KR20200053784A - System and method for discriminating defective folded electrode tabs of battery cell - Google Patents

Abstract

The present invention relates to a system for discriminating a failure of electrode tab folding of a battery cell and to a method thereof. According to one embodiment, the method for discriminating a failure of electrode tab folding of a battery cell comprises the steps of: calculating a capacity of a plurality of battery cells constituting a lot; calculating a capacity representative value for the plurality of battery cells constituting the lot; deriving a relative lower limit reference value for the electrode tab folding of the battery cell from the capacity representative value; and determining that the battery cell representing a capacity lower than the relative lower limit reference value is a failure of the electrode tab folding.

Description

Determination system of electrode tab folding of battery cell and method therefor {SYSTEM AND METHOD FOR DISCRIMINATING DEFECTIVE FOLDED ELECTRODE TABS OF BATTERY CELL}

The present invention relates to a system and method for discriminating a bad electrode tab folding of a battery cell.

Secondary batteries that can be charged and discharged are electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-ins that have been proposed as solutions to air pollution in existing gasoline and diesel vehicles using fossil fuels. It is attracting attention as a power source for devices requiring high output and large capacity, including hybrid electric vehicles (Plug-In HEV).

Typically, in the shape of the battery, the demand for a square secondary battery and a pouch-type secondary battery that can be applied to products such as a mobile phone with a small thickness is high, and in terms of material, it has advantages such as high energy density, discharge voltage, and output stability. There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

These secondary batteries are classified according to the structure of the electrode assembly of the anode / separator / cathode structure, and representatively, a jelly-roll having a structure in which the anodes and cathodes of a long sheet type are wound with a separator interposed therebetween. (Wind-up type) electrode assembly, a stacked (stacked) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, and a positive electrode and a negative electrode of a predetermined unit are interposed with a separator. And a stacked / folded electrode assembly having a structure in which bi-cells or full cells stacked with are wound.

The secondary battery has a structure in which an electrode assembly made of a positive electrode, a negative electrode, and a separator interposed therebetween and an electrolyte solution are housed in a battery case. As a device based on an electrochemical reaction, it is inevitably sensitive to environmental factors, and small parts are limited. It is manufactured through a series of processes that are precisely mounted and connected in a space, so product quality may deteriorate due to errors in some devices and incomplete work by some workers. In addition, in the manufacturing process of the secondary battery by the mass production system, serious defects may be caused by small defects in the process.

Accordingly, after every manufacturing process step and / or finished product manufacturing, inspection of the secondary battery should be closely conducted. This inspection is one of the most important in the production process of a secondary battery and is important in terms of quality control to check whether it provides desired performance and stability. Here, quality control is to determine whether the secondary battery properly has a charge / discharge performance, to produce good products, and to screen out defective products. By performing such quality control well, it is possible to produce a high quality secondary battery.

Meanwhile, the secondary battery is manufactured as a battery cell having various shapes and performances so as to provide output and capacity suitable for the applied device. In general, the capacity of the secondary battery is determined by reflecting the required margin in accordance with the customer's required capacity standard. This is a reasonable and economical method to determine the capacity to be achieved, but when selecting a distribution outlier within a lot, if the lot's center of gravity is skewed to the upper limit, the outlier also satisfies the required capacity criterion. There is a limit to receiving.

In addition, minimization of subsidiary materials is unavoidable due to high loading of raw materials and slim type or various design trends due to high capacity of batteries. Due to this, in particular, in the battery pack assembly process of assembling the bicell stack-type electrode assembly inside the battery case, the risk of occurrence of defects such as electrode tab folding increases, but electrode tab folding, which is a defect occurring in the battery pack assembly process, is increased. There are difficulties in screening. In addition, due to the characteristics that the battery pack is manufactured in a mass production system through a precise assembly process, it is not easy to identify small defects in the production line, and problems in defects or deterioration of the quality of products can actually be used in devices, etc. The cause can be found later or in that it can be confirmed.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a system and a method of discriminating using the same for discriminating defects in electrode tab folding among battery cell assembly defects.

