Patent Publication Number: US-2023160967-A1

Title: Inspection equipment for inspecting secondary battery cell

Description:
TECHNICAL FIELD 
     The present disclosure relates to an inspection system for inspecting a secondary battery cell, particularly a pouch-type secondary battery cell. 
     BACKGROUND 
     Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted as prior art by inclusion in this section. As the use of fossil fuels has caused economic and environmental problems, the interest in and demand for new renewable energy has surged. At the same time, the needs for secondary batteries capable of storing new renewable energy are also increasing. In particular, lithium secondary batteries are widely used as core parts of portable electronic devices, energy storage systems (ESSs) and electric vehicles, since they have high energy density, long life and low self-discharge rate. There are three types of the lithium secondary batteries mainly used, including: a prismatic battery, a polymer battery and a cylindrical battery. The polymer battery is also called as a pouch-type secondary battery because a stack of electrodes is wrapped with an aluminum thin film (which is usually referred to as a pouch). Since the polymer battery can be made thin and light, the use thereof continues to increase. 
     After manufactured, the pouch-type secondary battery needs to be inspected on whether there is a manufacturing defect. Defects to be inspected include not only external characteristics, such as the thickness and shape of the secondary battery, but also electrical characteristics of the secondary battery. In order to efficiently and accurately inspect manufactured secondary battery cells, conventionally, various inspection apparatuses, such as an insulation inspection apparatus of Prior Art Document 1, an OCV/IR inspection apparatus of Prior Art Document 2, and an electrode tab inspection apparatus of Prior Art Document 3, have been proposed. However, conducting inspections on the manufactured secondary battery cells for various items is followed by spending a lot of money and time. 
     (Patent Document 1) (Prior Art Document 1) Korean Patent Publication No. 10-1487496;
     Method and apparatus for checking insulation of pouch-type secondary battery   (Patent Document 2) (Prior Art Document 2) Korean Patent Publication No. 10-1084807;   Method of detecting IR/OCV of secondary battery and equipment for the method   (Patent Document 3) (Prior Art Document 3) Korean Patent Publication No. 10-1874281;   System for producing electrodes of battery   

     SUMMARY 
     In view of the foregoing, the present disclosure provides a secondary battery inspection system that can quickly and accurately perform various inspections of secondary batteries and various processes related thereto and thus can improve the inspection throughput for the secondary batteries. 
     An inspection system for inspecting a secondary battery cell according to an embodiment of the present disclosure is disclosed. An example inspection system may include a thickness measurement unit, an electrical characteristics measurement unit, a print processing unit, a tab cutting unit, a mass measurement unit, a tab inspection unit and a defect selection unit. The thickness measurement unit may measure the thickness of each of a plurality of secondary battery cells. The electrical characteristic measurement unit may measure electrical characteristics of a corresponding secondary battery cell using electrode tabs of each of the plurality of secondary battery cells. The print processing unit may include a data printer and a data verification unit. The data printer may print information about each of the plurality of secondary battery cells on a surface of a corresponding secondary battery cell. The data verification unit may verify the printed information. The tab cutting unit may cut the electrode tabs of each of the plurality of secondary battery cells to a predetermined size. The mass measurement unit may measure the mass of each of the plurality of secondary battery cells. The tab inspection unit may obtain a cut shapes of the electrode tabs of each of the plurality of secondary battery cells. The defect selection unit may include a plurality of magazines and a cell transferer. Each of the plurality of magazines may store one or more secondary battery cells. The cell transferer may select some defective secondary battery cells and transfer the selected secondary battery cells to a corresponding magazine among the plurality of magazines. The thickness measurement unit, the electrical characteristics measurement unit, the print processing unit, the tab cutting unit, the mass measurement unit, the tab inspection unit and the defect selection unit may be arranged in series. In this regard, the plurality of secondary battery cells may be inspected while being transferred in line within the inspection system. 
     In some examples, the inspection system may further include a control unit. The control unit may be configured to control an in-line transfer of the plurality of secondary battery cells. Also, the control unit may be configured to control operations of the thickness measurement unit, the electrical characteristics measurement unit, the print processing unit, the tab cutting unit, the mass measurement unit, the tab inspection unit and the defect selection unit, and to process data from the thickness measurement unit, the electrical characteristics measurement unit, the mass measurement unit and the tab inspection unit. In some examples, the inspection system may further include a cell supply and retrieval unit. The cell supply and retrieval unit may unload the plurality of secondary battery cells from a cell tray on which the plurality of secondary battery cells are loaded, move the cell tray, and load, onto the cell tray, the secondary battery cells having not been selected by the defect selection unit. 
     In some examples, the thickness measurement unit includes a pressing plate for pressing a secondary battery cell, and may measure the thickness of the secondary battery cell by measuring a plurality of points on a surface of the pressing plate in contact with the secondary battery cell. The thickness measurement unit may include a linear variable differential transformer (LVDT). 
     In some examples, the electrical characteristic measurement unit may include: an open circuit voltage/impedance reactance (OCV/IR) measurement unit, an insulation voltage measurement unit that measures an insulation voltage of a secondary battery cell by contacting sensing grippers with an anode tab and a terrace of the secondary battery cell, and an insulation resistance measurement unit that measures an insulation resistance of the secondary battery cell by contacting the sensing grippers with a cathode tab and the terrace of the secondary battery cell. 
