JP2006040813A - Non-aqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery which prevents a problem from occurring, where the problem is deterioration in shelf life caused by a reaction with an adhesive, or the like, and which can improve safety by being insulated with reliability. <P>SOLUTION: A non-aqueous electrolyte battery 1 has a positive electrode 4 capable of storing/emitting lithium ions, a negative electrode 3, a separator 5, an insulating tape 11, and an electrolyte, where the insulating tape 11 in contact with the electrolyte has a second resin layer with a melting point higher than a first resin layer, and a part or the whole of the surface on the first resin layer side of the insulating tape 11 are welded to the positive electrode 4 by thermal welding or ultrasonic welding. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nonaqueous electrolyte battery having a positive electrode, a negative electrode, a separator, an insulating tape, and an electrolyte capable of occluding and releasing lithium ions.

  Adhesive insulating tape that covers exposed metal parts of electrodes such as lithium ion batteries can be polypropylene film (PP), polyphenylene sulfide film (PPS), polyimide film (PI), polyetherimide film (PEI), or syndiotactic A rubber-based, acrylic acid-based, silicone-based, or epoxy-based adhesive is used with an electrically insulating film such as polystyrene as a base material.

  However, since the adhesive insulating tape is sticky, it is difficult to handle when attaching the insulating tape, or the adhesive of the insulating tape dissolves in the electrolyte, leaving the battery standing characteristics or charge / discharge cycle characteristics. There is a problem of lowering. Furthermore, in order to completely prevent contact between the exposed metal parts of the electrode plate, considering the displacement of the position where the insulating tape is applied in the manufacturing process, not only the exposed metal part but also the active material adjacent to the exposed metal part Often the layers are covered with insulating tape. In this case, the adhesive layer of the insulating tape is in direct contact with the active material layer, and the active material and the adhesive agent react at the contact portion, thereby causing a problem that the battery standing characteristics are extremely deteriorated. In addition, when an aromatic compound such as cyclohexylbenzene, 2,4 difluoroanisole, or biphenyl is added to the electrolyte, there is a problem that the above reaction is further accelerated.

As a method of attaching an insulating tape to an electrode without using an adhesive, there is a method of thermally welding a polyolefin film such as polyethylene, polypropylene, or polyethylene terephthalate (see, for example, Patent Document 1). When performing the heat welding, since no adhesive is used, it is possible to prevent the occurrence of problems related to the adhesive such as the deterioration of the leaving characteristics described above.
Japanese Patent Laid-Open No. 10-289696

  However, in the case of heat welding, there is a problem that when the insulating tape is heat-welded, insulation is incomplete, for example, a part of the insulating tape is melted and a metal part is exposed. Further, when a polyolefin film such as polyethylene terephthalate is used, polyethylene terephthalate easily dissolves in the electrolyte solution at a high temperature and easily reacts with the negative electrode, so that there is a problem that the discharge characteristics of the battery are deteriorated.

  This invention is made | formed in view of such a situation, The surface of the said 1st resin layer side surface of the insulating tape which has a 1st resin layer and the 2nd resin layer whose melting | fusing point is higher than this 1st resin layer is provided. By adopting a structure in which part or all is welded to the positive electrode, it is possible to prevent the occurrence of problems such as deterioration in standing characteristics due to the reaction with the adhesive, and also to ensure safety and improve safety. An object is to provide an electrolyte battery.

  In the present invention, the first resin layer includes one or more kinds of synthetic resins selected from the group consisting of polyethylene resin and polypropylene resin, and the second resin layer includes polypropylene resin, polyphenylene sulfide resin, and By including one or more kinds of synthetic resins selected from the group consisting of polyimide resins, the first resin layer can be welded without adversely affecting the second resin layer of the insulating tape, such as opening a hole. Another object is to provide a non-aqueous electrolyte battery.

  Further, the present invention provides a structure in which an insulating tape is welded so as to cover a metal part not covered with the active material layer of the positive electrode and an active material layer around the metal part. It is another object of the present invention to provide a nonaqueous electrolyte battery that can maintain insulation of the metal portion even when it is displaced.

In the present invention, the positive electrode is represented by the composition formula Li _x MO ₂ or Li _y M ₂ O ₄ (where M is one or more transition metals, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2). Even if it contains complex oxide, tunnel structure or layer structure metal chalcogenide, or tunnel structure or layer structure metal oxide, problems such as degradation of standing characteristics due to reaction with adhesives may occur. Another object is to provide a non-aqueous electrolyte battery that can be prevented.

