Electrode assembly, cylindrical lithium-sulfur battery cell including the same, battery pack including the cylindrical lithium-sulfur battery cell, and motor vehicle

Abstract

An electrode assembly, a cylindrical lithium-sulfur battery cell including the same, a battery pack including the cylindrical lithium-sulfur battery cell, and a vehicle are disclosed. An electrode assembly according to an embodiment of the present invention has a structure in which a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are wound in one direction, and is a jelly roll type electrode assembly having a central hole, and includes a center pin inserted into the central hole to pressurize the electrode assembly.

Description

Technical Field

[0001] The present invention relates to an electrode assembly, a cylindrical lithium-sulfur battery cell including the same, a battery pack including the cylindrical lithium-sulfur battery cell, and a vehicle. More specifically, the present invention relates to an electrode assembly that pressurizes a central portion of the electrode assembly, a cylindrical lithium-sulfur battery cell including the same, a battery pack including the cylindrical lithium-sulfur battery cell, and a vehicle.

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0177618 filed on December 16, 2022, and Korean Patent Application No. 10-2023-0038899 filed on March 24, 2023, and all of the contents disclosed in the specifications and drawings of the applications are incorporated into this application.

Background Art

[0003] As the application areas of secondary batteries expand to electric vehicles (EVs) and energy storage systems (ESSs), lithium-ion secondary batteries, which have a relatively low energy storage density (~250 Wh / kg) with respect to weight, have limitations in application to such products.

[0004] In contrast, lithium-sulfur secondary batteries have attracted attention as next-generation secondary battery technologies because they can theoretically achieve a high energy storage density (~2,600 Wh / kg) with respect to weight.

[0005] A lithium-sulfur secondary battery is a battery system that uses a sulfur-based material having a sulfur-sulfur bond as a positive electrode active material and lithium metal as a negative electrode active material. Such a lithium-sulfur secondary battery has the advantages that sulfur, which is the main material of the positive electrode active material, is abundant in resources worldwide, non-toxic, and has a low weight per atom.

[0006] In a lithium-sulfur secondary battery, during discharge, lithium, which is the negative electrode active material, is oxidized while giving off electrons and ionizing, and a sulfur-based material, which is the positive electrode active material, is reduced while accepting electrons. At this time, the oxidation reaction of lithium is a process in which lithium metal gives off electrons and is converted into the form of lithium cations.

[0007] Also, the reduction reaction of sulfur is a process in which an S-S bond accepts two electrons and is converted into the form of sulfur anions. The lithium cations generated by the oxidation reaction of lithium are transmitted to the positive electrode through the electrolyte and combine with the sulfur anions generated by the reduction reaction of sulfur to form a salt.

[0008] Specifically, sulfur before discharge has a cyclic S8 structure, which is converted into lithium polysulfide (lithium polysulfide, Li2S X , x = 8, 6, 4, 2) by a reduction reaction. When such lithium polysulfide is completely reduced, lithium sulfide (Li2S) is finally generated.

[0009] In order for a lithium-sulfur secondary battery to operate and exhibit appropriate electrochemical performance, an appropriate level of pressure needs to be applied to the electrode assembly during operation.

[0010] For example, in a lithium-sulfur secondary battery, when lithium metal is used as the negative electrode active material, if charging and discharging are repeated in this state, the thickness of the lithium metal itself will increase due to non-uniform plating and stripping of the lithium metal.

[0011] At this time, side reactions with the electrolyte may be induced due to reasons such as an increase in the specific surface area of the lithium metal, or the cell performance may deteriorate due to the generation of dead lithium, etc. Furthermore, an internal short circuit may occur due to the growth of lithium dendrites.

[0012] Thus, various problems that occur when using lithium metal as the negative electrode active material can be solved by applying pressure to the electrode assembly. Here, when a lithium-sulfur secondary battery is manufactured in a pouch type, the pressure applied from the outside can be transmitted to the electrode assembly.

[0013] However, when a lithium-sulfur secondary battery is designed in a jelly roll type cylindrical shape and a cylindrical metal can is used as the battery housing, pressure cannot be applied to the electrode assembly during the operation of the secondary battery, and various problems described above occur, making it difficult for the battery to operate normally.

Summary of the Invention

Problems to be Solved by the Invention

[0014] The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrode assembly in a jelly roll type, and particularly, an electrode assembly to which pressure is applied to a central hole.

[0015] Another object of the present invention is to provide a cylindrical lithium-sulfur battery cell including an electrode assembly having an improved structure, a battery pack including the cylindrical lithium-sulfur battery cell, and an automobile.

[0016] However, the technical problems to be solved by the present invention are not limited to the above problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description of the invention.

Means for Solving the Problems

[0017] According to one aspect of the present invention, there is provided an electrode assembly in a jelly roll type having a structure in which a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are wound in one direction and a central hole is formed, the electrode assembly including a center pin inserted into the central hole and pressing the electrode assembly.

[0018] In one embodiment of the present invention, the center pin may include a core portion that is inserted into the central hole, has an opening formed therein, and has at least a portion with a varying diameter, and an insertion portion that is inserted into the opening of the core portion to adjust the diameter of the core portion.

