JP6558906B2 - Separator and battery comprising the same - Google Patents

Description

The present invention relates to a separator and a battery including the separator. More specifically, the present invention relates to a separator that can be suitably used particularly for a battery including a zinc negative electrode, and a battery including the separator.

In recent years, the importance of development and improvement of batteries has been increasing in many industries from portable devices to automobiles mainly in terms of performance and secondary battery.

Batteries, especially secondary batteries composed of negative electrodes containing zinc species, cadmium species, and lithium species, undergo a metal dissolution and precipitation reaction in the vicinity of the electrode active material layer, etc., after repeated charge and discharge for a long period of time. However, there is a problem that the shape change of the electrode active material called shape change occurs, resulting in capacity deterioration and shortening of the life.

For such a problem, for example, an anion conductive material containing a polymer and a compound containing at least one element selected from Group 1 to Group 17 of the periodic table, and the anion conductive material are included. A battery comprising a battery constituent member constituted by the above is disclosed, and as the battery constituent member, at least one selected from the group consisting of a separator, a positive electrode, a negative electrode, and an electrolyte is disclosed (for example, Patent Document) 1).

A metal-air battery including a positive electrode layer, a negative electrode layer, and an electrolyte layer between the positive electrode layer and the negative electrode layer, the metal-air battery including a porous metal body between the negative electrode layer and the electrolyte layer. Is disclosed (for example, see Patent Document 2).

International Publication No. 2014/119665 JP 2014-49408 A

For example, when zinc is used for the negative electrode of the secondary battery, as described above, the positive electrode and the negative electrode are short-circuited by the dendrite formed on the zinc surface during charging, and the battery is killed. In order to prevent this, the present inventor has developed an anion conductive membrane as described in Patent Document 1 and aims to put the zinc secondary battery into practical use. However, only the compositional features of the anion conductive membranes proposed so far as described in Patent Document 1 described above have room for further enhancing the effect of suppressing the shape change.

In a long-term cycle test, the shape change of an active material such as zinc species due to charging / discharging becomes a problem. Controls the deposition mode of the active material when the active material dissolves / precipitates with the battery reaction, such as the secondary battery configured using the negative electrode containing zinc species, cadmium species, and lithium species described above. It is extremely important to do. If the deposition form of the active material is not controlled, the shape change proceeds each time the charge / discharge reaction is repeated, and the negative electrode active material is depleted and the capacity is reduced, or hydrogen gas is generated. Arise. This is one of the important issues in battery development.

The above-described problems related to shape change are particularly important in batteries using any one of a zinc negative electrode, a cadmium negative electrode, and a lithium negative electrode, but batteries using other electrodes are also included. In response to this problem, the present inventors have attempted to suppress dendrite with an anion conductive membrane so far, but there is room for further contrivance, particularly regarding the suppression of the shape change of the active material accompanying the long-term use of the battery. .

This invention is made | formed in view of the said present condition, and aims at providing the battery which can suppress the shape change of the active material accompanying a long-term use of a battery.

The present inventor considered that one of the causes of the active material shape change accompanying the long-term use of the battery is non-uniformity of the current distribution in the negative electrode surface. The present inventor, if there is a current distribution (current concentration) in any of the electrodes such as the positive electrode and the negative electrode and the separator, all battery constituent members are affected, for example, the current concentration in the zinc negative electrode If it occurred, the oxidation-reduction reaction of the zinc species in that part would be activated locally, so it was thought that the shape change would be large. The present inventor believes that this causes the active material such as zinc species to be unevenly distributed in the negative electrode surface during long-term use of the battery, causing a short circuit, a decrease in capacity, gas generation, etc. with the positive electrode. It was. Based on this idea, the present inventor has made various studies focusing on making the current distribution in the negative electrode surface more uniform and using a separator used for the battery for that purpose. As a result of intensive studies, the inventor assumed that the separator used in the battery has a multilayer structure including an insulating layer and a conductive layer, and the conductive layer is electrically insulated from the electrode through the insulating layer. Was placed in the battery. Thus, it has been found that the separator can exhibit a function of rectifying current in a direction perpendicular to the positive electrode and the negative electrode, that is, a function of flowing the current uniformly without creating a current density distribution from the positive electrode to the negative electrode. As a result, it has been found that the current distribution on the negative electrode surface of the battery can be made more uniform, the shape change of the active material accompanying the long-term use of the battery can be highly suppressed, and the battery can be extended in life. This is what I came up with.

Although the invention described in Patent Document 2 is described as related to a metal-air battery, the substantial content is specialized for a lithium-air battery using a lithium electrode. In this case, the basic reaction is a charge / discharge reaction due to the insertion / desorption phenomenon of lithium ions. Here, the occurrence of dendrites is also a phenomenon that becomes a problem when overcharging or the like occurs. In order to suppress this, in the metal-air battery described in Patent Document 2, the gap between the negative electrode layer and the electrolyte layer is reduced. By providing a metal porous body, the current is dispersed. On the other hand, Patent Document 2 shows that the porous metal body 5 is disposed on the negative electrode layer 3 so as to be in contact with the negative electrode layer 3 in FIGS. 1 and 3. Insulation (floating) is not disclosed. Such a metal-air battery described in Patent Document 2 makes the current distribution on the electrode surface uniform by making the current flow evenly without creating a current density distribution from the positive electrode to the negative electrode as in the present invention. Could not be suppressed. In addition, when the invention described in Patent Document 2 is applied to a battery using a negative electrode for an aqueous electrolyte such as a zinc electrode, if a conductive metal porous body is disposed on the negative electrode, the metal porous body will collect current. Since it plays the same function as the body, it is considered that during charging, a metal such as zinc is deposited on the metal porous body and dendrites are formed. On the other hand, in the present invention, even when a negative electrode for an aqueous electrolyte such as a zinc electrode is used, dendrite formation as considered in the invention described in the cited document 2 does not occur.

