KR101856830B1 - Electrode Assembly Comprising Separator Coated with Lithium or Lithium Compound and Method for Preparing the Same - Google Patents

Abstract

The present invention relates to an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the separator is provided with a lithium ion battery for compensating irreversible capacity of the negative electrode active material, And a lithium compound releasing lithium from the lithium compound.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode assembly including a separator coated with a lithium or lithium compound coating layer, and a method of manufacturing the same. 2. Description of the Related Art Electrode Assembly Comprising Separator Coated with Lithium or Lithium Compound Coating Layer

The present invention relates to an electrode assembly, and more particularly, to an electrode assembly including a separator coated with a coating layer containing lithium or a lithium compound to compensate an irreversible capacity of a negative electrode active material.

2. Description of the Related Art As technology development and demand for mobile devices such as portable computers, portable telephones, smart pads, and wearable devices have increased, the demand for secondary batteries as energy sources has been rapidly increasing, and the high energy density and operating potential A lithium secondary battery having a long cycle life and low self-discharge rate has been extensively studied, and it has been commercialized and widely used.

Such a lithium secondary battery has a structure in which an electrolyte including a lithium salt is impregnated in an electrode assembly having a porous separator interposed between a positive electrode and a negative electrode coated with an electrode active material on a current collector.

Lithium-containing cobalt oxide (LiCoO ₂ ) is mainly used as the positive electrode active material of the lithium secondary battery, and lithium-containing manganese oxide such as LiMn ₂ O _{4 having a} spinel crystal structure and lithium-containing nickel oxide (LiNiO ₂ ) are also used .

The theoretical specific capacity of pure silicon (Si) is maximum 4200 mAh / g, and the graphite carbon of 372 mAh / g. Therefore, a lithium secondary battery using the above-mentioned Si-based active material attracts a lot of attention, and a part of the electrode is mixed with a carbon material.

However, the Si-based active material as described above has a high irreversible capacity, which can negatively affect the capacity of the battery due to the consumption of lithium ions. Also, as the number of cycles increases, lithium ions are consumed, .

Therefore, when an electrode is manufactured using an active material having a high irreversible capacity, a pre-lithiation process should be included so that lithium can be inserted into the irreversible capacity portion. However, such a pre- There is a danger that there is a risk, a process is complicated, and an excessive cost is incurred.

Therefore, a need exists for a technique capable of solving such a problem.

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.

Specifically, an object of the present invention is to provide an electrode assembly having a separator coated with a coating layer containing lithium or a lithium compound that compensates for an irreversible capacity of a negative electrode active material, and is excellent in capacity characteristics and life characteristics.

It is also an object of the present invention to provide a method of manufacturing an electrode assembly for manufacturing a battery having a high initial efficiency without a pre-lithization process.

According to an aspect of the present invention, there is provided an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,

The entire or a part of the separation membrane is coated with a coating layer containing lithium (Li) for compensating irreversible capacity of the negative electrode active material or a lithium compound for discharging lithium in a charging and discharging process of the battery cell.

That is, since the electrode assembly according to the present invention is coated with a coating layer containing lithium or a lithium compound on the separator, even when an electrode active material having a high irreversible capacity is used, initial efficiency improvement and cycle life .

When the lithium secondary battery is charged, the lithium ions of the positive electrode active material are released and inserted into the negative electrode layer, and lithium ions in the negative electrode layer are reversely inserted into the positive electrode active material during discharge.

As described above, the theoretical specific capacity of pure silicon is as high as 4200 mAh / g, and a very high capacity can be secured. However, irreversible portion in which lithium ions inserted into the silicon layer are not reversibly discharged during the charging process has a big problem.

Therefore, it is common that a silicon anode material is used after performing a pre-lithization process in which lithium is doped. Such a pre-lithization process has a problem in that it is inexpensive in cost and safety.

Accordingly, the present invention provides an electrode assembly that is excellent in initial efficiency and capacity characteristics while omitting the lithium ionization process by applying a lithium compound to the separator to discharge lithium in the charging or discharging process of the lithium or battery cell.

The negative electrode is not particularly limited as long as the capacity is large and the irreversible capacity is large, but may include a Si-based negative electrode active material.

Specifically, the Si-based anode active material may be at least one selected from the group consisting of silicon, silicon oxide, silicon composite, and silicon alloy.

