KR101428710B1 - Electrode Assembly and Secondary Battery having the Same - Google Patents

Abstract

The present invention provides a secondary battery comprising a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, an electrode assembly including a separator for separating the positive electrode and the negative electrode, and an electrolyte, Wherein the separator comprises a porous film formed by bonding a ceramic material with a binder, and a secondary battery having the electrode assembly.

Accordingly, the present invention can provide a secondary battery having improved high-rate charge / discharge characteristics when the ceramic powder has a small particle size, by inhibiting deterioration of battery performance by corroding metal on the inner wall of the battery can by strong acid such as HF.

HMDS, Ceramic, Corrosion

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode assembly and a secondary battery having the electrode assembly. More particularly, the present invention relates to a secondary battery having suppressed cell corrosion and excellent charging / discharging characteristics.

BACKGROUND ART [0002] With the recent progress in miniaturization and weight reduction of portable electronic devices, there is an increasing need for miniaturization and high capacity of batteries used as driving power sources. Particularly, the lithium secondary battery has a working voltage of 3.6 V or higher, which is three times higher than a nickel-cadmium battery or a nickel-hydrogen battery which is widely used as a power source for portable electronic devices, and is rapidly expanded in terms of high energy density per unit weight There is a trend.

The lithium secondary battery generates electric energy by oxidation and reduction reactions when lithium ions are intercalated / deintercalated at the positive electrode and the negative electrode. The lithium secondary battery is manufactured by using a material capable of reversibly intercalating / deintercalating lithium ions as an active material for the positive electrode and the negative electrode, and filling an organic electrolytic solution or a polymer electrolyte between the positive electrode and the negative electrode.

The lithium secondary battery includes an electrode assembly in which a negative electrode plate and a positive electrode plate are wound in a predetermined form, for example, in a jelly-roll form with a separator interposed therebetween, a can containing the electrode assembly and the electrolyte, And a cap assembly assembled on the upper part.

As the conventional separator, a polyolefin-based microporous polymer membrane such as polypropylene or polyethylene or a multi-layer film thereof is usually used. However, such a polyolefin separator is in the form of sheet or film, And the sheet-like separator shrinks as well as the pores of the porous film due to heat generated by the sheet-shaped separator.

Therefore, when the sheet-like separator shrinks due to internal heat generation of the battery and shrinks, the separator is shrunk to cause direct contact between the positive electrode and the negative electrode, resulting in ignition, rupture and explosion.

Thus, by the combination of the ceramic material and the binder of the silica (SiO _2), alumina (Al ₂ O _3), zirconium oxide (ZrO _2), titanium oxide (TiO ₂₎ in order to compensate for the problem of the separator on the above film There has been actively studied a ceramic separator for applying a porous membrane as a separator.

However, in order to completely prevent the internal short circuit by removing the conventional separator on the film and only the porous film including the ceramic material, the porous film layer containing the ceramic material must be more compact.

For this purpose, ceramic powder particles must be made small in nano size. When the ceramic powder particles are made smaller, the specific surface area becomes larger.

In addition, when a ceramic powder having a high moisture content is present in the battery, it reacts with a lithium salt such as LiPF ₆ or LiBF ₄ in the electrolyte to form a strong acid of HF. When HF is generated, The metal on the inner wall is corroded to deteriorate the battery performance.

In addition, since the surface of the ceramic particles with a high moisture content is negatively charged by the OH ^- group or O ^{2 -} group in H ₂ O, the lithium ions are attracted and held to move lithium ions through the pores of the ceramic powder And the high rate charge / discharge characteristic is deteriorated.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems and disadvantages of the prior art, and it is an object of the present invention to suppress the deterioration of battery performance by corroding metal on the inner wall of a battery can by strong acid such as HF produced by reaction of ceramic powder with electrolyte SUMMARY OF THE INVENTION

Another object of the present invention is to provide a secondary battery having improved high rate charging / discharging characteristics when the ceramic powder has a small particle diameter.

The present invention relates to a positive electrode comprising a positive electrode active material layer; A negative electrode having a negative electrode active material layer; A separator for separating the anode and the cathode; And a Si-containing material layer formed on the separator, wherein the separator comprises a porous film formed by bonding a ceramic material with a binder.