  Another object of the present invention is to provide a non-aqueous electrolyte battery that can prevent the occurrence of problems such as deterioration in standing characteristics due to reaction with an adhesive even when the electrolyte contains an aromatic compound. To do.

  A nonaqueous electrolyte battery according to a first invention includes a positive electrode, a negative electrode, a separator, an insulating tape, and an electrolyte capable of occluding and releasing lithium ions, and the insulating tape is in contact with the electrolyte. The insulating tape has a first resin layer and a second resin layer having a melting point higher than that of the first resin layer, and a part or all of the surface of the insulating tape on the first resin layer side serves as the positive electrode. It is welded.

  The nonaqueous electrolyte battery according to a second invention is the nonaqueous electrolyte battery according to the first invention, wherein the first resin layer includes one or more kinds of synthetic resins selected from the group consisting of a polyethylene resin and a polypropylene resin, and the second resin layer Includes one or more kinds of synthetic resins selected from the group consisting of polypropylene resins, polyphenylene sulfide resins, and polyimide resins.

  A nonaqueous electrolyte battery according to a third invention is the nonaqueous electrolyte battery according to the first or second invention, wherein the positive electrode has a metal part and an active material layer covering most of the metal part, and the insulating tape is an active material. It is characterized by being welded to the positive electrode so as to cover the metal part not covered with the layer and the active material layer around the metal part.

A non-aqueous electrolyte battery according to a fourth invention is the non-aqueous electrolyte battery according to any one of the first to third inventions, wherein the positive electrode has a composition formula of Li _x MO ₂ or Li _y M ₂ O ₄ (where M is one or more transition metals). , 0 ≦ x ≦ 1, 0 ≦ y ≦ 2), a metal chalcogenide having a tunnel structure or a layered structure, or a metal oxide having a tunnel structure or a layered structure.

  The nonaqueous electrolyte battery according to a fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the electrolyte includes an aromatic compound.

  In the first invention, the first resin layer having a low melting point functions as a welding layer, and the insulating tape can be attached to the positive electrode without using an adhesive. Since no adhesive is used, it is possible to prevent the occurrence of problems such as deterioration in storage characteristics due to reaction with the adhesive. In addition, the second resin layer having a high melting point functions as an insulating layer, and even if the first resin layer is thermally welded or ultrasonically welded, it is possible to reliably perform insulation without generating a hole. Even if welding such as thermal welding or ultrasonic welding is performed, insulation can be reliably performed and safety can be improved.

  In the second invention, the melting point of polyethylene such as high density polyethylene, medium density polyethylene, or low density polyethylene used for the first resin layer is 100 ° C. to 120 ° C., and the melting point of polypropylene such as stretched polypropylene resin or unstretched polypropylene. Is around 160 ° C. Further, the melting point of polypropylene used for the second resin layer (provided that the first resin layer is polyethylene) is around 160 ° C., the melting point of polyphenylene sulfide is 270 ° C., and the melting point of polyimide is 500 ° C. or more. Therefore, when heat welding is performed on the insulating tape, the first resin layer having a low melting point is melted, but the second resin layer having a high melting point is not melted. Therefore, there is no adverse effect such as opening a hole in the second resin layer. In addition, the first resin layer can be welded.

  In the third invention, the insulating tape is welded to the positive electrode so as to cover the metal part not covered with the active material layer and the active material layer around the metal part. The insulating tape only needs to cover at least the metal portion so as to insulate the metal portion. However, even if the insulating tape is displaced in the manufacturing process by covering the active material layer around the metal portion, the metal tape can be used. The insulation of the part can be kept.

In the fourth invention, as the positive electrode active material, the composition formula is Li _x MO ₂ or Li _y M ₂ O ₄ (where M is one or more transition metals, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2). Even when transition metal oxides such as complex oxides, tunnel structure or layer structure metal chalcogenides, or tunnel structure or layer structure metal oxides are used, no adhesive is used. In addition, since the insulating tape is welded to the active material layer around the exposed metal portion, the reaction between the conventional active material layer and the adhesive does not occur, and the battery standing characteristics can be prevented from being deteriorated.

  In the fifth invention, even when an aromatic compound such as cyclohexylbenzene or 2,4 difluoroanisole is added to the electrolyte, an insulating tape is formed on the active material layer around the exposed metal portion without using an adhesive. Since it is welded, the reaction between the conventional active material layer and the adhesive does not occur, and it is possible to prevent the battery leaving characteristics from deteriorating.