     In some examples, the data printer of the print processing unit may include a plurality of print headers. Each of the plurality of print headers may print information about a secondary battery cell on the corresponding secondary battery cell. In some examples, the data verification unit of the print processing unit may include an optical reader configured to read the printed information. The optical reader may be inclined at 60 degrees with respect to a transfer direction of the secondary battery cell. 
     In some examples, the tab cutting unit may include an upper cutter and a lower cutter that are replaceably fixed. The upper cutter and the lower cutter may have cutting blades at two facing edges, respectively. In some examples, the tab cutting unit may further include an air blower provided in at least one of a region where the upper cutter is fixed and a region where the lower cutter is fixed. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative embodiments and features described above, further embodiments and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the present disclosure will be described in detail with reference to the accompanying drawings. Understanding that these drawings depict only several examples in accordance with the disclosure and are, therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings, in which: 
         FIG.  1    is a schematic block diagram illustrating a configuration of an inspection system according to some embodiments of the present disclosure; 
         FIG.  2    is a perspective view illustrating a thickness measurement apparatus according to an embodiment of the present disclosure; 
         FIG.  3    is a perspective view illustrating an OCV/IR measurement apparatus according to an embodiment of the present disclosure; 
         FIG.  4    is a perspective view illustrating an insulation voltage measurement apparatus according to an embodiment of the present disclosure; 
         FIG.  5    is a perspective view illustrating an insulation resistance measurement apparatus according to an embodiment of the present disclosure; 
         FIG.  6    is a perspective view illustrating a data printer according to an embodiment of the present disclosure; 
         FIG.  7 A  is a perspective view illustrating a data verification apparatus according to an embodiment of the present disclosure, and  FIG.  7 B  is an enlarged partial view of an optical reader of the data verification apparatus; 
         FIG.  8    is a perspective view illustrating a tab cutting apparatus according to an embodiment of the present disclosure; 
         FIG.  9    is a perspective view illustrating a mass inspection apparatus according to an embodiment of the present disclosure; 
         FIG.  10    is a perspective view illustrating a tab inspection apparatus according to an embodiment of the present disclosure; 
         FIG.  11    is a perspective view illustrating a defect selection apparatus according to an embodiment of the present disclosure; and 
         FIG.  12    is a perspective view illustrating an example of a secondary battery cell. 
     
    
    
     DETAILED DESCRIPTION 
     The terms used herein are used only to describe specific examples, but do not intend to limit the present disclosure. A singular expression includes a plural expression unless it is clearly construed in a different way in the context. All terms including technical and scientific terms used herein have the same meaning as commonly understood by a person with ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. In some cases, even terms defined in the present disclosure should not be interpreted as excluding embodiments of the present disclosure. 
     The foregoing features and other features of the present disclosure will be sufficiently apparent from the following descriptions with reference to the accompanying drawings. These drawings merely illustrate several embodiments in accordance with the present disclosure. Therefore, they should not be understood as limiting the present disclosure. The present disclosure will be described in more detail with reference to the accompanying drawings. 
     The present disclosure relates, inter alia, to an inspection system for inspecting a secondary battery cell, a method for controlling the same and a computer-readable storage medium storing a program. The inspection system according to the present disclosure may be configured to inspect various manufacturing characteristics of a secondary battery cell. Characteristics to be inspected by the inspection system according to the present disclosure include, for example, external characteristics regarding the shapes of electrode tabs, a terrace and a body of the secondary battery cell, physical characteristics such as the thickness, mass and strength of the secondary battery cell, and electrical characteristics such as various resistances, currents, voltages and capacitances of the secondary battery cell.  FIG.  12    is a perspective view illustrating an example of a secondary battery cell to be inspected by the inspection system. 
     As shown in  FIG.  12   , a secondary battery cell  1200  is composed of an electrode assembly  1210  and a pouch case  1220 . 
     Electrode assembly  1210  may be a stack-type electrode assembly in which a plurality of anode and cathode plates cut into units of a predetermined size is sequentially stacked with a separator interposed therebetween. An anode tab  1230  and a cathode tab  1240  of electrode assembly  1210  may oppose each other to be exposed at both sides of pouch case  1220 . In secondary battery cell  1200  of another embodiment, anode tab  1230  and cathode tab  1240  of electrode assembly  1210  may be exposed at the same side. Hereafter, for the convenience of description, anode tab  1230  and cathode tab  1240  may be collectively referred to as electrode tabs. 
     Pouch case  1220  may be configured to accommodate electrode assembly  1210  and an electrolyte and may be sealed at the periphery thereof. The periphery of pouch case  1220   may be referred to as a sealing portion, and a portion of pouch case  1220  that corresponds to a region where electrode assembly  1210  and the electrolyte are accommodated may be referred to as a body. Also, in pouch case  1220 , the sealing portion on both sides of pouch case  1220  where anode tab  1230  and cathode tab  1240  are not disposed may be referred to as a terrace  1250 . Before folding terrace  1250  of secondary battery cell  1200 , it is sealed along the periphery of pouch case  1220  after accommodating electrode assembly  1210  and the electrolyte, and then is cut to a predetermined size. 
