WO2021024563A1

WO2021024563A1 - Secondary cell, cell pack, electronic device, electric tool, and electric vehicle

Info

Publication number: WO2021024563A1
Application number: PCT/JP2020/018691
Authority: WO
Inventors: 袖山　国雄; 雅文梅川; 幸雄笹川
Original assignee: 株式会社村田製作所
Priority date: 2019-08-08
Filing date: 2020-05-08
Publication date: 2021-02-11

Abstract

Provided is a secondary cell in which an electrode winding body having a structure in which a band-shaped positive electrode and a band-shaped negative electrode are stacked via a separator and wound, and an electrolytic solution are accommodated in an outer can, wherein the outer peripheral surface of the electrode winding body is covered with fixing tape, the fixing tape has an adhesive strength of 0.01 (N/10 mm) or greater in a 180-degree peel test, and, when the tape sticking ratio is defined as the ratio of the length of the fixing tape along the axial direction to the length of the electrode winding body in the axial direction, the tape sticking ratio is 87% or greater.

Description

Rechargeable batteries, battery packs, electronic devices, power tools and electric vehicles

The present invention relates to a secondary battery, a battery pack, an electronic device, an electric tool, and an electric vehicle.

The use of lithium-ion batteries is expanding to electric tools, electric vehicles (including hybrid vehicles), electric aircraft (so-called drones), etc. Since the batteries of electronic devices including these large devices may be damaged by external impact, the impact resistance of the batteries is one of the important factors, and various development studies have been conducted. There is.

Patent Document 1 discloses that the electrode assembly fixing tape fixes the electrode assembly inside a can by, for example, embodying a three-dimensional shape with an electrolyte.

Special Table 2014-503978

However, with the method of Patent Document 1, if an impact is applied many times from the outside, the electrode assembly moves inside the battery can and repeatedly collides, causing damage to the welded portion of the tab and disconnection of the internal circuit. There was a risk.

Therefore, one of the objects of the present invention is to provide a battery that is resistant to external impact.

The present invention relates to a secondary battery in which a band-shaped positive electrode and a band-shaped negative electrode are laminated via a separator, and an electrode winding body having a wound structure and an electrolytic solution are housed in an outer can.
The outer peripheral surface of the electrode winding body is covered with fixing tape,
The fixing tape has an adhesive strength of 0.01 (N / 10 mm) or more in a 180-degree peel test.
When the tape sticking ratio is defined as the ratio of the length of the fixed tape along the axial direction to the axial length of the electrode winding body, the secondary battery has the tape sticking ratio of 87% or more.

Further, the present invention relates to a secondary battery in which a band-shaped positive electrode and a band-shaped negative electrode are laminated via a separator, and an electrode winding body having a wound structure and an electrolytic solution are housed in an outer can.
The outer peripheral surface of the electrode winding body is covered with a fixing tape for one or more turns.
The fixing tape has an adhesive strength of 0.01 (N / 10 mm) or more in a 180-degree peel test.
When the tape coverage is defined as the length of the fixing tape on the second lap that covers the fixing tape on the first lap, the secondary battery has the tape coverage of 5% or more.

Further, the present invention relates to a secondary battery in which a band-shaped positive electrode and a band-shaped negative electrode are laminated via a separator, and an electrode winding body having a wound structure and an electrolytic solution are housed in an outer can.
The outer peripheral surface of the electrode winding body is covered with a fixing tape for one or more turns.
The fixing tape has an adhesive strength of 0.01 (N / 10 mm) or more in a 180-degree peel test.
When the tape sticking ratio is defined as the ratio of the length of the fixed tape along the axial direction to the axial length of the electrode winding body, the tape sticking ratio is 87% or more.
When the tape coverage is defined as the length of the fixing tape on the second lap that covers the fixing tape on the first lap, the secondary battery has the tape coverage of 5% or more.

According to the embodiment of the present invention, it is possible to realize a battery having high impact resistance, which is particularly suitable for relatively large electronic devices such as electric tools, electric vehicles, and electric aircraft. It should be noted that the contents of the present invention are not limitedly interpreted by the effects exemplified in the present specification.

FIG. 1 is a cross-sectional view of a battery according to an embodiment. FIG. 2 is a front view of the electrode winding body to which the fixing tape is attached. FIG. 3 is a diagram used for explaining the amount of tape covering of the fixing tape attached to the electrode winding body. FIG. 4 is a diagram used to explain the height of wrinkles on the fixing tape. FIG. 5 is a connection diagram used for explaining a battery pack as an application example of the present invention. FIG. 6 is a connection diagram used for explaining a power tool as an application example of the present invention. FIG. 7 is a connection diagram used for explaining an unmanned aerial vehicle as an application example of the present invention. FIG. 8 is a connection diagram used for explaining an electric vehicle as an application example of the present invention.

Hereinafter, embodiments and the like of the present invention will be described with reference to the drawings. The explanation will be given in the following order.
<1. Embodiment>
<2. Modification example>
<3. Application example>
The embodiments described below are preferable specific examples of the present invention, and the contents of the present invention are not limited to these embodiments.

In the embodiment of the present invention, a cylindrical lithium ion battery will be described as an example of the secondary battery.

