KR100749626B1 - Secondary battery - Google Patents

Abstract

Provided is a secondary battery to allow the thickness of an electrode plate at an electrode plate pulling part to be constant and to prevent the falling of voltage due to the internal shortage in case of overcharge. A secondary battery comprises a first electrode plate(100) where a first active material(130) is coated; a second electrode plate which has the polarity different from that of the first electrode plate and where a second active material is coated; a separator which is interposed between the two electrode plates; and an electrolyte, wherein the first and second electrode plates have an electrode plate pulling part(150) of zigzag shape at the starting part and the ending part of the coating of the first and second active materials, and a porous layer(170) comprising an inorganic oxide filler and a binder is coated on the at least one pulling part.

Description

Secondary Battery {SECONDARY BATTERY}

1 is a view showing a conventional electrode plate coated with an active material, a schematic diagram showing that a zigzag pole plate drag portion is formed at the beginning and end of the coating,

2 is a view showing a conventional electrode plate with a polymer tape attached to the pole plate attracting portion,

3 is a view showing a pole plate coated with a porous membrane layer in the pole plate attracting portion according to an embodiment of the present invention,

4 to 6 are SEM pictures of the zirconia particles contained in the porous membrane layer according to an embodiment of the present invention, Figures 4 and 5 are secondary particles, Figure 6 is obtained by varying the magnification 1 Photo showing the secondary particles,

7 is a conceptual diagram illustrating a state in which secondary particles made of primary particles are bonded by a binder according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: pole plate 110: collector

130: active material 150: pole plate attracting portion

170: porous membrane layer

The present invention relates to a secondary battery, and more particularly, to cover the electrode plate attracting portion generated by coating the active material on the current collector, and to improve the battery capacity, electrolyte pourability and liquid retention, heat dissipation of the electrode plate, production rate of the electrode plate. It relates to a secondary battery.

In general, a secondary battery refers to a battery that can be charged and discharged, unlike a primary battery that cannot be charged, and is widely used in the field of advanced electronic devices such as a cellular phone, a notebook computer, a camcorder, and the like. In particular, the lithium ion secondary battery has an operating voltage of 3.6V, which is three times higher than nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as power sources for electronic equipment, and is rapidly increasing in terms of high energy density per unit weight. .

Such lithium ion secondary batteries are manufactured in various shapes, and typical shapes include cylindrical shapes, square shapes, and pouch types. Regardless of the shape described above, a lithium ion secondary battery includes a battery part for generating electricity, which is a positive electrode (hereinafter referred to as a “first electrode” or a “first electrode plate”), which is two different electrodes like a conventional chemical battery. And a cathode (hereinafter, used interchangeably with "second electrode" or "second electrode plate").

The positive electrode includes a metal substrate as a current collector, a positive electrode active material, a positive electrode conductive material, and a positive electrode binder. An aluminum foil is used as the metal substrate as the current collector. In addition, a chalcogenide compound is used as the positive electrode active material that substantially generates electricity. For example, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _{1- X} Co _X O ₂ (0 <x <1 ), And a complex metal oxide such as LiMnO ₂ is used. In addition, acetylene black or the like is used as a cathode conductive material that helps move electrons generated from the cathode active material to the current collector. In addition, PVdF (KF1300) is used as the positive electrode binder that binds the positive electrode active material and the conductive material and maintains the mechanical strength of the electrode plate.

Referring to the process of manufacturing the positive electrode, a binder solution is prepared by mixing a binder and a solvent (NMP; N-Methyl-2-Pyrrolidone), and then a cathode active material slurry is prepared by mixing an active material and a conductive agent in the binder solution. This slurry is then coated and dried on a metal substrate as a current collector using a coater. Then, after rolling in order to increase the capacity density of the active material, slitting is performed to obtain a positive electrode plate having a constant width.

