JP2011204520A - Hydrogen storage alloy electrode and nickel-hydrogen battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen storage alloy electrode providing a nickel-hydrogen battery which has a hydrogen storage alloy layer with an excellent water repellency, which can suppress an increase of an internal pressure of the battery, and which is excellent in cycle characteristics and load characteristics.SOLUTION: The hydrogen storage alloy electrode has the hydrogen storage alloy layer (I) on a conductive support (II), wherein the storage alloy layer (I) contains a fluorine compound (a) represented by formula (1): Rf-X (in the formula, Rf is a fluoroalkyl group which may contain a 1-12C ether linkage; X is carboxylic acid, sulfonic acid, phosphate, silicate, and their derivatives), a binder (b), and a hydrogen storage alloy particle (c).

Description

  The present invention relates to a hydrogen storage alloy electrode of a nickel metal hydride battery and a nickel metal hydride battery.

  In a nickel metal hydride battery, a layer containing hydrogen storage alloy particles that store hydrogen obtained by electrolyzing an alkaline aqueous solution at the time of charging is formed on the negative electrode current collector, and the stored hydrogen is released during discharge and is oxidized to water. The following reaction occurs.

  As a problem of such a nickel metal hydride battery, it is important to suppress an increase in the internal pressure of the battery that is increased by hydrogen gas generated at the negative electrode and oxygen gas generated at the positive electrode, and also inhibits hydrogen gas release by water generated during discharge. Therefore, it is also important to prevent the battery capacity, cycle characteristics, load characteristics, and the like from being reduced.

  Therefore, by making the surface of the hydrogen storage alloy particles water repellent, the surface of the hydrogen storage alloy particles is brought into a three-phase interface state of solid (alloy layer) -liquid (water or aqueous alkali solution) -gas (hydrogen gas), It has been proposed to improve the problem.

  In Patent Documents 1 and 2, a dispersion of solid fluororesin particles hardly soluble in an organic solvent such as polytetrafluoroethylene (PTFE) or tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer (FEP) is used. There has been proposed a method of applying to a hydrogen storage alloy layer and interspersing the surface of the hydrogen storage alloy particles with water-repellent fluororesin particles.

  In Patent Document 3, a solution in which a perfluoropolyether having hydrolyzable silyl groups (hydrosilyl groups) at both ends is dissolved in a fluorine-based solvent as a water repellent is applied to the hydrogen storage alloy layer, and the water repellent layer stores hydrogen. A method for coating the surface of alloy particles has been proposed.

  In Patent Documents 4 to 5, fluorine of a fluororesin polymer (perfluorobutenyl vinyl ether polymer, perfluoroallyl vinyl ether polymer or tetrafluoroethylene / perfluoro-2,2-dimethyl-1,3-dioxole copolymer). There has been proposed a method in which a solution of a system solvent is applied (or sprayed) to a hydrogen storage alloy layer, and a water repellent layer is formed (spotted) on the surface of the hydrogen storage alloy particles.

  Patent Document 6 proposes forming a three-phase interface state on the surface of the hydrogen storage alloy particles by fluorinating part or all of the carbon present on the surface of the carbon-containing hydrogen storage alloy particles.

  In Patent Document 7, as a paste for forming a hydrogen storage alloy layer, a perfluoropolyether having two or more specific unsaturated group-containing fluorine-containing amide compounds and two or more hydrosilyl groups is cured with respect to the hydrogen storage alloy particles. The hydrogen storage alloy layer forming material which mix | blended 5 weight% or less of the curable composition containing the platinum catalyst for this is described.

Japanese Patent Laid-Open No. 02-250260 Japanese Patent Laid-Open No. 02-291665 JP 09-097605 A Japanese Patent Laid-Open No. 10-012228 Japanese Patent Laid-Open No. 10-060361 JP 08-315814 A Japanese Patent Laid-Open No. 08-162101

  However, in the method of dispersing water-repellent fluororesin particles on the surface of the hydrogen storage alloy particles (Patent Documents 1 and 2), a process for forming a hardly soluble fluororesin particle layer on the surface of the hydrogen storage alloy particles is required. Moreover, there is a problem that it is difficult to uniformly apply the fluororesin particles.

  In Patent Documents 3 to 5 using a fluorinated ether polymer as a water repellent, it is necessary to use a fluorinated solvent as the organic solvent. However, the fluorinated solvent has a high global warming potential (GWP), and should not be used if possible. desirable.

  Further, in Patent Document 6 in which part or all of carbon existing on the surface of carbon-containing hydrogen storage alloy particles is fluorinated, an alloy other than carbon may be fluorinated together with carbon. Therefore, problems such as capacity reduction remain.

