Specification
Title of Invention: Secondary Battery and Secondary Battery Manufacturing Method
technical field
[One]
Cross-Citation with Related Application(s)
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2020-0011328 dated January 30, 2020, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.
[3]
The present invention relates to a secondary battery and a method for manufacturing the secondary battery, and more particularly, to a secondary battery including a reference electrode for measuring an electrode potential of a three-electrode system, and a method for manufacturing such a secondary battery.
background
[4]
Recently, an increase in the price of an energy source due to the depletion of fossil fuels, interest in environmental pollution is increasing, and the demand for an eco-friendly alternative energy source is becoming an indispensable factor for future life. Accordingly, research on various power production technologies such as nuclear power, solar power, wind power, and tidal power continues, and power storage devices for using the generated energy more efficiently are also of great interest.
[5]
In particular, as technology development and demand for mobile devices increase, the demand for batteries as an energy source is rapidly increasing, and accordingly, a lot of research on batteries capable of meeting various needs is being conducted.
[6]
Typically, there is a high demand for lithium secondary batteries, such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.
[7]
In addition, secondary batteries are classified according to the structure of the electrode assembly in which a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode are stacked. Typically, a jelly roll (winding type) electrode assembly in which a long sheet-shaped anode and anode are wound with a separator interposed therebetween, and a plurality of cathodes and anodes cut into units of a predetermined size are placed in a state with a separator interposed therebetween. and stack-type (stack-type) electrode assemblies stacked sequentially. Recently, in order to solve the problems of the jelly-roll type electrode assembly and the stack type electrode assembly, as a mixed type of the jelly-roll type and the stack type, a unit cell in which positive and negative electrodes of a predetermined unit are stacked with a separator interposed therebetween. A stack/folding type electrode assembly having a structure in which they are sequentially wound in a state in which they are placed on a separation film has been developed.
[8]
In addition, depending on the shape of the case, the secondary battery includes a cylindrical battery in which the electrode assembly is embedded in a cylindrical case, a prismatic battery in which the electrode assembly is embedded in a prismatic case, and a pouch in which the electrode assembly is embedded in a pouch-shaped case of an aluminum laminate sheet. classified as a type battery.
[9]
1 is a schematic diagram schematically showing the structure of a cylindrical secondary battery 10 .
[10]
Referring to FIG. 1 , in the cylindrical secondary battery 10 , the electrode assembly 20 having a wound type structure is accommodated in a cylindrical case 30 , and after injecting an electrolyte into the case 30 , the case 30 is opened. It is manufactured by combining the cap assembly 40 in which the electrode terminal is formed on the upper end.
[11]
In addition, the beading part 31 recessed in the center direction may be formed in the case 30 for stably coupling the cap assembly 40 and preventing the electrode assembly 20 from flowing.
[12]
When the electrode assembly 20 is mounted on the case 30 , the first electrode tab 51 and the second electrode tab 61 protrude in opposite directions. Furthermore, the first electrode tab 51 is connected to the cap assembly 40 coupled to the open surface of the case 30 in a state in which it protrudes in the direction of the open surface of the case 30 , and thus, the cap assembly One surface of (40) acts as the first electrode (50).
[13]
The second electrode tab 61 protrudes in the direction of the lower surface opposite to the open surface of the case 30 and is coupled to the inner surface of the case 30 , and accordingly, the lower surface of the case 30 is the second electrode 60 . acts as
[14]
The first electrode 50 and the second electrode 60 may be an anode and a cathode, respectively.
[15]
In order to check the performance of the newly developed and manufactured battery cell, the electrode potential of the battery cell is measured.
[16]
A three-electrode system electrode potential measurement method comprising a reference electrode, a working electrode, and a counter electrode is mainly used to measure the electrode potential.
[17]
A reference electrode is an electrode used to make a battery circuit for measuring an electrode potential to measure the potential of an electrode constituting a battery or an electrode undergoing electrolysis.
