KR20210154423A - Electrode assembly including an auxiliary tab, a secondary battery comprising the same and a battery evaluation method - Google Patents

Abstract

The present invention relates to an electrode assembly for evaluating a monocell formed by adjacent electrodes and a secondary battery including the same, wherein a plurality of first electrodes and a plurality of second electrodes having a polarity opposite to that of the first electrodes are alternately stacked with a separator interposed therebetween, the plurality of first electrodes include a first electrode tab formed on one side surface of the first electrodes and a first auxiliary tab formed on one of both side surfaces perpendicular to the side surface on which the first electrode tab is formed, and the plurality of second electrodes include a second electrode tab formed on one side surface of the second electrodes and a second auxiliary tab formed on one of both side surfaces perpendicular to the side surface on which the second electrode tab is formed.

Description

Electrode assembly including auxiliary tab, secondary battery including same, and battery evaluation method

The present invention relates to an electrode assembly including an auxiliary tab and a secondary battery including the same. The present invention also provides a battery evaluation method using the secondary battery.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and among such secondary batteries, lithium secondary batteries exhibiting high energy density and operating potential, long cycle life, and low self-discharge rate. Batteries have been commercialized and widely used.

In addition, as interest in environmental issues has increased in recent years, electric vehicles (EVs) and hybrid electric vehicles (HEVs) that can replace vehicles using fossil fuels such as gasoline vehicles and diesel vehicles, which are one of the main causes of air pollution, have been developed. There is a lot of research going on. Although nickel-metal hydride (Ni-MH) secondary batteries are mainly used as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs), lithium secondary batteries with high energy density, high discharge voltage and output stability are used. Research is being actively conducted, and some have been commercialized.

Such a lithium secondary battery has a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator is accommodated in a battery case.

1 is a schematic view showing the shape of a conventional electrode assembly. Referring to FIG. 1 , the electrode assembly 10 has a structure in which an anode 13 and a cathode 16 are alternately stacked with a separator 17 interposed therebetween. At this time, the positive electrode 13 has a structure in which the positive electrode active material layer 12 is formed on one or both surfaces of the positive electrode current collector 11 , and the negative electrode 16 has a negative electrode active material layer 15 on one or both surfaces of the negative electrode current collector 14 . ) is the formed structure. A plurality of each of the positive electrode, the negative electrode, and the separator may be stacked as shown in FIG. 1 to constitute one electrode assembly.

On the other hand, in the lithium secondary battery having the above structure, as a main method of evaluating the lithium secondary battery, there is a method of measuring the voltage of the lithium secondary battery, and the voltage between individual electrodes can also be measured. In particular, in a lithium secondary battery, the main method for measuring the voltage between the positive electrode and the negative electrode is a method using a reference electrode.

Korean Patent Registration No. 10-1806416 discloses a technique for measuring a voltage between electrodes constituting an electrode assembly using a reference electrode. However, when the reference electrode is used to measure the voltage as described above, there is a problem in that the reference electrode must be inserted one by one between the electrodes, and a separator to prevent a short circuit between the reference electrode and the electrode assembly must be interposed. can be done In addition, when the reference electrode deteriorates over time, there is a problem that an error may occur in the measured value.

Therefore, in a secondary battery including an electrode assembly including a plurality of electrodes, there is a need to develop a technology capable of simply and accurately measuring the voltage between individual electrodes.

Korean Patent Registration No. 10-1806416

The present invention has been devised to solve the above problems, and by measuring the voltage of a monocell formed by adjacent electrodes with a separator interposed therebetween, an electrode assembly capable of accurately performing electrochemical evaluation of each monocell, and an electrode assembly comprising the same An object of the present invention is to provide a secondary battery. In addition, the present invention provides a battery evaluation method using the secondary battery.

In one example, in the electrode assembly according to the present invention, a plurality of first electrodes and a plurality of second electrodes having a polarity opposite to that of the first electrode are alternately stacked with a separator interposed therebetween, and the plurality of first electrodes The electrode includes a first electrode tab formed on one side of the first electrode, and a first auxiliary tab formed on either side perpendicular to a side surface on which the first electrode tab is formed, and the plurality of second electrodes Each silver includes a second electrode tab formed on one side surface of the second electrode and a second auxiliary tab formed on one of both side surfaces perpendicular to the side surface on which the second electrode tab is formed.