  Patent Document 7 is an invention in which a specific perfluoropolyether is blended as a water repellent agent in a paste for forming a hydrogen storage alloy layer, rather than a form of forming a water repellent layer after forming a hydrogen storage alloy layer. In addition to the need for a platinum catalyst as a catalyst, the presence of the hydrophilic amide group of the amide compound tends to reduce the water-repellent effect.

  The present invention has been completed as a result of studying an environment-friendly material that can be easily applied to form a hydrogen storage alloy layer having excellent water repellency.

  That is, the present invention is represented by the formula (1): Rf-X (wherein Rf is a fluoroalkyl group optionally containing an ether bond having 1 to 12 carbon atoms; X is a carboxylic acid, sulfonic acid, phosphoric acid, silicic acid; And a hydrogen storage alloy layer (I) containing a fluorine compound (a), a binder (b), and hydrogen storage alloy particles (c) represented by the following formula: The present invention relates to an alloy electrode.

  X in the formula (1) is preferably a carboxylic acid ester, a phosphoric acid ester or a silicate.

  Rf in formula (1) is preferably a fluoroalkyl group having 1 to 8 carbon atoms.

  The hydrogen storage alloy layer (I) is formed by using a hydrogen storage alloy layer forming paste containing the fluorine compound (a) of the formula (1), the binder (b), and the hydrogen storage alloy particles (c). The fluorine compound (a) of the formula (1) dispersed or dissolved in an organic solvent or water may be applied to the hydrogen storage alloy layer containing the binder (b) and the hydrogen storage alloy particles (c). It may be formed by doing.

  The present invention also relates to a nickel-metal hydride secondary battery having the hydrogen storage alloy electrode of the present invention as a negative electrode and including a positive electrode and an alkaline electrolyte.

  According to the hydrogen storage alloy electrode of the present invention, a nickel hydrogen secondary battery having a hydrogen storage alloy layer excellent in water repellency, capable of suppressing an increase in battery internal pressure, and excellent in cycle characteristics and load characteristics is provided. be able to.

  The hydrogen storage alloy electrode of the present invention comprises a hydrogen storage alloy layer (I) containing a fluorine compound (a) of the formula (1), a binder (b) and hydrogen storage alloy particles (c) as a conductive support ( II) have on.

  Hereinafter, each element will be described.

(I) Hydrogen storage alloy layer In this invention, hydrogen storage alloy layer (I) contains the fluorine compound (a) of Formula (1), binder (b), and hydrogen storage alloy particle (c).

(A) Formula (1): Rf-X (wherein Rf is a fluoroalkyl group optionally containing an ether bond having 1 to 12 carbon atoms; X is a carboxylic acid, sulfonic acid, phosphoric acid, silicic acid and its Derivatives)

  It is important that the fluorine compound (a) of the formula (1) used in the present invention has a binding property to Ni metal or water repellency.

for that purpose,
(I) In order to express water repellency, Rf is a fluoroalkyl group which may contain an ether bond,
(Ii) It is important to have a functional group capable of binding to Ni metal.

  From the viewpoint of (i), Rf may have a long carbon number, but if the carbon number is long, it becomes difficult to bond to Ni metal, and as a result, water repellency is lowered, which is not preferable. Moreover, when carbon number is large, it becomes unpreferable from becoming an environmental control substance represented by the perfluoro oxyalkylene compound (PFOA). Therefore, the carbon number is 1 to 12, more preferably 1 to 8.

  From the viewpoint of (ii), X may be a functional group having a binding force with Ni metal, such as acids such as carboxylic acid, sulfonic acid and phosphoric acid, or derivatives of such acids such as esters and salts thereof, amines And a functional group having a hydrogen bonding force such as a hydroxyl group, and a silicate compound such as silicate having a chemical bonding force to a hydroxyl group on the surface of Ni metal. However, it is insoluble in an alkaline aqueous solution that is an electrolytic solution of a nickel metal hydride battery, and since it is important to have a stronger chemical bonding force to Ni metal, carboxylic acid, sulfonic acid, phosphoric acid, Silicic acid and its derivatives are preferred.

  As described above, the fluorine compound of the formula (1) used in the present invention has good affinity with Ni metal which is a component of the hydrogen storage alloy, and can impart water repellency to the hydrogen storage alloy particles for a long time.

As the fluorine compound containing phosphoric acid or a derivative thereof used in the present invention, formula (2): RfP (═O) (OR ¹ ) (OR ² ) (wherein Rf has 1 to 12 carbon atoms, preferably 1 to 1 carbon atoms). 8 perfluoroalkyl group, perfluoroalkylene group or perfluoroalkyl ether group; R ¹ and R ² may be the same or different, and may be a hydrogen atom or a halogenated C 1-6 carbon atom; Alkyl group, aromatic group which may be halogenated, NH ₄ , NRH ₃ , NR ₂ H ₂ , NR ₃ H (R is an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group), pyridinium group or piperidinium group ) Is preferred.

