JP3094041B2 - Nickel hydrogen secondary battery module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel-hydrogen secondary battery module.

[0002]

2. Description of the Related Art In recent years, a secondary battery module in which a plurality of secondary batteries are housed in a resin container has been frequently used as a power supply incorporated in electronic devices such as portable video and laptop computers. I have. Along with that, along with increasing the capacity of the secondary battery module,
It is required that the battery can be charged in a short time.

In order to meet the above demand for higher capacity, a nickel-metal hydride secondary battery having a battery capacity approximately twice as large as that of a nickel-cadmium secondary battery has been developed. A nickel-metal hydride secondary battery module has been proposed. Further, in order to meet the demand for charging in a short time, charging of the nickel hydride secondary battery module having a large capacity with a large current has been studied.

Incidentally, a secondary battery has a conversion efficiency of 100 from electric energy to chemical energy during charging.
%, And the unconverted portion becomes heat energy and is heated. In particular, as the charging proceeds, the conversion efficiency decreases, so that the battery is heated to a higher temperature. Even if the secondary battery is heated in this way, if the battery is charged alone,
Since the heat is directly radiated from the surface of the battery can to the outside air, the temperature rise of the battery can be suppressed to a level that does not cause any particular problem.

However, when the nickel-metal hydride secondary battery module is charged with a large current, a plurality of nickel-metal hydride secondary batteries are stored in the secondary battery module in close proximity, The temperature of the nickel-metal hydride secondary battery rapidly rises due to the heat insulation effect caused by the gap between the battery and the resin container.
As a result, the temperature breaker built into the nickel-metal hydride secondary battery module as a safety measure operates before full charge, resulting in poor charging. There is a problem that the reaction with the liquid at high temperature causes a reaction accompanied by corrosion, thereby shortening the battery life. For this reason, in the nickel-metal hydride secondary battery module, it is an important issue to suppress the temperature rise of the nickel-metal hydride secondary battery during charging.

In order to suppress the temperature rise of the nickel-metal hydride secondary battery at the time of charging in the nickel-metal hydride secondary battery module, a method of reducing the current value at the time of charging, and detecting the battery voltage and the battery temperature to charge the battery. A method of finely controlling the current value at the time has been proposed. However, these methods have not been essentially solved because of problems such as a long charging time and a very complicated charge control circuit.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and is intended to suppress a rise in temperature of a nickel-metal hydride secondary battery during charging. It is intended to provide a module.

[0008]

Means for Solving the Problems Nickel water according to the present invention
The elementary secondary battery module has a resin container and a
A plurality of nickel-metal hydride rechargeable batteries to be stored and a heat conductive part
In the nickel-metal hydride secondary battery module provided with a material, the heat conductive member is provided between the inner surface of the container and the nickel
Characterized in that it is filled in the gap with the hydrogen rechargeable battery
Things.

In the nickel-hydrogen secondary battery, for example, an electrode group in which a separator is interposed between a paste-type nickel positive electrode and a hydrogen-absorbing alloy negative electrode is housed in a battery can, and an alkaline electrolyte is further injected. One having a sealed structure is exemplified.

As the paste-type nickel positive electrode, a mixture having a composition in which a binder and, if necessary, cobalt oxide are blended with nickel hydroxide as an active material is formed on a conductive core as a current collector. Things.

Examples of the binder mixed in the positive electrode mixture include polyacrylates such as sodium polyacrylate and potassium polyacrylate, and carboxymethyl cellulose (CMC). It is desirable that the compounding ratio of the binder is in the range of 0.1 to 2 parts by weight based on 100 parts by weight of nickel hydroxide.

Examples of the conductive core of the positive electrode include those having a two-dimensional structure such as punched metal, expanded metal, and wire mesh, foamed metals, sintered substrates of metal fibers, and three-dimensional structures such as felt-like metal porous bodies. And the like.

The paste-type nickel positive electrode is prepared, for example, by kneading the above-mentioned nickel hydroxide, binder, cobalt oxide and the like in the presence of water to prepare a paste, applying the paste to the conductive core, and drying the paste. After that, it is manufactured by performing a roller press. Examples of the hydrogen storage alloy negative electrode include those in which a mixture having a composition of a mixture of a hydrogen storage alloy powder, a conductive material powder, and a binder is formed on a conductive core serving as a current collector.

