JP6044290B2 - Negative electrode for lithium ion secondary battery and lithium ion secondary battery - Google Patents

Description

  The present invention relates to a negative electrode for a lithium ion secondary battery and 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, and Cu) are present in the constituent materials of the battery, they may be deposited on the negative electrode during charge and discharge. The impurities deposited on the negative electrode break the separator and reach the positive electrode, causing a short circuit.

  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 may be deteriorated. For this reason, examination of the trapping material or adsorbent of impurities (hereinafter simply referred to as adsorbent) and the stabilization of the positive electrode have been conducted (for example, see Patent Document 1).

JP 2000-77103 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.
Then, this invention makes it a subject to provide the negative electrode for lithium ion secondary batteries excellent in metal ion adsorption property, and a lithium ion secondary battery.

Specific means for solving the above problems are as follows.
<1> A negative electrode for a lithium ion secondary battery, comprising an aluminum silicate having a Si / Al element molar ratio Si / Al of 0.3 or more and less than 1.0.

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

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

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

<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 is derived from a layered clay mineral 20 The negative electrode for a lithium ion secondary battery according to any one of <1> to <4>, wherein the negative electrode has no peak in the vicinity of ° and 35 °.

<6> In the ²⁹ Si-NMR spectrum, the aluminum silicate has an area ratio (peak B / peak A) between a peak A around −78 ppm and a peak B around −85 ppm in the range of 2.0 to 9.0. The negative electrode material for a lithium ion secondary battery according to any one of <3> to <5>, wherein:

<7> The negative electrode for a lithium ion secondary battery 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 negative electrode for a lithium ion secondary battery according to any one of <1> to <7>, wherein the moisture content of the aluminum silicate is 10% by mass or less.

<9> The negative electrode for a lithium ion secondary battery according to any one of <1> to <8>,
A positive electrode;
Electrolyte,
A lithium ion secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the negative electrode for lithium ion secondary batteries and lithium ion secondary battery which are excellent in metal ion adsorption property can be provided.

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

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. Further, in this specification, the amount of each component in the composition is the sum 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 quantity.
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.

<Anode for lithium ion secondary battery>
The negative electrode for a lithium ion secondary battery of the present invention includes an aluminum silicate having an element molar ratio Si / Al of Si and Al [silicon (Si) to aluminum (Al)] of 0.3 or more and less than 1.0. The negative electrode for a lithium ion secondary battery of the present invention may further contain other components as necessary.
In a lithium ion secondary battery, impurity ions and eluted ions exist in the electrolyte, and these ions travel between the positive and negative electrodes sandwiching the separator during charge and discharge, and deposit on the negative electrode, resulting in a short circuit. There is a case. Therefore, the negative electrode for a lithium ion secondary battery of the present invention contains aluminum silicate on the surface.

  Aluminum silicate is an oxide salt of Si and Al and has different valences. Therefore, many OH groups exist, and this has ion exchange ability. Therefore, it has a feature of having many metal ion adsorption sites per unit mass and adsorbing metal ions with a high specific surface area. Among the aluminum silicates, an aluminum silicate having an Si / Al element molar ratio Si / Al of 0.3 or more and less than 1.0 (hereinafter sometimes referred to as “specific aluminum silicate”) It has the feature of adsorbing metal ions more selectively.

The specific aluminum silicate 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, which 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, 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 this aluminum silicate in the negative electrode of the lithium ion secondary battery, unnecessary metal ions such as impurity ions in the battery or ions eluted from the positive electrode are adsorbed on the specific aluminum silicate. As a result, it is possible to selectively suppress an increase in the concentration of unnecessary specific metal ions in the lithium ion secondary battery. In particular, it is preferable to apply specific aluminum silicate to the surface of the negative electrode. In such a lithium ion secondary battery that is a negative electrode for a lithium ion secondary battery, occurrence of a short circuit is suppressed, and the lithium ion secondary battery has excellent life characteristics.
Below, specific aluminum silicate is demonstrated in detail.

(Specific aluminum silicate)
The specific aluminum silicate has an element molar ratio Si / Al of Si and Al [Si to Al] of 0.3 or more and less than 1.0 from the viewpoint of metal ion adsorption ability and metal ion selectivity. It is preferably 0.6 or more and more preferably 0.45 or more and 0.55 or less. The specific aluminum silicate is a substance different from zeolite having an element molar ratio Si / Al of 1.0 or more.
When 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 ability of the aluminum silicate becomes excessive, and the ion adsorption ability per unit mass decreases. 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 ability of the aluminum silicate tends to be excessive, and the ion adsorption per unit mass is lowered. Further, when the element molar ratio Si / Al is 1.0 or more, the metal ion selectivity to be adsorbed may be further lowered in some cases.