       FIG.  1    is a schematic block diagram illustrating a configuration of an inspection system  100  according to some embodiments of the present disclosure. As shown in  FIG.  1   , inspection system  100  includes a cell supply and retrieval unit  110 , a control unit  120 , a thickness measurement unit  130 , an electrical characteristic measurement unit  140 , a print processing unit  150 , a tab cutting unit  160 , a mass measurement unit  170 , a tab inspection unit  180  and a defect selection unit  190 . Thickness measurement unit  130 , electrical characteristic measurement unit  140 , print processing unit  150 , tab cutting unit  160 , mass measurement unit  170  and tab inspection unit  180  are examples of an inspection unit. Accordingly, components  130 ,  140 ,  150 ,  160 ,  170  and  180  of the inspection unit can be arranged in a different order from the order shown in  FIG.  1    without departing from the scope of the spirit of the present disclosure according to a required embodiment, for example, a required inspection order. Also, one or more components of the inspection unit can be combined, one component can be divided into one or more components, or one or more components can be omitted according to a required embodiment. 
     Secondary battery cells to be inspected in inspection system  100  are transferred in line. Accordingly, components  130 ,  140 ,  150 ,  160 ,  170  and  180  of the inspection unit of inspection system  100  and defect selection unit  190  are arranged in series. That is, the secondary battery cells are supplied into the inspection unit and sequentially inspected according to the arrangement order of components  130 ,  140 ,  150 ,  160 ,  170  and  180 , and the inspected secondary battery cells are supplied into defect selection unit  190 . Hereafter, for clarity of description, a process of inspecting secondary battery cells in the order shown in  FIG.  1    will be described. 
     Control unit  120  controls various operations in inspection system  100 , and receives and processes data. Accordingly, control unit  120  controls the in-line transfer of the plurality of secondary battery cells to be inspected and controls the respective operations of components  130 ,  140 ,  150 ,  160 ,  170  and  180  of the inspection unit and defect selection unit  190 , and may process data from some components, for example, thickness measurement unit  130 , electrical characteristic measurement unit  140 , mass measurement unit  170  and tab inspection unit  180 . The operation and process of control unit  120  will be described in more detail below. 
     Cell supply and retrieval unit  110  supplies the secondary battery cells into the inspection unit and collects the secondary battery cells from defect selection unit  190 . In some embodiments, cell supply and retrieval unit  110  includes a cell tray conveyor  112 , a cell unloader  113 , a cell transfer belt conveyor  114 , a cell transferer  115  and a cell loader  117 . Cell tray conveyor  112  is configured to transfer a cell tray capable of loading a plurality of secondary battery cells. When an operator of inspection system  100  supplies a cell tray for loading a plurality of secondary battery cells to an input port of cell tray conveyor  112 , cell tray conveyor  112  may transfer the supplied cell tray along a conveyor line. Cell unloader  113  may unload a plurality of secondary battery cells from the cell tray transferred by cell tray conveyor  112 , and put them down on cell transfer belt conveyor  114 . Cell unloader  113  may place the unloaded plurality of secondary battery cells on cell transfer belt conveyor  114  at a predetermined interval in a predetermined direction. Cell transferer  115  may transfer the plurality of secondary battery cells placed on cell transfer belt conveyor  114  from cell transfer belt conveyor  114  to thickness measurement unit  130 . 
     Thickness measurement unit  130  may be configured to measure the thickness of each of the plurality of secondary battery cells. In some examples, thickness measurement unit  130  is equipped with a plurality of measurement units connected in a line and thus may measure the thicknesses of the plurality of secondary battery cells in one measurement operation. In one embodiment, thickness measurement unit  130  may measure the thicknesses of four secondary battery cells in one measurement cycle. In some examples, thickness measurement unit  130  may include a pressing plate for pressing a body of a secondary battery cell in a vertical direction and a plurality of gauge pins for measuring a plurality of points on a surface of the pressing plate opposing a contact surface with the secondary battery cell. In some examples, each gauge pin may include a linear variable differential transformer (LVDT) that measures a linear distance difference. In some examples, thickness measurement unit  130  may determine the thickness of the secondary battery cell by measuring an average of a plurality of values obtained from the plurality of points. In some other examples, thickness measurement unit  130  may calculate the thickness of the cell by calculating and using values such as deviation and dispersion of a plurality of values obtained from a specific point (e.g., a center point). A specific embodiment of thickness measurement unit  130  will be described in more detail with reference to  FIG.  2   . 
     Electrical characteristic measurement unit  140  measures electrical characteristics of a secondary battery cell. In some embodiments, electrical characteristic measurement unit  140  may include an open circuit voltage/impedance reactance (OCV/IR) measurement unit  142 , an insulation voltage measurement unit  144  and an insulation resistance measurement unit  146 . Secondary battery cells may be sequentially transferred to OCV/IR measurement unit  142 , insulation voltage measurement unit  144  and insulation resistance measurement unit  146  so that a plurality of electrical characteristics of the secondary battery cells can be measured. Each of OCV/IR measurement unit  142 , insulation voltage measurement unit  144   and insulation resistance measurement unit  146  includes a plurality of measurement units for measuring corresponding electrical characteristics and thus can measure electrical characteristics of a plurality of secondary battery cells in one measurement cycle. In one embodiment, each of OCV/IR measurement unit  142 , insulation voltage measurement unit  144  and insulation resistance measurement unit  146  may measure two secondary battery cells in one measurement operation. 
