KR20090104642A - Secondary battery - Google Patents

Abstract

PURPOSE: A secondary battery is provided to minimize deplete of an electrolyte and to prevent electrical short between electrode plates and reduction of battery capacity. CONSTITUTION: A secondary battery includes a positive electrode plate(14), a negative electrode plate(15), and a separator(24). The positive electrode plate is such that a positive electrode active material layer(14b) is formed on the surface of a positive electrode collector. The negative electrode plate is such that a negative active material layer is formed on the surface of a negative electrode collector. An insulating tape(22A,22B) is adhered to the cut side containing an active material layer on at least one side of the positive electrode plate and negative electrode plate.

Description

Rechargeable battery {SECONDARY BATTERY}

TECHNICAL FIELD This invention relates to a secondary battery. More specifically, It is related with the secondary battery which has an electrode plate in which the electrode plate edge part is covered and protected by the insulating tape.

In various electronic devices such as portable terminals such as mobile phones, various types of batteries are used as the power source. In addition, due to the recent increase in environmental protection movements, emission regulations such as carbon dioxide gas are being tightened.In the automobile industry, not only automobiles using fossil fuels such as gasoline, diesel oil and natural gas, but also electric vehicles (EVs) and hybrids Electric vehicle (HEV) development is being actively carried out. In addition, the recent sharp rise in fossil fuel prices has become a favorable wind for advancing the development of these EVs and HEVs.

As a secondary battery used for such a use, the alkali storage battery represented by the nonaqueous electrolyte secondary battery represented by a lithium ion battery, nickel-hydrogen battery, etc. is known. Among them, a nonaqueous electrolyte secondary battery represented by a lithium ion battery has a high operating voltage (3 V or more), a higher theoretical energy density than an aqueous solution battery, and also a lower self discharge, and furthermore, a low operating temperature range. Its use has been expanded due to its excellent characteristics such as being wide and having excellent leakage resistance.

Such a secondary battery has, for example, a wound electrode group in which a positive electrode plate and a negative electrode plate are wound in a flat manner through a separator, a wound electrode group, and a size that can accommodate a predetermined amount of electrolyte solution. And a rectangular battery outer shell having an upper opening, and a sealing body having a positive electrode terminal and a negative electrode terminal inserted into the upper opening of the battery outer package and sealing the opening of the rectangular battery outer package in a sealed state. When assembling this battery, first, a flat wound electrode group is accommodated in a rectangular battery outer package, and the current collectors of each of the positive electrode plate and the negative electrode plate are welded to the positive electrode terminal or the negative electrode terminal, and then the rods of the battery outer package are sealed. The spheres are welded, the electrolyte is injected from the injection holes provided in the sealing body, and then assembled by sealing the injection holes.

By the way, this type of secondary battery may cause a short circuit inside for some reason. When such an internal short circuit occurs, not only the product is defective but also causes a rupture or fire. In particular, the nonaqueous electrolyte secondary battery represented by a lithium ion battery has high capacity and high output characteristics. Therefore, when an internal short circuit occurs, a chemical reaction occurs between the electrode body stored in the battery and the nonaqueous electrolyte, and the pressure inside the battery is abnormal. Rises and the battery may burst or ignite. Therefore, the technique which prevents a short circuit by attaching an insulating tape to the location which an internal short circuit tends to produce is proposed in such a battery (for example, refer following patent documents 1-4).

Here, with reference to FIG. 6 and FIG. 7, the short circuit prevention technique of the battery disclosed by following patent documents 1 and 2 is demonstrated. 6A is a plan view of an electrode material end shown in the following Patent Document 1, FIG. 6B is a sectional view taken along the line VIB-VIB in FIG. 6A, and FIG. 6C is an end of the electrode material disclosed as a prior art example in Patent Document 1 below. Longitudinal section. 7A is a plan view of the electrode plate disclosed in Patent Document 2 below, and FIG. 7B is a cross-sectional view taken along the line VIIB-VIIB in FIG. 7A.

The electrode material end part 50 disclosed in the following patent document 1 improves the electrode material end part 50A (refer FIG. 6C) of a prior art. As shown in FIGS. 6A and 6B, the electrode material end portion 50 forms a region 51a from which a part of the electrode active material layer 52 formed in the electrode current collector 51 is removed, and the resin is formed in this region 51a. By sticking the tape 53, the thickness H1 of the portion where the resin tape 53 is provided is approximately equal to the thickness H2 of the portion where the electrode active material layer 52 is formed.

