JP2001283840A - Nickel electrode for alkaline battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel electrode for an alkaline battery excellent in charging characteristic at high temperatures when spplied to an alkaline storage battery, which can restrain degradation of high-speed charging performance and working voltage. SOLUTION: With the nickel electrode for an alkaline battery with its conductive porous body filled with a nickel active material, the nickel active material is in such a structure that a compound layer of at least one kind of compounds selected from Sr, Sc, Y, Al, Mn, and lanthanoid is formed on the surface of a main active material with nickel hydroxide as a main constituent, and further, the compound layer is put through thermal treatment with oxygen and alkali coexisting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel electrode for an alkaline storage battery and a method for producing the same, and more particularly to an improvement in a nickel active material.

[0002]

2. Description of the Related Art In general, an alkaline storage battery has an electrode can in which a nickel positive electrode and a negative electrode using cadmium hydroxide or a hydrogen storage alloy as an active material are wound or laminated with a separator interposed therebetween. The body is impregnated with an alkaline electrolyte.

[0003] As the nickel positive electrode, a nickel positive electrode in which an active material mainly composed of nickel hydroxide is filled in a conductive porous body (porous nickel substrate) is often used.

In this alkaline storage battery, conventionally,
Performance has been improved in terms of higher capacity and longer life, but in recent years, as the operating environment of batteries has become more diverse, high-temperature charge acceptance, rapid charge acceptance, and operating voltage Performance such as securing is also required.

[0005]

In the conventional nickel electrode for an alkaline storage battery, the charging reaction and the oxygen gas generating reaction are close to each other in terms of potential, but at a high temperature, an oxygen overvoltage (in this specification, the charging reaction and However, there is a problem that sufficient charge efficiency cannot be obtained at high temperatures.

To solve this problem, Japanese Patent Application Laid-Open No. H11-73957 discloses a technique for improving the oxygen overvoltage.
Japanese Patent Application Laid-Open No. H10-125318 discloses a technique in which Ni, Co and Y are mixed (Y is 0.5 to 3%), and a group A (Mg, Ca, Sr, etc.) and a group B (Co, Japanese Patent Application Laid-Open No. 10-149821 discloses a technique for providing a surface portion which is an independent crystal in which Mn) is dissolved as a solid solution.
And Japanese Patent Application Laid-Open No. 10-25 / 1995, in which the average composition of the internal composition (Al, V, etc.) is different.
No. 5790 discloses that Ni (OH) ₂ particles are made of Ni and Y.
A technique of coating with a base hydroxide (0.15 to 3% as Y (OH) ₃ (yttrium hydroxide)) is disclosed.

As described above, in these techniques, Sr, S
Elements selected from c, Y, Al, Mn and lanthanoid elements are added in the form of hydroxide or oxide.

The compound containing the element selected from the group consisting of Sr, Sc, Y, Al, Mn and a lanthanoid element may be added to the surface of the Ni (OH) _{2 main} active material in the vicinity of the electrolyte interface. The effect of improving the oxygen overpotential is greater when more are present.

[0009] However, the above compound is converted to Ni (O
H) ₂ If it is coated on the surface of the main active material and is present more in the vicinity of the electrolyte interface, it has the effect of improving the oxygen overvoltage, but the compound does not directly participate in the charge / discharge reaction, but rather as a resistance component. As a result, the charge acceptability at a high temperature is improved, but the charge acceptability at a high temperature and the operating voltage are reduced.

Accordingly, the present invention has been made in view of the above-mentioned problems, and has been made in consideration of the application to an alkaline storage battery.
An object of the present invention is to provide a nickel electrode for an alkaline storage battery, which has excellent charging characteristics at high temperatures, and is capable of suppressing rapid chargeability and a decrease in operating voltage.

[0011]

In order to achieve the above object, the present invention provides a nickel electrode for an alkaline storage battery in which a conductive porous material is filled with a nickel active material, wherein the nickel active material is made of nickel hydroxide. A structure in which a compound layer made of at least one compound selected from Sr, Sc, Y, Al, Mn and lanthanoid elements is formed on the surface of the main active material as a main component, On the other hand, heat treatment in the coexistence of oxygen and alkali (hereinafter, referred to as
Described as "Alkali heat treatment". ).

