KR20080082289A - Electrode assembly and secondary battery having same - Google Patents

Abstract

The present invention relates to an electrode assembly and a secondary battery having the same, and more particularly, to an electrode assembly including a positive electrode plate and a negative electrode plate and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the separator is made of a ceramic separator, but different from each other An electrode assembly and a secondary battery having the same are formed of a ceramic layer.

According to the present invention, the functionality of the ceramic separator is improved, so that flexibility and insulation withstand voltage characteristics are improved.

Description

ELECTRODE ASSEMBLY AND RECHARGEABLE BATTERY WITH THE SAME

1 is an embodiment of a ceramic separator in which the same type of binder is mixed with ceramic fillers having different particle diameters of the same type according to an embodiment of the present invention, in which each layer is formed.

2A to 2D are schematic views illustrating various embodiments of ceramic separators having three layers in which the same kind of binder is mixed with ceramic fillers having different particle diameters.

Figure 3 is an embodiment of a ceramic separator in which each layer is formed by mixing the same kind of binder in the same ceramic filler having a different shape (morphology) according to an embodiment of the present invention.

Figure 4 is an embodiment of a ceramic separator in which the same type of binder is mixed with the heterogeneous ceramic filler according to an embodiment of the present invention each layer is formed.

5A and 5B are diagrams illustrating ceramic separators in which heterogeneous binders are mixed with heterogeneous ceramic fillers according to an embodiment of the present invention, in which respective layers are formed;

6 is an embodiment of a ceramic separator formed by coating a binder on at least one layer of a pre-formed ceramic layer according to an embodiment of the present invention.

7A and 7B are SEM morphologies of alumina powders having different morphologies.

<Description of the symbols for the main parts of the drawings>

11, 21, 31, 41, 51, 61: 1st layer

12, 22, 32, 42, 52, 62: second layer

23: the third floor

The present invention relates to an electrode assembly and a secondary battery having the same, and more particularly to an electrode assembly and a secondary battery having a ceramic separator interposed between the positive electrode plate and the negative electrode plate.

In general, a secondary battery is a battery that can be repeatedly used when recharged, unlike a disposable battery, and is mainly used as a main power source for mobile devices for communication, information processing, and audio / video. The main reason for the recent interest in secondary batteries and rapid development is that secondary batteries are ultralight, high energy density, high output voltage, low self-discharge rate, environmentally friendly battery and long life.

Secondary batteries are divided into nickel-hydrogen (Ni-MH) batteries and lithium-ion (Li-ion) batteries according to electrode active materials. Lithium-ion batteries, in particular, use a liquid electrolyte or a solid polymer electrolyte or gel depending on the type of electrolyte. It can be divided into the case of using the electrolyte of the phase. In addition, according to the shape of the container in which the electrode assembly is accommodated are divided into various types such as can type and pouch type.

Lithium-ion batteries have a much higher energy density per weight than disposable batteries, making it possible to realize ultralight batteries. The average voltage per cell is 3.6V, which is three times the compact effect of 1.2V of other rechargeable batteries such as Ni-Cd batteries or nickel-metal hydride batteries. There is. In addition, lithium ion batteries have a self-discharge rate of less than about 5% per month at 20 ° C, which is about one third of those of nickel-cadmium batteries or nickel-metal hydride batteries. In addition, there is an advantage that can be charged and discharged 1000 times or more in a normal state. Therefore, on the basis of these advantages, with the recent development of information and communication technology, the development is rapidly made.

In the conventional secondary battery, an electrode assembly consisting of a positive electrode plate, a negative electrode plate, and a separator is accommodated in a can made of aluminum or an aluminum alloy, the top opening of the can is closed with a cap assembly, and then the bare cell is injected and sealed with an electrolyte solution inside the can. To form. When the can is formed of aluminum or an aluminum alloy as described above, there is an advantage in that the weight of the battery can be reduced due to the light property of aluminum, and it does not corrode even when used for a long time under high voltage.

The sealed unit bare cell is housed in a separate hard pack in connection with safety devices such as PTC (Thermal Temperature Coefficient), Thermal Fuse and Protective Circuit Module (PCM) and other battery accessories. Or by using a hot melt resin to form a finished appearance through the mold.

Meanwhile, the separator of the electrode assembly is installed to prevent a short circuit between the positive electrode plate and the negative electrode plate between two electrodes. However, if the separator present between the two electrodes does not have sufficient permeability and wettability to the electrolyte, the separator limits the movement of lithium ions between the two electrodes, thereby degrading the electrical characteristics of the battery.