<1. Embodiment>
First, the overall configuration of the lithium ion battery will be described. FIG. 1 is a schematic cross-sectional view of the lithium ion battery 1. As shown in FIG. 1, the lithium ion battery 1 is a cylindrical lithium ion battery 1 in which an electrode winding body 20 is housed inside a battery can 11 (outer can).

Specifically, the lithium ion battery 1 includes a pair of

insulators

12 and 13 and an electrode winding body 20 inside a cylindrical battery can 11. The lithium ion battery 1 may further include any one or more of a heat-sensitive resistance (PTC) element, a reinforcing member, and the like inside the battery can 11.

[Battery can]
The battery can 11 is mainly a member for accommodating the electrode winding body 20. The battery can 11 is a cylindrical container in which one end is opened and the other end is closed. That is, the battery can 11 has an open end portion (open end portion 11N). The battery can 11 contains any one or more of metal materials such as iron, aluminum and alloys thereof. However, on the surface of the battery can 11, any one or more of the metal materials such as nickel may be plated.

[Insulator]
The

insulators

12 and 13 are sheet-like members having a surface substantially perpendicular to the winding axis direction (vertical direction in FIG. 1) of the electrode winding body 20. The

insulators

12 and 13 are arranged so as to sandwich the electrode winding body 20 with each other. As the materials of the

insulators

12 and 13, polyethylene terephthalate (PET), polypropylene (PP), bakelite and the like are used. Bakelite includes paper bakelite and cloth bakelite, which are produced by applying phenolic resin to paper or cloth and then heating it.

[Caulking structure]
A battery lid 14 and a safety valve mechanism 30 are crimped to the open end 11N of the battery can 11 via a gasket 15, and a crimping structure 11R (crimp structure) is formed. As a result, the battery can 11 is sealed in a state where the electrode winding body 20 and the like are housed inside the battery can 11.

[Battery lid]
The battery lid 14 is a member that closes the open end 11N of the battery can 11 in a state where the electrode winding body 20 and the like are housed inside the battery can 11. The battery lid 14 contains the same material as the material for forming the battery can 11. The central region of the battery lid 14 projects in the vertical direction of FIG. On the other hand, a region (peripheral region) of the battery lid 14 other than the central region is in contact with the safety valve mechanism 30 via the PTC element 16.

[gasket]
The gasket 15 is mainly interposed between the bent portion 11P (also referred to as a crimp portion) of the battery can 11 and the battery lid 14, thereby forming a gap between the bent portion 11P and the battery lid 14. It is a member to be sealed. For example, asphalt or the like may be coated on the surface of the gasket 15.

Gasket 15 contains an insulating material. The type of insulating material is not particularly limited, but is a polymer material such as polybutylene terephthalate (PBT) and polyp-mouth pyrene (PP). This is because the gap between the bent portion 11P and the battery lid 14 is sufficiently sealed while the battery can 11 and the battery lid 14 are electrically separated from each other.

[Safety valve mechanism]
The safety valve mechanism 30 mainly releases the internal pressure of the battery can 11 by releasing the sealed state of the battery can 11 as necessary when the internal pressure (internal pressure) of the battery can 11 rises. The cause of the increase in the internal pressure of the battery can 11 is gas generated due to the decomposition reaction of the electrolytic solution during charging and discharging.

[Electrode winder]
In a cylindrical lithium-ion battery, a band-shaped positive electrode 21 and a band-shaped negative electrode 22 are spirally wound with a separator 23 in between and housed in a battery can 11 in a state of being impregnated with an electrolytic solution. Although not shown, the positive electrode 21 and the negative electrode 22 have a positive electrode active material layer and a negative electrode active material layer formed on one or both sides of the positive electrode current collector and the negative electrode current collector, respectively. The material of the positive electrode current collector is a metal foil containing aluminum or an aluminum alloy. The material of the negative electrode current collector is a metal foil containing nickel, nickel alloy, copper or copper alloy. The separator 23 is a porous and insulating film, which enables the movement of lithium ions while electrically insulating the positive electrode 21 and the negative electrode 22.

In order to maintain the winding structure of the electrode winding body 20, a fixing tape 31 (see FIG. 2) is attached to the separator 23 on the outermost layer of the cylindrical surface of the electrode winding body 20. The fixing tape 31 is composed of a base material layer and an adhesive layer. Examples of the base material layer include acrylate-based, urethane-based, epoxy-based, and cellulose-based. As the adhesive layer, an acrylic-based, urethane-based, epoxy-based, silicone-based, or rubber-based adhesive can be used. The pressure-sensitive adhesive may contain additives such as stabilizers, cross-linking agents, and modifiers. As an example, a hydrolysis resistant stabilizer for ester polyurethane resin, a stabilizer for vinyl chloride resin, a cross-linking agent for solvent-based carboxyl group-containing resin (acrylic resin, urethane resin, polyester resin, etc.), and a modifier for epoxy resin. (Reduction of water absorption rate, improvement of adhesion), modifier of thermoplastic polyurethane resin (improvement of hydrolysis resistance, adhesion) can be mentioned.

