JP2001216997A - Spiral electrode group for battery and battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral electrode group for a battery which is improved in weight and volume energy densities as much as possible and a battery using the electrode group to improve the discharging characteristics. SOLUTION: One electrode plate 11 located inward of winding has active material layer non-formed portions 11c, 11d, to which a core body 11a is exposed with no active material layer 11b formed, provided on the inner face side of the core body 11a equivalent to one round at starting winding and on the outer face side of the core body 11a equivalent to one round at ending winding. The other electrode plate 12 located outward of the winding has active material layers 12b formed on the whole faces of both sides of a core body 12a having a length such that it terminates one-round shorter than one electrode plate 11. A pair of separators 3, 3 are set at lengths such that they terminate at the same position somewhat passing through the other electrode plate 12 where it terminates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween and a band-like electrode group is spirally wound. The present invention relates to a spirally wound electrode group used for a non-aqueous electrolyte battery and a prismatic non-aqueous electrolyte battery formed using the spiral electrode group.

[0002]

2. Description of the Related Art In recent years, portable and cordless electric devices such as AV devices, personal computers, and portable communication devices have been rapidly promoted. Conventionally, nickel cadmium batteries and nickel-metal hydride batteries have been mainly used as power sources for driving these electric devices. In recent years, however, lithium batteries which can be rapidly charged, have a high energy density, and have high safety have been used in recent years. Non-aqueous electrolyte (organic solvent-based electrolyte) batteries typified by (1) are becoming mainstream. In this non-aqueous electrolyte battery, it is promoted to be a sealed type having a high energy density and excellent load characteristics, and a square shape suitable for thinning of equipment and effective in using each space. Further, with the advancement of the performance and functions of portable electric devices, these batteries are required to have higher voltage and higher capacity. In general, a structure in which a positive electrode plate and a negative electrode plate are formed using a spiral electrode group formed by spirally winding a band-like electrode group in which a separator is interposed between the positive electrode plate and the negative electrode plate is widely used. ing.

Further, in a non-aqueous electrolyte battery using the above-mentioned spiral electrode group, a higher capacity is promoted by increasing both the weight energy density and the volume energy density of the battery. FIG. 3 shows before and after winding of positive and negative electrode plates 1 and 2 and a pair of separators 3 and 3, which are components of a spiral electrode group used in such a rectangular battery having a high capacity. FIG. 4 is a cut-away side view showing the relative positional relationship of FIG. In FIG. 1, a positive electrode plate 1 is formed by forming a positive electrode active material layer 1b formed by applying a positive electrode active material, rolling, and drying the both surfaces of a band-shaped positive electrode core 1a generally made of aluminum foil. ing. The negative electrode plate 2 is formed by forming a negative electrode active material layer 2b formed by applying a negative electrode active material, rolling and drying the negative electrode active material on both surfaces of a strip-shaped negative electrode core 2a generally made of copper foil.

The two electrode plates 1 and 2 are arranged such that the negative electrode plate 2 is located on the inner side of the winding, and the separators 3 and 3 are interposed therebetween.
In a state in which the separators are interposed, the pair of cores 4, 4 are wound by sandwiching the respective start ends of the separators 3, 3 from both sides and rotating in the direction of the arrow shown in FIG. As shown in the plan view, after the flat spiral electrode group 7 is formed, it is inserted into the battery case 8. The spiral electrode group 7 constitutes a power generation element of the battery together with a non-aqueous electrolyte (not shown) injected into the battery case 8.

[0005] Incidentally, in FIG. 3, R ₀ to R _11, a pair of the core 4, 4 indicates the winding order of the length component wound around every half turn. The pair of winding cores 4 and 4 are slightly displaced from each other for the purpose of facilitating removal of the spirally wound electrode group 7 from the winding cores 4 and 4. The lengths R _{1 to} R ₁₁ corresponding to half the circumference of the spiral wound when the core 4 rotates a half turn correspond to the distance between the outer ends of the cores 4. FIG. 4 shows a spiral electrode group 7.
Are schematically illustrated so that the configuration of the winding start portion and the winding end portion can be easily understood, and it is considerably different from the actual form. For example, FIG.
The electrode plates 1 and 2 and the separators 3 and 3 are shown apart from each other without being tightened, and the space between the spiral electrode group 7 and the battery case 8 is not shown. For the sake of convenience, the gap is different from the actual one.