Specifically, for example, C ₄ F ₉ C ₂ H ₄ P (═O) (OH) ₂ , C ₅ F ₁₁ C ₂ H ₄ P (═O) (OH) ₂ , C ₆ F ₁₃ C ₂ H ₄ P (= O) (OH) 2, C 8 F 17 C 2 H 4 P (= O) (OH) 2, C 3 F 7 C 2 H 4 P (= O) (OC 3 H 7) 2, ( CF ₃ ) ₂ CFC ₆ F ₁₂ C ₂ H ₄ P (═O) (OH) ₂ , C ₄ F ₉ C ₂ H ₄ P (═O) (OCH ₃ ) ₂ , C ₅ F ₁₁ C ₂ H ₄ P (= O) (O-iso -C 3 H 7) 2, C 8 F 17 C 2 H 4 P (= O) (OPh) 2, C 4 F 9 C 2 H 4 P (= O) (OC 2 _{H 4 -C 4 F 9) 2} , C 4 F 9 C 2 H 4 P (= O) (OC 2 H 4 -C 4 F 9) (OH), C 4 F 9 C 2 H 4 P (= O ) (ONH ₄ ) ₂ , C ₅ F ₁₁ C ₂ H ₄ P (═O) (ON (C ₂ H ₅ ) ₃ H) ₂ (where Ph is a phenyl group).

The fluorine compound containing a carboxylic acid or derivative thereof used in the present invention is represented by the formula (3): RfCOOR ³ (wherein Rf is a perfluoroalkyl group or perfluoroalkylene group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms). Or a perfluoroalkyl ether group; R ³ is a hydrogen atom, an optionally halogenated alkyl group having 1 to 6 carbon atoms, an optionally halogenated aromatic group, NH ₄ , NRH ₃ , NR ₂ H ₂ , NR ₃ H (R is an alkyl group or hydroxyalkyl group having 1 to 4 carbon atoms), a pyridimium group or a piperidinium group) is preferable.

Specifically, for example, C ₄ F ₉ COOH, C ₅ F ₁₁ COOH, C ₆ F ₁₃ COOH, C ₇ F ₁₅ COOH, C ₈ F ₁₇ COOH, C ₈ F ₁₇ COOCH ₃ , C ₈ F ₁₇ COOC ₂ H ₅ , C ₈ F ₁₇ COOC ₃ H ₇ , C ₈ F ₁₇ COOC ₄ H ₉ , C ₈ F ₁₇ COOC ₅ H ₁₁ , C ₈ F ₁₇ COOPh, etc. (where Ph is a phenyl group).

The fluorine compound containing silicic acid or a derivative thereof used in the present invention is represented by the formula (4): Rf _n SiR ⁴ _4-n (wherein Rf is a perfluoroalkyl group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms). R ⁴ is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, or a propoxy group, or an oxyalkoxy group such as a methoxymethoxy group or a methoxyethoxy group; And when R ⁴ is 2 or more, they may be the same or different; n is an integer of 1 to 3).

Specifically, for example, CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ , CF ₃ CF ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , CF ₂ (CF ₂ ) ₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ , C ₅ F ₁₁ Si (OCH ₃ ) ₃ , C ₅ F ₁₁ Si (OC ₂ H ₅ ) ₃ , C ₆ F ₁₃ Si (OCH ₃ ) ₃ , C ₆ F ₁₃ Si (OC ₂ H ₅ ) ₃ , C ₇ F ₁₅ Si (OCH ₃ ) ₃ , C ₈ H ₁₇ Si (OCH ₃ ) ₃ , C ₈ Examples thereof include F ₁₇ Si (OC ₂ H ₅ ) ₃ and C ₈ F ₁₇ Si (OC ₃ H ₇ ) ₃ .

The fluorine compound containing a sulfonic acid or a derivative thereof used in the present invention is represented by the formula (5): RfSO ₃ M (wherein Rf is a perfluoroalkyl group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, perfluoroalkylene). Group or perfluoroalkyl ether group; M is preferably a hydrogen atom, a metal atom or an ammonium salt).

  Specifically, for example, potassium perfluorobutanesulfonate, potassium perfluorohexanesulfonate, potassium perfluorooctanesulfonate, sodium perfluorobutanesulfonate, sodium perfluorooctanesulfonate, lithium perfluorobutanesulfonate, perfluorobutanesulfonate, Examples thereof include lithium fluoroheptanesulfonate, cesium perfluorooctanesulfonate, cesium perfluorohexanesulfonate, cesium perfluorobutanesulfonate, and tetramethylammonium perfluorobutanesulfonate.