[0019] In one embodiment, the core portion may include a support portion located at an upper portion, where the opening is formed, a connection portion coupled to the support portion, and an expansion portion coupled to the connection portion, expanded on both sides by the insertion portion, and pressing the electrode assembly in the centrifugal direction.

[0020] In one embodiment, the expansion portion includes a plurality of unit units, a preset space is formed between the plurality of unit units, and the insertion portion inserted from the opening may be inserted through the space.

[0021] In one embodiment, the expansion portion includes a first unit unit and a second unit unit. The first unit unit and the second unit unit each have at least one convex portion and at least one concave portion, and the convex and concave portions of the first unit unit and the concave and convex portions of the second unit unit may be alternately positioned so as to correspond to each other.

[0022] In one embodiment, a part of the convex portion of the first unit unit may engage with a part of the concave portion of the second unit unit, and a part of the concave portion of the first unit unit may engage with a part of the convex portion of the second unit unit.

[0023] In one embodiment, the convex and concave portions of the first unit unit have a curvature within a preset range, and the convex and concave portions of the second unit unit may also have a curvature within a preset range.

[0024] In one embodiment, the convex and concave portions of the first unit unit have a round shape, and the convex and concave portions of the second unit unit may also have a round shape.

[0025] In one embodiment, before the insertion part is inserted, the expansion part may be formed such that its diameter gradually decreases from top to bottom.

[0026] In one embodiment, the diameter of the connection part may be configured to be smaller than the diameter of the support part and smaller than the diameter of the expansion part.

[0027] In one embodiment, the connection part is coupled to the central part of the support part, and the support part may have a wider vertical width at the central part to which the connection part is coupled, and the vertical width may become narrower from the center to both ends.

[0028] In one embodiment, the insertion part may include a head and a rod part extending from the head.

[0029] In addition, according to another aspect of the present invention, there may be provided a cylindrical lithium-sulfur battery cell including the above-described electrode assembly, a cylindrical battery can in which the electrode assembly is housed, a positive electrode current collector electrically connected to the positive electrode plate, a cell terminal connected to the positive electrode current collector through a through hole of the battery can, and a negative electrode current collector electrically connected to the negative electrode plate.

[0030] On the other hand, according to still another aspect of the present invention, there is provided a battery pack including the above-described cylindrical lithium-sulfur battery cell, and further, an automobile including the cylindrical lithium-sulfur battery cell may be provided.

Advantages of the Invention

[0031] The center pin according to the present invention, when inserted into the center hole of a jelly roll type electrode assembly to press the electrode assembly and thus applied to a cylindrical lithium-sulfur battery cell, has the effect of maximizing the manifestation of electrochemical performance.

[0032] In addition, side reactions of the electrolytic solution can be reduced, deterioration of cell performance caused by dead lithium or the like can be prevented, and internal short circuits can also be prevented.

[0033] In addition, the present invention has various other effects, which will be described in each implementation configuration. For effects that can be easily inferred by those skilled in the art, such as those, the description will be omitted.

[0034] The following drawings attached to this specification illustrate desirable embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

[0035]

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Figure 12

Mode for Carrying Out the Invention

[0036] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor himself must interpret them in accordance with the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that he can appropriately define the concept of the terms in order to explain the invention in the best way.

[0037] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, so there can be various equivalents and modifications that can replace them at the time of this application.

[0038] In addition, for the purpose of assisting the understanding of the invention, the attached drawings may show some components exaggeratedly rather than at actual scale. Note that the same reference numerals may be assigned to the same components in different embodiments.

[0039] The terms used in this specification are merely used to explain exemplary embodiments and do not limit the present invention. Singular expressions include plural expressions unless otherwise specified in the context.

[0040] In addition, in this specification, terms indicating directions such as up, down, left, right, front, and back are used. However, such terms indicate relative positions and are for convenience of explanation only. It is obvious to those skilled in the art that these terms can change depending on the position of the object and the position of the observer, etc.

[0041] Throughout the specification, when a certain part "includes" and "has" a certain component, unless otherwise specified, this does not mean excluding other components, but rather means that other components can be further included.

[0042] FIG. 1 is a schematic cross-sectional view of a cylindrical lithium-sulfur battery cell according to an embodiment of the present invention, in which the center pin is separated from the electrode assembly. FIG. 2 is a cross-sectional view of the core of the center pin inserted into the center hole of the electrode assembly according to an embodiment of the present invention. FIG. 3 is a plan view of the core of the center pin inserted into the center hole of the electrode assembly according to an embodiment of the present invention. FIG. 4 is a perspective view of the insertion portion of the center pin inserted into the center hole of the electrode assembly according to an embodiment of the present invention. FIG. 5 is a cross-sectional view showing the state where the insertion portion is inserted into the core in the center pin inserted into the center hole of the electrode assembly according to an embodiment of the present invention. FIG. 6 is a plan view showing the state where the insertion portion is inserted into the core in the center pin inserted into the center hole of the electrode assembly according to an embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing the state where the core of the center pin is coupled to the electrode assembly in a cylindrical lithium-sulfur battery cell according to an embodiment of the present invention. FIG. 8 is a cross-sectional view schematically showing the state where the insertion portion is inserted into the core in the state of FIG. 7, showing the state where the core presses the electrode assembly by the insertion portion. FIG. 9 is another embodiment of FIG. 2, and FIG. 10 is another embodiment of FIG. 5.