The specific capacity of the Si-based anode active material is as high as 3200 mAh / g to 4200 mAh / g, and may further include a carbonaceous material depending on the case.

Specifically, the carbon-based material may be at least one selected from the group consisting of graphite, pitch, soft carbon, and hard carbon.

The carbon-based material may be included in an amount of 0 to 80 wt% based on the total weight of the negative electrode active material, and when the carbon-based material is included in the amount of 0 wt%, 100 wt% of the Si-based negative active material is used.

However, in this case, it is difficult to exhibit the advantages of the present invention to compensate for the high capacity characteristics and the irreversible capacity of the Si-based negative electrode active material, which is not preferable.

As described above, the electrode assembly according to the present invention provides a battery having a coating layer containing lithium or a lithium compound that compensates for the irreversible portion of the negative electrode active material having a large irreversible capacity, and is coated on the separator to provide a battery having excellent lifetime and cycle characteristics .

Therefore, it is preferable that the coating layer is coated on the separation membrane facing the cathode.

The electrode assembly has a structure in which the structure of the anode / separator / cathode / separator is repeated. That is, the electrodes located on both sides of the separator have polarities opposite to each other.

At this time, it is preferable that the electrode assembly according to the present invention has a coating layer formed on a portion of the separator facing the negative electrode so as to directly compensate the irreversible capacity of the negative electrode.

The thickness of the coating layer may be from 0.001 mu m to 100 mu m, and more specifically from 0.01 mu m to 50 mu m, and more specifically from 0.1 mu m to 10 mu m.

If the thickness of the coating layer is too thick, the volume of the separation membrane which does not contribute to the capacity of the battery may increase, the capacity per unit volume may decrease, and the overall capacity may be deteriorated.

On the other hand, lithium (Li) contained in the coating layer is an alkali metal and is very reactive. Therefore, it is likely to be oxidized under ordinary atmospheric conditions, and when it comes into contact with water, it is oxidized rapidly to generate hydrogen.

Therefore, the lithium metal should be stored in an inert or inert atmosphere, and it is preferable to use a vacuum deposition method or the like when forming the coating layer.

In the case of a lithium compound, it is a substance having a low reactivity to lithium metal and is relatively easy to handle. A solution or slurry can be prepared and a coating layer can be formed by a spray method, a coating method, a dip coating method or the like.

It is preferable that the lithium compound is activated in the initial charge / discharge process of the battery to compensate for the irreversible capacity and not in the subsequent charge / discharge process. Therefore, it is preferable that the lithium compound is different from the cathode active material, specifically, has an operating voltage lower than the operating voltage of the cathode active material.

In one specific example, the lithium compound may have an operating voltage of 1.0 V to 2.5 V relative to Li within a range smaller than the operating voltage of the cathode active material, and more specifically, may have an operating voltage of 1.2 to 2.4 V have.

Therefore, the lithium compound participates in the reaction only at the time of initial charging, and does not participate in the reaction at the time of discharging, thereby reducing the irreversible capacity of the cathode.

On the other hand, in the initial charging / discharging process, the voltage can be designed within the above range so that only the lithium compound can participate in the reaction.

The coating layer containing lithium or a lithium compound is applied to the separator and assembled together with the positive electrode and the negative electrode to produce an electrode assembly. Hereinafter, a method of manufacturing the electrode assembly will be described.

The manufacturing method is a method of manufacturing an electrode assembly according to the present invention,

(i) preparing a polyolefin-based porous substrate;

(ii) preparing a separator by coating a lithium or lithium compound on one surface or both surfaces of the polyolefin-based porous substrate; And

(iii) laminating and assembling a positive electrode-separator-negative electrode so that a surface coated with lithium or a lithium compound faces the negative electrode;

And a control unit.

As described above, it is preferable that the negative electrode contains a Si-based negative active material.

First, in step (i), a polyolefin-based porous substrate is prepared.

The polyolefin-based porous substrate is not particularly limited as long as it has chemical resistance and is excellent in lithium ion permeability, and a known separation membrane can be used as it is.

Representative examples of commercially available membranes include Celgard ^TM 2400, 2300 (manufactured by Hoechest Celanese Corp.), polypropylene membrane (manufactured by Ube Industries Ltd. or Pall RAI), polyethylene series (Tonen or Entek) And the like may be used, but the present invention is not limited thereto.