A method of determining a defect in folding of an electrode tab of a battery cell according to an embodiment of the present invention includes: calculating a capacity of a plurality of battery cells constituting a lot; Calculating a capacity representative value for the plurality of battery cells constituting the lot; Deriving a relative lower limit reference value for folding of the electrode tab of the battery cell from the representative capacity value; And determining that the battery cell exhibiting a capacity below the relative lower limit reference value is an electrode tab folding failure.

At this time, in the step of calculating the representative capacity of the capacity, the representative capacity of the capacity may be an average value of the capacity, a median or a mode.

In addition, in the step of deriving the relative lower limit reference value, the relative lower limit reference value for the folding of the electrode tab generated internally based on the electrode assembly of the battery cell may be derived by Equation 1 below.

[Equation 1]

In Equation 1, R _li is the relative lower reference value, R _c is the capacity representative value, N _e is the number of electrodes of the battery cell, and N _t is the number of electrodes that do not react due to the folding of the tab. .

In addition, in the step of deriving the relative lower limit reference value, the relative lower limit reference value for the electrode tab folding occurring at the outermost side based on the electrode assembly of the battery cell may be derived by Equation 2 below.

[Equation 2]

In Equation 2, the R _lo is the relative lower limit reference value, the R _c is the capacity representative value, the N _e is the number of electrodes of the battery cell, and N _t is the number of electrodes that do not react due to the tab folding. .

Meanwhile, prior to deriving the relative lower limit reference value, the method may further include calculating the number of electrodes of the battery cell.

Here, the number of electrodes may be the number of anodes or the number of cathodes, or the number of anodes and cathodes.

In addition, in the electrode assembly of the battery cell, a cathode / separator / anode / separator / cathode-structured C-type bicell and an anode / separator / cathode / separator / anode-structured A-type bicell are alternately stacked, at the outermost both ends. Each of the C-type bicells may be arranged.

In addition, calculating the number of electrodes of the battery cell may include: calculating the number of C-type bicells; And calculating the number of electrodes of the battery cell from the number of C-type bicells.

In this case, the number of C-type bicells may be derived by Equation 3 below.

[Equation 3]

In Equation (3), wherein N _c N _b is the number of the C-type bi-cell, is the total number of cells by the electrode assembly.

In addition, the number of electrodes of the battery cell may be derived by Equation 4 below.

[Equation 4]

In Equation 4, N _e is the number of electrodes of the battery cell, and N _c is the number of C-type bicells.

Meanwhile, the uppermost electrode and the lowermost electrode, which are the outermost electrodes forming the outer surface of the electrode assembly of the battery cell, may have the same polarity.

In addition, the electrode tab folding defect determination system of a battery cell according to an embodiment of the present invention includes a capacity calculating unit for calculating the capacity of a plurality of battery cells constituting a lot; A capacity representative value calculator for calculating a capacity representative value for the plurality of battery cells constituting the lot; A relative lower limit reference value deriving unit deriving a relative lower limit reference value for folding of the electrode tab of the battery cell from the representative capacity value; And it may include a discrimination unit for determining the battery cell exhibiting a capacity below the relative lower limit reference value as the electrode tab folding failure.

The electrode tab folding defect determination system of the battery cell may further include an input unit that receives the number of electrode assemblies of the battery cell.

In addition, the electrode tab folding defect determination system of the battery cell may further include an electrode number calculating unit for calculating the number of electrodes of the battery cell.

In addition, the electrode tab folding defect determination system of the battery cell stores the calculated capacity of the battery cell, the calculated capacity representative value, the derived relative lower limit reference value, the number of input electrode assemblies, and the calculated number of electrodes. It may further include a storage unit.

According to an embodiment of the present invention, by applying the condition for determining the defect of the battery cell relative to each lot, it is possible to minimize the occurrence of defects other than the relative lower limit reference value according to the change in the representative capacity of each lot, and it is possible to remove defective products in the existing good quality determination area. There is an advantage, it is possible to improve the reliability in screening the defects of the battery cell.

In addition, it is possible to derive a relative lower limit reference value according to the design characteristics of the battery cell, and it is possible to calculate a capacity reduction level due to defects such as electrode tab folding occurring at the inner or outermost side of the electrode assembly, and thus defective products due to electrode tab folding There is an effect that can be discriminated.

