JP2006040812A - 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 caused by a reaction between an adhesive of an insulating tape and a positive electrode when left at a high temperature. <P>SOLUTION: An insulating tape 11 adheres to a positive electrode 4. The adhesive of the insulating tape 11 contains 2-ethylhexyl-acrylic acid copolymer and/or methacrylic acid, and butyl acrylic acid of 3 mass% or less of the total mass of the adhesive, or contains 2-ethylhexyl-acrylic acid copolymer and/or methacrylic acid, but does not contain butyl acrylic acid. <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 bonded to the positive electrode, and an electrolyte.

Insulating tape is adhered to the exposed metal part of the electrode plate such as a lithium ion battery, but rubber, acrylic acid, silicone, or epoxy adhesive is used as the adhesive for the insulating tape. (For example, refer to Patent Document 1). Among them, acrylic acid adhesives are widely used because they have appropriate adhesiveness and are easy to handle the tape in the tape attaching process.
JP-A-8-138687

  However, when an acrylic acid adhesive is used, the adhesive dissolves in the electrolyte, weakening the adhesive force and reducing the function of the anti-winding tape, or insulating tape adhesive in the electrolyte. There exists a problem that it melt | dissolves and the melt | dissolved adhesive component reacts with an electrode and reduces the discharge performance of a battery.

  In addition, 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, the active material adjacent to the exposed metal part as well as the exposed metal part In many cases, the adhesive layer of the insulating tape is in direct contact with the active material layer, and the active material reacts with the adhesive at the contact portion, so that the battery is left at high temperature. There is a problem that the battery swells due to gas generation or the battery voltage drops abnormally. Further, 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.

  This invention is made | formed in view of such a situation, and is 3 mass% with respect to the total mass of 2-ethylhexyl-acrylic acid copolymer and / or methacrylic acid, and the adhesive agent of an insulating tape. By including 2-butylhexyl-acrylic acid copolymer and / or methacrylic acid but not including butylacrylic acid, the adhesive between the insulating tape and the positive electrode An object of the present invention is to provide a non-aqueous electrolyte battery that can suppress the occurrence of problems when left at high temperatures due to reaction.

  Further, the present invention relates to an adhesive for an insulating tape, the content of which is 0.01% by mass or less based on the total mass of the adhesive, from the group consisting of a hydroquinone derivative, a phenol compound, and an aromatic amine compound. By including one or more kinds of selected compounds (deterioration preventing agent), it is possible to suppress the deterioration of adhesive strength and to suppress the occurrence of problems when left at high temperatures due to the reaction between the deterioration preventing agent and the positive electrode. Another object is to provide a water electrolyte battery.

  Further, the present invention provides an insulating tape adhesive having a content of 0.01% by mass or less based on the total mass of the adhesive, petroleum resin, rosin resin, alkylphenol resin, styrene resin, water By including one or more kinds of synthetic resins (adhesion imparting agent) selected from the group consisting of petroleum-added resins, the adhesive force is improved and at the time of standing at high temperature due to the reaction between the adhesion imparting agent and the positive electrode. Another object is to provide a non-aqueous electrolyte battery capable of suppressing the occurrence of problems.

  Further, the present invention provides a non-aqueous solution that can suppress the occurrence of problems when left at high temperatures due to the reaction between the insulating tape and the positive electrode by selecting the base material of the insulating tape from the group consisting of polypropylene, polyimide, and polyphenylene sulfide. Another object is to provide an electrolyte battery.

  Another object of the present invention is to provide a non-aqueous electrolyte battery that can suppress the occurrence of problems during standing at high temperatures due to the reaction between the active material and the adhesive even when the electrolyte contains an aromatic compound. And

The nonaqueous electrolyte battery according to the first invention is 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). Composite oxide, tunnel structure or layered structure metal chalcogenide, or positive electrode including tunnel structure or layered structure metal oxide, anode capable of occluding and releasing lithium ions, and cathode and anode short circuit In the non-aqueous electrolyte battery having an insulating tape for preventing the insulating tape, the insulating tape is adhered to the positive electrode, and the adhesive of the insulating tape is composed of 2-ethylhexyl-acrylic acid copolymer and / or methacrylic acid. And 3% by mass or less of butylacrylic acid with respect to the total mass of the adhesive.

