JP6094163B2 - Separator for lithium ion secondary battery - Google Patents

Description

  The present invention relates to a separator for a lithium ion secondary battery.

  Lithium-ion secondary batteries are lighter and have higher input / output characteristics than other secondary batteries such as nickel metal hydride batteries and lead-acid batteries. It is attracting attention as an output power source.

However, if impurities (magnetic impurities such as Fe, Ni, Cu, etc.) are present in the constituent materials of the battery, the impurities may be deposited on the negative electrode during charge / discharge. Impurities deposited on the negative electrode can cause a short circuit by breaking the separator and reaching the positive electrode.
Moreover, the lithium ion secondary battery may be used in a car in summer. In this case, the operating temperature of the lithium ion secondary battery may be 40 ° C to 80 ° C. At this time, the metal in the Li-containing metal oxide constituting the positive electrode is eluted from the positive electrode, and the battery characteristics can be deteriorated.

  For this reason, studies have been made on impurity scavengers or adsorbents (hereinafter simply referred to as adsorbents) and positive electrode stabilization (see, for example, Patent Document 1).

  Further, for example, a positive electrode using a lithium compound containing Fe or Mn as a metal element as a constituent element as a positive electrode active material, and a negative electrode using a carbon material capable of occluding or releasing lithium ions as a negative electrode active material are contained in a non-aqueous electrolyte. The positive electrode contains 0.5 to 5 wt% of zeolite with respect to the positive electrode active material, and the zeolite has an effective pore diameter of the metal. A non-aqueous lithium ion secondary battery that is larger than the ion radius of the element and is 0.5 nm (5 cm) or less is disclosed (for example, see Patent Document 2).

JP 2000-77103 A JP 2010-129430 A

However, there are cases where the known adsorbents cannot adsorb impurities with high selectivity, and it is difficult to say that the adsorption capacity per unit mass is sufficient, so that sufficient life characteristics may not be obtained.
This invention makes it a subject to provide the separator for lithium ion secondary batteries which can selectively suppress the raise of the density | concentration of an unnecessary metal ion.

Specific means for solving the above problems are as follows.
<1> A separator for a lithium ion secondary battery including a separator base material and an aluminum silicate having an element molar ratio Si / Al of silicon (Si) to aluminum (Al) of 0.3 or more and less than 1.0.

<2> The lithium ion secondary battery separator according to <1>, wherein the aluminum silicate has a peak in the vicinity of 3 ppm in a ²⁷ Al-NMR spectrum.

<3> The lithium-ion secondary battery separator according to <1> or <2>, wherein the aluminum silicate has a peak in the vicinity of −78 ppm and in the vicinity of −85 ppm in a ²⁹ Si-NMR spectrum.

<4> The lithium ion secondary battery separator according to any one of <1> to <3>, wherein the elemental molar ratio Si / Al of the aluminum silicate is 0.4 or more and 0.6 or less. .

<5> The aluminum silicate has peaks in the vicinity of 2θ = 26.9 ° and 40.3 ° in a powder X-ray diffraction spectrum using CuKα ray as an X-ray source, and is derived from a layered clay mineral 2θ. = The separator for a lithium ion secondary battery according to any one of <1> to <4>, which does not have a peak around 20 ° and 35 °.

<6> The aluminum silicate has an area ratio (peak B / peak A) of the peak B near -85 ppm to the peak A near -78 ppm in the ²⁹ Si-NMR spectrum of 2.0 or more and 9.0. The separator for a lithium ion secondary battery according to any one of <3> to <5>, which is the following.

<7> The lithium ion secondary battery separator according to any one of <1> to <6>, wherein the aluminum silicate has a BET specific surface area of 250 m ² / g or more.

<8> The lithium-ion secondary battery separator according to any one of <1> to <7>, wherein the aluminum silicate has a moisture content of 10% by mass or less.

  ADVANTAGE OF THE INVENTION According to this invention, the separator for lithium ion secondary batteries which can selectively suppress the raise of the density | concentration of an unnecessary metal ion can be provided.

It is a ²⁷ Al-NMR spectrum of an aluminum silicate concerning manufacture example 1 and manufacture example 2. It is a ²⁹ Si-NMR spectrum of aluminum silicate concerning manufacture example 1 and manufacture example 2. 3 is a powder X-ray diffraction spectrum of aluminum silicate according to Production Example 1 and Production Example 2. FIG. 2 is a transmission electron microscope (TEM) photograph of aluminum silicate according to Production Example 1. FIG. 4 is a transmission electron microscope (TEM) photograph of aluminum silicate according to Production Example 2. It is a figure which shows typically what is called tubular imogolite which is an example of this embodiment.

In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . In the present specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Furthermore, in this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. means.
In this specification, “(meth) acrylate” means “acrylate” and “methacrylate” corresponding thereto. The same applies to other similar expressions such as “(meth) acrylic copolymer”.
The thickness of the layer or member in the present invention is an average value when five points are measured with a micrometer manufactured by Mitutoyo Corporation.

<Separator for lithium ion secondary battery>
The separator for a lithium ion secondary battery according to the present invention is an aluminum silica in which the element molar ratio Si / Al of silicon (Si) to aluminum (Al) is 0.3 or more and less than 1.0. An acid salt (hereinafter also referred to as “specific aluminum silicate”) is included. The lithium ion secondary battery separator may further contain other components as necessary.
The specific aluminum silicate having an element molar ratio Si / Al between silicon (Si) and aluminum (Al) of 0.3 or more and less than 1.0 is an oxide salt of Si and Al. Since Si and Al have different valences, there are many OH groups in the oxide salt of Si and Al, and this has ion exchange ability. Therefore, the specific aluminum silicate has many metal ion adsorption sites per unit mass, and thereby has a characteristic of highly selectively adsorbing metal ions with a high specific surface area. In particular, the specific aluminum silicate has a specific property of adsorbing unnecessary metal ions even though it hardly adsorbs lithium ions essential for charging and discharging of a lithium ion battery. In the present invention, unnecessary metal ions refer to nickel ions other than lithium ions, manganese ions, copper ions, iron ions, and the like. These unnecessary metal ions are derived from impurity ions present in the constituent material of the battery or ions eluted from the positive electrode at a high temperature.
Moreover, since specific aluminum silicate is an inorganic oxide, it is excellent in thermal stability and stability in a solvent. For this reason, specific aluminum silicate can exist stably also in the lithium ion secondary battery in charge / discharge.

  By including the specific aluminum silicate in the separator, unnecessary metal ions such as impurity ions in the lithium ion secondary battery or metal ions eluted from the positive electrode or the like are adsorbed on the specific aluminum silicate. Thereby, an increase in the concentration of unnecessary metal ions in the battery can be selectively suppressed. In the lithium ion secondary battery having such a separator, the occurrence of a short circuit over time due to unnecessary metal ions is suppressed, and the lithium ion secondary battery has excellent life characteristics.

  When the separator contains a specific aluminum silicate, unnecessary metal ions that pass through the separator and move in both directions between the positive electrode side and the negative electrode side become more efficient as the lithium ion secondary battery is charged and discharged. Can be adsorbed on.

[Specific aluminum silicate]
The specific aluminum silicate has an element molar ratio Si / Al of aluminum (Al) to aluminum (Al) of 0.3 or more and less than 1.0. In this respect, the specific aluminum silicate is a substance different from zeolite having an element molar ratio Si / Al of 1.0 or more.
The specific aluminum silicate having such a configuration has excellent adsorptivity for unnecessary metal ions such as manganese ions, nickel ions, copper ions, iron ions, and the like, and has relatively low adsorptivity for lithium ions. Thereby, it is possible to efficiently adsorb unnecessary metal ions that may cause a short circuit.

  The specific aluminum silicate is an oxide salt containing Si and Al. Since Si and Al have different valences, many oxides of Si and Al have many OH groups. This is considered to have excellent metal ion adsorption and metal ion selectivity. Moreover, since specific aluminum silicate is an inorganic oxide, it is excellent in thermal stability and stability in a solvent. For this reason, when it is made to contain in the component of a lithium ion secondary battery, specific aluminum silicate can exist stably also during charging / discharging.

The elemental molar ratio Si / Al of Al to Al in the specific aluminum silicate is 0.3 or more and less than 1.0, preferably 0.4 or more and 0.6 or less, and 0.45 or more and 0.00. More preferably, it is 55 or less.
If the element molar ratio Si / Al is less than 0.3, the amount of Al that does not contribute to the improvement of the metal ion adsorption property of the aluminum silicate becomes excessive, and the ion adsorption property per unit mass may be lowered. Further, when the element molar ratio Si / Al is 1.0 or more, the amount of Si that does not contribute to the improvement of the metal ion adsorption property of the aluminum silicate becomes excessive, and the ion adsorption property per unit mass may be lowered. . Further, when the element molar ratio Si / Al is 1.0 or more, the selectivity of the adsorbing metal ions may be lowered.

  In addition, element molar ratio Si / Al was obtained by calculating | requiring the atomic concentration of Si and Al by a conventional method using ICP emission-spectral-analysis (for example, ICP emission-analysis apparatus: P-4010 by Hitachi, Ltd.). Calculated from atomic concentration.

The specific aluminum silicate preferably has a peak in the vicinity of 3 ppm in the ²⁷ Al-NMR spectrum. ^{As the 27} Al-NMR measuring apparatus, for example, AV400WB manufactured by Bruker BioSpin can be used. Specific measurement conditions are as follows.
Resonance frequency: 104MHz
Measuring method: MAS (single pulse)
MAS rotation speed: 10 kHz
Measurement area: 52 kHz
Number of data points: 4096
resolution (measurement area / number of data points): 12.7 Hz
Pulse width: 3.0 μsec
Delay time: 2 seconds Chemical shift value standard: 3.94 ppm of α-alumina
window function: exponential function Line Broadening coefficient: 10 Hz

In FIG. 1, the ²⁷ Al-NMR spectrum of the specific aluminum silicate which concerns on the below-mentioned manufacture example 1 and manufacture example 2 is shown as an example of specific aluminum silicate.

As shown in FIG. 1, the specific aluminum silicate preferably has a peak in the vicinity of 3 ppm in the ²⁷ Al-NMR spectrum. The peak around 3 ppm is estimated to be a peak derived from 6-coordinated Al. Furthermore, you may have a peak around 55 ppm. The peak near 55 ppm is estimated to be a peak derived from tetracoordinated Al.

