KR101323153B1 - Electrode Assembly Having Novel Structure and Secondary Battery Using the Same - Google Patents

Abstract

The present invention has a positive electrode, a negative electrode, and a separation layer located between the positive electrode and the negative electrode has a monolithic structure, the separation layer is a linear polymer and a liquid phase component containing the ionic salt and the liquid phase component One or more two-phase electrolytes comprising a polymer matrix in which the crosslinked polymer forms a viscoelastic structure; And a polymer matrix in which a viscoelastic structure is formed between a liquid phase component including an ionic salt, a solid phase component supporting a separation layer between an anode and a cathode, and a linear polymer and a crosslinked polymer in a state in which the liquid component and the solid phase component are embedded. At least one three-phase electrolyte comprising a; multi-layer structure comprising a, wherein the polymer matrix is bonded to the positive electrode or the negative electrode, the liquid component of the separation layer in the manufacturing process of the electrode assembly part of the electrode It provides an integrated electrode assembly characterized in that the flow.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a novel structure electrode assembly,

The present invention relates to a novel structure electrode assembly and a secondary battery using the same, more particularly. The positive electrode, the negative electrode, and the separation layer positioned between the positive electrode and the negative electrode have an integral structure, and the separation layer has a viscoelasticity between the linear polymer and the crosslinked polymer in a state in which the liquid component including the ionic salt and the liquid component are embedded. One or more two-phase electrolytes comprising a polymer matrix forming the structure; And a polymer matrix in which a viscoelastic structure is formed between a liquid phase component including an ionic salt, a solid phase component supporting a separation layer between an anode and a cathode, and a linear polymer and a crosslinked polymer in a state in which the liquid component and the solid phase component are embedded. At least one three-phase electrolyte comprising a; multi-layer structure comprising a, wherein the polymer matrix is bonded to the positive electrode or the negative electrode, the liquid component of the separation layer in the manufacturing process of the electrode assembly part of the electrode It relates to an integrated electrode assembly characterized in that the flow.

As the price of energy sources increases due to exhaustion of fossil fuels and the interest of environmental pollution is amplified, demand for environmentally friendly alternative energy sources is an indispensable factor for future life. 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. Secondary batteries are mainly used as such power storage devices. Among secondary batteries, especially lithium secondary batteries, which are mainly used in portable devices, demand for light weight, high voltage, and capacity is increasing. Its use area has been expanded greatly for electric vehicles, power auxiliary power supply through gridization, and the like.

However, there are many problems to be solved for using a lithium secondary battery with a large capacity power source, and the most important task is improvement of energy density and safety. In addition, the wetting uniformity and shortening of the process time of the electrolyte due to the large area is also the most important problem to be solved. Therefore, many researchers are spurring research on materials that can meet low cost while improving energy density, and are also making efforts to study materials to improve safety.

As a material for improving the energy density, a Ni-based material or a Mn-based material having a capacity higher than that of LiCoO ₂ that has been used previously is being studied. As a cathode, The material by Li alloy reaction is being studied.

In order to improve safety, a stable olivine-based cathode active material such as LiFePO ₄ or an anode active material such as Li ₄ Ti ₅ O ₁₂ and the like are being studied. However, such a material for improving safety has a fundamentally low energy density, and can not fundamentally solve the safety problem of the structure of the lithium secondary battery.

The safety of the secondary battery can be divided into internal safety and external safety, and subdivided into electrical safety, impact safety and thermal safety. These various safety problems commonly involve a temperature rise in the event of a problem, in which case shrinkage of the drawn membranes generally used will inevitably occur.

There is a battery in which a positive electrode and a negative electrode are electrically separated by using an unstretched solid electrolyte, but due to limitations in ionic conductivity of a solid, it has not reached a level that satisfies desired battery performance.

Accordingly, there is a high need for a structure of a battery which prevents a short circuit due to shrinkage of the separator and has excellent cell performance.

