JP2020191224A - Non-aqueous electrolyte power storage element - Google Patents

Abstract

To provide a non-aqueous electrolyte power storage element having excellent output performance after a charge/discharge cycle and an effect of suppressing a minute short circuit between a positive electrode and a negative electrode.SOLUTION: A non-aqueous electrolyte power storage element according to an embodiment of the present invention includes a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and a separator having a porous resin layer laminated along the negative electrode mixture layer and uniaxially stretched, and a relationship between the peak intensity ratio (I(002)/I(110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer, and the air permeability B (seconds/100 mL) of the porous resin layer satisfies 5.7≤A×B/10000≤15.2.SELECTED DRAWING: None

Description

The present invention relates to a non-aqueous electrolyte power storage device.

Non-aqueous electrolyte secondary batteries represented by lithium ion non-aqueous electrolyte secondary batteries are widely used in electronic devices such as personal computers and communication terminals, automobiles, etc. due to their high energy density. The non-aqueous electrolyte secondary battery generally includes an electrode body having a pair of electrodes electrically separated by a separator, and a non-aqueous electrolyte interposed between the electrodes, and transfers ions between the two electrodes. It is configured to charge and discharge by doing so. In addition, capacitors such as lithium ion capacitors and electric double layer capacitors are also widely used as non-aqueous electrolyte power storage elements other than non-aqueous electrolyte secondary batteries.

As a technique for increasing the energy density of such a non-aqueous electrolyte power storage element, for example, increasing the density of the negative electrode active material, thinning the separator, and the like have been proposed (see Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2014-209472 JP-A-2007-179758

However, as the negative electrode expands during charging, the load applied in the average thickness direction of the non-aqueous electrolyte power storage element (that is, the direction in which the positive electrode, the separator, and the negative electrode are laminated) becomes remarkable. Therefore, in the above-mentioned prior art, the pores of the separator are blocked by the increase in load and the ionic conductivity is lowered, so that the output performance of the non-aqueous electrolyte power storage element after the charge / discharge cycle may be lowered. It is known that the decrease in ionic conductivity can be improved by using a separator having a high compressive elastic modulus in the average thickness direction or a separator having a high porosity indicating a void volume ratio to solve the above problems. On the other hand, when a separator having a high compressive elastic modulus or porosity is used, the tensile strength in the in-plane direction (that is, the direction orthogonal to the average thickness direction), which is a direction parallel to the surface of the separator, decreases. During charging, the negative electrode expands in the in-plane direction in addition to the expansion in the average thickness direction. Therefore, when the separator having a high compressive elastic modulus and porosity is used, the separator is easily deformed by being pulled by the negative electrode that expands during charging, and the void volume increases, resulting in a minute short circuit between the positive electrode and the negative electrode. The incidence may increase.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a non-aqueous electrolyte power storage element excellent in output performance after a charge / discharge cycle and an effect of suppressing a minute short circuit between a positive electrode and a negative electrode. To do.

One aspect of the present invention made to solve the above problems has a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles and a uniaxially stretched porous resin layer, and the negative electrode combination. A separator laminated along the agent layer is provided, and the peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and The non-aqueous electrolyte power storage element has a relationship with the air permeability B (seconds / 100 mL) of the porous resin layer of 5.7 ≦ A × B / 10000 ≦ 15.2.

Another aspect of the present invention has a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles and a biaxially stretched porous resin layer, and is laminated along the negative electrode mixture layer. The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the porous resin layer are provided. It is a non-aqueous electrolyte power storage element having a relationship with the air permeability C (seconds / 100 mL) of 3.6 ≦ A × C / 10000 ≦ 9.1.

According to the present invention, it is possible to provide a non-aqueous electrolyte power storage element excellent in output performance after a charge / discharge cycle and an effect of suppressing a minute short circuit between a positive electrode and a negative electrode.

It is a schematic sectional drawing which shows the negative electrode and the separator which concerns on one Embodiment of the non-aqueous electrolyte power storage element of this invention. It is an external perspective view which shows the non-aqueous electrolyte secondary battery which concerns on one Embodiment of this invention. It is a schematic diagram which shows the power storage device which was configured by gathering a plurality of non-aqueous electrolyte secondary batteries which concerns on one Embodiment of this invention. It is a graph which shows the output performance after the charge / discharge cycle of the Example which concerns on 1st Embodiment. It is a graph which shows the microshort circuit occurrence rate after the charge / discharge cycle of the Example which concerns on 1st Embodiment. It is a graph which shows the output performance after the charge / discharge cycle of the Example which concerns on 2nd Embodiment. It is a graph which shows the microshort circuit occurrence rate after the charge / discharge cycle of the Example which concerns on 2nd Embodiment.

One aspect of the present invention comprises a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and a separator having a porous resin layer laminated along the negative electrode mixture layer and uniaxially stretched. In addition, the peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the air permeability B of the porous resin layer ( The non-aqueous electrolyte power storage element has a relationship of 5.7 ≦ A × B / 10000 ≦ 15.2 (seconds / 100 mL).

A negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles and a uniaxially stretched porous resin layer laminated along the negative electrode mixture layer (hereinafter, also referred to as a uniaxially stretched porous resin layer). The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the porous resin layer. The non-aqueous electrolyte power storage element in which the air permeability B (seconds / 100 mL) satisfies the above relationship is excellent in the output performance after the charge / discharge cycle and the effect of suppressing minute short circuits between the positive electrode and the negative electrode. The reason why such an effect can be obtained is considered as follows, for example.
The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction is the peak intensity ratio of the horizontal plane to the vertical plane, and the negative electrode combination. It is an index of the orientation of the agent layer. When graphite particles are included as the negative electrode active material, the peak intensity ratio A is derived from the orientation of the basal plane formed of the benzene condensation plane of the graphite particles and the layered edge plane orthogonal to the basal plane. The graphite particles expand in a direction orthogonal to the basal plane as the charge carrier is inserted from the edge plane. The smaller the peak intensity ratio A, the more the basal surface is oriented in the direction perpendicular to the negative electrode base material (in-plane direction of the negative electrode). Therefore, the expansion of the negative electrode in the in-plane direction is increased, and the expansion of the negative electrode in the average thickness direction is suppressed. On the other hand, the peak intensity ratio A means that the larger the basal surface is oriented in the direction parallel to the negative electrode base material (in-plane direction of the negative electrode). Therefore, the expansion of the negative electrode in the average thickness direction is increased, and the expansion of the negative electrode in the in-plane direction is suppressed. Further, as the air permeability of the separator increases, the porosity of the separator tends to decrease and the tensile strength tends to increase.
The peak intensity ratio A in X-ray diffraction of the negative electrode mixture layer of the non-aqueous electrolyte power storage element including the negative electrode having the negative electrode mixture layer and the separator having the uniaxially stretched porous resin layer, and the porous material. In relation to the air permeability B (seconds / 100 mL) of the resin layer, when A × B / 10000 is 15.2 or less, expansion of the negative electrode in the average thickness direction is suppressed. In addition, the porosity of the separator tends to be small. Therefore, it is possible to suppress deterioration of the ionic conductivity of the non-aqueous electrolyte power storage element and the output performance after the charge / discharge cycle due to the tendency of the pores of the separator to be closed due to the expansion of the negative electrode in the average thickness direction. On the other hand, when the A × B / 10000 is 5.7 or more, the expansion of the negative electrode in the in-plane direction is suppressed. In addition, the tensile strength of the separator tends to increase. Therefore, it is possible to suppress the occurrence of a minute short circuit between the positive electrode and the negative electrode after the charge / discharge cycle due to the separator being easily torn due to the expansion of the negative electrode in the in-plane direction.
Therefore, when the non-aqueous electrolyte power storage element includes a separator having a uniaxially stretched porous resin layer, the average thickness of the negative electrode during charging is satisfied by satisfying 5.7 ≦ A × B / 10000 ≦ 15.2. An appropriate balance is achieved between the expansion in the longitudinal and in-plane directions and the porosity and tensile strength of the separator. As a result, it is presumed that the non-aqueous electrolyte power storage element is excellent in output performance after the charge / discharge cycle and in suppressing a minute short circuit between the positive electrode and the negative electrode. However, it is not limited to this reason.

Another aspect of the present invention is a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and a porous resin layer laminated along the negative electrode mixture layer and biaxially stretched (hereinafter referred to as a biaxially stretched porous resin layer). , Also referred to as a biaxially stretched porous resin layer), and the peak intensity ratio of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer (I (002) / I ( 110)) This is a non-aqueous electrolyte power storage element in which the relationship between A and the air permeability C (seconds / 100 mL) of the porous resin layer is 3.6 ≦ A × C / 10000 ≦ 9.1.

The negative electrode mixture comprises a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and a separator having a porous resin layer laminated along the negative electrode mixture layer and stretched biaxially. The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (102) plane in the X-ray diffraction of the layer and the air permeability C (seconds / 100 mL) of the porous resin layer are The non-aqueous electrolyte power storage element that satisfies the above relationship is excellent in output performance after a charge / discharge cycle and in suppressing a minute short circuit between a positive electrode and a negative electrode. The reason why such an effect can be obtained is considered as follows, for example.
The peak intensity ratio A in X-ray diffraction of the negative electrode mixture layer of the non-aqueous electrolyte power storage element including the negative electrode having the negative electrode mixture layer and the separator having the biaxially stretched porous resin layer, and the porous. When A × C / 10000 is 9.1 or less in relation to the air permeability C (seconds / 100 mL) of the quality resin layer, expansion of the negative electrode in the average thickness direction is suppressed. In addition, the porosity of the separator tends to be small. Therefore, it is possible to suppress deterioration of the ionic conductivity of the non-aqueous electrolyte power storage element and the output performance after the charge / discharge cycle due to the tendency of the pores of the separator to be closed due to the expansion of the negative electrode in the average thickness direction. On the other hand, when the A × C / 10000 is 3.6 or more, the expansion of the negative electrode in the in-plane direction is suppressed. In addition, the tensile strength of the separator tends to increase. Therefore, it is possible to suppress the occurrence of a minute short circuit between the positive electrode and the negative electrode after the charge / discharge cycle due to the separator being easily torn due to the expansion of the negative electrode in the in-plane direction.
Therefore, when the non-aqueous electrolyte power storage element includes a separator having a biaxially stretched porous resin layer, the average negative electrode during charging is satisfied by satisfying 3.6 ≦ A × C / 10000 ≦ 9.1. An appropriate balance is achieved between the expansion in the thickness direction and the in-plane direction and the porosity and tensile strength of the separator. As a result, it is presumed that the non-aqueous electrolyte power storage element is excellent in output performance after the charge / discharge cycle and in suppressing a minute short circuit between the positive electrode and the negative electrode. However, it is not limited to this reason.

