Apparatus and method for inspecting lithium deposition in battery cells

Abstract

The device and method for testing lithium deposition in a battery cell according to an embodiment of the present invention has high stability and reliability by forming a magnetic field around a battery cell to be tested to induce eddy currents, and then comparing the impedance measurement value of the electric cell with standard data to detect the presence or absence of lithium deposition in the battery cell.

Description

[Technical field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0035169 filed with the Korean Intellectual Property Office on March 22, 2022, and Korean Patent Application No. 10-2023-0034950 filed with the Korean Intellectual Property Office on March 17, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to an apparatus and method for inspecting lithium deposition in a battery cell, and more particularly to an apparatus and method for inspecting lithium deposition in a battery cell for inspecting the presence or absence of lithium deposition inside a secondary battery cell by using eddy current. [Background technology]

[0003] As the depletion of fossil fuels increases the value of energy sources and concerns about environmental pollution grow, the demand for environmentally friendly alternative energy sources has become an essential factor for future life. In particular, as technological development and demand for mobile devices increases, the demand for secondary batteries as an energy source is also increasing rapidly.

[0004] Typically, in terms of battery shape, there is a high demand for square-type secondary batteries and pouch-type secondary batteries that are thin and can be applied to products such as mobile phones, and in terms of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries that have high energy density, discharge voltage, and output stability.

[0005] Among these, pouch-type lithium secondary batteries have a problem in that if local lithium deposition occurs within the battery, it may cause an internal short circuit, thereby reducing the safety of the battery.

[0006] For this reason, there is a demand for the development of technology to diagnose the presence or absence of lithium deposition in pouch-type lithium secondary batteries. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention to solve the above problems is to provide a highly reliable lithium deposition inspection device.

[0008] SUMMARY OF THE PRESENT EMBODIMENT In order to solve the above problems, an object of the present invention is to provide a highly stable and highly reliable method for inspecting lithium deposition. [Means for solving the problem]

[0009] In order to achieve the above object, according to an embodiment of the present invention, an apparatus for detecting the presence or absence of lithium deposition inside at least one battery cell using eddy currents includes an inspection unit including a first sensor that induces eddy currents in the battery cell and a second sensor that measures the impedance of the battery cell in which the eddy current is induced; and a control unit that determines the presence or absence of lithium deposition in the battery cell by comparing a measured impedance value measured by the second sensor with standard data, wherein the first sensor and the second sensor are provided in a form in which a coil is wound around a magnetized member, and the first sensor induces eddy currents in the battery cell by applying an alternating current of a predefined specific frequency to the coil to form a magnetic field, and the second sensor measures the impedance at the specific frequency for the battery cell.

[0010] The lithium deposition inspection device may further include a transport unit configured to transport the battery cell, which is externally inserted, to the inspection unit.

[0011] In this case, the first sensor may be located at an upper portion based on the conveying portion, the second sensor may be located at a lower portion based on the conveying portion, and the first sensor and the second sensor may be located on the same vertical line based on the conveying portion.

[0012] The specific frequency may be any one of values ​​from 3190 Hz to 3210 Hz.

[0013] The specific frequency may be any one of the values ​​from 3990 Hz to 4010 Hz.

[0014] Meanwhile, the standard data may be data verified in advance by measuring impedance at the specific frequency for a battery cell with or without lithium deposition.

[0015] In addition, the control unit may determine the presence or absence of lithium deposition in the battery cell measured by the second sensor by comparing a position of the measured value of the impedance of the battery cell measured by the second sensor on the complex plane with a position of the first crowd data and a position of the second crowd data based on a dividing line that divides the standard data represented on a complex plane into first crowd data and second crowd data, and the first crowd data may be at least one piece of data measured from a battery cell in which lithium is deposited, and the second crowd data may be at least one piece of data measured from a battery cell in which lithium is not deposited.

[0016] The battery cell may be a pouch-type lithium secondary battery cell.

[0017] The battery cell may be used in an energy storage system (ESS).

[0018] According to another embodiment of the present invention for achieving the above object, a method for inspecting the presence or absence of lithium deposition in at least one battery cell, including an inspection unit including a first sensor and a second sensor having coils wound around a magnetized member, includes a step of inducing eddy current in the battery cell by applying an alternating current of a predefined specific frequency to the coil of the first sensor to form a magnetic field, a step of measuring the impedance of the battery cell at the specific frequency using the second sensor, and a step of comparing the impedance measurement value measured by the second sensor with standard data to determine the presence or absence of lithium deposition in the battery cell.

[0019] The lithium deposition inspection method may further include a transport unit, and may further include the step of transporting the battery cell to the inspection unit.

[0020] In this case, the first sensor may be located at an upper portion based on the conveying portion, the second sensor may be located at a lower portion based on the conveying portion, and the first sensor and the second sensor may be located on the same vertical line based on the conveying portion.

[0021] The specific frequency may be any one of values ​​from 3190 Hz to 3210 Hz.

[0022] The specific frequency may be any one of the values ​​from 3990 Hz to 4010 Hz.

[0023] Meanwhile, the standard data may be data verified in advance by measuring impedance at the specific frequency for a battery cell with or without lithium deposition.

[0024] In addition, the step of determining whether or not lithium deposition occurs in the battery cell includes a step of determining whether or not lithium deposition occurs in the battery cell measured by the second sensor by comparing a position of the measured value of the impedance of the battery cell measured by the second sensor on the complex plane with a position of the first crowd data and a position of the second crowd data based on a dividing line that divides the standard data represented on a complex plane into first crowd data and second crowd data, and the first crowd data may be at least one piece of data measured from a battery cell in which lithium is deposited, and the second crowd data may be at least one piece of data measured from a battery cell in which lithium is not deposited.

