WO2018124674A2 - Cylindrical battery cell having heat-shrinkable tube comprising ultraviolet stabilizer - Google Patents

Abstract

The present invention relates to a cylindrical battery cell having a heat-shrinkable tube wrapping around an outer surface of a cylindrical case excluding electrode terminal portions, wherein the heat-shrinkable tube comprises: a tube base made of a polyester-based resin having heat shrinkability; a reinforcing agent made of a nylon resin for increasing the tensile strength and use temperature of the heat-shrinkable tube; and an ultraviolet stabilizer for suppressing a chain reaction of free radicals which are generated by polymer chains of a nylon-based resin or a polyester-based resin being cut by ultraviolet rays irradiated to the heat-shrinkable tube.

Description

Cylindrical battery cell with heat-shrinkable tube containing UV stabilizer

This application claims the benefit of priority based on Korean Patent Application No. 2016-0178714 dated December 26, 2016, and all the contents disclosed in the literature of that Korean patent application are incorporated as part of this specification.

The present invention relates to a cylindrical battery cell having a heat shrinkable tube containing an ultraviolet stabilizer.

Recently, the increase in the price of energy sources due to the depletion of fossil fuels, interest in environmental pollution is amplified, and the demand for environmentally friendly alternative energy sources has become an indispensable factor for future life. Accordingly, researches on various power production technologies such as nuclear power, solar energy, wind power, tidal power, etc. continue, and power storage devices for more efficient use of the generated energy are also drawing attention.

In particular, as technology development and demand for mobile devices increase, the demand for batteries as energy sources is rapidly increasing, and in recent years, the use of secondary batteries as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs) has been realized. In addition, the field of use has also been extended to applications such as a power auxiliary power supply through gridization, and thus, many studies on batteries capable of meeting various needs have been conducted.

In general, the secondary battery is a cylindrical battery and a rectangular battery in which the electrode assembly is embedded in a cylindrical or rectangular metal can, and a pouch type battery in which the electrode assembly is embedded in a pouch type case of an aluminum laminate sheet according to the shape of the battery case. Classified as Here, the electrode assembly embedded in the battery case is a power generator capable of charging and discharging composed of a positive electrode, a negative electrode, and a separator structure interposed between the positive electrode and the negative electrode. It is roughly classified into a wound jelly-roll type and a stack type in which a plurality of positive and negative electrodes of a predetermined size are sequentially stacked in a state of being interposed in a separator.

1 schematically shows a vertical cross-sectional perspective view of a conventional cylindrical battery.

Referring to FIG. 1, the cylindrical secondary battery 10 accommodates a jelly-roll type (wound) electrode assembly 12 in a cylindrical case 13 and injects an electrolyte solution into the cylindrical case 13, followed by a case 13. The cap assembly 14 in which the electrode terminal (for example, a positive electrode terminal) is formed in the open upper end of the) is manufactured.

The cylindrical secondary battery covers the outer surface of the battery case using a tube made of a film of an electrically insulating plastic material in order to perform an insulating function and an external protective function with an external conductive material.

However, the outer tube for cylindrical secondary batteries of the prior art had a problem that the original insulation and appearance protection functions are lost, such as damage or discoloration of the film when exposed to ultraviolet (UV) for a long time.

Furthermore, after the tube was added to the outer surface of the battery case of the cylindrical secondary battery, the tube was exposed to high temperature, or the tube was easily deformed due to an external impact, thereby causing problems.

Therefore, there is a high need for a technology that can effectively solve the problems of the prior art described above.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After extensive research and various experiments, the inventors of the present application, as will be described later, the free radical produced by cutting the polymer chain of the nylon resin or polyester resin by ultraviolet rays irradiated to the heat shrinkable tube When the UV stabilizer (UV Stabilizer) that suppresses the chain reaction is included, it was confirmed that the desired effect can be achieved and came to complete the present invention.

Cylindrical battery cell according to the present invention for achieving this object,

A cylindrical battery cell is wrapped around the outer surface of the cylindrical case except for the electrode terminal, the heat shrinkable tube,

The heat shrinkable tube,

Tube base material of polyester resin having heat shrinkability;

Reinforcing agent of nylon-based resin to increase the tensile strength and the use temperature of the heat-shrinkable tube; And

UV stabilizer (UV Stabilizer) to suppress the chain reaction of the free radicals generated by cutting the polymer chain of the nylon resin or polyester resin by the ultraviolet light irradiated to the heat-shrinkable tube;

Characterized in that it includes.