The peak intensity ratio A is preferably 300 or more and 700 or less. When the range of the peak intensity ratio A is 300 or more and 700 or less, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

It is preferable that the graphite particles are solid particles. When the graphite particles are solid particles, the output performance after the charge / discharge cycle and the effect of suppressing minute short circuits between the positive electrode and the negative electrode can be further enhanced.

The average particle size of the graphite particles is preferably 2.0 μm or more and 6.0 μm or less. When the average particle size of the graphite particles is 2.0 μm or more and 6.0 μm or less, the output performance after the charge / discharge cycle and the effect of suppressing minute short circuits between the positive electrode and the negative electrode can be further enhanced.

The average aspect ratio of the graphite particles is preferably 1.0 or more and 5.0 or less. When the average aspect ratio of the graphite particles is in the above range, the output performance after the discharge cycle and the effect of suppressing minute short circuits between the positive electrode and the negative electrode can be further enhanced.

As used herein, the term "uniaxial stretching" refers to stretching the thermoplastic film in only one direction (for example, the longitudinal direction) in the process of stretching the thermoplastic film above the glass transition temperature and orienting the molecules. Means extending in two orthogonal directions (eg, longitudinal and width directions). Here, the longitudinal direction is parallel to the film conveying direction, and the width direction is a direction orthogonal to the longitudinal direction. The "air permeability", also called the Gale value, indicates the number of seconds required for 100 mL of air compressed at a constant pressure to pass through a circular porous resin layer having a diameter of 28.6 mm (area 642 mm ² ). It is a value measured according to JIS-P8117 (2009). By "solid" is meant that the inside of the particle is clogged and there are virtually no voids. More specifically, in the present specification, the term "solid" refers to the area of the entire particle in the cross section of the particle observed in the SEM image obtained by using a scanning electron microscope (SEM). This means that the area ratio excluding the area occupied by the voids in the particles is 95% or more. The "average aspect ratio" is the longest major axis T of the particles and the longest minor axis in the direction perpendicular to the major axis T in the cross section of the particles observed in the SEM image obtained by using a scanning electron microscope. It means the T / Y value which is the ratio with Y.

Hereinafter, the non-aqueous electrolyte power storage device according to the present invention will be described in detail with reference to the drawings.
<Non-aqueous electrolyte power storage element>
[First Embodiment]
The non-aqueous electrolyte power storage element according to the first embodiment of the present invention has a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. Hereinafter, a non-aqueous electrolyte secondary battery (particularly a lithium ion non-aqueous electrolyte secondary battery) will be described as an example of the non-aqueous electrolyte power storage element, but it is not intended to limit the application of the present invention. The positive electrode and the negative electrode usually form electrode bodies that are alternately superposed by stacking or winding through a separator. The electrode body is housed in a case, and the case is filled with a non-aqueous electrolyte. The non-aqueous electrolyte is interposed between the positive electrode and the negative electrode. Further, as the above case, a known metal case or the like which is usually used as a case of a non-aqueous electrolyte secondary battery can be used.

FIG. 1 is a schematic cross-sectional view showing a negative electrode and a separator according to an embodiment of the non-aqueous electrolyte power storage device. As shown in FIG. 1, the negative electrode 1 has a negative electrode base material 2 and a negative electrode mixture layer 3. The separator 4 has a uniaxially stretched porous resin layer. The separator 4 is laminated along the negative electrode mixture layer 3. When a negative electrode overcoat layer (not shown) is provided on the upper surface of the negative electrode mixture layer 3, the separator 4 is laminated on the upper surface of the negative electrode overcoat layer.

[Separator]
The separator of the non-aqueous electrolyte power storage element according to the first embodiment has a uniaxially stretched porous resin layer. As described above, "uniaxial stretching" is a process of stretching a thermoplastic film at a temperature equal to or higher than the glass transition temperature to orient the molecules, and stretching the thermoplastic film in only one direction (for example, in the longitudinal direction). Examples of the uniaxial stretching method include a dry uniaxial stretching method in which a thermoplastic crystalline polymer is heated and melted and then extruded and stretched into a film to peel off the intercrystal interface to form a porous structure. Further, a wet uniaxial stretching method may be used as the uniaxial stretching. In a preferred embodiment, the uniaxially stretched porous resin layer has a heat shrinkage rate of 5% or less (for example, 1% or more and 4% or less) in the transport direction (MD) of the film when dried at a temperature of 120 ° C. for 1 hour. Yes, and the heat shrinkage in the width direction (TD) orthogonal to the transport direction of the film can be 1% or less (for example, 0.5% or less, typically 0%).

Examples of the material constituting the porous resin layer include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacrylonitrile, polyphenylene sulfide, polyimide, and fluororesin from the viewpoint of strength. Among these, polyolefins such as polyethylene and polypropylene are preferable. Further, a copolymer of the monomers constituting these resins may be used.

The air permeability B of the uniaxially stretched porous resin layer is not particularly limited as long as A × B / 10000 is within a predetermined range with the peak intensity ratio A described later, but the lower limit thereof is not limited. , 50 seconds / 100 mL is preferable, and 90 seconds / 100 mL is more preferable. From the viewpoint of making it easier to exert the effect of this aspect, the air permeability B of the porous resin layer is more preferably 120 seconds / 100 mL or more, and particularly preferably 150 seconds / 100 mL or more. In some embodiments, the air permeability B may be, for example, 160 seconds / 100 mL or higher, typically 170 seconds / 100 mL or higher. On the other hand, as the upper limit of the air permeability B, 400 seconds / 100 mL is preferable, and 300 seconds / 100 mL is more preferable. From the viewpoint of making it easier to exert the effect of this aspect, the air permeability B of the porous resin layer is more preferably 250 seconds / 100 mL or less, and particularly preferably 220 seconds / 100 mL or less. In some embodiments, the air permeability B may be, for example, 200 seconds / 100 mL or less, typically 180 seconds / 100 mL or less. The technique disclosed herein is preferably carried out, for example, in an embodiment in which the air permeability B of the porous resin layer is 120 seconds / 100 mL or more and 220 seconds / 100 mL or less (preferably 150 seconds / 100 mL or more and 190 seconds / 100 mL or less). Can be done. By setting the air permeability B in the above range, it is possible to more effectively enhance the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode. When a separator having a heat-resistant layer formed on one surface or both sides of the porous resin layer is used, the air permeability of the porous resin layer excluding the heat-resistant layer is measured in the measurement of the air permeability. To do.

The average thickness of the porous resin layer is not particularly limited, but the lower limit thereof is preferably 3 μm, more preferably 5 μm, and even more preferably 7 μm. In some embodiments, the average thickness of the porous resin layer may be, for example, 8 μm or more, and typically 10 m or more. On the other hand, the upper limit of the average thickness of the porous resin layer is preferably 30 μm, more preferably 25 μm. In some embodiments, the average thickness of the porous resin layer may be, for example, 20 μm or less, and typically 15 μm or less. Sufficient insulating properties can be obtained by setting the average thickness of the porous resin layer to be equal to or higher than the above lower limit. By setting the average thickness of the porous resin layer to less than the above upper limit, it is possible to maintain a good energy density of the non-aqueous electrolyte power storage element.

The porosity of the porous resin layer is not particularly limited, but the lower limit thereof is preferably 20%, more preferably 30%. In some embodiments, the porosity of the porous resin layer may be, for example, 35% or higher, typically 40% or higher. On the other hand, the upper limit of the porosity is preferably 80%, more preferably 70%. In some embodiments, the porosity of the porous resin layer may be, for example, 65% or less, typically 60% or less (eg, 55% or less). By setting the porosity within the above range, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced. The porosity is the ratio of the void volume to the total volume of the porous resin layer, and is measured according to the "porosity" defined in JIS-L1096 (2010).

A heat-resistant layer may be provided between the separator and the positive electrode. This heat-resistant layer is a porous layer. Further, a separator having a heat resistant layer formed on one surface or both surfaces of the porous resin layer can also be used. The heat-resistant layer is usually composed of heat-resistant particles and a binder, and may contain other components.

The heat-resistant particles contained in the heat-resistant layer preferably have a weight loss of 5% or less at 500 ° C. in the atmosphere, and more preferably 5% or less in weight loss at 800 ° C. in the air. Inorganic compounds can be mentioned as materials whose weight loss is less than or equal to a predetermined value. As inorganic compounds, for example, oxides such as iron oxide, silicon oxide, aluminum oxide, titanium oxide, barium titanate, zirconium oxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide, aluminosilicate; magnesium hydroxide, water. Hydroxides such as calcium oxide and aluminum hydroxide; nitrides such as aluminum nitride and silicon nitride; carbonates such as calcium carbonate; sulfates such as barium sulfate; sparingly soluble ion crystals such as calcium fluoride and barium fluoride Covalently bonded crystals such as silicon and diamond; talc, montmorillonite, boehmite, zeolite, apatite, kaolin, mulite, spinel, olivine, sericite, bentonite, mica and other mineral resource-derived substances or man-made products thereof. .. As the inorganic compound, a simple substance or a complex of these substances may be used alone, or two or more kinds thereof may be mixed and used. Among these inorganic compounds, silicon oxide, aluminum oxide, or aluminosilicate is preferable.

[Negative electrode]
The negative electrode has a negative electrode mixture layer containing a negative electrode active material containing graphite particles.

A negative electrode overcoat layer having at least inorganic particles and a binder may be provided on the upper surface of the negative electrode mixture layer. By providing the negative electrode overcoat layer, effects such as improvement of ionic conductivity and reduction of the possibility of short circuit can be obtained.