That is, the present invention is a separator used in a battery, and the separator has a multilayer structure including an insulating layer and a conductive layer.
Moreover, this invention is also a battery comprised including the separator of this invention, an electrode, and electrolyte.

The present invention is described in detail below.
In addition, the form which combined two or more each preferable form of this invention described below is also a preferable form of this invention.

<Separator of the present invention>
The separator of the present invention has a multilayer structure including an insulating layer and a conductive layer. The multilayer structure only needs to include at least one insulating layer and one conductive layer. The separator may be any member that separates the positive electrode and the negative electrode and retains the electrolyte solution to ensure ionic conductivity between the positive electrode and the negative electrode. It may be one that works to avoid liquid drainage.

In the separator of the present invention, it is important that the conductive layer has (1) sufficient electron conductivity. When the battery is formed using the separator of the present invention, the conductive layer is (2) the positive electrode. It is important that the electrode is electrically insulated from an electrode such as a negative electrode (becomes electrically floating).

Regarding the above (2), the separator of the present invention has a multilayer structure including an insulating layer and a conductive layer, but preferably includes a conductive layer sandwiched between insulating layers. Thereby, when a battery is comprised using a separator, it will contain at least 1 the conductive layer insulated from both the positive electrode and the negative electrode, and the effect which suppresses a shape change can fully be exhibited. Here, that the conductive layer is sandwiched between the insulating layers means that the insulating layers are disposed on both sides in the thickness direction of the conductive layer.
That is, the separator of the present invention preferably includes a three-layer structure of insulating layer / conductive layer / insulating layer. The separator of the present invention includes a three-layer structure of insulating layer / conductive layer / insulating layer as long as it includes at least these three layers. Resistance may increase or battery performance may decrease. Unless otherwise specified, one or more conductive layers and / or one or more insulating layers may be further provided on the insulating layer and / or between the insulating layer and the conductive layer. For example, the separator of the present invention may have a four-layer structure of conductive layer / insulating layer / conductive layer / insulating layer.
In particular, the separator of the present invention has a three-layer structure of insulating layer / conductive layer / insulating layer, that is, one conductive layer is sandwiched between two insulating layers. Is one of the particularly preferred forms.

[Conductive layer]
With respect to the above (1), the conductive layer of the separator of the present invention only needs to have a conductivity higher than that of the electrolytic solution, and various types can be used as the conductive layer as long as it is limited. The conductive layer preferably has a conductivity exceeding 0.1 S / cm [Siemens per centimeter]. In other words, the conductive layer preferably has an electrical resistance value of less than 10 Ω · cm.

The conductive layer preferably has an electric resistance value of 5 Ω · cm or less, more preferably 3 Ω · cm or less, still more preferably 1 Ω · cm or less, and further preferably 0.3 Ω · cm or less. It is particularly preferred. The electrical resistance value is preferably 0.0001 Ω · cm or more, more preferably 0.001 Ω · cm or more, and further preferably 0.01 Ω · cm or more.
The electrical resistance value can be determined by the 4-short-needle method described in JIS H 0602-1995 or JIS K 7194-1994, and can be measured using Mitsubishi Chemical's Loresta-GP, Solartron's impedance analyzer 1260, or the like. .

The average thickness of the conductive layer is preferably 10 μm or more, for example. More preferably, it is 50 micrometers or more, More preferably, it is 100 micrometers or more. Moreover, it is preferable that this average thickness is 2000 micrometers or less. More preferably, it is 1000 micrometers or less, More preferably, it is 500 micrometers or less.
The average thickness of the conductive layer can be calculated by arbitrarily measuring five points with a micrometer. When there are a plurality of the conductive layers, the sum of the average thicknesses of the respective layers of the conductive layer can be set as the thickness of the conductive layer.

Examples of the conductive layer include (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, nickel Foil, corrosion-resistant nickel, nickel mesh (expanded metal), punching nickel, metal zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, anion conductive membrane with conductivity, conductivity Non-woven fabric, Ni / Zn / Sn / Pb / Hg / Bi / In / Tl / Brass (electrolytic) copper foil / copper mesh (expanded metal) / copper alloy such as foamed copper / punched copper / brass / Brass foil, brass mesh (expanded metal), foamed brass, punched brass, nickel foil, corrosion-resistant nickel Nickel mesh (expanded metal), punched nickel, metallic zinc, corrosion-resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel plate, anion conductive material, non-woven fabric; Ni, Zn, Sn, Pb, Hg, Bi -In, Tl, brass plated (electrolytic) copper foil, copper mesh (expanded metal), foamed copper, punched copper, copper alloys such as brass, brass foil, brass mesh (expanded metal), foamed brass, punching Brass, nickel foil, corrosion resistant nickel, nickel mesh (expanded metal), punched nickel, metal zinc, corrosion resistant metal zinc, zinc foil, zinc mesh (expanded metal), (punched) steel sheet, non-woven fabric; silver; copper, brass, nickel, Examples include porous metal bodies composed of zinc, steel, silver, etc. That. Among them, an anion conductive film imparted with conductivity, a metal mesh such as a copper mesh, and a metal porous body such as a copper porous body are preferable, and an anion conductive film imparted with conductivity is more preferable.

Suitable examples of the anion conductive membrane imparted with conductivity include those formed using an anion conductive material containing a polymer and an inorganic substance and a conductive substance.

Preferred examples of the conductive material include conductive carbon materials, conductive ceramics, zinc / zinc powder / zinc alloys, copper, brass, nickel, silver, bismuth, indium, lead, tin, and the like. One or more of these can be used, and among these, a conductive carbon material is more preferable.

