KR20150084168A - Battery Cell Comprising Unit Cells Having Different Electrode Structures - Google Patents

Abstract

Stacked structure unit cells comprising a positive electrode and a negative electrode where an active material is spread on both surfaces of a current collector, and a separation film interposed between the positive electrode and the negative electrode; and an electrode assembly including a separation film consecutively winding the unit cells are installed in a storage unit of a battery case. In the electrode assembly, the innermost unit cells and the outermost unit cells respectively and independently have a stacked structure where electrodes having the different polarity are located on both ends of the unit cells. Unit cells except for the innermost unit cells and the outermost unit cells respectively and independently have a stacked structure where electrodes having the same polarity are located on both ends of the unit cells. In outermost electrodes of the electrode assembly, the active material is applied on only one surface of the current collector facing the electrode of the opposite polarity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell having a plurality of unit cells,

The present invention relates to a battery cell in which the electrode structure includes different unit cells.

In recent years, the demand for environmentally friendly alternative energy sources has become an indispensable factor for the future, as the increase in the price of energy sources due to depletion of fossil fuels and the interest in environmental pollution are amplified. Various researches on power generation technologies such as nuclear power, solar power, wind power, and tidal power have been continuing, and electric power storage devices for more efficient use of such generated energy have also been attracting much attention.

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

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

Also, the secondary battery is classified according to the structure of the electrode assembly having the positive electrode, the negative electrode, and the separator interposed between the positive electrode and the negative electrode. Typically, the long battery- A stacked (stacked) electrode assembly in which a plurality of positive electrodes and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, the jelly-roll type (wound type) electrode assembly having a structure in which a separator is interposed; In recent years, electrode assemblies having an advanced structure, such as the jelly-roll type and stack type mixed structure, have been proposed, in which unit cells having a predetermined unit of positive and negative electrodes stacked with a separator interposed therebetween are placed on a separation film A stack / folding type electrode assembly having a structure in which the electrodes are sequentially wound in a state where they are positioned has been developed.

FIG. 1 schematically illustrates a typical structure of a conventional stack / folding type electrode assembly.

1, the electrode assembly 100 includes unit cells 110, 130, 150 and 170 having a cathode-separator-anode-separator-cathode structure and unit cells 110, 120, 130, 140, 150, 160, 170, and 180 of the electrode assembly 100. The separation films 120, 140, 160, The first electrode 190 surrounds the respective side surfaces of the unit cells 110, 120, 130, 140, 150, 160, 170, and 180 where the electrode terminal is not formed.

The electrode assembly 100 is manufactured by arranging the unit cells 110, 120, 130, 140, 150, 160, 170, 180 on the separation film 190 and winding the separation film 190, The anode 181 at the lowermost end of the assembly 100 may be configured such that the active material is applied to only one side of the current collector in the inward direction of the electrode assembly 100 and the other side of the cathode current collector faces the separation film 190 .

Therefore, the electrode assembly 100 includes a total of eleven positive electrodes 102, twelve negative electrodes 103, one positive electrode section 181, sixteen separation membranes 101, and one separation film 190.

However, in the case of such a stack / folding type electrode assembly, each unit cell generally has a structure in which electrodes having the same polarity are located at both ends of the unit cell. In this case, , A large amount of current collector and an inactive material such as a separator in the same volume, the energy density is not satisfied in proportion to the thickness of the battery cell, and there is a limitation in improving the overall capacity of the battery cell .

Therefore, there is a high need for a technique capable of fundamentally solving such problems.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and have found that a unit cell having a structure in which electrodes of different polarities are located at both ends of a unit cell is disposed at one of outermost sides of the electrode assembly The number of separators and current collectors as a whole is reduced compared with a conventional battery cell having only a unit cell having a structure in which electrodes of the same polarity are located at both ends of the unit cell, It is possible to increase the application amount of the active material of the unit cell by the reduced thickness, and thus it is possible to manufacture a battery having a higher energy density, which has higher capacity characteristics than the same volume. Thus, the present invention has been accomplished.

According to an aspect of the present invention, there is provided a battery cell comprising:

An electrode assembly including a positive electrode and a negative electrode coated with an active material on a current collector, a unit cell having a laminated structure composed of a separator interposed between the positive and negative electrodes, and a separator film for continuously winding the unit cells, Is mounted on the receiving portion of the housing;

One of the outermost unit cells in the electrode assembly has a structure in which electrodes of different polarities are positioned at both ends of the unit cell, and the remaining unit cells are independently positioned at both ends of the unit cell, Lt; / RTI >

The outermost electrodes of the electrode assembly are characterized in that an active material is added only to one surface of the current collector facing the electrode of the opposite polarity.

That is, since the battery cell according to the present invention includes unit cells formed of a structure in which electrodes having different polarities are located at both ends of a unit cell, for example, a cathode-separator-cathode, Compared with a battery cell having unit cells having structures located at both ends of the cell, for example, a unit cell composed of a positive electrode-separator-negative electrode-separator-positive electrode or a negative electrode-separator-positive electrode- It is possible to increase the application amount of the active material of each unit cell by a reduced thickness when manufacturing battery cells of the same volume so that a battery of high energy density having higher capacity characteristics than the same volume can be manufactured .

In addition, since the unit cells having the structure in which the electrodes of different polarities are located at the both ends of the unit cell are arranged at the outermost positions, it is not necessary to separately manufacture the unit cells having the sectional coating structure, The number of unit cells required for manufacturing the battery cell is small and the processability is also excellent.

Hereinafter, the configuration of the battery cell according to the present invention will be described in more detail.

In one specific example, the electrodes other than the outermost electrodes may be coated with an active material on both sides of the collector in order to exhibit excellent capacity.

These electrodes are stacked to form a unit cell. Unit cells each having a structure in which electrodes having the same polarity are located at both ends of the unit cell include a unit cell having a structure in which the anode is located at both ends and a unit Cell. ≪ / RTI >

Therefore, the battery cell according to the present invention is a unit cell of an electrode assembly, in which a structure in which electrodes of different polarities are located at both ends of a unit cell, a structure in which an anode is located at both ends of the unit cell, And the like.

