JP2013178883A - Alkaline storage battery and alkaline storage battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure excellent charging efficiency in the initial state of a battery, while enhancing the durability life of partial charge/discharge as compared with prior art.SOLUTION: In the alkaline storage battery including a positive electrode employing nickel hydroxide as a main positive electrode active material, a negative electrode and an alkaline electrolyte, zinc is added to the nickel hydroxide becoming the main positive electrode active material of the positive electrode. For the nickel mass in the positive electrode active material, 3-8 mass% of zinc is added and any one kind or more of compound, selected from a tungsten compound, a molybdenum compound and a niobium compound, is added to the alkaline electrolyte. Mass of the metal element in 1 g of the alkaline electrolyte is 5-34 mg, and the amount of alkaline electrolyte per unit positive electrode capacity of the alkaline storage battery is 2.4-3.3 g/Ah.

Description

The present invention relates to an alkaline storage battery and a storage battery system using the same.

In recent years, alkaline storage batteries for idling stop vehicles have been studied in addition to hybrid vehicle applications. In idling stop automobile applications, it is necessary to lower the voltage of the system (reducing the number of cells per system) from the viewpoint of compatibility with lead-acid batteries. In addition, since it is used in a high temperature environment, further improvement in charging efficiency characteristics at a high temperature is required.

Generally, an alkaline storage battery uses a nickel positive electrode in which a conductive substrate is filled with nickel hydroxide as an active material. In the alkaline storage battery including the positive electrode, zinc is added as a solid solution to the positive electrode active material for the purpose of suppressing the expansion of the positive electrode that occurs during overcharge. However, in a vehicle application that does not assume use up to the overcharge region, a method of reducing the amount of zinc that is an electrical resistance component in the positive electrode active material is being studied. (Patent Document 1)

JP 2010-231949 A

In alkaline storage batteries used for vehicle applications such as hybrid vehicles (HEV) and electric vehicles (PEV) where partial charge / discharge is performed, the charge efficiency declines due to the memory effect as a factor of output degradation and capacity degradation due to partial charge / discharge It has been known.
As a countermeasure against this, the present inventor has confirmed that the addition of at least one compound selected from a tungsten compound, a niobium compound, and a molybdenum compound in the electrolytic solution is effective (Japanese Patent Application No. 2011-259800). ).

However, even when the above compound is added, a problem has been found that sufficient charging efficiency cannot be obtained even in a higher temperature environment (60 ° C. to 80 ° C.). In an in-vehicle application, a battery may be used in an environment of 60 ° C. or more near an engine room, and thus excellent charging efficiency characteristics are required in a high temperature environment.

The present invention has been made in view of the above circumstances, and in an alkaline storage battery comprising a positive electrode and a negative electrode having nickel hydroxide as a main positive electrode active material, and an alkaline electrolyte,
In the positive electrode, zinc is added to nickel hydroxide as a main positive electrode active material, and the amount of zinc added is 3% by mass or more and 8% by mass or less with respect to the mass of nickel in the positive electrode active material. There,
One or more compounds selected from a tungsten compound, a molybdenum compound, and a niobium compound are added to the alkaline electrolyte, and the mass of the metal element in 1 g of the alkaline electrolyte is 5 mg or more and 34 mg. The amount of alkaline electrolyte per unit positive electrode capacity of the alkaline storage battery is 2.4 g / Ah or more and 3.3 g / Ah or less.

By doing as mentioned above, it is possible to obtain good charging efficiency in the initial state of the battery and to improve the durable life of partial charge / discharge.
For example, when tungsten is deposited on the positive electrode, the charging efficiency is improved. However, if the tungsten concentration in the electrolytic solution is not appropriate, the tungsten deposition is not uniform, and the expected charging efficiency cannot be obtained. This effect becomes more prominent in high temperature environments (60 ° C. to 80 ° C.).
It has been found that in order to deposit tungsten uniformly, it is effective that the amount of tungsten per gram of the electrolyte is 5 mg or more and 34 mg or less.
Moreover, even if the amount of tungsten per electrolytic solution is added, the amount of electrolytic solution per positive electrode capacity needs to be 2.4 g / Ah or more and 3.3 g / Ah or less in order to obtain sufficient characteristics.