A space (central space 20C) created when the positive electrode 21, the negative electrode 22 and the separator 23 are wound is provided at the center of the electrode winding body 20, and the center pin 24 is inserted into the central space 20C. (Fig. 1). However, the center pin 24 can be omitted.

The positive electrode lead 25 is connected to the positive electrode 21, and the negative electrode lead 26 is connected to the negative electrode 22 (FIG. 1). The positive electrode lead 25 contains a conductive material such as aluminum. The positive electrode lead 25 is connected to the safety valve mechanism 30 and is electrically connected to the battery lid 14 via the PTC element 16. The negative electrode lead 26 contains a conductive material such as nickel. The negative electrode lead 26 is electrically connected to the battery can 11. The detailed configurations and materials of the positive electrode 21, the negative electrode 22, the separator 23, and the electrolytic solution will be described later.

[Positive electrode]
The positive electrode active material layer contains at least a positive electrode material (positive electrode active material) capable of occluding and releasing lithium, and may further contain a positive electrode binder, a positive electrode conductive agent, and the like. The positive electrode material is preferably a lithium-containing compound (for example, a lithium-containing composite oxide and a lithium-containing phosphoric acid compound).

The lithium-containing composite oxide has, for example, a layered rock salt type or spinel type crystal structure. The lithium-containing phosphoric acid compound has, for example, an olivine-type crystal structure.

The positive electrode binder contains synthetic rubber or a polymer compound. Synthetic rubbers include styrene-butadiene rubbers, fluororubbers and ethylene propylene dienes. The polymer compound is polyvinylidene fluoride (PVdF), polyimide and the like.

The positive electrode conductive agent is a carbon material such as graphite, carbon black, acetylene black or ketjen black. However, the positive electrode conductive agent may be a metal material or a conductive polymer.

[Negative electrode]
The surface of the negative electrode current collector is preferably roughened. This is because the so-called anchor effect improves the adhesion of the negative electrode active material layer to the negative electrode current collector. As a method of roughening, for example, there is a method of forming fine particles by using an electrolytic method and providing unevenness on the surface of the negative electrode current collector. The copper foil produced by the electrolytic method is generally called an electrolytic copper foil.

The negative electrode active material layer contains at least a negative electrode material (negative electrode active material) capable of occluding and releasing lithium, and may further contain a negative electrode binder, a negative electrode conductive agent, and the like.

The negative electrode material includes, for example, a carbon material. This is because a high energy density can be stably obtained because the change in the crystal structure during the occlusion and release of lithium is very small. Further, since the carbon material also functions as a negative electrode conductive agent, the conductivity of the negative electrode active material layer is improved.

The carbon material is graphitizable carbon, non-graphitizable carbon, graphite, low crystallinity carbon, or amorphous carbon. The shape of the carbon material is fibrous, spherical, granular or scaly.

Further, the negative electrode material includes, for example, a metal-based material. Examples of metal-based materials include Li (lithium), Si (silicon), Sn (tin), Al (aluminum), Zr (zinc), and Ti (titanium). Metallic elements form compounds, mixtures or alloys with other elements, such as silicon oxide (SiO _x (0 <x≤2)), silicon carbide (SiC) or carbon-silicon alloys. , Lithium titanate (LTO).

In the lithium ion battery 1, when the open circuit voltage (that is, the battery voltage) at the time of full charge is 4.25 V or more, the same positive electrode active material is used as compared with the case where the open circuit voltage at the time of full charge is low. Also, the amount of lithium released per unit mass increases. As a result, a high energy density can be obtained.

[Separator]
The separator 23 is a porous film containing a resin, and may be a laminated film of two or more types of porous films. The resin is polypropylene, polyethylene and the like.

The separator 23 may have a porous film as a base material layer and may contain a resin layer on one side or both sides thereof. This is because the adhesion of the separator 23 to each of the positive electrode 21 and the negative electrode 22 is improved, so that the distortion of the electrode winding body 20 is suppressed.

The resin layer contains a resin such as PVdF. When forming this resin layer, a solution in which the resin is dissolved in an organic solvent is applied to the base material layer, and then the base material layer is dried. After immersing the base material layer in the solution, the base material layer may be dried. It is preferable that the resin layer contains inorganic particles or organic particles from the viewpoint of improving heat resistance and battery safety. The types of inorganic particles are aluminum oxide, aluminum nitride, aluminum hydroxide, magnesium hydroxide, boehmite, talc, silica, mica, and the like. Further, instead of the resin layer, a surface layer containing inorganic particles as a main component, which is formed by a sputtering method, an ALD (atomic layer deposition) method, or the like, may be used.

[Electrolytic solution]
The electrolytic solution contains a solvent and an electrolyte salt, and may further contain additives and the like, if necessary. The solvent is a non-aqueous solvent such as an organic solvent, or water. An electrolytic solution containing a non-aqueous solvent is called a non-aqueous electrolytic solution. The non-aqueous solvent is a cyclic carbonate ester, a chain carbonate ester, a lactone, a chain carboxylic acid ester, a nitrile (mononitrile), or the like.

