Title of the invention: Crack inspection method and inspection device inside battery cell using eddy current
Technical field
[One]
This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0044954 filed on April 17, 2019, and all contents disclosed in the documents of the Korean patent application are included as part of this specification.
[2]
The present invention relates to a method and apparatus for inspecting a crack inside a lithium secondary battery, and to a method and apparatus for non-destructively detecting electrode cracks, tab cracks, and cracks in welds using an eddy current.
Background
[3]
As the price of energy sources rises due to the depletion of fossil fuels and interest in environmental pollution increases, the demand for eco-friendly alternative energy sources is becoming an indispensable factor for future life. In particular, technology development for mobile devices As the demand and demand increase, the demand for secondary batteries as an energy source is rapidly increasing.
[4]
Typically, in terms of the shape of the battery, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with a thin thickness. In terms of materials, lithium-ion batteries with high energy density, discharge voltage, and output stability, There is high demand for lithium secondary batteries such as lithium ion polymer batteries.
[5]
Secondary batteries are classified according to the structure of the positive electrode, the negative electrode, and the electrode assembly having a separator structure interposed between the positive electrode and the negative electrode. Typically, long sheet-shaped positive and negative electrodes are wound with a separator interposed therebetween. Jelly-roll (wound type) electrode assembly of one structure, a stacked (stacked) electrode assembly in which a plurality of anodes and cathodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween, anodes and cathodes in predetermined units And a stack-folding electrode assembly having a structure in which unit cells such as a bi-cell or full cell stacked with a separator interposed therebetween are wound.
[6]
Further, the secondary battery is manufactured by injecting an electrolyte solution, which is a liquid electrolyte, while the electrode assembly is housed in a battery container, and sealing the battery container.
[7]
During the manufacturing process of the electrode or assembly process of the electrode assembly as described above, cracks may occur on the electrode, tab, and welding part due to differences in elongation of the holding part and the uncoated part, physical external force caused by welding, etc. Cause.
[8]
The problem is that in the case of stack-folding battery cells, due to the characteristics of the stack-folding process, assembly defects occurring during the folding process are difficult to screen for defects through vision inspection due to cracks in the folding cells. There is no way to non-destructively detect cracks inside cells.
[9]
Accordingly, there is a need to develop a technology for a method and apparatus for non-destructively detecting a crack inside a battery cell.
Detailed description of the invention
Technical challenge
[10]
The present invention has been conceived to solve the above problem, and an object of the present invention is to provide an apparatus and method for non-destructively detecting a crack inside a lithium secondary battery in which sealing is completed.
Means of solving the task
[11]
In order to solve the above problem, the present invention is an apparatus for detecting a crack inside a battery cell using an eddy current,
[12]
An inspection unit including a first sensor for inducing an eddy current and a second sensor for detecting an eddy current signal induced by the first sensor, and performing an inspection by the eddy current while the battery cell is traveling;
[13]
A transfer unit for sequentially transferring a plurality of battery cells from a point where the battery cells are input to a point where they are taken out; And
[14]
A control unit that is electrically connected to the test unit and receives, evaluates, and controls an eddy current signal sensed by the test unit; It is a crack detection device inside the battery cell comprising a.
[15]
In the present invention, the crack inside the battery cell may be a crack generated on an electrode, an electrode tab, and a weld.
[16]
In an embodiment of the present invention, the inspection unit is designed to move the first sensor and the second sensor to a position to be inspected, and performs inspection by eddy current while the first sensor and the second sensor are fixed. It could be something to do.
[17]
In one embodiment of the present invention, the inspection unit is one side coupled to the first sensor, the other side is a first position adjustment member coupled to the third position adjustment member by a position fixing bolt;
[18]
One side is coupled to the second sensor, the other side is a second position adjustment member coupled to the following third position adjustment member by a position fixing bolt;
[19]
One side is coupled to the first position adjustment member and the second position adjustment member, respectively, the other side is a third position adjustment member coupled to the following fourth position adjustment member by a position fixing bolt; And
[20]
A fourth position adjusting member coupled to the third position adjusting member by a position fixing bolt; Including,
[21]
The portions at which the first and second positioning members are respectively coupled to the third position adjustment member are spaced apart at predetermined intervals on the same extension line,
[22]
The third positioning member is provided with a sliding groove having a predetermined length for position adjustment of the first positioning member and the second positioning member, the first positioning member and the second positioning member, the Can move along the sliding groove,
[23]
The fourth position adjusting member may include a sliding groove having a predetermined length for adjusting the position of the third position adjusting member, and the third position adjusting member may be movable along the sliding groove.
