WO2015019647A1 - Nickel-metal hydride storage battery - Google Patents

Nickel-metal hydride storage battery Download PDF

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Publication number
WO2015019647A1
WO2015019647A1 PCT/JP2014/056203 JP2014056203W WO2015019647A1 WO 2015019647 A1 WO2015019647 A1 WO 2015019647A1 JP 2014056203 W JP2014056203 W JP 2014056203W WO 2015019647 A1 WO2015019647 A1 WO 2015019647A1
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Prior art keywords
nickel
electrode plate
metal hydride
battery
storage battery
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PCT/JP2014/056203
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French (fr)
Japanese (ja)
Inventor
賢一 前原
和城 中野
坂本　弘之
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プライムアースＥｖエナジー 株式会社
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Publication of WO2015019647A1 publication Critical patent/WO2015019647A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/30—Nickel accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/24—Alkaline accumulators
    • H01M10/26—Selection of materials as electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/24—Electrodes for alkaline accumulators
    • H01M4/32—Nickel oxide or hydroxide electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M2010/4292—Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0002—Aqueous electrolytes
    • H01M2300/0014—Alkaline electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a nickel metal hydride storage battery.
  • the nickel-metal hydride storage battery As is well known, various alkaline storage batteries (secondary batteries) are used as power sources for portable electronic devices and as power sources for electric vehicles and hybrid vehicles. Of these alkaline storage batteries, the nickel-metal hydride storage battery has a high energy density and is excellent in reliability.
  • This nickel-metal hydride storage battery includes, for example, an electrode plate group in which a plurality of positive electrodes mainly composed of nickel hydroxide and a negative electrode mainly composed of a hydrogen storage alloy are laminated via a separator, and an alkali composed of potassium hydroxide or the like. It is configured to be stored in a storage container together with the electrolytic solution.
  • Patent Document 1 discloses an example of such a nickel metal hydride storage battery.
  • a hydride secondary battery (nickel metal hydride storage battery) described in Patent Document 1 is composed of a positive electrode containing nickel oxide or nickel hydroxide, a negative electrode containing a hydrogen storage alloy, an electrolytic solution made of an alkaline aqueous solution, and a nonwoven fabric. And a separator.
  • the hydride secondary battery contains at least one metal ion selected from the group consisting of molybdenum ions, tungsten ions, and chromium ions in the electrolytic solution.
  • the content of metal ions in the electrolyte is 0.1 to 5% by weight as the metal amount of metal ions.
  • An object of the present invention is to provide a nickel-metal hydride storage battery that maintains good performance even in an extended use environment or storage environment while maintaining a low battery resistance value.
  • the nickel metal hydride storage battery according to the present invention is a nickel metal hydride storage battery mounted on a vehicle, and encloses an electrode group, an electrolytic solution containing a tungsten element and a potassium element, and the electrode group and the electrolytic solution. And a container.
  • the electrode group includes an active material containing nickel hydroxide as a main component, and a positive electrode plate including a compound powder containing zinc element mixed with the active material, a negative electrode plate including a hydrogen storage alloy, A separator disposed between the positive electrode plate and the negative electrode plate.
  • the relationship of the weight percentage of each element based on the total weight of the electrolyte and the zinc element is 0.02 ⁇ (wt% tungsten element + wt% zinc element) / (potassium) % By weight of element) ⁇ 0.16.
  • the graph which shows the relationship between the characteristic and composition of a nickel hydride storage battery about one Embodiment with which the nickel hydride storage battery was actualized.
  • Sectional drawing which shows a nickel metal hydride storage battery.
  • Sectional drawing which shows the electrode group of the nickel hydride storage battery of FIG.
  • the nickel-metal hydride storage battery 1 of this embodiment is a sealed battery used as a power source for an electric vehicle or a hybrid vehicle.
  • this nickel metal hydride storage battery 1 includes an electrode group 10 including a positive electrode plate 11, a negative electrode plate 12, and a separator 13, and the electrode group 10 includes, for example, a plurality of hydrogen storage alloys.
  • Negative electrode plates 12 and a plurality of positive electrode plates 11 containing nickel hydroxide (Ni (OH) 2 ) are alternately stacked via separators 13 made of a non-woven fabric of alkali-resistant resin.
  • the electrode group 10 shown in FIG. 3 includes ten positive plates 11 and eleven negative plates 12.
  • the electrode group according to another aspect includes 12 positive plates and 13 negative plates.
  • the negative electrode plate is manufactured by applying hydrogen storage alloy powder to a substrate made of a porous metal such as punching metal.
  • the positive electrode plate is manufactured by filling a substrate made of a metal porous body such as a foamed nickel substrate with an active material containing nickel hydroxide particles.
  • the positive electrode plate 11 is connected to a positive current collector plate 21, and the negative electrode plate 12 is connected to a negative current collector plate 22.
  • the electrode group 10 is housed in a sealed resin storage container 20, together with an electrolyte, in a so-called battery case.
  • nickel hydroxide particles contained as an active material in the positive electrode plate 11 were prepared as nickel hydroxide particles containing magnesium in a solid solution state by a known method.
  • a coating layer of cobalt oxyhydroxide having a ⁇ -type crystal structure was formed as a cobalt compound coating layer on the surface of nickel hydroxide particles containing magnesium in a solid solution state by a known method. That is, the active material of the positive electrode plate contains nickel hydroxide particles covered with a coating layer of a cobalt compound.
  • a nickel positive electrode constituting the positive electrode plate 11 was manufactured. Specifically, first, 100 parts by weight of the positive electrode active material powder obtained as described above was mixed with yttrium oxide (Y 2 O 3 ) powder as an additive and zinc oxide (ZnO) powder as an additive. A predetermined amount of each was added and mixed, and a predetermined amount of each of metallic cobalt and water was added thereto and kneaded to form a paste. The paste was filled into a foamed nickel substrate, dried, and then pressure-molded to produce a nickel positive electrode plate. Then, the positive electrode plate 11 was manufactured by cutting the nickel positive electrode plate into a predetermined size.
  • Y 2 O 3 yttrium oxide
  • ZnO zinc oxide
  • Zn 3 N 2 , Zn (NO 3 ) 2 .6H 2 O, Zn 3 P 2 , Zn (PH 2 O 2 ) 2 .H 2 O, Zn 3 (PO 4 ) 2. 4H 2 O, Zn (H 2 PO 4 ) 2 .2H 2 O, Zn 2 P 2 O 7 , ZnCO 3 , Zn (CN) 2 , Zn (SCN) 2, and the like can be given.
  • the electrolytic solution contains pure water and potassium element (K).
  • the electrolytic solution is held in the separator 13 by being accommodated together with the electrode group 10 in the battery case 20. Further, the electrolytic solution is supplied to the positive electrode plate 11 and the negative electrode plate 12 through the separator 13, thereby conducting ions between the positive electrode plate 11 and the negative electrode plate 12.
  • the potassium compound that supplies potassium element (K) to the electrolytic solution is often potassium hydroxide (KOH).
  • the electrolytic solution further contains a tungsten element (W).
  • the tungsten compound for supplying elemental tungsten (W) is the electrolyte, WO 2, WO 3, WO 3 ⁇ H 2 O, W 2 O 5, W 2 O 5 ⁇ H 2 O, ZrW 2 O 8, Al 2 (WO 4 ) 3 , WC, CaWO 4 , FeWO 4 , MnWO 4 , WCl 6 , WBr 6 , WCl 2 F 4 and the like.
  • the electrolytic solution contains at least tungsten element, potassium element and pure water.
  • the electrolyte solution may contain an additive other than the tungsten compound and the potassium compound, for example, LiOH as another additive of pure water.
  • each of the tungsten element and the potassium element contained in the electrolytic solution is obtained so that a nickel-metal hydride storage battery having excellent characteristics for use under a high load and a long-term storage can be obtained.
  • the amount of zinc element contained in the positive electrode plate were adjusted. More specifically, the composition of each element contained in the electrolytic solution and the positive electrode was adjusted so that a nickel-metal hydride storage battery having battery characteristics having both excellent long-term storage characteristics and low battery resistance was obtained. Note that the nickel-metal hydride storage battery having excellent long-term storage characteristics is indicated by a high capacity retention rate after storage.
  • nickel-metal hydride storage batteries usually have a high capacity retention rate (higher) at a high temperature or the like by adding tungsten element to the electrolyte solution or adding zinc element to the positive electrode plate. It becomes larger (deteriorates).
  • the nickel-metal hydride storage battery has a low (higher) capacity retention rate at a high temperature or the like due to the addition of potassium element to the electrolytic solution, but a lower (higher) battery resistance.
  • the effect produced by the tungsten element and the zinc element and the effect produced by the potassium element are in a contradictory relationship, an attempt is made to reconcile the two battery characteristics of excellent capacity retention and low battery resistance. Then, it is necessary to adjust the composition of the electrolytic solution and the composition of the positive electrode plate based on the relationship between the tungsten element, the zinc element, and the potassium element.
  • the inventors conducted sincere research on the relationship between the tungsten element, the zinc element, and the potassium element that can achieve two battery characteristics of an excellent capacity maintenance rate and a low battery resistance.
  • the inventors then used the weight of the electrolytic solution and the weight of the zinc element contained as the compound powder in the positive electrode plate (hereinafter referred to as “total weight”) as a reference, and the tungsten contained in the electrolytic solution. It has been found that the relationship between the elements, potassium element, and zinc element contained in the positive electrode plate as compound powder is evaluated based on the index value calculated from the following evaluation formula (1).
  • the characteristics of the nickel-metal hydride battery are adjusted by adjusting the weight% of each element in the combined weight so that the index value calculated from the evaluation formula (1) satisfies the range shown in the following formula (2). It became clear that it can be improved.
  • the weight percent of the tungsten element based on the total weight is in the range of 1.1 wt% or more and 21.8 wt% or less. This is because the tungsten element and the zinc element have an effect of suppressing the change in the valence of the positive electrode active material [NiOOH ⁇ Ni (OH) 2 ], so the added amount per combined weight (weight% based on the combined weight). ) Must be specified. As described above, since the battery resistance increases as the addition amount of the tungsten element and the zinc element increases, the addition amount of the tungsten element and the zinc element does not become an excessive addition amount so that the electrical resistance becomes excessively large. Need to be specified.
