JP3428448B2 - Electrode structure and battery using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an arrangement shape of an electrode active material layer used in a battery and a structure of the battery, and particularly to improving the performance of a spiral wound battery.

[0002]

2. Description of the Related Art As the performance of electronic devices has improved in recent years, there has been a demand for improved performance of batteries used as a power source for these electronic devices, especially secondary batteries that can be repeatedly charged. BACKGROUND ART A lithium ion secondary battery has attracted attention as a battery that can drive an electronic device for a longer time, is lightweight, easy to carry, and has a high capacity. Therefore, in the present invention, a lithium ion secondary battery will be described as an example.

FIG. 9 is a sectional view showing the structure of an electrode structure portion of a conventional lithium ion secondary battery. In the figure, 1 is a positive electrode current collector terminal, 2 is a negative electrode current collector terminal, 3 is a positive electrode active material, 4 is a negative electrode active material, 5 is a positive electrode current collector, 6 is a negative electrode current collector, and An electrolyte layer such as a separator (not shown) is provided between the anode active material 4 and the separator, and the separator is impregnated with a non-aqueous electrolyte solution in which an electrolyte is dissolved. 7 is an insulating tape.

In the lithium ion secondary battery shown in FIG. 9, the positive electrode active material 3 is used in order to make the battery small and thin.
Further, the electrode active material layer such as the negative electrode active material 4 has been improved and a new active material has been sought. Similarly, the development of an electrode structure capable of obtaining a higher energy density, that is, the positive electrode current collector terminal 1, the negative electrode current collector The electrode structure formed by the electric terminal 2, the positive electrode active material 3, the negative electrode active material 4, the positive electrode current collector 5, and the negative electrode current collector 6 is important.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Apply the electrode active material layers 3 and 4 on one side of the electrode current collectors 5 and 6
From the formed (hereinafter referred to as one-sided coated) electrode, the electrode active material layer 3 is formed on both surfaces of the electrode current collectors 5 and 6 as shown in FIG.
The electrode coated and molded with 4 (hereinafter referred to as double-sided coating) has a smaller proportion of the electrode current collectors 5 and 6 in the whole battery, and the volume energy density is improved. Further, in the case of having a structure in which the electrodes are wound, unnecessary electrode active material layers 3 and 4 are present because there is no facing electrode in the innermost layer or outermost layer of the electrode structure, and the thickness and weight increase. Leads to. Furthermore, when the electrode having the electrode active material layers 3 and 4 in the innermost layer is pressed into a flat plate shape, the electrode current collectors 5 and 6 may rupture because the bending rate of the innermost layer is large. There is a nature. Here, the innermost layer of the spiral structure refers to the innermost electrode active material layer from the position where the electrode starts to be wound to one or a half round, and the outermost layer is the outermost electrode having no opposing electrode. An active material layer is shown.

As described above, the battery needs the current collecting terminals 1 and 2 which are electrically connected to the outside, and the current collecting terminals 1 and 2 are not covered with the electrode active material layers 3 and 4 in the electrodes. The current collector terminals 1 and 2 are arranged on a part of the electrode current collectors 5 and 6, but especially when flattening to manufacture a thin battery, it is necessary to arrange the current collector terminals 1 and 2 in consideration of the thickness of the battery. is there.

Further, the electrode active material layers 3 and 4 at the portions where the positive and negative electrode current collecting terminals 1 and 2 are arranged are electrode current collectors 5 and 6, respectively.
It is removed to weld the collector terminals 1 and 2 to
For this reason, the electrode active material layers 3 and 4 existing in the electrode portion facing the portion where the current collecting terminals 1 and 2 are arranged do not work as a battery and become a wasteful active material, which causes an increase in thickness and weight.

Further, the positive electrode active material 3 is excessively present,
If a part of the negative electrode active material 4 facing the positive electrode active material 3 does not exist, or if the negative electrode active material 4 facing the positive electrode does not work as a battery, current concentrates on a part of the negative electrode and lithium metal is deposited. And a short circuit due to the short circuit and a problem such as ignition due to the short circuit occur. Therefore, when the positive electrode active material 3 facing the negative electrode active material 4 does not exist, there is no problem such as the deposition of the lithium metal, but for example, the positive electrode active material 3 arranged around the negative electrode current collector terminal 2 in FIG. When there is no opposing negative electrode active material 4, the surface of the positive electrode active material 3 is covered with a masking tape 7 or the like, or the positive electrode active material 3 is scraped off so that the negative electrode active material 4 does not substantially face. It is necessary to eliminate the positive electrode active material 3. As a result, there were problems such as an increase in production processes and an increase in cost.

