KR102168230B1 - Electrode collector improving battery safety, method of making the same and electrode comprising the same - Google Patents

Abstract

The present invention has a thickness of 10 to 20 μm, a plurality of recesses are formed, the recesses have a semi-sphere shape having a depth of 1 to 3 μm and a diameter of 1 to 6 μm, and the recesses are adjacent recesses And 1 to 100 μm, and the electrode current collector has an elongation in the range of 1/10 to 9/10 compared to the current collector before the formation of the concave portion. In relation to, an electrode including such an electrode current collector has improved safety when penetrating a nail.

Description

Electrode collector improving battery safety, method of making the same and electrode comprising the same}

The present invention relates to an electrode current collector that improves battery safety, a method for manufacturing the same, and an electrode including the same. More specifically, the internal short-circuit safety of a secondary battery is secured by increasing the penetration resistance of the positive electrode to a nail. It is an invention.

The battery energy increases in proportion to the energy density, and as the secondary battery becomes more energized, the safety of the battery is threatened. Normally, the electrical energy stored in the anode and the cathode is separated by a separator and safely maintained, but a short circuit is caused between the anode and the cathode due to various causes, and the stored electrical energy is released for a short time, resulting in heat/ignition or thermal runaway. ) Phenomenon. In particular, when a large current flows inside the battery within a short time due to an internal short circuit caused by nail penetration, the lithium secondary battery has a risk of ignition/explosion as the battery is heated by heat generation.

Accordingly, as part of efforts to secure safety against nail penetration, a method of mounting and using an element outside the cell and a method of using a material inside the cell have been mainly studied and applied. PTC elements using changes in temperature, protection circuits using changes in voltage, and safety vents using changes in battery internal pressure are electrons, and physical, chemical, and electrochemical according to changes in temperature or voltage inside the battery. The latter belongs to the addition of substances that can be changed into.

Another way to ensure safety against nail penetration is to adjust the elongation of the positive and negative electrodes. However, since a copper foil generally used as a negative electrode current collector has a considerably large elongation, it is known that it is very difficult to process the positive electrode current collector and the negative electrode current collector having a desired level of elongation. On the other hand, although it is preferable that the separator has a higher elongation than the electrode current collector in order to ensure safety against nail penetration, the electrode current collector, in particular, has a lower elongation than the negative electrode current collector. There is a problem that the possibility of this contact is further increased.

Therefore, in order to secure safety against nail penetration, it is necessary to adjust the elongation of the electrode including the electrode current collector.

One problem to be solved in the present invention is an electrode, more specifically, an electrode capable of solving the heating/ignition problem caused by a short by controlling the elongation of the anode and the cathode by controlling the internal short-circuit resistance through the nail, and a secondary including the same. It is to provide a battery.

Another problem to be solved in the present invention is to improve the safety against nail penetration of the battery by adjusting the elongation of each of the positive electrode current collector and the negative electrode current collector.

In order to solve the above-described problem, according to an embodiment of the present invention, as an electrode current collector for a secondary battery, it has a thickness of 10 to 20 μm, and a plurality of recesses are formed, and the recesses have a depth of 1 to 3 μm and a diameter It has a semi-sphere shape of 1 to 6 µm, and the concave portion is arranged to be spaced apart from the adjacent concave portion in a range of 1 to 100 µm, and the electrode current collector is 1/ There is provided an electrode current collector for a secondary battery, characterized in that it has an elongation in the range of 10 to 9/10.

The electrode current collector is a positive electrode current collector of aluminum foil, and may have an elongation in the range of 1.5 to 2.7%.

Alternatively, the electrode current collector is a negative electrode current collector made of a copper foil, and may have an elongation in the range of 6.0 to 7.0%.

According to another embodiment of the present invention, the above-described positive electrode current collector; And a positive electrode active material layer formed on at least one surface of the positive electrode current collector, and a positive electrode elongation of 0.5 to 1.0% is provided.

