Battery cell and battery pack including the same

Abstract

A battery cell according to one embodiment of the present invention comprises: an electrode stack having a plurality of sequentially stacked bipolar electrodes and separators, wherein a negative active material layer and a positive active material layer are respectively coated on both sides of a metal current collector; a battery case accommodating the electrode stack; and a sealing portion formed at a portion where a first outer surface formed at the bottom of the battery case and a second outer surface formed at the top of the battery case come into contact with each other, wherein one of the first outer surface and the second outer surface extends further outward with respect to the electrode stack than the other, and one of the first outer surface and the second outer surface is bent in a direction that wraps around the other together with the sealing portion.

Description

Technology Field

[0001] The present invention relates to a battery cell and a battery pack including the same, and more specifically, to a battery cell and a battery pack including the same comprising: a battery case in which an electrode stack including a bipolar electrode is accommodated; and a packaging structure in which one of the upper outer surface and the lower outer surface is folded in a direction that wraps around the other. Background Technology

[0002] Recently, as the application areas of lithium-ion batteries have rapidly expanded to include not only power supply for electronic devices such as electrical, electronic, telecommunications, and computers, but also power storage for large-area devices such as automobiles and power storage systems, there is a growing demand for high-capacity, high-output, and high-stability secondary batteries.

[0003] The electrodes used in such secondary batteries can be classified into monopolar electrodes, in which an active material with the same polarity is coated on both sides of a current collector, and bipolar electrodes, in which an active material with different polarities is coated on both sides of a current collector.

[0004] Secondary batteries utilizing monopolar electrodes have connection points that link the electrodes, and thus their output may be degraded due to the electrical resistance of these connections. Furthermore, secondary batteries with monopolar electrodes can cause various issues regarding cell safety due to temperature rise caused by Joule heating. Additionally, there is a problem of poor space efficiency because battery components for heat dissipation structures, thermal monitoring, and wiring occupy a significant amount of space within the battery pack.

[0005] In contrast, secondary batteries using bipolar electrodes stack electrodes without having connection points, thereby minimizing electrode contact resistance. Consequently, secondary batteries using bipolar electrodes offer excellent output performance and good space efficiency due to simplified structure and components; thus, energy density and output density per unit volume can be significantly improved compared to conventional lithium-ion batteries.

[0006] Accordingly, secondary batteries applying bipolar electrodes of various structures are currently being developed. The problem to be solved

[0007] The problem to be solved by the present invention relates to a battery cell and a battery pack including the same, comprising: a battery case that accommodates an electrode stack including a bipolar electrode; and a packaging structure in which one of the upper outer surface and the lower outer surface is folded in a direction that wraps around the other.

[0008] The problems that the present invention aims to solve are not limited to those described above, and problems not mentioned will be clearly understood by those skilled in the art from this specification and the attached drawings. means of solving the problem

[0009] A battery cell according to one embodiment of the present invention comprises: an electrode stack having a plurality of sequentially stacked bipolar electrodes and separators, wherein a negative active material layer and a positive active material layer are respectively coated on both sides of a metal current collector; a battery case accommodating the electrode stack; and a sealing portion formed at a portion where a first outer surface formed at the bottom of the battery case and a second outer surface formed at the top of the battery case come into contact with each other, wherein one of the first outer surface and the second outer surface extends further outward with respect to the electrode stack than the other, and one of the first outer surface and the second outer surface is bent in a direction that wraps around the other together with the sealing portion.

[0010] The first outer surface and the second outer surface may be compressed against each other.

[0011] The first outer surface may be extended further outward with respect to the electrode stack than the second outer surface, and the first outer surface may be bent in a direction that wraps around the second outer surface together with the sealing portion.

[0012] The battery case may include a lower metal located on the lower surface of the electrode stack and covering the lower part of the electrode stack, and an upper metal located on the upper surface of the electrode stack and covering the upper part of the electrode stack.

[0013] The lower metal includes a lower storage portion in which the electrode stack is accommodated, and the first outer surface is the outer surface of the lower storage portion, and the upper metal may include an upper storage portion in which the electrode stack is accommodated, and the second outer surface may be the outer surface of the upper storage portion.

[0014] It may further include a buffer member extending along the space between the first outer surface and the second outer surface.

[0015] The above buffer member is extended more briefly outwardly with respect to the electrode stack compared to one of the first outer surface and the second outer surface, and the buffer member may be extended more fully outwardly with respect to the electrode stack compared to the other of the first outer surface and the second outer surface.