The present invention also provides a secondary battery comprising a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, an electrode assembly including a separator for separating the positive electrode and the negative electrode, and an electrolyte, And a porous layer formed by bonding a ceramic material and a binder to the separator, wherein the separator comprises a Si-containing material layer.

The present invention also provides an electrode assembly and a secondary battery comprising the same, wherein the Si-containing material layer is a hexamethyl disilazane (HMDS) compound represented by the following formula (1).

[Chemical Formula 1]

Further, the present invention is characterized in that the ceramic material is made of at least one material selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ) and titanium oxide (TiO ₂ ) And a secondary battery having the electrode assembly.

Also, the present invention provides an electrode assembly and a secondary battery having the same, wherein the ceramic material has a particle diameter (D50) of more than 0 and less than or equal to 0.8 m.

Therefore, the electrode assembly of the present invention and the secondary battery having the same have the effect of inhibiting deterioration of the battery performance by corroding the metal on the inner wall of the battery can by strong acid such as HF.

Further, the present invention has an effect of providing a secondary battery having improved high rate charging / discharging characteristics when the ceramic powder has a small particle diameter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

An electrode assembly including the separator of the present invention and a secondary battery having the same will now be described.

The separator of the present invention comprises a porous film formed by bonding a ceramic material and a binder. The ceramic material and the binder are mixed with a solvent to prepare a paste, and then the paste is used to form a porous film .

The porous membrane may serve as a film-like separator such as a conventional polyethylene (PE) or polypropylene (PP).

The ceramic material is at least one material may be used which is selected from the group consisting of silica (SiO _2), alumina (Al ₂ O _3), zirconium oxide (ZrO _2), titanium oxide (TiO _2), In addition, zirconium, Aluminum, silicon, and titanium, respectively, of an insulating nitride, hydroxide, ketonide, or a mixture of such compounds may be used. At this time, the limitation of insulating nitride is mentioned because titanium nitride (TiN) etc. have conductivity and are not suitable as the ceramic material of the present invention.

At this time, it is preferable that the particle diameter (D50) of the ceramic material is more than 0 and not more than 0.8 mu m.

When the particle diameter (D50) of the ceramic material is more than 0.8 mu m, the moisture content is not large, so that the high rate charging / discharging characteristics of the battery are not significantly deteriorated. However, since the porosity of the porous film layer containing the ceramic material is low, There is a problem that can not be completely prevented.

As the binder, a synthetic rubber type latex binder or an acrylic rubber having a crosslinked structure may be used.

The synthetic rubber latex type binder may be at least one selected from the group consisting of styrene butadiene rubber latex, nitrile butadiene rubber latex, methyl methacrylate butadiene rubber latex, chloroprene rubber latex, carboxy modified styrene butadiene rubber latex and modified polyorganosiloxane latex And at least one selected from the group consisting of The polymer latex is preferably an aqueous dispersion. The content of the polymer latex is preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the electrode active material. When the amount is less than 0.1 part by weight, If the amount is more than 20 parts by weight, there is a possibility that the battery characteristics may be adversely affected.

The acrylic rubber having a crosslinked structure may be formed by a crosslinking reaction between a polymer or copolymer of an acrylic main monomer and a crosslinkable comonomer. When a polymer or copolymer of an acrylic main monomer is used, the bonding structure is weak and it tends to be broken. However, if a crosslinkable monomer is added to a polymer or copolymer of an acrylic main monomer, the polymer or copolymer of the acrylic main monomer It can be combined with the structure to make a more rigid net structure. The polymer having such a net structure is less likely to swell in a solvent as the degree of crosslinking increases. The acrylic rubber binder having the crosslinked structure may have a three-dimensional crosslinked structure having 2 to 10 crosslinking points, preferably 4 to 5 crosslinking points, per 10,000 molecular weight units of the main chain molecule. Therefore, the acrylic rubber having the crosslinked structure of the present invention may have swelling resistance that does not swell when the electrolytic solution is humidified.

An acrylic rubber binder having a crosslinking structure in which the decomposition temperature is 1000 ° C or higher and the decomposition temperature is 250 ° C or higher is used because of inherent characteristics of the ceramic material and thus a battery having high heat resistance can be obtained and the stability against the internal short circuit is improved .