  The element molar ratio Si / Al was obtained by determining the atomic concentrations of Si and Al by an ordinary method using an ICP emission spectrometer (for example, ICP emission spectrometer: P-4010 manufactured by Hitachi, Ltd.). Calculated from 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

FIG. 1 shows a ²⁷ Al-NMR spectrum of a specific aluminum silicate according to Example 1 and Example 2 described later as an example of the 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, a peak may exist in the vicinity of 55 ppm. The peak near 55 ppm is estimated to be a peak derived from tetracoordinated Al.

From the viewpoint of metal ion adsorption and metal ion selectivity, 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 25% or less. 20% or less is more preferable, and 15% or less is still more preferable.

In addition, the specific aluminum silicate 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. Is preferably 5% or more, more 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. The specific aluminum silicate showing the specific ²⁹ Si-NMR spectrum is excellent in metal ion adsorption and metal ion selectivity.

^As a ²⁹ Si-NMR measuring apparatus for measuring a ²⁹ Si-NMR spectrum, 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 below-mentioned Example 1 and 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 a specific aluminum silicate having a crystal structure such as imogolite and allophanes, and also due to a structure of HO—Si— (OAl) ₃ .
The peak B appearing around -85 ppm is considered to be a specific aluminum silicate having a clay structure or a specific aluminum silicate having an amorphous structure. Therefore, the specific aluminum silicate having peaks near 78 ppm and -85 ppm is a mixture or a composite of a specific aluminum silicate having a crystal structure and a specific aluminum silicate having a clay structure or an amorphous structure. It is estimated to be.

  In particular, an 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 an aluminum silicate having a peak A that appears in the vicinity of -78 ppm is excellent in water adsorption ability. On the other hand, the inventors have newly found that this aluminum silicate has an excellent ability to adsorb metal ions, and in particular selectively adsorbs metal ions which adversely affect the battery. For this reason, in the lithium ion battery containing the specific aluminum silicate, the occurrence of short circuit with time is remarkably reduced, and as a result, it can be considered that a lithium ion secondary battery having excellent life characteristics is provided.

  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 (around −81 ppm in FIG. 2) corresponding to the valley between the peak A that appears around −78 ppm and the peak B that is around −85 ppm.

Next, the area of the peak A in the vicinity of −78 ppm is the area surrounded by the straight line passing through −81 ppm orthogonal to the chemical shift axis in FIG. 2, the base line, 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 perpendicular to the chemical shift axis, the above-mentioned baseline, and the curve of 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.

  3 and 4 show an example of a transmission electron microscope (TEM) photograph of the specific aluminum silicate. The specific aluminum silicate shown in FIG. 3 is a specific aluminum silicate according to Example 1 described later. The specific aluminum silicate shown in FIG. 4 is a specific aluminum silicate according to Example 2 described later.

As shown in FIG. 3, the specific aluminum silicate according to 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 Example 2 is tubular so-called imogolite, 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 is not sufficiently obtained, 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 body as shown in FIG. 4 is manufactured by performing a heat treatment when the silicate ions and the aluminum ions are below a specific concentration 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. 3 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. 5 is a drawing schematically showing a tubular so-called imogolite (first specific aluminum silicate described in a manufacturing method described later) 10 which is an example of a specific aluminum silicate. As shown in FIG. 5, the specific aluminum silicate 10 has a structure in which a plurality of (three in FIG. 5) 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 a metal ion adsorption site. 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.

When a so-called imogolite fiber, which is a specific aluminum silicate tube, 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 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. Powder X-ray diffraction is measured using CuKα rays as an X-ray source. For example, a powder X-ray diffractometer manufactured by Rigaku Corporation: Geigerflex RAD-2X (trade name) can be used.

FIG. 6 shows a powder X-ray diffraction spectrum of the specific aluminum silicate according to Example 1 and Example 2 described later as an example of the specific aluminum silicate.
As shown in FIG. 6, the specific aluminum silicate has a peak in the vicinity of 2θ = 26.9 °, 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 aluminum silicate.

The specific aluminum silicate may not have a broad peak in the vicinity of 2θ = 20 ° and 35 ° in the powder X-ray diffraction spectrum. The peaks around 2θ = 20 ° and 35 ° are considered to be peaks obtained from reflection of the hk0 plane of the 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. It means that the displacement from the line is 100% or less of the noise width.

  Further, like the specific aluminum silicate according to Example 1, the specific aluminum silicate has 2θ = 18.8 °, 20.3 °, 27.8 °, 40.6 ° and around 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 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.

