JP4576785B2 - Battery and its electrode core material, positive electrode and negative electrode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery, an electrode core material thereof, a positive electrode, and a negative electrode.
[0002]
[Prior art and problems to be solved by the invention]
For example, in an electrode of a secondary battery, an active material powder is fixed to an electrode core material by a rolling process. The electrode core material receives electrons from the negative electrode active material, and the electrons work and are then passed to the positive electrode through the electrolytic solution. The battery functions as a result of this series of operations. However, since the active material fixed by the rolling process has a certain thickness, when considering each powder particle of the active material powder, there is a difference in the distance from each active material powder to the electrode core material. . That is, the quality of conditions for delivering and receiving electrons to the electrode core material occurs. Therefore, the problem that the current collection efficiency as the whole electrode will worsen arises. In particular, since the active material is often in the form of particles and the contact resistance of the particles is large, the influence of the distance to the electrode core material becomes large.
[0003]
The present invention has been made in view of the above-described problems, and an object of the present invention is to improve battery performance by improving the current collection efficiency of an electrode.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, as a first means related to an electrode core material of a battery, an electrode core material having a powdery active material fixed to a front surface and a back surface at a predetermined thickness, The tip of the protrusion provided on the surface of the active material is disposed so as to be exposed, and the protrusion has a hardness of 150 Hv (Vickers hardness) or less . As a result, the distance from the active material powder having poor conditions for transferring electrons from the electrode core material to the electrode core material is shortened, and the current collection efficiency of the entire electrode is improved. In addition, for example, it is possible to prevent damage to the insulating material due to the negative electrode active material rising to the tip of the protruding portion due to volume expansion during charging of the negative electrode active material. In addition, it is possible to prevent the tip of the protruding portion protruding due to volume shrinkage during discharge of the negative electrode active material from penetrating the insulating material.
[0005]
As a second means related to the electrode core material of the battery, in the first means, the protrusion is a burr having a hole provided by locally pressing from one or both surfaces of the electrode core material. Adopt the means. Thereby, the said protrusion part can be easily formed by providing the protrusion part set to the predetermined shape, for example to the roller which performs a rolling process.
[0007]
As first means according to the positive electrode of the battery, employing the means of securing the positive electrode active material on the surface and the back surface of the electrode core member in unit according to the first or electrode core member of the second battery. Thereby, the said electrode core material can be used as a positive electrode.
[0008]
As a second means relating to the positive electrode of the battery, a means is adopted in which, in the first means, the positive electrode active material is nickel hydroxide. Thereby, the said electrode core material can be used as a positive electrode of the secondary battery which can be charged.
[0009]
As a first means related to the negative electrode of the battery, employing the means of securing the anode active material on the surface and the back surface of the electrode core member in unit according to the electrode core member of the first or second battery. Thereby, the said electrode core material can be used as a negative electrode.
[0010]
As a second means related to the negative electrode of the battery, in the first means, a means is adopted in which the negative electrode active material is a hydrogen storage alloy. Thereby, the said electrode core material can be used as a positive electrode of the secondary battery which can be charged.
[0011]
As a first means relating to the battery, a means in which the positive electrode in the means relating to the first or second positive electrode is accommodated in the battery case in a state of being alternately laminated with the negative electrode with an insulating material interposed therebetween. adopt. Thereby, it is possible to constitute a small battery without causing the positive electrode to touch the negative electrode and causing a short circuit.
[0012]
As a second means according to the battery, housed in the first or second positive electrode positive electrode in means according to the inside it is wound spirally battery container in a state of kneaded heavy and negative electrodes sandwiching the insulating material Adopt the means that has been . Thereby, a positive electrode touches a negative electrode and an electrode can be accommodated in a cylindrical battery case, without short-circuiting.
[0013]
As a third means relating to the battery, a means in which the negative electrode in the means relating to the first or second negative electrode is accommodated in the battery case in a state of being alternately laminated with the positive electrode across the insulating material. adopt. Thereby, it is possible to constitute a small battery without the negative electrode touching the positive electrode and short-circuiting.
[0014]
As a fourth means according to the battery, housed in the first or the negative electrode in means according to the negative electrode 2 in being wound spirally battery container in a state of kneaded heavy and positive electrode across the insulating material Adopt the means that has been . Thereby, a negative electrode touches a positive electrode and an electrode can be accommodated in a cylindrical battery case, without short-circuiting.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with reference to the drawings, an embodiment of a battery according to the present invention and its electrode core material, a positive electrode, and a negative electrode will be described.
[0016]
FIG. 1 is a configuration diagram of an electrode E, (a) is a side view, and (b) is a front view. Reference numeral 1 is an electrode core, 1a is a burr, 1b is a through hole, 2 is an active material, and E is an electrode.
