JPWO2015053177A1 - Nonaqueous electrolyte battery and manufacturing method thereof - Google Patents

Abstract

Provided are a nonaqueous electrolyte battery capable of realizing low resistance while suppressing occurrence of short circuit failure, and a method for manufacturing the same. The positive electrode 1, the negative electrode 2, an ion conductive non-aqueous electrolyte, and a material formed on at least one surface of the positive electrode and the negative electrode and including insulating inorganic fine particles and a binder, between the positive electrode and the negative electrode In the non-aqueous electrolyte battery including the porous insulating layer 3 disposed so as to be interposed between the positive electrode and the negative electrode, the porous insulating layer (ceramic separator) is composed of a plurality of layers 13 and 23. And out of the plurality of layers constituting the porous insulating layer 3, the outermost layer opposite to the bonding layer 13 including the bonding surface in contact with the surface of the positive electrode or the negative electrode on which the porous insulating layer is formed. The PVC of the surface layer 23 located and including the outer surface of the porous insulating layer is made lower than the PVC of the other layers constituting the porous insulating layer.

Description

  The present invention relates to a battery, and more specifically, a nonaqueous electrolyte battery including a positive electrode, a negative electrode, an ion conductive nonaqueous electrolyte, and a porous insulating layer (ceramic separator) provided with the positive electrode and the negative electrode, and the same It relates to a manufacturing method.

  For example, in a non-aqueous electrolyte battery such as a lithium ion secondary battery, a separator (polyolefin separator) such as a polyolefin-based stretched film has been widely used as a separator disposed between a positive electrode and a negative electrode.

  Further, a non-aqueous electrolyte battery using a separator (a porous insulating layer or a ceramic separator) in which inorganic fine particles are dispersed in an organic polymer material (binder) has been proposed instead of such a polyolefin-based separator (for example, , See Patent Document 1).

  Unlike the polyolefin-based separator, the ceramic separator as described above has a characteristic that it is not deformed and contracted even in a high temperature environment. Therefore, non-aqueous electrolyte batteries using ceramic separators do not shrink even when exposed to unintended high temperatures, so there is no short circuit between the positive and negative electrodes, heat generation, smoke generation, or ignition, resulting in high safety. Will be secured. In the case of a non-aqueous electrolyte battery using a ceramic separator, this feature provides safety that does not ignite even in a nail clip test.

  However, the ceramic separator has a problem in strength. For example, as shown in FIG. 6, the ceramic separator 103 is configured to maintain electronic insulation only by being interposed between the positive electrode 101 and the negative electrode 102. However, in order to obtain a battery that does not cause the problem of short-circuit failure by securing electronic insulation only with a ceramic separator, the defect is caused by increasing the strength of the ceramic separator. It is necessary not to let it.

  For that purpose, it is effective to increase the ratio of the binder that plays a role of holding inorganic fine particles, and it is effective to reduce the pigment volume concentration (hereinafter referred to as PVC) (Pigment Volume Concentration) of the ceramic separator. .

On the other hand, since the resistance increases as the PVC decreases, the suppression of short circuit and the suppression of resistance are in a trade-off relationship.
Therefore, it is currently difficult to make the resistance lower than that of the conventional polyolefin-based separator while suppressing the occurrence of short circuit failure.

Japanese Patent No. 3253632

  The present invention solves the above problems and is a non-aqueous electrolyte battery including a porous insulating layer (ceramic palator) in which inorganic fine particles are dispersed in an organic polymer material, and suppresses the occurrence of short-circuit defects. However, it aims at providing the nonaqueous electrolyte battery which can implement | achieve low resistance, and its manufacturing method.

In order to solve the above problems, the nonaqueous electrolyte battery of the present invention is
A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A non-aqueous electrolyte battery comprising:
PVC on the outer surface of the porous insulating layer and the vicinity thereof on the opposite side of the bonding surface in contact with the surface of the positive electrode or the negative electrode of the porous insulating layer constitutes the porous insulating layer. It is characterized by being lower than the PVC of the region.

  In the nonaqueous electrolyte battery of the present invention, “the PVC in the outer surface of the porous insulating layer and the vicinity thereof is lower than the PVC in the other regions constituting the porous insulating layer” The state where PVC is continuously lowered from the bonding surface side to the surface side, the state where the PVC is lowered stepwise, or the porous insulating layer is formed of a plurality of layers, and is the most surface This is a concept including the case where the PVC of the side layer is lower than the PVC of the other layer (except when the PVC of the outermost layer is 0%).

In order to solve the above problems, another non-aqueous electrolyte battery of the present invention includes:
A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A non-aqueous electrolyte battery comprising:
The porous insulating layer comprises a plurality of layers, and
Among the plurality of layers constituting the porous insulating layer, the PVC of the surface layer located on the outermost side of the porous insulating layer on the side opposite to the bonding layer in contact with the surface of the positive electrode or the negative electrode, It is characterized by being lower than the PVC of the other layers constituting the porous insulating layer.

  In the nonaqueous electrolyte battery of the present invention, the PVC in a region having a depth from the outer surface of the porous insulating layer or the outer surface of the surface layer to 10% of the total film thickness of the porous insulating layer. Is preferably 70% or less and 40% or more.

  With the above configuration, it is possible to realize low resistance while more reliably suppressing the occurrence of short circuit failure. However, when the outer surface of the porous insulating layer or the PVC of the surface layer is less than 40%, the increase in resistance is increased and a sufficient effect cannot be obtained.

  Further, a region having a depth of up to 50% of the total film thickness of the porous insulating layer from the bonding surface of the porous insulating layer or the bonding surface of the bonding layer in contact with the surface of the positive electrode or the negative electrode of the bonding layer The average value of PVC is preferably 70% or more and less than 95%.

  By adopting the above configuration, it is possible to realize low resistance while more reliably suppressing the occurrence of short circuit failure. However, when the PVC on the joint surface side is 95% or more, defects such as cracking occur even with a weak force, and it is not preferable because the short circuit cannot be sufficiently suppressed.

  Moreover, in the nonaqueous electrolyte battery of this invention, it is preferable that PVC of the said surface layer which comprises the said porous insulating layer is 70% or less and 40% or more.

  By adopting the above configuration, it is possible to realize low resistance while more reliably suppressing the occurrence of short circuit failure. However, when the PVC of the surface layer constituting the porous insulating layer is less than 40%, the increase in resistance becomes large and a sufficient effect cannot be obtained.

  Moreover, it is preferable that PVC of the said joining layer which comprises the said porous insulating layer is 70% or more and 90% or less.

  With the above configuration, it is possible to achieve low resistance while reliably suppressing the occurrence of short circuit failure, and the present invention can be more effectively realized. However, when the PVC of the bonding layer constituting the porous insulating layer is 95% or more, defects such as cracking occur even with a weak force, and short circuit cannot be sufficiently suppressed.

In addition, the method for producing the nonaqueous electrolyte battery of the present invention includes:
A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A method for producing a nonaqueous electrolyte battery comprising a layer,
The step of forming the porous insulating layer includes:
A first step of forming a first porous insulating layer constituting a porous insulating layer on at least one of the positive electrode and the negative electrode;
And a second step of forming a second porous insulating layer having a PVC lower than that of the first porous insulating layer on the first porous insulating layer.

As described above, the nonaqueous electrolyte battery of the present invention is formed on the surface of at least one of the positive electrode, the negative electrode, the ion conductive nonaqueous electrolyte, the positive electrode and the negative electrode, and has insulating inorganic fine particles and a binder. In a non-aqueous electrolyte battery comprising a porous insulating layer (ceramic separator) disposed between a positive electrode and a negative electrode, the surface of the positive electrode or the negative electrode of the porous insulating layer PVC on the outer surface of the porous insulating layer on the side opposite to the bonding surface in contact with the outer peripheral surface of the porous insulating layer and the region in the vicinity thereof is lower than the PVC in other regions constituting the porous insulating layer. A short circuit is suppressed by the low outer surface and its vicinity region, and low resistance is realized by a region where PVC is higher than the outer surface and its vicinity region other than the outer surface and its vicinity region.
As a result, it is possible to provide a non-aqueous electrolyte battery that can simultaneously realize suppression of short circuit and reduction of resistance.

In addition, as described above, another non-aqueous electrolyte battery of the present invention is formed on at least one surface of a positive electrode, a negative electrode, an ion conductive non-aqueous electrolyte, and a positive electrode and a negative electrode. In a non-aqueous electrolyte battery comprising a porous insulating layer (ceramic separator) made of a material including a binder and disposed between a positive electrode and a negative electrode, the porous insulating layer includes a plurality of porous insulating layers. PVC of a surface layer located on the outermost side of the porous insulating layer on the side opposite to the bonding layer in contact with the surface of the positive electrode or the negative electrode, out of a plurality of layers constituting the porous insulating layer However, since it is made lower than the PVC of the other layers constituting the porous insulating layer, the short circuit is suppressed by the surface layer having a low PVC, and the PVC other than the surface layer is smaller than the region near the surface. High resistance due to high layer It is.
As a result, it is possible to provide a non-aqueous electrolyte battery that can simultaneously realize suppression of short circuit and reduction of resistance.

  In addition, the method for producing a nonaqueous electrolyte battery of the present invention includes a positive electrode, a negative electrode, an ion conductive nonaqueous electrolyte, and at least one surface of the positive electrode and the negative electrode, and insulating inorganic fine particles and a binder. In manufacturing a non-aqueous electrolyte battery comprising a porous insulating layer comprising a plurality of layers disposed so as to be interposed between a positive electrode and a negative electrode, a plurality of layers are laminated. A first step of forming a first porous insulating layer constituting the porous insulating layer on at least one of the positive electrode and the negative electrode, and on the first porous insulating layer And a second step of forming a second porous insulating layer having a PVC lower than that of the first porous insulating layer, thereby realizing low resistance while suppressing occurrence of short circuit failure. To obtain a non-aqueous electrolyte battery that can Kill.

