KR102048755B1 - Electrode Assembly Comprising Unit cell Having Separator Sheet-Folded Structure - Google Patents

Abstract

The present invention includes two or more unit cells including a positive electrode, a negative electrode, and a first separator sheet interposed between the positive electrode and the negative electrode on which the active material is applied on a current collector; And a second separator sheet surrounding the outer surface of the unit cell stack in a state in which the unit cells are stacked, wherein the unit cells include one or more anodes and one or more cathodes sequentially by the first separator sheet. It provides an electrode assembly, characterized in that consisting of a wound structure.

Description

Electrode assembly including unit cell of structure wound by separator sheet {Electrode Assembly Comprising Unit cell Having Separator Sheet-Folded Structure}

The present invention relates to an electrode assembly including a unit cell of a structure wound by a separator sheet.

Recently, the increase in the price of energy sources due to the depletion of fossil fuels, interest in environmental pollution is amplified, and the demand for environmentally friendly alternative energy sources has become an indispensable factor for future life. Accordingly, researches on various power production technologies such as nuclear power, solar energy, wind power, tidal power, etc. continue, and power storage devices for more efficient use of the generated energy are also drawing attention.

In particular, as technology development and demand for mobile devices increase, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries that can meet various needs have been conducted.

Representatively, there is a high demand for square and pouch type secondary batteries that can be applied to products such as mobile phones with a thin thickness in terms of shape of batteries, and high energy density, discharge voltage, and output stability in terms of materials. Demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries is high.

In addition, the secondary battery is a cylindrical battery and a rectangular battery in which the electrode assembly is embedded in a cylindrical or rectangular metal can according to the shape of the battery case, and a pouch type battery in which the electrode assembly is embedded in a pouch type case of an aluminum laminate sheet. Are classified.

In particular, recently, a pouch-type battery having a stacked or stacked / folding electrode assembly in a pouch-type battery case of an aluminum laminate sheet has attracted much attention due to its low manufacturing cost, small weight, and easy shape deformation. And its usage is gradually increasing.

In addition, secondary batteries are classified according to the structure of an electrode assembly having a structure in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are formed. Jelly-roll type electrode assembly having a structure wound in a state where a separator is interposed, a stack type electrode assembly in which a plurality of anodes and cathodes cut in units of a predetermined size are sequentially stacked with a separator therebetween In recent years, in order to solve the problems of the jelly-roll type electrode assembly and the stacked electrode assembly, an electrode assembly having an advanced structure which is a mixed form of the jelly-roll type and the stack type, has a predetermined unit. Stacked / foldable electrode having a structure in which positive and negative electrodes are sequentially wound in a state in which unit cells stacked on a separator film are stacked with a separator interposed therebetween Developed body lip.

FIG. 1 is a schematic diagram schematically illustrating an arrangement structure of unit cells before forming a conventional stack / foldable electrode assembly.

Referring to FIG. 1, three unit cells 110, 120, and 130 are arranged on one surface of the separator sheet 104 so as to be spaced apart from each other at predetermined intervals 151 and 152.

The first unit cell 110 has a structure in which one anode 101 and one cathode 102 are stacked with a separator 103 interposed therebetween, and the second unit cell 120 has two cathodes 102. ) And one anode 101 are stacked with the separator 103 interposed therebetween, and the outermost electrodes are formed to be the cathode 102. The third unit cell 130 includes two anodes 101 and 1. Two cathodes 102 are stacked with the separator 103 interposed therebetween, and the outermost electrodes are formed to be the anode 101.

The first unit cell 110 is spaced 151 from the second unit cell at predetermined intervals, and when the first unit cell 110 is wound, the first unit cell 110 and the second unit cell 120 The separator sheet 104 may be positioned between the layers.

The second unit cell 120 is also spaced apart from the third unit cell 130 at a predetermined interval.

The separator 103 interposed between the positive electrode 101 and the negative electrode 102 may prevent a short circuit due to direct contact between the positive electrode 101 and the negative electrode 102 constituting each unit cell 110, 120, 130. Thus, it is configured to have a relatively large area compared to the positive electrode 101 and the negative electrode 102.