[24]
In one embodiment of the present invention, the first sensor and the second sensor each include a coil.
[25]
In this case, the diameter of the coil may be 0.5 to 10 mm.
[26]
In an embodiment of the present invention, the transfer unit includes: a transfer die extending from an input point to a discharge point of the battery cell; And transfer means for transferring the battery cells. It may include.
[27]
In one embodiment of the present invention, the transfer unit has a plurality of unit movement sections, and the transfer means may reciprocate one or two or more unit movement sections.
[28]
In one embodiment of the present invention, the transfer die includes a nest in which a battery cell is seated between one unit movement section and an adjacent unit movement section, and the nest is internal in accordance with the shape of the battery cell. There may be a receiving groove recessed into the formed.
[29]
In one embodiment of the present invention, the transfer means, a lifting unit for lifting the battery cell from the transfer die; And a driving part that is movably coupled to the lifting part and reciprocating the lifting part.
[30]
In one embodiment of the present invention, the elevating unit may have an adsorption hole for adsorption of the battery cell, and may be configured to adsorb the battery cell by applying a vacuum through the adsorption hole.
[31]
In one embodiment of the present invention, the lifting unit may be a cylinder that reciprocates up and down by hydraulic pressure or pneumatic pressure.
[32]
In one embodiment of the present invention, the battery cell is a pouch-type lithium secondary battery.
[33]
In one embodiment of the present invention, while the test unit performs an eddy current test, the battery cell travels at a constant speed.
[34]
In an embodiment of the present invention, the traveling speed of the battery cell within the inspection area may be controlled differently from the traveling speed of other areas.
[35]
In one embodiment of the present invention, the eddy current signal is a voltage.
[36]
In one embodiment of the present invention, further comprising an optical sensor for transmitting the start and end time of the generation and detection of the eddy current to the first sensor and the second sensor,
[37]
The optical sensor detects both ends of the electrode lead and transmits it to the first sensor and the second sensor,
[38]
With the detection signal at the first end, the eddy current test starts, and with the detection signal at the second end, the eddy current test ends.
Effects of the Invention
[39]
Since the crack detection device inside the battery cell of the present invention detects the presence and location of cracks occurring on electrodes, electrode tabs, and welds using eddy current, there is an effect of detecting cracks inside the battery cell in a non-destructive method. .
Brief description of the drawing
[40]
1 is a schematic diagram showing the principle of detecting a crack using an eddy current.
[41]
2 is a schematic diagram of an apparatus for detecting cracks inside a battery cell according to an embodiment of the present invention.
[42]
3 is a detailed view of an inspection unit according to another embodiment of the present invention.
[43]
FIG. 4 is a schematic diagram of a coil of a first sensor and a second sensor constituting the inspection unit of FIG. 3.
[44]
5 is a detailed view of an inspection unit and a transfer unit according to an embodiment of the present invention.
[45]
6 is a schematic diagram showing a conveying unit of FIG. 5.
[46]
7 is a schematic diagram showing a transfer die according to an embodiment of the present invention.
Best mode for carrying out the invention
[47]
Terms used in this specification and claims should not be construed as being limited to a conventional or dictionary meaning, and that the inventor can appropriately define the concept of terms in order to describe his own invention in the best way. Based on the principle, it should be interpreted as a meaning and concept consistent with the technical idea of ​​the invention. Therefore, the configuration shown in the embodiments described in the present specification is only one of the most preferred embodiments of the present invention and does not represent all of the technical spirit of the present invention, and various equivalents that can replace them at the time of the present application And it should be understood that there may be variations.
[48]
In the entire specification of the present application, when a certain part "includes" a certain constituent element, it means that other constituent elements may be further included rather than excluding other constituent elements unless otherwise stated.
[49]
The terms "about", "substantially" and the like used throughout this specification are used as a meaning at or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and are accurate to aid the understanding of the present application. Or absolute figures are used to prevent unreasonable use of the stated disclosure by unconscionable infringers.
[50]
In the entire specification of the present application, the term "combination(s) thereof" included in the expression of the Makushi form means one or more mixtures or combinations selected from the group consisting of the constituent elements described in the expression of the Makushi form, It means to include at least one selected from the group consisting of the above constituent elements.
[51]
In the entire specification of the present application, the description of "A and/or B" means "A or B or both".
[52]
[53]
Hereinafter, the present invention will be described in more detail.
[54]
1 is a schematic diagram showing a crack detection principle using an eddy current.
