KR20200026629A - Electrode Having Pattered Coating Layer And Lithium Secondary Battery Comprising The Same - Google Patents

Abstract

Provided is an electrode for a lithium secondary battery, including a current collector and a patterned coating layer located on at least one surface thereof, wherein the patterned coating layer comprises a first pattern region and a second pattern region exhibiting different resistances. Also provided is a lithium secondary battery comprising the same. According to the present invention, when an internal short circuit or an external short circuit occurs, the current is concentrated to a first region having a low resistance from the patterned coating layer, and the second region having relatively high resistance acts as a resistor to reduce the short circuit area and the amount of heat generated, thereby improving the safety of the lithium secondary battery.

Description

Electrode having a patterned coating layer and a lithium secondary battery comprising the same {Electrode Having Pattered Coating Layer And Lithium Secondary Battery Comprising The Same}

The present invention relates to an electrode having a patterned coating layer and a lithium secondary battery including the same for improving safety.

As the technology development and demand for mobile devices increase, the demand for rechargeable batteries that can be recharged, miniaturized and large capacity is rapidly increasing. In addition, lithium secondary batteries having high energy density and voltage have been commercialized and widely used.

A lithium secondary battery is generally manufactured by interposing two electrodes having different potentials and a separator for preventing an electrical short between the two electrodes, and then injecting an electrolyte for transferring lithium ions to the two electrodes. As the electrolyte, most organic electrolyte solutions in which lithium salts are dissolved in an organic solvent are used.

In such a lithium secondary battery, when an internal short circuit caused by a foreign material or an external short circuit occurs due to penetration of a material such as a nail, a large current flows and heat or explosion may occur, thereby improving safety. .

Therefore, the development of a technology for securing the safety of the secondary battery has been continuously tried from various angles.

The present invention is to ensure the safety of the lithium secondary battery, an object of the present invention is to provide a lithium secondary battery electrode having a patterned coating layer that can improve the safety by reducing the heat generation even if an internal short or external short occurs To provide. Another object of the present invention is to provide a method of manufacturing the electrode. Still another object of the present invention is to provide a lithium secondary battery including the electrode.

The present invention is to solve the above problems, and provides an electrode for a lithium secondary battery. A first aspect of the present invention relates to the electrode and includes a current collector and an electrode active material layer formed on at least one surface thereof, wherein the electrode active material layer includes a first pattern region and a second pattern region, and the second pattern region is It is larger than the resistance of the first pattern region.

According to a second aspect of the present invention, in the first aspect, the first pattern region is 60 to 95 area% of the total area of the electrode active material layer.

In a third aspect of the present invention, in any one of the above-described aspects, the first pattern region and the second pattern region each include an electrode active material, a binder resin, and a conductive material, and the second pattern region is the first pattern region. The content of the binder resin is higher than that of the pattern region.

According to a fourth aspect of the present invention, in any one of the above-described aspects, the binder resin content of the second pattern region is more than one and five times less than the binder resin content of the first pattern region. In a fifth aspect of the present invention, in any one of the aforementioned aspects, the first pattern region and the second pattern region each include an electrode active material, a binder resin, and a conductive material, wherein the second pattern region includes a polymer resin and It further comprises at least one of PTC (positive temperature coefficient) material.

In a sixth aspect of the present invention, in any one of the aforementioned aspects, the polymer resin has a lower melting temperature than the binder resin.

In a seventh aspect of the present invention, the first pattern region and the second pattern region each include an electrode active material, a binder resin, and a conductive material, wherein the second pattern region includes a polymer resin and It further comprises at least one of PTC (positive temperature coefficient) material.

In an eighth aspect of the present invention, in any one of the aforementioned aspects, the polymer resin has a lower melting temperature than the binder resin.

In a ninth aspect of the present disclosure, the polymer resin and the PTC (positive temperature coefficient) material may be included in the range of 1% by weight to 10% by weight based on the total weight of the second pattern region. It will be.

