JP2003208890A - Plate for non-aqueous secondary battery and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate having excellent productivity and a high battery capacity, and to provide a battery using the same. <P>SOLUTION: In this plate for a non-aqueous secondary battery, an active material mix layer is coated on a foil-like collector 10 to form a coating part 11, and the coating parts 11 are intermittently arranged with a non-coating part 12. Density of a coating start end 13 of the coating part 11 adjacent to the non-coating part 12 is set at 102-150 when density of other parts is set as 100. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrode plate for a non-aqueous secondary battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the rapid miniaturization and diversification of consumer mobile phones, portable electronic devices, personal digital assistants, etc., they have a high energy density as a power source battery and are repeatedly charged and discharged for a long time. There is a strong demand for the development of possible secondary batteries. As a secondary battery satisfying such requirements, it has a several times higher energy density than a conventional battery using an aqueous electrolyte solution, so a non-aqueous electrolyte such as a polymer solid electrolyte or an organic solvent is used. The non-aqueous secondary battery used has already been put to practical use. Examples of this non-aqueous secondary battery include a positive electrode containing a positive electrode active material that reversibly electrochemically reacts with lithium ions, and a lithium ion storage / storage device.
A lithium ion secondary battery including a negative electrode containing a releasable negative electrode active material and a non-aqueous electrolyte containing a lithium salt can be given.

In the non-aqueous secondary battery, in order to enable high-rate charging / discharging, the electrode plate is formed into a sheet, and a spiral structure in which these are wound in a roll shape with a separator interposed therebetween makes the reaction area as small as possible. It is designed to be wider. The electrode plate, a paste-like or slurry-like active material mixture prepared by dispersing or dissolving an active material, a binder and a conductive agent in a suitable solvent is applied to a current collector made of a metal foil. It is obtained by

Usually, the metal foil surface of the current collector is exposed on the electrode plate such as a portion where a terminal for taking out an electric current is ultrasonically welded and a boundary portion between adjacent active material layers. A coating section is provided. The non-coated portion is formed by uniformly coating the active material mixture on the surface of the current collector while providing the non-coated portions at regular intervals.

[0005]

However, in the conventional electrode plate, a current collecting lead is ultrasonically welded to the non-coated portion,
When the electrode plate is wound, the end of the active material mixture layer may be chipped off and fall off, which causes a problem that the productivity of the battery is reduced.

In order to prevent the active material mixture layer from falling off, the active material mixture layer is compressed at a high pressure to improve the adhesiveness between the active material mixture layer and the current collector or to activate the active material mixture layer. Measures such as improving the strength of the material mixture layer or increasing the amount of the binder to increase the adhesiveness between the active materials can be considered.

However, if the whole active material mixture layer is compressed at a high pressure, the whole active material mixture layer becomes hard,
There is a problem that the electrode plate is easily broken when the electrode plate is wound. In addition, since the pore volume of the active material mixture layer is reduced, the infiltration of the non-aqueous electrolyte solution is reduced, and the battery capacity is reduced. On the other hand, when the amount of the binder is increased, the amount of the active material in the electrode is decreased, so that the battery capacity is decreased.

The present invention was completed in view of the above circumstances, and an object of the present invention is to provide an electrode plate having excellent productivity and high battery capacity, and a method for manufacturing the same.

[0009]

Means for Solving the Problems and Actions / Effects As a means for achieving the above object, the invention of claim 1 is one in which an active material mixture layer is formed on a foil-shaped current collector and the active material mixture layer is formed. In an electrode plate of a non-aqueous secondary battery in which a material mixture layer is formed so as to be intermittently arranged with a non-coated portion interposed therebetween, an end portion of the active material mixture layer adjacent to the non-coated portion. Is set to be not less than 102 and not more than 150 when the density of other portions is 100.

First, when the density of the end portion of the active material mixture layer adjacent to the non-coated portion (hereinafter referred to as the end portion of the active material layer) is 100 when the density of other portions is 100, By setting the ratio to 150 or less, the strength of the end portion of the active material layer can be improved. Therefore, when the lead is welded or the electrode plate is wound, it is possible to prevent the end portion of the active material layer from falling off due to stress, and as a result, the productivity of the electrode plate can be improved.

