JP2018147738A - Method of manufacturing separator for zinc negative electrode secondary battery and separator for zinc negative electrode secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a separator for a zinc negative electrode secondary battery which contains a layered double hydroxide and can secure ease of a process during manufacturing of a secondary battery.SOLUTION: A method of manufacturing a zinc negative electrode secondary battery includes: an impregnation step of impregnating fluid dispersion containing a layered double hydroxide into the nonwoven fabric; and a drying step of drying the nonwoven fabric impregnating the fluid dispersion therein.SELECTED DRAWING: None

Description

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

  As a nickel-zinc secondary battery separator, a laminate in which an anion conductive membrane containing a polymer and an inorganic compound is laminated on a nonwoven fabric or the like is known (for example, Patent Document 1). In this document, it is described that the separator can contain a layered double hydroxide in order to suppress the battery function deterioration due to zinc dendrite.

JP-A-2015-95286

  However, since such a laminated body necessarily has an asymmetric structure, it is necessary to perform an operation such as determining the front and back of the laminate and incorporating it into the secondary battery. Such an operation may make the manufacturing process of the secondary battery complicated.

  Accordingly, the present invention provides a method for producing a separator for a zinc negative electrode secondary battery and a separator for a zinc negative electrode secondary battery, which contain a layered double hydroxide and can ensure process easiness during the production of the secondary battery. The purpose is to provide.

  The present invention provides a separator for a zinc negative electrode secondary battery comprising a impregnation step of impregnating a nonwoven fabric with a dispersion containing a layered double hydroxide and a drying step of drying the nonwoven fabric impregnated with the dispersion (the negative electrode is zinc). And a secondary battery separator manufacturing method. ADVANTAGE OF THE INVENTION According to this invention, the separator which can ensure the process ease at the time of secondary battery manufacture can be manufactured. The separator obtained by the present invention has a simple structure in which a layered double hydroxide is dispersed and supported in a nonwoven fabric, and has a symmetrical structure in terms of function and appearance. Therefore, it is not necessary to pay attention to the front and back of the separator when incorporating into the secondary battery, and the complexity of the manufacturing process of the secondary battery can be suppressed.

  In the present invention, the content of the layered double hydroxide in the dispersion is preferably 1 to 99% by mass based on the total mass of the dispersion. Thereby, since it becomes easier to achieve good dispersibility, good impregnation property, simplicity of the separator preparation method, and the like, the impregnation step can be more suitably performed.

  The present invention also provides a separator for a zinc negative electrode secondary battery comprising a nonwoven fabric and a layered double hydroxide supported in the nonwoven fabric. According to the present invention, it is not necessary to pay attention to the front and back of the separator when incorporating into a secondary battery, and the complexity of the manufacturing process of the secondary battery can be suppressed.

  In this invention, it is preferable that content of a layered double hydroxide is 1-99 mass% on the basis of the total mass of a separator.

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

  ADVANTAGE OF THE INVENTION According to this invention, while containing layered double hydroxide, the manufacturing method of the separator for zinc negative electrode secondary batteries which can ensure the process ease at the time of secondary battery manufacture, and zinc negative electrode secondary battery A separator can be provided.

  The separator of this embodiment is a separator for a zinc negative electrode secondary battery incorporated in 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 includes a nickel (Ni) electrode as one of the positive electrode and the negative electrode, a zinc (Zn) electrode as the other electrode of the positive electrode and the negative electrode, a separator between both electrodes, and an alkali in which these are immersed. And an electrolytic solution made of an aqueous solution. The separator plays a role of electrically insulating the positive electrode and the negative electrode and conducting OH ⁻ ions through the micropore. An example of the battery reaction of the nickel zinc secondary battery is shown below (discharge reaction: rightward, charge reaction: leftward).
(Positive electrode) 2NiOOH + 2H ₂ O + 2e ⁻ → 2Ni (OH) ₂ + 2OH ⁻
(Negative electrode) Zn + 2OH ⁻ → Zn (OH) ₂ + 2e ⁻
(Overall) 2NiOOH + Zn + 2H ₂ O → 2Ni (OH) ₂ + Zn (OH) ₂