The nonaqueous electrolyte battery according to the second invention is 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). Composite oxide, tunnel structure or layered structure metal chalcogenide, or positive electrode including tunnel structure or layered structure metal oxide, anode capable of occluding and releasing lithium ions, and cathode and anode short circuit And the insulating tape is bonded to the positive electrode, and the adhesive of the insulating tape comprises 2-ethylhexyl-acrylic acid copolymer and / or methacrylic acid. It is characterized by containing butylacrylic acid.

  The nonaqueous electrolyte battery according to a third aspect of the present invention is the first or second aspect, wherein the insulating tape adhesive is selected from the group consisting of hydroquinone derivatives, phenolic compounds, and aromatic amine compounds. The content of the compound is 0.01% by mass or less based on the total mass of the adhesive.

  The nonaqueous electrolyte battery according to a fourth invention is the nonaqueous electrolyte battery according to any one of the first to third inventions, wherein the insulating tape adhesive is a petroleum resin, a rosin resin, an alkylphenol resin, a styrene resin, or a hydrogenated petroleum resin. 1 or a plurality of types of synthetic resins selected from the group consisting of: and a content of the synthetic resin is 0.01% by mass or less based on the total mass of the adhesive.

  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 base material of the insulating tape is selected from the group consisting of polypropylene, polyimide, and polyphenylene sulfide.

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

In the first and second inventions, 2-ethylhexyl-acrylic acid copolymer and / or methacrylic acid, which does not easily react with the positive electrode, is used for the adhesive of the insulating tape, and butyl acrylic acid, which is likely to react with the positive electrode, is not used. Alternatively, by using only 3% by mass or less of butylacrylic acid, it is possible to suppress the occurrence of problems when left at high temperatures due to the reaction between the adhesive of the insulating tape and the positive electrode. The butyl group has a higher affinity with the solvent than the 2-ethylhexyl group, so that it can be easily eluted, and since it has a low molecular weight, it is unstable to oxidation and has a high reactivity with lithium cobaltate. Butyl acrylic acid is easily eluted in the electrolyte, and the eluted butyl acrylic acid reacts with the positive electrode to induce self-discharge. In addition, the eluted butylacrylic acid is adsorbed on the separator to cause clogging, and the lithium ion conductivity is lowered, so that the discharge performance is lowered. Furthermore, since the eluted acrylic acid reacts with an electrolyte salt such as LiPF ₆ to hydrolyze and deactivate the electrolyte salt, the discharge performance is lowered. When a lithium-containing transition metal is used for the positive electrode, butylacrylic acid eluted in the electrolyte reacts with the lithium-containing transition metal to elute metal ions. The eluted metal ions are reduced on the negative electrode to become metal dendrite and reach the positive electrode to induce a micro short circuit, which causes an abnormal drop in voltage when left at high temperature. In particular, when an insulating tape is directly attached to the positive electrode active material, the above reaction is likely to occur, and abnormal voltage drop frequently occurs. On the other hand, since 2-ethylhexyl-acrylic acid copolymer is excellent in solvent resistance and methacrylic acid is excellent in adhesiveness, when 2-ethylhexyl-acrylic acid copolymer and methacrylic acid are used in combination, An adhesive having an appropriate adhesive strength and stable even in an electrolyte can be obtained.