(Negative electrode base material)
The negative electrode base material is a base material (current collector) having conductivity. As the material of the negative electrode base material, metals such as copper, nickel, stainless steel and nickel-plated steel or alloys thereof are used, and copper or a copper alloy is preferable. Further, examples of the form of the negative electrode base material include foil, a vapor-deposited film, and the like, and foil is preferable from the viewpoint of cost. That is, copper foil is preferable as the negative electrode base material. Examples of the copper foil include rolled copper foil and electrolytic copper foil. Incidentally, to have a "conductive" means that the volume resistivity is measured according to JIS-H0505 (1975) is not more than 1 × 10 ⁷ Ω · cm, and "non-conductive" are means that the volume resistivity is 1 × 10 ⁷ Ω · cm greater.

The upper limit of the average thickness of the negative electrode base material may be, for example, 30 μm, but 20 μm is preferable, and 10 μm is more preferable. By setting the average thickness of the negative electrode base material to the above upper limit or less, the energy density of the non-aqueous electrolyte power storage element can be further increased. On the other hand, the lower limit of this average thickness may be, for example, 1 μm or 5 μm. The average thickness means the average value of the thickness measured at 10 arbitrarily selected places.

[Negative electrode mixture layer]
The negative electrode mixture layer is laminated directly or via an intermediate layer along at least one surface of the negative electrode base material. The negative electrode mixture layer is formed from a so-called negative electrode mixture containing a negative electrode active material. The negative electrode mixture contains optional components such as a conductive agent, a binder, a thickener, and a filler, if necessary.

As the negative electrode active material, a material capable of occluding and releasing lithium ions is usually used. The non-aqueous electrolyte power storage element contains graphite particles as a negative electrode active material.

The average thickness (single-sided thickness) of the negative electrode mixture layer is not particularly limited. The lower limit of the average thickness of the negative electrode mixture layer is preferably 30 μm, more preferably 50 μm, further preferably 60 μm, and particularly preferably 70 μm. In some embodiments, the average thickness of the negative electrode mixture layer may be, for example, 80 μm or more, and typically 85 μm or more. On the other hand, the upper limit of the average thickness of the negative electrode mixture layer is preferably 200 μm, more preferably 150 μm, further preferably 130 μm, and particularly preferably 120 μm. In some embodiments, the average thickness of the negative electrode mixture layer may be, for example, 110 μm or less, and typically 100 μm or less.

The porosity of the negative electrode mixture layer is not particularly limited, but is preferably about 50% or less (for example, 40% or less). By setting the porosity of the negative electrode to 50% or less, the energy density of the non-aqueous electrolyte power storage element can be further increased. The porosity of the negative electrode is preferably 20% or more. The "porousness" of the negative electrode is a volume-based value, and the pore volume (mL) and bulk volume (mL) of the negative electrode are measured, and the formula of porosity = pore volume × 100 / bulk volume is used. Calculate the porosity (%).

The peak intensity ratio (I (002) / I (110)) A of the surface (002) to the surface (002) in the X-ray diffraction of the negative electrode mixture layer of the non-aqueous electrolyte storage element of the first embodiment, and the porosity. The relationship between the air permeability B (seconds / 100 mL) of the quality resin layer is 5.7 ≦ A × B / 10000 ≦ 15.2. The peak intensity ratio A in X-ray diffraction of the negative electrode mixture layer of the non-aqueous electrolyte power storage element including the negative electrode having the negative electrode mixture layer and the separator having the uniaxially stretched porous resin layer, and the porous material. In relation to the air permeability B (seconds / 100 mL) of the resin layer, when A × B / 10000 is 15.2 or less, expansion of the negative electrode in the average thickness direction is suppressed. Further, the porosity of the separator tends to be small, and the deterioration of the ionic conductivity of the non-aqueous electrolyte power storage element and the output performance after the charge / discharge cycle due to the tendency of the pores of the separator to be closed can be suppressed. On the other hand, when the A × B / 10000 is 5.7 or more, the expansion of the negative electrode in the in-plane direction is suppressed. Further, the tensile strength of the separator tends to increase, and the occurrence of a minute short circuit between the positive electrode and the negative electrode after the charge / discharge cycle due to the tendency of the separator to tear can be suppressed. Therefore, when the non-aqueous electrolyte power storage element includes a separator having a uniaxially stretched porous resin layer, the average thickness of the negative electrode during charging is satisfied by satisfying 5.7 ≦ A × B / 10000 ≦ 15.2. An appropriate balance is achieved between the expansion in the longitudinal and in-plane directions and the porosity and tensile strength of the separator. As a result, it is presumed that the non-aqueous electrolyte power storage element is excellent in output performance after the charge / discharge cycle and in suppressing a minute short circuit between the positive electrode and the negative electrode.

From the viewpoint of suppressing a decrease in output performance after the charge / discharge cycle, the A × B / 10000 is preferably 15.0 or less, more preferably 14.5 or less, still more preferably 14.0 or less. For example, the above A × B / 10000 may be, for example, 13.5 or less, and typically 13.0 or less. Further, from the viewpoint of better suppressing micro short circuits after the charge / discharge cycle, the A × B / 10000 is preferably 6.0 or more, more preferably 6.2 or more, still more preferably 6.5 or more. is there. For example, the above A × B / 10000 may be, for example, 7.0 or more, and typically 8.0 or more. In the technique disclosed herein, for example, the relationship between the peak intensity ratio (I (002) / I (110)) A and the air permeability B (seconds / 100 mL) of the porous resin layer is 5.7 ≦ A. It can be preferably carried out in an embodiment of × B / 10000 ≦ 15.2 (preferably 5.7 ≦ A × B / 10000 ≦ 13.5).

The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer is between the air permeability B of the porous resin layer. As long as A × B / 10000 is within the above-mentioned predetermined range, there is no particular limitation, but as the lower limit thereof, 100 is preferable, and 200 is more preferable. From the viewpoint of making it easier to exert the effect of this aspect, the peak intensity ratio A is more preferably 250 or more, and particularly preferably 300 or more. In some embodiments, the peak intensity ratio A may be, for example, 350 or greater, and typically 450 or greater. On the other hand, as the upper limit of the peak intensity ratio A, 1200 is preferable, and 1000 is more preferable. From the viewpoint of making it easier to exert the effect of this aspect, the peak intensity ratio A is more preferably 800 or less, and particularly preferably 700 or less. In some embodiments, the peak intensity ratio A may be, for example, 650 or less, typically 550 or less. The technique disclosed herein can be preferably carried out, for example, in a mode in which the peak intensity ratio A is 250 or more and 800 or less (preferably 300 or more and 700 or less). By setting the peak intensity ratio A in the above range, the negative electrode has an appropriate orientation, so that the expansion of the entire negative electrode is suppressed. Therefore, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

The peak intensity ratio A can be adjusted, for example, by changing the type and properties of the graphite particles contained in the negative electrode mixture layer. That is, the peak intensity ratio A can be adjusted to the above-mentioned suitable range disclosed herein by appropriately selecting the type and properties of the graphite particles. Another method for adjusting the peak intensity ratio A to the above-mentioned suitable range is to change the pressure when the negative electrode mixture layer is pressed in the average thickness direction in the negative electrode manufacturing step described later, for the negative electrode mixture layer. Methods such as changing the thickness and density, applying a magnetic field to the graphite particles in the negative electrode mixture layer to orient them in a predetermined direction can be adopted. The method for controlling the peak intensity ratio A can be used alone or in combination.

(Graphite particles)
“Graphite” means that the average lattice spacing d (002) of the (002) plane measured by the X-ray diffraction method before charging / discharging or in the discharged state is less than 0.340 nm (typically 0.330 nm or more and 0. It is a carbon substance (less than 340 nm). Here, the "discharged state" refers to a state in which the open circuit voltage is 0.7 V or more in a unipolar battery using a negative electrode containing graphite particles as a negative electrode active material as a working electrode and metal Li as a counter electrode. Since the potential of the metal Li counter electrode in the open circuit state is substantially equal to the oxidation-reduction potential of Li, the open circuit voltage in the single-pole battery is substantially equal to the potential of the negative electrode containing graphite particles with respect to the oxidation-reduction potential of Li. .. That is, the fact that the open circuit voltage in the single-pole battery is 0.7 V or more means that lithium ions that can be stored and discharged are sufficiently released from the graphite particles, which are the negative electrode active materials, as the battery is charged and discharged. .. The type and properties of the graphite particles are not particularly limited as long as the peak intensity ratio A of the negative electrode mixture layer satisfies the above relationship with the air permeability of the porous resin layer. For example, the graphite particles can be either artificial graphite particles or natural graphite particles. Of these, artificial graphite particles are preferable. The surface of these graphite particles may be coated with amorphous carbon. Such graphite particles may be flat scaly graphite particles, or spheroidized graphite particles obtained by spheroidizing the scaly graphite. In a preferred embodiment, the graphite particles are solid graphite particles. The solid graphite particles are suitable from the viewpoint that the peak intensity ratio A of the negative electrode mixture layer can be appropriately adjusted within the above-mentioned suitable range. Further, since the graphite particles are solid particles, the density in the graphite particles is uniform and current concentration is unlikely to occur, so that uneven expansion of the negative electrode can be suppressed. Therefore, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