[55]
Referring to FIG. 1, when an alternating current is added to the coil 10, a primary magnetic field 20 is generated around the coil. At this time, when the coil 10 on which the primary magnetic field 20 is formed is brought to the surface of the object 50, induced electromotive force is generated in the surface of the object 50 by electromagnetic induction. This induced electromotive force flows a current that interferes with the primary magnetic field 20, which is referred to as an eddy current (40).
[56]
Such eddy current changes according to changes in the state, location, defect, material, etc. of the surface of the inspection object 50. The present invention is to detect a crack inside a battery cell by using the characteristic of such an eddy current. In other words, the battery cell, which is an object to be inspected, is passed between the eddy current sensor, and the eddy current signal is measured, and at the point where the eddy current signal is changed, it is assumed that the eddy current signal has changed due to the crack of the electrode, electrode tab, or welding part, and a crack is detected. It is to do.
[57]
2 is a schematic diagram showing a crack detection apparatus according to an embodiment of the present invention, and FIG. 5 is a detailed view of an inspection unit and a transfer unit according to an embodiment of the present invention. Referring to these drawings, a crack detection device inside a battery cell of the present invention for detecting a crack inside a battery cell using an eddy current,
[58]
A first sensor for inducing an eddy current and a second sensor for detecting an eddy current signal induced by the first sensor, and an inspection unit 110 for performing an inspection by the eddy current while the battery cell is traveling;
[59]
A transfer unit 120 for sequentially transferring a plurality of battery cells from the point where the battery cells are inserted to the point where they are taken out; And
[60]
A control unit 130 that is electrically connected to the inspection unit and receives, evaluates, and controls an eddy current signal sensed by the inspection unit; Includes.
[61]
In the present invention, the crack inside the battery cell means a crack generated on an electrode, an electrode tab, or a weld.
[62]
The cracking of the electrode means that an electrode prepared through an electrode process such as drying and rolling after an electrode mixture including an electrode active material, a binder, and a conductive material is applied on the current collector, It may be a crack on the current collector caused by a difference in elongation of the electrode mixture.
[63]
The crack of the electrode tab may be a crack generated due to vibration or external force during welding due to a stress accumulated in the wrinkle of the electrode swell or the boundary part caused by a difference in elongation between the holding part and the uncoated part.
[64]
The crack on the welding part may be a non-welded part caused by insufficient welding during welding or a crack generated during a welding process.
[65]
Cracks generated on the electrodes, electrode tabs, and welds listed above are covered by the battery case by the sealing process of sealing the electrode assembly with a battery case such as a laminate sheet. These are cracks that cannot be done. However, when the crack detection apparatus using the eddy current of the present invention is used, there is an effect of detecting the cracks.
[66]
[67]
Hereinafter, the inspection unit will be described in detail. 3 is a view showing the structure of the inspection unit according to an embodiment of the present invention, referring to this, the inspection unit 110 of the present invention, the first sensor 111 and the second sensor 112 to be tested It can be moved to a position, and is configured to induce an eddy current and detect an eddy current while the first sensor 111 and the second sensor 112 are fixed.
[68]
Specifically, the inspection department
[69]
A first sensor 111 for inducing an eddy current;
[70]
A second sensor 112 for detecting an eddy current signal induced by the first sensor 111;
[71]
One side is coupled to the first sensor 111, the other side is a first position adjustment member 113 coupled to the following third position adjustment member 117 by a position fixing bolt 115;
[72]
One side is coupled to the second sensor 112, the other side is a second position adjustment member 114 coupled to the following third position adjustment member 117 by a position fixing bolt 116;
[73]
One side is coupled to the first position adjustment member 113 and the second position adjustment member 114, respectively, and the other side is coupled to the following fourth position adjustment member 118 by a position fixing bolt 119 A third position adjustment member 117; And
[74]
A fourth position adjusting member 118 coupled with the third position adjusting member 117 by a position fixing bolt 119; It includes.
[75]
The first positioning member 113 and the second positioning member 114 are respectively coupled to the third positioning member 117 is spaced apart at a predetermined interval on the same extension line, the third The position adjustment member 117 is provided with a sliding groove (not shown) having a predetermined length for position adjustment of the first position adjustment member and the second position adjustment member, and the first position adjustment member and the second position adjustment The member can move along the sliding groove.
[76]
In addition, the fourth position adjustment member 118 is provided with a sliding groove having a predetermined length for position adjustment of the third position adjustment member 117, the third position adjustment member 117 is the It can move along the sliding groove.
[77]
According to the above embodiment, in order to move the first sensor 111 and the second sensor 112 to a position desired by the operator, the first positioning member 113 and the second positioning member ( 114) is designed to move in the vertical direction. Here, the vertical direction may be defined as a direction moving away from the battery cell 200, which is an object to be inspected, in a vertical direction and a direction closer to each other.