In one example, the electrode assembly according to the present invention includes n+1 electrodes and n second electrodes. (however, n is an integer greater than or equal to 2)

In another example, the electrode assembly according to the present invention includes n of the first electrode and the second electrode. (however, n is an integer greater than or equal to 2)

In a specific example, each of the first auxiliary tabs has a different separation distance from one side surface on which the first electrode tab is formed, and the second auxiliary tab has a different separation distance from one side surface on which the second electrode tab is formed. do.

In a more specific example, the first auxiliary tab and the second auxiliary tab do not overlap each other in the stacking direction of the electrodes.

In one example, the protruding directions of the first auxiliary tabs are the same, and the second auxiliary tabs protrude in opposite directions with respect to the first auxiliary tabs.

In another example, the first auxiliary tab and the second auxiliary tab alternately protrude from each other along the side surface of the electrode assembly.

The present invention also provides a secondary battery, wherein the secondary battery according to the present invention has a structure in which the electrode assembly as described above is accommodated inside the battery case, and each of the first auxiliary tabs and the second auxiliary tabs is connected to a wire The wire has a structure in which one end is electrically connected to the first auxiliary tab or the second auxiliary tab, and the other end is drawn out of the battery case.

The present invention also provides a battery evaluation method using the secondary battery. The battery evaluation method according to the present invention includes the steps of manufacturing the secondary battery as described above;

charging and discharging the secondary battery; electrically connecting a wire connected to the first auxiliary tab and the second auxiliary tab with respect to the first and second electrodes adjacent to each other with a separator interposed therebetween; and measuring a voltage value of a monocell formed by the adjacent first electrode and the second electrode.

In a specific example, measuring the voltage value of the monocell includes measuring the voltage value of each monocell according to the SOC value of the secondary battery.

In a specific example, the battery evaluation method according to the present invention further comprises the step of determining a degraded monocell from the voltage value of the monocell.

In the present invention, since an auxiliary tab capable of measuring a potential is formed on one side of each electrode constituting the electrode assembly, the voltage of the monocell formed by the individual electrodes as well as the voltage of the entire electrode assembly can be easily and accurately measured through the auxiliary tab. measurement, and based on this, it is possible to accurately evaluate the charge amount of the monocell.

1 is a schematic view showing a conventional electrode assembly.
2 is a schematic diagram illustrating shapes of a first electrode and a second electrode constituting an electrode assembly according to an embodiment of the present invention.
3 is a top view schematically showing the shape of an electrode assembly according to an embodiment of the present invention.
4 is a side view schematically illustrating the shape of the electrode assembly according to FIG. 3 as viewed from the direction A;
5 is a schematic diagram illustrating shapes of a first electrode and a second electrode constituting an electrode assembly according to another embodiment of the present invention.
6 is a top view schematically showing the shape of an electrode assembly according to another embodiment of the present invention.
7 is a side view schematically illustrating the shape of the electrode assembly according to FIG. 6 as viewed from the direction A;
8 is a schematic diagram showing the structure of a secondary battery according to an embodiment of the present invention.
9 is a schematic diagram showing the structure of a secondary battery according to another embodiment of the present invention.
10 is a flowchart showing the sequence of the battery evaluation method according to the present invention.

Hereinafter, the present invention will be described in detail. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in

In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof. Also, when a part of a layer, film, region, plate, etc. is said to be “on” another part, it includes not only the case where the other part is “directly on” but also the case where there is another part in between. Conversely, when a part of a layer, film, region, plate, etc. is said to be “under” another part, it includes not only cases where it is “directly under” another part, but also cases where another part is in between. In addition, in the present application, “on” may include the case of being disposed not only on the upper part but also on the lower part.

Hereinafter, the present invention will be described in detail.

2 is a schematic diagram illustrating shapes of a first electrode and a second electrode constituting an electrode assembly according to an embodiment of the present invention. 3 is a top view schematically showing the shape of the electrode assembly according to an embodiment of the present invention, and FIG. 4 is a side view schematically showing the shape of the electrode assembly according to FIG. 3 as viewed from the direction A. Referring to FIG.