<Solid graphite particles>
The solid graphite particles mean graphite particles that are clogged inside the particles and have substantially no voids. As described above, in the present specification, the solid graphite particles are voids in the particles with respect to the total area of the particles in the cross section of the particles observed in the SEM image obtained by using a scanning electron microscope. It means graphite particles having an area ratio of 95% or more excluding the area occupied by. The area ratio can be preferably 96% or more, more preferably 97% or more. The area ratio can be determined as follows.
(1) Preparation of sample for measurement The powder of graphite particles to be measured is fixed with a thermosetting resin. For graphite particles fixed with resin, a cross section is exposed by using a cross section polisher to prepare a sample for measurement.
(2) Acquisition of SEM image JSM-7001F (manufactured by JEOL Ltd.) is used as a scanning electron microscope to acquire the SEM image. The condition for acquiring the SEM image is to observe the secondary electron image. The accelerating voltage is 15 kV. The observation magnification is set so that the number of graphite particles appearing in one field of view is 3 or more and 15 or less. The obtained SEM image is saved as an image file. In addition, various conditions such as spot diameter, working distance, irradiation current, brightness, focus, etc. are appropriately set so that the outline of the graphite particles becomes clear.
(3) Cutout of contour of graphite particles Using the image cropping function of the image editing software Adobe Photoshop Elements 11, the contour of graphite particles is cut out from the acquired SEM image. This contour cropping is performed by selecting the outside of the contour of the active material particles using the quick selection tool and editing the non-graphite particles to a black background. Then, the images of all the graphite particles whose contours can be cut out are subjected to binarization processing. At this time, if the number of graphite particles whose contours could be cut out was less than 3, the SEM image was acquired again, and the graphite particles were formed until the number of graphite particles whose contours could be cut out became 3 or more. Cut out the contour.
(4) Binarization processing For the image of the first graphite particles among the cut out graphite particles, use the image analysis software PopImaging 6.00 and set the threshold value to a concentration 20% smaller than the concentration that maximizes the intensity. And perform binarization processing. By calculating the area on the low concentration side by the binarization process, it is determined as "area S1 excluding the area occupied by the voids in the particles".
Then, the same image of the first graphite particles as before is subjected to a binarization process with a density of 10 as a threshold value. The outer edge of the graphite particles is determined by the binarization treatment, and the area inside the outer edge is calculated to obtain "the total area S0 of the particles".
By calculating S1 with respect to S0 (S1 / S0) using the calculated S1 and S0, the area of the first graphite particle excluding the area occupied by the voids in the particle with respect to the total area of the particle. Rate R1 ”is calculated.
The image of the second and subsequent graphite particles among the cut out graphite particles is also subjected to the above binarization treatment to calculate the area S1 and the area S0, respectively. Based on the calculated areas S1 and S0, the area ratio R2, the area ratio R3, ... Of each graphite particle is calculated.
(5) Determination of area ratio By calculating the average value of all area ratio R1, area ratio R2, area ratio R3, ... Calculated by the binarization process, "inside the particle with respect to the total area of the particle""Area ratio of graphite particles excluding the area occupied by voids" is determined.

The average lattice spacing d (002) of the (002) plane measured by the X-ray diffraction method of the solid graphite particles is preferably less than 0.338 nm. The average lattice spacing d (002) of the solid graphite particles is preferably 0.335 nm or more. The spherical solid graphite particles preferably have a shape close to a true sphere, but may be elliptical, oval, or the like, and may have irregularities on the surface. The solid graphite particles may include particles in which a plurality of solid graphite particles are agglomerated.

The true density of the solid graphite particles is preferably 2.1 g / cm ³ or more. By using the solid graphite particles having such a high true density, the energy density of the non-aqueous electrolyte power storage element can be further increased. On the other hand, the upper limit of the true density of the solid graphite particles is, for example, 2.5 g / cm ³ . The true density is measured by the gas volumetric method using a pycnometer using helium gas.

The average particle size of the graphite particles disclosed here is not particularly limited, but the lower limit thereof is preferably 0.5 μm, more preferably 1.0 μm. For example, the average particle size of the graphite particles may be 1.5 μm or more, and typically 2.0 μm or more (for example, 2.5 μm or more). On the other hand, the upper limit of the average particle size of the graphite particles is preferably 10.0 μm, more preferably 8.0 μm. In some embodiments, the average particle size of the graphite particles may be 6.0 μm or less, typically 4.0 μm or less (eg 3.6 μm or less). The technique disclosed herein can be preferably carried out, for example, in an embodiment in which the average particle size of the graphite particles is 1.0 μm or more and 6.0 μm or less (preferably 2.0 μm or more and 3.4 μm or less). Graphite particles having the average particle size are suitable from the viewpoint that the peak intensity ratio A of the negative electrode mixture layer can be appropriately adjusted within the suitable range. Further, when the average particle size of the graphite particles is in the above range, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

The average particle diameter is a value indicated by the median diameter. The “median diameter” means a value (D50) at which the volume-based integrated distribution calculated in accordance with JIS-Z8819-2 (2001) is 50%. Specifically, the measured value can be obtained by the following method. A laser diffraction type particle size distribution measuring device (“SALD-2200” manufactured by Shimadzu Corporation) is used as the measuring device, and a Wing SALD-2200 is used as the measurement control software. A scattering type measurement mode is adopted, and a wet cell in which a dispersion liquid in which a measurement sample is dispersed in a dispersion solvent circulates is irradiated with laser light to obtain a scattered light distribution from the measurement sample. Then, the scattered light distribution is approximated by a lognormal distribution, and the particle diameter corresponding to a cumulative degree of 50% is defined as the median diameter (D50).

The average aspect ratio of the graphite particles is not particularly limited, but the lower limit thereof is 1.0, preferably 1.2. As the graphite particles in the negative electrode mixture layer of the above aspect, graphite particles having an average aspect ratio of 1.4 or more can be preferably adopted. On the other hand, the upper limit of the average aspect ratio of the graphite particles is 5.0, preferably 4.0. For example, graphite particles having an average aspect ratio of 3.0 or less are preferable, those having an average aspect ratio of 2.5 or less are more preferable, and those having an average aspect ratio of 2.0 or less (for example, 1.8 or less) are particularly preferable. The graphite particles having the average aspect ratio are suitable from the viewpoint that the peak intensity ratio A of the negative electrode mixture layer can be appropriately adjusted within the suitable range. Further, when the average aspect ratio of the graphite particles is in the above range, since the graphite particles are close to a sphere, current concentration is unlikely to occur, so that uneven expansion of the negative electrode can be suppressed. Therefore, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

As described above, the "average aspect ratio" is the longest major axis T of the particles and the direction perpendicular to the major axis T in the cross section of the particles observed in the SEM image obtained by using a scanning electron microscope. It means the T / Y value which is the ratio with the shortest diameter Y which is the longest. The average aspect ratio can be determined as follows.
(1) Preparation of measurement sample A measurement sample with an exposed cross section used for determining the area ratio described above is used.
(2) Acquisition of SEM image JSM-7001F (manufactured by JEOL Ltd.) is used as a scanning electron microscope to acquire the SEM image. The condition for acquiring the SEM image is to observe the secondary electron image. The accelerating voltage is 15 kV. The observation magnification is set so that the number of graphite particles appearing in one field of view is 100 or more and 1000 or less. The obtained SEM image is saved as an image file. In addition, various conditions such as spot diameter, working distance, irradiation current, brightness, focus, etc. are appropriately set so that the outline of the graphite particles becomes clear.
(3) Determination of average aspect ratio 100 graphite particles are randomly selected from the acquired SEM image, and for each of them, the longest major axis T of the graphite particles and the longest minor axis Y in the direction perpendicular to the major axis T. Is measured and the T / Y value is calculated. The average aspect ratio of the graphite particles is determined by calculating the average value of all the calculated T / Y values.

The average value (average major axis) of the longest major axis T of the graphite particles is not particularly limited, but is generally 1.0 μm or more. The average major axis of the graphite particles is preferably 1.2 μm or more, more preferably 1.5 μm or more, and further preferably 1.8 μm or more. In some embodiments, the average major axis may be, for example, 2.0 μm or greater, typically 2.5 μm or greater (eg, 3.0 μm or greater). The average major axis of the graphite particles is approximately 15 μm or less, preferably 10 μm or less, and more preferably 8.0 μm or less (for example, 6.0 μm or less). The technique disclosed herein can be preferably carried out, for example, in an embodiment in which the average major axis of the graphite particles is 2.5 μm or more and 8.0 μm or less.

The average value (average minor axis) of the minor axis Y, which is the longest in the direction perpendicular to the major axis T of the graphite particles, is not particularly limited, but is generally 0.2 μm or more. The average minor axis of the graphite particles is preferably 0.3 μm or more, more preferably 0.5 μm or more, and further preferably 0.8 μm or more. The average minor axis of the graphite particles is approximately 10 μm or less, preferably 8 μm or less, and more preferably 6.0 μm or less (for example, 4.0 μm or less). In some embodiments, the average minor axis may be, for example, 3.0 μm or less, typically 2.5 μm or less (eg, 2.0 μm or less). The technique disclosed herein can be preferably carried out, for example, in an embodiment in which the average minor axis of the graphite particles is 0.5 μm or more and less than 2.5 μm.

(Other negative electrode active materials)
The negative electrode mixture layer may contain a negative electrode active material other than the above-mentioned graphite particles as long as the effect of the present invention is not impaired. Examples of such other negative electrode active materials include carbon materials such as non-graphitizable carbon particles and easily graphitizable carbon particles; metals Li; metals or semi-metals such as Si and Sn; Si oxides, Ti oxidation. Materials, metal oxides such as Sn oxides or semi-metal oxides; titanium-containing oxides such as Li ₄ Ti ₅ O ₁₂ , LiTIO _2, TiNb ₂ O ₇ ; polyphosphate compounds; silicon carbide and the like.

The technique disclosed herein can be preferably carried out in an embodiment in which the proportion of the graphite particles in the total mass of the negative electrode active material contained in the negative electrode mixture layer is larger than 50% by mass. The lower limit of the content of the graphite particles with respect to the total mass of the negative electrode active material is preferably 60% by mass, more preferably 70% by mass. For example, the content of the graphite particles with respect to the total mass of the negative electrode active material can be, for example, 80% by mass or more, typically 90% by mass or more. By setting the content of graphite particles to the above lower limit or more, the charge / discharge efficiency can be further improved. On the other hand, the upper limit of the content of the graphite particles with respect to the total mass of the negative electrode active material may be, for example, 100% by mass.

The content of the negative electrode active material in the negative electrode mixture layer is not particularly limited, but the lower limit thereof is preferably 50% by mass, more preferably 80% by mass, and even more preferably 90% by mass. On the other hand, as the upper limit of this content, 99% by mass is preferable, and 98% by mass is more preferable.

(Other optional ingredients)
The graphite particles also have conductivity, but the negative electrode mixture layer may contain a conductive agent. Examples of the conductive agent include carbon materials other than carbon materials such as metals, conductive ceramics, graphite such as acetylene black, and non-graphitizable carbon and easily graphitizable carbon particles. When a conductive agent is used in the negative electrode mixture layer, the ratio of the conductive agent to the entire negative electrode mixture layer can be about 8.0% by mass or less, and usually about 5.0% by mass or less (for example, 1). It is preferably 0.0% by mass or less). The technique disclosed herein can be preferably carried out in a manner in which the negative electrode mixture layer does not contain the above-mentioned conductive agent.