In the specific aluminum silicate, the area ratio of the peak in the vicinity of 55 pm to the peak in the vicinity of 3 ppm is preferably 25% or less and preferably 20% or less from the viewpoint of metal ion adsorption and metal ion selectivity. More preferably, it is more preferably 15% or less.
The specific aluminum silicate preferably has an area ratio of a peak near 55 pm to a peak near 3 ppm in the ²⁷ Al-NMR spectrum of 1% or more from the viewpoint of metal ion adsorption and metal ion selectivity. It is more preferably 5% or more, and further preferably 10% or more.

The specific aluminum silicate preferably has peaks at around -78 ppm and around -85 ppm in the ²⁹ Si-NMR spectrum. By being a specific aluminum silicate exhibiting such a specific ²⁹ Si-NMR spectrum, metal ion adsorption and metal ion selectivity are further improved.

^{As the 29} Si-NMR measuring apparatus, for example, AV400WB manufactured by Bruker BioSpin can be used. Specific measurement conditions are as follows.
Resonance frequency: 79.5 MHz
Measuring method: MAS (single pulse)
MAS rotation speed: 6 kHz
Measurement area: 24 kHz
Number of data points: 2048
resolution (measurement area / number of data points): 5.8 Hz
Pulse width: 4.7 μsec
Delay time: 600 sec chemical shift value criterion: _TMSP-d 4 (3- (trimethylsilyl) (2,2,3,3- ² H ₄₎ propionate) 1.52Ppm the
window function: exponential function Line Broadening coefficient: 50 Hz

In FIG. 2, the ²⁹ Si-NMR spectrum of the specific aluminum silicate which concerns on the below-mentioned manufacture example 1 and manufacture example 2 is shown as an example of specific aluminum silicate.

As shown in FIG. 2, the specific aluminum silicate preferably has peaks in the vicinity of −78 ppm and in the vicinity of 85 ppm in the ²⁹ Si-NMR spectrum. The peak A that appears in the vicinity of −78 ppm is considered to be derived from an aluminum silicate having a crystal structure such as imogolite and allophane, and also due to a structure of HO—Si— (OAl) ₃ .
The peak B appearing around −85 ppm is considered to be an aluminum silicate having a clay structure or an aluminum silicate having an amorphous structure. Therefore, the specific aluminum silicate having peaks at around -78 ppm and around 85 ppm is presumed to be a mixture or composite of an aluminum silicate having a crystal structure and an aluminum silicate having a clay structure or an amorphous structure. Is done.

  In particular, a specific aluminum silicate having a peak A that appears in the vicinity of −78 ppm has many OH groups per unit mass. For this reason, it has been found that the specific aluminum silicate having the peak A that appears in the vicinity of −78 ppm is excellent in moisture adsorption ability. The present inventors have found that this specific aluminum silicate is excellent in ion adsorption ability in addition to moisture adsorption ability, and selectively adsorbs ions that particularly adversely affect the battery. In particular, the present inventors say that this specific aluminum silicate adsorbs impurity ions or ions eluted from the positive electrode even though it hardly adsorbs lithium ions essential for charging and discharging of a lithium ion secondary battery. It has been found that it has specific properties. For this reason, in the lithium ion battery configured using the separator containing the specific aluminum silicate, the occurrence of short circuit with time is remarkably reduced, and as a result, a lithium ion secondary battery having excellent life characteristics can be provided. be able to.

  The specific aluminum silicate may not have a peak around −110 ppm derived from the layered clay mineral. Here, having no peak means that the displacement from the baseline in the vicinity of −110 ppm is less than or equal to the noise level, specifically, that the displacement from the baseline is less than 100% of the noise width. To do.

From the viewpoint of improving the metal ion adsorption ability and metal ion selectivity, the specific aluminum silicate has an area ratio (peak B / peak) of peak A around -78 ppm and peak B around -85 ppm in the ²⁹ Si-NMR spectrum. A) is preferably 0.4 to 9.0, more preferably 1.5 to 9.0, still more preferably 2.0 to 9.0, and 2.0 to 7 Is more preferably 0.0, more preferably 2.0 to 5.0, and particularly preferably 2.0 to 4.0.

When obtaining the area ratio of the peaks in ²⁹ Si-NMR spectrum, subtract baseline in first ²⁹ Si-NMR spectra. In FIG. 2, a straight line connecting -55 ppm and -140 ppm is taken as a baseline.

Next, the curve of the ²⁹ Si-NMR spectrum is delimited by a chemical shift value (near -81 ppm in FIG. 2) corresponding to the valley between the peak appearing near −78 ppm and the peak near −85 ppm.

The area of peak A around −78 ppm is the area of the region surrounded by the straight line passing through −81 ppm orthogonal to the chemical shift axis in FIG. 2, the above-mentioned baseline, and the curve of the ²⁹ Si-NMR spectrum. The area of peak B is the area of a region surrounded by a straight line passing through −81 ppm and orthogonal to the chemical shift axis, the base line, and the curve of the ²⁹ Si-NMR spectrum.
In addition, you may obtain | require the area of each said peak with the analysis software integrated in the NMR measuring apparatus.

  The specific aluminum silicate preferably has peaks in the vicinity of 2θ = 26.9 ° and 40.3 ° in a powder X-ray diffraction spectrum using CuKα ray as an X-ray source. The powder X-ray diffraction spectrum is measured using CuKα rays as an X-ray source. Further, for example, Rigaku Corporation: Geigerflex RAD-2X (trade name) can be used as the X-ray diffractometer.

FIG. 3 shows a powder X-ray diffraction spectrum of the specific aluminum silicate according to Production Example 1 and Production Example 2 described later as an example of the specific aluminum silicate.
As shown in FIG. 3, the specific aluminum silicate has a peak in the vicinity of 2θ = 26.9 ° and 40.3 ° in the powder X-ray diffraction spectrum. The peaks around 2θ = 26.9 ° and 40.3 ° are presumed to be peaks derived from the specific aluminum silicate.

The specific aluminum silicate may not have a broad peak around 2θ = 20 ° and 35 ° in the powder X-ray diffraction spectrum. The peaks around 2θ = 20 ° and 35 ° are considered to be peaks caused by reflection on the hk0 plane of the low crystalline layered clay mineral.
Here, having no peaks around 2θ = 20 ° and 35 ° means that the displacement from the baseline around 2θ = 20 ° and 35 ° is below the noise level, specifically, the baseline. This means that the displacement is 100% or less of the noise width.

  Further, like the specific aluminum silicate according to Production Example 1, the specific aluminum silicate is in the vicinity of 2θ = 18.8 °, 20.3 °, 27.8 °, 40.6 ° and 53.3 °. May have a peak. The peaks around 2θ = 18.8 °, 20.3 °, 27.8 °, 40.6 °, and 53.3 ° are presumed to be peaks derived from by-product aluminum hydroxide. In addition, in the manufacturing method of the specific aluminum silicate mentioned later, precipitation of aluminum hydroxide can be suppressed by making the heating temperature at the time of heat processing into 160 degrees C or less. Moreover, content of aluminum hydroxide can be adjusted by adjusting pH at the time of the desalting process by centrifugation.

  Further, like the specific aluminum silicate according to Production Example 2, the specific aluminum silicate may have peaks in the vicinity of 2θ = 4.8 °, 9.7 °, and 14.0 °. Further, it may have a peak in the vicinity of 2θ = 18.3 °. The peaks around 2θ = 4.8 °, 9.7 °, 14.0 °, and 18.3 ° indicate that bundles of so-called imogolite monofilaments, which are tubular specific aluminum silicates, aggregate in parallel. It is presumed to be a peak derived from taking it.

  4 and 5 show an example of a transmission electron microscope (TEM) photograph of the specific aluminum silicate. The specific aluminum silicate shown in FIG. 4 is a specific aluminum silicate according to Production Example 1 described later. The specific aluminum silicate shown in FIG. 5 is a specific aluminum silicate according to Production Example 2 described later.

As shown in FIG. 4, the specific aluminum silicate according to Production Example 1 has a tubular product having a length of 50 nm or more when observed at a magnification of 100,000 with a transmission electron microscope (TEM). Absent. The specific aluminum silicate according to Production Example 2 is a so-called imogolite having a tubular shape as shown in FIG.
From the viewpoint of metal ion adsorption ability and metal ion selectivity, the specific aluminum silicate has no tubular material with a length of 50 nm or more when observed at a magnification of 100,000 with a transmission electron microscope (TEM). It is preferable.

  Observation of the specific aluminum silicate with a transmission electron microscope (TEM) is performed at an acceleration voltage of 100 kV. Moreover, as an observation sample, the heated solution before the second washing step (desalting and solid separation) in the manufacturing method described later is dropped on a support for preparing a TEM observation sample, and then the dropped heated solution is dried. Then, a thin film is used. When the contrast of the TEM image cannot be obtained sufficiently, an observation sample is prepared using a solution obtained by appropriately diluting the solution after heating so that sufficient contrast can be obtained.

  The tubular product as shown in FIG. 5 is manufactured by performing a heat treatment when the silicate ions and the aluminum ions are at a specific concentration or less in the method for manufacturing a specific aluminum silicate described later. On the other hand, the specific aluminum silicate in which the tubular product as shown in FIG. 4 is not observed is manufactured by performing a heat treatment when the silicate ions and the aluminum ions have a specific concentration or more.

  FIG. 6 is a drawing schematically showing a tubular so-called imogolite, which is an example of a specific aluminum silicate. As shown in FIG. 6, this specific aluminum silicate 10 has a structure in which a plurality of (three in FIG. 6) tubular bodies 10a are assembled. A gap 30 defined by the outer wall of the tubular body 10a is formed between the plurality of tubular bodies 10a. The specific aluminum silicate 10 has a tendency that a fiber structure is formed by the tubular bodies 10a, and the tubular body 10a that forms the inner wall 20 in the tube of the tubular body 10a and the gap 30 between the plurality of tubular bodies 10a. The outer wall (outer peripheral surface) can be used as an adsorption site for metal ions. The length of the tubular body 10a in the tube portion length direction is, for example, 1 nm to 10 μm. The tubular body 10a has, for example, a circular tubular shape, and has an outer diameter of, for example, 1.5 nm to 3.0 nm and an inner diameter of, for example, 0.7 nm to 1.4 nm.

In addition, when the so-called imogolite fiber which is a tubular specific aluminum silicate is observed with a transmission electron microscope (TEM) photograph, the area of the peak B tends to be small in the ²⁹ Si-NMR spectrum.

The specific aluminum silicate preferably has a BET specific surface area of 250 m ² / g or more, and more preferably 280 m ² / g or more, from the viewpoint of improving the metal ion adsorption ability. When the BET specific surface area is 250 m ² / g or more, the adsorbed amount of impurity ions and eluted ions per unit mass is increased, so that the efficiency is good and a high effect is obtained with a small amount.