Next, since the decrease in flexibility of the electrode plate can be minimized by increasing only the density of the end portion of the active material layer, the decrease in the flexibility of the electrode plate causes Breaking can be prevented. As a result, the productivity of the electrode plate can be improved. Further, since it is also possible to prevent the pore volume of the active material mixture layer other than the end portion of the active material layer from being excessively reduced, the infiltration of the nonaqueous electrolyte into the active material mixture layer does not decrease, and a high capacity can be obtained. The provided electrode plate can be obtained.

If the density of the end portion of the active material layer is less than 102 when the density of the other portion is 100, the strength of the end portion of the active material layer is insufficient, so that the lead is welded or the electrode plate is wound. Due to the stress applied at the time of rotation, the end of the active material layer is chipped and falls off. On the other hand, if it exceeds 150, the end portion of the active material layer becomes excessively hard and the flexibility is reduced, so that the electrode plate is broken at the end portion of the active material layer at the time of lead welding or winding of the electrode plate. . From the above, the density of the end portion of the active material mixture layer adjacent to the non-coated portion is 100 times that of the other portion.
In this case, it is preferably 102 or more and 150 or less. More preferably, it is 110 or more and 140 or less.

According to a second aspect of the present invention, the active material mixture layer is formed on the foil-shaped current collector, and the active material mixture layer is formed so as to be intermittently arranged with the non-coated portion interposed therebetween. A method of manufacturing an electrode plate of a non-aqueous secondary battery, wherein an active material mixture is intermittently applied to the current collector with the non-coated portion interposed therebetween,
After coating so that the active material mixture locally rises at the coating starting end portion following the non-coating portion, the entire coating portion is flatly compressed, whereby the activity at the coating starting end portion is achieved. It is characterized in that the density of the material mixture layer after compression is 102 or more and 150 or less when the density of other portions is 100.

By manufacturing the electrode plate by the above method, it is possible to improve the strength of the coating starting end portion without requiring an extra step. Therefore, in addition to the effect of the invention of claim 1, An electrode plate with excellent productivity can be obtained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of the electrode plate of the present invention. In the electrode plate of FIG. 1, the active material mixture layer is applied to one surface of the elongated current collector 10 to form a coating portion 11, and the coating portion 11 exposes the surface of the current collector. The non-coated portions 12 are formed so as to be intermittently lined up. The coating portion 11 has a coating starting end portion 13, and the density of the active material mixture layer in the coating starting end portion 13 is 102 or more 1 when the density of other portions is 100.
It is 50 or less. When the active material layers are provided on both sides of the current collector, it is preferable that both sides satisfy the above conditions.

FIG. 2 is a schematic cross-sectional view showing an example of the method for manufacturing the electrode plate of the present invention. In the electrode plate 10 manufactured by the manufacturing method of the present invention, the active material mixture is intermittently applied to one surface of the elongated current collector 10 with the non-coating portion 12 interposed therebetween, and It is manufactured by coating the active material mixture so that the active material mixture locally rises at the coating start end portion 13 subsequent to the coating portion 12, and then flatly compressing the entire coating portion. The density of the active material mixture layer in the coating starting end portion 13 after compression is 102 or more and 150 or less when the density of other portions is 100. When the active material layers are provided on both sides of the current collector, it is preferable that both sides are manufactured by the above method.

FIG. 3 is a perspective view of a bag-shaped non-aqueous secondary battery 1 according to an embodiment of the present invention. In FIG. 3, 1 is a bag-shaped non-aqueous secondary battery, 2 is a battery exterior body, 3 is a power generation element,
4 is a positive electrode lead terminal, 5 is a negative electrode lead terminal, 6 is a back sealing portion, 7 is a bottom sealing portion, and 8 is a sealing portion.

As shown in FIG. 4, the bag-shaped non-aqueous secondary battery 1 comprises a power-generating element 3 in which a positive electrode plate and a negative electrode plate are wound in an elliptical shape with a separator in between, and a metal laminated resin film. The back sealing portion 6 and the bottom sealing portion 7 were formed by heat fusion to form a bag-shaped battery exterior body 2 and the nonaqueous electrolytic solution containing an electrolyte salt (not shown) was inserted from the opening. After that, the positive electrode lead terminal 4 and the negative electrode lead terminal 5 led out from the power generation element 3 are heat-sealed and sealed in a state in which the positive electrode lead terminal 4 and the negative electrode lead terminal 5 are projected from the opening.

