JP2019079701A - Method of manufacturing separator for zinc negative electrode secondary battery and separator for zinc negative electrode secondary battery - Google Patents

Abstract

To provide a method of manufacturing a separator for a zinc negative electrode secondary battery containing a metal ion adsorbent and/or a layered double hydroxide and capable of ensuring process ease at a time of secondary battery manufacture, and a zinc negative electrode secondary battery separator containing a metal ion adsorbent and a layered double hydroxide and capable of improving life performance of the secondary battery and suppressing self-discharge.SOLUTION: Provided is the method of manufacturing a separator for a zinc negative electrode secondary battery includes: an impregnation step of impregnating a non-woven fabric with a dispersion containing a metal ion adsorbent and/or a layered double hydroxide; and a drying step of drying the nonwoven fabric impregnated with the dispersion. Also provided is the zinc negative electrode secondary battery provided with the separator for the zinc negative electrode secondary battery.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a separator for zinc negative electrode secondary battery and a separator for zinc negative electrode secondary battery.

  As a technology for improving the cycle durability of nickel zinc secondary batteries, it is known to press a liquid containing material with a large electrolytic solution holding capacity into the negative electrode, and to arrange a porous nonwoven fabric of synthetic resin and a microporous synthetic resin film on the positive electrode. (E.g., Patent Document 1). In the document, improvement in separator configuration between positive and negative electrodes is described to suppress reduction in battery function due to zinc dendrite and to suppress reduction in utilization of zinc active material during discharge even when the amount of electrolyte is limited to a small amount. There is.

  It is known that an impurity metal trap material (imogolite) layer is added as a short circuit prevention technology of a lithium ion battery (for example, reference 1: Hitachi Chemical Co., Ltd. Technical Report No. 55 (January 2013)). In the document, it is described that an impurity metal trap material (imogolite) layer is added to a positive electrode active material in order to suppress a micro short circuit caused by an impurity metal (such as Cu) contained in a lithium ion battery.

  As a separator for a nickel zinc secondary battery, a laminate in which an anion conductive film containing a polymer and an inorganic compound is laminated on a nonwoven fabric or the like is known (for example, Patent Document 2). In the document, it is described that the separator may contain a layered double hydroxide in order to suppress the decrease in battery function due to zinc dendrite.

JP-A-52-9836 JP, 2015-95286, A

The nickel positive electrode used in the nickel zinc battery is eluted in the electrolytic solution by the charge / discharge cycle, overdischarge and overcharge, and the conductive auxiliary agent (Co etc.) of the positive electrode or the impurity metal is eluted into the electrolytic solution, and the eluted metal is transferred to the negative electrode through the separator. When reached, it causes a decrease in the hydrogenation voltage of the negative electrode and an increase in the amount of self-discharge. Therefore, it is necessary to devise that the metal ions do not reach the negative electrode.
Furthermore, since the laminate as in Patent Document 2 inevitably has an asymmetric structure, it is necessary to perform an operation such as determining the front and back sides of the secondary battery, and so on. Such an operation may complicate the manufacturing process of the secondary battery.

  Therefore, the present invention contains a metal ion adsorbent for suppressing self-discharge, and a method of manufacturing a zinc negative electrode secondary battery separator that can ensure process easiness in secondary battery manufacturing, and zinc An object of the present invention is to provide a separator for a negative electrode secondary battery.

  The present invention comprises a separator for a zinc negative electrode secondary battery (in which the negative electrode is a zinc electrode, the separator comprises: an impregnation step of impregnating a dispersion containing a metal ion adsorbent into a nonwoven fabric; and a drying step of drying the nonwoven fabric impregnated with the dispersion). A method of manufacturing a separator for a secondary battery, which is According to the present invention, it is possible to manufacture a separator that can ensure processability at the time of manufacturing a secondary battery. The separator obtained by the present invention has a simple structure in which a metal ion adsorbent is dispersed and supported in a non-woven fabric, and has a symmetrical structure in terms of both function and appearance. Therefore, when incorporating in a secondary battery, it is not necessary to pay attention to the front and back of a separator, and complication of the manufacturing process of a secondary battery can be suppressed.

  In the present invention, the content of the metal ion adsorbent in the dispersion is preferably 1 to 99% by mass based on the total mass of the dispersion. As a result, it is possible to more easily achieve good dispersibility, good impregnatability, simplicity of the method for producing a separator, and the like, so that the impregnation step can be carried out more suitably.

  In the present invention, preferably, the content of the layered double hydroxide in the dispersion is 1 to 99% by mass based on the total mass of the dispersion. As a result, it is possible to more easily achieve good dispersibility, good impregnatability, simplicity of the method for producing a separator, and the like, so that the impregnation step can be carried out more suitably.

  The present invention also provides a separator for a zinc negative electrode secondary battery, comprising a non-woven fabric and a metal ion adsorbent carried in the non-woven fabric. ADVANTAGE OF THE INVENTION According to this invention, when incorporating in a secondary battery, it is not necessary to pay attention to the front and back of a separator, and complication of the manufacturing process of a secondary battery can be suppressed.