  According to the first, fourth, and fifth inventions, it is possible to prevent the occurrence of problems such as deterioration of the standing characteristics due to the reaction with the adhesive. Further, it is possible to improve the safety by reliably performing the insulation.

  According to the second invention, the first resin layer can be welded without adversely affecting the second resin layer of the insulating tape such as opening a hole.

  According to the third aspect of the present invention, the insulation of the metal part of the positive electrode can be maintained even when the insulating tape is displaced in the manufacturing process.

  The present invention will be described below with reference to preferred examples. However, the present invention is not limited to the examples, and can be appropriately modified and implemented without departing from the scope of the present invention. .

Example 1
FIG. 1 is a cross-sectional view showing an example of a nonaqueous electrolyte battery according to the present invention. In FIG. 1, 1 is a nonaqueous electrolyte battery (hereinafter referred to as a battery), 2 is an electrode group, 3 is a negative electrode, 4 is a positive electrode, 5 is a separator, 6 is a battery case, 7 is a battery lid, 9 is a negative electrode terminal, 10 Is a negative electrode lead. The electrode group 2 is obtained by winding a negative electrode 3 and a positive electrode 4 with a separator 5 interposed therebetween. The electrode group 2 is housed in an aluminum battery case 6 together with an electrolyte, and the opening of the battery case 6 is sealed by laser welding an aluminum battery lid 7 having a negative electrode terminal 9. The negative electrode 3 is connected to the negative electrode lead 10, and the positive electrode 4 is connected to the battery case 6.

The positive electrode mixture was prepared by mixing 90% by mass of LiCoO ₂ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder, and N-methyl-2- A paste was prepared by dispersing in pyrrolidone (NMP). This paste was uniformly applied to an aluminum current collector with a thickness of 20 μm, dried, and then compression molded with a roll press to produce a positive electrode.

  The negative electrode mixture was prepared by mixing 95% by mass of graphite as a negative electrode active material, 3% by mass of carboxymethyl cellulose as a binder, and 2% by mass of styrene butadiene rubber, and adding distilled water as appropriate to disperse the slurry. did. This slurry was uniformly applied to a 15 μm thick copper current collector, dried at 100 ° C. for 5 hours, and then subjected to compression molding with a roll press to produce a negative electrode.

As the separator, a microporous polyethylene film having a thickness of about 20 μm was used. The separator is porous and has a melting point of 115 ° C to 130 ° C. As the electrolyte, a solution obtained by dissolving 1.1 mol / l of LiPF ₆ in a 3: 7 mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used.

  As described above, in the positive electrode 4, the positive electrode mixture is applied to the aluminum current collector, but the positive electrode mixture is not applied to a part of the aluminum current collector, and the aluminum current collector (metal portion) ) Is exposed (hereinafter referred to as an insulation processing portion). A portion where the insulating treatment portion of the positive electrode 4 and the peripheral positive electrode mixture are applied (hereinafter referred to as a peripheral application portion) is covered with an insulating tape 11.

  The insulating tape is obtained by laminating a first resin layer using an expanded polypropylene resin (OPP) having a thickness of 5 μm and a second resin layer using a polyphenylene sulfide resin (PPS) having a thickness of 10 μm. One resin layer is welded to the insulating treatment part and the peripheral application part of the positive electrode 4. For the welding, thermal welding is used. For example, thermal welding is performed at 225 ° C. for 15 seconds. The insulating tape is not porous and has a melting point of about 270 ° C. The insulating tape is in contact with the electrolyte.

  FIG. 2 is an enlarged cross-sectional view of a main part showing an example of an insulation processing part and a peripheral application part. In the positive electrode 4, the positive electrode mixture 4 b, 4 b is applied to the aluminum current collector 4 a, and the positive electrode mixture 4 b, 4 b is not applied in the vicinity of the center inside of the aluminum current collector 4 a in the drawing. The body 4a is exposed. Further, the negative electrode 3 is coated with the negative electrode mixture 3b, 3b on the copper current collector 3a, but the tip of the copper current collector 3a in the figure is not coated with the negative electrode mixture 3b, 3b. The current collector 3a is exposed. A portion of the positive electrode 4 where the aluminum current collector 4a is exposed (insulation processing portion) and a portion where the positive electrode mixture 4b, 4b is applied (peripheral coating portion) are formed on the first resin layer and the second resin layer. The 1st resin layer of the insulating tape 11 which laminated | stacked the resin layer is heat-welded. The insulating tape 11 is welded to, for example, a current collector exposed portion (insulation processing portion) at the end of the positive electrode winding. In this way, the insulating tape 11 is welded to the insulating treatment part where the current collector (metal part) is exposed, and prevents a short circuit with other metal parts. Further, the insulating tape 11 is also welded to the peripheral coating portion around the insulating processing portion, and even if a positional shift occurs in the manufacturing process, the insulating processing portion and other metal portions are short-circuited. To prevent.