  • tungsten element is easily dissolved in the electrolytic solution, it is highly dispersed to the positive electrode interface when added to the electrolytic solution.
  • zinc element is hardly dissolved in the electrolytic solution, it is appropriately dispersed in the positive electrode plate by being added as a compound powder to the paste containing the positive electrode active material. That is, the addition of tungsten element to the electrolytic solution and the addition of zinc element to the positive electrode plate as a compound powder of zinc element enables appropriate dispersion of tungsten element and zinc element. Therefore, it is possible to obtain a nickel-metal hydride storage battery having both battery characteristics of an excellent capacity retention rate and low battery resistance.
  • Capacity retention rate after storage [%] Residual SOC after storage [%] / 60 [%] ⁇ 100 (4)
  • SOC State Of Charge
  • battery resistance is measured as follows. First, the storage battery is charged at room temperature until the amount of stored electricity (SOC) reaches 60%. Thereafter, for example, the direct current internal resistance (DC-IR) of the nickel-metal hydride storage battery is calculated from “ ⁇ V / 10A” from the voltage drop ( ⁇ V) when discharged at 10 A for 10 seconds.
  • SOC stored electricity
  • DC-IR direct current internal resistance
  • index value As shown in FIG. 1, when a positive electrode plate and an electrolytic solution whose index value calculated from the evaluation formula (1) is in the range of “0.000” to “0.222” are used for a nickel metal hydride storage battery, For each index value, the capacity retention rate and battery resistance after storage were obtained. However, when the index value is “0.000”, the weight% in the combined weight of the tungsten element and the zinc element is both “0”. Below, for each index value calculated from the evaluation formula (1), the value of the capacity retention rate after storage and the value of the battery resistance are described. For convenience of explanation, the value of the capacity maintenance ratio after storage is described as “maintenance ratio value”, and the value of battery resistance is described as “resistance value”.
  • the capacity maintenance rate after storage tends to be low (bad) when the index value is small, and high (good) when the index value is large. More specifically, the capacity retention rate after storage is relatively large in the range A1 of the index value from “0.000” to “0.02”, while the index value is “0.02”. In the range from A2 to A4 from “0.222” to “0.222”, it has been clarified that the increase in the value tends to be relatively small. In other words, the capacity retention rate after storage is the range after the value has greatly increased, the range A2 to A4 where the index value is “0.02” or more, and the range A1 where the index value is less than “0.02”. It is a relatively good value compared to the value at.
  • the capacity maintenance rate after storage tends to decrease as the index value increases even if the index value is in the range A2 to A4 of “0.02” or more. That is, the increase in the value of the capacity maintenance rate after storage is smaller in the ranges A3 and A4 where the index value is “0.11” or more than in the range A2 where the index value is less than “0.11”. In the range A4 where the value is “0.16” or more, it becomes even smaller. In the range A4, the capacity retention rate hardly increases.
  • the resistance values R01 to R13 are shown in the graph LR when the index value is between “0.000” and “0.250” (range A1 to A4).
  • the battery resistance tends to be small (good) when the index value is small and large (bad) when the index value is large.
  • the battery resistance increases in a substantially constant increase range in accordance with the increase of the index value in the range A1 to A4 in which the index value is “0.000” to “0.250”.
  • a nickel-metal hydride storage battery mounted on a vehicle needs to pass a large current, so that the battery resistance value needs to be kept small regardless of the use environment.
  • the value of the battery resistance is preferably small, and it is not preferable that the electric resistance value of the nickel-metal hydride storage battery mounted on the vehicle exceeds 3.0 [m ⁇ ] because of the energy loss. That is, it is not preferable that the index value is in a range A4 larger than the vicinity of “0.16”, which may cause the battery resistance value to exceed 3.0 [m ⁇ ].
  • the increase in the value of the capacity maintenance rate after storage decreases as the index value increases, while the increase in the value of the battery resistance increases. Increases at a substantially constant rate as the index value increases. For this reason, as the index value increases, the value of the capacity maintenance rate after storage slows down, while the battery resistance constantly increases. From this, as the index value increases, the value of the battery resistance increases as compared to the improvement in battery characteristics obtained by increasing the capacity retention ratio after storage (capacity retention ratio improves) ( The deterioration of the battery characteristics due to the deterioration of the battery resistance becomes relatively large.
  • the value of the capacity retention rate after storage hardly increases as an index value that can maintain suitable battery characteristics, which is about “0.16”.
  • the following ranges A2 and A3 are preferable. More preferably, the range A2 of about “0.11” or less in which the increase in the value of the capacity retention rate after storage is small is preferable.
  • the lower limit of the index value for maintaining preferable battery characteristics is preferably before the capacity maintenance rate after storage suddenly decreases, that is, about “0.02”.
  • the upper limit of the index value for maintaining preferable battery characteristics is preferably about 0.16 or less at which the capacity retention rate after storage hardly increases, and more preferably, the value of the capacity maintenance rate after storage is increased. Is preferably about 0.11 or less. That is, as shown in FIG. 1, the positive electrode plate and the electrolyte solution that make the nickel hydride storage battery have both the two battery characteristics of the capacity maintenance rate excellent in storage and the low battery resistance, that is, the preferable battery characteristics are maintained. It is preferable that the value is in the range A2, A3 from “0.02” to “0.16”. In addition, the positive electrode plate and the electrolytic solution that maintain the preferable battery characteristics are more preferably in the range A2 from “0.02” to “0.11”.
  • the positive electrode plate and the electrolytic solution that can obtain the battery characteristics in which the two characteristics of the capacity retention rate excellent in storage and the low battery resistance are compatible have an index value of “0.02” as shown in Equation (2). It has become clear that it is preferable to be in the range A2 and A3 of “0.16” or less. Further, the positive electrode plate and the electrolytic solution that can obtain more preferable battery characteristics have an index value in the range A2 of “0.02” or more and “0.11” or less as shown in the formula (3). Was found to be preferable.
  • the characteristics of the nickel-metal hydride storage battery can be changed by changing the additive to the electrolytic solution.
  • nickel-metal hydride storage batteries that have good performance under the expanding usage environment conditions and storage environment conditions have been desired.
  • the configuration of the electrolytic solution suitable for maintaining such performance satisfactorily and the configuration of the positive electrode plate were not clear.
  • the nickel metal hydride storage battery mounted in a vehicle needs to flow a large current, it is necessary to keep the value of the battery resistance small regardless of the use environment.
  • adding tungsten element to the electrolytic solution or zinc element to the positive electrode plate increases (improves) the capacity retention ratio after storage, while increasing (deteriorates) battery resistance.
  • adding potassium element to the electrolytic solution the battery resistance is decreased (improved), while the capacity retention rate after storage is decreased (deteriorated). Therefore, in the situation where there are no provisions regarding the addition amount of tungsten element, potassium element, and zinc element, these additives are added to the electrolyte solution or added to the positive electrode plate so that good battery performance is maintained. It was difficult to do.
  • the evaluation formula (1) regarding the addition amount of tungsten element, potassium element, and zinc element and the appropriate range of the index value calculated from the evaluation formula (1) are defined.
  • a nickel-metal hydride storage battery having a low battery resistance excellent in use at a high load and a capacity retention rate excellent in long-term storage can be obtained. This provides a nickel-metal hydride storage battery that maintains good performance even under expanded use and storage environments.
  • tungsten element is easily dissolved in the electrolytic solution, it is highly dispersed to the positive electrode interface when added to the electrolytic solution.
  • zinc element is hardly dissolved in the electrolytic solution, it is appropriately dispersed in the positive electrode plate by being added as a compound powder to the paste containing the positive electrode active material. That is, it is possible to appropriately disperse the tungsten element and the zinc element by adding the tungsten element to the electrolytic solution and adding the zinc element to the positive electrode plate as the compound powder of the zinc element.
  • the valence of the positive electrode active material is adjusted by adjusting the content percentage by weight of the tungsten element in the total weight of the electrolyte solution and the zinc element contained in the positive electrode plate as compound powder. While the decrease [NiOOH ⁇ Ni (OH) 2 ] is satisfactorily suppressed, it is also possible to suppress an increase in battery resistance caused by excessive addition.
  • a nickel-metal hydride storage battery in which two characteristics of a capacity retention rate excellent in long-term storage and a low battery resistance are better compatible can be obtained.
  • the weight% of the said embodiment may be the mass%.
  • the resin storage container 20 is illustrated, but the material of the storage container is not limited to this.
  • the storage container may be made of a material other than a resin such as a metal as long as it can be used as a battery case. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
  • the electrode group 10 is illustrated in which a plurality of negative plates 12 and a plurality of positive plates are alternately stacked via separators.
  • an electrode device including 13 negative plates and 12 positive plates is shown.
  • the present invention is not limited thereto, and the number of negative electrode plates may be less than 13 or more than 13 as long as the electrode group is appropriately configured.
  • the number of positive electrode plates may be less than 12, or more than 12. Thereby, the expansion of the application range of a nickel metal hydride storage battery is achieved.
  • the negative electrode plate 12 manufactured by applying a hydrogen storage alloy powder to a substrate made of a porous metal such as punching metal is illustrated.
  • the present invention is not limited to this, and the negative electrode plate may be manufactured in any way as long as it functions as a negative electrode plate. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
  • the positive electrode plate 11 manufactured by filling a substrate made of a metal porous body such as a foamed nickel substrate with an active material containing nickel hydroxide particles is illustrated.
  • the present invention is not limited to this, and the positive electrode plate may be manufactured in any way as long as it functions as a positive electrode plate and zinc element can be added.
  • a positive electrode plate may be manufactured by filling a substrate made of a metal porous body such as a sintered substrate with a chemical reaction using an active material. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
  • the paste including the positive electrode active material powder, the yttrium oxide powder, the zinc oxide powder, the metallic cobalt, and water is illustrated.
  • the present invention is not limited to this, and the paste may not contain at least one of yttrium oxide powder and metallic cobalt as long as an appropriate positive electrode plate can be obtained. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
  • the separator 13 which is a non-woven fabric of alkali resistant resin is illustrated.
  • the present invention is not limited to this, and the separator may be formed from a material corresponding to the nickel metal hydride storage battery. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
  • the nickel metal hydride storage battery 1 used as a power source for an electric vehicle or a hybrid vehicle is exemplified.