(Nickel pole)
The nickel electrode includes a current collector, and an active material layer including an active material mainly composed of nickel hydroxide particles, an additive, and a binder on the current collector. Cobalt, zinc, cadmium, magnesium, zirconium, or the like may be dissolved in nickel hydroxide as a raw material for the nickel hydroxide particles. Further, 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 may be 0.05 to 30 parts by mass with respect to 100 parts by mass of the active material, for example.

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

  Examples of the current collector include copper foil, electrolytic copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, punched brass, Examples thereof include nickel foil, nickel mesh, corrosion-resistant nickel, nickel mesh (expanded metal), punching nickel, foamed nickel, metal zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), steel plate, punched steel plate, and silver foil. These current collector materials may be further added with elements such as Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, and the surface of the current collector material is Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, or the like may be plated.

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

  Additives include metal oxides that are noble than the reduction potential of zinc, such as indium oxide, bismuth oxide, lead oxide, cadmium oxide, and thallium oxide, and metal oxides with high wettability, such as titanium oxide, aluminum oxide, and silicon oxide. , 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 a binder can be 0.5-10 mass parts with respect to 100 mass parts of active materials, for example. In addition, in a zinc electrode, it can replace with these binders and can also use the fiber (fiber) which consists of polyethylene, a polypropylene, aluminum oxide, etc.

  Examples of the electrolytic solution include alkaline aqueous solutions such as a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

(Separator)
As the separator (separator for nickel-zinc secondary battery), the separator of this embodiment including a nonwoven fabric and a layered double hydroxide supported in the nonwoven fabric is used. Since the separator of this embodiment is provided with the layered double hydroxide, it has selectivity for the permeating anion. That is, while anions such as hydroxide ions are likely to pass through the separator, metal ions (Zn (OH) ₄ ²⁻ ) derived from an active material having a large ionic radius even if anions are present. It is difficult to penetrate. Thereby, the growth of the zinc dendrite from the zinc electrode surface by charging / discharging can be suppressed.

  The nonwoven fabric is not particularly limited as long as it is processed from fibers usually used for nonwoven fabrics. Examples of such fibers include cellulose fibers, aramid fibers, glass fibers, nylon fibers, vinylon fibers, polyester fibers, polyolefin fibers (such as polyethylene fibers and polypropylene fibers), and rayon fibers. A manufacturing method is not specifically limited, For example, the general method provided with the process of forming the fleece from a fiber and couple | bonding the formed fleece is mentioned.

  The thickness of the nonwoven fabric can be set to 5 to 300 μm from the viewpoint of reducing ohmic resistance of the battery, increasing the energy density, and the like. Here, the thickness is an average value of 10 different thicknesses measured using a film thickness meter.

The porosity of a nonwoven fabric can be 10-95 volume% from a viewpoint which makes easy the maintenance of the amount of electrolyte solutions required for charging / discharging reaction, the mass transfer at the time of battery reaction, etc. The porosity can be obtained by the following formula from the area A (cm ² ) of the nonwoven fabric, the thickness t (cm), the mass (g) of the nonwoven fabric, and the density M (g / cm ³ ) of the fibers used.
Porosity (volume%) = {1-B / (M × A × t)} × 100

Examples of the layered double hydroxide include 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 · mH 2 O] x- ··· (1)

In the formula (1), L represents a divalent metal ion, and specific examples include Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Ni ²⁺ , Co ²⁺ , Cu ²⁺ , and Q is trivalent. Specifically, Al ³⁺ , Fe ³⁺ , Mn ^{3+ and the} like can be mentioned. A represents an n-valent anion, 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), as compounds excellent in economic efficiency and availability, those in which L is Mg ²⁺ , Q is Al ³⁺ , and A is CO ₃ ²⁻ Can be mentioned. Such hydrotalcite compounds include STABLACE HR-1, STABLACE HR-7, STABLACE HR-P (product name, Sakai Chemical Industry Co., Ltd.), DHT-4A, DHT-4A-2, DHT-4C, and DHT. -4H (product name, manufactured by Kyowa Chemical Industry Co., Ltd.), IXE-700F (product name, manufactured by Toagosei Co., Ltd.), and the like.