  The present invention also provides a zinc negative electrode secondary battery separator comprising a non-woven fabric and a layered double hydroxide supported in the non-woven fabric. ADVANTAGE OF THE INVENTION According to this invention, when incorporating in a secondary battery, it is not necessary to pay attention to the front and back of a separator, and complication of the manufacturing process of a secondary battery can be suppressed.

  In the present invention, the content of the metal ion adsorbent is preferably 1 to 99% by mass based on the total mass of the separator.

  In the present invention, the content of the layered double hydroxide is preferably 1 to 99% by mass based on the total mass of the separator.

  The separator of the present invention can be suitably used as a nickel zinc secondary battery separator.

  According to the present invention, a metal ion adsorbent for suppressing self-discharge with cycles and / or a layered double hydroxide for suppressing zinc dendrite are contained, and process easiness in manufacturing a secondary battery The manufacturing method of the separator for zinc negative electrode secondary batteries which can be ensured, and the separator for zinc negative electrode secondary batteries can be provided.

7 shows the results of charge and discharge cycle tests of Examples and Comparative Examples.

  The separator of the present embodiment is a separator for a zinc negative electrode secondary battery incorporated into a zinc negative electrode secondary battery. First, the case where the secondary battery is a nickel zinc secondary battery will be described as an example.

[Nickel zinc secondary battery]
The nickel zinc secondary battery is an alkali in which a nickel (Ni) electrode as one of the positive electrode or the negative electrode, a zinc (Zn) electrode as the other of the positive electrode or the negative electrode, a separator between the two electrodes, and And at least an electrolytic solution composed of an aqueous solution. The separator serves to electrically insulate the positive electrode and the negative electrode and to conduct OH ^- ions through the fine pores. An example of the battery reaction of a nickel zinc secondary battery is shown below (discharge reaction: right direction, charge reaction: left direction).
(Positive _{electrode) 2NiOOH + 2H 2 O + 2e} - → 2Ni (OH) 2 + 2OH -
(Negative ^{electrode) Zn + 2OH - → Zn (} OH) 2 + 2e -
(Overall) ₂ NiOOH + Zn + 2 H ₂ O → ₂ Ni (OH) ₂ + Zn (OH) ₂

(Nickel electrode)
The nickel electrode includes a current collector, and an active material layer containing an active material mainly composed of nickel hydroxide particles, an additive, a binder and the like on the current collector. Cobalt, zinc, cadmium, magnesium, zirconium or the like may be dissolved in nickel hydroxide, which is a raw material of the nickel hydroxide particles. The surface of the nickel hydroxide particles may be coated with a cobalt compound or the like.

  Additives include cobalt compounds such as metallic cobalt, cobalt oxide and cobalt hydroxide, metallic nickel, metallic zinc, zinc compounds such as zinc oxide and zinc hydroxide, calcium compounds such as calcium hydroxide and calcium carbonate, rare earth metals, And rare earth metal compounds. The additive amount of the additive can be, for example, 0.05 to 30 parts by mass with respect to 100 parts by mass of the active material.

  Examples of the binder include hydrophilic or hydrophobic polymers and the like. More specifically, examples of the binder include hydroxypropyl methylcellulose (HPMC), carboxymethylcellulose (CMC), sodium polyacrylate (SPA) and the like. In addition, as a binder, fluorine-based polymers such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) can also be used. The addition amount of the binder can be, for example, 0.01 to 1.0 parts by mass with respect to 100 parts by mass of the active material.

  As the current collector, for example, copper foil, electrolytic copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloy such as brass, brass foil, brass mesh (expanded metal), foamed brass, punched brass, Nickel foil, nickel mesh, corrosion resistant nickel, nickel mesh (expanded metal), punching nickel, foamed nickel, zinc metal, zinc corrosion resistant metal, zinc foil, zinc mesh (expanded metal), steel plate, punching steel plate, silver foil and the like. Elements such as Ni, Zn, Sn, Pb, Hg, Bi, In, and Tl may be further added to these current collector materials, and Ni, Zn, Sn, etc. may be added to the surface of the current collector material. Plating with Pb, Hg, Bi, In, Tl or the like may be performed.

(Zinc electrode)
The zinc electrode includes a current collector, and an active material layer containing an active material mainly composed of zinc and zinc oxide particles, an additive, a binder and the like on the current collector.

  Additives include metal oxides which are nobler than the reduction potential of zinc such as indium oxide, bismuth oxide, lead oxide, cadmium oxide and thallium oxide, metal oxides having high wettability such as titanium oxide, aluminum oxide and silicon oxide And calcium compounds such as calcium oxide and calcium hydroxide, and fluorine compounds such as potassium fluoride and calcium fluoride. The additive amount of the additive can be, for example, 1 to 20 parts by mass with respect to 100 parts by mass of the active material.

  Examples of the binder include polytetrafluoroethylene, hydroxyethyl cellulose, polyethylene oxide and the like. The addition amount of the binder can be, for example, 0.5 to 10 parts by mass with respect to 100 parts by mass of the active material. In addition, in the zinc electrode, it is also possible to use a fiber (fiber) made of polyethylene, polypropylene, aluminum oxide or the like in place of these binders.