By satisfying both the above conditions, a necessary amount of tungsten can be uniformly deposited on the surface of the positive electrode, and charging efficiency in a high temperature environment (60 ° C. to 80 ° C.) can be improved.
Further, it is known that the amount of zinc in the positive electrode greatly changes the charging efficiency, but the amount of zinc at which good charging efficiency can be obtained by the above-mentioned addition of tungsten is 3 mass relative to the mass of nickel in the positive electrode active material. % To 8% by mass.
The effect of improving the charging efficiency can be confirmed even in the initial state of the battery, but the effect becomes more apparent after partial charge / discharge.
In addition, in the alkaline storage battery of this invention, since variation in high-temperature charging efficiency is suppressed, it is desirable to use it in parallel with alkaline storage batteries.

It is sectional drawing which shows typically the alkaline storage battery used for the alkaline storage battery system of this invention and a comparative example. It is the schematic which shows the structure of the alkaline storage battery system of this invention.

Next, embodiments of the present invention will be described in detail below. However, the present invention is not limited to these embodiments, and can be appropriately modified and implemented without departing from the scope of the present invention.

1. Nickel positive electrode The nickel positive electrode 11 of the present invention is formed by filling a predetermined amount of nickel hydroxide and zinc hydroxide in the pores of a nickel sintered substrate serving as a substrate.
In this case, the nickel sintered substrate is first prepared by mixing and kneading, for example, nickel powder with methyl cellulose (MC) as a thickener, polymer hollow microspheres (for example, having a pore diameter of 60 μm), and water. A nickel slurry is prepared. Next, after applying nickel slurry on both sides of the punching metal made of nickel-plated steel plate, it is heated at 1000 ° C. in a reducing atmosphere, and the applied thickener and polymer hollow microspheres disappear. It is produced by sintering nickel powders.
Then, after impregnating the obtained nickel sintered substrate with the following impregnating liquid, the alkali treatment with the alkali treatment liquid is repeated a predetermined number of times, whereby a predetermined amount of nickel hydroxide and water are placed in the pores of the nickel sintered substrate. Filled with zinc oxide. Then, the nickel positive electrode with which the positive electrode active material was filled is produced by cutting to a predetermined dimension. Here, it formed so that the ratio of the zinc mass of zinc hydroxide might be 1 mass% to 8 mass% with respect to the nickel mass of the nickel hydroxide used as a positive electrode active material.
In this case, as the impregnation liquid, a solution in which nickel nitrate and zinc nitrate are adjusted to a predetermined molar ratio is used, and as the alkali treatment liquid, a sodium hydroxide (NaOH) aqueous solution having a specific gravity of 1.3 is used. Note that an impregnation liquid to which cobalt nitrate, yttrium nitrate, ytterbium nitrate, or the like is added may be used for the purpose of improving high temperature characteristics.
Then, the nickel sintered substrate is immersed in the impregnating solution, the impregnating solution is impregnated in the pores of the nickel sintered substrate, dried, and then immersed in the alkali processing solution to perform the alkali treatment. Thereby, nickel salt and zinc salt are converted into nickel hydroxide and zinc hydroxide. Thereafter, it is sufficiently washed with water to remove the alkaline solution and then dried. A series of positive electrode active material filling operations such as impregnation with an impregnation solution, drying, immersion in an alkali treatment solution, washing with water, and drying are repeated six times, whereby a predetermined amount of the positive electrode active material is applied to the nickel sintered substrate. Filled nickel positive electrode 1
1 was produced.

