KR20230060477A - Cylindrical secondary battery - Google Patents

Abstract

The present invention is a cylindrical secondary battery in which a separator is interposed between a sheet-shaped positive electrode and a negative electrode and a rolled-up jelly roll-shaped electrode assembly is housed in a battery case, wherein the electrode assembly includes a metal current collector at the outermost part, A cylindrical secondary battery in which an insulating member having a width of 0.1 mm to 2 mm is spirally provided on a partial region of an outer circumferential surface of a metal current collector to fix the jelly roll shape.

Description

Cylindrical secondary battery {CYLINDRICAL SECONDARY BATTERY}

The present invention relates to a cylindrical secondary battery with improved resistance and stability by introducing an insulating member having a specific width on the outer circumferential surface of a jelly roll electrode assembly including a metal current collector at the outermost portion.

With the development of the information society, personal IT devices and computer networks are developed, and as the overall society's dependence on electrical energy increases, technology development for efficiently storing and utilizing electrical energy is required.

Among the technologies developed for this purpose, the most suitable technology for various uses is a secondary battery-based technology, and among them, a lithium secondary battery with the highest theoretical energy density is in the limelight.

Lithium secondary batteries have an operating voltage of about 3.6V, about three times the capacity of nickel-cadmium batteries or nickel-hydrogen batteries, which are widely used as power sources for electronic equipment, and have a high energy density per unit weight, so their utilization is high. It is on a rapidly growing trend.

A lithium secondary battery includes an electrode assembly in which a positive electrode plate coated with a positive electrode active material and a negative electrode plate coated with a negative electrode active material are disposed with a separator interposed therebetween, an electrolyte, and an exterior material for sealing and housing them together.

The lithium secondary battery may be classified into a can-type secondary battery and a pouch-type secondary battery according to the shape of a battery case. The can-type secondary battery can be further classified into a cylindrical secondary battery and a prismatic secondary battery according to the shape of the metal can, and can be manufactured by housing a jelly roll-type electrode assembly in which a cathode, a separator, and a cathode are wound in a metal can. . The pouch-type secondary battery may be manufactured by embedding a stack-type electrode assembly in which a plurality of positive electrodes, separators, and negative electrodes are sequentially stacked in a pouch made of an aluminum laminate sheet and then sealing the pouch.

On the other hand, since the lithium secondary battery is frequently moved and can be accommodated inside a machine that experiences strong vibration, such as a car, portability and vibration-resistant characteristics are required.

In the case of a cylindrical secondary battery using a metal can, optimization is performed by changing the thickness of a current collector or separator, and the size or shape of an exterior material in order to put a large amount of electrodes in a limited space.

As one of the methods, a method of using an electrode current collector as an outer tab has been proposed. It is a method of removing the electrode tab and the separator existing in the conventional electrode assembly so that the current collector physically contacts the cylindrical can to allow current to flow.

Through this method, the outer diameter can be reduced and the manufacturing cost can be reduced by reducing the amount of use of the separator and the electrode tab. In addition, the space freed up can be used to realize capacity or improve output.

However, when the electrode assembly including the outermost electrode current collector is fixed with the finishing tape, the contact area between the electrode current collector and the can is reduced by the amount of the area where the finishing tape is formed, so the area for direct current and heat transmission is also reduced. There is a problem with doing it.

Therefore, it is necessary to develop a cylindrical secondary battery that solves these problems.

Korean Patent Publication No. 10-2021-0004102

The present invention has been proposed to solve the above problems, and to provide a cylindrical secondary battery in which performance degradation due to a finishing tape is minimized in a metal current collector included in an outer circumferential surface of an electrode assembly and resistance and conductivity are improved.

According to one embodiment, the present invention is a cylindrical secondary battery in which a separator is interposed between a sheet-shaped positive electrode and a negative electrode and a rolled-up jelly roll-shaped electrode assembly is accommodated in a battery case,

The electrode assembly includes a metal current collector at the outermost part,

Provided is a cylindrical secondary battery in which an insulating member having a width of 0.1 mm to 2 mm is spirally provided on a partial region of an outer circumferential surface of the metal current collector to fix the jelly roll shape.