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

After extensive research and various experiments, the inventors of the present application have developed an integrated electrode assembly using a separation layer composed of a multilayer structure including a specific two-phase and three-phase electrolytes. The electrode assembly can prevent the short circuit caused by the shrinkage of the separator, the liquid component of the separation layer flows into the electrode in the manufacturing process of the electrode assembly to confirm that the wetting characteristics of the electrode is very excellent, thereby improving the ion conductivity, The invention was completed.

Accordingly, the electrode assembly according to the present invention has a structure in which an anode, a cathode, and a separation layer positioned between the anode and the cathode are integral with each other, and the separation layer,

At least one two-phase electrolyte comprising a liquid component including an ionic salt and a polymer matrix in which the linear polymer and the crosslinked polymer form a viscoelastic structure in a state in which the liquid component is embedded; And

A liquid matrix comprising an ionic salt, a solid component for supporting a separation layer between an anode and a cathode, and a polymer matrix in which a linear polymer and a crosslinked polymer form a viscoelastic structure in a state in which the liquid component and the solid component are embedded. One or more three-phase electrolytes comprising;

Consists of a multi-layer structure comprising a, wherein the polymer matrix is bonded to the positive electrode or the negative electrode, and is an integral electrode assembly having a configuration that the liquid component of the separation layer is partially introduced into the electrode during the manufacturing of the electrode assembly.

According to the experiment of the present inventors, the instant of maximization of the danger within the secondary battery is a state where the energy is increased, and the short-circuit situation which may occur due to the separation of the membrane in the charged state includes (1) 2) charged positive and negative current collectors, 3) negative current collector and positive current collector, and 4) positive current collector and charged negative electrode.

As a result of testing all of the above conditions in the dry room of the charged electrode, it was confirmed that the most severe thermal runaway occurred in the contact between the charged anode and the anode current collector. As a result of intensive research, it was found that this is due to a rapid exothermic reaction of, for example, 4Al + 3O ₂ → 2Al ₂ O ₃ in Al-foil, which is a positive electrode current collector. In all cases where the actual battery exploded, Al-foil could not find its shape.

In the above experiment, thermal runaway occurs only when the charged cathode and the positive electrode collector are in contact with each other. However, the other three cases are not necessarily safe. In a battery, it is dangerous to contact any part of the anode and the cathode with each other.

On the other hand, since the polymer matrix and the solid-phase component are not shrunk at high temperature, the integrated electrode assembly according to the present invention can prevent the occurrence of an event such as explosion as in the above-described experiment, and is excellent in high-temperature safety.

In addition, the electrode assembly includes a two-phase electrolyte comprising a polymer matrix in which the linear polymer and the crosslinked polymer form a viscoelastic structure in the state in which the liquid component and the liquid component are embedded, as an additional layer. In the manufacturing process, for example, the lamination process is introduced into the electrode to impregnate the electrode, thereby improving the ion conductivity of the electrode can improve the performance of the battery. In addition, as the electrolyte is uniformly wetting to the electrode, electrode degradation due to uneven penetration of the electrolyte, which is the biggest problem in large area, may be minimized.

Therefore, the electrode assembly of the present invention may be defined as having, in relation to the state of the electrolytic solution, a part of the liquid component derived from the separating layer contained or embedded in the electrode. At this time, the amount of the liquid component contained in or embedded in the electrode derived from the separation layer is not particularly limited, and may be, for example, 10 to 90% based on the total amount of the liquid component contained in the entire electrode assembly.

The liquid component of the separation layer may be partially introduced into the electrode by a pressurizing process. In the case of manufacturing the integrated battery with the above-described structure, it is preferable that the liquid phase component flows into the electrode by a separate pressing process because the separation layer carries the liquid phase component. In this case, the wettability of the electrode is improved, and the problem of ionic conductivity, which has been pointed out as a disadvantage of the conventional polymer battery, can be solved.