The specific aluminum silicate has a BET specific surface area of preferably 250 m ² / g or more, more preferably 280 m ² / g or more, and 300 m ² / g or more from the viewpoint of improving metal ion adsorption ability. More preferably it is. 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 if the specific surface area is too large, the amount of moisture adsorbed in the air per unit mass will increase, so the BET specific surface area should be 1500 m ² / g or less. Is preferably 1200 m ² / g or less, more preferably 1000 m ² / g or less.

  The BET specific surface area of the specific aluminum silicate is measured from the nitrogen adsorption ability at 77K 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 too large, the amount of moisture adsorbed in the air per unit mass will increase. Therefore, the total pore volume is preferably 1.5 m ² / g or less, and 1.2 m ² / g or less. It is more preferable that 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 ion is about 0.01 nm to 0.1 nm, the average pore diameter of the specific aluminum silicate is preferably 1.5 nm or more, and this impurity ion is in a state accompanied by a ligand. It is more preferable that the thickness is 2.0 nm or more. 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 a lithium ion secondary battery is constituted by having a water content of 10% by mass or less, generation of gas due to water causing electrolysis can be suppressed, and battery expansion can be suppressed.
The water content can be measured by the Karl Fischer method.

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

(Production method of 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.

After desalting the coexisting ions from the solution containing the aluminum silicate reaction product, heat treatment is performed in the presence of an acid to produce a specific aluminum silicate excellent in metal ion adsorption ability and metal ion selectivity. It can be manufactured efficiently.
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 the specific aluminum silicate has a regular structure, the affinity for unnecessary metal ions is improved, and the metal ion selectivity is enhanced while efficiently adsorbing the metal ions.

(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.

When producing a specific 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.

  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. Moreover, productivity improves more according to a silicon atom concentration as the silicon atom concentration of a silicic acid solution is 1000 mmol / L or less.

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 include anions other than silicate ions derived from a silicate source and an aluminum source (for example, chloride ions and nitrate ions) and cations other than aluminum ions (for example, sodium ions). 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 by HORIBA: F-55 and the company's general electrical conductivity cell: 9382-10D.

The first washing step includes a step of dispersing 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. Is preferred.
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 minute to 30 minutes at 1200 G or more at room temperature. Specifically, as the conditions for the centrifugation, for example, when TOMY manufactured by SUMY: SUPREMA23 and the company's standard rotor NA-16 are used as a centrifuge, the temperature is 3000 rpm (1450 G) or more and 5 to 10 minutes at room temperature. can do.

  As the solvent in the first washing step, a solvent that easily solvates with the raw material can be appropriately selected and 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 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. The number of treatments for desalting and solid separation can be, for example, 1 to 6 times, and more preferably about 3 times. If the washing is repeated about three times, the residual amount of coexisting ions is so small that it 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. May be.
By performing the synthesis step in a dilute solution, a specific aluminum silicate having a structure in which a regular structure is extended into a tubular shape as shown in FIG. 4 (hereinafter also referred to as “first specific aluminum silicate”). ) Can be obtained. Further, by performing the synthesis step in a high concentration solution, a specific aluminum silicate having a clay structure and an amorphous structure in addition to the regular structure as shown in FIG. Silicate "). In addition, it replaces with the 2nd specific aluminum silicate growing in the tubular thing of 50 nm or more in length, 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 and metal ion selectivity.

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 and metal ion selectivity, the dilution conditions are a silicon atom concentration of 0.1 mmol / L to 10 mmol / L and an aluminum atom concentration of 0.1 mmol / L to 34 mmol / L. Preferably, the silicon atom concentration is 0.1 mmol / L or more and 2 mmol / L or less, and the aluminum atom concentration is 0.1 mmol / L or more and 7 mmol / L or less.
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 and metal ion selectivity, the high concentration condition is preferably a silicon atom concentration of 120 mmol / L or more and 2000 mmol / L or less and an aluminum atom concentration of 120 mmol / L or more and 2000 mmol / L or less. More preferably, the silicon atom concentration is 150 mmol / L to 1500 mmol / L and the aluminum atom concentration is 150 mmol / L to 1500 mmol / L.
By setting the silicon atom concentration to 100 mmol / L or higher and the aluminum atom concentration to 100 mmol / L or higher as the high concentration condition, the second specific aluminum silicate can be efficiently produced. Productivity is also improved.