Or, according to another embodiment of the present invention, the above-described negative electrode current collector; And a negative electrode active material layer formed on at least one surface of the negative electrode current collector, and an elongation of the negative electrode is 2.0 to 3.5%.

The active material constituting the active material layer may have a hardness greater than that of the electrode current collector, and a particulate active material having a particle diameter of 2 to 6 μm may occupy 70 to 100% by volume of the total active material.

In addition, the porosity of the active material layer may be in the range of 23 to 35%.

In addition, the concave portion formed in the electrode current collector may be formed by press-fitting a fine active material.

According to another embodiment of the present invention, a roller having a plurality of protrusions is pressed against the electrode current collector so that the press line pressure is 1 to 5 tons, and the protrusions have a height of 1 to 3 µm and a diameter of 1 to There is provided a method of manufacturing an electrode current collector comprising a step, characterized in that it is in the shape of a 6 µm convex semi-sphere and is spaced apart from adjacent protrusions in a range of 1 to 100 µm.

According to another embodiment of the present invention, an active material slurry consisting of an active material, an electrode binder polymer, and an organic solvent is applied to an electrode current collector, wherein the active material has a hardness greater than that of the electrode current collector and 70 to 100 of the total active materials. Volume% having a particle diameter of 2 to 6 μm; And drying the active material slurry applied to the electrode current collector and laminating at a linear pressure of 1 to 5 tons.

According to an aspect of the present invention, by adjusting the elongation of the positive electrode and the negative electrode to an optimum range, an indirect short circuit through the nail through the nail and an internal short circuit between the positive electrode current collector and the negative electrode current collector due to a direct short not through the nail and It is possible to prevent or significantly reduce the internal short circuit between the entire and the negative active material layer.

In particular, according to an aspect of the present invention, the elongation of not only the positive electrode current collector but also the negative electrode current collector may be adjusted within a certain range.

Accordingly, heat generation and ignition of the secondary battery due to an internal short circuit can be prevented, and the safety of the secondary battery can be greatly improved.

The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the content of the above-described invention, so the present invention is limited to the matters described in such drawings. It is limited and should not be interpreted
1 is a cross-sectional view showing the surface of a roller used in an aspect of the present invention.
2 schematically shows an aspect of the present invention in which a roller having a projection is applied to an electrode current collector.
3 is an SEM image showing a cross section of an electrode in which a concave portion is formed in an electrode current collector by an active material having a specific particle diameter.

Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventors appropriately explain the concept of terms in order to explain their own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations described in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical spirit of the present invention, and thus various equivalents that can replace them at the time of application It should be understood that there may be water and variations.

According to an aspect of the present invention, as an electrode current collector for a secondary battery, the electrode current collector has a thickness of 10 to 20 μm, and a plurality of recesses are formed, and the recesses are semi-spheres having a depth of 1 to 3 μm and a diameter of 1 to 6 μm. sphere) shape, and the concave portions are arranged to be spaced apart from adjacent concave portions in a range of 1 to 100 μm, and the electrode current collector has an elongation in the range of 1/10 to 9/10 compared to the current collector before formation of the concave portion. There is provided an electrode current collector for a secondary battery, characterized in that it has.

In the present specification,'elongation' is used in relation to'electrode' or'electrode current collector', and is defined as Equation 1 below, and for specific measurement conditions and methods, the measurement method described in ISO527 is used:

The elongation is of a concept including both a longitudinal elongation and a transverse elongation. The elongation may be different from the elongation in the longitudinal direction and the elongation in the transverse direction. In this case, a value obtained by arithmetic average of the longitudinal elongation and the transverse elongation is defined as the elongation. For example, when the longitudinal elongation of the positive electrode is 50% and the transverse elongation is 100%, the elongation of the positive electrode is 75%.

The elongation rate of the electrode current collector may vary depending on the material, thickness, and strength of the electrode current collector, and may also vary depending on the manufacturing method and processing method of the electrode current collector. In the present invention, an electrode current collector having a predetermined thickness is used. It is characterized by imparting low elongation and high strength characteristics to the electrode current collector by rolling with a roller having a projection.