A typical example of the electrolyte salt is a lithium salt, but a salt other than the lithium salt may be contained. Lithium salts include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), and trifluoromethanesulfonic acid. Lithium (LiCF ₃ SO ₃ ), dilithium hexafluorosilicate (Li ₂ SF ₆ ), etc. These salts can be mixed and used, and among them, LiPF ₆ and LiBF ₄ are preferably mixed and used from the viewpoint of improving battery characteristics. The content of the electrolyte salt is not particularly limited, but is preferably 0.3 mol / kg to 3 mol / kg with respect to the solvent.

[How to make a lithium-ion battery]
Subsequently, a method for manufacturing the secondary battery will be described. First, when producing the positive electrode 21, the positive electrode mixture is produced by mixing the positive electrode active material, the positive electrode binder and the positive electrode conductive agent. Subsequently, the positive electrode mixture is dispersed in an organic solvent to prepare a pace-shaped positive electrode mixture slurry. Subsequently, a positive electrode mixture slurry is applied to both sides of the positive electrode current collector and then dried to form a positive electrode active material layer. Subsequently, while heating the positive electrode active material layer, the positive electrode active material layer is compression-molded using a roll press machine to obtain the positive electrode 21.

The negative electrode 22 is also manufactured by the same procedure as the positive electrode 21 described above.

Next, the positive electrode lead 25 and the negative electrode lead 26 are connected to the positive electrode current collector and the negative electrode current collector using a welding method, respectively. Subsequently, after laminating the positive electrode 21 and the negative electrode 22 via the separator 23, they are wound and the fixing tape 31 is attached to the outermost peripheral surface of the separator 23 to form the electrode winding body 20. Subsequently, the center pin 24 is inserted into the central space 20C of the electrode winding body 20.

Subsequently, the electrode winding body 20 is housed inside the battery can 11 while sandwiching the electrode winding body 20 between the pair of insulators. Next, one end of the positive electrode lead 25 is connected to the safety valve mechanism 30 by using a welding method, and one end of the negative electrode lead 26 is connected to the battery can 11.

Subsequently, the battery can 11 is processed using a beading processing machine (grooving processing machine) to form a recess in the battery can 11. Subsequently, the electrolytic solution is injected into the battery can 11 to impregnate the electrode winding body 20. Subsequently, the battery lid 14 and the safety valve mechanism 30 are housed together with the gasket 15 inside the battery can 11.

Next, as shown in FIG. 1, the caulking structure 11R is formed by caulking the battery lid 14 and the safety valve mechanism 30 at the open end 11N of the battery can 11 via the gasket 15. Finally, the secondary battery is completed by closing the battery can 11 with the battery lid 14 using a press machine.

Hereinafter, the present invention will be specifically described based on an example in which the fixing tape 31 attached to the electrode winding body 20 is tested using the secondary battery produced as described above. The present invention is not limited to the examples described below.

[Examples 1 to 3]
As shown in FIG. 2, the fixing tape 31 composed of a 40 μm-thick base material layer made of thermoplastic polyurethane and a 10 μm-thick adhesive layer containing an acrylic pressure-sensitive adhesive and a stabilizer is attached to the electrode winding body 20. The lithium ion battery 1 was manufactured by sticking it on a cylindrical surface and setting the tape sticking ratio to 87% or more. Here, the tape sticking ratio is the length of the fixing tape 31 along the axial direction of the electrode winding body 20 with respect to the axial length of the electrode winding body 20 (A in FIG. 2) (in FIG. 2). The ratio of B).

[Comparative Examples 1 and 2]
The same applies to Examples 1 to 3 except that the tape application ratio was set to 86% or less.

[Evaluation]
The above-mentioned lithium ion battery 1 was subjected to an impact test using a rotary drum type drop tester. The impact test is based on the UN38.3 standard. Batteries in which peeling was not visually observed on the fixing tape 31 after the test were accepted (OK in Table 1), and batteries in which peeling was observed were rejected (Table 1). NG).

[Table 1]

Examples 1 to 3 passed the impact test, and Comparative Examples 1 and 2 failed the impact test. From the results in Table 1, it was found that the lithium ion battery 1 is strong against impact when the tape attachment ratio is 87% or more.

[Examples 4 and 5]
As shown in FIG. 2, the fixing tape 31 similar to that of Examples 1 to 3 is attached to the cylindrical surface of the electrode winding body 20 having a peripheral length of 54.67 (mm), and the electrode winding is performed as shown in FIG. A lithium ion battery 1 was produced by coating a body 20 (diameter 17.41 (mm)). At this time, the tape coverage rate was set to 5% or more. Here, the tape covering ratio is the ratio of the tape covering amount to the peripheral length of the electrode winding body 20. The peripheral length of the electrode winding body 20 is the length of one circumference along the circumferential direction of the cylindrical surface of the electrode winding body 20. As shown by the value of C in FIG. 3, the tape covering amount is on the extension covering the cylindrical surface of the electrode winding body 20, and is on the second lap covering the fixing tape 31 on the first lap. This is the length of the fixing tape 31 (in short, the length at which the tapes overlap each other). Further, the length of the fixing tape 31 attached to the electrode winding body 20 in the circumferential direction is referred to as the tape length.

[Comparative Example 3]
The same applies to Examples 4 and 5 except that the tape coverage rate was set to 4%.