The silicon atom concentration and the aluminum atom concentration are the silicon atom concentration and the aluminum element concentration in the solution after adding an acidic compound to be described later and adjusting the pH to a predetermined range.
In addition, the silicon atom concentration and the aluminum atom concentration are measured 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 coexisting ions in the solution during the heat treatment and ease of 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 solution is preferably pH 3 or more and less than 7, and more preferably pH 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 temperature 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 and metal ion selectivity 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 specific aluminum silicates having high performance and metal ion selectivity 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 excellent metal ion adsorption ability and metal ion selectivity.

  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 minute 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 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 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 specific aluminum silicate remaining as a precipitate is redispersed in a solvent, and the process of returning to the volume before centrifugation is repeated 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 specific aluminum silicate remaining as a gel-like precipitate can be adjusted by a method of redispersing in a solvent and returning to the volume before centrifugation 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 specific aluminum silicate remaining as a gel-like precipitate can be adjusted by a method of redispersing in a solvent and returning to the volume before centrifugation once or a plurality of times.

(Configuration of negative electrode for lithium ion secondary battery)
The negative electrode for lithium ion secondary batteries contains specific aluminum silicate. In the negative electrode for a lithium secondary battery containing the specific aluminum silicate, impurity ions are captured by the specific aluminum silicate, so that the metal ions are reduced and the metal is prevented from being precipitated at the negative electrode. Thereby, the short circuit of a battery is suppressed. In particular, since the specific aluminum silicate is applied to the surface of the negative electrode, the ionized impurity ions are captured on the negative electrode surface before being reduced. Precipitation is suppressed.

  From the viewpoint that unnecessary metal ions (impurity ions or eluted ions) are captured by the specific aluminum silicate as described above, other configurations are not particularly limited as long as the specific aluminum silicate is contained in the negative electrode. . For example, as a specific aspect of the negative electrode for a lithium ion secondary battery, a layer containing a negative electrode active material (hereinafter sometimes referred to as “negative electrode layer”) is provided on a current collector, A negative electrode in which a layer containing a specific aluminum silicate is provided on the surface can be given.

1) Current collector As the current collector in the negative electrode for a lithium ion secondary battery, a normal current collector used for a negative electrode for a lithium ion secondary battery can be applied. For example, aluminum, copper, nickel, titanium, A strip or the like made of a metal or an alloy such as stainless steel in a foil shape, 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.

2) Negative electrode The negative electrode layer is provided on at least one surface of 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 or the like can be used alone or in combination of two or more.

  The negative electrode layer may contain a binder. The binder is not particularly limited. For example, styrene-butadiene copolymer; ethylenically unsaturated carboxylic acid ester (methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hydroxyethyl (meth)) Acrylate, etc.), and (meth) acrylic copolymers obtained by copolymerizing ethylenically unsaturated carboxylic acids (acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, etc.); polyvinylidene fluoride, polyethylene oxide , Polymer compounds such as polyepichlorohydrin, polyphosphazene, polyimide, and polyamideimide.

  As a method of forming a negative electrode layer on a current collector, a negative electrode mixture slurry is prepared by kneading the negative electrode active material and the binder together with a solvent by a dispersing device such as a stirrer, a ball mill, a super sand mill, and a pressure kneader. And a method of applying this to the current collector and drying it. Alternatively, the paste-like negative electrode mixture slurry may be formed into a sheet shape, a pellet shape, or the like and integrated with the current collector.

The content ratio of the binder in the negative electrode layer of the negative electrode is preferably 0.5 parts by mass to 20 parts by mass with respect to 100 parts by mass in total of the negative electrode active material and the binder, and is 1 part by mass to 10 parts by mass. It is more preferable.
Adhesiveness is good when the content ratio of the binder is 0.5 parts by mass or more, and the negative electrode is prevented from being destroyed by expansion or contraction during charge / discharge. On the other hand, it can suppress that electrode resistance becomes large because it is 20 mass parts or less.

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

  Further, a thickener may be added to the negative electrode mixture slurry in order to adjust the viscosity. As the thickener, for example, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, casein and the like can be used.

  The method for applying the negative electrode mixture 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, 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 mixture slurry and the current collector formed into a sheet shape, a pellet shape or the like 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 layer formed on the current collector and the negative electrode 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 or curing the binder, and can improve the adhesion between the particles and between the particles and the current collector. 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, natural graphite in a negative electrode for a lithium ion secondary battery using as a negative electrode material, it is preferable electrode density of ^{1.0g / cm 3 ~2.0g / cm 3} . About electrode density, volume capacity improves, so that it is high.