Examples of the acrylic main monomer include methoxymethyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, buthoxyethylacrylate, methoxyethoxyethyl acrylate, Alkoxyalkyl acrylate selected from the group consisting of methoxyethoxyethyl acrylate and dicyclopentenyloxyethyl acrylate; Vinyl acetate, vinyl methacrylate, vinyl acrylate, allyl methacrylate, 1,1-dimethylpropenyl methacrylate, 1,1-dimethylacrylate, Dimethylpropenyl acrylate, 3,3-dimethylbutenyl methacrylate, 3,3-dimethylbutenyl acrylate, 3,3-dimethylbutenyl acrylate, Alkenyl acrylate or alkenyl methacrylate; An unsaturated dicarboxylic acid ester selected from divinyl itaconate, divinyl maleate, and the like; A vinyl group-containing ether selected from vinyl 1,1-dimethylpropenyl ether and vinyl 3,3-dimethylbutenyl ether; 1-acryloyloxy-1-phenylethene; And methyl methacrylate can be used.

Examples of the crosslinkable comonomer include 2-ethylhexyl acrylate, methyl acrylate, ethyl acrylate, propyl acrylate, buthyl acrylate, An alkyl acrylate selected from isopropyl acrylate, isopropyl acrylate, isopropyl acrylate, butyl acrylate, butyl acrylate, isopropyl acrylate, butyl acrylate, Alkenyl chloroacetate; Glycidyl group-containing esters or ethers selected from glycidyl acrylate, vinyl glycidyl ether, and acryl glycidyl ether; An unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid and maleic acid; 2-chloroethyl vinyl ether; Chloromethyl styrene; And acrylonitrile may be used in combination.

Next, an electrode assembly including a separator of the present invention and a secondary battery having the separator include a Si-containing material layer on a porous film layer formed by binding the ceramic material with a binder.

At this time, the Si-containing material layer includes a compound represented by the following formula (1).

[Chemical Formula 1]

Wherein R 1, R 2 and R 3 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a substituted or unsubstituted amine group, -SH, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, A substituted or unsubstituted C1-C20 alkenyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C1-C20 alkyl group, of 6 to 30 aryloxy group, a represents a substituted or unsubstituted alkylcarbonyl group having 1 to 20, X is -NR- (wherein R is a substituent, such as capable of hydrogen, an alkyl group), -O-, -SO ₃ -, A substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms, a substituted or unsubstituted silanylene group, a substituted or unsubstituted arylene group having 6 to 30 carbon atoms, a substituted Or an unsubstituted peptyl group, A substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryl group, A substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C1-C10 silanyl group, or a substituted or unsubstituted C6-C20 aryl group.

As the compound of the above formula (1), a compound of the following formula (2) is preferable

(2)

(Wherein R1, R2, R3 and X are as defined above)

As the compound of formula (1), a compound of formula (3) is preferable.

(3)

Wherein R 1, R 2 and R 3 are as defined above and R 4, R 5 and R 6 are each independently a hydrogen atom, a halogen atom, a hydroxy group, a substituted or unsubstituted amine group, a substituted or unsubstituted thiol group, A substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, A substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, a substituted or unsubstituted alkylcarbonyl group having 1 to 20 carbon atoms, X 1 is -O-, -NH-, A substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms, or a substituted or unsubstituted arylene group having 6 to 30 carbon atoms.

The compound of Formula 1 is preferably a hexamethyl disilazane (HMDS) compound represented by Formula 4 below.

[Chemical Formula 4]

The HMDS (hexamethyl disilazane) compound reacts, for example, as follows.

First, it is reacted with water to form a capping reaction as shown in Reaction Scheme 1 below.

[Reaction Scheme 1]

(CH ₃ ) ₃ SiNHSi (CH ₃ ) ₃ + H ₂ O → (CH ₃ ) ₃ SiOSi (CH ₃ ) ₃ + NH ₃

When an acid is present, the reaction shown in the following Reaction Schemes 2 to 4 is carried out.

