KR101742609B1 - Electrode for a lithium secondary battery and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrode for a secondary battery, and more particularly, to an electrode for a lithium secondary battery comprising a current collector and an electrode active material layer formed on at least one side of the current collector, The present invention relates to an electrode for a secondary battery and a lithium secondary battery including the electrode.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrode for a lithium secondary battery, and a lithium secondary battery including the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to an electrode for a lithium secondary battery and a lithium secondary battery including the same.

2. Description of the Related Art Recently, compact and lightweight electric / electronic devices such as a mobile phone, a notebook computer, a camcorder and the like have been actively developed and produced. Such an electric / storage device can be operated in a place where a separate power source is not provided It has a built-in battery pack.

In addition, automobiles using motors such as hybrid vehicles (HV), electric vehicles (EV), and electric vehicles are being developed and produced, and battery packs capable of driving motors are also incorporated in such vehicles. The battery pack is provided with at least one battery for outputting a predetermined level of voltage for driving the electric / storage device or the automobile for a predetermined time.

Considering the economical aspect, recently, the battery pack employs a rechargeable / rechargeable secondary battery. The secondary battery is typically a nickel-cadmium (Ni-Cd) battery, a nickel-hydrogen (Ni-MH) battery, a lithium battery, or a lithium secondary battery such as a lithium ion battery.

Of these, lithium secondary batteries have been developed since the early 1970s, and lithium ion batteries using carbon as a cathode instead of lithium metal have been developed and commercialized in 1990. The battery has a cycle life of more than 500 cycles and a short charging time of 1 to 2 hours , Which is the most advanced secondary battery among the secondary batteries, and can be lightened by about 30 to 40% lighter than the nickel-hydrogen battery.

In addition, the lithium secondary battery has the highest unit cell voltage (3.0 to 3.7 V) among the existing secondary batteries, has a high energy density, has no memory effect, has a low degree of natural discharge even when not in use, , And portable electronic devices such as mobile phones. In addition, the frequency of use is increasing in the fields of automobiles and automobiles, automobiles, and aviation industries.

Such a lithium secondary battery is generally classified into a liquid electrolyte cell and a polymer electrolyte cell depending on the type of the electrolyte. A battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery.

On the other hand, in the case of a lithium secondary battery using a non-aqueous electrolyte, the ion mobility in the electrolyte deteriorates, and electrolyte impregnation of the electrode may not be accomplished in a short time. If the electrolytic solution impregnation is not carried out quickly, problems occur in the battery manufacturing process, and the life characteristics of the battery are deteriorated.

Therefore, in order to improve the electrolyte impregnation characteristics of the electrode, there have been attempts to inject the electrolyte under reduced pressure in the secondary cell manufacturing process, and to increase the amount of the electrolyte solution or to aging the electrolyte solution at a high temperature. However, The impregnation characteristics were not sufficiently improved.

Korean Patent No. 428971 discloses a method of impregnating an electrolytic solution under vacuum conditions to improve electrolyte impregnability. Since setting of the vacuum condition is a process which causes high cost, the manufacturing cost of the battery is greatly increased and the application to the actual manufacturing process is limited, so that an alternative to the above-mentioned problem can not be suggested.

Korea Patent No. 428971

An object of the present invention is to provide an electrode for a lithium secondary battery and a lithium secondary battery including the same, wherein the electrolyte impregnating property is improved and cycle characteristics are remarkably improved and the battery life is improved.

It is another object of the present invention to provide a secondary battery with improved insulation resistance.

It is another object of the present invention to provide a method for producing an electrode for a lithium secondary battery improved in electrolyte impregnation characteristics.

An electrode for a lithium secondary battery according to an embodiment of the present invention includes a current collector and an electrode active material layer formed on at least one surface of the current collector, and the electrode active material layer includes a porous barrier defining an active material application area.

In an electrode for a lithium secondary battery according to an embodiment of the present invention, the porous barrier may be arranged to pass through the center of the electrode active material layer.

The volume of the porous barrier rib in the electrode for a lithium secondary battery according to an embodiment of the present invention can be expressed by the following equation (1).