3) Layer containing specific aluminum silicate The layer containing the specific aluminum silicate is provided on the negative electrode layer and may be formed by any method. Among them, the specific aluminum silicate can be uniformly dispersed on the negative electrode, thereby forming an aqueous dispersion containing the specific aluminum silicate from the viewpoint of effectively adsorbing unnecessary metal ions. It is preferred that

  The dispersion can be prepared, for example, by kneading a specific aluminum silicate together with a binder and a solvent by a dispersing device such as a stirrer, a ball mill, a super sand mill, or a pressure kneader. This dispersion can be applied onto the negative electrode layer to form a layer containing a specific aluminum silicate.

  The method for applying the dispersion on the negative electrode layer 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, it is preferable to perform a rolling process using a flat plate press, a calender roll, or the like as necessary.

  Examples of the solvent for the dispersion include water, 1-methyl-2-pyrrolidone, alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2 -Methyl-2-propanol and the like, and water is more preferable from the viewpoint of reducing the environmental load.

  The content of the specific aluminum silicate in the dispersion is, for example, preferably 0.01% to 50% by mass, more preferably 0.1% to 30% by mass, and 1% by mass. It is still more preferable that it is% -20 mass%.

Application amount of the specific aluminum silicate in the negative electrode for a lithium ion secondary ^battery, it is preferably 0.01g / ^{m 2} ~50g / m 2 about ^a 0.05g / ^{m 2} ~30g / m 2 it is more ^preferable, and further preferably from ^{0.1g / m 2 ~20g / m 2} .

The dispersion preferably further contains a binder. The specific aluminum silicate is fixed to the positive electrode by adding the dispersion of the specific aluminum silicate to the binder. For this reason, when producing a battery, since specific aluminum silicate does not fall off and can exist on a negative electrode also at the time of charging / discharging, an unnecessary metal ion can be adsorb | sucked efficiently.
As the binder to be contained in the dispersion, the binder described in the negative electrode layer can be applied.

  A thickener may be added to the dispersion 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 electrically conductive agent with the said dispersion liquid as needed. Examples of the conductive agent include carbon black, graphite, acetylene black, conductive oxide, and conductive nitride. The usage-amount of a electrically conductive agent should just be about 0.1 mass%-20 mass% with respect to a negative electrode active material.

4) Other layers In the negative electrode for a lithium ion secondary battery, other layers may be provided. For example, an underlayer for improving the adhesion between the current collector and the negative electrode layer may be provided between the current collector and the negative electrode layer. The underlayer preferably contains a polymer that does not dissolve or swell in the solvent of the electrolytic solution, and may contain a conductive substance in order to reduce the electrical resistance of the electrode and ensure conductivity.

<Lithium ion secondary battery>
The lithium ion secondary battery of this invention is comprised including the above-mentioned negative electrode, a positive electrode, and electrolyte solution. The negative electrode is provided with a specific aluminum silicate on the surface.

1) Positive electrode As an aspect of a positive electrode, the thing provided with the layer (henceforth a "positive electrode layer") containing a positive electrode active material on the electrical power collector is mentioned, for example.

  As the current collector in the positive electrode, a normal current collector used for a positive electrode for a lithium ion secondary battery can be applied. For example, a metal or an alloy such as aluminum, copper, nickel, titanium, stainless steel, or the like 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 positive electrode layer is provided on the current collector and contains a positive electrode active material.
As a positive electrode active material, the normal thing used for the positive electrode for lithium ion secondary batteries is applicable. Examples of the positive electrode active material include metal compounds, metal oxides, metal sulfides, and conductive polymer materials that can be doped or intercalated with lithium ions. 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, etc. Etc. can be used alone or in combination of two or more.

The positive electrode layer may contain a binder. The binder is not particularly limited. For example, styrene-butadiene copolymer; ethylenically unsaturated carboxylic acid ester (methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylonitrile, hydroxy (Meth) acrylic copolymer obtained by copolymerizing ethyl (meth) acrylate, etc.) and ethylenically unsaturated carboxylic acid (acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, etc.); polyfluorinated Examples thereof include high molecular compounds such as vinylidene, polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polyimide, and polyamideimide.
“(Meth) acrylate” means “acrylate” and “methacrylate” corresponding thereto. The same applies to other similar expressions such as “(meth) acrylic copolymer”.

  Examples of the method for forming the positive electrode layer on the current collector include a method in which a positive electrode mixture slurry containing the positive electrode active material, the binder, and a solvent is applied to at least one surface of the current collector and dried. It is done. Alternatively, the paste-like positive electrode mixture slurry may be formed into a sheet shape, a pellet shape, or the like and integrated with the current collector. The viscosity of the positive electrode mixture slurry is preferably adjusted as appropriate in accordance with the coating method.