Examples of the conductive carbon material include natural graphite, artificial graphite, glassy carbon, amorphous carbon, graphitizable carbon, non-graphitizable carbon, carbon nanofoam, activated carbon, graphene, nanographene, graphene nanoribbon, fullerene, carbon black, carbon fiber , Fiber carbon, carbon nanotube, carbon nanohorn, Vulcan, ketjen black, acetylene black and the like, and one or more of these can be used. For example, natural graphite and artificial graphite are preferable.

When the conductive layer is an anion conductive film imparted with conductivity, the ratio of the conductive material is preferably 0.1% by mass or more in 100% by mass of the conductive layer. More preferably, it is 1 mass% or more, More preferably, it is 2 mass% or more, Most preferably, it is 5 mass% or more. Moreover, it is preferable that the ratio of this electrically conductive substance is 70 mass% or less. More preferably, it is 50 mass% or less, More preferably, it is 30 mass% or less, Most preferably, it is 20 mass% or less.

Below, the anion conductive material used for forming the anion conductive film | membrane which provided the said electroconductivity is demonstrated.

In this specification, an anion conductive membrane is a material that transmits anions such as hydroxide ions involved in battery reactions. The anion conductive membrane of the present invention has the selectivity of the permeating anion by the action of an inorganic substance or the like described later. For example, it is easy to permeate anions such as hydroxide ions, and even if it is an anion, the permeation of metal-containing ions (for example, Zn (OH) ₄ ²⁻ ) derived from an active material having a large ion radius is sufficiently prevented. To do. In this specification, the anion conductivity means that an anion having a small ion radius such as a hydroxide ion is sufficiently transmitted, or the permeation performance of the anion. Anions having a large ion radius, such as metal-containing ions, are more difficult to permeate and may not permeate at all.

The inorganic substance contained in the anion conductive material is preferably a compound containing at least one element selected from Group 1 to Group 17 of the periodic table (hereinafter also referred to as an inorganic compound).
As at least one element selected from Group 1 to Group 17 of the periodic table, alkali metal, alkaline earth metal, Sc, Y, lanthanoid, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo W, Mn, Fe, Ru, Co, Ni, Pd, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, C, Si, Ge, Sn, Pb, N, P, Sb , Bi, S, Se, Te, F, Cl, and at least one element selected from the group consisting of Br is preferable. Among these, at least one element selected from Group 1 to Group 15 of the periodic table is more preferable, Li, Na, K, Cs, Mg, Ca, Ba, Sc, Y, lanthanoid, Ti, Zr, Nb, Cr, Mn, Fe, Ru, Co, Ni, Pd, Cu, Ag, Au, Zn, Cd, B, Al, Ga, In, Tl, C, Si, Ge, Sn, Pb, N, P, Sb, And at least 1 element chosen from the group which consists of Bi is still more preferable. Particularly preferably, Li, Mg, Ca, Ba, Sc, Y, lanthanoid, Ti, Zr, Nb, Cr, Mn, Fe, Ru, Co, Ni, Pd, Cu, Zn, Cd, B, Al, Ga, It is at least one element selected from the group consisting of In and Tl.

Examples of the inorganic compound include oxides; complex oxides; layered double hydroxides; hydroxides; clay compounds; solid solutions; alloys; zeolites; halides; carboxylate compounds; A sulfuric acid compound; a sulfonic acid compound; a phosphoric acid compound such as hydroxyapatite; a phosphorous compound; a hypophosphorous acid compound, a boric acid compound; a silicic acid compound; an aluminate compound; a sulfide; an onium compound; Preferably, oxides; complex oxides; layered double hydroxides such as hydrotalcite; hydroxides; clay compounds; solid solutions; zeolites; fluorides; phosphoric acid compounds; boric acid compounds; A salt.
Among these, the inorganic compound is preferably at least one compound selected from the group consisting of oxides, hydroxides, layered double hydroxides, sulfuric acid compounds, and phosphoric acid compounds. More preferably, it is at least one compound selected from the group consisting of oxides, hydroxides, layered double hydroxides, and sulfuric acid compounds, and more preferably layered double hydroxides and / or oxides. .

The layered double hydroxide is preferably hydrotalcite, for example. Thereby, the anion conductivity of the anion conductive material can be remarkably improved.
The hydrotalcite is represented by the following formula (1);
[M ¹ _1-x M ² _x (OH) ₂ ] (A ⁿ⁻ ) _{x / n} · mH ₂ O (1)
^{(M 1} are, Mg, Fe, Zn, Ca , Li, Ni, Co, .M 2 represent either a Cu are, ^{.A n-is} representing Al, Fe, one of Mn, 1 to 3-valent M is a number of 0 or more, n is a number of 1 to 3, x is a number of 0.20 to 0.40), and 150 By calcining at a temperature of from 900 to 900 ° C., a dehydrated compound, a compound in which anions in the interlayer are decomposed, a compound in which the anions in the interlayer are exchanged with hydroxide ions, etc., Mg ₆ Al ₂ which is a natural mineral (OH) ₁₆ CO ₃ .mH ₂ O or the like may be used as the inorganic compound. The hydrotalcite may be coordinated with a compound having a functional group such as a hydroxyl group, an amino group, a carboxyl group, or a silanol group.
The monovalent to trivalent anion represented by ^{A n-} in the above formula ^{_{(1), CO 3 2-,}} OH - , and the like.

As the oxide, for example, cerium oxide and zirconium oxide are preferable. More preferably, it is cerium oxide. In addition, the cerium oxide may be, for example, a material doped with a metal oxide such as samarium oxide, gadolinium oxide, or bismuth oxide, or a solid solution with a metal oxide such as zirconium oxide. It may have an oxygen defect.