In the nickel electrode for an alkaline storage battery according to the present invention, a compound layer composed of Sr, Sc, Y, Al, Mn and a lanthanoid element is formed on the surface of the main active material. Improve. Therefore, if this nickel electrode is used, the charging characteristics at high temperatures will be excellent.

Further, according to the present invention, since the compound layer is subjected to the alkali heat treatment, the rapid chargeability is improved and the decrease in the operating voltage is suppressed. Although there are many unclear points about this action (the reason why the effect is obtained), when the compound layer is heat-treated in the coexistence of oxygen and alkali, a part of the alkali metal ion is taken into the compound layer, so that This is probably because defects occur in the crystal lattice and the crystallinity is disturbed, so that the conductivity of the compound layer is improved.

Therefore, according to the present invention, an alkaline storage battery having excellent high-temperature charge characteristics, excellent rapid chargeability, and a high operating voltage can be realized.

In the alkaline heat treatment, LiOH (lithium hydroxide), NaOH (sodium hydroxide), KO
It is preferable to use an alkaline aqueous solution containing at least one alkali selected from H (potassium hydroxide), RbOH (rubidium hydroxide), and CsOH (cesium hydroxide). This is considered to be because the use of an alkali containing an alkali metal as described above causes a part of the alkali metal ion to be taken into the compound layer, thereby further improving the conductivity improving effect.

Further, the alkali heat treatment is performed at 60 ° C. to 220 ° C.
It is desirable to carry out in a temperature range of ° C. This is because if the processing temperature is lower than 60 ° C., the reaction by heating does not proceed, and if the processing temperature is higher than 220 ° C., Ni (OH) ₂ which is the main active material is deteriorated.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the nickel electrode for an alkaline storage battery of the present invention is applied to an alkaline storage battery will be described below.

FIG. 1 is an exploded perspective view showing an alkaline storage battery according to the present embodiment.

Here, a cylindrical nickel-cadmium storage battery will be described as an example, but the present invention can be similarly applied to a square nickel-cadmium storage battery or a nickel-hydrogen storage battery.

In this battery, an electrode body 4 in which a positive electrode plate 1 and a negative electrode plate 2 are wound via a separator 3 is housed in a cylindrical outer can 6 in a state where an electrolyte is injected. I'm done.

The positive electrode plate 1 is one in which a positive electrode active material mainly composed of nickel hydroxide is held on a substrate. This active material has been subjected to a heat treatment in the coexistence of oxygen and alkali as described below.

The negative electrode plate 2 is obtained by coating a core material (for example, punching metal) with an active material made of cadmium hydroxide.

The circular opening at the upper end of the outer can 6 is sealed by a sealing plate 12 with a gasket 11 interposed therebetween. The positive electrode terminal 13 is mounted at the center of the sealing plate 12.

A valve plate 8, a holding plate 9, and a spring 10 for holding the valve plate 8 are mounted in the positive electrode terminal 13, and a valve is formed to release internal gas to the atmosphere when the internal pressure of the battery increases. ing.

The negative electrode plate 2 is made up of an outer can 6 by a negative electrode current collector 5.
The outer can 6 also serves as a negative electrode terminal, and the positive electrode terminal 13 is connected to the positive electrode current collector 7 and the sealing plate 1.
2 and is electrically connected to the positive electrode plate 1.

[0026]

[Example] [Example] A sintered nickel electrode was manufactured as follows, and an alkaline storage battery was manufactured using the sintered nickel electrode.

A sintered nickel substrate having a porosity of 80% is mixed with a mixed solution of nickel nitrate, cobalt nitrate and cadmium nitrate at a specific gravity of 1.70 and a temperature of 70 ° C.
i: Co: Cd = 90: 5: 5) and dried. Thereafter, the solution was alkali-treated with an aqueous NaOH solution having a concentration of 7 mol / L and a temperature of 60 ° C. to form a hydroxide, followed by washing with water.

The above process was repeated six times in total, and a nickel substrate was filled with an active material mainly composed of nickel hydroxide. The electrode obtained in this manner is referred to as an electrode plate A.

Next, the electrode plate A was heated to a specific gravity of 1.10 and a temperature of 25.
Immersed in an aqueous solution of yttrim nitrate at ℃, dried, and the concentration was 7m
After pouring into an aqueous solution of NaOH at ol / L and a temperature of 60 ° C. for a predetermined time, it was heated at 100 ° C. for 60 minutes in the presence of oxygen without washing with water. Then, the nickel electrode of the example was produced by washing and drying.