[0025] The battery cell may be a pouch-type lithium secondary battery cell.

[0026] The battery cell may be used in an energy storage system (ESS). Effect of the Invention

[0027] The device and method for testing lithium deposition in a battery cell according to an embodiment of the present invention has high stability and reliability by forming a magnetic field around a battery cell to be tested to induce eddy currents, and then comparing the impedance measurement value of the electric cell with standard data to detect the presence or absence of lithium deposition in the battery cell. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a plan view of a lithium deposition inspection device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a configuration diagram of a lithium precipitation inspection device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a design diagram of an inspection section in a lithium deposition inspection device according to an embodiment of the present invention. [Figure 4] 4 is a cross-sectional view of a first sensor and a second sensor in a testing portion according to an embodiment of the present invention. [Diagram 5] 1 is a conceptual diagram for explaining the principle of eddy current induction in a battery cell according to an embodiment of the present invention. [Figure 6] FIG. 2 is a plan view of a transport section in a lithium deposition inspection device according to an embodiment of the present invention. [Figure 7] 1 is an image of a transfer section within a lithium deposition inspection device according to an embodiment of the present invention. [Figure 8] 1 is a graph showing impedance measurement of standard data when the frequency is 3200 Hz according to a first experimental example of the present invention. [Figure 9] 11 is a graph showing impedance measurement of standard data when the frequency is 4000 Hz according to a second experimental example of the present invention. [Figure 10] 1 is a graph showing impedance measurement of standard data when the frequency is 8000 Hz according to a comparative example of the present invention. [Figure 11]FIG. 2 is a flow chart of a lithium deposition inspection method according to an embodiment of the present invention. [Figure 12] 13 is an impedance measurement graph of standard data and experimental data when the frequency is 3200 Hz according to a third experimental example of the present invention. [Figure 13] 13 is an impedance measurement graph of standard data and experimental data when the frequency is 4000 Hz according to a fourth experimental example of the present invention. [Figure 14] 13 is an impedance measurement graph of standard data and experimental data when the frequency is 8000 Hz according to a fifth experimental example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention can be modified in various ways and can have various embodiments, and a specific embodiment will be described in detail in the detailed description with reference to the drawings. However, this is not intended to limit the present invention to the specific embodiment, and it should be understood that the present invention includes all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. In the description of each drawing, the same reference numerals are used for similar components.

[0030] Terms such as first, second, A, and B may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component, without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any one of multiple associated listed items.

[0031] When a component is referred to as being "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but there may be other components in between. On the other hand, when a component is referred to as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0032] The terms used in this application are merely for describing certain embodiments and are not intended to limit the present invention. Unless otherwise clearly stated by the context, the singular form includes the plural form. In this application, the terms "comprise" or "have" mean the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0033] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Commonly used and dictionary-defined terms should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as idealized or overly formal unless expressly defined in this application.

[0034] The lithium deposition inspection device according to an embodiment of the present invention can detect whether lithium is locally deposited in a certain region inside a battery cell by using eddy current. Here, the battery cell may be a pouch-type lithium secondary battery for ESS.

[0035] In general, lithium secondary batteries can be classified according to the structure of the electrode assembly, which has a positive electrode / separator / negative electrode structure. For example, lithium secondary batteries can be classified into a jelly roll (wound type) electrode assembly in which a long sheet-shaped positive electrode and negative electrode are wound with a separator interposed therebetween, a stack type electrode assembly in which a number of positive electrodes and negative electrodes cut into a predetermined size are stacked in sequence with a separator interposed therebetween, and a stack / folded type electrode assembly in which a bi-cell or full cell in which a predetermined unit of positive electrodes and negative electrodes are stacked with a separator interposed therebetween is wound.

[0036] Recently, pouch-type batteries, which have a structure in which a stack-type or stack / fold-type electrode assembly is built into a pouch-type battery case made of an aluminum laminate sheet, have been attracting much attention due to their low manufacturing cost, light weight, and easy shape modification, and their usage is also increasing.

[0037] In general, a pouch-type lithium secondary battery includes an electrode assembly, electrode taps extending from the electrode assembly, electrode leads welded to the electrode taps, and a battery case that houses the electrode assembly.

[0038] At this time, the electrode assembly is a power generating element in which positive and negative electrodes are sequentially stacked with a separator interposed therebetween, and has a stacked or stacked / folded structure. Also, an electrode tap is extended from each electrode plate of the electrode assembly, and an electrode lead may be electrically connected to each of the electrode taps extended from each electrode plate by welding.

[0039] Meanwhile, a portion of the battery case is exposed to the outside, and an insulating film may be attached to a portion of the upper and lower surfaces of the electrode lead to improve the sealing with the battery case and at the same time ensure electrical insulation.

[0040] Generally, a battery case is made of an aluminum laminate sheet, has a pouch shape as a whole, and provides a storage space for the electrode assembly. In the case of a stacked electrode assembly, the upper end of the inside of the battery case is spaced apart from the electrode assembly so that a number of positive electrode tabs and a number of negative electrode tabs can be connected together to electrode leads.

[0041] On the other hand, the safety of lithium secondary batteries may be compromised if lithium is precipitated in a certain region of the battery cell. Among these, pouch-type lithium secondary batteries have a disadvantage in that it is difficult to check from the outside whether lithium has been precipitated because the electrodes, electrode taps, and welded parts are housed inside the battery case as described above.

[0042] Hereinafter, a lithium precipitation detection device capable of easily determining whether or not lithium precipitation occurs inside a pouch-type secondary battery by using eddy current will be described in more detail with reference to the accompanying drawings.