Examples of the binder include elastomers such as ethylene-propylene-diene rubber (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), and fluororubber; fluororesin (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.). , Polyplastic resins other than elastomers such as polyethylene, polypropylene and polyimide; polysaccharide polymers and the like. When a binder is used in the negative electrode mixture layer, the proportion of the binder in the entire negative electrode mixture layer can be about 0.50% by mass to 15% by mass, and usually about 1.0% by mass to 10% by mass. % (For example, 1.5% by mass to 5.0% by mass) is preferable.

Examples of the thickener include polysaccharide polymers such as carboxymethyl cellulose (CMC) and methyl cellulose. When the thickener has a functional group that reacts with lithium, it is preferable to deactivate the functional group by methylation or the like in advance. When a thickener is used in the negative electrode mixture layer, the ratio of the thickener to the entire negative electrode mixture layer can be about 0.10% by mass to 10% by mass, and usually about 0.20% by mass. It is preferably% to 5.0% by mass (for example, 0.30% by mass to 1.0% by mass).

The filler is not particularly limited. The main components of the filler are polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, alumina, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide and aluminosilicate, magnesium hydroxide and calcium hydroxide. , Hydroxides such as aluminum hydroxide, carbonates such as calcium carbonate, sparingly soluble ionic crystals such as calcium fluoride, barium fluoride, barium sulfate, nitrides such as aluminum nitride and silicon nitride, talc, montmorillonite, boehmite , Zeolites, Apatite, Kaolin, Murite, Spinel, Olivin, Cerisite, Bentnite, Mica and other mineral resource-derived substances, or man-made products thereof. When a filler is used in the negative electrode mixture layer, the proportion of the filler in the entire negative electrode mixture layer can be about 8.0% by mass or less, and usually about 5.0% by mass or less (for example, 1.0). It is preferably mass% or less). The technique disclosed herein can be preferably carried out in a manner in which the negative electrode mixture layer does not contain the above filler.

(Middle layer)
The intermediate layer is a coating layer on the surface of the negative electrode base material, and contains conductive particles such as carbon particles to reduce the contact resistance between the negative electrode base material and the negative electrode mixture layer. The composition of the intermediate layer is not particularly limited, and can be formed by, for example, a composition containing a resin binder and conductive particles. The technique disclosed herein can be preferably carried out in an embodiment without the intermediate layer.

[Positive electrode]
The positive electrode has a positive electrode base material and a positive electrode mixture layer. The positive electrode mixture layer contains a positive electrode active material. The positive electrode mixture layer is laminated directly or via an intermediate layer along at least one surface of the positive electrode base material.

The positive electrode base material has conductivity. As the material of the base material, metals such as aluminum, titanium, tantalum, and stainless steel or alloys thereof are used. Among these, aluminum and aluminum alloys are preferable from the viewpoint of balance of potential resistance, high conductivity and cost. Further, examples of the form of the positive electrode base material include a foil and a vapor-deposited film, and the foil is preferable from the viewpoint of cost. That is, an aluminum foil is preferable as the positive electrode base material. Examples of aluminum or aluminum alloy include A1085 and A3003 specified in JIS-H4000 (2014).

The positive electrode mixture layer is formed from a so-called positive electrode mixture containing a positive electrode active material. Further, the positive electrode mixture forming the positive electrode mixture layer contains optional components such as a conductive agent, a binder, a thickener, and a filler, if necessary.

Examples of the positive electrode active material include a lithium transition metal composite oxide having an α-NaFeO type ₂ crystal structure, a lithium transition metal oxide having a spinel type crystal structure, a polyanion compound, a chalcogen compound, sulfur and the like. Examples of the lithium transition metal composite oxide having an α-NaFeO type ₂ crystal structure include Li [Li _x Ni _1-x ] O ₂ (0 ≦ x <0.5) and Li [Li _x Ni _γ Co _{(1-). x-γ)} ] O ₂ (0 ≦ x <0.5, 0 <γ <1), Li [Li _x Co _(1-x) ] O ₂ (0 ≦ x <0.5), Li [Li _x Ni _γ Mn _(1-x-γ) ] O ₂ (0 ≦ x <0.5, 0 <γ <1), Li [Li _x Ni _γ Mn _β Co _(1-x-γ-β ] O ₂ ( 0 ≦ x <0.5, 0 <γ, 0 <β, 0.5 <γ + β <1), Li [Li _x Ni _γ Co _β Al _(1-x-γ-β ] O ₂ (0 ≦ x < Examples thereof include 0.5, 0 <γ, 0 <β, 0.5 <γ + β <1). Examples of the lithium transition metal oxide having a spinel-type crystal structure include Li _x Mn ₂ O _4, Li _x Ni _γ Mn. Examples of the polyanion compound include _(2-γ) O ₄ , LiFePO _4, LiMnPO _4, LiNiPO _4, LiCoPO _4, Li ₃ V ₂ (PO ₄ ) _3, Li ₂ MnSiO _4, Li ₂ CoPO ₄ F and the like. Examples of the chalcogen compound include titanium disulfide, molybdenum disulfide, molybdenum dioxide, and the like. Even if the atom or polyanion in these materials is partially substituted with an atom or anion species composed of other elements. The surface of these materials may be coated with another material. In the positive electrode mixture layer, one of these compounds may be used alone, or two or more thereof may be mixed and used. The content of the positive electrode active material in the positive electrode mixture layer is not particularly limited, but the lower limit thereof is preferably 50% by mass, more preferably 80% by mass, still more preferably 90% by mass, while this content. As the upper limit, 99% by mass is preferable, and 98% by mass is more preferable.

The conductive agent is not particularly limited as long as it is a conductive material. Examples of such a conductive agent include carbonaceous materials, metals, conductive ceramics and the like. Examples of the carbonaceous material include graphitized carbon, non-graphitized carbon, graphene-based carbon and the like. Examples of non-graphitized carbon include carbon nanofibers, pitch-based carbon fibers, and carbon black. Examples of carbon black include furnace black, acetylene black, and ketjen black. Examples of graphene-based carbon include graphene, carbon nanotubes (CNT), and fullerenes. Examples of the shape of the conductive material include powder and fibrous. As the conductive agent, one of these materials may be used alone, or two or more of these materials may be mixed and used. Moreover, you may use these materials in combination. For example, a material in which carbon black and CNT are composited may be used. Among these, carbon black is preferable from the viewpoint of electron conductivity and coatability, and acetylene black is particularly preferable. When a conductive agent is used, the proportion of the conductive agent in the entire positive electrode mixture layer can be about 1.0% by mass to 20% by mass, and usually about 2.0% by mass to 15% by mass (for example). It is preferably 3.0% by mass to 6.0% by mass).

Examples of the binder include fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), thermoplastic resins such as polyethylene, polypropylene, polyacrylic, and polyimide; ethylene-propylene-diene rubber (EPDM), sulfonated. Elastomers such as EPDM, styrene-butadiene rubber (SBR), fluororubber; and thermoplastic polymers can be mentioned. When a binder is used, the proportion of the binder in the entire positive mixture layer can be about 0.50% by mass to 15% by mass, and usually about 1.0% by mass to 10% by mass (for example, 1. 5% by mass to 3.0% by mass) is preferable.

Examples of the thickener include polysaccharide polymers such as carboxymethyl cellulose (CMC) and methyl cellulose. When the thickener has a functional group that reacts with lithium, it is preferable to deactivate the functional group by methylation or the like in advance. When a thickener is used, the proportion of the thickener in the entire positive electrode mixture layer can be about 8% by mass or less, and usually about 5.0% by mass or less (for example, 1.0% by mass or less). ) Is preferable. The technique disclosed herein can be preferably carried out in a manner in which the positive electrode mixture layer does not contain the thickener.

The filler is not particularly limited. The main components of the filler are polyolefins such as polypropylene and polyethylene, inorganic oxides such as silicon dioxide, aluminum oxide, titanium dioxide, calcium oxide, strontium oxide, barium oxide, magnesium oxide and aluminosilicate, magnesium hydroxide and hydroxide. Hydroxides such as calcium and aluminum hydroxide, carbonates such as calcium carbonate, sparingly soluble ion crystals such as calcium fluoride, barium fluoride and barium sulfate, nitrides such as aluminum nitride and silicon nitride, talc and montmorillonite, Examples include mineral resource-derived substances such as boehmite, zeolite, apatite, kaolin, mulite, spinel, olivine, cericite, bentonite, and mica, or man-made products thereof. When a filler is used, the proportion of the filler in the entire positive electrode mixture layer can be about 8.0% by mass or less, and usually about 5.0% by mass or less (for example, 1.0% by mass or less). It is preferable to do so. The technique disclosed herein can be preferably carried out in a manner in which the positive electrode mixture layer does not contain the above filler.

The intermediate layer is a coating layer on the surface of the positive electrode base material, and contains conductive particles such as carbon particles to reduce the contact resistance between the positive electrode base material and the positive electrode mixture layer. Similar to the negative electrode, the structure of the intermediate layer is not particularly limited, and can be formed by, for example, a composition containing a resin binder and conductive particles. The technique disclosed herein can be preferably carried out in an embodiment without the intermediate layer.

[Non-aqueous electrolyte]
As the non-aqueous electrolyte, a known non-aqueous electrolyte usually used for a general non-aqueous electrolyte secondary battery (non-aqueous electrolyte storage element) can be used. The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte may be a solid electrolyte or the like.

As the non-aqueous solvent, a known non-aqueous solvent usually used as a non-aqueous solvent for a non-aqueous electrolyte for a general non-aqueous electrolyte power storage element can be used. Examples of the non-aqueous solvent include cyclic carbonates, chain carbonates, esters, ethers, amides, sulfones, lactones, nitriles and the like. Among these, it is preferable to use at least cyclic carbonate or chain carbonate, and it is more preferable to use cyclic carbonate and chain carbonate in combination. When the cyclic carbonate and the chain carbonate are used in combination, the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate: chain carbonate) is not particularly limited, but may be, for example, 5:95 to 50:50. preferable.

Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), and difluoroethylene. Examples thereof include carbonate (DFEC), styrene carbonate, catechol carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate, and among these, EC is preferable.

