KR101170881B1 - High Power Secondary Battery of Series Connection Structure - Google Patents

Abstract

The present invention is a secondary battery including two unit cells, one electrode tab of the unit cells protrude out of the case, the opposite electrode tab is interconnected in a series connection method, each battery case is formed with a receiving portion It consists of a first member and a second member that includes a surplus for the diaphragm extending from one side of the first member or the second member so as to physically separate the electrolyte of the unit cells, Provided is a secondary battery having a structure in which the inner electrode tab connection part is heat-sealed together with a case sealing part in a state in which the excess portion for diaphragm is positioned between each of the mounted unit cells.

Accordingly, since the secondary battery according to the present invention includes unit cells connected in series, the secondary battery may exhibit high voltage and high output, and may have a compact structure, thereby improving battery capacity and lifespan, and configuring a battery pack. Management is easy by reducing the number of cells to be managed in a battery management system (BMS). In addition, it is possible to manufacture by a simple assembly process, it is possible to reduce the part price, the production cost is low, the production efficiency is high.

Description

High Power Secondary Battery of Series Connection Structure

The present invention relates to a high output secondary battery having a series connection structure, and more particularly, to a secondary battery having a structure in which two unit cells are heat-sealed and sealed at an outer circumferential surface sealing portion of a battery case in a state in which two unit cells are mounted in the case accommodation unit. The cells are formed with their positive and negative tabs in opposite positions, one electrode tab of the unit cells protrudes out of the case, and the opposite electrode tabs are interconnected in series, and the battery case is stored, respectively. The first member and the second member are formed integrally or separated type, and includes a diaphragm excess extending from one side of the first member or the second member to physically separate the electrolyte of the unit cells. In the state in which the surplus for the diaphragm is located between the unit cells respectively mounted to the case housing parts, The present invention relates to a secondary battery having a structure in which the internal electrode tab connection part is heat-sealed together with the case sealing part.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been widely used as energy sources for wireless mobile devices. Secondary batteries are also attracting attention as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are proposed as a way to solve air pollution in conventional gasoline and diesel vehicles that use fossil fuels. have.

In a small mobile device, one or two or more battery cells are used per device, while a middle- or large-sized battery module such as an automobile is used as a middle- or large-sized battery module in which a plurality of battery cells are electrically connected due to the necessity of a large-

Since the medium-large battery module is preferably manufactured in a small size and weight, the rectangular battery, the pouch-type battery, etc., which can be charged with high integration and have a small weight to capacity, are mainly used as battery cells of the medium-large battery module. In particular, a pouch-type battery using an aluminum laminate sheet or the like as an exterior member has attracted much attention in recent years due to the advantages of low weight and low manufacturing cost.

1 is a perspective view schematically showing a typical representative pouch-type battery. The pouch-type battery of FIG. 1 has a structure in which two electrode leads 11 and 12 protrude from each other to protrude from an upper end and a lower end of the battery main body 13, respectively. The exterior member 14 is composed of two upper and lower units, and both side surfaces 14b and upper and lower ends 14a, which are mutually contacting portions, with electrode assemblies (not shown) mounted on an accommodating portion formed on an inner surface thereof. The battery 10 is made by attaching 14c). The exterior member 14 has a laminate structure of a resin layer / metal foil layer / resin layer, and can be attached by mutually fusion bonding the resin layer by applying heat and pressure to both side surfaces 14b and the upper and lower ends 14a and 14c which are in contact with each other. In some cases, the adhesive may be attached using an adhesive. Since both side surfaces 14b are in direct contact with the same resin layer of the upper and lower exterior members 14, uniform sealing is possible by melting. On the other hand, since the electrode leads 11 and 12 protrude from the upper end 14a and the lower end 14c, the sealing properties are improved in consideration of the thickness of the electrode leads 11 and 12 and the heterogeneity with the material of the exterior member 14. Heat-sealing is carried out in the state which interposed the film-like sealing member 16 between the electrode leads 11 and 12 so that it may be made.