[0016] The above cushioning member may be bent in a direction that wraps together the other one of the first outer surface and the second outer surface and the sealing portion.

[0017] The above electrode laminate further includes an electrolyte impregnated therein, and the battery case can accommodate the electrolyte together with the electrode laminate.

[0018] The above electrolyte may be a gel or a solid electrolyte.

[0019] The electrode stack further includes a pair of single-sided cathodes and single-sided anodes, each disposed at the outermost edge based on the stacking direction, wherein the single-sided cathode has a single-sided cathode active material layer formed on one surface of a cathode current collector, and the single-sided anode has a single-sided anode active material layer formed on one surface of an anode current collector.

[0020] The separator may be disposed between the above-mentioned single-sided cathode, the above-mentioned single-sided anode, and the above-mentioned bipolar electrode, respectively.

[0021] The negative current collector included in the above-mentioned single-sided negative electrode and the positive current collector included in the above-mentioned single-sided positive electrode can each come into contact with the battery case.

[0022] A battery pack according to another embodiment of the present invention may include the battery cell described above. Effects of the invention

[0023] According to the embodiments, the battery cell of the present invention and the battery pack including the same include a battery case made of a metal material that accommodates an electrode stack including a bipolar electrode, and has the advantage that the battery case itself can perform the role of an electrode tab.

[0024] In addition, the battery cell and battery pack including the same according to the present invention include a battery case that accommodates an electrode stack including a bipolar electrode; and a packaging structure in which one of the upper outer surface and the lower outer surface is folded in a direction that wraps around the other, thereby having the advantage of stably maintaining contact between the components of the electrode stack even during charging and discharging by pressing the electrode stack in the vertical direction.

[0025] The effects of the present invention are not limited to the effects described above, and unmentioned effects will be clearly understood by those skilled in the art from this specification and the accompanying drawings. Brief explanation of the drawing

[0026] FIG. 1 is a cross-sectional view of a battery cell according to one embodiment of the present invention. Figure 2 is a cross-sectional view of an electrode stack included in the battery cell of Figure 1. Figure 3 is a cross-sectional view showing that the upper and lower parts of a battery case are combined with the electrode stack of Figure 2. FIG. 4 is a cross-sectional view showing that a first outer surface formed on the lower part of a battery case coupled to the electrode stack of FIG. 3 is bent in a direction that wraps around a second outer surface formed on the upper part of the battery case. Specific details for implementing the invention

[0027] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0028] To clearly explain the present invention, parts unrelated to the explanation have been omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0029] Furthermore, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and thus the present invention is not necessarily limited to what is illustrated. Thicknesses have been enlarged in the drawings to clearly represent various layers and regions. Additionally, for convenience of explanation, the thickness of some layers and regions has been exaggerated in the drawings.

[0030] Furthermore, throughout the specification, when a part is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0031] Additionally, throughout the specification, "planar" means when the subject part is viewed from above, and "cross-sectional" means when the cross-section obtained by vertically cutting the subject part is viewed from the side.

[0032] Hereinafter, a battery cell according to an embodiment of the present invention will be described.

[0033] FIG. 1 is a cross-sectional view of a battery cell according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of an electrode stack included in the battery cell of FIG. 1.

[0034] Referring to FIG. 1 and FIG. 2, a battery cell (100) according to one embodiment of the present invention comprises: an electrode stack (110) in which a bipolar electrode (111) and a separator (115) are sequentially stacked multiple times, wherein a negative electrode active material layer (111b) and a positive electrode active material layer (111c) are respectively coated on both sides of a metal current collector (111a); and a battery case (120) that accommodates the electrode stack (110).

[0035] More specifically, in the electrode stack (110), the bipolar electrode (111) is formed such that a negative active material layer (111b) and a positive active material layer (111c) are respectively coated on both sides of a metal current collector (111a), which can be referred to as a unit cell. Here, the bipolar electrode (111) may refer to a structure in which the negative active material layer (111b) and the positive active material layer (111c) are connected in series with the metal current collector (111a) in between. As an example, as shown in FIGS. 1 and 2, the bipolar electrode (111) may have a negative active material layer (111b) coated on the lower surface of the metal current collector (111a) and a positive active material layer (111c) coated on the upper surface of the metal current collector (111a). However, the arrangement of the negative electrode active material layer (111b) and the positive electrode active material layer (111c) is not limited thereto, and the opposite case may also be included in this embodiment.

