JP3407983B2 - Method for producing non-sintered positive electrode for alkaline storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to nickel-cadmium.
Storage batteries and nickelmetalUsed for hydride storage batteries
Production method for non-sintered positive electrodes for alkaline storage batteries
Or nickel hydroxide active material constituting such a positive electrode
Regarding improvement. [0002] 2. Description of the Related Art Conventionally, nickel-cadmium storage batteries, etc.
For the nickel electrode, a sintered nickel positive electrode is used.
However, this sintered nickel positive electrode has a pore diameter of the sintered substrate.
Nickel because it is smallActive materialPowder can be filled directly
I can't. For this reason, nickel is converted to a nickel nitrate solution.
After impregnating the sintered substrate with
Immersion to change the nickel nitrate to nickel hydroxide
By repeating the operation several times, the active material
Filling has been done. However, this method
The productivity is low because the process is complicated. Moreover, the sintered substrate
Has a sufficiently high active material packing density in the electrode plate due to its low porosity.
I can't do it. Therefore, high energy density cathode
There are limits to what you can do. Therefore, recently, the sintering method
Instead, non-sintered nickel cathodes are being used.
You. For non-sintered type, sponge-like or felt-like metal
Because a high porosity active material holder such as a porous body can be used,
Nickel active material can be directly filled as slurry
it can. Therefore, the non-sintered nickel positive electrode is
In addition, the manufacturing method is simple, and the weight and capacity of the electrodes are reduced.
There is a feature that quantification can be achieved. By the way, an alkali having a nickel positive electrode
In a storage battery, when lithium is added to the electrolyte,
It is known that the energy density of
I have. However, the effect is simply that lithium is
It is not something that is exhibited if it is present.
The added lithium becomes nickel hydroxide as lithium ions.
Effect only when incorporated into the crystal lattice of
Things. From this, Japanese Patent Application Laid-Open No. 60-21176
No. 7 discloses an alkali containing lithium in a nickel salt solution.
Aggregation of nickel hydroxide by the action of metal
A technology has been proposed to pre-contain lithium in the particles.
I have. According to this technology, the aggregated particles of nickel hydroxide
As it is formed, lithium is trapped inside
Charging and discharging compared to adding lithium to the electrolyte
Nickel active material utilization and charge acceptance from the early stages
Can be improved. Therefore, such a Lichi
Of positive electrode using nickel-containing nickel active material as active material
Thus, the capacitance density of the electrode is improved. [0004] However, the above technique is not suitable.
Even when used, the initial charge and discharge of the nickel positive electrode
Capacity density can not be sufficiently increased. Why
According to the above technology, lithium ions are sufficiently
Because it cannot be taken into the crystal lattice of the substance,
Of lithium contained in the aggregate of nickel hydroxide particles
Some simply exist on the nickel hydroxide particles
Because it is. Therefore, Nickel that applied the above technology
Initially, the positive electrode has an initial
Improved charge / discharge characteristicsToHowever, the capacity density is sufficient
It is not expensive. That is, with a nickel positive electrode to which the above-described technology is applied,
Is not incorporated in the nickel hydroxide crystal lattice.
Multiple cycles of charge and discharge due to the presence of
To form such lithium into nickel hydroxide.
If they are not incorporated in the crystal lattice, the effect of lithium
There was a problem that it could not be withdrawn. The present invention
Considering the problems of the above-mentioned technology, lithium
Incorporate ions well into the nickel hydroxide crystal lattice
We found a method to achieve high energy density from the beginning of charging and discharging.
Of non-sintered nickel positive electrode manufacturing method
What you want to do. [0006] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The invention according to claim 1 is characterized in that a lithium hydroxide containing lithium is provided.
Non-sintered nickel positive with process to make nickel powder
In the method for producing an electrode, the step may be an acidic lithium salt.
And a mixed aqueous solution of an acidic nickel salt and an aqueous alkaline solution
And PH in the reaction tank8 or more and 12 or lessTo be maintained
Controlling the amount of each aqueous solution introduced into the reactorgraduallyTo
Hydrogen containing lithium by introducing and mixing
Characterized by comprising a step of depositing nickel halide crystals
And [0007] [0008] [Action] According to the invention of claim 1, a lattice of nickel hydroxide crystal
Contains lithium with sufficient lithium ions incorporated
Nickel hydroxide can be obtained. In the following,
I will elaborate. In addition, when simply writing “lithium”,
Means that lithium element should be present in any form.
