JP3316301B2 - Activation method of sealed nickel-hydrogen storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for activating a sealed nickel-hydrogen storage battery using a hydrogen storage alloy electrode as a negative electrode, and more particularly to a method for efficiently activating a hydrogen storage alloy electrode in a short time. The present invention relates to an improvement in the amount of an electrolytic solution at the time of an activation process to make it possible.

[0002]

2. Description of the Related Art In recent years,
Since the sealed nickel-hydrogen storage battery using a hydrogen storage alloy capable of reversibly storing and releasing hydrogen for the negative electrode has a high energy density, is clean, and has substantially the same voltage as the nickel-cadmium storage battery. Because of its advantages such as compatibility with, it has attracted attention as a next-generation alkaline storage battery.

[0003] Before this sealed nickel-hydrogen storage battery is put into practical use, it is necessary to perform charging and discharging in advance to activate the hydrogen storage alloy of the negative electrode. Conventionally, this activation process has been performed with the entire amount of the electrolyte injected.

[0004] However, in this conventional activation treatment method, since the amount of the electrolyte during the activation treatment is too large, the internal pressure of the battery rises when the battery is rapidly charged at a high rate, and the battery cannot be sufficiently charged. As a result, the activation becomes insufficient, and on the other hand, there is a trade-off problem that the activation process takes a long time if charging and discharging at a low rate in order to suppress the rise in the internal pressure of the battery and perform the activation sufficiently. Was.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sealed nickel-nickel alloy.
It is an object of the present invention to provide a method for efficiently activating a hydrogen storage alloy in a hydrogen storage battery in a short time.

[0006]

The method of activating a sealed nickel-metal hydride storage battery according to the present invention for achieving the above object (hereinafter referred to as "the method of the present invention") is intended to achieve the above object. The charge / discharge is performed with the amount of the electrolyte corresponding to 35 to 80% by volume of the total amount of the electrolyte to be performed.

In the present invention, the amount of the electrolyte during the activation treatment is regulated to 35 to 80% by volume of the total amount of the electrolyte to be finally injected. Activation of the hydrogen storage alloy electrode becomes insufficient because the electrolyte does not sufficiently reach the plate. On the other hand, if it exceeds 80% by volume, the internal pressure of the battery rises in a short time, resulting in insufficient charging. Is insufficient (when charging and discharging at a high rate) or a long time is required for activation (when charging and discharging at a low rate).

After the activation treatment method according to the present invention is carried out, the remaining electrolyte (65 to 20% by volume of the total electrolyte) may be injected before the start of the charge / discharge cycle. It may be performed after the discharge cycle has elapsed. Further, the injection after the activation treatment can be performed in a plurality of times. If the concentration and the amount of the electrolyte injected before the activation treatment are more than a certain level, it is sufficient to simply supply water. In some cases.

The activation treatment method according to the present invention is preferably carried out in a state in which part or all of the air inside the battery is replaced with oxygen gas or hydrogen gas. By substituting with oxygen gas and / or hydrogen gas, the partial pressure of these gases inside the battery increases, and the oxygen gas absorption characteristics at the negative electrode or the hydrogen gas absorption characteristics at the positive electrode improve, thereby increasing the internal pressure of the battery. Is suppressed, and the charge amount during the activation process is increased. The gas replacement amount inside the battery with oxygen gas and / or hydrogen gas is preferably 80 to 100 mol%.

[0010]

The gas generated in the battery system at the time of activation is electrochemically quickly consumed because the amount of the electrolyte during the activation treatment is regulated to 80% by volume or less of the total amount of the electrolyte. As a result, an increase in battery internal pressure is suppressed. For this reason, it is possible to increase the current value at the time of charging in the activation process, that is, to perform rapid charging, whereby the activation process can be completed in a short time, and the charging depth is increased, so that the hydrogen storage alloy is increased. Is sufficiently activated to the inside of the electrode plate.

Further, since the amount of the electrolyte during the activation treatment is regulated to 35% by volume or more of the total amount of the electrolyte, the activation is not insufficient due to the shortage of the electrolyte.

[0012]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples, and may be carried out by appropriately changing the scope of the present invention. Is possible.