Meanwhile, the number of unit cells of the electrode assembly may be even or odd.

In one example, when the number of unit cells is an even number, the electrode assembly may include four or more unit cells, and the polarities of the outermost electrodes may be equal to each other.

For example, when the electrode assembly includes four unit cells, one of the outermost unit cells has a structure in which electrodes of different polarities are located at both ends of the unit cell, Unit cells have the structure in which electrodes having the same polarity are located at both ends of the unit cell.

The configuration and arrangement of the unit cells should be such that the positive electrode and the negative electrode alternate with each other in the wound state. If the number of unit cells in the arrangement for achieving such a structure is an even number, One is a structure in which electrodes of different polarities are located at both ends of a unit cell, and the other is a structure in which electrodes of the same polarity are located at both ends of the unit cell, and the outermost electrodes have the same polarity.

At this time, the polarities of the outermost electrodes may be both positive and negative, but are not limited to, and may be an anode.

In another example, when the number of unit cells is an odd number, the polarities of the outermost electrodes may be different from each other.

For example, when the electrode assembly includes five unit cells, in the electrode assembly including the four unit cells, one unit cell having electrodes of the same polarity positioned at both ends of the unit cell is added, The outermost electrodes will have different polarities when configured to alternate between the positive electrode and the negative electrode.

The electrode assembly according to the present invention may further include a first unit cell located at the innermost position of the n unit cells and an n-1 unit And the n < th > unit cell may be sequentially wound so as to be located at the outermost position.

In other words, since the electrode assembly is manufactured by sequentially winding from the first unit cell to the n-th unit cell in a state where n unit cells are arranged on the long length of the separation film, the first unit cell is positioned at the innermost side And the (n-1) th unit cell and the n < th > unit cell are located on the outermost side, respectively.

At this time, since the electrode assembly is wound around the first unit cell, the second unit cell and the third unit cell are positioned on both sides of the first unit cell, and therefore, the separator is positioned on both sides of the first unit cell A separation region corresponding to the size of the unit cell may be formed between the first unit cell and the second unit cell on the separation film before winding.

As described above, the n-th unit cell and the n-th unit cell located at the outermost side of the electrode assembly preferably have a configuration in which the outermost electrode is coated on one side from the viewpoint of safety, The active material may not be coated on one side of the current collector of the electrode facing the separation film.

Meanwhile, the battery cell according to the present invention is not limited as long as one of the unit cells positioned at the outermost portion has a structure in which electrodes having different polarities are located at both ends of the unit cell, and specifically, the n-1 The unit cell may have a structure in which electrodes of the same polarity are located at both ends of the unit cell, and the n-th unit cell may have a structure in which electrodes of different polarity are located at both ends of the unit cell, The unit cell may have a structure in which electrodes of different polarities are located at both ends of the unit cell, and the n-th unit cell may have a structure in which electrodes of the same polarity are located at both ends of the unit cell.

As described above, the thicknesses of the various types of unit cells may be equal to each other or may be different from each other, but they may be different from each other in detail.

Specifically, the active material corresponding to the reduced current collector and the thickness of the separator may be additionally added to the unit cell having a structure in which electrodes of different polarities are located at both ends of the unit cell, Unit cells having the same polarity as that of the unit cells having the electrodes of different polarity located at both ends of the unit cell are located at both ends of the unit cell.

On the other hand, the active material corresponding to the thickness of the collector and the separator reduced compared to the conventional battery cell can be uniformly added to all the unit cells constituting the battery cell, and accordingly, The unit cells having a structure in which electrodes having the same polarity as the unit cells formed at both ends of the unit cells are located at both ends of the unit cells may have different thicknesses.

When the unit cells are uniformly added to all the unit cells as described above, the amount of the positive electrode active material or the negative electrode active material applied to one surface of the current collector of each unit cell may be the same, The same amount of active material can be applied to one surface of the current collector without dividing the configuration of the unit cell in the manufacturing process of the cell because it is possible to reduce manpower and time required for the process.

The unit cells may have the same width and length, but the present invention is not limited thereto. The width and / or length of the unit cells may be varied depending on the type and shape of the device on which the battery cell is mounted. They may be made different from each other.

The width indicates a distance between the outer circumferential surface adjacent to the outer circumferential surface where the electrode terminal of the unit cell protrudes and the length indicates the distance from the outer circumferential surface of the unit cell protruding to the opposite outer circumferential surface.

The battery cell according to the present invention is manufactured by attaching the electrode assembly having the above structure to the battery case, and the battery case is not limited to a structure including a cylindrical or square can and a cap mounted on the open upper end portion of the can Or may be a pouch-shaped case of a laminate sheet including a resin layer and a metal layer.

Meanwhile, the battery cell according to the present invention is not particularly limited in its kind, but specific examples thereof include a lithium ion battery having advantages such as high energy density, discharge voltage, and output stability, a lithium secondary battery such as a lithium ion polymer battery, Lt; / RTI >

Generally, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt. In the present invention, the separation film is also included as the same function as the separation membrane.

The positive electrode is prepared, for example, by coating a mixture of a positive electrode active material, a conductive material and a binder on a positive electrode current collector, and then drying the mixture. Optionally, a filler may be further added to the mixture.

The cathode 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 and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where 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} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey 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 which assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, 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 suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

The negative electrode is manufactured by applying and drying a negative electrode active material on a negative electrode collector, and if necessary, the above-described components may be selectively included.

Examples of the negative electrode active material include carbon such as non-graphitized carbon and graphite 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 < Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{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 Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separation membrane and the separation film are interposed between the anode and the cathode, and generally an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separation membrane and the separation film is generally 0.01 to 10 mu m, and the thickness is generally 5 to 300 mu m. Such separation membranes and separation films include, for example, olefin-based polymers such as polypropylene, which is chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane and a separation film.

Further, in one specific example, in order to improve the safety of a high energy density cell, the separation membrane and / or the separation film may be an organic / inorganic composite porous SRS (Safety-Reinforcing Separators) separator.

