KR20240019601A - Secondary battery and manufacturing method of same - Google Patents

Abstract

This specification relates to secondary batteries and methods for manufacturing secondary batteries.

Description

Secondary battery and manufacturing method thereof {SECONDARY BATTERY AND MANUFACTURING METHOD OF SAME}

The present invention relates to secondary batteries and methods for manufacturing the same.

In recent years, as the demand for portable electronic products such as laptops, video cameras, and portable phones has rapidly increased, and as the development of electric vehicles, energy storage batteries, robots, and satellites has begun in earnest, secondary batteries used as driving power sources have A lot of research is being done on this.

Such secondary batteries include, for example, nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries are widely used in the field of advanced electronic devices due to their advantages of free charging and discharging, very low self-discharge rate, high operating voltage, and high energy density per unit weight as the memory effect rarely occurs compared to nickel-based secondary batteries. there is.

Generally, a lithium secondary battery is built into a case of a metal can or laminate sheet in a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode is stacked or wound, and an electrolyte solution is injected or It is constructed by impregnation.

The electrode assembly of the anode/separator/cathode structure that constitutes the secondary battery is largely divided into jelly-roll type (wound type) and stack type (laminated type) depending on its structure. The jelly-roll type is a structure in which a long sheet coated with an active material is wound with a separator between the anode and the cathode, while the stack type is a structure in which a number of anodes and cathodes of a certain size are sequentially stacked with a separator interposed between them. Among them, the jelly-roll type electrode assembly has the advantages of being easy to manufacture, having a high energy density per weight, and being structurally stable.

In order to check the performance of the battery cell developed and manufactured in this way, the electrode potential of the battery cell is measured.

To measure electrode potential, a three-electrode system electrode potential measurement method consisting of a reference electrode, a working electrode, and a counter electrode is mainly used.

The reference electrode is an electrode used to create a battery circuit for measuring electrode potential to measure the potential of the electrodes that make up the battery or the electrode where electrolysis is occurring. It serves as a reference for the potential when measuring the relative value of the electrode potential.

In the case of conventional electrode potential measurement methods, even for the same cylindrical secondary battery, data values may vary depending on the measurement procedure or method of the measurer.

In addition, during the process of manufacturing a battery, the actual potential may vary depending on the position of the electrode or the jelly roll. However, in the conventional electrode potential measurement method, the reference electrode is placed irregularly at only one location in the area of the jelly roll to determine the potential. Therefore, it is difficult to determine the degree of deterioration of the electrode due to the difference in movement of electrons and currents between the anode and cathode, and it is difficult to clearly distinguish the cause of deterioration. Additionally, it is difficult to determine the influence of the number of negative electrode tabs in the battery.

As above, the conventional method for measuring electrode potential has many problems, so there is a very high need for technology that can solve these problems.

Korean Patent Publication No. 10-2010-0075913

In this specification, a secondary battery including at least three reference electrodes and at least one temperature measuring device and a method for manufacturing the same are provided.

One embodiment of the present invention includes an electrode assembly in the form of a jelly roll; a battery case storing the electrode assembly and electrolyte; A cap assembly coupled to the top of the battery case; and at least three reference electrodes and at least one temperature measuring device, wherein one end of the reference electrode and the temperature measuring device is immersed in the electrolyte solution, and the other end is exposed to the outside through a gap between the battery case and the cap assembly. Provides a secondary battery.

One embodiment of the present invention includes the steps of attaching at least three reference electrodes to a jelly roll-shaped electrode assembly and providing a reference electrode and a temperature measuring device by placing at least one temperature measuring device on the electrode assembly; A storage step of storing the electrode assembly in a battery case; A coupling step of coupling the cap assembly to the top of the battery case; and a crimping step of crimping and combining the battery case and the cap assembly with the reference electrode and the temperature measuring device interposed therebetween.

The secondary battery according to the present invention includes at least three reference electrodes and at least one temperature measuring device, so that the location, extent, and cause of deterioration can be determined according to the difference in movement of electrons and currents of the positive and negative electrodes according to the electrode design. There is an effect. In addition, it is possible to measure the degree of cycle performance decline due to degradation, and the resulting temperature change has the effect of identifying risks due to temperature rise, making it possible to predict and prevent the overall performance and safety of secondary batteries. there is.

Additionally, by using an actual secondary battery without introducing a separate tray, it is possible to obtain an electrode potential value that excludes resistance caused by additional conductors or excessive electrolyte.

In addition, the reference electrode and temperature measuring device are configured to pass between the battery case and the cap assembly rather than being exposed to the outside through a separate hole, thereby maintaining sealing without damaging the structure of the secondary battery. It is possible to measure the deterioration of a single electrode. In addition, there is the advantage of being able to conduct high-temperature evaluations where high internal pressure occurs.

1 is a cross-sectional perspective view of a secondary battery according to an exemplary embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of portion “A” of FIG. 1.
Figure 3 is an enlarged cross-sectional view of portion “B” in Figure 1.
Figures 4 and 5 are perspective views showing the reference electrode, insulating tape, and separation member included in the secondary battery of Figure 1.
Figure 6 is a diagram showing the lower part of the electrode assembly equipped with the metal plate and electrode tab included in the reference electrode.
FIG. 7 is a perspective view showing the reference electrode, insulating tape, and separation member of FIG. 5 attached to the lower part of the electrode assembly.
8 to 11 are diagrams for explaining the process of manufacturing a secondary battery according to an embodiment of the present invention.
Figure 12 shows a charging profile of a secondary battery according to an exemplary embodiment of the present invention.
Figure 13 shows a discharge profile of a secondary battery according to an exemplary embodiment of the present invention.