[Reaction Scheme 2]

_{(CH 3) 3 SiNHSi (CH} 3) 3 + 2HCi → 2 (CH 3) 3 SiCl + NH 3

[Reaction Scheme 3]

_{(CH 3) 3 SiNHSi (CH} 3) 3 + 2HF → 2 (CH 3) 3 SiF + NH 3

[Reaction Scheme 4]

(CH ₃ ) ₃ SiNHSi (CH ₃ ) ₃ + 2H ₂ SO ₄ ? 2 (CH ₃ ) ₃ SiOSO ₃ H + NH ₃

Group or O ^{2 - -} the Si-containing material layer, the multi When applied to the surface of the porous layer Si Si-containing material layer is OH in the surface of the membrane layer being able to be capped (capping) group, through this, the negative It is possible to neutralize the ceramic powder charged with a positive charge or to charge it positively.

Accordingly, since the powders are not aggregated at the time of mixing the ceramic paste, the dispersibility is improved and it is possible to prevent the Li ⁺ ions from trapping on the surface of the ceramic powder, and as a result, the lithium cations can freely move between the pores of the ceramic powder The high rate charge / discharge performance can also be improved.

Also, as shown in Reaction Schemes 2 to 4, by removing HF, it is possible to prevent the risk of rupture and explosion due to the generation of O ₂ gas or the like by corrosion caused by HF or the like.

Next, an electrode assembly including the separator of the present invention and a secondary battery having the separator include a positive electrode and a negative electrode.

The positive electrode includes a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions. Typical examples of the positive electrode active material include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , or LiNi _{1 -} transition metal oxides such as _{x- y} Co _x M _y O ₂ (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ x + y ≤ 1, and M is a metal such as Al, Sr, Mg, La) However, the present invention does not limit the kind of the cathode active material.

The negative electrode includes a negative electrode active material capable of intercalating and deintercalating lithium ions. As the negative electrode active material, a carbon-based negative active material of a crystalline or amorphous carbon or a carbon composite may be used. The invention does not limit the kind of the negative electrode active material.

The positive electrode may include a positive electrode collector, and the positive electrode collector may include aluminum and an aluminum alloy. The negative electrode may include a negative electrode collector, and the negative electrode collector may include copper and a copper alloy. . The anode current collector and the anode current collector may be in the form of foil, film, sheet, punched, porous, foam or the like.

The electrode may be formed by stacking two electrodes in the state that the porous film of the present invention is formed on the anode, the cathode, or both, or after stacking and winding. As described above, since the porous membrane itself can serve as a separator, it is not necessary to provide a separate separator between the two electrodes.

There is a problem that the conventional film type separator shrinks at a high temperature, but the porous film does not shrink or melt. In the conventional polyolefin film separator, the peripheral shrinkage or melting of the peripheral film in addition to the portion damaged by the initial heat at the time of internal shorting causes a wider portion of the film separator to be burned out, resulting in a harder shot, The electrode with the porous membrane does not lead to a phenomenon that the short-circuited area is widened due to small damage in the area where the internal short-circuit occurs. In addition, the electrode with the porous film formed is kept at a constant voltage of 5 V to 6 V and a battery temperature of 100 ° C. or less by continuously consuming the overcharge current by causing a very small micro short, not a hard short, Stability can also be improved.

In particular, in the present invention is through an Si-containing material layer formed on the membrane layer, in the lithium cations can move freely through the pores of the ceramic powder, it is possible to improve the high rate charge-discharge performance, and also, O ₂ gas, by corrosion caused by HF It is possible to reduce the risk of rupture or explosion due to generation or the like.

Next, the secondary battery including the electrode assembly including the separator of the present invention includes an electrolytic solution.

The electrolyte according to the present invention includes a non-aqueous organic solvent, and the non-aqueous organic solvent may include a carbonate, an ester, an ether, or a ketone. Examples of the carbonate include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC) Propylene carbonate (PC), butylene carbonate (BC) and the like can be used as the ester. Examples of the ester include butyrolactone (BL), decanolide, valerolactone, mevalonolactone methacrylic acid, n-methyl acetate, n-ethyl acetate, n-propyl acetate and the like can be used. As the ether, dibutyl ether and the like can be used. As the ketone, polymethyl vinyl ketone However, the present invention is not limited to the kind of the non-aqueous organic solvent.

When the non-aqueous organic solvent is a carbonate-based organic solvent, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate. In this case, the cyclic carbonate and the chain carbonate are preferably used in a volume ratio of 1: 1 to 1: 9, more preferably 1: 1.5 to 1: 4. The electrolyte should preferably be mixed in the above volume ratio.