The upper limit of the BET specific surface area is not particularly limited, but a part of Si and Al in the specific aluminum silicate is bonded in the form of Si-O-Al, which contributes to the improvement of metal ion adsorption capacity. Therefore, the BET specific surface area is preferably 1500 m ² / g or less, more preferably 1200 m ² / g or less, and still more preferably 1000 m ² / g or less.

  The BET specific surface area of the specific aluminum silicate is measured from the nitrogen adsorption capacity according to JIS Z 8830. As an evaluation apparatus, QUANTACHROME make: AUTOSORB-1 (brand name) etc. can be used. When measuring the BET specific surface area, it is considered that the moisture adsorbed on the sample surface and the structure affects the gas adsorption capacity. Therefore, pretreatment for removing moisture by heating is first performed.

  In the pretreatment, the measurement cell charged with 0.05 g of the measurement sample is depressurized to 10 Pa or less with a vacuum pump, heated at 110 ° C., held for 3 hours or more, and kept at a normal temperature while maintaining the depressurized state. Cool naturally to (25 ° C). After performing this pretreatment, the evaluation temperature is 77K, and the evaluation pressure range is measured as a relative pressure (equilibrium pressure with respect to saturated vapor pressure) of less than 1.

Certain aluminum silicates, from the viewpoint of improving the adsorption capacity of the metal ion is preferably the total pore volume is 0.1 cm ³ / g or more, more preferably 0.12 cm ³ / g or more, More preferably, it is 0.15 cm ³ / g or more. Further, the upper limit value of the total pore volume is not particularly limited. If the total pore volume is large, the amount of moisture adsorbed in the air per unit mass increases, so the total pore volume is preferably 1.5 m ² / g or less, and 1.2 m ² / g or less. More preferably, it is 1.0 m ² / g or less.

  The total pore volume of the specific aluminum silicate is based on the BET specific surface area, and the gas adsorption amount closest to the relative pressure 1 is converted to liquid in the data obtained when the relative pressure is 0.95 or more and less than 1. And ask.

Since the ion radius of the impurity ions is 0.01 nm to 0.1 nm, the average pore diameter of the specific aluminum silicate is preferably 1.5 nm or more, and more preferably 2.0 nm or more. When the average pore diameter is within the above range, the impurity ions can be efficiently adsorbed even when the impurity ions move to the adsorption site with the ligand. Further, the upper limit value of the average pore diameter is not particularly limited, but when the average pore diameter is large, the specific surface area is decreased, so that it is preferably 50 nm or less, and more preferably 20 nm or less. More preferably, it is 5.0 nm or less.
The average pore diameter of the specific aluminum silicate is determined based on the BET specific surface area and the total pore volume, assuming that all the pores are composed of one cylindrical pore.

The specific aluminum silicate has a water content of preferably 10% by mass or less, and more preferably 5% by mass or less. When the water content is 10% by mass or less, when a lithium ion secondary battery is configured, generation of gas due to water causing electrolysis can be suppressed, and battery expansion can be suppressed.
The moisture content can be measured by the Karl Fischer method.

  As a method for adjusting the water content of the specific aluminum silicate to 10% by mass or less, a commonly used drying method can be used without any particular limitation. For example, the method of heat-processing at 100 degreeC-300 degreeC for about 6 hours-24 hours under atmospheric pressure is mentioned.

[Method for producing specific aluminum silicate]
The method for producing a specific aluminum silicate includes (a) a step of mixing a solution containing silicate ions and a solution containing aluminum ions to obtain a reaction product, and (b) desalting and solidifying the reaction product. (C) a step of heat-treating the solid separated in the step (b) in an aqueous medium in the presence of an acid; and (d) a heat-treatment in the step (c). And a step of desalting and separating the solid, and having other steps as necessary.

Desalting coexisting ions from a solution containing the reaction product aluminum silicate, and then heat-treating it in the presence of an acid to efficiently produce a specific aluminum silicate with excellent metal ion adsorption capacity Can do.
This can be considered as follows, for example. The specific aluminum silicate having a regular structure is formed by heat-treating the aluminum silicate from which the coexisting ions that inhibit the formation of the regular structure are removed in the presence of an acid. It can be considered that when the specific aluminum silicate has a regular structure, the affinity for metal ions is improved and the metal ions can be adsorbed efficiently.

(A) Step of obtaining reaction product In the step of obtaining reaction product, a solution containing silicate ions and a solution containing aluminum ions are mixed to contain a reaction product containing aluminum silicate and coexisting ions. To obtain a mixed solution.

(Silicate ion and aluminum ion)
When producing aluminum silicate, silicate ions and aluminum ions are required as raw materials. The silicic acid source constituting the solution containing silicate ions (hereinafter also referred to as “silicate solution”) is not particularly limited as long as silicate ions are generated when solvated. Examples of the silicic acid source include, but are not limited to, tetraalkoxysilane such as sodium orthosilicate, sodium metasilicate, and tetraethoxysilane.
Moreover, the aluminum source which comprises the solution containing aluminum ion (henceforth "aluminum solution") will not be restrict | limited especially if an aluminum ion produces | generates when it solvates. Examples of the aluminum source include, but are not limited to, aluminum chloride, aluminum perchlorate, aluminum nitrate, and aluminum sec-butoxide.

  As the solvent, those which can easily be solvated with the silicate source and the aluminum source which are raw materials can be appropriately selected and used. Specifically, water, ethanol or the like can be used as the solvent. From the viewpoint of reducing coexisting ions in the solution during the heat treatment and ease of handling, it is preferable to use water as the solvent.

(Mixing ratio and solution concentration)
These raw materials are dissolved in a solvent to prepare raw material solutions (silicic acid solution and aluminum solution), and then the raw material solutions are mixed with each other to obtain a mixed solution. The element molar ratio Si / Al in the mixed solution is 0.3 or more and less than 1.0 in accordance with the element molar ratio Si / Al of Si and Al in the specific aluminum silicate obtained. It adjusts, Preferably it adjusts so that it may become 0.4 or more and 0.6 or less, More preferably, it adjusts so that it may become 0.45 or more and 0.55 or less. By setting the element molar ratio Si / Al to 0.3 or more and less than 1.0, a specific aluminum silicate having a desired regular structure can be easily synthesized.

  In addition, when mixing the raw material solutions, it is preferable to gradually add the silicic acid solution to the aluminum solution. By doing in this way, the polymerization of silicic acid which can become a formation inhibition factor of desired specific aluminum silicate can be suppressed.

The silicon atom concentration of the silicic acid solution is not particularly limited. Preferably, it is 1 mmol / L to 1000 mmol / L.
When the silicon atom concentration of the silicate solution is 1 mmol / L or more, the productivity is improved and the specific aluminum silicate can be efficiently produced. Further, when the silicon atom concentration is 1000 mmol / L or less, the productivity is further improved according to the silicon atom concentration.

The aluminum atom concentration of the aluminum solution is not particularly limited. Preferably, it is 100 mmol / L to 1000 mmol / L.
When the aluminum atom concentration of the aluminum solution is 100 mmol / L or more, the productivity is improved and the specific aluminum silicate can be produced efficiently. Further, when the aluminum atom concentration is 1000 mmol / L or less, the productivity is further improved according to the aluminum atom concentration.

(B) First washing step (desalting and solid separation)
A solution containing silicate ions and a solution containing aluminum ions are mixed, and an aluminum silicate containing coexisting ions is generated as a reaction product in the obtained mixed solution. A first washing step of desalting the acid salt and separating the solid is performed. In the first washing step, at least a part of the coexisting ions is removed from the mixed solution to reduce the coexisting ion concentration in the mixed solution. By performing the first cleaning step, it is easy to form a desired specific aluminum silicate in the synthesis step.

  In the first washing step, desalting and solid separation are performed by using anions other than silicate ions derived from the silicate source and aluminum source (chloride ions, nitrate ions, etc.) and cations other than aluminum ions (sodium ions, etc.) There is no particular limitation as long as at least a part of them can be removed (desalted) and separated into solids. Examples of the first washing step include a method using centrifugation, a method using a dialysis membrane, and a method using an ion exchange resin.

The first washing step is preferably performed so that the concentration of coexisting ions in the mixed solution is equal to or lower than a predetermined concentration. For example, when the solid separated product obtained in the first washing step is dispersed in pure water so as to have a concentration of 60 g / L, the electrical conductivity of the dispersion becomes 4.0 S / m or less. It is preferable to perform the cleaning so that the cleaning is performed at 1.0 mS / m or more and 3.0 S / m or less, and the cleaning is performed at 1.0 mS / m or more and 2.0 S / m or less. It is more preferable to carry out.
When the electrical conductivity of the dispersion is 4.0 S / m or less, the desired specific aluminum silicate tends to be more easily formed in the synthesis step.
In addition, electrical conductivity is measured at normal temperature (25 degreeC) using the product made from HORIBA: F-55 and the company's general electrical conductivity cell: 9382-10D.

The first cleaning step includes a step of dispersing the aluminum silicate in a solvent to obtain a dispersion, a step of adjusting the pH of the dispersion to 5 to 8, and a step of depositing aluminum silicate. It is preferable.
For example, when performing a 1st washing | cleaning process using centrifugation, it can carry out as follows. The pH is adjusted to 5-8 by adding alkali or the like to the dispersion. After centrifuging the dispersion after adjusting the pH, the supernatant solution is discharged and the solid is separated as a gel-like precipitate. The separated solid is redispersed in a solvent. In that case, it is preferable to return the volume of the dispersion to the volume before centrifugation using, for example, a solvent. The concentration of the coexisting ions can be reduced to a predetermined concentration or less by repeating the operations of desalting and solid separation by centrifugal separation of the redispersed dispersion in the same manner.

  In the first washing step, the pH of the dispersion is adjusted to 5 to 8, for example. The pH of the dispersion is preferably 5.5 to 6.8, and more preferably 5.8 to 6.5. The alkali used for pH adjustment is not particularly limited. As the alkali used for pH adjustment, sodium hydroxide, ammonia and the like are preferable.

  Centrifugation conditions are appropriately selected according to the production scale or the type or size of the container used. As conditions for centrifugation, for example, it can be 1 to 30 minutes at 1200 G or more at room temperature. Specifically, as the conditions for the centrifugation, for example, when using TOMY: Suprema23 and the company's standard rotor NA-16 as a centrifuge, the temperature is set to 3000 rpm (1450 G) or more and 5 to 10 minutes at room temperature. be able to.