In addition, when the separation layer having a multi-layer structure is used, compared to the case of using a three-phase electrolyte alone, the advantages of the polymer degradation can be minimized in terms of performance while maintaining the advantages thereof, which is a safety characteristic required for the battery. Can be maximized.

 In addition, according to the present invention, since the separation layer is composed of a polymer matrix in which a linear polymer and a crosslinked polymer form a viscoelastic structure in a state in which a liquid phase component and optionally a solid phase component are embedded therein, the electrode is charged or discharged during the process. Although the volume expansion and contraction of is repeated continuously, the viscoelastic structure can cancel the volume change has the advantage of excellent durability and thereby improving the cycle characteristics.

In general, in the case of a membrane having a high degree of crosslinking composed of one crosslinked structure, the mobility of polymer chains affecting the movement of ions is suppressed, and thus the ion conductivity tends to be low, and brittleness in terms of mechanical properties. Tends to

On the other hand, in the case of the above-described viscoelastic structure, since the polymer chain has an appropriate fluidity due to the linear polymer, it may have high ionic conductivity, and the crosslinked polymer forms a crosslinking point in the matrix and the linear polymer interconnects it. Since it can have elasticity can exhibit excellent mechanical properties.

In one preferred embodiment, the viscoelastic structure is an independent gel made of the crosslinked polymer can be made of a structure in which the independent gels (crosslinked polymer) of the crosslinked polymer is physically interconnected by linear polymers in the liquid phase impregnated state They each form a crosslinking point and are physically interconnected by linear polymers, thereby forming a network, whereby the liquid component can be impregnated with a high content.

The linear polymers may, for example, form a physical connection structure in which a part thereof penetrates into the gel of the crosslinked polymers, which is more preferable for the formation of the network structure described above. The portion of the linear polymer that has penetrated the gel may be in the range of preferably less than 50%, more preferably 5 to 45% based on the linear polymer total size.

In the polymer matrix, the ratio of the linear polymer and the crosslinked polymer is not particularly limited as long as it is a ratio capable of forming a viscoelastic structure, but is preferably 1: 9 to 8: 2 by weight in the total composition of the separation layer. If the linear polymer is too small or too many, it is not preferable because the elasticity is weak and mechanical properties are lowered and the impregnation performance of the liquid component is lowered. For the same reason as above, the ratio of the linear polymer and the crosslinked polymer is more preferably 3: 7 to 7: 3 by weight.

The solid phase component may be a solid compound that is not reactive with ion conductive ceramics and / or lithium ions, and more preferably, the solid compound is one or more selected from the group consisting of oxides, nitrides, and carbides that are not reactive with lithium ions The oxide that is not reactive with the lithium ion may be at least one selected from the group consisting of MgO, TiO ₂ (Rutile), and Al ₂ O ₃ .

The liquid component of the separation layer may be partially introduced into the electrode by a pressurizing process.

In one preferred example, the liquid component may be an electrolyte comprising an ionic salt, and the ionic salt may be a lithium salt.

The lithium salt is, 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 It may be one or more selected from the group consisting of SO ₃ Li, (CF ₃ SO ₂ ) ₂ Nli, chloroborane lithium, lower aliphatic lithium carbonate and lithium tetraphenylborate, but is not limited thereto.

The electrolyte is, for example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, gamma butyrolactone, sulfolane, methyl acetate and methyl propionate. It may be one or more selected from the group consisting of, but is not limited thereto.

The linear polymer may be at least one selected from the group consisting of polyoxide-based noncrosslinked polymers and polar noncrosslinked polymers.

The polyoxide-based non-crosslinked polymer may be, for example, one or more selected from the group consisting of Poly (ethylene oxide), Poly (propylene oxide), Poly (oxymethylene), and Poly (dimethylsiloxane), and the polar non-crosslinked polymer For example, polyacrylonitrile, Poly (methyl methacrylate), Poly (vinyl chloride), Poly (vinylidene fluoride), Poly (vinylidenefluoride-co-hexafluoropropylene), Poly (ethylene imine) and Poly (p-phenylene terephthalamide) It may be one or more selected from the group, but is not limited to these.