The cylindrical secondary battery of the present invention includes an insulating member that serves to fix the jelly roll-shaped electrode assembly to maintain a rolled state, and the metal positioned at the outermost part of the electrode assembly by adjusting the width and attachment form of the insulating member. It has the effect of increasing the contact area between the current collector and the battery case, enhancing conductivity, and lowering resistance.

1 is a view showing a laminated structure before winding an electrode assembly of the present invention in a jelly roll form.
2 is a schematic view showing the structure of an electrode assembly in the form of a jelly roll according to an exemplary embodiment of the present invention.
3 is a schematic diagram showing a state in which an insulating member is spirally provided on an electrode assembly according to an exemplary embodiment of the present invention.
4 is a schematic diagram showing a state in which copper foil or an insulating member is provided on the electrode assembly in Reference Example 1 and Comparative Example 1 of the present invention.
5 is a schematic diagram showing a state in which copper foil is provided on the electrode assembly in Reference Example 2 of the present invention.
6 is a graph showing the results of measuring AC internal resistance for batteries prepared in Examples and Comparative Examples of the present invention.

Hereinafter, the present invention will be described in more detail.

In this specification, when a member is said to be located 'on' another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

In this specification, when a certain part is said to 'include' a certain component, this means that it may further include other components, not excluding other components unless otherwise stated.

In this specification, 'height direction' means a direction shown as H in the cylindrical structure as shown in FIG.

In this specification, 'width direction' refers to a direction indicated by W in a cylindrical structure as shown in FIG. 1 .

In the cylindrical secondary battery according to the present invention, a separator is interposed between a sheet-shaped positive electrode and a negative electrode, and a jelly roll-shaped electrode assembly is stored in a battery case. In addition, the electrode assembly includes a metal current collector at an outermost portion, and an insulating member having a width of 0.1 mm to 2 mm is spirally provided on a partial region of an outer circumferential surface of the metal current collector to fix the jelly roll shape.

Specifically, in the present invention, the resistance of the cylindrical secondary battery is lowered and safety is improved through a method of maximizing the contact area between the metal current collector and the battery case by winding an insulating member in a spiral thread shape on the metal current collector, which is the outermost layer of the electrode assembly. want to improve

Hereinafter, each configuration of the cylindrical secondary battery will be described in detail.

electrode assembly

The electrode assembly 100 according to the present invention has a jelly-roll shape in which a separator 40 is interposed and wound between a sheet-shaped positive electrode 50 and negative electrode 30. Here, the interposition of the separator means that the positive electrode, the separator, the negative electrode, the separator, and the positive electrode are alternately stacked in order to prevent a short circuit between the positive electrode and the negative electrode, and the separator is positioned between the electrodes. The sheet-type positive electrode 50 includes a positive electrode current collector made of a thin metal plate having excellent conductivity, for example, aluminum foil, and a positive electrode active material layer coated on both sides thereof, and the sheet-type negative electrode 30 includes a thin metal plate having excellent conductivity, For example, it includes a negative electrode current collector 20 made of copper (Cu) or nickel (Ni) foil and a negative electrode active material layer 10 coated on both sides thereof.

The cathode active material layer may include a cathode active material such as lithium metal oxide containing metals such as cobalt, manganese, and/or nickel, and lithium, and may further include a conductive material and/or a binder, if necessary. As the cathode active material, the conductive material, and the binder, various materials commonly used in the manufacture of secondary batteries may be used without limitation.

The negative electrode active material layer may be a carbonaceous material such as natural graphite or artificial graphite; metals or alloys composed of the metals; oxides of the above metals; and a negative electrode active material such as a composite of the metal and carbon, and may further include a conductive material and/or a binder as needed. As the anode active material, conductive material, and binder, various materials commonly used in the manufacture of secondary batteries may be used without limitation.