[0043] FIG. 1 is a plan view of a lithium deposition inspection apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a lithium deposition inspection apparatus according to an embodiment of the present invention, and FIG. 3 is a design diagram of an inspection section in the lithium deposition inspection apparatus according to an embodiment of the present invention.

[0044] 1 to 3, the lithium deposition inspection device 100 may include an inspection unit 110, a transport unit 120, and a control unit .

[0045] The inspection unit 110 includes a first sensor 111 and a second sensor 112, and can measure the impedance at a specific frequency of the battery cell 200 in which an eddy current is induced.

[0046] The transfer unit 120 may transfer at least one test target battery cell 200, which is input from the outside, to the test unit 110 in order to test whether or not lithium deposition is present.

[0047] In addition, the control unit 130 controls the operations of the inspection unit 110 and the transport unit 120, and can determine whether or not lithium deposition occurs in the inspection target battery cell 200 based on the impedance measurement value obtained from the inspection unit 110.

[0048] FIG. 4 is a cross-sectional view of a first sensor and a second sensor in a testing portion according to an embodiment of the present invention.

[0049] Referring to FIG. 4, the inspection unit 110 may include a first sensor 111 and a second sensor 112. According to an embodiment, the first sensor 111 and the second sensor 112 may be formed in a structure in which a coil is wound around a magnetized member (not shown) having magnetism. In this case, the diameter of the coil may be 0.5 to 10 mm. For example, if the diameter of the coil is less than 0.5 mm, the impedance measurement value measured by the second sensor 112 described below may be low. Conversely, if the diameter of the coil is more than 10 mm, the impedance measurement value measured by the second sensor 112 may be noisy and may be less reliable. Therefore, in order to determine the presence or absence of lithium deposition inside the battery cell 200, the user may select an optimal coil diameter by appropriately adjusting the coil diameter within the above numerical range.

[0050] Also, the inspection unit 110 may further include a case C that encloses and protects the first sensor 111 and the second sensor 112. For example, the case C may be provided in the shape of a cylinder with one end closed and the other end open. In this case, the one end may be an end portion positioned close to the object to be inspected.

[0051] FIG. 5 is a conceptual diagram for explaining the principle of eddy current induction in a battery cell according to an embodiment of the present invention.

[0052] Referring to FIG. 5, the first sensor 111 may be a sensor for inducing an eddy current from the battery cell 200 to be inspected.

[0053] To explain this in more detail according to the embodiment, when an AC current of a specific frequency is applied to the coil by the control unit 130 described below, a magnetic field may be formed around the coil of the first sensor 111. For example, the specific frequency may be any one of a value from 3190 Hz to 3210 Hz, or any one of a value from 3990 Hz to 4010 Hz.

[0054] Thereafter, when the battery cell 200 to be inspected is positioned within the magnetic field region by the transport unit 120 described below, an induced electromotive force due to an electromagnetic induction phenomenon may be generated in the battery cell 200. As a result, an eddy current that interferes with the magnetic field may flow in the battery cell 200.

[0055] 3 and 4, the second sensor 112 may be located on a vertical line corresponding to the first sensor 111 with respect to the conveyer 120. In other words, the first sensor 111 and the second sensor 112 are located on the same vertical line with respect to the conveyer 120, but the first sensor 111 may be located on an upper side with respect to the conveyer 120, and the second sensor 112 may be located on a lower side with respect to the conveyer 120. As a result, the second sensor 112 may measure the impedance from the battery cell 200 in which an eddy current is induced by the first sensor 111. At this time, the eddy current may cause a difference in the measured value depending on the resistance in the measurement area.

[0056] Meanwhile, the inspection unit 110 may further include a first position adjustment member 113, a second position adjustment member 114, a third position adjustment member 117, and a fourth position adjustment member 118. Here, the first position adjustment member 113, the second position adjustment member 114, the third position adjustment member 117, and the fourth position adjustment member 118 may be configured to move the positions of the first sensor 111 and the second sensor 112.

[0057] More specifically, one side of the first position adjustment member 113 may be coupled to the first sensor 111 , and the other side may be coupled to a third position adjustment member 117 (described below) by a position fixing bolt 115 .

[0058] In addition, one side of the second position adjustment member 114 may be coupled to the second sensor 112 and the other side may be coupled to a third position adjustment member 117 by a position fixing bolt 116 .

[0059] Meanwhile, one side of the third position adjustment member 117 may be coupled to the first position adjustment member 113 and the second position adjustment member 114, respectively, and the other side may be coupled to a fourth position adjustment member 118 via a position fixing bolt 119, described below.

[0060] In this case, the first position adjustment member 113 and the second position adjustment member 114 may be coupled to one side of the third position adjustment member 117 at a predetermined distance.

[0061] The third position adjustment member 117 may include a sliding groove (not shown) of a predetermined length on one side for adjusting the positions of the first position adjustment member 113 and the second position adjustment member 114.

[0062] In other words, the third position adjustment member 117 may include a first sliding groove (not shown) at a portion where the third position adjustment member 117 is coupled to the first position adjustment member 113. Thus, the first position adjustment member may move vertically along the first sliding groove within the length range of the first sliding groove.

[0063] Also, the third position adjustment member 117 may include a second sliding groove (not shown) at a portion where the third position adjustment member 117 is coupled to the second position adjustment member 114. Thus, the second position adjustment member 114 may move vertically along the second sliding groove within the length range of the second sliding groove.

[0064] Therefore, the first position adjustment member 113 and the second position adjustment member 114 can be moved vertically along the first sliding groove and the second sliding groove of the third position adjustment member 117 under the control of the control unit 130 described later. In other words, the control unit 130 can adjust the first sensor 111 and the second sensor 112 to be closer to or farther away from the battery cell to be inspected by moving the first position adjustment member 113 and the second position adjustment member 114 vertically.