The negative electrode includes a metal substrate as a current collector, a negative electrode active material, and a negative electrode binder. Copper foil is used as a metal base material which is an electrical power collector. In addition, as the negative electrode active material that substantially generates electricity, carbon-based materials, Si, Sn, tin oxide, composite tin alloys, transition metal oxides, lithium metal nitrides, or lithium metal oxides are used. In addition, PVdF 1100 is used as a negative electrode binder that binds the negative electrode active material and maintains the mechanical strength of the electrode plate. On the other hand, in the case of the negative electrode, the conductivity of the carbon active material itself is high, so it also plays a role as a conductive material. As a result, a separate conductive material may be used to compensate for this.

Referring to the process of manufacturing the negative electrode, a binder solution is prepared by mixing a binder and a solvent (NMP; N-Methyl-2-Pyrrolidone), and then a negative electrode active material slurry is prepared by mixing an active material and an additive in the binder solution. This slurry is then coated and dried on a metal substrate as a current collector using a coater. Then, after rolling in order to increase the capacity density of the active material, slitting is performed to obtain a negative electrode plate having a constant width.

However, when the positive and negative electrode active material 13 slurry is coated on the current collector 11, as shown in FIG. 1, a zigzag-shaped pole plate attracting portion 15 is generated at the beginning and the end of the coating. If there is such a pole plate 15, the current is concentrated to the site, the resistance is increased and the heat is generated, which threatens the safety of the battery.

In addition, the electrode plate portion 15 is formed in the portion of the electrode is not uniform thickness is uneven, it is easy to precipitate lithium metal during overcharging, lithium dendrite penetrates the separator made of polyethylene (PE) or polypropylene (PP) An internal short may occur, but a minute short may occur even if it is not a hard short, thereby causing a problem such as a voltage drop (OCV DROP) of the battery.

In order to overcome this problem, as shown in FIG. 2, conventionally, an adhesive polymer tape 17 having a component such as polyimide or polypropylene and having an adhesive force is attached to the pole plate drag portion to solve the problem that may occur due to the pole plate drag. I tried to overcome.

However, when the polymer tape 17 is pasted, ion permeation through the polymer tape 17 is impossible, resulting in a problem that the battery capacity decreases by the portion occupied by the tape 17.

In addition, since electrolyte injection through the polymer tape 17 is poorly performed, electrolyte injection characteristics deteriorate, which leads to a decrease in battery production rate.

In addition, the production speed is reduced by the time for attaching a tape to each battery.

In addition, since the monomolecular acrylic resin (eg, acrylonitrile), which is an adhesive component material used for the polymer tape 17, is dissolved in the EC and the like, which is an electrolyte component, the adhesive strength is weakened. May cause the battery to deteriorate, and also react with the electrolyte to produce side reactions, thereby degrading battery life.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and aims to improve the battery capacity, electrolyte pourability and liquid retention, heat dissipation of the electrode plate, and production rate of the electrode plate while covering the electrode plate drag portion.

Secondary battery according to the present invention for achieving this object,
A first electrode plate coated with a first active material; A second electrode plate having a polarity different from that of the first electrode plate and coated with a second active material; A separator interposed between the two electrode plates; And a secondary battery comprising an electrolyte, wherein the first and second electrode plates are provided with a zigzag pole plate drag portion at the beginning and the end of the first and second active material coatings, respectively, and the first and second electrode plates. At least one of the pole plate attracting portion, characterized in that the porous membrane layer comprising an inorganic oxide filler and a binder of the inorganic oxide filler is coated.

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In this case, the porous membrane layer is preferably formed so as to cover at least the entire region where the electrode plate drag portion is formed.

Moreover, it is preferable that the thickness of the said porous film layer is 3-50 micrometers.

Moreover, it is preferable that the area of the said porous film layer is 0.5 to 50% of the said electrode plate area.

In addition, the porous membrane layer preferably has a porosity of 50% or more.

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In addition, the weight ratio of the inorganic oxide filler and the binder of the filler is preferably in the range of 98: 2 to 85:15.