The electrolytic solution of the present invention may further contain an aromatic hydrocarbon-based organic solvent in the carbonate-based solvent. As the aromatic hydrocarbon-based organic solvent, an aromatic hydrocarbon-based compound may be used.

Specific examples of the aromatic hydrocarbon-based organic solvent include benzene, fluorobenzene, chlorobenzene, nitrobenzene, toluene, fluorotoluene, trifluorotoluene, xylene and the like. It is preferable that the volume ratio of the carbonate solvent / aromatic hydrocarbon solvent in the electrolyte containing the aromatic hydrocarbon organic solvent is 1: 1 to 30: 1. The electrolyte should preferably be mixed in the above volume ratio.

In addition, the electrolyte according to the present invention includes a lithium salt, and the lithium salt acts as a source of lithium ions in the battery to enable operation of a basic lithium battery. Examples thereof include LiPF ₆ , LiBF ₄ , LiSbF ₆ , _{LiAsF 6, LiClO 4, LiCF 3} SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, LiAlO 4, LiAlCl 4, LiN (C x F 2x +1 SO 2) (CyF _{2 x 1} SO ₂ ) (where x and y are natural numbers), and LiSO ₃ CF ₃ .

At this time, the concentration of the lithium salt can be used in the range of 0.6 to 2.0M, preferably in the range of 0.7 to 1.6M. If the concentration of the lithium salt is less than 0.6M, the conductivity of the electrolytic solution is lowered to deteriorate the performance of the electrolyte. If the concentration exceeds 2.0M, the viscosity of the electrolytic solution increases and the lithium ion mobility decreases.

The separator of the present invention as described above is interposed between the negative electrode and the positive electrode to form an electrode group by laminating or laminating it, and then inserted into a can or similar container, and then an electrolyte is injected to prepare a secondary battery .

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

[Example]

Four types of ceramic powder were selected: alpha alumina, zirconia, titanium barium titanate and silica. A ceramic paste was prepared by mixing ceramic powder, solvent and binder by particle size (D50) of the ceramic powder and then coated on the surface of the negative electrode active material layer to a thickness of 10 袖 m to prepare a battery.

The surface of the anode active material layer was surface-treated with HMDS (hexamethyl disilazane) compound, and a battery was fabricated by a general battery manufacturing process.

[Comparative Example]

Except that the surface of the negative electrode active material layer was not surface-treated with HMDS (hexamethyl disilazane) compound.

The high rate of charge (%) (3 C charge capacity / 0.2 C charge rate × 100) in the above Examples and Comparative Examples was measured. When the rate was 90% or more, "OK" was displayed.

Further, the high rate discharge amount (%) (3C charge capacity / 0.2C charge capacity × 100) in the above Examples and Comparative Examples was measured, and "OK" was shown when it was 90% or more and "NG" when it was less than 90%.

The results shown in Tables 1 to 4 were obtained for each ceramic powder type and particle size.

[Table 1]

division Alpha alumina
Particle size (D50) (nm) With HMDS surface treatment High rate charge (%) High rate discharge (%) Example 1 200 U OK OK Example 2 400 U OK OK Example 3 600 U OK OK Example 4 800 U OK OK Example 5 1000 U OK OK Example 6 1200 U OK OK Comparative Example 1 200 radish NG NG Comparative Example 2 400 radish NG NG Comparative Example 3 600 radish NG NG Comparative Example 4 800 radish NG NG Comparative Example 5 1000 radish OK OK Comparative Example 6 1200 radish OK OK

[Table 2]

division Zirconia
Particle size (D50) (nm) With HMDS surface treatment High rate charge (%) High rate discharge (%) Example 7 200 U OK OK Example 8 400 U OK OK Example 9 600 U OK OK Example 10 800 U OK OK Example 11 1000 U OK OK Example 12 1200 U OK OK Comparative Example 7 200 radish NG NG Comparative Example 8 400 radish NG NG Comparative Example 9 600 radish NG NG Comparative Example 10 800 radish NG NG Comparative Example 11 1000 radish OK OK Comparative Example 12 1200 radish OK OK