In addition, the separator itself serves as a safety device to prevent overheating of the battery. However, if the temperature of the battery suddenly rises for some reason, for example, due to external heat transfer, the temperature rise of the battery may be continued for a certain period of time even though the micropores of the separator are closed, which may cause breakage of the separator.

In addition, when a large amount of current flows in the secondary battery in a short time due to the high capacity of the battery, even if the micropores of the separator are closed, the separator is continued to melt due to heat generated rather than lowering the temperature of the battery due to the current blocking. There is a greater chance of internal short circuits.

Accordingly, as it is desired to stably prevent internal short circuits between the electrodes even at high temperatures, the separator is composed of a ceramic separator having a porous membrane in which particles of the ceramic filler are combined with a heat resistant binder.

Ceramic separators are generally formed in a single layer using the same type of ceramic filler. If the ceramic separator is a single layer composed of only fine small particles, the ceramic separator is too dense to hinder the smooth movement of lithium ions. Therefore, high-rate charge-discharge and low-temperature charge-discharge capacities are reduced, and if the same amount of binder is used, the smaller the particles, the larger the surface area, and thus, the absolute amount of the binder is insufficient and the flexibility is worsened. .

In addition, when the ceramic separator is a single layer composed of only too large particles, lithium dendrites tend to be formed at large pores, thereby lowering stability. Therefore, in order to improve insulation resistance, discharge characteristics, and the like of the secondary battery, a structure change of the ceramic separator is required.

Accordingly, an object of the present invention is to provide an electrode assembly and a secondary battery including the same, which are devised to solve the above-mentioned problems and improve the functionality of the ceramic separator to improve flexibility and insulation withstand voltage characteristics.

In order to achieve the above object, the electrode assembly according to the present invention is an electrode assembly consisting of a positive electrode plate and a negative electrode plate and a separator interposed between the positive electrode plate and the negative electrode plate, the separator is made of a ceramic separator, but formed of a plurality of different ceramic layers It is characterized by.

In addition, the ceramic separator may be formed by coating on at least one surface of the positive electrode plate or the negative electrode plate.

In addition, the ceramic separator may be a mixture of the same kind of binder in the ceramic filler having a different particle diameter of the same kind may be formed in each layer.

In addition, the ceramic separator may include a first layer formed of a ceramic filler having a particle diameter of 0.4 μm to 0.7 μm and a second layer formed of a ceramic filler having a particle size of 0.1 μm to 0.3 μm.

In addition, the ceramic separator may be formed by mixing the same kind of binder in a ceramic filler having the same morphology.

In addition, the ceramic filler may be made of alumina (Al ₂ O ₃ ).

In addition, the ceramic filler may be spherical, dumbbell-shaped, elliptical or amorphous.

In addition, in the ceramic separator, different types of binders may be mixed with each other to form respective layers.

In addition, the ceramic separator may include a first layer using an insulating filler and a second layer using a dielectric filler.

In addition, the insulating filler may be made of alumina (Al ₂ O ₃ ), and the dielectric filler may be made of barium titanate (BaTiO ₃ ).

In addition, in the ceramic separator, heterogeneous binders may be mixed with heterogeneous ceramic fillers to form respective layers.

In addition, at least one layer of the ceramic separator may be formed by coating a binder on a pre-formed ceramic layer.

In addition, the binder may be coated on the ceramic layer by a spray method.

In addition, another feature of the present invention, in the secondary battery consisting of the electrode assembly, the can and the cap assembly, the separator interposed between the two electrode plates of the electrode assembly may be formed of a plurality of different ceramic layers made of a ceramic separator. It is.

The separator may further include a resin porous film such as polyolefin resin, and the resin porous film is preferably polyethylene or polypropylene.

Hereinafter, with reference to the accompanying drawings illustrating a preferred embodiment of the electrode assembly according to an embodiment of the present invention in detail.

One preferred embodiment of the electrode assembly according to an embodiment of the present invention is composed of a separator which is interposed between the positive electrode plate, the negative electrode plate and the positive electrode plate and the negative electrode plate to prevent short circuit of the positive electrode plate and the negative electrode plate and to allow only movement of lithium ions. The cathode plate, the separator, and the anode plate are stacked and wound.