[0036] The metal current collector (111a) is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, the metal current collector (111a) may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy. More specifically, it may be an Al current collector or a Cu current collector. Here, the Al current collector or the Cu current collector may be made of Al or Cu, and the concept includes the inclusion of other metal materials in addition to the impurity content.

[0037] Regardless of the type, the metal current collector (111a) may have a thickness of 3 μm or more to 500 μm or less, and may also have fine irregularities formed on the surface of the current collector to increase adhesion to the positive active material layer and the negative active material layer. As an example, the metal current collector (111a) may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0038] The negative electrode active material layer (111b) may include a negative electrode active material commonly used in lithium secondary batteries, a binder, a conductive material, and other additives as described above.

[0039] The positive active material layer (111c) may include a positive active material commonly used in lithium secondary batteries, a binder, a conductive material, and other additives as described above.

[0040] The separator (115) can be used without any special limitations as long as it is used as a separator in a lithium secondary battery, and it is particularly desirable that it has low resistance to the movement of ions of the electrolyte described later and excellent electrolyte moisture retention ability.

[0041] Accordingly, in the battery cell (100) according to the present embodiment, the bipolar electrode (111) is connected in series as itself, and compared to the structure in which electrode current collectors (111a) are welded together to form an electrode tab, there is an advantage that the electrical connection structure is structurally simplified.

[0042] Additionally, as shown in FIGS. 1 and 2, the electrode stack (110) may further include a pair of single-sided cathodes (117) and single-sided anodes (119) respectively disposed at the outermost edge with respect to the stacking direction. Here, the single-sided cathode (117) may have a single-sided cathode active material layer (117b) formed on one side of a cathode current collector (117a), and the single-sided anode (119) may have a single-sided anode active material layer (119b) formed on one side of an anode current collector (119a). Additionally, in the electrode stack (110), a separator (115) may be disposed between the single-sided cathode (117) and the single-sided anode (119) and the bipolar electrode (111).

[0043] For example, as shown in FIGS. 1 and 2, a single-sided cathode (117) may be disposed on the outermost upper side of the electrode stack (110), and a single-sided anode (119) may be disposed on the outermost lower side of the electrode stack (110). However, the arrangement of the single-sided cathode (117) and the single-sided anode (119) is not limited thereto and may be changed according to the arrangement of the cathode active material layer (111b) and the anode active material layer (111c) included in the bipolar electrode (111).

[0044] As shown in FIG. 1, the electrode stack (110) can have a negative current collector (117a) included in the single-sided negative electrode (117) and a positive current collector (119a) included in the single-sided positive electrode (119) each in contact with the battery case (120). More specifically, the single-sided negative electrode (117) is positioned on the outermost upper side of the electrode stack (110), and the negative current collector (117a) included in the single-sided negative electrode (117) can be in contact with the upper side of the battery case (120). Additionally, the single-sided positive electrode (119) is positioned on the outermost lower side of the electrode stack (110), and the positive current collector (119a) included in the single-sided positive electrode (119) can be in contact with the lower side of the battery case (120).

[0045] The negative current collector (117a) and the positive current collector (119a) are not particularly limited as long as they each have high conductivity without causing chemical changes in the battery. For example, the negative current collector (117a) and the positive current collector (119a) may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy. More specifically, the negative current collector (117a) may be a Cu current collector, and the positive current collector (119a) may be an Al current collector. Here, the Al current collector or the Cu current collector may be made of Al or Cu, and the concept includes the inclusion of other metal materials in addition to the impurity content.

[0046] The cross-sectional negative electrode active material layer (117b) may include a negative electrode active material commonly used in lithium secondary batteries, a binder, a conductive material, and other additives as described above.

[0047] The cross-sectional positive active material layer (119b) may include a positive active material typically used in lithium secondary batteries, a binder, a conductive material, and other additives as described above.

[0048] Accordingly, in the battery cell (100) according to the present embodiment, a single-sided negative electrode (117) and a single-sided positive electrode (119) are respectively arranged at the outermost edge of the electrode stack (110), and the negative current collector (117a) and the positive current collector (119a) can perform the role of an electrode tab, thus having the advantage that a separate electrode tab is not required. In addition, since the front surface of the negative current collector (117a) and the positive current collector (119a) becomes a passage for electron movement, there is an advantage that it is more effective in terms of resistance than conventional electrode tabs.

