JPH04329265A - Open type alkaline storage battery - Google Patents

Abstract

PURPOSE:To enable the use under the normal condition for a long time without lowering voltage even in the case that charge/discharge cycle is repeated at a deepened discharge depth by making a real capacity of a negative electrode 1.2 times of a real capacity of a positive electrode. CONSTITUTION:In an open type alkaline storage battery, a desired nor of positive electrode plates and negative electrode plates filled with the active material are laminated on a plate substrate, and charge/discharge is performed at a discharge depth deepened to 100% or near 100%. When capacity of the positive and negative electrode plates is showed with real capacity, which is showed with a formula I, a real capacity of the negative electrode is made 1.2 times of a real capacity of the positive electrode. Open type alkaline storage battery, of which voltage lowering is remarkably small and of which lifetime is long and which has the excellent performance at the time of quick discharge even if charge/discharge cycle is repeated at 100 % of discharge depth, is thereby obtained.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to the improvement of open-type alkaline storage batteries, and in particular to the improvement of open-type alkaline storage batteries, which can withstand a long life without voltage drop even when repeatedly charged and discharged at or near 100% depth of discharge. This is an open type alkaline storage battery.

0002

[Prior Art] In general, sealed alkaline storage batteries and open alkaline storage batteries are known for alkaline storage batteries. Sealed alkaline storage batteries absorb and consume oxygen or hydrogen gas generated in the rechargeable battery. An overcharge protection design is being carried out in which the amount of either the positive electrode active material or the negative electrode active material is increased. However, in open-type alkaline storage batteries, the amount of electrolyte is increased and measures are taken to prevent absorption and consumption of gas, which is the opposite of that in closed-type alkaline storage batteries. As a preventive treatment for this, for example, the actual capacities of the positive electrode and the negative electrode are made to be equal when expressed by the following formula. Actual capacity = theoretical capacity x utilization rate x maintenance rate Note that the retention rate is a correction value that compensates for changes in capacity due to aging, and was set to 1.1.

When repeatedly charging and discharging the positive and negative electrodes obtained in this way, there is no particular problem as long as the depth of charge is shallow, such as 70 to 80%, but if the depth of discharge is 100% or 100%, there is no particular problem. It is required to perform the process at a depth close to %. The reason for this is that by increasing the depth of discharge, the capacity of the storage battery can be fully demonstrated. However, on the other hand, since charging and discharging are performed under harsh conditions, the cycle life is shortened, and there is a problem that the battery cannot be used for a long period of time.

0004

[Problems to be Solved by the Invention] The present invention has been made as a result of intensive research in view of the current situation.Even when the depth of discharge is deepened and charge/discharge cycles are repeated, the voltage does not drop and remains in a normal state for a long period of time. We have developed an open-type alkaline storage battery that can be used in

[0005]

[Means for Solving the Problems] The present invention comprises stacking a desired number of positive electrodes and negative electrodes filled with active materials on an electrode plate substrate, and performing charging and discharging by increasing the depth of discharge to 100% or close to 100%. The open-type alkaline storage battery is characterized in that, when the capacity of the positive and negative electrode plates is expressed by the actual capacity shown in the following formula, the actual capacity of the negative electrode is 1.2 times or more the actual capacity of the positive electrode. Actual capacity = theoretical capacity x utilization rate x maintenance rate

[0006]

[Function] As mentioned above, carrying out the discharge at 100% or near 100% means making the discharge as deep as possible, and after discharging to such a state, charging again. This is what we do. Therefore, the electrode plates in alkaline storage batteries are made of a sintered substrate filled with active material.
The utilization rate is different between the positive electrode and the negative electrode.

That is, the active material utilization rate of the positive electrode plate is usually 98 to 100%, depending on the thickness and filling amount of the electrode plate. On the other hand, the active material utilization rate of the negative electrode plate is usually 70 to 75%, although it is influenced by the same factors as the positive electrode plate. Therefore, it is shown that the utilization rate of the positive electrode plate is 25 to 30% higher than the utilization rate of the negative electrode plate.