Further, an electrode current collector 5 as shown in FIG.
When the electrode active material layers 3 and 4 are coated on both surfaces and the ends of both positive and negative electrodes are wound together, the innermost electrode active material layer 4 does not function as a battery because there is no opposing electrode. . When the terminals of the positive electrode and the negative electrode are wound so as to be shifted by a half circumference as shown in FIG. 9, the positive and negative electrode active material layers 3 and 4 are opposed to each other in the innermost layer, but between the positive electrode and the electrolyte layer and between the negative electrode and the electrolyte layer. It is difficult to expect a sufficient electrode reaction because a space is easily generated in the space. Furthermore, when the electrode coated on both sides was wound, a positive electrode active material or a negative electrode active material having no facing electrode was present in the outermost layer, which led to an increase in weight and volume.

As described above, the presence of the extra active material and the masking tape in the portion where the positive electrode active material 3 and the negative electrode active material 4 do not face each other reduces the energy density, increases the thickness of the entire battery, and produces the battery. There is a problem in that costs increase due to an increase in the number of processes.

A first object of the present invention is to provide an electrode structure which is lightweight and small in size and has an improved energy density, and a battery using the same. A second object is to provide a highly reliable electrode structure which prevents the deposition of lithium metal and a battery using the same. Furthermore, the third
The object is to provide an electrode structure having an improved battery life and a battery using the same.

[0012]

In the electrode structure according to the first invention, an electrode active material is formed on both front and back surfaces of an electrode current collector, and a current collector terminal is formed on a part of one surface of the electrode current collector. A positive electrode and a negative electrode, which are opposed to each other with an electronically insulating separator interposed therebetween, and are spirally wound to form an electrode structure,
The electrode active material layers are respectively provided in the spiral innermost layers.
The positive and negative electrode current collectors that are not formed are arranged.
Together with the positive electrode active material layer and the negative electrode active layer only on the opposite surface.
The material layer, the negative electrode current collector terminal, and the positive electrode current collector terminal are arranged,
Negative electrode current collector terminal, and of the portion facing the positive electrode current collector terminal
An electrode active material layer is not formed on each of the collectors of the other electrodes .

[0013]

An electrode structure according to a second invention is the above first electrode structure.
In the electrode structure of the present invention, the electrode active material is not formed outside the spiral outermost electrode current collector.

[0015]

[0016]

The battery according to a first aspect of the invention is the battery according to the first aspect .
2 the electrode structure of the invention of 2 is made of laminated sheet
It is enclosed in a bag .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a cross-sectional view showing an electrode structure according to a first embodiment of the present invention, which is an example in which a negative electrode and a positive electrode are wound so that the winding start thereof is offset by half a turn. Note that in FIG. 1, separators arranged between the positive electrode active material layer and the negative electrode active material layer and in the outermost layer are omitted in order to avoid complication of the drawing. In the figure, 1 is a positive electrode current collector terminal, 2 is a negative electrode current collector terminal, 3 is a positive electrode active material layer, 4 is a negative electrode active material layer, 5 is a positive electrode current collector, 6 is a negative electrode current collector, and A to G.
Is an active material uncoated part.

The feature of the electrode structure shown in FIG. 1 is that the positive electrode and the negative electrode face the first layer, that is, the innermost layer of the electrode active material layers 3 and 4 where the positive electrode and the negative electrode are less likely to adhere to each other. The outermost electrode active material layer (negative electrode active material layer 4) G having no counter electrode is not applied, and the electrode active material facing the electrode current collector terminals 1 and 2 attached to the innermost end. Since the layer portions C and F do not react as a battery, they are uncoated portions of the active material, and the electrode current collector terminals 1 and 2 having substantially the same thickness as the electrode active material layers 3 and 4 are formed on the first layer. The feature is that the unwinding portions A and D of the electrode active material layer are efficiently arranged so as to suppress an increase in the electrode thickness. With such a configuration, it is possible to obtain an electrode structure that is lightweight, compact, and has improved energy density. Furthermore, since the positive electrode portion formed on the negative electrode current collector 6 and facing the current collecting terminal 2 is an uncoated portion of the active material, it is possible to prevent the deposition of lithium metal. Furthermore, by forming the negative electrode active material layer 4 larger than the opposing positive electrode active material layer 3,
Lithium metal precipitation is prevented more reliably. This also applies to each of the following embodiments. In FIG. 1, the electrode current collectors 5 and 6 are indicated by thick lines, and the uncoated portion of the electrode active material layer of the electrode current collectors is indicated by thick lines. The first layer of the spiral-shaped electrode structure is defined as a starting point at a position where the winding is started and a part wound up to the starting point.