[0049] Referring to FIG. 1, in a battery cell (100) according to the present embodiment, the electrode stack (110) is impregnated with an electrolyte (110e), and the battery case (120) can accommodate the electrolyte (110e) together with the electrode stack (110). Here, the electrolyte (110e) may be a gel or a solid electrolyte.

[0050] The above gel-type electrolyte comprises a lithium salt and a non-aqueous organic solvent, and at least one polymerizable compound selected from the group consisting of a polymerizable monomer, oligomer, or copolymer having a polymerizable unsaturated functional group, and at least some of the polymerizable unsaturated functional group may be hardened.

[0051] In other words, the gel-type electrolyte may be a gel electrolyte composition that is cured by heat or light, comprising a lithium salt, a non-aqueous organic solvent, and at least one polymerizable compound selected from the group consisting of polymerizable monomers, oligomers, or copolymers having polymerizable unsaturated functional groups. Here, the lithium salt may be used in the same or similar way as that typically used in lithium secondary batteries. The lithium salt may be used as a medium for transferring ions within the lithium battery.

[0052] The above-mentioned solid electrolyte may be an organic solid electrolyte or an inorganic solid electrolyte.

[0053] The above organic solid electrolyte may be, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, a polymer containing an ionic dissociator, etc.

[0054] The above inorganic solid electrolyte may be, for example, a Li nitride, halide, sulfate, sulfide-based solid electrolyte, or an oxide solid electrolyte.

[0055] As the above inorganic solid electrolyte, for example, nitrides, halides, sulfates of Li such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2, etc., may be used, or sulfide-based solid electrolytes or oxide solid electrolytes may be used.

[0056] The above sulfide-based solid electrolyte is a Li2S-P2S5 system (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 (Li 13 GeP3S 16 , Li 10 GeP2S 12 etc.), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x Examples include, but are not limited to, combinations thereof.

[0057] The above oxide-based solid electrolyte is an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeS b O12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP-based compounds, LATP-based compounds, Li 1+x Ti 2-x Al x Si y (PO4) 3-y (where, 0≤x≤1, 0≤y≤1), LiAl x Zr 2-x (PO4)3(where, 0≤x≤1), LiTi x Zr 2-x It may include any one selected from the group consisting of (PO4)3 (wherein, 0≤x≤1), LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, Nasicon-based compounds, LLZO-based compounds, and LLZMO-based compounds, or two or more of these.

[0058] Accordingly, in the battery cell (100) according to the present embodiment, as the electrolyte (110e) includes a gel or solid form electrolyte, the fluidity of the electrolyte (110e) can be minimized, and an ionic short between bipolar electrodes (111) or an electronic short between metal current collectors (111a) caused by the fluidity of the electrolyte (110e) can be effectively prevented.

[0059] FIG. 3 is a cross-sectional view showing that the upper and lower parts of a battery case are combined with the electrode stack of FIG. 2. FIG. 4 is a cross-sectional view showing that a first outer surface formed on the lower part of the battery case combined with the electrode stack of FIG. 3 is bent in a direction that wraps around a second outer surface formed on the upper part of the battery case.

[0060] Referring to FIGS. 1 to 3, the battery cell (100) according to the present embodiment may include a sealing portion formed at a portion where a first outer surface (121s) formed at the bottom of the battery case (120) and a second outer surface (125s) formed at the top of the battery case (120) come into contact with each other. Here, the sealing portion may be a portion where the first outer surface (121s) formed at the bottom of the battery case (120) and the second outer surface (125s) formed at the top of the battery case (120) are joined to each other in a manner such as welding.

[0061] In the battery cell (100) according to the present embodiment, the battery case (120) may include a lower metal (121) located on the lower surface of the electrode stack (110) and covering the lower part of the electrode stack (110), and an upper metal (125) located on the upper surface of the electrode stack (110) and covering the upper part of the electrode stack (110). For example, as shown in FIG. 3, the battery cell (100) according to the present embodiment may have a structure in which the upper metal (125) is assembled on the upper part of the electrode stack (110) while the electrode stack (110) is accommodated in the lower metal (121).

[0062] In the electrode stack (110), the negative current collector (117a) included in the single-sided negative electrode (117) and the positive current collector (119a) included in the single-sided positive electrode (119) can each come into contact with the lower metal (121) and the upper metal (125) included in the battery case (120). For example, as shown in FIG. 1, in the electrode stack (110), the negative current collector (117a) included in the single-sided negative electrode (117) can come into contact with the upper metal (125), and the positive current collector (119a) included in the single-sided positive electrode (119) can come into contact with the lower metal (121).