  As an electrolyte solution, alkaline aqueous solution, such as potassium hydroxide aqueous solution, sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, is mentioned, for example.

(Separator)
As a separator (separator for nickel zinc secondary batteries), the separator of the present embodiment is used, which comprises a non-woven fabric, a metal ion adsorbent carried in the non-woven fabric and / or a layered double hydroxide. Since the separator of the present embodiment is provided with a metal ion adsorbent, a metal in which a conductive support agent (Co or the like) or impurity metal of the positive electrode associated with charge and discharge cycles, overdischarge and overcharge is eluted into the electrolytic solution It has ion adsorption performance. That is, by suppressing the eluted metal ions from reaching the negative electrode through the separator, it is possible to suppress a decrease in the hydrogenation voltage of the negative electrode and an increase in the self-discharge amount.
Moreover, since the separator of this embodiment is provided with layered double hydroxide, it has the selectivity of the anion to permeate | transmit. That is, while anions such as hydroxide ions are easily transmitted through the separator, metal-containing ions (Zn (OH) ₄ ^2- ) and the like derived from the active material, which are large in ion radius even if they are anions, are the separator Difficult to penetrate. Thereby, the growth of zinc dendrite from the zinc electrode surface by charge and discharge can be suppressed.

  The non-woven fabric is not particularly limited as long as it is processed from fibers commonly used in non-woven fabrics. Examples of such fibers include cellulose fibers, aramid fibers, glass fibers, nylon fibers, vinylon fibers, polyester fibers, polyolefin fibers (polyethylene fibers, polypropylene fibers and the like), rayon fibers and the like. The manufacturing method is not particularly limited, and for example, a general method including steps of forming a fleece from fibers and bonding the formed fleece can be mentioned.

  The thickness of the non-woven fabric can be 5 to 300 μm from the viewpoint of reducing the ohmic resistance of the battery, increasing the energy density, and the like. The thickness referred to here is an average value of the thickness of 10 different points measured using a film thickness meter.

The porosity of the non-woven fabric can be 10 to 95% by volume from the viewpoint of facilitating retention of the amount of electrolytic solution necessary for charge and discharge reaction, mass transfer at the time of battery reaction, and the like. The porosity can be determined from the area A (cm ² ) of the non-woven fabric, the thickness t (cm), the mass (g) of the non-woven fabric, and the density M (g / cm ³ ) of fibers used.
Porosity (volume%) = {1-B / (M × A × t)} × 100

  As metal ion adsorbents, amorphous viscosity minerals, quasicrystalline viscosity minerals, IXEPLAS-A1, IXEPLAS-A2, IXEPLAS-A1, and IXEPLAS-B1 (product name, Toho, as compounds excellent in economy and availability. And the like.

  As the amorphous viscosity mineral and the semicrystalline viscosity mineral, metal ions may be adsorbed in the alkaline electrolyte, and the adsorption ratio is preferably 100%. In addition, those having a large specific surface area are preferable because the amount of adsorption and the amount of release are large, and it is more preferable if they are easily available and inexpensive. Further, it is preferable to use one having a small hydrogenation voltage such as iron or copper and containing no metal that accelerates the self-discharge reaction of the nickel zinc battery. Among clay minerals, imogolite which is an amorphous clay mineral and allophane which is a semicrystalline clay mineral are particularly suitable for the above-mentioned metal ion adsorption conditions. The particles of these clay minerals are allophane particles in the form of hollow spheres having a diameter of 3.0 to 5.5 nm, and imogolite particles having a tube shape having an inner diameter of 0.5 to 1.20 nm and an outer diameter of 1.0 to 3.0 nm. Among clay minerals, the particle size is small and the specific surface area is high. Moreover, although the specific surface area is slightly inferior to that of the above-mentioned viscosity mineral, it is also possible to use a clay mineral such as kaolin mineral or aluminum hydroxide. The average particle size can be obtained by directly observing the separator using, for example, a scanning electron microscope (hereinafter abbreviated as “SEM”). Specifically, the diameter of 100 particles can be measured, and the average value of the measured values can be used as the average particle diameter.

Where the metal ion adsorbent is dispersed is between the positive electrode plate and the negative electrode plate, for example, whether it is dispersed in the electrolytic solution or fixed to the separator and dispersed, and / or the positive electrode active material of the positive electrode plate It may be scattered on the surface of.
The layered double hydroxide includes hydrotalcite, and specific examples include a hydrotalcite compound represented by the following general formula (1).
[L ²⁺ _1−x Q ³⁺ _x (OH) ₂ ] ^{x +} [(A ^{n −} ) _{x / n} · _m H ₂ O] ^{x −} (1)

In the formula (1), L represents a divalent metal ion, and specifically, Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Ni ²⁺ , Co ²⁺ , Cu ²⁺ etc. Q is a trivalent metal ion, specifically, Al ³⁺ , Fe ³⁺ , Mn ^{3+ and the} like, and A is an n-valent anion, and specifically, OH ⁻ , SO ₄ ^2- , CO ₃ ^2- , NO ^{3- and the} like. In the formula, x satisfies 0.2 ≦ x ≦ 0.33, and m satisfies 0 ≦ m ≦ 3.5.