  In the third invention, the adhesive for the insulating tape contains one or more kinds of compounds (degradation inhibitors) selected from the group consisting of hydroquinone derivatives, phenolic compounds, and aromatic amine compounds. Force degradation is suppressed. In addition, since the content of the deterioration preventing agent is 0.01% by mass or less with respect to the total mass of the adhesive, it is possible to suppress the occurrence of a problem when left at a high temperature due to the reaction between the deterioration preventing agent and the positive electrode. When the degradation inhibitor is contained in an amount of more than 0.01% by mass, the aromatic functional group contained in the degradation inhibitor is oxidized to generate gas, or cobalt elution is promoted to reduce the voltage. This is not preferable because the possibility of inducing becomes very high and a problem at the time of standing at high temperature due to the reaction between the deterioration preventing agent and the positive electrode is likely to occur.

  In the fourth invention, the insulating tape adhesive is one or more kinds of synthetic resins selected from the group consisting of petroleum resins, rosin resins, alkylphenol resins, styrene resins, and hydrogenated petroleum resins (adhesion imparting). Adhesive strength is improved because it contains (agent). Moreover, since content of an adhesion | attachment imparting agent is 0.01 mass% or less with respect to the total mass of an adhesive agent, generation | occurrence | production of the problem at the time of leaving at high temperature by reaction with an adhesion imparting agent and a positive electrode can be suppressed. When the adhesion-imparting agent is contained in an amount of more than 0.01% by mass, there is a very high possibility that gas will be generated by the reaction between the functional group such as a carboxyl group or hydroxyl group contained in the adhesion-imparting agent and the positive electrode. This is not preferable because a problem during standing at high temperature due to the reaction between the adhesion-imparting agent and the positive electrode tends to occur.

  In the fifth invention, since polypropylene, polyimide, and polyphenylene sulfide have low reactivity with the positive electrode, it is possible to suppress the occurrence of problems when left at high temperature due to the reaction between the insulating tape and the positive electrode.

  In the sixth invention, even when an aromatic compound such as cyclohexylbenzene, 2,4 difluoroanisole, or biphenyl is added to the electrolyte, the adhesive of the insulating tape does not contain or contain butylacrylic acid. However, since it is as small as 3% by mass or less, it is possible to suppress the occurrence of problems when left at high temperature due to the reaction between the active material and the adhesive. When butyl acrylic acid is included in the adhesive, the elution of metal ions or the deposition of metal on the negative electrode is accelerated, and the probability that a micro short circuit will occur becomes very high. This is not preferable because problems at high temperature due to the reaction tend to occur.

  According to the 1st and 2nd invention, generation | occurrence | production of the problem at the time of high temperature leaving by reaction of the adhesive agent of an insulating tape and a positive electrode can be suppressed.

  According to the third aspect of the present invention, it is possible to suppress the deterioration of the adhesive force, and it is possible to suppress the occurrence of a problem when left at a high temperature due to the reaction between the deterioration preventing agent and the positive electrode.

  According to the 4th invention, while improving adhesive force, generation | occurrence | production of the problem at the time of leaving at high temperature by reaction with an adhesion | attachment imparting agent and a positive electrode can be suppressed.

  According to the fifth aspect of the present invention, it is possible to suppress the occurrence of a problem when left at a high temperature due to the reaction between the insulating tape and the positive electrode.

  According to the sixth aspect of the invention, even when the electrolyte contains an aromatic compound such as cyclohexylbenzene, 2,4 difluoroanisole, or biphenyl, the problem of standing at high temperature due to the reaction between the active material and the adhesive is prevented. Can be suppressed.

  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 is a mixture of 90% by mass of LiCoO ₂ as a positive electrode 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 and dispersing distilled water as appropriate to prepare a slurry. . 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 is exposed. (Hereinafter referred to as an insulation processing section). 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 11 uses polyphenylene sulfide (PPS) as a base material and 2-ethylhexylacrylic acid copolymer (2HA) as an adhesive, and the adhesive side is used as an insulating treatment part and a peripheral application part of the positive electrode 4. Glued. The insulating tape 11 is not porous and has a melting point of about 270 ° C. The insulating tape 11 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. The adhesive side of the insulating tape 11 is on the portion of the positive electrode 4 where the aluminum current collector 4a is exposed (insulation processing portion) and the portion where the positive electrode mixture 4b, 4b is applied (peripheral coating portion). It is glued. Further, the insulating tape 11 is bonded to, for example, a current collector exposed portion (insulating portion) at the end of winding of the positive electrode. In this way, the insulating tape 11 is bonded 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 bonded to the peripheral application 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)
As the adhesive for the insulating tape 11, a battery similar to Example 1 was prepared except that 95% by mass of 2-ethylhexylacrylic acid copolymer (2HA) and 5% by mass of methacrylic acid (AA) were used.