2 to 4 , the electrode assembly 100 according to the present invention includes a plurality of first electrodes 110 and a plurality of second electrodes 120 . The first electrode 110 and the second electrode 120 have opposite polarities, and the plurality of first electrodes 110 and the plurality of second electrodes 120 are formed with the separator 130 interposed therebetween. alternately stacked. The first electrode 110 has a structure in which the first electrode active material layer 112 is formed on one or both surfaces of the first electrode current collector 111 , and the second electrode 120 is the second electrode current collector 121 . It has a structure in which the second electrode active material layer 122 is formed on one or both surfaces. Since the technology related to the current collector, the separator, and the active material layer is already known to those skilled in the art, detailed description thereof will be omitted.

Accordingly, the first electrode and the second electrode adjacent to each other with the separator therebetween form a mono cell, and the electrode assembly according to the present invention constitutes a stack cell in which a plurality of mono cells are stacked. do.

In the electrode assembly 100 according to the present invention, the plurality of first electrodes 110 includes a first electrode tab 113 formed on one side of the first electrode and a side surface on which the first electrode tab 113 is formed, respectively. It includes a first auxiliary tab 114 formed on either side of the vertical side.

In addition, the plurality of second electrodes 120 are formed on any one of a second electrode tab 123 formed on one side of the second electrode and a side perpendicular to the side on which the second electrode tab 123 is formed, respectively. and a second auxiliary tab 124 .

In the electrode assembly 100 according to the present invention, the first electrode tab 113 and the second electrode tab 123 serve as an external conductor for the secondary battery to be connected to an external device or to another battery cell, and a plurality of Each of the first electrode tabs and the plurality of second electrode tabs is assembled and connected to the electrode lead. A first electrode lead 115 and a second electrode lead 125 for connecting the battery to the outside are respectively connected to the first electrode tab 113 and the second electrode tab 123 .

The first auxiliary tab 114 and the second auxiliary tab 124 are connected to a wire passing to the outside, as will be described later, and serve to measure a voltage between each electrode. In the electrode assembly according to the present invention, by separately forming auxiliary tabs on the electrodes, it is possible to simply and accurately measure the voltage of the monocell formed between the first electrode and the second electrode adjacent to each other with a separator interposed therebetween as well as the voltage of the entire electrode assembly. The potential thus measured can be used to evaluate the lithium charge in the monocell.

In a specific example, the electrode assembly 100 may have a bi-cell shape. In this case, it includes n+1 first electrodes 110 and n second electrodes 120 (provided that n is an integer greater than or equal to 2), and in FIG. 2 , 9 first electrodes and 8 second electrodes that was shown. In this case, the first electrode 110 is positioned at both ends of the electrode assembly 100 .

2 to 4 , (a) shows the first electrode 110 and (b) shows the second electrode 120 . In addition, in FIG. 2, the numbers below each electrode indicate the stacking order of the electrodes. The (1) electrode is the uppermost electrode, and the (2) electrode is located below the (1) electrode. electrode means. Since the first electrode 110 and the second electrode 120 are alternately stacked with the separator 130 interposed therebetween, the (k) second electrode is positioned under the (k) first electrode when the electrode is stacked. and the (k+1)-th first electrode is positioned below the (k)-th second electrode (where k is an integer between 1 and n). As this lamination pattern is repeated, the first electrode (1) is positioned at the uppermost portion of the electrode assembly 100, and the first electrode (9) is positioned at the lowermost part of the electrode assembly.

2 to 4 illustrate only a case in which the electrode assembly has a bi-cell type, the electrode assembly may have a full-cell type. In this case, the electrode assembly includes both the first electrode and the second electrode n (where n is an integer of 2 or more), and the first electrode and the second electrode are positioned at both ends of the electrode assembly, respectively. For example, when the electrode assembly includes eight first electrodes and eight second electrodes, the first electrode (1) is positioned at the uppermost portion of the electrode assembly, and the second electrode (8) is positioned at the lowermost portion of the electrode assembly. electrodes are placed.

Meanwhile, in the electrode assembly 100 according to the present invention, positions of auxiliary tabs formed on respective electrodes may be different from each other. _{Specifically, each of the first auxiliary tabs 114 has a different separation distance d 1} from one side surface on which the first electrode tab 113 is formed, and the second auxiliary tabs 124 each have a second electrode tab 123 . ) and the separation distance (d ₂ ) from one side formed are different from each other.