The hydrogen storage alloy mixed in the mixture of the negative electrode is not particularly limited, and can store electrochemically generated hydrogen in an electrolyte and discharge the stored hydrogen during discharge. Any material that can be easily released may be used. For example, the general formula XY _5-a Z a (where, X is a rare earth element including La, Y is Ni, Z is Co, Mn, Al, Fe, T
At least one element selected from i, Cu, Zn, Zr, Cr, V, and B, and a represents 0 ≦ a <2.0) is used. Specifically, LaNi ₅ , Mm
Ni ₅ , LmNi ₅ (Lm; lanthanum-enriched misch metal), and a part of these Nis are Co, Mn, A
Examples thereof include multi-element-based materials that are substituted with elements such as 1, Fe, Ti, Cu, Zn, Zr, Cr, V, and B.

Examples of the conductive material powder mixed in the negative electrode mixture include carbon black, graphite, and acetylene black. The mixing ratio of the conductive material powder is desirably in the range of 0.1 to 4 parts by weight with respect to 100 parts by weight of the hydrogen storage alloy powder. A more preferable compounding ratio of the conductive powder is hydrogen storage alloy powder 10
It is in the range of 0.1 to 2 parts by weight with respect to 0 parts by weight.

Examples of the binder compounded in the mixture of the negative electrode include polyacrylates such as sodium polyacrylate and potassium polyacrylate, fluorine resins such as polytetrafluoroethylene (PTFE), and the like. Carboxymethyl cellulose (CMC) and the like can be mentioned. The compounding ratio of the binder is 10%.
It is desirable that the content is in the range of 0.1 to 5 parts by weight with respect to 0 parts by weight.

Examples of the conductive core of the negative electrode include those having a two-dimensional structure such as punched metal, expanded metal, and wire mesh, foamed metals, sintered substrates of metal fibers, and three-dimensional structures such as felt-like metal porous bodies. And the like.

The hydrogen storage alloy negative electrode is prepared, for example, by kneading the hydrogen storage alloy powder, conductive material powder, binder and the like in the presence of water to prepare a paste, and applying the paste to the conductive core. It is manufactured by performing a roller press after drying.

Examples of the separator interposed between the paste-type nickel positive electrode and the hydrogen storage alloy negative electrode include nonwoven fabrics made of synthetic resin such as nylon and polypropylene.

The heat conductive member is formed of a material having a fluidity such as silicone grease, silicone adhesive, grease mixed with silica filler, grease mixed with metal filler, etc., which has a higher thermal conductivity than air. be able to.

[0021]

According to the present invention, in a nickel-metal hydride secondary battery module in which a plurality of nickel-metal hydride secondary batteries are housed in a resin-made container, a heat conductive material is provided between the nickel-metal hydride secondary battery and the resin-made container. By filling the member,
Since the heat transfer between the nickel-metal hydride secondary battery and the resin container is improved and the heat of the nickel-metal hydride secondary battery is quickly released, the temperature rise of the nickel-metal hydride secondary battery during charging can be suppressed.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. Example 1

First, the composition is LmNi _4.0 Co _0.4 Mn.
A hydrogen storage alloy negative electrode was prepared by coating a conductive core with _0.3 Al _0.3 hydrogen storage alloy powder. Subsequently, the hydrogen-absorbing alloy negative electrode was wound with a paste-type nickel positive electrode having a theoretical capacity of 2300 mAh via a polypropylene separator to form an electrode group. Subsequently, after inserting the electrode group into the battery can, an alkaline electrolyte is injected and sealed. Thus, the utilization rate of the nickel positive electrode is 100% or more and the battery capacity is about 2400 m.
An A-size nickel-metal hydride secondary battery was assembled.

The following nickel-hydrogen secondary battery module was assembled using the obtained nickel-hydrogen secondary battery.
That is, FIG. 1 is an explanatory diagram showing the structure of the nickel-metal hydride secondary battery module of Example 1, and FIG. 2 is a circuit diagram of the nickel-metal hydride secondary battery module. 1 in the figure is thickness 2
It is a resin container made of an ABS resin plate of mm. In the resin container 1, six nickel-metal hydride rechargeable batteries 2 connected in series, a terminal 3 for connecting the nickel-metal hydride rechargeable batteries 2, a third battery 2 and a fourth A bimetal type temperature breaker 4 operating at a temperature of 72 ° C. interposed between the battery 2 and the battery 2 is housed. Inside of the resin container 1
The gap between the surface 6 and the nickel-metal hydride secondary battery 2 is filled with a heat conductive member 5 made of silicone grease (without metal filler). Example 2

A nickel-hydrogen secondary battery module similar to that of Example 1 was assembled except that a heat conductive member made of silicone grease mixed with 90% by volume of copper short fiber having a diameter of 50 μm and a length of 500 μm was used. Comparative Example 1 A nickel-hydrogen secondary battery module similar to that of Example 1 was assembled, except that the gap between the resin container and the nickel-metal hydride secondary battery was not filled with any heat-conductive member.