  As a solvent in a 1st washing | cleaning process, what can be easily solvated with a raw material can be selected suitably, and can be used. Specifically, water, ethanol or the like can be used as the solvent. As the solvent, it is preferable to use water, and more preferable to use pure water, from the viewpoint of reduction of coexisting ions in the solution at the time of heat synthesis and ease of handling. In addition, when performing washing | cleaning of multiple times repeatedly, it is preferable to abbreviate | omit pH adjustment of a mixed solution.

  The number of treatments for desalting and solid separation in the first washing step may be appropriately set according to the remaining amount of coexisting ions. For example, it can be 1 to 6 times. If the washing is repeated about three times, the residual amount of coexisting ions is reduced to such an extent that does not affect the synthesis of the desired specific aluminum silicate.

  The pH at the time of pH adjustment can be measured by a pH meter using a general glass electrode. Specifically, for example, trade name: MODEL (F-51) manufactured by HORIBA, Ltd. can be used.

(C) Synthesis step In the synthesis step, the solid isolate obtained in the first washing step is heat-treated in an aqueous medium in the presence of an acid.
The solution (dispersion) containing aluminum silicate with reduced concentration of coexisting ions obtained in the first washing step is heat-treated in the presence of an acid, whereby a specific aluminum silica having a regular structure is obtained. Acid salts can be formed.

In the synthesis step, the solid isolate obtained in the first washing step may be appropriately diluted to synthesize as a dilute solution, or the solid isolate obtained in the first washing step may be synthesized as a high concentration solution. Also good.
By performing the synthesis step in a dilute solution, it is possible to obtain a specific aluminum silicate having a structure in which a regular structure extends in a tubular shape (hereinafter also referred to as “first specific aluminum silicate”). In addition, a specific aluminum silicate having a clay structure and an amorphous structure in addition to a regular structure (hereinafter, also referred to as “second specific aluminum silicate”) by performing the synthesis process in a high concentration solution. Can be obtained. In addition, it replaces with the 2nd specific aluminum silicate growing in the tubular thing 50 nm or more in length, and it is estimated that the formation of a clay structure and an amorphous structure is increasing.
Since both the first and second specific aluminum silicates have a specific regular structure, they exhibit excellent metal ion adsorption ability.

As conditions for diluting the solution when obtaining the first specific aluminum silicate in the synthesis step, for example, the silicon atom concentration can be 20 mmol / L or less and the aluminum atom concentration can be 60 mmol / L or less. Among these, from the viewpoint of metal ion adsorption ability, the dilution conditions are preferably such that the silicon atom concentration is 0.1 mmol / L or more and 10 mmol / L or less and the aluminum atom concentration is 0.1 mmol / L or more and 34 mmol / L or less. More preferably, the atomic concentration is from 0.1 mmol / L to 2 mmol / L and the aluminum atomic concentration is from 0.1 mmol / L to 7 mmol / L.
By setting the silicon atom concentration to 20 mmol / L or less and the aluminum atom concentration to 60 mmol / L or less as the dilution conditions, the first specific aluminum silicate can be efficiently produced.

Moreover, as a high concentration condition of the solution when obtaining the second specific aluminum silicate in the synthesis step, for example, the silicon atom concentration can be 100 mmol / L or more and the aluminum atom concentration can be 100 mmol / L or more. Among these, from the viewpoint of metal ion adsorption ability, as the high concentration condition, the silicon atom concentration is preferably 120 mmol / L or more and 2000 mmol / L or less, and the aluminum atom concentration is preferably 120 mmol / L or more and 2000 mmol / L or less. More preferably, it is 150 mmol / L or more and 1500 mmol / L or less and the aluminum atom concentration is 150 mmol / L or more and 1500 mmol / L or less.
As the high concentration condition, the second specific aluminum silicate can be efficiently produced by setting the silicon atom concentration to 100 mmol / L or more and the aluminum atom concentration to 100 mmol / L or more. Productivity is also improved.

In addition, the said silicon atom concentration and aluminum atom concentration are the silicon atom concentration and aluminum atom concentration in the solution after adding the acidic compound mentioned later and adjusting pH to a predetermined range.
In addition, the silicon atom concentration and the aluminum atom concentration are measured by an ordinary method using an ICP emission spectrometer (for example, ICP emission spectrometer: P-4010 manufactured by Hitachi, Ltd.).

  When adjusting so that the silicon atom concentration and the aluminum atom concentration become predetermined concentrations, a solvent may be added to the solution. As the solvent, those which are easily solvated with the raw material can be appropriately selected and used. Specifically, water, ethanol, or the like can be used as the solvent, and it is preferable to use water from the viewpoint of reducing the coexisting ions in the solution during the heat treatment and handling.

  In the synthesis step, at least one acidic compound is added to the solution before the heat treatment. The pH of the solution after adding the acidic compound is not particularly limited. From the viewpoint of efficiently obtaining the desired specific aluminum silicate, the pH of the solution is preferably 3 or more and less than 7, and more preferably 3 or more and 5 or less.

  The acidic compound added in the synthesis step is not particularly limited, and may be an organic acid or an inorganic acid. Among these, it is preferable to use an inorganic acid. Specific examples of the inorganic acid include hydrochloric acid, perchloric acid, nitric acid and the like. Considering the reduction of coexisting ion species in the solution during the subsequent heat treatment, it is preferable to use an acidic compound that generates an anion similar to the anion contained in the used aluminum source.

After adding an acidic compound to a solution, the specific aluminum silicate which has a desired structure can be obtained by performing heat processing.
The heating temperature is not particularly limited. From the viewpoint of efficiently obtaining the desired specific aluminum silicate, the heating temperature is preferably 80 ° C to 160 ° C.
There exists a tendency which can suppress that boehmite (aluminum hydroxide) precipitates that heating temperature is 160 degrees C or less. When the heating temperature is 80 ° C. or higher, the synthesis rate of the desired specific aluminum silicate is improved, and the desired specific aluminum silicate tends to be produced more efficiently.

The heating time is not particularly limited. From the viewpoint of more efficiently obtaining a specific aluminum silicate having a desired structure, the heating time is preferably within 96 hours (4 days).
When the heating time is 96 hours or less, the desired specific aluminum silicate can be more efficiently produced.

(D) Second washing step (desalting and solid separation)
The product obtained by heat treatment in the synthesis step is subjected to desalting and solid separation in the second washing step. Thereby, the specific aluminum silicate which has the outstanding metal ion adsorption ability can be obtained. This can be considered as follows, for example. In other words, the product obtained by heat treatment in the synthesis process may have a specific aluminum silicate adsorption site clogged with coexisting ions, and the expected metal ion adsorption capacity may not be obtained. is there. Therefore, excellent metal ion adsorption is achieved by performing a second washing step that removes at least a part of the coexisting ions from the specific aluminum silicate as a product obtained in the synthesis step by desalting and solid separation. It can be considered that a specific aluminum silicate having a function can be obtained.

In the second washing step, it is sufficient that at least a part of anions other than silicate ions and cations other than aluminum ions can be removed by washing (desalting and solid separation) treatment. The washing treatment applied in the second washing step may be the same operation as the first washing step before the synthesis step or a different operation.
The second washing step is preferably performed so that the concentration of coexisting ions is not more than a predetermined concentration. Specifically, for example, when the solid separated product obtained in the second washing step is dispersed in pure water so as to have a concentration of 60 g / L, the electrical conductivity of the dispersion is 4.0 S / m. It is preferable to carry out so that it is less than or equal to 1.0 mS / m or more and 3.0 S / m or less, more preferably 1.0 mS / m or more and 2.0 S / m or less. Is more preferable.
When the electrical conductivity of the dispersion is 4.0 S / m or less, it tends to be easy to obtain a specific aluminum silicate having a more excellent metal ion adsorption ability.

  When performing a 2nd washing | cleaning process using centrifugation, it can carry out as follows, for example. A solvent is added to the product obtained after the heat treatment to obtain a mixed solution. The pH is adjusted to 5 to 10 by adding alkali or the like to the mixed solution. After centrifuging the mixed solution whose pH has been adjusted, the supernatant solution is discharged and the solid is separated as a gel-like precipitate. The solid separated is then redispersed in a solvent. At that time, the volume of the dispersion is preferably returned to the volume before the centrifugation. The concentration of the coexisting ions can be reduced to a predetermined concentration or less by repeating the operations of desalting and solid separation by centrifugal separation of the redispersed dispersion in the same manner.

  In the second washing step, the pH of the mixed solution is preferably adjusted to 5 to 10, for example, and more preferably 8 to 10. The alkali used for pH adjustment is not particularly limited. As the alkali used for pH adjustment, sodium hydroxide, ammonia and the like are preferable.

  Centrifugation conditions are appropriately selected according to the production scale or the type or size of the container used. As conditions for centrifugation, for example, it can be 1 to 30 minutes at 1200 G or more at room temperature. Specific examples of the centrifugation conditions include, for example, when TOMY made by TOMY: Suprema23 and the company's standard rotor NA-16 are used as a centrifuge, at 3000 rpm (1450 G) or more at room temperature for 5 minutes to 10 minutes. can do.

  As the solvent in the second washing step, a solvent that can easily be solvated with the product after the heat treatment can be appropriately selected and used. Specifically, water, ethanol, or the like can be used as the solvent. it can. As the solvent, it is preferable to use water from the viewpoint of reducing coexisting ions and ease of handling, and it is more preferable to use pure water. In addition, when performing washing | cleaning of multiple times repeatedly, it is preferable to abbreviate | omit pH adjustment of a mixed solution.

  The number of treatments for desalting and solid separation in the second washing step may be set according to the remaining amount of coexisting ions. The number of treatments for desalting and solid separation is preferably 1 to 6 times, more preferably about 3 times. When the washing is repeated about 3 times, the residual amount of coexisting ions in the specific aluminum silicate is sufficiently reduced.

About the dispersion liquid after a 2nd washing | cleaning process, it is preferable that the density | concentration of the chloride ion and sodium ion which especially affect the adsorption capacity of specific aluminum silicate among the remaining coexisting ions is reduced. That is, when the specific aluminum silicate after washing in the second washing step is prepared by dispersing the specific aluminum silicate in water to prepare an aqueous dispersion having a concentration of 400 mg / L, chloride ions are contained in the aqueous dispersion. It is preferable to give a concentration of 100 mg / L or less and a sodium ion concentration of 100 mg / L or less. When the chloride ion concentration is 100 mg / L or less and the sodium ion concentration is 100 mg / L or less, the adsorption ability can be further improved. The chloride ion concentration is more preferably 50 mg / L or less, and still more preferably 10 mg / L or less. The sodium ion concentration is more preferably 50 mg / L or less, and still more preferably 10 mg / L or less. Chloride ion concentration and sodium ion concentration can be adjusted by the number of treatments in the washing step or the type of alkali used for pH adjustment.
The chloride ion concentration and the sodium ion concentration are measured under normal conditions by ion chromatography (for example, DX-320 and DX-100 manufactured by Dionex).
Moreover, the density | concentration of the dispersion of a specific aluminum silicate is based on the mass of the solid obtained by drying what was separated into solids at 110 degreeC for 24 hours.