_{Referring to FIG. 2 , the distance d 1} of the first auxiliary tab of the (k+1) first electrode is greater than that of the auxiliary tab of the (k) first electrode, d 1 ) from one side surface on which the electrode tab is formed. , where k is an integer between 1 and n). As this pattern is repeated, in the first electrode, the distance d ₁ between the side on which the electrode tab is formed and the auxiliary tab is the largest in the (9) first electrode.

_{Similarly, referring to FIG. 2 , the distance d 2} of the auxiliary tab of the (k+1) second electrode is greater than that of the second auxiliary tab of the (k) second electrode, d 2 , from one side surface on which the electrode tab is formed. (k is an integer between 1 and n). As this pattern is repeated, in the second electrode, the distance d ₂ between the side on which the electrode tab is formed and the auxiliary tab is the largest in the second electrode (8).

As a result, referring to FIGS. 3 and 4 , when the first electrode 110 and the second electrode 120 are stacked, the first auxiliary tab 114 and the second auxiliary tab 124 are aligned in the electrode stacking direction. They do not overlap each other, and are arranged to be spaced apart from each other at regular intervals along the side surface of the electrode assembly 100 .

As described above, by preventing the first auxiliary tab 114 and the second auxiliary tab 124 from overlapping each other in the stacking direction in the electrode assembly 100 , it is easy to connect the wire to the auxiliary tab, and Depending on the flow, adjacent auxiliary tabs can be prevented from contacting each other causing a short circuit or affecting the voltage measurement.

Meanwhile, when a plurality of first electrodes 114 and second electrodes 124 are stacked to form an electrode assembly, the first electrode tab 113 and the second electrode tab 123 are formed in the electrode assembly 100 as shown in FIG. 3 . ), and the first auxiliary tab 114 and the second auxiliary tab 124 protrude at regular intervals along a side perpendicular to the side on which the electrode tab is formed.

In one example, referring to FIG. 3 , the protruding directions of the first auxiliary tabs 114 are the same, and the second auxiliary tabs 124 are opposite to each other with respect to the first auxiliary tabs 114 . is protruded into

To this end, the two first electrodes 110 closest to each other with the two separators 130 and one second electrode 120 interposed therebetween are stacked so that the protrusion directions of the first auxiliary tabs 114 are identical to each other. do. Specifically, the protrusion directions of the first auxiliary tabs are the same in the (k)-th first electrode and the (k+1)-th first electrode most adjacent thereto (provided that k is an integer between 1 and n). Similarly, two second electrodes 120 adjacent to each other with one separator 130 and one first electrode 110 interposed therebetween are stacked so that the protruding directions of the second auxiliary tabs 124 are identical to each other. For example, in the (k)-th second electrode and the (k+1)-th second electrode most adjacent thereto, the protrusion directions of the second auxiliary tabs are the same (provided that k is an integer between 1 and n).

As this pattern is repeated, first auxiliary tabs formed on the first electrodes (1) to (9) are sequentially arranged on one side of the electrode assembly, and (1) to (8) on the opposite side thereof Second auxiliary tabs formed on the No. second electrode are sequentially arranged.

5 is a schematic diagram illustrating shapes of a first electrode and a second electrode constituting an electrode assembly according to another embodiment of the present invention. 6 is a top view schematically showing the shape of the electrode assembly according to another embodiment of the present invention, and FIG. 7 is a side view schematically illustrating the shape of the electrode assembly according to FIG. 6 as viewed from the A direction.

5 to 7 , the electrode assembly 200 according to the present invention includes a plurality of first electrodes 210 and a plurality of second electrodes 220 . The first electrode 210 and the second electrode 220 have opposite polarities, and the plurality of first electrodes 210 and the plurality of second electrodes 220 have a separator 230 interposed therebetween. alternately stacked. The first electrode 210 has a structure in which the first electrode active material layer 212 is formed on one or both surfaces of the first electrode current collector 211 , and the second electrode 220 is the second electrode current collector 221 . It has a structure in which the second electrode active material layer 222 is formed on one or both surfaces.

Accordingly, the first electrode and the second electrode adjacent to each other with the separator therebetween form a mono cell, and the electrode assembly according to the present invention constitutes a stack cell in which a plurality of mono cells are stacked. do.

In the electrode assembly 200 according to the present invention, the plurality of first electrodes 210 includes a first electrode tab 213 formed on one side of the first electrode and a side surface on which the first electrode tab 213 is formed, respectively. It includes a first auxiliary tab 214 formed on any one of the two vertical sides.