With such a configuration, as is clear from the electrode material end portion 50A shown in Fig. 6C, there is no step between the portion where the resin tape 53 is formed and the portion where the electrode active material layer 52 is formed. Therefore, in the invention disclosed in Patent Document 1 below, a burr generated when the electrode material is cut by the resin tape 53 and an electrode terminal generated when the electrode terminal is welded to the ends of the negative electrode and the positive electrode The stepped portion of the wand breaks through the thin gel-like electrolyte layer and comes into contact with the other electrode, thereby preventing the occurrence of an electrical short circuit.

In addition, as shown in FIGS. 7A and 7B, the electrode plate 54 disclosed in Patent Literature 2, when the active material 56 is applied to the surface of the electrode material 55, is coated at the beginning and the coating end. The projections a and a 'formed in (iii) are covered with an insulating member 57. The base material of this insulating member 57 is formed with the porous material which permeate | transmits electrolyte solution. In addition, the current collector tab 58 is provided in a region where the active material 56 of the electrode plate 54 is not applied.

In this way, when the protruding portions (a, a ') serving as the coating start and end of the active material 56 are covered with the insulating member 57, the contact and protrusions (a, a') between the positive and negative electrodes are applied. Damage to the separator due to contact with is prevented. Therefore, since the insulating member 57 electrically insulates the positive electrode plates and is formed of a porous material, the movement of the electrolyte is facilitated, thereby preventing the occurrence of an electrical short circuit between the positive electrode plates and a decrease in battery capacity. It shows the effect that it can.

Furthermore, the lithium ion impermeable tape was coated on the coated end of the electrode mixture to suppress the negative electrode reaction at the portion not facing the positive electrode, thereby improving the storage characteristics of the nonaqueous electrolyte secondary battery (for example, Patent Document 3 below). Or a nonaqueous electrolyte secondary battery (for example, Patent Document 4 described below) covered with an insulating tape around one end of the positive electrode surface to prevent burrs generated on the cut surface of the electrode plate from contacting other electrode plates. Is also known.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-188115 (paragraphs [0008] to [0011], Figs. 3 and 9)

Patent Document 2: Japanese Patent Application Laid-Open No. 2006-128106 (paragraph [0017], Fig. 2, Fig. 3)

Patent document 3: Unexamined-Japanese-Patent No. 9-134719 (paragraph [0006], FIG. 2, FIG. 3)

Patent Document 4: Japanese Patent Application Laid-Open No. 2001-76758 (paragraphs [0040] to [0041], FIG. 2)

When the structure of the electrode material edge part shown to the said patent documents 1-4 is employ | adopted, the effect that the short circuit etc. which occur easily between electrodes of the nonaqueous electrolyte secondary battery produced once can be prevented.

By the way, the positive electrode plate and the negative electrode plate both apply a positive electrode active material layer to a negative electrode active material layer to a predetermined method on such an electrode sheet using a long strip-shaped electrode sheet, and then cut the lengths of the individual electrodes. After being produced. Application | coating of the active material layer to this long electrode sheet, after apply | coating for the length required for one electrode formation, provides the core exposed part which has not apply | coated the active material layer, and also apply | coats the active material layer for the next electrode. The so-called intermittent coating method (hereinafter referred to as the "intermittent coating method") to apply the repeated operation to apply, and the coating method to continuously apply the core exposed portion at one end of the side orthogonal to the long direction (hereinafter, `` Continuous coating method ''). Moreover, this core exposed part is provided in order to fix a collector tab.

When the continuous coating method as described above is adopted, the active material layer and the current collector supporting the active material layer are simultaneously cut at the time of cutting the long electrode sheet. Therefore, projections are generated on the cut surface of the current collector, and the cross section and the vicinity of the cross section of the active material layer are in an unstable state due to the impact at the time of cutting, so that the active material layer is easily slipped off. In addition, in the case of the intermittent coating method, since it cuts in a core exposed part, the problem which an active material layer slips by cutting does not arise. However, in the case of the intermittent coating method, since protrusions are formed at the beginning and the end of the application of the coating of the active material layer, as shown in Patent Document 2, the sticking of the resin tape is necessary.

The positive electrode plate and the negative electrode plate in which the active material layer is formed by employing the continuous coating method as described above are laminated or wound between the separators in the following assembling step. In that case, since the active material layer is easy to slip off the cut surface of a positive electrode plate and a negative electrode plate, there exists a possibility that an active material layer may slide off by an impact etc .. When the active material layer slips off, the slipped active material layer moves inside the battery after battery assembly and causes internal short circuits. Thus, as in the prior art disclosed in Patent Document 1 (see Fig. 6C), a method of sticking an adhesive tape to the cut surface of the electrode plate to prevent the active material from slipping is considered. However, when the adhesive tape is attached to the cut surface of the electrode plate, The adhesive provided in this tape may absorb electrolyte solution and may deplete electrolyte solution in a separator. As described above, when the electrolyte in the separator is depleted, the positive electrode material precipitates and causes an internal short circuit.