  • the nickel metal hydride storage battery may be used as a power source other than an automobile that requires a power source.
  • power sources other than automobiles include moving bodies such as railways, ships, airplanes, and robots, and power supplies for electrical products such as information processing apparatuses. Thereby, the expansion of the application range of a nickel metal hydride storage battery is achieved.

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  • Electrochemistry (AREA)
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Abstract

This nickel-metal hydride storage battery to be mounted to a vehicle comprises an electrode group, an electrolyte solution that contains elemental tungsten and elemental potassium, and a container in which the electrode group and the electrolyte solution are hermetically contained. The electrode group is provided with: a positive electrode plate which contains an active material that is mainly composed of nickel hydroxide, and a compound powder that contains elemental zinc and is mixed into the active material; a negative electrode plate which contains a hydrogen storage alloy; and a separator which is arranged between the positive electrode plate and the negative electrode plate. The relationship among the percentages by weight of the elements based on the total weight of the electrolyte solution and the elemental zinc satisfies 0.02 ≤ (percentage by weight of elemental tungsten + percentage by weight of elemental zinc)/(percentage by weight of elemental potassium) ≤ 0.16.

Description

ニッケル水素蓄電池Nickel metal hydride storage battery
　本発明は、ニッケル水素蓄電池に関する。 The present invention relates to a nickel metal hydride storage battery.
　周知のように、携帯用の電子機器の電源として、また、電気自動車やハイブリッド自動車などの電源として、様々なアルカリ蓄電池（二次電池）が用いられている。そして、こうしたアルカリ蓄電池のうちニッケル水素蓄電池は、エネルギー密度が高く、信頼性に優れた蓄電池である。このニッケル水素蓄電池は、例えば、水酸化ニッケルを主成分とした正極と水素吸蔵合金を主成分とした負極とがセパレータを介して複数枚積層された極板群を、水酸化カリウムなどからなるアルカリ電解液とともに収納容器に収納して構成されている。特許文献１は、このようなニッケル水素蓄電池の一例を開示している。 As is well known, various alkaline storage batteries (secondary batteries) are used as power sources for portable electronic devices and as power sources for electric vehicles and hybrid vehicles. Of these alkaline storage batteries, the nickel-metal hydride storage battery has a high energy density and is excellent in reliability. This nickel-metal hydride storage battery includes, for example, an electrode plate group in which a plurality of positive electrodes mainly composed of nickel hydroxide and a negative electrode mainly composed of a hydrogen storage alloy are laminated via a separator, and an alkali composed of potassium hydroxide or the like. It is configured to be stored in a storage container together with the electrolytic solution. Patent Document 1 discloses an example of such a nickel metal hydride storage battery.
　特許文献１に記載の水素化物二次電池（ニッケル水素蓄電池）は、ニッケル酸化物またはニッケル水酸化物を含む正極と、水素吸蔵合金を含む負極と、アルカリ水溶液からなる電解液と、不織布からなるセパレータとを有する。そしてこの水素化物二次電池には、電解液中にモリブデンイオン、タングステンイオンおよびクロムイオンよりなる群から選ばれる少なくとも１種の金属イオンが含有される。金属イオンの電解液中での含有量は、金属イオンの金属量として０．１～５重量％である。 A hydride secondary battery (nickel metal hydride storage battery) described in Patent Document 1 is composed of a positive electrode containing nickel oxide or nickel hydroxide, a negative electrode containing a hydrogen storage alloy, an electrolytic solution made of an alkaline aqueous solution, and a nonwoven fabric. And a separator. The hydride secondary battery contains at least one metal ion selected from the group consisting of molybdenum ions, tungsten ions, and chromium ions in the electrolytic solution. The content of metal ions in the electrolyte is 0.1 to 5% by weight as the metal amount of metal ions.
特開平８－８８０２０号公報JP-A-8-88020
　上述の特許文献１に記載のニッケル水素蓄電池によれば、高温環境における保存後の容量を維持する特性に優れたニッケル水素蓄電池が得られる。 According to the nickel-metal hydride storage battery described in Patent Document 1 described above, a nickel-metal hydride storage battery having excellent characteristics for maintaining the capacity after storage in a high-temperature environment can be obtained.
　近年、電気自動車やハイブリッド自動車の利用環境が様々な環境に拡大していくことに伴って、それら電気自動車やハイブリッド自動車に搭載されているニッケル水素蓄電池の使用環境条件や保存環境条件の拡大が避けられなくなってきている。また、車両に搭載される蓄電池は、大電流を流す必要があるので、その使用環境にかかわらず、その電池抵抗の値を小さく維持する必要がある。そのため、電池抵抗の値を小さく維持しつつ、拡大される使用環境条件や保存環境条件にあってその性能が良好に維持されるニッケル水素蓄電池の研究及び開発が進められている。 In recent years, as the usage environment of electric vehicles and hybrid vehicles has expanded to various environments, the use environment conditions and storage environment conditions of nickel-metal hydride storage batteries installed in these electric vehicles and hybrid vehicles should be avoided. It is becoming impossible. Moreover, since the storage battery mounted in a vehicle needs to flow a large current, it is necessary to keep the value of the battery resistance small irrespective of the use environment. Therefore, research and development of nickel-metal hydride storage batteries that maintain good performance under expanded use environment conditions and storage environment conditions while keeping the battery resistance value small are underway.
　本発明の目的は、電池抵抗の値を小さく維持しつつ、拡大される使用環境下や保存環境下にあっても良好な性能が維持されるニッケル水素蓄電池を提供することにある。 An object of the present invention is to provide a nickel-metal hydride storage battery that maintains good performance even in an extended use environment or storage environment while maintaining a low battery resistance value.
　本発明におけるニッケル水素蓄電池の一態様は、車両に搭載されるニッケル水素蓄電池であって、電極群と、タングステン元素及びカリウム元素を含む電解液と、前記電極群と前記電解液とを封入する収納容器と、を備えている。前記電極群は、水酸化ニッケルを主成分とする活物質を含み、かつ、亜鉛元素を含む化合物粉末を前記活物質に混合された態様で含む正極板と、水素吸蔵合金を含む負極板と、前記正極板と前記負極板との間に配置されるセパレータとを備える。前記電解液の重量と前記亜鉛元素の重量とを合せた重量を基準とした前記各元素の重量％の関係が、０．０２≦（タングステン元素の重量％＋亜鉛元素の重量％）／（カリウム元素の重量％）≦０．１６である。 One aspect of the nickel metal hydride storage battery according to the present invention is a nickel metal hydride storage battery mounted on a vehicle, and encloses an electrode group, an electrolytic solution containing a tungsten element and a potassium element, and the electrode group and the electrolytic solution. And a container. The electrode group includes an active material containing nickel hydroxide as a main component, and a positive electrode plate including a compound powder containing zinc element mixed with the active material, a negative electrode plate including a hydrogen storage alloy, A separator disposed between the positive electrode plate and the negative electrode plate. The relationship of the weight percentage of each element based on the total weight of the electrolyte and the zinc element is 0.02 ≦ (wt% tungsten element + wt% zinc element) / (potassium) % By weight of element) ≦ 0.16.
ニッケル水素蓄電池が具体化された一実施形態について、ニッケル水素蓄電池の特性と組成との関係を示すグラフ。The graph which shows the relationship between the characteristic and composition of a nickel hydride storage battery about one Embodiment with which the nickel hydride storage battery was actualized. ニッケル水素蓄電池を示す断面図。Sectional drawing which shows a nickel metal hydride storage battery. 図２のニッケル水素蓄電池の電極群を示す断面図。Sectional drawing which shows the electrode group of the nickel hydride storage battery of FIG.
　ニッケル水素蓄電池を具体化した一実施形態について説明する。 An embodiment embodying a nickel metal hydride storage battery will be described.
　本実施形態のニッケル水素蓄電池１は、電気自動車やハイブリッド自動車の電源として用いられる密閉型の電池である。図２及び図３に示すように、このニッケル水素蓄電池１は、正極板１１と負極板１２とセパレータ１３とを備えた電極群１０を含み、電極群１０では、例えば、水素吸蔵合金を含む複数の負極板１２と、水酸化ニッケル（Ｎｉ（ＯＨ）２）を含む複数の正極板１１とが、耐アルカリ性樹脂の不織布から構成されるセパレータ１３を介して交互に積層されている。例えば、図３に示される電極群１０は、１０枚の正極板１１と、１１枚の負極板１２とを備えている。他の態様の電極群は、１２枚の正極板と、１３枚の負極板とを備えている。負極板は、パンチングメタルなどの金属多孔体からなる基板に水素吸蔵合金粉末を塗布して製作される。正極板は、発泡ニッケル基板などの金属多孔体からなる基板に水酸化ニッケル粒子を含む活物質を充填して製作される。 The nickel-metal hydride storage battery 1 of this embodiment is a sealed battery used as a power source for an electric vehicle or a hybrid vehicle. As shown in FIGS. 2 and 3, this nickel metal hydride storage battery 1 includes an electrode group 10 including a positive electrode plate 11, a negative electrode plate 12, and a separator 13, and the electrode group 10 includes, for example, a plurality of hydrogen storage alloys. Negative electrode plates 12 and a plurality of positive electrode plates 11 containing nickel hydroxide (Ni (OH) 2 ) are alternately stacked via separators 13 made of a non-woven fabric of alkali-resistant resin. For example, the electrode group 10 shown in FIG. 3 includes ten positive plates 11 and eleven negative plates 12. The electrode group according to another aspect includes 12 positive plates and 13 negative plates. The negative electrode plate is manufactured by applying hydrogen storage alloy powder to a substrate made of a porous metal such as punching metal. The positive electrode plate is manufactured by filling a substrate made of a metal porous body such as a foamed nickel substrate with an active material containing nickel hydroxide particles.
　正極板１１は正極側の集電板２１に接続され、負極板１２は負極側の集電板２２に接続されている。電極群１０は電解液とともに密閉型の樹脂製の収納容器２０内、いわゆる電槽内に収容されている。 The positive electrode plate 11 is connected to a positive current collector plate 21, and the negative electrode plate 12 is connected to a negative current collector plate 22. The electrode group 10 is housed in a sealed resin storage container 20, together with an electrolyte, in a so-called battery case.