Accordingly, the separator 103 interposed between the anode 101 and the cathode 102 protrudes in the lateral direction relative to the anode 101 and the cathode 102, and thus, the second unit cell 120 adjacent to each other. ) And the third unit cell 130 are spaced 152 in consideration of the length of the protruding separator 103, so that the third unit cell 130 is spaced 152 at a wider interval than a substantially necessary space.

However, the portion of the separator sheet 104 that is excessively spaced 152 between the second unit cell 120 and the third unit cell 130 is bent inwardly between the unit cells 120 and 130. As the deformations 104a and 104b occur, the structural stability of the electrode assembly may be lowered.

In addition, the portions 151 and 152 of the separator sheet 104 are overlapped in the lateral direction of the unit cells 110, 120, and 130 as the unit cells 110, 120, and 130 are wound. As the quantity of the unit cells 110, 120, and 130 constituting the electrode assembly increases, the battery cells occupy too much space in the battery cell, thereby reducing the overall capacity of the battery cell, There is a problem that acts as a factor to increase the size.

Therefore, there is a high need for a technology that can fundamentally solve these problems.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After extensive research and various experiments, the inventors of the present application configure the unit cells in a structure in which the anode and the cathode are sequentially wound by the separator sheet, as described later, to form the anode and the electrode assembly. When the negative electrode is disposed on the separator sheet, it is not necessary to consider the length of the separator protruding between the positive electrode and the negative electrode in order to prevent the short circuit of the positive electrode and the negative electrode, so that the gap on the separator sheet can be minimized. By preventing the shape deformation of the separator sheet that may occur between the configuration of the electrode assembly, to improve the structural stability of the electrode assembly, and to minimize the space required by the overlap of the separator sheet, to maximize the capacity of the electrode assembly compared to the same size, It was confirmed that the size of the electrode assembly can be minimized compared to the same capacity. Leading to the completion of the person.

Electrode assembly according to the present invention for achieving this object,

Two or more unit cells including a positive electrode, a negative electrode, and a first separator sheet interposed between the positive electrode and the negative electrode on which an active material is coated on a current collector; And

A second separator sheet surrounding the outer surface of the unit cell stack in the state in which the unit cells are stacked;

It contains,

The unit cells may have a structure in which one or more anodes and one or more cathodes are sequentially wound by the first separator sheet.

Therefore, each of the unit cells has a structure in which the positive electrode and the negative electrode are sequentially wound by the separator sheet, so that when the positive electrode and the negative electrode constituting the electrode assembly are disposed on the separator sheet, between the positive electrode and the negative electrode, the positive electrode Since it is not necessary to consider the length of the protruding membrane in order to prevent the short of the cathode and the cathode, it is possible to minimize the gap on the separator sheet, thereby preventing the deformation of the separator sheet that may occur between the configuration of the electrode assembly, thereby preventing the electrode assembly By improving the structural stability and minimizing the space required by the overlap of the separator sheet, it is possible to maximize the capacity of the electrode assembly compared to the same size, or to minimize the size of the electrode assembly compared to the same capacity.

In one specific example, the total quantity of the positive electrode and the negative electrode included in one unit cell among the unit cells may be two to six.

As described above, the unit cell has a structure in which one or more anodes and one or more cathodes are sequentially wound by the first separator sheet so as to independently exhibit electrical characteristics. The total quantity of the positive electrode and the negative electrode is at least two or more, and if the total quantity of the positive electrode and the negative electrode included in the one unit cell exceeds six, the separation between the positive electrode and the negative electrode on the first separator sheet Too much space may reduce the overall structural stability, or the first separator sheet may overlap too much in the lateral direction during the winding of the unit cell, and thus may not exhibit the desired effect.

In addition, the quantity of the positive electrode and the negative electrode included in one unit cell of the unit cells may be the same or different from each other.

In other words, each of the positive and negative electrodes included in the one unit cell is composed of at least one, each of the positive or negative electrode within the range that the total quantity of the positive electrode and the negative electrode does not exceed 6, Can be.