The SRS separator is manufactured by using inorganic particles and a binder polymer on the polyolefin-based separator substrate as an active layer component. In addition to the pore structure contained in the separator substrate itself, the SRS separator is formed by interstitial volume between inorganic particles And has a uniform pore structure.

The use of such an organic / inorganic composite porous separator has the advantage of suppressing an increase in thickness of the cell due to swelling at the time of chemical conversion compared with the case of using a conventional separator, When a gelable polymer is used when liquid electrolyte is impregnated, it can also be used as an electrolyte.

In addition, the organic / inorganic composite porous separator has a plurality of uniform pore structures formed in both the active layer and the polyolefin-based separator substrate, and the lithium ion is smoothly moved through the pores, and a large amount of electrolyte is filled, Therefore, the performance of the battery can be improved at the same time.

The organic / inorganic composite porous separator composed of the inorganic particles and the binder polymer does not have high temperature heat shrinkage due to the heat resistance of the inorganic particles. Therefore, in the electrochemical device using the organic / inorganic composite porous film as a separator, even if the separator ruptures in the cell due to internal or external factors such as high temperature, overcharging, external impact, etc., The electrodes are hardly short-circuited completely, and even if a short circuit occurs, the short-circuited area is prevented from being greatly enlarged, thereby improving the safety of the battery.

Since the organic / inorganic composite porous separation membrane is formed by coating directly on the polyolefin-based separation membrane, the pores on the surface of the polyolefin-based membrane substrate and the active layer exist as anchoring mutually, so that the active layer and the porous substrate are physically and firmly bonded . Accordingly, not only the problems of mechanical properties such as brittleness can be improved, but also the interfacial adhesion between the polyolefin-based separator base material and the active layer is excellent and the interface resistance is reduced. In the organic / inorganic composite porous separator, the organic / inorganic complex active layer and the porous substrate are chemically bonded to each other, and the pore structure existing in the porous substrate remains unaffected by the active layer, It can be seen that a uniform pore structure due to the inorganic particles is formed in itself. Such a pore structure is filled with a liquid electrolyte to be injected at a later stage, which results in a significant reduction in interfacial resistance between the inorganic particles and between the inorganic particles and the binder polymer.

The organic / inorganic composite porous separation membrane can exhibit excellent adhesive force characteristics by controlling the content of inorganic particles and binder polymer in the separation membrane, so that the battery assembly process can be easily performed.

In the organic / inorganic composite porous separator, one of the active layer components formed on the surface of the polyolefin-based separator substrate and / or the pores of the substrate is an inorganic particle ordinarily used in the art. The inorganic particles enable the formation of voids between the inorganic particles to form micropores and serve as a kind of spacer capable of maintaining the physical shape. In addition, since the inorganic particles generally have a property that their physical properties do not change even at a high temperature of 200 DEG C or more, the formed organic / inorganic composite porous film has excellent heat resistance.

The inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles usable in the present invention are not particularly limited as long as the oxidation and / or reduction reaction does not occur in the operating voltage range of the applied battery (for example, 0 to 5 V based on Li / Li +). Particularly, when inorganic particles having an ion-transporting ability are used, the ion conductivity in the electrochemical device can be increased and the performance can be improved. Therefore, it is preferable that the ionic conductivity is as high as possible. In addition, when the inorganic particles have a high density, it is difficult to disperse the particles at the time of coating, and there is a problem of an increase in weight during the production of the battery. In the case of an inorganic substance having a high dielectric constant, dissociation of an electrolyte salt, for example, a lithium salt, in the liquid electrolyte also contributes to increase ionic conductivity of the electrolyte.

For the reasons stated above, the inorganic particles are preferably high-permittivity inorganic particles having a dielectric constant of 5 or more, preferably 10 or more, inorganic particles having piezoelectricity, inorganic particles having lithium ion transporting ability, or mixtures thereof Do.

The piezoelectricity inorganic particle means a non-conductive material at normal pressure or a material having electrical conductivity due to a change in internal structure when a certain pressure is applied, and exhibits a high permittivity with a dielectric constant of 100 or more, The charge is generated in the case of applying tensile or compressive force, so that one side is charged positively and the other side is negatively charged, thereby generating a potential difference between both sides.

When inorganic particles having the above-described characteristics are used as the porous active layer component, if an internal short-circuit of both electrodes occurs due to an external impact such as local crush or nail, due to the inorganic particles coated on the separator, Not only do not directly contact but also cause a potential difference in the particle due to the piezoelectricity of the inorganic particles. As a result, the electron transfer between the two electrodes, that is, the flow of a minute current, The safety can be improved.

Examples of the inorganic particles having piezoelectricity include BaTiO ₃ , Pb (Zr, Ti) O ₃ (PZT), Pb _{1 -x} La _x Zr _{1 -y} Ti _y O ₃ (PLZT), PB (Mg ₃ Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT) hafnia (HfO ₂ ), or mixtures thereof.

The inorganic particles having the lithium ion transferring ability refer to inorganic particles that contain a lithium element but do not store lithium but have a function of transferring lithium ions. The inorganic particles having lithium ion transferring ability exist in the particle structure Since lithium ions can be transferred and transferred due to a kind of defect, the lithium ion conductivity in the battery can be improved and the battery performance can be improved.

Examples of the inorganic particles having lithium ion transferring ability include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y < (Li _x Al _y Ti _z (PO ₄ ) ₃ , 0 <x <2, 0 <y <1, 0 <z <3), 14Li ₂ O-9Al ₂ O ₃ -38TiO ₂ -39P ₂ O ₅ (0 <x <4, 0 <y <13), lithium lanthanum titanate (Li _x La _y TiO ₃ , 0 <x <2, 0 <y <3), Li _3.25 Ge (Li _x Ge _y P _z S _w , 0 <x <4, 0 <y <1, 0 <z <1, 0 <w <5) such as _0.25 P _0.75 S ₄ , Li ₃ lithium nitride such as _{N (Li x N y, 0} <x <4, 0 <y <2), Li 3 PO 4 -Li 2 Li x (SiS 2 based glass, such as _{S-SiS 2 Si y S z} , 0 <x <3, 0 < y <2, 0 <z <4), LiI-Li 2 SP 2 S 5 P 2 , such as S ₅ based _{glass (Li x P y S z} , 0 <x <3, 0 <y <3, 0 <z <7), or a mixture thereof, but are not limited thereto.