In the tenth aspect of the present invention, the electrode active material layer has a stripe shape in which the linear first pattern regions A and the second pattern regions B are alternately formed.

An eleventh aspect of the present invention relates to a lithium secondary battery, and includes an electrode according to any one of the aforementioned aspects.

The patterned coating layer provided on the electrode for a lithium secondary battery according to the present invention includes a first pattern region and a second pattern region exhibiting different resistances, so that current flows to a first region having a low resistance when an internal short circuit or an external short circuit occurs. The concentrated second region having a relatively high resistance serves as a resistor to reduce the short-circuit area and the calorific value, thereby improving the safety of the lithium secondary battery.

1 schematically shows the structure of an electrode for a lithium secondary battery according to an embodiment of the present invention.
2 to 4 each show an exemplary patterned coating layer provided on an electrode according to one embodiment of the invention.

Hereinafter, the terms or words used in the present specification and claims should not be construed as being limited to the ordinary or dictionary meanings, and the inventors properly define the concept of terms in order to explain their inventions in the best way. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can.

As shown in FIG. 1, an embodiment of the present invention includes a lithium secondary battery electrode 100, 100 ′, 100 ″ including a current collector 10 and an electrode active material layer 20 disposed on at least one surface thereof. ) The electrode active material layer is characterized in that the patterned in a predetermined pattern.

In one embodiment of the present invention, the current collector 10 is not particularly limited so long as it has conductivity without causing chemical changes in the battery, for example, copper, stainless steel, aluminum, nickel, titanium, sintering Surface-treated with carbon, nickel, titanium, silver, and the like on the surface of carbon, copper, or stainless steel, aluminum-cadmium alloy, and the like can be used.

The thickness of the current collector is not particularly limited, but may have a thickness of 3 to 500 μm that is commonly applied.

In the present invention, the electrode active material layer 20 is divided into two or more regions having different resistance characteristics and patterned. According to one embodiment the electrode is patterned to include a first pattern region A and a second pattern region B exhibiting different resistance characteristics. In the first pattern region and the second pattern region, the total area of each region, and the shape and size of each pattern region may be the same or different.

In one embodiment of the present invention, the first pattern region A may be designed to exhibit a lower resistance value than the second pattern region B. FIG. In this case, the heights of the first pattern region and the second pattern region are the same, and the total area occupied by the first pattern region to the total area of the electrode active material layer may be 60 to 95 area%. As long as said area% is satisfied, the shape, shape, and dimension of each pattern area are not specifically limited. However, it is preferable that the same pattern regions are distributed in an evenly distributed form in the electrode active material layer so that any one pattern region is not concentrated as a part of the electrode. 2 to 4 each show an exemplary patterned coating layer provided on an electrode according to one embodiment of the invention.

Referring to FIG. 2, the patterned coating layer may have a stripe shape in which the linear first pattern area A and the second pattern area B are alternately formed. In addition, referring to FIG. 3, the patterned coating layer forms a matrix in which a rectangular first pattern region A and a second pattern region B having a predetermined area are alternated up, down, left, and right. The resistance increase rate of the pattern region A is smaller than the resistance increase rate of the second pattern region B. FIG. Alternatively, a plurality of first pattern regions in a dot form may be regularly spaced apart from each other by a predetermined interval, and the remaining portions except for the first pattern region may be filled with the second pattern region. Alternatively, the arrangement of the first pattern region and the second pattern region may be reversed. Herein, the dot shapes may have a circle, polygon, or amorphous closed curve, respectively, and are not limited to any one form. FIG. 4 exemplarily illustrates the electrode 100 ′ in which the first pattern region is arranged in a dot form and the remaining portions except the first pattern region are filled with the second pattern region. In this way, the first pattern region and the second pattern region are arranged such that the pattern elements constituting them are evenly distributed in the electrode active material layer.