As the hydroxide, for example, cerium hydroxide and zirconium hydroxide are preferable. The sulfuric acid compound is preferably ettringite, for example.

The phosphoric acid compound is preferably, for example, hydroxyapatite.
The hydroxyapatite is a compound typified by Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , a compound in which the amount of Ca is reduced depending on the conditions during preparation, a hydroxyapatite compound into which an element other than Ca is introduced, etc. May be used as the inorganic compound.

The layered double hydroxide contained in the anion conductive membrane has the ability to selectively permeate the anion by its ionic radius. For example, “Layered Double Hydroxide”, [online], 2011 6 Monthly release, National Institute of Advanced Industrial Science and Technology, [October 22, 2013 search] Internet, <URL: http://unit.aist.go.jp/emtech-ri/ci/e-keyword/LDH /ldh.html>, Yuya Asada and three others, "Anion transport properties of Mg-Al-based layered double hydroxides with controlled host cation ratio", Proceedings of the Electrochemical Society Conference, Vol. 79, 2012 It is suggested from technical information such as p284 issued on March 29. In addition to the layered double hydroxide, the oxide, hydroxide, phosphoric acid compound, and sulfuric acid compound according to the present invention can exhibit the ability to selectively permeate the anion by its ionic radius.

The proportion of the inorganic substance is preferably 1% by mass or more in 100% by mass of the conductive layer. More preferably, it is 5 mass% or more, More preferably, it is 10 mass% or more, Most preferably, it is 30 mass% or more. Moreover, it is preferable that the ratio of this inorganic substance is 99 mass% or less. More preferably, it is 90 mass% or less, More preferably, it is 60 mass% or less, Most preferably, it is 50 mass% or less.

Examples of the polymer contained in the anion conductive material in the present invention include hydrocarbon moiety-containing polymers such as polyethylene and polypropylene, aromatic group-containing polymers represented by polystyrene, etc .; ether group-containing polymers represented by alkylene glycol, etc .; polyvinyl alcohol Hydroxyl group-containing polymers such as poly (α-hydroxymethyl acrylate), etc .; polyamide, nylon, polyacrylamide, amide bond-containing polymers such as polyvinylpyrrolidone and N-substituted polyacrylamide; and polymaleimide Imide bond-containing polymer; carboxyl group-containing polymer represented by poly (meth) acrylic acid, polymaleic acid, polyitaconic acid, polymethyleneglutaric acid, etc .; poly (meth) acrylate, polymaleate, polyi Carboxylate-containing polymers such as concates and polymethylene glutarates; halogen-containing polymers such as polyvinyl chloride, polyvinylidene fluoride, and polytetrafluoroethylene; Bonded polymer; sulfonate moiety-containing polymer; AR ¹ R ² R ³ B (A represents N or P. B represents an anion such as a halogen anion or OH ^−. R ¹ , R ² , R ³ Are the same or different and each represents an alkyl group having 1 to 7 carbon atoms, a hydroxyalkyl group, an alkyl carboxyl group, or an aromatic ring group, and R ¹ , R ² , and R ³ may combine to form a ring structure. A polymer containing a quaternary ammonium salt or a quaternary phosphonium salt represented by a polymer having a group represented by Natural rubber; Artificial rubber represented by styrene butadiene rubber (SBR), etc .; Cellulose, cellulose acetate, hydroxyalkyl cellulose (for example, hydroxyethyl cellulose), carboxymethyl cellulose, chitin, chitosan, alginic acid ( Saccharides such as salt); amino group-containing polymers represented by polyethyleneimine; carbamate group site-containing polymers; carbamide group site-containing polymers; epoxy group site-containing polymers; heterocycles and / or ionized heterocycle sites A polymer containing alloy; a heteroatom-containing polymer; a low molecular weight surfactant and the like.
Of these, carboxyl group-containing polymers and / or halogen-containing polymers are preferred. More preferred are fluorine-containing polymers such as polyvinylidene fluoride and polytetrafluoroethylene. When manufacturing the said anion conductive film, it is preferable to use the method including the process of rolling an electrically conductive substance and an anion conductive material. At this time, if the anion conductive material contains a fluorine-containing polymer, a strong force is applied to the fluorine-containing polymer at the time of rolling to promote the fiberization of the polymer, and as a result, the physical strength of the anion conductive membrane is improved. Therefore, the effect of preventing a short circuit between the electrodes due to the growth of dendrites is further enhanced.

Polymer is radical polymerization, radical (alternate) copolymerization, anion polymerization, anion (alternate) copolymerization, cationic polymerization, cationic (alternate) copolymerization, graft polymerization, graft (alternate) copolymerization from monomers corresponding to the structural unit. , Living polymerization, living (alternate) copolymerization, dispersion polymerization, emulsion polymerization, suspension polymerization, ring-opening polymerization, cyclization polymerization, polymerization by light, ultraviolet ray or electron beam irradiation, metathesis polymerization, electrolytic polymerization, etc. . When these polymers have a functional group, they may be present in the main chain and / or side chain, and may exist as a binding site with a crosslinking agent. These polymers may be used alone or in combination of two or more.
These polymers are composed of ester, amide, ionic, van der Waals, agostic, hydrogen, acetal, ketal, ether, peroxide, carbon, and organic crosslinker compounds other than the above inorganic compounds. -Cross-linked via carbon bond, carbon-nitrogen bond, carbon-oxygen bond, carbon-sulfur bond, carbamate bond, thiocarbamate bond, carbamide bond, thiocarbamide bond, oxazoline moiety-containing bond, triazine bond, etc. Good.

The polymer preferably has a weight average molecular weight of 200 to 7000000. Thereby, the ion conductivity, flexibility, etc. of an anion conductive material can be adjusted. The weight average molecular weight is more preferably 400 to 6500000, and still more preferably 500 to 5000000.
The weight average molecular weight can be measured by gel permeation chromatography (GPC).