[0043] Referring to FIG. 1, the electrode assembly 10 is formed in a jelly roll type in which a separator 120 is interposed between a current collector and a long sheet-like positive electrode plate 110 and a negative electrode plate 130 having an electrode active material coated on the surface of the current collector and wound up.

[0044] That is, the electrode assembly 10 includes a positive electrode plate 110, a negative electrode plate 130, and a separator 120. The separator 120 is interposed between the positive electrode plate 110 and the negative electrode plate 130 and is wound in one direction.

[0045] Here, when the electrode assembly 10 is wound, a winding core is disposed at one end of the electrode assembly 10. After the electrode assembly 10 is wound around the winding core, when the winding core is removed, a central hole 140 is formed in the central portion from which the winding core has been removed. Then, by inserting the center pin 20 into the central hole 140, the electrode assembly 10 is pressurized. A detailed description of the center pin 20 will be given later.

[0046] The positive electrode plate 110 has a positive electrode active material layer containing a positive electrode active material formed on at least one surface of the positive electrode current collector 40. A positive electrode tab may be attached to the positive electrode plate 110, and the positive electrode tab can be attached to a non-coated portion of the positive electrode current collector 40 where no positive electrode active material is applied by a method such as ultrasonic welding.

[0047] However, in the present invention, a non-coated portion does not necessarily have to be formed, and the present invention is not limited by the method of attaching the positive electrode tab as described above, and various known tab attachment techniques at the time of filing the present invention can be adopted in the present invention.

[0048] On the other hand, for the positive electrode current collector 40, a metal thin plate with excellent conductivity, for example, an aluminum foil, may be used, and the positive electrode tab may be made of, for example, aluminum Al.

[0049] The negative electrode plate 130 is formed by applying a negative electrode active material to at least one surface of the negative electrode current collector 60, and a negative electrode tab is attached to the negative electrode plate 130. Such a negative electrode tab may also be attached to a non-coated portion of the negative electrode current collector 60 where no negative electrode active material is applied, and various attachment methods such as ultrasonic welding are applicable.

[0050] And, similar to the description of the positive electrode plate 110, the negative electrode plate 130 does not necessarily have to have a non-coated portion, is not limited by the negative tab attachment method as described above, and various known tab attachment techniques at the time of filing of the present invention can be adopted in the present invention.

[0051] And, as the negative current collector 60, a conductive metal thin plate, for example, a copper or nickel foil can be used, and the negative tab can be made of, for example, nickel.

[0052] The separator 120 is disposed between the positive electrode plate 110 and the negative electrode plate 130, insulates between the positive electrode plate 110 and the negative electrode plate 130, and allows active material ions to be exchanged between the positive electrode plate 110 and the negative electrode plate 130. The separator 120 can be used without particular limitation as long as it is usually used as the separator 120 in a lithium secondary battery.

[0053] Specifically, the separator 120 can be a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof.

[0054] And, a normal porous non-woven fabric, for example, a non-woven fabric made of high melting point glass fibers, polyethylene terephthalate fibers, etc. can be used. Further, in order to ensure heat resistance or mechanical strength, a separator 120 coated with a coating layer containing a heat-resistant polymer substance such as a ceramic component or an engineering plastic can be used.

[0055] In the cylindrical lithium-sulfur battery cell 1 according to an embodiment of the present invention, the sulfur-based substance is inorganic sulfur (S8), Li2S n(n ≧ 1), 2,5-dimercapto-1,3,4-thiadiazole, disulfide compounds such as 1,3,5-trithiocyanuric acid, organic sulfur compounds, and carbon-sulfur polymers ((C2S x ) n , x = 2.5 to 50, n ≧ 2), and may be one or more selected from the group consisting of. Desirably, it may contain inorganic sulfur (S8).

[0056] In one embodiment of the present invention, the sulfur-based substance may be included in the positive electrode active material in the form of a sulfur-carbon composite complexed with a carbon material. The positive electrode active material may contain 80 wt% or more of the sulfur-carbon composite based on 100 wt% of the positive electrode active material. Here, it is desirable that the content of the sulfur-based substance is 70 wt% or more based on 100 wt% of the sulfur-carbon composite.

[0057] In one embodiment of the present invention, the sulfur-carbon composite may have a form in which sulfur and a carbon material are simply mixed and complexed, or a coating form or a supported form of a core-shell structure. The coating form of the core-shell structure is one in which either sulfur or a carbon material coats the other substance, and in one embodiment, the surface of the carbon material may be surrounded by sulfur or vice versa. And the carbon material has a porous structure having pores inside and on the surface of the main body, and in particular, may be in a form in which sulfur is filled in the internal pores.

[0058] The carbon material has a porous structure including a plurality of non-uniform pores on the surface and inside, and serves as a carrier that provides a skeleton for uniformly and stably immobilizing sulfur, compensates for the low electrical conductivity of sulfur, and smooths the electrochemical reaction.

[0059] In the sulfur-carbon composite according to one embodiment of the present invention, the carbon material may be any of those commonly used in the art as a porous and conductive carbon-based substance.