[0063] Accordingly, in the battery cell (100) according to the present embodiment, the electrode stack (110) and the battery case (120) can be connected in series as they are, and there is an advantage that a separate electrical connection structure is not required.

[0064] For example, the lower metal (121) and the upper metal (125) are not specifically limited as long as they are metal materials that have high conductivity without causing chemical changes in the battery. For example, the lower metal (121) and the upper metal (125) may be made of aluminum, SUS (Steel Use Stainless), etc. Additionally, regardless of their type, the lower metal (121) and the upper metal (125) may have a thickness of 0.1 mm (0.1 T) or more and 0.3 mm (0.3 T) or less in terms of manufacturing process and cost.

[0065] In the battery case (120), the lower metal (121) includes a lower storage portion (121p) in which an electrode stack (110) can be accommodated, and the first outer surface (121s) may be the outer surface of the lower storage portion (121p). Additionally, in the battery case (120), the upper metal (125) includes an upper storage portion (125p) in which an electrode stack (110) can be accommodated, and the second outer surface (125s) may be the outer surface of the upper storage portion (125p).

[0066] However, the shape of the battery case (120) included in the battery cell (100) according to the present embodiment is not limited to this, and various shapes of the battery case (120) may be applied. For example, unlike FIGS. 1 and FIGS. 3, the battery case (120) may be in a form in which the upper storage portion (125p) of the upper metal (125) is omitted, and a structure in which the upper metal (125) in the form of a flat plate covers the lower metal (121) may also be included in the present embodiment.

[0067] The battery cell (110) according to the present embodiment may further include a buffer member (130) extending along the first outer surface (121s) of the lower metal (121) and the second outer surface (125s) of the upper metal (125). Here, the buffer member (130) is preferably in the form of a pad sized to cover the entire area between the first outer surface (121s) of the lower metal (121) and the second outer surface (125s) of the upper metal (125).

[0068] For example, as shown in FIGS. 1 to 3, the battery cell (100) according to the present embodiment may accommodate an electrode stack (110) in a lower storage portion (121p) of a lower metal (121) while a buffer member (130) is disposed on a first outer surface (121s) of a lower metal (121). Subsequently, an upper metal (125) is assembled on the upper part of the electrode stack (110), so that the second outer surface (125s) comes into contact with the buffer member (130).

[0069] The cushioning member (130) is not particularly limited as long as it is made of a material having elasticity that allows for some degree of compression during the process in which one of the first outer surface (121s) and the second outer surface (125s) is bent to wrap around the other, while ensuring insulation performance between the first outer surface (121s) of the lower metal (121) and the second outer surface (125s) described later. For example, the cushioning member (130) may be a porous pad such as a silicone pad, a polymer elastomer pad, or a nonwoven fabric.

[0070] Accordingly, in the battery cell (100) according to the present embodiment, a buffer member (130) is additionally disposed between the first outer surface (121s) of the lower metal (121) and the second outer surface (125s) of the upper metal (125), thereby ensuring sufficient insulation performance between the lower metal (121) and the upper metal (125), and there is an advantage that compression is possible during the process of one of the first outer surface (121s) and the second outer surface (125s) being bent in a direction that wraps around the other, thereby allowing the upper and lower parts of the electrode laminate (110) to be pressed with a predetermined pressure.

[0071] As such, the battery cell (100) according to the present embodiment has the advantage that contact between the components of the electrode stack (110) can be stably maintained during the contraction or expansion of the electrode stack (110) due to charging or discharging of the battery cell (100) as the upper and lower parts of the electrode stack (110) are pressed by a predetermined pressure.

[0073] Referring to FIG. 1 and FIG. 4, in the battery cell (100) according to the present embodiment, in the battery case (120), one of the first outer surface (121s) and the second outer surface (125s) may be extended further outward with respect to the electrode stack (110) than the other. For example, as shown in FIG. 4, in the battery case (120), the first outer surface (121s) may be extended further outward with respect to the electrode stack (110) than the second outer surface (125s).