[78]
On one side of the third positioning member 117, a sliding groove (not shown) for moving the first positioning member may be provided at a portion coupled to the first positioning member 113. The first position adjusting member may move the movable groove along the movable groove within a length range of the movable groove. The moving groove has a shape extending in a vertical direction of the battery cell. The first position adjustment member 113 may be fixed to the third position adjustment member 117 by operation of the position fixing bolt 115.
[79]
The second sensor 112 is also coupled with one side of the second position adjustment member 114 so that it can move in the vertical direction, like the first sensor, and the other side of the first position adjustment member adjusts the third position. It is designed to be coupled to one side of the member 117. On one side of the third positioning member 117, a sliding groove (not shown) for moving the second positioning member 114 may be provided at a portion coupled to the second positioning member, and the second The position adjusting member may move along the sliding groove, and the second position adjusting member may be fixed to the third position adjusting member by operation of the position fixing bolt 116. The portions at which the first and second position adjustment members 113 and 114 are respectively coupled to the third position adjustment member 117 are spaced apart from each other at predetermined intervals on the same extension line.
[80]
In the same principle as the first positioning member and the second positioning member coupled with the third positioning member, the third positioning member is coupled with the fourth positioning member. The fourth position adjustment member may be provided with a sliding groove (not shown) through which the third position adjustment member can move, and the third position adjustment member can move by the length of the sliding groove, and the user can move the sliding groove. After moving the third positioning member to a desired position through the groove, the positioning bolt 119 is operated to fix the third positioning member to the fourth positioning member.
[81]
4 is a schematic diagram showing a first sensor and a second sensor. Referring to FIG. 4, the first sensor 111 and the second sensor 112 each include a coil.
[82]
In one embodiment of the present invention, the first sensor and the second sensor are formed in a structure in which a coil is wound around a magnetization member (not shown), and may include a case surrounding the coil. In addition, a cover is formed at one end of the case, and the other end may have an open shape. The case can protect the first sensor and the second sensor using the eddy current from external impacts, and allows the first sensor and the second sensor to be easily mounted to other places such as a transfer unit or a position fixing member to be described later.
[83]
When an alternating current is applied to the coil of the first sensor 111, a primary magnetic field is formed around the coil. In this embodiment, the coil has a spring shape, but is not limited thereto. When the coil in which the primary magnetic field is formed is brought to a lithium secondary battery, which is an object to be inspected, induced electromotive force is generated in the lithium secondary battery due to electromagnetic induction, and an eddy current that interferes with the primary magnetic field flows. As such, the first sensor induces an eddy current in the lithium secondary battery.
[84]
The second sensor 112 is located on the opposite surface of the first sensor 111 based on the battery cell as the object to be inspected. The second sensor functions to detect an eddy current signal induced by the first sensor. The second sensor detects an attenuated eddy current signal such as formation, reflection, absorption, etc. due to factors such as a state, a location, a defect, and a material of a lithium secondary battery that is an object to be inspected by the eddy current induced by the first sensor. Therefore, when there is a crack inside the battery cell, a change in the eddy current signal occurs, and the second sensor detects the eddy current signal and transmits it to a control unit to be described later.
[85]
In a preferred embodiment of the present invention, the diameter of the coil is 0.5 to 10 mm. Here, the diameter of the coil means the diameter on the horizontal cross-section of the magnetic member or the coil around which the magnetizing member is wound. If the diameter of the coil is less than 0.5mm, the diameter is too small and the detection sensitivity of the eddy current signal is low, so it may be difficult to precisely detect the internal crack of the secondary battery.On the contrary, when the diameter of the coil exceeds 10mm, the internal crack is detected due to noise. It is not desirable because it has a negative effect on Therefore, it is desirable to select an optimum coil diameter for detecting internal cracks while appropriately adjusting the diameter of the coil within the above numerical range.
[86]
In performing the inspection using eddy current, the distance between the coil and the surface to be inspected is referred to as lift-off. In order to improve the ability to detect defects on the surface to be inspected, it is desirable to maintain or minimize the lift-off.
[87]
[88]
Hereinafter, the transfer unit 120 will be described.
[89]
5 is a view of a crack inspection apparatus according to an embodiment of the present invention as viewed from above, showing the inspection unit 110 and the transfer unit 120, and FIG. 6 is a detailed view of the transfer unit 120 of FIG. 5. Referring to these drawings, the transfer unit 120 includes a transfer die 121 extending from an input point to a discharge point of the battery cell; Transfer means (122, 123, 124) for transferring the battery cell; Contains.