In one preferred example, the crosslinked polymer may be a polymer of a monomer having two or more functional groups, or a copolymer of a monomer having two or more functional groups and a polar monomer having one functional group.

The monomer having two or more functional groups may be, for example, trimethylolpropane ethoxylate triacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, and the like. diacrylate), divinylbenzene, polyester dimethacrylate, divinyl ether, trimethylolpropane, trimethylolpropane trimethacrylate, and ethoxylated bisphenol A dimethacryl It may be one or more selected from the group consisting of ethoxylated bis phenol A dimethacrylate.

Examples of the polar monomer having one functional group include methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, ethylene glycol methyl ether acrylate, and ethylene glycol methyl ether methacryl. It may be at least one selected from the group consisting of latex, acrylonitrile, vinyl acetate, vinyl chloride, and vinyl fluoride.

The separation layer may be composed of two layers of a two-phase electrolyte and a three-phase electrolyte, or may be composed of three layers of a two-phase electrolyte / 3 phase electrolyte / 2 phase electrolyte, and a three-phase electrolyte / 2 phase electrolyte / 3 phase electrolyte Various structures are possible, such as three layers.

In the electrode assembly of the present invention, the positive electrode is prepared, for example, by applying and drying a slurry prepared by adding a positive electrode mixture containing a positive electrode active material to a solvent such as NMP on a positive electrode collector, May further include a binder, a conductive material, a filler, a viscosity adjusting agent, and an adhesion promoter.

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver, or the like can be used. The positive electrode current collector may have fine unevenness formed on the surface thereof to increase the adhesive force of the positive electrode active material as in the case of the negative electrode current collector. Alternatively, the positive electrode current collector may have various properties such as a film, sheet, foil, net, porous body, Form is possible.

The cathode active material is a material capable of causing an electrochemical reaction. Examples of the lithium transition metal oxide include lithium cobalt oxide (LiCoO ₂ ) containing two or more transition metals and substituted with one or more transition metals, lithium Layered compounds such as nickel oxide (LiNiO ₂ ); Lithium manganese oxide substituted with one or more transition metals; Formula _{LiNi 1-y M y O 2} ( where, M = Co, Mn, Al , Cu, Fe, Mg, B, Cr, Zn or Ga and Lim, 0.01≤y≤0.7 include one or more elements of the element) A lithium nickel-based oxide represented by the following formula: _{Li 1 + z Ni 1/3 Co 1/3} Mn 1/3 O 2, Li 1 + z Ni 0.4 Mn 0.4 Co 0.2 O 2 , such as _{Li 1 + z Ni b Mn c} Co 1- (b + c + d _{) M d O (2-e} ) A e ( where, -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2 , 0≤e≤0.2, b + c + d <1, M = Al, Mg, Cr, Ti, Si or Y, and A = F, P or Cl; lithium nickel cobalt manganese composite oxide; And the formula _{Li 1 + x M 1-y} M 'y PO 4-z X z ( wherein, M = a transition metal, preferably Fe, Mn, Co or Ni, M' = Al, Mg or Ti, X = F, S or N, and -0.5? X? +0.5, 0? Y? 0.5, and 0? Z? 0.1), but the present invention is not limited thereto.

Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), cellulose, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, various copolymers, high molecular weight polyolefins such as polyolefin, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, Vinyl alcohol, and the like.

The conductive material is not particularly limited as long as it has electrical conductivity without causing any chemical change in the battery, for example, 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 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. Concrete examples of commercially available conductive materials include acetylene black series such as Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, etc.), Ketjenblack, EC (Armak Company), Vulcan XC-72 (Cabot Company), and Super P (Timcal).

The filler 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 fibers and carbon fibers are used.

The viscosity modifier may be added up to 30% by weight based on the total weight of the negative electrode mixture as a component for adjusting the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the current collector may be easy. Examples of such viscosity modifiers include carboxymethylcellulose, polyvinylidene fluoride and the like, but are not limited thereto. In some cases, the above-described solvent may play a role as a viscosity adjusting agent.