[Evaluation]
The above-mentioned lithium ion battery 1 was subjected to an impact test using a rotary drum type drop tester. The impact test is based on the UN38.3 standard. Batteries in which peeling was not visually observed on the fixing tape 31 after the test were accepted (OK in Table 2), and batteries in which peeling was observed were rejected (Table 2). NG).

[Table 2]

Examples 4 and 5 passed the impact test, and Comparative Example 3 failed the impact test. From the results in Table 2, it was found that the lithium ion battery 1 is strong against impact when the tape coverage is 5% or more.

Next, with respect to the fixing tapes 31 of Examples 1 to 5 and Comparative Examples 1 to 3 described above, a sample cut out from the peripheral surface of the electrode winding body 20 (that is, the outermost separator 23) was prepared, and after the high temperature storage test. The adhesive strength and the height of wrinkles of the fixing tape 31 in the above were investigated.

[Example 6]
Polyethylene (PE) is used as the separator 23, and the same fixing tape 31 as in Examples 1 to 3 attached to the peripheral surface (the outermost separator 23) of the electrode winding body 20 is attached together with the separator 23 to a size of 60 (mm). ) X 150 (mm). The fixing tape 31 attached to the separator 23 is placed in a solvent obtained by mixing ethylene carbonate (Ethylene Carbonate, EC) and dimethyl carbonate (DMC) at a volume ratio of 35:65 in an environment of 45 ° C. Soaked for 5 hours.

[Comparative Example 4]
Example 6 except that the fixing tape 31 is composed of a base material layer having a thickness of 40 μm made of thermoplastic polyurethane and an adhesive layer having a thickness of 10 μm (not containing a stabilizer) containing an acrylic pressure-sensitive adhesive. I did the same.

[Evaluation]
With respect to the fixing tape 31 attached to the separator 23 described above, the height of wrinkles was measured, a 180-degree peel test was performed, and the adhesive strength after immersion was measured. The 180-degree peel test uses a method based on JIS Z 0237. After immersing in a mixed solvent in an environment of 45 ° C. for 5 hours, a load of about 20 g is applied with a paper waste cloth to absorb the solvent, and then 30 A 180 degree peel test was performed within minutes. The height of the wrinkles is, for example, the value of S (mean value) shown in FIG.

[Table 3]

In Example 6, the height of the wrinkles was 100 μm and the adhesive strength after immersion was 0.01 (N / 10 mm), whereas in Comparative Example 4, the height of the wrinkles was 50 μm and the adhesive strength was adhesive. The force could not be measured because the fixing tape 31 and the separator 23 were peeled off. The adhesive strength before immersion in the mixed solvent (adhesive strength before immersion) was 0.30 (N / 10 mm) in both Example 6 and Comparative Example 4. The fact that the adhesive strength remains even after immersion as in Example 6 suggests that the structure of the electrode winding body 20 can be maintained even in an environment of 45 ° C. It is considered that this is because the adhesive layer is not easily dissolved in the electrolytic solution due to the stabilizer.

From the results in Table 3, it was found that the adhesive strength of the fixing tape 31 after immersion in the 180-degree peeling test is preferably 0.01 (N / 10 mm) or more. The preferable upper limit of the adhesive strength after immersion is 0.03 (N / 10 mm) or less in the case of this example. This is because it is generally considered that the adhesive strength after immersion does not exceed the adhesive strength before immersion. Further, from the results in Table 3, it was found that the height of the wrinkles of the fixing tape 31 after immersion is preferably 100 μm or more. The preferable upper limit of the wrinkle height after immersion depends on the distance between the electrode winding body 20 and the battery can 11 (outer can). In the case of this example, since the distance between the gaps was 250 μm, the height of the wrinkles is preferably 250 μm or less.

Next, in Example 7, the lithium ion batteries 1 of Examples 1 to 5 were produced, and after the batteries were shipped, an impact test was performed, and at the same time, the physical property values of the fixing tape 31 were measured. The relationship between the pass / fail of the impact test and the characteristics of the tape was examined.

[Example 7]
A lithium ion battery 1 having a battery size of 18650 was produced by using the electrode winding body 20 to which the fixing tape 31 was attached in the same manner as in Examples 1 to 3, and one charge / discharge operation was performed in an environment of 65 ° C. After storing for 36 hours or more and storing at room temperature for several days, the batteries were shipped.

[Comparative Example 5]
Example 7 except that the fixing tape 31 is composed of a base material layer having a thickness of 40 μm made of thermoplastic polyurethane and an adhesive layer having a thickness of 10 μm (not containing a stabilizer) containing an acrylic pressure-sensitive adhesive. I did the same.

[Evaluation]
With respect to the fixing tape 31 of the lithium ion battery 1 shipped from the battery, the presence or absence of adhesiveness was determined, the height of wrinkles was measured, the tape length change rate was measured, and an impact test was conducted. Whether it is sticky or not is visually determined whether it is in a fixed state or a peeled state, and when the fixing tape 31 remains stuck, it is regarded as a fixed state (OK in Table 4), and when it is peeled, it is in a peeled state (Table 4). NG). The height of the wrinkles is, for example, the value of S (mean value) shown in FIG. Further, regarding the length of the fixing tape 31 (B in FIG. 2) along the axial direction of the electrode winding body 20, the length before charging / discharging is defined as B1, and the length in the battery shipping state is defined as B2. Then, the tape length change rate was set to (B2-B1) / B1. The impact test was performed using a rotary drum type drop tester, and it was based on the UN38.3 standard. Batteries in which peeling was not visually observed on the fixing tape 31 after the test were accepted (OK in Table 4), and peeling was performed. The accepted batteries were rejected (NG in Table 4).