　続いて、正極板１１の製作について詳述する。 Subsequently, the production of the positive electrode plate 11 will be described in detail.
　まず、正極板１１に活物質として含まれる水酸化ニッケル粒子を、公知の方法で、マグネシウムを固溶状態で含む水酸化ニッケル粒子として作成した。また、このマグネシウムを固溶状態で含む水酸化ニッケル粒子の表面には、公知の方法で、コバルト化合物被膜層としてβ型の結晶構造を有するオキシ水酸化コバルトの被覆層を形成した。つまり、正極板の活物質は、コバルト化合物の被膜層により被覆されている水酸化ニッケル粒子を含んでいる。 First, nickel hydroxide particles contained as an active material in the positive electrode plate 11 were prepared as nickel hydroxide particles containing magnesium in a solid solution state by a known method. A coating layer of cobalt oxyhydroxide having a β-type crystal structure was formed as a cobalt compound coating layer on the surface of nickel hydroxide particles containing magnesium in a solid solution state by a known method. That is, the active material of the positive electrode plate contains nickel hydroxide particles covered with a coating layer of a cobalt compound.
　次に、正極板１１を構成するニッケル正極を製作した。具体的には、まず、上述のようにして得られた正極活物質粉末１００重量部に、添加剤としての酸化イットリウム（Ｙ２Ｏ３）粉末と、同じく添加剤としての酸化亜鉛（ＺｎＯ）粉末をそれぞれ所定量ずつ添加して混合し、これに金属コバルトと水とをそれぞれ所定量ずつ加え、混練することにより、ペースト状にした。そして、このペーストを発泡ニッケル基板に充填し、乾燥した後、加圧成形することにより、ニッケル正極板を製作した。その後、このニッケル正極板を所定の大きさに切断することにより、正極板１１を製作した。 Next, a nickel positive electrode constituting the positive electrode plate 11 was manufactured. Specifically, first, 100 parts by weight of the positive electrode active material powder obtained as described above was mixed with yttrium oxide (Y 2 O 3 ) powder as an additive and zinc oxide (ZnO) powder as an additive. A predetermined amount of each was added and mixed, and a predetermined amount of each of metallic cobalt and water was added thereto and kneaded to form a paste. The paste was filled into a foamed nickel substrate, dried, and then pressure-molded to produce a nickel positive electrode plate. Then, the positive electrode plate 11 was manufactured by cutting the nickel positive electrode plate into a predetermined size.
　なお、正極活物質粉末に亜鉛元素（Ｚｎ）を供給する亜鉛化合物としては、上述した酸化亜鉛（ＺｎＯ）の他、ＺｎＯ２、ＺｎＦ２、ＺｎＦ２・Ｈ２Ｏ、ＺｎＣｌ２、Ｚｎ（ＯＨ）２、ＺｎＳ、ＺｎＳ２Ｏ４、ＺｎＳＯ３・２Ｈ２Ｏ、ＺｎＳＯ４、ＺｎＳＯ４・７Ｈ２Ｏなどが挙げられる。また、同亜鉛化合物としては、Ｚｎ３Ｎ２、Ｚｎ（ＮＯ３）２・６Ｈ２Ｏ、Ｚｎ３Ｐ２、Ｚｎ（ＰＨ２Ｏ２）２・Ｈ２Ｏ、Ｚｎ３（ＰＯ４）２・４Ｈ２Ｏ、Ｚｎ（Ｈ２ＰＯ４）２・２Ｈ２Ｏ、Ｚｎ２Ｐ２Ｏ７、ＺｎＣＯ３、Ｚｎ（ＣＮ）２、Ｚｎ（ＳＣＮ）２などが挙げられる。 As the zinc compound supply positive electrode active material powder to zinc element a (Zn), other than the above zinc oxide (ZnO), ZnO 2, ZnF 2, ZnF 2 · H 2 O, ZnCl 2, Zn (OH) 2 , ZnS, ZnS 2 O 4 , ZnSO 3 .2H 2 O, ZnSO 4 , ZnSO 4 .7H 2 O, and the like. Moreover, as the zinc compound, Zn 3 N 2 , Zn (NO 3 ) 2 .6H 2 O, Zn 3 P 2 , Zn (PH 2 O 2 ) 2 .H 2 O, Zn 3 (PO 4 ) 2. 4H 2 O, Zn (H 2 PO 4 ) 2 .2H 2 O, Zn 2 P 2 O 7 , ZnCO 3 , Zn (CN) 2 , Zn (SCN) 2, and the like can be given.
　次に、電解液について詳述する。 Next, the electrolyte solution will be described in detail.
　電解液は、純水とカリウム元素（Ｋ）とを含んでいる。電解液は、電槽２０内に電極群１０とともに収容されることで、セパレータ１３の中に保持される。また電解液は、セパレータ１３を介して正極板１１や負極板１２に供給されることで、正極板１１と負極板１２との間にイオンを伝導させる。なお、電解液にカリウム元素（Ｋ）を供給するカリウム化合物は、水酸化カリウム（ＫＯＨ）であることが多い。電解液にカリウム元素（Ｋ）を供給するカリウム化合物としては、ＫＯＨの他、Ｋ２Ｃ２、ＫＣｌ、ＫＦ、ＫＨ、ＫＮ３、Ｋ３Ｎ、ＫＯ２、ＫＯ３、Ｋ２Ｏ、Ｋ２Ｏ２、Ｋ３Ｐ、Ｋ２Ｓ、ＫＡｌＦ４、ＫＢＦ４、ＫＢＨ４、ＫＣＨ３、ＫＣＮ、ＫＨＣＯＯ、ＫＨＦ２、ＫＨＳ、ＫＮＨ２、ＫＰＦ６などが挙げられる。 The electrolytic solution contains pure water and potassium element (K). The electrolytic solution is held in the separator 13 by being accommodated together with the electrode group 10 in the battery case 20. Further, the electrolytic solution is supplied to the positive electrode plate 11 and the negative electrode plate 12 through the separator 13, thereby conducting ions between the positive electrode plate 11 and the negative electrode plate 12. The potassium compound that supplies potassium element (K) to the electrolytic solution is often potassium hydroxide (KOH). The potassium compound supplying potassium electrolyte element of (K), other KOH, K 2 C 2, KCl , KF, KH, KN 3, K 3 N, KO 2, KO 3, K 2 O, K 2 Examples include O 2 , K 3 P, K 2 S, KAlF 4 , KBF 4 , KBH 4 , KCH 3 , KCN, KHCOO, KHF 2 , KHS, KNH 2 , KPF 6 and the like.
　また、本実施形態では、電解液はさらに、タングステン元素（Ｗ）を含んでいる。電解液にタングステン元素（Ｗ）を供給するタングステン化合物としては、ＷＯ２、ＷＯ３、ＷＯ３・Ｈ２Ｏ、Ｗ２Ｏ５、Ｗ２Ｏ５・Ｈ２Ｏ、ＺｒＷ２Ｏ８、Ａｌ２（ＷＯ４）３、ＷＣ、ＣａＷＯ４、ＦｅＷＯ４、ＭｎＷＯ４、ＷＣｌ６、ＷＢｒ６、ＷＣｌ２Ｆ４などが挙げられる。また、同タングステン化合物としては、Ｗ（ＣＯ）６、ＷＯ２Ｃｌ２、Ｌｉ２ＷＯ２、Ｈ２ＷＯ４、Ｋ２ＷＯ４、Ｎａ２ＷＯ４、Ｌｉ２ＷＯ４・２Ｈ２Ｏ、Ｈ２ＷＯ４・２Ｈ２Ｏ、Ｋ２ＷＯ４・２Ｈ２Ｏ、Ｎａ２ＷＯ４・２Ｈ２Ｏ、（ＮＨ４）３ＰＯ４・１２ＷＯ３・３Ｈ２Ｏ、Ｎａ３（ＰＯ４・１２ＷＯ３）・ｘＨ２Ｏ、ＷＦ５、ＷＦ６などが挙げられる。 In the present embodiment, the electrolytic solution further contains a tungsten element (W). The tungsten compound for supplying elemental tungsten (W) is the electrolyte, WO 2, WO 3, WO 3 · H 2 O, W 2 O 5, W 2 O 5 · H 2 O, ZrW 2 O 8, Al 2 (WO 4 ) 3 , WC, CaWO 4 , FeWO 4 , MnWO 4 , WCl 6 , WBr 6 , WCl 2 F 4 and the like. Moreover, as the tungsten compound, W (CO) 6 , WO 2 Cl 2 , Li 2 WO 2 , H 2 WO 4 , K 2 WO 4 , Na 2 WO 4 , Li 2 WO 4 .2H 2 O, H 2 WO 4 · 2H 2 O, K 2 WO 4 · 2H 2 O, Na 2 WO 4 · 2H 2 O, (NH 4 ) 3 PO 4 · 12WO 3 · 3H 2 O, Na 3 (PO 4 · 12WO 3 ) · xH 2 O, such as WF 5, WF 6, and the like.
　つまり電解液は、少なくとも、タングステン元素、カリウム元素及び純水を含んでいる。なお、電解液には、純水の他の添加物として、タングステン化合物及びカリウム化合物以外の添加物、例えばＬｉＯＨなどが含まれていてもよい。 That is, the electrolytic solution contains at least tungsten element, potassium element and pure water. In addition, the electrolyte solution may contain an additive other than the tungsten compound and the potassium compound, for example, LiOH as another additive of pure water.
　ところで、本実施形態では、特に、大電流を流す高負荷での使用及び長期間の保存に良好な特性を有するニッケル水素蓄電池が得られるように、電解液に含まれるタングステン元素、カリウム元素のそれぞれの量、及び、正極板に含まれる亜鉛元素の量をそれぞれ調整した。詳述すると、優れた長期保存特性と低い電池抵抗との２つの特性が両立する電池特性を有するニッケル水素蓄電池が得られるように、電解液及び正極に含まれる各元素の組成を調整した。なお、長期保存特性が優れたニッケル水素蓄電池であることは、保管後の容量維持率が高いことにより示される。 By the way, in the present embodiment, each of the tungsten element and the potassium element contained in the electrolytic solution is obtained so that a nickel-metal hydride storage battery having excellent characteristics for use under a high load and a long-term storage can be obtained. And the amount of zinc element contained in the positive electrode plate were adjusted. More specifically, the composition of each element contained in the electrolytic solution and the positive electrode was adjusted so that a nickel-metal hydride storage battery having battery characteristics having both excellent long-term storage characteristics and low battery resistance was obtained. Note that the nickel-metal hydride storage battery having excellent long-term storage characteristics is indicated by a high capacity retention rate after storage.