2A and 2B, electrode active material layers 3 and 4 are provided to form uncoated portions on one or both sides of the electrode current collectors 5 and 6 as shown in FIG. In the example of the patterned electrode, A to G in the figure are portions where the electrode active material layer is not coated, and correspond to A to G in FIG. In FIGS. 1 (a) and 1 (b), A and D are portions where an active material layer for attaching the positive electrode current collector terminal 1 and the negative electrode current collector terminal 2 is not coated, and B and E are innermost layers. Corresponding parts, C and F are the negative electrode current collecting terminal 2 respectively.
The positive electrode active material layer 3 and the negative electrode active material layer 4 facing the positive electrode current collector terminal 1 correspond to the uncoated portions. Also,
G corresponds to the portion where the negative electrode active material layer 4 on the outer side of the outermost electrode current collector 6 is uncoated. The uncoated portion may be formed by pattern coating when forming the electrode active material layers 3 and 4, or may be formed by scraping off a part of the entire surface after coating. .

Embodiment 2. FIG. 3 is a cross-sectional view showing an electrode structure according to a second embodiment of the present invention, which is disposed between the positive electrode active material layer 3 and the negative electrode active material layer 4 and in the outermost layer in order to avoid complication of the drawing. The separator is omitted. This is an example in which the winding start of the negative electrode and the positive electrode are offset by half a turn, and the current collecting terminals 1, 2 are provided at the outer ends of the wound electrodes.
Shows the case where is arranged. Since this structure does not have current collector terminals 1 and 2 inside the electrode body, it is difficult for an excess space to exist and an extra space is unlikely to occur in the innermost layer. Therefore, unlike FIG. 1, the innermost electrode current collectors 5 and 6 are not provided. The active material layers 3 and 4 are also formed inside. Further, since there is no counter active material facing the outside of the outermost electrode current collectors 5 and 6, the active material layers 3 and 4 are not formed. Therefore, there is no active material layer facing the current collecting terminals 1 and 2, and the precipitation of lithium metal due to the surplus positive electrode active material can be prevented. Although the positive electrode active material layer 3 facing the winding start end of the negative electrode is covered with the insulating tape 7 to prevent the deposition of lithium metal, the active material in this portion is removed instead of being covered with the insulating tape 7. Good. Further, when the innermost layer is difficult to adhere, a structure in which the active material of the innermost layer is removed is also effective.

Embodiment 3. FIG. 4 is a cross-sectional view showing an electrode structure according to a third embodiment of the present invention, which is disposed between the positive electrode active material layer 3 and the negative electrode active material layer 4 and in the outermost layer in order to avoid complication of the drawing. The separator is omitted. This is an example in which the negative electrode and the positive electrode are wound with the winding start shifted by a half turn, and the case where the current collecting terminals 1 and 2 are arranged in the center of the electrode is shown. In the case of this structure as well, as in the case of FIG. 3, since the collector terminals 1 and 2 are not provided inside the electrode body, an excess space is unlikely to exist, and an extra space is unlikely to occur in the innermost layer. The active material layers 3 and 4 are also formed inside the electric bodies 5 and 6. Further, since there is no counter active material facing the outside of the outermost electrode current collectors 5 and 6, the active material layers 3 and 4 are not formed. In addition, an active material layer facing the current collecting terminals 1 and 2 is not formed, an extra space due to the thickness of the current collecting terminals 1 and 2 is eliminated, and precipitation of lithium metal due to excess positive electrode active material is prevented. There is. The positive electrode active material layer 3 facing the winding start end of the negative electrode is covered with an insulating tape 7 to prevent the deposition of lithium metal. However, instead of covering with the insulating tape 7, the active material in this portion is removed. Good. Further, when the innermost layer is difficult to adhere, a structure in which the active material of the innermost layer is removed is also effective.