Next, in step (ii), lithium or a lithium compound is coated on one side or both sides of the prepared polyolefin-based porous substrate to prepare a separator.

This coating process (ii) can be carried out by chemical vapor deposition (CVD) or physical vapor deposition (PVD).

Particularly, when lithium metal is contained in the coating layer of the separation membrane, it is preferable to perform the deposition by the above-mentioned vapor deposition method, and more specifically, it is more preferably performed by physical vapor deposition such as vacuum deposition.

The process (ii) may be performed while the plasma is being applied.

In addition, the step (ii) may be carried out in an inert gas atmosphere.

Specifically, the deposition process is performed by making the chamber in which the deposition takes place into a vacuum state and ionizing the inert gas introduced into the chamber by applying a high voltage.

The ionized inert gas forms a plasma between the polyolefin-based substrate and the plate, and the impact of the ionized inert gas releases lithium metal from the plate and is deposited on the polyolefin-based substrate.

Since the lithium metal deposited on the polyolefin based substrate may still be oxidized, it may further include a step (ii ') of storing the separator in an inert gas atmosphere between steps (ii) and (iii).

The inert gas is a stable gas that does not cause a well to the other elements and the response, in particular, argon (Ar), helium (He), nitrogen (N _2), or carbon dioxide (CO ₂₎ either or both selected from the group consisting of Or more, and argon is generally used.

Meanwhile, the step (ii) may be performed by applying a coating solution containing a lithium compound which releases lithium in the charging and discharging process of the battery cell to the polyolefin-based porous substrate to compensate the irreversible capacity of the negative electrode active material.

By forming the coating layer, the pores of the porous polyolefin-based substrate may be covered with lithium or a lithium compound, and blocking of the pores may lower the movement of lithium ions during the charge-discharge process.

Therefore, it is preferable that the separation membrane produced in the process (ii) has a porosity of 25% to 80%.

The porosity can be achieved by various methods such as adjusting the coating amount of the coating layer or forming a coating layer on only a part of the separation layer as a porosity of the entire separation membrane including the polyolefin substrate and the coating layer.

Finally, in the step (iii), the cathode-separator-cathode is laminated and assembled so that the surface coated with lithium or a lithium compound faces the cathode.

The structure of the assembled electrode assembly is not particularly limited, and may be a jelly-roll type electrode assembly in which long sheet-type positive electrodes and negative electrodes are wound with a separator interposed therebetween, a plurality of positive electrodes and negative electrodes cut in a predetermined unit, Stacked type electrode assembly in which unit cells stacked in a state in which a separator is interposed between a positive electrode and a negative electrode of a predetermined unit are sequentially wound in a state of being placed on a separator film, .

The electrode assembly includes a positive electrode and a negative electrode together with the separator prepared in steps (i) and (ii).

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 wt% to 30 wt% 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 that 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 wt% 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.

On the other hand, the negative electrode is manufactured by applying and drying a negative electrode active material on a negative electrode collector, and may optionally further include the components as described above.

As described above, the negative electrode active material is preferably a silicon (Si) -based active material, and the silicon based material has a high irreversible capacity and is generally subjected to preliminary lithium ionization treatment. However, Or a lithium compound is applied, so that a separate pre-lithization process is not required.

The present invention also provides a battery cell in which the electrode assembly is embedded in a battery case in a state of being impregnated with an electrolyte solution.

The electrolytic solution is composed of a polar organic electrolyte and a lithium salt. As the electrolytic solution, a non-aqueous liquid electrolyte, an organic solid electrolyte, and an inorganic solid electrolyte 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, 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 battery pack including at least one battery cell and a device including such a battery pack as a power source.

Typical examples of the device include, but are not limited to, a mobile phone, a notebook, a tablet PC, a wearable electronic device, an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or a power storage system.

Since the structure of the device and the method of manufacturing the device are well known in the art, a detailed description thereof will be omitted herein.

As described above, the electrode assembly according to the present invention has a coating layer containing lithium or a lithium compound which compensates for the irreversible capacity of the negative electrode active material is applied to the separator, thereby improving the low initial efficiency of the Si-based negative electrode, The electrode assemblies can be manufactured at a reduced manufacturing time.

Hereinafter, the content of the present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.