In one specific example, the unit cells may be a structure including two or more types of unit cells having a different stacked structure of a positive electrode and a negative electrode.

More specifically, the unit cells include unit cells stacked in the order of positive electrode, negative electrode, positive electrode and unit cells stacked in the order of negative electrode, positive electrode, and negative electrode, or stacked in the order of positive electrode, negative electrode, positive electrode, negative electrode, and positive electrode. It may be a structure including a unit cell and a unit cell stacked in the order of the negative electrode, the positive electrode, the negative electrode.

That is, the unit cells may have a structure including at least two or more types of unit cells. In detail, the different types of unit cells may have a positive electrode and a negative electrode laminated structure different from each other, or may be included in one unit cell. The quantity of the and the cathode may be different from each other.

In another specific example, the unit cells may be formed of the same structure of the stacked structure of the positive electrode and the negative electrode.

More specifically, the unit cells are all unit cells stacked in the order of the positive electrode, the negative electrode, the positive electrode, and the negative electrode, and the stacked structure of the positive electrode and the negative electrode and the quantity of the positive electrode and the negative electrode included in one unit cell are all the same structure. In this case, one of the unit cells may have a structure in which the unit cells stacked adjacent to each other and the outermost electrodes having different polarities are stacked to face each other.

Therefore, the electrode assembly according to the present invention may be configured by applying a combination of unit cells including various stacking structures and quantities of the positive electrode and the negative electrode, depending on the desired output and capacity characteristics, or the overall size.

Hereinafter, a detailed structure of the unit cells will be described in more detail.

In one specific example, at least one unit cell of the unit cells is more positive than the negative electrode,

The cathodes are arranged on the first side at the start of winding of the first separator sheet, and the two anodes are sequentially arranged in the state of being spaced apart by the width of the electrode, and the cathodes are arranged on the first side at the end of the winding. In a state where the anode is arranged on the opposing second surface, it may have a wound structure.

That is, the unit cells manufactured according to the above structure are alternately stacked with the first separator sheet having two cathodes and three anodes continuously connected therebetween, and the outermost electrodes may be configured as anodes.

In another specific example, at least one unit cell of the unit cells has a greater number of cathodes than the anode,

The anodes are arranged on the first side at the start of winding of the first separator sheet and two cathodes are sequentially arranged with the electrodes spaced apart, and the anodes are arranged on the first side at the end of the winding and In a state in which the cathodes are arranged on the opposing second surface, it may have a wound structure.

That is, the unit cells manufactured according to the above structure are alternately stacked with the first separator sheet having two anodes and three cathodes continuously connected therebetween, and the outermost electrodes may be configured as cathodes.

Accordingly, the unit cells of the above structure may be formed by stacking the unit cells including the outermost electrodes as the anodes and the unit cells including the outermost electrodes as the cathodes adjacent to each other, thereby forming an electrode assembly according to the present invention.

Meanwhile, the unit cells may be a structure in which unit cells having a structure in which both outermost electrodes are surrounded by the first separator sheet and unit cells having a structure in which both outermost electrodes are exposed to the outside are alternately stacked. have.

More specifically, the unit cells are composed of two types of unit cells, one of which is the first unit cell may have a structure in which the outermost electrodes of both sides are surrounded by the first separator sheet, the rest One type of second unit cell may have a structure in which the outermost electrodes on both sides are exposed to the outside.

In this case, the unit cells are alternately stacked so that the first separator sheet positioned at the outermost side of the first unit cell is positioned between the outermost electrode of the first unit cell and the outermost electrode of the second unit cell. Can be.

However, the structure of the unit cell constituting the electrode assembly according to the present invention is not limited thereto, and in the unit cells, one electrode of the outermost electrodes on both sides is surrounded by the first separator sheet, and is opposed thereto. It may be made of a structure in which the other electrode is exposed to the outside.

In other words, all the unit cells constituting the electrode assembly may have a structure in which only one electrode of the outermost electrodes on both sides is surrounded by the first separator sheet.