In one embodiment of the present invention, the resistance value of the first pattern region and the second pattern region has a small difference in resistance value at room temperature (25 ° C) or in a temperature range in which the battery is normally driven. However, the first pattern and the second pattern is abnormally increased in the internal temperature of the battery, for example, when the internal temperature of the battery exceeds the melting temperature of the polymer material such as polymer resin and binder resin contained in the electrode When the temperature rises above the melting temperature and cooled, the resistance value of the second pattern region is greatly increased. Damage to the cell, such as a short circuit of the cell, may cause current to concentrate on localized areas with low resistance, which may result in rapid heat generation. The present invention is to solve such a problem, the resistance is relatively low when a short circuit occurs due to damage to the battery, such as penetration by foreign matter such as nail (nail) by distributing the low resistance region and high resistance region in the electrode active material layer. It is possible to induce a current to flow to a low portion, and such a low resistance region is evenly distributed on the front surface of the electrode active material layer can be uniformly distributed to the front surface of the electrode without focusing current movement or heat generation.

In one embodiment of the present invention, the first pattern region and the second pattern region may each include an electrode active material, a binder resin and a conductive material. In this case, the content of the binder resin is higher in the second pattern region than in the first pattern region. In another embodiment of the present invention, together with or independently of, the second pattern region may further include at least one selected from a polymer resin and a positive temperature coefficient (PTC) material.

When the internal temperature of the battery is rapidly increased due to thermal runaway due to a short circuit, the second pattern region melts the polymer material included in the binder resin and the polymer resin, and the electrode structure collapses, thereby breaking the conductive network. Shutdown effect, resistance is greatly increased. On the other hand, when the PTC material is included, the resistance of the PTC material increases rapidly with increasing temperature. In the case of the first pattern region, a shutdown effect may occur while the binder resin is melted, but the increase in resistance is not large compared to the second pattern region. As such, when the resistance of the second pattern region is greatly increased, a current is induced to the first pattern region, thereby lowering the amount of heat generated.

In one embodiment of the present invention, the binder resin content of the second pattern region is higher than the binder resin content of the first pattern region, which is more than one and five times less than the binder resin content of the first pattern region. For example, it is 1.2 times or more, Preferably it is 2 times or more, More preferably, it is 3 times or more. According to this structural feature, since the content of the binder resin is higher than that of the first pattern area, the shutdown effect due to melting of the binder resin is more effective than that of the first pattern area. On the other hand, when the content of the binder resin is too high, the content of the electrode active material may be lowered to decrease the energy density, so in this respect, the content of the binder resin in the second pattern region is 5 times or less than the content of the binder resin in the first pattern region. May be appropriately limited. In addition, when the binder resin content of the second pattern region satisfies the above range, a difference in resistance between the second pattern region and the first pattern region is small at a normal driving temperature of the battery, and thus may exhibit even resistance characteristics throughout the electrode active material layer. In addition, in the event of a short circuit or thermal runaway resulting therefrom, the device is shut down to induce a current to move to the first pattern region, thereby reducing the amount of heat generated.