     OCV/IR measurement unit  142  may measure a no-load potential and an internal impedance of the secondary battery cell. In some examples, OCV/IR measurement unit  142  may include sensing grippers and may perform a measurement by contacting the sensing gripper with two electrode tabs (i.e., an anode tab and a cathode tab) of the secondary battery cell. In some examples, a measurement may be performed when the contact of the sensing grippers of OCV/IR measurement unit  142  causes intentional damage the electrode tabs in order to apply an external resistance. A specific embodiment of OCV/IR measurement unit  142  will be described in more detail with reference to  FIG.  3   . 
     Insulation voltage measurement unit  144  may measure the insulation voltage of the secondary battery cell. The insulation voltage can be used to determine the internal state of the secondary battery and whether it is defective. In some examples, insulation voltage measurement unit  144  may include sensing grippers and may perform a measurement by contacting the sensing grippers with the anode tab and a terrace of the secondary battery cell. In some examples, the contact of the sensing grippers of insulation voltage measurement unit  144  may be performed without damaging the electrode tabs. A mechanical embodiment of insulation voltage measurement unit  144  will be described in more detail with reference to  FIG.  4   . 
     Insulation resistance measurement unit  146  may measure the insulation resistance of the secondary battery cell. The insulation resistance can be used to determine the internal state of the secondary battery and whether it is defective. In some examples, insulation resistance measurement unit  146  may include sensing grippers and may perform a measurement by contacting the sensing grippers with the cathode tab and the terrace of the secondary battery cell. In some examples, the contact of the sensing grippers of insulation resistance measurement unit  146  may be performed without damaging the electrode tabs. A specific embodiment of insulation resistance measurement unit  146  will be described in more detail with reference to  FIG.  5   . 
     The plurality of secondary battery cells whose electrical characteristics have been measured by electrical characteristic measurement unit  140  is transferred to print processing unit  150 . Print processing unit  150  may include a data printer  152  and a data verification unit  154 . Data printer  152  may print information about a secondary battery cell on a surface of the secondary battery cell, for example, a surface of a body of the secondary battery cell. The printed information may include at least some of information measured by thickness measurement unit  130  and electrical characteristic measurement unit  140 , and may take the form of text and/or encoded code such as quick response (QR) code and barcode. Data printer  152  may print information on a plurality of secondary battery cells at the same time by using a multi-head marking printer. In one embodiment, data printer  152  may perform printing on four secondary battery cells in one printing cycle by using a four-head marking printer. A specific embodiment of data printer  152  will be described in more detail with reference to  FIG.  6   . 
     Data verification unit  154  may verify whether printing is correctly performed by reading the data printed by print processing unit  150 . In some embodiments, data verification unit  154  may include an optical reader for reading the printed information. Since the secondary battery cells are transferred in line within inspection system  100 , the optical reader needs to read the information printed on the secondary battery cells being transferred. Accordingly, the optical reader is inclined at a predetermined angle with respect to a transfer direction of the secondary battery cells. According to the ISO standard documents and AIM guidelines, the optical reader is required to have a light source angle of 45 degrees. However, it was found that if the optical reader is set to the standard angle, data can be read only when the optical reader (light source or camera) is very close to the secondary battery cells, and it is difficult to apply the standard angle to the inspection system adopting an in-line process because diffused reflection occurs depending on material characteristics of the pouch. In the inline process, it is preferable to apply a predetermined angle higher than the standard angle according to the ISO standard documents and AIM guidelines. In one embodiment, the predetermined inclination angle of the optical reader may be, for example, about 60 degrees. A specific embodiment of data verification unit  154  will be described in more detail with reference to  FIG.  7   . 
     The plurality of secondary battery cells is transferred from print processing unit  150  to tab cutting unit  160 . Tab cutting unit  160  may cut the electrode tabs of each of the plurality of secondary battery cells to a predetermined size. In some examples, tab cutting unit  160  is equipped with a plurality of cutting units connected in a line and thus may cut the electrode tabs of the plurality of secondary battery cells in one cutting cycle. Also, tab cutting unit  160  may be equipped with at least one cutting unit for each of the cathode tab and the anode tab as required. In one embodiment, tab cutting unit  160  may include two cutting apparatuses for each of the anode tab and the cathode tab. In some examples, tab cutting unit  160  may include an upper cutter and a lower cutter that are replaceably fixed. In some examples, the upper cutter and the lower cutter may have cutting blades at two facing edges, respectively. When the life of any one blade ends, the upper cutter and/or the lower cutter may use the opposing blade of the upper cutter and/or the lower cutter. Accordingly, at least one of the upper cutter and the lower cutter may have a vertically symmetrical shape. Tab cutting unit  160  may further include an air blower provided in at least one of a region where the upper cutter is fixed and a region where the lower cutter is fixed. Tab cutting unit  160  may remove cutting residues attached to tab cutting unit  160  by using the air blower whenever a cutting operation is performed. A specific embodiment of tab cutting unit  160  will be described in more detail with reference to  FIG.  8   . 