In addition, the binder of the filler is preferably in close contact with the inorganic oxide filler in a point bonding manner.

In addition, the inorganic oxide filler may be a semiconductor filler having a band gap.

In addition, the inorganic oxide filler may be secondary particles obtained by partially sintering or dissolving and recrystallization of primary particles of a ceramic material having a band gap.

In addition, the inorganic oxide filler is alumina (α-Al ₂ O ₃ ), zirconia (ZrO ₂ ), titanium oxide (Anatase-TiO ₂ ), silica (SiO ₂ ), zeolite, magnesium oxide (MgO), calcium carbonate (CaCO _It may be any one selected from ₃ ).

In addition, the binder of the filler is a secondary battery, characterized in that made of a polymer resin.

In addition, the binder of the filler is preferably heterogeneous to the binder of the electrode plate active material.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment according to the present invention.

Although secondary batteries are manufactured in various shapes, typical shapes include cylindrical, square and pouch types. Regardless of the shape described above, the secondary battery includes a battery part that generates electricity, and the battery part includes first and second electrode plates having a different polarity, a separator, and an electrolyte as in a conventional chemical cell.

Referring to the process of manufacturing the first electrode plate, a binder solution is prepared by mixing a binder and a solvent (for example, N-Methyl-2-Pyrrolidone (NMP)), and then the first active material and the conductive agent are mixed with the binder solution to form the first active material. Prepare a slurry. This slurry is then coated and dried using a coater onto a metallic substrate (eg, aluminum) that is the current collector. Then, after rolling in order to increase the capacity density of the active material, slitting is performed to obtain a first electrode plate having a constant width. However, the content of the present invention is not limited thereto. Here, the active material slurry is a state containing a solvent, and the active material is a state in which the active material slurry is dried and the solvent is removed.

In the process of manufacturing the second electrode plate, a binder solution is prepared by mixing a binder and a solvent (for example, N-Methyl-2-Pyrrolidone (NMP)), and then a second active material slurry is mixed with the second active material and an additive in the binder solution. To prepare. This slurry is then coated and dried using a coater on a metallic substrate (eg copper) that is the current collector. Then, after rolling in order to increase the capacity density of the active material, slitting is performed to obtain a second electrode plate having a constant width. However, the content of the present invention is not limited thereto.

The separator may be made of polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene. The separator is interposed between the first electrode plate and the second electrode plate to insulate between the two electrode plates, and it is advantageous to form a wider width than the first and second electrode plates to prevent a short circuit between the two electrode plates. In addition, the separator is formed of a porous membrane to allow the movement of the electrolyte and the ions through the separator.

The electrolyte may be a liquid electrolyte and a polymer electrolyte. A battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is also called a lithium polymer battery. In the case of a lithium secondary battery, even when using a liquid electrolyte, a nonaqueous electrolyte is used because of the reactivity of lithium and water (H ₂ O). As the non-aqueous electrolyte is used, the lithium ion battery may have a relatively high battery voltage because it is not controlled by the decomposition voltage of water during charging. The liquid electrolyte has a state in which the lithium salt is dissociated in the organic solvent. As a solvent in which the lithium salt is dissolved, ethylene carbonate, propylene carbonate or other alkyl group-containing carbonate or similar organic compound may be used. However, the content of the present invention is not limited thereto.

Meanwhile, as shown in FIG. 3, when the slurry of the active material 130 is coated on the current collector 110, a zigzag pole plate drag portion 150 is formed at a coating start portion and a coating end portion, and the pole plate draw portion 150 is formed. ) Is coated with a porous film layer 170 including an inorganic oxide.

The pole plate 100 shown in FIG. 3 may be a first pole plate or a second pole plate, and in the drawing, the porous membrane layer 170 is formed on the pole plate drag portions 150 at both the coating start and the coating end portions. However, it may be formed at the pole plate drag portion on one side of the coating start or coating end. In addition, although FIG. 3 illustrates only one surface of the electrode plate 100, the active material may be coated on the opposite surface to form the electrode plate drag portion, and the porous membrane layer may be coated on the electrode plate drag portion.