Tastes, regardless of the chemical form of lithium. As already described, a nickel positive electrode is provided.
Lithium is added to the electrolyte of alkaline storage batteries
In this case, the nickel positive electrode energy is
Energy density is improved.
Addition effect). This effect of adding lithium
Since the ion radius is smaller than the nickel ion radius, the battery
At the time of charging, lithium ion
Nickel hydroxide penetrates into the crystal lattice of KelElectrification
To improve the physical properties,Those that improve charge acceptance and utilization
ThoughtLaIt is. From this, the effect of lithium addition is sufficient
In order to draw out as much as possible from the beginning
The ions into the crystal lattice of nickel hydroxide
Is good. However, as in the prior art, nickel
A predetermined amount of alcohol is simply added to the acidic mixed aqueous solution of salt and lithium salt.
When the potash solution is poured, lithium ions are sufficient
Not incorporated into the crystal lattice of nickel hydroxide. This reason
The reason will be described below. Nickel and lithium salts
Predetermined amount of alkali required for acid-alkali reaction in mixed aqueous solution
When added, a gel of lithium hydroxide and nickel hydroxide
When the gel-like precipitate is dried,
A nickel hydroxide powder containing titanium can be obtained. Only
And a method of simply acting a predetermined amount of alkali in this way.
Is convenient for precipitation of nickel hydroxide and lithium hydroxide
Is not done. Therefore, the nickel hydroxide crystal lattice
Lithium cannot be sufficiently taken in. what
Because of this, it is necessary to use an acidic mixed aqueous solution of nickel salt and lithium salt.
Immediately after the addition of Lucari, nickel and lithium salts
The reaction between the solution and the alkali proceeds, and the solution PH changes accordingly.
Precipitation of nickel hydroxide or lithium hydroxide
The matter changes every moment. Therefore, lithium hydroxide in nickel hydroxide
The presence of um is not uniform and non-uniform. Toes
And incorporated into nickel hydroxide crystals as lithium ions
Some lithium, but separate from nickel hydroxide crystals
Deposited as lithium hydroxide around nickel hydroxide
Some are issued. Therefore, it is made in this way.
The lithium-containing nickel hydroxide powder
Low percentage of lithium in the Kel crystal lattice
And only a part of the contained lithium is
It merely shows an improvement effect. In the present invention, the acidic nickel salt and the lithium
The mixed aqueous solution of calcium salt and alkaline aqueous solution
In the step of depositing nickel-containing nickel hydroxide,
In order to always maintain the solution PH in the reaction tank at a predetermined value,
Reaction by controlling the amount of both solutions introduced per unit time
Introduced into the tank and mixed to remove lithium-containing nickel hydroxide
It was configured to precipitate. With such a configuration,
The solution PH in the reactor is always maintained at the desired value
Under certain suitable conditions
To deposit lithium, thereby converting lithium
Obtaining nickel hydroxide sufficiently incorporated in the crystal lattice
Becomes possible. [0012] Here, the predetermined PH is determined by the intensity of stirring of the solution.
Considering the temperature and solution temperature, the lattice of nickel hydroxide crystal
Set conditions suitable for incorporating lithium into
I just need. Water thus precipitated under suitable conditions
Nickel oxide ensures that lithium ion
The lithium-containing water thus obtained.
If the nickel cathode is composed of nickel oxide powder,
Even if no charge / discharge operation is added as in
It has an energy density. Claims1In the invention of, AntiPH in the tank is 8 ~
12, but within such a pH range, P
When H is set, the nickel hydroxide crystal lattice
Lithium-containing nickel hydroxide with lithium incorporated
Obtainable. Here, the reason why the PH is set to 8 or more is that
The lithium-containing nickel hydroxide obtained at a pH of less than 8
Many anion roots (impurities) remain in the Kel powder,
This is because the anion root affects the battery reaction,
The reason for setting it to 2 or less is that if the PH in the reaction tank exceeds 12,
It is not preferable because the activity of nickel hydroxide decreases.
It is. From this, PH in the reaction tank is 8-12.
It is preferable to set the pH in a range. [0014] The present invention will now be described based on examples and comparative examples.
Will be explained. [Examples 1 to 5] (Preparation of lithium-containing nickel hydroxide powder)
2mol / l (liter; same hereafter) nickel sulfate
Mixed aqueous solution consisting of 0.03 mol / l lithium sulfate
Liquid (Ni / Li mixed liquid) and 6.0 mol / l
Prepare an aqueous solution of sodium hydroxide (referred to as alkaline solution)
And PH7.5, 8, 10, 12, 13
Sodium hydroxide aqueous solution of PH
Is prepared. Next, the above-mentioned pH was introduced into a reaction vessel equipped with a stirrer.