     The plurality of secondary battery cells is transferred from tab cutting unit  160  to mass measurement unit  170 . Mass measurement unit  170  may measure the mass of each of the plurality of secondary battery cells. In some examples, mass measurement unit  170  may measure the mass of a secondary battery cell whose electrode tabs have been cut. In some examples, since the mass of the secondary battery cell may be measured differently depending on the direction and position of the secondary battery cell, mass measurement unit  170  may measure the secondary battery cell after aligning the direction and position. In some examples, mass measurement unit  170  is equipped with a plurality of measurement units connected in a line and thus may measure the mass of the plurality of secondary battery cells in one measurement cycle. In one embodiment, mass measurement unit  170  may measure the mass of two secondary battery cells in one measurement cycle. A specific embodiment of mass measurement unit  170  will be described in more detail with reference to  FIG.  9   . 
     Tab inspection unit  180  may obtain a cut shape of the electrode tabs of each of the plurality of secondary battery cells. Tab inspection unit  180  may perform a vision inspection on the length and shape of the electrode tabs cut by tab cutting unit  160 . A specific embodiment of tab inspection unit  180  will be described in more detail with reference to  FIG.  10   . 
     Defect selection unit  190  may select some defective secondary battery cells among the plurality of secondary battery cells and may transfer non-defective secondary battery cells to cell loader  117  of cell supply and retrieval unit  110 . In some examples, defect selection unit  190  may include a cell transferer  192  and a magazine set  194  including a plurality of magazines #1, #2,..., #k (k is a natural number). Each of the plurality of magazines #1, #2,..., #k of magazine set  194  may store one or more secondary battery cells. Cell transferer  192  may identify each of the plurality of secondary battery cells that have passed through the inspection unit  130 ,  140 ,  150 ,  160 ,  170  and  180  and may select some defective secondary battery cells among the identified plurality of secondary battery cells. Cell transferer  192  may transfer the selected secondary battery cells to a corresponding magazine of magazine set  194  and store them. In some examples, cell transferer  192  may identify the type of a defect of a secondary battery cell and may transfer the secondary battery cell to a predetermined magazine corresponding to the type of the defect. A specific embodiment of defect selection unit  190  will be described in more detail with reference to  FIG.  11   . 
     In some examples, cell loader  117  of cell supply and retrieval unit  110  may load the secondary battery cells, which have not been selected by defect selection unit  190 , onto the cell tray. Cell supply and retrieval unit  110  may operate to cause cell tray conveyor  112  to discharge the cell tray on which the non-defective secondary battery cells are loaded. 
     In some embodiments, control unit  120  may include a cell transfer control unit  122 , a data processing unit  124  and an inspection control unit  126 . Cell transfer control unit  122  may control a transfer of secondary battery cells throughout inspection system  100 . The transfer controlled by cell transfer control unit  122  includes not only the transfer of the secondary battery cells, but also the transfer of the cell tray by cell tray conveyor  112 . Further, the transfer controlled by cell transfer control unit  122  includes the transfer to cell supply and retrieval unit  110 , the transfer to components  130 ,  140 ,  150 ,  160 ,  170  and  180  of the inspection unit and the transfer to cell supply and retrieval unit  110  through defect selection unit  190 . Furthermore, the transfer controlled by cell transfer control unit  122  may include a continuous transfer that does not require synchronization, e.g., the transfer by cell transfer belt conveyor  114  as well as a control of synchronization throughout components  130 ,  140 ,  150 ,  160 ,  170  and  180  of the inspection unit. 
     Data processing unit  124  may receive data measured from thickness measurement unit  130 , OCV/IR measurement unit  142 , insulation voltage measurement unit  144  and insulation resistance measurement unit  146  of electrical characteristic measurement unit  140 , mass measurement unit  170  and tab inspection unit  180 , and may appropriately process the data if required. In one example, data processing unit  124  may encode data received from thickness measurement unit  130  and electrical characteristic measurement unit  140  (e.g., in the case of a barcode or QR code) or may perform other appropriate processes to produce data to be printed by data printer  150 . In another example, data processing unit  124  may determine whether a secondary battery cell is defective based on the data measured from thickness measurement unit  130 , OCV/IR measurement unit  142 , insulation voltage measurement unit  144  and insulation resistance measurement unit  146  of electrical characteristic measurement unit  140 , mass measurement unit  170  and tab inspection unit  180 . In this example, cell transferer  192  may identify a secondary battery cell and may determine whether the identified secondary battery cell is defective by obtaining a defect determination result made by data processing unit  124 . 
     Inspection control unit  126  may control the respective operations of components  130 ,  140 ,  150 ,  160 ,  170  and  180  of the inspection unit and defect selection unit  190 . Inspection control unit  126  may control measurement operations of thickness measurement unit  130 , OCV/IR measurement unit  142 , insulation voltage measurement unit  144  and insulation resistance measurement unit  146  of electrical characteristic measurement unit  140 , data verification unit  154 , mass measurement unit  170  and tab inspection unit  180 . Inspection control unit  126  may control a printing operation of data printer  152 , a cutting operation of tab cutting unit  160  and a cell transfer operation of cell transferer  192 . 
     As described above, inspection system  100  according to the present disclosure can perform various inspections, print inspection data and discharge defective cells in line and can adjust the throughput depending on operation cycle. Therefore, inspection system  100  can improve the inspection efficiency of secondary batteries. 