Fourth Embodiment FIG. 5 is a cross-sectional view showing an electrode structure according to a fourth embodiment of the present invention, which is disposed between the positive electrode active material layer 3 and the negative electrode active material layer 4 and in the outermost layer in order to avoid complication of the drawing. The separator is omitted. This is an example in which the negative electrode and the positive electrode are wound at the same winding start position, and the current collecting terminals 1, 2 are attached to the outer ends of the wound electrodes.
Shows the case where is arranged. In this case, unlike the cases of Embodiments 1 to 3, since the winding start positions of the positive electrode and the negative electrode are the same, the same poles face each other like the negative electrode and the negative electrode in the innermost portion by the initial folding. Even if an active material is present in the innermost layer, battery reaction cannot be expected. Therefore, no electrode active material is formed inside the innermost electrode collector (negative electrode collector 6 in this figure).

Embodiment 5. FIG. 6 is a cross-sectional view showing an electrode structure according to a fifth embodiment of the present invention, which is disposed between the positive electrode active material layer 3 and the negative electrode active material layer 4 and in the outermost layer in order to avoid complication of the drawing. The separator is omitted. This is an example in which the negative electrode and the positive electrode are wound at the same winding start position, and one current collecting terminal 1 is arranged at the inner end of the wound electrode and the other current collecting terminal 2 is arranged at the center. Show. Also in this case, no electrode active material is formed inside the innermost electrode current collector 6. In addition, the negative electrode current collector 6 at the inner end portion
The active material is not formed on the positive electrode current collector 5 facing the negative electrode current collector terminal 2 formed in the above to prevent the deposition of lithium metal, but the positive electrode current collector terminal 1 formed on the positive electrode current collector 5 is An active material is formed on the negative electrode portion facing to, because there is no concern about deposition of lithium metal. Of course, the active material in this portion may be removed.

[0025]

EXAMPLES Example 1. (Production of Positive Electrode) 91 parts by weight of a positive electrode active material made of LiCoO _2, 6 parts by weight of artificial graphite as a conductive material, and polyvinylidene fluoride as a binder (hereinafter abbreviated as PVDF)
The positive electrode active material paste prepared by dispersing 3 parts by weight in N-methylpyrrolidone (hereinafter, abbreviated as NMP) was applied onto a 20 μm-thick aluminum foil serving as a positive electrode current collector by a doctor blade method, as shown in FIG. ), A positive electrode active material layer having a coated portion and a non-coated portion of the positive electrode active material layer was formed, and then dried. Further, the same positive electrode active material paste was pattern-coated on the back surface by a doctor blade method to form a positive electrode active material layer on both sides of the aluminum foil, which was dried and then pressed to produce a positive electrode having a thickness of 200 μm. The electrode size was 49 mm in length × 150 mm in width, the uncoated portion A had a width of 10 mm, B + C had a width of 30 mm, and the positive electrode active material film on one surface had a thickness of 90 μm. An aluminum current collector terminal having a thickness of 0.1 mm and a width of 3 mm as a lead was attached by ultrasonic welding to the end of the uncoated portion of the positive electrode aluminum foil. In addition,
The current collector is not limited to foil and may be mesh.

(Preparation of Negative Electrode) 90 parts by weight of a negative electrode active material composed of mesophase carbon microbeads and PVDF1
The negative electrode active material paste prepared by dispersing 0 parts by weight in NMP was used as a negative electrode current collector with Cu having a thickness of 12 μm.
The foil was patterned by a doctor blade method as shown in FIG. 2 (b) to form a negative electrode active material film having a negative electrode active material coated portion and an uncoated portion, and then dried. Further, a negative electrode active material paste was pattern-coated on the back surface and dried to form a negative electrode active material film on both surfaces of the Cu foil, and then pressed to form a negative electrode. The electrode dimensions are 50 mm length x 180 mm width, uncoated part D has a width of 5 mm, uncoated part E + F has a width of 30 mm, and G55 m.
m, and the negative electrode active material film on one surface was 90 μm. Cu of negative electrode
0.1m thickness as a lead on the edge of the uncoated part of the foil
A Cu current collector terminal having a width of m and a width of 3 mm was attached by ultrasonic welding. The current collector is not limited to foil and may be a mesh, and the current collector terminal is not limited to Cu and may be Ni.