Hereinafter, with reference to the attached drawings, various embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. The invention may be implemented in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts that are not relevant to the description are omitted, and identical or similar components are assigned the same reference numerals throughout the specification.

In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, so the present invention is not necessarily limited to what is shown. In the drawing, the thickness is enlarged to clearly express various layers and areas. And in the drawings, for convenience of explanation, the thicknesses of some layers and regions are exaggerated.

In this specification, when a part “includes” a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

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

In this specification, when a part is connected to another part, this includes not only the case where it is directly connected, but also the case where it is indirectly connected with another element in between.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. However, the embodiments of the present invention may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below. However, when explaining in detail the operating principle of the preferred embodiment of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, the same reference numerals are used for parts that perform similar functions and actions throughout the drawings.

One embodiment of the present invention includes an electrode assembly in the form of a jelly roll; a battery case storing the electrode assembly and electrolyte; A cap assembly coupled to the top of the battery case; and at least three reference electrodes and at least one temperature measuring device, wherein one end of the reference electrode and the temperature measuring device is immersed in the electrolyte solution, and the other end is exposed to the outside through a gap between the battery case and the cap assembly. Provides a secondary battery.

Generally, in the conventional electrode potential measurement method, the potential of the anode and cathode can be determined by using Li metal as a reference electrode. During the process of manufacturing a battery, the actual potential may vary depending on the position of the electrode or the jelly roll, but in the case of the existing measurement method, the potential is determined by placing the reference electrode irregularly in only one place in the area of the jelly roll. There is a problem in that it is difficult to determine the degree of electrode deterioration due to the difference in movement of electrons and currents between the anode and cathode, and it is difficult to clearly distinguish the cause of deterioration. Additionally, it is difficult to determine the influence of the number of negative electrode tabs in the battery.

On the other hand, in the case of the present invention, at least three reference electrodes and at least one temperature measuring device are introduced into the secondary battery, and the positions of the reference electrodes are subdivided and positioned to determine the potential of the positive and negative electrodes according to electron movement for each electrode position. Therefore, it is possible to determine the extent of deterioration and the cause of deterioration depending on the electrode design, and the influence of the number and material of the cathode tabs can be determined. Additionally, heat generation associated with deterioration through dislocation can be measured through a temperature measuring device, allowing the risk of long-term cycling to be reviewed. In addition, since the battery according to the present invention is manufactured from an actual cylindrical battery, it can similarly simulate the actual operating environment.

Referring to FIGS. 1 to 3, the secondary battery 100 according to an embodiment of the present invention includes a jelly roll-shaped electrode assembly 120, a battery case 130 for storing the electrode assembly 120 and an electrolyte, It includes a cap assembly 140 coupled to the top of the battery case 130, at least three reference electrodes (200, 200A, 200B, 200C), and at least one temperature measuring device (500, 500A, 500B). One end (210, 510) of these reference electrodes (200, 200A, 200B, 200C) and temperature measuring devices (500, 500A, 500B) is immersed in an electrolyte solution, and the other ends (220, 520) are connected to the battery case (130) and the cap. It is exposed to the outside through the assembly 140. In Figure 1, three reference electrodes and two temperature measuring devices are shown, and additional temperature measuring devices may be introduced.

The electrode assembly 120 has a jelly roll-shaped structure in which a plurality of anodes 121 and cathodes 122 are wound with a separator 123 interposed between them, and a center pin 150 can be inserted into the center thereof. A top insulator (160) may be located on the top of the electrode assembly 120, and a bottom insulator (160) may be located between the bottom (124) of the electrode assembly (120) and the bottom (131) of the battery case (130). (170, Bottom insulator) may be located.

The electrolyte may be a non-aqueous electrolyte containing a lithium salt, and the non-aqueous electrolyte containing a lithium salt is composed of a non-aqueous electrolyte and a lithium salt. Non-aqueous electrolytes include, but are not limited to, non-aqueous organic solvents, organic solid electrolytes, and inorganic solid electrolytes. This electrolyte is stored in the battery case 130 together with the electrode assembly 120, and specific indications are omitted in the drawing.

The battery case 130 may include a beading portion 132 and a crimping portion 133.

The beading portion 132 refers to a portion of the battery case 130 that is indented toward the center of the electrode assembly 120, and is used to ensure stable coupling of the cap assembly 140 and prevent the electrode assembly 120 from flowing. It is for.

The crimping part 133 is located on the upper part of the beading part 132 and refers to a part surrounding the cap assembly 140, and is for stable coupling of the cap assembly 140. That is, the battery case 130 is coupled to the cap assembly 140 by crimping to form the crimping portion 133.

The cap assembly 140 may include a top cap 141 forming a positive terminal, and a cap plate 142 to which the positive electrode tab 144 extending upward from the electrode assembly 120 is connected. The anode tab 144 may extend from the anode 121 of the electrode assembly 120.

Meanwhile, the secondary battery 100 according to this embodiment may include a gasket 143 located between the battery case 130 and the cap assembly 140. Specifically, it may be located between the crimping portion 133 of the battery case 130 and the cap plate 142 of the cap assembly 140.

The gasket 143 is mounted on the upper inner surface of the beading portion 132 and the crimping portion 133 to maintain airtightness, thereby increasing the sealing force between the cap assembly 140 and the battery case 130.