       FIG.  2    is a perspective view illustrating a thickness measurement apparatus  200  according to an embodiment of the present disclosure. Thickness measurement apparatus  200  is an example of thickness measurement unit  130  shown in  FIG.  1   . In  FIG.  2   , thickness measurement apparatus  200  is illustrated as having one measurement unit, but in another example, thickness measurement apparatus  200  may include a plurality of measurement units and measure the thickness of a plurality of secondary battery cells in one measurement operation. Thickness measurement apparatus  200  may include a main body  210 , a display  220 , a cell support  230 , a pressing plate  240 , a pressing plate driver  250 , a plurality of gauge pins  260  and a gauge pin driver  270 . Main body  210  may provide a space where the other components  220  to  270  of thickness measurement apparatus  200  are installed. Display  220  may display the measurement result of thickness of the secondary battery cells. Cell support  230  provides a placing surface on which a secondary battery cell to be inspected is placed. In some examples, thickness measurement apparatus  200  may be configured to adjust the position of the secondary battery cell placed on cell support  230 . 
     Pressing plate  200  may press or contact an upper surface of the secondary battery cell placed on cell support  230  at a predetermined pressure or less by an operation of pressing plate driver  250 . Thereafter, the plurality of gauge pins  260  may be operated by gauge pin driver  270  to measure a plurality of points on a surface of pressing plate  200  opposing a contact surface with the secondary battery cell. In one example, the plurality of gauge pins  260  may perform a measurement from at least five points, such as the center, upper left, lower left, upper right and lower right of the secondary battery cell, but the number of measurement points is not limited thereto. In some examples, each gauge pin  260  may include a linear variable differential transformer (LVDT) that is an electrical transformer for measuring a linear distance difference. In some examples, thickness measurement apparatus  200  may determine the thickness of the secondary battery cell by measuring an average of a plurality of values obtained from the plurality of points by the plurality of gauge pins  260 . In some other examples, thickness measurement apparatus  200  may calculate the thickness of the cell by calculating and using values such as deviation and dispersion of a plurality of values obtained from a specific point (e.g., a center point). 
       FIG.  3    is a perspective view illustrating an OCV/IR measurement apparatus  300  according to an embodiment of the present disclosure. OCV/IR measurement apparatus  300  is an example of OCV/IR measurement unit  142  shown in  FIG.  1   . OCV/IR measurement apparatus  300  may include two measurement units as shown in  FIG.  3   , and each unit performs the same function. OCV/IR measurement apparatus  300  may include a cell support  320 , a sensing gripper  330 , a sensing gripper driver  340  and a measuring instrument  350 . Measuring instrument  350  may be provided in a non-illustrated frame. Cell support  320  may be configured to place thereon a secondary battery cell to be inspected. When the secondary battery cell is placed, sensing gripper driver  340  may operate to cause sensing gripper  330  to contact electrode tabs of the secondary battery cell. Sensing gripper  330  may contact two electrode tabs (i.e., an anode tab and a cathode tab) of the secondary battery cell. The contact of sensing gripper  330  may cause intentional damage the electrode tabs of the secondary battery cell in order to apply an intentional external resistance during a measurement on the secondary battery cell. A value measured by the operation of OCV/IR measurement apparatus  300  may include values caused by DC power, such as an open circuit voltage (OCV) of the secondary battery cell, and values caused by AC power, such as impedance (Z) and reactance (X). The value measured by the operation of OCV/IR measurement apparatus  300  can be used to determine the internal state of the secondary battery and whether it is defective. Measuring instrument  350  may output a measurement value using a value measured by the contact between the secondary battery cell and sensing gripper  330 . In one embodiment, for example, the HIOKI BT3562 BATTERY HiTester may be used as measuring instrument  350 . 
       FIG.  4    is a perspective view illustrating an insulation voltage measurement apparatus  400  according to an embodiment of the present disclosure. Insulation voltage measurement apparatus  400  is an example of insulation voltage measurement unit  144  shown in  FIG.  1   . As shown in  FIG.  4   , insulation voltage measurement apparatus  400  may include two measurement units, and each unit performs the same function. Insulation voltage measurement apparatus  400  may include a cell support  420 , a sensing gripper  430 , a sensing gripper driver  440  and a measuring instrument  450 . Measuring instrument  450  may be provided in a non-illustrated frame. Cell support  420  may be configured to place thereon a secondary battery cell to be inspected. When the secondary battery cell is placed, sensing gripper driver  440  may operate to cause sensing gripper  430  to contact an anode tab and a terrace of the secondary battery cell (or another part of a pouch of the secondary battery cell). Sensing gripper  430  may contact the anode tab and the terrace of the secondary battery cell without any physical damage. Insulation voltage measurement apparatus  400  is configured to measure a voltage between two points contacted by sensing gripper  430 . If the measured value does not come out or is equal to or less than a predetermined value (e.g., equal to or less than 0.5 V), it may be considered normal. The value measured by the operation of insulation voltage measurement apparatus  400  can be used to determine the internal state of the secondary battery and whether it is defective. Measuring instrument  450  may output a measurement value using a value measured by the contact between the secondary battery cell and sensing gripper  430 . In one embodiment, for example, the HIOKI DM7275-03 PRECISION DC VOLTMETER may be used as measuring instrument  450 . 