The porous membrane layer 170 serves to keep the thickness of the pole plate 100 constant at the pole plate drag portion 150 as in the conventional polymer tape, and to prevent a voltage drop due to internal short-circuit during overcharging.

Furthermore, unlike the conventional polymer tape, since the porous membrane layer 170 has a large number of holes, ions can be moved through the porous membrane layer, and thus, ions can be moved even in a portion where the porous membrane layer 170 is coated, thereby providing battery capacity. This decreasing problem does not occur. In addition, since the porous membrane layer 170 has a high porosity, the electrolyte pourability is also improved, and the liquid retention property is also good, so that the battery life is also improved. In addition, even if heat is generated due to current concentration in the pole plate drawer 150, heat generation through the porous membrane layer 170 may be easily performed, thereby lowering the temperature. In addition, in terms of process, it is easier to coat than attaching a tape, thereby increasing the production speed. In addition, there is no problem of dissolving in the electrolyte component or reacting with the electrolyte to produce a side reaction.

Referring to FIG. 3, the porous membrane layer 170 is formed to cover at least the entire region where the electrode plate drag portions 150 are formed. This is because when the part of the pole plate drawer 150 is exposed, there is a risk that a heat generation problem due to the conventional current concentration, a nonuniformity of the pole plate thickness, and an internal short problem may occur. In addition, the porous membrane layer may be formed not only on the pole plate attracting portion but also on the whole plate, which greatly increases the process cost and time and has a problem of mass productivity that is difficult to coat with a uniform thickness as a whole.

In addition, it is preferable that the area of the porous film layer 170 is 0.5 to 50% of the area of the electrode plate 100. If it is formed too narrow, there is a risk that the pole plate drag portion 150 is exposed, if too wide formed there is a problem of the process cost, time and mass production described above.

The porous membrane layer 170 may include an inorganic oxide filler and a binder of the filler. In the present exemplary embodiment, the porous membrane layer 170 is not formed as a separate film, and the porous membrane liquid or the precursor liquid of the porous membrane is coated on at least one of the surfaces covered with the active material 130 of the electrode plate 100. The solvent is then removed from the porous membrane solution or formed by curing the precursor.

That is, in order to form the porous membrane layer 170, first, an inorganic oxide filler is mixed and mixed with a binder to form an inorganic oxide paste. Next, this inorganic oxide paste is applied to a predetermined electrode plate surface. The paste application may be performed by a partial printing method or a spray method on the electrode plate surface. Next, after controlling the thickness of the porous membrane layer with a gravure roller, the solvent is removed by baking to form the porous membrane layer 170. Various other methods can be used for forming a porous film layer.

Here, the inorganic oxide filler is alumina (α-Al ₂ O ₃ ), zirconia (ZrO ₂ ), titanium oxide (Anatase-TiO ₂ ), silica (SiO ₂ ), zeolite, magnesium oxide (MgO), calcium carbonate (CaCO _It may be any one selected from ₃ ). However, the content of the present invention is not limited thereto.

In this case, the inorganic oxide filler may be a semiconductor filler having a band gap. In this case, the separator may not be provided in the portion of the electrode plate 100 corresponding to the portion where the porous membrane layer 170 is formed. That is, the porous membrane layer 170 may serve as a separator. The separator insulates the two pole plates and acts as a passage for ions, but it also shuts down when the temperature of the battery is above a certain level to cut off the current. When the inorganic oxide filler is a semiconductor filler, a current corresponding to the shutdown of the separator by suppressing the movement of ions by the p / n semiconductor function generated at high temperature between the inorganic oxide filler and the ion-containing material (for example, lithium ions) The blocking role is played and safety can be secured.