1 is a schematic diagram of an exemplary structure of an electrode assembly.
FIG. 2 is a perspective view illustrating folding of an electrode tab occurring when assembling the electrode assembly of FIG. 1.
3 is a block diagram schematically illustrating a system for determining a defect in folding of an electrode tab of a battery cell according to an embodiment of the present invention.
4 is a flowchart illustrating a method for determining a defect in folding of an electrode tab of a battery cell according to an embodiment of the present invention.
5 is a dose histogram according to Example 1.
6 is a dose histogram according to Example 2.

The present invention can be applied to various changes and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosure form, and it should be understood that it includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals are used for similar components. In the accompanying drawings, the dimensions of the structures are shown to be enlarged than the actual for clarity of the present invention. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described in the specification, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, actions, components, parts or combinations thereof are not excluded in advance. In addition, when a part such as a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the case of being "directly above" the other part but also another part in the middle. Conversely, when a portion of a layer, film, region, plate, etc. is said to be “under” another portion, this includes not only the case “underneath” another portion, but also another portion in the middle. In addition, in the present application, being referred to as being "on" may include the case of being disposed on the lower portion as well as the upper portion.

Hereinafter, with reference to the drawings will be described in detail with respect to the electrode tab folding failure determination system of a battery cell according to an embodiment of the present invention.

3 is a block diagram schematically illustrating a system for determining a defect in folding of an electrode tab of a battery cell according to an embodiment of the present invention. As shown in FIG. 1, the electrode tab folding defect determination system of the battery cell includes a capacity calculation unit 110, a capacity representative value calculation unit 120, a relative lower limit reference value calculation unit 130, and a failure determination unit 140. It can contain.

The capacity calculator 110 may calculate the capacity of a plurality of battery cells 200 constituting a lot. At this time, the capacity of the battery cell can be calculated by measuring the open voltage (open circuit voltage, OCV) and discharge voltage, it can be calculated by using a conventional method other than that, a detailed description thereof will be omitted.

The capacity representative value calculating unit 120 may calculate a representative value for the capacity of a plurality of battery cells constituting a lot. In general, a lot is a collection of a plurality of battery cells, and means a unit or unit amount of a material, part, product, etc., collected for a certain purpose. For example, when a certain type of product is put together and a production order or production is made with about 100 units as one unit, these 100 units are called production lots and the united quantity units of 100 units are called lot sizes. When manufacturing a battery cell, it can be manufactured by configuring in a predetermined lot unit.

At this time, the representative capacity value may be an average value, a median number or a mode number for the capacity of the battery cell, and can be freely selected as a desired representative value in accordance with the required capacity standard.

The relative lower limit reference value calculating unit 130 may calculate a relative lower limit reference value for folding of the electrode tab of the battery cell from the representative capacity value. The relative lower limit reference value is a theoretical capacity reduction level calculated according to a representative capacity value for each lot, which can be said to calculate a capacity reduction level due to defects such as electrode tab folding. That is, the relative lower limit reference value may be set differently according to the capacity of a plurality of battery cells constituting a lot, the capacity representative value, or the like, and may mean a capacity for determining that the battery cell is normal or defective.

Here, the relative lower limit reference value can be calculated not only from the representative capacity value, but also from the number of electrodes in the battery cell. Accordingly, the system of the present invention may further include an input unit 150 for receiving the number of electrode assemblies of the battery cell and an electrode number calculating unit 160 for calculating the number of electrodes of the battery cell. The number of electrode assemblies of the battery cell received from the input unit 150 is input to the electrode number calculating unit 160, from which the number of electrodes of the battery cell can be calculated. In addition, the electrode assembly structure of the battery cell can also be input to the input unit 150, and the electrode number calculating unit 160 can more accurately calculate the number of electrodes of the battery cell from the structure and number of electrode assemblies.