[0065] Furthermore, the first position adjustment member 113 and the second position adjustment member 114 can fix the vertical movement of the first sensor 111 and the second sensor 112 using position fixing bolts 115 and 116. According to an embodiment, after the user adjusts the positions of the first position adjustment member 113 and the second position adjustment member 114, the user can fix the movement of the first sensor 111 and the second sensor 112 by tightening the position fixing bolts 115 and 116 coupled to the third position adjustment member 117.

[0066] Meanwhile, the fourth position adjustment member 118 may be coupled to the third position adjustment member 117 by a position fixing bolt 119 .

[0067] More specifically, the fourth position adjustment member 118 may include a third sliding groove of a predetermined length for adjusting the position of the third position adjustment member 117. Thus, the third position adjustment member 117 can move horizontally along the third sliding groove within the length range of the third sliding groove.

[0068] Also, the fourth position adjustment member 118 may further include a position fixing bolt 119. Thus, a user can move the third position adjustment member 117 to a desired position via the third sliding groove, and then operate the position fixing bolt 119 to fix the third position adjustment member 117 to the fourth position adjustment member 118. Thus, the third position adjustment member 117 can fix the first sensor 111 and the second sensor 112 coupled to the third position adjustment member 117 against horizontal movement.

[0069] FIG. 6 is a plan view of a transfer section in a lithium deposition inspection apparatus according to an embodiment of the present invention, and FIG. 7 is an image of the transfer section in a lithium deposition inspection apparatus according to an embodiment of the present invention.

[0070] 6 and 7, the transfer unit 120 can transfer the electronic cell 200 inserted into the lithium deposition testing apparatus 100 according to an embodiment of the present invention toward the testing unit 110. In addition, the transfer unit 120 can transfer the electronic cell 200 after testing to an outlet.

[0071] While the inspection unit 110 measures the impedance of the battery cell to be inspected, the transport unit 120 can transport the following battery cell to the position where the battery cell to be inspected was previously located. This allows the following battery cell to have a predetermined inspection waiting time. After that, when the inspection of the battery cell is completed and the battery cell leaves the inspection area, the transport unit 120 can transport the following battery cell into the inspection area. This allows the inspection unit 110 to measure the impedance of the battery cell according to a specific frequency.

[0072] In addition, the transport unit 120 may be controlled by the control unit 130, which will be described later, so that the running speed of a specific battery cell in the inspection area is different from the moving speed of battery cells outside the inspection area. For example, the running speed of the battery cell to be inspected in the inspection area may be slower than the moving speed of battery cells located in areas other than the inspection area.

[0073] The transfer unit 120 may include a transfer die 121 extending from an input point of the battery cells to an output point, and transfer means 122, 123, and 124 for transferring the battery cells.

[0074] Here, the transfer die 121 may include a plurality of nests 126 in which the battery cells 200 are seated between one unit transfer section and an adjacent unit transfer section.

[0075] The nest 126 is a receiving groove that is dug inwardly to correspond to the shape of a battery cell on the transferring die 121, and the battery cell 200 can be seated therein. As a result, when the transferring unit 120 moves, the battery cell is seated in the nest and transferred from the input point to the inspection area, so that the battery cell can be aligned.

[0076] Meanwhile, the transfer means 122, 123, 124 may include a lifting unit 122 that lifts and lowers the battery cell from the transfer die 121, and a driving unit 124 that moves the lifting unit 122 in a transfer direction of the battery cell 200. In this case, the driving unit 124 may have various forms for moving the lifting unit 122.

[0077] The lifting unit 122 may be a cylinder that reciprocates up and down using hydraulic or pneumatic pressure.

[0078] The lifting unit 122 may be provided in the form of two narrow bars of a predetermined length extending in a direction parallel to the transfer direction of the battery cells 200. According to an embodiment, the lifting unit 122 may be disposed spaced apart above and below a center line parallel to the length direction of the transfer die 121 (the running direction of the battery cells).

[0079] The lifting unit 122 supports the battery cell 200 and can move in a transfer direction of the battery cell 200 together with the driving unit 124 as the driving unit 124 moves, thereby transferring the battery cell 200 .

[0080] According to an embodiment of the present invention, the lifting unit 122 may include one or more suction holes 123 for suctioning the battery cells 200. Here, the number of the suction holes 123 may be appropriately adjusted as necessary.

[0081] The lifting unit 122 may be extended and elevated by the driving unit 124 to pick up the battery cell 200 and adsorb the battery cell 200 .

[0082] The driving unit 124 may be located on a lower surface with respect to the transferring die 121. The driving unit 124 may pass through an opening 125 formed in the transferring die 121 and ascend to an upper portion of the transferring die 121 according to a control signal from a control unit 130 described below. Thereafter, the control unit 130 described below may fix the battery cell 200 to the elevating unit 122 by applying a vacuum to the suction holes 123.

[0083] The lithium deposition inspection device according to an embodiment of the present invention provides the lifting unit 122 including the suction holes 123, so that the vibration of the battery cell 200 during transportation is suppressed by the lifting unit 122, thereby preventing the battery cell 200 from being out of alignment or falling off the lifting unit 122. Therefore, the lithium deposition inspection device according to an embodiment of the present invention is capable of measuring a highly reliable impedance value even during transportation of the battery cell. However, the lithium deposition inspection device according to an embodiment of the present invention is not limited to the embodiment in which the battery cell 200 is sucked to the lifting unit 122 by applying a vacuum through the suction holes 123, and various forms in which the battery cell 200 can be fixed to the lifting unit 122 may be provided.

[0084] Meanwhile, the transport unit 120 of the lithium deposition testing apparatus according to an embodiment of the present invention includes a plurality of unit movement sections, and the transport means 122, 123, and 124 can reciprocate through one unit movement section or two or more unit movement sections.