Among the hydrotalcite compounds represented by the above formula (1), L is Mg ²⁺ , Q is Al ³⁺ , and A is CO ₃ ^2- as a compound which is excellent in economy and availability. The thing is mentioned. As such a hydrotalcite compound, STABLACE
HR-1, STABLACE HR-7, STABLACE HR-P (product name, Sakai Chemical Industry Co., Ltd.), DHT-4A, DHT-4A-2, DHT-4C, DHT-4H, etc. (product name, Kyowa Chemical Industry Co., Ltd.) Company company), IXE-700F (product name, manufactured by Toagosei Co., Ltd.) and the like.

  The average particle diameter of the layered double hydroxide can be set to 0.3 to 10 μm from the viewpoint of good dispersibility in the below-described dispersion liquid and good filling into the non-woven fabric voids. The average particle size can be obtained by directly observing the separator using, for example, a scanning electron microscope (hereinafter abbreviated as “SEM”). Specifically, the diameter of 100 particles can be measured, and the average value of the measured values can be used as the average particle diameter.

  From the viewpoint of further improving the selectivity of the anion, it is also possible to use one obtained by firing the hydrotalcite compound represented by the above formula (1) at high temperature (for example, about 500 ° C.).

  The content (carrying amount) of the metal ion adsorbent in the non-woven fabric is 1 to 99 mass based on the total mass of the separator from the viewpoint of coexistence with metal ion adsorption and retention of the electrolyte amount necessary for charge and discharge reaction. It can be%. Moreover, the said content can be made into 1-99 volume% on the basis of the whole volume of a separator. The supported amount of the metal ion adsorbent in the separator is, for example, thermobalance-mass spectrometry (hereinafter abbreviated as "TG-MS"), inductively coupled plasma mass spectrometry (hereinafter abbreviated as "ICP-MS"), etc. The weight of the non-woven fabric and the metal ion adsorbent can be separated to obtain the content of the metal ion adsorbent in the separator. The volume occupied by the metal ion adsorbent in the separator can be obtained by directly observing the separator using, for example, an SEM. Specifically, the volume is calculated from the ratio of the non-woven fabric in the SEM image and the ratio of the metal ion adsorbent, and the average value of the volume per 10 SEM images is used as the metal ion adsorbent volume. Can.

  The content (loading amount) of the layered double hydroxide in the non-woven fabric is 1 to 99 based on the total mass of the separator from the viewpoint of achieving both the selectivity of the anion and the retention of the amount of electrolyte necessary for charge and discharge reaction. It can be mass%. Moreover, the said content can be made into 1-99 volume% on the basis of the whole volume of a separator. The supported amount of layered double hydroxide in the separator is, for example, thermobalance-mass spectrometry (hereinafter abbreviated as "TG-MS"), inductively coupled plasma mass spectrometry (hereinafter abbreviated as "ICP-MS"). The mass of the non-woven fabric and the layered double hydroxide can be separated to obtain the content of the layered double hydroxide in the separator. The volume occupied by the layered double hydroxide in the separator can be obtained by directly observing the separator using, for example, an SEM. Specifically, the volume is calculated from the ratio of the non-woven fabric in the SEM image and the ratio of the layered double hydroxide, and the average value of the volume per 10 SEM images is the volume of the layered double hydroxide can do.

  In the non-woven fabric, compounds other than metal ion adsorbents and / or layered double hydroxides may also be supported. The additive is mainly used in the production of the positive electrode and the negative electrode active material, and examples thereof include a binder such as carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene oxide, polytetrafluoroethylene and the like. The content of these additives can be set to a level that does not impair the characteristics of the separator, and can be, for example, 0 to 90% by mass based on the total mass of the separator.

  Also, other separators such as a polyolefin-based microporous membrane, a nylon-based microporous membrane, an oxidation-resistant ion exchange resin membrane, a cellophane-based regenerated resin membrane, and an inorganic-organic separator may be used in combination with the separator of this embodiment. Good. In this case, for example, there is a mode in which the positive electrode and the negative electrode are respectively sandwiched by the other separators, and these are stacked via the separator of the present embodiment. By using other separators (for example, a hydrophilic polyolefin-based microporous film) in combination, it is easy to achieve, for example, suppression of morphological change, aggregation and dendrite of the negative electrode, improvement of the conductivity of the negative electrode, etc. It becomes easy to extend the cycle life of charge and discharge of the battery.

[Method of manufacturing nickel zinc secondary battery]
The method for producing the nickel electrode and the zinc electrode is not particularly limited, and examples thereof include the following methods. That is, each raw material for obtaining an active material layer and water are kneaded to prepare an active material paste, which is applied on a current collector. At this time, when a porous material is used as the current collector, the active material paste is also filled in the pores. Thereafter, the resultant is dried and further subjected to pressure forming by a roller press, whereby an electrode having an active material layer on a current collector can be obtained. In addition, only an active material paste is rolled beforehand, it forms in a sheet form, this is crimped | bonded to a collector, and after press-molding, an electrode can also be obtained by drying.