In this case, the unit cells may have a structure in which the outermost electrode of one unit cell wrapped by the first separator sheet faces the outermost electrode exposed to the outside of another adjacent unit cell.

Therefore, since only one layer of the first separator sheet is interposed between the unit cells, the first separator sheet does not overlap, and thus, an increase in the thickness of the electrode assembly and a decrease in electrical performance can be effectively prevented. .

In addition, the unit cells may have a structure including two or more types of unit cells having different output and capacitance characteristics of the positive electrode and the negative electrode.

More specifically, recently, secondary batteries have been proposed as solutions for air pollution of conventional gasoline and diesel vehicles using fossil fuels, including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-ins. It is also attracting attention as a power source for hybrid electric vehicles (Plug-In HEV).

On the other hand, in order to use the secondary battery as a power source of a device or a system requiring a complex driving state such as EV and HEV, a complex output and capacity characteristic corresponding to the driving state is required. As a hybrid type battery pack having a structure in which a high output & low capacity secondary battery and a low output & high capacity secondary battery are included as unit cells, and the plurality of unit cells are connected in series and / or in parallel. It is used.

Accordingly, the electrode assembly according to the present invention includes two or more types of unit cells having different output and capacitance characteristics of the positive electrode and the negative electrode, thereby exerting the above effect, and thus a power source of a device or system requiring the complex driving state. It can be applied effectively as.

In this case, the unit cells may exhibit different output and capacitive characteristics, respectively, by various constituent conditions. In detail, the unit cells having different output and capacitive characteristics may have different kinds of active materials of positive and negative electrodes, coating methods, and porosity. The coating amount, or the mixing ratio may be different from each other.

On the other hand, the outermost portion of the unit cell stack may have a structure in which the upper separator and the lower separator of the second separator sheet are located.

More specifically, the unit cell stack has an outer surface wrapped by a second separator sheet to form a final electrode assembly. In this case, the inner surface of the second separator sheet may be formed at the top and bottom of the unit cell stack. The upper separator and the lower separator are positioned, respectively, and thus, the upper separator and the lower separator are respectively positioned at both outermost sides of the unit cell stack, and are enclosed together with the unit cell stack by the second separator sheet. Thus, the electrode assembly can be configured.

Accordingly, the top separator and the bottom separator may eliminate or minimize damage and internal short circuits of the electrode assembly, which may occur due to the impact or penetration of an external foreign material such as metal, thereby reinforcing the structural stability of the electrode assembly.

In one specific example, the electrode positioned at the outermost portion of the unit cell stack may have a structure in which an active material is coated only on one surface of the current collector facing the electrode of opposite polarity.

More specifically, only one surface facing the electrode having the opposite polarity and one surface facing the electrode having the opposite polarity, based on the current collector of the electrode located at the outermost portion of the unit cell stack, are opposite to the electrode. Participate

Therefore, the electrode assembly according to the present invention has an active material coated on only one surface of the electrode cell facing the electrode of the opposite polarity to participate in the reaction based on the current collector of the electrode located at the outermost of the unit cell stack, the electrode of the same capacity The thickness can be minimized compared to the assembly, or the capacity can be maximized compared to the electrode assembly of the same thickness.

In addition, as long as the unit cells are capable of exhibiting the electrical performance of the desired electrode assembly, the total number of the unit cells is not particularly limited, and in detail, the total number of the unit cells may be five to fifteen.

If the total number of unit cells is less than five, the total number of unit cells included in one electrode assembly may be too small to exhibit desired electrical performance, and if more than 15, The size of the electrode assembly is too large, there is a problem that can occur in the space of the device to which the electrode assembly is applied.

In addition, the present invention provides a battery cell comprising the electrode assembly, the battery cell is not particularly limited in its kind, but as a specific example, has the advantages of high energy density, discharge voltage, output stability, etc. It may be a lithium secondary battery such as a lithium ion battery, a lithium ion polymer battery and the like.

In general, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a lithium salt-containing nonaqueous electrolyte.