       FIG.  5    is a perspective view illustrating an insulation resistance measurement apparatus  500  according to an embodiment of the present disclosure. Insulation resistance measurement apparatus  500  is an example of insulation resistance measurement unit  146  shown in  FIG.  1   . As shown in  FIG.  5   , insulation resistance measurement apparatus  500  may include two measurement units, and each unit performs the same function. Insulation resistance measurement apparatus  500  may include a cell support  520 , a sensing gripper  530 , a sensing gripper driver  540  and a measuring instrument  550 . Measuring instrument  550  may be provided in a non-illustrated frame. Cell support  520  may be configured to place thereon a secondary battery cell to be inspected. In some examples, when the secondary battery cell is placed, sensing gripper driver  540  may operate to cause sensing gripper  530  to contact a cathode tab and a terrace of the secondary battery cell (or another part of a pouch of the secondary battery). Sensing gripper  530  may contact the cathode tab and the terrace of the secondary battery cell without any physical damage. Insulation resistance measurement apparatus  500  is configured to measure a resistance between two points contacted by sensing gripper  530 . If the measured value does not come out or is equal to or more than a predetermined value (e.g., equal to or more than 100 MΩ to 200 MΩ), it may be considered normal. In some other examples, sensing gripper driver  540  may operate to cause sensing gripper  530  to contact two end surfaces of the terrace. In these examples, if a resistance value measured by insulation resistance measurement apparatus  500  is equal to or less than a predetermined value (e.g., equal to less than 0.5 Ω), it may be considered normal. The value measured by the operation of insulation resistance measurement apparatus  500  can be used to determine the internal state of the secondary battery and whether it is defective. Measuring instrument  550  may output a measurement value using a value measured by the contact between the secondary battery cell and sensing gripper  530 . In one embodiment, for example, the HIOKI ST5520-S INSULATION TESTER may be used as measuring instrument  550 . 
       FIG.  6    is a perspective view illustrating a data printer  600  according to an embodiment of the present disclosure. Data printer  600  is an example of data printer  152  shown in  FIG.  1   . As shown in  FIG.  6   , data printer  600  may include a main body  610 , an orthogonal robot  620 , a marking controller  630  and a multi-head marking printer  640 . Main body  610  may include a frame capable of supporting the other components  620  to  640  of data printer  600 . Orthogonal robot  620  may move multi-head marking printer  640  under the control of marking controller  630 . Marking controller  630  may control an operation of orthogonal robot  620  and an operation of multi-head marking printer  640 , and may be provided in a non-illustrated frame or fixed element. Multi-head marking printer  640  may include a plurality of cartridges, and may include a driver for moving each cartridge. Each cartridge may print information about a secondary battery cell on a surface of a body of the secondary battery cell. The printed information may take the form of text and/or encoded code such as QR code, data matrix code (DMC) and barcode. In this way, the multi-head marking printer can print information on a plurality of secondary battery cells at the same time. In one example, multi-head marking printer  640  may be a four-head marking printer, which may perform printing on four secondary battery cells in one printing cycle. In one embodiment, the MARK-O-PRINT X4JET may be used as multi-head marking printer  640 . In some additional examples, data printer  600  may further include an ink purge box (not shown). The ink purge box may accommodate ink residues discharged after multi-head marking printer  640  performs printing. 
       FIG.  7 A  is a perspective view illustrating a data verification apparatus  700  according to an embodiment of the present disclosure, and  FIG.  7 B  is an enlarged partial view of an optical reader  720  of data verification apparatus  700 . Data verification apparatus  700  is an example of data verification unit  154  shown in  FIG.  1   . A main body  710  may include a frame capable of supporting optical reader  720  of data verification apparatus  700 . For example, data verification apparatus  700  includes two optical readers  720  as shown in  FIG.  7 A , and each optical reader  720  performs the same function. Therefore, data verification apparatus  700  may verify data printed on two secondary battery cells in one measurement cycle. Each optical reader  720  may include an optical camera  730  and an optical lens  740  as shown in  FIG.  7 B , and may further include an illumination device and a display device which are not illustrated in  FIG.  7 B . Optical reader  720  may check whether data printed on a plurality of (e.g., two) secondary battery cells being transferred in line are correctly printed. For example, optical reader  720  may determine whether there is a defect in data printed on a surface of a secondary battery cell. Optical camera  730  of optical reader  720  may be inclined at a predetermined angle, for example, about 60 degrees with respect to a transfer direction of the secondary battery cell. In one embodiment, a C-Mount Vision Hawk camera (MV4000-13) may be used as optical camera  730  of optical reader  720 . 
       FIG.  8    is a perspective view illustrating a tab cutting apparatus  800  according to an embodiment of the present disclosure. Tab cutting apparatus  800  is an example of tab cutting unit  160  shown in  FIG.  1   . Accordingly, tab cutting apparatus  800  may cut an electrode tab, i.e., an anode tab or a cathode tab, of a transferred secondary battery cell to a predetermined size. As shown in  FIG.  8   , tab cutting apparatus  800  may include a main body  810 , a cell alignment unit  820 , a moving frame  830 , an upper cutter  835 , a fixing frame  840 , a lower cutter  845  and a moving frame driver  850 . Main body  810  includes a frame for arranging the other components  820  to  850  of tab cutting apparatus  800 . 