More specifically, the positive electrode current collector usable in the present invention may have a thickness of 6 μm to 20 μm. If the positive electrode current collector is manufactured thinner than the above lower limit, it may cause cell resistance to decrease and fracture during the rolling process, and at the same time, it may be lower than the desired lower limit elongation. If it is manufactured thicker than the upper limit, the desired elongation may be secured. And the volume of the electrode unnecessarily increases.

In addition, the material of the positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes to the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel. Carbon, nickel, titanium, silver, or the like may be used on the surface of the steel. Aluminum can be preferably used. In addition, the current collector can increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible.

The negative electrode current collector may be generally made to have a thickness of about 3 to 30 μm. If the negative electrode current collector is manufactured thinner than the lower limit, it may cause a decrease in cell resistance and breakage during the rolling process, and at the same time, it may be lower than the desired lower limit elongation. If it is manufactured thicker than the upper limit, the desired elongation may be secured. And the volume of the electrode unnecessarily increases.

The material of the negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes to the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface treatment with carbon, nickel, titanium, silver or the like, aluminum-cadmium alloy, etc. may be used. Also, like the positive electrode current collector, it is possible to enhance the bonding strength of the negative electrode active material by forming fine irregularities on the surface thereof, and it may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

When the concave portion formed in the electrode current collector has the depth, diameter, and separation distance in the above-described range, the elongation desired by the electrode current collector, more specifically, 1/10 of the elongation rate of the electrode current collector before the concave portion pattern is formed. It has an elongation corresponding to the range of 9/10. When the elongation is significantly less than the elongation before the concave pattern is formed, that is, when the elongation is less than 10%, the electrode active material layer slurry coating becomes impossible due to the breakage of the current collector, and there is little difference in the elongation rate. That is, if it has an elongation greater than 9/10, it does not have nail penetration stability.

According to an aspect of the present invention, when the positive electrode has an elongation in the range of 0.5 to 1.0%, the possibility of an internal short circuit is lowered due to the penetration resistance of the positive electrode to the nail when penetrating the nail. The effect of preventing/reducing the internal short circuit by the positive electrode having an elongation in the above numerical range is that when the negative electrode current collector has a high elongation, e.g., about 15%, and/or the separator has a low elongation, e.g., about 6%. It can also be obtained when it has an elongation. If the elongation of the positive electrode is lower than 0.5%, the positive electrode may be broken in the rolling process, and if it is higher than 1.0%, the positive electrode is stretched together in the through direction when penetrating the nail to come into contact with the negative current collector or the negative active material. There is a problem in that an internal short circuit may be caused, or an internal short circuit may be caused by contacting the negative electrode current collector or the negative electrode active material through the nail because it is in direct contact with the nail.

To this end, according to an aspect of the present invention, the positive electrode current collector may have an elongation of 1.5 to 2.7%. If the elongation of the positive electrode current collector is less than 1.5%, a rupture phenomenon occurs during the cell manufacturing process, and if it is greater than 2.7%, nail penetration stability will not be achieved.

In addition, according to an aspect of the present invention, the negative electrode preferably has an elongation in the range of 2.0 to 3.5%. To this end, the negative electrode current collector may have an elongation of 6.0 to 7.0%. When the negative electrode has an elongation in the range of 2.0 to 3.5%, the possibility of an internal short circuit is lowered due to the penetration resistance of the negative electrode to the nail when penetrating the nail. As for the negative electrode elongation, as described above, since copper (Cu) used as a negative electrode current collector generally has a higher elongation rate than that of the positive electrode current collector, the negative electrode including the negative electrode current collector has a weak nail penetrability. It has important significance when considering

In order to manufacture the above-described electrode current collector, in one aspect of the present invention, a process of pressing the roller 100 on which the protrusion 110 is formed as disclosed in FIG. 1 to the electrode current collector with a line pressure of 1 to 5 tons is adopted. I can. When the line pressure is lower than 1 ton, the desired elongation cannot be obtained in the present invention, and when it is higher than 5 ton, a rupture phenomenon of the current collector occurs.