[0060] For example, it may include one or more selected from the group consisting of graphite; graphene; carbon black such as Denka black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black; carbon nanotubes (CNT) such as single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT); carbon fibers such as graphite nanofibers (GNF), carbon nanofibers (CNF), activated carbon fibers (ACF); graphite such as natural graphite, artificial graphite, expanded graphite; carbon nanoribbons; carbon nanobelts, carbon nanorods and activated carbon.

[0061] Also, in one embodiment of the present invention, the sulfur-carbon composite can be produced by a composite method comprising the steps of: (S1) mixing a carbon material and sulfur to form a mixture, and then (S2) composite the mixture.

[0062] The mixing in step (S1) is for increasing the mixing degree of sulfur and the carbon material, and can be carried out using a stirring device commonly used in the art. At this time, the mixing time and speed can also be selectively adjusted according to the content and conditions of the raw materials.

[0063] And the composite method in step (S2) is not particularly limited in the present invention, and a method commonly used in the art can be used. In one embodiment, a method commonly used in the art such as dry composite or wet composite such as spray coating can be used. In one embodiment, a method can be used in which the mixture of sulfur and carbon material obtained after mixing is heat-treated so that the molten sulfur is uniformly coated on the inner and outer surfaces of the carbon material.

[0064] On the other hand, in one embodiment of the present invention, a step of pulverizing the mixture of sulfur and carbon material by a method such as a ball mill can be performed before heat treatment. In one embodiment of the present invention, the heat treatment may be carried out at a temperature condition of 120°C to 160°C for about 20 minutes to 24 hours, and a heating device such as an oven can be applied.

[0065] The sulfur-carbon composite manufactured by the above-described manufacturing method has a structure with a high specific surface area, a high sulfur loading amount, and an improved sulfur utilization rate. Therefore, not only is the electrochemical reactivity of sulfur improved, but also the capacity and life characteristics of the lithium-sulfur battery can be improved by enhancing the accessibility and contactability of the electrolyte.

[0066] In addition to the content described in this specification regarding the configuration, materials, manufacturing methods, etc. of the above-described positive electrode plate 110, negative electrode plate 130, and separator 120, content widely known to an ordinary technician in the art of the present invention can be adopted in the present invention, and detailed descriptions thereof are omitted in this specification.

[0067] Referring to both FIGS. 1 and 8, the center pin 20 is inserted into the central hole 140 of the jelly roll type electrode assembly 10 as described above to press the electrode assembly 10. The center pin 20 according to an embodiment of the present invention can structurally support the electrode assembly 10 and apply a pressure within a preset range from the winding center to the outer direction.

[0068] The center pin 20 may include a core portion 210 and an insertion portion 270. The center pin 20 may have a long rod-like appearance, but is not limited thereto.

[0069] Referring to FIGS. 1 to 3 together, the core portion 210 is inserted into the central hole 140 formed in the electrode assembly 10. An opening 221 is formed in the core portion 210. And at least a part (for example, the lower part of the core portion 210) of the core portion 210 is formed such that the diameter changes.

[0070] The center pin 20 is inserted into the central hole 140 of the electrode assembly 10 and applies pressure in the outer direction of the electrode assembly 10, whereby the center pin 20 is closely adhered and fixed to the electrode assembly 10. Further, the electrode assembly 10 housed in the battery can 30 can be closely adhered and fixed to the battery can 30 by the pressure applied by the center pin 20.

[0071] Then, the insertion part 270 is inserted into the opening 221 of the core part 210 and is configured to adjust the diameter of the core part 210.

[0072] The insertion part 270 can be configured in various ways. For example, referring to FIG. 4, the insertion part 270 can include a head 271 and a rod part 272. The head 271 can be formed, for example, in a disc shape. And the rod part 272 extends from the head 271. The insertion part 270 can be formed, for example, in the shape of a nail or a pushpin.

[0073] Referring to both FIGS. 5 and 8, when the insertion part 270 presses the core part 210 while being inserted into the core part 210, the core part 210 expands to both sides, thereby pressing the electrode assembly 10. Here, the core part 210 is made of, for example, a polymer material having flexibility or elasticity, and the deformation of the form can be easily configured by the insertion and separation of the insertion part 270.

[0074] Also, the inner surface of the core part 210 and the outer surface of the insertion part 270 can be subjected to a low-friction coating treatment such as Teflon (registered trademark) coating to minimize the frictional force so that the insertion part 270 can be easily inserted into the inside of the core part 210.

[0075] On the other hand, when manufacturing the cylindrical lithium-sulfur battery cell 1, before inserting the insertion part 270 into the core part 210, the jelly roll electrode assembly 10 in the state where the core part 210 is inserted is first housed in the battery can 30. When the insertion part 270 is inserted into the core part 210, the expansion part 240 of the center pin 20 expands, and it may become difficult to insert the electrode assembly 10 into the inside of the exterior material.

[0076] Therefore, before the insertion part 270 is inserted into the core part 210, it is desirable to insert the electrode assembly 10 into the battery can 30. However, it is not necessarily limited to this.

[0077] After the electrode assembly 10 with the core part 210 inserted therein is housed in the battery can 30, the insertion part 270 is inserted so as to penetrate the support part 220 of the core part 210, and the core part 210 and the insertion part 270 are joined together.