In the nickel electrode thus manufactured, an alkali-heat-treated yttrium compound is formed on the surface of the nickel hydroxide layer.

This nickel electrode and a sintered cadmium electrode plate are wound through a polypropylene separator,
An electrode body was produced. Then, the electrode body was put in an outer can, and an electrolytic solution consisting of an aqueous solution having a concentration of 8 mol / LKOH was injected to prepare a nickel cadmium storage battery having a nominal capacity of 1.2 Ah and an SC size.

Comparative Example 1 In this comparative example, the electrode plate A (that is, the yttrium layer is not formed on the surface of the nickel hydroxide layer) is used as a nickel electrode.

Then, using this nickel electrode, a nickel cadmium storage battery of Comparative Example 1 was produced in the same manner as in the above example.

Comparative Example 2 A sintered nickel substrate having a porosity of 80% was mixed with a mixed solution of nickel nitrate, cobalt nitrate, cadmium nitrate and yttrium nitrate at a specific gravity of 1.70 and a temperature of 70 ° C. : Co: Cd: Y = 8
9: 5: 5: 1), after immersion and drying, concentration 7 mol / L,
Alkali treatment was performed with an aqueous NaOH solution at a temperature of 60 ° C. to form a hydroxide, followed by washing with water.

By repeating this process six times in total,
A nickel electrode of this comparative example was produced.

Using this nickel electrode, a nickel cadmium storage battery of Comparative Example 2 was produced in the same manner as in the above-mentioned Example.

[Comparative Example 3] The above-mentioned electrode plate A was prepared with a specific gravity of 1.10,
After dipping and drying in an aqueous solution of yttrium nitrate at a temperature of 25 ° C,
After pouring into a NaOH aqueous solution having a concentration of 7 mol / L and a temperature of 60 ° C. for a predetermined time, washing with water to remove alkali components,
The nickel electrode of this comparative example was produced by performing a heat treatment at 100 ° C. for 60 minutes in the presence of oxygen.

Then, using this nickel electrode, a nickel cadmium storage battery of Comparative Example 3 was produced in the same manner as in the above example.

Table 1 summarizes the features of the examples and comparative examples.

[0040]

[Table 1] The batteries of the examples and the comparative examples 1 to 5 produced as described above.
Battery 3 was charged and discharged under the following conditions,
The discharge capacity of the battery and the intermediate voltage during discharge were measured.

Conditions Charge: 0.1 C × 16 hours (25
Temperature), discharge: 1C (EV = 1.0V, 25 ° C environment) Condition charging: 0.1C x 16 hours (45 ° C environment)
Discharge: 1C (EV = 1.0V, 25 ° C environment) Conditions Charge: 1C x 90 minutes (25 ° C environment), Discharge:
1C (EV = 1.0 V, in a 25 ° C. environment) Then, from each result, a discharge intermediate voltage, a high-temperature charge characteristic, and a rapid charge characteristic were calculated in accordance with the following formulas.

-Intermediate discharge voltage = Intermediate discharge voltage under conditions-High temperature charge characteristics = Discharge capacity under conditions / Discharge capacity under conditions-Quick charge characteristics = Discharge capacity under conditions / Discharge capacity under conditions Table 1 shows the results of each calculation. Indicated.

As can be seen from the results in Table 1, the high-temperature charging characteristics are improved in Comparative Examples 2, 3 and Examples in which Y is added, as compared with Comparative Example 1 in which Y is not added.

Further, in Comparative Example 3 and Example in which Y was added to the surface, the high-temperature charging characteristics were more improved than in Comparative Example 2 in which Y was added as a solid solution.

In addition, a comparison between Comparative Example 3 in which Y was added to the surface and Example of the present invention shows that Comparative Example 3 in which the alkali heat treatment was not performed.
Examples in which the alkali heat treatment was performed exhibited higher values of the discharge intermediate voltage and the rapid charge characteristic than the examples in which the alkali heat treatment was performed.

That is, in the comparative example 3, the discharge intermediate voltage and the quick charge characteristic are lower than those of the comparative examples 1 and 2, but in the embodiment, the discharge intermediate voltage and the quick charge characteristic are equal to those of the comparative examples 1 and 2.

