Battery cell clamp including spacer, device for measuring battery cell volume including the battery cell clamp, and method for measuring battery cell volume using the device

Abstract

The present invention relates to a battery cell clamp including a spacer, a device for measuring the volume of a battery cell including the battery cell clamp, and a method for measuring the volume of a battery cell using the device. The spacer includes a slit portion open along its length, thereby preventing water from accumulating between the battery cell clamp and the spacer when measuring the volume change of a battery cell using the Archimedes principle.

Description

Technical Field

[0001] This application claims priority based on Korean Patent Application No. 10-2020-0125775, filed on September 28, 2020, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a battery cell jig including a spacer, a battery cell volume measuring device including the battery cell jig, and a battery cell volume measuring method performed by using the device. Background Art

[0003] Recently, secondary batteries, which can be charged and discharged, have become widely used as energy sources for wireless mobile devices. Furthermore, secondary batteries are attracting attention as energy sources for electric vehicles, hybrid electric vehicles, and the like, which are proposed as a solution to air pollution caused by existing gasoline and diesel vehicles that use fossil fuels. Consequently, due to the advantages of secondary batteries, the types of applications using them are currently extremely diverse, and they are expected to be applied to many fields and products in the future.

[0004] Depending on the composition of the electrodes and electrolyte, such secondary batteries can be classified as lithium-ion batteries, lithium-ion polymer batteries, lithium polymer batteries, etc., among which the use of lithium-ion polymer batteries, which are less likely to leak electrolytes and easier to manufacture, is increasing. Generally, depending on the shape of the battery casing, secondary batteries are classified into: cylindrical batteries and prismatic batteries, in which the electrode assembly is embedded in a cylindrical or rectangular metal can; and pouch-type batteries, in which the electrode assembly is embedded in a pouch-shaped casing of aluminum laminate sheet. The electrode assembly built into the battery casing consists of a positive electrode, a negative electrode, and a separator between the positive and negative electrodes, and is a power generation element capable of charging and discharging. The electrode assembly is classified into: a jelly roll type, which is wound with a separator between the positive and negative electrodes, and the positive and negative electrodes are long sheets coated with active materials; and a stacked type, in which multiple positive and negative electrodes of predetermined sizes are stacked in sequence with a separator between them.

[0005] Here, as battery capacity increases, the size of the housing also increases, and the processing of thin materials is attracting attention. Therefore, the use of pouch-type batteries with a structure in which a stacked or stacked / folded electrode assembly is built into a pouch-type battery housing made of aluminum laminate sheets is gradually increasing due to low manufacturing costs, light weight, and easy shape change.

[0006] Such secondary batteries degrade as large amounts of gas are generated by the decomposition of the electrolyte due to repeated charge and discharge cycles. This degradation varies depending on the battery design and usage. Continued gas generation within the battery causes swelling, which increases the battery's volume. If the internal pressure of the battery cell exceeds a critical point, the battery may explode. Therefore, it is essential to monitor changes in the volume of the battery cell.

[0007] Conventionally, in order to observe the volume change of a battery cell, the Archimedes principle is used to measure the volume change of the battery cell. In this case, the battery cell is placed in a battery cell fixture to squeeze the battery cell, and then the experiment is performed. Figure 1 is a schematic diagram of a conventional battery cell jig for evaluating the performance of a secondary battery, and Figure 2 yes Figure 1 The right side cross-sectional view (A-A') of the battery cell clamp shown in FIG. Figure 1 As shown, the battery cell clamp 10 performs bolt tightening using nuts 15 and bolts 14 that penetrate the first plate 12 and the second plate 13 to fix the battery cell 11. In addition, since there is a problem that the pressure applied to the battery cell 11 varies depending on the position according to the tightening order of the bolts 14 and the nuts 15 or the style of the workers, as shown in FIG. Figure 2 As shown, a method of minimizing the application of deviation pressure caused by position or fastening errors by using a spacer adapted to the thickness of the battery cell 11 has been used.