(Example 3)
As the adhesive for the insulating tape 11, a battery similar to Example 1 was prepared except that 50% by mass of 2-ethylhexylacrylic acid copolymer (2HA) and 50% by mass of methacrylic acid (AA) were used.

Example 4
As the adhesive for the insulating tape 11, a battery similar to that of Example 1 was prepared except that 5% by mass of 2-ethylhexylacrylic acid copolymer (2HA) and 95% by mass of methacrylic acid (AA) were used.

(Example 5)
A battery similar to that of Example 1 was prepared except that 3% by mass of butylacrylic acid (BA) and 97% by mass of methacrylic acid (AA) were used as the adhesive for the insulating tape 11.

(Example 6)
As the adhesive for the insulating tape 11, a battery was manufactured in the same manner as in Example 1 except that 2% by mass of butylacrylic acid (BA) and 98% by mass of methacrylic acid (AA) were used.

(Example 7)
A battery similar to that of Example 1 was prepared except that 1% by mass of butylacrylic acid (BA) and 99% by mass of methacrylic acid (AA) were used as the adhesive for the insulating tape 11.

(Example 8)
A battery similar to that of Example 1 was manufactured except that 0.5% by mass of butylacrylic acid (BA) and 99.5% by mass of methacrylic acid (AA) were used as the adhesive for the insulating tape 11.

Example 9
A battery similar to that of Example 1 was prepared except that methacrylic acid (AA) was used as an adhesive for the insulating tape 11.

(Example 10)
A battery was prepared in the same manner as in Example 2 except that 0.01% by mass of the hydroquinone derivative was added as a deterioration preventing agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 11)
A battery was prepared in the same manner as in Example 2 except that 0.005% by mass of a phenol-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Example 12)
A battery was manufactured in the same manner as in Example 2 except that 0.01% by mass of the phenol-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Example 13)
A battery was manufactured in the same manner as in Example 2 except that 0.05% by mass of a phenol-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Example 14)
A battery was prepared in the same manner as in Example 2 except that 0.075% by mass of a phenol-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Example 15)
A battery was manufactured in the same manner as in Example 2 except that 0.01 mass% of the aromatic amine-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Example 16)
A battery was manufactured in the same manner as in Example 2 except that 0.01% by mass of a petroleum resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 17)
A battery was manufactured in the same manner as in Example 2 except that 0.005% by mass of a rosin resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 18)
A battery was manufactured in the same manner as in Example 2 except that 0.01% by mass of rosin resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 19)
A battery was manufactured in the same manner as in Example 2 except that 0.05% by mass of rosin resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 20)
A battery was prepared in the same manner as in Example 2 except that 0.075% by mass of rosin resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 21)
A battery was manufactured in the same manner as in Example 2 except that 0.01% by mass of an alkylphenol resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 22)
A battery was manufactured in the same manner as in Example 2 except that 0.01% by mass of a styrene resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 23)
A battery was manufactured in the same manner as in Example 2 except that 0.01% by mass of a hydrogenated petroleum resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Example 24)
A battery similar to that of Example 2 was prepared except that polypropylene (PP) was used as the base material of the insulating tape 11.

(Example 25)
A battery similar to that of Example 2 was prepared using polyimide (PI) as the base material of the insulating tape 11.