≪ Example 1 > (Coating layer thickness - 0.3 mu m)

Manufacture of anode

LiCoO ₂ was used as the positive electrode active material and 2.5 wt% of LiCoO ₂ , 2.5 wt% of Super-P (conductive agent) and 2.5 wt% of PVdF (binder) were added to NMP (N-methyl-2-pyrrolidone) The mixture slurry was prepared and then coated on an aluminum current collector, dried and pressed to prepare a positive electrode.

Cathode manufacturing

A negative electrode active material having an irreversible efficiency of 75% (charge capacity: 2000 mAh / g), 2.5 wt% of Super-P (conductive agent), 2 wt% of SBR (binder) (Thickener) was added to water as a solvent to prepare a negative electrode mixture slurry, followed by coating, drying and pressing on the copper current collector to prepare a negative electrode.

Preparation of Membrane

Lithium metal was deposited on one surface of a polyolefin porous separator (Celgard ^TM , triple layer polyolefin separator) by sputtering to prepare a separator having an average coating thickness of 0.3 μm.

Manufacture of batteries

An electrode assembly was prepared with a separator interposed between the positive and negative electrodes so that the coating layer of the prepared separator was adjacent to the negative electrode. The electrode assembly was inserted into the pouch and connected to lead wires, and a volume ratio of 1 M LiPF ₆ salt dissolved therein was 1: 1, a mixed solution of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) was injected into the electrolyte and sealed to prepare a pouch type lithium secondary battery.

Example 2 (Coating layer thickness - 1 占 퐉)

A lithium secondary battery was fabricated in the same manner as in Example 1, except that a separation membrane having a coating layer of an average thickness of 1 mu m was used.

≪ Example 3 > (average coating layer - 10 mu m)

A lithium secondary battery was fabricated in the same manner as in Example 1, except that a separator having a coating layer of 10 mu m in average thickness was used.

≪ Example 4 > (average coating layer - 20 mu m)

A lithium secondary battery was fabricated in the same manner as in Example 1, except that a separator having a coating layer of 20 mu m in average thickness was used.

Example 5 (Formation of lithium compound coating layer - 0.3 mu m)

Preparation of Membrane

A coating slurry was prepared by mixing a lithium molybdenum compound having an operating voltage of 2.4 V or less and a small amount of PVdF (binder) in a solvent NMP to prepare a coating slurry on one surface of a polyolefin porous separator (Celgard ^TM , triple layer polyolefin separator) And a coating film was formed so that the thickness of the coating layer was 0.3 mu m on average.

A lithium secondary battery was fabricated in the same manner as in Example 1, except that the separator thus prepared was used.

≪ Example 6 > (Coating layer thickness - 1 mu m)

A lithium secondary battery was fabricated in the same manner as in Example 5, except that a separation membrane having an average thickness of 1 占 퐉 of the coating layer was used.

≪ Example 7 > (average coating layer - 10 mu m)

A lithium secondary battery was fabricated in the same manner as in Example 5, except that a separation membrane having an average thickness of 10 mu m was used as the coating layer.

≪ Example 8 > (average of coating layer - 20 mu m)

A lithium secondary battery was fabricated in the same manner as in Example 5, except that a separation membrane having a coating layer of 20 mu m in average thickness was used.

≪ Comparative Example 1 &

A lithium secondary battery was fabricated in the same manner as in Example 1, except that a separation membrane in which a coating layer was not formed was used.

≪ Comparative Example 2 > (Si-based negative electrode subjected to pre-lithiation)

Cathode manufacturing

Lithium is doped in an inert atmosphere to an anode active material having an irreversible efficiency of 75% (charge capacity: 2000 mAh / g) as an anode including a SiO-based anode active material, thereby producing an anode material subjected to preliminary lithium ionization.

The negative electrode mixture slurry was prepared by adding 94 wt% of the negative electrode material, 2.5 wt% of Super-P (conductive agent), 2 wt% of SBR (binder) and 1.5 wt% of CMC (thickener) The negative electrode was prepared by coating, drying and pressing on the copper collector.

A lithium secondary battery was fabricated in the same manner as in Example 1, except that the negative electrode prepared above and the separator without a coating layer were used.