The ratio of the polymer is preferably 1% by mass or more in 100% by mass of the conductive layer. More preferably, it is 5 mass% or more, More preferably, it is 10 mass% or more, Most preferably, it is 40 mass% or more. Moreover, it is preferable that the ratio of this polymer is 99 mass% or less. More preferably, it is 90 mass% or less, More preferably, it is 70 mass% or less, Most preferably, it is 60 mass% or less.

In addition, it is preferable that the mixture ratio of a polymer and an inorganic compound in the said conductive layer is 5000000/1-1/100000. More preferably, it is 2000000/1-1 / 50,000, More preferably, it is 1000000/1-1/10000.

As long as the said conductive layer contains a conductive substance, a polymer, and an inorganic substance, it may further contain other components other than the said conductive substance, a polymer, and an inorganic substance. Moreover, 1 type may be sufficient as another component, and 2 or more types may be sufficient as it.

When the said conductive layer contains the said other component, it is preferable that the ratio of the said other component is 10 mass% or less in 100 mass% of conductive layers. More preferably, it is 5 mass% or less, More preferably, it is 1 mass% or less, Most preferably, it is 0.1 mass% or less.

[Insulation layer]
The insulating layer in the separator of the present invention has an electric resistance value of 10 Ω · cm or more. The electrical resistance value is preferably 1 × 10 ² Ω · cm or more, more preferably 1 × 10 ³ Ω · cm or more, still more preferably 1 × 10 ⁴ Ω · cm or more, It is particularly preferably 1 × 10 ⁵ Ω · cm or more, and most preferably 1 × 10 ⁶ Ω · cm or more. The upper limit value of the electric resistance value is not particularly limited, but is preferably 1 × 10 ⁹ Ω · cm or less, for example.
The electrical resistance value can be measured by the same method as the electrical resistance value of the conductive layer.

The average thickness of the insulating layer is preferably 10 μm or more, for example. More preferably, it is 50 micrometers or more, More preferably, it is 100 micrometers or more. Moreover, it is preferable that this average thickness is 2000 micrometers or less. More preferably, it is 1000 micrometers or less, More preferably, it is 500 micrometers or less.
The average thickness of the insulating layer can be calculated by arbitrarily measuring five points with a micrometer. When there are a plurality of the insulating layers, the sum of the average thicknesses of the respective layers of the insulating layer can be set as the thickness of the insulating layer.

Examples of the insulating layer include a nonwoven fabric, a microporous membrane, and an anion conductive membrane formed using an anion conductive material containing a polymer and an inorganic substance.
The said nonwoven fabric should just be comprised from the polymer normally used as a nonwoven fabric, for example, what is comprised from a cellulose is preferable.
Examples of the microporous membrane include those made of a resin such as low density polyethylene. The micropores of the microporous membrane can be formed by mixing a water-soluble substance such as carboxymethyl cellulose and polyvinyl alcohol with a resin dispersion, forming a film, washing with water and eluting the water-soluble substance. . The microporous membrane is preferably hydrophilic, such as one that has been hydrophilically treated.
Among these, at least one layer (one) of the insulating layers is more preferably an anion conductive film formed using an anion conductive material containing a polymer and an inorganic substance. In particular, as will be described later, when the separator of the present invention is used for a battery including a zinc negative electrode, a cadmium negative electrode, or a lithium negative electrode, a separator in which at least one of the insulating layers is the anion conductive film is preferable. . Even in this case, the separator of the present invention may further have a nonwoven fabric and / or a microporous membrane.

As the anion conductive film in the insulating layer, the same one as described above as the anion conductive film in the conductive layer can be used except that a conductive substance is not added and conductivity is not imparted. That is, the anion conductive film in the insulating layer can be formed using the same inorganic compound and polymer as those described above as the anion conductive material in the conductive layer.
The proportion of the inorganic compound is preferably 1% by mass or more in 100% by mass of the insulating layer. More preferably, it is 5 mass% or more, More preferably, it is 10 mass% or more, Most preferably, it is 30 mass% or more. Moreover, it is preferable that the ratio of this inorganic compound is 99 mass% or less. More preferably, it is 90 mass% or less, More preferably, it is 60 mass% or less, Most preferably, it is 50 mass% or less.

It is preferable that the ratio of the said polymer is 1 mass% or more in 100 mass% of insulating layers. More preferably, it is 5 mass% or more, More preferably, it is 10 mass% or more, Most preferably, it is 50 mass% or more. Moreover, it is preferable that the ratio of this polymer is 99 mass% or less. More preferably, it is 90 mass% or less, More preferably, it is 80 mass% or less, Most preferably, it is 70 mass% or less.
Note that the preferable blending ratio of the polymer and the inorganic compound in the insulating layer is the same as that described above as the blending ratio of the polymer and the inorganic compound in the conductive layer.

As a method for preparing the separator of the present invention, it can be suitably prepared by a conventionally known method. For example, the following method can be mentioned.
The above-mentioned other components are mixed with the conductive material, polymer, inorganic compound, and the like as necessary. Separately, if necessary, the above-mentioned other components are mixed together with the polymer, the inorganic compound, and the like, and the resultant is superposed on the mixture of the conductive material, the polymer, the inorganic compound, and the like, and then rolling is performed. For mixing, a mixer, blender, kneader, bead mill, ready mill, ball mill, or the like can be used. In mixing, water, an organic solvent such as methanol, ethanol, propanol, isopropanol, butanol, hexanol, tetrahydrofuran, N-methylpyrrolidone, or a mixed solvent of water and an organic solvent may be added.