The adhesion promoter may be added in an amount of 10% by weight or less based on the binder, for example, oxalic acid, adipic acid, Formic acid, acrylic acid derivatives, itaconic acid derivatives, and the like.

The negative electrode may be formed by applying a slurry prepared by adding a negative electrode active material containing a negative active material on a negative electrode current collector to a solvent such as NMP and drying the negative electrode active material. Fillers, viscosity modifiers, and adhesion promoters, and the like.

The negative electrode collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery, and may be formed of a material such as copper, stainless steel, aluminum, nickel, titanium, fired carbon, surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the negative electrode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

Examples of the negative electrode active material include carbon and graphite materials such as natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotube, fullerene and activated carbon; Metals such as Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pt, and Ti that can be alloyed with lithium and compounds containing these elements; Complexes of metals and their compounds and carbon and graphite materials; Lithium-containing nitrides, and the like. Among them, a carbon-based active material, a tin-based active material, a silicon-based active material, or a silicon-carbon based active material is more preferable, and these may be used singly or in combination of two or more.

The present invention also provides a method of manufacturing an integral electrode assembly,

(1) a process for preparing a mixture for a two- or three-phase electrolyte by uniformly mixing a linear polymer, a monomer component for a crosslinking polymer, a liquid component comprising an ionic salt, a polymerization initiator and optionally a solid phase component;

(2) coating the two-phase or three-phase mixture on one electrode;

(3) a step of forming a two-phase or three-phase electrolyte layer by performing a polymerization reaction by UV irradiation or application of heat;

(4) repeating steps (2) and (3) on the two-phase or three-phase electrolyte layer to form a separation layer comprising a plurality of electrolyte layers; And

(5) placing and pressing the corresponding electrode on the separation layer;

The present invention provides a method of manufacturing an integral electrode assembly.

A conventional method for manufacturing an electrode assembly is a method of manufacturing a mold for forming a space between an anode and a cathode, and injecting a polymer monomer mixture into the space and then polymerizing the mixture.

On the other hand, as in the present invention, the method of coating and polymerizing a predetermined material on one electrode can simplify the process, and the liquid component of the separation layer in the pressurizing step (step (5) The ion conductivity of the electrode can be improved by impregnating the electrode, which is preferable for improving the performance of the battery.

In addition, in the process (1) of the present invention, the linear polymer is mixed in the form of a polymer rather than a monomer, so that during the polymerization of the crosslinked polymer in the process (3), a part of the linear polymer penetrates into the gel of the crosslinked polymer Physical connection structure can be achieved.

The present invention also provides a lithium secondary battery including the integral electrode assembly, wherein the lithium secondary battery includes the integral electrode assembly and a non-aqueous electrolyte solution containing a lithium salt. In one preferred example, the lithium secondary battery does not include a separate lithium salt-containing non-aqueous electrolyte, or may contain only a small amount.

This is possible by partially inflowing the liquid component of the separation layer into the electrode by impregnation with the electrode in step (5) of the manufacturing method of the present invention. Considering that the electrode impregnation process is a bottleneck process in the battery manufacturing process, An excellent secondary battery can be provided.

In addition, the present invention provides a lithium secondary battery comprising the integrated electrode assembly, and provides a medium-large battery module including the lithium secondary battery as a unit battery and a battery pack including the battery module. The battery pack may be used in a variety of medium-large and large devices that require high rate characteristics and high temperature safety, for example, a power tool that is driven by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); Electric motorcycle including E-bike, E-scooter; An electric golf cart, or the like, and may be used in a power storage system, but the present invention is not limited thereto.

As described above, the integrated electrode assembly according to the present invention can prevent a short circuit due to shrinkage of the separator, and significantly improve the problem of electrode unevenness and process time increase due to wetting due to the electrolyte being impregnated into the electrode during the manufacturing process. In addition, there is an advantage that the ion conductivity of the electrode can be improved.