[0008] However, when the volume change is measured using Archimedes' principle in a state where the battery cell 11 is accommodated in the battery cell clamp 10, inaccurate data may be obtained because water is retained in the space between the battery cell clamp 10 and the spacer 16, which may cause corrosion of the bolt 14 and the battery cell clamp 10. Therefore, the volume of the battery cell should be measured after disassembling the battery cell clamp 10. Summary of the Invention

[0009]

Technical Issues

[0010] The present invention is believed to solve at least some of the above-mentioned problems. For example, aspects of the present invention provide: a battery cell clamp including a spacer that can prevent water from stagnating in the space between the battery cell clamp and the spacer when measuring the volume change of a battery cell; a battery cell volume measurement device including the battery cell clamp; and a battery cell volume measurement method performed using the device.

[0011]

Technical Solution

[0012] The present invention provides a battery cell clamp including a spacer and a battery cell volume measurement device including the battery cell clamp. In one embodiment, the battery cell clamp according to the present invention includes: a first plate and a second plate; a bolt and a nut that secure the first and second plates with a battery cell interposed therebetween; and a spacer positioned between the first and second plates to define a separation distance and having a structure that surrounds the bolt. In this case, the spacer includes a slit unit that opens in the longitudinal direction of the spacer.

[0013] In one embodiment, the slit unit of the spacer is opened from one side to the other side along the longitudinal direction.

[0014] In another embodiment, the angle of the slit unit of the spacer is in the range of 10 degrees to 70 degrees relative to the axis center.

[0015] The height of the spacer may correspond to the height of the battery cell interposed between the first plate and the second plate.In addition, the battery cell clamp may include 4 to 12 bolts and nuts, respectively, and the spacer may be fastened by at least one bolt.

[0016] The present invention also provides a battery cell volume measurement device including the aforementioned battery cell clamp. In one embodiment, the device for measuring the volume of a battery cell according to the present invention includes: the battery cell clamp; a water tank containing a liquid; and a scale for measuring the weight of the battery cell clamp containing a battery cell, both outside and inside the water tank. In a specific example, the battery cell volume measurement device further includes a charging and discharging unit electrically connected to the battery cell.

[0017] The present invention also provides a method for measuring the volume of a battery cell using the above-mentioned battery cell volume measuring device. In one embodiment, the method for measuring the volume of a battery cell according to the present invention is performed by placing a battery cell in a battery cell fixture and then measuring the weight of the battery cell before and after the volume change.

[0018] In a specific example, the method includes: placing a battery cell in a battery cell fixture, and then measuring the weight of the battery cell fixture in air; placing the battery cell fixture in a water tank containing a liquid, and then measuring the weight of the battery cell fixture in the liquid; and calculating the volume of the battery cell after the volume change using the following formula 1:

[0019] [Formula 1]

[0020]

[0021] Here, V represents the volume of the battery cell after the volume change, W1 represents the weight of the battery cell jig in the air, W2 represents the weight of the battery cell jig accommodated in the liquid, and ρ represents the density of the liquid.

[0022] At this time, measuring the weight of the battery cell jig in the liquid may include charging and discharging the battery cell.

[0023] Furthermore, during the measurement of the weight of the battery cell jig in the air and the measurement of the weight of the battery cell jig in the liquid, the weight of the battery cell jig may be measured by using a spring balance.

[0024] In another embodiment, measuring the weight of the battery cell fixture in the liquid may include heating the liquid to a predetermined temperature. In this case, calculating the volume of the battery cell after the volume change may include calculating the volume change of the battery cell according to the temperature of the liquid.

[0025] Furthermore, the liquid contained in the water tank may be water, ethanol, or silicone oil.

[0026]

Beneficial effects

[0027] According to the battery cell clamp including a spacer, the battery cell volume measuring device including the battery cell clamp, and the battery cell volume measuring method performed by using the device of the present invention, the space between the first plate and the second plate (the first plate and the second plate have the battery cell interposed therebetween) can be kept constant.

[0028] Furthermore, by including the slit unit opened in the longitudinal direction in the spacer, it is possible to prevent water from being retained at the space between the battery cell clamp and the spacer when measuring the volume change of the battery cell using Archimedes' principle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of a conventional battery cell jig used to evaluate secondary battery performance.

[0030] Figure 2 yes Figure 1 1 is a right side cross-sectional view (AA') of the battery cell clamp shown in FIG.

[0031] Figure 3 is a right side cross-sectional view of a battery cell clamp including a spacer according to one embodiment of the present invention.