However, since the mechanical rigidity of the exterior member 14 itself is not excellent, in order to manufacture a battery module having a stable structure, battery cells are manufactured by mounting battery cells (unit cells) in a pack case such as a cartridge. However, since a mounting space is generally limited to a device or a vehicle on which a medium / large battery module is mounted, when the size of the battery module is increased due to the use of a pack case such as a cartridge, there is a problem of low space utilization. In addition, the low mechanical stiffness of the battery cell results in repeated expansion and contraction of the battery cell during charging and discharging, thereby causing a case where the heat fusion sites are separated.

In addition, since a battery module is a structure in which a plurality of battery cells are combined, when some battery cells are overvoltage, overcurrent, and overheating, safety and operation efficiency of the battery module are greatly detrimental, and thus a means for detecting them is necessary. Therefore, safety systems such as fuses, bimetals, and battery management systems (BMS) are provided to check and control the operation state in real time or at regular intervals. This safety system is difficult to manage the larger the number of cells, the installation or connection of such a detection means makes the assembly process of the battery module very complicated and there is a risk of short circuit due to a number of wiring for this.

Apart from this, when constructing a medium-large battery module using a plurality of battery cells or a medium-large battery module using a plurality of unit modules consisting of a predetermined unit of battery cells, for the mechanical fastening and electrical connection of the Since many members are needed, the process of assembling these members is very complicated. Moreover, space is required for joining, welding, soldering, etc. a plurality of members for mechanical fastening and electrical connection, thereby increasing the size of the entire system. This increase in size is not desirable in view of the above-described, high voltage and high output characteristics, can be easily and easily manufactured and managed, there is a high need for a secondary battery having a compact and excellent structural stability.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art and the technical problems required from the past.

An object of the present invention is to provide a secondary battery having a structure comprising two unit cells, and connected in series with each other to exhibit high voltage and high output characteristics.

Still another object of the present invention is to provide a method of manufacturing a secondary battery including two unit cells connected in series in a simple and easy manner.

A secondary battery according to the present invention for achieving the above object is a secondary battery having a structure in which the outer peripheral surface sealing portion of the battery case is heat-sealed and sealed in a state in which two unit cells are mounted in the case accommodating part.

Each of the unit cells has a positive electrode tab and a negative electrode tab formed at opposite positions, and one electrode tab ('external electrode tab') of the unit cells protrudes out of the case and the opposite electrode tab ('inner electrode tab'). ) Are interconnected by serial connection,

The battery case includes a first member and a second member each having an accommodating portion formed integrally or separately, and the diaphragm extends from one side of the first member or the second member so as to physically separate the electrolyte of the unit cells. Contains surplus for

The inner electrode tab connection part is heat-sealed together with the case sealing part in a state in which the redundant portion for diaphragm is positioned between the unit cells mounted in the case accommodating parts.

Therefore, since the secondary battery according to the present invention includes a plurality of unit cells connected in series, the secondary battery can exhibit high voltage and high output, and can be manufactured as a battery having high efficiency compared to volume by having a compact structure. For example, when one unit cell is applied to a lithium secondary battery generating an electromotive force of about 3.6 V, an electromotive force of about 7.2 V is generated, and thus, when the unit cell is applied to HEV or EV, which requires a high operating voltage, excellent performance is obtained. Can be exercised.

In addition, when a plurality of secondary batteries according to the present invention are configured as battery modules, the number of cells to be managed in a battery management system (BMS) is reduced compared to the same standard, thereby enabling efficient management. In addition, the number of cells required to be installed or connected to the detection means, etc. may be reduced, thereby simplifying the assembly process of the battery module, reducing the risk of short circuit due to a plurality of wirings, and reducing the cost of parts. There is this.

In addition, since the redundant portion for diaphragm for physically separating the unit cells is integrally formed with the battery case, the assembly process is very simple and easy, so there is an advantage of excellent process efficiency.