[0078] The core part 210 can be formed in various shapes, but can be formed in a shape corresponding to the shape of the central hole 140 so as to be inserted from the central hole 140 of the electrode assembly 10.

[0079] The core part 210 may include a support part 220, a connection part 230, and an extension part 240.

[0080] The support part 220 is located at the upper part, and an opening 221 into which the insertion part 270 is inserted is formed. Referring to FIG. 3, the opening 221 can be formed, for example, at the center of the support part 220. And referring to FIG. 7, the diameter of the support part 220 is formed larger than the diameter of the central hole 140 of the electrode assembly 10, whereby the support part 220 is not inserted into the central hole 140 and can be located at the upper part of the electrode assembly 10.

[0081] One side of the connection part 230 is joined to the support part 220, and the other side is joined to the extension part 240 to connect the support part 220 and the extension part 240. The extension part 240 is joined to the connection part 230 and presses the electrode assembly 10 in the centrifugal direction while being expanded to both sides by the insertion part 270 (see FIGS. 5 and 8).

[0082] The extension part 240 may include a plurality of unit units. For example, the extension part 240 may include a first unit unit 241 and a second unit unit 244, but is not limited thereto. However, hereinafter, the case where the extension part 240 includes the first unit unit 241 and the second unit unit 244 will be described for convenience of explanation.

[0083] Referring to both FIGS. 2 and 5, a preset space 247 is formed between the plurality of unit units, that is, the first unit unit 241 and the second unit unit 244. And the insertion part 270 inserted from the opening 221 is inserted through the space 247.

[0084] Referring to FIG. 2 here, the first unit 241 and the second unit 244 can each be configured to have at least one convex portion 242, 245 and at least one concave portion 243, 246.

[0085] And the convex portion 242 and the concave portion 243 of the first unit 241 and the concave portion 246 and the convex portion 245 of the second unit 244 can be alternately positioned so as to correspond to each other. That is, the convex portion 242 of the first unit 241 can be formed at the same position as the concave portion 246 of the second unit 244, and the concave portion 243 of the first unit 241 can be formed at the same position as the convex portion 245 of the second unit 244.

[0086] Here, the convex portion 242 and the concave portion 243 of the first unit 241 and the concave portion 246 and the convex portion 245 of the second unit 244 can be configured to be in contact with or separated from each other.

[0087] For example, in FIG. 2, in the upper part, the convex portion 242 and the concave portion 243 of the first unit 241 and the concave portion 246 and the convex portion 245 of the second unit 244 do not contact each other, but in the lower part, the convex portion 242 and the concave portion 243 of the first unit 241 and the concave portion 246 and the convex portion 245 of the second unit 244 contact each other respectively. However, such a configuration is only one embodiment and can be variously deformed.

[0088] And when the convex portion 242 and the concave portion 243 of the first unit 241 and the concave portion 246 and the convex portion 245 of the second unit 244 contact each other, a part of the convex portion 242 of the first unit 241 can be engaged with a part of the concave portion 246 of the second unit 244, and a part of the concave portion 243 of the first unit 241 can be engaged with a part of the convex portion 245 of the second unit 244.

[0089] Referring to FIG. 2, the convex portion 242 and the concave portion 243 of the first unit 241 can have a curvature within a preset range. For example, the convex portion 242 and the concave portion 243 of the first unit 241 can have a round shape.

[0090] And the convex portions 245 and concave portions 246 of the second unit unit 244 may also have a curvature within a preset range. For example, the convex portions 245 and concave portions 246 of the second unit unit 244 may have a round shape.

[0091] Thus, when curvatures are formed on the convex portions 242, 245 and concave portions 243, 246, it has the effect of reducing interference or friction during the insertion of the insertion portion 270 and facilitating the insertion of the insertion portion 270.

[0092] In another embodiment, referring to FIG. 9, curvatures are formed on the convex portion 242 and concave portion 243 of the first unit unit 241 and the concave portion 246 and convex portion 245 of the second unit unit 244, but the degree of curvature is different from that in FIG. 2.

[0093] As described above, the expansion portion 240 expands to both sides by the insertion portion 270. Referring to FIG. 2, before the insertion portion 270 is inserted, that is, before the expansion portion 240 is expanded, the expansion portion 240 may be formed in a shape where the diameter gradually decreases from the upper part to the lower part. That is, the expansion portion 240 may be formed in a shape that is wider at the top and narrower at the bottom.

[0094] Thus, when the expansion portion 240 is formed in a shape that is wider at the top and narrower at the bottom, when the core portion 210 is inserted into the central hole 140 of the electrode assembly 10 as shown in FIG. 7, a gap S is formed between the core portion 210 and the electrode assembly 10, so that interference between the core portion 210 and the electrode assembly 10 is prevented, and the insertion of the core portion 210 becomes easier.

[0095] Referring to both FIGS. 2 and 5, the diameter of the connection portion 230 may be configured to be smaller than the diameter of the support portion 220 and also smaller than the diameter of the expansion portion 240. And the connection portion 230 is coupled to the central portion of the support portion 220, and the support portion 220 may be configured such that the vertical width of the central portion to which the connection portion 230 is coupled is wide, and the vertical width becomes thinner from the center to both ends.