[0074] Here, one of the first outer surface (121s) and the second outer surface (125s) may be bent in a direction that wraps around the other one together with the sealing portion. Additionally, one of the first outer surface (121s) and the second outer surface (125s) may cover the upper part of the other one. For example, as shown in FIGS. 1 and 4, in a battery case (120), the first outer surface (121s) may be bent in a direction that wraps around the second outer surface (125s) together with the sealing portion. Additionally, the first outer surface (121s) may cover the upper part of the second outer surface (125s). In FIG. 4, the first bent portion (120c) may refer to the portion where the first outer surface (121s) is bent in a direction that wraps around the second outer surface (125s).

[0075] At this time, in the battery cell (100) according to the present embodiment, the first outer surface (121s) and the second outer surface (125s) of the battery case (120) may be pressed together. In other words, the space between the first outer surface (121s) and the second outer surface (125s) of the battery case (120) may be sealed.

[0076] Accordingly, in the battery cell (100) according to the present embodiment, the first outer surface (121s) is bent in a direction that wraps the second outer surface (125s) together with the sealing portion, so that the lower metal (121) and the upper metal (125) of the battery case (120) can be stably fixed to each other. That is, the first bent portion (120c) formed on the first outer surface (121s) presses the electrode stack (110) in the vertical direction, thereby having the advantage of stably maintaining contact between the components of the electrode stack even during charging and discharging.

[0077] In addition, the first bend (120c) formed on the first outer surface (121s) seals the space between the first outer surface (121s) and the second outer surface (125s), while preventing the first outer surface (121s) and the second outer surface (125s) from being exposed to the outside, making it easy to handle the battery cell (100) during the process and effectively preventing foreign substances such as moisture from penetrating into the battery cell (100) from the outside.

[0078] In addition, since the sealing structure between the first outer surface (121s) and the second outer surface (125s) can be formed relatively easily through the first bending portion (120c), the battery cell (100) according to the present embodiment has the advantage of having a packaging structure with improved ease of assembly and productivity.

[0079] In addition, unlike as illustrated in FIGS. 1, 3, and 4, the battery cell (100) according to the present embodiment may also include a case where the length of the second outer surface (125s) of the upper metal (125) is greater than the length of the first outer surface (121s) of the lower metal (121). That is, in this case, the second outer surface (125s) of the upper metal (125) may be bent in a direction that wraps around the first outer surface (121s) together with the sealing portion. The technical advantages of the present embodiment may be described in the same way as the embodiments illustrated in FIGS. 1, 3, and 4.

[0080] Referring to FIG. 4, in the battery cell (100) according to the present embodiment, the buffer member (130) may be extended further outward with respect to the electrode stack (110) than one of the first outer surface (121s) and the second outer surface (125s). Additionally, the buffer member (130) may be extended further outward with respect to the electrode stack (110) than the other of the first outer surface (121s) and the second outer surface (125s).

[0081] Here, the cushioning member (130) may be bent in a direction that wraps around the sealing portion together with the other of the first outer surface (121s) and the second outer surface (125s). For example, as shown in FIGS. 1 and 4, in the battery case (120), the cushioning member (130) may be bent in a direction that wraps around the second outer surface (125s) together with the sealing portion. Additionally, the cushioning member (130) may cover the upper part of the second outer surface (125s). In FIG. 4, the second bent portion (130c) may refer to the part where the cushioning member (130) is bent in a direction that wraps around the second outer surface (125s).

[0082] At this time, in the battery cell (100) according to the present embodiment, the first outer surface (121s), the second outer surface (125s) of the battery case (120), and the buffer member (130) may be compressed against each other. In other words, the first outer surface (121s), the second outer surface (125s) of the battery case (120), and the buffer member (130) may be sealed together.

[0083] Accordingly, in the battery cell (100) according to the present embodiment, a buffer member (130) is additionally disposed between the first outer surface (121s) of the lower metal (121) and the second outer surface (125s) of the upper metal (125). As the first outer surface (121s) and the buffer member (130) are bent together, a second bent portion (130c) can be formed between the first bent portion (120c) of the first outer surface (121s) and the second outer surface (125s). At this time, the second bent portion (130c) of the buffer member (130) has the advantage of sufficiently ensuring insulation performance between the first bent portion (120c) and the second outer surface (125s).

[0084] In addition, in the battery cell (100) according to the present embodiment, as the first outer surface (121s) and the cushioning member (130) are bent together, the cushioning member (130) is sealed in a compressed state within the first bent portion (120c) of the first outer surface (121s), thereby effectively preventing air and / or moisture from entering from the outside of the battery cell (100).