The separator 40 included in the electrode assembly is a conventional porous polymer film used as a separator conventionally, for example, ethylene homopolymer, propylene homopolymer, ethylene and butene copolymer, ethylene and hexene copolymer, and ethylene and A polyolefin-based porous polymer film such as a methacrylate copolymer may be used alone or in a laminated manner. In addition, a polyolefin-based porous polymer film coated with inorganic particles (eg, Al ₂ O ₃ ) or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, etc. may be used, but is limited thereto. it is not going to be

metal current collector

According to the present invention, the electrode assembly includes a metal current collector at the outermost part. The metal current collector is provided as an outer tab that physically contacts the cylindrical battery case and passes current. In this way, when the metal current collector serves as an outer tab, the electrode tab existing in the conventional electrode assembly and Since the space in the cylindrical secondary battery can be secured by removing the separator, the secured space can be used to realize capacity and improve output while reducing costs. In addition, since the area to which heat is directly transferred increases, heat generation can also be reduced.

According to one embodiment of the present invention, the metal current collector is made of a metal foil and may be in contact with a portion of an inner circumferential surface of the battery case. Specifically, the metal current collector may be nickel foil, silver foil or copper foil, preferably copper foil.

According to an exemplary embodiment of the present invention, the metal current collector may be a part of an anode current collector or a part of a cathode current collector, and in the present invention, a representative case of a part of an anode current collector will be described. Specifically, according to one embodiment of the present invention, the metal current collector corresponds to the negative electrode uncoated portion on which the negative electrode active material is not formed on the negative electrode current collector, and forms the outermost part of the jelly roll electrode assembly when wound among them. means An example in which the outermost metal current collector is a part of the negative electrode current collector is shown in FIGS. 1 and 2, respectively. FIG. 1 shows a laminated structure before winding an electrode assembly in a jelly-roll form, and FIG. 2 shows a jelly-roll structure in which the laminated structure of FIG. 1 is wound in a winding direction. Of the negative electrode current collector 20 of FIG. 1, a portion of the negative electrode uncoated portion on which the negative electrode active material layer 10 is not formed surrounds the outermost periphery of the jelly roll as shown in FIG. 2 to form the outermost metal current collector 102. , Except for the outermost metal current collector 102 and the swelling tape 101 attached to the inner circumferential surface thereof, constitute the remaining area of the jelly roll as shown in 90 of FIG.

According to one embodiment of the present invention, the thickness of the metal current collector may be 10 μm to 30 μm, specifically 15 μm to 25 μm.

swelling tape

According to one embodiment of the present invention, the electrode assembly may further include a swelling tape 101 whose volume expands when electrolyte is injected. Specifically, the swelling tape may be attached to the inner circumferential surface of the metal current collector as shown in FIG. 2, and may be attached to a partial region of the negative electrode uncoated portion as shown in FIG. 1 before winding.

When the swelling tape is attached to the outer circumferential surface of the metal current collector, that is, the outermost part of the electrode assembly, the portion to which the swelling tape is attached after being inserted into the case may have a reduced resistance reduction effect by the finishing tape of the present invention. , the swelling tape is preferably attached to the inner circumferential surface of the metal current collector.

The swelling tape It serves to fill and fix the gap between the electrode assembly and the metal current collector. Specifically, the swelling tape is a film or sheet shape having an expansion property when in contact with a fluid such as a liquid, and may have a circular shape, a triangular shape, or an amorphous shape in addition to a square shape. In addition, the swelling tape may have a width in a width direction of 17 μm to 40 μm.

According to one embodiment of the present invention, the swelling tape may be attached to a partial region of the electrode assembly through an absorption pad, and the absorption pad may use a material commonly used for attachment of a conventional swelling tape without limitation. However, for example, acrylic adhesives, urethane-based adhesives, epoxy-based adhesives, silicone-based adhesives, and rubber-based adhesives may be used as the suction pad.

According to an exemplary embodiment of the present invention, the swelling tape may be provided on an area of 30% or more and 70% or less of the total area of the inner circumferential surface of the outermost metal current collector, and preferably, an area of 40% or more and 60% or less. can be provided in In this case, it is preferable in terms of preventing the formation of pores between the metal current collector and the swelling tape when attaching through the suction pad while securing a sufficient swelling effect.