[18]
FIG. 2 is a schematic view showing the secondary battery of FIG. 1 after cutting the beading part for measuring the electrode potential.
[19]
Referring to FIG. 2 , the beading part 31 of the secondary battery 10 of FIG. 1 is cut in order to measure the electrode potential. The separated cylindrical secondary battery 10a includes a cap assembly 40a having an open lower portion and a case 30a having an open upper portion, and the first electrode tab 51 is maintained uncut. That is, the sealing of the cylindrical secondary battery 10a is released by cutting the beading part 31 .
[20]
3 is a schematic diagram schematically showing a conventional electrode potential measurement method, and specifically, a conventional electrode potential measurement method using the cylindrical secondary battery 10a of FIG. 2 .
[21]
Referring to FIG. 3 together with FIG. 2 , the separated, that is, the sealed cylindrical secondary battery 10a is sealed in the tray 70 while immersed in the electrolyte 71, and the separated cylindrical secondary battery ( A working electrode terminal 52 and a counter electrode terminal 62 for measuring an electrode potential are respectively connected to the first electrode 50 and the second electrode 60 of 10a).
[22]
The working electrode terminal 52 and the counter electrode terminal 62 are connected to the measurement unit 73 together with the reference electrode terminal 72 to measure the electrode potential of the cylindrical secondary battery 10a.
[23]
However, in the case of such a conventional electrode potential measurement method, even in the same cylindrical secondary battery 10a, the data value may vary depending on the measurement procedure or method of the measurer. In particular, in the conventional method, it is difficult to closely control the amount of electrolyte input, and when the amount of electrolyte is excessively added, a large deviation may occur in the measured data value.
[24]
In addition, the resistance may increase due to the introduction of an additional conducting wire or an excessive amount of electrolyte. That is, it is difficult to measure the actual potential because various types of resistance are involved in the electrode potential.
[25]
In addition, since the cylindrical secondary battery 10a is immersed in the electrolyte, there is a problem in that the electrolyte is used more than necessary.
[26]
As described above, since the conventional method for measuring the three-electrode system electrode potential has many problems, the need for a technology capable of solving these problems is very high.
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[27]
Embodiments of the present invention are proposed to solve the above problems of the previously proposed methods, and provide a secondary battery capable of accurately measuring an actual electrode potential without introducing a separate tray and a method for manufacturing such a secondary battery is intended for
[28]
However, the problems to be solved by the embodiments of the present invention are not limited to the above problems and may be variously expanded within the scope of the technical idea included in the present invention.
means of solving the problem
[29]
A secondary battery according to an embodiment of the present invention includes an electrode assembly in the form of a jelly roll impregnated with an electrolyte; a battery case accommodating the electrode assembly and the electrolyte; a cap assembly coupled to an upper portion of the battery case; and a reference electrode having one end immersed in the electrolyte and the other end exposed to the outside through a gap between the battery case and the cap assembly.
[30]
The secondary battery may further include a gas-tight gasket positioned between the battery case and the cap assembly, and the reference electrode may be positioned between the battery case and the gasket.
[31]
The battery case and the cap assembly may be coupled by crimping with the gasket and the reference electrode interposed therebetween.
[32]
The reference electrode may extend from a lower portion of the electrode assembly along an outer circumferential surface of the electrode assembly to pass between the battery case and the cap assembly.
[33]
The one end of the reference electrode may be located under the electrode assembly.
[34]
The secondary battery may further include a separation member positioned between the electrode assembly and the one end of the reference electrode.
[35]
The secondary battery may further include an insulating tape positioned between the reference electrode and the battery case.
[36]
The insulating tape may include at least one of polyimide (PI), polyethylene terephthalate (PET), and polypropylene (PP).
[37]
The insulating tape may extend to cover the one end of the reference electrode.
[38]
The reference electrode may include a metal wire and a coating layer surrounding the metal wire.
[39]
The coating layer may include an enamel layer.
[40]
The reference electrode may include a metal plate attached to the one end of the reference electrode.