[Production of Sealed Nickel-Hydrogen Storage Battery] (Example 1) Commercially available misch metal (Mm), nickel, cobalt, aluminum and manganese are weighed and mixed at a predetermined ratio, and are mixed using an arc melting furnace. After being melted, it is cooled, and has a composition formula: MmNi _3.2 Co _1.0 Al _0.6
A hydrogen storage alloy lump represented by Mn _0.2 was obtained, and the alloy lump was mechanically pulverized to produce a hydrogen storage alloy powder having an average particle diameter of 50 μm.

Next, 0.5 parts by weight of polyethylene oxide and water as a dispersion medium were added to 100 parts by weight of the hydrogen storage alloy powder and kneaded to prepare a slurry.

The slurry is poured into a container, passed through a conductive support made of punched metal plated with nickel, and the slurry is applied to both surfaces of the support. The slurry is dried and pressure-formed. Thus, a hydrogen storage alloy electrode was produced.

The above-mentioned hydrogen storage alloy electrode as a negative electrode and a well-known sintered nickel electrode are spirally wound through a separator made of a non-woven fabric made of a polyamide resin to form an electrode body. Then, an electrolyte containing an aqueous solution containing 25% by weight of potassium hydroxide, 2% by weight of sodium hydroxide and 1% by weight of lithium hydroxide was charged to 2.00%.
cc (corresponding to about 57% of the total electrolyte volume of 3.50 cc) was injected, sealed, and an AA size sealed nickel-hydrogen storage battery A (theoretical capacity: 1000 mAh) was assembled.

FIG. 1 is a schematic sectional view of an assembled sealed nickel-hydrogen storage battery A. The battery A shown in FIG.
It comprises a positive electrode 1 and a negative electrode 2, a separator 3, which separates these electrodes, a positive electrode lead 4, a negative electrode lead 5, a positive electrode external terminal 6, a negative electrode can 7, and the like. On the bottom surface of the negative electrode can 7, a replacement fluid pipe 9 having a rubber stopper 8 at the tip for replenishing the electrolyte solution after the activation treatment is attached. Is prevented from dropping from the replacement fluid pipe 9. The positive electrode 1 and the negative electrode 2 are spirally wound via a separator 3 and housed in a negative electrode can 7. The positive electrode 1 is connected to a positive electrode external terminal 6 via a positive electrode lead 4, and the negative electrode 2 is connected to a negative electrode lead 5. The battery is connected to the negative electrode can 7 via the anode, so that the chemical energy generated inside the sealed nickel-hydrogen storage battery A can be taken out as electric energy.

With respect to this sealed nickel-hydrogen storage battery A, the rubber plug 8 of the replacement fluid pipe 9 is removed, and a pressure sensor is attached instead. At 0.05 C, the battery internal pressure reaches 2.5 atm within 30 hours. If the battery pressure did not reach 30 hours, or if the battery pressure reached 2.5 atm within 30 hours, charge the battery until the battery pressure reached 2.5 atm.
After halting at 0 ° C. for 24 hours, discharge was performed at 0.1 C to 1 V to perform an activation process. Then, the battery was turned upside down, the pressure sensor was removed, and 1.50 cc of the electrolyte solution was replaced. Then, a rubber stopper 8 was attached to the replacement solution pipe 9 and sealed. This battery is referred to as battery A1.

(Example 2) In the same manner as in Example 1, activation of the sealed nickel-hydrogen storage battery A was performed. However, the replacement solution of the electrolyte solution after activation (1.50 cc)
The test was performed not at the start of the charge / discharge cycle but at the 500th cycle. This battery is referred to as battery A2.

Example 3 A sealed nickel-hydrogen battery was prepared in the same manner as in Example 1 except that the inside of the battery can was replaced with oxygen gas after the injection of the electrolytic solution and before the activation treatment. The activation process of the storage battery A was performed. This battery is referred to as battery A3.

(Comparative Example 1) The activation process of the sealed nickel-hydrogen storage battery A was performed in the same manner as in Example 1. However, replacement of the electrolytic solution (1.50 cc) after the activation treatment was not performed. This battery is referred to as battery B1.