[Equation 1]

B is the volume of the porous barrier, C is the number of the electrode active material layers on which the porous barrier is formed, D is the density of the electrolyte, and E is the porosity of the porous barrier.

In the electrode for a lithium secondary battery according to an embodiment of the present invention, the bottom surface area of the porous barrier may be 5 to 30% of the total area of the electrode active material layer.

In the electrode for a lithium secondary battery according to an embodiment of the present invention, the water absorption amount of the porous partition wall may be 300 g / m 2 or more, and the height of the porous partition wall may be 5 to 200 탆.

The height of the porous barrier rib in the electrode for a lithium secondary battery according to an embodiment of the present invention may be the same as the thickness of the electrode active material layer.

In the electrode for a lithium secondary battery according to an embodiment of the present invention, the porous barrier may be at least one selected from the group consisting of nonwoven fabric, pulp and polymer foam, and the shape of the porous barrier may be lattice, polygonal or circular.

The electrode for a lithium secondary battery according to an embodiment of the present invention may be at least one of an anode and a cathode and may be usefully used in a lithium secondary battery including a separator interposed between the anode and the cathode and a nonaqueous electrolyte.

A method of manufacturing an electrode for a lithium secondary battery according to an embodiment of the present invention includes: attaching a porous barrier to at least one surface of an electrode current collector; And coating an electrode slurry on the electrode current collector having the porous barrier ribs to form an electrode active material layer partitioned by the barrier ribs.

In the method of manufacturing an electrode for a lithium secondary battery according to an embodiment of the present invention, the height of the porous barrier may be equal to the thickness of the electrode active material layer.

INDUSTRIAL APPLICABILITY The electrode for a lithium secondary battery of the present invention improves the electrolyte impregnation characteristics to improve cycle characteristics and improve insulation resistance.

In addition, the electrode for a lithium secondary battery of the present invention can additionally replenish an electrolyte, thereby improving the lifetime of the battery.

1 is a schematic cross-sectional view of an electrode for a lithium secondary battery according to an embodiment of the present invention.
2 is a schematic view illustrating an electrode for a lithium secondary battery according to an embodiment of the present invention.
3 is a schematic view illustrating a method of manufacturing an electrode for a lithium secondary battery according to an embodiment of the present invention.
4 is a graph showing the capacity retention rate according to the number of cycles of Example 1 and Comparative Example 1 according to an embodiment of the present invention.

An electrode for a lithium secondary battery comprising a current collector and an electrode active material layer formed on at least one side of the current collector, wherein the electrode active material layer includes a porous partition wall for partitioning the active material application region And an electrode for a secondary battery having improved cycle characteristics due to improved electrolyte impregnation characteristics.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. And shall not be construed as limited to what has been made.

Secondary battery electrode

<Electrode Active Material Layer>

The electrode of the lithium secondary battery formed by collectively coating the electrode slurry on the collector has insufficient electrolyte impregnability at the electrode (particularly at the center of the electrode), so that the electrolytic solution does not reach the active material particles of the electrode, The current is reduced due to non-smoothness and the cycle characteristics are deteriorated accordingly. In addition, if the impregnation of the electrolyte solution is not performed quickly, the productivity of the secondary battery is lowered.

Accordingly, the electrode for a lithium secondary battery of the present invention is formed by partitioning the electrode active material layer into porous barrier ribs.

FIG. 1 schematically shows a cross section of an electrode for a secondary battery according to an embodiment of the present invention, and FIG. 2 schematically shows an electrode for a lithium secondary battery according to an embodiment of the present invention.

The electrode 100 for a lithium secondary battery includes a current collector 10 and an electrode active material layer 20 formed on at least one side of the current collector. The electrode active material layer 20 includes an electrode active material region 30, And includes a porous partition wall 40.

The electrode slurry is collectively applied on the current collector and the electrode active material layer of the secondary battery subjected to the compression process for high capacity is densely formed so that the electrolyte can not reach the entire electrode active material particles even if the electrolyte solution is injected.

The electrode active material layer 20 of the present invention includes the porous partition wall 40 that separates the active material application region of the electrode active material layer 20 and can absorb the electrolytic solution so that the electrode active material layer on the bottom of the electrode active material layer Can reach.