(Creation of spiral electrode structure) A 25 μm porous polypropylene sheet (trade name Celgard manufactured by Hoechst) was used as a separator. The positive electrode and the negative electrode created above are arranged such that the winding start is shifted by half a turn, the current collecting terminals are located inside, and the active material uncoated parts of the positive electrode and the negative electrode are opposed to each other via the separator to form an oval shape. After winding, the end of winding was fixed with a polyimide tape to form a spiral electrode structure.

Example 2. (Flatization of Electrode Structure) In Example 1, the elliptical rolled electrode structure is sandwiched by flat plates such as metal plates, and a load is applied to form a flat plate spiral electrode body as shown in FIG. Created.
At this time, the elliptical electrode body was dried at 60 to 120 ° C. under pressure to obtain a flat spiral electrode body. By flattening in this manner, an extra space is eliminated and the device can be made compact and the adhesion between the electrode and the separator is improved.

Example 3. (Adhesive flat plate spiral electrode structure) The positive electrode and the negative electrode were prepared in the same manner as in Example 1. PVD on one side of two separators
An NMP solution in which 7 parts by weight of F was dissolved and 9 parts by weight of aluminum oxide powder was dispersed was applied as an adhesive. The adhesive layer formed of this adhesive holds the electrolytic solution when the electrolytic solution is injected and forms an adhesive layer having ion conductivity. Then, before the adhesive was dried, it was brought into close contact with both sides of the above-prepared negative electrode and bonded to form a negative electrode with a separator. The adhesive is an example, and not limited to PVDF, but may be a polymer such as polyvinyl alcohol, polyvinyl butyrate, or polymethacrylsanmethyl. The concentration is not limited to 7 parts by weight. Further, the aluminum oxide powder is added so that the adhesive layer easily becomes a porous body, and fine powder such as graphite or silica gel may be added.
Further, the solvent is not limited to NMP, and may be, for example, dimethylformamide (hereinafter abbreviated as DMF).

PVDF is added to the negative electrode with the separator 7 times.
DMF solution in which 9 parts by weight of aluminum oxide powder is dispersed is applied as an adhesive, and the bonding is performed so that the negative electrode active material uncoated part and the positive electrode active material uncoated part overlap each other. Wrap in a circle and before the adhesive dries,
Vacuum drying was performed while applying a load to form a bonded flat plate spiral electrode body as shown in FIG. In the bonding step, the negative electrode may be bonded to the positive electrode to which the separator is bonded, or the positive electrode, the separator, and the negative electrode may be bonded simultaneously. Further, only one of the positive electrode and the negative electrode may be adhered to the separator, and by adhering the electrode and the separator, it is possible to obtain a highly reliable electrode structure which is hardly displaced. In addition, one of the electrodes is adhered to the separator, and then the other electrode is rolled up and bonded to each other to facilitate the production.

Comparative Example 1. As Comparative Example 1, the same production method as in Example 3 was used using an electrode which is made of the same material as in Example 1 and in which the electrode active material is formed on both surfaces of the electrode current collector and which is not subjected to pattern coating. Then, the electrode structure shown in FIG. 9 was prepared. Note that the dimensions of the electrode structure are the thickness (dimension in the vertical direction toward the drawing) of Example 3 and Comparative Example 1.
The width was 0 mm, the width (horizontal direction) was 25 mm, and the height (direction perpendicular to the drawing) was 50 mm.

(Sealing of Electrode Body) The above-prepared electrode structure according to Example 3 and Comparative Example 1 was mixed with a mixed solvent of ethylene carbonate and diethyl carbonate (molar ratio of 1: 1).
Lithium fluorophosphate was immersed in an electrolyte solution having a concentration of 1 mol / dm ³ to sufficiently impregnate it, and then heat sealed in a bag made of an aluminum laminate sheet having a thickness of 110 μm. The current collecting tab portion was sealed by heat-sealing by sandwiching a portion of polyethylene having heat-sealing property with metal with an aluminum laminate sheet. The closing margin of the aluminum laminate sheet was 5 mm, and the upper and left and right directions were sealed by heat fusion to form a battery.

The above-prepared batteries were charged at a current of 100 mA to 4.1 V and discharged after 10 minutes at the same current value to reach 2.5 V.
Shown in. The battery prepared in Example 3 had a discharge capacity of 340 mAh, but the battery prepared in Comparative Example 1 was 280 m.
Only the discharge capacity of Ah was obtained. Although the external dimensions of the battery are the same, in Example 3, the active material that does not participate in the battery reaction is removed, and the electrode active material layer is arranged only in the portion where the positive and negative electrode active materials face each other. This is because the amount of the functioning electrode active material layer in Example 3 is larger than that in Comparative Example 1.