Examples of inorganic particles having a dielectric constant of 5 or more include SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , TiO ₂ , SiC, But is not limited thereto. When the above-mentioned high-permittivity inorganic particles, piezoelectric particles, and inorganic particles having lithium ion-transporting ability are mixed, their synergistic effect can be doubled.

The organic / inorganic composite porous separator of the present invention can control the pore structure of the active layer, as well as the pores contained in the separator substrate, by adjusting the size of the inorganic particles, the content of the inorganic particles, and the composition of the inorganic particles and the binder polymer, And the pore size and porosity can be adjusted together.

The size of the inorganic particles is not limited, but is preferably in the range of 0.001 to 10 mu m for the formation of a film of uniform thickness and a suitable porosity. In the case where the thickness is less than 0.001 탆, the dispersibility of the organic / inorganic composite porous separator is lowered, and it is difficult to control the physical properties of the organic / inorganic composite porous separator. When the thickness exceeds 10 탆, And the excessively large pore size increases the probability of an internal short circuit occurring during charging and discharging of the battery.

The content of the inorganic particles is not particularly limited, but is preferably in the range of 50 to 99% by weight, more preferably 60 to 95% by weight, based on 100% by weight of the mixture of the inorganic particles constituting the organic / inorganic composite porous separator and the binder polymer Do. If the amount is less than 50% by weight, the content of the polymer is excessively increased, and the pore size and porosity may be decreased due to the reduction of the void space formed between the inorganic particles, resulting in deterioration of the final battery performance. On the contrary, when the content is more than 99% by weight, the mechanical properties of the final organic / inorganic composite porous membrane are deteriorated due to the weak adhesive force between the inorganic materials because the polymer content is too small.

In the organic / inorganic composite porous separator according to the present invention, the other of the active layer constituents formed on the surface of the polyolefin-based membrane base material and / or the pores of the above-described substrate is a polymer commonly used in the art. Particularly, it is possible to use a glass transition temperature (Tg) as low as possible, preferably in the range of -200 to 200 ° C. This is because the mechanical properties such as flexibility and elasticity of the final film can be improved. The polymer faithfully fulfills the role of a binder to connect and stably fix the inorganic particles and particles, the inorganic particles and the surface of the separator substrate, and the pores of the separator membrane, thereby improving the mechanical properties of the final organic / inorganic composite porous separator Thereby preventing degradation.

In addition, although the binder polymer does not necessarily have ion conductivity, the performance of the electrochemical device can be further improved by using a polymer having ion conductivity. Therefore, it is preferable that the binder polymer has a high permittivity constant.

In fact, since the degree of dissociation of the salt in the electrolyte depends on the permittivity constant of the electrolyte solvent, the higher the permittivity constant of the polymer is, the better the salt dissociation degree in the electrolyte of the present invention can be. The dielectric constant of the polymer may be in the range of 1.0 to 100 (measurement frequency = 1 kHz), more preferably 10 or more.

In addition to the above-mentioned functions, the binder polymer may be gelled upon impregnation with a liquid electrolyte to exhibit a high degree of swelling of the electrolyte. In fact, when the binder polymer is a polymer having an excellent electrolyte impregnation rate, the electrolyte injected after assembling the battery is impregnated with the polymer, and the polymer having the absorbed electrolyte has electrolytic ion conduction capability. Therefore, the performance of the electrochemical device can be improved compared to the conventional organic / inorganic composite electrolyte. In addition, compared with the conventional hydrophobic polyolefin-based separator, wetting of the electrolyte for a battery is improved, and polarity electrolytic solution for a battery, which has not been used conventionally, can be applied. In addition, when the polymer is a polymer that can be gelled when the electrolyte is impregnated, the gelled organic / inorganic composite electrolyte can be formed by allowing the injected electrolyte and the polymer to react with each other and gel. The thus formed electrolyte is easier to manufacture than the conventional gel type electrolyte, and exhibits high ion conductivity and electrolyte impregnation rate, thereby improving the performance of the battery. Therefore, if possible, a polymer having a solubility index of 15 to 45 MPa &lt; 1/2 &gt; is preferable, and 15 to 25 MPa &lt; 1/2 &gt; and 30 to 45 MPa & When the solubility index is less than 15 MPa &lt; 1/2 &gt; and more than 45 MPa &lt; 1/2 &gt;, it becomes difficult to swell by a common liquid electrolyte for a battery.

Examples of usable binder polymers include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotylchlorethylene, polymethylmethacrylate, Polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate (cellulose acetate), cellulose acetate Cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, hydroxypropylcellulose, hydroxypropylcellulose, hydroxypropylcellulose, Cyanoethyl Acrylonitrile-styrene-butadiene copolymer, polyimide, or a mixture thereof, and the like may be used as the binder resin. The binder may be selected from the group consisting of acrylonitrile-styrene-butadiene copolymer, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, acrylonitrile- However, it is not limited thereto, and any material including the above-mentioned characteristics may be used alone or in combination.

The composition ratio of the inorganic particles and the binder polymer as the active layer component is not particularly limited, but can be adjusted within a range of 10:90 to 99: 1 wt.%, And is preferably in a range of 80:20 to 99: 1 wt. When the ratio is less than 10: 90% by weight, the content of the polymer is excessively increased, resulting in a decrease in the pore size and porosity due to the reduction of the void space formed between the inorganic particles, , The mechanical properties of the final organic / inorganic composite porous membrane may be deteriorated due to the weakening of the adhesion between the inorganic materials because the polymer content is too small.

The active layer of the organic / inorganic composite porous separator may further include other commonly known additives in addition to the inorganic particles and polymers described above.