　ところで通常、ニッケル水素蓄電池は、電解液にタングステン元素が添加されたり、正極板に亜鉛元素が添加されたりすることで、高温などでの容量維持率が高くなる（良くなる）ものの、電池抵抗が大きくなる（悪化する）。一方、ニッケル水素蓄電池は、電解液にカリウム元素が添加されることで高温などでの容量維持率が低くなる（悪化する）ものの、電池抵抗は小さくなる（良くなる）。このように、タングステン元素や亜鉛元素が生じさせる効果と、カリウム元素が生じさせる効果とが相反する関係にあるので、優れた容量維持率と低い電池抵抗との２つの電池特性を両立させようとすると、タングステン元素、亜鉛元素及びカリウム元素の関係に基づいて電解液の組成、及び、正極板の組成をそれぞれ調整する必要が生じる。 By the way, nickel-metal hydride storage batteries usually have a high capacity retention rate (higher) at a high temperature or the like by adding tungsten element to the electrolyte solution or adding zinc element to the positive electrode plate. It becomes larger (deteriorates). On the other hand, the nickel-metal hydride storage battery has a low (higher) capacity retention rate at a high temperature or the like due to the addition of potassium element to the electrolytic solution, but a lower (higher) battery resistance. As described above, since the effect produced by the tungsten element and the zinc element and the effect produced by the potassium element are in a contradictory relationship, an attempt is made to reconcile the two battery characteristics of excellent capacity retention and low battery resistance. Then, it is necessary to adjust the composition of the electrolytic solution and the composition of the positive electrode plate based on the relationship between the tungsten element, the zinc element, and the potassium element.
　そこで、発明者らは、優れた容量維持率と低い電池抵抗との２つの電池特性を両立させることのできる、タングステン元素、亜鉛元素及びカリウム元素の関係について誠意研究を行った。そして、発明者らは、電解液の重量と正極板に化合物粉末として含まれる亜鉛元素の重量とを合せた重量（以下、「合算重量」と記す。）を基準とし、電解液に含まれるタングステン元素、カリウム元素、及び正極板に化合物粉末として含まれる亜鉛元素のそれぞれの重量％の関係を、次の評価式（１）より算出される指標値に基づき評価することを見出した。 Therefore, the inventors conducted sincere research on the relationship between the tungsten element, the zinc element, and the potassium element that can achieve two battery characteristics of an excellent capacity maintenance rate and a low battery resistance. The inventors then used the weight of the electrolytic solution and the weight of the zinc element contained as the compound powder in the positive electrode plate (hereinafter referred to as “total weight”) as a reference, and the tungsten contained in the electrolytic solution. It has been found that the relationship between the elements, potassium element, and zinc element contained in the positive electrode plate as compound powder is evaluated based on the index value calculated from the following evaluation formula (1).
　（タングステン元素の重量％＋亜鉛元素の重量％）／（カリウム元素の重量％）・・・（１）
つまり、この指標値によれば、タングステン元素、カリウム元素、及び亜鉛元素の関係に基づいて、優れた容量維持率と低い電池抵抗との２つの電池特性を共に有するニッケル水素蓄電池が得られるか否かを判断できることが明らかになった。 (Wt% of tungsten element + wt% of zinc element) / (wt% of potassium element) (1)
That is, according to this index value, whether or not a nickel-metal hydride storage battery having both battery characteristics of an excellent capacity retention ratio and low battery resistance can be obtained based on the relationship between tungsten element, potassium element, and zinc element. It became clear that it can be judged.
　詳述すると、評価式（１）より算出される指標値が、次式（２）に示す範囲を満足するように合算重量中での各元素の重量％を調整することによりニッケル水素蓄電池の特性を良好にできることが明らかになった。 More specifically, the characteristics of the nickel-metal hydride battery are adjusted by adjusting the weight% of each element in the combined weight so that the index value calculated from the evaluation formula (1) satisfies the range shown in the following formula (2). It became clear that it can be improved.
　０．０２≦（タングステン元素の重量％＋亜鉛元素の重量％）／（カリウム元素の重量％）≦０．１６・・・（２）
　つまり、式（２）を満足するように合算重量中の各元素の重量％が調整された正極板及び電解液によれば、優れた容量維持率と低い電池抵抗との２つの電池特性を共に有するニッケル水素蓄電池が得られることが明らかになった。 0.02 ≦ (wt% of tungsten element + wt% of zinc element) / (wt% of potassium element) ≦ 0.16 (2)
That is, according to the positive electrode plate and the electrolytic solution in which the weight% of each element in the combined weight is adjusted so as to satisfy the formula (2), the two battery characteristics of an excellent capacity retention rate and a low battery resistance are both obtained. It became clear that the nickel hydride storage battery which has is obtained.
　また、評価式（１）より算出される指標値が、次式（３）を満足するときには、ニッケル水素蓄電池の特性をより良好にする正極板及び電解液が得られることが明らかになった。 It has also been clarified that when the index value calculated from the evaluation formula (1) satisfies the following formula (3), a positive electrode plate and an electrolytic solution that improve the characteristics of the nickel-metal hydride storage battery can be obtained.
　０．０２≦（タングステン元素の重量％＋亜鉛元素の重量％）／（カリウム元素の重量％）≦０．１１・・・（３）
　なお、本実施形態では、合算重量を基準としたタングステン元素の重量％が１．１重量％以上、かつ、２１．８重量％以下の範囲である。これは、タングステン元素や亜鉛元素は、正極活物質の価数低下変化［ＮｉＯＯＨ→Ｎｉ（ＯＨ）２］を抑制する効果があるので、合算重量あたりの添加量（合算重量を基準とした重量％）を規定する必要があるからである。なお、上述の通り、タングステン元素と亜鉛元素の添加量が増加すると電池抵抗が大きくなるので、電気抵抗が過度に大きくなるような過剰な添加量とはならない範囲でタングステン元素と亜鉛元素の添加量が規定される必要もある。 0.02 ≦ (wt% of tungsten element + wt% of zinc element) / (wt% of potassium element) ≦ 0.11 (3)
In the present embodiment, the weight percent of the tungsten element based on the total weight is in the range of 1.1 wt% or more and 21.8 wt% or less. This is because the tungsten element and the zinc element have an effect of suppressing the change in the valence of the positive electrode active material [NiOOH → Ni (OH) 2 ], so the added amount per combined weight (weight% based on the combined weight). ) Must be specified. As described above, since the battery resistance increases as the addition amount of the tungsten element and the zinc element increases, the addition amount of the tungsten element and the zinc element does not become an excessive addition amount so that the electrical resistance becomes excessively large. Need to be specified.
　また、タングステン元素は電解液に溶けやすいので、電解液に添加されることで正極板界面へ高分散される。一方、亜鉛元素は電解液に溶けにくいので、正極の活物質を含むペーストへの化合物粉末として添加されることよって正極板へ適切に分散される。つまり、タングステン元素の電解液への添加と、亜鉛元素の化合物粉末としての正極板への添加とにより、タングステン元素と亜鉛元素とを適切に分散させることが可能にもなる。よって、優れた容量維持率と低い電池抵抗との２つの電池特性を共に有するニッケル水素蓄電池を得ることができる。 Also, since tungsten element is easily dissolved in the electrolytic solution, it is highly dispersed to the positive electrode interface when added to the electrolytic solution. On the other hand, since zinc element is hardly dissolved in the electrolytic solution, it is appropriately dispersed in the positive electrode plate by being added as a compound powder to the paste containing the positive electrode active material. That is, the addition of tungsten element to the electrolytic solution and the addition of zinc element to the positive electrode plate as a compound powder of zinc element enables appropriate dispersion of tungsten element and zinc element. Therefore, it is possible to obtain a nickel-metal hydride storage battery having both battery characteristics of an excellent capacity retention rate and low battery resistance.
　次に、図１を参照して、正極板の組成及び電解液の組成に基づいて上記評価式（１）に従って算出される指標値と、ニッケル水素蓄電池の保管後の容量維持率との関係、及び電池抵抗との関係について説明する。 Next, referring to FIG. 1, the relationship between the index value calculated according to the evaluation formula (1) based on the composition of the positive electrode plate and the composition of the electrolytic solution, and the capacity retention rate after storage of the nickel-metal hydride storage battery, The relationship with the battery resistance will be described.
　［保管後の容量維持率］
　本実施形態の「保管後の容量維持率」は、保管（保存）前に「２５℃」の環境下でＳＯＣ＝６０％に充電した蓄電池を、「４５℃」の環境下で一週間保管（保存）し、その後、「２５℃」の環境下で放電した保管（保存）後のＳＯＣ（保管後の残存ＳＯＣ）に基づき算出される数値であり、次式（４）より算出される。 [Capacity maintenance ratio after storage]
The “capacity maintenance ratio after storage” in this embodiment is a storage battery charged to SOC = 60% in an environment of “25 ° C.” before storage (storage), and stored in an environment of “45 ° C.” for one week ( This is a numerical value calculated based on the SOC after storage (storage) discharged in an environment of “25 ° C.” (residual SOC after storage), and is calculated from the following equation (4).
　保管後の容量維持率［％］＝保管後の残存ＳＯＣ［％］／６０［％］×１００・・・（４）
ここで、ＳＯＣ（エスオーシー：Ｓｔａｔｅ　Ｏｆ　Ｃｈａｒｇｅ）は、蓄電池の残存容量を示し、完全充電された蓄電池から放電された電気量を除いた割合を示す。 Capacity retention rate after storage [%] = Residual SOC after storage [%] / 60 [%] × 100 (4)
Here, SOC (State Of Charge) indicates the remaining capacity of the storage battery, and indicates a ratio excluding the amount of electricity discharged from the fully charged storage battery.