The positive electrode is prepared by, for example, applying a mixture of a positive electrode active material, a conductive material, and a binder to a positive electrode current collector, followed by drying, and optionally, a filler is further added to the mixture.

The positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O ₇ and the like; Ni-site type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3; Formula LiMn _2-x M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like, but are not limited to these.

The conductive material is typically added in an amount of 1 to 30 wt% based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists the bonding of the active material and the conductive material to the current collector, and is generally added in an amount of 1 to 30 wt% based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for inhibiting expansion of the positive electrode, and is not particularly limited as long as it is a fibrous material without causing chemical change in the battery. Examples of the filler include olefinic polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.

The negative electrode is manufactured by coating and drying a negative electrode active material on a negative electrode current collector, and optionally, the components as described above may optionally be further included.

As said negative electrode active material, For example, carbon, such as hardly graphitized carbon and graphite type carbon; Li _x Fe ₂ O ₃ (0 ≦ _x ≦ 1), Li _x WO ₂ (0 ≦ _x ≦ 1), Sn _x Me _1-x Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me' Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 <x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , and metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator and the separator are interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛. As such a separator, for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fibers or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

In addition, in one specific example, in order to improve safety of the battery of high energy density, the separator and / or the separator may be a safety-reinforcing separator (SRS) separator of organic / inorganic composite porous.

The SRS separator is manufactured using inorganic particles and a binder polymer as an active layer component on a polyolefin-based separator substrate, wherein the pore structure included in the separator substrate itself and the interstitial volume between the inorganic particles as the active layer component are used. It has a uniform pore structure formed.

In the case of using the organic / inorganic composite porous membrane, an increase in battery thickness due to swelling during the formation process can be suppressed as compared with a conventional separator. In the case of using a gelable polymer when impregnating a liquid electrolyte, it may be used simultaneously as an electrolyte.

In addition, the organic / inorganic composite porous separator may exhibit excellent adhesion characteristics by controlling the content of the inorganic particles and the binder polymer, which are the active layer components in the separator, and thus may have an easy battery assembly process.

The inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in the present invention are not particularly limited as long as the oxidation and / or reduction reactions do not occur in the operating voltage range of the battery to be applied (for example, 0 to 5 V on the basis of Li / Li +). In particular, in the case of using the inorganic particles having the ion transfer ability, since the ion conductivity in the electrochemical device can be improved to improve the performance, it is preferable that the ion conductivity is as high as possible. In addition, when the inorganic particles have a high density, it is not only difficult to disperse during coating, but also has a problem of weight increase during battery manufacturing, and therefore, it is preferable that the density is as small as possible. In addition, in the case of an inorganic material having a high dielectric constant, it is possible to contribute to an increase in the degree of dissociation of an electrolyte salt such as lithium salt in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution.

The lithium salt-containing nonaqueous electrolyte solution consists of a polar organic electrolyte solution and a lithium salt. As the electrolyte, a non-aqueous liquid electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, and the like are used.

As said non-aqueous liquid electrolyte solution, N-methyl- 2-pyrrolidinone, a propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma, for example Butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxorone, formamide, dimethylformamide, dioxolon , Acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbo Aprotic organic solvents such as nate derivatives, tetrahydrofuran derivatives, ethers, methyl pyroionate and ethyl propionate can be used.

Examples of the organic solid electrolyte include polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, polyedgetion lysine, polyester sulfides, polyvinyl alcohols, polyvinylidene fluorides, Polymers containing ionic dissociating groups and the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, sulfates and the like of Li, such as Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ , and the like, may be used.

The lithium salt is a good material to be dissolved in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., the non-aqueous electrolyte solution includes, for example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, and hexaphosphate triamide. Nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride, etc. It may be. In some cases, in order to impart nonflammability, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further included, and carbon dioxide gas may be further included to improve high temperature storage characteristics.

The present invention also provides a device including at least one of the battery cells, the device is specifically, mobile phones, tablet computers, notebook computers, power tools, wearable electronics, electric vehicles, hybrid electric vehicles, plug-in It may be any one selected from the group consisting of a hybrid electric vehicle, and a power storage device.