Since the porous partition wall 40 is disposed to pass through the center portion of the electrode active material layer 20, the electrolyte solution can easily reach the central portion of the electrode where the impregnability of the electrolyte solution is particularly poor, and the impregnability of the electrode electrolyte solution can be remarkably improved have.

Further, since the porous partition wall 40 uses the secondary battery to decompose the electrolyte, the electrolyte can be further absorbed by the porous partition wall 40 even if the initially absorbed electrolyte is depleted, so that the electrolyte can be continuously supplied to the electrode The life of the battery can be improved.

Therefore, the electrode 100 for a lithium secondary battery according to the present invention includes the porous partition wall 40 to improve the electrolyte impregnation characteristics, thereby remarkably improving the cycle characteristics and further supplying the electrolyte solution, thereby improving the life of the battery . In addition, productivity of the secondary battery can be increased by increasing the rate of impregnation of the electrolyte solution.

Further, since the impregnated island of the electrolyte solution is improved, it is possible to prevent the excess electrolytic solution, which has not been impregnated, from flowing into the sealing part or the like, thereby improving the insulation resistance.

The volume of the porous partition wall 40 is not particularly limited and can be appropriately adjusted according to the type and use of the battery, the kind of the electrolytic solution, the kind of the porous partition wall, the use environment and the like.

For example, the volume of the porous partition wall 40 can be expressed by the following equation (1).

[Equation 1]

B is the volume of the porous barrier, C is the number of the electrode active material layers on which the porous barrier is formed, D is the density of the electrolyte, and E is the porosity of the porous barrier.

B is the volume of the porous partition wall, and can be obtained as the width, length, and height of the porous partition wall.

The lithium secondary battery includes a stack of unit cells, wherein the unit cell includes a positive electrode and a negative electrode formed by coating an electrode active material on at least one surface of an electrode collector, and a separator interposed between the positive electrode and the negative electrode. And C is the number of electrode active material layers on which the porous barrier ribs are formed. For example, when the number of stacked unit cells is 20, and the porous partition walls are attached to both surfaces of the electrode and the porous partition walls are attached to both the positive and negative electrodes, the number of the electrode active material layers having the porous partition walls is 20 * 2 * 2 80. &Lt; / RTI &gt;

D is the density of the electrolyte used, and E is the porosity. The percentage of the volume of the pores to the volume of the porous barrier is called porosity.

According to Equation (1) of the present invention, the volume of the porous barrier ribs, the number of the electrode active material layers having the porous barrier ribs, and the like can be designed according to the desired amount of liquid.

More specifically, the bottom surface area of the porous partition wall 40 may be 5 to 30% of the total area of the electrode active material layer 20, but is not limited thereto. The impregnation improving effect can be exhibited most excellently without decreasing the capacity of the battery in the above range and by increasing the loading amount of the electrode active material in the area of the electrode active material where the porous partition wall 40 does not exist, Can be offset. For example, the anode density may be 2.0 to 4.0 g / cm 3, and the cathode density may be 1.0 to 3.0 g / cm 3, but is not limited thereto.

The amount of water absorption of the porous partition wall 40 of the present invention is preferably 300 g / m 2 or more, and the upper limit is not particularly limited in terms of the effect of improving the impregnation of the electrolyte solution as the water absorption amount is larger.

The height of the porous partition wall 40 is not particularly limited but may be in the range of 5 to 200 탆. In order to facilitate the manufacturing process of the secondary battery and to deposit the electrolyte on the entire electrode, 20). The same thickness includes those which can be regarded as substantially equal in thickness.

The material of the porous partition wall 40 of the present invention is not particularly limited as being a porous material capable of absorbing an electrolyte, and examples thereof include nonwoven fabric, pulp, and polymer foam. The nonwoven fabric is preferable as the material of the porous partition wall 40 because it has less shrinkage due to heat and relatively large pores so that the electrolyte can be sufficiently faded and the electrolyte can be transferred to the surrounding electrodes.