Therefore, the cylindrical battery cell according to the present invention, by including a UV stabilizer that suppresses the chain reaction of free radicals generated by cutting the polymer chain of the nylon resin or polyester resin by ultraviolet rays irradiated to the heat-shrinkable tube, Even if the heat-shrinkable tube is exposed to ultraviolet light for a long time, the film is not damaged or discolored, so that the insulation and appearance protection function of the heat shrinkage can be maintained well.

In addition, the cylindrical battery cell according to the present invention, by using a reinforcing agent of nylon resin to increase the tensile strength and the use temperature of the heat-shrinkable tube in the heat-shrinkable tube is exposed to high temperature, or the tube is easily deformed due to external impact Can be prevented.

The heat-shrinkable tube may further include a pigment for imparting color, and thus may be distinguished and displayed by different colors, such as capacity of a battery cell, and thus may be easily classified and distinguished.

In one specific example, the polyester-based resin may be, for example, polyethylene terephthalate resin.

Specifically, the polyester-based resin may be included in 70% to 90% by weight based on the total weight of the tube, more specifically, when the polyester-based resin is included in less than 70% by weight, Difficult to obtain the proper heat shrinkage rate required by the invention is difficult to properly exhibit the function of the heat shrink tube, on the contrary, when more than 90% by weight when exposed to high temperature easily deformed or deformed of the tube easily occurs.

In one specific example, the thickness of the heat shrinkable tube for the cylindrical secondary battery may be 1 ㎛ to 100 ㎛.

In one specific example, the UV stabilizer may be a benzoate-based compound, specifically, the benzoate-based compound may be butyl-4-hydroxybenzoate.

In addition, the UV stabilizer may be included in 0.1% by weight to 5% by weight based on the total weight of the heat-shrinkable tube, in detail may be included in 0.5% by weight to 5% by weight, more specifically the UV stabilizer When included in less than 0.1% by weight, the function of inhibiting the chain reaction of the generated free radicals of the ultraviolet light stabilizer is not exhibited throughout the tube, it is difficult to prevent the occurrence of cracks due to ultraviolet irradiation, on the contrary, if it exceeds 5% by weight, Too much UV stabilizer is added to the problem that the manufacturing cost is excessively high compared to the UV stabilization efficacy.

In one specific example, the nylon-based resin may be nylon 66, the nylon 66 has a relatively high heat deformation temperature of 70 degrees Celsius, a heat resistance temperature of 105 degrees Celsius, a tensile modulus of 2.9 ㅧ 104 kg / cm2, Flexural modulus is 3.0 ㅧ 104 kg / cm2. Compared to other nylon 6, nylon 6-10 and nylon 6-12, it has high heat resistance and high mechanical rigidity.

In addition, the nylon-based resin may be included in 3% by weight to 10% by weight based on the total weight of the heat shrinkable tube.

In addition, the nylon-based resin may be included in a blended state in the polyester-based resin.

In one specific example, the pigment may be included in 10% to 20% by weight based on the total weight of the heat shrinkable tube.

In one specific example, the heat-shrinkable tube according to the present invention will not generate cracks even after 1000 hours of exposure under the condition that the light intensity of ultraviolet light is 61.5 W / m ² and the wavelength of light is 300 nm to 400 nm. Can be.

In one specific example, the heat-shrinkable tube may further include an ultraviolet absorber for absorbing the emitted ultraviolet rays to release the thermal energy, specifically, the ultraviolet absorber may be a benzophenone-based compound, the benzophenone-based The compound may be, for example, hydroxy benzophenone.

Therefore, the heat-shrinkable tube according to the present invention can not only prevent cracks from occurring in the film as an ultraviolet stabilizer, but also further include an ultraviolet absorber that absorbs the irradiated ultraviolet rays and releases them as thermal energy. It can prevent the oxidation (decomposition) reaction to occur, and can prevent the deterioration of the tube due to ultraviolet rays for a longer time.

In one specific example, the cylindrical battery cell may be a secondary battery, the secondary battery is not particularly limited in its kind, but as a specific example, lithium having advantages such as high energy density, discharge voltage, output stability, etc. Lithium secondary batteries such as ion batteries, lithium ion polymer batteries, and the like.