  Among them, carboxylic acid or a salt or ester thereof, sulfonic acid or a salt or ester thereof, phosphoric acid or a salt or ester thereof, silicic acid or a salt or ester thereof is more preferable, and has a stronger binding force with Ni metal. From the viewpoint, carboxylic acid ester, phosphoric acid ester, and silicate are more preferable.

(B) Binder As the binder (b) used in the present invention, a known material conventionally used for forming a hydrogen storage alloy layer of a nickel metal hydride secondary battery, for example, JP-A-2002-15731 The binder described in the above can be employed.

  Specifically, for example, cellulose-based binders such as methylcellulose and carboxymethylcellulose; hydrophilic synthetic resin-based binders such as polyvinyl alcohol and polyethylene oxide; polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and the like Examples include fluororesin binders; hydrocarbon binders such as polypropylene, polyethylene, and polystyrene; rubber binders such as styrene-butadiene rubber (SBR).

  Among these, when a non-fluorinated binder is used, the water repellent effect of the fluorine compound (a) of the formula (1) is remarkably exhibited. In the case of using a fluororesin-based binder, the fluororesin itself has water repellency, but by adding the fluorine compound (a) of the formula (1), water repellency is further exhibited on the electrode surface. It becomes easy to let you.

(C) Hydrogen storage alloy particles As the hydrogen storage alloy used in the present invention, known materials conventionally used for forming a hydrogen storage alloy layer of a nickel hydrogen secondary battery, for example, Japanese Patent Application Laid-Open No. 02-291665, Alloys described in Japanese Unexamined Patent Publication No. 2008-210554 can be employed.

Specifically, for example, AB ₅ type and the called and is misch metal (Mm) is called the alloy and AB ₂ type whose main raw material Ti-Zr-Mn-V, Ti-Zr-Cr-FeTi- Examples thereof include Ti—Cr—V called Cr—V or BCC type. Among these, a misch metal-based hydrogen storage alloy is preferable from the viewpoint of good battery characteristics such as cycle characteristics.

The Misch metal-based hydrogen storage alloy (AB ₅ type) is a mixture in which a part of La of a LaNi ₅ -based alloy having a CaCu ₅ structure is replaced with a rare earth metal element such as Ce, Pr, Nd. As a representative example, Ce / La / Nd / other rare earth metal elements (= 45/30/5/20% by weight). Further, Mm, Ni, Co, Al, and Mn alloyed at a molar ratio of Mm / Ni / Co / Al / Mn of 1.0 / 3.3 / 0.9 / 0.2 / 0.6 Those alloyed with 1.0 / 4.1 / 0.3 / 0.35 / 0.3 and those alloyed with 1.0 / 3.4 / 0.8 / 0.2 / 0.6 Are known.

  The hydrogen storage alloy is used in the form of particles (powder). The particle size is usually about 40 to 300 μm.

  In the hydrogen storage alloy layer (I) used in the present invention, the contents of the fluorine compound (a) of formula (1), the binder (b), and the hydrogen storage alloy particles (c) are determined according to the hydrogen storage alloy layer (I). In the middle (hereinafter the same), 0.1 to 5.0% by mass of the fluorine compound (a) of the formula (1), 0.5 to 5.0% by mass of the binder (b), and hydrogen storage alloy particles (c) It is preferable that it is 90-97 mass%. From the viewpoint of improving battery characteristics, the total amount of the fluorine compound (a) of the formula (1) and the binder (b) is 5% by mass or less, and more preferably 0.6 to 4.0% by mass. preferable.

  The blending amount of the fluorine compound (a) of the formula (1) is preferably 5.0% by mass or less, more preferably 1.0% by mass or less from the viewpoint of good cycle characteristics and load characteristics. From the viewpoint of uniformly covering the surface, it is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more.

  The blending amount of the binder (b) varies depending on the type and molecular weight, but generally it is preferably 5.0% by mass or less, more preferably 3.0% by mass or less from the viewpoint of good battery characteristics. Moreover, it is preferable that it is 0.5 mass% or more from a point with favorable adhesiveness, Furthermore, it is preferable that it is 1.0 mass% or more.

(II) Conductive support As the conductive support (current collector) used in the present invention, a support of a known material conventionally used for a hydrogen storage alloy electrode (negative electrode) of a nickel hydrogen secondary battery, For example, the support body described in Unexamined-Japanese-Patent No. 2002-260646 etc. can be employ | adopted.

  Specific examples include three-dimensional conductive supports such as fibrous nickel and foamed nickel; two-dimensional conductive supports such as punching metal, expanded metal, and metal net.

  The hydrogen storage alloy electrode of the present invention can be produced by forming the hydrogen storage alloy layer (I) on the conductive support (II) by various methods.