Examples of the chain carbonate include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diphenyl carbonate and the like, and among these, EMC is preferable.

As the electrolyte salt, a known electrolyte salt usually used as an electrolyte salt of a non-aqueous electrolyte for a general non-aqueous electrolyte power storage element can be used. Examples of the electrolyte salt include lithium salt, sodium salt, potassium salt, magnesium salt, onium salt and the like, but lithium salt is preferable.

Examples of the lithium salt include inorganic lithium salts such as LiPF ₆ , LiPO ₂ F ₂ , LiBF ₄ , LiClO ₄ , LiN (SO ₂ F) ₂ , LiSO ₃ CF ₃ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO). ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂ C ₂ F ₅ ) ₃ hydrogen is replaced with fluorine Examples thereof include a lithium salt having a sulfur group. Among these, an inorganic lithium salt is preferable, and LiPF ₆ is more preferable.

The lower limit of the content of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 mol / L, more preferably 0.3 mol / L, further preferably 0.5 mol / L, and particularly preferably 0.7 mol / L. .. On the other hand, the upper limit is not particularly limited, but is preferably 2.5 mol / L, more preferably 2.0 mol / L, and even more preferably 1.5 mol / L.

Other additives may be added to the non-aqueous electrolyte. Further, as the non-aqueous electrolyte, a room temperature molten salt, an ionic liquid, or the like can also be used.

According to the non-aqueous electrolyte power storage element according to the first embodiment, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode are excellent.

[Second Embodiment]
The non-aqueous electrolyte power storage element according to the second embodiment of the present invention is laminated with a negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and biaxially stretched along the negative electrode mixture layer. It is provided with a separator having a porous resin layer. The non-aqueous electrolyte storage element according to the second embodiment also has a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, like the non-aqueous electrolyte storage element according to the first embodiment. In the non-aqueous electrolyte power storage element according to the second embodiment, the same configuration as the non-aqueous electrolyte power storage element according to the first embodiment will not be described.

The peak intensity ratio (I (002) / I (110)) A of the surface (002) to the surface (002) in the X-ray diffraction of the negative electrode mixture layer of the non-aqueous electrolyte storage element of the second embodiment, and the porosity. The relationship between the air permeability C (seconds / 100 mL) of the quality resin layer is 3.6 ≦ A × C / 10000 ≦ 9.1. The peak intensity ratio A in X-ray diffraction of the negative electrode mixture layer of the non-aqueous electrolyte power storage element including the negative electrode having the negative electrode mixture layer and the separator having the biaxially stretched porous resin layer, and the porous. When A × C / 10000 is 9.1 or less in relation to the air permeability C (seconds / 100 mL) of the quality resin layer, expansion of the negative electrode in the average thickness direction is suppressed. Further, the porosity of the separator tends to be small, and the deterioration of the ionic conductivity of the non-aqueous electrolyte power storage element and the output performance after the charge / discharge cycle due to the tendency of the pores of the separator to be closed can be suppressed. On the other hand, when the A × C / 10000 is 3.6 or more, the expansion of the negative electrode in the in-plane direction is suppressed. In addition, the tensile strength of the separator tends to increase, and the occurrence of a minute short circuit between the positive electrode and the negative electrode after the charge / discharge cycle due to the separation becoming easy to tear can be suppressed. Therefore, when the non-aqueous electrolyte power storage element includes a separator having a biaxially stretched porous resin layer, the average negative electrode during charging is satisfied by satisfying 3.6 ≦ A × C / 10000 ≦ 9.1. An appropriate balance is achieved between the expansion in the thickness direction and the in-plane direction and the porosity and tensile strength of the separator. As a result, it is presumed that the non-aqueous electrolyte power storage element is excellent in output performance after the charge / discharge cycle and in suppressing a minute short circuit between the positive electrode and the negative electrode.

From the viewpoint of suppressing a decrease in output performance after the charge / discharge cycle, the A × C / 10000 is preferably 9.0 or less, more preferably 8.5 or less, still more preferably 8.0 or less. For example, the above A × B / 10000 may be, for example, 7.5 or less, and typically 7.0 or less. Further, from the viewpoint of suppressing a minute short circuit between the positive electrode and the negative electrode after the charge / discharge cycle, the A × C / 10000 is preferably 3.8 or more, more preferably 4.0 or more, still more preferably 4. 5 or more. For example, the above A × C / 10000 may be, for example, 5.0 or more, and typically 5.5 or more. In the technique disclosed herein, for example, the relationship between the peak intensity ratio (I (002) / I (110)) A and the air permeability C (seconds / 100 mL) of the porous resin layer is 3.6 ≦ A. It can be preferably carried out in an embodiment of × C / 10000 ≦ 9.1 (preferably 4.0 ≦ A × C / 10000 ≦ 8.5).

The separator of the non-aqueous electrolyte power storage element according to the second embodiment has a biaxially stretched porous resin layer. As described above, "biaxial stretching" refers to stretching a thermoplastic film in two orthogonal directions (for example, in the longitudinal direction and the width direction) in the process of stretching the thermoplastic film above the glass transition temperature and orienting the molecules. Examples of the biaxial stretching method include a wet biaxial stretching method in which a polymer and a plasticizer are heated and mixed, then extruded and stretched into a film, and finally the plasticizer is extracted with a solvent to form a porous structure. Moreover, you may use the dry uniaxial stretching method as biaxial stretching. In a preferred embodiment, the biaxially stretched porous resin layer has a heat shrinkage rate of 4% or less (for example, 1% or more and 3% or less) in the transport direction (MD) of the film when dried at a temperature of 120 ° C. for 1 hour. And the heat shrinkage rate in the width direction (TD) orthogonal to the transport direction of the film can be 4% or less (for example, 1% or more and 3% or less).

The average thickness of the porous resin layer is not particularly limited, but the lower limit thereof is preferably 2 μm, more preferably 4 μm, and even more preferably 6 μm. In some embodiments, the average thickness of the porous resin layer may be, for example, 7 μm or more, and typically 9 m or more. On the other hand, the upper limit of the average thickness of the porous resin layer is preferably 30 μm, more preferably 25 μm. In some embodiments, the average thickness of the porous resin layer may be, for example, 20 μm or less, typically 15 μm or less (eg, 12 μm or less). Sufficient insulating properties can be obtained by setting the average thickness of the porous resin layer to be equal to or higher than the above lower limit. By setting the average thickness of the porous resin layer to less than the above upper limit, it is possible to maintain a good energy density of the non-aqueous electrolyte power storage element.

The air permeability C of the biaxially stretched porous resin layer is not particularly limited as long as A × C / 10000 is within a predetermined range with the peak intensity ratio A, but the lower limit thereof is not limited. 10 seconds / 100 mL is preferable, and 30 seconds / 100 mL is more preferable. From the viewpoint of making it easier to exert the effect of this aspect, the air permeability C of the porous resin layer is more preferably 60 seconds / 100 mL or more, and particularly preferably 80 seconds / 100 mL or more. In some embodiments, the air permeability C may be, for example, 90 seconds / 100 mL or higher, typically 100 seconds / 100 mL or higher (eg 110 seconds / 100 mL or higher). On the other hand, as the upper limit of the air permeability, 300 seconds / 100 mL is preferable, and 200 seconds / 100 mL is more preferable. From the viewpoint of making it easier to exert the effect of this aspect, the air permeability C of the porous resin layer is more preferably 180 seconds / 100 mL or less, and particularly preferably 150 seconds / 100 mL or less. In some embodiments, the air permeability C may be, for example, 130 seconds / 100 mL or less, typically 120 seconds / 100 mL or less. The technique disclosed herein can be preferably carried out, for example, in an embodiment in which the air permeability C of the porous resin layer is 60 seconds / 100 mL or more and 180 mL or less (preferably 90 seconds / 100 mL or more and 130 mL or less). By setting the air permeability C in the above range, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be more effectively enhanced.

The porosity of the porous resin layer is not particularly limited, but the lower limit thereof is preferably 20%, more preferably 30%. In some embodiments, the porosity of the porous resin layer may be, for example, 35% or higher, typically 40% or higher. On the other hand, the upper limit of the porosity is preferably 80%, more preferably 70%. In some embodiments, the porosity of the porous resin layer may be, for example, 65% or less, typically 60% or less (eg, 55% or less). By setting the porosity within the above range, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

According to the non-aqueous electrolyte power storage element according to the second embodiment, even when a separator having a biaxially stretched porous resin layer is used, the output performance after the charge / discharge cycle and the suppression against a minute short circuit between the positive electrode and the negative electrode are suppressed. Excellent effect.

[Specific configuration of non-aqueous electrolyte power storage element]
Next, a specific configuration example of the non-aqueous electrolyte power storage device according to the embodiment of the present invention will be described. FIG. 2 shows a schematic view of a rectangular non-aqueous electrolyte secondary battery 10 which is an example of the non-aqueous electrolyte power storage element of the present invention. The figure is a perspective view of the inside of the container. In the non-aqueous electrolyte secondary battery 10 shown in FIG. 2, the electrode body 12 is housed in the battery container 13 (case). The electrode body 12 is formed by winding a positive electrode having a positive electrode active material and a negative electrode having a negative electrode active material through a separator. The positive electrode is electrically connected to the positive electrode terminal 14 via the positive electrode lead 14', and the negative electrode is electrically connected to the negative electrode terminal 15 via the negative electrode lead 15'. As the negative electrode, the negative electrode according to the embodiment of the present invention is used. Further, a non-aqueous electrolyte (electrolyte solution) is injected into the battery container 13 from an injection hole (not shown).

[Manufacturing method of non-aqueous electrolyte power storage element]
The method for producing a non-aqueous electrolyte power storage element according to an embodiment of the present invention is to prepare a negative electrode containing a negative electrode active material containing graphite particles, and to combine a separator having a uniaxially stretched porous resin layer with the above negative electrode. It is provided to be laminated along the agent layer. When a separator having the uniaxially stretched porous resin layer is used, the peak intensity ratio of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer (I (002) / I (110)). The relationship between A and the air permeability B (seconds / 100 mL) of the porous resin layer is 5.7 ≦ A × B / 10000 ≦ 15.2. The method for manufacturing the non-aqueous electrolyte power storage element is to prepare a positive electrode having a positive electrode mixture layer containing a positive electrode active material, and to prepare the positive electrode mixture on the surface side of the separator opposite to the negative electrode mixture layer. It is preferable that the layers are further provided.