(Example 2)
A battery was manufactured in the same manner as in Example 1 except that the first resin layer of the insulating tape was low density polyethylene (LDPE) and the second resin layer was polyphenylene sulfide resin (PPS).

(Example 3)
A battery was manufactured in the same manner as in Example 1 except that the first resin layer of the insulating tape was medium density polyethylene (MDPE) and the second resin layer was polyphenylene sulfide resin (PPS).

Example 4
A battery was manufactured in the same manner as in Example 1 except that the first resin layer of the insulating tape was high-density polyethylene (HDPE) and the second resin layer was polyphenylene sulfide resin (PPS).

(Example 5)
A battery was manufactured in the same manner as in Example 1 except that the first resin layer of the insulating tape was expanded polypropylene resin (OPP) and the second resin layer was polyimide resin (PI).

(Example 6)
A battery was produced in the same manner as in Example 1 except that the first resin layer of the insulating tape was unstretched polypropylene resin (CPP) and the second resin layer was polyetherimide (PEI).

(Example 7)
A battery was manufactured in the same manner as in Example 1 except that the first resin layer of the insulating tape was low density polyethylene (LDPE) and the second resin layer was polypropylene resin (PP).

(Example 8)
As an electrolyte, 1.1 mol / l of LiPF ₆ and 2% by mass of cyclohexylbenzene (CHB) were dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7. A battery similar to 1 was produced.

Example 9
As an electrolyte, 1.1% by mass of LiPF ₆ and 2% by mass of 2,4 difluoroanisole (2FA) were dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7. Produced the same battery as in Example 1.

(Example 10)
As an electrolyte, 1.1 mol / l of LiPF ₆ and 2% by mass of biphenyl (BP) were dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7. A similar battery was produced.

(Example 11)
The positive electrode mixture uses 90% by mass of LiNiO ₂ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder, and the others are the same as in Example 1. A battery was prepared.

(Example 12)
The positive electrode mixture used 90% by mass of LiMn ₂ O ₄ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder. A similar battery was produced.

(Example 13)
The positive electrode mixture uses 90% by mass of LiNi _0.4 Co _0.3 Mn _0.3 O ₂ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder. Produced the same battery as in Example 1.

(Comparative Example 1)
The first resin layer of the insulating tape is an adhesive layer of 95% by mass of butyl acrylic acid (BA) and 5% by mass of acrylic acid (AA), the second resin layer is polyphenylene sulfide resin (PPS), and the others are Example 1. A similar battery was produced.

(Comparative Example 2)
A battery was prepared in the same manner as in Example 1 except that an insulating tape of stretched polypropylene resin (OPP) (consisting of one layer of OPP) was used.

(Comparative Example 3)
A battery similar to that of Example 1 was fabricated except that no insulating tape was used.

(Comparative Example 4)
As an electrolyte, 1.1 mol / l of LiPF ₆ and 2% by mass of cyclohexylbenzene (CHB) were dissolved in a 3: 7 mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC). A battery similar to 1 was produced.

(Comparative Example 5)
As an electrolyte, 1.1% by mass of LiPF ₆ and 2% by mass of 2,4 difluoroanisole (2FA) were dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7. Produced a battery similar to Comparative Example 1.

(Comparative Example 6)
As an electrolyte, 1.1 mol / l of LiPF ₆ and 2% by mass of biphenyl (BP) were dissolved in a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3: 7. A similar battery was produced.

(Comparative Example 7)
The positive electrode mixture uses 90% by mass of LiNiO ₂ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder. A battery was prepared.

(Comparative Example 8)
The positive electrode mixture uses 90% by mass of LiMn ₂ O ₄ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder, and the others are Comparative Example 1. A similar battery was produced.

(Comparative Example 9)
The positive electrode mixture uses 90% by mass of LiNi _0.4 Co _0.3 Mn _0.3 O ₂ as an active material, 5% by mass of acetylene black as a conductive additive, and 5% by mass of polyvinylidene fluoride (PVDF) as a binder. Produced a battery similar to Comparative Example 1.