[0032] Figure 4 is a right side cross-sectional view of a battery cell clamp including a spacer according to another embodiment of the present invention.

[0033] Figure 5is a block diagram illustrating each component of a battery cell volume measuring device according to still another embodiment of the present invention.

[0034] Figure 6 is a flowchart illustrating a method for measuring the volume of a battery cell according to yet another embodiment of the present invention. DETAILED DESCRIPTION

[0035] Since the present invention allows for various variations and numerous embodiments, specific embodiments will be shown in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific forms disclosed, and it should be understood that all variations, equivalents, and alternatives are included within the spirit and scope of the invention.

[0036] In the present application, it should be understood that terms such as "including" or "having" are intended to indicate the presence of features, quantities, steps, operations, components, parts, or combinations thereof described in the specification, and these terms do not preclude the possibility of the presence or addition of one or more other features or quantities, steps, operations, components, parts, or combinations thereof. Moreover, when a portion such as a layer, film, region, plate, etc. is referred to as being "on" another portion, this includes not only the case where the portion is "directly on" another portion, but also the case where another further portion is interposed therebetween. On the other hand, when a portion such as a layer, film, region, plate, etc. is referred to as being "under" another portion, this includes not only the case where the portion is "directly under" another portion, but also the case where another further portion is interposed therebetween. Furthermore, "disposed on..." in the present application may include the case where it is disposed at the bottom as well as the top.

[0037] The present invention provides a battery cell jig including a spacer, a battery cell volume measuring device including the battery cell jig, and a battery cell volume measuring method performed by using the device.

[0038] Traditionally, the volume change of a battery cell is measured using the Archimedes principle. At this time, in order to squeeze the battery cell, the battery cell is contained in a battery cell fixture to perform the experiment, and in order to squeeze the battery cell contained in the battery cell fixture with uniform pressure, a spacer corresponding to the thickness of the battery cell is used to minimize the deviation pressure application due to position and tightening errors. However, when the Archimedes principle is used to measure the volume change in a state where the battery cell is contained in the battery cell fixture, inaccurate data may be obtained because water is trapped in the space between the battery cell fixture and the spacer, which may cause corrosion of the bolts and the battery cell fixture. Therefore, the volume of the battery cell should be measured after disassembling the battery cell fixture.

[0039] Therefore, the present invention provides: a battery cell clamp including a spacer, which can prevent water from being retained in the space between the battery cell clamp and the spacer when measuring the volume change of the battery cell; a battery cell volume measuring device including the battery cell clamp; and a battery cell volume measuring method performed by using the device.

[0040] Specifically, according to the battery cell clamp including a spacer, the battery cell volume measuring device including the battery cell clamp, and the battery cell volume measuring method performed by using the device of the present invention, the space between the first plate and the second plate (the first plate and the second plate so that the battery cell is interposed between the first plate and the second plate) can be kept constant, and by including a slit unit open in the longitudinal direction in the spacer, when the volume change of the battery cell is measured using the Archimedes principle, water can be prevented from being retained in the space between the battery cell clamp and the spacer.

[0041] In one embodiment, the present invention provides a battery cell clamp including a spacer. Specifically, the battery cell clamp includes: a first plate and a second plate; a bolt and a nut that secure the first and second plates with a battery cell interposed therebetween; and a spacer positioned between the first and second plates to define a separation distance and surrounding the bolt. The spacer includes a slit unit that opens longitudinally.

[0042] In the present invention, a "slit unit" refers to a gap formed in the longitudinal direction of a spacer, and also refers to an open area formed in the longitudinal direction of the spacer. In particular, since the battery cell clamp according to the present invention includes a slit unit in the spacer, it is possible to prevent water or gas from being trapped in the space when measuring the volume change of a battery cell using the Archimedes principle.

[0043] In one embodiment, a battery cell clamp according to the present invention includes a spacer including a slit unit that is open in the longitudinal direction. The spacer is used to maintain a constant distance between the first plate and the second plate and has a structure that surrounds the bolt. The spacer can be made of aluminum.

[0044] In addition, the slit unit of the spacer may be opened from one side to the other side along the longitudinal direction.

[0045] In a specific example, the spacer has a C-shape when viewed based on a cross section. The slit unit of the spacer can prevent water from being retained in the spacer or prevent gas from being filled in the spacer when measuring the volume of the battery cell using the Archimedean principle.