[90]
The inserted battery cell 200 of the crack detection device inside the battery cell of the present invention is transferred to the inspection unit 110 by the transfer unit 120, and is transferred to the carrying out after the inspection by the inspection unit 110 is finished. It is taken out. A plurality of battery cells 200 are sequentially introduced into the transfer unit 120, and the battery cells are arranged and transferred at regular intervals.
[91]
The inspection unit 110 performs inspection by using eddy current while the battery cell travels through the inspection area. During inspection of the preceding battery cell, the subsequent battery cell is transferred to a position where the preceding battery cell stayed. At this time, the subsequent battery cells may have a predetermined inspection waiting time, and when the preceding battery cell inspection ends and leaves the inspection area, the subsequent battery cells are transferred into the inspection area to start the inspection.
[92]
The inspection apparatus of the present invention may adjust the traveling speed of the battery cells in the inspection area differently from the transfer speed of the battery cells outside the inspection area, if necessary. That is, the traveling speed of the battery cells within the inspection area may be slower than the transfer speed of the battery cells in an area other than the inspection area.
[93]
Referring to FIGS. 3 and 5, the apparatus for detecting internal cracks of the present invention includes a first sensor while the battery cell 200, which is an inspection object, passes between the first sensor 111 and the second sensor 112. And the second sensor is operated, and the eddy current is inspected while the battery cell 200 is interposed between the sensors 111 and 112. At this time, the battery cell passes between the first sensor and the second sensor by means of transport means 122, 123, 124 to be described later. And while the eddy current test is being performed by the first sensor and the second sensor, it is preferable that the battery cell travels the test area at a constant speed.
[94]
Referring to Figure 6 showing an embodiment of the transfer unit 120 of the present invention, the transfer unit 120 of the present invention, the transfer die 121; It may include a transfer means (122, 123, 124) for transferring the battery cell. And the transfer means, the elevating part 122 for lifting the battery cell from the transfer die; And the lifting part 122 is coupled to be movable, and may include a driving part 124 for transferring the lifting part in the transfer direction of the battery cell. As long as the driving unit moves the lifting unit, various forms may be applied.
[95]
The elevating unit may be a cylinder that reciprocates up and down by hydraulic pressure or pneumatic pressure. Hereinafter, an embodiment of the lifting unit will be described.
[96]
Referring to FIG. 6, the elevating part 122 extends in a direction parallel to the driving direction of the battery cell 200, has a narrow width and a long length, and has a shape of a bar. Long bars are disposed above and below the center line parallel to the longitudinal direction of the transfer die (the driving direction of the battery cell), respectively. These cuboid-shaped lifting units support the battery cells 200, and move the battery cells together while moving in the transport direction of the battery cells as the driving unit 124 moves.
[97]
In an embodiment of the present invention, the elevating unit may include at least one adsorption hole 123 for adsorption of the battery cell. The number of adsorption holes 123 may be appropriately adjusted as necessary.
[98]
The elevating part 122 adsorbs the battery cell to pick up the battery cell, and extends and rises from the driving part 124 to adsorb the battery cell. The driving unit 124 may have a surface facing the surface on which the battery cells are seated relative to the transfer die, and may be installed on the lower surface of the transfer die 121. The transfer die 121 may have an opening 125 at a portion corresponding to the elevation part so that the lift part penetrates the transfer die and rises to the upper part of the transfer die.
[99]
When the elevating portion extends from the driving unit and passes through the opening 125 of the transfer die and rises to the upper portion of the transfer die, the battery cell is adsorbed and fixed to the elevating portion by applying a vacuum through the suction hole 123. .
[100]
As the elevating portion can adsorb the battery cell as described above, the internal crack detection apparatus of the present invention can suppress the alignment of the battery cells, the battery cells are removed from the elevating portion, or the vibration of the battery cells. There is an effect. In the present invention for detecting eddy current induction and eddy current signal change while the battery cell is running, in order to improve inspection reliability, disturbance of battery cell alignment and battery cell vibration should be suppressed as much as possible when the battery cell is running. The apparatus is provided with an adsorption unit in the elevating portion, thereby suppressing vibration even when the battery cell travels during the eddy current inspection, thereby improving the reliability of inspection.
[101]
In one embodiment of the present invention, an embodiment in which the elevating unit applies a vacuum through the suction hole to adsorb the battery cell is illustrated, but as long as the elevating unit can fix the battery cell, various forms are not limited to the method Can be applied.
[102]
In an embodiment of the present invention, the transfer unit may have a plurality of unit movement sections, and the transfer means may reciprocate one unit movement section or two or more unit movement sections. Accordingly, the transfer unit may have a plurality of transfer means.