  In the method for producing a nonaqueous electrolyte battery of the present invention, the first porous insulating layer may have a single layer structure or a multi-layer structure.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the principal part structure (structure of a battery element) of the lithium ion secondary battery cell (nonaqueous electrolyte battery) concerning one Example (Example 1) of this invention, (a) is a positive electrode, The figure which isolate | separates and shows a negative electrode, (b) is a figure which shows the state in which the positive electrode and the negative electrode were joined through the porous insulating layer. It is a figure which shows the other example (modified example 1) of the battery element which comprises the lithium ion secondary battery cell (nonaqueous electrolyte battery) of this invention. It is a figure which shows the further another example (modification 2) of the battery element which comprises the lithium ion secondary battery cell (nonaqueous electrolyte battery) of this invention. It is a figure which shows typically the principal part structure of the lithium ion secondary battery cell concerning other Example (Example 2) of this invention, (a) is a figure which isolate | separates and shows a positive electrode and a negative electrode, (b) FIG. 3 is a view showing a state in which a positive electrode and a negative electrode are joined via a porous insulating layer. It is a figure which shows typically the principal part structure of the lithium ion secondary battery cell concerning another Example (Example 3) of this invention, (a) is a figure which isolate | separates and shows a positive electrode and a negative electrode, (b) ) Is a diagram showing a state in which a positive electrode and a negative electrode are joined via a porous insulating layer. It is a figure which shows the principal part structure of the conventional nonaqueous electrolyte battery.

  1 (a) and 1 (b) are diagrams showing a main part configuration (configuration of a battery element) of a nonaqueous electrolyte battery according to an embodiment (Embodiment 1) of the present invention. The figure which isolate | separates and shows a negative electrode, (b) is a figure which shows the state with which the positive electrode and the negative electrode were joined through the porous insulating layer.

A battery element 10 constituting this nonaqueous electrolyte battery is formed by applying a positive electrode 1 obtained by applying a positive electrode active material 1b on a positive electrode current collector foil 1a and a negative electrode active material 2b on a negative electrode current collector foil 2a. A negative electrode 2 and a porous insulating layer 3 formed on at least one surface of the positive electrode 1 and the negative electrode 2 (the surface of the negative electrode 2 in this embodiment) are provided.
The porous insulating layer 3 is made of a material containing insulating inorganic fine particles and a binder, and is disposed so as to be interposed between the positive electrode 1 and the negative electrode 2.

  The porous insulating layer 3 includes a first porous insulating layer 13 made of a high PVC material formed on the surface of the negative electrode 2, and a first porous layer formed on the first porous insulating layer 13. A second porous insulating layer 23 having a PVC lower than that of the porous insulating layer 13 is provided.

  Incidentally, in order to reduce the resistance of the porous insulating layer (ceramic separator) 3, it is effective to increase the PVC. This is because as the PVC becomes higher, voids increase and the electrolyte solution is more easily impregnated, and the obstacles to the path of ions moving during the charge / discharge reaction decrease.

  On the other hand, the higher the PVC is, the lower the proportion of the binder (binder) that holds the inorganic fine particles, so that the inorganic fine particles are likely to drop off, and a short circuit failure is likely to occur. In addition, when the PVC becomes high, defects such as cracks and cracks are easily generated in the porous insulating layer due to external force, the underlying electrode is exposed, and the exposed part contacts the other electrode. It becomes easy to cause. Such defects in the porous insulating layer can occur during the manufacturing process, and can also occur during use as a battery. During use, a short circuit, especially when fully charged, can lead to overheating, smoke, and fire.

  As described above, there is a trade-off relationship between making the resistance low and making the short circuit difficult, and there is a limit in reducing the resistance of the ceramic separator while preventing the short circuit.

  On the other hand, in the nonaqueous electrolyte battery of the present invention, the bonding layer (first porous layer) in contact with the surface of the negative electrode 2 among the plurality of layers (two layers in this embodiment) constituting the porous insulating layer 3. PVC of the surface layer (second porous insulating layer) 23 located on the outermost side of the porous insulating layer 3 on the side opposite to the porous insulating layer) 13 is replaced with another layer (this In the embodiment, the bonding layer 13) is made lower than the PVC. That is, in the present invention, the PVC of the surface layer 23 is made the lowest among the layers constituting the porous insulating layer 3.

  As a result, a short circuit is suppressed by the surface layer 23 having a low PVC, and a low resistance is realized by the layer (junction layer) 13 having a high PVC other than the surface layer 23, so that both the low resistance and the suppression of the short circuit can be achieved. become able to.

  Specifically, a region having a depth from the outer surface of the porous insulating layer 3 (that is, the outer surface of the surface layer 23) to 10% of the total film thickness of the porous insulating layer 3 (for example, the porous insulating layer) When the total film thickness is 15 μm, it is desirable that the average value of the pigment volume concentration PVC in the region of 1.5 μm from the outer surface of the surface layer 23 is 70% or less and 40% or more.

  Moreover, in the present invention, as described above, the PVC of the surface layer 23 constituting the porous insulating layer 3 is lowered to improve the strength of the outer surface of the porous insulating layer 3, so that it is lower than the surface layer 23. In the side layer (the bonding layer 13 in this embodiment), it becomes possible to increase the PVC in order to realize a low resistance. However, when the outer surface of the porous insulating layer or the PVC of the surface layer is less than 40%, the increase in resistance is increased and a sufficient effect cannot be obtained.

  For example, the total thickness of the first porous insulating layer (bonding layer) 13 formed on the surface of the negative electrode 2 and the second porous insulating layer (surface layer) 23 formed thereon is 15 μm. When the porous insulating layer 3 is formed, the thickness of the bonding layer 13, which is a high PVC layer, is 13 μm, and the thickness of the surface layer 23, which is a low PVC layer, is 2 μm. Can be obtained.

  Further, as the thickness of the surface layer (second porous insulating layer) 23 having a low PVC is made thinner, the proportion of the bonding layer (first porous insulating layer) having a higher PVC is relatively increased. It becomes possible to raise PVC in the whole insulating layer, and to achieve lower resistance.

  The porous insulating layer used in the nonaqueous electrolyte battery of the present invention can be easily obtained by, for example, a method of applying a slurry prepared for forming a porous insulating layer on an electrode (positive electrode or negative electrode). Can do.

  In this case, for example, a porous insulating layer having a two-layer structure is prepared by applying a slurry for a porous insulating layer for a lower layer on an electrode (positive electrode or negative electrode) and drying to form a porous insulating layer (bonding layer) on the lower layer side. After forming, the slurry for forming the porous insulating layer for the surface layer is applied on the lower porous insulating layer and dried to form the porous insulating layer (surface layer) on the surface side. Can do.

  And when it manufactures with such a manufacturing method, when a coating-film defect, such as a pinhole, arises in the porous insulating layer (bonding layer) on the lower layer side, when forming the porous insulating layer of the surface layer Since the coating film defect of the bonding layer is repaired, it is possible to prevent the porous insulating layer as a whole from having a defect causing a problem. As a result, it is possible to more reliably suppress the occurrence of short circuit failure.

  1 has a two-layer structure in which a low-PVC surface layer (second porous insulating layer) 23 is formed on a high-PVC bonding layer (first porous insulating layer) 13. Although the porous insulating layer 3 is shown, in the present invention, it is not necessary to have a structure in which the bonding layer 13 having a high PVC and the surface layer 23 having a low PVC are clearly divided into layers. It is only necessary that the outer surface 3 and the vicinity thereof are made of a low PVC material.

  What is important in the present invention is to lower the PVC of the outer surface of the porous insulating layer and the vicinity thereof to prevent defects in the porous insulating layer as a whole. In the region other than the surface and the vicinity thereof, PVC is increased to reduce the resistance, and each layer does not need to be clearly divided.

  Therefore, for example, a layer having a PVC gradient (transition layer) such that the PVC gradually decreases from the one main surface side closer to the electrode toward the other main surface side (transition from high PVC to low PVC). Can be made to exist in a single layer, and in this case, the same effect can be obtained.

  Whether the structure is clearly divided or the structure in which PVC continuously changes in the layer is, for example, the porous insulating layer in forming the outermost porous insulating layer. The viscosity can be adjusted by appropriately selecting the viscosity of the slurry for formation and the porosity of the porous insulating layer serving as the base.

In addition, PVC (Pigment Volume Concentration; pigment volume concentration) is calculated | required by following formula (1).
PVC = (volume of inorganic fine particles) / (volume of inorganic fine particles + volume of organic binder) × 100 (1)
Volume of inorganic fine particles = weight of inorganic fine particles / density of inorganic fine particles Volume of organic binder = weight of organic binder / density of organic binder

  A lithium ion secondary battery cell (non-aqueous electrolyte battery) was produced by the following procedure, and the characteristics of the short circuit failure and the resistance were examined.

(Step 1) Preparation of slurry for positive electrode active material Lithium iron phosphate (Mitsui Engineering & Shipbuilding Co., Ltd .: EF014-LCC, D ₅₀ = 13.2 μm) 84 g, acetylene black 12 g (Electrochemical Industry Co., Ltd .: HS- 100), 100 g of N-methylpyrrolidone (hereinafter referred to as NMP) and 40 g of a 10 wt% NMP solution of polyvinylidene fluoride (Kureha Co., Ltd .: # 7208) are mixed together and stirred with a planetary mixer to obtain a slurry for a positive electrode active material Was made.

(Step 2) Production of slurry for negative electrode active material 85 g of graphite (Mitsubishi Chemical Corporation: GTR6, D ₅₀ = 11.0 μm), 15 g of conductive additive (manufactured by Hitachi Chemical Co., Ltd .: SMSC10-4V3), 100 g of NMP, A slurry for negative electrode active material was prepared by combining 53 g of a 10 wt% NMP solution of polyvinylidene fluoride (manufactured by Kureha Co., Ltd .: # 7305) and stirring with a planetary mixer.