<Experimental Example 1>

The initial efficiencies and capacities of the lithium secondary batteries prepared in the above Examples and Comparative Examples were measured and shown in Table 1, respectively. The initial efficiency means the ratio of the reversible capacity in the first charge and discharge reaction.

Initial efficiency (%) Battery capacity (mAh) Example 1 87.2 1642 Example 2 86.0 1635 Example 3 85.5 1622 Example 4 84.2 1610 Example 5 83.9 1599 Example 6 83.3 1586 Example 7 83.0 1588 Example 8 80.0 1520 Comparative Example 1 75.0 1488 Comparative Example 2 83.1 1580

As shown in Table 1, Examples 1 to 4 of the present invention exhibit much higher initial efficiency than Comparative Example 1 using the lithium-deposited separator, and have an initial efficiency similar to that of Comparative Example 2.

On the other hand, Examples 5 to 8, in which the lithium molybdenum compound was applied, exhibited a somewhat lower initial efficiency as compared with Examples 1 to 4, but had significantly higher initial efficiency as compared with Comparative Example 1, .

This seems to be due to the fact that the lithium consumed in the Si-based anode material is compensated by Li deposited on the separator during the charging process, thereby reducing the irreversible part.

Battery Capacity It is also confirmed that Examples 1 to 8 are higher than Comparative Example 1, because the irreversible capacity decreases during the cell charging process due to Li deposited on the separator.

On the other hand, the comparative example 2 shows a capacity and initial efficiency similar to those of the example 7, but the preparation time is longer than that of the examples 1 to 8 because the lithium ionization process is performed as described above.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (20)

An electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode,
Wherein the separator is coated with a coating layer containing lithium (Li) that compensates for the irreversible capacity of the negative electrode active material or a lithium compound that releases lithium in a charging and discharging process of the battery cell,
The negative electrode includes a Si-based negative active material,
Wherein the thickness of the coating layer is in the range of 0.001 m to 100 m. delete The electrode assembly according to claim 1, wherein the Si based negative active material is at least one selected from the group consisting of silicon, silicon oxide, silicon composite, and silicon alloy. The electrode assembly according to claim 1, wherein the specific capacity of the Si-based negative electrode active material is 3200 mAh / g to 4200 mAh / g. The electrode assembly of claim 1, wherein the cathode further comprises a carbon-based material. The electrode assembly according to claim 5, wherein the carbon-based material is at least one selected from the group consisting of graphite, pitch, soft carbon, and hard carbon. The electrode assembly according to claim 1, wherein the coating layer is applied on a separation membrane facing the cathode. delete The electrode assembly according to claim 1, wherein the thickness of the coating layer is 0.01 탆 to 50 탆. 10. A method of manufacturing an electrode assembly according to any one of claims 1, 3, 7, and 9,
(i) preparing a polyolefin-based porous substrate;
(ii) preparing a separator by coating a lithium or lithium compound on one or both sides of the polyolefin-based porous substrate; And
(iii) laminating and assembling a positive electrode-separator-negative electrode so that a surface coated with lithium or a lithium compound faces the negative electrode;
&Lt; / RTI &gt; 11. The method according to claim 10, wherein the negative electrode comprises a Si-based negative active material. 11. The method of claim 10, wherein step (ii) is performed by chemical vapor deposition (CVD) or physical vapor deposition (PVD). The method according to claim 11, wherein the step (ii) is performed in a state in which the plasma is applied. 12. The method of claim 11, wherein step (ii) is performed in an inert gas atmosphere. The method according to claim 10, further comprising a step (ii ') of storing the separation membrane in an inert gas atmosphere between the step (ii) and the step (iii). 15. The method of claim 14, wherein said inert gas further comprises argon (Ar), helium (He), nitrogen (N _2), or carbon dioxide (CO ₂₎ is any one or more than one gas mixture selected from the group consisting of . [10] The method of claim 10, wherein the step (ii) is performed by applying a coating solution containing a lithium compound that releases lithium to the polyolefin-based porous substrate to charge the irreversible capacity of the negative electrode active material during charging and discharging of the battery cell . 11. The method of claim 10, wherein the separation membrane produced in step (ii) has a porosity of 25% to 80%. The battery cell according to any one of claims 1, 3, 7, and 9, wherein the electrode assembly is embedded in the battery case with the electrolyte solution impregnated therein. A battery pack comprising at least one battery cell according to claim 19.