  Examples of the solvent include alcohol solvents, glycol solvents, cellosolve solvents, amino alcohol solvents, amine solvents, ketone solvents, carboxylic acid amide solvents, phosphoric acid amide solvents, sulfoxide solvents, carboxylic acid ester solvents, phosphoric acid ester solvents, ether solvents, A nitrile solvent, water, etc. are mentioned. In order to obtain the solubility of the binder or the dispersion stability of the conductive auxiliary agent, it is preferable to use a highly polar solvent.

  Specific examples of the solvent include amide solvents obtained by dialkylating nitrogen such as N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methylpyrrolidone, Examples include, but are not limited to, hexamethylphosphoric triamide, dimethyl sulfoxide, and the like. Two or more kinds of solvents can be used in combination.

  Moreover, you may add a thickener to a positive mix slurry in order to adjust a 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 electrically conductive agent with the said positive mix slurry as needed. Examples of the conductive agent include carbon black such as ketjen black, acetylene black, channel black, furnace black, lamp black, and thermal black; natural graphite such as flake graphite; graphite such as artificial graphite and expanded graphite; carbon fiber Or conductive fibers such as metal fibers; metal powders such as copper, silver, nickel, and aluminum; organic conductive materials such as polyphenylene derivatives; In addition, these conductive agents may be used alone or in combination. What is necessary is just to let the content rate of a electrically conductive agent be about 0.1 mass%-20 mass% with respect to a positive electrode active material.

  Moreover, you may add a thickener to the said positive mix slurry in order to adjust a viscosity. Examples of the thickener include carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, polyacrylic acid (salt), oxidized starch, phosphorylated starch, and casein.

  There is no restriction | limiting in particular about the method of providing the said positive mix slurry to a collector, A well-known method can be used. Specific examples of the application method include a die coating method, a dip coating method, a roll coating method, a doctor coating method, a spray coating method, a gravure coating method, a screen printing method, and an electrostatic coating method. Moreover, you may perform the rolling process by a lithographic press, a calender roll, etc. as needed after provision.

  Moreover, integration of the positive electrode mixture slurry and the current collector formed into a sheet shape, a pellet shape, or the like can be performed by a known method such as a roll, a press, or a combination thereof.

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

2) Electrolytic solution 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 is obtained by using an electrolytic solution in which an electrolyte is dissolved in an organic solvent.

As the electrolyte, for _{example, 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 And lithium salts such as LiC (CF ₃ SO ₂ ) ₃ , LiCl, and LiI.
The concentration of the electrolyte is not particularly limited. For example, the electrolyte is preferably 0.3 mol to 5 mol, more preferably 0.5 mol to 3 mol, and particularly preferably 0.8 mol to 1.5 mol with respect to 1 L of the electrolytic solution. preferable.

Examples of the organic solvent include carbonate solvents (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, etc.), lactone solvents (γ-butyrolactone, etc.), ester solvents (methyl acetate, ethyl acetate, etc.), chain ether solvents (1,2-dimethoxyethane, dimethyl ether, diethyl ether, etc.), cyclic ether solvents ( Tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane, 4-methyldioxolane, etc.), ketone solvent (cyclopentano) Etc.), sulfolane solvents (sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane etc.), sulfoxide solvents (dimethyl sulfoxide etc.), nitrile solvents (acetonitrile, propionitrile, benzonitrile etc.), amide solvents (N, N -Aprotic solvents such as dimethylformamide, N, N-dimethylacetamide, etc.), urethane solvents (3-methyl-1,3-oxazolidine-2-one, etc.), polyoxyalkylene glycol solvents (diethylene glycol, etc.) be able to.
An organic solvent may be used independently and may be used as 2 or more types of mixed solvents.

3) Separator The lithium ion secondary battery may have a separator. As the separator, a nonwoven fabric, a cloth, a microporous film, or a combination thereof having a polyolefin as a main component such as polyethylene or polypropylene can be used. In the case where the positive electrode and the negative electrode of the lithium ion secondary battery to be manufactured are not in direct contact, it is not necessary to use a separator.

4) Configuration 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 plate group. Are generally laminated to form a laminated electrode plate group, and the electrode plate group is generally enclosed in an exterior body.
The lithium ion secondary battery is not particularly limited, and is used as a paper type battery, a button type battery, a coin type battery, a stacked type battery, a cylindrical type battery, a rectangular type battery, or the like.

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.
In Examples 1 to 4 and Comparative Examples 1 to 3 below, as a preliminary test, the metal ion adsorption ability of the specific aluminum silicate in water was evaluated. In Examples 5 and 6, the model electrolyte solution was used. The metal ion adsorption ability was evaluated.
In Example 7, a lithium ion secondary battery was produced, and the initial capacity, charge / discharge characteristics, and impedance were measured.

[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.