[103]
Referring to FIG. 5, the transfer unit has a plurality of unit movement sections (a). The transfer means picks up the battery cell placed at the start point of the unit movement section and transfers it to the start point of the adjacent unit movement section. After completing the transfer of the battery cells in the unit movement section, the transfer means returns to the starting point of the unit movement section. By repeating the above process, the plurality of battery cells are sequentially transferred.
[104]
7 shows a part of the transfer die 121 according to an embodiment of the present invention, and referring to this, the transfer die 121 includes a battery between one unit movement section and an adjacent unit movement section. A nest 126 on which the cell is seated may be provided.
[105]
The nest 126 has an accommodating groove recessed therein corresponding to the shape of the battery cell, and the battery cell 200 is seated in the nest. As the battery cells are transferred from the input point to the inspection area, the alignment of the battery cells may be disturbed.The crack detection device of the present invention has a nest in the transfer die, so that the battery cells are aligned by being seated in the nest. .
[106]
Referring to FIG. 7, the receiving groove is formed in a direction parallel to the driving direction of the battery cell and a direction orthogonal to the driving direction of the battery cell, so that a cross-shaped shape is recessed into the interior. This is for inspection in the length direction of the battery cell and the width direction of the battery cell when inspecting the battery cell.
[107]
A detailed description will be given of a process in which the test target battery cell 200 is put into and taken out of the test apparatus of the present invention.
[108]
The conveying die constituting the conveying part of the present invention is provided with a plurality of nests.
[109]
When the battery cell is inserted into the nest located at the battery cell input point, the elevating part 122 from the driving part 124 extends in the direction of the transfer die and rises through the opening 125 of the transfer die 121.
[110]
The lifting part 122 raised to the upper part of the transfer die adsorbs and fixes the battery cell 200 seated on the nest. This is to minimize the movement of the battery cells during transport, when the battery cells are removed from the transport means, the alignment is disturbed during transport, or during inspection. The method of adsorbing the battery cell by the elevating unit is not limited to the above-described embodiment as long as the movement of the battery cell can be minimized.
[111]
The lifting part 122 is movably coupled to the driving part 124, and reciprocating movement is possible through the driving of the driving part. The lifting part 122 adsorbing the battery cell moves toward the direction in which the inspection part 110 is installed by driving the driving part while maintaining the raised state. At this time, the battery cells supported or adsorbed by the lifting unit are also transported.
[112]
The elevating unit transfers the adsorbed battery cells to the adjacent nest, and the elevating unit, which has completed the transfer to the adjacent nest, releases the vacuum. The elevating portion after releasing the vacuum is lowered again toward the driving portion installed at the lower portion of the transfer die, and the driving portion returns to its original position together with the elevating portion. As a result, one battery cell is transferred from one unit movement section to an adjacent movement section. Then, this process is sequentially repeated, so that the battery cell reaches the nest closest to the inspection unit 110 from the point of input.
[113]
In one embodiment of the present invention, the internal crack inspection apparatus of the present invention may further include an alignment unit for aligning the battery cells seated in the nest closest to the inspection unit. By aligning the battery cells immediately before performing the eddy current test, reliability of the test may be improved.
[114]
The battery cells aligned by the alignment unit are again adsorbed by the lifting unit 122 to travel through the inspection area, and are subjected to an eddy current test by the first sensor and the second sensor.
[115]
It is preferable that the running speed of the battery cell is constant in order to increase the accuracy of the inspection within the inspection area by the inspection unit. In addition, the traveling speed while the battery cells pass through the inspection area may be controlled differently from the transfer speed of the battery cells in other areas.
[116]
The battery cell, which has completed the eddy current test by the inspection unit, is transferred to the point where the battery cell is carried out by a transfer unit including the lifting unit and the driving unit.
[117]
The control unit 130 will be described in detail. The control unit 130 constituting the crack detection apparatus of the present invention is electrically connected to the inspection unit 110, receives and evaluates the eddy current signal sensed by the inspection unit, and controls the detection apparatus of the present invention. Do it.
[118]
The control unit may receive information on the eddy current signal and display an image, and may determine an internal crack based on the displayed image.
[119]
In one embodiment of the present invention, the eddy current signal sensed by the inspection unit may be a voltage, and when there is a crack inside the battery cell, the cracked portion has a voltage change, and based on this, the presence or absence of a crack and the crack The location of can be detected.
[120]
The control unit receives and records the voltage sensed by the inspection unit, and detects the presence or absence of a crack and the location from the profile of the voltage value according to the detection location.