From this point of view, if the tape is affixed to the end of the electrode material with the adhesive as in the prior art, there is a fear that the adhesive applied to the tape absorbs the electrolyte and depletes the electrolyte in the battery. However, in the invention disclosed in the patent documents 1 to 4, nothing is considered about the problem of exhaustion of the electrolyte when the tape is attached to the end of such an electrode material with an adhesive.

For example, the electrode material end portion 50A of the prior art disclosed in Patent Document 1 (see FIG. 6C) has an adhesive of a resin tape adhered to the entire surface of the active material, so that the adhesive absorbs the electrolyte solution. The electrolyte in the separator may be depleted. On the other hand, in the structure (refer FIG. 6A and 6B) of the electrode material edge part 50 corresponding to the improved invention disclosed by patent document 1, the active material layer exists in the elongate electrode plate produced by the continuous coating method. When the core exposed portion is provided by removing the active material layer formed on the core after cutting at the portion to be cut, the end of the active material layer is not covered with the resin tape, so that the active material layer may slip. Moreover, when providing a core exposed part by the intermittent coating method and cutting this part, since an active material layer is not cut | disconnected, there exists no problem that the active material layer which slips when cutting an active material layer slips. Moreover, since the structure of the electrode material edge part of the said patent document 2 does not cut an active material layer by providing a core exposed part by the intermittent coating method, and cuts this part, the active material layer which arises when cutting an active material layer is No slippage problem exists. Further, in Patent Documents 3 and 4, nothing is mentioned about slippage, movement, and depletion of the active material generated when the active material layer is cut.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to prevent the active material from slipping and moving when the electrode plate ends are covered with an insulating tape, thereby preventing the exhaustion of the electrolyte, and It is to provide a secondary battery which prevents occurrence of electrical short circuit between plates and reduction of battery capacity.

The secondary battery of the present invention has a cut end including at least one of the positive electrode plate having the positive electrode active material layer formed on the surface of the positive electrode current collector and the negative electrode plate having the negative electrode active material layer formed on the surface of the negative electrode current collector including the active material layer portion thereof. In the secondary battery in which the electrode group which laminated | stacked or wound each other and laminated | stacked with each other through the separator between the said positive electrode plate and the negative electrode plate with an insulating tape was sealed in the battery exterior body with electrolyte solution,

The insulating tape is composed of an adhesive insulating tape having an adhesive application region to which the adhesive is applied and an uncoated adhesive region to which the adhesive is not applied,

The insulating tape is affixed so that the adhesive uncoated region is located in the center direction on the active material layer of the electrode plate to which the insulating tape is attached, and a part of the adhesive coating region is located on the active material layer on the cut end side. It features.

According to the secondary battery of the present invention, the adhesive insulating tape has a portion of the adhesive coating region on the active material layer on the cut end side such that the adhesive uncoated region is located in the center direction on the active material layer of the electrode plate with the insulating tape. It is affixed so that it may be located. Since the adhesive application area | region is abutting on the surface of an active material layer by the sticking of this insulating tape, it can prevent that the active material layer of a cutting edge side slips off. Moreover, since an adhesive agent is not apply | coated the adhesive agent is not provided, it does not absorb electrolyte solution. Since the adhesive uncoated region is provided at a portion near the separator at the end of the insulating tape, absorption of the electrolyte solution in the separator near the end of the insulating tape by the adhesive can be prevented. Moreover, in the state in which the electrode group was formed, since the area | region which is an adhesive agent uncoated part of an insulating tape is pressed firmly to an active material layer direction, it becomes difficult to contact electrolyte solution to an adhesive part, and absorption of the electrolyte solution by an adhesive agent is suppressed. In addition, since the uncoated area of the adhesive is disposed on the active material near the cut end portion, even if an insulating tape having the same width as in the prior art is used, the area of the adhesive material applying portion of the insulating tape positioned on the active material layer is narrowed, so that the electrolyte solution absorbed by the adhesive You can minimize the amount of. Therefore, according to the secondary battery of the present invention, slipping and movement of the active material are less likely to occur, and depletion of the electrolyte is suppressed, so that a secondary battery having suppressed the occurrence of an electrical short between the electrode plates and a decrease in battery capacity can be obtained. have.

Moreover, the secondary battery of this invention is applicable also to the case of the electrode group in which the electrode group laminated | stacked on each other through the separator between the positive electrode plate and the negative electrode plate, or the wound electrode group. Moreover, in the case of the wound electrode group, it is applicable also to a cylindrical wound electrode group, an elliptical wound electrode group, and also a flat wound electrode group.

In the secondary battery of the present invention, it is preferable that the positive electrode plate and the negative electrode plate have active material layers formed on both sides of the front and back, and the insulating tape is affixed on both sides of the cut portion side including the cut portion.