[Table 3]

division Barium titanate
Particle size (D50) (nm) With HMDS surface treatment High rate charge (%) High rate discharge (%) Example 13 200 U OK OK Example 14 400 U OK OK Example 15 600 U OK OK Example 16 800 U OK OK Example 17 1000 U OK OK Example 18 1200 U OK OK Comparative Example 13 200 radish NG NG Comparative Example 14 400 radish NG NG Comparative Example 15 600 radish NG NG Comparative Example 16 800 radish NG NG Comparative Example 17 1000 radish OK OK Comparative Example 18 1200 radish OK OK

[Table 4]

division Silica
Particle size (D50) (nm) With HMDS surface treatment High rate charge (%) High rate discharge (%) Example 19 200 U OK OK Example 20 400 U OK OK Example 21 600 U OK OK Example 22 800 U OK OK Example 23 1000 U OK OK Example 24 1200 U OK OK Comparative Example 19 200 radish NG NG Comparative Example 20 400 radish NG NG Comparative Example 21 600 radish NG NG Comparative Example 22 800 radish NG NG Comparative Example 23 1000 radish OK OK Comparative Example 24 1200 radish OK OK

Tables 1 to 4 show characteristics of particle sizes (D50) of alpha alumina, zirconia, titanium barium titanate and silica, respectively.

As can be seen from the above Comparative Examples 5, 6, 11, 12, 17, 18, 23 and 24, when the D50 value of the ceramic powder becomes large enough to exceed 0.8 μm, the moisture content of the ceramic powder is not large, There is no problem.

However, if the D50 value is less than 0.8 .mu.m regardless of the type of ceramics, the moisture content of the air increases and adversely affects the high rate charge / discharge characteristics of the battery. Therefore, in the case of the fine ceramic powder, By removing the negatively charged state by moisture, the high rate charge / discharge characteristic of the battery can be improved.

When the particle diameter (D50) of the ceramic material is more than 0.8 mu m, the moisture content is not large, so that the high rate charging / discharging characteristics of the battery are not significantly deteriorated. However, since the porosity of the porous film layer containing the ceramic material is low, There is a problem that can not be completely prevented.

Therefore, in the present invention, when the particle size (D50) of the ceramic material is more than 0 and not more than 0.8 탆, it is preferable that the porous material layer is made of a ceramic material and a binder.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

Claims (11)

A positive electrode having a positive electrode active material layer; A negative electrode having a negative electrode active material layer; A separator separating the anode and the cathode, the separator including a porous membrane formed by bonding a ceramic material and a binder; And And a Si-containing material layer formed on the separator, Wherein the Si-containing material layer is a hexamethyl disilazane (HMDS) compound represented by Formula 1 below. [Chemical Formula 1]

The method according to claim 1, And the Si-containing material layer is positioned between the negative active material layer and the separator. The method according to claim 1, The ceramic material is an electrode assembly which comprises at least one material selected from the group consisting of silica (SiO _2), alumina (Al ₂ O _3), zirconium oxide (ZrO ₂₎ and titanium oxide (TiO _2). The method according to claim 1, Wherein the ceramic material has a particle diameter (D50) of more than 0 and less than or equal to 0.8 占 퐉. The method according to claim 1, Wherein the binder is a synthetic rubber type latex binder or an acrylic rubber having a crosslinked structure. A secondary battery comprising an electrode assembly and an electrolyte, The electrode assembly includes an anode, a cathode, a separator separating the anode and the cathode, and a Si-containing material layer formed on the separator, Wherein the separator comprises a porous film formed by binding a ceramic material with a binder, Wherein the Si-containing material layer is a hexamethyl disilazane (HMDS) compound represented by the following formula (1). [Chemical Formula 1]

The method according to claim 6, Wherein the negative electrode has a negative electrode active material layer, and the Si-containing material layer is positioned on the negative active material layer. The method according to claim 6, The ceramic materials are silica (SiO _2), alumina (Al ₂ O _3), zirconium oxide (ZrO ₂₎ and titanium oxide secondary battery which comprises at least one material selected from the group consisting of (TiO _2). The method according to claim 6, Wherein the ceramic material has a particle diameter (D50) of more than 0 and not more than 0.8 mu m. The method according to claim 6, Wherein the binder is a synthetic rubber-based latex binder or an acrylic rubber having a crosslinked structure. The method according to claim 6, Wherein the electrolyte solution comprises a non-aqueous organic solvent and a lithium salt.