Further, the method for manufacturing a non-aqueous electrolyte power storage element according to another embodiment of the present invention is to prepare a negative electrode containing a negative electrode active material containing graphite particles, and a separator having a biaxially stretched porous resin layer. Is provided to be laminated along the negative electrode mixture layer. When a separator having the biaxially stretched porous resin layer is used, the peak intensity ratio (I (002) / I (110) of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer is used. )) The relationship between A and the air permeability C (seconds / 100 mL) of the porous resin layer is 3.6 ≦ A × C / 10000 ≦ 9.1.

In the step of producing the negative electrode, for example, by applying a negative electrode mixture to the negative electrode base material, a negative electrode mixture layer containing a negative electrode active material containing graphite particles is laminated along at least one surface of the negative electrode base material. .. Specifically, for example, the negative electrode mixture layer is laminated by applying the negative electrode mixture to the negative electrode base material and drying it. After the drying, pressing may be performed in the direction of the average thickness of the negative electrode mixture layer in order to improve the adhesion between the negative electrode mixture layer and the negative electrode base material. In a preferred embodiment, the negative electrode mixture layer is not pressed before laminating the negative electrode and the positive electrode. That is, the negative electrode mixture layer is arranged on the negative electrode base material in an unpressed state. The term "unpressed" as used herein means that a pressure (linear pressure) of 10 kgf / mm or more is applied to the negative electrode mixture layer by a device intended to apply pressure to a work such as a roll press machine at the time of manufacturing. It means that the process has not been performed. That is, the "unpressed" includes those in which a slight pressure is applied to the negative electrode mixture layer in another step such as winding the negative electrode. Further, "unpressed" includes a step of applying a pressure (linear pressure) of less than 10 kgf / mm. By arranging the negative electrode mixture layer on the negative electrode base material in an unpressed state in this way, the peak intensity ratio A of the negative electrode mixture layer can be appropriately adjusted to the above-mentioned suitable range. Further, since the negative electrode mixture layer arranged in the unpressed state has no or small pressure applied to the negative electrode mixture layer, the graphite particles themselves have little residual stress and the residual stress is released. Non-uniform expansion of the negative electrode can be suppressed. Therefore, the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode can be further enhanced.

The fact that the negative electrode mixture layer is "unpressed" means that the negative electrode mixture layer is not arranged with respect to the surface roughness R1 of the negative electrode base material in the area where the negative electrode mixture layer is arranged. It can be grasped from R2 / R1 which is the ratio of the surface roughness R2 of the negative electrode base material in the so-called exposed region of the negative electrode base material). That is, as the pressure applied to the negative electrode base material, the surface roughness R1 of the region where the negative electrode mixture layer is formed increases, so that R2 / R1 decreases. In other words, when no pressure is applied to the negative electrode mixture layer, the surface roughness of the negative electrode base material is defined in the region where the negative electrode mixture layer is arranged and the region where the negative electrode mixture layer is not arranged. Is almost the same value. That is, R2 / R1 approaches 1. The negative electrode in which the negative electrode mixture layer is arranged on the negative electrode base material in the unpressed state may have R2 / R1 of, for example, 0.90 or more (typically 0.95 or more).

The negative electrode mixture may be a negative electrode mixture paste containing a dispersion medium in addition to the above-mentioned optional components. As the dispersion medium, for example, an aqueous solvent such as water or a mixed solvent mainly composed of water; or an organic solvent such as N-methyl-2-pyrrolidone or toluene can be used.

Next, in the step of laminating the separator, the separator having the uniaxially stretched or biaxially stretched porous resin layer is laminated along the negative electrode mixture layer.

In the step of producing the positive electrode, for example, the positive electrode mixture layer containing the positive electrode active material can be laminated along at least one surface of the positive electrode base material by applying the positive electrode mixture to the positive electrode base material. Specifically, for example, the positive electrode mixture layer is laminated by applying the positive electrode mixture to the positive electrode base material and drying it. After the drying, pressing may be performed in the average thickness direction of the positive electrode mixture layer in order to improve the adhesion between the positive electrode mixture layer and the positive electrode base material. Further, the positive electrode mixture may be a positive electrode mixture paste in which a dispersion medium is further contained in addition to the above-mentioned optional components. The dispersion medium can be arbitrarily selected from those exemplified in the negative electrode mixture.

In addition to the above steps, for example, a step of accommodating the negative electrode, the separator, and an electrode body in which the positive electrode is laminated in a case and a step of injecting the non-aqueous electrolyte into the case are provided. The above injection can be performed by a known method. After the injection, a non-aqueous electrolyte power storage element can be obtained by sealing the injection port. Details of each element constituting the non-aqueous electrolyte power storage element obtained by the production method are as described above.

[Other Embodiments]
The non-aqueous electrolyte power storage element of the present invention is not limited to the above embodiment.

In the above embodiment, the non-aqueous electrolyte storage element has been described mainly in the form of a non-aqueous electrolyte secondary battery, but other non-aqueous electrolyte storage elements may be used. Examples of other non-aqueous electrolyte power storage elements include capacitors (electric double layer capacitors, lithium ion capacitors) and the like. Examples of the non-aqueous electrolyte secondary battery include a lithium ion non-aqueous electrolyte secondary battery.

The present invention can also be realized as a power storage device including a plurality of the above-mentioned non-aqueous electrolyte power storage elements. Further, a power storage unit can be configured by using one or more non-aqueous electrolyte power storage elements of the present invention, and a power storage device can be further configured by using this power storage unit. In this case, the technique of the present invention may be applied to at least one non-aqueous electrolyte power storage element included in the power storage unit or the power storage device.

FIG. 3 shows an example of a power storage device 30 in which a power storage unit 20 in which two or more electrically connected non-aqueous electrolyte power storage elements 10 are assembled is further assembled. The power storage device 30 includes a plurality of power storage units 20. Each power storage unit 20 includes a plurality of non-aqueous electrolyte secondary batteries 10. The power storage device can be used as a power source for automobiles such as electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid vehicles (PHEV). Further, the power storage device 30 can be used for various power supply devices such as an engine starting power supply device, an auxiliary power supply device, and an uninterruptible power supply (UPS).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[Preparation of negative electrodes of Examples 1 to 10 and Comparative Examples 1 to 5]
It contains artificial solid graphite particles (average particle size 3.2 μm, average aspect ratio 1.6) as a negative electrode active material, SBR as a binder, and CMC as a thickener, and uses water as a dispersion medium. A negative electrode mixture paste was prepared. The ratio of the negative electrode active material, the binder, and the thickener was 97: 2: 1 in terms of mass ratio. Negative electrode mixture paste is applied to both sides of a copper foil substrate having an average thickness of 10 μm and dried to form a negative electrode mixture layer, and the negative electrodes of Examples 1 to 10 and Comparative Examples 1 to 5 are formed. Got Table 1 shows the physical property values of the negative electrode active material and the presence or absence of the pressing process. The coating amount of the negative electrode mixture (the dispersion medium evaporated from the negative electrode mixture paste) per unit area on one side after drying was set to 1.0 g / 100 cm ² . Further, in Example 6, Comparative Example 2 and Comparative Example 4, pressing was performed after drying the negative electrode mixture paste using a roll press machine so that the pressure (linear pressure) was 5 kgf / mm.

(Average particle size of graphite particles)
As the average particle diameter, the median diameter (D50) at which the volume-based integrated distribution calculated in accordance with JIS-Z8819-2 (2001) by the above method is 50% was determined.

(Determination of average aspect ratio of graphite particles)
The longest major axis T of the graphite particles and the longest minor axis Y in the direction perpendicular to the major axis T were measured by the above method, and the average aspect ratio of the graphite particles was determined.

[Preparation of Separator of Examples 1 to 10 and Comparative Examples 1 to 5]
A polyethylene microporous membrane was prepared as a separator. This microporous membrane is manufactured by a dry uniaxial stretching method. The uniaxially stretched microporous film has a heat shrinkage rate of 4% in the film transport direction (MD) when dried at a temperature of 120 ° C. for 1 hour, and has a width direction (TD) orthogonal to the film transport direction. The heat shrinkage rate is 0%. Table 1 shows the air permeability B, average thickness and porosity of the separator.

[Preparation of negative electrodes of Examples 11 to 19 and Comparative Examples 6 to 11]
Negative electrodes of Examples 11 to 19 and Comparative Examples 6 to 11 were obtained in the same manner as in Example 1 except that the configurations of the negative electrodes were as shown in Table 2. In each of Examples 11 to 19 and Comparative Examples 6 to 11, graphite as the negative electrode active material, which is the same as that used in Example 1, has an average particle size of 3.2 μm and an average aspect ratio of 1.6. )It was used.

[Preparation of Separator of Examples 11 to 19 and Comparative Examples 6 to 11]
A polyethylene microporous membrane was prepared as a separator. This microporous film is produced by a wet biaxial stretching method. Such a biaxially stretched microporous film has a heat shrinkage rate of 3% in the film transport direction (MD) when dried at a temperature of 120 ° C. for 1 hour, and has a width direction (TD) orthogonal to the film transport direction. The heat shrinkage rate of is 3%. Table 2 shows the air permeability C, average thickness and porosity of the separator.

[Manufacture of Non-Aqueous Electrolyte Storage Device of Examples 1 to 19 and Comparative Examples 1 to 11]
A non-aqueous electrolyte was prepared by dissolving LiPF ₆ in a non-aqueous solvent in which EC, EMC and DMC were mixed at a volume ratio of 30:35:35 so as to be 1.2 mol / L.
The positive electrode was prepared as follows. It contains Li _1.1 Ni _3/5 Mn _1/5 Co _1/5 O ₂ as a positive electrode active material, polyvinylidene fluoride (PVDF) as a binder, and acetylene black as a conductive agent, and N-methyl. A positive electrode mixture paste using -2-pyrrolidone (NMP) as a dispersion medium was prepared. The ratio of the positive electrode active material, the binder, and the conductive agent was 95: 4: 1 in mass ratio. The positive electrode mixture paste was applied to both sides of an aluminum foil base material having an average thickness of 15 μm, dried, and pressed to form a positive electrode mixture layer. The coating amount of the positive electrode mixture (the dispersion medium evaporated from the positive electrode mixture paste) per unit area on one side after drying was set to 1.7 g / 100 cm ² .
An electrode body was produced by winding the negative electrode, the positive electrode, and the polyethylene separator in a laminated state. The electrode body is housed in a metal case, the non-aqueous electrolyte is injected into the inside, and the cells are sealed, and the non-aqueous electrolytes of Examples 1 to 19 and Comparative Examples 1 to 11 which are test cells. A power storage element was obtained. Each battery produced in this manner was subjected to a predetermined initial charge / discharge treatment.