The positive electrode plate includes a positive electrode current collector, a positive electrode active material layer, and a positive electrode tab.

The positive electrode current collector is formed of a thin aluminum foil, and a positive electrode active material layer containing lithium-based oxide as a main component is coated on both surfaces of the positive electrode current collector. At this time, lithium oxide, such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiMnO ₂ , is used as the cathode active material. In addition, both ends of the positive electrode current collector have a positive electrode non-coating portion, which is a region where the positive electrode active material layer is not formed, at predetermined intervals.

The positive electrode tab is fixed by ultrasonic welding or laser welding to the positive electrode non-coating portion positioned in the inner circumference of the positive electrode non-coating portion. The positive electrode tab is formed of nickel metal, and the upper end portion is fixed to protrude above the upper end portion of the positive electrode current collector.

Meanwhile, the negative electrode plate includes a negative electrode current collector, a negative electrode active material layer, and a negative electrode tab.

The negative electrode current collector is formed of a thin copper foil, and a negative electrode active material layer containing a carbon material as a main component is coated on both surfaces of the negative electrode current collector. In this case, as the negative electrode active material, carbon (C) -based material, Si, Sn, tin oxide, tin alloy composites, transition metal oxides, and the like are used. Also, both ends of the negative electrode current collector are provided with a negative electrode non-coating portion, which is a region where the negative electrode active material layer is not coated.

The negative electrode tab is formed of nickel metal, and the negative electrode tab is fixed by ultrasonic welding to the negative electrode non-coating portion positioned at the inner circumference of the negative electrode non-coating portions at both ends. The negative electrode tab is fixed such that an upper end thereof protrudes above an upper end of the negative electrode current collector.

The separator consists of a ceramic separator. In general, the ceramic separator forms a porous membrane solution to form an evenly dispersed phase of ceramic particles in a mixture of a binder and a solvent, and dips the electrode plate coated with the active material on the current collector into the porous membrane solution. It may be made to surround the whole, or may be made by a method such as spraying the porous membrane liquid on the electrode plate in the form of a spray.

In addition, the separator may further include a polyethylene or polypropylene film.

In addition, the binder is mainly composed of a polymer resin, the polymer resin is preferably made of a polymer of acrylate or methacrylate or a copolymer thereof that can withstand heat of 200 ° C or more. In addition, it is preferable that the said binder is used a small amount in the slurry for porous film formation. In other words, if the ratio of the ceramic material and the binder in the porous film is 98: 2 to 85:15 on a mass basis, the ceramic filler may be prevented from being completely covered by the binder. That is, the problem that the binder covers the ceramic filler and the ion conduction is limited into the ceramic filler can be avoided.

On the other hand, the ceramic separator is formed of a plurality of different ceramic layers.

The ceramic separator may be coated on both sides of the positive electrode plate or the negative electrode plate, and may be formed by coating on either side of the positive electrode plate or the negative electrode plate in consideration of mass production.

In the ceramic separator formed of a plurality of ceramic layers, the same kind of binder may be mixed with ceramic fillers having different particle diameters of the same kind to form respective layers. That is, as shown in FIG. 1, the ceramic separator may include a first layer 11 coated on the positive electrode plate or a negative electrode plate and a second layer 12 coated on the first layer 11. It can be made of a total of two ceramic layers. As such, when using different types of ceramic fillers of the same type, the bending resistance can be improved by adjusting the particle diameter of each layer according to the radius of curvature.

As described above, the first layer 11 and the second layer 12 are formed of ceramic fillers having different particle diameters of the same kind, and the first layer 11 is a ceramic having a particle diameter of 0.4 μm to 0.7 μm. It may be formed of a filler, and the second layer 12 may be formed of a ceramic filler having a particle diameter of 0.1 μm to 0.3 μm. In this case, the same type of binder is used for both the first layer 11 and the second layer 12. The ceramic filler may be made of alumina (Al ₂ O ₃ ) or barium titanate (BaTiO ₃ ).

On the other hand, the ceramic separator may be formed of a ceramic layer of a total of three layers in another embodiment. That is, as shown in Figure 2a, the ceramic separator is a ceramic filler having a different particle diameter layer layer is layered, the first layer 21 coated on the electrode active material layer of the positive electrode plate or negative electrode plate is made of a ceramic filler having the largest particle diameter As the distance from the electrode plate increases, the second layer 22 and the third layer 23 may be formed of a ceramic filler having a small particle size in steps.