For example, (1) a paste is prepared by mixing a predetermined amount of the fluorine compound (a) of the formula (1), the binder (b), and the hydrogen storage alloy particles (c) in the absence of a solvent, and the conductive support Applying or crimping to the body;
(2) A binder (b) and hydrogen storage alloy particles (c) are mixed using a solvent to prepare a paste, which is applied to a conductive support or pressed to form a hydrogen storage alloy layer, Next, a method of applying the fluorine compound (a) of the formula (1) to the hydrogen storage alloy layer;
(3) The binder (b) and the hydrogen storage alloy particles (c) are mixed using a solvent to prepare a paste, and a hydrogen storage alloy sheet is formed by a casting method or a compression molding method. A method of applying or impregnating the fluorine compound (a) of the formula (1) to the occlusion alloy sheet and then sticking it to the conductive support can be employed.

  Among these methods, the method (1) is preferable because the fluorine compound (a) of the formula (1) can be uniformly coated on the hydrogen storage alloy particles (c).

  The present invention also relates to a nickel-metal hydride secondary battery using the hydrogen storage alloy electrode of the present invention as a negative electrode and including a positive electrode and an alkaline electrolyte. The nickel metal hydride secondary battery of the present invention is the same as the conventional nickel metal hydride secondary battery, except that the hydrogen storage alloy electrode of the present invention is used as the negative electrode. In addition to the positive electrode and the alkaline electrolyte, the separator, the negative electrode can, etc. Conventionally known structures and materials can be used.

  Specifically, for example, a nickel electrode filled with nickel hydroxide is generally used. This nickel electrode can be produced by filling foam nickel with a paste mainly composed of nickel hydroxide powder having a cobalt oxyhydroxide layer formed on the surface thereof.

  Examples of the alkaline electrolyte include an aqueous potassium hydroxide solution, sodium hydroxide, lithium hydroxide, or a mixed solution thereof.

  The nickel metal hydride secondary battery of the present invention contains an alkyl phosphoric acid or an alkyl phosphate having excellent water repellency and good affinity for nickel in the hydrogen storage alloy layer. Since a -3 phase interface state is formed and hydrogen gas can be occluded / released smoothly, an increase in battery internal pressure can be suppressed, and as a result, battery characteristics such as cycle characteristics and load characteristics are improved.

  EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

  The measurement method employed in the present invention is as follows.

(1) NMR
Apparatus: AC-300 manufactured by BRUKER
Measurement condition:
¹ H-MNR: 300.133 MHz, CDCl ₃ , neat
¹⁹ F-MNR: 282.40 MHz, CF ₃ COOH, neat

(2) Contact angle with water Using an automatic contact angle measuring device DSA100S (manufactured by Kyowa Interface Science Co., Ltd.), 0.5 μL of pure water is dropped on the electrode, and the contact angle after 8 seconds is measured.

Synthesis example 1
A 200 ml stainless steel autoclave was charged with 160 g of C ₈ F ₁₇ I, 90 g of fuming sulfuric acid containing 60% sulfur trioxide and 0.66 g of phosphorus pentoxide, heated to 110 ° C. and reacted for about 6 hours. It was. The reaction pressure was 5.1 kg / cm ² .

After completion of the reaction, the mixture was cooled and returned to atmospheric pressure, and then the product was collected to obtain 47.3 g of a crude product. As a result of NMR analysis, it was found that C ₇ F ₁₅ COF was 92.9 mol%, C ₈ F ₁₇ SO ₃ F was 5.8 mol%, C ₈ F ₁₇ I was 0.9 mol%, C ₇ F ₁₅ COOH was a 0.3 mol% mixture. By rectifying this mixture, C ₇ F ₁₅ COF having a purity of 99% or more was obtained. Next, C ₇ F ₁₅ COOH was quantitatively obtained by adding water to C ₇ F ₁₅ COF obtained by rectification and hydrolyzing it.

¹ H-NMR (300.133 MHz, CDC 1 ₃ , neat: 11.0 ppm (s, 1H)

Synthesis example 2
Sulfuric acid (29.4 g, 0.3 mol) and methanol (3.2 g, 0.1 mol) were added to C ₇ F ₁₅ COOH (42.8 g, 0.1 mol) produced in Synthesis Example 1, and the reaction was conducted for 3 hours with stirring. I let you. Thereafter, distilled to give a C ₇ F ₁₅ COOCH ₃ quantitatively.