In the present invention, the secondary battery has two unit cells connected to each other in a series connection method, such a structure may provide a high output secondary battery because the structure has a voltage twice as large as that of a case including one unit cell. .

When each unit cell is referred to as a first unit cell and a second unit cell, the outer electrode tab of the first unit cell and the outer electrode tab of the second unit cell have opposite polarities, and the inner electrode tab of the first unit cell. The internal electrode tabs of the second unit cells and the second unit cells may have opposite polarities, and thus may be connected in series.

In a specific example, the outer electrode tab and the inner electrode tab of the first unit cell and the second unit cell protrude from the upper and lower ends of the unit cell, respectively, in the first unit cell, the outer electrode tab is a cathode, and the inner electrode tab is The cathode may be an anode, and the outer electrode tab may be an anode in the second unit cell, and the inner electrode tab may be a cathode. Accordingly, by connecting the positive electrode tab of the first unit cell and the negative electrode tab of the second unit cell with each other, and connecting the negative electrode tab and the positive electrode tab, which are the outer electrode tabs of the first unit cell and the second unit cell, to the external input / output terminals, Battery cells are connected in series.

The external electrode tab protrudes out of the case from the outermost unit cell and is connected to an external input / output terminal. When all of the external input / output terminals are located on the top surface of the battery case, the external electrode tabs may preferably have a structure protruding to the top of the case. At this time, since the negative electrode tab and the positive electrode tab should not be in contact with each other, in order to minimize the possibility of such contact, it is preferable to be formed at positions spaced from each other, for example, it may be formed on the left and right of the upper case, for example.

In addition, as a preferred example for minimizing the possibility of contact between the inner electrode tab and the outer electrode tab and the opposite polarities of the tabs, the inner electrode tabs are all formed at the center of the top or bottom of the unit cells, The external electrode tabs may have a structure formed at the upper left and right sides of the case, respectively.

Electrical connection between the internal electrode tabs may be achieved by a separate connection member or may be directly coupled. In consideration of the ease and economical efficiency of the manufacturing process, it is preferable to directly join by means of welding or soldering without a separate connection member by forming the same direction and position of the inner electrode tabs protruding from adjacent unit cells. . The welding method may be carried out by a known method and is not particularly limited, and examples thereof include resistance welding, spot welding, ultrasonic welding, laser welding, electron beam welding, arc welding, and the like.

In the present invention, the battery case has a first member and a second member, each of which is provided with an accommodating part, are formed in one piece or in a separate type. Here, the 'integral type' means that the first member and the second member share one side and are formed integrally with one unit, and the 'separate type' means that the first member and the second member are two units. Means formed separately from the member. In the following, they are sometimes referred to as an integrated battery case (first embodiment) and a separate battery case (second embodiment), respectively.

The battery case may be preferably made of a laminate sheet including a metal layer and a resin layer. In the battery case of the laminate sheet, a sealing portion is formed on the outer circumferential surface of the housing part, and thus the first member and the second member may be coupled by performing a heat fusion process at a portion where the laminate sheets are in contact with each other along the sealing portion.

The battery case of the laminate sheet may be formed, for example, from a laminate sheet composed of an outer coating layer of a polymer film, a barrier layer of metal foil, and an inner sealant layer of a polyolefin series. Since the outer coating layer must have excellent resistance from the external environment, it is necessary to have a tensile strength and weather resistance of at least a predetermined level. In such aspect, a stretched nylon film or polyethylene terephthalate (PET) may be preferably used as the polymer resin of the outer resin layer. The barrier layer is preferably aluminum may be used to exhibit a function of improving the strength of the battery case in addition to the function of preventing the inflow or leakage of foreign substances such as gas, moisture. The inner sealant layer has a heat sealability (heat adhesiveness), low hygroscopicity to suppress the penetration of the electrolyte solution, polyolefin resin that is not expanded or eroded by the electrolyte solution may be preferably used, More preferably unstretched polypropylene (cPP) can be used.