The battery modules of Examples 1 and 2 and Comparative Example 1 were completely discharged at 1 A, and then discharged at 1 C at 0.5 CmA.
A charging test for charging 50% was performed. As a result, the battery modules of Examples 1 and 2 could be charged 150% satisfactorily, but the battery module of Comparative Example 1 was charged poorly due to the operation of the temperature breaker at 120% charge.

In the above-described charging test, thermocouples were attached to the surface of the nickel-hydrogen secondary battery of each battery module and the outer surface of the resin container, respectively, and the temperatures were measured. As a result, in the battery modules of Example 1 and Comparative Example 1, the temperature of the surface of the nickel hydride secondary battery and the temperature of the outer surface of the resin container changed as shown in FIG. The temperature of the surface of the nickel-hydrogen secondary battery and the temperature of the outer surface of the resin container of the battery module of Example 2 showed changes similar to those of the battery module of Example 1. Further, Table 1 below shows the maximum temperature at the time of charging the surface of the nickel-hydrogen secondary battery and the outer surface of the resin container in the battery modules of Examples 1 and 2 and Comparative Example 1.

Table 1 Maximum temperature during charging Surface of nickel-metal hydride secondary battery Outer surface of resin container Example 1 68 ° C (at 150% charge) 58 ° C (at 150% charge) Example 2 62 ° C (150%) 58 ° C (at 150% charge) Comparative Example 1 79 ° C (at 120% charge) 59 ° C (at 120% charge)

As is clear from FIG. 3, the battery module of Example 1 has a smaller temperature rise of the nickel-metal hydride secondary battery than the battery module of Comparative Example 1, and the surface of the nickel-metal hydride secondary battery and the outer surface of the resin container. It can also be seen that the temperature difference between them is small. This is because the heat transfer between the nickel-metal hydride secondary battery and the resin container is improved, and the nickel-metal hydride secondary battery is quickly radiated. As is clear from Table 1, the battery modules of Examples 1 and 2 have a lower maximum temperature at the time of charging the nickel-metal hydride secondary battery than the battery module of Comparative Example 1.

In the above embodiment, the nickel-hydrogen secondary battery module accommodating a nickel hydrogen secondary battery of 4 / 3A size has been described. Similar effects were obtained with the battery module.

[0031]

As described above in detail, according to the present invention, it is possible to suppress the temperature rise of the nickel-metal hydride secondary battery during charging, and to obtain a highly reliable nickel-metal hydride battery which can be charged in a short time with a high capacity. A secondary battery module can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the structure of a nickel-metal hydride secondary battery module of Example 1.

FIG. 2 is a circuit diagram of a nickel-metal hydride secondary battery module of Example 1.

FIG. 3 is a characteristic diagram showing a temperature change on a surface of a nickel-metal hydride secondary battery and a temperature change on a resin container outer surface with respect to a charged amount in the battery modules of Example 1 and Comparative Example 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Resin container, 2 ... Ni-MH secondary battery, 5 ... Heat-conductive member.

Continuing on the front page (72) Katsuharu Ikeda 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Corporation (72) Inventor Yuji Sato 1st Kogashi Toshiba-cho, Kouki-ku, Kawasaki-shi, Kawasaki Toshiba Research Institute (56) References JP-A-3-88275 (JP, A) JP-A-3-77263 (JP, A) JP-A 55-132860 (JP, U) (58) Fields studied (Int .Cl. ⁷ , DB name) H01M 2/02-2/08 H01M 10/30 H01M 10/34 H01M 2/10

Claims (2)

(57) [Claims] 1. A resin container and housed in the container.
Equipped with a plurality of nickel-metal hydride secondary batteries and a heat conductive member
In the nickel-metal hydride secondary battery module, the heat conductive member includes an inner surface of the container and the nickel water.
A nickel-metal hydride secondary battery module, which is filled in a gap with an elementary secondary battery . 2. The heat conductive member has a metal filler mixed therein.
2. The grease according to claim 1, wherein said grease is made of grease.
Nickel-metal hydride secondary battery module.