1 is a schematic view showing a cross section of an integral electrode assembly according to one embodiment of the present invention;
FIG. 2 is an enlarged view of the three phase separation layer of FIG. 1; FIG.
3 is an enlarged view of the two phase separation layer of FIG. 1;
4 is a graph showing the voltage and capacity relationship of the integrated electrode assembly according to the present invention;
5 is a graph showing the cycle characteristics of a secondary battery according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

1 is a cross-sectional view schematically showing an integrated electrode assembly according to an embodiment of the present invention, Figures 2 to 3 is an enlarged view of a three-phase separation layer and a two-phase separation layer schematically. .

Referring to these drawings, the electrode assembly 100 of the present invention is composed of a separation layer in which the anode 110, the cathode 120 and the three-phase separation layer 130 and the two-phase separation layer 140 forms a multilayer structure. have. The positive electrode 110 has a structure in which positive electrode mixtures 112 and 113 are coated on both sides of the positive electrode current collector 111, and the separation layer having the multilayer structure is positioned between the positive electrode 110 and the negative electrode 120. It consists of a structure.

The three phase separation layer 130 is a solid phase component 131; Liquid component 132; And a polymer matrix in which the linear polymer 133 and the crosslinked polymer 134 form a viscoelastic structure in a state in which the solid component 131 and the liquid component 132 are embedded.

In addition, the two-phase separation layer 140 does not include a separate solid component, and the linear polymer 143 and the crosslinked polymer 144 are viscoelastic in a state in which the liquid component 142 and the liquid component 142 are embedded. It consists of a polymer matrix forming a structure.

Since the integrated electrode assembly having the separation layer of the multilayer structure as described above does not shrink at high temperature, the polymer matrix and the solid phase component can prevent occurrence of an event such as explosion and thus have excellent high temperature safety.

In addition, due to the two-phase separation layer containing a relatively large amount of the liquid component 142, the liquid component 132, 142 in the direction of the arrow of Figure 1 during the manufacturing process, for example, lamination process of the electrode assembly Since the electrodes 110 and 120 are introduced to impregnate the electrodes 110 and 120, ion conductivity of the electrodes 110 and 120 may be improved, thereby improving performance of the battery. In addition, as the electrolyte is uniformly wetted to the electrodes 110 and 120, the deterioration of the electrodes 110 and 120 due to the inhomogeneous penetration of the electrolyte, which is the biggest problem in large area, may be minimized.

Hereinafter, the present invention will be described in detail with reference to the following 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 negative electrode was prepared by adding graphite, PVdF, and carbon black to NMP to prepare a slurry, which was then applied to a copper foil and dried at about 130 ° C for 2 hours. The anode was prepared by adding LiNiMnCoO ₂ / LiMnO ₂ , PVdF, and carbon black to NMP, coating it on aluminum foil, and drying it at about 130 ° C for 2 hours.

The two-phase electrolyte layer and the three-phase electrolyte layer were prepared to have a composition ratio of Table 1 below, and then prepared by adding 3% by weight of benzoin, which is an ultraviolet initiator, to PEGDMA.

TABLE 1

After coating the two-phase electrolyte on the surface of the prepared positive and negative electrodes, polymer crosslinking is performed by UV irradiation to form a polymer electrolyte layer having a viscoelastic structure. The three-phase electrolyte was coated on the positive electrode on which the two-phase electrolyte layer was formed, and the polymer crosslinked through UV irradiation to form a polymer electrolyte layer having a viscoelastic structure. An electrode assembly was prepared by laminating a cathode and an anode on which the electrolyte layer was formed, and then inserting the electrolyte assembly into a pouch to prepare a secondary battery.

&Lt; Comparative Example 1 &

An olefin-based porous separator was inserted between the positive electrode and the negative electrode according to Example 1, and a liquid electrolyte was further injected to prepare a secondary battery.