¹ H-NMR (300.133 MHz, CDC 1 ₃ , neat): 3.67 ppm (s, 3H)

Synthesis example 3
C ₄ F ₉ CH ₂ CH ₂ I (11.4 g, 0.031 mol) was charged into a 50 ml four-necked flask equipped with a reflux tube, a dropping funnel and a thermometer, and P (iPrO) was added at room temperature from the dropping funnel. ₃ (6.36 g, 0.031 mol) was added dropwise in about 30 minutes. The mixture was refluxed for 8 hours. Then, the unreacted raw material was distilled under reduced pressure (11 mmHg) at 64 ° C. NMR spectrum measurement of the obtained product confirmed that it was C ₄ F ₉ CH ₂ CH ₂ P (═O) (iPrO) ₂ (6.12 g, 0.031 mol). The various analysis results are as follows.

¹ H-NMR (300.133 MHz, CDCl ₃ , neat): 1.6 ppm (d, J = 7.14 Hz, 12H), 2.13 to 2.32 ppm (m, 2H), 2.56 to 2.82 ppm (M, 2H), 5.05 ppm (q, J = 7.14 Hz, 2H)
¹⁹ F-NMR (282.40 MHz, CF ₃ COOH, neat): -82 ppm (m, 3F), -116.2 ppm (m, 2F), -125.23 ppm (m, 2F), -127.1 ppm (m , 2F)

Synthesis example 4
C ₄ F ₉ CH ₂ CH ₂ P (═O) (iPrO) ₂ (6.12 g, 0.031 mol) synthesized in Synthesis Example 3 was charged into a round bottom flask equipped with a reflux tube, and gradually added in an oil bath. The temperature was raised. Since white smoke was generated when the system temperature reached about 220 ° C., the system was heated to 220 ° C. for about 2 hours until the generation of white smoke disappeared. After standing to cool, the gas generated using a vacuum pump was extracted from the upper part of the reflux tube to obtain 4.31 g of product. From the results of NMR spectral analysis of the product, it was confirmed that it was C ₄ F ₉ CH ₂ CH ₂ P (═O) (OH) ₂ . The various analysis results are as follows.

¹ H-NMR (300.133 MHz, CDCl ₃ , D ₂ O): 1.83 to 2.10 ppm (m, 2H), 2.28 to 2.65 ppm (m, 2H)
¹⁹ F-NMR (282.40 MHz, CF ₃ COOH, D ₂ O): −79.939 ppm (s, 3F), −144.013 ppm (s, 2F), −123.36 ppm (s, 2F), −124 .943 ppm (s, 2F)

Synthesis example 5
CH ₃ MgBr (1 mol / liter concentration diethyl ether solution, 2 L) was placed in a glass three-necked flask and kept constant at −20 ° C. A solution prepared by dissolving 346 g of CF ₃ (CF ₂ ) ₃ I in 1 liter of THF was dropped into the flask over 5 hours, stirred for 1 hour, and 3 mol of sulfurous acid gas was blown into the reaction system over 5 hours. After completion of blowing, the mixture was returned to room temperature and stirred for 3 hours. Then, hydrogen peroxide solution (35% aqueous solution 300 ml) was added dropwise over 2 hours, and after completion of the addition, the mixture was stirred at room temperature for 12 hours. The solvent was removed from the reaction system, the residue was added to 2 liters of ion-exchanged water, cooled to 0 ° C., and insolubles were collected by filtration. Thereafter, the obtained solid was dried at 100 ° C., 100 g of the obtained solid was dissolved in methanol (200 g) at 60 ° C., and ion-exchanged water (500 ml) was added to this liquid. Thereafter, this solution was desolvated with a rotary evaporator and concentrated until the total weight reached 300 g. The solution was cooled to 0 ° C. and left overnight. Here, the precipitated solid was separated by filtration and washed with 100 ml of ion-exchanged water. Thereafter, the obtained solid was dried at 100 ° C. to obtain CF ₃ (CF ₂ ) ₃ SO ₃ Na (42 g) with reduced iodine ions.

Example 1
(1) Preparation of hydrogen storage alloy powder Weigh each commercially available metal element Mm, Ni, Co, Al and Mn so as to be MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 (molar ratio. Mm is Misch metal). Mix in the given ratio. The mixture was poured into a high-frequency melting furnace and dissolved, and then poured into a mold and cooled to prepare a hydrogen storage alloy lump (ingot) made of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 . This lump of hydrogen storage alloy was coarsely pulverized and then mechanically pulverized in an inert gas atmosphere until the average particle size became about 50 μm to prepare a hydrogen storage alloy powder. In addition, the average particle diameter of the obtained hydrogen storage alloy powder is a value measured by a laser diffraction method.

(2) Production of hydrogen storage alloy electrode To 98 parts by mass of the produced hydrogen storage alloy powder, 1.5 parts by mass (solid content) of PTFE dispersion (D-210C manufactured by Daikin Industries, Ltd.) as a binder and 0.5 parts by mass of C ₇ F ₁₅ COOH synthesized in Synthesis Example 1 was added, and pure water was added and kneaded to prepare a hydrogen storage alloy layer forming slurry (active material slurry). This hydrogen storage alloy layer forming slurry was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until moisture disappeared to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 120.2 degrees.