  The “dispersion after the second washing step” described here means a dispersion in which the volume is returned to the volume before the second washing step after the second washing step by using a solvent. To do. As the solvent to be used, a solvent that easily solvates with the raw material can be appropriately selected and used. Specifically, water, ethanol or the like can be used, but the residual amount of coexisting ions in the specific aluminum silicate It is preferable to use water from the viewpoint of reduction of the amount and ease of handling.

  The BET specific surface area of the specific aluminum silicate is determined by the processing method of the second washing step (for example, adding alkali to the synthesis solution to adjust the pH to 5-10, centrifuging, then discharging the supernatant solution to form a gel The aluminum silicate remaining as a precipitate is redispersed in a solvent, and the process of returning to the volume before centrifugation can be adjusted by a method of repeating once or a plurality of times.

  The total pore volume of the specific aluminum silicate is determined by the processing method of the second washing step (for example, adding alkali to the synthesis solution to adjust the pH to 5-10, centrifuging, and discharging the supernatant solution). The aluminum silicate remaining as a gel-like precipitate is redispersed in a solvent, and the process of returning to the volume before centrifugation can be adjusted by repeating the process once or a plurality of times.

  In addition, the average pore diameter of the specific aluminum silicate is determined by the processing method of the second washing step (for example, adding alkali to the synthesis solution to adjust the pH to 5-10, centrifuging, and then discharging the supernatant solution. The aluminum silicate remaining as a gel-like precipitate is redispersed in a solvent, and the process of returning to the volume before centrifugation can be adjusted by repeating the process once or a plurality of times.

Preferred embodiments of the specific aluminum silicate include the following:
1) The element molar ratio Si / Al to Al is 0.4 or more and 0.6 or less,
Has a peak at 3ppm near the ²⁷ Al-NMR spectrum ^has a peak in the vicinity -78ppm near and -85ppm in 29 Si-NMR ^spectrum, the relative peak A near the -78ppm in 29 Si-NMR spectrum -85ppm The area ratio (peak B / peak A) of the nearby peak B is 2.0 or more and 9.0 or less,
The powder X-ray diffraction spectrum using CuKα ray as the X-ray source has peaks near 2θ = 26.9 ° and 40.3 °, and peaks near 2θ = 20 ° and 35 ° derived from the layered clay mineral. Aluminum silicate, which does not have
2) The elemental molar ratio Si / Al to Al is 0.4 or more and 0.6 or less,
Has a peak at 3ppm near the ²⁷ Al-NMR spectrum ^has a peak in the vicinity -78ppm near and -85ppm in 29 Si-NMR ^spectrum, the relative peak A near the -78ppm in 29 Si-NMR spectrum -85ppm The area ratio of peak B in the vicinity (peak B / peak A) is 2.0 or more and 4.0 or less,
The powder X-ray diffraction spectrum using CuKα ray as the X-ray source has peaks near 2θ = 26.9 ° and 40.3 °, and peaks near 2θ = 20 ° and 35 ° derived from the layered clay mineral. Aluminum silicate, which does not have
3) The elemental molar ratio Si / Al to Al is 0.45 or more and 0.55 or less,
Has a peak at 3ppm near the ²⁷ Al-NMR spectrum ^has a peak in the vicinity -78ppm near and -85ppm in 29 Si-NMR ^spectrum, the relative peak A near the -78ppm in 29 Si-NMR spectrum -85ppm The area ratio (peak B / peak A) of the nearby peak B is 2.0 or more and 5.0 or less,
The powder X-ray diffraction spectrum using CuKα ray as the X-ray source has peaks near 2θ = 26.9 ° and 40.3 °, and peaks near 2θ = 20 ° and 35 ° derived from the layered clay mineral. Aluminum silicate that does not have.

The above preferred embodiments 1) to 3) of the specific aluminum silicate may be the following more preferred embodiments:
4) Any of the above 1) to 3), wherein the BET specific surface area is 250 m ² / g or more, the total pore volume is 0.1 cm ³ / g or more and 1.0 m ² / g or less, and the average The pore diameter is 1.5 nm or more. 5) Any one of 1) to 3) above, wherein the BET specific surface area is 280 m ² / g or more, and the total pore volume is 0.1 cm ³ / g or more. It is 1.5 m ² / g or less and the average pore diameter is 1.5 nm or more and 20 nm or less. 6) It is any one of 1) to 3) above, and the BET specific surface area is 250 m ² / g or more and 1200 m ² /. g or less, the total pore volume is 0.1 cm ³ / g or more and 1.5 m ² / g or less, and the average pore diameter is 1.5 nm or more and 20 nm or less. 7) Any of 1) to 3) above The BET specific surface area is 280 m ² / g or more and 1000 m ² / G or less, the total pore volume is 0.1 cm ³ / g or more and 1.0 m ² / g or less, and the average pore diameter is 1.5 nm or more and 5.0 nm or less.

[Separator substrate]
If the separator base material which comprises a separator is a porous base material, there will be no restriction | limiting in particular, From the separator base material used normally, it can select suitably and can be used. The porous substrate is not particularly limited as long as it has a large number of pores or voids inside and has a porous structure in which these pores are connected to each other. Examples of the porous substrate include a microporous film, a nonwoven fabric, a paper sheet, and other sheets having a three-dimensional network structure. Among these, a microporous membrane is preferable from the viewpoint of handling properties or strength. As the material constituting the porous substrate, both organic materials and inorganic materials can be used, but thermoplastic resins such as polyolefin resins are preferable from the viewpoint of obtaining shutdown characteristics. Therefore, if such a polyolefin porous substrate is applied, both heat resistance and a shutdown function can be achieved.

Examples of the polyolefin resin include polyethylene, polypropylene, polymethylpentene, and the like. Among them, those containing 90% by mass or more of polyethylene are preferable from the viewpoint of obtaining good shutdown characteristics. The polyethylene may be any of low density polyethylene, high density polyethylene and ultra high molecular weight polyethylene. In particular, it is preferable to include at least one selected from high-density polyethylene and ultrahigh-molecular-weight polyethylene, and more preferably polyethylene composed of a mixture of high-density polyethylene and ultra-high-molecular-weight polyethylene. Such polyethylene is excellent in strength and moldability.
The molecular weight of polyethylene is preferably 100,000 to 10,000,000 in terms of weight average molecular weight, and particularly preferably a polyethylene composition containing at least 1% by mass of ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more.
In addition, the porous substrate in the present invention may be constituted by mixing other polyolefins such as polypropylene and polymethylpentene in addition to polyethylene, or two or more layers of a polyethylene microporous membrane and a polypropylene microporous membrane. You may comprise as a laminated body.

  The film thickness of the porous substrate is not particularly limited. For example, the range of 5-50 micrometers is preferable, and 7-30 micrometers is more preferable. When the film thickness is 5 μm or more, sufficient strength is obtained, good handling properties are obtained, and the yield of the battery is improved. Further, when the film thickness is 50 μm or less, ion mobility is improved, the volume occupied by the separator in the battery is suppressed, and the energy density of the battery is improved.

  The porosity of the porous substrate is not particularly limited. For example, 10% to 60% is preferable, and 20% to 50% is more preferable. When the porosity is 10% or more, a sufficient amount of electrolytic solution for the operation of the battery can be retained, and good charge / discharge characteristics can be obtained. Further, when the porosity is 60% or less, good shutdown characteristics can be obtained, and further sufficient strength can be obtained. As the porosity of the porous body, a porosity obtained by a mercury intrusion method using PoreMaster 60GT manufactured by QUANTACHROME is used.

The puncture strength of the separator is a value converted to a thickness of 20 μm, and is preferably in the range of 0.020 N / cm ² or more and 0.061 N / cm ² or less. When the puncture strength is 0.020 N / cm ² or more, sufficient strength for suppressing the occurrence of a short circuit can be obtained. Moreover, the fall of ion conductivity can be suppressed as it is 0.061 N / cm < ² > or less. As the piercing strength of the porous body, one obtained by Shimadzu Corporation precision universal testing machine AGS-X is used.

  The Gurley value (JIS P8117) of the porous substrate is preferably in the range of 100 seconds / 100 ml to 500 seconds / 100 ml, more preferably in the range of 100 seconds / 100 ml to 300 seconds / 100 ml. When the Gurley value is 100 seconds / 100 ml or more, good shutdown characteristics or mechanical strength can be obtained. Further, when the Gurley value is 500 seconds / 100 ml or less, good ion permeability is obtained and the load characteristics of the battery are improved.

  The average pore size of the porous substrate is preferably 10 nm to 100 nm. When the average pore diameter is 10 nm or more, the impregnation property of the electrolytic solution is improved. When the average pore size is 100 nm or less, good shutdown characteristics can be obtained.

The separator should just contain the separator base material and at least 1 sort (s) of specific aluminum silicate, and another structure is not restrict | limited in particular.
Examples of a method for obtaining a separator containing a specific aluminum silicate include a method of impregnating a separator base material with a dispersion of a specific aluminum silicate, a method of applying a specific aluminum silicate dispersion to a separator base material, and the like. be able to. Furthermore, after impregnating or applying the dispersion of the specific aluminum silicate to the separator substrate, drying may be performed as necessary. Thereby, the separator by which the layer containing specific aluminum silicate was formed in the surface of a separator base material can be obtained.

  When the layer containing the specific aluminum silicate is formed on the surface of the separator substrate, it may be only one surface or both surfaces of the separator substrate. When forming only on one side of the separator base, it may be on either the positive side or the negative side. In view of elution of metal ions from the positive electrode or reduction of metal ions in the negative electrode and precipitation of metal, it is preferable to form at least the surface on the positive electrode side, and more preferably on both surfaces.

  The solvent of the dispersion liquid containing the specific aluminum silicate is not particularly limited. Examples of the solvent for the dispersion include water, amide solvents such as 1-methyl-2-pyrrolidone, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2 -Alcohol solvents, such as methyl-2-propanol, etc. can be mentioned.

  Moreover, the density | concentration of the specific aluminum silicate in a dispersion liquid can be suitably selected as needed. For example, it can be 0.01 mass%-50 mass%, and it is preferable that it is 1 mass%-20 mass%.