(Comparative Example 2) The activation process of the sealed nickel-hydrogen storage battery A was performed in the same manner as in Example 1 except that the activation process was performed with the whole electrolyte (3.50 cc). This battery is referred to as battery B2.

[Battery internal pressure during charging in activation process]
Regarding the batteries A1 to A3, B1 and B2, the degree of increase in the battery internal pressure during charging in the activation process was examined. The results are shown in FIG. FIG. 2 is a graph showing the battery internal pressure (atmospheric pressure) on the vertical axis and the charging capacity (Ah) on the horizontal axis.
As shown in the figure, in the batteries A1, A2, and B1 activated by using a part (about 57%) of the total amount of the electrolyte, the internal pressure of the battery gradually increases until the charging capacity reaches about 1.00 Ah. In contrast, the battery can be charged to about 1.20 Ah, whereas the battery B2, which has been activated by using the entire amount of the electrolytic solution, does not charge sufficiently because the internal pressure of the battery rapidly increases immediately after the start of charging. This is because, in the battery B2, the amount of the electrolyte during the activation process is large, and the oxygen gas generated at the positive electrode during charging is difficult to pass through the separator due to the large amount of the electrolyte. Further, in the battery A3 in which the gas inside the battery was replaced with oxygen gas and the activation process was performed, the internal pressure of the battery during the activation process rose most slowly. This is because the oxygen gas consumption reaction at the negative electrode progressed quickly because the partial pressure of oxygen gas inside the battery increased. In the battery A3, the rise in the internal pressure of the battery during the activation process is moderate, so that the charging during the activation process can be performed by a simple time-cut method.

[Initial (First Cycle) Discharge Capacity After Activation] For batteries A1 to A3, B1 and B2,
At 0.1C, 12 hours if the battery internal pressure does not reach 2.5 atm within 12 hours, or 2.5 atm if the battery internal pressure reaches 2.5 atm within 12 hours , And then discharged to 1 V at 0.1 C, and the initial discharge capacity after the activation treatment was examined. Table 1 shows the results.

[0025]

[Table 1]

As shown in Table 1, in the batteries A1, A2, and B1 in which the charging in the activation process was performed up to about 1.20 Ah and the activation of the hydrogen storage alloy electrode was sufficiently performed, the initial state after the activation process was performed. Is not more than 1.00 Ah, whereas the battery in B2, in which the charging in the activation process was not sufficiently performed and the activation of the hydrogen storage alloy electrode was insufficient, was performed after the activation process. The initial discharge capacity is 0.65
It is as small as 5Ah. Further, in the battery A3 in which the charging in the activation process was performed at 1.50 Ah or more because the rise in the battery internal pressure was small, the initial discharge capacity after the activation process was 1.
030 Ah, which is the largest.

[Charge / Discharge Cycle Characteristics]
A3 and comparative batteries B1 and B2 were charged at 2C for 11 minutes, paused for 1 hour, discharged at 2C to 1V,
A cycle test was performed in which the time-pausing step was defined as one cycle, and the discharge capacity of each battery was determined every 50 cycles. 5
The discharge capacity of each battery at every 0 cycle is 0.1 C
12 hours if the battery internal pressure does not reach 2.5 atm within the time, or after charging the battery internal pressure reaches 2.5 atm if the battery internal pressure reaches 2.5 atm within 12 hours , And 0.1 C and discharged to 1 V. FIG. 3 shows the results, and Table 1 shows the discharge capacity at the 1001th cycle.

As shown in FIG. 3 and Table 1, the capacity of the battery B1 begins to decrease after 500 cycles, and the initial discharge capacity of 1.005 Ah reaches 0.1 at the 1001th cycle.
675 Ah, and in the battery B2, the initial discharge capacity is 0.655 Ah, and the discharge capacity in the 1001 cycle is 0.730 Ah, which are all low. On the other hand, in the battery A3, even at the 1001th cycle, the battery capacity did not decrease at all and the discharge capacity was 1.030 Ah.
Has been maintained. In the battery A1, the discharge capacity gradually increased with the lapse of the charge / discharge cycle, and became equal to the discharge capacity of the battery A3 after the 500th cycle. In the battery A2 in which the electrolyte was replaced at the 500th cycle, the battery A2 before the replacement was used. Although the discharge capacity was slightly lower than the initial discharge capacity (showing exactly the same charge / discharge cycle characteristics as the battery B1 before the replacement), the capacity gradually recovered after the replacement and eventually became equivalent to the discharge capacity of the battery A3. .