  The separator can be obtained by a method including an impregnating step of impregnating a non-woven fabric with a dispersion containing a metal ion adsorbent and / or a layered double hydroxide, and a drying step of drying the non-woven fabric impregnated with the dispersion.

  The dispersion is prepared by adding metal ion adsorbent and / or layered double hydroxide and, for example, a binder such as carboxymethyl cellulose, polytetrafluoroethylene, hydroxyethyl cellulose and polyethylene oxide to water and stirring. It can be prepared. For stirring, for example, equipment such as a mortar, a stirrer MAZWLA ZZ-2221 (product name, Tokyo Rika Kikai Co., Ltd.), Hibismix 2P-1 type (product name, Primix Corporation), etc. can be used.

  The content of the metal ion adsorbent in the dispersion is 1 to 99% by mass based on the total mass of the dispersion, from the viewpoint of securing good dispersibility, good impregnatability, simplicity of the separator production method, etc. can do.

  The content of the layered double hydroxide in the dispersion is 1 to 99% by mass based on the total mass of the dispersion from the viewpoint of securing good dispersibility, good impregnatability, simplicity of the separator production method, etc. It can be done.

  The content of the binder in the dispersion can be from 0 to 90% by mass based on the total mass of the dispersion from the viewpoint of good dispersibility, good impregnation, and the like.

  The dispersion thus prepared is depressurized for 20 minutes to 24 hours to remove air from the dispersion (defoaming), and then the whole nonwoven fabric is impregnated. The impregnation time can be about 20 minutes to 24 hours. In order to uniformly impregnate the non-woven fabric with the dispersion, it may be impregnated under reduced pressure.

  The separator of this embodiment can be obtained by drying the nonwoven fabric impregnated with the dispersion thereafter. The drying temperature and the drying time can be set to 35 to 60 ° C. and 20 minutes to 24 hours, respectively, from the viewpoint of completely removing the water in the separator. For drying, an apparatus such as, for example, a small high-temperature chamber ST-120B1 (product name, ESPEC Corp.) can be used. In the separator thus obtained, the layered double hydroxide is dispersed and supported in the nonwoven fabric, and has a symmetrical structure in terms of both function and appearance. Therefore, when incorporating in a secondary battery, it is not necessary to pay attention to the front and back of a separator, and complication of the manufacturing process of a secondary battery can be suppressed.

  The nickel electrode and the zinc electrode obtained as described above are alternately stacked via the separator of this embodiment, and electrode plates of the same polarity are connected by straps to produce an electrode plate group. The electrode plate group is disposed in a battery case to form an unformed nickel zinc secondary battery, into which an electrolytic solution is injected and left to stand, and then charged (chemical conversion treatment) under predetermined conditions to obtain nickel zinc. A secondary battery can be obtained.

  In addition, from the viewpoint of extending the cycle life of charge and discharge of the nickel zinc battery, for example, the positive electrode and the negative electrode may be sandwiched by hydrophilic polyolefin microporous membranes, if necessary.

[Zinc-air battery]
As mentioned above, although the case where the separator of this embodiment is integrated in a nickel zinc secondary battery was explained to the example, it is not limited to a nickel electrode especially about a positive electrode. An air electrode is mentioned as another positive electrode.

  As an air electrode, the well-known air electrode used for a zinc air battery is mentioned. The air electrode generally comprises an air electrode catalyst, an electron conductive material, and the like. When an air electrode catalyst that also functions as an electron conductive material is used, the air electrode may be such an electron conductive material and may include the air electrode catalyst.

  As an air electrode catalyst, what functions as a positive electrode in a zinc air battery is mentioned, and various air electrode catalysts which can use oxygen as a positive electrode active material can be used. As an air electrode catalyst, carbon based materials having a redox catalyst function such as graphite, metal materials having a redox catalyst function such as platinum and nickel, perovskite type oxide, manganese dioxide, nickel oxide, cobalt oxide, spinel oxide And inorganic oxide materials having a redox catalyst function. The shape of the cathode catalyst is not particularly limited, but may be, for example, in the form of particles. The content of the air electrode catalyst in the air electrode can be 5 to 70% by volume, may be 5 to 60% by volume, or 5 to 50% by volume with respect to the total amount of the air electrode.

  Examples of the electron conductive material include those having conductivity and enabling electron conduction between the cathode catalyst and the separator. Electron conductive materials include carbon blacks such as ketjen black, acetylene black, channel black, furnace black, lamp black, thermal black, natural graphite such as scale-like graphite, and graphite such as artificial graphite and exfoliated graphite Examples thereof include conductive fibers such as carbon fibers and metal fibers, metal powders such as copper, silver, nickel and aluminum, organic electron conductive materials such as polyphenylene derivatives, and arbitrary mixtures thereof. The shape of the electron conductive material may be in the form of particles or other shapes, but is preferably used in a form that provides a continuous phase in the thickness direction of the air electrode. For example, the electron conducting material may be a porous material. In addition, the electron conductive material may be in the form of a mixture or a complex with the air electrode catalyst, and as described above, may be an air electrode catalyst that also functions as an electron conductive material. The content of the electron conductive material in the air electrode may be 10 to 80% by volume, may be 15 to 80% by volume, or may be 20 to 80% by volume with respect to the total amount of the air electrode. .