The spiral electrode group 7 has the following configuration in order to increase both the weight energy density and the volume energy density of the battery. In other words, the negative electrode plate 2 is provided with an active material non-formed portion 2c in which the negative electrode core 2a is exposed without forming the negative electrode active material layer 2b on the inner surface of a portion corresponding to one round of the winding start side, and the positive electrode The plate 1 has a positive electrode active material layer 1 on the outer surface side of a portion corresponding to one round of the winding end side.
An active material non-formed portion 1c where the positive electrode core 1a is exposed without forming b is provided.

This is because, as is apparent from FIG. 4, active material layers 2b, 1b having opposite polarities for chemically reacting with the active material non-formed portions 1c, 2c are provided on the sides opposed to each other with the separator 3 interposed therebetween. Therefore, each active material unformed portion 1c,
The active material layers 1b and 2b are provided on the cores 1a and 2a, respectively.
Is formed, the active material layers 1b and 2b not only become unnecessary and do not participate in charge / discharge at all, but also the power generating element becomes thicker by the thickness of the unnecessary active material layer, and the weight energy as a battery is reduced. This is because the density and the volume energy density are reduced. As a result, the spiral electrode group 7 increases the lengths of the two electrode plates 1 and 2 by the amount of the unnecessary active material layer removed from the battery case 8 having a fixed volume, or the active material layer 1b,
By increasing the thickness of 2b, the capacity can be increased.

In the spiral electrode group 7, the negative electrode lead 10 is attached to the negative electrode core 2a protruding from the winding start end of the negative electrode plate 2, and the positive electrode protruding from the winding end end of the positive electrode plate 1. Positive electrode lead 9 on core 1a
Is installed. On the other hand, in the previous spiral electrode group, the lead was attached to the part where each of the active material layers of the positive electrode and the negative electrode was cut off, or the lead was directly caulked to the active material layer and attached. The attached positive and negative leads are disposed opposite to the active material layers having the opposite polarities, and the capacitance is reduced by that amount. Such a disadvantage is solved in the spiral electrode group 7. I have.

Further, in the past, after the separator was inserted through the slit of the winding core and wound about twice, the positive and negative electrode plates were fed and spirally wound. There was a useless part. On the other hand, in the spiral electrode group 7, at the end of the winding step, the two separators 3 and 3 are overlapped with tension applied, and the same positions are simultaneously cut with a cutter, and the next winding is performed. In the process, two separators 3, 3
And the negative electrode plate 2 in which the same cut portions are aligned.
And the negative electrode core 2a provided with the negative electrode lead 10 is wound between the pair of winding cores 4 and 4, so that the waste of the separators 3 and 3 at the winding start portion is reduced. In addition, 2
The reason why the separators 3 and 3 are cut at the same position is that
If the cutting is performed at different positions, the winding start ends of the two separators 3 and 3 are not uniform, and the winding operation by the winding cores 4 and 4 becomes very difficult in view of the configuration of the apparatus. The positive and negative electrode plates 1 and 2 are cut into a predetermined length before winding.

[0010]

By the way, in the above-mentioned non-aqueous electrolyte battery, the battery case 8 is generally formed of aluminum and configured as the positive electrode side of the battery.
The battery case 8 is made of aluminum.
When stainless steel, which has been used as a material for the battery case of this type of battery for a long time, dissolves as iron ions in the stainless steel during long-term storage, and if this dissolution reaction continues, corrosion This is because there is a drawback. On the other hand, aluminum is less soluble than stainless steel, so that corrosion can be prevented, and the specific gravity is small, so that there is an advantage that the weight energy density as a battery can be improved with weight reduction. . In addition, the positive electrode core 1
The reason why aluminum is used as the material a is that the weight energy density can be improved as the weight is reduced.

Therefore, the positive electrode core 1a exposed in the active material non-formed portion 1c located at the outermost periphery of the positive electrode plate 1 in the spiral electrode group 7 is made of the same metal and the same positive electrode as the battery case 8 Not only does not cause any inconvenience even if it comes into contact with the inner peripheral surface of the battery case 8, but also makes one round of the exposed positive electrode core 1 a contact the inner peripheral surface of the battery case 8. Is remarkably large and a good electrical connection can be obtained, so that efficient current collection is possible and discharge characteristics can be remarkably improved.