In the organic / inorganic composite porous separator, a substrate coated with a mixture of inorganic particles and a binder polymer as the active layer constituent may be a polyolefin-based separator commonly used in the art. Examples of the polyolefin-based separation membrane component include high-density polyethylene, linear low-density polyethylene, low-density polyethylene, ultra-high molecular weight polyethylene, polypropylene or derivatives thereof.

The thickness of the polyolefin-based separator base material is not particularly limited, but is preferably in the range of 1 to 100 mu m, more preferably in the range of 5 to 50 mu m. If it is less than 1 탆, it is difficult to maintain the mechanical properties, and when it exceeds 100 탆, it can act as a resistive layer.

The pore size and porosity in the polyolefin-based membrane substrate are not particularly limited, but the pore size is preferably in the range of 10 to 95% and the pore size (diameter) is preferably in the range of 0.1 to 50 μm. When the pore size and the porosity are less than 0.1 μm and less than 10%, respectively, they act as resistance layers. If the pore size and porosity are more than 50 μm and 95%, it becomes difficult to maintain the mechanical properties. In addition, the polyolefin-based membrane substrate may be in the form of fibers or membranes.

The organic / inorganic composite porous separation membrane of the present invention formed by coating a mixture of inorganic particles and a binder polymer on a polyolefin separation membrane substrate includes not only pores in the separation membrane substrate itself but also inorganic particles Both the substrate and the active layer form a pore structure. The pore size and porosity of the organic / inorganic composite porous separation membrane depend mainly on the size of the inorganic particles. For example, when inorganic particles having a particle size of 1 μm or less are used, the pores formed also show 1 μm or less. Such a pore structure is filled with an electrolyte solution to be injected at a later stage, and the filled electrolyte serves as an ion transfer function. Therefore, the pore size and porosity are important factors for controlling the ionic conductivity of the organic / inorganic composite porous separator.

The thickness of the active layer on which the pore structure is formed by coating with the above mixture on the polyolefin separator substrate is not particularly limited, but is preferably in the range of 0.01 to 100 mu m. The pore size and the porosity of the active layer are preferably in the range of 0.001 to 10 탆 and 5 to 95%, respectively, but are not limited thereto.

Preferably, the pore size and the porosity of the organic / inorganic composite porous separation membrane are in the range of 0.001 to 10 탆 and 5 to 95%, respectively. In addition, the thickness of the organic / inorganic composite porous separator is not particularly limited, and can be adjusted in consideration of cell performance. More preferably in the range of 1 to 100 mu m, and particularly preferably in the range of 1 to 30 mu m.

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

Examples of the nonaqueous liquid electrolytic solution include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane , Acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Nonionic organic solvents such as tetrahydrofuran derivatives, ethers, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, Polymers containing ionic dissociation 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 and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a material that is readily soluble 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.

For the purpose of improving the charge-discharge characteristics and the flame retardancy, the non-aqueous liquid electrolyte may contain, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like are added It is possible. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability, or a carbon dioxide gas may be further added to improve high-temperature storage characteristics.

The present invention also provides a device comprising one or more of the battery cells, the device including at least one of a cell phone, a tablet computer, a notebook computer, a power tool, an electric vehicle, a hybrid electric vehicle, a plug- And a power storage device.

Such devices or devices are well known in the art, so a detailed description thereof will be omitted herein.

As described above, in the battery cell according to the present invention, since one of the outermost unit cells in the electrode assembly is constituted by unit cells each having a structure in which electrodes of different polarities are located at both ends of the unit cell, The number of separators and current collectors can be reduced as a whole compared to a battery cell having only unit cells of a structure in which electrodes of the same polarity are located at both ends of the unit cell, The application amount of the active material of the unit cell can be increased by the thickness, so that it is possible to manufacture a battery of high energy density having higher capacity characteristics than the same volume.

The battery cell according to the present invention is characterized in that compared with the case where any one of the unit cells located on the inner side of the electrode assembly is constituted by unit cells having different polarity electrodes located at both ends of the unit cell, The number of types is smaller, and thus the processability is excellent.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view schematically showing a general structure of a conventional stack / folding type electrode assembly; FIG.
2 is a schematic view illustrating a method of manufacturing an electrode assembly of a battery cell according to an embodiment of the present invention;
FIG. 3 is a schematic view schematically showing the structure of some unit cells of FIG. 2; FIG.
4 is a schematic view schematically showing the structure of a battery cell manufactured according to the manufacturing method of FIG. 2;
5 is a schematic view illustrating a method of manufacturing an electrode assembly of a battery cell according to another embodiment of the present invention;
FIG. 6 is a schematic view schematically showing the structure of a battery cell manufactured according to the manufacturing method of FIG. 5; FIG.
7 is a schematic view illustrating a method of manufacturing an electrode assembly of a battery cell according to another embodiment of the present invention;
FIG. 8 is a schematic view schematically showing the structure of a battery cell manufactured according to the manufacturing method of FIG. 7; FIG.
9 is a schematic view illustrating a method of manufacturing an electrode assembly of a battery cell according to another embodiment of the present invention;
10 is a schematic view schematically showing the structure of a battery cell manufactured according to the manufacturing method of FIG.

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

FIG. 2 is a schematic view showing a method of manufacturing an electrode assembly for a battery cell according to an embodiment of the present invention, and FIG. 3 is a schematic view schematically showing the structure of a unit cell of FIG.

2 and 3, the electrode assembly 200 includes a plurality of unit cells 210, 220, 230, 240, 250, 260, and 270 having a structure in which electrodes of the same polarity are located at both ends of the unit cell, By arranging the unit cells 280 having the structure in which the electrodes of the unit cells are located at both ends of the unit cell on the separation film 290 in an alternating manner and winding the separation film 290.

Specifically, the electrode assembly 200 includes eight unit cells 210, 220, 230, 240, 250, 260, 270 and 280, and the eighth unit cell 280 includes electrodes of different polarities 210, 220, 230, 240, 250, 260, and 270 from the first unit cell 210 to the seventh unit cell 270. Each of the unit cells 210, Has a structure in which electrodes of the same polarity are located at both ends of the unit cell.