In addition, the inorganic oxide filler may be secondary particles obtained by partially sintering or dissolving and recrystallization of primary particles of a ceramic material having a band gap. Here, the secondary particles may be formed by agglomeration of at least three primary particles. As a method of forming such secondary particles, partial sintering of primary particles, total dissolution or recrystallization after partial dissolution can be proposed. When all the ceramic materials are dissolved and recrystallized, the primary particles may be precipitated in a cohesive shape, and thus the primary particles and the secondary particles may be simultaneously formed.

In one embodiment, a ceramic material such as zirconia (ZrO ₂ ) is heated at 900 ° C. for about 10 minutes to obtain some sintered particle structure. The ceramic material may be re-precipitated by dissolving all of the ceramic material using a solvent having high solubility in the ceramic material, or by partially dissolving a portion of the solvent in the primary particle powder and then removing the solvent.

4 to 6 are SEM pictures of the zirconia particles contained in the porous membrane layer according to an embodiment of the present invention, Figures 4 and 5 are secondary particles, Figure 6 is obtained by varying the magnification 1 Photograph showing the primary particles.

Referring to the drawings, the secondary particles consist of a group of grains (grapes) or layered. In order to achieve a state in which the group of particles in the form of a layer or a layer is bound by a binder, first, the first particles of the ceramic material form a secondary particle, that is, a group of particles in a condensed state. When the primary particles are in a flattened state, the secondary particles may be a group of stacked particles in which primary particles are partially sintered and stacked.

It is preferable that the diameter of the said primary particle or individual particle | grains which form a spine exists in the range of 0.01-0.3 micrometer, and the scale-shaped individual flake which forms a layered particle group is 0.1 to 1 micrometer in width. The thickness of the porous membrane layer including such a particle group may be about 3 to 50㎛.

7 is a conceptual diagram illustrating a state in which secondary particles made of primary particles are bonded by a binder according to an embodiment of the present invention.

Referring to the drawings, the binder of the filler is in close contact with the inorganic oxide filler in a point bonding method. A powder composed of secondary particles is mixed with a binder and a solvent to form a porous membrane liquid. When the binder binds the secondary particles while covering the entire surface of each secondary particle and the ion conductivity of the binder is small, ion conduction through the inside of the secondary particles may not be performed smoothly. Therefore, in order to increase the ion conductivity of the porous membrane layer irrespective of the ion conductivity of the binder, the binder exists only on a part of the surface of the secondary particles as indicated by the rectangle between the secondary particles made of the primary particles as shown by the arrow in FIG. It is preferable to combine the secondary particles in the form of a bridge connecting the secondary particles.

For this purpose, the binder is preferably used in a small amount in the porous membrane liquid. When the weight ratio of the inorganic oxide filler (ceramic material) and the binder binder in the porous membrane solution of the present invention is in the range of 98: 2 to 85:15, the inorganic oxide filler can be prevented from being completely covered by the binder. That is, the problem that the binder covers the filler material and the ion conductivity is limited into the filler material can be avoided.

In the porous membrane layer thus formed, both the microporosity of the ceramic material itself, the pores between the individual primary particles in the particle group forming the spherical structure, and the pores between the group of spherical particle groups bonded by the filler binder are all porous membranes. Contribute to increasing the porosity of As a result, all of these pores contribute to increase electrolyte permeability and ion mobility in the porous membrane layer.

It is preferable that the porosity of a porous film layer is 50% or more. In order to obtain a porosity of 50% or more, first, the proportion of the binder of the filler is preferably 20% or less, and second, it is important that the binder itself does not expand. In particular, it is important that the expansion or swellability by the electrolyte is low.

In order to reduce the amount of binder, it is necessary to disperse the binder evenly. Since this operation is of high difficulty, it is difficult to obtain a stable film having high porosity in the past. However, when some sintered ceramic material is used as a filler and an acrylate rubber binder, which is a polymer resin, is used as a filler, the binder can be easily dispersed and a film having a large porosity can be obtained with a small amount of binder.