(Step 3) Production of positive electrode The positive electrode active material slurry produced in step 1 was coated on a positive electrode current collector foil made of aluminum foil (manufactured by Tokai Toyo Aluminum Co., Ltd .: thickness 20 μm) with a die coater and dried. A positive electrode was produced by pressing.
The positive electrode produced in this way was cut so as to obtain a 4.5 cm square battery reaction part and a tab attachment part where the positive electrode current collector foil was exposed, and an aluminum tab was attached to the tab attachment part where the positive electrode current collector foil was exposed. Attachment and extraction electrodes were formed.

(Step 4) Production of Negative Electrode The negative electrode active material slurry produced in Step 2 was applied on a negative electrode current collector foil made of rolled copper foil (manufactured by Nippon Foil Co., Ltd .: thickness 10 μm) with a die coater, The negative electrode was produced by pressing after drying.

(Step 5) Formation of high PVC porous insulating layer (bonding layer) In a 500 mL pot, spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle size (D ₅₀ ) 0.3 μm) 100 g, solvent (NMP) 80 g Was introduced. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 39.8 g of a binder solution (20 wt% NMP solution) of PVDF-HFP (manufactured by Kynar: # 2850) was added and mixed for 4 hours at 150 rpm using a rolling ball mill, and 85% PVC slurry for porous insulation layer (Slurry for high PVC porous insulating layer) was prepared.
And after apply | coating the produced slurry for high PVC porous insulation layers on the negative electrode produced at the process 4 with the bar coater, it was made to dry and the 13-micrometer-thick high PVC porous insulation layer (joining layer) was formed. This high PVC porous insulating layer (bonding layer) corresponds to the first porous insulating layer in the present invention.

(Step 6) Formation of low PVC porous insulating layer (surface layer) In a 500 mL pot, spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle diameter (D ₅₀ ) 0.3 μm) 100 g and NMP 80 g as a solvent I put it in. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 151 g of a binder solution (20 wt% NMP solution) of PVDF-HFP (manufactured by Kynar: # 2850) is added and mixed for 4 hours at 150 rpm using a rolling ball mill, and a slurry for porous insulation layer of 60% PVC (low PVC) A slurry for a porous insulating layer) was prepared.
Then, the prepared slurry for low PVC porous insulating layer was coated on the high PVC porous insulating layer (bonding layer) formed on the negative electrode in Step 5 with a bar coater, and then dried to a film thickness of 2 μm. A low PVC porous insulating layer (surface layer) was formed. This low PVC porous insulating layer (surface layer) corresponds to the second porous insulating layer in the present invention.

(Step 7) Cut of negative electrode on which porous insulating layer is formed A porous insulating layer comprising a high PVC porous insulating layer (bonding layer) having a thickness of 13 μm and a low PVC porous insulating layer (surface layer) having a thickness of 2 μm The negative electrode obtained in step 6 is cut so as to obtain a battery reaction portion of 4.8 cm square and a tab attachment portion where the negative electrode current collector foil is exposed, and further, the tab attachment portion where the negative electrode current collector foil is exposed A nickel tab was attached to the lead electrode to form a lead electrode.

(Step 8) Production of Lithium Ion Secondary Battery Cell One positive electrode produced in Step 3 is opposed to a negative electrode having a two-layered porous insulating layer composed of a bonding layer and a surface layer produced in Step 7. 1 (a)), the positive electrode 1 and the negative electrode 2 are joined to each other through the porous insulating layer 3 having a two-layer structure, as shown in FIG. 1 (b). (Ceramic separator) A battery element 10 having a structure joined via 3 was obtained.
Then, the formed battery element 10 was sandwiched between two laminate sheets, and three sides were thermocompression bonded with an impulse sealer to produce a laminate package with one side opened.
Next, an electrolytic solution (ion conductive nonaqueous electrolyte) was injected from the opening of the laminate package. As the electrolytic solution, an electrolytic solution in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of 3: 7 so as to be 1 M was used.
Then, the lithium ion secondary battery cell (nonaqueous electrolyte battery) was obtained by vacuum-sealing the opening part of a laminate package.

<Confirmation of short circuit failure>
In order to evaluate the characteristics of the lithium ion secondary battery cell (nonaqueous electrolyte battery) produced as described above, the presence or absence of occurrence of short-circuit failure was examined for 10 lithium ion secondary battery cells (samples). The presence or absence of occurrence of short-circuit failure was examined by the method described below.

First, the lithium ion secondary battery cell was charged to 3.5 V and left at room temperature for 1 week.
Then, the voltage of the lithium ion secondary battery cell is measured, and a sample in which a short circuit failure does not occur in a lithium ion secondary battery cell having a voltage of 3.4 V or higher (good product), a lithium ion secondary of less than 3.4 V The battery cell was a sample (defective product) in which a short circuit failure occurred. The results (occurrence rate of short circuit failure) are shown in Table 1.

For comparison, lithium ion secondary battery cells (samples of Comparative Examples 1 and 2) were prepared in the same manner as in the above example except that the porous insulating layer was a single layer. In addition, as a sample of a comparative example, the thing of 85% of PVC and the thing of 70% were produced as a single layer porous insulating layer. Note that the thickness of each porous insulating layer was 15 μm.
And also about the lithium ion secondary battery cell of the comparative examples 1 and 2, it evaluated by the method similar to the case of the above-mentioned Example. The results are also shown in Table 1.

<Measurement of resistance>
In order to evaluate the resistance of each lithium ion secondary battery cell, the lithium ion secondary battery cell (sample) as an example produced as described above, and the lithium ion secondary battery cell (sample) of Comparative Examples 1 and 2 ), The input DCR and the output DCR were measured. The DCR was measured using the charge / discharge profile shown in Table 2.

  Table 3 shows the results of measurement of input DCR and output DCR performed on the sample of the example and the samples of comparative examples 1 and 2. In addition, the values of the input DCR and the output DCR shown in Table 3 are average values of values obtained by measuring lithium ion secondary battery cells (samples) that are not short-circuited.

  As shown in Table 1, in the case of the lithium ion secondary battery cells (samples) of Comparative Examples 1 and 2 using a porous insulating layer having a single layer structure as a ceramic separator, 85% of PVC was used as in Comparative Example 1. It has been confirmed that short circuit defects occur due to falling off or cracking of inorganic fine particles.

  Further, even in a sample in which the PVC of the porous insulating layer having a single layer structure is designed to be low so that the short circuit can be suppressed (sample with 70% PVC), the occurrence of short circuit failure cannot be eliminated.

On the other hand, in the case of the sample of the example in which the porous insulating layer has a two-layer structure and the surface layer of low PVC is located on the surface side, it was confirmed that no short circuit failure occurred.
This is due to the effect of short circuit suppression by improving the strength of the outer surface of the porous insulating layer and the effect of repairing defects in the porous insulating layer (bonding layer) on the lower layer side by the two-layer coating. It is thought that it became possible to prevent.

  In addition, as shown in Table 3, in the case of the sample of the example in which the porous insulating layer has a two-layer structure and the surface layer of low PVC is formed on the surface, the resistance due to the formation of the surface layer of low PVC on the surface is reduced. It was confirmed that the increase rate, that is, the increase rate of the resistance of the sample of the example with respect to the resistance of the sample of Comparative Example 1 was less than 3%, which was a slight increase rate.

  Moreover, the sample of the comparative example 2 (PVC70%) which designed the PVC of the porous insulation layer of the single layer structure low in order to suppress the short circuit failure, and the porous insulation layer have a two-layer structure, and the surface of the low PVC on the surface When the resistance of the sample of the example in which the layer was formed was compared, it was confirmed that the resistance of the sample of the example was reduced by about 30%.

  From this result, in the case of the sample of the example in which the porous insulating layer has a two-layer structure and the surface layer of low PVC is formed on the surface, it cannot be realized when a single porous insulating layer (ceramic separator) is used. It can be seen that a lithium ion secondary battery cell (non-aqueous electrolyte battery) with low resistance and no short-circuit failure can be obtained.

<Modification 1>
In Example 1, a porous insulating layer having a two-layer structure is formed on the negative electrode. However, as shown in FIG. 2, a first porous insulating layer (bonding layer) 13 having a high PVC on the positive electrode 1 is used. Furthermore, a second porous insulating layer (surface layer) 23 having a low PVC is formed on the first porous insulating layer (bonding layer) 13 to form a porous insulating layer 3 having a two-layer structure. May be formed. In FIG. 2, the parts denoted by the same reference numerals as those in FIGS. 1A and 1B indicate the same or corresponding parts.

<Modification 2>
In Example 1, a porous insulating layer having a two-layer structure is formed on the negative electrode, but as shown in FIG.
(A) a first porous insulating layer (bonding layer) 13 having a high PVC;
(B) a third porous insulating layer (intermediate layer) 33 having a PVC lower than that of the first porous insulating layer, formed on the first porous insulating layer (bonding layer) 13;
(C) a second porous insulating layer (surface layer) 23 formed on the third porous insulating layer (intermediate layer) 33 and having a PVC lower than that of the first and third porous insulating layers. Alternatively, the porous insulating layer 3 having a three-layer structure may be formed.
In FIG. 3, the parts denoted by the same reference numerals as those in FIGS. 1A and 1B indicate the same or corresponding parts.
The porous insulating layer 3 can also be formed of four or more layers with different PVCs in stages.

  4 (a) and 4 (b) are diagrams showing a main part configuration (configuration of a battery element) of a nonaqueous electrolyte battery according to another example (Example 2) of the present invention, and (a) is a positive electrode. FIG. 2B is a diagram showing the anode and the anode separated, and FIG. 2B is a diagram showing a state in which the cathode and the anode are joined via a porous insulating layer.

  In Example 2, a lithium ion secondary battery cell (non-aqueous electrolyte battery) was produced by the following procedure, and the characteristics of the short circuit failure and the resistance were examined.

(Step 1) Preparation of slurry for positive electrode active material Lithium iron phosphate (Mitsui Engineering & Shipbuilding Co., Ltd .: EF014-LCC, D ₅₀ = 13.2 μm) 84 g, acetylene black 12 g (Electrochemical Industry Co., Ltd .: HS- 100), 100 g of N-methylpyrrolidone (hereinafter referred to as NMP) and 40 g of a 10 wt% NMP solution of polyvinylidene fluoride (Kureha Co., Ltd .: # 7208) are mixed together and stirred with a planetary mixer to obtain a slurry for a positive electrode active material Was made.