The defect determining unit 140 may determine the defect of the battery cell according to the derived relative lower limit reference value. At this time, it is possible to determine whether the battery cells are defective by comparing the capacity of each battery cell with a relative lower reference value. Specifically, when the capacity of each of the battery cells is less than the relative lower limit reference value, the corresponding battery cell may be determined as defective, and the battery cell determined as defective may be subjected to a separate separation process later because of poor productability.

On the other hand, the system of the present invention may further include a storage unit 170, the storage unit 170, the calculated capacity of the battery cell, the calculated capacity representative value, the derived relative lower limit reference value, the number of input electrode assemblies, The calculated number of electrodes can be stored. The storage unit may be implemented in various forms, such as random access memory (RAM), read only memory (ROM), and flash memory.

As described above, in the electrode tab folding defect determination system of the battery cell according to the present invention, the failure determination condition can be applied relative to each lot, thereby minimizing the occurrence of defects other than the relative lower limit reference value according to the change in the representative capacity of each lot, and minimizing the existing good products. It is possible to remove defective products in the judgment area, so that more accurate defect determination can be made.

Hereinafter, a method for determining a defect in folding of an electrode tab of a battery cell according to an embodiment of the present invention will be described with reference to the drawings. 4 is a flowchart illustrating a method for determining a defect in folding of an electrode tab of a battery cell according to an embodiment of the present invention.

As illustrated in FIG. 4, the method for determining the electrode tab folding failure of a battery cell includes a step of calculating a capacity of the battery cell (S110), a step of calculating a representative value of the capacity of the battery cells per lot (S120), and a reference value of the relative lower limit of the battery cells per lot. Derivation step (S130) and may include the step of determining the battery cell as defective (S140). At this time, the electrode tab folding defect determination system of the battery cell according to the present invention may be applied, but is not limited thereto.

First, the step of calculating the capacity of the battery cell (S110) may be a step of calculating the capacity of a plurality of battery cells constituting a lot. The capacity of the plurality of battery cells can be calculated by measuring the open voltage and discharge voltage.

Subsequently, the step of calculating the representative capacity of the battery cell (S120) may be a step of calculating a representative value of the capacity of the plurality of battery cells calculated in the step of calculating the capacity of the battery cell (S110). At this time, the representative capacity value may be an average value for the capacity of the battery cell, a median number or a mode number according to the capacity distribution, and can be freely selected as a desired representative value according to a required capacity criterion.

Thereafter, the step of deriving the relative lower limit reference value (S130) may be a step of deriving the relative lower limit reference value for the electrode tab folding of the battery cell from the calculated capacity representative value. The relative lower limit reference value refers to a reference value for determining a defect of the battery cell due to folding of the electrode tab.

At this time, the relative lower limit reference value is derived according to the position where the electrode tab folding occurs. First, the relative lower limit reference value for the electrode tab folding occurring therein based on the electrode assembly of the battery cell may be derived by Equation 1 below.

[Equation 1]

In Equation 1, R _li is a relative lower limit reference value, R _c is a representative capacity value, N _e is the number of electrodes of the battery cell, and N _t is the number of electrodes that do not react due to the occurrence of tap folding.

In addition, the relative lower limit reference value for the electrode tab folding occurring at the outermost point based on the electrode assembly of the battery cell may be derived by Equation 2 below.

[Equation 2]

In Equation 2, R _lo is a relative lower limit reference value, R _c is a capacity representative value, N _e is the number of electrodes of the battery cell, and N _t is the number of electrodes that do not react due to the occurrence of tap folding.

That is, the relative lower limit reference value is calculated by calculating the capacity of the electrode participating in the electrochemical reaction and applying the reference capacity relative lower limit criterion for each lot, and the number of electrodes participating in the reaction does not participate in the reaction due to folding or breaking of the electrode tap. It is the relative lower limit based on the representative capacity value excluding the expected number of electrodes. For example, if tap folding occurs on one of the electrodes (positive or negative), the number of non-reactive electrodes (N _t ) due to the occurrence of tab folding on one sheet will not respond because neither of the interacting negative or positive electrodes will react. Becomes Chapter 2, and by substituting this into Equation 1 or 2, the relative lower limit reference value can be derived. In addition, when two positive or negative tabs that are not adjacent to each other are folded, the number of electrodes (N _t ) that do not react due to the folding of the tab is four, and when both positive and negative tabs adjacent to each other are folded, the tab is folded. The number of non-reactive electrodes (N _t ) is three.