At this time, the reference electrode 200 and the temperature measuring device 500 may be located between the battery case 130 and the gasket 143. Additionally, the battery case 130 and the cap assembly 140 may be coupled by crimping with the gasket 143, the reference electrode 200, and the temperature measuring device 500 interposed therebetween. Therefore, the reference electrode 200 and the temperature measuring device 500 can be provided in the secondary battery 100 in an actual operating state, and the reference electrode 200 and the temperature measuring device 500 are connected to the battery case 130 and the temperature measuring device 500. It can be stably fixed between the gaskets 143.

Unlike the conventional electrode potential measurement method, the secondary battery according to an embodiment of the present invention includes at least three reference electrodes and at least one temperature measuring device, so that the positions of the reference electrodes are subdivided and the anode/electrode is measured for each position. By measuring the potential of the cathode and measuring the temperature of degradation, the cause of degradation can be clearly identified depending on the electrode design.

On the other hand, the secondary battery 100 according to this embodiment does not provide a separate hole to expose the reference electrode 200, but rather uses the crimping portion 133 and the cap assembly 140 of the battery case 130. Since the reference electrode 200 and the temperature measuring device 500 are positioned between the cap plate 142, electrode potential can be measured while maintaining sealing without damaging the structure of the secondary battery 100. .

If a separate hole is provided, a separate sealant must be inserted to seal between the reference electrode and the hole. In this case, there is a disadvantage that additional space is required inside the secondary battery for insertion of the sealant, and there is also a problem that the seal is easily broken due to deformation of the sealant.

In contrast, the reference electrode 200 and the temperature measuring device 500 of the secondary battery 100 according to this embodiment are provided between the crimping portion 133 and the gasket 143, so there is no need to form a separate hole, and the clipping connection is used to It can be strongly fixed and sealed. In other words, even if the reference electrode 200 and the temperature measuring device 500 are provided, problems such as unsealing or structural deformation of the secondary battery 100 do not occur. Accordingly, the secondary battery 100 according to this embodiment has the advantage of being able to conduct high-temperature evaluation where a large internal pressure occurs.

The battery case 130 may be a cylindrical case or a square case, but as shown in FIG. 1, it is preferably a cylindrical case.

Meanwhile, the reference electrode 200 extends from the lower part 124 of the electrode assembly 120 along the outer peripheral surface 125 of the electrode assembly 120 (see FIG. 7) and extends between the battery case 130 and the cap assembly 140. It can pass through, and one end 210 of the reference electrode 200 can be located in the lower part 124 of the electrode assembly 120, as shown in FIG. 2. In other words, one end 210 of the reference electrode 200 may be positioned between the lower part 124 and the lower insulating member 170 of the electrode assembly 120 while being immersed in an electrolyte solution.

Additionally, the reference electrode 200 may include a metal plate 250 attached to one end 210 of each reference electrode 200. The metal plate 250 will be described later.

By extending one end 210 of each reference electrode 200 to the lower part 124 of the electrode assembly 120, the reference electrode 200 can be stably immersed in the electrolyte solution and more accurate and consistent measurement of electrode potential is possible. This is possible.

In addition, if one end 210 of each reference electrode 200 is located on the outer peripheral surface 125 of the electrode assembly 120, it may interfere with the electrode assembly 120 being stored in the battery case 130, but in this embodiment In the example, one end 210 of the reference electrode 200 extends to the lower part 124 of the electrode assembly 120, so this problem does not occur.

In addition, since one end 210 of each reference electrode 200 is located in the lower part 124 of the electrode assembly 120, the one end 210 of the reference electrode 200 is positioned by the weight of the electrode assembly 120. There is an advantage that the deviation of the gap between the metal plate 250 and the positive and negative electrodes 121 and 122 of the electrode assembly 120 is reduced.

At this time, the secondary battery 100 according to an embodiment of the present invention may further include a separation member 400 located between the electrode assembly 120 and one end 210 of the reference electrode 200, This separation member 400 may be in the form of a thin film. Furthermore, the separation member 400 may be positioned between the electrode assembly 120 and the metal plate 250 attached to one end 210 of the reference electrode 200.

Although not specifically shown, the jelly roll-shaped electrode assembly 120 in which the anode 121, the cathode 122, and the separator 123 are wound can have its outer peripheral surface 125 (see FIG. 7) wrapped with an outer peripheral sheet. . Therefore, it is possible to prevent a problem in which a short circuit occurs when the reference electrode 200 connected along the outer peripheral surface 125 of the electrode assembly 120 contacts the outer peripheral surface 125 of the electrode assembly 120.

Figures 4 and 5 are perspective views showing the reference electrode 200, the insulating tape 300, and the separation member 400 included in the secondary battery 100.

Referring to FIGS. 4 and 5 together with FIGS. 1 to 3, the secondary battery 100 according to an exemplary embodiment of the present specification includes an insulating tape 300 located between the reference electrode 200 and the battery case 130. ) may further be included. This insulating tape 300 is an electrically insulating tape and may include at least one of polyimide (PI), polyethylene terephthalate (PET), and polypropylene (PP).

Specifically, the insulating tape 300 may extend together along the direction in which the reference electrode 200 is connected to cover the reference electrode 200, except for the other end 220 of the reference electrode 200 exposed to the outside. . Therefore, the insulating tape 300 prevents the reference electrode 200 from contacting the battery case 130, including the bottom portion 131, the beading portion 132, and the crimping portion 133, thereby ) Prevents the risk of short circuit that may result from Additionally, as will be described later, by wrapping the metal wire 230 of the reference electrode 200 with the insulating tape 300, breakage of the metal wire 230 can be prevented.