As the swelling tape, various polymer materials commonly used, specifically polyacrylate, thermoplastic polyurethane (TPU), polyvinyl chloride, polyethylene terephthalate, polyethylene, polypropylene, polyamide, polycarbonate, polyimide and polystyrene One or more polymeric materials may be used. Preferably, the swelling tape may be polyurethane.

The thickness of the swelling tape may be selected in consideration of the three-dimensional shape to be implemented or the size of the gap to be filled, etc., and is preferably formed to a thickness of 30 μm to 60 μm, more preferably 40 μm to 55 μm. can

Insulation member

In the cylindrical secondary battery according to the present invention, an insulating member 103 having a width of 0.1 mm to 2 mm is provided on a portion of the outer peripheral surface of the metal current collector so that the jelly roll-shaped electrode assembly can be maintained in a rolled state, as shown in FIG. It is equipped with a spiral. The insulating member may preferably have a width of 0.5 mm to 1.8 mm, more preferably 1 mm to 1.5 mm. In FIG. 3, 'T' means the width of the insulating member 103, and for convenience, the width of the insulating member is described as being constant in all sections, but it may be provided in a form having an irregular width although it is included within the numerical range. there is.

The insulating member should have a width of 0.1 mm or more to prevent unwinding of the jelly roll. In addition, since the width of the insulating member is 2 mm or less, the swelling tape is sufficiently inflated, and a sufficient heating area can be secured by maximizing the contact area between the metal current collector and the battery case, and thus safety against heat can be secured.

In addition, in the form of spirally winding a narrow insulation member like a thread, the resistance of the battery can be reduced because the swelling tape can swell over the entire area of the electrode assembly, and the conventional method of finishing tape only on the top and bottom ends It is possible to prevent the lifting phenomenon of the outermost metal current collector in the central part. At this time, the insulating member may be wound on the outer circumferential surface of the metal current collector 3 to 15 times, preferably 5 to 15 times, and more preferably 8 to 12 times.

According to an exemplary embodiment of the present invention, the area of the insulating portion formed by the insulating member is 5% to 20%, preferably 8% to 17%, more preferably 10% of the total area of the outer circumferential surface of the metal current collector. % to 15%.

According to an exemplary embodiment of the present invention, the insulating member may be a polyimide (PI) film, a polyethylene terephthalate (PET) film, a polyethylene (PE) film, or a polyurethane (PU) film, preferably a polyimide film. can be

Polyimide (PI) is a high molecular material with thermal stability based on a strong aromatic main chain, and has excellent durability based on the chemical stability of the imide ring. In addition, since it has excellent electrical properties such as insulating properties and low permittivity, it is preferable as a sealing material for fixing the shape of a jelly roll.

Meanwhile, the polyimide film may be a polyimide tape having an adhesive layer having a thickness of 1 μm to 10 μm formed on either side of both sides, and the thickness of the polyimide tape may be 10 μm to 30 μm. The adhesive layer may be formed by applying an acrylic adhesive, a urethane adhesive, an epoxy adhesive, a silicone adhesive, and a rubber adhesive, and preferably may be an acrylic adhesive layer coated with an acrylic adhesive.

The polyimide film preferably has a width of 0.1 mm or more in order to prevent unwinding of the jelly roll. In addition, when it has a width of 2 mm or less, the swelling tape is sufficiently swollen, and the area in which the metal current collector and the battery case come into contact is maximized to ensure a sufficient heating area, thereby ensuring safety against heat. desirable.

Cylindrical Secondary Battery

Next, a cylindrical secondary battery according to the present invention will be described.

A cylindrical secondary battery according to the present invention includes the electrode assembly, a metal current collector, an electrolyte, and a cylindrical battery case accommodating them.

Since the electrode assembly and the metal current collector have been described above, a description thereof will be omitted, and other components will be described below.

(1) electrolyte

The cylindrical secondary battery according to the present invention includes an electrolyte to enable the movement of lithium ions generated by electrochemical reactions in electrodes during charging and discharging.