Preferably, the sealing part of the battery case may be formed on all four sides of the receiving part so that the internal electrode tabs can be inserted.

In one preferred embodiment, the coupling portion of the inner electrode tab may be located between the end of the diaphragm surplus portion and the outer peripheral surface end of the battery case sealing portion. That is, the coupling portion does not protrude out of the case by having a length shorter than the end portion of the outer peripheral surface of the case, and has a length longer than the edge portion of the diaphragm excess, thereby maintaining electrolyte sealing between unit cells by the diaphragm excess. The inner electrode tabs may be interconnected at a position between the end of the diaphragm excess and the end of the outer peripheral surface. As a result, the length of the inner electrode tab may be configured such that the inner electrode tabs overlap each other at the length between the end of the diaphragm excess portion and the end of the outer peripheral surface.

Although the widths of the sealing parts may all be the same, in one preferred embodiment for preventing the sealing force of the sealing part from being lowered due to the location of the inner electrode tabs, a surface into which the inner electrode tabs are inserted among the four surface sealing parts. The width of the sealing portion of may be greater than the width of the sealing portion of the remaining surface. In addition, in order to increase the bonding force of the sealing portion, an adhesive insulating tape may be further attached to the contact surface of the inner electrode tab with the sealing portion.

In the present invention, the excess portion for the diaphragm extends from one side of the first member or the second member of the battery case, and preferably, the electrode tab does not protrude. It may be a structure extending from one long side.

As such, the excess portion for the diaphragm extending from the battery case may be integrally formed at the time of manufacturing the battery case, or may be formed by a method such as combining a separate diaphragm excess to the manufactured battery case. More preferred is the structure.

In one preferred embodiment, the battery case is made of a laminate sheet comprising a metal layer and a resin layer, the excess portion for the diaphragm may be made of the same laminate sheet. Since the excess portion for diaphragm can be formed integrally during the manufacture of the battery case, there is an advantage that the manufacturing process is simple.

The excess material for the diaphragm is not particularly limited as long as it can play a role of physically separating the unit cells and the electrolyte from each other, and has electrolyte resistance and prevents the movement of lithium ions.

Examples of such diaphragm surpluses include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyethylene-terephthalate (PET), polymethacrylate (PMMA), and polyacrylonitrile (PAN). It is made of one or two or more materials selected from the group consisting of, and preferably may be a polyolefin-based polymer sheet such as PE, PP. It is preferable to use a material having the same or similar physical properties as the material of the internal resin layer, and more preferably, a polymer sheet of unstretched polypropylene (cPP) for excellent bonding with the internal resin layer of the battery case.

The area of the diaphragm excess may be configured to be larger than the cross-sectional area of the housing so that the area of the diaphragm may be located on the sealing portion formed on the outer peripheral surface of the housing. In addition, the upper case and the lower case may be of a size smaller than the cross-sectional area of the outer peripheral surface of the case in order to at least partially directly heat-sealed to exert high bonding force and minimize waste of unnecessary material.

When the thickness of the diaphragm surplus is too thick, thermal conductivity during thermal fusion decreases, and the distance between the upper case and the lower case is widened, so that bonding by thermal fusion is not easy, and the thickness of the battery is increased. have. On the contrary, when too thin, it may be difficult to sufficiently achieve electrolyte sealing between unit cells due to deformation of the diaphragm surplus itself during charging and discharging. In consideration of this point, the thickness of the surplus portion for the diaphragm may be preferably 10 μm to 500 μm.

On the other hand, since the external electrode tab is coupled to the electrode lead can be connected to the external input and output terminals, the sealing member in the form of a film between the electrode lead to increase the sealing property in consideration of the thickness of the electrode lead and heterogeneity with the case material It can heat bond in the state interposed.