In general, a lithium secondary battery is composed of a positive electrode, a negative electrode, a separator, and a lithium salt-containing nonaqueous electrolyte.

Hereinafter, other components of the lithium secondary battery will be described.

Specifically, the positive electrode may be prepared by, for example, applying a positive electrode active material composed of positive electrode active material particles to a positive electrode current collector, and a positive electrode mixture in which a conductive material and a binder are mixed. More fillers may be added.

The positive electrode current collector is generally manufactured to a thickness of 3 to 201 μm, and is not particularly limited as long as it has high conductivity without causing chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium , And one selected from surface treated with carbon, nickel, titanium, or silver on the surface of aluminum or stainless steel may be used, and in detail, aluminum may be used. The current collector may form fine irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in various forms such as film, sheet, foil, net, porous body, foam, and nonwoven fabric.

The positive electrode active material may be, for example, in addition to the positive electrode active material particles, a layered compound such as lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _2-x O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO _2, and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiV ₃ O ₄ , V ₂ O ₅ , Cu ₂ V ₂ O _7, and the like; Ni-site type lithium nickel oxide represented by the formula LiNi _1-x M _x O ₂ , wherein M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3; Formula LiMn _2-x M _x O ₂ (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li ₂ Mn ₃ MO ₈ (wherein M = Fe, Co, Lithium manganese composite oxide represented by Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with alkaline earth metal ions; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like, but is not limited to these.

The conductive material is typically added in an amount of 0.1 to 30% by weight based on the total weight of the mixture including the positive electrode active material. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder included in the positive electrode is a component that assists in bonding the active material, the conductive material, and the like to the current collector, and is generally added in an amount of 0.1 to 30 wt% based on the total weight of the mixture including the positive electrode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers, and the like.

The negative electrode is manufactured by coating and drying a negative electrode active material on a negative electrode current collector, and optionally, the components included in the positive electrode described above may be further included as necessary.

The negative electrode current collector is generally made to a thickness of 3 to 500 micrometers. The negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, a surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper, or stainless steel may be used. Surface-treated with carbon, nickel, titanium, silver and the like, aluminum-cadmium alloy and the like can be used. In addition, like the positive electrode current collector, fine concavities and convexities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

As said negative electrode active material, For example, carbon, such as hardly graphitized carbon and graphite type carbon; Li _x Fe ₂ O ₃ (0 ≦ _x ≦ 1), Li _x WO ₂ (0 ≦ _x ≦ 1), Sn _x Me _1-x Me ' _y O _z (Me: Mn, Fe, Pb, Ge; Me': Metal composite oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 <x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , and metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

The separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally from 0.01 to 10 ㎛ ㎛, thickness is generally 5 ~ 300 ㎛. As such a separator, for example, olefin polymers such as chemical resistance and hydrophobic polypropylene; Sheets or non-woven fabrics made of glass fibers or polyethylene are used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The said lithium salt containing non-aqueous electrolyte solution consists of a nonaqueous electrolyte solution and a lithium salt. As the nonaqueous electrolyte, nonaqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like are used, but not limited thereto.

1 is a vertical cross-sectional perspective view of a cylindrical cell of the prior art;

2 is a photograph showing the experimental procedure of Experimental Example 1 of the present invention;

3 is a schematic view for explaining the mechanism of the ultraviolet stabilizer contained in the heat-shrinkable tube of the present invention.

Figure 4 is a photograph showing the results of Example 1 in Experimental Example 2.

5 is a photograph showing the results of Comparative Example 2 in Experimental Example 2.

FIG. 6 shows a stress deformation curve (S-S Curve) of Example 1 in Experimental Example 3. FIG.

7 shows a stress deformation curve (S-S Curve) of Comparative Example 3 in Experimental Example 3.

In the following, with reference to the embodiment according to the present invention, but for the easier understanding of the present invention, the scope of the present invention is not limited thereto.

<Example 1>

80 g of polyethylene terephthalate resin, 2 g of butyl-4-hydroxybenzoate, an ultraviolet stabilizer, 8 g of pigment and 10 g of nylon 66, based on the total weight of the composition The mixture was mixed together and melt blended to prepare a resin composition, and the prepared resin composition was quench-cured in a cooling apparatus to prepare cylindrical heat-shrinkable tubes with open top and bottom.

Comparative Example 1

Heat-shrinkable tubes were prepared in the same manner as in Example 1, except that butyl-4-hydroxybenzoate and nylon 66, which are ultraviolet stabilizers, were prepared without using a UV stabilizer.