(Peak intensity ratio of negative electrode mixture layer (I (002) / I (110)))
Each battery after the initial charge / discharge treatment was discharged at a constant current of 1 CA in a constant temperature bath at 25 ° C. until a voltage at which the charge state (SOC: State of Charge) became 0% (end-of-discharge state). The discharged battery was disassembled in an atmosphere having a dew point of −20 ° C. or lower to take out the negative electrode, and then a portion not facing the positive electrode was cut out. After immersing in DMC to wash the lithium salt adhering to the negative electrode, the DMC was dried.
X-ray diffraction (XRD) measurement was performed on the negative electrode mixture layer of the negative electrode thus obtained. An X-ray diffractometer (manufactured by Rigaku Co., Ltd., RINT PTR3) was used for the measurement, and the following conditions were adopted.
Light source: Cu-Kα
Output voltage: 50kV
Output current: 300mA
Scan speed: 1 ° / sec
Step width: 0.03 °
Scan range: 10-100 °
Slit width (light receiving side): 0.3 mm
The data obtained by the measurement was analyzed using PDXL1.8.1, which is the software attached to the device, and the diffraction peak attributed to the (002) plane and the diffraction peak attributed to the (100) plane of the negative electrode mixture layer. The peak intensity ratio (I (002) / I (110)) with and was determined.
Background removal was performed when analyzing the X-ray diffraction data. No peak removal from Kα2 was performed. The intensity of the diffraction peak means the integrated intensity of the diffraction peak.

(Measurement of average thickness of negative electrode mixture layer)
As measurement samples, 10 samples with an area of 2 cm x 1 cm of the negative electrode before manufacturing the non-aqueous electrolyte power storage element were prepared, and the average thickness of each negative electrode was measured using a high-precision digital micrometer manufactured by Mitutoyo. did. The thickness of one negative electrode was measured at five points, and the average thickness of the negative electrode base material of 8 μm was subtracted from the average value to obtain the average thickness of the negative electrode mixture layer of one negative electrode. By calculating the average value of the average thicknesses of the negative electrode mixture layers of 10 negative electrodes, the average thickness of the negative electrode mixture layers was obtained.

[Evaluation]
(Output performance after charge / discharge cycle)
(1) Charge / Discharge Cycle Test The non-aqueous electrolyte power storage devices of the examples and comparative examples after the initial charge / discharge treatment were stored in a constant temperature bath at 45 ° C. for 5 hours, and then each had a SOC (System of Charge) of 100%. After a constant current charge of 0.5 CA to a certain voltage, the constant voltage charge was performed. The charging end condition was until the current value fell below 0.01 CA. Next, a 10-minute rest was provided after charging. Then, a constant current discharge was performed with a discharge current of 1 CA to a voltage at SOC 0%, and then a 10-minute pause was provided. These charging and discharging steps were regarded as one cycle, and this cycle was repeated for 500 cycles. Charging, discharging and pausing were performed in a constant temperature bath at 45 ° C.
(2) Output Performance Test at 25 ° C. After the charge / discharge cycle, each non-aqueous electrolyte power storage element is charged at a constant current at 0.5 CA to a voltage of 100% SOC in a constant temperature bath at 25 ° C., and then charged at a constant voltage. did. The charging end condition was until the current value fell below 0.01 CA. Next, a constant current was discharged at 1CA to adjust the SOC to 50%, and then the lower limit voltage was set to 2.75 V and the output at the first second of energization was measured by the IV method. The ratio (%) of the measured value of the output of each non-aqueous electrolyte power storage element to the measured value of the output of Example 1 was calculated and used as the output performance.

(Occurrence rate of minute short circuits after charge / discharge cycle)
When each non-aqueous electrolyte power storage element after the charge / discharge cycle is charged to SOC 20% and stored at 25 ° C. for 14 days, the difference between the voltage before storage and the battery voltage after storage of the non-aqueous electrolyte power storage element. The percentage (%) of the battery whose (battery voltage drop) was 0.01 V or more was defined as the micro short circuit occurrence rate. In this embodiment, after performing constant voltage charging at 3.55 V for 5 hours, the voltage is measured from 170 hours to 220 hours, and after storing at 25 ° C. for 14 days, the voltage is measured again. , The difference was taken as the battery voltage drop. Then, a test of 20 cells per level was performed, and the ratio was calculated to obtain a minute short circuit occurrence rate.

Table 1 shows the evaluation results of the non-aqueous electrolyte power storage devices of Examples 1 to 10 and Comparative Examples 1 to 5 provided with a uniaxially stretched porous resin layer separator. Table 2 shows the evaluation results of the non-aqueous electrolyte power storage devices of Examples 11 to 19 and Comparative Examples 6 to 11 provided with the separator of the biaxially stretched porous resin layer. Further, FIG. 4 shows the relationship between the peak intensity ratio A of the negative electrode mixture layer of Examples 1 to 10 and Comparative Examples 1 to 5 × the air permeability B / 10000 of the porous resin layer and the output performance. FIG. 6 shows the relationship between the peak intensity ratio A of the negative electrode mixture layer of Examples 11 to 19 and Comparative Examples 6 to 11 × the air permeability C / 10000 of the porous resin layer and the output performance. Shown. FIG. 5 shows the relationship between the peak intensity ratio A of the negative electrode mixture layer of Examples 1 to 10 and Comparative Examples 1 to 5 × the air permeability B / 10000 of the porous resin layer and the occurrence rate of micro short circuits. Shown, FIG. 7 shows the peak intensity ratio A of the negative electrode mixture layer of Examples 11 to 19 and Comparative Examples 6 to 11 × the air permeability C / 10000 of the porous resin layer and the occurrence rate of micro short circuits. Show the relationship.

As shown in Tables 1, 4 and 5, a separator having a uniaxially stretched porous resin layer is provided, and the peak intensity ratio of the (002) plane to the (110) plane in X-ray diffraction of the negative electrode mixture layer. The relationship between (I (002) / I (110)) A and the air permeability B (seconds / 100 mL) of the porous resin layer is 5.7 ≦ A × B / 10000 ≦ 15.2. In Examples 1 to 10, both the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit were excellent. Further, from Example 6, it can be seen that it is excellent even when the negative electrode is pressed.

On the other hand, the peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the air permeability B (seconds) of the porous resin layer. Comparative Examples 1 to 5 having a relationship with (/ 100 mL) of less than 5.7 or more than 15.2 have a charge / discharge cycle as compared with Examples 1 to 10 regardless of the presence or absence of pressing of the negative electrode. Either the later output performance or the suppression effect against minute short circuits was inferior.

Further, as shown in Tables 2, 6 and 7, a separator having a biaxially stretched porous resin layer is provided, and the (002) plane with respect to the (110) plane in the X-ray diffraction of the negative electrode mixture layer is provided. The relationship between the peak intensity ratio (I (002) / I (110)) A and the air permeability C (seconds / 100 mL) of the porous resin layer is 3.6 ≦ A × C / 10000 ≦ 9.1. In Examples 11 to 19, the output performance after the charge / discharge cycle and the effect of suppressing minute short circuits were both excellent.

On the other hand, the peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the air permeability C (seconds) of the porous resin layer. Comparative Examples 6 to 11 having a relationship with (/ 100 mL) of less than 3.6 or more than 9.1 have a charge / discharge cycle as compared with Examples 11 to 19 regardless of the presence or absence of pressing of the negative electrode. Either the later output performance or the suppression effect against minute short circuits was inferior.

As described above, it was shown that the non-aqueous electrolyte power storage element is excellent in the output performance after the charge / discharge cycle and the effect of suppressing a minute short circuit between the positive electrode and the negative electrode.

The present invention is suitably used as a non-aqueous electrolyte power storage element such as a non-aqueous electrolyte secondary battery used as a power source for personal computers, electronic devices such as communication terminals, automobiles, and the like.

1 Negative electrode 2 Negative electrode base material 3 Negative electrode mixture layer 4 Separator 10 Non-aqueous electrolyte secondary battery 12 Electrode body 13 Battery container 14 Positive electrode terminal 14'Positive lead 15 Negative terminal 15' Negative lead 20 Power storage unit 30 Power storage device

Claims (6)

A negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and a negative electrode
It has a uniaxially stretched porous resin layer, and includes a separator laminated along the negative electrode mixture layer.
The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the air permeability B (seconds / second) of the porous resin layer. A non-aqueous electrolyte power storage element having a relationship of 5.7 ≦ A × B / 10000 ≦ 15.2 (100 mL). A negative electrode having a negative electrode mixture layer containing a negative electrode active material containing graphite particles, and a negative electrode
It has a biaxially stretched porous resin layer, and includes a separator laminated along the negative electrode mixture layer.
The peak intensity ratio (I (002) / I (110)) A of the (002) plane to the (110) plane in the X-ray diffraction of the negative electrode mixture layer and the air permeability C (seconds / second) of the porous resin layer. A non-aqueous electrolyte power storage element having a relationship with (100 mL) of 3.6 ≦ A × C / 10000 ≦ 9.1. The non-aqueous electrolyte power storage element according to claim 1 or 2, wherein the peak intensity ratio A is 300 or more and 700 or less. The non-aqueous electrolyte power storage device according to any one of claims 1 to 3, wherein the graphite particles are solid particles. The non-aqueous electrolyte power storage device according to any one of claims 1 to 4, wherein the average particle size of the graphite particles is 2.0 μm or more and 6.0 μm or less. The non-aqueous electrolyte power storage element according to any one of claims 1 to 5, wherein the average aspect ratio of the graphite particles is 1.0 or more and 5.0 or less.

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