　なお蓄電池は、例えば、保管前に充電電流４Ａで４．２Ａｈまで充電を行うことでＳＯＣ＝６０％に調整される。また蓄電池は、保管後に２Ａの放電電流を放電終止電圧（１Ｖ）になるまで放電されたとき、その放電電流と時間との積から算出される容量が残存ＳＯＣとして求められる。なお、一般的に、保管後の残存ＳＯＣが大きいほど、つまり保管後の容量維持率が高い程、電池特性が優れている電池であると判断される。 Note that the storage battery is adjusted to SOC = 60%, for example, by charging up to 4.2 Ah with a charging current of 4 A before storage. Further, when the storage battery is discharged after storage until the discharge current of 2A reaches the end-of-discharge voltage (1 V), the capacity calculated from the product of the discharge current and time is obtained as the remaining SOC. In general, it is determined that the battery has better battery characteristics as the residual SOC after storage is larger, that is, as the capacity retention rate after storage is higher.
　［電池抵抗］
　本実施形態の「電池抵抗」（ＤＣ－ＩＲ）は、環境温度が「２５℃」の下で、ニッケル水素蓄電池に所定の充電容量分（ＳＯＣ＝６０％）だけ充電した後、該蓄電池に対して短時間の充放電を繰り返し、充放電の際に印加した電流と測定された電圧との関係から算出される。なお一般に、蓄電池は、内部抵抗（ＩＲ）が小さいほど優れていると判断される。 [Battery resistance]
The “battery resistance” (DC-IR) of the present embodiment is obtained by charging a nickel-metal hydride storage battery for a predetermined charging capacity (SOC = 60%) under an environmental temperature of “25 ° C.” Thus, charging / discharging for a short time is repeated, and it is calculated from the relationship between the current applied during charging / discharging and the measured voltage. In general, it is determined that the storage battery is more excellent as the internal resistance (IR) is smaller.
　具体的には、以下のように「電池抵抗」が測定される。まず、常温の下で蓄電池に、その蓄電量（ＳＯＣ）が６０％になるまで充電を実施する。その後、例えば、１０Ａで１０秒間放電した際の電圧降下（ΔＶ）から、ニッケル水素蓄電池の直流の内部抵抗（ＤＣ－ＩＲ）を「ΔＶ／１０Ａ」により算出する。 Specifically, “battery resistance” is measured as follows. First, the storage battery is charged at room temperature until the amount of stored electricity (SOC) reaches 60%. Thereafter, for example, the direct current internal resistance (DC-IR) of the nickel-metal hydride storage battery is calculated from “ΔV / 10A” from the voltage drop (ΔV) when discharged at 10 A for 10 seconds.
　［指標値と保管後の容量維持率及び電池抵抗の関係］
　図１に示すように、評価式（１）から算出される指標値が「０．０００」～「０．２２２」の範囲となる正極板と電解液とをニッケル水素蓄電池に利用した場合について、指標値ごとに、保管後の容量維持率及び電池抵抗を得た。但し、指標値が「０．０００」のとき、タングステン元素及び亜鉛元素の合算重量中での重量％はいずれも「０」としている。以下に、評価式（１）から算出される指標値ごとに、対応する保管後の容量維持率の値、及び電池抵抗の値を記載する。なお、説明の便宜上、保管後の容量維持率の値を「維持率値」、電池抵抗の値を「抵抗値」と記載する。
・指標値「０．０００」：維持率値Ｃ０１「７７．５」、抵抗値Ｒ０１「２．８０」
・指標値「０．０２０」：維持率値Ｃ０２「８３．５」、抵抗値Ｒ０２「２．８５」
・指標値「０．０３７」：維持率値Ｃ０３「８２．２」、抵抗値Ｒ０３「２．８６」
・指標値「０．０５６」：維持率値Ｃ０４「８３．８」、抵抗値Ｒ０４「２．８８」
・指標値「０．０６３」：維持率値Ｃ０５「８４．８」、抵抗値Ｒ０５「２．９２」
・指標値「０．０７４」：維持率値Ｃ０６「８３．２」、抵抗値Ｒ０６「２．８８」
・指標値「０．１００」：維持率値Ｃ０７「８５．５」、抵抗値Ｒ０７「２．９３」
・指標値「０．１１１」：維持率値Ｃ０８「８６．１」、抵抗値Ｒ０８「２．９５」
・指標値「０．１３３」：維持率値Ｃ０９「８４．８」、抵抗値Ｒ０９「３．０１」
・指標値「０．１４８」：維持率値Ｃ１０「８６．７」、抵抗値Ｒ１０「２．９７」
・指標値「０．１６０」：維持率値Ｃ１１「８５．５」、抵抗値Ｒ１１「３．００」
・指標値「０．１８５」：維持率値Ｃ１２「８７．０」、抵抗値Ｒ１２「３．０５」
・指標値「０．２２２」：維持率値Ｃ１３「８５．３」、抵抗値Ｒ１３「３．０５」
　こうして得られた保管後の容量維持率によれば、維持率値Ｃ０１～Ｃ１３は、指標値が「０．０００」から「０．２５０」までの間（範囲Ａ１～Ａ４）において、グラフＬＣのように変化する。つまり、保管後の容量維持率は、指標値が小さければ低く（悪く）なり、指標値が大きければ高く（良く）なる傾向を有している。詳述すると、保管後の容量維持率は、指標値が「０．０００」から「０．０２」までの範囲Ａ１では、その値の上昇幅が比較的大きい一方、指標値が「０．０２」から「０．２２２」までの範囲Ａ２～Ａ４では、その値の上昇幅が比較的小さい傾向を有していることが明らかになった。つまり、保管後の容量維持率は、その値が大きく上昇した後の範囲となる、指標値が「０．０２」以上の範囲Ａ２～Ａ４で、指標値が「０．０２」未満の範囲Ａ１のときの値に比べて、相対的に良好な値となる。また、保管後の容量維持率は、指標値が「０．０２」以上の範囲Ａ２～Ａ４であっても、指標値が大きくなるにつれ、その値の上昇幅が小さくなる傾向にある。つまり保管後の容量維持率の値の上昇幅は、指標値が「０．１１」未満の範囲Ａ２に比較して、指標値が「０．１１」以上の範囲Ａ３，Ａ４において小さくなり、指標値が「０．１６」以上の範囲Ａ４では、より一層小さくなる。範囲Ａ４では、容量維持率の値は、ほとんど上昇しない。 [Relationship between index value, capacity retention rate after storage and battery resistance]
As shown in FIG. 1, when a positive electrode plate and an electrolytic solution whose index value calculated from the evaluation formula (1) is in the range of “0.000” to “0.222” are used for a nickel metal hydride storage battery, For each index value, the capacity retention rate and battery resistance after storage were obtained. However, when the index value is “0.000”, the weight% in the combined weight of the tungsten element and the zinc element is both “0”. Below, for each index value calculated from the evaluation formula (1), the value of the capacity retention rate after storage and the value of the battery resistance are described. For convenience of explanation, the value of the capacity maintenance ratio after storage is described as “maintenance ratio value”, and the value of battery resistance is described as “resistance value”.
Index value “0.000”: maintenance rate value C01 “77.5”, resistance value R01 “2.80”
Index value “0.020”: maintenance rate value C02 “83.5”, resistance value R02 “2.85”
Index value “0.037”: maintenance rate value C03 “82.2”, resistance value R03 “2.86”
Index value “0.056”: maintenance rate value C04 “83.8”, resistance value R04 “2.88”
Index value “0.063”: maintenance rate value C05 “84.8”, resistance value R05 “2.92”
Index value “0.074”: maintenance ratio value C06 “83.2”, resistance value R06 “2.88”
Index value “0.100”: maintenance rate value C07 “85.5”, resistance value R07 “2.93”
Index value “0.111”: maintenance rate value C08 “86.1”, resistance value R08 “2.95”
Index value “0.133”: maintenance rate value C09 “84.8”, resistance value R09 “3.01”
Index value “0.148”: maintenance ratio value C10 “86.7”, resistance value R10 “2.97”
Index value “0.160”: maintenance ratio value C11 “85.5”, resistance value R11 “3.00”
Index value “0.185”: maintenance rate value C12 “87.0”, resistance value R12 “3.05”
Index value “0.222”: maintenance ratio value C13 “85.3”, resistance value R13 “3.05”
According to the capacity retention ratio after storage thus obtained, the retention ratio values C01 to C13 are shown in the graph LC between the index values “0.000” and “0.250” (range A1 to A4). To change. That is, the capacity maintenance rate after storage tends to be low (bad) when the index value is small, and high (good) when the index value is large. More specifically, the capacity retention rate after storage is relatively large in the range A1 of the index value from “0.000” to “0.02”, while the index value is “0.02”. In the range from A2 to A4 from “0.222” to “0.222”, it has been clarified that the increase in the value tends to be relatively small. In other words, the capacity retention rate after storage is the range after the value has greatly increased, the range A2 to A4 where the index value is “0.02” or more, and the range A1 where the index value is less than “0.02”. It is a relatively good value compared to the value at. In addition, the capacity maintenance rate after storage tends to decrease as the index value increases even if the index value is in the range A2 to A4 of “0.02” or more. That is, the increase in the value of the capacity maintenance rate after storage is smaller in the ranges A3 and A4 where the index value is “0.11” or more than in the range A2 where the index value is less than “0.11”. In the range A4 where the value is “0.16” or more, it becomes even smaller. In the range A4, the capacity retention rate hardly increases.
　また、上述した算出によって得られた電池抵抗によれば、抵抗値Ｒ０１～Ｒ１３は、指標値が「０．０００」から「０．２５０」までの間（範囲Ａ１～Ａ４）において、グラフＬＲのように変化する。つまり、電池抵抗は、指標値が小さければ小さく（良く）なり、指標値が大きければ大きく（悪く）なる傾向を有している。詳述すると、電池抵抗は、指標値が「０．０００」から「０．２５０」までの範囲Ａ１～Ａ４では、指標値が大きくなることに応じて、その値が略一定の上昇幅で大きくなる傾向を有している。一般に、車両に搭載されるニッケル水素蓄電池は、大電流を流す必要があるので、その使用環境にかかわらず、その電池抵抗の値を小さく維持する必要がある。つまり、電池抵抗の値は、小さい方が好ましく、特に車載されるニッケル水素蓄電池の電気抵抗の値としては、エネルギーロスの関係から３．０［ｍΩ］を超えることは好ましくない。つまり、電池抵抗の値が３．０［ｍΩ］を超えるおそれが生じる、指標値が「０．１６」付近よりも大きい範囲Ａ４となることは好ましくない。 Further, according to the battery resistance obtained by the above calculation, the resistance values R01 to R13 are shown in the graph LR when the index value is between “0.000” and “0.250” (range A1 to A4). To change. That is, the battery resistance tends to be small (good) when the index value is small and large (bad) when the index value is large. More specifically, the battery resistance increases in a substantially constant increase range in accordance with the increase of the index value in the range A1 to A4 in which the index value is “0.000” to “0.250”. Tend to be. In general, a nickel-metal hydride storage battery mounted on a vehicle needs to pass a large current, so that the battery resistance value needs to be kept small regardless of the use environment. That is, the value of the battery resistance is preferably small, and it is not preferable that the electric resistance value of the nickel-metal hydride storage battery mounted on the vehicle exceeds 3.0 [mΩ] because of the energy loss. That is, it is not preferable that the index value is in a range A4 larger than the vicinity of “0.16”, which may cause the battery resistance value to exceed 3.0 [mΩ].