The shape of the porous partition wall 40 of the present invention is not particularly limited and may be a lattice shape as shown in Fig. 2, or a polygonal shape or a circular shape. 3, and the polygon includes, for example, a triangle, a rectangle, a hexagon, an octagon, a cross, and the like. The rectangle includes a rectangle, a rhombus, and the like. do. It is preferable that the lattice type is used in view of improving the impregnation improvement effect at the center of the electrode while minimizing the reduction in the capacity of the battery.

As described above, the electrode 100 for a lithium secondary battery including the electrode active material layer 30 and the electrode active material layer 20 including the porous barrier 40 has improved impregnability of the electrolyte to improve the cycle characteristics of the secondary battery. And the electrolyte can be additionally replenished to the electrode, so that the life characteristic of the secondary battery can be improved.

In the present invention, the electrode slurry used for forming the active material application region of the electrode active material layer is not particularly limited and a conventionally used electrode slurry may be used. For example, an electrode slurry can be prepared by mixing and stirring a solvent, a binder, a conductive material, a dispersing material, etc., with each of the cathode active material and the anode active material.

The cathode active material is not particularly limited, and a material conventionally used as a cathode active material may be used. As a specific example, at least one selected from the group consisting of cobalt, manganese, and nickel and at least one compound oxide of lithium are preferable, and typical examples thereof include a lithium-containing compound having a partition wall as described below.

Li _x Mn _{1 - y} M _y A ₂ (1)

Li _x Mn _{1 - y} M _y O _{2 - z} X _z (2)

Li _x Mn ₂ O _{4 - z} X _z (3)

Li _x Mn _{2 - y} M _y M ' _z A ₄ (4)

Li _x Co _{1 - y} M _y A ₂ (5)

Li _x Co _{1 - y} M _y O _{2 - z} X _z (6)

Li _x Ni _{1 - y} M _y A ₂ (7)

Li _x Ni _{1 - y} M _y O _{2 - z} X _z (8)

Li _x Ni _{1 - y} Co _y O _{2 - z} X _z (9)

Li _x Ni _{1- y- z} Co _y M _z A _? (10)

Li _x Ni _{1 - y - z} Co _y M _z O _{2 - ?} X _? (11)

Li _x Ni _{1- y- z} Mn _y M _z A _? (12)

Li _x Ni _{1- y- z} Mn _y M _z O _{2 - ?} X _? (13)

In the formula, 0.9? X? 1.1, 0? Y? 0.5, 0? Z? 0.5, 0?? 2, M and M 'are the same or different, and Mg, Al, Co, K, Wherein A is selected from the group consisting of Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V and rare earth elements. And X is selected from the group consisting of F, S and P.

The negative electrode active material is not particularly limited and those conventionally used as negative electrode active materials may be used. For example, carbon materials such as crystalline carbon, amorphous carbon, carbon composites and carbon fibers, lithium metal, alloys of lithium and other elements, silicon or tin, and the like. Examples of the amorphous carbon include hard carbon, coke, mesocarbon microbead (MCMB) calcined at 1500 ° C or less, and mesophase pitch-based carbon fiber (MPCF). The crystalline carbon is a graphite-based material, specifically natural graphite, graphitized coke, graphitized MCMB, and graphitized MPCF. Other elements constituting the alloy with lithium may be aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium or indium.

As the solvent, usually a non-aqueous solvent may be used. Examples of the non-aqueous solvent include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, N, N-dimethylaminopropylamine, ethylene oxide and tetrahydrofuran , But is not limited thereto.

As the binder, those used in the art can be used without any particular limitation, and examples thereof include vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF) An organic binder such as polyacrylonitrile or polymethylmethacrylate or an aqueous binder such as styrene-butadiene rubber (SBR) may be used together with a thickener such as carboxymethylcellulose (CMC).

The conductive material may be at least one material selected from the group consisting of a graphite conductive material, a carbon black conductive material, and a metal or metal compound conductive material, which improves the electronic conductivity. Examples of the black electroconductive material include artificial graphite and natural graphite. Examples of the carbon black conductive material include acetylene black, ketjen black, denka black, thermal black, channel black ( channel black). Examples of metal or metal compound conductive materials include perovskite materials such as tin, tin oxide, tin phosphate (SnPO ₄ ), titanium oxide, potassium titanate, LaSrCoO ₃ , and LaSrMnO ₃ have. However, the present invention is not limited to the above-mentioned conductive materials.