[0085] For example, the transporting means 122, 123, 124 may pick up a battery cell placed at the start point of a unit movement section and transport it to the start point of an adjacent unit movement section. After that, the transporting means 122, 123, 124 that has completed transporting the battery cell 200 in the unit movement section may return to the start point of the unit movement section. In other words, the transporting unit 120 may transport a plurality of battery cells 200 in sequence by repeating the above process.

[0086] To explain in detail the process in which the battery cell 200 to be inspected is inserted into and removed from the lithium deposition inspection device of the present invention, when the battery cell 200 is inserted into the nest 126 located at the insertion port, the driving unit 124 can operate the lifting unit 122. As a result, the lifting unit 122 can pass through the opening 125 of the transfer die 121 and move upward to the top of the transfer die 121.

[0087] Thereafter, the lifting unit 122 raised to the top of the transferring die 121 can adsorb the battery cell 200 seated on the nest 126. This prevents the battery cell 200 from falling off the lifting unit 122 or becoming out of alignment during transfer, and minimizes movement due to vibration during inspection. The method of the lifting unit 122 adsorbing the battery cell 200 is not limited to the above embodiment as long as it can minimize movement of the battery cell 200 during transfer.

[0088] The lifting portion 122 is coupled to the driving portion 124 and can be reciprocated by the driving of the driving portion 124 .

[0089] The lifting unit 122, which has adsorbed the battery cell 200, may move horizontally in a direction in which the inspection unit 110 is installed, while remaining elevated, by the driving unit 124. As a result, the battery cell 200 supported or adsorbed by the lifting unit 122 may be transported together with the lifting unit 122.

[0090] The lifting unit 122 may release the vacuum after transferring the battery cell 200 to the adjacent nest 126. Then, the lifting unit 122 may return to the original position by descending to the lower part of the transfer die 121 together with the driving unit 124. In this way, one battery cell 200 may be transferred from one unit transfer section to an adjacent transfer section.

[0091] Thereafter, the transfer unit 120 according to an embodiment of the present invention may sequentially repeat the above process to transfer the battery cell 200 from the input port to the nest 126 closest to the inspection unit 110 .

[0092] Meanwhile, the lithium deposition inspection device according to an embodiment of the present invention may further include an alignment unit (not shown) that aligns the battery cells 200 seated in the nest 126 that is closest to the inspection unit 110 .

[0093] The alignment unit aligns the battery cells 200 immediately before carrying out an eddy current inspection, thereby making it possible to improve the reliability of the inspection.

[0094] The battery cell 200 aligned by the alignment unit may be attracted to the lifting unit 122 again. Thus, the battery cell 200 may have its impedance measured in a state in which an eddy current is induced at a specific frequency by the inspection unit 110 including the first sensor 111 and the second sensor 112.

[0095] In order to increase the accuracy of the inspection, it is preferable that the traveling speed of the battery cell 200 is constant within the inspection area by the inspection unit 110. In addition, the traveling speed of the battery cell 200 while passing through the inspection area may be controlled to be different from the transport speed of the battery cell 200 positioned on the transport die outside the inspection area.

[0096] Thereafter, the battery cell 200, whose impedance has been measured by the test unit 110, may be transported to an outlet by transport means 122, 123, and .

[0097] Also, referring to FIG. 2, the control unit 130 is electrically connected to the inspection unit 110. Thus, the control unit 130 can receive from the inspection unit 110 an impedance measurement value of the inspection target battery cell 200 in which an eddy current is induced at a specific frequency, and determine whether or not lithium is deposited in the battery cell 200. More specifically, the control unit 130 can determine whether or not lithium is deposited in the inspection target battery cell by comparing the eddy current impedance measurement value of the inspection target battery cell 200 received from the inspection unit 110 with standard data. Here, the standard data may be pre-verified data obtained by measuring the impedance at a specific frequency for a battery cell in which lithium is deposited or a battery cell in which lithium is not deposited. A method of determining whether or not lithium is deposited in the inspection target battery cell using the standard data will be described in more detail below.

[0098] Standard Data Acquisition Experiments According to Experimental Examples of the Invention For bidirectional tab-type pouch-type lithium-ion battery cells with a battery capacity of 60 Ah, four newly manufactured battery cells in which it was confirmed through CT measurement that there was no lithium deposition, and four battery cells in which it was confirmed through CT measurement that there was lithium deposition were prepared.

[0099] Thereafter, the impedance of each of the battery cells was measured individually for each frequency using an eddy current sensor.

[0100] At this time, the boundary between the positive electrode tab and the electrode plate of the battery cell was positioned at the center of the eddy current sensor, and the battery cell was fixed so as to maintain a distance of 1 mm from the eddy current sensor, and then the individual impedance of the battery cell was measured.

[0101] FIG. 8 is a graph showing impedance measurements of standard data when the frequency is 3200 Hz according to a first experimental example of the present invention, FIG. 9 is a graph showing impedance measurements of standard data when the frequency is 4000 Hz according to a second experimental example of the present invention, and FIG. 10 is a graph showing impedance measurements of standard data when the frequency is 8000 Hz according to a comparative example of the present invention.

[0102] 8, it can be seen that when the frequency is 3200 Hz, the impedance measurement values ​​of the battery cells in which lithium is deposited are clustered in the first and second quadrants on the complex plane graph, and the impedance measurement values ​​of the battery cells in which lithium is not deposited are clustered in the third and fourth quadrants. In other words, when the frequency is 3200 Hz, the impedance measurement values ​​of the battery cells in which lithium is deposited may be clustered on the upper side with respect to the linear first division line L1, and the impedance measurement values ​​of the battery cells in which lithium is not deposited may be clustered on the lower side with respect to the first division line L1.