According to the secondary battery of the present invention, the positive electrode plate and the negative electrode plate have active material layers formed on both sides of the front and back sides, and the insulating tape is affixed on both sides of the side of the cut portion including the cut portion. I can raise it. Moreover, since the insulating tape can be stuck so as to cover the vicinity including the cutout portion, slipping and moving of the active material can be suppressed more effectively.

Moreover, in the secondary battery of this invention, it is preferable that the said insulating tape has the adhesive agent uncoated area | region to which the adhesive agent is not apply | coated at both ends, and the adhesive agent application | coating area | region to which the adhesive agent was apply | coated between these uncoated area | regions is provided. .

When the insulating tape of this invention is used, it can be bent and affixed on both ends of one electrode plate, or can be affixed on the edge part of two other electrode plates at once. In particular, when the latter configuration is adopted, the affixation is also easy, and the production efficiency is improved, so that the mass production is optimal.

Moreover, in the secondary battery of this invention, the ratio of the adhesive application area | region width with respect to the sum of the adhesive application area | region width and the width | variety of the adhesive agent uncoated area | region located in the center direction on an active material layer is 25 to 95%, and is a cutting edge side It is preferable that the width | variety of the adhesive agent application area | region located on the active material of is 1.5 mm or more, and the width | variety of the adhesive agent application area | region which is not located on the active material by the cutting edge side is 1.5 mm or more.

In the secondary battery of the present invention, the ratio of the adhesive coating area width to the sum of the adhesive coating area width and the width of the adhesive uncoated area located in the center direction on the active material layer is 25 to 95%, When the width of the adhesive coating area located on the active material is 1.5 mm or more and the width of the adhesive coating area not on the active material on the cut end side is 1.5 mm or more, the active material is prevented from slipping and moving even in various sizes of electrode plates. By minimizing the depletion of the electrolyte solution, it is possible to prevent the occurrence of an electrical short between the electrode plates and the reduction of the battery capacity.

EMBODIMENT OF THE INVENTION Hereinafter, the best embodiment of this invention is described with reference to drawings. However, the embodiment shown below illustrates a rectangular nonaqueous electrolyte secondary battery as an example of a secondary battery for incorporating the technical idea of this invention, and intends to specify this invention to this rectangular nonaqueous electrolyte secondary battery. The other embodiments included in the claims can be similarly adapted.

1A is a front view showing the internal structure of the square nonaqueous electrolyte secondary battery according to the embodiment of the present invention, and FIG. 1B is a sectional view taken along the line IB-IB in FIG. 1A. FIG. 2A is a plan view showing an electrode sheet, and FIG. 2B is a plan view of a positive electrode plate in which the electrode sheet of FIG. 2A is cut and pasted with insulating tape at both ends. 3 is a cross-sectional view taken along the line III-III of FIG. 2B. 4 is a cross-sectional view schematically showing the arrangement of the positive electrode plate, the negative electrode plate, and the separator. FIG. 5 is an enlarged side view showing an end portion of an electrode body using another insulating tape as another embodiment. FIG.

First, as an example of the secondary battery which concerns on this embodiment, a rectangular nonaqueous electrolyte secondary battery is demonstrated using FIG. The rectangular nonaqueous electrolyte secondary battery 10 includes a flat wound electrode group 11 in which the positive electrode plate 14 and the negative electrode plate 15 are wound through a separator (not shown). It accommodates inside and seals the battery exterior body 12 with the sealing plate 13. As shown in FIG.

This flat wound electrode group 11 has no positive electrode core exposed portion 14a that does not form a positive electrode active material layer 14b at an end of at least one side in the winding axis direction, and does not form a negative electrode core which does not form a negative electrode active material layer 15b. The exposed part 15a is provided. The positive electrode core exposed portion 14a is connected to the positive electrode terminal 17 through the positive electrode current collector 16 ₁ , and the negative electrode core exposed portion 15a is connected to the negative electrode terminal 19 through the negative electrode current collector 18. have. The positive electrode terminal 17 and the negative electrode terminal 19 are fixed to the sealing plate 13 via the insulating members 20 and 21, respectively.

The rectangular nonaqueous electrolyte secondary battery 10 inserts the flat wound electrode group 11 into the battery exterior body 12, and then laser-welds the sealing plate 13 to the opening of the battery exterior body 12, Then, it manufactures by pouring a nonaqueous electrolyte from an electrolyte injection hole (not shown), and sealing this electrolyte injection hole.

Of these positive electrode plates 14 and negative electrode plates 15, the cut end portion in the direction orthogonal to the winding direction of at least one positive electrode plate 14 is covered with insulating tape 22 to eliminate slipping and movement of the active material. At the same time, it is configured to suppress exhaustion of the electrolyte solution. Here, with reference to FIG. 2 and FIG. 3, the manufacturing method of the positive electrode plate 14 and the structure of the insulating tape 22 affixed to this positive electrode plate 14 are demonstrated.