(Example 26)
A battery was manufactured in the same manner as in Example 2 except that 2% by mass of cyclohexylbenzene (CHB) was added to the total mass of the electrolytic solution.

(Example 27)
A battery was prepared in the same manner as in Example 2 except that 2% by mass of 2,4 difluoroanisole (2FA) was added to the total mass of the electrolytic solution.

(Example 28)
A battery was prepared in the same manner as in Example 2 except that 2% by mass of biphenyl (BP) was added to the total mass of the electrolytic solution.

(Example 29)
A battery was manufactured in the same manner as in Example 2 except that 90% by mass of LiNiO ₂ was used as the active material of the positive electrode mixture.

(Example 30)
A battery was prepared in the same manner as in Example 2 except that 90% by mass of LiMn ₂ O ₄ was used as the active material for the positive electrode mixture.

(Example 31)
A battery was manufactured in the same manner as in Example 2 except that 90% by mass of LiNi _0.4 Co _0.3 Mn _0.3 O ₂ was used as the active material of the positive electrode mixture.

(Comparative Example 1)
A battery similar to that of Example 1 was manufactured except that the insulating tape 11 was not used.

(Comparative Example 2)
A battery similar to that of Example 1 was prepared except that 5% by mass of butylacrylic acid (BA) and 95% by mass of methacrylic acid (AA) were used as the adhesive for the insulating tape 11.

(Comparative Example 3)
A battery similar to that of Example 1 was prepared except that 95% by mass of butylacrylic acid (BA) and 5% by mass of methacrylic acid (AA) were used as the adhesive for the insulating tape 11.

(Comparative Example 4)
A battery was prepared in the same manner as in Example 2 except that 0.1% by mass of the hydroquinone derivative was added as a deterioration preventing agent with respect to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 5)
A battery was prepared in the same manner as in Example 2 except that 0.1% by mass of the phenol-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 6)
A battery was manufactured in the same manner as in Example 2 except that 0.1 mass% of the aromatic amine-based degradation inhibitor was added as a degradation inhibitor to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 7)
A battery was prepared in the same manner as in Example 2 except that 0.1% by mass of a petroleum resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 8)
A battery was prepared in the same manner as in Example 2 except that 0.1% by mass of rosin resin was added as an adhesion-imparting agent to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 9)
A battery was manufactured in the same manner as in Example 2 except that 0.1% by mass of an alkylphenol resin was added as an adhesion promoter with respect to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 10)
A battery was prepared in the same manner as in Example 2 except that 0.1% by mass of a styrene resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 11)
A battery similar to that of Example 2 was prepared except that 0.1% by mass of a hydrogenated petroleum resin was added as an adhesion-imparting agent with respect to the total mass of the adhesive of the insulating tape 11.

(Comparative Example 12)
A battery similar to that of Example 2 was fabricated using polyethylene terephthalate (PET) as the base material of the insulating tape 11.

(Comparative Example 13)
A battery was manufactured in the same manner as in Comparative Example 3 except that 2% by mass of cyclohexylbenzene (CHB) was added to the total mass of the electrolytic solution.

(Comparative Example 14)
A battery was prepared in the same manner as in Comparative Example 3 except that 2% by mass of 2,4 difluoroanisole (2FA) was added to the total mass of the electrolytic solution.

(Comparative Example 15)
A battery was prepared in the same manner as in Comparative Example 3 except that 2% by mass of biphenyl (BP) was added to the total mass of the electrolytic solution.

(Comparative Example 16)
A battery was prepared in the same manner as in Comparative Example 3 except that 90% by mass of LiNiO ₂ was used as the active material for the positive electrode mixture.

(Comparative Example 17)
A battery was manufactured in the same manner as in Comparative Example 3 except that 90% by mass of LiMn ₂ O ₄ was used as the active material of the positive electrode mixture.

(Comparative Example 18)
A battery was prepared in the same manner as in Comparative Example 3 except that 90% by mass of LiNi _0.4 Co _0.3 Mn _0.3 O ₂ was used as the active material for the positive electrode mixture.