As described above, in the case where a small amount of the electrolytic solution is used during the activation process and the replacement is not performed after the activation process (battery B1)
Means that although the initial discharge capacity is large, the cycle life is short, while a large amount of electrolyte is used at the time of the activation treatment and no replenishment is performed after the activation treatment (battery B2), the discharge capacity is long but the discharge capacity becomes small throughout. Therefore, the activation treatment is performed on a part of the entire electrolyte, and the remaining electrolyte is replaced after the activation treatment including after the start of the charge / discharge cycle,
It can be seen that this is necessary for obtaining a sealed nickel-hydrogen storage battery having a large discharge capacity and a long cycle life.

[Amount of Electrolyte Solution During Activation Process] Amount of electrolyte solution during activation process and after activation process (before start of charge / discharge cycle)
In the same manner as in Example 1 except that the replacement fluid amount was variously changed, sealed nickel-hydrogen storage batteries C1 to C9 were produced.
A cycle test was performed under the same conditions as described in the section of [Charge / Discharge Cycle Characteristics], and the discharge capacity at the 1001th cycle of each battery was examined. In addition, the amount of the electrolytic solution at the time of the activation treatment is set to 2.
75 cc, after activation (before start of charge / discharge cycle)
The battery C10 in which 0.75 cc of pure water was supplemented to
The discharge capacity at the 1001th cycle was examined. Table 2 shows the results.

[0031]

[Table 2]

As shown in Table 2, when the activation treatment was performed with an electrolyte amount of 35 to 80% by volume of the total electrolyte amount (3.50 cc) to be finally injected, the 1001 cycle Has a large discharge capacity of 0.95 to 1.02 Ah, but outside of this range, the discharge capacity decreases. This indicates that in order to obtain a battery having a long cycle life, it is necessary to perform the activation treatment with an electrolyte amount of 35 to 80% by volume of the total electrolyte amount.

After the activation treatment, 0.75 cc of pure water is added.
Since the discharge capacity at the 1001 cycle of the refilled battery C10 is 1.00 Ah, which is almost equivalent to the discharge capacity (1.02 Ah) of the battery C8 replenished with 0.75 cc of the electrolyte, in this case, after the activation treatment, It can be seen that the replacement fluid can be made of pure water.

[0034]

According to the present invention, since the activation treatment is performed with a part of the total amount of the electrolyte, the internal pressure of the battery hardly rises during charging in the activation treatment, and the hydrogen storage alloy electrode can be sufficiently activated. In addition, the remaining electrolyte or water is replaced after the activation treatment, so that the cycle life is not shortened.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a sealed nickel-hydrogen storage battery assembled in an example.

FIG. 2 is a graph showing a relationship between a charging capacity and a battery internal pressure during an activation process.

FIG. 3 is a graph showing cycle characteristics of the battery of the present invention and a comparative battery.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Nishio, Inventor 2-5-5, Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Toshihiko Saito 2-5-2, Keihanhondori, Moriguchi-shi, Osaka No. 5 Inside Sanyo Electric Co., Ltd. (56) References JP-A-51-38632 (JP, A) JP-A-61-7574 (JP, A) JP-A-61-7575 (JP, A) JP-A-59-7575 132574 (JP, A) JP-A-3-246871 (JP, A) JP-A-4-82170 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/30 H01M 10 / 44

Claims (2)

(57) [Claims] 1. A method for activating a sealed nickel-hydrogen storage battery having a hydrogen storage alloy electrode as a negative electrode, wherein the electrolyte corresponds to 35 to 80% by volume of the total electrolyte to be finally injected. An activation treatment method characterized by performing charge / discharge in an amount. 2. The activation treatment method according to claim 1, wherein charging and discharging are performed by partially or entirely replacing the gas inside the battery with oxygen gas and / or hydrogen gas.