Lithium ions can be used as the positive electrode active material.
It is possible to use compounds that can be inserted and removed in reverse.
You can Examples of such compounds include the following substances
Is mentioned. As the inorganic compound, a composition formula Li_xMO
_Two(M is a transition metal, 0 ≦ x ≦ 1), or a composition formula Li_y
M_TwoO_Four(M is a transition metal, 0 ≦ y ≦ 2)
Um-transition metal composite oxide, acid with tunnel-like vacancies
Compound, metal chalcogenide having a layered structure, etc.
it can. Specific examples of these include LiCoO 2. _Two, Li
NiO_Two, LiMn_TwoO_Four, Li_TwoMn_TwoO_Four, MnO
_Two, FeO_Two, V_TwoO₅, V₆O_Thirteen, TiO_Two, Ti
S_TwoEtc. Also, as an organic compound, for example,
Examples thereof include conductive polymers such as polyaniline.
Furthermore, regardless of whether it is an inorganic compound or an organic compound, the above various positive electrodes
You may mix and use an active material.

A positive electrode plate is prepared by mixing the above positive electrode active material, a conductive agent, and a binder to prepare a positive electrode mixture, and applying this positive electrode mixture onto a positive electrode current collector made of a metal foil. Can be manufactured.

The type of conductive agent is not particularly limited, and may be a metal or a nonmetal. As a metal conductive agent,
Examples thereof include materials composed of metal elements such as Cu and Ni. Examples of the non-metal conductive agent include carbon materials such as graphite, carbon black, acetylene black and Ketjen black.

The type of binder is not particularly limited as long as it is a material that is stable with respect to the solvent and electrolytic solution used during electrode production. Specifically, polyethylene, polypropylene,
Polyethylene terephthalate, aromatic polyamide, cellulose, styrene-butadiene rubber, isoprene rubber,
Butadiene rubber, ethylene-propylene rubber, styrene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-ethylene-butadiene-styrene block copolymer and hydrogenated product thereof, styrene-isoprene-styrene block copolymer and The hydrogenated product, syndiotactic 1,2-polybutadiene, ethylene-vinyl acetate copolymer, propylene-α-olefin (C2-12) copolymer, polyvinylidene fluoride, polytetrafluoroethylene, polytetrafluoro An ethylene-ethylene copolymer or the like can be used.

As the binder, a polymer composition having an alkali metal ion conductivity such as lithium ion can also be used. Examples of the polymer having such ion conductivity include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, cross-linked polymer compounds of polyether, polyepichlorohydrin,
Polyphosphazene, polysiloxane, polyvinylpyrrolidone, polyvinylidene carbonate, a system in which a lithium salt or an alkali metal salt mainly composed of lithium is combined with a polymer compound such as polyacrylonitrile, or propylene carbonate, ethylene carbonate,
A system containing an organic compound having a high dielectric constant such as γ-butyrolactone can be used. These materials may be used in combination.

The positive electrode current collector includes, for example, Al, Ta, N
Examples thereof include b, Ti, Hf, Zr, Zn, W, Bi, and alloys containing these metals. These metals form a passivation film on the surface by anodic oxidation in the electrolytic solution, and therefore effectively prevent oxidative decomposition of the non-aqueous electrolyte in the liquid contact part between the positive electrode current collector and the electrolytic solution. You can As a result, the cycle characteristics of the non-aqueous secondary battery can be effectively improved. Of the above metals, A
1, Ti, Ta and alloys containing these metals can be preferably used. In particular, Al and its alloys have a low density, so that the mass of the positive electrode current collector can be reduced as compared with the case of using other metals. Therefore, the energy density of the battery can be improved, which is particularly preferable.

In the present invention, when the positive electrode mixture obtained as described above is applied to the positive electrode current collector, general coating methods such as reverse roll method, direct roll method, blade method, knife method and dip method are used. Although it can be carried out by a method, it is preferable to carry out by a die nozzle method because it is easy to mechanically control the coating amount of the positive electrode mixture. When a solvent is used, the positive electrode plate can be prepared by drying and removing the solvent.

When connecting the lead to the positive electrode plate obtained as described above, it is preferable to connect by ultrasonic welding in view of the smoothness of the connecting portion and the stability of impedance.
In this case, the lead needs to be connected to the non-coated part where the mixture is not applied, and when forming this non-coated part, from the viewpoint of coating accuracy, it is not stripped by a spatula or the like, but from the die nozzle. It is preferable to employ intermittent coating in which the positive electrode mixture is applied onto the current collector while mechanically controlling the amount of the positive electrode mixture to be discharged to form a coated portion and a non-coated portion.