The protrusion may be in the shape of a hemispherical protruding convexly on the roller surface, the height of the hemisphere protruding from the surface may be 1 to 3 µm, the diameter of the hemisphere may be 1 to 6 µm, and the separation distance between the adjacent protrusions may be 1 to 100 µm. The shape and size of the protrusion may correspond to the size of the fine active material. In this case, when the electrode mixture slurry containing the fine active material is coated on the electrode current collector pressed by the roller, the active material is an electrode collector formed by the roller protrusion. It is supported on the entire recess to increase the loading of the electrode active material, and at the same time, it can contribute to improving the binding force of the active material to the electrode current collector. The protrusions may be regularly arranged on the roller surface, arranged in a predetermined pattern, or irregularly arranged.

On the other hand, in order to form the concave-convex portion in the electrode current collector, a roller having a protrusion is not used, but a roller having a concave portion is used to form the concave-convex portion in the electrode current collector. In this case, in the case of pressing the electrode current collector using a roller having a protrusion, for example, a roller shown in FIG. 1, a thickness equal to the height of the protrusion 110 formed on the roller 100 shown in FIG. 2'a' While it is preferable that the electrode current collector 200 having a concave portion can be secured, in the case of forming a convex portion in the electrode current collector using a roller having a concave portion, a protrusion formed convexly in the electrode current collector is formed, but depending on the line pressure, the electrode collector There is a risk that the overall thickness may become too thin than the desired level.

Alternatively, according to an embodiment of the present invention, a process of laminating after applying an active material slurry containing a specific active material to the electrode current collector without going through the process of separately processing the electrode current collector using a roller as described above is performed. Through this, it is possible to obtain an electrode including an electrode current collector in which a concave portion is formed according to the present invention. However, in the case of processing the electrode current collector using a roller, unlike the hardness, particle diameter, and porosity of the active material included in the active material slurry applied to the electrode current collector, the electrode is applied by application of the active material slurry and lamination. When a specific recess is formed in the current collector, the hardness, particle diameter, and porosity of the active material are limited as follows.

More specifically, with respect to the hardness of the active material itself, the active material itself must have a higher hardness than the electrode current collector, and through the process of applying and laminating the active material slurry, the active material press-fitting effect as shown in FIG. 3 occurs. In the lamination process, a linear pressure of 1 to 5 ton may be applied. Therefore, an active material having a higher hardness than an electrode current collector must be used. For example, when the A1100 alloy is used as the positive electrode current collector, the A1100 alloy has a Brinell hardness of 28, so an active material having a hardness greater than the Brinell hardness of 28 should be used.

In addition, with respect to the particle size of the active material, it is preferable to include a particulate active material having a particle diameter of 6 μm or less, preferably 2 to 6 μm, and more preferably 70% or more of the particulate active material having the particle size. When an active material having a particle diameter larger than that described above is used in an amount of 30% or more of the total volume of the active material, it is difficult to obtain the effect of reducing the elongation rate of the entire electrode targeted in the present invention. For example, according to an embodiment of the present invention, when a particulate active material having a particle diameter of 6 μm and an active material having a particle diameter of 10 μm are mixed and used, 70% or more of the total volume of the active material should be included.

In the specification of the present application, the active material serving as a reference in relation to the particle size generally refers to an active material in the form of primary particles or secondary particles.

In addition, as the porosity of the electrode active material layer decreases, the elongation rate of the positive electrode active material layer tends to decrease. In one aspect of the present invention, the porosity of the positive active material layer is preferably 23% to 35% or 23% to 31%. If the porosity is less than the lower limit, smooth movement of the electrolyte and/or lithium ions may not be ensured, and battery performance may be degraded, and when the porosity is greater than the upper limit, it is difficult to secure the desired elongation, The volume of the electrode is unnecessarily increased.

