Secondary battery comprising injection-molded battery case

Abstract

A secondary battery configured to have a structure in which an electrode assembly is received in a battery case together with an electrolytic material, wherein the battery case is provided therein with a space for receiving the electrode assembly and wherein the battery case is made of a thermoplastic resin, which can be injection-molded. An injection mold may be formed such that the size of the mold corresponds to the thickness of the electrode, thereby solving a problem in which the formability of a conventional laminate sheet including a metal layer is low. In addition, a process of forming the laminate sheet and a process of sealing the battery case using a pressing member, which are essentially required in order to use the laminate sheet, may be omitted, whereby a manufacturing process is simplified and thus productivity is improved.

Claims

1. A secondary battery in which an electrode assembly is received in a battery case together with an electrolytic material, wherein an aluminum tape is attached to at least a portion of a surface of the electrode assembly, wherein the battery case is provided therein with a space for receiving the electrode assembly and the electrolytic material, wherein the electrode assembly and the electrolytic material are disposed within the battery case such that the electrolytic material contacts the battery case, wherein the battery case is made of a thermoplastic resin and does not include metal, wherein the thermoplastic resin comprises a hygroscopic additive, and wherein the battery case is injection molded such that the battery case has no seam on an outer surface thereof with the thermoplastic resin surrounding the entire outer surface of the electrode assembly and the electrode assembly completely enclosed by the battery case, such that only electrode terminals protruding from the electrode assembly extend outwards from the battery case.

2. The secondary battery according to claim 1, wherein the electrolytic material is liquid or solid.

3. The secondary battery according to claim 1, wherein the thermoplastic resin is at least one selected from a group consisting of polyvinyl alcohol, polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene copolymer (ABS), polyamide, polyvinyl chloride, acryl, fluorine resin, and polyethylene terephthalate.

4. The secondary battery according to claim 1, wherein the electrolytic material is solid.

5. The secondary battery according to claim 1, wherein the battery case is made of a material consisting essentially of the thermoplastic resin and the hygroscopic additive.

6. A secondary battery comprising: an electrode assembly; an aluminum tape is attached to at least a portion of a surface of the electrode assembly; an electrolytic material; and a battery case having an integrated structure made of injection molded thermoplastic resin such that the battery case has no seam on an outer surface thereof with the thermoplastic resin surrounding an entire outer surface of the electrode assembly and the electrode assembly completely enclosed by the battery case, such that only electrode terminals protruding from the electrode assembly extend outwards from the battery case, the battery case provided therein with a space for receiving the electrode assembly and the electrolytic material, wherein the thermoplastic resin comprises a hygroscopic additive.

7. A method of manufacturing a secondary battery, the method comprising: preparing a mold for manufacturing a battery case having therein a space for receiving an electrode assembly; attaching an aluminum tape to surround at least a portion of a surface of an electrode assembly; placing the electrode assembly in the mold; injecting a thermoplastic resin into the mold, in which the electrode assembly and an electrolytic material are placed, to form the battery case having the electrode assembly and the electrolytic material placed therein such that the electrolytic material contacts the battery case, such that the battery case has no seam on an outer surface thereof with the thermoplastic resin surrounding the entire outer surface of the electrode assembly and the electrode assembly completely enclosed by the battery case, such that only electrode terminals protruding from the electrode assembly extend outwards from the battery case, wherein the battery case does not include metal, and wherein the thermoplastic resin comprises a hygroscopic additive; and separating the battery case from the mold.

8. The method according to claim 7, wherein the electrode assembly is configured to have a structure in which the electrolytic material is a solid electrolyte interposed between a positive electrode and a negative electrode.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is an exploded perspective view showing a secondary battery according to an embodiment of the present invention.

(2) FIG. 2 is an exploded perspective view showing a battery case according to an embodiment of the present invention.

(3) FIG. 3 is a series of perspective views showing electrode assemblies according to a plurality of embodiments of the present invention.

(4) FIG. 4 is a perspective view showing a secondary battery according to another embodiment of the present invention.

(5) FIG. 5 is a perspective view showing a mold for manufacturing the secondary battery of FIG. 1.

(6) FIG. 6 is a perspective view showing a mold for manufacturing the secondary battery of FIG. 4.

BEST MODE

(7) Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention.

(8) Wherever possible, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. Meanwhile, in the case in which one part is connected to another part in the following description of the present invention, not only may the one part be directly connected to the another part, but also, the one part may be indirectly connected to the another part via a further part. In addition, that a certain element is included means that other elements are not excluded, but may be further included unless mentioned otherwise.

(9) Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

(10) FIG. 1 is an exploded perspective view showing a secondary battery according to an embodiment of the present invention.

(11) Referring to FIG. 1, the secondary battery, denoted by reference numeral 100, includes a battery case made of a thermoplastic resin, which can be injection-molded, the battery case including an upper case 110 and a lower case 120. The upper case 110 is provided with a reception unit 111 for receiving an electrode assembly 130, and the lower case 120 is provided with a reception unit 121 for receiving the electrode assembly 130. The electrode assembly 130 is disposed in the reception units 111 and 121 together with an electrolytic material. The sum of the height D2 of the reception unit 111 and the height D3 of the reception unit 121 is equal to or greater than the thickness D1 of the electrode assembly 130.

(12) In the state in which the electrode assembly 130 is received in the upper case 110 and the lower case 120, the outer edge 112 of the reception unit of the upper case 110 and the outer edge 122 of the reception unit of the lower case 120 are located so as to face each other. The outer edges 112 and 122 are sealed by thermal fusion, ultrasonic fusion, or laser fusion.

(13) FIG. 2 is an exploded perspective view showing a battery case according to an embodiment of the present invention.