[0017]
The electrode core material 1 is, for example, a foil-like flat plate having a thickness of 50 μm, and an active material 2 is fixed to the front and back surfaces with a predetermined thickness. The burr (protrusion) 1a has a tip exposed at the surface of the active material 2, and a substantially rectangular through-hole (hole) provided by locally pressing from one or both surfaces of the electrode core material 1. ) It is formed so as to reach the surface of the active material 2 from the short side of 1b. Further, the hardness of the electrode core material 1 is set to 150 Hv or less, that is, the hardness of the burr 1a is formed to 150 Hv (Vickers hardness) or less. The through holes 1b are provided in the electrode core material 1 at predetermined intervals. The active material 2 is a negative electrode active material when the electrode E is used for the negative electrode E1, and a positive electrode active material when the electrode E is used for the positive electrode E2, and is applied to the front and back surfaces of the electrode core material 1 by rolling. It is fixed to a certain thickness. For example, when the electrode E is used in a nickel metal hydride battery, the negative electrode active material is a hydrogen storage alloy powder, and the positive electrode active material is a nickel hydroxide powder.
[0018]
FIG. 2 is a perspective view of the secondary battery B on which the electrode E in FIG. E1 is a negative electrode, E2 is a positive electrode, 3 is a separator (insulating material), 4 is a battery case (negative electrode terminal), 5 is a positive electrode terminal, and 6 is a sealing plate.
[0019]
The negative electrode E1 and the positive electrode E2 are wound in a multi-winding manner with the separator 3 interposed therebetween, and are accommodated in a cylindrical battery case (negative electrode terminal) 4, and the battery case 4 is filled with an electrolytic solution. An opening is formed at the upper end of the battery case 4, and the opening is sealed by a sealing plate 6 provided with a positive electrode terminal 5 at the center and insulated from the battery case 4. The negative electrode E1 is connected to the battery case 4, the positive electrode E2 is connected to the positive electrode terminal 5, and the negative electrode E1 and the positive electrode E2 constitute a series circuit through the electrolytic solution.
[0020]
Next, the effect | action of the battery in this embodiment, its electrode core material, a positive electrode, and a negative electrode is demonstrated.
[0021]
For example, in the case of the negative electrode E1, hydrogen storage alloy powder is used for the active material 2. Since the powder of the active material 2 located at the point A on the surface of the negative electrode E1 is closer to the electrode core material 1 than the case where the electrode core material 1 is not provided with the burr 1a, the point A This hydrogen storage alloy powder makes it easy to pass electrons to the burr 1 a, that is, the electrode core material 1. Conversely, at the point A ′ on the surface of the negative electrode E1 positioned symmetrically with respect to the electrode core material 1, the electrode core material 1 is compared with the case where there is no burr 1a because the electrode core material 1 is provided with the through-hole 1b. However, even if this point is taken into consideration, the current collection efficiency is improved when viewed from the negative electrode E1 as a whole. In general, the active material 2 is a powder, and since the resistance of the powder surface is large, the effect of having a conductor nearby increases. According to experiments, when the distance between one burr 1a formed in one substantially rectangular through hole 1b and the other burr 1a is about four times the thickness of the electrode, the current collection effect is improved by 10% or more. It recognized.
[0022]
However, in order to realize the above-described electrode configuration, the burr 1a needs to have a hardness of 150 Hv (Vickers hardness) or less. For example, in the case of the negative electrode E1, when the volume of the powder of the active material 2 expands due to the charging of the secondary battery B, if the hardness of the burr 1a is 150 Hv or more, the electrode core material 1 and the active material 2 Particles are poorly bonded and easily float on the surface of the electrode E, and the powder of the active material 2 that has floated loses its escape, enters between the burr 1a and the separator 3, breaks through the separator 3, and comes into contact with the positive electrode E2. As a result, a short circuit occurs in the secondary battery B. When the powder of the active material 2 contracts and expands due to repeated discharge of the secondary battery B, the tip of the burr 1a peeled off from the active material 2 gradually protrudes from the surface of the active material 2, and this burr 1a If the hardness of the battery is 150 Hv or more, the separator 3 is broken through, which similarly causes a short circuit in the secondary battery B. That is, by setting the hardness of the burr 1a to 150 Hv or less, the active material 2 expands, and even if it enters between the burr 1a and the separator 3, the burr 1a is deformed and breaks through the separator 3. Decrease. Further, even when the active material 2 contracts and the burr 1a protrudes from the surface of the active material 2, the breakage of the separator 3 due to the deformation of the burr 1a is reduced. In order to reduce the hardness of the burr 1a to 150 Hv or less, the electrode core material 1 is heat-treated, and the electrode core material 1 itself is processed to 150 Hv or less.