Comparative Example 2

A heat shrinkable tube was prepared in the same manner as in Example 1 except that the resin composition was prepared without using butyl-4-hydroxybenzoate, which is an ultraviolet stabilizer.

Comparative Example 3

A heat shrinkable tube was prepared in the same manner as in Example 1 except that the resin composition was prepared without using nylon 66.

Experimental Example 1

2 of the present invention discloses a photograph showing an experimental procedure of Experimental Example 1. As shown in FIG. 2, the heat-shrinkable tubes 110 prepared in Example 1 and Comparative Examples 1 to 3 are disposed 3 cm apart from the lamp of the ultraviolet irradiator 200 so that the light intensity is 61.5 W / m ² and the light is The wavelength was 300 nm to 400 nm, and after exposure for 1,000 hours in an atmosphere condition of 50 degrees Celsius, it was confirmed whether cracks were generated on the tube surface.

	Crack occurrence (○, X)
Example 1	X
Comparative Example 1	○
Comparative Example 2	X
Comparative Example 3	X

Referring to Table 1, cracks were generated in Comparative Example 1, in which both nylon and UV stabilizer were not used, but cracks occurred after 1,000 hours of ultraviolet irradiation in Example 1, Comparative Example 2, and Comparative Example 3. Did not do it. That is, when nylon-based resin is added to the tube base material of the polyester-based resin as in Comparative Example 2, it is possible to prevent cracks in the heat-shrinkable tube due to the elasticity inherent in nylon. In addition, when the ultraviolet ray stabilizer is included in the tube base material of the polyester resin as in Comparative Example 3, the ultraviolet ray stabilizer suppresses the chain reaction of the free radicals generated by cleaving the polymer chains of the nylon resin and the polyester resin. By this, cracks can be prevented from occurring.

In addition, when the nylon-based resin and the ultraviolet stabilizer are included in the tube base material of the polyester-based resin as in Example 1, these synergistic effects occur and the effect of preventing the occurrence of cracks is further enhanced.

On the other hand, Figure 3 is a schematic diagram for explaining the mechanism of the ultraviolet stabilizer contained in the heat shrinkable tube of the present invention. Referring to FIG. 3, free radicals 120 and ultraviolet stabilizers 130 generated by cutting polymer chains of a nylon-based resin or a polyester-based resin by ultraviolet rays irradiated to the heat-shrinkable tube 110 from the ultraviolet irradiator 200. ) May inhibit the chain reaction of the free radicals 120.

Experimental Example 2

The heat-shrinkable tube prepared in Example 1 and the heat-shrinkable tube prepared in Comparative Example 2 were prepared, and black letters were printed on the tube surface. The heat shrinkable tubes were exposed to an ultraviolet irradiator having a light intensity of 61.5 W / m ² and a wavelength of light of 300 nm to 400 nm for 500 hours, and then the color change of the black letters was confirmed. 5 is shown.

4 shows the color change of the heat-shrinkable tube of Example 1, and FIG. 5 shows the color change of the heat-shrinkable tube of Comparative Example 2.

Referring to FIGS. 4 and 5, in Example 1, the color change of the letter is hardly seen in the state before and after the UV irradiation, but in Comparative Example 2, the color of the letter is changed from black to gray. You can see that it is very cloudy. Therefore, when the ultraviolet absorber is included, it does not affect the color change of the tube, but when it is not included, it can be seen that the color change is remarkable.

Experimental Example 3

Using three heat shrinkable tubes manufactured by the method according to Example 1 and three heat shrinkable tubes prepared by the method according to Comparative Example 3, a universal tester (Universal Test) to measure their tensile strength and elongation Machine) was used.

The insulating sheath test specimens were placed in a tester, and then the stress strain curve (SS Curve) was measured while stretching at a constant speed. The results of Example 1 are shown in FIG. 6, and the results of Comparative Example 3 are shown in FIG. 7. The specific values are shown in Table 2 below.

	Example 1	Comparative Example 3
Tensile Strength (Kgf / cm 2 )	636 (average)	569 (average)
Elongation (%)	750 (average)	683 (average)

Referring to Table 2 and FIGS. 6 and 7, the tensile strength and elongation of the heat-shrinkable tube of Example 1 show a remarkably improved value when compared to the heat-shrinkable tube of Comparative Example 3. Accordingly, it can be seen that the heat shrinkable tube including the UV stabilizer and nylon has improved mechanical rigidity than the heat shrinkable tube without the nylon. This is believed to be due to the high tensile strength and elastic nylon.