(Step 2) Production of slurry for negative electrode active material 85 g of graphite (Mitsubishi Chemical Corporation: GTR6, D ₅₀ = 11.0 μm), 15 g of conductive additive (manufactured by Hitachi Chemical Co., Ltd .: SMSC10-4V3), 100 g of NMP, A slurry for negative electrode active material was prepared by combining 53 g of a 10 wt% NMP solution of polyvinylidene fluoride (manufactured by Kureha Co., Ltd .: # 7305) and stirring with a planetary mixer.

(Step 3) Preparation of Positive Electrode The positive electrode active material slurry prepared in Step 1 was coated on a positive electrode current collector foil made of aluminum foil (manufactured by Tokai Toyo Aluminum Co., Ltd .: thickness 20 μm) with a die coater and dried. The positive electrode was produced by post-pressing.

(Step 4) Production of Negative Electrode The negative electrode active material slurry produced in Step 2 was applied on a negative electrode current collector foil made of rolled copper foil (manufactured by Nippon Foil Co., Ltd .: thickness 10 μm) with a die coater, The negative electrode was produced by pressing after drying.

(Step 5) Formation of high PVC porous insulating layer (bonding layer) In a 500 mL pot, spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle size (D ₅₀ ) 0.3 μm) 100 g, solvent (NMP) 80 g Was introduced. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 39.8 g of a binder solution (20 wt% NMP solution) of PVDF-HFP (manufactured by Kynar: # 2850) was added and mixed for 4 hours at 150 rpm using a rolling ball mill, and 85% PVC slurry for porous insulation layer (Slurry for high PVC porous insulating layer) was prepared.
Then, the produced high-PVC porous insulating layer slurry was applied to the surfaces of the positive electrode produced in step 3 and the negative electrode produced in step 4 with a bar coater, and then dried to obtain a high PVC film having a thickness of 6 μm. A porous insulating layer (bonding layer) was formed. This high PVC porous insulating layer (bonding layer) corresponds to the first porous insulating layer in the present invention.

(Step 6) Formation of low PVC porous insulating layer (surface layer) In a 500 mL pot, spherical alumina powder (manufactured by Denki Kagaku Kogyo Co., Ltd .: average particle diameter (D ₅₀ ) 0.3 μm) 100 g and NMP 80 g as a solvent I put it in. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 151 g of a binder solution (20 wt% NMP solution) of PVDF-HFP (manufactured by Kynar: # 2850) is added and mixed for 4 hours at 150 rpm using a rolling ball mill, and a slurry for porous insulation layer of 60% PVC (low PVC) A slurry for a porous insulating layer) was prepared.
Then, the slurry for the low-PVC porous insulating layer thus prepared is placed on the respective high-PVC porous insulating layers of the positive electrode and the negative electrode having the high-PVC porous insulating layer (bonding layer) formed on the surface thereof in Step 5. After coating with a coater, it was dried to form a low PVC porous insulating layer (surface layer) having a thickness of 1.5 μm. This low PVC porous insulating layer (surface layer) corresponds to the second porous insulating layer in the present invention.

(Step 7) Cut of positive electrode and negative electrode having porous insulating layer formed thereon A negative electrode having a porous insulating layer having a two-layer structure formed through steps 5 and 6 was subjected to a 4.8 cm square battery reaction portion and a negative electrode current collector foil. Then, the exposed tab attachment portion was cut, and a nickel tab was attached to the exposed tab attachment portion of the negative electrode current collector foil to produce a lead electrode.
Similarly, a positive electrode having a porous insulating layer having a two-layer structure formed through steps 5 and 6 is obtained so that a 4.5 cm square battery reaction part and an exposed tab attachment part of the positive electrode current collector foil are obtained. Then, an aluminum tab was attached to the exposed tab attachment portion of the positive electrode current collector foil to produce a lead electrode.

(Step 8) Production of Lithium Ion Secondary Battery Cell One positive electrode having a porous insulating layer having a two-layer structure produced in Step 7, and a negative electrode having a porous insulating layer having a two-layer structure similarly produced in Step 7 Are opposed to each other (see FIG. 4A), and a positive electrode and a negative electrode are joined to each other, thereby forming a battery element 10 having a pair of electrodes (positive electrode 1 and negative electrode 2) as shown in FIG. 4B. Formed. 4A and 4B, the same reference numerals as those in FIGS. 1A and 1B denote the same or corresponding parts.
Then, the formed battery element 10 was sandwiched between two laminate sheets, and three sides were thermocompression bonded with an impulse sealer to produce a laminate package with one side opened.
Next, an electrolytic solution (ion conductive nonaqueous electrolyte) was injected from the opening of the laminate package. As the electrolytic solution, an electrolytic solution in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7 so as to be 1 M was used. .
Then, the lithium ion secondary battery cell (nonaqueous electrolyte battery) was obtained by vacuum-sealing the opening part of a laminate package.

<Confirmation of short circuit failure>
In order to evaluate the characteristics of the lithium ion secondary battery cell (nonaqueous electrolyte battery) produced as described above, the presence or absence of occurrence of short-circuit failure was examined for 10 lithium ion secondary battery cells (samples).
In the same manner as in Example 1 above, first, the lithium ion secondary battery cell was charged to 3.5 V and left at room temperature for 1 week. Then, the voltage of the lithium ion secondary battery cell is measured, and a sample in which a short circuit failure does not occur in a lithium ion secondary battery cell having a voltage of 3.4 V or higher (good product), a lithium ion secondary of less than 3.4 V The battery cell was a sample (defective product) in which a short circuit failure occurred. The results (occurrence rate of short circuit failure) are shown in Table 4.
For comparison, the same samples as those of Comparative Examples 1 and 2 prepared in Example 1 were evaluated by the same method. The results are also shown in Table 4.

<Measurement of resistance>
In order to evaluate the resistance of each lithium ion secondary battery cell, the lithium ion secondary battery cell (sample) as an example produced as described above, and the lithium ion secondary battery cell (sample) of Comparative Examples 1 and 2 ), The input DCR and the output DCR were measured. The DCR was measured using the charge / discharge profile shown in Table 2.
The DCR was measured using the charge / discharge profile shown in Table 2 in the same manner as in Example 1.

  Table 5 shows the measurement results of the input DCR and the output DCR. In addition, the value of input DCR and output DCR which are shown in Table 5 is an average value of the value obtained by measuring about the lithium ion secondary battery cell which is not short-circuited.

  As shown in Tables 4 and 5, a porous insulating layer (ceramic separator) having a two-layer structure of a low PVC porous insulating layer and a high PVC porous insulating layer is formed on each of the positive electrode and the negative electrode. The lithium ion secondary battery cell of Example 2 in which a battery element was formed by bonding a positive electrode and a negative electrode in such a manner that two porous insulating layers having a two-layer structure as described above were interposed (FIG. 4A). In the case of (b)), the lithium ion secondary battery cell of Example 1 described above, that is, a negative electrode in which two porous insulating layers of a low PVC porous insulating layer and a high PVC porous insulating layer are formed. It was confirmed that the same effect as in the case of a lithium ion secondary battery cell (see FIGS. 1 (a) and 1 (b)) produced by combining a positive electrode without forming a porous insulating layer was obtained. .

5 (a) and 5 (b) are diagrams showing a main part configuration (configuration of a battery element) of a nonaqueous electrolyte battery according to another example (Example 3) of the present invention, and (a) is a positive electrode. FIG. 2B is a diagram showing the anode and the anode separated, and FIG. 2B is a diagram showing a state in which the cathode and the anode are joined via a porous insulating layer.
In FIG. 5, the parts denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

  In Example 3, as the porous insulating layer (ceramic separator) 3 disposed between the positive electrode 1 and the negative electrode 2, PVC is connected to the negative electrode 2 from the bonding surface side to the surface side opposite to the bonding surface. A porous insulating layer having a single-layer structure configured so as to continuously decrease is used.

  In Examples 1 and 2, the lithium ion secondary battery cell using the porous insulating layer having a multilayer structure (two-layer structure) as the ceramic separator is shown. As in Example 3, as described above, As the porous insulating layer 3 disposed between the positive electrode 1 and the negative electrode 2, PVC is used from the bonding surface side to the surface side without using the porous insulating layer 3 having a multi-layer structure. Even when the porous insulating layer 3 having a single layer structure that continuously decreases is used, the same effect as in the case of Example 1 can be obtained.

As in Example 3, when a porous insulating layer having a single layer structure in which PVC continuously decreases from the bonding surface side to the surface side, the outer surface of PVC is low and Since there are few defects in the vicinity region, short-circuiting is suppressed compared to the surface vicinity region, and low resistance is realized by regions other than the surface vicinity region where PVC is higher than the surface vicinity region.
As a result, it is possible to simultaneously suppress the short circuit and reduce the resistance.

  In addition, this invention is not limited to the said embodiment and Example, Specific constituent materials and formation methods, such as a positive electrode and a negative electrode, a positive electrode active material, and a negative electrode active material, The kind of ion-conductive nonaqueous electrolyte It is possible to add various applications and modifications within the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode current collection foil 1b Positive electrode active material 2 Negative electrode 2a Negative electrode current collection foil 2b Negative electrode active material 3 Porous insulation layer 10 Battery element 13 1st porous insulation layer 23 2nd porous insulation layer 33 3rd Porous insulation layer

  The present invention relates to a battery, and more specifically, a nonaqueous electrolyte battery including a positive electrode, a negative electrode, an ion conductive nonaqueous electrolyte, and a porous insulating layer (ceramic separator) provided with the positive electrode and the negative electrode, and the same It relates to a manufacturing method.

  For example, in a non-aqueous electrolyte battery such as a lithium ion secondary battery, a separator (polyolefin separator) such as a polyolefin-based stretched film has been widely used as a separator disposed between a positive electrode and a negative electrode.