The positive electrode may be formed by including a positive electrode active material layer on one or both surfaces of the positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material, a conductive material, and a binder.

The positive electrode active material may include a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as the formula Li _{1 + x} Mn _{2 - x} O ₄ (wherein x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, etc.; Formula Li _x Ni _a Mn _b Co _c O ₂ (here, 0<a≤0.9, 0<b≤0.9, 0<c≤0.5, 0.85 ≤a+b+c≤1.05, 0.95≤x≤1.15), etc. A three-component lithium composite oxide of; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , and Cu ₂ V ₂ O ₇ ; Ni site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ (here, M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x =0.01 ~ 0.3); Formula LiMn _{2 - x} M _x O ₂ (where 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, A lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 wherein} part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like may be used, but are not limited thereto.

The binder is a component that aids in bonding of the active material and the conductive material and bonding to the current collector, and may be generally added in an amount of 1 to 50% by weight based on the total weight of the positive electrode active material layer. As such a binder, the high molecular weight polyacrylonitrile-acrylic acid copolymer may be used, but is not limited thereto. Other examples include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, fluorine rubber, and various copolymers.

The conductive material has conductivity without causing a chemical change in the battery, and may be added in an amount of 1% to 50% by weight based on the total weight of the positive electrode active material layer. Graphite, such as natural graphite and artificial graphite, for example; Carbon blacks such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; Carbon nanotube (CNT); Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive polymers such as polyphenylene derivatives may be used.

The negative electrode may be obtained by applying a mixture including a negative electrode active material, a binder, and a conductive material to a negative electrode current collector and then drying the solvent.

Examples of the negative electrode active material include carbon and graphite materials such as natural graphite, artificial graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotube, fullerene, and activated carbon; Metals such as Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt, Ti, etc., which can be alloyed with lithium, and compounds containing these elements; A composite compound of a metal and a compound thereof and a carbon and graphite material; Lithium-containing nitrides, and the like.

A conductive material may be further included as a component for improving the conductivity of the negative active material. The conductive material is the same as described in relation to the positive electrode.

In addition, a separator interposed between the anode and the cathode may be included, and an insulating thin film having high ion permeability and mechanical strength is used as the separator. The pore diameter of the separator is generally 0.01 to 10 μm, and the thickness is generally 5 to 50 μm. As such a separator, For example, olefin-based polymers such as polypropylene having chemical resistance and hydrophobicity; Sheets or non-woven fabrics made of glass fiber or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The lithium secondary battery generally further includes a lithium salt-containing non-aqueous electrolyte in addition to a positive electrode, a negative electrode, and a separator.

The lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and lithium.

As the nonaqueous electrolyte, a nonaqueous electrolyte, an organic solid electrolyte, an inorganic solid electrolyte, or the like is used.

As the non-aqueous electrolyte, for example, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyllolactone, 1,2-dime Toxiethane, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate tryster , Trimethoxy methane, dioxolone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, ethyl propionate, etc. An aprotic organic solvent can be used.

As the organic solid electrolyte, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, a poly agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer or the like containing an ionic dissociating group may be used.

As the inorganic solid electrolyte, for example, Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides, and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ may be used.

The lithium salt is a material that is easily soluble in the non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF _{6, LiSbF 6, LiAlCl 4,} CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, chloroborane lithium, lower aliphatic carboxylic acid lithium, lithium tetraphenyl borate and imide have.

In addition, non-aqueous electrolytes include pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, and trihexaphosphate for the purpose of improving charge/discharge properties and flame retardancy. Addition of amide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, aluminum trichloride, etc. It could be.

In some cases, in order to impart non-flammability, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further included, and carbon dioxide gas may be further included in order to improve high-temperature storage characteristics.

The present invention will be described in more detail by way of examples below. The embodiments herein are for detailed description of the invention and are not intended to limit the scope of the rights.