Example 2
The mixture was kneaded in the same manner as in Example 1 except that C ₇ H ₁₅ COOCH ₃ synthesized in Synthesis Example 2 was used to prepare a hydrogen storage alloy layer forming paste, which was applied to nickel-plated punching metal, Drying was performed in a constant temperature bath at 90 ° C. until there was no moisture, and a hydrogen storage alloy electrode (negative electrode) was produced.

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 120.8 degrees.

Example 3
A paste for forming a hydrogen storage alloy layer was prepared by kneading the mixture in the same manner as in Example 1 except that C ₄ F ₉ CH ₂ CH ₂ P (═O) (iPrO) ₂ synthesized in Synthesis Example 3 was used. This was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until no water was present, thereby producing a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 121.3 degrees.

Example 4
A paste for forming a hydrogen storage alloy layer was prepared by kneading the mixture in the same manner as in Example 1 except that C ₄ F ₉ CH ₂ CH ₂ P (═O) (OH) ₂ produced in Synthesis Example 4 was used. This was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until no water was present, thereby producing a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 119.8 degrees.

Example 5
A paste for forming a hydrogen storage alloy layer was prepared by kneading the mixture in the same manner as in Example 1 except that CF ₃ (CF ₂ ) ₃ SO ₃ Na synthesized in Synthesis Example 5 was used. And dried in a constant temperature bath at 90 ° C. until the water disappeared to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 115.1 degrees.

Example 6
The mixture is kneaded in the same manner as in Example 1 except that C ₆ F ₁₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ (GE / Toshiba Silicone Co., Ltd. TSL-8257) is used. A paste was prepared, applied to a nickel-plated punching metal, and dried in a constant temperature bath at 90 ° C. until moisture was lost, thereby preparing a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 120.5 degrees.

Example 7
A dispersion of PTFE as a binder (D-210C manufactured by Daikin Industries, Ltd.) was added to 98.5 parts by mass of the hydrogen storage alloy powder composed of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 prepared in step (1) of Example 1. 1.5 parts by mass (solid content) was added, and pure water was further added and kneaded to prepare a hydrogen storage alloy layer forming slurry (active material slurry). This slurry for forming a hydrogen storage alloy layer was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until there was no water.

Next, C ₇ F ₁₅ COOH produced in Synthesis Example 1 was uniformly applied to the obtained hydrogen storage alloy electrode so as to have a thickness of about 15 μm, and then dried again in a constant temperature bath at 90 ° C. until the water disappeared. The hydrogen storage alloy electrode (negative electrode) was produced.

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 120.8 degrees.

Example 8
To 97.9 parts by mass of the hydrogen storage alloy powder composed of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 prepared in step (1) of Example 1, SBR aqueous emulsion (TRD2001 manufactured by JSR Co., Ltd. (solid content 48) was used as a binder. 0.0%)) 1.5 parts by mass (solid content), 0.5 part by mass of C ₇ F ₁₅ COOH produced in Synthesis Example 1 and 0.1 part by mass of carboxymethylcellulose (CMC) as a thickener Further, pure water was added and kneaded to prepare a slurry for forming a hydrogen storage alloy layer (active material slurry). This hydrogen storage alloy layer forming slurry was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until moisture disappeared to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 121.2 degrees.

Example 9
A dispersion of PTFE as a binder (D-210C manufactured by Daikin Industries, Ltd.) was added to 98.4 parts by mass of the hydrogen storage alloy powder made of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 produced in the step (1) of Example 1. ) 1.5 parts by mass (solid content), 0.1 part by mass of C ₇ F ₁₅ COOH produced in Synthesis Example 1, and then adding pure water and kneading to make a slurry for forming a hydrogen storage alloy layer (active material) Slurry) was prepared. This hydrogen storage alloy layer forming slurry was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until moisture disappeared to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 116.8 degrees.

Example 10
A dispersion of PTFE (D-210C manufactured by Daikin Industries, Ltd.) as a binder was added to 93.5 parts by mass of the hydrogen storage alloy powder made of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 produced in the step (1) of Example 1. ) 1.5 parts by mass (solid content), 5.0 parts by mass of C ₇ F ₁₅ COOH produced in Synthesis Example 1, and further kneaded by adding pure water (slurry for forming a hydrogen storage alloy layer (active material) Slurry) was prepared. This hydrogen storage alloy layer forming slurry was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until moisture disappeared to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 124.5 degrees.