  Further, a non-aqueous electrolyte battery using a separator (a porous insulating layer or a ceramic separator) in which inorganic fine particles are dispersed in an organic polymer material (binder) has been proposed instead of such a polyolefin-based separator (for example, , See Patent Document 1).

  Unlike the polyolefin-based separator, the ceramic separator as described above has a characteristic that it is not deformed and contracted even in a high temperature environment. Therefore, non-aqueous electrolyte batteries using ceramic separators do not shrink even when exposed to unintended high temperatures, so there is no short circuit between the positive and negative electrodes, heat generation, smoke generation, or ignition, resulting in high safety. Will be secured. In the case of a non-aqueous electrolyte battery using a ceramic separator, this feature provides safety that does not ignite even in a nail clip test.

  However, the ceramic separator has a problem in strength. For example, as shown in FIG. 6, the ceramic separator 103 is configured to maintain electronic insulation only by being interposed between the positive electrode 101 and the negative electrode 102. However, in order to obtain a battery that does not cause the problem of short-circuit failure by securing electronic insulation only with a ceramic separator, the defect is caused by increasing the strength of the ceramic separator. It is necessary not to let it.

  For that purpose, it is effective to increase the ratio of the binder that plays a role of holding inorganic fine particles, and it is effective to reduce the pigment volume concentration (hereinafter referred to as PVC) (Pigment Volume Concentration) of the ceramic separator. .

On the other hand, since the resistance increases as the PVC decreases, the suppression of short circuit and the suppression of resistance are in a trade-off relationship.
Therefore, it is currently difficult to make the resistance lower than that of the conventional polyolefin-based separator while suppressing the occurrence of short circuit failure.

Japanese Patent No. 3253632

  The present invention solves the above problems and is a non-aqueous electrolyte battery including a porous insulating layer (ceramic palator) in which inorganic fine particles are dispersed in an organic polymer material, and suppresses the occurrence of short-circuit defects. However, it aims at providing the nonaqueous electrolyte battery which can implement | achieve low resistance, and its manufacturing method.

In order to solve the above problems, the nonaqueous electrolyte battery of the present invention is
A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A non-aqueous electrolyte battery comprising:
PVC on the outer surface of the porous insulating layer and the vicinity thereof on the opposite side of the bonding surface in contact with the surface of the positive electrode or the negative electrode of the porous insulating layer constitutes the porous insulating layer. rather than lower than the PVC of the area, and,
In the porous insulating layer, the binder contained in the neighboring region and the other region is the same binder .

  In the nonaqueous electrolyte battery of the present invention, “the PVC in the outer surface of the porous insulating layer and the vicinity thereof is lower than the PVC in the other regions constituting the porous insulating layer” The state where PVC is continuously lowered from the bonding surface side to the surface side, the state where the PVC is lowered stepwise, or the porous insulating layer is formed of a plurality of layers, and is the most surface This is a concept including the case where the PVC of the side layer is lower than the PVC of the other layer (except when the PVC of the outermost layer is 0%).

In order to solve the above problems, another non-aqueous electrolyte battery of the present invention includes:
A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A non-aqueous electrolyte battery comprising:
The porous insulating layer comprises a plurality of layers, and
Among the plurality of layers constituting the porous insulating layer, the PVC of the surface layer located on the outermost side of the porous insulating layer on the side opposite to the bonding layer in contact with the surface of the positive electrode or the negative electrode, rather lower than PVC of other layers constituting the porous insulating layer, and,
The binder contained in the surface layer and the other layer constituting the porous insulating layer is the same binder .

  In the nonaqueous electrolyte battery of the present invention, the PVC in a region having a depth from the outer surface of the porous insulating layer or the outer surface of the surface layer to 10% of the total film thickness of the porous insulating layer. Is preferably 70% or less and 40% or more.

  With the above configuration, it is possible to realize low resistance while more reliably suppressing the occurrence of short circuit failure. However, when the outer surface of the porous insulating layer or the PVC of the surface layer is less than 40%, the increase in resistance is increased and a sufficient effect cannot be obtained.

  Further, a region having a depth of up to 50% of the total film thickness of the porous insulating layer from the bonding surface of the porous insulating layer or the bonding surface of the bonding layer in contact with the surface of the positive electrode or the negative electrode of the bonding layer The average value of PVC is preferably 70% or more and less than 95%.

  By adopting the above configuration, it is possible to realize low resistance while more reliably suppressing the occurrence of short circuit failure. However, when the PVC on the joint surface side is 95% or more, defects such as cracking occur even with a weak force, and it is not preferable because the short circuit cannot be sufficiently suppressed.

  Moreover, in the nonaqueous electrolyte battery of this invention, it is preferable that PVC of the said surface layer which comprises the said porous insulating layer is 70% or less and 40% or more.

  By adopting the above configuration, it is possible to realize low resistance while more reliably suppressing the occurrence of short circuit failure. However, when the PVC of the surface layer constituting the porous insulating layer is less than 40%, the increase in resistance becomes large and a sufficient effect cannot be obtained.

  Moreover, it is preferable that PVC of the said joining layer which comprises the said porous insulating layer is 70% or more and 90% or less.

  With the above configuration, it is possible to achieve low resistance while reliably suppressing the occurrence of short circuit failure, and the present invention can be more effectively realized. However, when the PVC of the bonding layer constituting the porous insulating layer is 95% or more, defects such as cracking occur even with a weak force, and short circuit cannot be sufficiently suppressed.

In addition, the method for producing the nonaqueous electrolyte battery of the present invention includes:
A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A method for producing a nonaqueous electrolyte battery comprising a layer,
The step of forming the porous insulating layer includes:
A first step of forming a first porous insulating layer constituting a porous insulating layer on at least one of the positive electrode and the negative electrode;
A second step of forming a second porous insulating layer having a PVC lower than that of the first porous insulating layer on the first porous insulating layer , and
The binder contained in the first porous insulating layer and the second porous insulating layer is the same binder .

As described above, the nonaqueous electrolyte battery of the present invention is formed on the surface of at least one of the positive electrode, the negative electrode, the ion conductive nonaqueous electrolyte, the positive electrode and the negative electrode, and has insulating inorganic fine particles and a binder. In a non-aqueous electrolyte battery comprising a porous insulating layer (ceramic separator) disposed between a positive electrode and a negative electrode, the surface of the positive electrode or the negative electrode of the porous insulating layer PVC on the outer surface of the porous insulating layer on the side opposite to the bonding surface in contact with the surface of the porous insulating layer and in the vicinity thereof is lower than PVC in other regions constituting the porous insulating layer, and the porous insulating layer has Since the binder contained in the neighboring region and the other region is the same binder, a short circuit is suppressed by the outer surface having a low PVC and the neighboring region, and the outer surface and the neighborhood thereof. PVC outside the area And the low-resistance is achieved by the higher regions near the surface region.
As a result, it is possible to provide a non-aqueous electrolyte battery that can simultaneously realize suppression of short circuit and reduction of resistance.

In addition, as described above, another non-aqueous electrolyte battery of the present invention is formed on at least one surface of a positive electrode, a negative electrode, an ion conductive non-aqueous electrolyte, and a positive electrode and a negative electrode. In a non-aqueous electrolyte battery comprising a porous insulating layer (ceramic separator) made of a material including a binder and disposed between a positive electrode and a negative electrode, the porous insulating layer includes a plurality of porous insulating layers. PVC of a surface layer located on the outermost side of the porous insulating layer on the side opposite to the bonding layer in contact with the surface of the positive electrode or the negative electrode, out of a plurality of layers constituting the porous insulating layer However, the binder contained in the surface layer and other layers constituting the porous insulating layer is lower than the PVC of the other layers constituting the porous insulating layer, and is the same binder. So that the surface layer with low PVC is short-circuited. Is suppressed, and, other than the surface layer, PVC low resistance is realized by the higher surface region near the layer.
As a result, it is possible to provide a non-aqueous electrolyte battery that can simultaneously realize suppression of short circuit and reduction of resistance.

In addition, the method for producing a nonaqueous electrolyte battery of the present invention includes a positive electrode, a negative electrode, an ion conductive nonaqueous electrolyte, and at least one surface of the positive electrode and the negative electrode, and insulating inorganic fine particles and a binder. In manufacturing a non-aqueous electrolyte battery comprising a porous insulating layer comprising a plurality of layers disposed so as to be interposed between a positive electrode and a negative electrode, a plurality of layers are laminated. A first step of forming a first porous insulating layer constituting the porous insulating layer on at least one of the positive electrode and the negative electrode, and on the first porous insulating layer And a second step of forming a second porous insulating layer having a PVC lower than that of the first porous insulating layer , and the first porous insulating layer and the second porous insulating layer The included binder is the same binder Thus, it is possible to reliably obtain a nonaqueous electrolyte battery capable of realizing low resistance while suppressing occurrence of short circuit failure.

  In the method for producing a nonaqueous electrolyte battery of the present invention, the first porous insulating layer may have a single layer structure or a multi-layer structure.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the principal part structure (structure of a battery element) of the lithium ion secondary battery cell (nonaqueous electrolyte battery) concerning one Example (Example 1) of this invention, (a) is a positive electrode, The figure which isolate | separates and shows a negative electrode, (b) is a figure which shows the state in which the positive electrode and the negative electrode were joined through the porous insulating layer. It is a figure which shows the other example (modified example 1) of the battery element which comprises the lithium ion secondary battery cell (nonaqueous electrolyte battery) of this invention. It is a figure which shows the further another example (modification 2) of the battery element which comprises the lithium ion secondary battery cell (nonaqueous electrolyte battery) of this invention. It is a figure which shows typically the principal part structure of the lithium ion secondary battery cell concerning other Example (Example 2) of this invention, (a) is a figure which isolate | separates and shows a positive electrode and a negative electrode, (b) FIG. 3 is a view showing a state in which a positive electrode and a negative electrode are joined via a porous insulating layer. It is a figure which shows typically the principal part structure of the lithium ion secondary battery cell concerning another Example (Example 3) of this invention, (a) is a figure which isolate | separates and shows a positive electrode and a negative electrode, (b) ) Is a diagram showing a state in which a positive electrode and a negative electrode are joined via a porous insulating layer. It is a figure which shows the principal part structure of the conventional nonaqueous electrolyte battery.