The unit cell is composed of an electrode assembly having a stack structure of an anode, a separator, and a cathode, and the type of the electrode assembly is not particularly limited, and may be selected from a stack type, a stack type, a folding type, or a folding type electrode assembly. . In the case of using the folding electrode assembly, the cross-sectional shape may be substantially rectangular by pressing.

In particular, the secondary battery according to the present invention may be preferably applied to a pouch type secondary battery in which an electrode assembly is embedded in a laminate sheet including a metal layer and a resin layer, and in one specific example, an aluminum laminate sheet.

In the present invention, the secondary battery is preferably a lithium secondary battery having a high energy density, a discharge voltage, and an output stability, and a lithium ion polymer secondary battery is more preferable. Since other components and a manufacturing method of the lithium secondary battery are well known in the art, detailed description thereof will be omitted herein.

The present invention also provides a high-power large-capacity battery module using such a secondary battery as a unit.

The medium-large battery module according to the present invention can be assembled by treating two unit cells as one battery cell, and since their coupling structure is compact, the overall assembly process of the battery module can be simplified and manufactured in a more compact structure. Can be. In addition, there is an advantage that the risk of occurrence of a short circuit due to complicated wiring or the like can be reduced by easy BMS management.

The present invention also provides a method of manufacturing the secondary battery comprising the following steps (i) to (iv).

(i) Two internal electrode tabs face each other in a battery case in which the first member and the second member each having an accommodating portion are formed in one piece or a separate type, and the diaphragm surplus extends from one side of the first member. Mounting unit cells;

(ii) bending the excess portion for diaphragm in the unit cell direction and placing it on the unit cell mounted in the step (i);

(iii) combining the sealing portion of the first member into which the diaphragm surplus is inserted and the diaphragm surplus in one step except for one side;

(iv) positioning the first member on the second member;

(v) combining the sealing part of the first member and the sealing part of the second member into which the diaphragm surplus is inserted in step (iv), except for the same side as the unbonded side in step (iii); And

(vi) injecting an electrolyte through the unbound portion and fully coupling the outer circumferential surface sealing portion of the case.

The manufacturing method according to the present invention can be manufactured according to a known secondary battery manufacturing method without having to go through a separate complicated process, and can be manufactured by a continuous process, so the process efficiency is very excellent.

Specifically, in the step (i), the unit cell is mounted in the housing, and when the unit cells are mounted in the integrated battery case, the inner electrode tabs facing each other are positioned at a side shared by the first member and the second member. It is preferable. In the step (ii), the upper portion of the unit cell is covered by bending the excess portion for the diaphragm formed continuously in the battery case in the direction of the storage part. Then, in the step (iii), the excess portion for the diaphragm and the outer peripheral surface sealing portion of the first member is coupled, at this time except for one side. Since this is to facilitate the injection of the electrolyte afterwards, it is preferable that the unbound side is not a side in which the excess portion for diaphragm of the first member is extended, and the side shared by the first member and the second member in the integrated battery case. Also excluded. The above-described diaphragm surplus portion and the sealing portion can be joined by a method such as heat fusion or an adhesive, as described above.

In the state where the unit cell mounted on the first member is combined with the diaphragm surplus, it is positioned in the second member direction in the step (iv). In the case of the integrated battery case, the first member can be positioned by bending the first member in the direction of the second member. Then, in step (v), the sealing portion of the first member and the sealing portion of the second member are engaged. However, also in this case, as in the first member, except for the side and the corresponding side that is not bonded for the injection of the electrolyte is bonded. After the electrolyte is injected through the unbound side, the first member and the second member are completely coupled to each other.

In one preferred embodiment, at any point before or after the steps (i) to (iv), the step of welding the internal electrode tab of the unit cell by bonding. That is, the coupling of the internal electrode tab is not particularly limited as long as it is a time before the first member and the second member are joined, and more preferably, may be performed before or after the step (i). For example, two unit cells having internal electrode tabs coupled to each other may be mounted in the accommodating unit, or the unit electrode may be connected to the internal electrode tabs after the unit cells are mounted in the accommodating unit.