The positive electrode plate 14 is produced by cutting the positive electrode sheet 14 _T into the length of each battery cell using the long positive electrode sheet 14 _T shown in FIG. 2A. A long positive electrode sheet (14 _T) is used for a long positive electrode core body sheet having a predetermined width in length in a direction of a length of, and perpendicular to the longitudinal direction in the longitudinal direction, and a positive electrode active material on the both surfaces of the positive electrode core sheet The mixture containing is apply | coated and the positive electrode active material layer 14b is formed. As this positive electrode core sheet, what consists of aluminum, stainless steel, nickel, titanium, or these alloys, and made into thin foil shape is used.

Although the positive electrode active material layer 14b becomes a longitudinal direction and this direction becomes a winding direction, the uncoated area | region which does not apply the positive electrode active material layer 14b over a predetermined width length is provided in the one end, and the positive electrode core 14c is provided. The exposed positive electrode core exposed portion 14a is formed. The positive electrode core exposed portion 14a is bundled after winding, and the positive electrode current collector 16 ₁ is welded together with the positive electrode current collector receiving part 16 ₂ (see FIG. 1). As the positive electrode active material layer 14b, for example, one containing lithium cobaltate is used. In addition, this positive electrode active material layer 14b is formed by a well-known method.

The long positive electrode sheet 14 _T is cut at the dotted line (a) in FIG. 2A to produce one battery positive electrode plate 14. Since a long positive electrode sheet (14 _T) that when cutting opposite ends of the cut electrode plate is a positive electrode active material layer (14b) and the positive electrode core body (14c) is cut off, the cross-section of the positive electrode core body (14c) has the member projection is generated, Moreover, the cross section of the positive electrode active material layer 14b slips easily by the impact at the time of cutting | disconnection. Therefore, it protects by attaching the insulating tape 22 to the end of this at least one side. As the insulating tape 22, two front and back insulating tapes 22A and 22B are used.

These insulating tapes 22A and 22B are each made of an adhesive insulating tape obtained by applying an adhesive 23 to a part thereof, and all have the same configuration. As shown in Fig. 3, the insulating tapes 22A and 22B have a predetermined length L in the longitudinal direction and a predetermined width length in the direction orthogonal to the longitudinal direction, and the adhesive is not coated on one surface. A tape having an uncoated area L ₁ and an adhesive application area L ₂ to which an adhesive is applied is used. As the tape base material, polyethylene, polypropylene, polyester, nylon, vinyl chloride, Teflon (registered trademark), polyimide, kapton (registered trademark), polyphenylene sulfide and the like are used. As the adhesive, an acrylic adhesive, a silicone adhesive, a rubber adhesive or the like is used.

Such insulating tapes 22A and 22B are attached to both ends 14d of the positive electrode plate 14, for example, as shown in FIG. 2B. As shown in the patch is a third of the insulating tape (22A, 22B), towards each of the insulating tape (22A, 22B) the adhesive uncoated region (L ₁₎ toward the center from the end portion (14d), the adhesive application zone ( A partial region L ₂₁ of L ₂ is affixed on the positive electrode active material layer 14b of the end portion 14d, and the remaining region L ₂₂ is affixed so that both tapes 22A and 22B are adhered to each other. That is, the adhesive uncoated region L ₁ is located at a position close to the formation region side (center side) of the positive electrode active material layer 14b from the end portion 14d, and a partial region L ₂₁ of the adhesive coating region L ₂ is present. It is affixed on the positive electrode active material layer 14b of this edge part 14d. By this sticking, since the adhesive agent uncoated region L ₁ abuts on the surface of the positive electrode active material layer 14b, the positive electrode active material layer 14b is prevented from slipping off. Further, in a region (L _1), since the adhesive is not provided, it is not happen to absorb the electrolyte. Since the adhesive uncoated region is provided in a portion near the separator at the end of the insulating tape, absorption of the electrolyte solution in the separator near the end of the insulating tape by the adhesive can be prevented. Further, in the state where the electrode group is formed, since the tight press-in area (L ₁₎ of an insulating adhesive tape uncoated with the active material layer direction and becomes difficult to reach the electrolyte to the adhesive portion of the electrolytic solution is absorbed by the adhesive can be suppressed. Moreover, the adhesive applied area (L _2), but some regions (L ₂₁₎ pasted on the positive electrode active material layer (14b) of the end portion (14d), the same as the conventional example, the width of the insulating tape (22A, 22B), the conventional example with In comparison, the region of the partial region L ₂₁ of the adhesive application region L ₂ attached on the positive electrode active material layer 14b is narrowed, so that absorption of the electrolyte solution can be suppressed to a minimum.