(14) Referring to FIG. 2, the battery case, denoted by reference numeral 200, is a separable battery case including an upper case 210 and a lower case 220, as in the battery case shown in FIG. 1. The battery case 200 is made of a thermoplastic resin, which can be injection-molded. The thermoplastic resin includes a hygroscopic additive.

(15) FIG. 3 is a series of perspective views schematically showing three kinds of electrode assemblies.

(16) Referring to FIG. 3, each of the electrode assemblies, denoted by reference numerals 230, 240, and 250, may be a jelly-roll type (wound type) electrode assembly, which is configured to have a structure in which long sheet type positive electrodes and long sheet type negative electrodes are wound in the state in which separators are interposed respectively between the positive electrodes and the negative electrodes, a stacked type electrode assembly, which is configured to have a structure in which a plurality of positive electrodes cut so as to have a predetermined size and a plurality of negative electrodes cut so as to have a predetermined size are sequentially stacked in the state in which separators are interposed respectively between the positive electrodes and the negative electrodes, a stacked/folded type electrode assembly, which is configured to have a structure in which bi-cells or full cells, each of which is configured to have a structure in which predetermined numbers of positive electrodes and negative electrodes are stacked in the state in which separators are disposed respectively between the positive electrodes and the negative electrodes, are wound using a separation sheet, or a laminated/stacked type electrode assembly, which is configured to have a structure in which bi-cells or full cells are stacked and laminated in the state in which separators are disposed respectively between the bi-cells or the full cells.

(17) In addition, each of the electrode assemblies, denoted by reference numerals 230, 240, and 250, may be an electrode assembly that constitutes an all-solid-state battery. Each of the electrode assemblies may be configured to have a structure in which a solid electrolyte is interposed between a positive electrode and a negative electrode.

(18) The electrode assembly 230, 240, or 250 is shown as having a structure in which electrode terminals 231, 241, or 251 protrude in different directions. Alternatively, the electrode terminals may protrude in one direction.

(19) An aluminum tape may be attached to at least a portion of the outer surface of each of the electrode assemblies 230, 240, and 250 in order to prevent moisture from permeating into the electrode assembly. An aluminum tape 235 having a linear pattern is attached to the electrode assembly 230. An aluminum tape 245 is attached to the side surfaces of the electrode assembly 240 so as to surround the side surfaces of the electrode assembly, excluding the end surfaces of the electrode assembly from which the electrode terminals 241 protrude. An aluminum tape 255 is attached to the entire outer surface of the electrode assembly 250 including the end surfaces of the electrode assembly from which the electrode terminals protrude.

(20) FIG. 4 is a perspective view showing a secondary battery according to another embodiment of the present invention.

(21) Referring to FIG. 4, the secondary battery, denoted by reference numeral 300, is configured to have an integrated structure in which an electrode assembly 330 is received in a battery case 310, in which only electrode terminals 331 protrude outwards from the battery case, and in which the battery case 310 has no seam on the outer surface thereof.

(22) The electrode assembly 330 included in the secondary battery 300 is configured to have a structure in which a solid electrolyte is interposed between a positive electrode and a negative electrode. No liquid electrolytic solution is used. Consequently, the secondary battery is an all-solid-state battery, all components of which are solid.

(23) The secondary battery 300 is manufactured by injecting a thermoplastic resin into a mold for forming a battery case in the state in which the electrode assembly is placed in the mold.

(24) FIG. 5 is a perspective view showing a mold for manufacturing a separable secondary battery as shown in FIG. 1.

(25) Referring to FIG. 5, the mold, denoted by reference numeral 400, is provided with a concave unit 442 having a size and shape corresponding to the size and the shape of an upper case or a lower case. In addition, the mold is provided with a plurality of injection ports 441, through which a thermoplastic resin is injected.

(26) An electrode assembly is put in a battery case manufactured using the mold 400, the upper case and the lower case are coupled to each other, an electrolyte is injected into the battery case, and opposite surfaces of the upper case and the lower case are thermally fused to seal the battery case.

(27) FIG. 6 is a perspective view showing a mold for manufacturing an integrated secondary battery as shown in FIG. 4.

(28) Referring to FIG. 6, the mold, denoted by reference numeral 500, includes an upper mold 510 and a lower mold 520. A space for receiving an electrode assembly 530 is defined in each of the upper mold 510 and the lower mold 520. The upper and lower molds 510 and 520 are coupled to each other in the state in which the electrode assembly 530 is received in the spaces, and a thermoplastic resin is injected into the mold through thermoplastic resin injection ports 521.

(29) The thermoplastic resin forms an integrated battery case configured to surround the entire outer surface of the electrode assembly 530.

(30) The outer surface of the electrode assembly 530 may not be treated at all, or an aluminum tape may be attached to at least a portion of the outer surface of the electrode assembly. In addition, the thermoplastic resin may not include any additive, or may include a hygroscopic additive.

(31) Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible based on the above description, without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY

(32) As is apparent from the above description, a secondary battery according to the present invention includes a battery case made of a thermoplastic resin, which can be injection-molded, wherein the battery case is provided therein with a space for receiving an electrode assembly and an electrolytic material. Even in the case in which the thickness of the electrode assembly is increased, the size of a mold for injection molding may be adjusted in order to receive the thick electrode assembly, whereby it is possible to manufacture a secondary battery having a large capacity and high energy density.

(33) In addition, an additional process of forming the battery case or a thermal fusion process using a pressing member is not required, whereby a manufacturing process is simplified and thus productivity is improved.

(34) In addition, the thermoplastic resin, which constitutes the battery case, may include a hygroscopic additive, or an aluminum tape may be attached to the outer surface of the electrode assembly, whereby it is possible to prevent foreign matter from being introduced into the electrode assembly.