In addition, the plurality of second electrodes 220 are formed on any one of a second electrode tab 223 formed on one side surface of the second electrode, and both side surfaces perpendicular to a side surface on which the second electrode tab 223 is formed, respectively. and a second auxiliary tab 224 .

A first electrode lead 215 and a second electrode lead 225 for connecting the battery to the outside are respectively connected to the first electrode tab 213 and the second electrode tab 223 .

In the electrode assembly according to the present invention, by separately forming auxiliary tabs on the electrodes, it is possible to simply and accurately measure the voltage of the monocell formed between the first electrode and the second electrode adjacent to each other with a separator interposed therebetween as well as the voltage of the entire electrode assembly. The potential thus measured can be used to evaluate the lithium charge in the monocell.

As described above, the electrode assembly 200 according to the present invention may be in the form of a bi-cell, and in this case, n+1 first electrodes 210 and n second electrodes 220 are included. When the electrode assembly is in the form of a full cell, the electrode assembly 200 includes all n first electrodes 210 and n second electrodes 220 . 2 to 4 illustrate a case in which the electrode assembly has a bi-cell shape, and 9 first electrodes 210 and 8 second electrodes 220 are illustrated.

5 to 7 , (a) shows the first electrode 210 and (b) shows the second electrode 220 . In addition, in FIG. 5 , the numbers written below each electrode indicate the stacking order of the electrodes. The electrode (1) is the uppermost electrode, and the electrode (2) is located below the electrode (1). electrode means. Since the first electrode 210 and the second electrode 220 are alternately stacked with the separator 230 interposed therebetween, the (k) second electrode is positioned under the (k) first electrode when the electrode is stacked. and the (k+1)-th first electrode is positioned below the (k)-th second electrode (where k is an integer between 1 and n). As this lamination pattern is repeated, the (1) first electrode is positioned at the uppermost portion of the electrode assembly 200, and the (9) first electrode is positioned at the lowermost portion of the electrode assembly.

In the electrode assembly 200 according to the present invention, positions of auxiliary tabs formed on respective electrodes may be different from each other. _{In detail, each of the first auxiliary tabs 214 has a different separation distance d 3} from one side surface on which the first electrode tab 213 is formed, and the second auxiliary tabs 224 are each different from the second electrode tab 223 . ) and the separation distance (d ₄ ) from one side formed are different from each other.

Referring to FIG. 5 , the first auxiliary tab of the (k+1)-th first electrode has a greater _{distance d 3} from the side on which the electrode tab is formed than the auxiliary tab of the (k)-th first electrode (provided that , where k is an integer between 1 and n). As this pattern is repeated, in the first electrode, the distance d1 between the side on which the electrode tab is formed and the auxiliary tab is the largest in the (9) first electrode.

_{Likewise, the auxiliary tab of the (k+1)-th second electrode has a greater distance (d 4} ) from the side on which the electrode tab is formed than the second auxiliary tab of the (k)-th second electrode (provided that k is 1) an integer between and n). As this pattern is repeated, in the second electrode, the distance d ₄ between the side on which the electrode tab is formed and the auxiliary tab is the largest in the second electrode (8).

As a result, referring to FIGS. 6 and 7 , when the first electrode 210 and the second electrode 220 are stacked, the first auxiliary tab 214 and the second auxiliary tab 224 are aligned in the electrode stacking direction. They do not overlap each other, and are arranged to be spaced apart from each other at regular intervals along the side surface of the electrode assembly 200 .

As described above, by preventing the first auxiliary tab 214 and the second auxiliary tab 224 from overlapping each other in the stacking direction in the electrode assembly 200 , it is easy to connect the wire to the auxiliary tab, and Depending on the flow, adjacent auxiliary tabs can be prevented from contacting each other causing a short circuit or affecting the voltage measurement.

Meanwhile, when the plurality of first electrodes 214 and the second electrodes 224 are stacked to form an electrode assembly, the first electrode tab 213 and the second electrode tab 223 are formed in the electrode assembly 200 as shown in FIG. 6 . ), and the first auxiliary tab 214 and the second auxiliary tab 224 protrude at regular intervals along a side perpendicular to the side on which the electrode tab is formed.

In another example, referring to FIG. 6 , the first auxiliary tab and the second auxiliary tab alternately protrude from each other along the side surface of the electrode assembly.