Here, the acrylate rubber-based binder is excellent in binding strength to other materials and low in expansion rate. When the acrylate rubber-based binder is used, it is treated to exist in the oligomer state, which is an intermediate state between the monomer and the polymer at room temperature, and stored in a mixed state with a solvent, that is, a binder solution, to make an inorganic oxide paste.

In addition, the binder of the filler may be made of one of a polymer of acrylate or methacrylate or a copolymer thereof.

One example of the binder exhibiting the best properties is a polymer resin consisting of 10% by weight of 2-ethyl hexyl acrylate and 90% by weight of polymethyl methacrylate (PMMA) having a molecular weight of about 1 million. At this time, in order to improve life and stability, PMMA has a double bond in the main chain molecule, and has 2 to 10 crosslinking points in 10,000 molecular weight units, and preferably 4 to 5. As a basis for causing the crosslinking reaction, a part of PMMA capped with an alkali metal (Na, K) is mixed, and a binder having a structure of crosslinking after liberating the alkali metal at 160 ° C is used.

It is preferable that the binder of such a filler is heterogeneous with the binder of an electrode plate active material. For example, when the porous membrane layer (inorganic oxide layer) is formed on the negative electrode (second electrode plate), if the binder of the negative electrode active material is water-based (for example, SBR), the binder of the filler used in the porous membrane layer is combined using an organic type. . In addition, if the binder of a negative electrode active material is organic type (for example, PVDF type), the binder of the filler used for a porous film layer is combined using an aqueous system. If the same organic or water-based binder is used for the active material layer and the porous film layer, the same organic or water-based solvent must be used. This is because the problem of re-dissolving in the solvent may occur.

On the other hand, when the organic solvent is used as the binder of the filler, a solvent having a weight ratio of 0: 100 to 50:50 of NMP and cyclohexanon is used as the solvent for the inorganic oxide paste, or NMP is used as the solvent. Instead, isopropylachole, toluen, and xylene may be used. If the binder of the negative electrode active material is organic, it is possible to use water as the solvent for the binder of the filler.

Table 1 below relates to the data of the battery temperature during overcharging, the battery temperature during high-rate discharge, and the lifespan according to the type of inorganic oxide contained in the porous membrane layer.

Table 1 Characteristic data according to the type of inorganic oxide contained in the porous membrane layer

division Top plate coating Share time (minutes) Volume (%) Battery temperature at 2C overcharge (℃) Battery temperature at 2C high rate discharge (℃) % Lifetime at 300 cycles Comparative Example 1 none 6.35 100 80.6 56.3 90.7 Comparative Example 2 Polymer tape 9.71 94.4 62.3 40.1 83.3 Example 1 Alumina (α-Al ₂ O ₃ ) 4.65 102.3 55.6 36.5 95.4 Example 2 Zirconia (ZrO ₂ ) 5.39 101.4 60.2 34.7 94.5 Example 3 Titanium Oxide (Anatase-TiO ₂ ) 5.23 99.5 56.8 40.2 96.4 Example 4 Silica (SiO ₂ ) 4.87 99.6 45.6 37.8 93.4 Example 5 Zeolite 5.33 99.9 52.6 39.1 92.5

Comparative Example 1 is a battery prepared by preparing a negative electrode and a positive electrode using a conventional negative electrode active material, a positive electrode active material, a binder, and a solvent, and having a polyethylene (PE) separator. Both positive and negative electrodes have a zigzag pole plate drag phenomenon at the beginning and end of the slurry coating.

In Comparative Example 2, a cylindrical battery was fabricated by coating (laminating) the polymer plate with the drag portions of both positive and negative pole plates made in the same manner as Comparative Example 1 to cover the pole plate trailing portions.

The positive and negative electrodes of Examples 1 to 5 are the same as in Comparative Example 2, and the kinds of inorganic oxides used for laminating are different. The binder used for preparing the inorganic oxide was an acrylate-based binder in which 10 wt% was added to the ceramic powder, and as a solvent, a solvent having a weight ratio of NMP: cyclohexanone of 5: / 5 was used.