Comparative Example 1
A dispersion of PTFE as a binder (D-210C manufactured by Daikin Industries, Ltd.) was added to 98.5 parts by mass of the hydrogen storage alloy powder made of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 prepared in the step (1) of Example 1. 1.5 parts by mass (solid content) was added, and pure water was further added and kneaded to prepare a hydrogen storage alloy layer forming slurry (active material slurry). This hydrogen storage alloy layer forming slurry was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until moisture disappeared to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 63.5 degrees.

Comparative Example 2
A dispersion of PTFE as a binder (D-210C manufactured by Daikin Industries, Ltd.) was added to 98.5 parts by mass of the hydrogen storage alloy powder composed of MmNi _3.4 Co _0.8 Al _0.2 Mn _0.6 prepared in step (1) of Example 1. 1.5 parts by mass (solid content) was added, and pure water was further added and kneaded to prepare a hydrogen storage alloy layer forming slurry (active material slurry). This slurry for forming a hydrogen storage alloy layer was applied to a nickel-plated punching metal and dried in a constant temperature bath at 90 ° C. until there was no water.

  Next, PTFE dispersion (D-210C manufactured by Daikin Industries, Ltd.) was uniformly applied to the obtained hydrogen storage alloy electrode so as to have a thickness of about 15 μm, and then the water disappeared again in a constant temperature bath at 90 ° C. Was dried to prepare a hydrogen storage alloy electrode (negative electrode).

  When the contact angle with water on the surface of the hydrogen storage alloy layer of the obtained hydrogen storage alloy electrode was examined, it was 105.0 degrees.

Example 11
The hydrogen storage alloy electrode of the present invention produced in Example 1 was cut into a size of 330 mm × 30 mm to form a negative electrode, a fired nickel plate (270 mm × 30 mm) was used as a positive electrode, and a thickness of 130 μm as a separator between the positive electrode and the negative electrode Was wound in a spiral shape with a polypropylene non-woven fabric subjected to hydrophilization treatment in between, and then accommodated in a battery can having a size of SUBC (diameter 22.5 mm, total length 43 mm). Next, a 6N-potassium hydroxide aqueous solution was filled in the battery can and then sealed to prepare a nickel metal hydride secondary battery of the present invention.

  The cycle characteristics and load characteristics of this nickel metal hydride secondary battery were examined as follows. The results are shown in Table 1.

(Load characteristics)
After charging at a current value of 1 C for 1.5 hours, the discharge capacity when discharged to a final voltage of 1.0 V at a current value of 3.0 C is measured. The evaluation is performed using an index with the discharge capacity of Comparative Example 3 as 100.

(Cycle characteristics)
A charge / discharge cycle in which the battery is charged at a current value of 1 C for 1.5 hours and then discharged to a final voltage of 1.0 V at a current value of 1 C while measuring the discharge capacity is defined as one cycle. The number of cycles until the discharge capacity becomes 80% or less of the initial discharge capacity is counted, and the evaluation is performed using an index with the number of cycles of Comparative Example 3 as 100.

Examples 12-20 and Comparative Examples 3-4
A nickel-metal hydride secondary battery was produced in the same manner as in Example 11 except that the hydrogen storage alloy electrodes manufactured in Examples 2 to 10 and Comparative Examples 1 and 2 were used, and the cycle characteristics and load characteristics were examined. The results are shown in Table 1.

  From the results of Table 1, it can be seen that all the examples are clearly improved in both load characteristics and cycle characteristics as compared with Comparative Examples 3 and 4. Further, in Comparative Example 4 in which a PTFE dispersion was later applied to the electrode, since some of the hydrogen storage alloy particles were not uniformly covered, the water repellency became poor as a whole, and carboxylic acid was used as the electrode. It is considered that the load characteristics and the cycle characteristics were not improved as compared with Example 7 applied later.

Claims (4)

Formula (1): Rf-X (wherein Rf is a fluoroalkyl group optionally containing an ether bond having 1 to 12 carbon atoms; X is carboxylic acid, sulfonic acid, phosphoric acid, silicic acid and derivatives thereof) A hydrogen storage alloy electrode having a hydrogen storage alloy layer (I) containing a fluorine compound (a), a binder (b) and hydrogen storage alloy particles (c) shown on a conductive support (II). The hydrogen storage alloy electrode according to claim 1, wherein X in the formula (1) of the fluorine compound (a) is a carboxylic acid ester, a phosphoric acid ester or a silicate. The hydrogen storage alloy electrode according to claim 1 or 2, wherein Rf in the formula (1) of the fluorine compound (a) is a fluoroalkyl group having 1 to 8 carbon atoms. A nickel metal hydride secondary battery comprising the hydrogen storage alloy electrode according to any one of claims 1 to 3 as a negative electrode, and a positive electrode and an alkaline electrolyte.