To effectively prevent short circuit, as shown in FIGS. 4 and 5, it is preferable that the insulating tape 300 covers all parts of the reference electrode 200 except the other end 220 of the reference electrode 200. In particular, the insulating tape 300 may extend to cover one end 210 of the reference electrode 200.

Additionally, a separation member 400 may be provided on the metal plate 250 of the reference electrode 200. By positioning the separation member 400 between the electrode assembly 120 and one end 210 of the reference electrode 200, short circuit between the lower part 124 of the electrode assembly 120 and the reference electrode 200 can be prevented. there is. In order to effectively prevent a short circuit, the separation member 400 may completely cover the metal plate 250 and, for example, may be attached in a rectangular or square shape while covering the metal plate 250. Alternatively, the separation member 400 may cover both the reference electrode 200 and the metal plate 250 attached to one end 210 of the reference electrode 200.

The separation member 400 may include a porous non-woven material or a material applied to the separator 123, and there is no particular limitation on the material applied to the separator 123, such as polypropylene, glass fiber, or polyethylene. materials may be used.

The reference electrode 200 may include a metal wire 230 and a coating layer 240 surrounding the metal wire 230.

In another embodiment, referring to FIG. 5, in the insulating tape 300 covering the reference electrode 200, any part of the insulating tape 300 where the reference electrode 200 is located is used as the reference electrode. It may be partially cut in a direction perpendicular to (200) and folded to surround the reference electrode (200). Specifically, an arbitrary portion of the insulating tape 300 where the metal wire 230 of the reference electrode 200 and the coating layer 240 surrounding the metal wire are located is formed into a metal wire 230 and a coating layer 240 surrounding the metal wire. It may be partially cut in a direction perpendicular to the metal wire 230 and folded to surround the coating layer 240 surrounding the metal wire.

In one example, the area where the insulating tape 300 is folded to surround the reference electrode 200 may be located on the outer peripheral surface 125 of the electrode assembly.

In one example, the area where the insulating tape 300 is not folded and covers the reference electrode 200 may be located in the lower portion 124 of the electrode assembly.

In one example, the metal plate 250 may be positioned within 10 mm from the end of the insulating tape 300, and the distance from the position where the insulating tape 300 is cut to the end of the insulating tape 300 is ) It may be 20% or more of the total length, specifically 25% or more or 30% or more, and may be 50% or less or 40% or less, but is not limited to this and can be appropriately changed depending on the size of the battery. By covering the reference electrode 200 with the insulating tape 300 as described above, the metal wire 230 of the reference electrode 200 can be prevented from breaking and short circuiting can be prevented.

Meanwhile, since the reference electrode 200 can be attached to the outer peripheral surface 125 of the electrode assembly 120 and/or the lower part 124 of the electrode assembly using the insulating tape 300, the insulating tape 300 prevents short circuit. In addition to the effect, it can play a role in fixing the reference electrode 200 within the secondary battery 100. In addition, since the insulating tape 300 can cover up to one end 210 of the reference electrode 200, the metal plate 250 and the separation member 400, including one end 210 of the reference electrode 200, are connected to the electrode assembly 120. ) can be attached and fixed to the lower part 124.

In addition, since the reference electrode 200 can be assembled together while attached to the electrode assembly 120, the secondary battery 100 equipped with the reference electrode 200 can be easily manufactured without any additional processes.

Meanwhile, the reference electrode 200 may include a metal wire 230 and a coating layer 240 surrounding the metal wire 230. There is no limitation on the material of the metal wire 230 as long as it contains an electrically conductive metal, and may include copper (Cu). The coating layer 240 may include an enamel layer. This coating layer 240 can prevent the metal wire 230 from contacting other parts of the secondary battery 100 and causing an unintentional short circuit.

As described above, the secondary battery 100 according to an embodiment of the present invention is provided with an insulating tape 300 and a coating layer 240 to prevent unintentional short circuits within the secondary battery. Depending on each embodiment, only one of the insulating tape 300 or the coating layer 240 may be provided, but it is preferable to provide both the insulating tape 300 and the coating layer 240.

Meanwhile, as shown in FIGS. 4 and 5, the other end 220 of the reference electrode 200 may peel off a portion of the coating layer 240 to expose the metal wire 230.

Likewise, at one end 210 of the reference electrode 200, a portion of the coating layer 240 can be peeled off to expose the metal wire 230, and the metal plate 250 is attached to the exposed metal wire 230 as described above. can be attached. The separation member 400 can then be placed on the metal plate 250.

The metal plate 250 functions as a reference electrode terminal, and the metal wire 230 exposed at the other end 220 of the reference electrode 200 is connected to an external wire to measure the electrode potential of the three-electrode system. Although not specifically shown, when the electrode potential of the three-electrode system is not measured, the exposed metal wire 230 can be stored wrapped with another insulating tape. This metal plate 250 may contain at least one of lithium (Li), lithium titanate (LTO), lithium iron phosphate (LFP), platinum (Pt), and palladium (Pd).

As described above, the insulating tape 300 can attach and fix the metal plate 250 and the separation member 400 to the lower part 124 of the electrode assembly 120. Furthermore, as shown in FIGS. 4 and 5, the reference electrode 200, the metal plate 250, and the separation member 400 can be positioned on the insulating tape 300, so that the reference electrode 200, the metal plate 250, and the Connection and fixation between the separation members 400 can be achieved by the insulating tape 300.