[0103] 9, when the frequency is 4000 Hz, the impedance measurement values ​​of the battery cells in which lithium is deposited are located in a cluster in 3 quadrants on the complex plane graph, and the impedance measurement values ​​of the battery cells in which lithium is not deposited are located in a cluster in 1 quadrant. In other words, when the frequency is 4000 Hz, the impedance measurement values ​​of the battery cells in which lithium is deposited may be located in a cluster on the upper side with respect to the straight second division line L2, and the impedance measurement values ​​of the battery cells in which lithium is not deposited may be located in a cluster on the lower side with respect to the second division line L2.

[0104] 10, it can be seen that when the frequency is 8000 Hz, the impedance measurement values ​​of the battery cells in which lithium is deposited and the impedance measurement values ​​of the battery cells in which lithium is not deposited are not clustered together but are scattered, and therefore, when the frequency is 8000 Hz, a straight dividing line dividing the impedance measurement values ​​of the battery cells in which lithium is deposited and the impedance measurement values ​​of the battery cells in which lithium is not deposited cannot be obtained.

[0105] In addition, although not shown in the drawings, at frequencies other than 8000 Hz, outside the ranges of 3190 Hz to 3210 Hz and 3990 Hz to 4010 Hz, the impedance measurement values ​​of battery cells in which lithium is deposited and the impedance measurement values ​​of battery cells in which lithium is not deposited are not clustered together but are scattered, making it difficult to distinguish them from each other using dividing lines.

[0106] Thus, the lithium deposition inspection device according to the embodiment of the present invention can determine the presence or absence of lithium deposition in a battery cell by checking the position of the impedance measurement value of the battery cell to be inspected, which is measured at a specific frequency, based on a division line obtained based on impedance standard data of the battery cell previously measured at the same frequency. According to the embodiment, the specific frequency may be any one value within a range of 3190Hz to 3210Hz or 3990Hz to 4010Hz.

[0107] Meanwhile, the control unit 130 can control the inspection unit 110 and the transport means 122, 123, 124. The control unit 130 may be configured with a conventional programmable electronic computer coupled with a memory for controlling the transport and speed of the plurality of battery cells 200. According to an embodiment, the control unit 130 may be provided with a processor that executes at least one program command stored in the memory. Here, the processor may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the method according to the embodiment of the present invention is executed.

[0108] The lithium deposition inspection device according to the embodiment of the present invention has been described above. Hereinafter, a lithium deposition inspection method according to the embodiment of the present invention using the operation of a control unit in the lithium deposition inspection device will be described.

[0109] FIG. 11 is a flow chart of a lithium deposition inspection method according to an embodiment of the present invention.

[0110] 11, a control unit 130 in the lithium deposition inspection apparatus can transfer a test target battery cell input from the outside to the inspection unit 110 by a transfer unit 120 (S100). A detailed method of transferring the test target battery cell to the inspection unit 110 using the transfer unit 120 overlaps with the description of the lithium deposition inspection apparatus described above, and therefore will not be described here.

[0111] Thereafter, the control unit 130 can operate the first sensor 111 of the inspection unit 110 to induce an eddy current in the battery cell 200 (S200).

[0112] To describe this in more detail according to an embodiment, the control unit 130 may apply an AC current at a specific frequency to the coil in the first sensor 111. As a result, a magnetic field may be formed around the battery cell 200. In this case, the specific frequency may be any one of a value from 3190 Hz to 3210 Hz or a value from 3990 Hz to 4010 Hz.

[0113] Thereafter, the control unit 130 may position the first sensor 111 close to the battery cell 200. As a result, an induced electromotive force is generated around the battery cell 200 due to an electromagnetic induction phenomenon, and an eddy current may flow in the battery cell 200 in a direction that interferes with the magnetic field.

[0114] The control unit 130 may measure the impedance of the battery cell 200 in which an eddy current is induced, using the second sensor 112 positioned adjacent to the battery cell 200 together with the first sensor 111 (S300).

[0115] Thereafter, when the measurement of the impedance of the battery cell 200 by the second sensor 112 is completed, the control unit 130 can move the first sensor 111 and the second sensor 112, which are positioned close to each other, to their initial positions so as to maintain a predetermined distance from the battery cell 200.

[0116] In addition, the control unit 130 may compare the impedance measurement value of the battery cell acquired from the second sensor 112 with standard data (S400). Here, the standard data may be pre-verified data obtained by measuring the impedance at the specific frequency for a battery cell in which lithium is deposited or a battery cell in which lithium is not deposited. In this case, the specific frequency may be the same as the specific frequency applied to the coil in the first sensor.

[0117] Thus, the control unit 130 can determine whether or not lithium has been deposited in the battery cell (S500).

[0118] According to one embodiment, the control unit 130 can compare the impedance measurement value of the battery cell obtained from the second sensor 112 with the standard data in real time to determine in real time whether or not lithium deposition has occurred in the battery cell.

[0119] According to another embodiment, the control unit 130 may collect the impedance measurement values ​​of the battery cells obtained from the second sensor 112 according to a predetermined criterion preset by a user. Then, the control unit 130 may compare the collected impedance measurement values ​​of the battery cells with the standard data to determine whether or not lithium deposition has occurred in each battery cell. For example, the predetermined criterion may be a time or the number of battery cells whose impedance has been measured by the second sensor.

[0120] To describe in more detail the method of determining whether or not lithium is deposited in a battery cell, the lithium deposition inspection device according to the embodiment of the present invention can obtain a division line at a particular frequency from previously measured standard data for each frequency. For example, the division line may be a straight reference line that divides a first group of data of battery cells in which lithium is deposited and a second group of data of battery cells in which lithium is not deposited, among the standard data at a particular frequency.