[0096] Accordingly, when the extension part 240 is expanded to both sides by the insertion part 270, the support part 220 and the extension part 240 do not interfere with each other.

[0097] Referring to FIGS. 2 and 5, the connection part 230 has an outer diameter smaller than those of the support part 220 and the extension part 240. And the outer diameter of the uppermost end of the extension part 240 may be the same as or smaller than the outer diameter of the support part 220. The insertion part 270 is inserted inside the support part 220 and the connection part 230. An opening is formed in the support part 220 in the vertical direction and extends downward to be connected to a space.

[0098] When the extension part 240 is expanded by the insertion of the insertion part, the connection part 230 separates the support part 220 and the extension part 240 so that the lower end of the support part 220 and the upper part of the extension part 240 do not interfere with each other. Referring to FIG. 2, the support part 220 and the extension part 240 are separated by the width of the connection part 230, and the distance between the support part 220 and the extension part 240 increases as it advances in the outer direction from the center of the connection part 230 (W2>W1).

[0099] In one embodiment, the support part 220 may have a form in which the width is large at the central part where the connection part 230 is formed, and gradually decreases from the center to the outer periphery. That is, based on FIG. 5, the lower part of the support part 220 may be formed to incline upward as it advances from the central part to the end part.

[0100] And by being formed in this way, even when the insertion part 270 is inserted inside the core part 210 and the outer diameter of the extension part 240 is expanded as shown in FIG. 5, the support part 220 and the extension part 240 are separated by W3, so interference between the support part 220 and the extension part 240 is prevented.

[0101] Hereinafter, the electrode assembly 10 including the center pin 20 according to the present invention and the manufacturing method of the cylindrical lithium-sulfur battery cell 1 including the electrode assembly 10 will be described in detail.

[0102] In one embodiment of the present invention, first, a separator 120 is interposed between the positive electrode plate 110 and the negative electrode plate 130, and the winding core is wound around a preset number of times around the winding core. However, the method of forming the electrode assembly 10 in a jelly roll shape is diverse and is not limited to the above-described embodiment.

[0103] Thereafter, the winding core is removed from the center of the wound jelly roll-type electrode assembly 10. Thereafter, the core part 210 is inserted into the central hole 140 formed in the center of the jelly roll-shaped electrode assembly 10.

[0104] Here, the core part 210 can be formed such that the outer diameter of one end portion gradually decreases along the longitudinal direction. And the core part 210 can be inserted from the entrance of the central hole 140 of the electrode assembly 10 to the opposite end portion.

[0105] Then, the jelly roll-shaped electrode assembly 10 into which the core part 210 is inserted is inserted into the inside of the cylindrical battery can 30. Here, before inserting the insertion part 270 into the core part 210, the electrode assembly 10 and the lower end part of the battery can 30 can be joined by welding.

[0106] Subsequently, the insertion part 270 is inserted into the core part 210. And while the outer diameter of the core part 210 is expanded by the insertion of the insertion part 270, the core part 210 presses the electrode assembly 10 from the center of the electrode assembly 10 toward the battery can 30.

[0107] On the other hand, before and / or after the insertion of the insertion part 270, an electrolyte can be injected into the inside of the battery can 30. In one embodiment of the present invention, the electrolyte can contain an organic solvent and a lithium salt. The solvent serves as a medium that enables ions involved in the electrochemical reaction of the battery to move.

[0108] As the organic solvent, it can be used without limitation as long as it is used in the electrolytic solution of a normal lithium secondary battery. For example, ether, ester, amide, chain carbonate, cyclic carbonate, etc. can be used alone or in combination of two or more. Among these, typically, an ether-based compound can be included.

[0109] The ether compounds can include acyclic ethers and cyclic ethers. For example, the acyclic ethers can be one or more selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, dimethoxyethane, diethoxyethane, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl ethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, and polyethylene glycol methyl ethyl ether.

[0110] For example, the cyclic ether may be one or more selected from the group consisting of 1,3-dioxolane, 4,5-dimethyl-dioxolane, 4,5-diethyl-dioxolane, 4-methyl-1,3-dioxolane, 4-ethyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2,5-dimethoxytetrahydrofuran, 2-ethoxytetrahydrofuran, 2-methyl-1,3-dioxolane, 2-vinyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, 2-methoxy-1,3-dioxolane, 2-ethyl-2-methyl-1,3-dioxolane, tetrahydropyran, 1,4-dioxane, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,4-dimethoxybenzene and isosorbid dimethyl ether, furan, 2-methylfuran, 3-methylfuran, 2-ethylfuran, 2-butylfuran, 2,3-dimethylfuran, 2,4-dimethylfuran, 2,5-dimethylfuran, pyran, 2-methylpyran, 3-methylpyran, 4-methylpyran, benzofuran, 2-(2-nitrovinyl)furan, thiophene, 2-methylthiophene, 2-ethylthiophene, 2-propylthiophene, 2-butylthiophene, 2,3-dimethylthiophene, 2,4-dimethylthiophene, 2,5-dimethylthiophene, but is not limited thereto.

[0111] Examples of the ester of the organic solvent include, but are not limited to, any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone and ε-caprolactone and mixtures of two or more thereof.