  The leaving characteristics (battery swelling, voltage drop, capacity retention) were measured for each of the above-described examples and comparative examples. In the measurement, 10 cells each of the same conditions were produced, and these batteries were charged at a constant current and a constant voltage for 3 hours up to 4.2 V at a current of 600 mA, and then discharged to 3 V at a current of 600 mA. The capacity was measured. After that, the battery was charged at a constant current of 600 mA to 4.2 V for 3 hours, and the battery voltage and battery thickness were measured. Then, the battery voltage and battery thickness were measured at 80 ° C. for 200 hours. Then, the battery voltage drop after being left (voltage drop [mV]) and battery thickness increase (battery swelling [mm]) after being left alone were determined. Then, the battery after being left is discharged to 3 V at a current of 600 mA, the discharge capacity after being left is measured, and the capacity retention rate (= “discharge capacity after being left” ÷ “discharge capacity before being left” × 100 [% ]). Tables 1 to 3 show measurement results of the leaving characteristics (battery swelling, voltage drop, capacity retention). In addition, the measurement result has shown the average of 10 cells.

  As shown in Table 1, the welded portions of Examples 1 to 7 and Comparative Example 1 were insulated without the second resin layer being melted, and sufficient weld strength was obtained. On the other hand, in the welded part of Comparative Example 2, the insulating tape was melted and a hole was formed, and there was a part that was not completely insulated. Moreover, although welding was performed at a lower temperature, sufficient adhesive strength could not be obtained. In addition, the battery of Comparative Example 3 does not use an insulating tape and does not use an adhesive. Therefore, there is no problem in battery swelling, voltage drop, and capacity retention when left standing, but the metal exposed portion ( Since the insulation processing portion is not covered with insulation, there is a high possibility that a short circuit will occur when the separator and the battery are deformed during abnormal overheating.

  Moreover, as shown in Comparative Example 1 of Table 1, when the insulating tape has an adhesive layer (first resin layer) containing BA and AA, gas is generated due to the reaction between the BA and the positive electrode, so that the battery swells. Large and the voltage drop is large. Moreover, since BA reacts with the positive electrode to promote self-discharge or deactivate the positive electrode active material, the discharge resistance of the positive electrode increases and the capacity retention after discharge decreases. On the other hand, in the batteries shown in Examples 1 to 7 in Table 1, since the insulating tape is thermally welded and no adhesive is used, no reaction occurs between the positive electrode and the welded portion, and the battery swells and voltage Both the decrease and the capacity retention are good.

  As shown in Examples 8 to 10 in Table 2, the battery in which the OPP resin layer (first resin layer) is thermally welded is particularly problematic even when CHB, 2FA, or BP is added to the electrolytic solution. It has not occurred. On the other hand, as shown in Comparative Examples 4 to 6 in Table 2, when BA and AA are used for the first resin layer and CHB, 2FA, or BP is added to the electrolyte, the battery voltage after standing is abnormally lowered. (Voltage drop increases). In addition, the capacity retention rate decreases as the voltage drop increases. However, the battery bulge is reduced because the battery voltage is lowered and the reaction between the positive electrode and the electrolyte is suppressed. When the batteries of Comparative Examples 4 to 6 after the test were disassembled, a large amount of metallic cobalt eluted from the positive electrode active material was deposited on the negative electrode. Therefore, the abnormal decrease in voltage was caused by dendrites of metallic cobalt deposited on the negative electrode. This is thought to be due to the fact that reached the positive electrode and caused a short circuit. From this, it is presumed that transition metal oxides are likely to elute when BA is combined with an aromatic compound such as CHB, 2FA, or BP.

As shown in Examples 11 to 13 in Table 3, the battery in which the OPP resin layer (first resin layer) is thermally welded has LiNiO ₂ , LiMn ₂ O ₄ , or LiNi _0.4 Co _0.3 Mn _0.3 O _{2 as the} positive electrode active material. Even when transition metal oxides such as these are used, no particular problem has occurred. On the other hand, as shown in Comparative Examples 7 to 9 in Table 3, an adhesive layer (first resin layer) containing BA and AA is used for the insulating tape, and LiNiO ₂ , LiMn ₂ O ₄ , or LiNi _0.4 is used for the positive electrode active material. A battery using a transition metal oxide such as Co _0.3 Mn _0.3 O ₂ has a large battery swelling, a low voltage (an increase in voltage drop), and a low capacity retention rate.