To this end, in the two first electrodes 210 closest to each other with the two separators 230 and one second electrode 220 interposed therebetween, the first auxiliary tabs 214 protrude in opposite directions. do. In addition, in the two second electrodes 220 adjacent to each other with one separator 230 and one first electrode 210 interposed therebetween, the second auxiliary tabs 224 protrude in opposite directions.

5 and 7 , in the (k)-th first electrode and the (k+1)-th first electrode closest to it, the first auxiliary tabs protrude in opposite directions (provided that k is 1 to n) integer between). Similarly, in the (k)-th second electrode and the (k+1)-th second electrode most adjacent thereto, the second auxiliary tabs protrude in opposite directions.

As this pattern is repeated, the first auxiliary tabs 214 and the second auxiliary tabs 224 are alternately arranged on both sides of the electrode assembly 200 .

In addition, in the electrode assembly according to the present invention, any one of the first electrode and the second electrode may be a negative electrode, and at least one of the negative electrodes may be pre-lithiated. By prelithiating at least one of the anodes, it is possible to evaluate the effect of prelithiation of the anode in evaluating the amount of lithium charge through the potential measurement of the monocell.

Pre-lithiation is to minimize irreversible capacity loss that occurs in the first charging and discharging reaction in a secondary battery. It is known that this initial irreversible capacity loss is mostly due to an electrolyte decomposition reaction on the surface of the anode active material, which is to undergo a side reaction that occurs during the first charge through prelithiation. As such a prelithiation method, there are a method of manufacturing an electrode after lithiating the negative active material by a physicochemical method and a method of electrochemically prelithiating the negative electrode. Since it is a known technique, a detailed description thereof will be omitted.

Meanwhile, the present invention provides a secondary battery including the electrode assembly as described above.

8 is a schematic diagram showing the structure of a secondary battery according to an embodiment of the present invention, and FIG. 9 is a schematic diagram showing the structure of a secondary battery according to another embodiment of the present invention.

Referring to FIG. 8 , a secondary battery 300 according to an embodiment of the present invention has a structure in which an electrode assembly 100 is accommodated in a battery case 310 , and the first auxiliary tabs 114 and the second Each of the auxiliary tabs 124 is connected to a wire 320, and the wire 320 has one end electrically connected to the first auxiliary tab 114 or the second auxiliary tab 124, and the other end of the battery. It has a structure drawn out of the case 310 . Here, the electrode assembly 100 is the same as that shown in FIGS. 3 and 4 . Also, the first electrode lead 115 and the second electrode lead 125 are drawn out of the battery case 310 .

Similarly, referring to FIG. 9 , the secondary battery 400 according to another embodiment of the present invention has a structure in which the electrode assembly 200 is accommodated in the battery case 410, the first auxiliary tabs 214 and Each of the second auxiliary tabs 224 is connected to a wire 420 , and the wire 420 has one end electrically connected to the first auxiliary tab 214 or the second auxiliary tab 224 , and the other end of the wire 420 . This structure is drawn out of the battery case 410 . Here, the electrode assembly 200 is the same as that shown in FIGS. 6 and 7 .

In the secondary battery according to the present invention, the battery cases 310 and 410 are not particularly limited as long as they are used as exterior materials for battery packaging, and cylindrical, prismatic, or pouch types may be used, but in detail, pouch-type battery cases can be used.

The wires 320 and 420 are conductive wires for connecting the first auxiliary tabs 114 and 214 and the second auxiliary tabs 214 and 224 protruding from one side of the electrode assembly to the outside. The wire may be formed of a metal material such as copper or aluminum. The number of wires equal to the number of the first auxiliary tabs and the second auxiliary tabs is used, and each wire is connected to one auxiliary tab. One end of the wire is connected to the first auxiliary tab or the second auxiliary tab, and the other end is drawn out and used to electrically connect the auxiliary tab. More specifically, the voltage of the monocell formed by the first electrode and the second electrode can be measured by electrically connecting the wire drawn out from the first auxiliary tab and the wire drawn from the second auxiliary tab to form one circuit. .

Meanwhile, the present invention provides a battery evaluation method using the secondary battery as described above.

10 is a flowchart illustrating a sequence of a battery evaluation method according to the present invention.