In addition, the relative lower limit reference values of Equations 1 and 2 are calculated based on the number of electrodes summing the numbers of both the anode and the cathode. On the other hand, by substituting the number of anodes or the number of cathodes of the battery cell, the relative lower limit reference values for the folding of the positive electrode tab or the negative electrode tab may be respectively derived, which will be described in detail later.

On the other hand, the electrode assembly of the battery cell used in the present invention, as shown in Figure 1, cathode / separator / anode / separator / C-type bi-cell (10, 13, 14) and anode / separator / cathode / of the cathode structure A type bicells 11 and 12 of the separator / anode structure may be alternately stacked, and C type bicells 13 and 14 may be disposed on both outermost ends. At this time, the uppermost electrode and the lowermost electrode, which are the outermost electrodes forming the outer surface of the electrode assembly, may have the same polarity. In the drawing, the cathode is illustrated as the outermost electrode, but is not limited thereto.

The above-described bicells are alternately superposed, and a folding separator sheet 20 is interposed in each overlapping portion. In addition, the folding separator sheet 20 has a unit length capable of wrapping a bicell, and is bent inward for each unit length, starting from the central bicell 10 and continuously extending to the outermost bicell 14, respectively. The structure surrounding the cell may be interposed in the overlapping portion of the bicell. The distal end of the folding separator sheet 20 may be finished by heat-sealing or attaching an adhesive tape 25 or the like. Subsequently, the electrode assembly may be manufactured through a battery pack assembly process for assembling the battery case into a finished battery cell.

Recently, due to the high-loading of the battery, high-loading of raw materials and minimization of subsidiary materials is inevitable due to slim type or various design trends, which causes defects such as electrode tab folding (F) as shown in FIG. 2 in the battery pack assembly process. This occurs, and in particular, in the process of assembling the electrode assembly of the bi-cell structure, the risk that the above-described defect occurs is increased. However, in the related art, there has been a difficulty in sorting out the electrode tab folding, which is a defect that occurs in the battery pack assembly process. Thus, the method for determining the electrode tab folding failure of a battery cell according to the present invention may be usefully applied to a battery cell having a bicell structure, but is not limited thereto, and may also be applied to a battery cell having a full cell structure.

Meanwhile, before the step of deriving the relative lower limit reference value (S130), a step (S150) of calculating the number of electrodes of the battery cell may be performed, and the relative lower limit reference value may be derived from the calculated electrode number and capacity representative value. The number of electrodes means the number of anodes or the number of cathodes, or the number of both anodes and cathodes.

For example, step S150 of calculating the number of electrodes of a battery cell including electrode assemblies alternately stacked of C-type bicells and A-type bicells shown in FIG. 1 calculates the number of C-type bicells. And calculating the number of electrodes of the battery cell from the number of C-type bicells. Here, the number of C-type bicells may be derived by Equation 3 below.

[Equation 3]

In Equation 3, N _c is the number of C-type bicells, and N _b is the total number of bicells in the electrode assembly.

In addition, the number of electrodes of the battery cell may be derived by Equation 4 below.

[Equation 4]

In Equation 4, N _e is the number of electrodes of the battery cell, N _c is the number of C-type bicells.

In addition, Equation 4 calculates the number of electrodes of both the positive electrode and the negative electrode, and may calculate only the number of positive electrodes or the number of negative electrodes. Specifically, the number of anodes may be calculated by Equation 5 below, and the number of cathodes may be calculated by Equation 6 below. This is limited to the case where the uppermost electrode and the lowermost electrode, which are the outermost electrodes forming the outer surface of the electrode assembly, are cathodes, as shown in FIG. 1.

[Equation 5]

In Equation 5, N ' _e is the number of anodes of the battery cell, and N _c is the number of C-type bicells.

[Equation 6]

In Equation 6, N '' _e is the number of the negative electrode of the battery cell, N _c is the number of the C-type bi-cell.