In addition, as shown in FIG. 2B, the ceramic separator is formed of a ceramic filler having the smallest particle diameter, and the second layer 22 and the third layer 23 having a ceramic filler having a large particle size in steps. ) May be formed.

In addition, the ceramic separator may form the second layer 22 as the ceramic filler having the smallest particle diameter as shown in FIGS. 2C and 2D, and as shown in FIG. 2C, the first layer 21 may be the largest. It may be formed of a ceramic filler having a particle diameter, or as shown in FIG. 2D, the third layer 23 may be formed of a ceramic filler having the largest particle diameter.

On the other hand, the ceramic layer of the ceramic separator may be any number of two or more layers, but considering the mass production, two to ten layers are suitable, the thickness of the ceramic separator composed of a plurality of ceramic layers is 2㎛ to 50㎛ It is suitable when considering the energy density of the secondary battery.

Table 1 shows the experimental results of the flexibility of the pole plate state, the withstand voltage of the jelly roll state, the deposition of lithium dendrite in the battery state, and the high rate charging and discharging efficiency according to the type of the ceramic separator made of ceramic fillers having different particle diameters. Table showing

In the above experiment, the ratio of the ceramic filler and the binder was fixed at a weight ratio of 95: 5 to prepare pastes for each ceramic particle diameter, and the coatings were dried on the electrodes. In addition, after finishing the polymerization of the binder at 120 ℃ vacuum high temperature, flexibility was measured by observing with a microscope how many cracks (crack) occurs after the end test on the round bar in the plate state.

Thereafter, the jelly roll was placed in a circular can, and the electrolyte solution was poured and then granulated to carry out chemical conversion. The battery under the conditions where lithium dendrite was precipitated was not subjected to high rate charging and discharging for safety, and the discharge rate was measured by charging and discharging only when the lithium dendrite was not precipitated. The divided value is expressed as a percentage.

On the other hand, in the above experiment, since the ceramic separator may serve as a conventional separator, the polyolefin-based film separator was not used, and the electrode plate and the ceramic separator coated with only one side of the positive electrode plate or the negative electrode plate and the ceramic separator were not coated. The plates were phased to form jellyrolls.

Types of ceramic fillers and their particle diameters and types of electrodes Flexibility Jelly Roll Resistance at 250V Lithium dendrite deposition (SEM) High rate charge and discharge efficiency (%) electrode First floor 2nd floor 3rd floor Round Bar Test Withstand voltage test Comparative Example 1 cathode Al ₂ O ₃ 0.1 μm - - 4.5mmФ crack occurrence 5 none 70 Comparative Example 2 cathode Al ₂ O ₃ 0.5 μm - - 3.5mmФ crack occurrence One none 75 Comparative Example 3 cathode Al ₂ O ₃ 1 μm - - 3.0mmФ crack occurrence 0.001 has exist - Example 1 cathode Al ₂ O ₃ 1 μm Al ₂ O ₃ 0.5 μm Al ₂ O ₃ 0.1 μm 2.5mmФ crack occurrence 20 none 90 Example 2 cathode Al ₂ O ₃ 0.1 μm Al ₂ O ₃ 0.5 μm Al ₂ O ₃ 1 μm 2.0mmФ crack crack 15 none 65 Example 3 cathode Al ₂ O ₃ 0.5 μm Al ₂ O ₃ 0.1 μm Al ₂ O ₃ 1 μm 3.0mmФ crack occurrence 14 none 75 Example 4 cathode Al ₂ O ₃ 1 μm Al ₂ O ₃ 0.1 μm Al ₂ O ₃ 0.5 μm 3.0mmФ crack occurrence 13 none 76 Example 5 anode Al ₂ O ₃ 1 μm Al ₂ O ₃ 0.5 μm Al ₂ O ₃ 0.1 μm 3.0mmФ crack occurrence 14 none 91 Example 6 cathode ZrO ₂ 1 μm ZrO ₂ 0.5 μm ZrO ₂ 0.1 μm 2.0mmФ crack crack 16 none 88 Example 7 cathode BaTiO ₃ 1 μm BaTiO ₃ 0.5 μm BaTiO ₃ 0.1 μm 2.0mmФ crack crack 17 none 87