In the following, secondary batteries according to an embodiment of the present invention will be described with reference to the drawings, but this is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

2 schematically illustrates a unit cell inserted into a secondary battery according to an exemplary embodiment of the present invention.

2, external electrode tabs 310 and 320 and internal electrode tabs 410 and 420 are formed in each unit cell 210 and 220, respectively. The inner electrode tabs 410 and 420 are positioned at the lower center of the unit cell, and the outer electrode tab 310 of the first unit cell 210 is formed at the upper left side of the unit cell, and the second unit cell 220 The external electrode tab 320 is formed at the upper right side of the unit cell. Insulating tapes 311 and 321 are attached to the external electrode tabs 310 and 320, respectively.

FIG. 3 schematically illustrates an assembly process of a secondary battery including two unit cells according to FIG. 2 in an integrated case according to a first embodiment of the present invention, and FIG. 4 illustrates a second embodiment of the present invention. A detachable case is shown schematically.

Referring to these drawings, the battery case of FIG. 3 is continuously formed on one surface of the first member 610 and the first member 610 in which the accommodating part 611 is formed, and the accommodating part 621 is formed. It consists of the bending-shaped 2nd member 620 and the diaphragm excess part 500 formed continuously in the long side of the 1st member 610. As shown in FIG. The diaphragm surplus portion 500 has a length shorter than the length of the long side of the first member 610 and longer than the length of the storage portion.

The manufacturing method of the secondary battery may be performed by the following process, for example.

First, the internal electrode tabs 410 of the first unit cell 210 and the second unit cell 220 are joined to each other by welding, and then the accommodating part 611 and the second member 620 of the first member 610 are combined. The first unit cell 210 and the second unit cell 220 are mounted in the accommodating part 621. After the diaphragm excess portion 500 is bent in the direction of the storage portion 611 of the first member 610, and the other side except for one side is heat-sealed, the first member 610 is second member 620. Bending in the direction. Then, the three sides except for the side corresponding to the unbound side in the first member 610 are combined, and the electrolyte is injected through the unbound side and then heat-sealed. In some cases, the first unit cell 210 is mounted on the accommodating part 611 of the first member 610, the excess portion 500 for the diaphragm is bent and placed on the first unit cell 210. The upper case 620 may be bent after inserting the second unit cell 220 into the accommodating portion of the second member 620, welding the internal electrode tab of the first unit cell 210.

The internal electrode tab of the first unit cell 210 and the internal electrode tab of the second unit cell 220 are connected by a method such as welding to connect the first unit cell 210 and the second unit cell 220 in series. . The timing at which these internal electrode tabs are connected to each other is not particularly limited, and may be, for example, before heat fusion of the first and second members 620 and 610.

Meanwhile, in the state where the first unit cell 210 and the second unit cell 220 are mounted in the accommodating parts 611 and 621, respectively, the internal electrode tab 410 and the second unit of the first unit cell 210 are provided. The inner electrode tab 420 of the cell 220 is positioned at a portion 650 where the first member 610 and the second member 620 are in contact with each other. Therefore, the first member 610 and the second member 620 are not exposed to the outside in a combined state. In addition, the external electrode tab 310 of the first unit cell 210 and the external electrode tab 320 of the second unit cell 220 respectively protrude to the outside of the upper end of the case. At this time, the insulating tape attached to the external electrode tabs 310 and 320 is positioned on the outer circumferential surface sealing part 630 of the case.

Meanwhile, in the battery case of FIG. 4, except that the first member 610 ′ in which the accommodating part 611 ′ is formed and the second member 620 ′ in which the accommodating part 621 ′ is formed are separated from each other. 3 is the same as the battery case of FIG.