  The dispersion preferably further contains a binder. The specific aluminum silicate is immobilized on the separator by the binder containing the specific aluminum silicate dispersion. For this reason, when producing a battery, since specific aluminum silicate does not fall off and can exist on the separator surface at the time of charging / discharging, it can adsorb | suck an impurity ion efficiently.

  Although it does not restrict | limit especially as a binder contained in the said dispersion liquid, It is preferable that it is the same as that used for a positive electrode material layer or a negative electrode material layer as a binder from a viewpoint of the constituent material of a battery. Although it does not specifically limit as a binder, Styrene-butadiene copolymer; Ethylenic nonpolymers, such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, hydroxyethyl (meth) acrylate, etc. (Meth) acrylic copolymers obtained by copolymerizing saturated carboxylic acid esters and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid; polyvinylidene fluoride; And polymer compounds such as polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polyimide, and polyamideimide.

The content ratio of the binder in the layer containing the specific aluminum silicate is preferably 0.1 parts by mass to 15 parts by mass with respect to a total of 100 parts by mass of the specific aluminum silicate and the binder. It is more preferable that it is 10 mass parts.
When the content ratio of the binder is 0.1 parts by mass or more, the specific aluminum silicate is effectively fixed to the positive electrode, and the effect of providing the specific aluminum silicate is continuously obtained. On the other hand, the metal adsorption | suction efficiency per mass can be improved because it is 15 mass parts or less.

The content of the specific aluminum silicate in the separator, it is preferable from the viewpoint of short circuit suppression ^{is 0.01g / m 2 ~50g / m 2} , 0.1g / m 2 ~20g / m 2 It is more preferable that

  The method for applying the dispersion to the separator substrate is not particularly limited. Examples of the coating method include known methods such as a metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method, and screen printing method.

  Further, as another method for obtaining a separator containing the specific aluminum silicate, for example, it is obtained after adding the specific aluminum silicate in a solid state or a dispersion state to a resin composition constituting the separator base material. The method of forming a separator using the resin composition base material containing the specific aluminum silicate can be mentioned. Thereby, the separator comprised from the separator base material containing specific aluminum silicate can be obtained.

The content of the specific aluminum silicate in the separator which is composed of a separator substrate including the specific aluminum silicates, from the viewpoint of short circuit control and the internal resistance suppressing, at 0.01g ^/ m ² ~50g / m 2 preferably ^there, and more preferably ^{0.1g / m 2 ~20g / m 2} .

  As a specific method for forming a separator substrate using a resin composition containing a specific aluminum silicate, for example, refer to the description of paragraph numbers [0063] to [0122] of JP-A-2008-146963. be able to.

The said lithium ion secondary battery separator can comprise a lithium ion secondary battery with a negative electrode, a positive electrode, and electrolyte. If the said separator for lithium ion secondary batteries is arrange | positioned between both electrodes of a positive electrode and a negative electrode, it will not restrict | limit in particular and can be used by a normal method.
The lithium ion secondary battery using the lithium ion secondary battery separator of the present invention will be described below.

[Negative electrode]
The negative electrode constituting the lithium ion secondary battery is configured, for example, by forming a negative electrode material layer on at least one surface of the current collector surface.

  As the current collector in the negative electrode, a normal current collector used for a negative electrode for a lithium ion secondary battery can be applied. For example, a metal or an alloy such as aluminum, copper, nickel, titanium, and stainless steel is foil-shaped. Further, a belt-like one having a perforated foil shape, a mesh shape, or the like can be used. A porous material can also be used. Examples of the porous material include porous metal (foamed metal) and carbon paper.

The negative electrode material layer is provided on the current collector and contains a negative electrode active material.
As a negative electrode active material, the normal thing used for the negative electrode for lithium ion secondary batteries is applicable. Examples of the negative electrode active material include carbon materials that can be doped or intercalated with lithium ions, metal compounds, metal oxides, metal sulfides, and conductive polymer materials. As the negative electrode active material, natural graphite, artificial graphite, silicon, lithium titanate and the like can be used singly or in combination of two or more.

  The negative electrode is prepared by, for example, kneading a negative electrode material for a lithium ion secondary battery and a binder together with a solvent by a dispersing device such as a stirrer, a ball mill, a super sand mill, a pressure kneader to prepare a negative electrode material slurry, It can be obtained by forming a negative electrode material layer by applying it to a body, or forming a paste-like negative electrode material slurry into a sheet shape, a pellet shape or the like and integrating it with a current collector.

  The binder is not particularly limited. As the binder, styrene-butadiene copolymer; ethylenically unsaturated carboxylic acid ester such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, hydroxyethyl (meth) acrylate, and the like , (Meth) acrylic copolymers obtained by copolymerization with ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin , Polymer compounds such as polyphosphazene, polyacrylonitrile, polyimide, and polyamideimide;

The content ratio of the binder in the negative electrode material layer of the negative electrode is preferably 0.5 part by mass to 20 parts by mass with respect to a total of 100 parts by mass of the negative electrode material for the lithium ion secondary battery and the binder, and preferably 1 part by mass to 1 part by mass. It is more preferable that it is 10 mass parts.
Adhesiveness is good when the content ratio of the binder is 0.5 mass or more, and destruction of the negative electrode due to expansion or contraction during charge / discharge is suppressed. On the other hand, it can suppress that electrode resistance becomes large because it is 20 mass% or less.

  Further, a thickener may be added to the negative electrode material slurry in order to adjust the viscosity. As the thickener, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, casein and the like can be used.

  Moreover, you may mix a conductive support material with the said negative electrode material slurry as needed. Examples of the conductive auxiliary material include carbon black, graphite, acetylene black, conductive oxide, and conductive nitride. The usage-amount of a conductive auxiliary material should just be about 0.1 mass%-20 mass% with respect to a negative electrode material.

The method for applying the negative electrode material slurry to the current collector is not particularly limited. Examples of the application method include known methods such as a metal mask printing method, electrostatic coating method, dip coating method, spray coating method, roll coating method, doctor blade method, gravure coating method, and screen printing method. After the application of the negative electrode material slurry, it is preferable to perform a rolling process using a flat plate press, a calender roll, or the like as necessary.
Further, the integration of the negative electrode material slurry formed into a sheet shape, a pellet shape or the like and the current collector can be performed by a known method such as a roll, a press, or a combination thereof.

  The thickness of the negative electrode layer is generally 1 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less.

The negative electrode material layer formed on the current collector and the negative electrode material layer integrated with the current collector are preferably heat-treated according to the binder used. For example, when a binder having polyacrylonitrile as the main skeleton is used, heat treatment is preferably performed at 100 ° C. to 180 ° C., and when using a binder having polyimide or polyamideimide as the main skeleton at 150 ° C. to 450 ° C. .
This heat treatment increases the strength by removing the solvent and curing the binder, and the adhesion between the particles and between the particles and the current collector can be improved. Note that these heat treatments are preferably performed in an inert atmosphere such as helium, argon, nitrogen, or a vacuum atmosphere in order to prevent oxidation of the current collector during the treatment.

Moreover, it is preferable that the negative electrode is pressure-pressed (pressure treatment) after the heat treatment. The electrode density can be adjusted by applying pressure treatment. For example, a negative electrode using natural graphite as the negative electrode material is preferably electrode density of ^{1.0g / cm 3 ~2.0g / cm 3} . About electrode density, volume capacity improves, so that it is high.

[Positive electrode]
The positive electrode can be obtained by forming a positive electrode material layer on the current collector surface in the same manner as the negative electrode. As the current collector, for example, a band-shaped material in which a metal or an alloy such as aluminum, copper, nickel, titanium, or stainless steel is formed into a foil shape, a punched foil shape, a mesh shape, or the like can be used. A porous material can also be used. Examples of the porous material include porous metal (foamed metal) and carbon paper.

The positive electrode active material used for the positive electrode material layer may be, for example, a metal compound, metal oxide, metal sulfide, or conductive polymer material that can be doped or intercalated with lithium ions, and is not particularly limited. Specifically, as the positive electrode active material, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and their double oxides (LiCo _x Ni _y Mn _z O _2). , X + y + z = 1, 0 <x, 0 <y; LiNi _2-x Mn _x O ₄ , 0 <x ≦ 2), lithium manganese spinel (LiMn ₂ O ₄ ); lithium vanadium compound, V ₂ O ₅ , V ₆ O ₁₃ , VO ₂ , MnO ₂ , TiO ₂ , MoV ₂ O ₈ , TiS ₂ , V ₂ S ₅ , VS ₂ , MoS ₂ , MoS ₃ , Cr ₃ O ₈ , Cr ₂ O ₅ , olivine type LiMPO ₄ (M : Co, Ni, Mn, Fe); conductive polymer such as polyacetylene, polyaniline, polypyrrole, polythiophene, polyacene; porous carbon Can be used alone or in admixture of two or more.

[Electrolyte]
The electrolytic solution used for the lithium ion secondary battery is not particularly limited, and a known one can be used. For example, a non-aqueous lithium ion secondary battery can be manufactured by using an electrolytic solution in which an electrolyte is dissolved in an organic solvent.

As _{the electrolyte, LiPF 6, LiClO 4, LiBF} 4, LiClF 4, LiAsF 6, LiSbF 6, LiAlO 4, LiAlCl 4, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, LiC Examples thereof include lithium salts such as (CF ₃ SO ₂ ) ₃ , LiCl, and LiI.
The concentration of the electrolyte is not particularly limited. The concentration of the electrolyte is preferably 0.3 to 5 mol, more preferably 0.5 to 3 mol, and more preferably 0.8 to 1.5 mol with respect to 1 L of the electrolyte. It is particularly preferred.

Examples of the organic solvent include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, dipropyl Carbonate solvents such as carbonate; lactone solvents such as γ-butyrolactone; ester solvents such as methyl acetate and ethyl acetate; chain ether solvents such as 1,2-dimethoxyethane, dimethyl ether and diethyl ether; tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane Cyclic ether solvents such as 4-methyldioxolane; ketone solvents such as cyclopentanone; Sulfolane solvents such as lan, 3-methylsulfolane, 2,4-dimethylsulfolane; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile, propionitrile, benzonitrile; N, N-dimethylformamide, N, N-dimethyl Aprotic solvents such as amide solvents such as acetamide; urethane solvents such as 3-methyl-1,3-oxazolidine-2-one; polyoxyalkylene glycol solvents such as diethylene glycol;
An organic solvent may be used individually by 1 type, and may be used as a 2 or more types of mixed solvent.