Both the Comparative Example and the Example made the cylindrical cell using the same electrolyte.

In Example 1, a ceramic paste was prepared by using alumina as an inorganic oxide, and the coating was dried by laminating the electrode plate.

In Example 2, a ceramic paste was prepared using zirconia as an inorganic oxide, and the coating was dried by laminating the electrode plate portions.

In Example 3, a ceramic paste was prepared using titanium oxide as an inorganic oxide, and the coating was dried by laminating the electrode plate portions.

In Example 4, a ceramic paste was prepared using silica as the inorganic oxide, the coating was dried on the electrode plate, and subjected to laminating.

In Example 5, a ceramic paste was prepared by using zeolite as an inorganic oxide, and the coating was dried by laminating the electrode plate portions.

For the batteries made in the same manner as in Comparative Example and Example, the electrolyte was injected and the time for all injection was measured. The pouring method is as follows. After aligning the injection hole of the battery with the jig, put the electrolyte on the top of the jig and put it in the open state in the vacuum chamber. After extracting the vacuum to 10 mbar, air was added at atmospheric pressure, and the time until all the electrolyte in the jig entered the injection hole of the battery was measured and indicated in [Table 1].

Next, the batteries produced in the same manner as in Comparative Examples and Examples were cut-off at 1C / 4.2V 10mA under CC / CV constant current / constant voltage conditions, and 1C 3V cut-off discharge under CC constant current conditions were checked for capacity. The value calculated using the capacity of Comparative Example 1 as 100% is shown in [Table 1].

When the battery of Comparative Example 1 had a capacity of 100%, the lamination with a polymer tape as in Comparative Example 2 caused a capacity reduction of about 6%. However, as in Examples 1 to 5, lamination with an inorganic oxide layer (porous membrane layer) resulted in almost no decrease in capacity.

Next, the battery made as in Comparative Example and Example was fully charged with 1C / 4.2V 10mA cutoff under CC / CV constant current / constant voltage condition, and then overcharged with 1C / 12V 60 minutes under CC / CV constant current / constant voltage condition. The maximum temperature outside the cell was measured with a thermal couple.

Similarly, a battery fully charged with 1C / 4.2V 10 mA cut-off under CC / CV constant current / constant voltage condition was discharged by 2C 3V cut-off high rate under CC constant current condition, and the maximum temperature outside the cell at the time of discharge was measured by a thermocouple.

As can be seen in Table 1, in Comparative Example 2 laminated with a polymer tape than Comparative Example 1, the battery temperature was lowered during overcharging and high rate discharge, indicating that laminating was effective.

Similarly, also in Examples 1 to 5 of the present invention, it was confirmed that there was a heat dissipation effect equal to or greater than that in the case of laminating the polymer tape.

Next, charging / discharging was performed 300 times in such a manner that the 1C / 4.2V 10mA cut-off charged battery under CC / CV constant current / constant voltage condition was discharged by 1C 3V cut-off discharge under CC constant current condition. The discharge capacity of the 300th time was written in% compared with the discharge capacity of the 1st time. When polymer tape lamination was carried out as in Comparative Example 2 than in Comparative Example 1, the cycle capacity retention was reduced by 7%. However, in Examples 1 to 5 in which the inorganic oxide layer lamination was performed, the capacity retention rate was superior to that of Comparative Example 1. The cycle characteristics are improved because the inorganic oxide layer has high porosity and excellent electrolyte retention.

According to the present invention, the porous membrane layer coated on the pole plate attracting portion maintains the thickness of the pole plate at the pole plate attracting portion like the conventional polymer tape and prevents the voltage drop due to the internal short when overcharged.

Furthermore, unlike the conventional polymer tape, since the porous membrane layer has a lot of pores, the ions can be moved through the porous membrane layer, so that the ions can be moved even in a portion where the porous membrane layer is coated, thereby reducing battery capacity. I never do that.