[0034]

[Table 1]

Further, in Comparative Example 1, as shown in an enlarged view of the central portion of the electrode structure in FIG. 8, an extra space is apt to occur in the innermost portion due to the thickness of the current collecting terminals 1 and 2 and the insulating tape 7, but In Example 3, as shown in an enlarged view of the central portion of the electrode structure in FIG. 7, it is difficult for an extra space to exist. Further Example 3
In the above, the electrode active material layer inside the innermost layer in which a space is easily generated and a battery reaction is hard to occur is eliminated to reduce an extra thickness. As a result, it can be seen that a difference in discharge capacity from Comparative Example 1 occurred, a higher discharge capacity was obtained, and the volume energy density was improved.

Further, a cycle test was repeated in which the batteries according to Example 3 and Comparative Example 1 were charged at a current value of 100 mA to 4.1 V and discharged after 10 minutes at the same current value, which was repeated charge and discharge. Table 2 shows the results of comparing the deterioration of the discharge capacity after 100 cycles. In the battery according to Example 3, the discharge capacity after 100 cycles maintained 90% or more of the initial discharge capacity, while in the battery according to Comparative Example 1, it was about 86%. This is because, in Comparative Example 1, since extra negative electrode active material was present in the innermost layer and the outermost layer, lithium ions were taken in during charging in the extra negative electrode active material portion when the charge / discharge cycle was repeated. It is considered that this is because the lithium ions were not released during discharge. Thus, by removing the surplus active material in the outermost layer and the innermost layer, the cycle characteristics are improved, the deterioration of the battery due to repeated use is suppressed, and the life of the battery is extended.

[0037]

[Table 2]

Example 4. Using the electrode prepared in Example 1 and an electrode having a different active material coating pattern, and the same preparation method as in Example 3, the positive electrode and negative electrode of Embodiment 4 shown in FIG. 5 have the same winding start position. Example 4 was prepared and an electrode structure was prepared.

Comparative Example 2. As Comparative Example 2, an electrode made of the same material as that of Example 1 and having an electrode active material formed on both surfaces of the electrode current collector without being subjected to pattern coating was used, and the same production method as in Example 3 was used. Then, the electrode structure shown in FIG. 10 was prepared. The dimensions of the electrode structure are shown in Example 4,
Comparative Example 2 was the same as Example 3 and Comparative Example 1.

The electrode structure prepared as described above was impregnated with an electrolytic solution in the same manner as in Example 3 and Comparative Example 1 and sealed with an aluminum laminate sheet to prepare a battery. Table 2 shows the results when each of the batteries thus prepared was charged at a current of 100 mA until it reached 4.1 V, and was discharged after 10 minutes at the same current value until it reached 2.5 V. Example 4
The battery prepared in Example 3 obtained a discharge capacity of 340 mAh, but the battery prepared in Comparative Example 2 obtained a discharge capacity of 300 mAh. The external dimensions of the battery are the same,
In Example 4, the active material that does not participate in the battery reaction was removed, and the electrode active material layer was arranged only in the portions where the positive electrode and negative electrode active materials face each other. This is because Example 4 has more number than Comparative Example 2.

[0041]

[Table 3]

When the electrode body of Comparative Example 2 was pressed into a flat plate, the current collector at the innermost bent portion of the electrode body sometimes cracked. However, in the electrode body of Example 4, the crack occurred. No such thing was seen. This is because the electrode body of Comparative Example 2 has an electrode active material layer in the innermost layer as shown in FIG. This is because the positive electrode current collector could not withstand the elongation of the metal due to bending.
On the other hand, in the electrode body of Example 4, since the innermost layer does not have an electrode active material layer, the elongation rate of the metal electrode current collector is smaller than that of Comparative Example 2, and the rupture of the electrode current collector is suppressed. It was Thus, by not providing the electrode active material in the innermost layer, the effect of controlling the rupture of the electrode current collector was also observed when pressed and flattened.

Although the electrode structures shown in the first and fourth embodiments are taken up in the above-mentioned examples, the electrode structures shown in the other embodiments are different from those in the first embodiment only in the active material coating pattern. It can be prepared by the same method as in Examples 1 to 4 using the same electrode.