With or without increasing the binder resin content, the second pattern region may further comprise a polymer resin, and the polymer resin preferably has a melting temperature equal to or lower than that of the binder resin used. As a result, the polymer resin included in the second pattern region is first melted compared to the binder resin, and the shutdown effect is exhibited. As a result, there is an effect of lowering the amount of heat generated by inducing the movement of the current to the first pattern region. The polymer resin may be appropriately selected in consideration of the melting temperature of the binder resin used for the electrode. Non-limiting examples of such polymeric resins include high density polyethylene, linear low density polyethylene, low density polyethylene, medium density polyethylene, polyethylene such as maleic anhydride functionalized polyethylene , maleic anhydride functionalized elastomers, ethylene copolymers (e.g. exonmobiles). EXXELOR VA1801 and VA1803 from ExxonMobil), ethylene butene copolymer, ethylene octene copolymer, ethylene methyl acrylate, ethylene acrylate copolymer such as ethylene ethyl acrylate and ethylene butyl acrylate copolymer, glycidyl methacrylate Polyethylene (PE), Polypropylene (PP) , Modified Polyethylene (maleic anhydride functionalized polypropylene), Glycidyl methacrylate modified polypropylene, Polyvinyl Chloride (PVC) , Polyvinyl acetate, polyvinyl acetyl, acrylic resins, alternating polystyrene (sPS), PA6, PA66, PA11, PA12, PA6T, PA9T, including but not limited to polyamide, polytetrafluoroethylene ( poly-tetra-fluoroethylene: PTFE), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyamideimide, polyimide, polyethylene vinyl acetate ( EVA ) , glycidyl methacrylate modified polyethylene vinyl acetate , Polyvinyl alcohol, polymethyl methacrylate (PMMA), polyisobutylene, polyvinylidene chloride, polyvinylidene fluoride (PVDF), polymethyl acrylate, polyacrylonitrile, polybutadiene, polyethylene-terephthalate (PET), poly8-aminocaprylic acid, polyvinyl alcohol (PVA), and polycaprolactone, silicone rubber, and the like. It may include one or more. However, in one embodiment of the present invention, in view of exhibiting a rapid shutdown effect, the polymer resin may be one having a melting temperature of 150 ° C. or less.

In addition, as described above, the second pattern region may include a positive temperature coefficient (PTC) material. The PTC material is a composite material in which a conductive material in the form of fine particles is incorporated into a polymer material, and has a positive temperature coefficient characteristic of significantly increasing resistance when temperature is increased while having conductivity. When the PTC material rises above a certain temperature, the distance between the conductive materials increases due to the volume expansion of the polymer material and, in some cases, the flow of the conductive materials, thereby increasing the distance between the conductive materials. The resistance of the PTC material increases rapidly, and the current is cut off.

Such a PTC material may be a polymer material, for example, may include a thermoplastic polymer, and preferably, the thermoplastic polymer may have a crystallinity of about 15% or more.

The thermoplastic polymer is not particularly limited as long as it meets the above characteristics, but for example, high density polyethylene, linear low density polyethylene, low density polyethylene, medium density polyethylene, maleic anhydride functionalized polyethylene, maleic anhydride functionalized Ethylene acrylics such as elastomers, ethylene copolymers (e.g. EXXELOR VA1801 and VA1803 from ExxonMobil), ethylene butene copolymers, ethylene octene copolymers, ethylene methyl acrylate, ethylene ethyl acrylate and ethylene butyl acrylate copolymers Copolymers, Polyethylene (PE), Polypropylene (PP), Glycidyl methacrylate modified polypropylene, Maleic anhydride functionalized polypropylene, Glycidyl methacrylate modified poly Propylene (glycidyl methacrylate modified p olypropylene), polyvinyl chloride (PVC), polyvinyl acetate, polyvinyl acetyl, acrylic resin, syndiotactic polystyrene (sPS), PA6, PA66, PA11, PA12, PA6T, PA9T Polyamide, poly-tetra-fluoroethylene (PTFE), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyamideimide, polyimide, polyethylene vinyl acetate (EVA), glyc Cydyl methacrylate modified polyethylene vinyl acetate, polyvinyl alcohol, polymethyl methacrylate (PMMA), polyisobutylene, polyvinylidene chloride, polyvinylidene fluoride (PVDF), polymethyl acrylate, poly acrylo Nitrile, polybutadiene, polyethylene-terephthalate (PET), poly8-aminocaprylic acid, polyvinyl alcohol (PVA), and polycaprolactone It may be at least one selected from the group. In addition, the conductive material may include, for example, BaTiO ₃ , conductive carbon material, silver, and the like, and one or a mixture of two or more selected from these may be used.

In the present invention, the PTC material and the polymer resin may be included in an amount of 1 to 10% by weight or 1 to 5% by weight based on the total weight of the second pattern region in consideration of electrode capacity. When exceeding the above range, the amount of the electrode active material may be reduced to reduce the energy density.