2. Hydrogen Storage Alloy Negative Electrode The hydrogen storage alloy negative electrode 12 is formed by filling a negative electrode core made of punching metal with a hydrogen storage alloy slurry. In this case, for example, after mixing lanthanum (La), neodymium (Nd), magnesium (Mg), nickel (Ni), aluminum (Al), and cobalt (Co) at a predetermined molar ratio, the mixture is mixed with high frequency. A hydrogen storage alloy ingot is produced by melting in an induction furnace and then cooling. This time, La _0.3 Nd _0.6 Mg _0.1 Ni _3.6 Al _0.1 was produced.
Thereafter, heat treatment is performed in an argon gas atmosphere at 1000 ° C. for 10 hours to adjust the crystal structure in the ingot. This hydrogen storage alloy was mechanically pulverized in an inert atmosphere, and an alloy powder having a particle size of 25 μm was selected by sieving.
Thereafter, 1.0 part by mass of SBR (styrene butadiene latex) as a water-insoluble polymer binder and CMC (carboxymethylcellulose) as a thickener are added to 100 parts by mass of the obtained hydrogen storage alloy particles. 0.1 parts by mass and an appropriate amount of pure water were added and kneaded to prepare a hydrogen storage alloy slurry. And after apply | coating the obtained hydrogen storage alloy slurry to both surfaces of the negative electrode core body which consists of punching metal (made by nickel plating steel plate), after drying at 100 degreeC and rolling so that it may become predetermined | prescribed packing density, predetermined The hydrogen storage alloy negative electrode 11 was produced by cutting into the following dimensions.

4). Nickel-hydrogen storage battery A nickel positive electrode 11 and a hydrogen storage alloy negative electrode 12 produced as described above are used, and a separator 13 made of a polyolefin nonwoven fabric having a basis weight of 55 g / m ² is interposed between them. A spiral electrode group was produced by winding the electrode into a spiral shape. The core exposed part 11c of the nickel positive electrode 11 is exposed at the upper part of the spiral electrode group thus produced, and the core exposed part 12c of the hydrogen storage alloy electrode 12 is exposed at the lower part. ing. Next, the negative electrode current collector 14 is welded to the core exposed portion 12c exposed at the lower end surface of the obtained spiral electrode group, and the core exposed portion 11c of the nickel electrode 11 exposed at the upper end surface of the spiral electrode group. A positive electrode current collector 15 was welded onto the electrode body to obtain an electrode body.

Next, after the obtained electrode body was accommodated in a bottomed cylindrical outer can in which nickel was plated on iron (the outer surface of the bottom surface becomes a negative external terminal) 17, the negative electrode current collector 14 was attached to the outer can 17. Welded to the inner bottom.
On the other hand, a current collecting lead portion 15 a extending from the positive electrode current collector 15 was welded to the bottom portion of the sealing body 18. The sealing body 18 is provided with a positive electrode cap 18a, and a pressure valve (not shown) composed of a valve body 18b and a spring 18c, which are deformed when a predetermined pressure is reached, is disposed in the positive electrode cap 18a.

Next, after forming the annular groove portion 17 a on the outer periphery of the upper portion of the outer can 17, an alkaline electrolyte is injected, and the outer periphery portion of the sealing body 18 is mounted on the annular groove portion 17 a formed on the upper portion of the outer can 17. An insulating gasket 19 was placed. Then, the nickel-hydrogen storage battery 10 having a nominal capacity of 4.0 Ah and a D size (a diameter of 32 mm and a height of 44.7 mm) was produced by caulking the opening edge 17b of the outer can 17. The amount of the alkaline electrolyte injected into the outer can is 6.7 mol / L, the potassium hydroxide concentration is 4.3 mol / L, the sodium hydroxide concentration is 2.2 mol / L, and the lithium hydroxide concentration is 0.00. What mixed any 1 or more types of compounds selected from the niobium compound, the tungsten compound, and the molybdenum compound to the mixed aqueous solution adjusted to 2 mol / L was used.
In this case, as shown in Table 1, tungsten was added so as to have a predetermined amount with respect to the mass of the electrolytic solution, and nickel-hydrogen storage batteries A to R were produced.

5. Battery Test (1) Battery Activation First, using the nickel-hydrogen storage battery A to battery R produced as described above, SOC (State Of Charge) at a charging current of 1.0 It in a temperature atmosphere of 25 ° C. Charge to 120% of the charging depth) and rest for 1 hour. Next, after being left in a 60 ° C. temperature atmosphere for 24 hours, in a 30 ° C. temperature atmosphere, a cycle of discharging at a discharge current of 1.0 It until the battery voltage reaches 0.9 V is repeated two times, and these nickel -Activated the hydrogen storage batteries A to R.