[0044]

As described above, according to the electrode current collector of the first invention, an electrode active material is provided on both front and back surfaces of the electrode current collector, and a part of one side of the electrode current collector is used. A positive electrode and a negative electrode each having a current collector terminal formed thereon are arranged facing each other with an electronically insulating separator interposed therebetween, and are wound in a spiral shape, wherein the spiral innermost layer is It the electrode active material layer
The positive and negative electrode current collectors, which are not formed respectively, are arranged.
And the negative electrode active material layer and negative
A polar active material layer, a negative electrode current collector terminal, and a positive electrode current collector terminal are arranged,
The negative electrode current collector terminal, and a portion facing the positive electrode current collector terminal
Since the electrode active material is not formed on the collector of the other electrode of the second position, it is lightweight and small, and the energy density is improved.
Moreover, a highly reliable electrode structure can be obtained by preventing deposition of lithium metal.

[0045]

According to the electrode current collector of the second invention,
In the electrode structure of the first aspect of the invention , since the electrode active material is not formed outside the spiral outermost electrode current collector, the active material outside the outermost layer that does not participate in the battery reaction without a counter electrode is formed. It is possible to obtain an electrode structure that is light in weight, small in size, and has improved energy density by omitting. Further, the cycle characteristics are improved in repeated use, and the battery life can be expected to be improved.

[0047]

[0048]

Further, according to the battery of the first invention, the first or second electrode structure is made of a laminated sheet.
Since it is enclosed in a sealed bag, a battery that is lightweight and compact, has improved energy density, and prevents the deposition of lithium metal, and has high reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a spiral electrode structure according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an electrode pattern coating example according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a spiral electrode structure according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a structure of a spiral electrode structure according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a structure of a spiral electrode structure according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view showing the structure of a spiral electrode structure according to a fifth embodiment of the present invention.

FIG. 7 is an enlarged sectional view showing a central portion of a flat plate spiral electrode structure according to a third embodiment of the present invention.

FIG. 8 is an enlarged cross-sectional view showing a central portion of a flat plate spiral electrode structure according to Comparative Example 1 of the present invention.

FIG. 9 is a cross-sectional view showing a configuration of a conventional spiral electrode structure.

FIG. 10 is a cross-sectional view showing another structure of a conventional spirally wound electrode structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Positive electrode collector terminal, 2 Negative electrode collector terminal, 3 Positive electrode active material layer, 4 Negative electrode active material layer, 5 Positive electrode collector, 6 Negative electrode collector, 7 Insulating tape, 8 Separator, A to G active material uncoated Engineering department.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Jun Aragane 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Shoji Yoshioka 2-3-2, Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Machinery Co., Ltd. (72) Inventor Shigeru Aihara 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Makiko Yoshise 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Takashi Nishimura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (56) References JP-A-5-74498 (JP, A) JP-A-5-325989 (JP, A) JP-A-6-223841 (JP, A) JP-A-10-172537 (JP, A) JP-A-10-172606 (JP, A) JP-A-11-111327 (JP, A) JP-A-11-265706 (JP A) Patent flat 7-320770 (JP, A) JP flat 8-339818 (JP, A) JP flat 8-339817 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name ) H01M 10/04 H01M 4/02 H01M 10/40 H01M 2/02

Claims (3)

(57) [Claims] 1. An electrode active material on both front and back surfaces of an electrode current collector.layer
A collector terminal on one side of each of the electrode collectors.
The formed positive electrode and negative electrode are separated by an electronically insulating separator.
Electrode structure formed by spirally arranging in opposition to each other
AndThe innermost layer of the spiral shape has the electrode active material layer.
The positive and negative electrode current collectors that do not respectively form
The positive electrode active material is arranged on the opposite side only
Layer, negative electrode active material layer, negative electrode collector terminal, positive electrode collector terminal arranged
Facing the negative electrode current collector terminal and the positive electrode current collector terminal
Each of the collectors of the other poleElectrode active materiallayerShape
An electrode structure characterized by being not formed. 2. The electrode active material is not formed on the outer side of the spiral outermost electrode current collector.
1. The electrode structure according to 1 . 3. The electrode structure according to claim 1 or 2.
Was enclosed in a bag made of laminated sheet
Characteristic battery.