As such, the patterned electrode active material layer according to the embodiment of the present invention includes two regions having different resistances, so that when the temperature inside the battery rises due to an internal short circuit or an external short circuit, the resistance is low. The current is concentrated in the first pattern region, and the second pattern region having a high resistance to the binder resin or additionally including a PTC material may act as a resistor to maintain a temperature. As a result, the heat generating area in the patterned coating layer is limited to the first pattern area to minimize the total amount of heat generated, thereby improving the safety of the lithium secondary battery. If all of the electrode active material layers have the same resistance characteristics, there is a risk of ignition or explosion when heat generation occurs in the entire electrode to increase the temperature inside the battery.

The electrode active material layer as described above may be formed by a patterning process known in the art, such as a mask process, a lift-off process, using two coating slurries having different compositions.

For example, a first coating slurry and a second coating slurry obtained by dispersing an electrode active material, a binder resin, and a conductive material in a solvent are prepared on at least one surface of a current collector, and a first coating slurry is coated through a mask to form a first pattern. After forming the region, the mask may be moved to apply the second coating slurry to form the second pattern region. Here, the second coating slurry may have a higher content of the binder resin than the first coating slurry. Alternatively, the second coating slurry may further include at least one or more of the aforementioned polymer resin and PTC material together or independently of this.

In this case, the binder resin content of the second coating slurry may be 1.2 times or more, or two times or three times or more of the binder resin content of the first coating slurry. In addition, or together with or independently, the polymer resin and the PTC material in the second coating slurry may be included, and the content thereof is 1 to 10 wt% or 1 to 5 wt% based on the total weight of solids in the second coating slurry. It may be included in an appropriate amount of the range.

The active material usable for the first coating slurry and the second coating slurry may be determined according to the type of electrode. For example, when the electrode for lithium secondary batteries which concerns on one Embodiment of this invention is a positive electrode, any material can be used as a substance which can be used as a positive electrode active material of a lithium secondary battery as an active material. For example, lithium cobalt oxide (LiCoO _2), lithium nickel oxide (LiNiO ₂₎ layered compounds or one or more transition metal compounds, such as substituted; Li _{1 + x} Mn _{2 - x} O ₄ (Where x is 0 to 0.33), lithium manganese oxide such as LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ ; Vanadium oxides such as lithium copper oxide (Li ₂ CuO ₂ ); LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Ni-site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ , wherein 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 , wherein M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1, or Li ₂ Mn ₃ MO ₈ , where M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); Spinel-structure lithium manganese composite oxides represented by LiNi _x Mn _{2 - x} O ₄ ; LiMn ₂ O _{4 in} which Li is partially substituted with alkaline earth metal ions; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , LiNi _{0 . 8} Co _{0 . 1} Mn _{0 . 1} O ₂ and the like. However, it is not limited only to these. On the other hand, when the electrode for a lithium secondary battery according to an embodiment of the present invention is a negative electrode, as long as it can be used as a negative electrode active material of a lithium secondary battery as an active material can be used without limitation. For example, carbon, such as hardly graphitized carbon and graphite type carbon (natural graphite, artificial graphite); Li _x Fe ₂ O ₃ (0≤x≤1), Li _x WO ₂ (0≤x≤1), Sn _x Me _{1 - x} Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me' Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 <x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ And metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; One or two or more selected from lithium titanium oxide and the like can be used. In one specific embodiment, the negative electrode active material may include a carbonaceous material and / or Si. Such an active material may be used in an amount of 80 to 98 wt% based on the solid content of each slurry.

The conductive material usable in the first coating slurry and the second coating slurry is not particularly limited as long as it has conductivity without causing chemical change in the battery. Examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; It may include one or a mixture of two or more selected from conductive materials such as polyphenylene derivatives. Such a conductive material may be used in an amount of 0.1 to 20% by weight, in particular 1 to 10% by weight, based on the solids content of each slurry.