7.5An appropriate amount of the preliminary alkaline solution of
Introduce the acidic mixture at a constant flow rate and
And the solution in the reaction tank7.5To be maintained in
While monitoring the PH in the tank with a
The liquid is introduced into the reaction tank. When introducing the alkaline solution
Means that the pH in the reaction tank is
Nickel, precipitation of lithium hydroxide)ToMore variable,
In accordance with this, the introduction flow rate of the alkaline solution was appropriately adjusted.
The reaction vessel is heated to about 40 ° C.
The solution in the reaction tank is always stirred. Thus, the Ni / Li mixed solution and the alkali
The mixture was mixed to precipitate nickel hydroxide.
The sample is washed with water, dried, and
Kel powder was obtained. Such a series of operations is performed on PH8, 1
About the case of using 0, 12, and 13 preliminary alkaline liquids
Is performed in the same manner as described above, and the five
Ri (a₁~ A_Five) Lithium-containing nickel hydroxide powder
Produced. Note that these five types of lithium-containing nickel hydroxide
The lithium content of Kel powder was measured by atomic absorption spectrometry.
At this time, all contained about 1% by weight of lithium. (Preparation of Nickel Positive Electrode)
Nickel hydroxide powder (a₁~ A_Five) To 0.2 by weight
Cobalt hydroxide powder is added to form an active material powder.
0.5% by weight methylcellulose aqueous solution in substance powder
Are added and mixed to prepare an active material slurry. This activity
After filling the material slurry into the foamed nickel substrate and drying,
Rolling produced a nickel electrode plate. The nickel plate thus produced is
For each lithium-containing nickel hydroxide powder used,
In response, the present invention example nickel positive electrode A₁~ A_FiveAnd [Comparative Example 1] Ni / Li mixed without using a preliminary alkaline liquid
Liquid and alkaline solution are charged into the reaction tank to control the pH in the reaction tank
Except for stirring without performing, the above Examples 1-5
Similarly, a nickel hydroxide powder was produced. The powder produced in this manner is added to
Hackel powder b₁And This nickel powder b₁Using
Comparative Example Nickel Positive Electrode B as in Examples 1 to 5₁Make
Made. [Comparative Example 2] 13 kg of hexahydrated crystalline nickel sulfate was converted to water.
Dissolve to a total volume of 40 l, and stir at about 25 ° C.
While stirring, 6.5 kg of lithium hydroxide powder was added.
Then, it is left at about 50 ° C. for 1 hour. After that, collect the precipitate
After drying, pulverizing, washing with water and drying again,
Thus, a nickel powder was obtained. The powder thus prepared was used as a comparative water
Nickel oxide powder b_TwoAnd This nickel hydroxide powder
b_TwoComparative Example Nickel in the same manner as in Examples 1 to 5
Positive electrode B_TwoWas prepared. . [Comparative Example 3] Instead of the Ni / Li mixed solution, 2.2 standard
Use a fixed nickel sulfate aqueous solution and adjust the pH of the reaction tank to 1
Except having set to 0, it carried out similarly to the method of Examples 1-5.
And nickel hydroxide powder b_ThreeWas prepared. In addition, this water
Nickel oxide powder b_ThreeContains no lithium
Things. This nickel hydroxide powder b_ThreeUsing
Comparative Example Nickel Positive Electrode B as in Examples 1 to 5_ThreeMake
Was. [Experiment 1] Regarding the various nickel hydroxide powders,
The degree was measured. Table 1 shows the results. Table 1
Is nickel hydroxide powder b_ThreeConcentration of residual sulfate (w /
w) is assumed to be 100, and is expressed in% with respect to this. [Table 1] From Table 1, when the reaction tank PH was set to 8 to 13,
In this case, the concentration of residual sulfate is nickel hydroxide powder b_Three(versus
) And almost the same. On the other hand, the reaction tank PH is set to less than 8.
As a result, it can be seen that the concentration of residual sulfate radicals is significantly increased. this child
Therefore, the reaction tank PH is preferably set to 8 or more. [Experiment 2] The above various nickel hydroxide powders were treated with
After washing thoroughly with exchange water, dry and wash with hot water
Nickel hydroxide is prepared by preparing nickel powder
The powder and various nickel hydroxide powders before hot water washing
The measurement of the amount of titanium was performed. The measurement results are as follows:
And the lithium content after hot water washing as 100
Calculate the ratio to the previous lithium content, and
The state of lithium in the powder was evaluated. The right column of Table 1 shows the lithium content ratio after hot water washing.
