured using the method according to claim 1.

12. The secondary battery according to claim 11, wherein impregnation amount of an electrolytic solution of an electrode assembly locating in the secondary battery is 120% to 140% of an impregnation amount of an electrode assembly to which vibration is not applied.

13. The secondary battery according to claim 11, wherein the secondary battery is a lithium secondary battery.

14. The method according to claim 1, further comprising embedding the electrode assembly in a battery case before the step of impregnating the electrode assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIG. 1 is a graph illustrating impregnation amounts according to time of an electrode assembly according to Experimental Example 1.

MODE FOR INVENTION

(3) Now, the present invention will be described in more detail with reference to the accompanying drawings. These examples are provided for illustrative purposes only and should not be construed as limiting the scope and spirit of the present invention.

Example 1

(4) A porous separator was interposed between a cathode including a cathode active material and an anode including an anode active material to manufacture an electrode assembly. The electrode assembly was embedded in a battery case and then a non-aqueous lithium electrolytic solution including ethylene carbonate and ethylmethyl carbonate mixed in a volumetric ratio of 3:7 was injected thereinto. Subsequently, vibration having a frequency of 40 kHz was applied thereto, resulting in completion of a secondary battery.

Comparative Example 1

(5) A secondary battery was manufactured in the same manner as in Example 1, except that vibration was not applied to an electrolytic solution.

Experimental Example 1

(6) In each of Example 1 and Comparative Example 1, the amount of an impregnated electrolytic solution according to time was measured after injecting an electrolytic solution. Results are illustrated in FIG. 1 below.

(7) In accordance with FIG. 1 below, it can be confirmed that the secondary battery, in which vibration was added to an electrolytic solution, manufactured according to Example 1 exhibits improved electrolytic solution impregnation amount and impregnation rate when compared to the secondary battery, in which vibration was not added to an electrolytic solution, manufactured according to Comparative Example 1.

INDUSTRIAL APPLICABILITY

(8) As described above, a method of manufacturing a secondary battery according to the present invention includes applying a predetermined frequency to an electrolytic solution with which an electrode assembly is impregnated. Accordingly, electrolytic solution impregnation properties, ionic conductivity, electronic conductivity and the like are improved and, as such, electrochemical performance of a secondary battery manufactured according to the method may be improved.