The first unit cell 210, the fourth unit cell 240, and the fifth unit cell 250 of the unit cells 210, 220, 230, 240, 250, 260, And the outermost electrodes of the second unit cell 220, the third unit cell 230, the sixth unit cell 260, and the seventh unit cell 270 are formed of an anode.

The first unit cell 210 faces the separation film 290 with the cathode 211 facing the bottom and the second unit cell 220 faces the separation film 290 along the electrode direction of the first unit cell 210. The unit cell 280 is positioned on the separation film.

The seventh unit cell 270 and the eighth unit cell 280 located at the outermost side of the electrode assembly 200 are disposed at the outermost portion of the electrode assembly 200, Are arranged such that the anodes 271 and 281 face the separation films 290 toward the bottom, respectively.

The seventh unit cell 270 positioned at the outermost portion of the electrode assembly 200 is disposed on the anode 271 which is the outermost electrode of the electrode assembly 200 with the separator 274 therebetween, The active material 271b is added only to one surface of the current collector 271a facing the cathode 272 and the active material is not provided on the other surface of the current collector 271a facing the separation film 290 . Likewise, the eighth unit cell 280 also includes an anode 281, which is the outermost electrode of the electrode assembly 200, and a current collector 281a facing the cathode 282 having the opposite polarity with the separator 283 therebetween. The active material 281b is added only to one side of the separator 290 and no active material is added to the other side of the current collector 281a facing the separator 290. [

Accordingly, the other surfaces of the current collectors 271a and 281a to which the active material is not applied are located at the outermost portions of the electrode assembly 200. Accordingly, when the battery cell is damaged by the conductive material, the active material 271b, 272b, 273b, 272c, 273c, 281b, 282b, and 282c can be directly contacted with the conductive material to prevent heat generation and fire, and to improve safety.

The electrode assembly 200 is manufactured by winding the first unit cell 210 in the counterclockwise direction 292 from the first unit cell 210 to the eighth unit cell 280 so that the first unit cell 210 is positioned at the innermost position .

The first unit cell 210 is separated from the second unit cell 220 by a separation film 290 corresponding to the unit cell size, A separation film 290 is interposed between the cathode 212 disposed on the upper surface of the first unit cell 210 and the anode 232 disposed on the upper surface of the third unit cell 230. [

Specifically, the first unit cell 210 moves to the spaced-apart portion 291 between the first unit cell 210 and the second unit cell 220 in an inverted state during the winding process, The cathode 211 located on the lower surface of the unit cell 210 is wound so as to face the anode 222 located on the upper surface of the second unit cell 220 and the separation film 290 therebetween.

The first unit cell 210 and the second unit cell 220 facing each other with the separation film 290 therebetween are simultaneously wound by the separation film 290 so that the first unit cell 210 The cathode 212 faces the anode 232 located on the upper surface of the third unit cell 230 with the separation film 290 interposed therebetween.

The process progresses sequentially to the eighth unit cell 280. Thus, the first unit cell 210 is located on the innermost side and the seventh unit cell 270 and the eighth unit cell 270 280 are respectively disposed on the electrode assembly 200.

FIG. 4 is a schematic view schematically showing the structure of the electrode assembly manufactured according to the above-described manufacturing method.

Referring to FIG. 4 together with FIG. 2, an eighth unit cell 280 having a structure in which electrodes of different polarities are located at both ends of a unit cell constitutes one outermost unit cell.

The electrode assembly 200 includes eight unit cells 210, 220, 230, 240, 250, 260, 270 and 280. The electrodes of the outermost electrodes 271 and 281 of the electrode assembly 200 The polarities are the same as the anode.

The first unit cell 210 of the electrode assembly 200 has the cathodes 211 and 212 located at both ends so that the outermost electrodes 271 and 281 of the electrode assembly 200 are composed of an anode .

On the other hand, when the first unit cell 210 is positioned at both ends of the anode, the outermost electrodes of the electrode assembly 200 may be configured as a cathode.

The electrode assembly 200 includes 10 anodes, 11 cathodes, 2 anode sections, and 15 separators.

As a result, the number of separation membranes, which are inactive materials, is reduced and the number of the positive and negative electrodes is reduced compared to a battery cell composed of only unit cells having a structure in which electrodes of the same polarity are located at both ends of the unit cell. The total amount of water is also reduced, and as much as the amount of the active material corresponding to the thickness of the reduced inert material can be added, as a result, the overall capacity of the battery cell can be increased.

In the electrode assembly 200, a first unit cell 210 having a structure in which electrodes having the same polarity as that of the eighth unit cell 280 having electrodes of different polarities located at both ends of the unit cell are located at both ends of the unit cell, The seventh to the seventh unit cells 270 are different from each other in the overall thicknesses of the unit cells 210, 220, 230, 240, 250, 260, 270, 280).

Accordingly, since the coating amount of the active material on one side of the current collector of each of the unit cells 210, 220, 230, 240, 250, 260, 270, and 280 is uniform, , 220, 230, 240, 250, 260, 270, and 280, the active material is uniformly applied to one surface of the current collector, thereby reducing manpower and time required for the process.

However, the present invention is not limited thereto. The unit cells 210, 220, 230, 240, 250, 260, 270, and 280 of the electrode assembly 200 may have the same thickness, It is possible to further add the active material corresponding to the thickness of the collector and the separation membrane to the eighth unit cell 280 having a structure in which electrodes of different polarities are positioned at both ends of the unit cell, Accordingly, the eighth unit cell 280 may have the same thickness as the first unit cell 210 to the seventh unit cell 270 having the electrodes of the same polarity positioned at both ends of the unit cell.

5 is a schematic view illustrating a method of manufacturing an electrode assembly of a battery cell according to another embodiment of the present invention.

5, the electrode assembly 300 includes a seventh unit cell 370 instead of the eighth unit cell 380 in which the unit cell having a structure in which electrodes of different polarities are located at both ends of the unit cell Which is different from the electrode assembly 200 of FIG.