Meanwhile, referring again to FIG. 1, the top and bottom insulating members 160 and 170 may include insulating fibers, and these insulating fibers may be entangled without direction to form a non-woven fabric-like shape. The insulating fiber may include at least one of polyethylene, polybutylene, polystyrene, polyethylene terephthalate, polypropylene, glass fiber, natural rubber, and synthetic rubber.

The center pin 150 generally contains a metal material to provide a certain strength and has a cylindrical structure in which a plate material is bent round. This center pin 150 fixes and supports the electrode assembly 120 and may function as a passage for discharging gas generated by internal reactions during charging, discharging, and operation.

Hereinafter, with reference to FIGS. 6 and 7, the positions of reference electrodes in a secondary battery according to an exemplary embodiment of the present invention will be described. Figure 6 shows the lower part 124 of the electrode assembly 120, showing an example of the positions of the first metal plate 250A, the second metal plate 250B, and the third metal plate 250C and the electrode tab, Insulating tapes and metal wires are omitted.

FIG. 7 is a perspective view showing the reference electrode 200 and the insulating tape 300 attached to the electrode assembly 120. In FIG. 7, the temperature measuring device 500 and the electrode tab are omitted. The position/direction of the reference electrode and the insulating tape can be appropriately adjusted depending on the temperature measuring device and the position of the electrode tab.

A secondary battery according to an exemplary embodiment of the present invention includes at least three reference electrodes (200A, 200B, 200C). The reference electrodes may be positioned so as not to overlap each other. The reference electrodes may be attached to the lower part 124 of the electrode assembly 120.

In one example, a secondary battery according to an exemplary embodiment of the present invention may include three reference electrodes, that is, a first reference electrode (200A), a second reference electrode (200B), and a third reference electrode (200C). .

In general, the potentials of the anode and cathode are measured differently depending on the location of the reference electrode at the bottom of the jelly roll-shaped electrode assembly. The current moves through the electrode tab, and depending on the positions of the anode and cathode, there are areas where current is concentrated and areas where current is low. This can be seen as a kinetic effect between current and ions.

By providing at least three reference electrodes as shown below, the potential of areas with different current densities can be measured in detail at each location, and from this, the area and cause of battery deterioration can be analyzed.

The first reference electrode 200A may include a first metal plate 250A attached to one end 210, and the second reference electrode 200B may include a second metal plate 250B attached to one end 210. It may include, and the third reference electrode (200C) may include a third metal plate (250C) attached to one end (210).

Hereinafter, the position of the metal plate 250 included in the reference electrode 200 will be described with reference to FIG. 6.

The first metal plate 250A, the second metal plate 250B, and the third metal plate 250C are formed on a straight line (dashed one-dot line in FIG. 6) including the center of the winding with respect to the lower portion 124 of the electrode assembly 120. It can be located in . As described above, the fact that the metal plate is located on a straight line includes the case where a partial area of the metal plate is located on the straight line. In other words, it does not mean that the perfect center is located on a straight line, and a certain degree of error range can be considered.

The first metal plate 250A may be located in an area between the end 601 of the inner peripheral surface of the electrode assembly and the end 602 of the outer peripheral surface closest to the end of the inner peripheral surface.

The second metal plate 250B and the third metal plate 250C may be located in a direction opposite to the direction in which the first metal plate 250A is located relative to the winding center on a straight line including the winding center. Specifically, the second metal plate 250B and the third metal plate 250C have an inner peripheral surface end 601 and an outer peripheral surface end 602 in a direction opposite to the direction in which the first metal plate 250A is located on a straight line including the winding center. ) can be located in the area between.

The second metal plate 250B may be located closer to the end 601 of the inner peripheral surface of the lower electrode assembly 124 than the third metal plate 250C.

The shortest distance between the first metal plate 250A and the end 601 of the inner peripheral surface may be shorter than the shortest distance between the second metal plate 250B and the end 601 of the inner peripheral surface.

The electrode assembly 120 includes an anode tab 144, and the anode tab 144 has an end 601 of the inner peripheral surface in a direction opposite to the direction in which the first metal plate 250A is located on a straight line including the center of the winding. It may be located in the upper direction of the area between and the outer peripheral surface end 602.

Specifically, the anode tab 144 may be positioned toward the top of the area between the first metal plate 250A and the second metal plate 250B. That is, when the portion where the anode tab 144 is located is extended downward, the corresponding lower portion and the first metal plate 250A and the second metal plate 250B may be located on a straight line.

The electrode assembly 120 includes at least one cathode tab 145. The first metal plate 250A, the second metal plate 250B, the third metal plate 250C, and the cathode tab 145 form a straight line including the center of the winding with respect to the lower portion 124 of the electrode assembly 120. It can be located in .

When one negative electrode tab 145 is included, the one negative electrode tab 145 may be located closer to the outer peripheral surface end 602 than the third metal plate 250C.

When two cathode tabs 145 are included, as shown in FIG. 6, one cathode tab 145 may be located closer to the outer circumferential end 602 than the third metal plate 250C, and the remaining cathode tab 145 The tab 145 may be located in the same direction as the first metal plate 250A, and may be located closer to the end 601 of the inner peripheral surface than the first metal plate 250A.

The gap between the first metal plate 250A, the second metal plate 250B, and the third metal plate 250C may be 10% to 30% or 15% to 25%, respectively, based on the radius of the electrode assembly.

The spacing between the first metal plate 250A, the second metal plate 250B, and the third metal plate 250C may be the same.