[Table 4]

In Example 7, the fixing tape 31 was in a fixed state, the height of the wrinkles was 100 μm, and the tape length change rate was -1% (the fixing tape shrank), whereas in Comparative Example 5, it was fixed. When the tape 31 was peeled off, the height of the wrinkles was 50 μm, and the tape length change rate was 5% (the fixed tape was stretched). Further, in the impact test, the battery of Example 7 passed, and the battery of Comparative Example 5 failed.

Since the fixing tape 31 of the seventh embodiment is fixed in the state of shipment of the battery, the structure of the fixing tape 31 is maintained. In addition, the reason why the battery of Example 7 passed the impact test is that the fixing tape 31 swells in the outer peripheral direction of the electrode winding body 20 by the height of the wrinkles during immersion in the electrolytic solution, so that the wrinkles are prevented from slipping. (Or, the probability that the wrinkles of the fixing tape 31 and the inner surface of the battery can 11 come into contact with each other increases), and it is considered that the electrode winding body 20 is fixed in the battery can 11. In Example 7, the reason why the fixing tape shrank is considered to be the occurrence of relatively high wrinkles of 100 μm.

On the other hand, in Comparative Example 5, since the fixing tape 31 was peeled off, the structure of the electrode winding body 20 was not maintained and the height of the wrinkles of the fixing tape 31 was relatively low, so that the wrinkles were prevented from slipping. It is probable that the battery of Comparative Example 5 failed the impact test because it was insufficient and the electrode winding body 20 was not fixed in the battery can 11. In Comparative Example 5, the reason why the fixing tape was stretched is considered to be related to the relatively small height of the wrinkles.

From the results in Table 4, lithium is obtained when the height of the wrinkles is 100 μm or more, or when the fixing tape 31 is contracted in the axial direction of the electrode winding body 20 in the battery shipping state and / or after shipping. It was found that the ion battery 1 is strong against impact.

<2. Modification example>
Although one embodiment of the present invention has been specifically described above, the content of the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. ..

Regarding the fixed tape 31, the tape sticking ratio may be 87% or more and the tape covering ratio may be 5% or more. At this time, the lithium ion battery 1 is considered to be more resistant to impact.

The size of the lithium ion battery 1 was partially set to 18650, but it may be another size such as 21700. The adhesive layer is said to contain a polyacrylic adhesive, but other adhesives may be used.

Unless deviating from the gist of the present invention, the present invention applies to batteries other than lithium-ion batteries and batteries other than cylindrical batteries (for example, laminated batteries, square batteries, coin batteries, button batteries). It is also possible. In this case, the shape of the "outer peripheral surface of the electrode winding body" may be not only a cylindrical shape but also an elliptical shape or a flat shape.

<3. Application example>
(1) Battery pack FIG. 5 is a block diagram showing a circuit configuration example when the secondary battery according to the embodiment or embodiment of the present invention is applied to the battery pack 330. The battery pack 300 includes a switch unit 304 including an assembled battery 301, a charge control switch 302a, and a discharge control switch 303a, a current detection resistor 307, a temperature detection element 308, and a control unit 310. The control unit 310 can control each device, perform charge / discharge control at the time of abnormal heat generation, and calculate and correct the remaining capacity of the battery pack 300.

When charging the battery pack 300, the positive electrode terminal 321 and the negative electrode terminal 322 are connected to the positive electrode terminal and the negative electrode terminal of the charger, respectively, and charging is performed. Further, when the electronic device connected to the battery pack 300 is used, the positive electrode terminal 321 and the negative electrode terminal 322 are connected to the positive electrode terminal and the negative electrode terminal of the electronic device, respectively, and discharge is performed.

The assembled battery 301 is formed by connecting a plurality of secondary batteries 301a in series and / or in parallel. In FIG. 5, the case where the six secondary batteries 301a are connected in two parallels and three series (2P3S) is shown as an example, but any connection method may be used.

The temperature detection unit 318 is connected to a temperature detection element 308 (for example, a thermistor), measures the temperature of the assembled battery 301 or the battery pack 300, and supplies the measured temperature to the control unit 310. The voltage detection unit 311 measures the voltage of the assembled battery 301 and each of the secondary batteries 301a constituting the assembled battery 301, A / D converts the measured voltage, and supplies the measured voltage to the control unit 310. The current measuring unit 313 measures the current using the current detection resistor 307, and supplies the measured current to the control unit 310.