[121]
The control unit may control the inspection unit and the transfer unit. The control unit may be configured as a conventional programmable electronic computer coupled with a memory for controlling the transfer and speed of a plurality of battery cells.
[122]
The crack detection apparatus of the present invention determines cracks based on changes in eddy current signals, and is useful when detecting internal cracks of a pouch-type lithium secondary battery.
[123]
Hereinafter, the pouch-type lithium secondary battery of the present invention will be described in detail.
[124]
In general, lithium secondary batteries can be classified according to the structure of the electrode assembly of the anode/separator/cathode structure. Wind-up type) electrode assembly, a stacked (stacked) electrode assembly in which a plurality of anodes and cathodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween. A bi-cell in which positive and negative electrodes of a predetermined unit are stacked with a separator interposed therebetween, or a stack/folding electrode assembly having a structure in which full cells are wound.
[125]
Recently, a pouch-type battery having a structure in which a stack-type or stack/folding-type electrode assembly is embedded in a pouch-type battery case of an aluminum laminate sheet is attracting a lot of attention due to low manufacturing cost, low weight, and easy shape transformation. Also, its usage is increasing sticky.
[126]
A pouch-type lithium secondary battery includes an electrode assembly, electrode tabs extending from the electrode assembly, electrode leads welded to the electrode tabs, and a battery case accommodating the electrode assembly.
[127]
[128]
An electrode assembly is a power plant in which an anode and a cathode are sequentially stacked with a separator interposed therebetween, and has a stacked or stacked/folded structure. The electrode tabs extend from each electrode plate of the electrode assembly, and the electrode lead is electrically connected to a plurality of electrode tabs extending from each electrode plate, for example, by welding, and a part of the battery case is exposed to the outside. . In addition, insulating films are attached to the upper and lower portions of the electrode leads to increase the degree of sealing with the battery case and at the same time secure electrical insulation.
[129]
The battery case is made of an aluminum laminate sheet, provides a storage space for accommodating an electrode assembly, and has a pouch shape as a whole. In the case of the stacked electrode assembly, the inner top of the battery case is spaced apart from the electrode assembly so that the plurality of positive electrode tabs and the plurality of negative electrode tabs can be coupled together to the electrode lead.
[130]
Pouch-type lithium secondary batteries are difficult to detect from the outside because electrodes, electrode tabs, and welding portions are inside the battery case as described above. Cracks inside the battery can be detected.
[131]
[132]
The crack detection apparatus according to another embodiment of the present invention may further include an optical sensor that transmits the induction time of the eddy current and the end time of detection of the eddy current signal to the inspection unit.
[133]
Specifically, when the optical sensor detects the first end, which is the first end, of both ends of the electrode lead and transmits a detection signal to the test unit, the first sensor and the second sensor of the test unit operate to induce eddy current. And when the detection of the eddy current signal is started, and the optical sensor detects a second end, which is a second end, of both ends of the electrode lead and transmits the detection signal to the test unit, the first and second sensors of the test unit The operation ends. As described above, by limiting the start and end points of the eddy current test by the test unit to the region of the electrode lead, the test range is reduced to a region included in the electrode lead length, thereby improving detection sensitivity.
[134]
As described above, the electrode lead is electrically connected to a plurality of electrode tabs extending from each electrode plate by welding, and the electrode lead is drawn out of the battery case, so that the recognition of the electrode lead end by the optical sensor It is possible.
[135]
The electrode lead includes a first end on one side and a second end on the other side, and the optical sensor moves from the first end to the second end and senses the first end and the second end. Specifically, the fine light wire recognizes the first end of one side of the electrode lead and transmits the recognition signal to the first sensor. When the first sensor receives a recognition signal from the photosensor, the first sensor applies current to the eddy current coil and ultimately starts inducing the eddy current to the lithium secondary battery. The optical sensor detects the second end while moving from the first end toward the second end, and transmits a recognition signal to the second sensor when the second end is recognized. When the second sensor receives the recognition signal from the optical sensor, it ends the reception of the eddy current signal by the second sensor.
[136]
[137]
The present invention has been described with reference to the embodiments shown in the drawings, but this is only exemplary, and those of ordinary skill in the field to which the present technology belongs can make various modifications and other equivalent embodiments possible I will understand. Therefore, the true technical protection scope of the present invention should be determined by the claims.