<Battery of the present invention>
This invention is also a battery comprised including the separator of this invention, an electrode, and electrolyte.
In the battery of the present invention, it is important that the separator is along the electrode. By making a battery having a configuration in which the separator having the characteristics (1) and (2) is arranged along the electrode, the current distribution in the negative electrode surface can be made more uniform, and the effect of the present invention is remarkable. Can demonstrate.
The preferable form of the separator used for constituting the battery of the present invention is the same as the preferable form of the separator of the present invention described above. In the battery of the present invention, the separator of the present invention can be used singly or in combination of two or more as a separator, and as long as the separator of the present invention is used as a separator, non-woven fabric and / or fine particles other than the separator of the present invention are used. A porous film may be used. That is, any number of films can be used as long as resistance does not increase or battery performance does not decrease. For example, when the separator of the present invention is composed of a conductive layer and an insulating layer laminated only on one side of the conductive layer, the other side of the conductive layer is made of a high-resistance member (non-woven fabric, microporous membrane, etc.). The conductive layer and the electrode can be isolated by arranging a conductive member or the like.

When the battery according to the present invention is a battery including a zinc negative electrode, a cadmium negative electrode, or a lithium negative electrode, a separator in which at least one insulating layer is the anion conductive film is used. It is preferable that an anion conductive membrane is disposed on the negative electrode side. Thereby, dendrite can be suppressed sufficiently. In addition, when the battery of the present invention is a battery that does not include any of a zinc negative electrode, a cadmium negative electrode, and a lithium negative electrode and includes an electrode other than these negative electrodes, the negative electrode side of the conductive layer of the separator is an anion conductive film. Any of high resistance members such as nonwoven fabrics and microporous membranes may be disposed. In addition, any of high resistance members, such as an anion conductive film, a nonwoven fabric, and a microporous film, should just be arrange | positioned at the positive electrode side of the conductive layer of a separator.

That the conductive layer is disposed along the electrode means that the conductive layer is disposed along one surface of the electrode. Usually, the conductive layer is disposed along each of the surfaces where the positive electrode and the negative electrode face each other. The phrase “the conductive layer is disposed along the electrode surfaces such as the positive electrode and the negative electrode” means that the angle formed by the conductive layer and the electrode surface is 10 ° or less. Especially, it is preferable that the said conductive layer is arrange | positioned in parallel with respect to the said surface.
That is, the separator of the present invention is disposed between the positive electrode and the negative electrode so as to intersect with the current flowing from the positive electrode to the negative electrode. That the separator intersects with the current flowing from the positive electrode to the negative electrode means that the angle formed by the separator and the current is 80 ° or more. Especially, it is preferable to arrange | position so that it may orthogonally cross with respect to the electric current which flows from a positive electrode to a negative electrode. The conductive layer is preferably disposed so as to at least partially cover a path through which current flows linearly from the surface of the positive electrode facing the negative electrode to the surface of the negative electrode facing the positive electrode. More preferably, they are arranged. Thereby, an electric current can be sent from the positive electrode toward the negative electrode without unevenness, and the effect of suppressing the shape change or the like can be exhibited more remarkably.

Examples of the battery of the present invention include various batteries configured to include the separator of the present invention. For example, alkaline (storage) batteries, nickel-hydrogen (storage) batteries, nickel zinc (storage) batteries, nickel cadmium (storage). ) Batteries, nickel lithium (storage) batteries, zinc ion (storage) batteries, silver zinc (storage) batteries, air (storage) batteries, fuel cells, and the like. As described above, the battery of the present invention preferably contains a zinc negative electrode, a cadmium negative electrode, or a lithium negative electrode from the viewpoint that it can significantly exhibit the effect of suppressing the dendrite and shape change and extending the life of the battery. More preferably, a negative electrode or a cadmium negative electrode is included, and a zinc negative electrode is further preferably included. Moreover, this invention is also a secondary battery and a fuel cell comprised including the separator of this invention. That is, it is one of the preferable embodiments of the present invention that the battery of the present invention is a secondary battery. Moreover, it is also one of the preferable forms of this invention that the battery of this invention is a fuel cell.

Examples of the electrode in the battery of the present invention include a positive electrode and a negative electrode.
The end of the positive electrode and / or negative electrode (preferably, the negative electrode) (refers to a side surface located around the surface where the positive electrode and the negative electrode face each other) is a polymer (for example, It is preferable to coat with an insulating film made of polyethylene or the like so that current flows only in the direction orthogonal to the separator. Thereby, the effect of this invention can be exhibited more notably.
The insulating film covers the ends of the positive electrode and / or the negative electrode, so that at least a part of the surface of the positive electrode and / or the negative electrode facing the other electrode becomes an opening of the insulating film. The open area is preferably 10% or more and more preferably 40% or more with respect to the entire surface area of the electrode.

As the positive electrode active material, those normally used as the positive electrode active material for primary batteries and secondary batteries can be used, and are not particularly limited. For example, oxygen; nickel oxyhydroxide, nickel hydroxide, cobalt-containing water Nickel-containing compounds such as nickel oxide; manganese-containing compounds such as manganese dioxide; silver oxide; lithium-containing compounds such as lithium cobaltate; iron-containing compounds. Among these, it is one of the preferred embodiments of the present invention that the positive electrode active material is a nickel-containing compound.
When the battery of the present invention is a fuel cell, one of the preferred embodiments of the present invention is that the positive electrode active material is oxygen. That is, it is also one of the preferred embodiments of the present invention that the positive electrode of the fuel cell of the present invention is an electrode having oxygen reducing ability.