  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 6 show the 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 Examples 1 to 4 and 9 in Table 1, when 2HA and / or AA is used as the adhesive for the insulating tape, the reaction between the positive electrode and the adhesive for the insulating tape hardly occurs, and the battery swells. The voltage drop and the capacity retention rate are all good. For example, almost the same battery swelling, voltage drop, and capacity retention as in Comparative Example 1 without using an insulating tape are obtained. In addition, when using 2HA and AA as an adhesive of an insulating tape, the mixing ratio of one to 5 mass% to 95 mass% is preferable from the point of the ease of handling.

  Further, as shown in Comparative Examples 2 to 3 in Table 1, when AA and 5% by mass or more of BA are used as the adhesive of the insulating tape, 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. Furthermore, 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 rate decreases. However, as shown in Examples 5 to 8 in Table 1, when AA and 3% by mass or less of BA are used as the adhesive of the insulating tape, all of the battery swelling, the voltage drop, and the capacity retention rate are particularly high. No problem. In addition, as shown in Examples 5 to 8 in Table 1, it is more preferable that the BA is smaller because battery swelling, voltage drop, and capacity retention are all better.

  In Table 2, “deterioration resistance” refers to the degree of deterioration of adhesive strength when an insulating tape with an anti-degradation agent added to an adhesive and an unadded insulating tape are left in a 40 ° C. environment for 6 months. Represents. As shown in each Example and each Comparative Example in Table 2, by adding a deterioration preventing agent, the deterioration of the adhesive force is suppressed and the adhesive force is kept good as compared with the case where it is not added.

  However, as shown in Comparative Examples 4 to 6 in Table 2, when 0.1 mass% of the deterioration preventing agent is added, the battery swells and the voltage decreases greatly, and the capacity retention rate decreases. These causes include the fact that the aromatic functional group contained in the degradation inhibitor is oxidized to generate gas, and the cobalt elution is promoted in the same way as when the aromatic additive is added to the electrolyte. It may be possible to induce a voltage drop. On the other hand, as shown in Examples 10 to 15 in Table 2, when the deterioration inhibitor of 0.01% by mass or less is added, all of the battery swelling, voltage drop, and capacity retention are good. . The addition amount of the deterioration inhibitor is preferably 0.01% by mass or less.

  In Table 3, “adhesiveness” represents the degree of adhesive strength between an insulating tape to which an adhesion-imparting agent is added and an unadded insulating tape. As shown in each Example and each Comparative Example of Table 3, by adding an adhesion-imparting agent, the adhesive force is improved and a good adhesive force is obtained as compared with the case where no adhesion is added.

  However, as shown in Comparative Examples 7 to 11 in Table 3, when 0.1% by mass of the adhesion-imparting agent is added, the battery swells and the voltage decreases, and the capacity retention rate decreases. As these causes, many adhesion imparting agents have a functional group such as a carboxyl group or a hydroxyl group, and it is considered that gas is generated by the reaction between these functional group and the positive electrode. On the other hand, as shown in Examples 16 to 23 in Table 3, when the adhesion-imparting agent is 0.01% by mass or less, all of the battery swelling, voltage drop, and capacity retention are good. The addition amount of the adhesion promoter is preferably 0.01% by mass or less. In addition, when adhesiveness is considered, about 0.01 mass% is preferable for the addition amount of an adhesion | attachment imparting agent.

  As shown in Comparative Example 12 in Table 4, when PET is used as the base material of the insulating tape, the battery swells and the voltage decreases greatly, and the capacity retention rate decreases. This is considered to be because a dissolved product obtained by hydrolyzing PET or a reaction between PET and the positive electrode. On the other hand, as shown in Examples 24 to 25 in Table 4, when PP or PI is used for the base material of the insulating tape, all of battery swelling, voltage drop, and capacity retention are good. Therefore, it is preferable to use PPS, PP, or PI, which has low reactivity with the positive electrode, as the base material of the insulating tape.