Specifically, the jelly roll-shaped electrode assembly includes one cathode tab located on the outer portion of the electrode assembly or two cathode tabs located on the core portion and the outer portion, and a middle portion. ) may include one anode tab located at The degree of current density between the cathode tab and the anode tab varies, and the closer the area to the cathode tab and the anode tab, the higher the current density, which can actively cause charge/discharge depth and affect deterioration.

Therefore, when the reference electrode is provided as above to measure the current density of the negative electrode tab and the positive electrode tab, it is possible to easily identify parts that are vulnerable to deterioration and parts that are not vulnerable to deterioration in the secondary battery structural design. You can. On the other hand, if the reference electrode is not placed in the above-mentioned area, there is a problem in that it is difficult to determine the location and degree of deterioration according to the current density measurement.

A secondary battery according to an exemplary embodiment of the present invention includes at least one temperature measuring device 500. When there are a plurality of temperature measuring devices 500, they may be positioned so as not to overlap each other.

A secondary battery according to an exemplary embodiment of the present invention includes at least two temperature measuring devices 500.

In one embodiment of the present invention, one end of the temperature measuring device 500 is immersed in the electrolyte solution, and the other end is exposed to the outside through a gap between the battery case and the cap assembly. Specifically, the other end of the temperature measuring device 500 may pass between the crimping portion 133 and the gasket 143 and extend outward.

The temperature measuring device 500 includes a temperature sensor connected to a secondary battery, and the temperature sensor may be located at one end 510 of the temperature measuring device 500.

The temperature sensor may be provided to contact the surface of the jelly roll-shaped electrode assembly 120. The temperature sensor is mounted on one end of the temperature measuring device 500 and can sense the temperature of the secondary battery by contacting the surface of the secondary battery. The temperature sensor can be formed as a thermocouple in the form of a wire. Information sensed through the temperature sensor is transmitted to the sensing unit (not shown) through a wire, and the sensing unit can obtain temperature information of the secondary battery.

In one example, a secondary battery according to an exemplary embodiment of the present invention may include two temperature measurement devices, that is, first temperature measurement devices 500 and 500A and second temperature measurement devices 500 and 500B.

The first temperature measuring device 500A may be located on the outer peripheral surface 125 of the electrode assembly.

Specifically, one end of the first temperature measuring device 500A is provided on the outer peripheral surface 125 of the jelly roll-shaped electrode assembly 120. The first temperature measuring device 500A extends upward along the outer peripheral surface of the electrode assembly, passes between the crimping portion 133 and the gasket 143, and the other end may extend outward. The first temperature measuring device 500A located on the outer peripheral surface may be additionally fixed with an insulating tape.

The second temperature measuring device 500B may be located at the center of the electrode assembly 120. The second temperature measuring device 500B may be located on the inner peripheral surface of the electrode assembly 120, and specifically, may be located between the center pin 150 and the inner peripheral surface of the electrode assembly 120.

Specifically, when assembling a secondary battery, one end of the second temperature measuring device 500B is provided at the center of the jelly roll-shaped electrode assembly 120. The second temperature measuring device 500B extends upward along the center of the electrode assembly, passes between the crimping portion 133 and the gasket 143, and the other end may extend outward.

In another embodiment, the second temperature measuring device 500B extends along the lower and outer peripheral surfaces along the center of the electrode assembly, passes between the crimping portion 133 and the gasket 143, and has the other end to the outside. It may be extended. That is, the second temperature measuring device 500B may extend downward from the center of the electrode assembly, then extend along the lower portion to the outer circumferential surface, and then extend upward along the outer peripheral surface, and the other end may extend outward. The second temperature measuring device 500B located on the outer peripheral surface may be additionally fixed with an insulating tape.

The first temperature measuring device 500A and the second temperature measuring device 500B provided as described above are located and fixed between the battery case 130 and the gasket 143, so there is little space to move inside the secondary battery and a large Since there is no movement, temperature can be measured stably.

Through the temperature measuring device, the temperature according to the location of the battery can be determined in detail and the location of heat generation can be determined.

As mentioned above, even if a plurality of reference electrodes are used, it is difficult to determine the risk due to temperature rise due to deterioration by measuring the potential using only the reference electrode.

On the other hand, by measuring the detailed potential and temperature according to the position of the battery as in the present invention, it is possible to measure the degree of cycle performance degradation due to deterioration, and the resulting temperature change has the effect of identifying risks due to temperature rise. there is. In addition, if there is a side reaction in the battery, the rise in temperature during charging/discharging can be analyzed, and the possibility of separator damage and internal short circuit in the relevant area can be inferred. In the long term, heat generation continues up to the point of self-heating. If a trend is observed, it has the effect of predicting even battery ignition.

Therefore, the secondary battery of the present invention can predict and prevent the overall performance and safety of the secondary battery by understanding the potential and temperature changes of the electrodes.

In addition, the secondary battery of the present invention can also determine the influence of the number and material of the negative electrode tabs.

Hereinafter, a method for manufacturing a secondary battery according to an embodiment of the present invention will be described with reference to FIGS. 7 to 11. However, descriptions of parts that overlap with what was explained previously will be omitted.

7 to 11 are diagrams for explaining a method of manufacturing a secondary battery according to an embodiment of the present invention. In the following steps, only one reference electrode among the plurality of reference electrodes is shown.