Since such devices or apparatuses are known in the art, detailed description thereof will be omitted herein.

As described above, in the electrode assembly according to the present invention, each of the unit cells has a structure in which the positive electrode and the negative electrode are sequentially wound by the separator sheet, thereby disposing the positive electrode and the negative electrode constituting the electrode assembly on the separator sheet. In this case, between the positive electrode and the negative electrode, it is not necessary to consider the length of the membrane protruding to prevent the short of the positive electrode and the negative electrode, it is possible to minimize the gap on the separator sheet, and thus, may occur between the composition of the electrode assembly By preventing the shape deformation of the separator sheet, the structural stability of the electrode assembly is improved, and the space required by the overlap of the separator sheets is minimized, thereby maximizing the capacity of the electrode assembly to the same size or increasing the size of the electrode assembly to the same capacity. There is an effect that can be minimized.

1 is a schematic diagram showing an arrangement structure of unit cells before constructing a conventional stack / foldable electrode assembly;
2 is a schematic view showing the structure of an electrode assembly according to an embodiment of the present invention;
FIG. 3 is a schematic diagram schematically illustrating an uppermost negative electrode of the first unit cell of FIG. 2 and a lowermost negative electrode of the fifth unit cell; FIG.
4 is a schematic diagram schematically showing a method of manufacturing a first unit cell of FIG. 2;
5 is a schematic diagram schematically showing various structures of a unit cell that can be applied to an electrode assembly according to another embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings according to embodiments of the present invention, but the scope of the present invention is not limited thereto.

2 is a schematic diagram schematically showing the structure of an electrode assembly according to an embodiment of the present invention.

Referring to FIG. 2, the electrode assembly 200 includes a total of five unit cells 210, 220, 230, 240, and 250 from the first unit cell 210 located at the top to the fifth unit cell 250. Doing.

Each unit cell 210, 220, 230, 240, 250 has a structure in which a cathode and an anode are sequentially wound by a first separator sheet.

The first unit cell 210, the third unit cell, and the fifth unit cell 250 have a structure in which two anodes and three cathodes are alternately stacked with the first separator sheet 201 interposed therebetween. The outermost electrode of is composed of a cathode.

The second unit cell and the fourth unit cell have a structure in which two cathodes and three anodes are alternately stacked with the first separator sheet 201 interposed therebetween, and the outermost electrodes on both sides are composed of anodes.

All of the unit cells 210, 220, 230, 240, and 250 have the total number of positive and negative electrodes five, all the same, and the lowest electrode among the outermost electrodes on both sides of the first separator sheet 201. It is enclosed by a structure, and has a structure in which the electrode on the opposite side is exposed to the outside.

Accordingly, the lowermost electrodes of the first unit cell 210, the second unit cell, the third unit cell, and the fourth unit cell wrapped by the first separator sheet 201 are exposed to the outside, respectively. The uppermost electrodes of the unit cell, the third unit cell, the fourth unit cell, and the fifth unit cell 250 face each other.

Therefore, a first separator sheet 201 of one layer is interposed between the outermost electrodes of the unit cells 210, 220, 230, 240, and 250.

An upper separator 261 and a lower separator 262 are positioned at the outermost sides of the unit cell stack 270 in which the unit cells 210, 220, 230, 240, and 250 are stacked, and one second separator sheet is provided. Reference numeral 202 surrounds the outer surface of the unit cell stack 270.

Accordingly, the upper separator 261 and the lower separator 262 may eliminate or minimize damage and internal short circuits of the electrode assembly 200, which may be caused by the impact or penetration of an external foreign material such as metal, thereby minimizing the electrode assembly ( 200) can enhance the structural stability.

FIG. 3 is a schematic diagram schematically illustrating the uppermost negative electrode of the first unit cell of FIG. 2 and the lowermost negative electrode of the fifth unit cell.