The thickening agent is not particularly limited as long as it can control the viscosity of the active material slurry. For example, carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and the like can be used.

<Home>

The current collector 10 according to the present invention may be an anode current collector or a cathode current collector.

The current collector of the metal material is a metal having high conductivity and easily adhered to the slurry of the positive electrode or the negative electrode active material, and any material can be used as long as it is not reactive in the voltage range of the battery.

The negative electrode current collector may be made of copper or a copper alloy, but the present invention is not limited thereto. The surface of the stainless steel, nickel, copper, titanium or alloys thereof, copper or stainless steel may be subjected to surface treatment with carbon, nickel, Or the like may be used.

The anode current collector may be made of aluminum or an aluminum alloy, but the present invention is not limited thereto. The surface of the stainless steel, nickel, aluminum, titanium or an alloy thereof, aluminum or stainless steel may be subjected to surface treatment with carbon, nickel, Or the like may be used.

The form of the current collector 10 is not particularly limited, and a commonly used form can be used. For example, a planar current collector, a hollow current collector, a wire-like current collector, a wound wire-like current collector, a wound sheet-like current collector, a mesh-like current collector, or the like can be used.

Hereinafter, an embodiment of a method of manufacturing an electrode for a secondary battery of the present invention will be described in more detail.

FIG. 3 schematically shows a method of manufacturing an electrode for a lithium secondary battery according to an embodiment of the present invention.

As shown in Fig. 3, first, a porous partition wall is attached on the electrode current collector to form a porous partition wall in the form of a lattice. For example, a nonwoven fabric 50 having a length of 170 mm, a width of 30 mm, and a thickness of 100 탆 is attached on the electrode current collector 60 having a width of 170 mm. As a method for attaching the nonwoven fabric to the electrode current collector, a method of attaching the nonwoven fabric using an adhesive may be mentioned.

Then, an electrode slurry is coated on the electrode current collector having the nonwoven fabric 50 attached thereto to form an electrode active material layer 70 divided into porous barrier ribs (nonwoven fabric). The electrode slurry is coated on the electrode current collector on which the nonwoven fabric 50 is adhered so that the electrode active material layer 70 defined by the nonwoven fabric 50 is formed can do.

The method of coating (coating) the electrode slurry on the current collector of the electrode may be selected from known methods in consideration of the characteristics of the material, or may be carried out by a new suitable method. For example, the electrode slurry may be uniformly dispersed on a current collector by a method of uniformly applying the electrode slurry on the electrode current collector, and then dispersed using a doctor blade or the like. In some cases, a method of performing the distribution and dispersion processes in a single process may be used. Other methods such as die casting, comma coating, and screen printing may be used, or they may be formed on a separate partition and bonded to the current collector by a pressing or lamination method.

The drying of the electrode slurry applied over the current collector can be carried out in a vacuum oven at 50 ° C to 200 ° C for 12 to 72 hours.

By forming the electrode active material layer partitioned by the porous barrier ribs in this way, impregnation of the electrolyte solution is improved to improve the cyclic characteristics, and additionally replenishment of the electrolytic solution is possible, thereby making it possible to manufacture an electrode for a lithium secondary battery having improved life characteristics.

In FIG. 3, a method of coating the electrode slurry after attaching the porous barrier to the electrode collector is exemplified. An electrode for a lithium secondary battery can be manufactured in the order of first forming the partitioned electrode active material layer and then attaching the porous partition wall.

Lithium secondary battery

The electrode 100 for a lithium secondary battery of the present invention may be at least one of a negative electrode and a positive electrode, and the present invention provides a lithium secondary battery including the positive electrode, the negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non- .

The lithium secondary battery of the present invention is manufactured by making an electrode structure having a separator interposed between a positive electrode and a negative electrode, storing the electrode structure in a battery case, and injecting an electrolyte solution thereinto.