However, in the spiral electrode group 7,
As described above, it is necessary to cut each end of the two separators 3 at the same position from the viewpoint of manufacturing, and the positive electrode plate 1 is placed between the outermost peripheral portions of the separators 3. , The end of each of the separators 3 must be set to a position beyond the end of the positive electrode plate 1 without stopping. Therefore, in the battery using the spiral electrode group 7, not only the positive electrode core 1 a of the active material non-formed portion 1 c cannot be brought into contact with the inner peripheral surface of the battery case 8, but also the outermost peripheral portion of the outer separator 4. One or more rounds are completely unnecessary and do not perform any function, and the amount of the active material layers 1b and 2b is reduced by the volume of the useless unnecessary portion 3a of the separator 4. Has a low volume energy density. In the above battery, the positive electrode core 1a of the active material non-formed portion 1c is connected to the battery case 8
The positive electrode lead 9 is electrically connected to the sealing plate (not shown) by laser welding, but sufficient discharge characteristics are obtained due to poor current collection efficiency. I can't.

Apart from the above, the positive electrode core body exposed by dropping the outermost circumference of the positive electrode active material layer in the outermost circumference of the positive electrode plate is brought into contact with the inner peripheral surface of the aluminum battery case of the positive electrode. A non-aqueous electrolyte battery has been proposed (see JP-A-6-63025). However, in this non-aqueous electrolyte battery, the spirally wound spiral electrode group is inserted into a rectangular or oblong battery case while forcibly deforming it into a flat shape, so that the exposed positive electrode core and the battery are exposed. It merely discloses a technique in which the inner peripheral surface of the case is brought into electrical connection with a contact pressure increased by a restoring force for returning the spiral electrode group to a circular shape. That is, since the above-mentioned publication does not disclose any specific relationship with the configuration for increasing the volume energy density and the weight energy density of the spiral electrode group, the spiral configuration having the configuration for increasing the capacity as much as possible is not disclosed. It is not possible to realize a battery that can obtain improved discharge characteristics while using an electrode group.

In view of the above, the present invention has been made in view of the above-mentioned conventional problems, and uses a spiral electrode group for a battery and a group of the spiral electrodes for a battery in which the weight energy density and the volume energy density are improved as much as possible. It is an object of the present invention to provide a battery having a structure capable of improving discharge characteristics.

[0015]

In order to achieve the above object, a spiral electrode group for a battery according to the present invention comprises: a positive electrode plate having a positive electrode active material layer formed on both sides of a belt-like positive electrode core; A negative electrode plate in which a negative electrode active material layer is formed on both surfaces of the negative electrode core, and a negative electrode plate that is spirally wound with a separator interposed therebetween; Wherein the active material layer is not formed on the inner surface side of the core body for at least one round of the winding start and the outer surface side of the core body for at least one round of the winding end. Is provided with an active material layer unformed portion having an exposed portion, and the other electrode plate located on the outer side of the winding is set to a length having an end at a position shorter than the one electrode plate by at least one turn. The active material layer is formed on both surfaces of the core body thus formed, and a pair of the separators is formed. Over others, it is characterized in that it is set to one another the same length having an end at substantially the same the same position as the end of the other electrode plate.

In this spiral electrode group for a battery, the active material layer of the other electrode for performing a chemical reaction does not exist in a portion of one electrode plate facing the two active material non-formed portions. The structure is such that unnecessary active material layers that are not involved at all are deleted at all. Further, since the outermost circumference is formed by the active material non-formed portion of one of the electrode plates, if the battery case has the same polarity as the one electrode plate, it is exposed in the active material non-formed portion. One core of one of the poles can be brought into contact with the inner peripheral surface of the battery case. for that reason,
Since both the other electrode plate and the pair of separators can be shortened by about one turn with respect to one electrode plate, a pair of separators that need to be cut at the same position due to manufacturing restrictions are It is possible to set the same position just before the end by one round as the end. As a result, both separators can be shortened by a total of two turns as compared with the conventional one, and the thickness or length of the positive and negative electrode active material layers can be set to be larger by the amount of the separator being shortened. Therefore, the weight energy density and the volume energy density of the battery can be increased.