Referring to FIG. 3, the uppermost cathode 215 of the first unit cell 210 faces the anode 214 and the first separation membrane 201a therebetween, and the upper separation membrane 261 and the upper upper separation membrane 261 are formed. 2 is faced with the separation membrane 202 in between.

Since the uppermost negative electrode 215 of the first unit cell 210 faces only the lower surface facing the lower positive electrode 214 with the first separator 201a therebetween, based on the current collector 215a, the reaction participates in the reaction. The active material 215b is applied only to the bottom surface of the current collector 215a, and the active material is not applied to the top surface of the current collector 215a that does not participate in the reaction.

The lowermost negative electrode 253 of the fifth unit cell 250 faces the upper positive electrode 251 and the lower lower separator 262 with the first separator 201b and 201c interposed therebetween.

Since the lowermost negative electrode 253 of the fifth unit cell 250 is based on the current collector 253a, only the upper surface facing the upper positive electrode 251 with the first separator 201b therebetween participates in the reaction. The active material 253b is applied only to the upper surface of the current collector 253a, and the active material is not applied to the lower surface of the current collector 253a that does not participate in the reaction.

Therefore, it is possible to minimize the thickness compared to the electrode assembly of the same capacity, or to maximize the capacity compared to the electrode assembly of the same thickness.

FIG. 4 is a schematic diagram schematically showing a manufacturing method of the first unit cell of FIG. 2.

Referring to FIG. 4, the first unit cell 210 includes two anodes 211 and 214 and three cathodes 212, 213 and 215.

First, the first anode 211 is arranged on the upper surface at the start of the winding of the first separator sheet 201, and in the state spaced apart by a width corresponding to the width of the first anode 211, the second cathode 212 ) And the third cathode 213 are sequentially arranged, the fourth anode 214 is arranged on the upper surface at the end of the winding, and the fifth cathode 215 is arranged on the lower surface opposite thereto.

Since the first unit cell 210 does not include a separate separator interposed between the anodes 211 and 214 and the cathodes 212, 213 and 215 except the first separator sheet 201, the first unit cell 210 protrudes. Since it is not necessary to consider the length of the separation membrane, the separation distance on the first separation membrane sheet 201 can be minimized, and thus, the shape of the shape of the first separation membrane sheet 201 generated in the conventional stack / foldable electrode assembly is reduced. By preventing deformation, structural stability can be improved and the size of the electrode assembly can be minimized.

The first separator sheet 201 is sequentially wound from the first positive electrode 211 to the fourth positive electrode 214 and the fifth negative electrode 215 as a winding start portion.

In the first unit cell 210 manufactured according to the above method, the outermost electrodes on both sides of the first unit cell 210 include a third cathode 213 and a fifth cathode 215, and two first separator cells 201 are interposed therebetween. The anodes 211, 214 and the three cathodes 212, 213, 215 are stacked to face each other.

An outer surface of the third cathode 213 that faces the first anode 211 is surrounded by the first separator sheet 201, and an outer surface of the third cathode 215 that faces the fourth anode 214 to the outside. This is exposed to the outside.

5 is a schematic diagram schematically illustrating various structures of a unit cell that may be applied to an electrode assembly according to another exemplary embodiment of the present invention.

Referring to FIG. 5, each of the unit cells 510, 520, and 530 has a structure in which two anodes and two cathodes are sequentially wound by one first separator sheet 501a, 501b, and 501c. In a state where the positive electrode and the two negative electrodes are alternately stacked, first separator sheets 501a, 501b, and 501c are interposed between the positive electrode and the negative electrode.

Of the outermost electrodes of the unit cells 510, 520, 530, the uppermost electrode is composed of an anode, and the lowermost electrode is composed of a cathode.

In the first unit cell 510, both the uppermost positive electrode and the lowermost negative electrode are surrounded by the first separator sheet 501a.

In the second unit cell 520, only the lowermost negative electrode is surrounded by the first separator sheet 501b, and the uppermost positive electrode is exposed to the outside.

In the third unit cell 530, both the uppermost positive electrode and the lowermost negative electrode are exposed to the outside.