In addition, the binder resin usable in the first coating slurry and the second coating slurry is independently polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride, or polyvinylidene fluoride. , Polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, polyacrylic acid, styrene butyrene rubber (SBR) and the like can be used. The binder resin may be suitably used within the range of 1 to 10% by weight based on solids content in the first coating slurry. In addition, the second coating slurry may be included in a content higher than the content of the binder resin contained in the first coating slurry in the content range as described above.

Meanwhile, as a solvent usable for the first coating slurry and the second coating slurry, water, or an organic solvent such as N-methyl-2-pyrrolidone (NMP) or acetonitrile may be used independently, and the solid content in each slurry may be used. It may be used in an amount such that the concentration is 50 to 95% by weight, preferably 70 to 90% by weight.

After application of the first coating slurry and the second coating slurry, a patterned coating layer may be formed by performing drying and rolling.

Another embodiment of the present invention relates to a lithium secondary battery including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the positive electrode or the negative electrode is an electrode for a lithium secondary battery according to the present invention described above. It is characterized by.

The separator is interposed between the positive electrode and the negative electrode, and serves to electrically insulate the positive electrode and the negative electrode and to allow lithium ions to pass therethrough. The separator may be used as long as it is used in a separator used in a general lithium secondary battery field and is not particularly limited.

The lithium secondary battery according to the present invention may be included in a battery module as a unit cell, and the battery module may be used in a battery pack and a device including the battery pack as a power source. Specific examples of the device may be, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, or power storage systems.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

Example 1:

Li (Ni _0.8 Mn _0.1 Co _0.1 ) O ₂ (GL80) as the active material, carbon black (Super P) as the conductive material and PVdF (KF9700) as the binder resin were added to the solvent NMP in a weight ratio of 97.5: 1: 1.5, The first coating slurry for forming the first pattern region was prepared.

Meanwhile, Li (Ni _0.8 Mn _0.1 Co _0.1 ) O ₂ (GL80) as an active material, carbon black (Super P) as a conductive material, and PVdF (KF9700) as a binder resin were added to NMP as a solvent in a weight ratio of 94: 1: 5. Then, the second coating slurry for forming the second pattern region was prepared.

Next, using the first coating slurry and the second coating slurry on one surface of an aluminum current collector (thickness 12 μm), a patterned electrode active material layer having a width of 1 mm was alternately applied, and then dried at 130 ° C. And rolled to form an electrode active material layer having a thickness of 150㎛ to prepare a positive electrode. The area of the first pattern region in the electrode active material layer was 70 area% of the total area of the electrode active material layer.

Example 2:

The second coating slurry was Li (Ni _0.8 Mn _0.1 Co _0.1 ) O ₂ (GL80) as the electrode active material, carbon black (Super P) as the conductive material, PVdF (KF9700) as the binder resin and 94: 1: 1.5: 3.5 A positive electrode was prepared in the same manner as in Example 1, except that the mixture was added to NMP as a solvent in a weight ratio of.

Comparative Example 1 :

Li (Ni _0.8 Mn _0.1 Co _0.1 ) O ₂ (GL80) as the active material, carbon black (Super P) as the conductive material and PVdF (KF9700) as the binder resin were added to the solvent NMP in a weight ratio of 97.5: 1: 1.5, A coating slurry for forming an electrode active material was prepared. The coating slurry was applied to one surface of an aluminum current collector having a thickness of 12 μm, dried at 130 ° C., and rolled to form an electrode active material layer having a thickness of 150 μm to prepare a positive electrode.

Comparative Example 2 :

Li (Ni _0.8 Mn _0.1 Co _0.1 ) O ₂ (GL80), carbon black (Super P) as the conductive material, PVdF (KF9700) and polyethylene as the binder resin were added to the solvent NMP in a weight ratio of 94: 1: 1.5: 3.5 Thus, a coating slurry for forming an electrode active material layer was prepared. The coating slurry was applied to one surface of an aluminum current collector having a thickness of 12 μm, dried at 130 ° C., and rolled to form an electrode active material layer having a thickness of 150 μm to prepare a positive electrode.