In Comparative Examples 1 to 3, a paste prepared for each particle diameter of the ceramic filler was formed to have a thickness of 30 μm as a single layer on the cathode. If the particle size is too small, the ceramic particles are too densely arranged, and since the specific surface area of the ceramic is large, when the binder is used in 5% by weight, the relative weight is small, thereby reducing the flexibility. If the amount of binder is large, the binder acts as a rubber, and thus the flexibility is improved to some extent, but since it can prevent the smooth movement of lithium ions by blocking side reactions caused by the binder or pores between ceramic particles. The discharge efficiency drops. Therefore, the amount of binder cannot be increased indefinitely in order to increase only flexibility. As shown in Comparative Example 1, when the particles are small, the ceramics are arranged too closely and the binder content is relatively small, so the flexibility is reduced, but the pores are small, thereby improving the voltage resistance. As shown in Comparative Example 3, in the case of a single layer, when the ceramic particle size is too large as 1 μm, pores between the ceramic particles are too large, and lithium dendrite is precipitated after overcharging.

Examples 1 to 4 are cases in which ceramic layers are formed from the first layer to the third layer by particle diameter using alumina (Al ₂ O ₃ ). The first layer represents a portion to be coated on the active material layer of the electrode and was coated with a thickness of 10 μm for each layer.

Example 1 is flexible in that large particles are arranged on the electrode active material side, smaller particles are arranged on the second layer than the first layer, and particles of the smallest size are arranged on the third layer, that is, the layer farthest from the electrode active material. Also excellent and withstand voltage. Moreover, it disassembles after charging, and there is no precipitation of lithium dendrite in a negative electrode. Therefore, the result of confirming the discharge amount relative to the charge amount also shows excellent charge and discharge efficiency.

Example 2 Example 1 and the small size particles in the first layer in the opposite case the array and of larger particles of alumina in the top outside to the case of the largest particles arranged on the larger particles, on top of the (Al ₂ O ₃ ), the relative specific surface area of the alumina (Al ₂ O ₃ ) particles is small. Therefore, when the same amount of binder is used, the amount of binder is larger than that of ceramics of small particles, so the relative flexibility is excellent. However, when high-rate charging and discharging is performed, the alumina (Al ₂ O ₃ ) particles are densely arranged on the surface of the electrode active material, thereby preventing the smooth movement of lithium ions, thereby decreasing the charge and discharge efficiency.

Examples 3 to 4 are the case where the smallest particles are present in the middle layer and the medium and the largest particles of alumina (Al ₂ O ₃ ) are present in the active material side and the layer farthest from the active material, respectively. In this case, the ductility and withstand voltage are somewhat to some extent, but since the smallest particle is present in the intermediate layer, it hinders the smooth movement of lithium ions, thereby slightly decreasing the high-rate charging and discharging efficiency.

Therefore, as in Example 1, it is excellent in terms of safety and performance of the battery that the ceramic layer of the largest particles exists on the active material side and the particles of the small size sequentially form the ceramic layer.

Example 5 is the same as Example 1 except that the alumina (Al ₂ O ₃ ) layer is not coated on the cathode, but the alumina (Al ₂ O ₃ ) layer is formed on the anode. Forming an alumina (Al ₂ O ₃ ) layer on the anode has similar results to that formed on the cathode.

Examples 6 to 7 are the same as those of Example 1, but only the ceramic type is changed from alumina to zirconia (ZrO ₂ ) and barium titanate (BaTiO ₃ ), respectively. In addition to alumina (Al ₂ O ₃ ), a ceramic such as zirconia (ZrO ₂ ) or barium titanate (BaTiO ₃ ) may be used.

Meanwhile, in the ceramic separator, the same kind of binder may be mixed with ceramic fillers having different morphologies of the same kind to form respective layers. That is, as shown in FIG. 3, the ceramic separator may include a first layer 31 coated on the positive electrode plate or a negative electrode plate and a second layer 32 coated on the first layer 31. It can be made of a total of two ceramic layers.

The first layer 31 and the second layer 32 are formed of ceramic fillers having different morphologies of the same type to increase the density of the ceramic layer and to improve insulation resistance and porosity. That is, even in the same ceramic filler, the morphology may be formed into a spherical shape, a dumbbell shape, an elliptical shape, or an amorphous form through a crystallization process or a firing process. The same kind of binder is used for the first layer 31 and the second layer 32, and the ceramic filler is made of alumina (Al ₂ O ₃ ). 7A and 7B show alumina (Al ₂ O ₃ ) powders having different morphologies. FIG. 7A shows a dumbbell-shaped alumina (Al ₂ O ₃ ) powder, and FIG. 7B shows a spherical alumina (Al. ₂ O ₃ ) powder.