Referring to FIGS. 7 to 11, the method of manufacturing a secondary battery according to an embodiment of the present invention attaches at least three reference electrodes 200 to a jelly roll-shaped electrode assembly 120, and the electrode assembly A step (S1) of providing a reference electrode and a temperature measuring device for positioning at least one temperature measuring device 500 on (120); A storage step (S2) of storing the electrode assembly 120 in the battery case 130; A coupling step (S3) of coupling the cap assembly 140 to the top of the battery case 130; and a crimping step (S4) of crimping and combining the battery case 130 and the cap assembly 140 with the reference electrode 200 and the temperature measuring device 500 interposed therebetween.

First, the step (S1) of providing the reference electrode and the temperature measuring device will be described with reference to FIG. 7. In the step of providing the reference electrode and the temperature measuring device, the reference electrode 250 can be attached to the electrode assembly 120 using an electrically insulating insulating tape 300. Specifically, it may be attached to the lower portion 124 and the outer peripheral surface 125 of the electrode assembly 120. As described above, a separation member may be positioned between the lower part 124 of the electrode assembly 120 and one end 210 of the reference electrode 200. At this time, the reference electrode can be arranged so that the first metal plate 250A, the second metal plate 250B, and the third metal plate 250C are located on a straight line including the center of the winding when viewed from the bottom of the electrode assembly as shown in FIG. 7. there is.

The wires of the plurality of reference electrodes 200 may be positioned in different directions so as not to overlap each other to prevent leakage during battery assembly.

In addition, although not shown in the drawing, in the step of providing the reference electrode and the temperature measuring device, the temperature measuring device 500 may be provided to contact the surface of the jelly roll-shaped electrode assembly 120. The temperature measuring device 500 may pass between the crimping portion 133 and the gasket 143 and extend outward.

In one example, a secondary battery according to an exemplary embodiment of the present invention may include two temperature measurement devices, that is, first temperature measurement devices 500 and 500A and second temperature measurement devices 500 and 500B.

The first temperature measuring device 500A may be located on the outer peripheral surface 125 of the electrode assembly.

Specifically, one end of the first temperature measuring device 500A is provided on the outer peripheral surface 125 of the jelly roll-shaped electrode assembly 120. The first temperature measuring device 500A extends upward along the outer peripheral surface of the electrode assembly, passes between the crimping portion 133 and the gasket 143, and the other end may extend outward. The first temperature measuring device 500A located on the outer peripheral surface may be additionally fixed with an insulating tape.

The second temperature measuring device 500B may be located at the center of the electrode assembly 120. The second temperature measuring device 500B may be located on the inner peripheral surface of the electrode assembly 120, and specifically, may be located between the center pin 150 and the inner peripheral surface of the electrode assembly 120.

Specifically, when assembling a secondary battery, one end of the second temperature measuring device 500B is provided at the center of the jelly roll-shaped electrode assembly 120. The second temperature measuring device 500B extends upward along the center of the electrode assembly, passes between the crimping portion 133 and the gasket 143, and the other end may extend outward.

In another embodiment, the second temperature measuring device 500B extends along the lower and outer peripheral surfaces along the center of the electrode assembly, passes between the crimping portion 133 and the gasket 143, and has the other end to the outside. It may be extended. That is, the second temperature measuring device 500B may extend downward from the center of the electrode assembly, then extend along the lower portion to the outer circumferential surface, and then extend upward along the outer peripheral surface, and the other end may extend outward. The second temperature measuring device 500B located on the outer peripheral surface may be additionally fixed with an insulating tape.

The first temperature measuring device 500A and the second temperature measuring device 500B provided as described above are located and fixed between the battery case 130 and the gasket 143, so there is little space to move inside the secondary battery and a large Since there is no movement, temperature can be measured stably.

When there are a plurality of temperature measuring devices 500, they may be positioned so as not to overlap each other.

The wire of the reference electrode 200 and the temperature measuring device 500 may be positioned so as not to overlap each other.

The provision of the temperature measuring device may be performed after attachment of the reference electrode, or may be performed before attachment of the reference electrode. The above sequence can be performed by appropriately changing the process so that the reference electrode and the temperature measuring device do not overlap.

Next, the storage step (S2) will be described with reference to FIG. 8. In the storage step, the electrode assembly 120 can be stored in the battery case 130 with the reference electrode 200 attached and the temperature measuring device 500 provided. The battery case 130 has an open top, and the electrode assembly 120 can be accommodated through the top. At this time, since the reference electrode 200 is attached to the outer peripheral surface 125 and/or the lower part 124 of the electrode assembly 120, this structure prevents the metal plate 250 of the reference electrode 200 from interfering with the storage. It may not work.

Thereafter, as shown in FIG. 9, the beading portion 132 may be formed by indenting the area of the battery case 130 above the electrode assembly 120 toward the center of the electrode assembly 120. Although not specifically shown, welding of the electrode tab and insertion of the upper insulating member may be performed before forming the beading portion 132. Meanwhile, in order to prevent the metal wire of the reference electrode 200 from being disconnected, the other end 220 of the reference electrode 200 can be adjusted to be located inside the battery case 130, and the reference electrode ( Only the other end (220) of 200) can be wrapped.

Next, the combining step (S3) will be described with reference to FIG. 10. In the coupling step, the cap assembly 140 is coupled to the open upper part of the battery case 130. Additionally, the gasket 143 can be coupled to the battery case 130 together with the cap assembly 140. The reference electrode 200 and the temperature measuring devices 500A and 500B may be located between the battery case 130 and the gasket 143, and the insulating tape 300 may be located between the battery case 130 and the reference electrode 200. It can be located in .