As the negative electrode active material, lithium metal, lithium such as lithium-aluminum alloy, lithium-lead alloy, lithium-tin alloy, lithium-zinc alloy, lithium-cadmium alloy, etc. which can absorb and release lithium. Alloys, lithium nitride such as Li ₅ (Li ₃ N), carbon materials such as graphite, coke, and organic fired bodies, LiFe
₂ O ₃ , WO ₂ , MoO ₂ , SnO ₂ , SnO, TiO
₂ , transition metal oxides such as NbO ₃ can be used. Only one kind of these negative electrode active materials may be selected and used, or two or more kinds thereof may be used in combination.

The material of the negative electrode current collector is preferably a metal such as copper, nickel or stainless steel. Among them, it is more preferable to use a copper foil because it is easily processed into a thin film and is inexpensive.

The manufacturing method of the negative electrode plate is not particularly limited, and the negative electrode plate can be manufactured by the same method as the above-mentioned manufacturing method of the positive electrode.

By providing the active material mixture coating portion and the non-coating portion when manufacturing the positive electrode plate and the negative electrode plate as in the above method, the flexibility of the electrode plate in the non-coating portion can be secured. Therefore, it is possible to prevent the active material mixture from peeling off or dropping off at a portion where the electrode plate is largely deformed, such as the inner peripheral portion of the winding type electrode plate or the folded portion of the stack type electrode plate.

Examples of the non-aqueous solvent for the non-aqueous electrolytic solution include:
Ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, γ-butyrolactone, γ-valerolactone, methyl acetate, methyl propionate, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, dimethoxyethane, dimethoxymethane. , Ethylene methyl phosphate, ethyl ethylene phosphate, trimethyl phosphate, triethyl phosphate and the like can be used. Only one kind of these organic solvents may be selected and used, or two or more kinds thereof may be used in combination.

The solute of the non-aqueous electrolyte is LiCl
O_Four, LiPF₆, LiBF_FourInorganic lithium salts such as
LiCF_ThreeSO_Three, LiN (CF_ThreeSO_Two)_Two, Li
N (CF _ThreeCF_TwoSO_Two )_Two, LiN (CF_ThreeSO
_Two )_TwoAnd LiC (CF_ThreeSO_Two)_ThreeFluorine containing
Examples thereof include organic lithium salts. These solutes
, You may select and use only one type, or two or more types.
The above may be used in combination.

As the electrolyte, a solid or gel electrolyte can be used in addition to the above electrolyte solution. Examples of such an electrolyte include an inorganic solid electrolyte, polyethylene oxide, polypropylene oxide, or a derivative thereof.

As the separator, an insulating polyethylene microporous film, polypropylene microporous film, polyethylene nonwoven fabric, polypropylene nonwoven fabric, or the like impregnated with an electrolytic solution can be used. In addition, a polymer solid electrolyte or a gel electrolyte in which a polymer solid electrolyte contains an electrolytic solution can also be used. Further, an insulating microporous film and a polymer solid electrolyte may be used in combination. When the porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolytic solution contained in the polymer may be different from the electrolytic solution contained in the pores.

The present invention will be described in detail below based on examples. The present invention is not limited to the following examples.

<Examples 1 to 6 and Comparative Examples 1 and 2
> 91 parts by weight of LiCoO _2, 3 parts by weight of acetylene black as a conductive agent, and 6 parts by weight of polyvinylidene fluoride as a binder are mixed, and N-methyl-2-pyrrolidone is appropriately added to prepare a paste. Then, this was applied to both surfaces of the positive electrode current collector 10 made of aluminum having a thickness of 20 μm by a die method while controlling the discharge amount so that the coating starting end portion 13 was locally raised as shown in FIG. A coated part 11 and a non-coated part 12 were provided, dried, and then compression molded by a roll press. Through the above steps, as shown in FIG. 1, a coating portion 11 and a non-coating portion 12 having a predetermined thickness are provided,
In the positive electrode mixture, a positive electrode plate was obtained in which the ratio of the density of the coating starting end portion 13 to the density of other portions was the value shown in Table 1. Then, the lead 4 made of aluminum was ultrasonically welded to the non-coated portion 12.