  In each of the above-described embodiments, the insulating tape is welded by the thermal welding method, but is not limited to the thermal welding, for example, the insulating tape is welded by laser welding, or the insulating tape is welded by ultrasonic welding. It is possible to weld the insulating tape by any welding method such as welding. When the insulating tape is welded, since no adhesive is used, the leaving characteristics are not adversely affected.

  Further, when the insulating tape is welded, it is only necessary to obtain a welding strength that does not cause the insulating tape to be detached and the position is not shifted in the manufacturing process. Therefore, not only the entire surface of the insulating tape on the first resin layer side can be welded, but also a part of the surface of the insulating tape on the first resin layer side can be spot-welded. In particular, when ultrasonic welding is performed, since the positive electrode mixture or the negative electrode mixture may fall off by ultrasonic waves, it is preferable to perform spot welding.

  By making the insulating tape a laminated structure of the first resin layer and the second resin layer, it is possible to prevent the insulating tape from being broken at the time of welding or to form a pinhole, and to perform insulation reliably. In thermal welding, if the melting point of the second resin layer is higher than the melting point of the first resin layer, it is possible to weld only the first resin layer, but the welding can be performed in a shorter time and insulation can be ensured. Therefore, the difference in melting point between the first resin layer and the second resin layer is preferably 40 ° C. or higher. For the first resin layer, PE (LDPE, MDPE, HDPE) (melting point is 100 ° C. to 120 ° C.), PP (CPP) having a melting point of 160 ° C. or less, easy to perform welding, and excellent in electrochemical stability. , OPP) (melting point is around 160 ° C.). The second resin layer is preferably made of PPS (melting point is 270 ° C.) or PI (melting point is 500 ° C. or more), which has a melting point of 200 ° C. or more and excellent thermal stability and electrochemical stability. Polypropylene resin may be mixed with polyethylene. By using those having different strengths and melting points, a more preferable effect can be obtained.

  The thickness of the insulating tape is preferably as thin as possible so as not to affect the thickness of the entire electrode group 2. When the thickness of the insulating tape is larger than 20 μm, the thickness of the portion where the insulating tape is welded is increased and a part of the electrode group is deformed. For example, when the electrode group is inserted into the battery case, the outer periphery of the electrode group is The thickness of the insulating tape is preferably 20 μm or less because there is a possibility that scratches may occur upon contact with the battery case inner wall. Thus, the thickness of the first resin layer and the second resin layer is preferably thin, but in order to ensure insulation, the second resin layer that is an insulating layer is preferably 5 μm or more, more preferably 10 to 10 μm. 20 μm. Moreover, in order to maintain the welding strength, the first resin layer, which is a welding layer, is preferably 2 μm or more, more preferably 3 to 5 μm.

It is sectional drawing which shows an example of the nonaqueous electrolyte battery which concerns on this invention. It is a principal part expanded sectional view which shows the example of an insulation process part and a peripheral application part.

Explanation of symbols

1 battery (non-aqueous electrolyte battery)
2 Electrode group 3 Negative electrode 4 Positive electrode 5 Separator 6 Battery case 7 Battery lid 9 Negative electrode terminal 10 Negative electrode lead

Claims (5)

In a non-aqueous electrolyte battery having a positive electrode, a negative electrode, a separator, an insulating tape, and an electrolyte that can occlude and release lithium ions, and the insulating tape is in contact with the electrolyte,
The insulating tape is
A first resin layer, and a second resin layer having a melting point higher than that of the first resin layer,
A non-aqueous electrolyte battery, wherein a part or all of the surface of the insulating tape on the first resin layer side is welded to the positive electrode. The first resin layer includes one or more kinds of synthetic resins selected from the group consisting of polyethylene resins and polypropylene resins,
2. The nonaqueous electrolyte battery according to claim 1, wherein the second resin layer includes one or more kinds of synthetic resins selected from the group consisting of polypropylene resin, polyphenylene sulfide resin, and polyimide resin. The positive electrode has a metal part and an active material layer covering most of the metal part,
3. The non-aqueous solution according to claim 1, wherein the insulating tape is welded to the positive electrode so as to cover a metal portion not covered with the active material layer and an active material layer around the metal portion. Electrolyte battery. The positive electrode is a composite oxide or tunnel represented by a composition formula Li _x MO ₂ or Li _y M ₂ O ₄ (where M is one or more transition metals, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2). 4. The nonaqueous electrolyte battery according to claim 1, comprising a metal chalcogenide having a structure or a layered structure, or a metal oxide having a tunnel structure or a layered structure. 5. The non-aqueous electrolyte battery according to claim 1, wherein the electrolyte contains an aromatic compound.

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