<Experimental Example 1>

The secondary battery prepared in Example 1 was evaluated for battery characteristics without any additional impregnation process.

The charge was maintained at a constant voltage (CV) of 4.2 V after the constant current (CC) was charged to 4.2 V at a current density of 0.1 C at the time of charging. When the current density reached 0.05 C, charging was terminated. The discharge was completed in the CC mode up to 2.5 V at a current density of 0.1 C at discharge. Charging and discharging were repeated 50 times under the same conditions.

Although the discharge profile of the secondary battery as described above did not add a separate electrolyte and did not undergo a separate impregnation process, it showed excellent discharge characteristics and capacity implementation rate.

The first charge and discharge profile and cycle life characteristics of the secondary battery of Example 1 are shown in FIGS. 4 and 5, respectively. Through this, it was confirmed that the intrinsic battery material properties of the battery in which the multilayer polymer electrolyte was inserted. In addition, the cycle life characteristics, it was confirmed that the stable performance without fading. Therefore, it was confirmed that the processability can be improved by shortening the wetting time of the electrolyte using the electrolyte layer coating.

<Experimental Example 2>

The secondary batteries prepared in Example 1 and Comparative Example 1 were evaluated for battery characteristics without any additional impregnation process. Discharge capacities shown during the first charge and discharge are shown in Table 2 below.

<Table 2>

Referring to Table 2, the results of evaluating the charge and discharge characteristics of the battery of Example 1 and Comparative Example 1 without the electrolyte solution impregnation process. It can be seen that the battery of Example 1 exhibits a higher discharge capacity than the battery of Comparative Example 1 at an actual 1 ^st discharge capacity and that the capacity implementation rate is superior to the theoretical capacity (17 mAh).

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 (27)