  As shown in Comparative Examples 13 to 15 in Table 5, when BA and AA are used as the adhesive for the insulating tape and CHB, 2FA, or BP is added to the electrolyte, the voltage drop is abnormally large. In addition, the capacity retention rate is large and decreased. However, with respect to battery swelling, since the voltage drop is large, the reaction between the positive electrode and the electrolyte is suppressed and reduced. The reason for this was that when the battery after the test was disassembled, a large amount of metallic cobalt eluted from the positive electrode active material was deposited on the negative electrode, and therefore the abnormal drop in voltage was caused by the dendrites of metallic cobalt deposited on the negative electrode. This is thought to be due to reaching the positive electrode and causing a short circuit.

  On the other hand, as shown in Examples 26 to 28 in Table 5, when 2HA and AA are used as the adhesive of the insulating tape and CHB, 2FA, or BP is added to the electrolyte, battery swelling, voltage drop, and capacity There is no particular problem with any of the retention rates. Thus, when 2HA and AA are used for the adhesive, there is no particular problem. Therefore, it is presumed that the transition metal oxide is likely to be eluted when BA is combined with the aromatic compound described above.

  As shown in Comparative Examples 16 to 18 in Table 6, when BA and AA are used as the adhesive of the insulating tape and a transition metal oxide is used as the positive electrode active material, the voltage drop increases and the capacity retention rate also increases. It is falling. On the other hand, as shown in Examples 29 to 31 of Table 6, when 2HA and AA were used as the adhesive for the insulating tape and a transition metal oxide was used as the positive electrode active material, battery swelling, voltage drop, and capacity retention There is no particular problem with any of the rates.

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 (6)

A composite oxide, tunnel structure or layered structure 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) A non-aqueous electrolyte comprising a positive electrode containing a metal chalcogenide or a metal oxide having a tunnel structure or a layered structure, a negative electrode capable of occluding and releasing lithium ions, and an insulating tape for preventing a short circuit between the positive electrode and the negative electrode In batteries,
The insulating tape is bonded to the positive electrode;
The adhesive of the insulating tape contains 2-ethylhexyl-acrylic acid copolymer and / or methacrylic acid and 3% by mass or less of butylacrylic acid based on the total mass of the adhesive. Water electrolyte battery. A composite oxide, tunnel structure or layered structure 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) A non-aqueous electrolyte comprising a positive electrode containing a metal chalcogenide or a metal oxide having a tunnel structure or a layered structure, a negative electrode capable of occluding and releasing lithium ions, and an insulating tape for preventing a short circuit between the positive electrode and the negative electrode In batteries,
The insulating tape is bonded to the positive electrode;
The non-aqueous electrolyte battery characterized in that the adhesive of the insulating tape contains 2-ethylhexyl-acrylic acid copolymer and / or methacrylic acid and does not contain butyl acrylic acid.   The adhesive of the insulating tape contains one or more kinds of compounds selected from the group consisting of hydroquinone derivatives, phenolic compounds, and aromatic amine compounds, and the content of the compound is based on the total mass of the adhesive. The nonaqueous electrolyte battery according to claim 1, wherein the content is 0.01% by mass or less.   The adhesive for the insulating tape contains one or more kinds of synthetic resins selected from the group consisting of petroleum resins, rosin resins, alkylphenol resins, styrene resins, and hydrogenated petroleum resins. Content is 0.01 mass% or less with respect to the total mass of an adhesive agent, The nonaqueous electrolyte battery in any one of the Claims 1 thru | or 3 characterized by the above-mentioned.   The nonaqueous electrolyte battery according to any one of claims 1 to 4, wherein the base material of the insulating tape is selected from the group consisting of polypropylene, polyimide, and polyphenylene sulfide.   The nonaqueous electrolyte battery according to claim 1, comprising an electrolyte containing an aromatic compound.

Images