Relationship with the insulating tape (22) total length (L) of the adhesive applied area (L ₂₎ is an adhesive application area (L ₂₎ and more preferably range between 25 and 95% with respect to the tape length (L) Is set in the range of 40 to 60%. When it is set in this range, tape sticking becomes easy and it can prevent effectively that an active material slips. Moreover, cycling characteristics (inhibition of liquid exhaustion) become favorable. In order to effectively prevent slipping of the active material layer, it is preferable that L ₂₁ and L ₂₂ be 1.5 mm or more, respectively.

Like the positive electrode plate 14, the negative electrode plate 15 is also produced by cutting the negative electrode sheet into lengths of individual battery cells using a long negative electrode sheet. Graphite powder is used as a negative electrode active material, for example. Moreover, copper foil is used as a negative electrode collector by which this negative electrode active material is apply | coated.

Although the insulating tape 22 was affixed to the edge part of the positive electrode plate 14, you may stick the same insulating tape to the edge part of this negative electrode plate 15, too. However, it is preferable to stick this insulating tape 22 to the positive electrode plate 14. The reason for this is that the negative electrode plate 15 usually has a larger width and length than the positive electrode plate 14, so that the end portion 14d of the positive electrode plate 14 faces the negative electrode active material layer. For this reason, since the burr | bump in the positive electrode plate edge part 14d and the penetration by an active material slipping off are feared, when applied to the edge part 14d of the positive electrode plate, it becomes more effective.

When the insulating tape 22 uses two tapes 22A and 22B having the same configuration as a set, the insulating tape 22 can be easily pasted to the end portion 14d of the positive electrode plate and the mass production efficiency can be increased. For example, when it is going to stick with one tape, this tape requires bending, annealing, etc., and the sticking operation becomes cumbersome.

In addition, the use of the insulating tape 22 are each an adhesive non-coated area (L _1, L _3), the provided insulating tape (22A ', 22B') at both ends of the adhesive applied area shown in Fig. 5, the direction of the tape It disappears and can halve a tape type. That is, if two tapes 22A and 22B are to be affixed to the pole plate start and end, four tape types are used, which is disadvantageously costly. Therefore, when the insulating tapes 22A 'and 22B' provided with the non-adhesive areas L ₁ and L ₃ respectively provided at both ends of the adhesive coating area are used, the tape loses the directivity, regardless of the electrode plate start or end. Pasting is possible only with two tape species of the sum.

Figure 5 represents in each adhesive at both ends of the adhesive application zone uncoated region (L _1, L ₃₎ to provided insulation tape (22A ', 22B'), if used, the adhesive area applied with a width (L ₂₎ and the active material The ratio of the adhesive coating area width L ₂ to the sum of the adhesive uncoated area width L ₁ located in the center direction on the layer is in the range of 25 to 95%, more preferably in the range of 40 to 60%. It is preferable to be set. When it is set in this range, tape sticking becomes easy, and also slipping of an active material can be prevented effectively. Moreover, cycling characteristics (inhibition of liquid exhaustion) become favorable. In order to effectively prevent slipping of the active material layer, it is preferable that L ₂₁ and L ₂₂ be 1.5 mm or more, respectively.

As the separator 24, an insulating microporous membrane having a predetermined mechanical strength, for example, a polyethylene microporous membrane is used. As the electrolyte, for example, an organic solvent composed of ethylene carbonate (EC): methyl ethyl carbonate (MEC): dimethyl carbonate (DMC) = 30:30:40 dissolved in LiPF ₆ to 1 mol / L as an electrolyte is used. do.

The rectangular nonaqueous electrolyte secondary battery 10 first attaches the insulating tape 22 to the positive electrode plate 14, and interposes the separator 24 with the negative electrode plate 15 to form a flat wound electrode group. (11) is formed. This flat wound electrode group 11 is set so that the positive electrode core exposed portion 14a of the positive electrode plate 14 and the negative electrode core exposed portion 15a of the negative electrode plate 15 do not overlap with the active material layer of the opposite electrode, respectively. It winds up through the polyethylene porous separator and manufactures the flat wound electrode group 11 in which the some positive electrode core exposed part 15a and the some negative electrode core exposed part 16a were formed in both sides, respectively. Next, the positive electrode core exposed portion 14a in the flat wound electrode group 11 is bundled, and the positive electrode collector 16 ₁ and the positive electrode collector receiving part are provided on both sides of the bundled positive electrode core exposed portion 14a. 16 ₂ is abutted, and the positive electrode current collector 16 ₁ is welded to the positive electrode core exposed portion 14a. In this way, the negative electrode current collector 18 is welded to the negative electrode core exposed portion 15a of the negative electrode plate 15.