<Element molar ratio Si / Al>
For sample A, 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.

<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.

<Transmission electron microscope (TEM) photo observation>
FIG. 3 shows a transmission electron microscope (TEM) photograph of sample A observed at a magnification of 100,000. Note that the TEM observation was performed using a transmission electron microscope (H-7100FA type, manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 100 kV. 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. 3, there is no tubular object having a length of 50 nm or more.

<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. 6 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 °. No peaks were observed around 2θ = 20 ° and 35 °.

<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 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 as to have a final concentration of 1.0% by mass, mixed thoroughly, and allowed to stand. Then, each metal ion concentration before and after the addition of sample A was measured by ICP emission spectroscopic analysis.

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⁺ . On the other hand, Li ⁺ was 90 ppm and was hardly adsorbed. Therefore, although sample A adsorbs Ni ²⁺ and Mn ²⁺ unnecessary for the lithium ion secondary battery, it hardly adsorbs Li ⁺ essential for charge and discharge, and can suppress a short circuit without impairing the performance of the battery. I understand.

[Comparative Example 1]
Commercially available activated carbon (manufactured by Wako Pure Chemical Industries, Ltd., activated carbon, crushed, 2 to 5 mm) was used as sample B. 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 ⁺ .

[Comparative Example 2]
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 ⁺ .

[Comparative Example 3]
Sample D was commercially available zeolite 4A (manufactured by Wako Pure Chemical Industries, Ltd., molecular sieves 4A, Si / Al molar ratio = 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 allowed to stand.

[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.

<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.

<BET specific surface area, total pore volume, average pore diameter>
In the same manner as in 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.

^<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.

<Transmission electron microscope (TEM) photo observation>
In FIG. 4, the transmission electron microscope (TEM) photograph when the sample E is observed by 100,000 times by the same method as Example 1 is shown. As shown in FIG. 4, a tubular product is generated, 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 to 3.0 nm, and the inner diameter Was about 0.7 to 1.4 nm.

<Powder X-ray diffraction>
In the same manner as in Example 1, powder X-ray diffraction of Sample E was performed. FIG. 6 shows the powder X-ray diffraction spectrum of Sample E. It had broad peaks around 2θ = 4.8 °, 9.7 °, 14.0 °, 18.3 °, 27.3 °, and 40.8 °. No peaks were observed around 2θ = 20 ° and 35 °.

<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 Example 1, Sample E showed the same metal ion adsorption ability as Sample A.

[Example 3]
The sample A prepared in Example 1 was used, and the ability to adsorb metal ions in water was evaluated by the method described in Example 1 except that the addition amount of Sample A was changed as shown in the following table. The results are shown in the table below.

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

[Example 4]
Using the sample A prepared in Example 1, the metal ion adsorption ability in water was evaluated by the method described in 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 pH at this time was 5.1. The concentration after addition of Sample A was 160 ppm for Cu ²⁺ .

[Example 5]
<Metal ion adsorption capacity in model electrolyte>
Assuming application to lithium ion secondary batteries, the ability to adsorb metal ions in a model electrolyte was evaluated. Using a solution in which diethyl carbonate (DEC) and ethylene carbonate (EC) were mixed as a solvent so that the volume ratio was DEC / EC = 1/1, nickel tetrafluoroborate as an solute had an initial Ni ²⁺ ion concentration of 100 ppm. In addition, a model electrolyte was obtained.

  30 mL of the model electrolyte was placed in a glass bottle, and 0.3 g of Sample A was added thereto. The solution was stirred for several minutes and then allowed to stand for several hours. The concentration change before and after the sample addition was measured by ICP emission spectroscopic analysis (ICP emission spectroscopic device: SPS5100 (manufactured by SII Nanotechnology)). In addition, acid decomposition (microwave method) was performed for the pretreatment of the measurement sample.

In the above, instead of the sample A, the sample C, the sample D, the sample E, and a commercially available zeolite 13X (manufactured by Wako Pure Chemical Industries, Ltd., molecular sieves 13X, Si / Al molar ratio = 1.2) Using the sample F, the adsorption amount of Ni ²⁺ was measured. The results are shown in the table below.

As shown in the above table, in the model electrolyte, the specific aluminum silicates of Examples 1 and 2 exhibited Ni ²⁺ ion adsorption ability superior to silica gel, zeolite 4A, and zeolite 13X.

[Example 6]
The Ni ²⁺ ion adsorption ability in the model electrolyte was evaluated by the method described in Example 5 except that the amount of sample A added was changed as shown in the table below. The results are shown in the table below.