Referring to FIG. 10 , the battery evaluation method according to the present invention includes manufacturing a secondary battery as described above (S10); charging and discharging the secondary battery (S20); electrically connecting a wire connected to the first auxiliary tab and the second auxiliary tab with respect to the adjacent first and second electrodes with a separator interposed therebetween (S30); and measuring the voltage value of the monocell formed by the adjacent first electrode and the second electrode (S40).

That is, the battery evaluation method according to the present invention can measure the voltage of the entire electrode assembly as well as the voltage of the monocell formed between the first and second electrodes adjacent to each other with a separator between them simply and accurately by separately forming auxiliary tabs on the electrodes. have. The potential thus measured can be used to evaluate the lithium charge in the monocell.

The secondary battery used in the battery evaluation method according to the present invention has a structure in which the first electrode and the second electrode are alternately stacked with the separator interposed therebetween, as described above, in which auxiliary tabs are formed separately on the first electrode and the second electrode to be. The auxiliary tab may be manufactured by integrally molding the current collector to form a structure in which the electrode current collector is extended, or by manufacturing a separate auxiliary tab and bonding it to the electrode current collector through welding or the like. First electrode and The second electrode is manufactured by applying an electrode active material to the current collector, respectively, and a detailed description thereof is the same as described above.

The secondary battery manufactured as described above may be charged and discharged to exhibit a certain level of state of charge (SOC). The charging/discharging process may be performed by a known method, and may be performed by connecting the charger to the first electrode lead and the second electrode lead respectively connected to the first electrode tab and the second electrode tab.

In such a secondary battery, each electrode is electrically connected to each other for voltage measurement. Specifically, the wire connected to the first auxiliary tab and the second auxiliary tab is electrically connected to the first electrode and the second electrode adjacent to each other with the separator interposed therebetween. Here, the electrical connection means that the first electrode and the second electrode are connected in a circuit through a wire connected to the auxiliary tab to enable voltage measurement. A voltage measuring device may be connected between the wire drawn out from the first auxiliary tap and the wire drawn out from the second auxiliary tap for measuring the voltage.

Thereafter, the charge amount of each monocell included in the electrode assembly may be evaluated by measuring the voltage value of the monocell formed by the adjacent first electrode and the second electrode. Voltage measurement can be measured separately for each monocell. Taking the secondary battery according to FIG. 8 as an example, by measuring the voltage after connecting the first auxiliary tab of the (k) first electrode and the second auxiliary tab of the (k) second electrode through a wire, (k) The voltage of the monocell formed by the first electrode and the (k+1)-th second electrode may be measured. Then, after connecting the second auxiliary tab of the (k) second electrode and the first auxiliary tab of the (k+1) first electrode through a wire, the voltage is measured to connect the (k+1) first electrode and ( The voltage of the monocell formed by the second electrode k) may be measured (however, k is an integer between 1 and n). The voltage value of each monocell measured in this way can be converted into SOC to evaluate the lithium charge amount of each monocell. 8 or 9 , when the electrode assembly includes nine first electrodes and eight second electrodes, voltages of a total of 16 monocells can be measured.

In addition, the step of measuring the voltage value of the monocell includes the process of measuring the voltage value of each monocell according to the SOC value of the secondary battery. This is to simulate the charge amount of lithium of an electrode assembly in which a plurality of electrodes are stacked during the charging process of the secondary battery. Specifically, in the step of charging and discharging the secondary battery, after charging the secondary battery to a specific SOC, the voltage of each monocell may be measured to evaluate the lithium charge amount of each monocell. For example, the SOC of the secondary battery is gradually changed, such as measuring the voltage of each monocell with the SOC of the secondary battery set to 10%, and then measuring the voltage of each monocell with the SOC set to 20% It is possible to simulate how the lithium charge amount of each monocell changes.

The battery evaluation method according to the present invention further includes the step (S50) of determining the degraded monocell from the voltage value of the monocell. A degraded monocell means a monocell including an electrode that is deteriorated or defective according to the use of the battery. In the battery evaluation method according to the present invention, a monocell exhibiting a lower voltage than the average voltage of other monocells or a set reference voltage may be evaluated as degraded.