[41]
A method of manufacturing a secondary battery according to an embodiment of the present invention includes an attachment step of attaching a reference electrode to an electrode assembly in the form of a jelly roll; a receiving step of accommodating the electrode assembly to which the reference electrode is attached in a battery case; a coupling step of coupling a cap assembly to an upper portion of the battery case; and a crimping step of crimping the battery case and the cap assembly with the reference electrode interposed therebetween.
[42]
The attaching may include attaching the reference electrode to the electrode assembly using an electrically insulating insulating tape.
[43]
The coupling step may include coupling a gasket together with the cap assembly to an upper portion of the battery case, and the crimping step may include the battery case and the cap assembly with the reference electrode and the gasket interposed therebetween. It may include the step of combining the crimping (Crimping).
filial pietyclass
[44]
According to embodiments of the present invention, it is possible to provide a secondary battery capable of accurately measuring an actual electrode potential by providing a reference electrode passing between the battery case and the cap assembly.
[45]
In addition, by using an actual secondary battery without introducing a separate tray, it is possible to obtain an electrode potential value excluding resistance intervened by an additional conducting wire or an excessive amount of electrolyte.
[46]
In addition, since the reference electrode is configured to pass between the battery case and the cap assembly rather than exposing it to the outside by forming a separate hole, the electrode potential is maintained without damaging the structure of the secondary battery and maintaining sealing. measurement is possible. In addition, there is an advantage in that it is possible to proceed with a high-temperature evaluation in which the internal pressure is large.
Brief description of the drawing
[47]
1 is a schematic diagram schematically showing the structure of a cylindrical secondary battery.
[48]
FIG. 2 is a schematic view showing the cylindrical secondary battery of FIG. 1 after cutting the beading part for measuring the electrode potential.
[49]
3 is a schematic diagram schematically illustrating a conventional electrode potential measurement method.
[50]
4 is a cross-sectional perspective view of a secondary battery according to an embodiment of the present invention.
[51]
FIG. 5 is an enlarged cross-sectional view of part “A” of FIG. 4 .
[52]
6 is an enlarged cross-sectional view of part “B” of FIG. 4 .
[53]
7 is a perspective view illustrating a reference electrode, an insulating tape, and a separation member included in the secondary battery of FIG. 4 .
[54]
8 is a perspective view illustrating a state in which the reference electrode, the insulating tape, and the separation member of FIG. 7 are attached to the electrode assembly.
[55]
9 to 12 are views for explaining a process of manufacturing a secondary battery according to an embodiment of the present invention.
Modes for carrying out the invention
[56]
Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.
[57]
In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar elements throughout the specification.
[58]
In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for convenience of description, the present invention is not necessarily limited to the illustrated bar. In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions are exaggerated.
[59]
Also, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, it includes not only cases where it is “directly on” another part, but also cases where another part is in between. . Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, to be "on" or "on" the reference part means to be located above or below the reference part, and it means to be located "on" or "on" in the direction opposite to the gravity. not.
[60]
In addition, throughout the specification, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated.
[61]
In addition, throughout the specification, when it is referred to as "planar view", it means when the target part is viewed from above, and when it is referred to as "cross-section", it means when the cross-section obtained by cutting the target part vertically is viewed from the side.
[62]
4 is a cross-sectional perspective view of a secondary battery according to an embodiment of the present invention, FIG. 5 is an enlarged cross-sectional view of part “A” of FIG. 4 , and FIG. 6 is an enlarged cross-sectional view of part “B” of FIG. 4 . .
[63]
4 to 6, the secondary battery 100 according to an embodiment of the present invention includes an electrode assembly 120 in the form of a jelly roll impregnated with an electrolyte, an electrode assembly 120, and a battery case for accommodating the electrolyte ( 130 ), a cap assembly 140 coupled to the upper portion of the battery case 130 , and a reference electrode 200 . One end 210 of the reference electrode 200 is immersed in the electrolyte, and the other end 220 is exposed to the outside through the gap between the battery case 130 and the cap assembly 140 .