     Cell alignment unit  820  is configured to align the secondary battery cell before the electrode tab of the secondary battery cell is cut by tab cutting apparatus  800 . In some examples, the secondary battery cell may be placed on cell alignment unit  820  by a separate device such as a cell transferer (not shown), and may be aligned by cell alignment unit  820 . Moving frame  830  may include an upper cutter holder for holding upper cutter  835  and a guide bar for vertical movement. Fixing frame  840  may include a lower cutter holder for holding lower cutter  845 . In this way, upper cutter  835  and lower cutter  845  may be replaceably mounted on moving frame  830  and fixing frame  840 . In some examples, upper cutter  835  and lower cutter  845  may have cutting blades at two facing edges, respectively. Accordingly, upper cutter  835  and lower cutter  845  may be vertically symmetrical to each other. In some examples, a surface of upper cutter  835  in contact with moving frame  830  may be aligned a surface of lower cutter  845  in contact with fixing frame  840 . 
     In an additional example, tab cutting apparatus  800  may further include an air blower  860 . Air blower  860  may be formed at moving frame  830  as shown in  FIG.  8   , but is not limited thereto and may be formed at fixing frame  840 . Air blower  860  may remove cutting residues that may be attached to upper cutter  835  and/or lower cutter  845  when cutting is performed by tab cutting apparatus  800 . 
       FIG.  9    is a perspective view illustrating a mass inspection apparatus  900  according to an embodiment of the present disclosure. Mass inspection apparatus  900  is an example of mass measurement unit  170  shown in  FIG.  1   . As shown in  FIG.  9   , mass inspection apparatus  900  may include two measurement units, and each unit performs the same function. Mass inspection apparatus  900  may include a main body  910 , a cell alignment unit  920  and a mass meter  930 . Main body  910  may provide a space where the other components  920  to  930  of mass inspection apparatus  900  are installed, and may include a frame. Cell alignment unit  920  may be configured to place and align a secondary battery cell to be inspected. The alignment of the secondary battery cell may be based on the type of the secondary battery cell. In some examples, cell alignment unit  920  may perform alignment of the secondary battery cell independently of measurement by mass meter  930 . In some examples, the secondary battery cell may be placed on cell alignment unit  920  by a separate device such as a cell transferer (not shown). When the secondary battery cell is placed on cell alignment unit  920 , cell alignment unit  920  aligns the secondary battery cell while mass meter  930  measures the mass of the secondary battery cell. The mass measured by mass meter  930  may be displayed on a display unit (not shown). 
       FIG.  10    is a perspective view illustrating a tab inspection apparatus  1000  according to an embodiment of the present disclosure. Tab inspection apparatus  1000  is an example of tab inspection unit  180  shown in  FIG.  1   . Tab inspection apparatus  1000  may include a vision inspection unit  1020  and an illumination unit  1030 . Vision inspection unit  1020  of tab inspection apparatus  1000  may be provided in a non-illustrated frame. As shown in  FIG.  10   , two vision inspection units  1020  may be provided in main body  1010  corresponding to respective electrode tabs. In some examples, vision inspection unit  1020  may obtain image data of the electrode tabs of the secondary battery cell being transferred in line. In one embodiment, a shutter speed of vision inspection unit  1020  may be set at a predetermined interval (e.g., 1/120 second). Tab inspection apparatus  1000  may inspect the length and shape of the electrode tabs by using the image data of the electrode tabs. Illumination unit  1030  may be spaced apart from the secondary battery cell (i.e., electrode tabs) at a predetermined distance (e.g., 10 mm), and may provide a predetermined light when vision inspection unit  1020  obtains an image. 
       FIG.  11    is a perspective view illustrating a defect selection apparatus  1100  according to an embodiment of the present disclosure. Defect selection apparatus  1100  is an example of defect selection unit  180  shown in  FIG.  1   . Defect selection apparatus  1100  may include a cell transferer  1110  and a magazine set. The magazine set may include a plurality of magazines  1130 . Each magazine  1130  may store one or more secondary battery cells. Cell transferer  1110  may select a defective secondary battery cell and load the selected secondary battery cell into magazine  1130 . In some examples, cell transferer  1110  may transfer a secondary battery cell to predetermined magazine  1130  depending on the type of a defect of the secondary battery cell. 
     While certain example techniques have been described and shown herein using various methods and systems, it should be understood by those skilled in the art that various other modifications may be made, and equivalents may be substituted, without departing from claimed subject matter. Additionally, many modifications may be made to adapt a particular situation to the teachings of claimed subject matter without departing from the central concept described herein. Therefore, it is intended that claimed subject matter not be limited to the particular examples disclosed, but that such claimed subject matter also may include all implementations falling within the scope of the appended claims, and equivalents thereof. Throughout this document, the term “connected to” may be used to designate a connection or coupling of one element to another element and includes both an element being “directly connected to” another element and an element being “electronically connected to” another element via another element. Through the whole document, the term “on” that is used to designate a position of one element with respect to another element includes both a case that the one element is adjacent to the other element and a case that any other element exists between these two elements. Further, through the whole document, the term “comprises or includes” and/or “comprising or including” used in the document means that one or more other components, steps, operation and/or existence or addition of elements are not excluded in addition to the described components, steps, operation and/or elements unless context dictates otherwise. Through the whole document, the term “about or approximately” or “substantially” is intended to have meanings close to numerical values or ranges specified with an allowable error and intended to prevent accurate or absolute numerical values disclosed for understanding of the present disclosure from being illegally or unfairly used by any unconscionable third party. 
     The scope of the present disclosure is defined by the following claims rather than by the detailed description of the embodiment. It shall be understood that all modifications and embodiments conceived from the meaning and scope of the claims and their equivalents are included in the scope of the present disclosure.