  1 (a) and 1 (b) are diagrams showing a main part configuration (configuration of a battery element) of a nonaqueous electrolyte battery according to an embodiment (Embodiment 1) of the present invention. The figure which isolate | separates and shows a negative electrode, (b) is a figure which shows the state with which the positive electrode and the negative electrode were joined through the porous insulating layer.

A battery element 10 constituting this nonaqueous electrolyte battery is formed by applying a positive electrode 1 obtained by applying a positive electrode active material 1b on a positive electrode current collector foil 1a and a negative electrode active material 2b on a negative electrode current collector foil 2a. A negative electrode 2 and a porous insulating layer 3 formed on at least one surface of the positive electrode 1 and the negative electrode 2 (the surface of the negative electrode 2 in this embodiment) are provided.
The porous insulating layer 3 is made of a material containing insulating inorganic fine particles and a binder, and is disposed so as to be interposed between the positive electrode 1 and the negative electrode 2.

  The porous insulating layer 3 includes a first porous insulating layer 13 made of a high PVC material formed on the surface of the negative electrode 2, and a first porous layer formed on the first porous insulating layer 13. A second porous insulating layer 23 having a PVC lower than that of the porous insulating layer 13 is provided.

  Incidentally, in order to reduce the resistance of the porous insulating layer (ceramic separator) 3, it is effective to increase the PVC. This is because as the PVC becomes higher, voids increase and the electrolyte solution is more easily impregnated, and the obstacles to the path of ions moving during the charge / discharge reaction decrease.

  On the other hand, the higher the PVC is, the lower the proportion of the binder (binder) that holds the inorganic fine particles, so that the inorganic fine particles are likely to drop off, and a short circuit failure is likely to occur. In addition, when the PVC becomes high, defects such as cracks and cracks are easily generated in the porous insulating layer due to external force, the underlying electrode is exposed, and the exposed part contacts the other electrode. It becomes easy to cause. Such defects in the porous insulating layer can occur during the manufacturing process, and can also occur during use as a battery. During use, a short circuit, especially when fully charged, can lead to overheating, smoke, and fire.

  As described above, there is a trade-off relationship between making the resistance low and making the short circuit difficult, and there is a limit in reducing the resistance of the ceramic separator while preventing the short circuit.

  On the other hand, in the nonaqueous electrolyte battery of the present invention, the bonding layer (first porous layer) in contact with the surface of the negative electrode 2 among the plurality of layers (two layers in this embodiment) constituting the porous insulating layer 3. PVC of the surface layer (second porous insulating layer) 23 located on the outermost side of the porous insulating layer 3 on the side opposite to the porous insulating layer) 13 is replaced with another layer (this In the embodiment, the bonding layer 13) is made lower than the PVC. That is, in the present invention, the PVC of the surface layer 23 is made the lowest among the layers constituting the porous insulating layer 3.

  As a result, a short circuit is suppressed by the surface layer 23 having a low PVC, and a low resistance is realized by the layer (junction layer) 13 having a high PVC other than the surface layer 23, so that both the low resistance and the suppression of the short circuit can be achieved. become able to.

  Specifically, a region having a depth from the outer surface of the porous insulating layer 3 (that is, the outer surface of the surface layer 23) to 10% of the total film thickness of the porous insulating layer 3 (for example, the porous insulating layer) When the total film thickness is 15 μm, it is desirable that the average value of the pigment volume concentration PVC in the region of 1.5 μm from the outer surface of the surface layer 23 is 70% or less and 40% or more.

  Moreover, in the present invention, as described above, the PVC of the surface layer 23 constituting the porous insulating layer 3 is lowered to improve the strength of the outer surface of the porous insulating layer 3, so that it is lower than the surface layer 23. In the side layer (the bonding layer 13 in this embodiment), it becomes possible to increase the PVC in order to realize a low resistance. However, when the outer surface of the porous insulating layer or the PVC of the surface layer is less than 40%, the increase in resistance is increased and a sufficient effect cannot be obtained.

  For example, the total thickness of the first porous insulating layer (bonding layer) 13 formed on the surface of the negative electrode 2 and the second porous insulating layer (surface layer) 23 formed thereon is 15 μm. When the porous insulating layer 3 is formed, the thickness of the bonding layer 13, which is a high PVC layer, is 13 μm, and the thickness of the surface layer 23, which is a low PVC layer, is 2 μm. Can be obtained.

  Further, as the thickness of the surface layer (second porous insulating layer) 23 having a low PVC is made thinner, the proportion of the bonding layer (first porous insulating layer) having a higher PVC is relatively increased. It becomes possible to raise PVC in the whole insulating layer, and to achieve lower resistance.

  The porous insulating layer used in the nonaqueous electrolyte battery of the present invention can be easily obtained by, for example, a method of applying a slurry prepared for forming a porous insulating layer on an electrode (positive electrode or negative electrode). Can do.

  In this case, for example, a porous insulating layer having a two-layer structure is prepared by applying a slurry for a porous insulating layer for a lower layer on an electrode (positive electrode or negative electrode) and drying to form a porous insulating layer (bonding layer) on the lower layer side. After forming, the slurry for forming the porous insulating layer for the surface layer is applied on the lower porous insulating layer and dried to form the porous insulating layer (surface layer) on the surface side. Can do.

  And when it manufactures with such a manufacturing method, when a coating-film defect, such as a pinhole, arises in the porous insulating layer (bonding layer) on the lower layer side, when forming the porous insulating layer of the surface layer Since the coating film defect of the bonding layer is repaired, it is possible to prevent the porous insulating layer as a whole from having a defect causing a problem. As a result, it is possible to more reliably suppress the occurrence of short circuit failure.

  1 has a two-layer structure in which a low-PVC surface layer (second porous insulating layer) 23 is formed on a high-PVC bonding layer (first porous insulating layer) 13. Although the porous insulating layer 3 is shown, in the present invention, it is not necessary to have a structure in which the bonding layer 13 having a high PVC and the surface layer 23 having a low PVC are clearly divided into layers. It is only necessary that the outer surface 3 and the vicinity thereof are made of a low PVC material.

  What is important in the present invention is to lower the PVC of the outer surface of the porous insulating layer and the vicinity thereof to prevent defects in the porous insulating layer as a whole. In the region other than the surface and the vicinity thereof, PVC is increased to reduce the resistance, and each layer does not need to be clearly divided.

  Therefore, for example, a layer having a PVC gradient (transition layer) such that the PVC gradually decreases from the one main surface side closer to the electrode toward the other main surface side (transition from high PVC to low PVC). Can be made to exist in a single layer, and in this case, the same effect can be obtained.

  Whether the structure is clearly divided or the structure in which PVC continuously changes in the layer is, for example, the porous insulating layer in forming the outermost porous insulating layer. The viscosity can be adjusted by appropriately selecting the viscosity of the slurry for formation and the porosity of the porous insulating layer serving as the base.

In addition, PVC (Pigment Volume Concentration; pigment volume concentration) is calculated | required by following formula (1).
PVC = (volume of inorganic fine particles) / (volume of inorganic fine particles + volume of organic binder) × 100 (1)
Volume of inorganic fine particles = weight of inorganic fine particles / density of inorganic fine particles Volume of organic binder = weight of organic binder / density of organic binder

  A lithium ion secondary battery cell (non-aqueous electrolyte battery) was produced by the following procedure, and the characteristics of the short circuit failure and the resistance were examined.

(Step 1) Preparation of slurry for positive electrode active material
By combining 84 g of lithium iron phosphate ( D ₅₀ = 13.2 μm), 12 g of acetylene black, 100 g of N-methylpyrrolidone (hereinafter referred to as NMP), and 40 g of a 10 wt% NMP solution of polyvinylidene fluoride , the mixture was stirred with a planetary mixer. A slurry for positive electrode active material was prepared.

(Step 2) Preparation of slurry for negative electrode active material
A slurry for negative electrode active material was prepared by combining 85 g of graphite ( D ₅₀ = 11.0 μm), 15 g of a conductive aid , 100 g of NMP, and 53 g of a 10 wt% NMP solution of polyvinylidene fluoride and stirring with a planetary mixer.

(Step 3) Production of Positive Electrode The positive electrode active material slurry produced in Step 1 was coated on a positive electrode current collector foil made of aluminum foil (thickness 20 μm) with a die coater, dried and pressed to produce a positive electrode. .
The positive electrode produced in this way was cut so as to obtain a 4.5 cm square battery reaction part and a tab attachment part where the positive electrode current collector foil was exposed, and an aluminum tab was attached to the tab attachment part where the positive electrode current collector foil was exposed. Attachment and extraction electrodes were formed.

(Step 4) Production of Negative Electrode The negative electrode active material slurry produced in Step 2 was coated on a negative electrode current collector foil made of rolled copper foil (thickness 10 μm) with a die coater, dried and pressed to obtain the negative electrode. Produced.

(Step 5) Formation of high PVC porous insulating layer (bonding layer) 100 g of spherical alumina powder ( average particle diameter (D ₅₀ ) 0.3 μm) and 80 g of solvent (NMP) were charged into a 500 mL pot. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 39.8 g of a PVDF-HFP binder solution (20 wt% NMP solution) was added and mixed for 4 hours at 150 rpm using a rolling ball mill, and a 85% PVC porous insulating layer slurry (high PVC porous insulating layer) Slurry) was prepared.
And after apply | coating the produced slurry for high PVC porous insulation layers on the negative electrode produced at the process 4 with the bar coater, it was made to dry and the 13-micrometer-thick high PVC porous insulation layer (joining layer) was formed. This high PVC porous insulating layer (bonding layer) corresponds to the first porous insulating layer in the present invention.