As shown in the table above, when Sample A was added by 1.0 mass%, Ni ²⁺ ions were adsorbed by 80%. When 2.0 mass% of sample A was added, 95% of Ni ²⁺ ions were adsorbed.

[Example 7]
<Preparation of positive electrode>
The positive electrode active material used in this example is LiMn ₂ O ₄ powder having an average particle size of 20 μm and a maximum particle size of 80 μm. This positive electrode active material, natural graphite, and a 1-methyl-2-pyrrolidone solution of polyvinylidene fluoride were mixed and sufficiently kneaded to obtain a positive electrode slurry. The mixing ratio of LiMn ₂ O ₄ , natural graphite, and polyvinylidene fluoride was 90: 6: 4 by mass ratio. This slurry was applied to the surface of a positive electrode current collector made of an aluminum foil having a thickness of 20 μm by a doctor blade method so that the coating amount after drying was 250 g / m ² . This positive electrode was dried at 100 ° C. for 2 hours to produce a positive electrode.

<Production of negative electrode>
The negative electrode was produced by the following method. Artificial graphite powder having an average particle size of 10 μm was used as the negative electrode active material. Artificial graphite powder and polyvinylidene fluoride were mixed at a mass ratio of 90:10, 1-methyl-2-pyrrolidone was added as an organic solvent, and the mixture was sufficiently kneaded to prepare a negative electrode slurry. This slurry was applied to the surface of a negative electrode current collector made of a copper foil having a thickness of 10 μm by a doctor blade method so that the coating amount after drying was 75 g / m ² and dried at 100 ° C. for 2 hours.

Specified aluminum silicate dispersion obtained by adding polyvinylidene fluoride as a binder to 15% by mass aqueous dispersion of the specific aluminum silicate (sample A) prepared in Example 1 to 5% by mass with respect to sample A Was applied onto the negative electrode sheet by a doctor blade method and vacuum dried at 120 ° C. to prepare a negative electrode. The application amount of Sample A in the negative electrode was 5 g / m ² .

<Production of lithium ion secondary battery>
A polyethylene porous sheet having a thickness of 25 μm was used as a separator, and an electrolyte solution was prepared by dissolving LiPF _{6 in} a mixed solvent of 1: 1 volume ratio of diethyl carbonate and ethylene carbonate to a concentration of 1 mol / l. An aluminum laminate cell was produced. 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. It is a battery.

<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 where sample A was applied to the negative electrode showed similar initial capacity compared to the cell where 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 in which sample A was applied to the negative electrode had a lower discharge capacity reduction rate than the cell in which sample A was not applied.

(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.
In the cell in which sample A was applied to the negative electrode, the rate of increase in impedance after standing at 50 ° C. for 1 week was smaller than that in the cell to which sample A was not applied.

  From the measurement results of the initial capacity, charge / discharge characteristics, and impedance, it was confirmed that Sample A applied to the negative electrode surface contributes to the extension of cell life and safety. This is presumed to be due to the adsorption of impurities eluted from the positive electrode from the evaluation results of the ion adsorption ability of sample A.

10 1st specific aluminum silicate 10a Tubular body 20 Inner wall 30 Crevice

Claims (8)

Si and Al element molar ratio Si / Al of look-containing aluminum silicate of less than 0.3 or more 1.0, the aluminum silicate ⁱⁿ 29 Si-NMR spectrum, a peak in the vicinity -78ppm and -85ppm A negative electrode for a lithium ion secondary battery. The negative electrode for a lithium ion secondary battery according to claim 1, wherein the aluminum silicate has a peak in the vicinity of 3 ppm in a ²⁷ Al-NMR spectrum. The negative electrode for a lithium ion secondary battery according to claim 1 or 2 , wherein the element molar ratio Si / Al of the aluminum silicate is 0.4 or more and 0.6 or less. 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 20 ° and 35 derived from layered clay minerals. The negative electrode for a lithium ion secondary battery according to any one of claims 1 to 3 , which has no peak in the vicinity of °. In the ²⁹ Si-NMR spectrum, the aluminum silicate has an area ratio (peak B / peak A) between peak A near -78 ppm and peak B near -85 ppm in the range of 2.0 to 9.0. anode material for a lithium ion secondary battery according to any one of claims 1 to 4. The negative electrode for a lithium ion secondary battery according to any one of claims 1 to 5 , wherein the aluminum silicate has a BET specific surface area of 250 m ² / g or more. The negative electrode for a lithium ion secondary battery according to any one of claims 1 to 6 , wherein the aluminum silicate has a water content of 10% by mass or less. A negative electrode for a lithium ion secondary battery according to any one of claims 1 to 7 ,
A positive electrode;
Electrolyte,
A lithium ion secondary battery.