In addition, in the battery evaluation method according to the present invention, the manufacturing of the secondary battery may include prelithiation of at least one of the negative electrodes. This is to evaluate the effect of pre-lithiation of the negative electrode in evaluating the amount of lithium charge by pre-lithiating at least one of the negative electrodes as described above. As described above, as the prelithiation method, known techniques such as a method of manufacturing an electrode after lithiating the negative active material by a physicochemical method and a method of electrochemically prelithiating the negative electrode can be used.

Accordingly, in the step of measuring the voltage value of the monocell, the lithium charge amount of the pre-lithiated negative electrode and the non-lithiated negative electrode may be compared, and the amount of lithium doped into the negative electrode during pre-lithiation may be evaluated. This can be evaluated by measuring the discharge capacity. Specifically, after prelithiating a portion of the negative electrode included in the electrode assembly, the secondary battery is charged only once, and the voltage of each monocell is measured while discharging it again, and the discharge profile of each monocell can be obtained from this. . The discharge capacity and the irreversible capacity of each monocell are calculated from the discharge profile, and it can be understood to what extent the irreversible capacity is improved in the monocell including the pre-lithiated negative electrode compared to the monocell which does not.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Accordingly, the drawings disclosed in the present invention are for explanation rather than limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these drawings. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Meanwhile, in this specification, terms indicating directions such as up, down, left, right, front, and back are used, but these terms are for convenience of explanation only, and may vary depending on the location of the object or the position of the observer. It is self-evident that it can

10, 100, 200: electrode assembly
11: positive electrode current collector 12: positive electrode active material layer
13: positive electrode 14: negative electrode current collector
15: negative electrode active material layer 16 negative electrode
17: separator
110, 210: first electrode 111, 211: first electrode current collector
112, 212: first electrode active material layer 113, 213: first electrode tab
114, 214: first auxiliary tabs 115, 215: first electrode lead
120, 220: second electrode 121, 221: second electrode current collector
122, 222: second electrode active material layer 123, 223: second electrode tab
124, 224: second auxiliary tab 125, 225: second electrode lead
130, 230: separator
300, 400: secondary battery 310, 410: battery case
320, 420: wire

Claims (11)

A plurality of first electrodes and a plurality of second electrodes having a polarity opposite to that of the first electrode are alternately stacked with a separator interposed therebetween,
Each of the plurality of first electrodes includes a first electrode tab formed on one side of the first electrode and a first auxiliary tab formed on one of both sides perpendicular to the side on which the first electrode tab is formed,
Each of the plurality of second electrodes includes an electrode assembly including a second electrode tab formed on one side of the second electrode and a second auxiliary tab formed on either side perpendicular to the side surface on which the second electrode tab is formed. .
According to claim 1,
An electrode assembly including n+1 first electrodes and n second electrodes.
(however, n is an integer greater than or equal to 2)
According to claim 1,
An electrode assembly including n of the first electrode and the second electrode.
(however, n is an integer greater than or equal to 2)
According to claim 1,
Each of the first auxiliary tabs has a different separation distance from one side surface on which the first electrode tab is formed,
Each of the second auxiliary tabs has a different separation distance from one side surface on which the second electrode tab is formed.
5. The method of claim 4,
The first auxiliary tab and the second auxiliary tab do not overlap each other in the electrode stacking direction.
According to claim 1,
The protrusion directions of the first auxiliary tabs are the same as each other,
The second auxiliary tabs protrude in opposite directions with respect to the first auxiliary tabs.
According to claim 1,
The first auxiliary tab and the second auxiliary tab alternately protrude from each other along a side surface of the electrode assembly.
The electrode assembly according to claim 1 has a structure accommodated inside the battery case,
Each of the first auxiliary tabs and the second auxiliary tabs are connected to a wire,
The wire has one end electrically connected to the first auxiliary tab or the second auxiliary tab, and the other end is drawn out of the battery case.
manufacturing the secondary battery according to claim 8;
charging and discharging the secondary battery;
electrically connecting a wire connected to the first auxiliary tab and the second auxiliary tab with respect to the first and second electrodes adjacent to each other with a separator interposed therebetween; and
and measuring a voltage value of a monocell formed by the adjacent first electrode and the second electrode.
10. The method of claim 9,
The step of measuring the voltage value of the monocell,
A battery evaluation method comprising the step of measuring the voltage value of each monocell according to the SOC value of the secondary battery.
10. The method of claim 9,
Battery evaluation method further comprising the step of determining a degraded monocell from the voltage value of the monocell.

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