(Step 6) Formation of Low PVC Porous Insulating Layer (Surface Layer) A 500 mL pot was charged with 100 g of spherical alumina powder ( average particle diameter (D ₅₀ ) 0.3 μm) and NMP 80 g as a solvent. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 151 g of PVDF-HFP binder solution (20 wt% NMP solution) was added and mixed for 4 hours at 150 rpm using a rolling ball mill, and a slurry for porous insulation layer of 60% PVC (slurry for low PVC porous insulation layer) Was made.
Then, the prepared slurry for low PVC porous insulating layer was coated on the high PVC porous insulating layer (bonding layer) formed on the negative electrode in Step 5 with a bar coater, and then dried to a film thickness of 2 μm. A low PVC porous insulating layer (surface layer) was formed. This low PVC porous insulating layer (surface layer) corresponds to the second porous insulating layer in the present invention.

(Step 7) Cut of negative electrode on which porous insulating layer is formed A porous insulating layer comprising a high PVC porous insulating layer (bonding layer) having a thickness of 13 μm and a low PVC porous insulating layer (surface layer) having a thickness of 2 μm The negative electrode obtained in step 6 is cut so as to obtain a battery reaction portion of 4.8 cm square and a tab attachment portion where the negative electrode current collector foil is exposed, and further, the tab attachment portion where the negative electrode current collector foil is exposed A nickel tab was attached to the lead electrode to form a lead electrode.

(Step 8) Production of Lithium Ion Secondary Battery Cell One positive electrode produced in Step 3 is opposed to a negative electrode having a two-layered porous insulating layer composed of a bonding layer and a surface layer produced in Step 7. 1 (a)), the positive electrode 1 and the negative electrode 2 are joined to each other through the porous insulating layer 3 having a two-layer structure, as shown in FIG. 1 (b). (Ceramic separator) A battery element 10 having a structure joined via 3 was obtained.
Then, the formed battery element 10 was sandwiched between two laminate sheets, and three sides were thermocompression bonded with an impulse sealer to produce a laminate package with one side opened.
Next, an electrolytic solution (ion conductive nonaqueous electrolyte) was injected from the opening of the laminate package. As the electrolytic solution, an electrolytic solution in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) at a volume ratio of 3: 7 so as to be 1 M was used.
Then, the lithium ion secondary battery cell (nonaqueous electrolyte battery) was obtained by vacuum-sealing the opening part of a laminate package.

<Confirmation of short circuit failure>
In order to evaluate the characteristics of the lithium ion secondary battery cell (nonaqueous electrolyte battery) produced as described above, the presence or absence of occurrence of short-circuit failure was examined for 10 lithium ion secondary battery cells (samples). The presence or absence of occurrence of short-circuit failure was examined by the method described below.

First, the lithium ion secondary battery cell was charged to 3.5 V and left at room temperature for 1 week.
Then, the voltage of the lithium ion secondary battery cell is measured, and a sample in which a short circuit failure does not occur in a lithium ion secondary battery cell having a voltage of 3.4 V or higher (good product), a lithium ion secondary of less than 3.4 V The battery cell was a sample (defective product) in which a short circuit failure occurred. The results (occurrence rate of short circuit failure) are shown in Table 1.

For comparison, lithium ion secondary battery cells (samples of Comparative Examples 1 and 2) were prepared in the same manner as in the above example except that the porous insulating layer was a single layer. In addition, as a sample of a comparative example, the thing of 85% of PVC and the thing of 70% were produced as a single layer porous insulating layer. Note that the thickness of each porous insulating layer was 15 μm.
And also about the lithium ion secondary battery cell of the comparative examples 1 and 2, it evaluated by the method similar to the case of the above-mentioned Example. The results are also shown in Table 1.

<Measurement of resistance>
In order to evaluate the resistance of each lithium ion secondary battery cell, the lithium ion secondary battery cell (sample) as an example produced as described above, and the lithium ion secondary battery cell (sample) of Comparative Examples 1 and 2 ), The input DCR and the output DCR were measured. The DCR was measured using the charge / discharge profile shown in Table 2.

  Table 3 shows the results of measurement of input DCR and output DCR performed on the sample of the example and the samples of comparative examples 1 and 2. In addition, the values of the input DCR and the output DCR shown in Table 3 are average values of values obtained by measuring lithium ion secondary battery cells (samples) that are not short-circuited.

  As shown in Table 1, in the case of the lithium ion secondary battery cells (samples) of Comparative Examples 1 and 2 using a porous insulating layer having a single layer structure as a ceramic separator, 85% of PVC was used as in Comparative Example 1. It has been confirmed that short circuit defects occur due to falling off or cracking of inorganic fine particles.

  Further, even in a sample in which the PVC of the porous insulating layer having a single layer structure is designed to be low so that the short circuit can be suppressed (sample with 70% PVC), the occurrence of short circuit failure cannot be eliminated.

On the other hand, in the case of the sample of the example in which the porous insulating layer has a two-layer structure and the surface layer of low PVC is located on the surface side, it was confirmed that no short circuit failure occurred.
This is due to the effect of short circuit suppression by improving the strength of the outer surface of the porous insulating layer and the effect of repairing defects in the porous insulating layer (bonding layer) on the lower layer side by the two-layer coating. It is thought that it became possible to prevent.

  In addition, as shown in Table 3, in the case of the sample of the example in which the porous insulating layer has a two-layer structure and the surface layer of low PVC is formed on the surface, the resistance due to the formation of the surface layer of low PVC on the surface is reduced. It was confirmed that the increase rate, that is, the increase rate of the resistance of the sample of the example with respect to the resistance of the sample of Comparative Example 1 was less than 3%, which was a slight increase rate.

  Moreover, the sample of the comparative example 2 (PVC70%) which designed the PVC of the porous insulation layer of the single layer structure low in order to suppress the short circuit failure, and the porous insulation layer have a two-layer structure, and the surface of the low PVC on the surface When the resistance of the sample of the example in which the layer was formed was compared, it was confirmed that the resistance of the sample of the example was reduced by about 30%.

  From this result, in the case of the sample of the example in which the porous insulating layer has a two-layer structure and the surface layer of low PVC is formed on the surface, it cannot be realized when a single porous insulating layer (ceramic separator) is used. It can be seen that a lithium ion secondary battery cell (non-aqueous electrolyte battery) with low resistance and no short-circuit failure can be obtained.

<Modification 1>
In Example 1, a porous insulating layer having a two-layer structure is formed on the negative electrode. However, as shown in FIG. 2, a first porous insulating layer (bonding layer) 13 having a high PVC on the positive electrode 1 is used. Furthermore, a second porous insulating layer (surface layer) 23 having a low PVC is formed on the first porous insulating layer (bonding layer) 13 to form a porous insulating layer 3 having a two-layer structure. May be formed. In FIG. 2, the parts denoted by the same reference numerals as those in FIGS. 1A and 1B indicate the same or corresponding parts.

<Modification 2>
In Example 1, a porous insulating layer having a two-layer structure is formed on the negative electrode, but as shown in FIG.
(A) a first porous insulating layer (bonding layer) 13 having a high PVC;
(B) a third porous insulating layer (intermediate layer) 33 having a PVC lower than that of the first porous insulating layer, formed on the first porous insulating layer (bonding layer) 13;
(C) a second porous insulating layer (surface layer) 23 formed on the third porous insulating layer (intermediate layer) 33 and having a PVC lower than that of the first and third porous insulating layers. Alternatively, the porous insulating layer 3 having a three-layer structure may be formed.
In FIG. 3, the parts denoted by the same reference numerals as those in FIGS. 1A and 1B indicate the same or corresponding parts.
The porous insulating layer 3 can also be formed of four or more layers with different PVCs in stages.

  4 (a) and 4 (b) are diagrams showing a main part configuration (configuration of a battery element) of a nonaqueous electrolyte battery according to another example (Example 2) of the present invention, and (a) is a positive electrode. FIG. 2B is a diagram showing the anode and the anode separated, and FIG. 2B is a diagram showing a state in which the cathode and the anode are joined via a porous insulating layer.

  In Example 2, a lithium ion secondary battery cell (non-aqueous electrolyte battery) was produced by the following procedure, and the characteristics of the short circuit failure and the resistance were examined.

(Step 1) Preparation of slurry for positive electrode active material
By combining 84 g of lithium iron phosphate ( D ₅₀ = 13.2 μm), 12 g of acetylene black, 100 g of N-methylpyrrolidone (hereinafter referred to as NMP), and 40 g of a 10 wt% NMP solution of polyvinylidene fluoride , the mixture was stirred with a planetary mixer. A slurry for positive electrode active material was prepared.

(Step 2) Preparation of slurry for negative electrode active material
A slurry for negative electrode active material was prepared by combining 85 g of graphite ( D ₅₀ = 11.0 μm), 15 g of a conductive aid , 100 g of NMP, and 53 g of a 10 wt% NMP solution of polyvinylidene fluoride and stirring with a planetary mixer.

(Step 3) Production of Positive Electrode The positive electrode active material slurry produced in Step 1 was coated on a positive electrode current collector foil made of aluminum foil ( thickness 20 μm) with a die coater, dried and pressed to produce a positive electrode. did.

(Step 4) Production of Negative Electrode The negative electrode active material slurry produced in Step 2 was coated on a negative electrode current collector foil made of rolled copper foil ( thickness 10 μm) with a die coater, dried and pressed to obtain the negative electrode. Produced.

(Step 5) Formation of high PVC porous insulating layer (bonding layer) 100 g of spherical alumina powder ( average particle diameter (D ₅₀ ) 0.3 μm) and 80 g of solvent (NMP) were charged into a 500 mL pot. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 39.8 g of a PVDF-HFP binder solution (20 wt% NMP solution) was added and mixed for 4 hours at 150 rpm using a rolling ball mill, and a 85% PVC slurry for a porous insulating layer (high PVC porous insulating layer) Slurry) was prepared.
Then, the produced high-PVC porous insulating layer slurry was applied to the surfaces of the positive electrode produced in step 3 and the negative electrode produced in step 4 with a bar coater, and then dried to obtain a high PVC film having a thickness of 6 μm. A porous insulating layer (bonding layer) was formed. This high PVC porous insulating layer (bonding layer) corresponds to the first porous insulating layer in the present invention.