In addition, in the ceramic separator, in order to improve the functionality of the ceramic layer, different types of binders may be mixed with each other to form respective layers. That is, as shown in FIG. 4, the ceramic separator may include a first layer 41 coated on the positive electrode plate or a negative electrode plate and a second layer 42 coated on the first layer 41. It can be made of a total of two ceramic layers.

The first layer 41 and the second layer 42 are formed of heterogeneous ceramic fillers. The first layer 41 is formed of an insulating ceramic filler, and the second layer 42 is a dielectric ceramic. By forming the filler, the ion conductivity and the high rate characteristic are improved. On the other hand, the same kind of binder is used for both the first layer 41 and the second layer 42. The insulating filler may be made of alumina (Al ₂ O ₃ ), and the dielectric filler may be made of barium titanate (BaTiO ₃ ).

In addition, in the ceramic separator, heterogeneous binders may be mixed with heterogeneous ceramic fillers to form respective layers. That is, as shown in FIG. 5A, the ceramic separator may include a first layer 51 coated on a negative electrode plate using an aqueous binder and a second layer coated on the first layer 51. 52), a total of two ceramic layers may be formed.

In forming the first layer 51 on the negative electrode plate, an organic binder is used for the first layer 51. This is to prevent the phenomenon that the negative electrode plate swells by melting the negative binder of the negative electrode plate by using an aqueous binder in the first layer 51. In addition, an aqueous binder is used for the second layer 52 to form a ceramic layer on the first layer 51.

In addition, as illustrated in FIG. 5B, the ceramic separator may include a first layer 51 coated on a positive electrode plate using an organic binder and a second layer coated on the first layer 51. 52), a total of two ceramic layers may be formed.

In forming the first layer 51 on the positive electrode plate, an aqueous binder is used for the first layer 51 in the same manner as in the first embodiment, and the second layer 52 is the first layer. An organic binder is used to form a ceramic layer on 51.

The ceramic separator may be formed of a plurality of different ceramic layers, but at least one layer may be formed by coating a binder on a pre-formed ceramic layer. That is, as shown in FIG. 6, in the ceramic separator, a first layer 61 coated with a ceramic filler and a binder is formed on a positive electrode plate or a negative electrode plate, and is formed on the first layer 61. A second layer 62 coated only with a binder may be formed.

In this case, the second layer 62 is formed by coating the first layer 61 in a spray method so that the binder is thickly coated on the first layer 61 so as not to completely close pores of the ceramic layer. It is desirable to be. Therefore, the battery can be charged and discharged by the smooth movement of lithium ions, flexibility is increased, and insulation resistance and porosity can be controlled.

Next, a preferred embodiment of a secondary battery provided with an electrode assembly according to an embodiment of the present invention will be described in detail.

One preferred embodiment of a secondary battery having an electrode assembly according to an embodiment of the present invention includes an electrode assembly, a can containing the electrode assembly, and a cap assembly sealing an open upper portion of the can. .

As described above, the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator that is laminated between the positive electrode plate and the negative electrode plate and laminated. In this case, the separator is made of a ceramic separator is formed of a plurality of different ceramic layers.

In this case, as described above, the same type of binder is mixed with the same type of ceramic filler having different particle diameters, so that each layer is formed, or the same type of binder is used in the ceramic filler having the same shape (morphology). Are mixed to form respective layers, or different types of binders are mixed with different types of ceramic fillers to form respective layers, or different types of binders are mixed with different types of ceramic fillers to form respective layers, or at least one layer is The binder may be formed on the formed ceramic layer.

On the other hand, the can and the cap assembly is made of a general configuration of a secondary battery.

That is, the can is formed of aluminum or an aluminum alloy having a substantially rectangular parallelepiped shape. The electrode assembly is received through the open top of the can so that the can serves as a container for the electrode assembly and electrolyte. The can itself can serve as a terminal.

The cap assembly is provided with a flat cap plate having a size and shape corresponding to the open top of the can. At this time, a tube-shaped gasket is installed between the electrode terminal penetrating the central portion of the cap plate and the cap plate for electrical insulation. In addition, an insulating plate is disposed on the lower surface of the cap plate, and a terminal plate is provided on the lower surface of the insulating plate. In addition, the bottom of the electrode terminal is electrically connected to the terminal plate. The positive electrode tab drawn from the positive electrode plate is welded to the lower surface of the cap plate, and the negative electrode tab drawn from the negative electrode plate is welded to the lower end of the electrode terminal in a state of having a zigzag bent portion.