As such an electrolyte, a liquid electrolyte containing a non-aqueous organic solvent in which lithium salt is dissolved, or a gel polymer electrolyte containing a gelable polymer resin in the non-aqueous organic solvent may be used without limitation.

The lithium salt may be used without particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlO _{4 , LiAlCl 4 ,} LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ . LiCl, LiI, or LiB(C ₂ O ₄ ) ₂ or the like may be used. The concentration of the lithium salt may be appropriately changed within a commonly usable range, but it is preferable to use it within the range of 0.1 to 5.0M, preferably 0.1 to 3,0M.

The non-aqueous organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. For example, cyclic carbonate-based solvents such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate, linear solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, and ethylmethyl carbonate (EMC) A carbonate-based organic solvent or a mixed organic solvent thereof may be used.

The electrolyte can easily penetrate and expand between the polymers constituting the swelling tape.

(2) Cylindrical battery case

The electrode assembly of the present invention is accommodated inside a cylindrical battery case (not shown), and a cap assembly may be coupled to the top of the battery case. The cap assembly may be formed by sequentially stacking a safety band, a current blocking device, a PTC device, and a top cap. In particular, the top cap is seated on the uppermost part of the cap assembly and coupled thereto, and transmits current generated in the secondary battery to the outside.

The inner surface of the cylindrical battery case of the present invention may be made of a material having a relatively good affinity with the electrolyte, such as aluminum (Al) or iron (Fe).

The cylindrical secondary battery according to the present invention can be manufactured by a conventional method.

Specifically, the above-described electrode assembly is accommodated in a cylindrical battery case (cylindrical can), and the above-described electrolyte is injected into the cylindrical battery case.

Thereafter, the secondary battery may be manufactured by assembling the secondary battery by a known method of fixing the cap assembly to the opening of the battery case, and then performing a conventional post-processing process, such as a conversion process and an aging process.

At this time, the conversion process is a process of activating the battery by repeating charging and discharging after assembling the battery. In the formation process, lithium ions from lithium metal oxide used as a cathode during charging are moved to and inserted into a carbon electrode used as a cathode. At this time, since lithium is highly reactive, it reacts with the carbon anode, Li ₂ CO ₃ , LiO , LiOH, etc., and these form a film called SEI (Solid Electrolyte Interface) on the surface of the carbon electrode.

In addition, the aging process is a process in which the battery is left for a certain period of time to stabilize the SEI film. In general, the aging process is performed by exposing the secondary battery that has undergone the assembly step to an environment of 50° C. to 70° C. for 18 hours to 36 hours.

The cylindrical secondary battery may be applied to various devices. These devices can be applied to means of transportation such as electric bicycles, electric vehicles, hybrids, etc., but are not limited thereto and can be applied to various devices that can use secondary batteries.

Since the cylindrical secondary battery according to the present invention has low resistance and excellent safety, it can be applied to the field of electric vehicles such as electric bicycles, electric vehicles, hybrid electric vehicles (HEV), etc., but is not limited thereto, and secondary batteries can be used. Applicable to a variety of devices that can

Accordingly, according to another embodiment of the present invention, a battery module including the cylindrical secondary battery as a unit cell and a battery pack including the same are provided.

The battery module or battery pack may include a power tool; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); Alternatively, it may be used as a power source for one or more medium or large-sized devices among power storage systems.

Hereinafter, preferred embodiments of the present invention will be described in detail.

<Example: Manufacturing of Cylindrical Secondary Battery>

Example 1.

With the structure shown in FIG. 1, a sheet-type polyethylene separator 40, a positive electrode (anode current collector: Al foil, positive electrode active material: LiCoO ₂ ) 50, a polyethylene separator 40, and a negative electrode (negative electrode current collector: Cu foil, negative electrode) Active material: artificial graphite) (30) were sequentially laminated and wound together to prepare a jelly-roll shaped electrode assembly as shown in FIG.