(2) Charge the nickel-hydrogen storage battery A to battery R after battery capacity activation to 120% of SOC (State Of Charge) at a charging current of 1.0 It in a temperature atmosphere of 25 ° C., Paused for 1 hour. Next, the initial battery capacity of each battery was determined by repeating two cycles of discharging at a temperature atmosphere of 25 ° C. until the battery voltage reached 1.0 V with a discharge current of 1.0 It.

(3) Charging efficiency test After activation, the nickel-hydrogen storage battery A to battery R were charged with 0.5 It at an environmental temperature of 55 ° C. and 80 ° C. at an environmental temperature of 80 ° C. The state of charge (charging depth) is charged until it reaches 80%, and then a cycle of discharging until the battery voltage reaches 1.0 V with a discharge current of 1.0 It is repeated 2 cycles to discharge to the charge capacity of the second cycle. Charging efficiency was calculated from the capacity ratio.

(4) Nickel-hydrogen storage battery A to battery R after the completion of the partial charge / discharge test activation, SOC (State Of Charge) with respect to the initial battery capacity measured above in a temperature atmosphere of 50 ° C. at a charging current of 10 It. A partial charge / discharge cycle test was repeated in which a cycle of charging to a voltage at which the SOC was 20% was performed at a discharge current of 10 It after charging to a voltage at which the charge depth was 80%. And 25 degreeC discharge output was confirmed before and after such a partial charging / discharging cycle.

(5) After activation of the 25 ° C. discharge output test and after the partial charge / discharge cycle test, the nickel-hydrogen storage batteries A to R are 50% of the battery capacity at a charging current of 1.0 It in a temperature atmosphere of 25 ° C. The battery was stored for 3 hours in a temperature atmosphere at 25 ° C. and then discharged for 10 seconds at a discharge current of 50 It, and the 25 ° C. discharge output was obtained from the product of the battery voltage and current after 10 seconds. In addition, the durability was compared using the total amount of electricity discharged until the 25 ° C. discharge output reached 70% of the initial ratio after the partial charge / discharge cycle.

(6) Evaluation results Table 2 shows the evaluation results obtained as described above.

As shown in Table 2, it was confirmed that the charging efficiency and durability were greatly improved in Example 7 and Example 8 in which the amount of the electrolytic solution per positive electrode capacity was increased from Comparative Example 1.
If the charging efficiency is improved, the generation of oxygen during partial charge / discharge is reduced, and the material oxidation of the positive and negative electrodes is suppressed.
In addition, when the zinc amount of the positive electrode is in the range of 3% by mass to 8% by mass, the tungsten amount is 5 mg to 34 mg, and the charging efficiency tends to be improved as the zinc amount and the tungsten amount increase. It was confirmed in Comparative Examples 2 to 4 that the effect was not exhibited unless the liquid volume was changed from 2.4 g / Ah to 3.3 g / Ah. In the relationship between the amount of the electrolytic solution and the amount of tungsten, it is considered that a necessary amount of tungsten can be uniformly deposited on the positive electrode in order to improve the charging efficiency.
In addition, although the charging efficiency was improved even when the zinc amount was 15% by mass, it was confirmed that the output performance after partial charge / discharge was greatly reduced. This is considered to be because even though the charging efficiency is good, the reaction resistance increases due to the large amount of zinc, and the accompanying heat generation of the battery influences, accelerating material deterioration of the positive and negative electrodes.
Although no particular data is shown, similar effects have been confirmed for niobium compounds and molybdenum compounds.

As described above, an alkaline storage battery including a positive electrode and a negative electrode using nickel hydroxide as a main positive electrode active material and an alkaline electrolyte, wherein zinc is added to nickel hydroxide as a main positive electrode active material. In addition, the amount of zinc added is 3% by mass or more and 8% by mass or less based on the mass of nickel in the positive electrode active material. The alkaline electrolyte includes a tungsten compound, a molybdenum compound, and a niobium compound. Any one or more selected compounds are added, the mass of the metal element in 1 g of the alkaline electrolyte is 5 mg or more and 34 mg or less, and the alkaline electrolyte per unit positive electrode capacity of the alkaline storage battery In the alkaline storage battery, the amount is 2.4 g / Ah or more and 3.3 g / Ah or less. It was excellent and it turned out that the output fall by partial charging / discharging can be suppressed.
In addition, it is clear that batteries with low charging efficiency tend to have variations in SOC between batteries as partial charge / discharge progresses. However, in alkaline storage batteries, since this variation is reduced, the variation in SOC is further increased. It can be said that it is suitable for parallel use of sensitive alkaline batteries.