Show. Table 1 shows the following. Constant P using a reaction tank
Inventive nickel powder a produced by the method of controlling H₁
~ A _FiveShowed little difference in lithium content before and after hot water washing.
Not. On the other hand, comparison made by a method without PH control
Nickel powder b₁, B_TwoThen, it contains lithium by washing with hot water
The amount has dropped significantly. It is considered that these results are due to the following reasons.
Can be Lithium-containing prepared by the method according to the present invention
Nickel hydroxide powder, lithium is nickel hydroxide crystal
Because it is fully taken into the inside,
Therefore, it is not lost. In response, PH control
Nickel hydroxide powder produced by a method that does not
The reason for the much lower lithium content is that lithium
Not sufficiently incorporated in the nickel hydroxide crystal lattice,
Exists around nickel hydroxide crystals
This is probably due to the large amount of lithium. [Experiment 3] Using the above various nickel positive electrodes
A test battery was constructed, and various nickel positive batteries were
The pole performance was compared. The test battery was made as follows.
Was. The nickel positive electrode A₁~ A_FiveAnd each of the above
A well-known cadmium negative electrode with a capacity much larger than
And using an aqueous solution of potassium hydroxide as the electrolyte
A sealed nickel of A size with a nominal capacity of 1.2 Ah
Cadmium storage battery. For each of the test batteries thus configured,
After charging for 16 hours at 0.1C, battery voltage at 1C
Charge-discharge cycle of discharging until the voltage reaches 1.0 V
Was repeated for 10 cycles. And in the first cycle
The discharge capacity at the tenth cycle was measured. Table 2 shows the results.
Shown in [Table 2] From Table 2, it is possible to control the pH of the reactor by a constant method.
XA using a nickel positive electrode manufactured according to the present invention₁~ X
A_FiveAre all XB using a comparative nickel positive electrode.₁, X
B_TwoAnd XB as a control_Three(Contains no lithium)
Higher discharge capacity at 1st cycle and 10th cycle
Indicates the amount. Of particular note is the invention
Such a battery XA₁~ XA_FiveThen, high from the first cycle
Battery capacity of Comparative Example X
B₁, B_TwoSo the 10th cycle is better than the 1st cycle
The discharge capacity has increased. This is the case with the present invention.
In the nickel positive electrode, lithium is formed from nickel hydroxide from the beginning.
Since it is taken into the crystal lattice,
While the effect of adding titanium is exhibited, the comparison nickel
In the positive electrode, the lithium hydroxide powder contained in the nickel hydroxide powder
A significant amount of lithium in the crystal lattice of nickel hydroxide
These lithiums are charged and discharged
Gradually introduces lithium into the crystal lattice of nickel hydroxide
Incorporated to show the effect of lithium addition
It is thought to be. The battery XA of the present invention_FiveIs a comparative battery
XA₁~ XA_Four, The discharge capacity is slightly lower. This
This is a nickel positive electrode A_FiveOf Nickel Hydroxide Used for Iron
Is considered to be due to the low degree,
It is understood that the reaction tank PH is preferably set to 12 or less. [0028] The production method of the present invention is used as described above.
And lithium ions ensure the crystal lattice of nickel hydroxide
Lithium addition effect
Lithium hydroxide
Kel powder. Therefore, for the alkaline storage battery of the present invention
According to the method for manufacturing a non-sintered positive electrode, high
It is possible to provide a nickel positive electrode that can realize a high battery capacity.

Continuation of the front page (56) References JP-A-5-62673 (JP, A) JP-A-1-267957 (JP, A) JP-A-60-211767 (JP, A) JP-A-61-104565 (JP) , A) JP-A-63-16556 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/26 H01M 4/32

Claims (1)

(57) [Claim 1] In a method for producing a non-sintered nickel positive electrode comprising a step of producing lithium hydroxide-containing nickel hydroxide powder, the step comprises at least an acidic lithium salt And a mixed aqueous solution of an acidic nickel salt and an alkaline aqueous solution are gradually introduced into the reaction tank while controlling the introduction amount of each aqueous solution so that the PH in the reaction tank is maintained at 8 or more and 12 or less. A method for producing a non-sintered positive electrode for an alkaline storage battery, comprising a step of precipitating lithium-containing nickel hydroxide crystals by mixing.