Example 1: Preparation of the anode

An aluminum foil having an elongation of 2.3% in which a plurality of concave portions having a thickness of 12 µm, a depth of 3 µm, a diameter of 6 µm, and a distance of 100 µm to the adjacent concave portions was formed as a positive electrode current collector.

In addition, the positive electrode active material LiNi _{0 . 6} Mn _{0 . 2} Co _{0 . 2} O ₂ (average particle diameter: 6 µm), PVDF as a binder, and carbon black as a conductive material were added to N-methylpyrrolidone (NMP) in a composition ratio of 92.5:4:3.5 to form a positive electrode active material layer. The slurry was prepared.

The slurry for forming the positive electrode active material layer was coated on both surfaces of an aluminum foil, dried and rolled to form a positive electrode active material layer having a thickness of 118 μm.

The finally fabricated anode had an elongation of 1.0%.

Example 2: Preparation of the anode

A positive electrode was prepared in the same manner as in Example 1, except that an aluminum foil having a depth of 2 µm, a diameter of 3 µm, and an elongation of 2.0% having a concave portion having a distance of 10 µm to the adjacent concave portion was used as the positive electrode current collector. Was prepared.

The finally fabricated anode had an elongation of 0.7%.

Example 3: Preparation of the anode

A positive electrode was prepared in the same manner as in Example 1, except that an aluminum foil having an elongation of 1.5% in which a concave portion having a depth of 1 µm, a diameter of 1 µm, and a distance from the adjacent concave portion was formed as a positive electrode current collector. Was prepared.

The finally fabricated anode had an elongation of 0.5%.

Example 4: Preparation of cathode

A copper foil having an elongation of 7.0% in which a plurality of concave portions having a thickness of 10 µm, a depth of 3 µm, a diameter of 6 µm, and a spacing distance of 100 µm to the adjacent concave portions was prepared as a negative electrode current collector.

Natural graphite as an anode active material: binder SBR: thickener CMC: conductive carbon black was added to water as a solvent in a composition ratio of 96.2:1.8:1:1 to prepare a slurry for forming a negative electrode active material layer.

The slurry for forming the negative active material layer was coated on both sides of a negative electrode current collector, dried, and rolled to prepare a negative electrode.

The final fabricated negative electrode had an elongation of 3.5%.

Example 5: Preparation of negative electrode

A negative electrode was prepared in the same manner as in Example 4, except that a copper foil having an elongation of 6.5% having a concave portion having a depth of 2 µm, a diameter of 3 µm, and a spacing distance of 10 µm from the adjacent concave portion was used as the negative electrode current collector. Was prepared.

The finally fabricated negative electrode had an elongation of 2.9%.

Example 6: Preparation of the cathode

A negative electrode was prepared in the same manner as in Example 4, except that a copper foil having an elongation of 6.0% in which a concave portion having a depth of 1 µm, a diameter of 1 µm, and a distance from the adjacent concave portion was formed as a negative electrode current collector was used. Was prepared.

The finally fabricated negative electrode had an elongation of 2.1%.

Comparative example 1: Preparation of the anode

A positive electrode was manufactured in the same manner as in Example 1, except that a positive electrode current collector having an elongation of 3% in which no recess was formed was used.

The elongation of the finally prepared positive electrode was 1.5%.

Comparative example 2: Preparation of the anode

In the same manner as in Example 1, except that an aluminum foil having an elongation of 2.9% in which a plurality of concave portions having a depth of 1 µm, a diameter of 100 µm, and a distance of 100 µm to the adjacent concave portions was used as the positive electrode current collector. A positive electrode was prepared.

The finally fabricated anode had an elongation of 1.4%.

Comparative example 3: Preparation of cathode

A negative electrode was manufactured in the same manner as in Example 3, except that a copper current collector having an elongation of 8% with no recessed portion was used.

The elongation of the finally fabricated negative electrode was 4%.

Comparative example 4: Preparation of cathode

A negative electrode was prepared in the same manner as in Example 3, except that a copper current collector having a depth of 3 µm, a diameter of 10 µm, and a plurality of concave portions having a spacing distance of 1000 µm from the adjacent concave portions was used. I did.