In addition, since the porous membrane layer has a high porosity, the electrolyte pourability is also improved, and the liquid-retaining property is also good, thereby improving battery life.

In addition, even when heat is generated due to current concentration in the pole plate attracting portion, heat generation through the porous membrane layer is easy, thereby lowering the temperature.

In addition, in terms of process, it is easier to coat than attaching a tape, thereby increasing the production speed.

In addition, there is no problem of dissolving in the electrolyte component or reacting with the electrolyte to produce a side reaction.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and the present invention may encompass various modifications and equivalent other embodiments that can be made by those skilled in the art. Will understand.

Claims (22)

A first electrode plate coated with a first active material; A second electrode plate having a polarity different from that of the first electrode plate and coated with a second active material; A separator interposed between the two electrode plates; And In a secondary battery comprising an electrolyte, The first and second electrode plates are provided with a zigzag pole plate trailing portion at the beginning and the end of the first and second active material coatings, respectively, and at least one pole plate trailing portion of the first and second electrode plates, the inorganic oxide A secondary battery characterized in that the porous membrane layer comprising a filler and a binder of the inorganic oxide filler is coated. The method of claim 1, And the porous membrane layer is formed to cover at least the entire region where the electrode plate drag portion is formed. The method of claim 1, The thickness of the porous membrane layer is a secondary battery, characterized in that 3 to 50㎛. The method of claim 1, The area of the porous membrane layer is a secondary battery, characterized in that 0.5 to 50% of the area of the electrode plate. The method of claim 1, The porous membrane layer is a secondary battery, characterized in that the porosity is 50% or more. delete The method of claim 1, A secondary battery, characterized in that the weight ratio of the inorganic oxide filler and the binder binder is in the range of 98: 2 to 85:15. The method of claim 1, The secondary battery, characterized in that the binder of the filler is in close contact with the inorganic oxide filler in a point bonding method. The method of claim 1, The inorganic oxide filler is a secondary battery, characterized in that the semiconductor filler having a band gap. The method of claim 1, The inorganic oxide filler is a secondary battery, characterized in that the secondary particles formed by sintering or dissolving and recrystallization of primary particles of a ceramic material having a band gap. The method of claim 10, The secondary particle is a secondary battery, characterized in that the at least three primary particles are aggregated. The method of claim 10, The secondary battery is characterized in that consisting of a group of particles in the shape of a staple (grape-shaped) or layered. The method of claim 12, The secondary battery, characterized in that the diameter of the primary particles forming a spin in the range of 0.01 ~ 0.3㎛. The method of claim 12, The width of the primary particles forming a layer is in the range of 0.1 ~ 1㎛, lithium ion secondary battery, characterized in that the flaky flakes. The method of claim 1, The inorganic oxide filler is any one selected from alumina (α-Al2O3), zirconia (ZrO2), titanium oxide (Anatase-TiO2), silica (SiO2), zeolite, magnesium oxide (MgO), calcium carbonate (CaCO3) Secondary battery. The method of claim 1, The binder of the filler is a secondary battery, characterized in that made of a polymer resin. The method of claim 16, The polymer resin is a secondary battery, characterized in that the acrylate rubber (acrylate rubber) series. The method of claim 17, The acrylate rubber-based binder is a secondary battery characterized in that the capping with Na or K. The method of claim 16, The binder of the filler is a secondary battery having a double bond in the main chain molecule, and has a crosslinking point of 2 to 10, preferably 4 to 5 in 10,000 molecular weight units. The method of claim 16, The polymer resin is a secondary battery, characterized in that made of one of a polymer of acrylate or methacrylate or a copolymer thereof. The method of claim 20, The polymer resin is a secondary battery, characterized in that consisting of 10% by weight of 2-ethyl hexyl acrylate, 90% by weight of polymethyl methacrylate (PMMA; Poly Methyl Meta Acrylate) of approximately 1 million molecular weight. The method of claim 1, The binder of the filler is a secondary battery, characterized in that the heterogeneous with the binder of the electrode plate active material.

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