  The average particle size of the layered double hydroxide can be set to 0.3 to 10 μm from the viewpoint of good dispersibility in the dispersion described later and good filling properties into the nonwoven fabric voids. The average particle diameter 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, a product obtained by firing the hydrotalcite compound represented by the above formula (1) at a high temperature (for example, about 500 ° C.) can also be used.

  The content (supported amount) of the layered double hydroxide in the nonwoven fabric is from 1 to 99 on the basis of the total mass of the separator from the viewpoint of coexistence of anion selectivity and retention of the amount of electrolyte necessary for charge / discharge reaction. It can be made into the mass%. Moreover, the said content can be 1-99 volume% on the basis of the whole volume of a separator. The supported amount of the 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”). Etc. can be used to separate the mass of the nonwoven fabric and the layered double hydroxide 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, SEM. Specifically, the volume is calculated from the ratio of the nonwoven fabric fibers and the ratio of the layered double hydroxide in the SEM image, and the average value of the volume per 10 SEM images is the volume of the layered double hydroxide. can do.

  In the nonwoven fabric, compounds other than the layered double hydroxide can also be supported. It is an additive mainly used in the production of the positive electrode and the negative electrode active material, and examples thereof include binders such as carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene oxide, and polytetrafluoroethylene. The content of these additives can be set to such an extent that does not impair the properties 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 polyolefin microporous membranes, nylon microporous membranes, oxidation-resistant ion exchange resin membranes, cellophane-based recycled resin membranes, and inorganic-organic separators may be used in combination with the separator of this embodiment. Good. In this case, for example, a mode in which the positive electrode and the negative electrode are sandwiched between other separators and these are stacked via the separator of the present embodiment can be mentioned. By using another separator (for example, a hydrophilic polyolefin-based microporous membrane) in combination, for example, it is easy to achieve negative electrode shape change, aggregation and dendrite suppression, negative electrode conductivity improvement, etc. It becomes easy to extend the charge / discharge cycle life of the battery.

[Manufacturing method of nickel zinc secondary battery]
The manufacturing method of a nickel electrode and a zinc electrode is not specifically limited, For example, the following methods are mentioned. That is, each raw material for obtaining an active material layer and water are kneaded to prepare an active material paste, which is applied onto 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, this is dried and further subjected to pressure molding by a roller press to obtain an electrode having an active material layer on the current collector. Note that it is also possible to obtain an electrode by rolling only the active material paste in advance to form a sheet, press-bonding this to a current collector, press-molding, and drying.

  The separator can be obtained by a method comprising an impregnation step of impregnating a nonwoven fabric with a dispersion containing a layered double hydroxide and a drying step of drying the nonwoven fabric impregnated with the dispersion.

  The dispersion can be prepared by adding layered double hydroxide and, for example, binders such as carboxymethyl cellulose, polytetrafluoroethylene, hydroxyethyl cellulose, polyethylene oxide and the like to water and stirring. For the stirring, for example, a mortar, a stirrer MAZWLA ZZ-2221 (product name, Tokyo Rika Kikai Co., Ltd.), Hibismix 2P-1 type (product name, Primix Co., Ltd.) or the like can be used.

  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 viewpoints of ensuring good dispersibility, good impregnation properties, simplicity of the separator preparation method, and the like. It can be.

  The content of the binder in the dispersion can be 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 (defoamed) air in the dispersion, and then impregnated throughout the nonwoven fabric. The impregnation time can be about 20 minutes to 24 hours. In order to uniformly impregnate the non-woven fabric with the dispersion, the nonwoven fabric may be impregnated under reduced pressure.