The positive electrode, the negative electrode, and the separation layer located between the positive electrode and the negative electrode have an integral structure,
Wherein,
At least one two-phase electrolyte comprising a liquid component including an ionic salt and a polymer matrix in which the linear polymer and the crosslinked polymer form a viscoelastic structure in a state in which the liquid component is embedded; And
A liquid matrix comprising an ionic salt, a solid component for supporting a separation layer between an anode and a cathode, and a polymer matrix in which a linear polymer and a crosslinked polymer form a viscoelastic structure in a state in which the liquid component and the solid component are embedded. One or more three-phase electrolytes comprising;
Consists of a multi-layer structure including
The polymer matrix is bonded to the positive electrode or the negative electrode,
Wherein a part of the liquid phase component of the separation layer flows into the electrode during fabrication of the electrode assembly. The method of claim 1, wherein the viscoelastic structure is a unitary electrode assembly, characterized in that the independent gels (gel) made of crosslinked polymer in the state in which the liquid component is impregnated physically interconnected by the linear polymer. The unitary electrode assembly of claim 2, wherein the linear polymers have a physical connection structure in which a part thereof penetrates the gel of the crosslinked polymers. The integrated electrode assembly according to claim 1, wherein a part of the liquid component of the separation layer flows into the electrode by a pressing process. The method of claim 1, wherein the ratio of the linear polymer and the crosslinked polymer in the total composition of the separation layer is an integral electrode assembly, characterized in that 1: 1 to 9: 8 by weight. The integrated electrode assembly according to claim 1, wherein the liquid component is an electrolyte solution containing an ionic salt. 7. The integrated electrode assembly of claim 6, wherein the ionic salt is a lithium salt. The method of claim 7, wherein the lithium salt is 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 ₂ ) ₂ Nli, lithium chloroborane, lower aliphatic lithium carbonate and lithium tetraphenyl borate one-piece electrode assembly characterized in that at least one selected from the group consisting of. The method of claim 6, wherein the electrolyte is ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, gamma butyrolactone, sulfolane, methyl acetate and methyl propionate Integral electrode assembly, characterized in that at least one selected from the group consisting of. 2. The integrated electrode assembly of claim 1, wherein the solid phase component is a solid compound that is not reactive with lithium ions. 11. The integrated electrode assembly of claim 10, wherein the solid compound is at least one selected from the group consisting of ion conductive ceramics, oxides, nitrides, and carbides that are not reactive with lithium ions. 12. The integrated electrode assembly of claim 11, wherein the oxide that is not reactive with lithium ions is at least one selected from the group consisting of MgO, TiO ₂ (Rutile), and Al ₂ O ₃ . The integrated electrode assembly of claim 1, wherein the linear polymer is at least one selected from the group consisting of a polyoxide-based non-crosslinked polymer and a polar noncrosslinked polymer. The integrated electrode assembly of claim 13, wherein the polyoxide-based non-crosslinked polymer is at least one selected from the group consisting of Poly (ethylene oxide), Poly (propylene oxide), Poly (oxymethylene), and Poly (dimethylsiloxane). . The method of claim 13, wherein the polar non-crosslinked polymer is Polyacrylonitrile, Poly (methyl methacrylate), Poly (vinyl chloride), Poly (vinylidene fluoride), Poly (vinylidenefluoride-co-hexafluoropropylene), Poly (ethylene imine) and Poly (p). -phenylene terephthalamide) one-piece electrode assembly, characterized in that at least one selected from the group consisting of. The method of claim 1, wherein the crosslinked polymer is a polymer of a monomer having two or more functional groups or a copolymer of a monomer having two or more functional groups and a polar monomer having one functional group. The method of claim 16, wherein the monomer having two or more functional groups is trimethylolpropane ethoxylate triacrylate (polymethylolpropane ethoxylate triacrylate), polyethylene glycol dimethacrylate (polyethylene glycol dimethacrylate), polyethylene glycol diacrylate (polyethylene) glycol diacrylate, divinylbenzene, polyester dimethacrylate, divinylether, trimethylolpropane, trimethylolpropane trimethacrylate, and ethoxylated bisphenol A dimetha Integral electrode assembly, characterized in that at least one selected from the group consisting of ethoxylated bis phenol A dimethacrylate. The method of claim 16, wherein the polar monomer having one functional group is methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, ethylene glycol methyl ether acrylate, ethylene glycol methyl ether meta Integral electrode assembly, characterized in that at least one selected from the group consisting of acrylate, acrylonitrile, vinyl acetate, vinyl chloride, and vinyl fluoride. The integrated electrode assembly of claim 1, wherein the separation layer comprises two layers of a two-phase electrolyte and a three-phase electrolyte. The integrated electrode assembly according to claim 1, wherein the separation layer is composed of three layers of two-phase electrolytes / 3 phase electrolytes / 2 phase electrolytes. The integrated electrode assembly according to claim 1, wherein the separation layer comprises three layers of a three-phase electrolyte / a two-phase electrolyte / a three-phase electrolyte. A method of manufacturing an integral electrode assembly according to claim 1,
(1) a process for preparing a mixture for a two- or three-phase electrolyte by uniformly mixing a linear polymer, a monomer component for a crosslinking polymer, a liquid component comprising an ionic salt, a polymerization initiator and optionally a solid phase component;
(2) coating the two-phase or three-phase mixture on one electrode;
(3) a step of forming a two-phase or three-phase electrolyte layer by performing a polymerization reaction by UV irradiation or application of heat;
(4) repeating steps (2) and (3) on the two-phase or three-phase electrolyte layer to form a separation layer comprising a plurality of electrolyte layers; And
(5) placing and pressing the corresponding electrode on the separation layer;
Wherein the electrode assembly includes a first electrode and a second electrode. A lithium secondary battery comprising an integrated electrode assembly according to any one of claims 1 to 21. A battery module comprising the lithium secondary battery according to claim 23 as a unit cell. A battery pack comprising a battery module according to claim 24. The battery pack as claimed in claim 25, wherein the battery pack is used as a power source for medium and large devices. 27. The battery pack as claimed in claim 26, wherein the medium-large device is an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a system for power storage.

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