  Next, the present invention will be described in more detail by the following examples, but these examples do not limit the present invention in any way.

Example 1
[Fabrication of nickel electrode]
A sponge-like nickel metal porous body having a porosity of 95% and 1.6 mm was adjusted to 1.2 mm by a roll press. In addition, 88 parts by mass of cobalt-coated nickel hydroxide powder having an average diameter of 20 microns, 8 parts by mass of cobalt powder as an additive, 2 parts by mass of cobalt oxide, 2 parts by mass of zinc oxide, and 30 parts by mass of a 2 mass% aqueous solution of carboxymethylcellulose Was filled with a paste-like active material. Thereafter, it was dried at 80 ° C. for 60 minutes, and then pressure-formed to 0.66 mm by a roll press to prepare a nickel electrode.

[Preparation of zinc electrode]
PTFE dispersion containing 60% by mass of PTFE in a mixed powder obtained by mixing 82 parts by mass of zinc oxide powder, 10 parts by mass of zinc powder, and 5 parts by mass of indium oxide as an additive (trade name of Mitsui DuPont Fluorochemicals; Teflon 31 -5 parts by mass of JR (Teflon is a registered trademark) and 10 parts by mass of water were added, and the mixture was kneaded for 15 minutes while applying shear stress in a mortar to obtain a kneaded product. Further, 40 parts by mass of water was added, and the mixture was kneaded for 15 minutes to obtain an active material paste. The paste is rolled to 1.0 mm with a roller to form a sheet, and two sheets cut to a predetermined size are placed on both sides of a 0.1 mm tin-plated copper punching metal as a current collector, pressure-formed, and then dried. Then, a 0.4 mm zinc electrode was produced.

[Preparation of imogolite]
The manufacturing method of the imogolite used by the present Example is shown. Concentration: 500 mL of a sodium orthosilicate aqueous solution having a concentration of 350 mmol / L was added to 500 mL of an aluminum chloride aqueous solution having a concentration of 700 mmol / L, and the mixture was stirred for 30 minutes. To this solution was added 330 mL of a 1 mol / L aqueous solution of sodium hydroxide to adjust to pH = 6.1. The pH-adjusted solution was stirred for 30 minutes, and then centrifuged for 5 minutes at a rotational speed of 3,000 revolutions / minute using Suprema 23 and Standard Rotor NA-16 manufactured by TOMY as a centrifugal separator. After centrifugation, the supernatant was drained and the gel-like precipitate was redispersed in pure water and returned to the volume before centrifugation. Such desalting treatment by centrifugation was performed three times. The gelled precipitate obtained after the third desalting treatment was discharged from the supernatant was dispersed in pure water to a concentration of 60 g / L, and made by HORIBA: F-55 and conductivity cell: 9382-10D. It was 1.3 S / m, when the electrical conductivity was measured at normal temperature (25 degreeC) using it. A gelled precipitate obtained after the third desalting treatment was discharged from the supernatant liquid was adjusted to pH = 3.5 by adding 135 mL of hydrochloric acid having a concentration of 1 mol / L and stirred for 30 minutes. The silicon atom concentration and the aluminum atom concentration in the solution at this time are measured by an ordinary method using ICP emission spectrometer: P-4010 (manufactured by Hitachi, Ltd.), and the silicon atom concentration is 213 mmol / L, aluminum The atomic concentration was 426 mmol / L. The solution was then placed in an oven and heated to 98 ° C. for 48 hours (2 days). After heating, 188 mL of a 1 mol / L aqueous solution of sodium hydroxide was added to the solution (aluminum silicate concentration 47 g / L) to adjust to pH = 9.1. The aluminum silicate in the solution was flocculated by pH adjustment, and this flocculate was precipitated by the same centrifugation as above, and the supernatant was drained. Pure water was added to this, and the desalting process of returning to the volume before centrifugation was performed 3 times. The gelled precipitate obtained after the third desalting treatment was discharged from the supernatant was dispersed in pure water to a concentration of 60 g / L, and made by HORIBA: F-55 and conductivity cell: 9382-10D. It was 0.6 S / m, when the electrical conductivity was measured at normal temperature (25 degreeC) using it. The gelled precipitate obtained after the third supernatant discharge was subjected to desalination treatment was dried at 60 ° C. for 16 hours to obtain 30 g of imogolite.

[Preparation of separator]
A carboxymethylcellulose solution was prepared by mixing 0.09 g of carboxymethylcellulose and 7.7 g of water. Thereafter, 1.5 g of imogolite, 6.5 g of a 60% solution of polytetrafluoroethylene, and the carboxymethyl cellulose solution prepared above were mixed to prepare an imogolite dispersion. The prepared hydrotalcite dispersion was then depressurized for 20 minutes for degassing to remove air in the dispersion.