　また、保管後の容量維持率と電池抵抗との関係によれば、保管後の容量維持率の値の上昇幅は指標値が増加することに伴って小さくなる一方、電池抵抗の値の上昇幅は指標値が増加することに伴って略一定の幅で上昇する。このため、指標値が大きくなるにつれて、保管後の容量維持率の値は上昇が鈍化する一方、電池抵抗は定常的に上昇することとなる。このことから、指標値が大きくなるにつれて、保管後の容量維持率の値が上昇する（容量維持率が良くなる）ことにより得られる電池特性の向上に比べて、電池抵抗の値が増加する（電池抵抗が悪くなる）ことによる電池特性の劣化が相対的に大きくなってしまう。つまり保管後の容量維持率と電池抵抗との関係によれば、好適な電池特性を維持することのできる指標値として、保管後の容量維持率の値がほとんど上昇しなくなる「０．１６」程度以下の範囲Ａ２，Ａ３が好ましい。またより好ましくは、保管後の容量維持率の値の増加が小さくなる「０．１１」程度以下の範囲Ａ２が好ましい。 Also, according to the relationship between the capacity retention rate after storage and the battery resistance, the increase in the value of the capacity maintenance rate after storage decreases as the index value increases, while the increase in the value of the battery resistance increases. Increases at a substantially constant rate as the index value increases. For this reason, as the index value increases, the value of the capacity maintenance rate after storage slows down, while the battery resistance constantly increases. From this, as the index value increases, the value of the battery resistance increases as compared to the improvement in battery characteristics obtained by increasing the capacity retention ratio after storage (capacity retention ratio improves) ( The deterioration of the battery characteristics due to the deterioration of the battery resistance becomes relatively large. In other words, according to the relationship between the capacity retention rate after storage and the battery resistance, the value of the capacity retention rate after storage hardly increases as an index value that can maintain suitable battery characteristics, which is about “0.16”. The following ranges A2 and A3 are preferable. More preferably, the range A2 of about “0.11” or less in which the increase in the value of the capacity retention rate after storage is small is preferable.
　これらのことから、好ましい電池特性を維持する指標値の下限は、保管後の容量維持率が急激に低下する前、つまり「０．０２」程度が好ましい。また、好ましい電池特性を維持する指標値の上限としては、保管後の容量維持率がほとんど上昇しなくなる「０．１６」程度以下が好ましく、より好ましくは、保管後の容量維持率の値の増加が少なくなる「０．１１」程度以下が好ましい。つまり、図１に示すように、ニッケル水素蓄電池に保存に優れた容量維持率と低い電池抵抗との２つの電池特性を両立させる、つまり好ましい電池特性を維持させる正極板及び電解液は、その指標値が「０．０２」から「０．１６」までの範囲Ａ２，Ａ３であることが好ましい。また、上述の好ましい電池特性を維持する正極板及び電解液は、その指標値が「０．０２」から「０．１１」までの範囲Ａ２であることがより好ましい。 For these reasons, the lower limit of the index value for maintaining preferable battery characteristics is preferably before the capacity maintenance rate after storage suddenly decreases, that is, about “0.02”. In addition, the upper limit of the index value for maintaining preferable battery characteristics is preferably about 0.16 or less at which the capacity retention rate after storage hardly increases, and more preferably, the value of the capacity maintenance rate after storage is increased. Is preferably about 0.11 or less. That is, as shown in FIG. 1, the positive electrode plate and the electrolyte solution that make the nickel hydride storage battery have both the two battery characteristics of the capacity maintenance rate excellent in storage and the low battery resistance, that is, the preferable battery characteristics are maintained. It is preferable that the value is in the range A2, A3 from “0.02” to “0.16”. In addition, the positive electrode plate and the electrolytic solution that maintain the preferable battery characteristics are more preferably in the range A2 from “0.02” to “0.11”.
　よって、保存に優れた容量維持率と低い電池抵抗との２つの特性が両立する電池特性を得られる正極板及び電解液は、式（２）に示すように、その指標値が「０．０２」以上、かつ、「０．１６」以下の範囲Ａ２，Ａ３であることが好ましいことが明らかになった。また、より好ましい電池特性を得られる正極板及び電解液は、式（３）に示すように、その指標値が「０．０２」以上、かつ、「０．１１」以下の範囲Ａ２であることが好ましいことが明らかになった。 Therefore, the positive electrode plate and the electrolytic solution that can obtain the battery characteristics in which the two characteristics of the capacity retention rate excellent in storage and the low battery resistance are compatible have an index value of “0.02” as shown in Equation (2). It has become clear that it is preferable to be in the range A2 and A3 of “0.16” or less. Further, the positive electrode plate and the electrolytic solution that can obtain more preferable battery characteristics have an index value in the range A2 of “0.02” or more and “0.11” or less as shown in the formula (3). Was found to be preferable.
　ところで、上述したように、従来から、電解液への添加物を変更することにより、ニッケル水素蓄電池の特性を変化させることができることは知られている。近年、ハイブリッド自動車の利用環境が様々な環境に拡大することに伴い、その拡大する使用環境条件及び保存環境条件においても性能が良好に維持されるニッケル水素蓄電池が望まれるようになってきた。しかし、こうした性能を良好に維持させることに好適な電解液の構成、及び正極板の構成については明らかではなかった。また、車両に搭載されるニッケル水素蓄電池は、大電流を流す必要があるので、その使用環境にかかわらず、その電池抵抗の値を小さく維持する必要もある。また、一般に、電解液にタングステン元素を、又は、正極板に亜鉛元素を添加することで、保管後の容量維持率が高くなる（良くなる）一方、電池抵抗が大きくなる（悪化する）。他方、電解液にカリウム元素を添加することで、電池抵抗が小さくなる（良くなる）一方、保管後の容量維持率が低くなる（悪化する）。そのため、タングステン元素、カリウム元素、及び亜鉛元素の添加量に関する規定が存在しない状況においては、良好な電池性能が維持されるように、これら添加物を電解液に添加したり、正極板に添加したりすることは困難であった。 Incidentally, as described above, it has been conventionally known that the characteristics of the nickel-metal hydride storage battery can be changed by changing the additive to the electrolytic solution. In recent years, as the usage environment of hybrid vehicles has expanded to various environments, nickel-metal hydride storage batteries that have good performance under the expanding usage environment conditions and storage environment conditions have been desired. However, the configuration of the electrolytic solution suitable for maintaining such performance satisfactorily and the configuration of the positive electrode plate were not clear. Moreover, since the nickel metal hydride storage battery mounted in a vehicle needs to flow a large current, it is necessary to keep the value of the battery resistance small regardless of the use environment. In general, adding tungsten element to the electrolytic solution or zinc element to the positive electrode plate increases (improves) the capacity retention ratio after storage, while increasing (deteriorates) battery resistance. On the other hand, by adding potassium element to the electrolytic solution, the battery resistance is decreased (improved), while the capacity retention rate after storage is decreased (deteriorated). Therefore, in the situation where there are no provisions regarding the addition amount of tungsten element, potassium element, and zinc element, these additives are added to the electrolyte solution or added to the positive electrode plate so that good battery performance is maintained. It was difficult to do.
　本実施形態では、タングステン元素、カリウム元素、及び亜鉛元素の添加量に関する評価式（１）と、その評価式（１）より算出される指標値の適切な範囲を規定した。これにより、拡大される使用環境下及び保存環境下において良好な電池特性を有するニッケル水素蓄電池を得るための正極板及び電解液が得られる。こうしたニッケル水素蓄電池では、具体的には、保管後の容量維持率が高く維持されるとともに、低い電池抵抗が維持されて使用時のエネルギーロスが低く抑えられる。 In this embodiment, the evaluation formula (1) regarding the addition amount of tungsten element, potassium element, and zinc element and the appropriate range of the index value calculated from the evaluation formula (1) are defined. Thereby, the positive electrode plate and electrolyte solution for obtaining the nickel hydride storage battery which has a favorable battery characteristic in the use environment expanded and a storage environment are obtained. Specifically, in such a nickel metal hydride storage battery, the capacity maintenance rate after storage is maintained high, and low battery resistance is maintained, so that energy loss during use is kept low.
　以上説明したように、本実施形態のニッケル水素蓄電池によれば、以下に列記するような利点が得られる。 As described above, according to the nickel-metal hydride storage battery of this embodiment, the advantages listed below can be obtained.
　（１）ニッケル水素蓄電池では、電解液中のカリウム元素は、電池抵抗を低下させるものの保管後の容量維持率を悪化させる。一方、同電解液中のタングステン元素や正極板の化合物粉末中の亜鉛元素は、保管後の容量維持率を良好にするものの電池抵抗を上昇させる傾向にある。 (1) In nickel-metal hydride storage batteries, potassium element in the electrolyte deteriorates the capacity retention rate after storage, although it reduces battery resistance. On the other hand, the tungsten element in the electrolytic solution and the zinc element in the compound powder of the positive electrode plate tend to increase the battery resistance although the capacity retention rate after storage is good.
　本実施形態によれば、ニッケル水素蓄電池として、高負荷での使用に優れた低い電池抵抗と、長期間の保存に優れた容量維持率との２つの特性が両立する蓄電池が得られる。これにより、拡大される使用環境下及び保存環境下においても良好な性能の維持されるニッケル水素蓄電池が提供される。 According to the present embodiment, a nickel-metal hydride storage battery having a low battery resistance excellent in use at a high load and a capacity retention rate excellent in long-term storage can be obtained. This provides a nickel-metal hydride storage battery that maintains good performance even under expanded use and storage environments.