6). Next, an alkaline storage battery system 100 configured by combining a plurality of nickel-hydrogen storage batteries 10 produced as described above will be described with reference to FIG. Here, as shown in FIG. 2, the alkaline storage battery system 100 of the present invention has a power supply 101 and two battery modules connected in series with 10 unit cells made of the nickel-hydrogen storage battery 10 connected in parallel. The assembled battery 102 is formed.

Between the power source 101 and the assembled battery 102, a current and voltage from the power source 101 are converted into a predetermined constant current and constant voltage and supplied to the assembled battery 102, and a current flowing through the assembled battery 102 From the current detection circuit 104 for detecting the battery voltage, the voltage detection circuit 105 for detecting the battery voltage of the assembled battery 102, the discharge control unit 106 for controlling the forced discharge of the assembled battery 102, the current detection circuit 104 and the voltage detection circuit 105. A microcomputer 107 composed of a CPU or the like that controls the operation of the charge control unit 103 and the discharge control unit 106 is connected based on the detected value. The discharge controller 106 is connected to a discharge resistor for discharging the assembled battery 102, and the microcomputer 107 is connected to a timer 108 for measuring a predetermined time. The microcomputer 107 includes a partial charge / discharge control circuit, and is controlled such that the nickel-hydrogen storage battery 10 is partially charged / discharged.

Further, the partial charge / discharge control in the alkaline storage battery system 100 having the above-described configuration is such that the alkaline storage battery is charged / discharged only when the SOC is in the range of 20 to 80%, so that the nickel-hydrogen storage battery 10 is low. An SOC or high SOC state can be effectively prevented. Since the output performance deterioration of the nickel-hydrogen storage battery 10 is governed by the negative electrode alloy deterioration within the above control range, the alkaline storage battery of the present invention can be said to be suitable for the alkaline storage battery system having the above configuration.

DESCRIPTION OF SYMBOLS 11 ... Nickel electrode, 11c ... Core exposed part, 12 ... Hydrogen storage alloy electrode, 12c ... Core exposed part, 13 ... Separator, 14 ... Negative electrode collector, 15 ... Positive electrode collector, 15a ... Current collection lead part ,
DESCRIPTION OF SYMBOLS 17 ... Exterior can, 17a ... Annular groove part, 17b ... Opening edge, 18 ... Sealing body, 18a ... Positive electrode cap, 18b ... Valve plate, 18c ... Spring, 19 ... Insulating gasket, 100 ... Alkaline storage battery system, 101 ... Power supply, DESCRIPTION OF SYMBOLS 102 ... Battery assembly 103 ... Charge control part 104 ... Current detection part 105 ... Voltage detection part 106 ... Discharge control part 107 ... Microcomputer 108 ... Timer

Claims (3)

An alkaline storage battery comprising a positive electrode and a negative electrode having nickel hydroxide as a main positive electrode active material, and an alkaline electrolyte,
In the positive electrode, zinc is added to nickel hydroxide as a main positive electrode active material, and the amount of zinc added is 3% by mass or more and 8% by mass or less with respect to the mass of nickel in the positive electrode active material. There,
One or more compounds selected from a tungsten compound, a molybdenum compound, and a niobium compound are added to the alkaline electrolyte, and the mass of the metal element in 1 g of the alkaline electrolyte is 5 mg or more and 34 mg. An alkaline storage battery, wherein the alkaline electrolyte amount per unit positive electrode capacity of the alkaline storage battery is 2.4 g / Ah or more and 3.3 g / Ah or less.   An alkaline storage battery system comprising the alkaline storage battery according to claim 1, wherein the alkaline storage battery is subjected to partial charge / discharge control.   An alkaline storage battery system comprising the alkaline storage battery according to claim 1, wherein the alkaline storage battery is connected in parallel.

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