[0121] Thereafter, the lithium deposition inspection device can determine whether or not lithium deposition has occurred in the battery cell by using the impedance measurement value of the battery cell measured at a specific frequency and the division line previously obtained at the specific frequency.

[0122] According to one embodiment, the lithium deposition inspection device can display impedance measurements by eddy currents at specific frequencies on a complex plane in real time, and can also display the division lines obtained from standard data corresponding to the frequencies on the complex plane.

[0123] Thereafter, the lithium deposition inspection device may compare the positions of the real-time impedance measurement values ​​of the battery cells positioned on the complex plane with the positions of the first and second population data based on the division line.

[0124] In this case, when the impedance measurement value of the battery cell on a complex plane based on the dividing line is at a point where the first group of data is located, the lithium deposition inspection device can determine that lithium has been deposited in the battery cell.

[0125] On the other hand, when the impedance measurement value of the battery cell on the complex plane based on the dividing line is at a point where the second group data is located, the lithium deposition inspection device can determine that lithium has not been deposited in the battery cell.

[0126] According to another embodiment, the lithium deposition inspection device can display a plurality of impedance measurement values ​​by eddy current at a specific frequency collected according to a predetermined standard on a complex plane. The lithium inspection device can also display the division line obtained from standard data corresponding to the frequency on the complex plane.

[0127] Then, the lithium deposition inspection device may analyze positions of impedance measurement data of the plurality of battery cells positioned on the complex plane. For example, the lithium deposition inspection device may check whether the measurement data is clustered. Then, the lithium deposition inspection device may check whether the clustered measurement data on the complex plane is located at a position similar to the first and second cluster data of the standard data based on the division line or an arbitrary reference line having the same inclination as the division line. At this time, when the impedance measurement value of the battery cell on the complex plane is located at a position where the first cluster data is located based on the division line, the lithium deposition inspection device may determine that lithium is deposited in the battery cell.

[0128] The lithium deposition inspection method according to the embodiment of the present invention has been described above. Hereinafter, a lithium deposition inspection experiment of a battery cell performed using the lithium deposition inspection device according to the embodiment of the present invention will be described in more detail.

[0129] Lithium Deposition Inspection Experiments According to Experimental Examples of the Present Invention Using a lithium deposition inspection device according to an embodiment of the present invention including a coil-type magnetic sensor as a first sensor and an eddy current sensor as a second sensor, the presence or absence of lithium deposition was inspected for a bidirectional tab-type pouch-type lithium ion battery cell with a battery capacity of 60 Ah.

[0130] At this time, the boundary between the positive electrode tab and the electrode plate of the battery cell was positioned at the center of the eddy current sensor, and the distance between the boundary of the battery cell and the eddy current sensor was fixed to maintain a gap of 1 mm. The frequency of the first sensor was adjusted to 3200 Hz, 4000 Hz, and 8000 Hz, and the impedance of the battery cell for each frequency was measured individually.

[0131] After that, the experimental data obtained from the four battery cells that were determined to have no lithium deposition and the four battery cells that were determined to have lithium deposition were expressed on a complex plane and compared with the standard data at the relevant frequency.

[0132] FIG. 12 is an impedance measurement graph of standard data and experimental data when the frequency is 3200 Hz according to the third embodiment of the present invention, FIG. 13 is an impedance measurement graph of standard data and experimental data when the frequency is 4000 Hz according to the fourth embodiment of the present invention, and FIG. 14 is an impedance measurement graph of standard data and experimental data when the frequency is 8000 Hz according to the fifth embodiment of the present invention.

[0133] Referring to FIG. 12, when the frequency is 3200 Hz, it was confirmed that the experimental data measured by the second sensor on the complex plane was located in the form of a cluster of the first experimental data and the second experimental data based on the first division line L1 acquired in advance.

[0134] At this time, the first experimental data was impedance measurement data of four battery cells in which it was determined that lithium had been deposited, and the second experimental data was impedance measurement data of four battery cells in which it was determined that lithium had not been deposited.

[0135] In other words, it was confirmed that the impedance measurement data of the battery cell has a clustered form depending on the presence or absence of lithium deposition.

[0136] Then, previously acquired standard data with a frequency of 3200 Hz was plotted on the complex plane, and the crowd positions of the first and second experimental data were compared.

[0137] As a result of the comparison, it was confirmed that the first experimental data and the first standard data were located in the first and second quadrants located above the first demarcation line L1, and it was confirmed that the second experimental data and the second standard data were located in the third and fourth quadrants located below the first demarcation line L1.

[0138] Also, referring to FIG. 13, previously acquired standard data in the case of a frequency of 4000 Hz was plotted on the same complex plane to compare the first and second experimental data.

[0139] As a result of the comparison, it was confirmed that the first experimental data and the first standard data were located in three quadrants located to the left of the second dividing line L2, and it was confirmed that the second experimental data and the second standard data were located in one quadrant located to the right of the second dividing line L2.

[0140] On the other hand, referring to FIG. 14, it was confirmed that the first and second experimental data on the complex plane when the frequency is 8000 Hz did not have a clustering characteristic.

[0141] As a result, it can be confirmed that the lithium deposition inspection device according to the embodiment and experimental example of the present invention is capable of non-destructive inspection of battery cells for the presence or absence of lithium deposition within a specific frequency range.

[0142] The above describes an apparatus and method for inspecting lithium deposition in a battery cell according to an embodiment of the present invention.

[0143] The device and method for testing lithium deposition in a battery cell according to an embodiment of the present invention has high stability and reliability by forming a magnetic field around a battery cell to be tested to induce eddy currents, and then comparing the impedance measurement value of the battery cell with standard data to detect the presence or absence of lithium deposition in the battery cell.