By substituting the number of the negative electrodes of the battery cells in Equations 1 and 2, respectively, the relative lower limit reference values for the inner or outermost negative electrode tab folding can be derived, respectively. In this case, the number of electrodes N _{t that} do not react due to the occurrence of tap folding may be substituted by the number of cathodes that do not react due to the occurrence of tap folding, that is, the number of cathodes where tap folding occurs.

On the other hand, the relative lower limit reference value for the positive electrode tab folding, which occurs in the interior of the battery cell as a reference, can be derived by substituting the number of positive electrodes derived by Equation 5 into Equation 7 below.

[Equation 7]

In Equation 7, R ' _li is a relative lower limit reference value, R _c is a capacity representative value, N' _e is the number of anodes in the battery cell, and N ' _t is the number of anodes that do not react due to the occurrence of tap folding.

On the other hand, in the case of a battery cell including an electrode assembly in which a full cell of a positive electrode / separator / negative electrode structure is alternately stacked, the number of electrodes is equal to the number of full cells of the electrode assembly, as the positive and negative electrodes are included one by one. Therefore, it can be calculated simply.

Finally, the step of determining the battery cell as defective (S140) may be a step of determining a battery cell having a capacity lower than the relative lower limit reference value as an electrode tab folding failure. At this time, the capacity of the battery cell calculated in the step of calculating the capacity of the battery cell (S110) is compared with the reference value of the relative lower limit derived in the step (S130) of deriving the relative lower limit reference value of each battery cell to determine the failure of folding of the electrode tab of the battery cell. can do. Specifically, when the capacity of the battery cell is less than the relative lower limit reference value, it may be determined as an electrode tab folding failure (S141), and when the relative capacity is higher than the relative lower limit reference value, it may be determined as normal (S142).

As described above, the method for determining the electrode tab folding failure of the battery cell according to the present invention can derive a relative lower reference value according to the design / structural characteristics of the electrode assembly, and the failure such as electrode tab folding occurring inside or outside the electrode assembly It is possible to calculate the capacity reduction level according to, it is possible to discriminate defective products according to the folding of the electrode tabs, thereby improving the ability to discriminate defective products.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited by the following examples.

[Example 1]

The relative lower limit reference values of lot A (17,130 battery cells, C-type bi-cell / A-type bi-cell / C-type bi-cell / A-type bi-cell / C-type bi-cell structure) were derived, and Equation 1 was used. , It was calculated based on the cathode. In addition, R _c is the median number according to the capacity distribution, and N _t is 1, which is the number of cathodes where tap folding occurs. In addition, the number of cathodes of the battery cells was calculated using Equations 3 and 6. The dose histogram of Lot A is shown in FIG. 5. As can be seen in Figure 5, the derived capacity relative lower limit reference value (R _li ) is 6,125mAh, and the battery cell (D) whose capacity is less than the relative lower limit reference value was determined as electrode tab folding failure.

[Example 2]

A reference value for the lower limit of capacity of lot B (28,701 battery cells, C type bicell / A type bicell / C type bicell / A type bicell / C type bicell structure) was derived, wherein Equations 1 and 2 were obtained. Each was used and calculated based on the cathode. In addition, R _c is the median number according to the capacity distribution, and N _t is 1, which is the number of cathodes where tap folding occurs. In addition, the number of cathodes of the battery cells was calculated using Equations 3 and 6. The dose histogram of Lot B is shown in Figure 6. As can be seen in FIG. 6, the relative value of the lower limit of the capacity for electrode tab folding, R _li , which is generated internally based on the electrode assembly is 56,741 mAh, and the lower limit of the capacity for electrode tab folding that occurs at the outermost side. (R _lo ) is 57,686mAh, and the battery cell (D ′) having a capacity of less than R _lo was determined to be the outermost electrode tab folding failure.

Although described above with reference to the preferred embodiment of the present invention, those skilled in the art or those skilled in the art will depart from the spirit and technical scope of the invention described in the claims below. It will be understood that various modifications and changes can be made to the present invention without departing from the scope.

Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

110: capacity calculator
120: capacity representative value calculation unit
130: relative lower limit reference value calculator
140: defective discrimination unit
150: input unit
160: electrode number calculation unit
170: storage unit

Claims (15)

Calculating a capacity of a plurality of battery cells constituting a lot;
Calculating a capacity representative value for the plurality of battery cells constituting the lot;
Deriving a relative lower limit reference value for folding of the electrode tab of the battery cell from the representative capacity value; And
And determining that the battery cell exhibiting a capacity below the relative lower limit reference value is an electrode tab folding failure. According to claim 1,
In the calculating of the representative capacity value, the representative capacity value is an average value of the capacity, the median or the mode of the electrode tab folding failure determination method of the battery cell. According to claim 1,
In the step of deriving the relative lower limit reference value,
The method for determining the electrode tab folding defect of the battery cell, which is derived by the following Equation 1, is a reference value of the relative lower limit for the electrode tab folding generated internally based on the electrode assembly of the battery cell.
[Equation 1]

In Equation 1, R _li is the relative lower limit reference value, R _c is the capacity representative value, N _e is the number of electrodes of the battery cell, N _t is the number of electrodes that do not react due to the tab folding. According to claim 1,
In the step of deriving the relative lower limit reference value,
The relative lower reference value for the electrode tab folding occurring at the outermost point based on the electrode assembly of the battery cell is a method for determining the electrode tab folding failure of the battery cell derived by Equation 2 below.
[Equation 2]

In Equation 2, R _lo is the relative lower limit reference value, R _c is the capacity representative value, N _e is the number of electrodes of the battery cell, and N _t is the number of electrodes that do not react due to the occurrence of the tab folding. According to claim 1,
The method of determining the electrode tab folding failure of the battery cell, further comprising calculating the number of electrodes of the battery cell before the step of deriving the relative lower limit reference value. The method of claim 5,
The number of electrodes is the number of anodes or the number of cathodes, or the number of positive and negative electrodes. The method of claim 5,
The electrode assembly of the battery cell is a cathode / separator / anode / separator / cathode structured C type bicell and an anode / separator / cathode / separator / anode structured A type bicell alternately stacked, respectively at the outermost both ends. Method for determining defective electrode tab folding of a battery cell having a structure in which a C type bicell is disposed. The method of claim 7,
The step of calculating the number of electrodes of the battery cell,
Calculating the number of C-type bicells; And calculating the number of electrodes of the battery cell from the number of the C-type bicells. The method of claim 8,
The number of C-type bi-cells is a method for determining a defect in electrode tab folding of a battery cell derived by Equation 3 below.
[Equation 3]

In Equation 3, N _c is the number of C-type bicells, and N _b is the total number of bicells in the electrode assembly. The method of claim 8,
The number of electrodes of the battery cell is a method for determining the electrode tab folding failure of the battery cell derived by Equation 4 below.
[Equation 4]

In Equation 4, N _e is the number of electrodes of the battery cell, N _c is the number of C-type bicells. According to claim 1,
A method of determining an electrode tab folding defect of a battery cell having the same polarity between the topmost layer electrode and the bottommost layer electrode, which are the outermost electrodes forming the outer surface of the electrode assembly of the battery cell. A capacity calculating unit for calculating the capacity of a plurality of battery cells constituting a lot;
A capacity representative value calculator for calculating a capacity representative value for the plurality of battery cells constituting the lot;
A relative lower limit reference value deriving unit deriving a relative lower limit reference value for folding of the electrode tab of the battery cell from the representative capacity value; And
And a discrimination unit for discriminating the battery cell, which indicates a capacity of less than the derived relative lower limit reference value, as an electrode tab folding failure. The method of claim 12,
The battery cell electrode tab folding failure determination system further comprising an input unit for receiving the number of the electrode assembly of the battery cell. The method of claim 12,
The electrode tab folding failure discrimination system of the battery cell further comprising an electrode number calculating unit for calculating the number of electrodes of the battery cell. The method according to any one of claims 12 to 14,
Discrimination of electrode tab folding failure of the battery cell further comprising a storage unit for storing the calculated capacity of the battery cell, the calculated capacity representative value, the derived relative lower limit reference value, the number of input electrode assemblies, and the calculated number of electrodes. system.

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