[0112] Specific examples of the linear carbonate compound typically include any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate, or a mixture of two or more thereof, but are not limited thereto.

[0113] In addition, specific examples of the cyclic carbonate compound can be ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinyl ethylene carbonate, and halides thereof, or a mixture of two or more thereof. Examples of such halides include, but are not limited to, fluoroethylene carbonate (FEC).

[0114] On the other hand, in the present invention, the lithium salt is a compound that can provide lithium ions in the electrolyte. Such lithium salts include LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3CO2, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiCH3SO3, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiC4BO8, LiCl, LiBr, LiB 10 Cl 10 , LiI, or LiB(C2O4)2, etc. can be used.

[0115] In one embodiment of the present invention, in terms of enhancing the availability of sulfur and realizing a battery with high capacity and high voltage, it is desirable that the lithium salt contains Li-TFSI. More desirably, the lithium salt can contain LiN(CF3SO2)2 (Li-TFSI) at a content of 80 wt% or more, or 90 wt% or more, or 100% based on 100 wt% of the total lithium salt.

[0116] The concentration of the lithium salt ranges from 0.1 to 2.0 M, desirably from 0.5 to 1 M, more desirably from 0.5 to 0.75 M. When the concentration of the lithium salt is within the above range, the electrolyte will have appropriate conductivity and viscosity, thus showing excellent electrolyte performance and enabling effective movement of lithium ions.

[0117] When the concentration of the lithium salt is less than the above range, it may be difficult to ensure the ionic conductivity suitable for battery driving. When it exceeds the above range, the viscosity of the electrolyte may increase, resulting in a decrease in the mobility of lithium ions, or the decomposition reaction of the lithium salt itself may increase, leading to a decrease in battery performance.

[0118] In a specific embodiment of the present invention, in the electrolyte containing the first solvent, the second solvent, and the lithium salt, the molar ratio of the lithium salt, the second solvent, and the first solvent can be 1:0.5 to 3:4.1 to 15.

[0119] Also, in one embodiment of the present invention, the molar ratio of the lithium salt, the second solvent, and the first solvent may be 1:2:4 to 13, or 1:3:3 to 10, or 1:4:5 to 10, etc. In the electrolyte contained in the lithium-sulfur battery of the present invention, the first solvent containing a fluorine-based ether compound may be contained in a higher content ratio than the second solvent containing a glyme-based compound.

[0120] On the other hand, referring to FIGS. 1, 7, and 8, the cylindrical lithium-sulfur battery cell 1 includes the electrode assembly 10 according to one embodiment of the present invention described above, a battery can 30, a positive electrode current collector 40, a cell terminal 50, and a negative electrode current collector 60.

[0121] For a detailed description of the electrode assembly 10, the above description shall apply instead.

[0122] The battery can 30 is formed in a cylindrical shape, with a through-hole formed therein, and the electrode assembly 10 is housed therein. For example, the battery can 30 is formed in a cylindrical shape, the electrode assembly 10 is housed inside the battery can 30, and can be electrically connected to the negative electrode plate 130 of the electrode assembly 10. Thereby, the battery can 30 can have the same polarity as the negative electrode plate 130, that is, a negative electrode. However, it is not necessarily limited to this.

[0123] Here, the diameter of the battery can 30 is formed larger than the diameter of the electrode assembly 10. A preset-sized gap is formed between the battery can 30 and the electrode assembly 10 (when the positive current collector 40 is coupled to the electrode assembly 10, between the battery can 30 and the positive current collector 40), and an insulator can be interposed between the gaps.

[0124] The battery can 30 can be made of a conductive material such as metal, for example. The material of the battery can 30 can be made from conductive metals such as aluminum, steel, stainless steel, etc., but is not limited thereto.

[0125] The positive current collector 40 is electrically connected to the positive electrode plate 110, and the positive current collector 40 is connected to the positive electrode plate 110 at the upper part of the electrode assembly 10. For example, the positive current collector 40 can be made of a conductive metal material.

[0126] The cell terminal 50 is made of a conductive metal material, can be coupled to the through-hole formed in the battery can 30, and is electrically connected to the positive current collector 40 through the through-hole. And the cell terminal 50 is electrically connected to the positive electrode plate 110 of the electrode assembly 10 through the positive current collector 40, and thereby has a positive positive electrode.

[0127] That is, the cell terminal 50 can function as a positive electrode terminal. And the battery can 30 is electrically connected to the negative electrode plate 130 of the electrode assembly 10 as described above, and thereby can have a negative polarity.

[0128] The negative electrode current collector 60 is electrically connected to the negative electrode plate 130. The negative electrode current collector 60 can be coupled to the lower part of the electrode assembly 10. The negative electrode current collector 60 can be made of a conductive metal material such as aluminum, steel, copper, nickel, or the like.

[0129] The negative electrode current collector 60 can be electrically connected to the battery can 30. For this purpose, at least a part of the peripheral edge of the negative electrode current collector 60 can be interposed between the inner surface of the battery can 30 and the sealing gasket and fixed.

[0130] In one embodiment, at least a part of the peripheral edge of the negative electrode current collector 60 can be fixed to the beading portion by welding while being supported by the lower end surface of the beading portion formed at the lower end of the battery can 30. In a modified embodiment, at least a part of the peripheral edge of the negative electrode current collector 60 can be directly welded to the inner wall surface of the battery can 30.