An electrolyte inlet is formed at one side of the cap plate, and a cap is installed to seal the electrolyte inlet after the electrolyte is injected. The stopper is formed by placing a ball-shaped base material made of aluminum or an aluminum-containing metal on the electrolyte inlet and mechanically inserting it into the electrolyte inlet. The cap is welded to the cap plate around the electrolyte inlet for sealing. The cap assembly is joined to the can by welding the cap plate periphery to the can opening sidewall.

Hereinafter, the operation of the electrode assembly and the secondary battery having the same according to an embodiment of the present invention.

A separator for preventing a short circuit is interposed between the positive electrode plate and the negative electrode plate, and the separator includes a ceramic separator coated on the positive electrode plate or the negative electrode plate. In forming the ceramic separator, unlike the conventional method of forming a single layer, the ceramic separator is composed of a plurality of different ceramic layers. As a result, the functionality is improved by the action of the plurality of ceramic layers formed on the ceramic separator, thereby forming a ceramic insulating layer having excellent insulation withstand voltage characteristics.

The present invention is not limited to the technical spirit of the specific embodiments or drawings described above, and those skilled in the art without departing from the gist of the invention claimed in the claims Various modifications are possible, of course, and such changes are within the scope of the claims of the present invention.

As described above, according to the present invention, the separator that insulates the positive electrode plate and the negative electrode plate is formed of a ceramic separator composed of a plurality of different ceramic layers, thereby improving the functionality of the ceramic separator, thereby providing excellent flexibility and insulation withstand voltage characteristics, and an electrode assembly having the same. There is an effect of providing a secondary battery provided.

Further, another effect of the present invention is to provide an electrode assembly having a porosity, insulation resistance, and improved density and discharge characteristics of a ceramic layer, and a secondary battery having the same.

Claims (16)

An electrode assembly comprising a positive electrode plate and a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, The separator is composed of a ceramic separator, characterized in that formed of a plurality of different ceramic layers. The method of claim 1, The ceramic separator is coated on at least one side of the positive electrode plate or the negative electrode plate, characterized in that formed. The method according to claim 1 or 2, The ceramic separator is an electrode assembly, characterized in that each layer is formed by mixing the same type of binder in a ceramic filler having a different particle size of the same type. The method of claim 3, wherein The ceramic separator includes a first layer formed of a ceramic filler having a particle diameter of 0.4 μm to 0.7 μm, and a second layer formed of a ceramic filler having a particle diameter of 0.1 μm to 0.3 μm. The method according to claim 1 or 2, The ceramic separator is an electrode assembly, characterized in that each layer is formed by mixing the same type of binder in a ceramic filler having a different shape (morphology) of the same type. The method of claim 5, The ceramic filler is an electrode assembly, characterized in that made of alumina (Al ₂ O ₃ ). The method of claim 6, The ceramic filler is an electrode assembly, characterized in that formed in a spherical, dumbbell-shaped, elliptical or amorphous. The method according to claim 1 or 2, The ceramic separator is an electrode assembly, characterized in that each layer is formed by mixing the same type of binder in different types of ceramic filler. The method of claim 8, The ceramic separator is an electrode assembly, characterized in that it comprises a first layer using an insulating filler and a second layer using a dielectric filler. The method of claim 9, The insulating filler is made of alumina (Al ₂ O ₃ ), the dielectric filler is an electrode assembly, characterized in that made of barium titanate (BaTiO ₃ ). The method according to claim 1 or 2, The ceramic separator is an electrode assembly, characterized in that each layer is formed by mixing a heterogeneous binder in a heterogeneous ceramic filler. The method according to claim 1 or 2, At least one layer of the ceramic separator is formed by coating a binder on a pre-formed ceramic layer. The method of claim 12, The binder is an electrode assembly, characterized in that the coating on the ceramic layer in a spray method. The method of claim 1, The separator further comprises a resin porous film. The method of claim 14, The resin porous film is an electrode assembly, characterized in that the polyethylene or polypropylene. In a secondary battery comprising an electrode assembly, a can, and a cap assembly, The separator interposed between the two electrode plates of the electrode assembly is made of a ceramic separator, characterized in that formed of a plurality of different ceramic layers.

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