Finally, the crimping step (S4) will be described with reference to FIG. 11. In the crimping step, the battery case 130 and the cap assembly 140 are crimped together with the reference electrode 200, the temperature measuring devices 500A, 500B, and the gasket 143 interposed, thereby forming the crimping portion 133. ) can be formed.

The reference electrode 200 and the temperature measuring devices 500A and 500B according to an exemplary embodiment of the present invention are provided between the battery case 130 and the cap assembly 140, especially the crimping portion ( It may pass between 133) and gasket 143 and extend to the outside. Without any additional process, the reference electrode 200 for measuring the electrode potential of the three-electrode system can be easily prepared along with the process of storing the electrode assembly 120 in the battery case 130.

In addition, since it is strongly sealed by the crimping portion 133 and the gasket 143, high-temperature evaluation where a large internal pressure occurs can be performed without difficulty.

FIG. 12 shows a charging profile of a secondary battery according to an exemplary embodiment of the present invention, and FIG. 13 shows a discharging profile of a secondary battery according to an exemplary embodiment of the present invention.

By providing the reference electrode 200 and the temperature measuring device 500 as in the present invention, it is possible to obtain the charge/discharge profile of the secondary battery as shown in Figures 12 and 13, and from this, the parts vulnerable to deterioration in the secondary battery structural design are identified. can be identified, and it is possible to predict and prevent safety aspects related to risks due to deterioration.

In this specification, terms indicating directions such as front, back, left, right, up, and down are used, but these terms are only for convenience of explanation and may vary depending on the location of the target object or the location of the observer.

One or more secondary batteries according to an embodiment of the present specification described above may be applied to various devices. For example, it can be applied to transportation means such as electric bicycles, electric vehicles, and hybrids, but is not limited to this and can be applied to various devices that can use secondary batteries.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims are also possible. falls within the scope of rights.

100: Secondary battery
120: Electrode assembly
121: anode
122: cathode
123: Separator
124: Lower part of electrode assembly
125: Outer peripheral surface of electrode assembly
130: Battery case
131: bottom part
132: Bidding department
133: Clamping part
140: Cap assembly
141: top cap
142: cap plate
143: gasket
144: positive tab
145: cathode tab
150: Center pin
160: Top insulation member
170: Bottom insulation member
200: reference electrode
200A: first reference electrode
200B: second reference electrode
200C: Third reference electrode
210: One end of the reference electrode
220: Other end of reference electrode
230: metal wire
240: coating layer
250: metal plate
250A: first metal plate
250B: second metal plate
250C: Third metal plate
300: Insulating tape
400: Separating member
500A: first temperature measuring device
500B: Second temperature measuring device
510: One end of the temperature measuring device
520: Other end of temperature measuring device
601: End of inner surface
602: End of outer peripheral surface

Claims (15)

Jelly roll-shaped electrode assembly;
a battery case storing the electrode assembly and electrolyte;
A cap assembly coupled to the top of the battery case; and
It includes at least three reference electrodes and at least one temperature measuring device,
A secondary battery in which one end of the reference electrode and the temperature measuring device is immersed in the electrolyte solution, and the other end is exposed to the outside through a gap between the battery case and the cap assembly. In claim 1,
A secondary battery wherein the reference electrode and the temperature measuring device are located between the battery case and the gasket. In claim 1,
A secondary battery further comprising an insulating tape positioned between the reference electrode and the battery case. In claim 3,
A secondary battery in which the insulating tape extends along the direction in which the reference electrodes are connected to cover the reference electrode, except for the other end of the reference electrode exposed to the outside. In claim 3,
The insulating tape is a secondary battery in which a random portion of the insulating tape where the reference electrode is located is partially cut in a direction perpendicular to the reference electrode and folded to surround the reference electrode. In claim 1,
A secondary battery comprising a first reference electrode, a second reference electrode, and a third reference electrode. In claim 6,
The first reference electrode further includes a first metal plate attached to one end,
The second reference electrode further includes a second metal plate attached to one end,
A secondary battery wherein the third reference electrode further includes a third metal plate attached to one end. In claim 7,
A secondary battery wherein the first metal plate, the second metal plate, and the third metal plate are located on a straight line including the center of the winding with respect to the lower part of the electrode assembly. In claim 8,
The secondary battery wherein the second metal plate and the third metal plate are located in a direction opposite to the direction in which the first metal plate is located relative to the winding center on a straight line including the winding center. In claim 9,
The secondary battery wherein the second metal plate is located closer to an end of the inner peripheral surface of the lower portion of the electrode assembly than the third metal plate. In claim 9,
A secondary battery wherein the shortest distance between the first metal plate and an end of the inner peripheral surface of the lower part of the electrode assembly is shorter than the shortest distance between the second metal plate and an end of the inner peripheral surface of the lower part of the electrode assembly. In claim 8,
A secondary battery in which a positive electrode tab is located in the upper direction of the area between the first metal plate and the second metal plate. In claim 1,
A secondary battery comprising a first temperature measurement device and a second temperature measurement device. In claim 13,
The first temperature measuring device is located on the outer peripheral surface of the electrode assembly,
The secondary battery wherein the second temperature measuring device is located at the center of the electrode assembly. Attaching at least three reference electrodes to a jelly roll-shaped electrode assembly and placing at least one temperature measuring device on the electrode assembly; providing a reference electrode and a temperature measuring device;
A storage step of storing the electrode assembly in a battery case;
A coupling step of coupling the cap assembly to the top of the battery case; and
A method of manufacturing a secondary battery comprising a crimping step of crimping and combining the battery case and the cap assembly with the reference electrode and the temperature measuring device interposed therebetween.

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