As the separator, a conventional porous polymer film conventionally used as a separator, for example, a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer Or a nonwoven fabric made of conventional porous nonwoven fabric such as high melting point glass fiber or polyethylene terephthalate fiber can be used, but the present invention is not limited thereto . As a method of applying the separator to a battery, lamination, stacking and folding of a separator and an electrode can be performed in addition to a general method of winding.

The nonaqueous electrolytic solution may include a lithium salt as an electrolyte and an organic solvent.

The lithium salt may be any of those conventionally used in an electrolyte for a lithium secondary battery, and may be represented by Li ⁺ X ^- .

In this lithium salt anion is not particularly ^{limited, F -, Cl -, Br} -, I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, PF 6 -, (CF 3) _{^{2 PF 4 -, (CF 3}} ) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, CF 3 CF 2 SO _{^{3 -, (CF 3 SO 2}} ) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) 3 C - _{, (CF 3 SO 2) 3} C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , and the like.

Examples of the organic solvent include, but are not limited to, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, gamma-butyrolactone , Propylene sulfite, and tetrahydrofuran, or a mixture of two or more thereof.

The aforementioned non-aqueous electrolyte solution is injected into an electrode structure composed of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode to manufacture a lithium secondary battery.

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape, a square shape, a pouch shape, a coin shape, or the like using a can.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example  And Comparative Example

Example  One

<Anode>

The cathode active material was Li _{1 . 1} using a _{Ni 1/3 Co 1/3} Mn 1/3 O 2 , the use of PVDF as Denka Black, a binder of a conductive material, and 92: 5: After producing the positive electrode slurry are each weight ratio composition of the three, this The non-woven fabric bulkhead was coated, dried and pressed on an aluminum substrate having a lattice shape to produce a positive electrode.

The area to which the nonwoven bulkhead was attached was 10% of the total area of the cathode active material layer.

<Cathode>

Negative electrode slurry was prepared by mixing 90 wt% of natural graphite, 5 wt% of PVDF binder and 5 wt% of dimethyl sulfoxide (DMSO) as an anode active material. This was coated, dried and pressed on a copper substrate having a nonwoven bulkhead as a lattice type to prepare a negative electrode.

The area where the nonwoven bulkhead was attached was 10% of the total area of the negative electrode active material layer

<Secondary Battery>

A positive electrode plate and a negative electrode plate were laminated, and a battery was formed between the positive electrode plate and the negative electrode plate with a separator (polyethylene, thickness: 25 μm) interposed therebetween. The tab portion of the positive electrode and the tab portion of the negative electrode were welded. The welded anode / separator / cathode combination was put into the pouch, and the three sides of the electrolyte except the electrolyte solution were sealed. At this time, the part with the tab is included in the sealing part.

Example  2

A secondary battery was manufactured in the same manner as in Example 1 except that the areas where the non-woven fabric of the positive electrode and the negative electrode were attached were 30% of the area of the positive electrode active material layer and the negative electrode active material layer.

Comparative Example  One

A secondary battery was produced in the same manner as in Example 1, except that the non-woven partition wall was not attached to the current collector, and the electrode slurry was applied all at once on the current collector.

Experimental Example

Evaluation of the lithium secondary batteries of Examples and Comparative Examples was carried out as follows.

(1) Impregnability  evaluation

An electrolyte solution was injected into the electrode assemblies of Examples and Comparative Examples to impregnate them.

1 M LiPF ₆ solution was prepared from a mixed solvent of EC / EMC / DEC (25/45/30; volume ratio), and then 1 wt% of vinylene carbonate (VC) and 0.5 wt% of 1,3-propensulfone (PRS) And 0.5 wt% of lithium bis (oxalate) borate (LiBOB).

The amount of electrolytic solution impregnated per hour in the electrode assembly was calculated by the following equation (2).

&Quot; (2) &quot;

(Weight of the electrolyte + electrode assembly after impregnating the electrode assembly into the electrolyte) - (weight of the initial electrode assembly)

The results are shown in Table 1 below.

(2) Evaluation of insulation resistance

A voltage of 50 V was applied to the anode tab of each cell and the aluminum film of the pouch of each of the above Examples and Comparative Examples to measure the resistance (insulation resistance) after one second elapsed.