[0131] And at least a part of the peripheral edge of the negative electrode current collector 60 can be electrically coupled to the surface adjacent to the crimping portion among the upper and lower surfaces of the beading portion.

[0132] FIG. 11 is a diagram schematically showing the configuration of a battery pack according to an embodiment of the present invention, and FIG. 12 is a diagram for explaining an automobile including the battery pack of FIG. 11.

[0133] Referring to FIG. 11, a battery pack 2 according to an embodiment of the present invention may include one or more cylindrical lithium-sulfur battery cells 1 according to an embodiment of the present invention as described above. Further, the battery pack 2 may further include a pack housing 3 for housing the cylindrical lithium-sulfur battery cell 1, various devices for controlling charging and discharging of the cylindrical lithium-sulfur battery cell 1, for example, a BMS, a current sensor, a fuse, and the like.

[0134] Referring to FIG. 12, the vehicle 4 according to an embodiment of the present invention may include the above-described cylindrical lithium-sulfur battery cell 1 or battery pack 2. And the cylindrical lithium-sulfur battery cell 1 or battery pack 2 according to an embodiment of the present invention is applicable to a predetermined vehicle 4 that uses electricity, such as an electric vehicle or a hybrid vehicle.

[0135] As described above, the present invention has been described with reference to limited embodiments and drawings. However, the present invention is not limited thereto, and various modifications and variations can be made within the equivalent scope of the technical idea and claims of the present invention by those having ordinary knowledge in the technical field to which the present invention pertains.

[0136] In this specification, terms indicating directions such as up, down, left, and right are used. However, such terms indicate relative positions and are for convenience of explanation only, and it is obvious to those skilled in the art that they can change depending on the position of the object and the position of the observer.

Industrial Applicability

[0137] The present invention relates to an electrode assembly, a cylindrical lithium-sulfur battery cell including the same, a battery pack including the cylindrical lithium-sulfur battery cell, and a vehicle, and is particularly applicable to the secondary battery-related industry.

Claims

1. A jelly roll type electrode assembly having a structure in which a positive electrode plate, a negative electrode plate, and a separator interposed therebetween are wound in one direction and having a central hole formed therein, The electrode assembly includes a center pin inserted into the central hole and pressing the electrode assembly.

2. The center pin is A core portion inserted into the central hole, having an opening formed therein, and having a diameter that changes at least in part, An insertion portion inserted into the opening of the core portion to adjust the diameter of the core portion, and the electrode assembly according to claim 1, characterized in that it comprises.

3. The core portion is A support portion located at the upper portion and having the opening formed therein, A connecting portion coupled to the support portion, The electrode assembly according to claim 2, characterized in that it comprises an expansion portion coupled to the connecting portion, expanded on both sides by the insertion portion, and pressing the electrode assembly in the centrifugal direction.

4. The expansion portion includes a plurality of unit units, A preset space is formed between the plurality of unit units, The electrode assembly according to claim 3, characterized in that the insertion portion inserted from the opening is inserted through the space.

5. The expansion portion includes a first unit unit and a second unit unit, The first unit unit and the second unit unit each have at least one convex portion and at least one concave portion, The electrode assembly according to claim 4, characterized in that the convex portions and concave portions of the first unit unit and the concave portions and convex portions of the second unit unit are alternately positioned so as to correspond to each other.

6. The electrode assembly according to claim 5, characterized in that a part of the convex portion of the first unit unit engages with a part of the concave portion of the second unit unit, and a part of the concave portion of the first unit unit engages with a part of the convex portion of the second unit unit.

7. The convex portions and concave portions of the first unit unit have a curvature within a preset range, and the convex portions and concave portions of the second unit unit also have a curvature within a preset range, and the electrode assembly according to claim 6, characterized in that it has.

8. The convex portions and concave portions of the first unit unit have a round shape, The electrode assembly according to claim 7, characterized in that the convex portions and concave portions of the second unit unit also have a round shape.

9. The electrode assembly according to claim 3, wherein before the insertion part is inserted, the diameter of the expansion part gradually decreases from the upper part to the lower part.

10. The electrode assembly according to claim 3, wherein the diameter of the connection part is smaller than the diameter of the support part and smaller than the diameter of the expansion part.

11. The connection part is coupled to the central part of the support part, The electrode assembly according to claim 3, wherein the support part has a wide vertical width at the central part to which the connection part is coupled, and the vertical width gradually becomes narrower from the center to both ends.

12. The insertion part is a head, and a rod part extending from the head, and is characterized in that it includes the above, and the electrode assembly according to claim 2.

13. An electrode assembly according to any one of claims 1 to 12, a cylindrical battery can in which the electrode assembly is housed, a positive current collector electrically connected to the positive electrode plate, a cell terminal connected to the positive current collector through a through hole of the battery can, and a negative current collector electrically connected to the negative electrode plate, and includes a cylindrical lithium-sulfur battery cell.

14. A battery pack including the cylindrical lithium-sulfur battery cell according to claim 13.

15. An automobile including the cylindrical lithium-sulfur battery cell according to claim 13.

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