Before winding, a swelling tape 101 made of polyurethane was attached to a region of the Cu foil where the negative electrode active material was not formed using a silicone adhesive. At this time, the swelling tape had a width of 20 mm in the width direction and a height direction of the swelling tape. A length of 62 mm and a thickness of 52 μm were used. The swelling tape was 4 mm apart from the end of the Cu foil, and after winding, the swelling tape was attached to the inner circumferential surface of the outermost Cu foil.

Polyimide tape (manufactured by Tapex, PI Tape) having a width (T) of 1 mm to 1.5 mm as an insulating member 103 for fixing a jelly roll shape on the manufactured electrode assembly is spirally formed from top to bottom as shown in FIG. It was attached so that a total of 10 times were wound. The polyimide tape has an acrylic adhesive layer having a thickness of 5 μm on one side of both sides, and a total thickness including the adhesive layer is 23 μm. At this time, of the total area of the outer circumferential surface of the outermost Cu foil, the area around which the polyimide tape was wound, that is, the area of the insulating portion, was about 12%.

Thereafter, after housing the electrode assembly in a cylindrical battery case, ethylene carbonate (EC): ethyl methyl carbonate (EMC) was mixed in a volume ratio of 30:70, and LiPF ₆ was dissolved to 1.0 M. , The cylindrical secondary battery was completed by sealing the upper part of the case with the cap assembly.

Reference example 1.

In order to fix the shape of the jelly roll, instead of the polyimide tape, winder sealing is performed so that copper foil 103' having a width (T) of 14 mm and a length of 61 mm is wound on the upper and lower ends of the electrode assembly once each in the form shown in FIG. A cylindrical secondary battery was prepared in the same manner as in Example 1, except that it was attached using an adhesive (polymers of HEMA, HEA, AA, and MAA) using a group.

Reference example 2.

In order to fix the shape of the jelly roll, instead of the polyimide tape, a copper foil 103 'with a width (a) of 15 mm and a length (b) of 55 mm is wound in the form shown in FIG. A cylindrical secondary battery was prepared through the same process as in Example 1, except for attaching through polymers of HEA, AA, and MAA).

Comparative Example 1.

A cylindrical secondary battery was manufactured through the same process as in Reference Example 1, except that a polyimide tape having a width (T) of 14 mm was used instead of the copper foil to fix the jelly roll shape. At this time, the area around which the polyimide tape was wound was about 42% of the total area of the outer circumferential surface of the outermost Cu foil.

Comparative Example 2.

Except for using a polyimide tape having a width (T) of more than 2 mm and less than or equal to 3 mm instead of a polyimide tape having a width (T) of 1 mm to 1.5 mm as an insulating member for fixing the jelly roll shape, the same as in Example 1 A cylindrical secondary battery was manufactured through the same process. At this time, the area around which the polyimide tape was wound was about 24% of the total area of the outer circumferential surface of the outermost Cu foil.

<Experimental Example 1: Evaluation of Battery Characteristics and Direct Current Internal Resistance (DC-IR)>

50 battery samples were prepared by the methods described in Example 1, Reference Examples 1 and 2, and Comparative Examples 1 and 2, respectively, and after measuring the weight of each sample, formation was performed with a current of 200 mA (0.1 C rate). After the process, the battery is moved to a charger and discharger at room temperature (25℃), and then charged under constant current/constant voltage conditions up to 4.2V at a rate of 0.33C and charging with a 0.05C cut off, followed by discharging to 2.5V at a rate of 0.33C. conducted. The state of charge (SOC) was set to 50% based on the discharge capacity after the charge/discharge was performed once. At this time, the nominal voltage was measured, and the DC internal resistance was measured through the voltage drop that appears when a discharge pulse was given for 10 seconds at 5A (2.5C).

The average/lowest/highest values of the average weight, average nominal voltage, and DC internal resistance of the batteries measured in 50 samples are shown in Table 1 below.