92 parts by weight of graphite and 8 parts by weight of polyvinylidene fluoride as a binder were mixed and N-methyl-2-pyrrolidone was appropriately added to prepare a paste, which was made of copper having a thickness of 14 μm. As shown in FIG. 2, the negative electrode current collector 10 is coated with a die method to adjust the discharge amount so that the coating starting end portion 13 locally rises, and the coating portion 11 and the non-coating portion 12 are applied. It was provided, dried, and then compression molded by a roll press. Through the above steps, as shown in FIG. 1, a coating portion 11 and a non-coating portion 12 having a predetermined thickness are provided,
A negative electrode plate was obtained in which the ratio of the density of the coating starting end portion 13 to the density of other portions of the negative electrode mixture layer was the value shown in Table 1. Then, the copper lead 5 was ultrasonically welded to the non-coated portion 12.

As the separator, a microporous polyethylene film having a thickness of 25 μm was used.

The positive electrode plate, the separator, and the negative electrode plate were laminated in this order, and this was wound in an elliptical spiral shape around a rectangular winding core made of polyethylene to obtain a power generating element 3. At this time, the winding center axis of the power generation element 3 was made parallel to the long side of the winding core. The power generation element 3 thus obtained was housed in the battery exterior body 2, and the electrolytic solution was injected. At this time, the winding center axis of the power generation element 3 was set to be perpendicular to the opening surface of the battery exterior body 2.

As the non-aqueous electrolyte, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 3: 7, and LiPF ₆ was added to this solution at 1.0 mo.
1 / l dissolved product was used.

Subsequently, after precharging at a constant current of 200 mA for 30 minutes, the lead terminals were fixed and the battery outer casing 2
The opening was sealed by heat welding while reducing the pressure. Thus, the non-aqueous secondary battery 1 of Example 1 was obtained.

<Example 7> When the positive electrode mixture and the negative electrode mixture are coated on the current collector, the amount of the active material mixture discharged from the die is kept constant and the coating starting end portion 13 is coated. A non-aqueous secondary battery was produced in the same manner as in Example 1 except that the active material mixture density of the coating starting end portion 13 was increased by decreasing the moving speed of the current collector only.

<Comparative Example 3> When the positive electrode mixture and the negative electrode mixture were applied onto the current collector, the amount of the active material mixture discharged from the die and the moving speed of the current collector were made uniform so as to be uniform. A non-aqueous secondary battery was produced in the same manner as in Example 1 except that the electrode plate was compressed at a pressure 20% higher than that in Example 1 after applying the active material mixture.

<Measurement> (Measurement of Packing Density) The density of the active material of the electrode plate manufactured as described above was measured as follows. First,
The metal foil used as the current collector was punched into a disk having a diameter of 20 mmφ, and the weight thereof was measured in advance. Next, a disc with a diameter of 20 mmφ was punched out from the electrode plate, and its weight and thickness were measured. The weight of the active material layer was calculated by subtracting the previously measured weight of the metal foil disk from the weight of the electrode disk thus obtained. Further, the thickness of the active material layer was calculated by subtracting the thickness of the metal foil from the thickness of the electrode disc. The density of the active material was calculated by dividing the weight of the active material by the volume of the active material layer calculated from the thickness of the active material layer. The densities of the coating start end and other portions were measured by the above method, and the density of the coating start end was calculated when the density of the portion other than the coating start end was 100. These values are summarized in Table 1 as the density ratio of the positive electrode mixture layer starting end portion for the positive electrode and as the negative electrode mixture layer starting end portion of the negative electrode.

(Detachment of electrode mixture layer and breakage of electrode plate)
For each of the positive electrode plate and the negative electrode plate produced by the above method, the presence or absence of the mixture layer being dropped when attaching the leads by ultrasonic welding was observed, and the number of electrode plates from which the electrode mixture layer was dropped was observed. The percentages of the 10 tested electrode plates were calculated and used as the falling rate of the positive electrode mixture layer during lead welding and the falling rate of the negative electrode mixture layer during coating. In addition, for each of the elliptical spirally wound power generation elements of the non-aqueous secondary battery produced by the above method, 10 cells each, and for the positive electrode plate, check whether or not the electrode plate was broken during winding, On the other hand, regarding the negative electrode plate, the presence or absence of the electrode mixture layer falling off from the electrode plate during winding was checked, the percentage for 10 cells was calculated, and the breaking rate of the positive electrode plate during winding and the negative electrode during winding were measured. The dropout rate of the mixture layer was used. The results are summarized in Table 1.