In the above invention, it is preferable that the one electrode plate is a positive electrode plate having an aluminum positive electrode core. This makes it possible to insert the positive electrode core body into the same inner peripheral surface of the same-polarity battery case with the same metal as that of the non-aqueous electrolyte battery. Electrical connection can be obtained. In addition, since aluminum foil generally used as a positive electrode core has low strength and is easy to stretch or cut, it is very difficult to form an intermittent positive electrode active material-free portion. However, two positive electrode active material non-formed portions, each having the same length for one round, are formed at the winding start portion and the winding end portion on opposite sides of the positive electrode core body. The material-unformed portion can be easily formed by utilizing a retardation coating method, which is a new coating technology established in recent years.

In the battery according to the present invention, the spiral electrode group for a battery according to the present invention is inserted into a battery case forming one of the electrodes, and the active material is not formed on one of the electrode plates located at the outermost periphery. The battery is characterized in that at least one circumference of the exposed part of the core is brought into contact with the inner peripheral surface of the battery case.

In this battery, a large contact area for electrical connection is secured by contact between the core of one circumference of one of the electrode plates and the inner circumferential surface of the battery case. Since electrical connection is obtained, the chemical energy generated inside the battery can be efficiently collected as electric energy, and the discharge characteristics are significantly improved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a relative positional relationship before winding of positive and negative electrode plates 11 and 12 and a pair of separators 3 and 3, which are components of a spiral electrode group 13 according to an embodiment of the present invention. FIG. 4 is a cut-away side view in which the same or equivalent components as those in FIG. 3 are denoted by the same reference numerals. The positive electrode plate 11 is formed by forming a positive electrode active material layer 11b formed by applying a positive electrode active material on both sides of a strip-shaped positive electrode core 11a made of aluminum foil, and then rolling and drying. The plate 12 is formed by coating a negative electrode active material on both sides of a strip-shaped negative electrode core 12a made of copper foil, and then forming a negative electrode active material layer 12b formed by rolling and drying.

The spiral electrode group 13 is exemplified by one inserted into an aluminum battery case 8 constituting the positive electrode of the battery. The positive electrode plate 11 having the same polarity as the battery case 8 is connected to the negative electrode plate 12. On the other hand, it differs from FIG. 3 in that it is arranged on the inner side of the winding. In the positive electrode plate 11, the positive electrode core 11a was exposed without forming the positive electrode active material layer 11b on the inner surface side of a portion corresponding to one round on the winding start side and on the outer surface side of a portion corresponding to one round on the winding end side. Active material unformed portions 11c, 11d
Are provided respectively. On the other hand, the negative electrode plate 12
No active material-unformed portion is provided. Also, the negative electrode plate 1
2, a negative electrode lead 10 is attached to a negative electrode core 12a protruding from the winding start end.
The positive electrode lead 9 is attached to the positive electrode core 11a protruding from the winding end.

The two electrode plates 11 and 12 are laminated with a separator 3 interposed therebetween, and a pair of winding cores 4 and 4 are connected to the winding start end of each of the separators 3 and the negative electrode. After the negative electrode core 12a portion of the plate 12 to which the negative electrode lead 10 is attached is sandwiched and rotated in the direction indicated by the arrow in the drawing, the negative electrode core 12a is wound to form a spiral electrode group 13, and then, as shown in FIG.
Is inserted into the battery case 8 as shown in the cross-sectional view of the rectangular battery. The spiral electrode group 13 forms a power generating element of the battery together with a non-aqueous electrolyte (not shown) injected into the battery case 8.

Note that R _{0 to} R ₁₃ in FIG. 1 indicate the winding order of a length corresponding to a half circumference of the spiral electrode group 13 that is wound every time the pair of winding cores 4 and 4 makes a half turn. . A pair of cores 4, 4
Are arranged slightly shifted in order to make it easy to take out the spirally wound electrode group 13 from the winding cores 4, 4. The length of a half turn of the spiral to be turned corresponds to the distance between the outer ends of the respective winding cores 4 and 4. The winding order R _{0 in} FIG.
The length of the to R ₁₃ is is shown in correspondence to the R ₀ to R ₁₃ in FIG. 3. That is, the spiral electrode group 13 and the spiral electrode group 7 shown in FIG. 3 are both inserted into the battery case 8 having the same capacity.