[0008] The theoretical capacity of the active material used to calculate the actual capacity in the above equation means that the active material of the positive electrode is usually nickel hydroxide (Ni(OH)2), and the active material of the negative electrode is usually nickel hydroxide (Ni(OH)2). Cadmium (Cd(OH)2) is used, and when their theoretical capacities are measured, the capacity per unit g of the positive electrode is 0.289Ah/g, and the capacity per unit g of the negative electrode is 0. .366Ah/g.

In the present invention, the filling ratio of the active material between the positive electrode and the negative electrode is set to 1:1.20 or more, and the actual capacity of the negative electrode is equal to or higher than that of the positive electrode, so that the positive electrode is The capacitance of becomes 0 before the capacitance of the negative electrode.
It was designed so that Note that 1. at the negative electrode.
Although the upper limit of 20 or more is not particularly limited, it is preferably in the range of 1.0 for the positive electrode and 1.20 to 1.5 for the negative electrode.

0010

[Example] Nickel sintered substrate filled with active nickel hydroxide, thickness 0.17mm, height 950mm, width 550mm
mm positive electrode plate (capacity per unit g 0.289Ah/g)
8 sheets and 9 negative electrode plates each having a thickness of 0.81 mm, a height of 950 mm, and a width of 550 mm (capacity per unit g of 0.366 Ah/g) filled with an active material of cadmium hydroxide on the above substrate as a gas barrier. Cellophane sandwiched between nylon cloth was used as a separator, and the negative electrode plate was provided on both sides, and a pole pole was attached to the stacked electrode plate group, and this was stored in a stainless steel container, and the ratio was 1.24. An open type alkaline storage battery of the present invention having a nominal capacity of 12 Ah was obtained by injecting a potassium hydroxide electrolyte of 100 ml. Further, the amount (g) of active material required in the above positive electrode and negative electrode was calculated using the following formula. 12
Positive electrode =
×1.1=46.6g
0.289×0.98 Amount per positive electrode = 5.8g
12
Negative electrode = (
×1.1)×1.2=61.8g
0.366×0.7
In addition, in the above formula (1), the value of 12 in the numerator is the battery capacity. (2) 1.2 of the negative electrode indicates the magnification of the actual capacity of the negative electrode. (3) 1.1 for the positive and negative electrodes indicates the maintenance rate.

In addition, in order to compare with the open type alkaline storage battery of the present invention, a comparative open type alkaline storage battery having a nominal capacity of 12 Ah was prepared in the same manner as in the example except that only the negative electrode was calculated using the following formula. 12
Negative electrode =
×1.1=51.5g
0.366×0.7

The alkaline storage battery of the present invention and the alkaline storage battery of the comparative example thus obtained were charged at 120% at a current of 2.4A at a discharge end voltage of 1.0V at a current of 12A, and the number of cycles and voltage were determined. We measured the relationship between The results are shown in FIG.

[0013]

Effects of the Invention: According to the open type alkaline storage battery of the present invention, even when charging and discharging cycles are repeated at a depth of discharge as deep as 100%, the voltage drop is extremely small and the battery has a long life, and is excellent in rapid discharge. It has good performance and is industrially useful.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the relationship between the number of charge/discharge cycles and voltage.

Claims (1)

[Claims] 1. An open-type alkaline storage battery in which a desired number of positive and negative plates filled with an active material are stacked on an electrode plate substrate, and charging and discharging are performed at a depth of discharge of 100% or close to 100%. , an open type alkaline storage battery characterized in that, when the capacity of the positive and negative electrode plates is expressed by the actual capacity shown in the following formula, the actual capacity of the negative electrode is 1.2 times or more the actual capacity of the positive electrode. Actual capacity = theoretical capacity x utilization rate x maintenance rate