(Step 6) Formation of Low PVC Porous Insulating Layer (Surface Layer) A 500 mL pot was charged with 100 g of spherical alumina powder ( average particle diameter (D ₅₀ ) 0.3 μm) and NMP 80 g as a solvent. Further, PSZ grinding media having a diameter of 5 mm were put, and the mixture was dispersed by mixing at 150 rpm for 16 hours using a rolling ball mill.
Thereafter, 151 g of PVDF-HFP binder solution (20 wt% NMP solution) was added and mixed for 4 hours at 150 rpm using a rolling ball mill, and a slurry for porous insulation layer of 60% PVC (slurry for low PVC porous insulation layer) Was made.
Then, the slurry for the low-PVC porous insulating layer thus prepared is placed on the respective high-PVC porous insulating layers of the positive electrode and the negative electrode having the high-PVC porous insulating layer (bonding layer) formed on the surface thereof in Step 5. After coating with a coater, it was dried to form a low PVC porous insulating layer (surface layer) having a thickness of 1.5 μm. This low PVC porous insulating layer (surface layer) corresponds to the second porous insulating layer in the present invention.

(Step 7) Cut of positive electrode and negative electrode having porous insulating layer formed thereon A negative electrode having a porous insulating layer having a two-layer structure formed through steps 5 and 6 was subjected to a 4.8 cm square battery reaction portion and a negative electrode current collector foil. Then, the exposed tab attachment portion was cut, and a nickel tab was attached to the exposed tab attachment portion of the negative electrode current collector foil to produce a lead electrode.
Similarly, a positive electrode having a porous insulating layer having a two-layer structure formed through steps 5 and 6 is obtained so that a 4.5 cm square battery reaction part and an exposed tab attachment part of the positive electrode current collector foil are obtained. Then, an aluminum tab was attached to the exposed tab attachment portion of the positive electrode current collector foil to produce a lead electrode.

(Step 8) Production of Lithium Ion Secondary Battery Cell One positive electrode having a porous insulating layer having a two-layer structure produced in Step 7, and a negative electrode having a porous insulating layer having a two-layer structure similarly produced in Step 7 Are opposed to each other (see FIG. 4A), and a positive electrode and a negative electrode are joined to each other, thereby forming a battery element 10 having a pair of electrodes (positive electrode 1 and negative electrode 2) as shown in FIG. 4B. Formed. 4A and 4B, the same reference numerals as those in FIGS. 1A and 1B denote the same or corresponding parts.
Then, the formed battery element 10 was sandwiched between two laminate sheets, and three sides were thermocompression bonded with an impulse sealer to produce a laminate package with one side opened.
Next, an electrolytic solution (ion conductive nonaqueous electrolyte) was injected from the opening of the laminate package. As the electrolytic solution, an electrolytic solution in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7 so as to be 1 M was used. .
Then, the lithium ion secondary battery cell (nonaqueous electrolyte battery) was obtained by vacuum-sealing the opening part of a laminate package.

<Confirmation of short circuit failure>
In order to evaluate the characteristics of the lithium ion secondary battery cell (nonaqueous electrolyte battery) produced as described above, the presence or absence of occurrence of short-circuit failure was examined for 10 lithium ion secondary battery cells (samples).
In the same manner as in Example 1 above, first, the lithium ion secondary battery cell was charged to 3.5 V and left at room temperature for 1 week. Then, the voltage of the lithium ion secondary battery cell is measured, and a sample in which a short circuit failure does not occur in a lithium ion secondary battery cell having a voltage of 3.4 V or higher (good product), a lithium ion secondary of less than 3.4 V The battery cell was a sample (defective product) in which a short circuit failure occurred. The results (occurrence rate of short circuit failure) are shown in Table 4.
For comparison, the same samples as those of Comparative Examples 1 and 2 prepared in Example 1 were evaluated by the same method. The results are also shown in Table 4.

<Measurement of resistance>
In order to evaluate the resistance of each lithium ion secondary battery cell, the lithium ion secondary battery cell (sample) as an example produced as described above, and the lithium ion secondary battery cell (sample) of Comparative Examples 1 and 2 ), The input DCR and the output DCR were measured. The DCR was measured using the charge / discharge profile shown in Table 2.
The DCR was measured using the charge / discharge profile shown in Table 2 in the same manner as in Example 1.

  Table 5 shows the measurement results of the input DCR and the output DCR. In addition, the value of input DCR and output DCR which are shown in Table 5 is an average value of the value obtained by measuring about the lithium ion secondary battery cell which is not short-circuited.

  As shown in Tables 4 and 5, a porous insulating layer (ceramic separator) having a two-layer structure of a low PVC porous insulating layer and a high PVC porous insulating layer is formed on each of the positive electrode and the negative electrode. The lithium ion secondary battery cell of Example 2 in which a battery element was formed by bonding a positive electrode and a negative electrode in such a manner that two porous insulating layers having a two-layer structure as described above were interposed (FIG. 4A). In the case of (b)), the lithium ion secondary battery cell of Example 1 described above, that is, a negative electrode in which two porous insulating layers of a low PVC porous insulating layer and a high PVC porous insulating layer are formed. It was confirmed that the same effect as in the case of a lithium ion secondary battery cell (see FIGS. 1 (a) and 1 (b)) produced by combining a positive electrode without forming a porous insulating layer was obtained. .

5 (a) and 5 (b) are diagrams showing a main part configuration (configuration of a battery element) of a nonaqueous electrolyte battery according to another example (Example 3) of the present invention, and (a) is a positive electrode. FIG. 2B is a diagram showing the anode and the anode separated, and FIG. 2B is a diagram showing a state in which the cathode and the anode are joined via a porous insulating layer.
In FIG. 5, the parts denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding parts.

  In Example 3, as the porous insulating layer (ceramic separator) 3 disposed between the positive electrode 1 and the negative electrode 2, PVC is connected to the negative electrode 2 from the bonding surface side to the surface side opposite to the bonding surface. A porous insulating layer having a single-layer structure configured so as to continuously decrease is used.

  In Examples 1 and 2, the lithium ion secondary battery cell using the porous insulating layer having a multilayer structure (two-layer structure) as the ceramic separator is shown. As in Example 3, as described above, As the porous insulating layer 3 disposed between the positive electrode 1 and the negative electrode 2, PVC is used from the bonding surface side to the surface side without using the porous insulating layer 3 having a multi-layer structure. Even when the porous insulating layer 3 having a single layer structure that continuously decreases is used, the same effect as in the case of Example 1 can be obtained.

As in Example 3, when a porous insulating layer having a single layer structure in which PVC continuously decreases from the bonding surface side to the surface side, the outer surface of PVC is low and Since there are few defects in the vicinity region, short-circuiting is suppressed compared to the surface vicinity region, and low resistance is realized by regions other than the surface vicinity region where PVC is higher than the surface vicinity region.
As a result, it is possible to simultaneously suppress the short circuit and reduce the resistance.

  In addition, this invention is not limited to the said embodiment and Example, Specific constituent materials and formation methods, such as a positive electrode and a negative electrode, a positive electrode active material, and a negative electrode active material, The kind of ion-conductive nonaqueous electrolyte It is possible to add various applications and modifications within the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode current collection foil 1b Positive electrode active material 2 Negative electrode 2a Negative electrode current collection foil 2b Negative electrode active material 3 Porous insulation layer 10 Battery element 13 1st porous insulation layer 23 2nd porous insulation layer 33 3rd Porous insulation layer

Claims (7)

A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A non-aqueous electrolyte battery comprising:
The pigment volume concentration (hereinafter referred to as PVC) of the outer surface of the porous insulating layer and the vicinity thereof on the opposite side of the bonding surface in contact with the surface of the positive electrode or the negative electrode of the porous insulating layer is the porous material. A nonaqueous electrolyte battery characterized by being lower than PVC in other regions constituting the insulating layer. A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A non-aqueous electrolyte battery comprising:
The porous insulating layer comprises a plurality of layers, and
Among the plurality of layers constituting the porous insulating layer, the PVC of the surface layer located on the outermost side of the porous insulating layer on the side opposite to the bonding layer in contact with the surface of the positive electrode or the negative electrode, A nonaqueous electrolyte battery characterized by being lower than PVC of other layers constituting the porous insulating layer.   The average value of PVC in the region from the outer surface of the porous insulating layer or the outer surface of the surface layer to a depth of 10% of the total film thickness of the porous insulating layer is 70% or less, 40% or more. The nonaqueous electrolyte battery according to claim 1, wherein the nonaqueous electrolyte battery is provided.   PVC in a region having a depth of up to 50% of the total film thickness of the porous insulating layer from the bonding surface of the porous insulating layer or the bonding surface of the bonding layer in contact with the surface of the positive electrode or the negative electrode of the bonding layer The non-aqueous electrolyte battery according to claim 1, wherein an average value of the non-aqueous electrolyte battery is 70% or more and 95% or less.   The non-aqueous electrolyte battery according to claim 2, wherein the surface layer constituting the porous insulating layer has a PVC of 70% or less and 40% or more.   The non-aqueous electrolyte battery according to claim 2, wherein the bonding layer constituting the porous insulating layer has a PVC of 70% or more and 95% or less. A positive electrode;
A negative electrode,
An ion conductive non-aqueous electrolyte;
Porous insulation formed on a surface of at least one of the positive electrode and the negative electrode, made of a material containing insulating inorganic fine particles and a binder, and disposed between the positive electrode and the negative electrode A method for producing a nonaqueous electrolyte battery comprising a layer,
The step of forming the porous insulating layer includes:
A first step of forming a first porous insulating layer constituting a porous insulating layer on at least one of the positive electrode and the negative electrode;
And a second step of forming a second porous insulating layer having a PVC lower than that of the first porous insulating layer on the first porous insulating layer. Battery manufacturing method.

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