FIG. 5 schematically illustrates a structure in which unit cells are connected in a secondary battery according to an exemplary embodiment of the present invention, and FIG. 6 schematically illustrates a front view of a secondary battery having a structure according to FIG. 5. 7 and 8 schematically show cross-sectional views of the straight line AA and the straight line BB in FIG. 6, respectively. For reference, the battery case is omitted in FIG.

First, referring to FIG. 5, the secondary battery 100 is composed of two unit cells 210 and 220. External electrode tabs 310 and 320 protruding from the upper end 201 are formed in the first unit cell 210 and the second unit cell 220, respectively, and internal electrode tabs 410 protruding from the lower end 202 are formed. 420 is formed. The inner electrode tabs 410 and 420 of the first unit cell 210 and the second unit cell 220 have opposite polarities, and the outer electrode tab 300 and the inner electrode tabs 410 and 420 in each unit cell. Have opposite polarities. Therefore, the two unit cells 210 and 220 are connected in series by interconnecting the internal electrode tabs 410 and 420. A diaphragm surplus portion 500 is inserted between the first unit cell 210 and the second unit cell 220 to physically separate the electrolyte solutions of the unit cells 210 and 220 from each other.

In FIG. 6, the width of the sealing part 630 may be sufficient to exert the coupling force between the first member and the second member of the battery case, but the width L of the portion where the internal electrode tab is positioned to increase the coupling force. It may be preferable that is larger than the width l of the remaining sealing portion. The size of the diaphragm surplus 500 is larger than the cross-sectional area of the housing so as to seal the housing, and smaller than the cross-sectional area of the entire case to ensure the bonding force in the sealing unit 630. Therefore, the outer periphery of the diaphragm surplus portion 500 is located approximately in the middle of the sealing portion 630. However, one side of the diaphragm excess part 500 is connected with the 1st member or the 2nd member.

Referring to FIG. 7, which is a side cross-sectional view of a straight line AA, and FIG. 8, which is a side cross-sectional view of a straight line BB, a battery case includes an outer resin layer 601, a metal barrier layer 602, and an inner resin layer 603, the innermost layer. It consists of a laminate sheet having a laminated structure of. The diaphragm excess part 500 is inserted in a part of the sealing part which is a contact surface of a 1st member and a 2nd member, and the facing internal resin layer 603 is heat-sealed by heating / pressurization. The internal electrode tabs 310 and 320 are separated from each other at the portion where the diaphragm surplus 500 is inserted, but are coupled to each other at an end of the diaphragm surplus 500.

For convenience of explanation, in FIG. 7 and FIG. 8, a corresponding portion is expressed as a state before thermal fusion. However, when thermal fusion is actually performed, between the inner resin layers 603 and the diaphragm surplus 500 of the upper and lower cases, It is thermally fused so that there are no spaced apart parts.

In addition, although the diaphragm surplus portion 500 is represented in a single layer structure in FIGS. 7 and 8 for convenience of description, when the diaphragm surplus portion 500 is made of the same material as the first member, the diaphragm excess portion 500 may have the same multilayer structure. Of course.

Although described above with reference to the drawings according to an embodiment of the present invention, those of ordinary skill in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

As described above, in the secondary battery according to the present invention, since two unit cells physically separated by a diaphragm are connected in series, a secondary battery having high voltage and high output characteristics may be manufactured, and BMS management may be performed. It has the advantage of being easy, and can be manufactured by a low cost and a simple assembly process has the advantage of high production efficiency.

1 is a perspective view of a typical representative pouch type battery;

2 is a schematic diagram of unit cells inserted into a secondary battery according to one embodiment of the present invention;

3 is a schematic diagram of a process of manufacturing a secondary battery with an integrated battery case according to a first embodiment of the present invention;

4 is a schematic view of a removable battery case according to a second embodiment of the present invention;

5 is a schematic diagram of a structure in which unit cells are connected in a secondary battery according to one embodiment of the present invention;

6 is a front view of a secondary battery having a structure according to FIG. 5;

7 and 8 are cross-sectional views of the straight line A-A and the straight line B-B in FIG.