[0085] In addition, unlike as illustrated in FIGS. 1, 3, and 4, the battery cell (100) according to the present embodiment may also include a case where the length of the second outer surface (125s) of the upper metal (125) is greater than the length of the first outer surface (121s) of the lower metal (121). That is, in this case, a cushioning member (130) is additionally disposed between the second outer surface (125s) of the upper metal (125) and the first outer surface (121s) of the lower metal (121), and as the second outer surface (125s) and the cushioning member (130) are bent together, a second bent portion (130c) may be formed between the first bent portion (120c) of the first outer surface (121s) and the second outer surface (125s). The technical advantages of the present embodiment may be described in the same way as the embodiment illustrated in FIGS. 1, 3, and 4.

[0086] A battery pack according to another embodiment of the present invention may include the battery cell (100) described above. Meanwhile, the battery pack according to the present embodiment may be formed by directly packaging one or more of the battery cells (100) described above within a pack case, or by manufacturing the battery cells (100) in battery module units and then packaging them within a pack case.

[0087] The battery pack described above can be applied to various devices. While such devices may include means of transportation such as electric bicycles, electric vehicles, and hybrid vehicles, the present invention is not limited thereto and can be applied to various devices capable of using the battery pack, and this also falls within the scope of the present invention.

[0089] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0090] 100: Battery cell 110: Electrode laminate 110e: Electrolyte 120: Battery case 130: Buffer member

Claims

Claim 1 An electrode stack having a bipolar electrode and a separator sequentially stacked multiple times, wherein a negative active material layer and a positive active material layer are coated on each side of a metal current collector; a battery case accommodating the electrode stack; and a sealing portion formed at a portion where a first outer surface formed at the bottom of the battery case and a second outer surface formed at the top of the battery case come into contact with each other, wherein one of the first outer surface and the second outer surface extends further outwardly with respect to the electrode stack than the other, and one of the first outer surface and the second outer surface is bent in a direction that wraps around the other together with the sealing portion. Claim 2 In claim 1, the first outer surface and the second outer surface are compressed together in a battery cell. Claim 3 A battery cell according to claim 1, wherein the first outer surface extends further outwardly with respect to the electrode stack than the second outer surface, and the first outer surface is bent in a direction that wraps around the second outer surface together with the sealing portion. Claim 4 A battery cell according to claim 1, wherein the battery case comprises a lower metal located on the lower surface of the electrode stack and covering the lower part of the electrode stack, and an upper metal located on the upper surface of the electrode stack and covering the upper part of the electrode stack. Claim 5 A battery cell according to claim 4, wherein the lower metal includes a lower housing portion in which the electrode stack is received, the first outer surface is the outer surface of the lower housing portion, and the upper metal includes an upper housing portion in which the electrode stack is received, and the second outer surface is the outer surface of the upper housing portion. Claim 6 A battery cell according to claim 1, further comprising a buffer member extending along the space between the first outer surface and the second outer surface. Claim 7 A battery cell according to claim 6, wherein the buffer member is extended more briefly outwardly with respect to the electrode stack compared to one of the first outer surface and the second outer surface, and the buffer member is extended more fully outwardly with respect to the electrode stack compared to the other of the first outer surface and the second outer surface. Claim 8 In claim 7, the buffer member is a battery cell that is bent in a direction that wraps together the sealing portion and the other one of the first outer surface and the second outer surface. Claim 9 In claim 1, the battery cell further comprises an electrolyte impregnated with the electrode laminate, and the battery case accommodates the electrolyte together with the electrode laminate. Claim 10 In claim 9, the above electrolyte is a battery cell in which the electrolyte is a gel or solid form. Claim 11 A battery cell according to claim 1, wherein the electrode stack further comprises a pair of single-sided negative electrodes and single-sided positive electrodes respectively disposed at the outermost edge with respect to the stacking direction, wherein the single-sided negative electrode has a single-sided negative active material layer formed on one surface of a negative current collector, and the single-sided positive electrode has a single-sided positive active material layer formed on one surface of a positive current collector. Claim 12 A battery cell according to claim 11, wherein the separator is disposed between the single-sided cathode, the single-sided anode, and the bipolar electrode, respectively. Claim 13 A battery cell in which, in claim 11, the negative current collector included in the cross-sectional negative electrode and the positive current collector included in the cross-sectional positive electrode each come into contact with the battery case. Claim 14 A battery pack comprising the battery cell of claim 1.

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