Next, the positive electrode current collector 16 ₁ is welded to the positive electrode terminal 17 formed on the sealing plate 13, and the negative electrode current collector 18 is welded to the negative electrode terminal 19 formed on the sealing plate 13. . Thereafter, the wound electrode body 11 is inserted into the battery exterior body 12, and the sealing plate 13 is fitted into the opening of the battery exterior body 12 to seal the sealing plate 13 and the battery exterior body 12. Between is welded by laser welding, for example. Then, after inject | pouring electrolyte solution from the electrolyte injection hole (not shown) of the sealing plate 13 battery exterior body, the rectangular nonaqueous electrolyte secondary battery 10 is completed by sealing an electrolyte injection hole.

In the wound electrode group 11 having such a configuration, the adhesive uncoated region L ₁ of the insulating tape 22 is located at a position near the positive electrode active material layer 14b forming region side from the end 14d, and the adhesive is applied. A partial region L _{21 of the} region L ₂ is affixed on the positive electrode active material layer 14b of the end portion 14d of the positive electrode plate 14. By the adhesive patch of the insulating tape 14, the adhesive uncoated region (L _1), so abut the surface of the positive electrode active material layer (14b), sliding in the positive electrode active material layer (14b) can be prevented from falling. Further, in the adhesive agent non-coated area (L _1), because the adhesive does not have, it is not happen to absorb the electrolyte. In addition, since only a part of the region L ₂₁ of the adhesive application region L ₂ is affixed on the positive electrode active material layer 14b of the end portion 14d of the positive electrode plate 14, this affixed region is narrower than that of the conventional example. Absorption of electrolyte solution can be minimized.

[Examples 1 and 2 and Comparative Examples]

The positive electrode active material layer 14b was apply | coated to both surfaces of the aluminum foil positive electrode core 14c, and after drying and rolling, it slit so that the strip | belt-shaped positive electrode core exposed part 14a may be formed in one end side of the width direction, and an Example and The positive electrode plate 14 used as a comparative example was produced. Similarly, after applying a negative electrode active material layer to both surfaces of a copper foil negative electrode core, and drying and rolling, it slit so that the strip | belt-shaped negative electrode core exposed part 15a may be formed in one end side of the width direction, and is carried out by Example 1, 2, and The negative electrode plate 15 used as a comparative example was produced.

In the positive electrode plates of Examples 1 and 2, insulating tapes 22A and 22B were attached to both surfaces of the positive electrode plate 14 so as to have the arrangement shown in FIG. 3. In addition, in the positive electrode plate of Example 1, the adhesive material coating width L ₂ = 4 mm, the uncoated portion width L ₁ = 3 mm, the adhesive coating area width L ₂₁ = 2 mm located on the positive electrode active material, the adhesive not located on the positive electrode active material The coating area width L ₂₂ = 2 mm, and in the positive electrode plate of Example 2, the adhesive material coating width L ₂ = 8 mm, the uncoated portion width L ₁ = 7 mm, the adhesive coating area width L ₂₁ = 4 located on the positive electrode active material mm, the adhesive application is not located on the positive electrode active material has a region width L ₂₂ = 4 mm. In addition, in the positive electrode plate of the comparative example, the adhesive coating area was 7 mm, the adhesive coating area width L ₂₁ = 3.5 mm located on the active material, the adhesive coating area width L ₂₂ = 3.5 mm not located on the active material, and the uncoated width was I saw no.

Thus, the rectangular nonaqueous electrolyte secondary batteries of Examples 1, 2 and Comparative Example were produced as described above using the positive electrode plates of Examples 1, 2 and Comparative Example, respectively. The following high temperature storage test was done using this rectangular secondary battery. The results are summarized in Table 1.

In the high temperature storage test, the rectangular nonaqueous electrolyte secondary batteries of Examples 1, 2 and Comparative Examples in a discharged state are stored at 70 ° C. for 23 days at the beginning of the charge / discharge cycle, and after completion of storage, the nonaqueous electrolyte secondary batteries are disassembled. The degree of electrolyte depletion was examined by visually inspecting the degree of discoloration of the separator. The results are summarized in Table 1. In addition, the cycle characteristics of the rectangular nonaqueous electrolyte secondary batteries of Examples 1 and 2 and the nonaqueous electrolyte secondary battery using the electrode plate without affixing the insulating tape were examined, but the rectangular nonaqueous electrolyte secondary batteries of Examples 1 and 2 were examined. The battery exhibited the same cycle characteristics as that of the square nonaqueous electrolyte secondary battery using an electrode plate without affixing an insulating tape. Therefore, when the insulating tape is affixed by the method of this invention, it is thought that a cycle characteristic will not be reduced.