Therefore, the electrode assembly according to the present invention may be composed of a combination of the first unit cell and the third unit cell, or may be composed of a combination of only the second unit cell.

The structure of the electrode assembly and the unit cell according to the present invention is not limited thereto, and in detail, the unit cell may have various quantities and stacked structures of positive and negative electrodes and various structures within a range capable of exhibiting desired performance and effects. The separator sheet may be configured in various forms by the method of constructing the separator sheet, and the electrode assembly may be configured by the combination of the unit cells of the various forms.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (19)

At least two unit cells including at least one positive electrode and at least one negative electrode coated with an active material on a current collector, and a first separator sheet which sequentially wraps the positive electrode and the negative electrode in one direction; And
A second separator sheet in which the unit cells are stacked to form a unit cell stack and surrounding the outer surface of the entire unit cell stack;
It contains,
The total quantity of the positive electrode and the negative electrode included in one unit cell of the unit cells is 2 to 5,
At least one unit cell of the unit cells is more positive than the negative electrode,
The cathodes are arranged on the first side at the start of winding of the first separator sheet, and the two anodes are sequentially arranged in the state of being spaced apart by the width of the electrode, and the cathodes are arranged on the first side at the end of the winding. An electrode assembly comprising a wound structure in a state in which the anode is arranged on an opposing second surface. At least two unit cells including at least one positive electrode and at least one negative electrode coated with an active material on a current collector, and a first separator sheet which sequentially wraps the positive electrode and the negative electrode in one direction; And
A second separator sheet in which the unit cells are stacked to form a unit cell stack and surrounding the outer surface of the entire unit cell stack;
It contains,
The total quantity of the positive electrode and the negative electrode included in one unit cell of the unit cells is 2 to 5,
At least one unit cell of the unit cells has a greater number of cathodes than the anode,
The anodes are arranged on the first side at the start of winding of the first separator sheet and two cathodes are sequentially arranged with the electrodes spaced apart, and the anodes are arranged on the first side at the end of the winding and An electrode assembly comprising a wound structure in a state in which cathodes are arranged on opposing second surfaces. delete The electrode assembly of claim 1 or 2, wherein the unit cells include two or more types of unit cells having a different stacked structure of an anode and a cathode. delete delete delete The unit cell of claim 1 or 2, wherein the unit cells include a unit cell having a structure in which outermost electrodes on both sides are surrounded by a first separator sheet, and a unit cell having a structure in which both outermost electrodes are exposed to the outside. An electrode assembly, which is alternately stacked. According to claim 1 or claim 2, wherein the unit cells of the outermost electrodes on both sides of the structure is surrounded by the first separator sheet, the other electrode opposite to this structure is exposed to the outside Electrode assembly, characterized in that. 10. The method of claim 9, wherein the unit cells, the outermost electrode of one unit cell wrapped by the first separator sheet, the outermost electrode exposed to the outside of another adjacent unit cell, characterized in that Electrode assembly. The electrode assembly of claim 1 or 2, wherein the unit cells include two or more types of unit cells having different output and capacitance characteristics of the positive electrode and the negative electrode. The electrode assembly of claim 11, wherein the unit cells having different output and capacity characteristics are different from each other in the type, coating method, porosity, coating amount, or mixing ratio of the active materials of the positive electrode and the negative electrode. The electrode assembly according to claim 1 or 2, wherein an upper separator and a lower separator of the second separator sheet are positioned at the outermost sides of the unit cell stack. The electrode assembly according to claim 1 or 2, wherein the electrode located at the outermost part of the unit cell stack is coated with an active material only on one surface of the electrode facing the electrode of opposite polarity. The electrode assembly according to claim 1 or 2, wherein the total number of the unit cells is 5 to 15. A battery cell comprising the electrode assembly according to claim 1. The battery cell of claim 16, wherein the battery cell is a lithium secondary battery. A device comprising at least one battery cell according to claim 16. 19. The device of claim 18, wherein the device is any one selected from the group consisting of mobile phones, tablet computers, notebook computers, power tools, wearable electronics, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage devices. Device characterized in that.

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