  The prepared imogolite dispersion was impregnated for 20 minutes in a non-woven fabric VL-100 (product name, manufactured by Nippon Advanced Paper Industry Co., Ltd.). Thereafter, the non-woven fabric was taken out and suspended in a small high-temperature chamber ST-120B1 (product name, Primix Co., Ltd.) and dried at 50 ° C. for 20 minutes. Thereby, the separator provided with the non-woven fabric and the imogolite carried in the non-woven fabric was obtained. In this way, a symmetrical separator was obtained, which did not need to distinguish between the front and back.

[Fabrication of a nickel zinc secondary battery]
After covering one nickel electrode and two zinc electrodes obtained as described above with a microporous film of polypropylene / polyethylene which has been subjected to a hydrophilic treatment for the positive electrode and the negative electrode, they are alternately laminated via the separator of this embodiment, The electrode plates of the same polarity were connected by spot welding to produce an electrode plate group. The electrode plate group is disposed in a battery case to form an unformed nickel zinc secondary battery, and a 30% by mass aqueous solution of potassium hydroxide to which 1% by mass of lithium hydroxide is added as an electrolytic solution is injected for 24 hours I left it. Thereafter, charging (chemical conversion treatment) was performed under the conditions of 15 mA for 15 hours to prepare a nickel zinc secondary battery having a design capacity of about 150 mAh.

Example 2
A nickel zinc secondary battery was produced in the same manner as in the example except that a non-woven fabric impregnated with hydrotalcite was used as the separator.

[Preparation of separator]
A carboxymethylcellulose solution was prepared by mixing 0.09 g of carboxymethylcellulose and 7.7 g of water. Thereafter, 10.0 g of hydrotalcite (STABLACE HR-1 (product name, Sakai Chemical Industry Co., Ltd.)), 6.5 g of a 60% solution of polytetrafluoroethylene, and the carboxymethylcellulose solution prepared above are mixed, Talcite dispersions were prepared. The content of hydrotalcite in the dispersion was 41.2% by mass. The prepared hydrotalcite dispersion was then depressurized for 20 minutes for degassing to remove air in the dispersion.

  The prepared hydrotalcite dispersion was impregnated for 20 minutes in a non-woven fabric VL-100 (product name, manufactured by Nippon Advanced Paper Industry Co., Ltd.). Thereafter, the non-woven fabric was taken out and suspended in a small high-temperature chamber ST-120B1 (product name, Primix Co., Ltd.) and dried at 50 ° C. for 20 minutes. Thereby, the separator provided with the nonwoven fabric and the hydrotalcite supported in the nonwoven fabric was obtained. The content of hydrotalcite in the separator was 56.1% by mass based on the total mass of the separator. The content was measured by an electronic balance GX-600 (product name, A & D Co., Ltd.). In this way, a symmetrical separator was obtained, which did not need to distinguish between the front and back.

Example 3
A nickel zinc secondary battery was produced in the same manner as in the example except that a non-woven fabric impregnated with imogolite and hydrotalcite was used as a separator.

[Preparation of separator]
A carboxymethylcellulose solution was prepared by mixing 0.09 g of carboxymethylcellulose and 7.7 g of water. Thereafter, 1.5 g of imogolite, 8.5 g of hydrotalcite (STABLACE HR-1 (product name, Sakai Chemical Industry Co., Ltd.)), 6.5 g of a polytetrafluoroethylene 60% adjusting solution, and the carboxymethyl cellulose solution prepared above The mixture was mixed to prepare imogolite and hydrotalcite dispersions. The content of hydrotalcite in the dispersion was 41.2% by mass. The prepared hydrotalcite dispersion was then depressurized for 20 minutes for degassing to remove air in the dispersion.

  The prepared imogolite and hydrotalcite dispersion were impregnated for 20 minutes in a non-woven fabric VL-100 (product name, manufactured by Nippon High Paper Industry Co., Ltd.). Thereafter, the non-woven fabric was taken out and suspended in a small high-temperature chamber ST-120B1 (product name, Primix Co., Ltd.) and dried at 50 ° C. for 20 minutes. Thereby, the separator provided with the nonwoven fabric and the hydrotalcite supported in the nonwoven fabric was obtained. The imogolite content in the separator was 5.1% by mass based on the total mass of the separator. The content of hydrotalcite in the separator was 47.7% by mass based on the total mass of the separator. The content was measured by an electronic balance GX-600 (product name, A & D Co., Ltd.). In this way, a symmetrical separator was obtained, which did not need to distinguish between the front and back.

Comparative Example A nickel zinc secondary battery was produced in the same manner as in the example except that a non-woven fabric not impregnated with imogolite and hydrotalcite was used as a separator.