[0144] The operation of the method according to the embodiment of the present invention can be realized as a computer readable program or code in a computer readable recording medium. The computer readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. In addition, the computer readable recording medium can be distributed to computer systems connected to a network so that the computer readable program or code can be stored and executed in a distributed manner.

[0145] The computer-readable recording medium may also include a hardware device specially configured to store and execute program instructions, such as a ROM, RAM, flash memory, etc. The program instructions may include not only machine code, such as produced by a compiler, but also high-level language code that may be executed by a computer using an interpreter, etc.

[0146] Although some aspects of the invention have been described in the context of an apparatus, it may also be presented in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may also be presented in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0147] Although the present invention has been described with reference to preferred embodiments thereof, it will be understood that those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention as set forth in the claims. [Explanation of symbols]

[0148] 100 ···Lithium Deposition Inspection Equipment 110 Inspection Department 111 First sensor 112 Second sensor 120...transfer section 121 Transfer die 122 Lifting section 123...Adsorption hole 124 Drive unit 125 Opening 126 Nest 130 Control section

Claims

1. An apparatus for detecting the presence or absence of lithium deposition in at least one battery cell by utilizing eddy current, comprising: An inspection unit including a first sensor that induces an eddy current in the battery cell and a second sensor that measures the impedance of the battery cell in which the eddy current is induced; and a control unit that compares a measured value of the impedance measured by the second sensor with standard data to determine whether or not lithium deposition occurs in the battery cell; Including, the first sensor and the second sensor are provided in a form in which a coil is wound around a magnetized member, The first sensor applies an alternating current having a predefined frequency to the coil to form a magnetic field, thereby inducing an eddy current in the battery cell; The second sensor measures the impedance of the battery cell at the specific frequency.

2. The lithium deposition inspection device according to claim 1 , further comprising a transport unit that transports the battery cell input from the outside to the inspection unit.

3. the first sensor is located at an upper side with respect to the conveying portion, the second sensor is located at a lower side with respect to the conveying portion, The lithium deposition inspection device according to claim 2 , wherein the first sensor and the second sensor are positioned on the same vertical line with respect to the transport unit.

4. The specific frequency is The lithium precipitation inspection device according to claim 1 , wherein the frequency is any one of values ​​from 3190 Hz to 3210 Hz.

5. The specific frequency is The lithium precipitation inspection device according to claim 1 , wherein the frequency is any one of 3990 Hz to 4010 Hz.

6. The standard data is The lithium deposition inspection device according to any one of claims 1 to 5, wherein the data is verified in advance by measuring impedance at the specific frequency for the battery cell in which lithium is deposited or the battery cell in which lithium is not deposited.

7. The control unit is using a dividing line dividing the standard data expressed on a complex plane into first crowd data and second crowd data as a reference, comparing a position of a measured value of the impedance of the battery cell measured by the second sensor on the complex plane with a position of the first crowd data and a position of the second crowd data to determine the presence or absence of lithium deposition in the battery cell measured by the second sensor; the first population data is at least one data measured from the battery cell in which lithium has been deposited; The lithium deposition inspection device according to claim 6 , wherein the second group of data is at least one piece of data measured from the battery cell in which lithium is not deposited.

8. The battery cell includes:

2. The lithium precipitation inspection device according to claim 1, which is a pouch-type lithium secondary battery cell.

9. The battery cell includes: The lithium deposition inspection device according to claim 1, which is used in an energy storage system (ESS).

10. A method for inspecting whether or not lithium is deposited inside at least one battery cell, the method including an inspection unit including a first sensor and a second sensor each having a coil wound around a magnetized member, the method comprising: applying an alternating current of a predefined specific frequency to a coil of the first sensor to generate a magnetic field, thereby inducing eddy currents in the battery cell; measuring the impedance of the battery cell at the particular frequency using the second sensor; and comparing the impedance measured by the second sensor with standard data to determine whether or not lithium deposition exists in the battery cell; A lithium deposition inspection method comprising:

11. The lithium deposition inspection method according to claim 10 , further comprising the step of: transporting the battery cell to the inspection unit, the method further comprising the step of transporting the battery cell to the inspection unit.

12. the first sensor is located at an upper side with respect to the conveying portion, the second sensor is located at a lower side with respect to the conveying portion, The lithium deposition inspection method according to claim 11 , wherein the first sensor and the second sensor are positioned on the same vertical line with respect to the transport unit.

13. The specific frequency is The lithium deposition inspection method according to claim 10, wherein the frequency is any one value between 3190 Hz and 3210 Hz.

14. The specific frequency is The lithium deposition inspection method according to claim 10, wherein the frequency is any one value between 3990 Hz and 4010 Hz.

15. The standard data is The lithium deposition inspection method according to any one of claims 10 to 14, wherein the data is verified in advance by measuring impedance at the specific frequency for the battery cell in which lithium is deposited or the battery cell in which lithium is not deposited.

16. The step of determining whether or not lithium deposition exists in the battery cell includes: a step of comparing a position of a measured value of the impedance of the battery cell measured by the second sensor with a position of the first crowd data and a position of the second crowd data on a complex plane based on a dividing line dividing the standard data expressed on a complex plane into first crowd data and second crowd data, thereby determining whether or not lithium deposition has occurred in the battery cell measured by the second sensor; Including, the first population data is at least one data measured from the battery cell in which lithium has been deposited; 16. The method of claim 15, wherein the second population of data is at least one data measured from the battery cell in which lithium is not deposited.

17. The battery cell includes: The lithium deposition inspection method according to claim 10, wherein the cell is a pouch-type lithium secondary battery cell.

18. The battery cell includes: The lithium deposition inspection method according to claim 10, which is used in an energy storage system (ESS).

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