As the active material of the negative electrode in the battery of the present invention, materials normally used as the negative electrode active material of the battery, such as carbon, lithium, sodium, magnesium, zinc, cadmium, tin, and silicon-containing material can be used. Lithium, zinc and cadmium are preferred, zinc and cadmium are more preferred, and zinc is still more preferred.
When the battery of the present invention is a fuel cell, the negative electrode active material may be any of those normally used as the negative electrode active material of the fuel cell, and is not particularly limited. For example, hydrogen, methanol, ethanol , Propanol, butanol, ethylene glycol, propylene glycol, ammonia and the like.

The positive electrode and / or the negative electrode may further contain a binder.
The binder is, for example, a hydrocarbon site-containing polymer; an aromatic group-containing polymer; an ether group-containing polymer; a hydroxyl group-containing polymer; an amide group-containing polymer; an imide group-containing polymer; a carboxyl group-containing polymer; Polymers: Polymers bonded by ring opening of epoxy groups such as epoxy resins; Polymers containing sulfonate sites; Polymers containing quaternary ammonium salts or quaternary phosphonium salts; Used for cation / anion exchange membranes, etc. Natural rubber; Artificial rubber; Sugar; Amine group-containing polymer; Carbamate group site-containing polymer; Carbamide group site-containing polymer; Epoxy group site-containing polymer; Heterocycle and / or ionized heterocycle site Containing polymer; Polymer alloy; Heteroatom Yes polymers; low molecular weight surfactants, and the like.

The mass ratio of the active material other than oxygen in the electrode and the binder in the battery of the present invention is preferably 100: 1 to 1: 100, more preferably 90: 1 to 1: 1. 80: 1 to 10: 1 are more preferable, and 50: 1 to 20: 1 are particularly preferable.

The positive electrode and / or the negative electrode may further contain a conductive additive. Examples of the conductive auxiliary include conductive carbon, conductive ceramic, zinc used in zinc powder, zinc powder, zinc alloy, (alkaline) dry batteries and air batteries (hereinafter also referred to as metal zinc). Can be used. Conductive carbon includes graphite, glassy carbon, amorphous carbon, graphitizable carbon, non-graphitizable carbon, carbon nanofoam, activated carbon, graphene, nanographene, graphene nanoribbon, fullerene, carbon black, carbon fiber, fibrous carbon, carbon Nanotubes, carbon nanohorns, Vulcan, ketjen black, acetylene black and the like can be mentioned.

The positive electrode and / or the negative electrode in the battery of the present invention are usually obtained by forming an active material layer on a current collector using a battery electrode composition prepared by mixing the above components constituting the electrode. It is. For mixing each component, a mixer, blender, kneader, bead mill, ready mill, ball mill, or the like can be used.
In addition, after mixing, operations such as sieving may be performed in order to align the particles with a desired particle diameter.

Examples of the current collector include materials used as current collectors and containers for batteries, and examples include copper foil, electrolytic copper foil, copper mesh (expanded metal), copper foam, punched copper, brass, and the like. Alloy, brass foil, brass mesh (expanded metal), foamed brass, punched brass, nickel foil, nickel mesh, corrosion resistant nickel, nickel mesh (expanded metal), punched nickel, metal zinc, corrosion resistant metal zinc, zinc foil, zinc mesh ( Expanded metal), steel plates, punched steel plates, silver and the like. These are further added with Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, etc. or plated with Ni, Zn, Sn, Pb, Hg, Bi, In, Tl, etc. Also good.

The electrolyte in the battery of the present invention is not particularly limited as long as it is normally used as the battery electrolyte, and examples thereof include water-containing electrolytes and organic solvent-based electrolytes, and water-containing electrolytes are preferred. The water-containing electrolytic solution refers to an electrolytic solution using only water as an electrolytic solution raw material (aqueous electrolytic solution) or an electrolytic solution using a solution obtained by adding an organic solvent to water as an electrolytic solution raw material.

Examples of the aqueous electrolyte include alkaline electrolytes such as an aqueous potassium hydroxide solution, an aqueous sodium hydroxide solution, and an aqueous lithium hydroxide solution, an aqueous zinc sulfate solution, an aqueous zinc nitrate solution, an aqueous zinc phosphate solution, and an aqueous zinc acetate solution. . The aqueous electrolyte solution can be used alone or in combination of two or more.
Moreover, the said water containing electrolyte solution may contain the organic solvent used for an organic solvent type electrolyte solution. Examples of the organic solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, dimethoxymethane, diethoxymethane, dimethoxyethane, tetrahydrofuran, methyltetrahydrofuran, diethoxyethane, dimethyl sulfoxide, sulfolane, acetonitrile, Examples include benzonitrile, ionic liquid, fluorine-containing carbonates, fluorine-containing ethers, polyethylene glycols, fluorine-containing polyethylene glycols and the like. The organic solvent electrolyte can be used alone or in combination of two or more. The electrolyte of the organic solvent-based electrolytic solution is not particularly limited, but LiPF ₆ , LiBF ₄ , LiB (CN) ₄ , lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethylsulfonyl) imide ( LiTFSI) and the like are preferable.
A solid (gel) electrolyte or the anion conductive membrane of the present invention having the above electrolyte solution can also be used as a solid (gel) electrolyte.

In addition, as the form of the battery, a primary battery, a chargeable / dischargeable secondary battery, use of mechanical charge (for example, mechanical replacement of a zinc negative electrode), a third electrode (for example, charge / discharge) different from the negative electrode and the positive electrode However, as described above, it is preferable that the battery of the present invention is a secondary battery, as described above. One.

The separator of this invention consists of the above-mentioned structure, and when it uses for a battery, it can suppress the shape change of the active material accompanying a long-term use of a battery, and can extend a battery life.