Claims (17)

A secondary battery having a structure in which two unit cells are mounted in a case accommodating part and heat sealed by sealing the outer circumferential surface of the battery case. Each of the unit cells has a positive electrode tab and a negative electrode tab formed at opposite positions, and one electrode tab ('external electrode tab') of the unit cells protrudes out of the case and the opposite electrode tab ('inner electrode tab'). ) Are interconnected by a series connection method, the battery case is a first member and a second member each of which is formed in the receiving unit is formed of an integral or separate type, the first member so as to physically separate the electrolyte of the unit cells Or a diaphragm surplus extending from one side of the second member, wherein the diaphragm surplus is positioned between the unit cells respectively mounted to the case accommodating portions, and the inner electrode tab connection unit is a case sealing unit. Secondary battery, characterized in that consisting of a heat-sealed structure together. The secondary battery of claim 1, wherein internal electrode tabs of adjacent unit cells have opposite polarities. The secondary battery of claim 1, wherein the external electrode tabs are formed to protrude to an upper end of the case. The secondary battery of claim 1, wherein the inner electrode tabs protrude from adjacent unit cells in the same direction and position. The method of claim 1, wherein the inner electrode tabs are all formed at the center of the upper or lower end of the unit cell, the outer electrode tabs are formed on the upper end of the unit cell, the opposite electrode tabs of the upper left and right of the case Secondary batteries, characterized in that each is formed. The secondary battery of claim 1, wherein the inner electrode tab is positioned between an end portion of the excess portion for diaphragm and an outer peripheral surface end portion of the battery case sealing portion. The secondary battery according to claim 1, wherein the battery case is made of a laminate sheet including a metal layer and a resin layer, and the surplus portion for the diaphragm is made of the same laminate sheet. The secondary battery according to claim 1, wherein the diaphragm excess extends from one of the long sides of the first member or the second member. The secondary battery according to claim 1, wherein an area of the diaphragm surplus portion is larger than a cross-sectional area of the accommodating portion and smaller than an entire cross-sectional area including the sealing portion. The secondary battery of claim 1, wherein the thickness of the diaphragm excess is 10 μm to 500 μm. According to claim 1, wherein the case is formed on all four sides of the sealing portion, the inner electrode tab is inserted into any one of the four surface, the width of the sealing portion of the surface in which the inner electrode tab is inserted the sealing portion of the remaining surface Secondary battery, characterized in that larger than the width. The secondary battery of claim 1, wherein the internal electrode tabs are connected by series welding by soldering or soldering to each other. The secondary battery of claim 1, wherein the unit cell is one selected from the group consisting of a stack type, a stack / fold type, and a folding type electrode assembly. The secondary battery of claim 1, wherein the battery is a lithium secondary battery. A high output large-capacity battery module using the secondary battery according to any one of claims 1 to 15 as a unit. (i) Two internal electrode tabs face each other in a battery case in which the first member and the second member each having an accommodating portion are formed in one piece or a separate type, and the diaphragm surplus extends from one side of the first member. Mounting unit cells; (ii) bending the excess portion for diaphragm in the unit cell direction and placing it on the unit cell mounted in the step (i); (iii) combining the sealing portion of the first member into which the diaphragm surplus is inserted and the diaphragm surplus in one step except for one side; (iv) positioning the first member on the second member; And (v) combining the sealing part of the first member and the sealing part of the second member into which the diaphragm surplus is inserted in step (iv), except for the same side as the unbonded side in step (iii); (vi) injecting an electrolyte through an unbonded site and fully engaging the outer circumferential sealing of the case; Method for manufacturing a secondary battery according to claim 1, characterized in that it comprises a. The method according to claim 16, further comprising the step of coupling the inner electrode tabs of the unit cells at any point before and after the steps (i) to (iv).

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