　また、タングステン元素は電解液に溶けやすいので、電解液に添加されることで正極板界面へ高分散される。一方、亜鉛元素は電解液に溶けにくいので、正極活物質を含むペーストへの化合物粉末として添加されることよって正極板へ適切に分散される。つまり、タングステン元素の電解液への添加と、亜鉛元素の化合物粉末としての正極板への添加とにより、タングステン元素と亜鉛元素とを適切に分散させることが可能になる。 Also, since tungsten element is easily dissolved in the electrolytic solution, it is highly dispersed to the positive electrode interface when added to the electrolytic solution. On the other hand, since zinc element is hardly dissolved in the electrolytic solution, it is appropriately dispersed in the positive electrode plate by being added as a compound powder to the paste containing the positive electrode active material. That is, it is possible to appropriately disperse the tungsten element and the zinc element by adding the tungsten element to the electrolytic solution and adding the zinc element to the positive electrode plate as the compound powder of the zinc element.
　（２）電解液の重量と正極板に化合物粉末として含まれている亜鉛元素の重量とを合算した重量中のタングステン元素の含有重量％を適切な割合にすることで、正極活物質の価数低下変化［ＮｉＯＯＨ→Ｎｉ（ＯＨ）２］が良好に抑制されるとともに、過剰な添加が生じさせる電池抵抗が大きくなることを抑えることもできる。 (2) The valence of the positive electrode active material is adjusted by adjusting the content percentage by weight of the tungsten element in the total weight of the electrolyte solution and the zinc element contained in the positive electrode plate as compound powder. While the decrease [NiOOH → Ni (OH) 2 ] is satisfactorily suppressed, it is also possible to suppress an increase in battery resistance caused by excessive addition.
　（３）長期間の保存に優れた容量維持率と低い電池抵抗との２つの特性がより良好に両立するニッケル水素蓄電池が得られる。 (3) A nickel-metal hydride storage battery in which two characteristics of a capacity retention rate excellent in long-term storage and a low battery resistance are better compatible can be obtained.
　（４）使用環境や保存環境が様々である車両に搭載された蓄電池においても、その性能が好適に維持される。 (4) Even in a storage battery mounted on a vehicle having various usage and storage environments, the performance is suitably maintained.
　（その他の実施形態）
　なお上記実施形態は、以下の態様で実施することもできる。 (Other embodiments)
In addition, the said embodiment can also be implemented with the following aspects.
　・上記実施形態の重量％は、質量％であってもよい。 -The weight% of the said embodiment may be the mass%.
　・上記実施形態では、樹脂製の収納容器２０について例示しているが、収納容器の材料はこれに限らない。収納容器は、電槽として利用できるのであれば、金属製などの樹脂以外の材料から製作されてもよい。これにより、ニッケル水素蓄電池の設計自由度の拡大が図られる。 In the above embodiment, the resin storage container 20 is illustrated, but the material of the storage container is not limited to this. The storage container may be made of a material other than a resin such as a metal as long as it can be used as a battery case. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
　・上記実施形態では、複数の負極板１２と複数の正極板とがセパレータを介して交互に積層された電極群１０について例示している。また、例として、１３枚の負極板と１２枚の正極板とを備えた電極具について示している。しかしこれに限らず、電極群が適切に構成されるのであれば、負極板は１３枚より少なくてもよいし、１３枚より多くてもよい。また、正極板は１２枚より少なくてもよいし、１２枚より多くてもよい。これにより、ニッケル水素蓄電池の適用範囲の拡大が図られる。 In the above embodiment, the electrode group 10 is illustrated in which a plurality of negative plates 12 and a plurality of positive plates are alternately stacked via separators. As an example, an electrode device including 13 negative plates and 12 positive plates is shown. However, the present invention is not limited thereto, and the number of negative electrode plates may be less than 13 or more than 13 as long as the electrode group is appropriately configured. Further, the number of positive electrode plates may be less than 12, or more than 12. Thereby, the expansion of the application range of a nickel metal hydride storage battery is achieved.
　・上記実施形態では、パンチングメタルなどの金属多孔体からなる基板に水素吸蔵合金粉末を塗布して製作された負極板１２について例示している。しかしこれに限らず、負極板として機能するのであれば、負極板はどのように製作されてもよい。これにより、ニッケル水素蓄電池の設計自由度の拡大が図られる。 In the above embodiment, the negative electrode plate 12 manufactured by applying a hydrogen storage alloy powder to a substrate made of a porous metal such as punching metal is illustrated. However, the present invention is not limited to this, and the negative electrode plate may be manufactured in any way as long as it functions as a negative electrode plate. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
　・上記実施形態では、発泡ニッケル基板などの金属多孔体からなる基板に水酸化ニッケル粒子を含む活物質を充填して製作された正極板１１について例示している。しかしこれに限らず、正極板として機能するとともに亜鉛元素の添加ができるのであれば、正極板はどのように製作されてもよい。例えば、焼結基板などの金属多孔体からなる基板に化学反応を用いて活物質を充填して正極板が製作されてもよい。これにより、ニッケル水素蓄電池の設計自由度の拡大が図られる。 In the above embodiment, the positive electrode plate 11 manufactured by filling a substrate made of a metal porous body such as a foamed nickel substrate with an active material containing nickel hydroxide particles is illustrated. However, the present invention is not limited to this, and the positive electrode plate may be manufactured in any way as long as it functions as a positive electrode plate and zinc element can be added. For example, a positive electrode plate may be manufactured by filling a substrate made of a metal porous body such as a sintered substrate with a chemical reaction using an active material. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
　・上記実施形態では、正極活物質粉末、酸化イットリウム粉末、酸化亜鉛粉末、金属コバルト、及び水が含まれるペーストについて例示した。しかしこれに限らず、適切な正極板を得ることができるのであれば、ペーストには、酸化イットリウム粉末及び金属コバルトの少なくとも一方が含まれていなくてもよい。これにより、ニッケル水素蓄電池の設計自由度の拡大が図られる。 In the above embodiment, the paste including the positive electrode active material powder, the yttrium oxide powder, the zinc oxide powder, the metallic cobalt, and water is illustrated. However, the present invention is not limited to this, and the paste may not contain at least one of yttrium oxide powder and metallic cobalt as long as an appropriate positive electrode plate can be obtained. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
　・上記実施形態では、耐アルカリ性樹脂の不織布であるセパレータ１３について例示した。しかしこれに限らず、セパレータは、ニッケル水素蓄電池に対応する素材から形成されていればよい。これにより、ニッケル水素蓄電池の設計自由度の拡大が図られる。 In the above embodiment, the separator 13 which is a non-woven fabric of alkali resistant resin is illustrated. However, the present invention is not limited to this, and the separator may be formed from a material corresponding to the nickel metal hydride storage battery. Thereby, expansion of the design freedom of a nickel metal hydride storage battery is achieved.
　・上記実施形態では、電気自動車やハイブリッド自動車の電源として用いられるニッケル水素蓄電池１について例示した。しかしニッケル水素蓄電池は、電源が必要な自動車以外の電源として用いられてもよい。例えば、自動車以外の電源としては、鉄道、船舶、航空機やロボットなどの移動体や、情報処理装置などの電気製品の電源などが挙げられる。これにより、ニッケル水素蓄電池の適用範囲の拡大が図られる。 In the above embodiment, the nickel metal hydride storage battery 1 used as a power source for an electric vehicle or a hybrid vehicle is exemplified. However, the nickel metal hydride storage battery may be used as a power source other than an automobile that requires a power source. For example, power sources other than automobiles include moving bodies such as railways, ships, airplanes, and robots, and power supplies for electrical products such as information processing apparatuses. Thereby, the expansion of the application range of a nickel metal hydride storage battery is achieved.

Claims (3)

  1. 　車両に搭載されるニッケル水素蓄電池であって、
    　水酸化ニッケルを主成分とする活物質を含み、かつ、亜鉛元素を含む化合物粉末を前記活物質に混合された態様で含む正極板と、水素吸蔵合金を含む負極板と、前記正極板と前記負極板との間に配置されるセパレータとを備える電極群と、
    　タングステン元素及びカリウム元素を含む電解液と、
    　前記電極群と前記電解液とを封入する収納容器と、を備え、
    　前記電解液の重量と前記亜鉛元素の重量とを合せた重量を基準とした前記各元素の重量％の関係が、
    　０．０２≦（タングステン元素の重量％＋亜鉛元素の重量％）／（カリウム元素の重量％）≦０．１６
    　である、ニッケル水素蓄電池。     A nickel metal hydride storage battery mounted on a vehicle,
    A positive electrode plate containing an active material mainly composed of nickel hydroxide and containing a compound powder containing zinc element in a mixed state with the active material, a negative electrode plate containing a hydrogen storage alloy, the positive electrode plate, An electrode group comprising a separator disposed between the negative electrode plate,
    An electrolyte containing tungsten and potassium elements;
    A storage container that encloses the electrode group and the electrolytic solution;
    The relationship of the weight percent of each element based on the total weight of the electrolyte solution and the zinc element,
    0.02 ≦ (wt% of tungsten element + wt% of zinc element) / (wt% of potassium element) ≦ 0.16
    A nickel metal hydride storage battery.
  2. 　前記タングステン元素の重量％が、１．１重量％以上、かつ、２１．８重量％以下である
    　請求項１に記載のニッケル水素蓄電池。     The nickel metal hydride storage battery according to claim 1, wherein a weight percent of the tungsten element is 1.1 wt% or more and 21.8 wt% or less.
  3. 　前記タングステン元素、カリウム元素、及び亜鉛元素、のそれぞれの重量％の関係が、
    　０．０２≦（タングステン元素の重量％＋亜鉛元素の重量％）／（カリウム元素の重量％）≦０．１１
    　である、請求項１又は２に記載のニッケル水素蓄電池。     The weight% relationship between the tungsten element, the potassium element, and the zinc element,
    0.02 ≦ (wt% of tungsten element + wt% of zinc element) / (wt% of potassium element) ≦ 0.11
    The nickel-metal hydride storage battery according to claim 1 or 2, wherein
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