Unlike the electrode assembly 200 of FIG. 2, the electrode assembly 300 includes a seventh unit cell 370 having electrodes of different polarities positioned at both ends of the unit cell, The negative electrode 371 of the seventh unit cell 370 and the negative electrode 381 of the eighth unit cell 380 located on the outermost side of the electrode assembly 500 are separated from the separation film 580 As shown in Fig.

The electrode assembly 300 is manufactured by winding the first unit cell 310 in the counterclockwise direction 392 from the first unit cell 310 to the eighth unit cell 380 so that the first unit cell 310 is positioned at the innermost position, The winding process is the same as in Fig.

The cathode 371 of the seventh unit cell 370 facing the separation film and the cathode 381 of the eighth unit cell 380 correspond to the seventh unit cell 270 and the eighth unit cell The active material is added only to one surface of the current collector facing the electrode having the opposite polarity with the separator interposed therebetween, and no active material is added to the other surface of the current collector facing the separation film.

FIG. 6 is a schematic view schematically showing the structure of the electrode assembly 300 manufactured according to the above manufacturing method.

Referring to FIG. 6 together with FIG. 5, a seventh unit cell 370 having a structure in which electrodes of different polarities are located at both ends of a unit cell constitutes one outermost unit cell.

The electrode assembly 300 includes eight unit cells 310, 320, 330, 340, 350, 360, 370 and 380. The electrode assemblies 300 are formed on the outermost electrodes 371 and 381 of the electrode assembly 300, The polarities are the same as the cathodes.

The first unit cell 310 of the electrode assembly 300 has the cathodes 311 and 312 at both ends so that the outermost electrodes 371 and 381 of the electrode assembly 300 are composed of cathodes .

On the other hand, when the first unit cell 310 is configured such that the anodes are located at both ends, the outermost electrodes of the electrode assembly 300 may be configured as an anode.

The electrode assembly 300 includes 11 anodes, 10 cathodes, 2 cathode sections, and 15 separators.

The configuration and effect of the other electrode assembly 300 are the same as those of the electrode assembly 200 of FIG.

7 is a schematic view showing a method of manufacturing an electrode assembly for a battery cell according to another embodiment of the present invention.

Referring to FIG. 7, similarly to the electrode assembly 200 of FIG. 2, the electrode assembly 400 includes unit cells 410, 420, 430, 440 and 450 having a structure in which electrodes of the same polarity are located at both ends of the unit cell 460 are arranged on alternate sides of the separation film 490 and the separation film 490 is wound around the unit cells 470. The unit cells 470 are arranged on both sides of the unit cell.

Specifically, the electrode assembly 400 includes seven unit cells 410, 420, 430, 440, 450, 460 and 470, and the seventh unit cell 470 includes electrodes of different polarities, And the six unit cells 410, 420, 430, 440, 450, and 460 from the first unit cell 410 to the sixth unit cell 460 have the same structure And the electrodes of the polarity are located at both ends of the unit cell.

Unlike the electrode assembly 200 of FIG. 2, the electrode assembly 400 includes an odd number of unit cells 410, 420, 430, 440, 450, 460 and 470, The anode 461 of the sixth unit cell 460 and the cathode 471 of the seventh unit cell 470 located on the outermost side of the electrode assembly 400 respectively face the bottom (490).

The electrode assembly 400 is manufactured by winding the first unit cell 410 in the counterclockwise direction 492 from the first unit cell 410 to the seventh unit cell 470 so that the first unit cell 410 is positioned at the innermost position, The winding process is the same as in Fig.

The anode 461 of the sixth unit cell 460 facing the separation film and the cathode 471 of the seventh unit cell 470 are connected to the seventh unit cell 270 and the eighth unit cell The active material is added only to one surface of the current collector facing the electrode having the opposite polarity with the separator interposed therebetween, and no active material is added to the other surface of the current collector facing the separation film.

A schematic view schematically showing the structure of the electrode assembly 400 manufactured according to the above manufacturing method is shown in FIG.

Referring to FIG. 8 together with FIG. 7, a seventh unit cell 570 having a structure in which electrodes of different polarities are located at both ends of a unit cell constitutes one outermost unit cell.

The electrode assembly 400 includes seven unit cells 410, 420, 430, 440, 450, 460, 470 and 480, and the outermost electrodes 461 and 471 of the electrode assembly 300 The polarities are different from each other as an anode and a cathode.

The first unit cell 410 of the electrode assembly 400 has the cathodes 411 and 412 at both ends so that the outermost electrodes 461 and 471 of the electrode assembly 400 are respectively connected to the cathode (471), and the lowermost end thereof is constituted by the anode (461).

On the other hand, when the first unit cell 410 is configured such that the anodes are located at both ends, the outermost electrodes of the electrode assembly 400 may be constituted by the anode at the uppermost end and by the cathode at the lowermost end.

The construction and effect of the other electrode assembly 400 are the same as those of the electrode assembly 200 of FIG.

9 is a schematic view illustrating a method of manufacturing an electrode assembly for a battery cell according to another embodiment of the present invention.

Referring to FIG. 9, the electrode assembly 500 includes a sixth unit cell 560 instead of the seventh unit cell 570, which has a structure in which electrodes of different polarities are located at both ends of the unit cell Which is different from the electrode assembly 400 of FIG.

Unlike the electrode assembly 400 of FIG. 7, the electrode assembly 500 includes a sixth unit cell 560 having electrodes of different polarities located at both ends of the unit cell, The cathode 561 of the sixth unit cell 560 located on the outer side and the anode 571 of the seventh unit cell 570 are arranged facing the separation film 580 toward the bottom.

The electrode assembly 500 is manufactured by winding the first unit cell 510 in the counterclockwise direction 592 from the first unit cell 510 to the seventh unit cell 570 so that the first unit cell 510 is positioned at the innermost side, The winding process is the same as in Fig.

The cathode 561 of the sixth unit cell 560 facing the separation film and the anode 571 of the seventh unit cell 570 are connected to the seventh unit cell 270 and the eighth unit cell The active material is added only to one surface of the current collector facing the electrode having the opposite polarity with the separator interposed therebetween, and no active material is added to the other surface of the current collector facing the separation film.