(Battery capacity) The non-aqueous secondary battery produced by the above method was charged at a constant current of 500 mA to 4.2 V and then charged at a constant voltage of 4.2 V for 3 hours from the start of charging. This battery was discharged at a constant current of 500 mA to 2.75 V and the battery capacity was measured. The results are summarized in Table 1.

<Results> First, in Table 1, by comparing Examples 1 to 6 with Comparative Examples 1 and 2, the density ratio of the leading end portion of the positive electrode mixture layer and the positive electrode mixture at the time of lead welding The relationship between the layer loss and the breakage of the positive electrode plate during electrode winding is examined.

[0048]

[Table 1]

As the density ratio of the positive electrode mixture layer increased, the falling rate of the positive electrode mixture layer decreased. This is because the adhesion ratio between the coating start end and the current collector was improved due to the increase in the density ratio of the positive electrode mixture layer start end, and the adhesion between the positive electrode active materials at the coating start end was improved. It is considered that the falling of the work start edge was suppressed.

In Examples 1 to 6 in which the density ratio of the leading end of the positive electrode mixture layer was 102 or more, the falling rate of the positive electrode mixture layer was 20%.
In contrast to the following, Comparative Example 1 of less than 102 is 5
It was 0%. It is considered that when the density ratio of the positive electrode material mixture layer is less than 102, the adhesiveness between the coating start end and the current collector and the adhesiveness between the positive electrode active materials at the coating start end are insufficient. . Therefore, the density ratio of the positive electrode mixture layer is preferably 102 or more in order to prevent the positive electrode mixture layer from falling off. Furthermore, when the ratio is 110 or more, the falling rate of the positive electrode mixture layer is 10% or less. Therefore, the density ratio of the positive electrode mixture layer is particularly preferably 110 or more.

As the density ratio of the positive electrode mixture layer increases,
The fracture rate of the positive electrode plate increased. This is because the hardness at the coating start end increases due to the increase in the density ratio of the positive electrode mixture layer, and as a result,
It is considered that the flexibility at the coating start end decreased and the stress was concentrated at the coating start end.

In Examples 1 to 6 in which the density ratio of the positive electrode material mixture layer was 150 or less, the breakage rate of the positive electrode plate was 10% or less, whereas in Comparative Example 2 in which it exceeded 150, it was 40%. It is considered that when the density ratio of the positive electrode mixture exceeds 150, the hardness of the positive electrode mixture increases, so that the flexibility of the coating start end portion remarkably decreases. Therefore, in order to prevent breakage of the positive electrode plate, the density ratio of the positive electrode mixture layer is preferably 150 or less. Further, in the case of 140 or less, the breaking ratio of the positive electrode plate is 0%, so that the density ratio of the positive electrode mixture layer is particularly preferably 140 or less.

From the above, in order to prevent the coating start end from falling off when the lead is ultrasonically welded onto the current collector and the positive electrode plate from being broken when the positive electrode plate is wound, the density ratio of the positive electrode mixture layer is Is preferably 102 or more and 150 or less, and 110
Above 140 is particularly preferable.

Next, in Table 1, for Examples 1 to 6 and Comparative Examples 1 and 2, the density ratio of the starting end portion of the negative electrode mixture layer,
Comparing the dropout rate of the negative electrode mixture layer during lead welding and winding, it was found that the negative electrode had the same tendency as the positive electrode. Therefore, in order to prevent the coating start end from falling off when the lead is ultrasonically welded onto the current collector and the negative electrode mixture from falling off when the negative electrode plate is wound, the density ratio of the negative electrode mixture layer is 102 or more. It is preferably 150 or less, and particularly preferably 110 or more and 140 or less.

When the positive electrode mixture is applied on the current collector, the positive electrode mixture is uniformly applied by adjusting the amount of the positive electrode mixture discharged from the die and the moving speed of the current collector. In Comparative Example 3 in which the electrode plate was compression-processed at a pressure 20% higher than that in Example 1, the positive electrode mixture layer dropout rate was 0%, which was equivalent to that in Example 3, but the positive electrode plate fracture rate was 50%. It was remarkably high. It is considered that this is because the entire positive electrode was compressed at a high pressure and thus the flexibility of the entire active material layer was reduced.
Therefore, in order to prevent breakage of the positive electrode plate, it was found that it is preferable not to compress the entire positive electrode plate at a high pressure, but to make the coating start end portion, which easily falls off, higher in density than other portions. . Since similar results were obtained with the negative electrode as well, in order to prevent the negative electrode material mixture layer from falling off during winding, it is preferable to make the density of the coating start end part, which is easy to drop off, higher than the other parts. I understood it.