FIG. 2 mainly shows the spiral electrode group 13.
Are schematically illustrated so that the configuration of the winding start portion and the winding end portion can be easily understood, and are considerably different from the actual form. For example, the number of windings does not correspond to FIG.
3 are separated from each other without being wound, and the spiral electrode group 13 and the battery case 8 have a large gap different from the actual one for convenience of illustration. Therefore, FIG. 2 and FIG. 4 are not shown so that the number of windings and the like can be compared.

As apparent from FIG. 2, in the spiral electrode group 13, each active material non-formed portion 11 c of the positive electrode plate 11 is formed.
Since there is no negative electrode active material layer 12b for performing a chemical reaction on the side opposite to 11d, unnecessary positive electrode active material layers 11b that are not involved in charge / discharge at all are eliminated.
In other words, all of the positive and negative electrode active material layers 11b and 12b provided in the spiral electrode group 13 have a structure capable of participating in charge and discharge by a chemical reaction.

As is clear from the comparison between FIG. 1 and FIG.
Positive electrode active material layer 1 in both spiral electrode groups 7 and 13
Each of b, 11b and the negative electrode active material layers 2b, 12b has a total length of 10 turns, which is the sum of the lengths of both sides of the positive electrode cores 1a, 11a and the negative electrode cores 2a, 12a. , In length. Further, the positive electrode core 11a of the spiral electrode group 13 is longer than the positive electrode core 1a of the conventional spiral electrode group 7 by half the circumference, but the negative electrode core 12a is longer.
Is shorter by half a circumference than the negative electrode core 2a of the conventional spiral electrode group 7, which is equivalent in this respect.

On the other hand, in the spiral electrode group 13,
One round of outermost circumference (R on turn 11)₁₁And turn 12 R₁₂of
Part) is formed by the positive electrode active material non-formed portion 11d of the positive electrode plate 11.
Therefore, the positive electrode active material unformed portion 11d
The exposed positive electrode core 11a is made of the same metal and has the same positive electrode potential.
The inner peripheral surface of the pond case 8 can be brought into contact. Also,
The negative electrode plate 12 is in the 10th turn R_TenEnds with did
Therefore, it is necessary to cut both at the same position from manufacturing
Both separators 3 and 3 are connected to each other in turn 11 R ₁₁And the twelfth
Turn R₁₂Is no longer required, and turn 10
Eye R_TenAre cut off at the same position after passing through.
Thereby, as is clear from the comparison between FIG. 1 and FIG. 3,
The separators 3 and 3 are compared with the conventional spiral electrode group 7.
That is, two rounds are reduced in total.

Therefore, when the battery case 8 having the same volume is used, the spiral electrode group 13 has a total length of the separators 3 and 3 shorter than that of the conventional spiral electrode group 7 by two turns. The positive and negative active material layers 11b by
Since the thickness of the battery 12b can be increased, the volume energy density of the battery can be increased. On the other hand, when the positive and negative electrode active material layers 11b and 12b are set to the same thickness and length as the conventional spiral electrode group 7, the length of both separators 3 and 3 is reduced by a total of two turns. Since the thickness of the spiral electrode group 13 can be reduced as much as possible, the weight energy density as well as the volume energy density of the battery can be increased.

The spiral electrode group 13 also has a great advantage in terms of manufacturing. That is, the positive electrode core 1
Aluminum foil commonly used as 1a is:
It is very difficult to form a partially intermittent positive electrode active material-unformed portion 1c on one surface side of the positive electrode core 1a as shown in FIG. And the possibility of practical application is poor. On the other hand, in the positive electrode plate 11 of the spiral electrode group 13, the two positive electrode active material-free portions 11c and 11d each having the same length for one round are formed on the opposite side surfaces of the positive electrode core 11a. A winding start portion and a winding end portion are formed. Therefore, the two positive electrode active material non-formed portions 11c and 11d can be easily formed by utilizing the phase difference coating method, which is a new active material coating technology established in recent years with the improvement of the roll press. .