Based on such an embodiment, the effects obtained by using the positive electrode plate 1 are summarized as follows.

<Effect of Positive Electrode Plate 1> In the positive electrode plate 1, a compound layer composed of Sr, Sc, Y, Al, Mn and a lanthanoid element is formed on the surface of the nickel hydroxide layer or the nickel hydroxide particles. Since the compound layer improves the oxygen overvoltage, the nickel-cadmium storage battery using the nickel electrode has excellent high-temperature charging characteristics.

In the positive electrode plate 1, the above compound layer is formed on the surface of nickel hydroxide, but is charged at a high temperature in the same amount as when the same compound is added as a solid solution to the nickel hydroxide active material. The effect of improving characteristics can be obtained.

In the alkaline heat treatment, LiO
Since an alkaline aqueous solution containing an alkali selected from H, NaOH, KOH, RbOH, and CsOH was used, a part of the alkali metal ions was incorporated in the compound layer. Then, the incorporated metal ions cause a defect in the crystal lattice of the compound layer to disturb the crystallinity, so that it is considered that there is an effect of improving the conductivity of the active material. Due to the effect of improving the conductivity, an alkaline storage battery using this nickel electrode has excellent quick chargeability and a high operating voltage.

It should be noted that such an effect of improving the charging characteristics and rapid charging properties can be obtained without adding elements such as Co and Cd to the nickel hydroxide active material. An even better effect can be expected by making Co, Cd form a solid solution in Ni or Co, C, or Cd in the compound layer.

In the above embodiment, an example in which Y is used is shown. However, Ca, Al, Sr, Sc and lanthanoid-based elements have the effect of similarly improving the high-temperature charging characteristics. The same effect can be obtained by using a mixture of these.

[0053]

As described above, the present invention relates to a nickel electrode for an alkaline storage battery in which a conductive porous body is filled with a nickel active material, wherein the nickel active material is mainly composed of nickel hydroxide. Sr, S on the surface of the substance
A structure in which a compound layer composed of at least one compound selected from c, Y, Al, Mn and a lanthanoid element is formed, and the compound layer is subjected to a heat treatment in the presence of oxygen and an alkali. This makes it possible to realize an alkaline storage battery having excellent high-temperature charging characteristics, excellent rapid charging properties, and a high operating voltage.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an alkaline storage battery according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 4 Electrode body 6 Outer can

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Chihiro Fujisawa 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. F-term (reference) 5H050 AA02 BA13 BA14 CA03 CB14 CB16 DA02 DA09 EA12 FA05 GA02 GA14 GA15 GA23 HA14

Claims (5)

[Claims] 1. A nickel electrode for an alkaline storage battery in which a conductive porous body is filled with a nickel active material, wherein the nickel active material is formed on a surface of a main active material mainly composed of nickel hydroxide.
A compound layer comprising at least one compound selected from r, Sc, Y, Al, Mn and lanthanoid elements is formed, and the compound layer is subjected to a heat treatment in the presence of oxygen and an alkali. A nickel electrode for an alkaline storage battery. 2. A conductive porous substrate is filled with a main active material mainly composed of nickel hydroxide and then filled with Sr, Sc, Y, and A.
A method for producing a nickel electrode for an alkaline storage battery, comprising: providing a compound layer comprising at least one compound selected from l, Mn, and a lanthanoid-based element, and performing heat treatment in the presence of oxygen and an alkali. 3. A compound layer comprising at least one compound selected from Sr, Sc, Y, Al, Mn and lanthanoid elements is provided on a main active material mainly composed of nickel hydroxide, and oxygen and alkali coexist. A method for producing a nickel electrode for an alkaline storage battery, comprising filling an active material obtained by heat treatment below into a conductive porous substrate. 4. The method according to claim 1, wherein the heat treatment is carried out in the presence of oxygen and alkali, wherein the alkali species is LiOH, NaOH, KOH,
4. The method for producing a nickel electrode for an alkaline storage battery according to claim 2, wherein the aqueous solution is an alkaline aqueous solution containing at least one alkali selected from RbOH and CsOH. 5. The production of a nickel electrode for an alkaline storage battery according to claim 2, wherein the treatment temperature in the case of performing the heat treatment in the coexistence of oxygen and alkali is in a temperature range of 60 ° C. to 220 ° C. Method.