The structure of the lithium ion secondary battery is not particularly limited. Usually, a positive electrode and a negative electrode, and a separator provided as necessary, are wound into a flat spiral shape to form a wound electrode group, In general, the electrode plates are laminated to form a laminated electrode plate group, and the electrode plate group is enclosed in an exterior body.
Although the form of a lithium ion secondary battery is not specifically limited, Lithium ion secondary batteries, such as a paper-type battery, a button-type battery, a coin-type battery, a laminated battery, a cylindrical battery, a square battery, are mentioned.

  Next, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[Production Example 1]
<Production of specific aluminum silicate>
A concentration: 350 mmol / L sodium orthosilicate aqueous solution (500 mL) was added to a 700 mmol / L aluminum chloride aqueous solution (500 mL), and the mixture was stirred for 30 minutes. To this solution, 330 mL of an aqueous sodium hydroxide solution having a concentration of 1 mol / L was added to adjust the pH to 6.1.

After the pH-adjusted solution was stirred for 30 minutes, centrifugal separation was carried out for 5 minutes at a rotational speed of 3,000 rpm using a TOMY Corporation: Superma23 and standard rotor NA-16 as a centrifugal separator. After centrifugation, the supernatant solution was discharged, the gel precipitate was redispersed in pure water, and returned to the volume before centrifugation. Such desalting treatment by centrifugation was performed three times.
The gel-like precipitate obtained after the desalting treatment of the third supernatant was dispersed in pure water so as to have a concentration of 60 g / L, and HORIBA: F-55 and electric conductivity cell: 9382-10D were used. The electrical conductivity measured at room temperature (25 ° C.) was 1.3 S / m.

135 mL of hydrochloric acid having a concentration of 1 mol / L was added to the gel-like precipitate obtained after the supernatant was discharged for the third time in the desalting treatment, and the pH was adjusted to 3.5, followed by stirring for 30 minutes. When the silicon atom concentration and the aluminum atom concentration in the solution at this time were measured by an ordinary method using an ICP emission spectrometer: P-4010 (manufactured by Hitachi, Ltd.), the silicon atom concentration was 213 mmol / L, aluminum The concentration of atoms was 426 mmol / L.
The solution was then placed in a dryer and heated at 98 ° C. for 48 hours (2 days).

188 mL of a 1 mol / L sodium hydroxide aqueous solution was added to the solution after heating (aluminum silicate concentration 47 g / L) to adjust the pH to 9.1. By adjusting the pH, the aluminum silicate in the solution was aggregated, and the aggregate was precipitated by the same centrifugation as described above, and then the supernatant was discharged. The desalting process of adding pure water to the precipitate after discharging the supernatant and returning to the volume before centrifugation was performed three times.
The gel-like precipitate obtained after the desalting treatment of the third supernatant was dispersed in pure water so as to have a concentration of 60 g / L, and HORIBA: F-55 and electric conductivity cell: 9382-10D were used. The electrical conductivity measured at room temperature (25 ° C.) was 0.6 S / m.

  The gel-like precipitate obtained after the third desalting of the desalting treatment was dried at 60 ° C. for 16 hours to obtain 30 g of powder. This powder was designated as sample A.

<BET specific surface area, total pore volume, average pore diameter>
The BET specific surface area, total pore volume, and average pore diameter of Sample A were measured based on the nitrogen adsorption ability. For the evaluation apparatus, QUANTACHROME: AUTOSORB-1 (trade name) was used. When performing these measurements, after pre-treatment of the sample described later, the evaluation temperature is 77K, and the evaluation pressure range is less than 1 in relative pressure (equilibrium pressure with respect to the saturated vapor pressure).

  As pretreatment, the measurement cell charged with 0.05 g of sample A was automatically deaerated and heated with a vacuum pump. The detailed conditions of this treatment were set such that the pressure was reduced to 10 Pa or less, heated at 110 ° C., held for 3 hours or more, and then naturally cooled to room temperature (25 ° C.) while maintaining the reduced pressure.

As a result of the evaluation, the BET specific surface area of Sample A was 363 m ² / g, the total pore volume was 0.22 cm ³ / g, and the average pore diameter was 2.4 nm.

^<27 Al-NMR>
^The measurement was performed under the following conditions using a Bruker BioSpin AV400WB model as a ²⁷ Al-NMR spectrum measuring apparatus.
Resonance frequency: 104MHz
Measuring method: MAS (single pulse)
MAS rotation speed: 10 kHz
Measurement area: 52 kHz
Number of data points: 4096
resolution (measurement area / number of data points): 12.7 Hz
Pulse width: 3.0 μsec
Delay time: 2 seconds Chemical shift value standard: 3.94 ppm of α-alumina
window function: exponential function Line Broadening coefficient: 10 Hz

FIG. 1 shows the ²⁷ Al-NMR spectrum of Sample A. As shown in FIG. 1, it had a peak around 3 ppm. A slight peak was observed around 55 ppm. The area ratio of the peak near 55 ppm to the peak near 3 ppm was 15%.

^<29 Si-NMR>
^{As a 29} Si-NMR spectrum measuring apparatus, an AV400WB type manufactured by Bruker BioSpin was used, and measurement was performed under the following conditions.
Resonance frequency: 79.5 MHz
Measuring method: MAS (single pulse)
MAS rotation speed: 6 kHz
Measurement area: 24 kHz
Number of data points: 2048
resolution (measurement area / number of data points): 5.8 Hz
Pulse width: 4.7 μsec
Delay time: 600 sec chemical shift value criterion: _TMSP-d 4 (3- (trimethylsilyl) (2,2,3,3- ² H ₄₎ propionate) 1.52Ppm the
window function: exponential function Line Broadening coefficient: 50 Hz

FIG. 2 shows the ²⁹ Si-NMR spectrum of Sample A. As shown in FIG. 2, there were peaks at around -78 ppm and around -85 ppm. The peak areas around -78 ppm and -85 ppm were measured by the above method. As a result, when the area of the peak A at −78 ppm was 1.00, the area of the peak B at −85 ppm was 2.61.

<Element molar ratio Si / Al>
The elemental molar ratio Si / Al of Si and Al determined from a conventional ICP emission spectroscopic analysis (ICP emission spectroscopic apparatus: P-4010 (manufactured by Hitachi, Ltd.)) was 0.5.

<Powder X-ray diffraction>
Powder X-ray diffraction was performed using Rigaku Corporation: Geigerflex RAD-2X (trade name) and CuKα rays as an X-ray source. FIG. 3 shows a powder X-ray diffraction spectrum of Sample A. Broad peaks were observed around 2θ = 26.9 ° and around 40.3 °. In addition, sharp peaks were observed in the vicinity of 2θ = 18.8 °, 20.3 °, 27.8 °, 40.6 °, and 53.3 °. In addition, no broad peaks were observed around 2θ = 20 ° and 35 °.

<Transmission electron microscope (TEM) photo observation>
FIG. 4 shows a transmission electron microscope (TEM) photograph of sample A observed at a magnification of 100,000. The TEM observation was performed at an acceleration voltage of 100 kV using a transmission electron microscope (H-7100FA type, manufactured by Hitachi High-Technologies Corporation). A sample A to be observed with TEM was prepared as follows. That is, the solution after heating (aluminum silicate concentration of 47 g / L) before the final desalting treatment process was diluted 10 times with pure water and subjected to ultrasonic irradiation for 5 minutes. It was prepared by dropping it onto a support and then drying it naturally to form a thin film.
As shown in FIG. 4, there is no tubular object having a length of 50 nm or more.

<Moisture content>
The moisture content of sample A was heated at 120 ° C. under atmospheric pressure, held for 6 hours, and then measured by the Karl Fischer method. As a result, it was 3% by mass.

<Metal ion adsorption capacity 1 in water>
Metal ion adsorption ability evaluation was performed by ICP emission spectroscopic analysis (ICP emission spectroscopic device: P-4010 (manufactured by Hitachi, Ltd.)).
In evaluating the metal ion adsorption capacity, first, a 100 ppm metal ion solution was prepared for each of Li ⁺ , Ni ^2+, or Mn ²⁺ using each metal sulfate and pure water. Sample A was added to the prepared solution so that the final concentration was 1.0% by mass, mixed well, and then allowed to stand. Then, each metal ion concentration before and after the addition of sample A was measured by ICP emission spectroscopic analysis. The results are shown in Table 1.

Concerning metal ion adsorption capacity, the concentration after addition of sample A was less than 5 ppm for Ni ²⁺ and 10 ppm for Mn ²⁺ . In contrast, Li ⁺ was hardly adsorbed at 90 ppm. Therefore, sample A adsorbs Ni ²⁺ and Mn ²⁺ unnecessary for the lithium ion secondary battery, but hardly absorbs Li ⁺ essential for charge and discharge, and can suppress short circuit without impairing battery performance. .

  As comparative controls, the following Sample B, Sample C, and Sample D were prepared, and the metal ion adsorption ability was evaluated. The results are shown in Table 1.

Sample B was a commercially available activated carbon (manufactured by Wako Pure Chemical Industries, activated carbon, crushed, 2 mm to 5 mm). Regarding the metal ion adsorption capacity in water, the concentrations after addition of Sample B were 50 ppm for Ni ²⁺ , 60 ppm for Mn ²⁺ , and 100 ppm for Li ⁺ .

Sample C was a commercially available silica gel (manufactured by Wako Pure Chemical Industries, Ltd., small granular (white)). Regarding the metal ion adsorption ability in water, the concentrations after addition of Sample C were 100 ppm for Ni ²⁺ , 100 ppm for Mn ²⁺ , and 80 ppm for Li ⁺ .

Sample D was commercially available zeolite 4A (manufactured by Wako Pure Chemical Industries, Ltd., molecular sieves 4A, element molar ratio Si / Al = 1.0). Concerning metal ion adsorption ability in water, the concentrations after addition of sample D were 30 ppm for Ni ²⁺ , 10 ppm for Mn ²⁺ , and 60 ppm for Li ⁺ .
The Mn ²⁺ solution to which zeolite 4A was added turned brown and turbid when left standing.

<Metal ion adsorption capacity 2 in water>
The sample A prepared in Production Example 1 was used, and the amount of sample A added was changed as shown in Table 2 below, except that the metal ion adsorption in water was performed by the method described in “Metal ion adsorption capacity 1 in water”. Noh was evaluated. The results are shown in Table 2 below.

  As shown in Table 2, when 0.5% by mass of sample A was added, the manganese ion concentration was halved. When 2.0% by mass of sample A was added, 95% of manganese ions were trapped.

<Metal ion adsorption capacity 3 in water>
Using the sample A prepared in Production Example 1, except that the metal ion species was changed to Cu ²⁺ and the metal ion adjustment concentration was changed to 400 ppm, the method described in “Metal ion adsorption capacity 1 in water” was used. Metal ion adsorption ability was evaluated. The pH at this time was 5.1. The concentration after addition of Sample A was 160 ppm for Cu ²⁺ .