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

  The nickel electrode and the zinc electrode obtained as described above are alternately stacked via the separator of the present embodiment, and the electrode plates having the same polarity are connected with a strap to produce an electrode plate group. This electrode group is placed in a battery case to form an unformed nickel-zinc secondary battery. After injecting an electrolyte into the secondary battery, it is left to charge and then charged (chemical conversion treatment) under predetermined conditions. A secondary battery can be obtained.

  If necessary, from the viewpoint of extending the charge / discharge cycle life of the nickel-zinc battery, for example, the positive electrode and the negative electrode may be sandwiched between hydrophilic polyolefin microporous membranes.

[Zinc-air battery]
The case where the separator of this embodiment is incorporated in a nickel zinc secondary battery has been described above as an example, but the positive electrode is not particularly limited to a nickel 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 includes 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 include an air electrode catalyst.

  Examples of the air electrode catalyst include those that function as a positive electrode in a zinc-air battery, and various air electrode catalysts that 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 oxide, manganese dioxide, nickel oxide, cobalt oxide, spinel oxide Examples thereof include inorganic oxide materials having a redox catalyst function. Although the shape of an air electrode catalyst is not specifically limited, For example, it can be set as a particle shape. The content of the air electrode catalyst in the air electrode can be 5 to 70% by volume, 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 a material having conductivity and enabling electron conduction between the air electrode catalyst and the separator. As an electron conductive material, carbon blacks 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, 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 a particle shape or any other shape, but is preferably used in a form that provides a continuous phase in the thickness direction at the air electrode. For example, the electron conductive material may be a porous material. Further, the electron conductive material may be in the form of a mixture or a complex with an air electrode catalyst, or may be an air electrode catalyst that also functions as an electron conductive material as described above. 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 with reference to the following examples, but these examples do not limit the present invention.

Example [Preparation 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. Further, 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% by mass aqueous solution of carboxymethyl cellulose The paste-like active material made by mixing was filled. Thereafter, the film was dried at 80 ° C. for 60 minutes, and then pressure-formed to 0.66 mm by a roll press to produce a nickel electrode.

[Production of zinc electrode]
PTFE dispersion containing 60% by mass of PTFE (trade name manufactured by Mitsui DuPont Fluoro Chemical Co., Ltd .; Teflon 31) mixed with 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 -5 parts by weight of JR (Teflon is a registered trademark) and 10 parts by weight of water were added and kneaded for 15 minutes while applying a shear stress in a mortar to obtain a kneaded product. Furthermore, 40 parts by mass of water was added and kneaded for 15 minutes to obtain an active material paste. This paste is rolled to a sheet of 1.0 mm with a roller, and two sheets cut to a predetermined size are placed on both sides of a current collector 0.1 mm tin-plated copper punching metal, pressed and dried. Thus, a 0.4 mm zinc electrode was produced.

[Preparation of separator]
Carboxymethylcellulose solution was prepared by mixing 0.09 g of carboxymethylcellulose and 7.7 g of water. Then, hydrotalcite (STABLACE HR-1 (product name, Sakai Chemical Industry Co., Ltd.)) 10.0 g, polytetrafluoroethylene 60% adjustment solution 6.5 g, and the carboxymethylcellulose solution prepared above were mixed, A talcite dispersion was 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 with a nonwoven fabric VL-100 (product name, manufactured by Nippon Kogyo Paper Industries Co., Ltd.) for 20 minutes. Thereafter, the nonwoven fabric was taken out, suspended in a small high temperature chamber ST-120B1 (product name, Primics Co., Ltd.), and dried at 50 ° C. for 20 minutes. Thereby, the separator provided with a nonwoven fabric and the hydrotalcite carry | 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 weighed with an electronic balance GX-600 (product name, A & D Co., Ltd.). In this way, a symmetrical separator that does not need to be distinguished between the front and the back was obtained.