[0023]
FIG. 3 is a comparative table showing experimental results of how often a short circuit occurs in the secondary battery B depending on the type of material used for the electrode core material 1 and the difference in Vickers hardness. As shown in this figure, the frequency of occurrence of a short circuit in the secondary battery B is reduced when the hardness of the electrode core material 1 is either iron foil or nickel foil and the hardness is 150 Hv or less.
[0024]
Further, since the burr 1a is formed so as to reach the position where the burr 1a is exposed to the surface of the active material 2, the active material 2 that enters between the burr 1a and the burr 1a and is fixed to the electrode core 1 is The fixing force with respect to the electrode core material 1 is improved as compared with the conventional electrode. Therefore, it is possible to suppress peeling or dropping of the active material 2. Therefore, even when stress is applied to the negative electrode E1 by winding the negative electrode E1 and the positive electrode E2 with the separator 3 interposed therebetween in order to assemble the secondary battery B set in the cylinder of FIG. The active material 2 can maintain the state of being more firmly fixed to the electrode core material 1.
[0025]
In the present embodiment, the electrode core material 1 on which the burr 1a is formed is used for the negative electrode E1 in the above embodiment, but may be used for the positive electrode E2. In this case, for example, the active material 2 uses nickel hydroxide. In addition, the electrode core material 1 may be provided with a protruding portion having current collecting properties from the outside without providing the burr 1a.
[0026]
In the above-described embodiment, the flat electrode core material 1 is used. However, for example, the electrode core material 1 curved in a direction perpendicular to the direction in which the electrode E is wound may be used. Even in this case, the burr 1a is formed so as to reach the surface of the active material from the through hole 1b.
Further, the through hole 1b is not substantially rectangular, and may be, for example, substantially square or substantially elliptical.
[0027]
【The invention's effect】
As described above, according to the present invention, an electrode core material in which a powdery active material is fixed to a front surface and a back surface with a predetermined thickness, and a tip of a protrusion provided on the electrode core material is formed of the active material. Since it is installed exposed on the surface and the protruding portion has a hardness of 150 Hv (Vickers hardness) or less, the distance from the active material powder having poor conditions for transferring electrons from the electrode core material to the electrode core material is short. Thus, the current collection efficiency of the entire electrode is improved. In addition, for example, it is possible to prevent damage to the insulating material due to the negative electrode active material rising to the tip of the protruding portion due to volume expansion during charging of the negative electrode active material. In addition, it is possible to prevent the tip of the protruding portion protruding due to volume shrinkage during discharge of the negative electrode active material from penetrating the insulating material.
[Brief description of the drawings]
1A and 1B are configuration diagrams of an electrode E according to an embodiment of the present invention, in which FIG. 1A is a side view and FIG. 1B is a front view.
FIG. 2 is a perspective view of a secondary battery B having a cylindrical shape according to an embodiment of the present invention.
FIG. 3 is a comparison diagram of the frequency of occurrence of a short circuit in the secondary battery B due to the difference in material of the electrode core material 1;
[Explanation of symbols]
1 …… Electrode core material 1a …… Burr (protrusion)
1b: Through hole (hole)
2 …… Active material 3 …… Separator (insulating material)
4. Battery case (negative electrode terminal)
5 ... Positive terminal 6 ... Sealing plate E1 ... Negative electrode E2 ... Positive electrode B ... Secondary battery

Claims (10)

An electrode core material in which a powdered active material is fixed to a front surface and a back surface with a predetermined thickness,
An electrode core material, characterized in that a tip of a protruding portion provided on the electrode core material is disposed so as to be exposed on the surface of the active material, and the protruding portion has a hardness of 150 Hv (Vickers hardness) or less .     2. The electrode core material according to claim 1, wherein the protruding portion is a burr provided in a hole provided by locally pressing from one or both surfaces of the electrode core material. 3. A positive electrode, wherein a positive electrode active material is fixed to the front and back surfaces of the electrode core material according to claim 1 or 2. The positive electrode according to claim 3, wherein the positive electrode active material is nickel hydroxide. A negative electrode, wherein a negative electrode active material is fixed to a front surface and a back surface of the electrode core material according to claim 1. The negative electrode according to claim 5, wherein the negative electrode active material is a hydrogen storage alloy. 5. A battery, wherein the positive electrode according to claim 3 or 4 is accommodated in a battery case in a state where the positive electrode is alternately laminated with a negative electrode with an insulating material interposed therebetween. A battery, wherein the positive electrode according to claim 3 or 4 is spirally wound in a state where the positive electrode is overlapped with the negative electrode with an insulating material interposed therebetween and accommodated in a battery case. A battery characterized in that the negative electrode according to claim 5 or 6 is accommodated in a battery case in a state of being alternately laminated with a positive electrode with an insulating material interposed therebetween. A battery characterized in that the negative electrode according to claim 5 or 6 is spirally wound in a state of being overlapped with the positive electrode with an insulating material interposed therebetween and accommodated in a battery case.

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