In the first to sixth embodiments, the battery capacity is 5
While it is over 00 mAh, in Comparative Example 3 420 mAh
Was extremely low. It is considered that this is because the electrode plate was compressed at a high pressure, and thus the infiltration property of the non-aqueous electrolytic solution was lowered. Therefore, in order to obtain a non-aqueous secondary battery with a high battery capacity, it is necessary not to compress the entire electrode plate at a high pressure, but to make only the density of the coating start end higher than other parts. I found out.

When the active material mixture is applied to the current collector, the amount of the active material mixture discharged from the die is kept constant, and the moving speed of the current collector is slowed at the coating start end so that the coating start end Example 7 in which the density of the active material mixture in each part was increased, the removal rate of the positive electrode and negative electrode mixture layers during lead welding, the breakage rate of the positive electrode plate during winding and the negative electrode mixture layer removal rate, and the battery capacity The performance of the active material mixture was about the same as that of Example 3 in which the active material mixture was locally raised at the coating start end. However, in Example 7, since the moving speed of the current collector was slowed at the coating start portion, Example 3 was adopted in terms of productivity.
Inferior to. Therefore, in order to improve the productivity of the non-aqueous secondary battery, it was found that it is preferable to apply the active material mixture so that the active material mixture locally bulges at the coating start end and then compress it.

As described above, the active material mixture layer is formed on the foil-shaped current collector, and the active material mixture layer is formed so as to be arranged intermittently with the non-coated portion sandwiched therebetween. In the electrode plate of the secondary battery, the density of the end portion of the active material mixture layer adjacent to the non-coated portion is set to be 102 or more and 150 or less when the density of the other portion is 100, thereby producing It is possible to obtain an electrode plate having excellent properties and a high battery capacity. Further, the electrode plate, the active material mixture is intermittently applied to the current collector with the non-coated portion interposed therebetween, and the active material mixture is applied at a coating start end portion following the non-coated portion. The electrode plate having excellent productivity and a high battery capacity can be efficiently obtained by applying the coating so that it locally swells and then compressing the entire coating part flat.

<Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition to the above, various modifications can be made without departing from the scope of the invention.

Although the bag-shaped non-aqueous secondary battery 1 has been described in the above embodiment, the battery structure is not particularly limited, and needless to say, it may be a cylindrical, prismatic, lithium polymer battery or the like.

[0061]

According to the present invention, an electrode plate having excellent productivity and high battery capacity can be obtained. In addition, the electrode plate can be efficiently manufactured without requiring extra steps.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an electrode according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of an electrode before compression processing according to an embodiment of the present invention.

FIG. 3 is a perspective view of a bag-shaped non-aqueous secondary battery according to an embodiment of the present invention.

FIG. 4 is a perspective view of a power generation element and a battery exterior body.

[Explanation of symbols]

1 ... Non-aqueous secondary battery 2 ... Battery exterior body 3 ... Power generation element 4 ... Positive electrode lead terminal 5 ... Negative electrode lead terminal 6 ... Back sealing part 7 ... Bottom sealing part 8 ... Sealing part 10 ... Current collector 11 ... Coating department 12 ... Non-coated part 13 ... Starting edge of coating

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Claims (2)

[Claims] 1. A non-aqueous secondary material in which an active material mixture layer is formed on a foil-shaped current collector, and the active material mixture layer is formed so as to be arranged intermittently with a non-coated portion interposed therebetween. In the electrode plate of the battery, 10 when the density of the end portion of the active material mixture layer adjacent to the non-coated portion is 100, and the density of the other portion is 100.
An electrode plate for a non-aqueous secondary battery, which is 2 or more and 150 or less. 2. A non-aqueous secondary material in which an active material mixture layer is formed on a foil-shaped current collector, and the active material mixture layer is formed so as to be arranged intermittently with a non-coated portion interposed therebetween. A method of manufacturing an electrode plate of a battery, wherein the active material mixture is intermittently applied to the current collector with the non-coated portion interposed therebetween, and at the coating start end portion following the non-coated portion. After coating the active material mixture so as to locally swell, by compressing the entire coating portion flat, the density after compression of the active material mixture layer at the coating start end, other, The method for producing an electrode plate for a non-aqueous secondary battery, wherein the density of the portion is 100 or more and 150 or less when the density is 100.