It is a 2D static electric field simulation result of Example 2. It is the 2D static electric field simulation result similar to Example 2 except not having inserted the conductive layer.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

(Comparative Example 1)
Hydrotalcite and polytetrafluoroethylene (PTFE) were kneaded at a mass ratio of 4: 6 to prepare a single-layer anion conductive membrane having an average thickness of 300 μm. This single-layer anion-conducting membrane is disposed on the surface of a zinc negative electrode prepared by pasting an electrode mixture composition obtained by kneading zinc oxide as an active material and PTFE as a binder at a mass ratio of 96: 4 to punching nickel. The part was covered with a polyethylene film to constitute a negative electrode in which current flowed only in the direction penetrating the anion conductive membrane. The area where the polyethylene film is opened is 2 cm ² . Using a nickel positive electrode as a counter electrode and a mercury electrode as a reference electrode, a charge / discharge test was performed with a number of samples N = 4 on the negative electrode at a charge / discharge current of 10 mA / cm ² and a charge depth of 50%. As a result, all four samples died between 200 and 500 cycles.

(Example 1)
An anion conductive membrane having the same composition as Comparative Example 1 was superposed on both surfaces of an anion conductive membrane having electrical conductivity mixed with natural graphite: hydrotalcite: PTFE = 10: 40: 50 (mass ratio). Then, it was rolled to produce a layered structure. About it, the charging / discharging test was tried similarly to the comparative example 1. FIG. As a result, the life was extended to about 400 to 600 cycles.

(Example 2)
In order to investigate the current concentration suppression effect by the conductive layer, a 2D (two-dimensional) static electric field simulation was performed. The size of one segment is 10 μm, the electrolyte resistance is 10 Ω · cm, the current collector resistance is 0.001 Ω · cm, and the conductor layer (conductive layer) resistance is 0.1 Ω · cm. A point map and a negative electrode were used as line electrodes, and a resistance layer was prepared by inserting a conductive layer between the positive electrode and the negative electrode as shown in FIG. For the resistance map, potential distribution calculation using Kirchhoff's law was performed to create a potential map formed between the positive electrode and the negative electrode, and then an electric field strength map was created from the potential gradient. The results are shown in FIG.

(Comparative Example 2)
An electric field strength map was created under the same conditions as in Example 2 except that no conductive layer was inserted. The results are shown in FIG.

In FIG. 1 and FIG. 2, the location indicated as “the region where the electric field strength is very strong” has the strongest electric field strength, and the location indicated as “the region where the electric field strength is very weak” from that location. It is shown using an isoline that the electric field strength becomes weaker as it goes. As seen from this, in Comparative Example 2 (FIG. 2) without the conductive layer, the electric field generated from the positive electrode spreads toward the negative electrode, and the electric field intensity on the negative electrode surface has a strong and weak mottle, and the current distribution on the negative electrode surface is It is uneven. On the other hand, in Example 2 (FIG. 1), since there is a conductive layer insulated from both the positive electrode and the negative electrode, it diffuses once at the position where the conductive layer is present, and a parallel electric field (electric field (electric field) is generated in the region between the conductive layer and the negative electrode. Is uniform) and the current distribution on the negative electrode surface is uniform. As shown in the simulation results of FIG. 1, the separator of the present invention having a multilayer structure including an insulating layer and a conductive layer is used in order to dispose a conductive layer insulated from both the positive electrode and the negative electrode in the battery. Can do.

From Example 1 and Comparative Example 1, it was found that the battery life can be extended by using a separator in which an insulating layer and a conductive layer are overlapped. Further, from Example 2 and Comparative Example 2, it was found that the current distribution in the negative electrode surface can be made more uniform by inserting a conductive layer insulated from both the positive electrode and the negative electrode as shown in FIG. . Thereby, generation | occurrence | production of a dendrite and the shape change of an active material can be suppressed, and it is thought that a lifetime of a battery can be extended.

Summarizing the above, the following was found from the results of the above Examples and Comparative Examples. In the battery configured using the separator of the present invention, the current distribution on the negative electrode surface of the battery can be made more uniform, and the generation of dendrites and the active material shape change can be suppressed. Thereby, the battery life can be extended.

In the first embodiment, specific materials are used for the insulating layer and the conductive layer. However, the current distribution on the negative electrode surface of the battery can be made more uniform, and dendrites are generated and the active material is shaped. The change can be suppressed when the separator has a multilayer structure including an insulating layer and a conductive layer, and the conductive layer is disposed in the battery while being electrically insulated from the electrode through the insulating layer. It can be evaluated that all are the same.

In addition, Example 1 described above relates to a nickel / zinc battery using a zinc negative electrode, and this is one preferred embodiment of the present invention, but the separator of the present invention is also applied to various other electrodes / batteries. If used, the current distribution on the negative electrode surface of the battery can be made more uniform, and the shape change of the active material can be suppressed, so that the operational effects of the present invention can be exhibited. Therefore, from the results of the above examples, it is proved that the present invention can be applied in various technical forms of the present invention and in various forms disclosed in the present specification, and advantageous effects can be exhibited.

Claims (5)

An ion conductive separator used in a secondary battery,
The separator is in electrical resistance 10 [Omega · cm or more, Chi also a multilayer structure comprising an electrical resistance value and the insulation layer average thickness is 50μm or more is less than 10 [Omega · cm conductive layer,
The separator, wherein the conductive layer is sandwiched between the insulating layers and is in an electrically floating state when a secondary battery is configured using the separator. The separator according to claim 1 , wherein at least one of the insulating layers is an anion conductive film formed using an anion conductive material including a polymer and an inorganic substance. The conductive layer separator according to claim 1 or 2, characterized in that it comprises a conductive carbon material. A separator according to any one of claims 1 to 3 electrodes, and a secondary battery characterized in that it is configured to include an electrolyte. The secondary battery according to claim 4 , wherein the battery includes a zinc negative electrode.