The elongation of the finally fabricated negative electrode was 3.8%.

Evaluation example : Nail penetration experiment

A pouch-type cell was fabricated using the prepared electrodes of Examples 1 to 6 and Comparative Examples 1 to 4, the counter electrode, separator, and pouch of each of Examples and Comparative Examples.

More specifically, the cathode used with Examples 1 to 3 (anode) corresponds to Comparative Example 3, and the anode used with Examples 4 to 6 (cathode) corresponds to Comparative Example 1. In addition, the negative electrode used with Comparative Examples 1 to 2 (anode) corresponds to Comparative Example 3, and the positive electrode used with Comparative Examples 3 to 4 (cathode) corresponds to Comparative Example 1. All of the separators were Toray's 15um thick PE fabric separator coated with a ceramic layer, and for the pouch, DNP's PH3 grade was used. These cells were fully charged under a voltage of 4.15V at 25° C., and a 3 mm diameter nail was used to penetrate the center of the battery, and then ignition was observed. At this time, the nail penetration speed was set to 80 mm/sec.

The results were shown in Table 1 below.

Safety test result Pass/Fail Example 1 HL3 Pass Example 2 HL2 Pass Example 3 HL2 Pass Example 4 HL3 Pass Example 5 HL2 Pass Example 6 HL2 Pass Comparative Example 1 HL5 Fail Comparative Example 2 HL5 Fail Comparative Example 3 HL5 Fail Comparative Example 4 HL5 Fail Hazard level 0: No change.
-Hazard level 1: passive protection activated (No defect, no leakage; no venting, fire or
flame; no rupture; no explosion; no exothermic reaction or thermal runaway. Cell
reversibly damaged. Repair of protetion device needed)
-Hazard level 2: defect/damage (No leakage; no venting, fire, or flame; no rupture; no
explosion; no exothermic reaction of thermal runaway. Cell irreversibly damaged. Repair
needed)
-Hazard level 3: Leakage △ mass <50% (No venting, fire or flame; no rupture; no explosion.
Weight loss <50% of electrolyte(solvent+salt) weight)
-Hazard level 4: Venting△mass ≥ 50% (No fire or flame; no rupture; no explosion.Weight
loss ≥ 50% of electrolyte weight)
-Hazard level 5: ignite or flame (No rupture; no explosion)
-Hazard level 6: rupture (No explosion, but flying parts of the active mass)
-Hazard level 7: Explosion

Claims (10)

It is a manufacturing method of an electrode for secondary batteries,
(S1) preparing an electrode current collector having a plurality of concave portions formed on the surface by pressing the electrode current collector using a roller having a plurality of projections formed thereon; And
(S2) comprising the step of applying an active material slurry consisting of an electrode active material, an electrode binder polymer, and an organic solvent to the electrode current collector in which the concave portion is formed,
The electrode current collector has a thickness of 10 μm to 20 μm,
In step (S1), the press is applied with a linear pressure of 1 to 5 tons, and has a semi-sphere shape having a depth of 1 to 3 µm and a diameter of 1 µm to 6 µm to the current collector by the press. And a concave portion spaced apart in the range of 1 μm to 100 μm is formed,
The electrode current collector in which the concave portion is formed has an elongation in the range of 1/10 to 9/10 compared to the electrode current collector before the concave portion is formed,
The electrode is an anode or a cathode,
When the electrode is a positive electrode, the positive electrode has an elongation of 0.5% to 1.0%, a porosity of 23% to 35%, and the electrode current collector has an elongation in the range of 1.5% to 2.7%,
When the electrode is a negative electrode, the negative electrode has an elongation of 2.0% to 3.5%, and the electrode current collector has an elongation in the range of 6.0% to 7.0%.
The method of claim 1,
The electrode current collector is an aluminum foil (aluminium foil).
The method of claim 1,
The electrode current collector is a method of manufacturing an electrode that is a copper foil. delete delete delete delete delete delete delete

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