As confirmed above, the heat-shrinkable tube of the present invention includes a nylon-based resin and an ultraviolet stabilizer in the tube base material, and the heat-shrinkable tube containing any one of the nylon-based resin or the ultraviolet stabilizer may generate cracks. Suppressed. In addition, when the nylon-based resin is included but does not contain an ultraviolet stabilizer, the effect of increasing the tensile strength and elongation can be obtained, but it was confirmed that the color change is remarkable for ultraviolet irradiation.

That is, the present invention exhibits the synergistic effect obtained by including both the nylon-based resin and the ultraviolet absorber, so that cracks can be prevented from occurring in the tube, and discoloration against ultraviolet rays can be prevented.

Although described above with reference to embodiments of the present invention, those skilled in the art will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

As described above, the cylindrical battery cell according to the present invention, UV stabilizer that suppresses the chain reaction of the free radicals generated by cutting the polymer chain of the nylon resin or polyester resin by ultraviolet rays irradiated to the heat-shrinkable tube If it includes, even if the heat-shrinkable tube is exposed to ultraviolet rays for a long time does not damage or discolor the tube has the effect of maintaining the original insulation and appearance protection function well.

In addition, the cylindrical battery cell according to the present invention, by using a reinforcing agent of nylon-based resin to increase the tensile strength and the use temperature of the heat shrinkable tube in the heat shrinkable tube, the tube is exposed to high temperature, or the tube is easily deformed due to external impact It is effective to prevent that.

Claims (15)

1. A cylindrical battery cell is wrapped around the outer surface of the cylindrical case except the electrode terminal portion, the heat shrinkable tube, the heat shrinkable tube,

   Tube base material of polyester resin having heat shrinkability;

   Reinforcing agents of nylon-based resins that increase the tensile strength and the use temperature of the heat-shrinkable tube; And

   UV stabilizers (UV Stabilizer) to suppress the chain reaction of the free radicals generated by cutting the polymer chain of the nylon resin or polyester resin by the ultraviolet rays irradiated to the heat-shrinkable tube;

   Cylindrical battery cell comprising a.
2. The cylindrical battery cell of claim 1, wherein the heat-shrinkable tube further comprises a pigment for imparting color.
3. The cylindrical battery cell of claim 1, wherein the polyester-based resin is a polyethylene terephthalate resin.
4. The cylindrical battery cell of claim 3, wherein the polyester-based resin is included in an amount of 70 wt% to 90 wt% based on the total weight of the tube.
5. The cylindrical battery cell according to claim 1, wherein the heat shrinkable tube for the cylindrical secondary battery has a thickness of 1 µm to 100 µm.
6. The cylindrical battery cell of claim 1, wherein the ultraviolet light stabilizer is a benzoate compound.
7. The cylindrical battery cell of claim 6, wherein the benzoate compound is butyl-4-hydroxybenzoate.
8. The cylindrical battery cell of claim 1, wherein the ultraviolet light stabilizer is included in an amount of 0.1 wt% to 5 wt% based on the total weight of the heat shrinkable tube.
9. The cylindrical battery cell according to claim 1, wherein the nylon-based resin is nylon 66.
10. The cylindrical battery cell of claim 9, wherein the nylon-based resin is included in an amount of 3 wt% to 10 wt% based on the total weight of the heat shrinkable tube.
11. The cylindrical battery cell of claim 2, wherein the pigment is contained in an amount of 10 wt% to 20 wt% based on the total weight of the heat shrinkable tube.
12. According to claim 1, wherein the heat shrinkable tube is characterized in that the crack (crack) does not occur even after exposure for 1,000 hours in the condition that the light intensity is 61.5 W / m ² and the wavelength of light 300 nm to 400 nm Battery cell.
13. The cylindrical battery cell of claim 1, wherein the nylon-based resin is contained in a polyester-based resin in a blended state.
14. The cylindrical battery cell according to claim 1, wherein the heat-shrinkable tube further comprises an ultraviolet absorber that absorbs the irradiated ultraviolet rays and emits them as thermal energy.
15. 15. The cylindrical battery cell according to claim 14, wherein the ultraviolet absorber is a benzophenone compound.

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