The switch control unit 314 controls the charge control switch 302a and the discharge control switch 303a of the switch unit 304 based on the voltage and current input from the voltage detection unit 311 and the current measurement unit 313. The switch control unit 314 controls the switch unit 304 to turn off when any voltage of the secondary battery 301a becomes equal to or lower than the overcharge detection voltage or the overdischarge detection voltage, or when a large current suddenly flows. By sending a signal, overcharging, overdischarging, and overcurrent charging / discharging are prevented.
Here, when the secondary battery is a lithium ion secondary battery, the overcharge detection voltage is determined to be, for example, 4.20 V ± 0.05 V, and the over discharge detection voltage is determined to be, for example, 2.4 V ± 0.1 V.

After the charge control switch 302a or the discharge control switch 303a is turned off, charging or discharging is possible only through the diode 302b or the diode 303b. As these charge / discharge switches, semiconductor switches such as MOSFETs can be used. In this case, the parasitic diodes of the MOSFET function as diodes 302b and 303b. Although the switch portion 304 is provided on the + side in FIG. 5, it may be provided on the − side.

The memory 317 is composed of a RAM or a ROM, and includes, for example, an EPROM (Erasable Programmable Read Only Memory) which is a non-volatile memory. The memory 317 stores in advance the numerical values calculated by the control unit 310, the battery characteristics in the initial state of each secondary battery 301a measured at the stage of the manufacturing process, and the like, and can be rewritten as appropriate. Further, by storing the fully charged capacity of the secondary battery 301a, the remaining capacity can be calculated in cooperation with the control unit 310.

(2) Electronic device The secondary battery according to the embodiment or embodiment of the present invention described above can be mounted on a device such as an electronic device, an electric transport device, or a power storage device and used to supply electric power. ..

Electronic devices include, for example, laptop computers, smartphones, tablet terminals, PDAs (personal digital assistants), mobile phones, wearable terminals, video movies, digital still cameras, electronic books, music players, headphones, game consoles, pacemakers, hearing aids, etc. Examples include power tools, televisions, lighting equipment, toys, medical equipment, and robots. In a broad sense, electronic devices may also include electric transport devices, power storage devices, power tools, and electric unmanned aerial vehicles, which will be described later.

Examples of electric transportation equipment include electric vehicles (including hybrid vehicles), electric motorcycles, electrically assisted bicycles, electric buses, electric carts, unmanned transport vehicles (AGV), railway vehicles, and the like. It also includes electric passenger aircraft and electric unmanned aerial vehicles for transportation. The secondary battery according to the present invention is used not only as a power source for driving these, but also as an auxiliary power source, a power source for energy regeneration, and the like.

Examples of the power storage device include a power storage module for commercial or household use, a power storage power source for a building such as a house, a building, an office, or a power generation facility.

(3) Power Tool With reference to FIG. 6, an example of an electric screwdriver as an electric tool to which the present invention can be applied will be schematically described. The electric screwdriver 431 is provided with a motor 433 that transmits rotational power to the shaft 434 and a trigger switch 432 that is operated by the user. By operating the trigger switch 432, a screw or the like is driven into the object by the shaft 434.

The battery pack 430 and the motor control unit 435 are housed in the lower housing of the handle of the electric screwdriver 431. As the battery pack 430, the battery pack 300 described above can be used.
The battery pack 430 is built into the electric screwdriver 431 or is detachable. The battery pack 430 can be attached to the charging device in a state of being built in or removed from the electric driver 431.

Each of the battery pack 430 and the motor control unit 435 is equipped with a microcomputer. Power is supplied from the battery pack 430 to the motor control unit 435, and charge / discharge information of the battery pack 430 is communicated between both microcomputers. The motor control unit 435 can control the rotation / stop and the rotation direction of the motor 433, and can cut off the power supply to the load (motor 433 and the like) at the time of over-discharging.

(4) Electric Unmanned Aerial Vehicle An example in which the present invention is applied to a power source for an electric electric unmanned aerial vehicle 440 (hereinafter, simply referred to as “drone 440”) will be described with reference to FIG. The drone 440 of FIG. 7 has a cylindrical or square tubular body portion 441, support shafts 442a to 442f fixed to the upper part of the body portion, and a battery portion (not shown) arranged below the body portion. The aircraft is constructed from. As an example, the body portion has a hexagonal tubular shape, and six support shafts 442a to 442f extend radially from the center of the body portion at equiangular intervals.

Motors 443a to 443f as power sources for the rotary blades 444a to 444f are attached to the tips of the support shafts 442a to 442f, respectively. The control circuit unit 445 that controls each motor is attached to the upper part of the body portion 441. As the battery unit, the secondary battery or the battery pack 300 according to the present invention can be used. The number of secondary batteries and battery packs is not limited, but it is preferable that the number of rotor blades (three in FIG. 7) forming a pair is equal to the number of battery packs. Further, although not shown, the drone 440 may be equipped with a camera or a loading platform capable of carrying a small amount of cargo.

(5) Power Storage System for Electric Vehicles As an example of applying the present invention to a power storage system for electric vehicles, FIG. 8 schematically shows a configuration example of a hybrid vehicle (HV) that employs a series hybrid system. The series hybrid system is a vehicle that runs on a power driving force converter using the electric power generated by an engine-powered generator or the electric power temporarily stored in a battery.