[64]
The electrode assembly 120 has a structure in the form of a jelly roll wound with a separator 123 interposed between the plurality of positive electrodes 121 and negative electrodes 122 , and a center pin 150 may be inserted into the center thereof. A top insulating member 160 (Top insulator) may be positioned on the upper portion of the electrode assembly 120 , and a lower insulating member between the lower portion 124 of the electrode assembly 120 and the bottom portion 131 of the battery case 130 . (170, Bottom insulator) may be located.
[65]
The electrolyte may be a lithium salt-containing non-aqueous electrolyte, and the lithium salt-containing non-aqueous electrolyte includes a non-aqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, and the like are used, but are not limited thereto. This electrolyte is accommodated in the battery case 130 together with the electrode assembly 120, and detailed marks are omitted from the drawings.
[66]
The battery case 130 may include a beading part 132 and a crimping part 133 .
[67]
The beading part 132 refers to a portion in which a part of the battery case 130 is recessed toward the center of the electrode assembly 120 , and prevents stable coupling of the cap assembly 140 and flow of the electrode assembly 120 .

Claims
[Claim 1]
Electrode assembly in the form of a jelly roll impregnated with an electrolyte; a battery case accommodating the electrode assembly and the electrolyte; a cap assembly coupled to an upper portion of the battery case; and a reference electrode having one end immersed in the electrolyte and the other end exposed to the outside through a gap between the battery case and the cap assembly.
[Claim 2]
The secondary battery of claim 1 , further comprising a gasket for maintaining airtightness positioned between the battery case and the cap assembly, wherein the reference electrode is positioned between the battery case and the gasket.
[Claim 3]
The secondary battery of claim 2 , wherein the battery case and the cap assembly are coupled by crimping with the gasket and the reference electrode interposed therebetween.
[Claim 4]
The secondary battery of claim 1 , wherein the reference electrode extends from a lower portion of the electrode assembly along an outer circumferential surface of the electrode assembly and passes between the battery case and the cap assembly.
[Claim 5]
The secondary battery of claim 1 , wherein the one end of the reference electrode is positioned below the electrode assembly.
[Claim 6]
The secondary battery of claim 5, further comprising a separation member positioned between the electrode assembly and the one end of the reference electrode.
[Claim 7]
The secondary battery of claim 1, further comprising an insulating tape positioned between the reference electrode and the battery case.
[Claim 8]
The secondary battery of claim 7 , wherein the insulating tape includes at least one of polyimide (PI), polyethylene terephthalate (PET), and polypropylene (PP).
[Claim 9]
The secondary battery of claim 7 , wherein the insulating tape extends to cover the one end of the reference electrode.
[Claim 10]
The secondary battery of claim 1 , wherein the reference electrode includes a metal wire and a coating layer surrounding the metal wire.
[Claim 11]
The secondary battery of claim 1 , wherein the coating layer comprises an enamel layer.
[Claim 12]
The secondary battery of claim 1 , wherein the reference electrode includes a metal plate attached to the one end of the reference electrode.
[Claim 13]
Attaching step of attaching a reference electrode to the electrode assembly in the form of a jelly roll; a receiving step of accommodating the electrode assembly to which the reference electrode is attached in a battery case; a coupling step of coupling a cap assembly to an upper portion of the battery case; and a crimping step of clamping the battery case and the cap assembly with the reference electrode interposed therebetween.
[Claim 14]
The method of claim 13 , wherein the attaching comprises attaching the reference electrode to the electrode assembly using an electrically insulating insulating tape.
[Claim 15]
14. The method of claim 13, wherein the coupling step comprises coupling a gasket together with the cap assembly to an upper portion of the battery case, and the crimping step is performed with the battery case with the reference electrode and the gasket interposed therebetween. A method of manufacturing a secondary battery comprising the step of crimping the cap assembly.