On the other hand, in the prismatic battery using the spiral electrode group 13, one outermost circumference is formed by the positive electrode active material-free portion 11 d of the positive electrode plate 11, and the positive electrode active material-free portion is formed. Since the separator 3 is not interposed on the outer side of 11d, one round of the positive electrode core 11a exposed in the positive electrode active material non-formed portion 11d is directly in contact with the inner peripheral surface of the battery case 8 of the positive electrode. Thus, electrical connection can be achieved. Therefore, in this prismatic battery, in addition to connecting the positive electrode lead 9 to the sealing plate by laser welding, one round of the positive electrode core 11a and the inner peripheral surface of the battery case 8 come into contact with each other with a large contact area. As a result, good electrical connection can be obtained, so that the chemical energy generated inside the battery can be efficiently collected as electric energy, and the discharge characteristics are significantly improved.

When the battery case is made of iron and forms a negative electrode, the same configuration and arrangement as those of the positive electrode plate 11 and the negative electrode plate 12 in FIG. Needless to say, the effect can be obtained.

[0032]

As described above, according to the spiral electrode group for a battery according to the present invention, the inner surface of the electrode plate located on the inner side of the winding for one turn and the end of the electrode plate for one turn at the end of the winding. Since no active material layer is formed on the outer surface side of the substrate, there is no unnecessary active material layer not involved in charge / discharge at all. In addition, since the outermost circumference can be formed by the active material-free portion of one electrode plate, a pair of separators that need to be cut at the same position due to manufacturing restrictions can be removed by one rotation relative to one electrode plate. It is possible to set the same position just before the end as the end, and both separators can be shortened by a total of two rounds compared to the conventional, and the positive and negative electrode active material layers can be shortened by the length of the separator. Since the thickness or the length of the battery can be set large, the weight energy density and the volume energy density of the battery can be increased.

Further, according to the battery of the present invention, a good electrical connection can be obtained because the core body for one round of one of the poles and the inner circumferential surface of the battery case come into contact with each other with a large contact area. In addition, the chemical energy generated inside the battery can be efficiently collected as electric energy, and the discharge characteristics are significantly improved.

[Brief description of the drawings]

FIG. 1 is a cut-away side view showing a relative positional relationship before winding of each component in a spiral electrode group for a battery according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a state in which the spiral electrode group is inserted into a battery case.

FIG. 3 is a cross-sectional side view showing a relative positional relationship before winding each component in a spiral electrode group of a conventional rectangular battery.

FIG. 4 is a cross-sectional view schematically showing a state where the spiral electrode group is inserted into a battery case.

[Explanation of symbols]

 3 Separator 8 Battery case 11 Positive electrode plate (one electrode plate) 11a Positive electrode core (one electrode core) 11b Positive electrode active material layer (one electrode active material layer) 11c, 11d Active material unformed portion 12 Negative electrode plate (the other electrode plate) 12a Negative electrode core (the other electrode core) 12b Negative electrode active material layer (the other electrode active material layer) 13 Spiral electrode group

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeharu Nakanose 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference) BJ14 CJ07 DJ05 DJ07

Claims (3)

[Claims] A positive electrode plate having a positive electrode active material layer formed on both sides of a strip-shaped positive electrode core, and a negative electrode plate having a negative electrode active material layer formed on both surfaces of a strip-shaped negative electrode core, In a spirally wound electrode group for a battery, which is spirally wound with a separator interposed therebetween, one of the electrode plates located on the inner side of the spirally wound electrode is disposed on at least one round of the winding start with respect to the core body. An active material layer-free portion where the active material layer is not formed and the core material is exposed is provided on the inner surface side and the outer surface side of the core body for at least one round at the end of winding, and the winding outer side The active material layer is formed on both surfaces of the core body, which is set to have a length that has an end at a position shorter by at least one turn than the one electrode plate, and End of the separator at substantially the same position as the end of the other electrode plate A spiral electrode group for a battery, wherein the spiral electrode groups have the same length. 2. The spiral electrode group for a battery according to claim 1, wherein the one electrode plate is a positive electrode plate having an aluminum positive electrode core. 3. The spirally wound electrode group for a battery according to claim 1 or 2 is inserted into a battery case constituting one of the electrodes, and the active material is not formed on one of the electrode plates located at the outermost periphery. A battery wherein at least one round of the exposed core of the portion is in contact with the inner peripheral surface of the battery case.