JPH08153543A - Forming method of sealed alkaline storage battery - Google Patents

Abstract

PURPOSE: To provide a sealed alkaline storage battery in which the utilization factor of a positive electrode is not lowered even when overcharge or reverse charge is performed and the capacity can be recovered by the next charge and discharge. CONSTITUTION: This sealed alkaline storage battery is provided with a negative electrode containing a hydrogen storage alloy as a main component, a positive electrode containing a nickel hydroxide as a main component, an electrolyte and a separator as constituent materials. An initial charge in the operation of the initial activating charge and discharge is performed on condition that a charging current is within the range of 0.02CmA to 0.03CmA and battery capacity is within the range of 10% to 30% and after that, the charge is performed on condition that a charging current is within the range of 0.1CmA to 1.0CmA and battery capacity is within the range of 120% to 150%, and the original capacity is recovered in the next charge and discharge by the forming method of a sealed alkaline storage battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed alkaline storage battery, and more particularly to an improvement in the chemical conversion method for a battery using a paste type nickel positive electrode plate.

[0002]

2. Description of the Related Art Today's portable devices have made remarkable progress, and the batteries used in these devices are required to have high energy density. Therefore, nickel-cadmium batteries, which have been used conventionally, are replaced by light-weight and high-performance batteries. A nickel-metal hydride battery with a large capacity is drawing attention.

Compared with conventional nickel-cadmium batteries,
This nickel-hydrogen storage battery has a high energy density, that is, a high capacity, and is incorporated in a portable device as an assembled battery in which a plurality of batteries are connected in series or in parallel. Some portable devices have a small current even when the power is off.
Some so-called dark currents flow. When a dark current flows for a long time, a battery with a small battery capacity falls into a reverse charge state among the assembled batteries. In this case, the battery once in the reverse charge state may not recover even after repeating charging and discharging several times. The reason for not recovering was that the conductive path of cobalt oxyhydroxide (CoOOH) formed in the paste type positive electrode was broken and the utilization rate of the positive electrode was lowered.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a sealed alkaline storage battery in which the utilization factor of the positive electrode does not decrease even if it is over-discharged or reversely charged, and the capacity can be recovered by subsequent charging / discharging. .

[0005]

In order to solve this problem, the present invention is directed to the formation of a conductive network by oxidizing cobalt monoxide added to the positive electrode active material by performing initial charge in a charge / discharge operation with a minute current. It secures the formation and solidifies the fixing of cobalt oxyhydroxide (CoOOH) in the positive electrode.

[0006]

Function: Cobalt monoxide added in the positive electrode active material dissolves in an alkaline solution to form cobalt complex ions. By firmly fixing this cobalt complex ion between the particles of the positive electrode active material and between the particles of the positive electrode active material and the particles of the positive electrode active material with a current caused by a slight current, even if an overcharge or a reverse charge occurs, The original capacity is restored by charging and discharging.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a front view and a plan view of a small angle sealed nickel-metal hydride storage battery showing an embodiment of the present invention.

The battery of this example is equipped with the following positive electrode, electrolytic solution, separator and negative electrode as constituent materials.
It is of the 00 mAh type. For the positive electrode, high density nickel hydroxide powder in which zinc was solid solution was added with cobalt monoxide 5
A nickel substrate having a three-dimensional mesh structure is filled in a paste form by adding the resin in a weight percentage, and the separator is made of a polyamide nonwoven fabric. The electrolyte is 6
It consists of normal potassium hydroxide and 0.5 normal lithium hydroxide. The negative electrode is made of a paste of MmNiAlCo alloy powder, which is a hydrogen storage alloy,
Nickel Filling a nickel substrate with a three-dimensional network structure,
After inserting into a square metal case, about 4.5 ml of 6N potassium hydroxide and 0.5N lithium hydroxide
The solution was poured and sealed with a sealing plate equipped with a safety valve and a positive electrode terminal to form a square 3000 mAh nickel-hydrogen battery shown in FIG. Next, this battery was left in an atmosphere of room temperature of 25 ° C. for 24 hours or more, charged with a current having a nominal capacity of 0.03 CmA for 5 hours, and then continuously charged with a current of 0.1 CmA for 15 hours. The battery was discharged at a current of 1 CmA to 1.0 V / cell.

Next, the battery was charged with a current of 0.03 CmA for 1 hour, then charged with a current of 0.1 CmA for 15 hours, then discharged with a current of 0.2 CmA to a voltage of 1.0 V / cell, and initial activation charge / discharge. The operation was performed. Next, 8 cells of this battery were connected in series, charged at a current of 0.3 CmA for 4 hours at room temperature of 25 ° C., and then discharged to a voltage of 1.0 V at a current of 0.2 CmA to obtain an initial capacity.

The battery was connected to a resistance of 16.5 ohms for 3 days to over discharge the battery. After that, when the capacity of this battery was confirmed by the above-mentioned method of obtaining the initial capacity,
A capacity of 97% of the initial capacity was obtained. These operations were repeated 5 times, but it was confirmed that the capacity decreased only to 95% of the initial capacity.

FIG. 3 shows the state of capacity recovery after over-discharging when the initial charge was performed at a nominal capacity of 0.1 CmA for 20 hours and then discharged at 1 CmA to 1.0V. As is clear from FIG. 3, the capacity recovery rate in the first cycle was 91%, and it decreased to 86% in the third cycle. That is, the charging current of the first charging according to the present invention is 0.0
Charging at 17% or more of the nominal capacity at 3 CmA or less shows a remarkable effect on capacity recovery after overdischarging.

[0012]

As described above, in the initial activation charging / discharging operation method in the nickel-hydrogen storage battery using the hydrogen storage alloy, the simple operation of only performing the initial charging with a small current,
Greatly improved and great industrial value.

[Brief description of drawings]

FIG. 1 is a front view of a sealed nickel-metal hydride storage battery according to an embodiment of the present invention.

FIG. 2 is a plan view of the sealed nickel-metal hydride storage battery according to the present invention viewed from the direction of the arrow in FIG.

FIG. 3 is a diagram showing a capacity recovery rate after overdischarge of a sealed nickel-hydrogen storage battery according to the present invention and a capacity recovery rate after overdischarge by a conventional method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Yufufu 6-6 Josaimachi, Takatsuki City, Osaka Prefecture Yuasa Corporation

Claims (1)

[Claims] 1. A negative electrode containing a hydrogen storage alloy as a main component, and a positive electrode containing nickel hydroxide as a main component,
A sealed alkaline storage battery comprising an electrolytic solution and a separator as constituent materials, wherein initial charging in initial activation charging / discharging operation is 0.02 CmA to 0.03 of charging current.
Perform 10% to 30% of the battery capacity in the range of CmA, and then 120 to 120% of the capacity at a current of 0.1 CmA to 1.0 CmA.
A method for forming a sealed alkaline storage battery, which is characterized by charging 150%.