FIG. 10 is a schematic view schematically showing the structure of the electrode assembly 500 manufactured according to the above manufacturing method.

Referring to FIG. 10 together with FIG. 9, a sixth unit cell 560 having a structure in which electrodes of different polarities are located at both ends of a unit cell constitutes one outermost unit cell.

The electrode assembly 500 includes seven unit cells 510, 520, 530, 540, 550, 560 and 570 and the polarities of the outermost electrodes 561 and 571 of the electrode assembly 500 are And are different from each other as an anode and a cathode.

The first unit cell 510 of the electrode assembly 500 has the cathodes 511 and 512 located at both ends so that the outermost electrodes 561 and 571 of the electrode assembly 500 are respectively connected to the anode (571), and the lowermost end thereof is constituted by the cathode (561).

On the other hand, when the first unit cell 510 is configured such that the anodes are located at both ends, the outermost electrodes of the electrode assembly 500 may be constituted by the cathode at the uppermost end and by the anode at the lowermost end.

The configuration and effects of the other electrode assembly 400 are the same as those of the electrode assembly 400 of FIG.

The structure of the battery cell according to the present invention is not limited thereto and the battery cell may be manufactured by folding the unit cells in a structure in which the separation film is wrapped in a Z shape from the lowermost unit cell to the uppermost unit cell of the electrode assembly have.

Hereinafter, the present invention will be described with reference to Examples. However, the following Examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

&Lt; Example 1 >

The electrode assembly was assembled as shown in FIGS. 2 to 4, embedded in a pouch-shaped battery case, and impregnated with an EC / EMC electrolyte solution containing 1 M LiPF ₆ lithium salt to prepare a battery cell. At this time, the size of the battery cell was designed to be 3.5 mm * 79.6 mm * 92.5 mm.

&Lt; Comparative Example 1 &

The electrode assembly was assembled as shown in FIG. 1, embedded in a pouch-shaped battery case, and impregnated with an EC / EMC electrolyte solution containing 1 M LiPF ₆ lithium salt to prepare a battery cell. At this time, the size of the battery cell was designed to be 3.5 mm * 79.6 mm * 92.5 mm.

<Experimental Example 1>

The total loading amount of the positive electrode, the battery capacity, and the energy density were measured for the battery cells manufactured in Example 1 and Comparative Example 1, and the results are shown in Table 1 below.

division Number of Stack Anode loading
(mg / 25 cm ² ) Capacity (mAh) Energy density
(Wh / L) Example 1 8 470 3986 588 Comparative Example 1 433 3840 568

Referring to Table 1, the battery cell according to the present invention can increase the loading amount of the electrode active material as compared with the battery cell having the unit cells of the structure in which the electrodes of the same polarity are located at both ends of the unit cell, And the energy density increased by 3.8% and 3.5%, respectively.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (20)

An electrode assembly including a positive electrode and a negative electrode coated with an active material on a current collector, a unit cell having a laminated structure composed of a separator interposed between the positive and negative electrodes, and a separator film for continuously winding the unit cells, Is mounted on the receiving portion of the housing;
One of the outermost unit cells in the electrode assembly has a structure in which electrodes of different polarities are positioned at both ends of the unit cell, and the remaining unit cells are independently positioned at both ends of the unit cell, Lt; / RTI &gt;
Wherein the outermost electrodes of the electrode assembly are provided with an active material only on one surface of the current collector facing the electrode of the opposite polarity. The battery cell according to claim 1, wherein the electrodes except the outermost electrodes of the electrode assembly are coated with active material on both sides of the current collector. The unit cell according to claim 1, wherein the unit cells having the structure in which the electrodes of the same polarity are located at both ends of the unit cell include a unit cell having a structure in which an anode is located at both ends and a unit cell having a structure in which a cathode is disposed at both ends And the battery cell. The battery cell according to claim 1, wherein the number of unit cells of the electrode assembly is an even number. The battery cell according to claim 4, wherein the outermost electrodes of the electrode assembly have the same polarity. The battery cell according to claim 5, wherein the polarity of the outermost electrodes is an anode. The battery cell according to claim 1, wherein the number of unit cells of the electrode assembly is an odd number. The battery cell according to claim 7, wherein the outermost electrodes of the electrode assembly have different polarities from each other. The method according to claim 1, wherein the electrode assembly includes a first unit cell located at the innermost position and an n-1 th unit cell and an n th unit cell, And each of the plurality of battery cells is sequentially wound so as to be positioned on the outermost side thereof. The battery cell according to claim 9, wherein a separation region corresponding to the size of the unit cell is formed on the separation film between the first unit cell and the second unit cell. The battery cell according to claim 9, wherein the n-1 th unit cell and the n th unit cell do not have an active material coated on one side of the current collector of the electrode facing the separation film on the separation film before being wound. The apparatus of claim 9, wherein the (n-1) th unit cell has a structure in which electrodes having the same polarity are located at both ends of the unit cell, and the n-th unit cell has electrodes having different polarities at both ends of the unit cell Wherein the battery cell is a battery cell. The apparatus of claim 9, wherein the (n-1) th unit cell has a structure in which electrodes of different polarities are located at both ends of the unit cell, and the n-th unit cell has electrodes of the same polarity positioned at both ends of the unit cell Wherein the battery cell is a battery cell. The battery cell according to claim 1, wherein the unit cells have the same thickness. 2. The unit cell according to claim 1, wherein the unit cells each having a structure in which the electrodes of the same polarity are located at both ends of the unit cell, A battery cell characterized by: 16. The battery cell according to claim 15, wherein the unit cells have the same coating amount of the positive electrode active material or negative electrode active material on one surface of the current collector. The battery cell according to claim 1, wherein the battery cell is a lithium secondary battery. [3] The battery cell of claim 1, wherein the separator and / or the separator film is an oil / inorganic composite porous SRS (Safety-Reinforcing Separators) separator. A device comprising at least one battery cell according to claim 1. 20. The device of claim 19, wherein the device is any one selected from the group consisting of a cell phone, a tablet computer, a notebook computer, a power tool, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, Device.

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