Resistance measurement result

The surface resistances of the first pattern region and the second pattern region were measured for each electrode (anode) manufactured in the above example. In addition, the surface resistance was measured for each electrode (anode) manufactured in each of the comparative examples. The surface resistance was measured by Laresta-GP (MCP-T600 model, MITSUBISHI CHEMICAL Co., Ltd.) five times the surface resistance at room temperature (about 25 ℃ condition) and then averaged.

Next, after preparing a lithium metal in each of the positive electrode and counter electrode prepared in the above Examples and Comparative Examples and placing a polypropylene separator therebetween, ethylene carbonate / dimethyl carbonate / LiPF ₆ (MerckBatteryGrade, EC / DMC = 1/1 A coin half cell was prepared using an electrolyte solution of 1 mliPF ₆ ).

Each of the prepared batteries was allowed to stand in a chamber at 300 ° C. for about 10 hours, and then cooled to room temperature and decomposed to recover a positive electrode. The surface resistances of the first pattern region and the second pattern region were measured for each of the recovered anodes. Surface resistance was measured at room temperature (about 25 ° C. conditions), and the same method as described above was used. The results are summarized in Table 1 below.

As can be seen in the table below, in Examples 1 and 2 of the present invention, it was confirmed that the resistance of the second pattern region increased significantly after high temperature exposure. Therefore, when the internal temperature of the battery rises rapidly due to an internal short circuit or the like, it is possible to bring about an effect of distributing the current flow to the first pattern region having a low resistance.

Coating layer
Resistance (Ω)
Room temperature
After exposure to high temperature (300 ℃)
Example 1
First pattern region
0.6
63
Second pattern area
0.8
124
Example 2
First pattern region
0.6
69
Second pattern area
0.9
714
Comparative Example 1
0.6
67
Comparative Example 2
0.9
924

100, 100 ', 100''electrode
A first pattern region
B second pattern area
20 electrode active material layer
10 current collector

Claims (11)

A current collector and an electrode active material layer formed on at least one surface thereof;
The electrode active material layer includes a first pattern region and a second pattern region, wherein the second pattern region is larger than the resistance of the first pattern region electrode for a lithium secondary battery. The method of claim 1,
The first pattern region is a lithium secondary battery electrode that is 60 to 95 area% of the total area of the electrode active material layer. The method of claim 1,
The first pattern region and the second pattern region each include an electrode active material, a binder resin and a conductive material, and the second pattern region has a higher content of binder resin than the first pattern region. . The method of claim 1,
And a binder resin content of the second pattern region is greater than 1 times and 5 times less than the binder resin content of the first pattern region. The method of claim 4, wherein
Wherein the first pattern region and the second pattern region each include an electrode active material, a binder resin, and a conductive material, and the second pattern region further includes at least one of a polymer resin and a positive temperature coefficient (PTC) material. Phosphorus for lithium secondary battery. The method of claim 5,
The polymer resin is a lithium secondary battery electrode having a lower melting temperature than the binder resin. The method of claim 1,
Wherein the first pattern region and the second pattern region each include an electrode active material, a binder resin, and a conductive material, and the second pattern region further includes at least one of a polymer resin and a positive temperature coefficient (PTC) material. Phosphorus for lithium secondary battery. The method of claim 7, wherein
The polymer resin is a lithium secondary battery electrode having a lower melting temperature than the binder resin. The method of claim 7, wherein
At least one of the polymer resin and the positive temperature coefficient (PTC) material may be included in the range of 1 wt% to 10 wt% based on the total weight of the second pattern region. The method of claim 1,
The electrode active material layer is a lithium secondary battery electrode having a stripe shape formed by alternating linear first pattern regions (A) and second pattern regions (B) with each other. A lithium secondary battery comprising the lithium secondary battery electrode according to any one of claims 1 to 10.

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