Example 1 Reference example 1 Reference example 2 Comparative Example 1 Comparative Example 2 average nominal voltage
(V) 3.53 3.51 3.53 3.52 3.52 average cell weight
(g) 67.16 67.20 67.11 67.23 67.25 DC-IR
(mOhms) average 12.38 12.37 12.33 13.74 13.35 lowest 11.92 11.99 11.96 13.02 12.85 best 12.86 12.88 12.94 14.82 14.22

Through the battery weight measurement results in Table 1, it can be confirmed that the same amount of electrolyte is included in the batteries of Example 1, Reference Examples 1 and 2, and Comparative Examples 1 and 2, and the nominal voltage is also at the same level.

That is, despite the fact that there is no difference in the weight and voltage of the battery, the battery of Example 1 attached with the insulating member according to an exemplary embodiment of the present invention has a lower DC internal resistance than the batteries of Comparative Examples 1 and 2. You can check. In addition, despite the use of an insulating member, the battery of Example 1 exhibits resistance characteristics equivalent to those of the batteries of Reference Examples 1 and 2 in which the jelly roll shape was fixed by attaching a metal foil on the outermost metal current collector again. You can check. That is, compared to the metal foil, it is easy to slit a required area and it is possible to implement an equivalent level of resistance characteristics while using an insulating member without fear of performance degradation due to residual metal powder.

<Experimental Example 2: Evaluation of alternating current internal resistance (AC-IR)>

200 battery samples were prepared by the method described in Example 1 and Comparative Examples 1 and 2, respectively, formed at a current of 200 mA (0.1 C rate), and after adjusting to SOC 30%, which is the shipping charge state, Hioki AC internal resistance was measured using an ohmmeter RM3534.

The distribution of alternating current internal resistance values of the battery measured in 200 samples is shown in FIG. 6, and the average/lowest/highest values are listed in Table 2 below.

Example 1 Comparative Example 1 Comparative Example 2 AC-IR
(mOhms) average 13.0 15.8 16.3 lowest 11.0 13.0 13.4 best 14.6 17.0 17.2

Through the results of Table 2 and FIG. 6, it can be confirmed that the battery of Example 1 attached with the insulating member according to an exemplary embodiment of the present invention has lower AC internal resistance than the batteries of Comparative Examples 1 and 2. In particular, even if the polyimide tape is spirally attached, when the width exceeds 2 mm as in Comparative Example 2, it can be confirmed that the resistance is further increased compared to the conventional method in which the tape is attached only to the upper and lower ends.

10: negative electrode current collector
20: negative electrode active material layer
30: cathode
40: separator
50: anode
90: part of the electrode assembly except for the outermost metal current collector and swelling tape
100: electrode assembly
101: swelling tape
102: outermost metal current collector
103: insulation member
103': copper foil

Claims (10)

In a cylindrical secondary battery in which a separator is interposed between a sheet-shaped positive electrode and a negative electrode and a rolled-up jelly roll-shaped electrode assembly is housed in a battery case,
The electrode assembly includes a metal current collector at the outermost part,
A cylindrical secondary battery, wherein an insulating member having a width of 0.1 mm to 2 mm is spirally provided on a partial region of an outer circumferential surface of the metal current collector to fix the jelly roll shape.
The method of claim 1,
The insulating member is a cylindrical secondary battery that is a polyimide film.
The method of claim 1,
The cylindrical secondary battery, wherein the area of the insulating portion formed by the insulating member is 5% to 20% of the total area of the outer circumferential surface of the metal current collector.
The method of claim 1,
The insulating member is a cylindrical secondary battery having a width of 0.5mm to 1.8mm.
The method of claim 1,
The insulating member is a cylindrical secondary battery having a width of 1.0 mm to 1.5 mm.
The method of claim 1,
The insulating member is a cylindrical secondary battery that is wound 3 to 15 times on the outer circumferential surface of the metal current collector.
The method of claim 1,
The electrode assembly further comprises a swelling tape whose volume expands when the electrolyte is injected.
The method of claim 7,
The swelling tape is a cylindrical secondary battery attached to the inner circumferential surface of the metal current collector.
The method of claim 7,
A cylindrical secondary battery having a thickness of the swelling tape of 30 μm to 60 μm.
The method of claim 1,
The metal current collector is made of a metal foil and is in contact with a partial region of the inner circumferential surface of the battery case.

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