[Evaluation of self-discharge performance of nickel zinc secondary battery]
In order to confirm the self-discharge performance of the nickel zinc secondary battery obtained as described above, a capacity storage characteristic test was performed. As a condition of the capacity storage characteristic test, the battery was stored in an open circuit state for a certain period, and the self-discharge performance was evaluated from the retention rate of the discharge capacity before and after storage. Test temperature is 25 ° C, storage period is 30 days, measurement of discharge capacity before and after storage is constant current of discharge current 1C, discharge termination voltage 1.1V, depth of discharge 100%, charge current 1C, charge current The voltage was 1.9 V and constant voltage was applied for 4 hours.
Table 1 shows the results of the self-discharge rates calculated from the values of the discharge capacity before and after the test. The self-discharge rate was calculated as follows.
Self discharge rate (%) = (Discharge capacity before storage / Discharge capacity after storage after 30 days) × 100

  In addition, CA is a unit showing the characteristic of charging / discharging of a storage battery. C in CA is a unit representing the discharge rate of the storage battery, and A represents a unit such as an amperage representing a current value. The discharge rate is the relative ratio of the current during discharge to the battery capacity. The battery capacity indicates an amount of electricity which can be discharged and taken out by the end of the discharge, and the unit is Ah (ampere hour) or the like. 1C indicates a current value at which discharge is completed in one hour by performing constant current discharge on a cell having a capacity of a nominal capacity value. 1CA shows the current value which actually flows in the case of 1C.

  In Example 1, the discharge capacity after 30 days was maintained at 90%, while in Comparative Example 1, the discharge capacity was maintained at 85%. Thus, when the separator in which the nonwoven fabric was impregnated with imogolite was used, self-discharge was suppressed. That is, in the example, it became clear that the self-discharge of the nickel zinc battery can be suppressed and the discharge capacity after storage can be maintained.

[Evaluation of cycle performance of nickel zinc secondary battery]
In order to confirm the performance of the nickel zinc secondary battery obtained as described above, a charge and discharge cycle test was performed. As conditions for charge and discharge cycle test, test temperature is 25 ° C, discharge current is constant current of 0.5C, discharge termination voltage is 1.1V, depth of discharge is 100%, after discharge rest is 1 hour, charge is charging A cycle test was performed at a current of 1 C, a charge voltage of 1.9 V, and a constant voltage for 4 hours, and after charge and for 1 hour off. Moreover, the self-discharge rate in rest was measured by rest for 16 hours to 24 hours every 25 cycles and comparing the first discharge capacity after rest.
FIG. 1 shows the result of the charge and discharge cycle test of the embodiment. The discharge capacity retention rate was calculated as follows.
Discharge capacity retention rate (%) = (Discharge capacity at each cycle number / initial discharge capacity) × 100
Also, Table 2 shows the results of the self-discharge rate during the rest of 16 hours to 24 hours every 25 cycles. The self-discharge rate was calculated as follows.
Self-discharge rate (%) = (Discharge capacity before suspension / Discharge capacity after first pause) × 100

  In Example 2, although 152 cycles of charge and discharge cycle tests were conducted, the discharge capacity was maintained at 90.1%. Moreover, the self-discharge rate in 16 hours-24 hours for every 25 cycles was 10.8% at the maximum. Thus, the decrease in discharge capacity was suppressed by using the separator in which the non-woven fabric is impregnated with the hydrotalcite. That is, it became clear that the cycle life of the nickel zinc battery can be improved in the examples.

  Similarly, in Example 3, 152 cycles of charge and discharge cycle tests were conducted, but the discharge capacity was maintained at 98.6%. Moreover, the self-discharge rate in 16 hours-24 hours for every 25 cycles was 1.3% at the maximum. Thus, the decrease in discharge capacity and the self-discharge were suppressed by using the separator in which the non-woven fabric is impregnated with imogolite and hydrotalcite. That is, it became clear in the Example that the cycle life of the nickel zinc battery can be improved and the self-discharge can be suppressed.

  Similarly, in Comparative Example 1, the charge / discharge cycle test was conducted for 152 cycles, but the discharge capacity decreased to 50.2%. Moreover, since the battery voltage after 150 cycles fell to 0.3V vicinity, the measurement of discharge capacity was not possible in the self-discharge rate in 16 hours-24 hours for every 25 cycles. However, the self-discharge rate was 48.7% when calculated from the amount of discharged electricity immediately before the value. As described above, it has become clear that the use of a separator not impregnated with imogolite and / or hydrotalcite in the non-woven fabric can not maintain the discharge capacity of the battery and suppress the self-discharge.

Claims (6)

  Production of a separator for a zinc negative electrode secondary battery, comprising: an impregnation step of impregnating a non-woven fabric with a dispersion containing a metal ion adsorbent and / or layered double hydroxide into a non-woven fabric; and a drying step of drying the non-woven fabric impregnated with the dispersion. Method.   The method according to claim 1, wherein the content of the metal ion adsorbent in the dispersion is 1 to 99% by mass based on the total mass of the dispersion.   The method according to claim 1, wherein the content of the layered double hydroxide in the dispersion is 1 to 99% by mass based on the total mass of the dispersion.   A separator for a zinc negative electrode secondary battery, comprising a non-woven fabric and a metal ion adsorbent carried in the non-woven fabric.   A separator for a zinc negative electrode secondary battery comprising a non-woven fabric and a layered double hydroxide carried in the non-woven fabric.   The separator according to claim 4, which is a nickel zinc secondary battery separator.

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