Glue Application L2` Uncoated Width L1 Adhesive coating area width L21 located on active material Adhesive coating area width not located on active material L22 Depletion of electrolyte in separator Example 1 4 mm 3 mm 2 mm 2 mm Less Example 2 8 mm 7 mm 4 mm 4 mm Less Comparative example 7 mm 0 mm 3.5 mm 3.5 mm plenty

From the results shown in Table 1, according to the nonaqueous electrolyte secondary battery of the present invention, the absorption amount of the electrolyte solution is reduced compared to that of the comparative example in which the adhesive material is applied to the entire surface by leaving the region where the adhesive material is not applied on the active material layer. Confirmed. In addition, although the Example demonstrated the case where the wound electrode group wound around each other in the planar manner using the separator between the positive electrode plate and the negative electrode plate was used, the electrode group of this invention has a positive electrode plate and In the case of a laminated electrode group laminated with each other with a separator interposed between the negative electrode plates, and in the case of a wound electrode group, the same effects and effects are generated in the case of a cylindrical wound electrode group and an elliptic wound electrode group.

FIG. 1A of FIG. 1 is a front view showing the internal structure of the square nonaqueous electrolyte secondary battery according to the embodiment of the present invention, and FIG. 1B is a sectional view taken along the line IB-IB of FIG. 1A.

FIG. 2A of FIG. 2 is a plan view showing an electrode sheet, and FIG. 2B is a plan view of a positive electrode plate in which the electrode sheet of FIG. 2A is cut and pasted with insulating tape at both ends.

3 is a cross-sectional view taken along the line III-III of FIG. 2B.

4 is a cross-sectional view schematically showing the arrangement of the positive electrode plate, the negative electrode plate, and the separator.

FIG. 5 is an enlarged side view showing an end portion of an electrode body using another insulating tape as another embodiment. FIG.

6A of FIG. 6 is a plan view of the electrode material end of a prior art example, FIG. 6B is a sectional view along the VIB-VIB line of FIG. 6A, and FIG. 6C is a longitudinal cross-sectional view of the electrode material end of a separate conventional example.

7A is a plan view of an electrode plate of a separate conventional example, and FIG. 7B is a sectional view taken along the line VIIB-VIIB in FIG. 7A.

<Code description>

DESCRIPTION OF SYMBOLS 10: nonaqueous electrolyte secondary battery, 11: wound electrode group, 12: battery exterior body, 13: sealing plate, 14: positive electrode plate, 14a: positive electrode core exposed part, 14b: positive electrode active material layer, 14c: positive electrode core, 14d: End part (of the positive electrode plate), 14 _T : positive electrode sheet, 15: negative electrode plate, 15a: negative electrode core exposed portion, 16 ₁ : positive electrode current collector, 16 ₂ : positive electrode collector receiving part, 17: positive electrode terminal, 18: negative electrode collector, 19: negative electrode terminal, 20, 21: insulating member 22, 22A, 22B: insulating tape, 23: adhesive, 24: separator, L _1: the adhesive uncoated region, L _2: the adhesive application region, L _3: adhesive Uncoated area

Claims (4)

An insulating tape is applied to at least one of a positive electrode plate having a positive electrode active material layer formed on the surface of the positive electrode current collector and a cut end including the active material layer portion on at least one of the negative electrode plate having a negative electrode active material layer formed on the surface of the negative electrode current collector. And a secondary battery in which electrode groups laminated or wound together with a separator between negative electrode plates are sealed together with an electrolyte in a battery exterior body. The insulating tape is composed of an adhesive insulating tape having an adhesive application region to which the adhesive is applied and an uncoated adhesive region to which the adhesive is not applied, The insulating tape is affixed so that the adhesive uncoated region is located in the center direction on the active material layer of the electrode plate to which the insulating tape is attached, and a part of the adhesive coating region is located on the active material layer on the cut end side. A secondary battery characterized by the above-mentioned. The method according to claim 1, The said electrode plate has active material layers formed in both front and back, and the said insulating tape is affixed on both surfaces by the side of the said cutting part including the said cutting part. The method according to claim 1, The insulating tape has an adhesive uncoated region to which no adhesive is applied at both ends, and an adhesive application region to which an adhesive is applied is provided between the adhesive uncoated regions. The method according to any one of claims 1 to 3, The ratio of the said adhesive application area | region width with respect to the sum of the said adhesive application area | region width and the width | variety of the adhesive agent uncoated area | region located in the center direction on the said active material layer is 25 to 95%, and the said adhesive agent located on the active material by the said cutting edge side The width | variety of application | coating area | region is 1.5 mm or more, and the width | variety of the said adhesive agent application area | region which is not located on the active material by the said cutting edge side is 1.5 mm or more.

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