[Production of nickel zinc secondary battery]
After wrapping one nickel electrode and two zinc electrodes obtained as described above with a polypropylene / polyethylene microporous membrane in which the positive electrode and the negative electrode are hydrophilized, the layers are alternately laminated via the separator of this embodiment, Electrode plates of the same polarity were connected by spot welding to produce a group of electrode plates. This electrode group was placed in a battery case to form an unformed nickel-zinc secondary battery, and a 30% by weight aqueous solution of potassium hydroxide to which 1% by weight of lithium hydroxide was added as an electrolytic solution was poured into the battery for 24 hours. I left it alone. Thereafter, charging (chemical conversion treatment) was performed under conditions of 15 mA for 15 hours, and a nickel zinc secondary battery having a design capacity of about 150 mAh was produced.

-Comparative example The nickel zinc secondary battery was produced like the Example except having used the nonwoven fabric which does not impregnate hydrotalcite as a separator.

[Evaluation of nickel zinc secondary battery]
In order to confirm the performance of the nickel zinc secondary battery obtained as described above, a discharge test in which the discharge current was changed was performed. In the discharge test, the discharge characteristics were evaluated by changing the discharge current to 0.05C, 0.2C, 1C, 3C, 5C, and 10C. As conditions for the discharge test, the test temperature was set to 25 ° C., and the discharge start voltage was set to 1.1V. Further, as charging conditions after each discharge test, the test temperature was set to 25 ° C., the charging current was set to 0.1 C, and the charging capacity was set to 150% with respect to the design capacity.
Table 1 shows the results of the discharge test of the embodiment. The discharge capacity retention rate was calculated as follows. The results of the discharge test are shown in Table 1.
Discharge capacity retention rate (%) = (discharge capacity at each discharge rate / discharge capacity at 0.05 C) × 100

  CA is a unit that represents the charge / discharge characteristics of the storage battery. C in CA is a unit representing the discharge rate of the storage battery, and A represents a unit such as an ampere representing a current value. The discharge rate is a relative ratio of current during discharge to battery capacity. The battery capacity indicates the amount of electricity that can be discharged and taken out before the end of discharge, and its unit is Ah (ampere hour) or the like. 1C indicates a current value at which discharge of a single cell having a capacity of a nominal capacity value is constant-current discharged and discharge is completed in one hour. 1CA indicates a current value that actually flows in the case of 1C.

  The discharge capacity retention rate corresponds to the value of the discharge capacity that is the capacity of the storage battery after discharging in each discharge test. In particular, the discharge capacity of the 0.05C discharge test is defined as 100% as the initial capacity, and the subsequent discharge capacity values of 0.2C, 1C, 3C, 5C, and 10C are shown.

  In the example, the discharge capacity at the maximum discharge current of 10 C was maintained at 54%, whereas in the comparative example, the discharge capacity at the discharge current of 10 C was maintained at 69%. Thus, even if the separator which impregnated the hydrotalcite to the nonwoven fabric was used, the capacity | capacitance fall was fully suppressed. That is, in the examples, it was revealed that the nickel-zinc battery can be charged and discharged, and the capacity can be maintained even when discharging with a large current.

Claims (5)

  A method for producing a separator for a zinc negative electrode secondary battery, comprising: an impregnation step of impregnating a nonwoven fabric with a dispersion containing a layered double hydroxide; and a drying step of drying the nonwoven fabric impregnated with the dispersion.   The manufacturing method of Claim 1 whose content of the said layered double hydroxide in the said dispersion liquid is 1-99 mass% on the basis of the total mass of a dispersion liquid.   A separator for a zinc negative electrode secondary battery, comprising a nonwoven fabric and a layered double hydroxide supported in the nonwoven fabric.   The separator according to claim 3, wherein the content of the layered double hydroxide is 1 to 99% by mass based on the total mass of the separator.   The separator according to claim 3 or 4, which is a separator for a nickel zinc secondary battery.