The hybrid vehicle 600 includes an engine 601, a generator 602, a power driving force converter 603 (DC motor or AC motor; hereinafter simply referred to as "motor 603"), drive wheels 604a, drive wheels 604b, wheels 605a, and wheels 605b. , Battery 608, vehicle control device 609, various sensors 610, and charging port 611 are mounted. The battery pack 300 of the present invention described above or a power storage module equipped with a plurality of secondary batteries of the present invention can be applied to the battery 608. The shape of the secondary battery is cylindrical, square or laminated.

The motor 603 is operated by the electric power of the battery 608, and the rotational force of the motor 603 is transmitted to the

drive wheels

604a and 604b. The rotational force of the engine 601 is transmitted to the generator 602, and the electric power generated by the generator 602 by the rotational force can be stored in the battery 608. The various sensors 610 control the engine speed via the vehicle control device 609, and control the opening degree of a throttle valve (not shown). The various sensors 610 include a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

When the hybrid vehicle 600 is decelerated by a braking mechanism (not shown), the resistance force at the time of deceleration is applied to the motor 603 as a rotational force, and the regenerative power generated by this rotational force is stored in the battery 608. Further, although not shown, an information processing device (for example, a battery remaining amount display device) that performs information processing on vehicle control based on information on the secondary battery may be provided. The battery 608 can receive electric power and store electricity by being connected to an external power source via the charging port 611 of the hybrid vehicle 600. Such an HV vehicle is called a plug-in hybrid vehicle (PHV or PHEV).

Although the series hybrid vehicle has been described above as an example, the present invention can also be applied to a parallel system in which an engine and a motor are used together, or a hybrid vehicle in which a series system and a parallel system are combined. Furthermore, the present invention is also applicable to an electric vehicle (EV or BEV) or a fuel cell vehicle (FCV) that travels only with a drive motor that does not use an engine.

1 ... Lithium ion battery, 11 ... Battery can, 12, 13 ... Insulator, 20 ... Electrode winder, 21 ... Positive electrode, 22 ... Negative electrode, 23 ... Separator , 24 ... Center pin, 25 ... Positive electrode lead, 26 ... Negative electrode lead, 31 ... Fixed tape

Claims

In a secondary battery in which a band-shaped positive electrode and a band-shaped negative electrode are laminated via a separator, an electrode winding body having a wound structure, and an electrolytic solution are housed in an outer can.
The outer peripheral surface of the electrode winding body is covered with a fixing tape.
The fixing tape has an adhesive strength of 0.01 (N / 10 mm) or more in a 180-degree peeling test.
A secondary battery having a tape sticking ratio of 87% or more when the tape sticking ratio is defined as the ratio of the length of the fixed tape along the axial direction to the axial length of the electrode winding body.
In a secondary battery in which a band-shaped positive electrode and a band-shaped negative electrode are laminated via a separator, an electrode winding body having a wound structure, and an electrolytic solution are housed in an outer can.
The outer peripheral surface of the electrode winding body is covered with a fixing tape for one or more turns.
The fixing tape has an adhesive strength of 0.01 (N / 10 mm) or more in a 180-degree peeling test.
A secondary battery having a tape coverage of 5% or more when the tape coverage is defined as the length of the fixing tape on the second lap that covers the fixing tape on the first lap.
In a secondary battery in which a band-shaped positive electrode and a band-shaped negative electrode are laminated via a separator, an electrode winding body having a wound structure, and an electrolytic solution are housed in an outer can.
The outer peripheral surface of the electrode winding body is covered with a fixing tape for one or more turns.
The fixing tape has an adhesive strength of 0.01 (N / 10 mm) or more in a 180-degree peeling test.
When the tape sticking ratio is defined as the ratio of the length of the fixed tape along the axial direction to the axial length of the electrode winding body, the tape sticking ratio is 87% or more.
A secondary battery having a tape coverage of 5% or more when the tape coverage is defined as the length of the fixing tape on the second lap that covers the fixing tape on the first lap.
The secondary battery according to any one of claims 1 to 3, wherein the fixing tape is contracted in a direction along the axial direction of the electrode winding body.
The secondary battery according to any one of claims 1 to 4, wherein the height of the wrinkles of the fixing tape is 100 μm or more.
The fixing tape according to any one of claims 1 to 5, wherein the fixing tape has a base material layer made of thermoplastic polyurethane, an acrylic pressure-sensitive adhesive, and a pressure-sensitive adhesive layer containing at least one of a cross-linking agent, a stabilizer or a modifier. Secondary battery.
The secondary battery according to any one of claims 1 to 6, wherein the adhesive strength of the fixing tape is 0.03 (N / 10 mm) or less.
The secondary battery according to any one of claims 1 to 7, wherein the height of the wrinkles of the fixing tape is 250 μm or less.
The secondary battery according to any one of claims 1 to 8.
A control unit that controls the secondary battery and
A battery pack having an exterior body containing the secondary battery.
An electronic device having the secondary battery according to any one of claims 1 to 8 or the battery pack according to claim 9.
An electric tool having the battery pack according to claim 9 and using the battery pack as a power source.
The secondary battery according to any one of claims 1 to 8 is provided.
An electric vehicle having a conversion device that receives electric power from the secondary battery and converts it into the driving force of the vehicle.