[138]
[Explanation of code]
[139]
100: crack detection device inside the secondary battery
[140]
110: inspection unit
[141]
111: first sensor 112: second sensor
[142]
113: first positioning member 114: second positioning member
[143]
115, 116, 119: Position fixing bolt
[144]
117: third positioning member 118: fourth positioning member
[145]
120: transfer unit
[146]
121: transfer die 122: elevating part
[147]
123: adsorption hole 124: drive unit
[148]
125: opening 126: nest
[149]
a: unit movement section
[150]
130: control unit
[151]
200: battery cell
Claims
[Claim 1]
A device that detects cracks inside a battery cell using an eddy current, comprising a first sensor for inducing an eddy current and a second sensor for sensing an eddy current signal induced by the first sensor, and the battery cell is driven An inspection unit that performs inspection by eddy current during the operation; A transfer unit for sequentially transferring a plurality of battery cells from a point where the battery cells are input to a point where they are taken out; And a control unit electrically connected to the test unit and configured to receive, evaluate, and control an eddy current signal sensed by the test unit. Crack detection device inside the battery cell comprising a.
[Claim 2]
The apparatus for detecting a crack inside a battery cell according to claim 1, wherein the crack inside the battery cell is a crack generated on an electrode, an electrode tab, and a welding portion.
[Claim 3]
The method of claim 1, wherein the inspection unit is designed to move the first sensor and the second sensor to a location to be inspected, and performs inspection by eddy current while the first sensor and the second sensor are fixed. Crack detection device inside the battery cell, characterized in that.
[Claim 4]
According to claim 3, The inspection unit, One side is coupled to the first sensor, the other side is a first position adjustment member coupled to the third position adjustment member by a position fixing bolt; One side is coupled to the second sensor, the other side is a second position adjustment member coupled to the following third position adjustment member by a position fixing bolt; One side is coupled to the first position adjustment member and the second position adjustment member, respectively, the other side is a third position adjustment member coupled to the following fourth position adjustment member by a position fixing bolt; And a fourth position adjusting member coupled to the third position adjusting member by a position fixing bolt. Including, wherein the first position adjustment member and the second position adjustment member are respectively coupled to the third position adjustment member is spaced apart at a predetermined interval on the same extension line, the third position adjustment member, It is provided with a sliding groove having a predetermined length for position adjustment of the first positioning member and the second positioning member, the first positioning member and the second positioning member can move along the sliding groove, , Wherein the fourth position adjustment member has a sliding groove having a predetermined length for position adjustment of the third position adjustment member, and the third position adjustment member is movable along the sliding groove. Crack detection device inside the battery cell.
[Claim 5]
The apparatus of claim 1, wherein the first sensor and the second sensor each include a coil.
[Claim 6]
The apparatus of claim 5, wherein the coil has a diameter of 0.5 to 10 mm.
[Claim 7]
The apparatus of claim 1, wherein the transfer unit comprises: a transfer die extending from an input point to a discharge point of the battery cell; And transfer means for transferring the battery cells. Crack detection device inside the battery cell comprising a.
[Claim 8]
8. The apparatus of claim 7, wherein the transfer unit includes a plurality of unit movement sections, and the transfer unit reciprocates one or two or more unit movement sections.
[Claim 9]
The method of claim 8, wherein the transfer die includes a nest in which a battery cell is seated between one unit movement section and an adjacent unit movement section, and the nest is recessed inward corresponding to the shape of the battery cell Crack detection device inside the battery cell, characterized in that the receiving groove is formed.
[Claim 10]
The apparatus of claim 7, wherein the transfer means comprises: an elevating unit for elevating the battery cell from the transfer die; And a driving unit configured to be movably coupled to the elevating portion and reciprocating the elevating portion in a horizontal direction.
[Claim 11]
The crack detection apparatus according to claim 10, wherein the elevating portion has an adsorption hole for adsorption of the battery cell, and vacuum is applied through the adsorption hole to adsorb the battery cell.
[Claim 12]
11. The apparatus of claim 10, wherein the elevating unit is a cylinder that reciprocates up and down by hydraulic pressure or pneumatic pressure.
[Claim 13]
The apparatus of claim 1, wherein while the inspection unit performs an eddy current inspection, the battery cell travels at a constant speed.
[Claim 14]
The apparatus of claim 1, wherein the driving speed of the battery cell within the inspection area is controlled differently from the driving speed of other areas.
[Claim 15]
The apparatus of claim 1, wherein the eddy current signal is a voltage.
[Claim 16]
The method of claim 1, further comprising an optical sensor that transmits the start and end time of generation and detection of eddy current to the first sensor and the second sensor, wherein the optical sensor detects both ends of the electrode lead, Crack detection inside the lithium secondary battery, characterized in that the eddy current test is started by the detection signal of the first end and the eddy current test is terminated by the detection signal of the second end, transmitted to the first sensor and the second sensor. Device.