[Production Example 2]
<Production of specific aluminum silicate>
A concentration: 74 mmol / L sodium orthosilicate aqueous solution (500 mL) was added to an aluminum chloride aqueous solution (500 mL) having a concentration of 180 mmol / L, followed by stirring for 30 minutes. To this solution, 93 mL of a 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 7.0.

  After the pH-adjusted solution was stirred for 30 minutes, centrifugal separation was carried out for 5 minutes at a rotational speed of 3,000 rpm using a TOMY Corporation: Superma23 and standard rotor NA-16 as a centrifugal separator. After centrifugation, the supernatant solution was discharged, the gel precipitate was redispersed in pure water, and returned to the volume before centrifugation. Such desalting treatment by centrifugation was performed three times.

  The gel-like precipitate obtained after the third desalting of the desalting treatment was adjusted to a concentration of 60 g / L, and it was used at normal temperature using HORIBA: F-55 and conductivity cell: 9382-10D. The electrical conductivity was measured at 25 ° C. and found to be 1.3 S / m.

Pure water was added to the gel-like precipitate obtained after the third desalting of the desalting treatment to make the volume 12 L. The solution was adjusted to pH = 4.0 by adding 60 mL of hydrochloric acid having a concentration of 1 mol / L and stirred for 30 minutes. When the silicon atom concentration and the aluminum atom concentration in the solution at this time were measured using an ICP emission spectrometer: P-4010 (manufactured by Hitachi, Ltd.), the silicon atom concentration was 2 mmol / L and the aluminum atom concentration was 4 mmol. / L.
The solution was then placed in a dryer and heated at 98 ° C. for 96 hours (4 days).

  To the solution after heating (aluminum silicate concentration 0.4 g / L), 60 mL of a 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH to 9.0. The solution was agglomerated by adjusting the pH, and the agglomerate was precipitated by the same centrifugation as in the first washing step, whereby the supernatant was discharged. The desalting process of adding pure water to this and returning to the volume before centrifugation was performed 3 times.

  The gel-like precipitate obtained after the third desalting of the desalting treatment was adjusted to a concentration of 60 g / L, and it was used at normal temperature using HORIBA: F-55 and conductivity cell: 9382-10D. When the electric conductivity was measured at 25 ° C., it was 0.6 S / m.

  The gel-like precipitate obtained after the desalting treatment was dried at 60 ° C. for 72 hours (3 days) to obtain 4.8 g of powder. This powder was designated as Sample E.

^<27 Al-NMR>
FIG. 1 shows the ²⁷ Al-NMR spectrum of Sample E. As shown in FIG. 1, it had a peak around 3 ppm. A slight peak was observed around 55 ppm. The area ratio of the peak around 55 ppm to the peak around 3 ppm was 4%.

^<29 Si-NMR>
FIG. 2 shows the ²⁹ Si-NMR spectrum of Sample E. As shown in FIG. 2, there were peaks near −78 ppm and −85 ppm. The peak areas around -78 ppm and -85 ppm were measured by the above method. As a result, when the area of peak A near -78 ppm was 1.00, the area of peak B near -85 ppm was 0.44.

<Element molar ratio Si / Al>
The elemental molar ratio Si / Al of Si and Al determined from a conventional ICP emission spectroscopic analysis (ICP emission spectroscopic apparatus: P-4010 (manufactured by Hitachi, Ltd.)) was 0.5.

<Powder X-ray diffraction>
Powder X-ray diffraction of Sample E was performed in the same manner as in Production Example 1. In FIG. 3, the spectrum of the powder X-ray diffraction of the sample E is shown. It had broad peaks around 2θ = 4.8 °, 9.7 °, 14.0 °, 18.3 °, 27.3 °, and 40.8 °. In addition, no broad peaks were observed around 2θ = 20 ° and 35 °.

<BET specific surface area, total pore volume, average pore diameter>
In the same manner as in Production Example 1, the BET specific surface area, the total pore volume, and the average pore diameter were measured based on the nitrogen adsorption ability.
As a result of the evaluation, the BET specific surface area of Sample E was 323 m ² / g, the total pore volume was 0.22 cm ³ / g, and the average pore diameter was 2.7 nm.

<Transmission electron microscope (TEM) photo observation>
FIG. 5 shows a transmission electron microscope (TEM) photograph of Sample E observed at a magnification of 100,000 by the same method as in Example 1. As shown in FIG. 5, a tubular product is generated, and the length of the tubular body 10a in the tube portion length direction is about 1 nm to 10 μm, the outer diameter is about 1.5 nm to 3.0 nm, and the inner diameter is Was about 0.7 nm to 1.4 nm.

<Moisture content>
The moisture content of Sample E was heated at 120 ° C. under atmospheric pressure, held for 6 hours, and then measured by the Karl Fischer method. As a result, it was 3% by mass.

<Metal ion adsorption capacity in water>
When the Mn ²⁺ ion adsorption ability in water was evaluated in the same manner as in Production Example 1, Sample E showed the same metal ion adsorption ability as Sample A.

[Example 1]
<Preparation of separator for lithium ion secondary battery>
Dispersion of specific aluminum silicate by adding polyvinylidene fluoride as a binder to 8% by mass aqueous dispersion of specific aluminum silicate (sample A) prepared in Production Example 1 to 5% by mass with respect to sample A A liquid was prepared. The obtained specific aluminum silicate dispersion was applied to one side of a 25 μm thick polyethylene porous sheet by the doctor blade method and dried at 100 ° C. under vacuum. This was designated as separator A. The amount of sample A applied to separator A was 5 g / m ² .

<Production of lithium ion secondary battery>
An aluminum laminate cell was prepared by using LiPF ₆ dissolved in a mixed solvent of diethyl carbonate and ethylene carbonate in a volume ratio of 1: 1 to a concentration of 1 mol / l as an electrolytic solution. An aluminum laminate cell is a lithium ion secondary that uses a three-layer laminate film made of nylon film-aluminum foil-modified polyolefin film as an exterior material, and encloses the positive electrode, negative electrode, separator, electrolyte, etc. in the exterior material. A battery (hereinafter also simply referred to as a “cell”).
Here, the lithium ion secondary battery was configured such that the surface of the separator A provided with the specific aluminum silicate was on the positive electrode side.

<Measurement of battery characteristics>
About the produced lithium ion secondary battery, the initial stage capacity | capacitance, charging / discharging characteristic, and impedance were measured with the following method. Then, after being left in a thermostatic bath at 50 ° C. for 1 week, charge / discharge measurement and impedance measurement were performed again.

(Measurement of initial capacity)
0 is obtained when the prepared lithium ion secondary battery is connected to a charge / discharge measuring device (TOSCAT-3100 manufactured by Toyo System Co., Ltd.) and calculated from the amount of active material, and the theoretical current value reaching full charge in 1 hour is 1C. The battery was charged at a constant current until a current value of 4.2 C reached 4.2 V, and then charged at a constant voltage of 4.2 V until the current value reached 0.01 mA. After standing for 30 minutes after the end of charging, constant current discharge was performed at a current value of 0.2 C until the lithium ion secondary battery reached 3V. After the end of discharging, it was left for 30 minutes until the next charge. The discharge capacity at the second time when the above operation was performed twice was defined as the discharge capacity of the battery.
The cell produced using the separator to which sample A was applied showed similar initial capacity compared to the cell produced using the separator to which sample A was not applied.

(Measurement of charge / discharge characteristics)
The battery was charged with a constant current until it reached 4.2 V with a current value of 0.2 C, and then was charged with a constant voltage at 4.2 V until the current value reached 0.01 mA. After standing for 30 minutes after the completion of charging, constant current discharge was performed at a current value of 0.5 C until the lithium ion secondary battery reached 3V. The discharge capacity was measured with the current values of 1C, 2C, 3C, and 5C after charging under the same charging conditions, and the dependence of the discharge capacity on the discharge conditions was evaluated.
The cell produced using the separator to which the sample A was applied was compared with the cell produced using the separator to which the sample A was not applied. The rate of decrease in capacity became smaller.

(Impedance measurement)
After leaving the lithium ion secondary battery after measuring the charge / discharge characteristics for 30 minutes, measure the Cole-Cole Plot using a digital multimeter (a combination of HZ-5000 and a frequency response analyzer manufactured by Hokuto Denko), The impedance at a frequency of 1 kHz was compared as a representative value.
The cell produced using the separator to which the sample A was applied had a smaller impedance increase rate after standing at 50 ° C. for 1 week than the cell produced using the separator to which the sample A was not applied. .

  From the measurement results of the initial capacity, charge / discharge characteristics, and impedance, it can be seen that the sample A in the cell contributed to the improvement of the life and safety of the cell by, for example, adsorbing impurities eluted from the positive electrode. .

  Further, when a separator was prepared in the same manner except that the sample E was used instead of the sample A and evaluated in the same manner, the same result as that of the sample A was obtained.

10 Specific aluminum silicate 10a Tubular body 20 Inner wall 30 Crevice

Claims (7)

A separator substrate;
Aluminum (Al) Ri elemental molar ratio Si / Al is 0.3 to 1.0 below der of silicon (Si) ^for, has a peak at 3ppm near the 27 Al-NMR spectrum, disposed on the separator substrate surface With aluminum silicate ,
A separator for a lithium ion secondary battery. 2. The lithium ion secondary battery separator according to claim 1 , wherein the aluminum silicate has peaks at around −78 ppm and around −85 ppm in a ²⁹ Si-NMR spectrum. The aluminum silicate has an area ratio (peak B / peak A) of the peak B near -85 ppm to the peak A near -78 ppm in the ²⁹ Si-NMR spectrum is 2.0 or more and 9.0 or less. The separator for lithium ion secondary batteries according to claim 2 .   4. The separator for a lithium ion secondary battery according to claim 1, wherein the element molar ratio Si / Al of the aluminum silicate is not less than 0.4 and not more than 0.6. 5.   The aluminum silicate has peaks at 2θ = 26.9 ° and around 40.3 ° in a powder X-ray diffraction spectrum using CuKα ray as an X-ray source, and 2θ = 20 ° derived from a layered clay mineral. And the separator for lithium ion secondary batteries of any one of Claims 1-4 which does not have a peak around 35 degrees. Lithium-ion secondary battery separator according to any one of claims 1 to 5 BET specific surface area of 250 meters 2 / ^g or more of the aluminum silicate. The lithium-ion secondary battery separator according to any one of claims 1 to 6 , wherein the aluminum silicate has a water content of 10% by mass or less.