The insulation resistance defect ratio is a ratio of the number of cells having an insulation resistance of less than 50 M OMEGA to the total number of manufactured batteries, and the results are shown in Table 1 below.

(3) Evaluation of cycle characteristics

The cycle characteristics of the lithium secondary batteries of Examples and Comparative Examples were evaluated by charging the produced lithium secondary batteries at 25 ° C (CC-CV 1C, 4.2V, and 0.05CA CUT-OFF) and discharging (CC 1C, Was repeated 300 times, and the ratio of the discharge capacity of the battery to the initial capacity was evaluated as the capacity retention rate. The results are shown in Table 1 below.

The capacity retention ratio according to the number of cycles (charging and discharging) of Example 1 and Comparative Example 1 is shown in Fig.

division Electrolyte impregnation time Insulation resistance defect rate
(%) 300 ^st cycle capacity retention rate
(%) One 24 48 Example 1 80g 104g 136 g One 98.2 Example 2 102g 134 g 149g 0.4 98.7 Comparative Example 1 25g 76g 132 g 5 96.4

The results are shown in Table 1. Referring to Table 1, it was confirmed that the secondary battery including the electrode of the embodiment including the porous barrier rib of the present invention had a higher amount of the electrolyte impregnated than the secondary battery of the comparative example, I could.

In particular, it was confirmed that the secondary battery including the electrode of Example 2 had an increased amount of electrolyte impregnated by 13% than the secondary battery including the electrode of Comparative Example 1 and improved the insulation resistance defect rate by 92%.

Also, referring to Table 1 and FIG. 4, it can be seen that the secondary battery of the embodiment including the electrode including the porous barrier rib of the present invention has better cycle characteristics than the secondary battery of the comparative example because the electrolyte impregnation characteristics are improved.

100: Electrode for lithium secondary battery
10: The whole house
20: electrode active material layer
30: electrode active material region
40: Porous barrier
50: Nonwoven fabric
60: electrode collector
70: electrode active material region

Claims (13)

A positive electrode and a negative electrode each comprising a current collector and an electrode active material layer formed on at least one side of the current collector;
A porous partition wall inserted into the electrode active material layer of at least one of the anode and the cathode; And
And a separator interposed between the positive electrode and the negative electrode. The lithium secondary battery of claim 1, wherein the porous partition wall is disposed across the electrode active material layer and passes through the center of the electrode active material layer. The lithium secondary battery according to claim 1, wherein the volume of the porous partition wall is represented by the following formula:
[Equation 1]

B is the volume of the porous barrier, C is the number of the electrode active material layers on which the porous barrier is formed, D is the density of the electrolyte, and E is the porosity of the porous barrier. The lithium secondary battery according to claim 1, wherein a bottom surface area of the porous barrier is 5 to 30% of the total area of the electrode active material layer. The lithium secondary battery according to claim 1, wherein the porous barrier rib has a water absorption amount of 300 g / m 2 or more. The lithium secondary battery of claim 1, wherein the porous barrier rib has a height of 5 to 200 μm. The lithium secondary battery of claim 1, wherein a height of the porous partition wall is equal to a thickness of the electrode active material layer. The lithium secondary battery of claim 1, wherein the porous barrier is at least one selected from the group consisting of nonwoven fabric, pulp and polymer foam. The lithium secondary battery according to claim 1, wherein the porous barrier ribs are in a lattice shape, a polygonal shape, or a circular shape. The lithium secondary battery according to claim 1, wherein the porous partition wall is disposed on the current collector and contacts the current collector. Forming an anode and a cathode; And
And interposing a separation membrane between the anode and the cathode,
At least one of the positive electrode positive electrode and the negative electrode,
Attaching a porous barrier to at least one surface of the electrode current collector; And
And forming an electrode active material layer partitioned by the partition wall by coating an electrode slurry on an electrode current collector having the porous partition wall. The method of manufacturing a lithium secondary battery according to claim 11, wherein the height of the porous barrier is equal to the thickness of the electrode active material layer. The method according to claim 1,
An electrolyte solution impregnating the electrode active material layer; And
And a sealing portion for containing the electrolyte solution.

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