[0046] In another embodiment, a spacer is provided that includes a slit unit that is open in a longitudinal direction. Specifically, the slit unit of the spacer may be open in a range of 10 to 70 degrees relative to the center of the axis.

[0047] The slit unit of the spacer opens at an angle of 10 to 70 degrees relative to the center axis of the spacer, based on the cross-section of the spacer. For example, the slit unit opens at an average of 60 degrees relative to the spacer's axis. The slit unit opening at this angle prevents water from stagnating in the space between the battery cell clamp and the spacer, or prevents gas from filling the space.

[0048] In another embodiment, when measuring the volume change of the battery cell using the Archimedes principle, since the spacer is opened at the above-mentioned angle, the volume change of the battery cell may be measured after separating the spacer from the battery cell jig.

[0049] Furthermore, the first and second plates have a structure that squeezes the battery cells while interposing the battery cells therebetween, and are fastened together by bolts and nuts with the battery cells interposed therebetween. In this case, the first and second plates may be made of aluminum.

[0050] Furthermore, the battery cell interposed between the first and second plates may be a pouch-type unit cell. Specifically, the pouch-type unit cell may have a structure in which an electrode assembly having a positive electrode / separator / negative electrode structure is embedded in the outer material of the laminate sheet while being connected to an electrode lead formed on the outer surface of the outer material. The electrode lead may be led to the outer side of the sheet and may extend in the same or opposite directions.

[0051] In one embodiment, the battery cell clamp according to the present invention includes a plurality of bolts and nuts. In a specific example, the battery cell clamp according to the present invention includes 4 to 12 or 6 to 10 bolts and nuts, respectively. For example, the battery cell clamp includes 10 bolts and nuts, respectively.

[0052] Furthermore, the spacers can be fastened by at least one bolt. That is, each spacer is fastened to each of the plurality of bolts, and the spacers are fastened to have the same height. Furthermore, each bolt and nut can be fastened with the same pressure.

[0053] In one embodiment, the height of the spacer can correspond to the height of the battery cells between the first and second plates. This makes it easy to adjust the spacing between the first and second plates. Specifically, the user allows the battery cells to be positioned at the second plate, which is coupled to the bolts, and inserts the spacer into the bolts. After allowing the battery cells to reach the height of the spacer stack, the first plates can be coupled and secured with nuts.

[0054] In one embodiment, the battery cell clamp according to the present invention includes a plurality of bolts and nuts. In particular, by inserting a spacer having the same height into each bolt, deviation pressure or tightening error at each position can be minimized.

[0055] Furthermore, the present invention provides a battery cell volume measuring device including the battery cell clamp.

[0056] In one embodiment, the device for measuring the volume of a battery cell according to the present invention includes: the battery cell clamp; a water tank containing liquid; and a scale that measures the weight of the battery cell clamp containing the battery cell at the outside and inside of the water tank, respectively.

[0057] The device for measuring the volume of a battery cell according to the present invention utilizes Archimedes' principle. According to Archimedes' principle, the buoyant force applied to an object fully or partially immersed in a liquid acts in a direction opposite to the direction of gravity, and the magnitude of this buoyant force is equal to the weight of the volume of liquid displaced by the object (F = ρgV = mg, where F is the buoyant force, ρ is the density of the liquid, V is the volume of the object (equivalent to the amount immersed in the liquid), g is the acceleration due to gravity, and m is the mass of the object). The difference between the weight of the battery cell before and after immersion in the liquid contained in the water tank can be calculated as the weight of the liquid whose volume increases as the battery cell is immersed in the liquid. Since the weight of the liquid displaced as the battery cell is immersed in the liquid is equal to the buoyant force, the volume of the battery cell can be determined based on the measured buoyancy. That is, if the weight of the battery cell in air and the weight of the battery cell in the liquid are determined, the volume of the battery cell can be calculated.

[0058] Likewise, the battery cell volume measuring device according to the present invention can measure the volume of a battery cell in a non-destructive manner under normal pressure by only measuring the weight of the battery cell without punching or pressing the battery.

[0059] In one embodiment, the water tank has a space in which a liquid can be contained. The type of liquid contained in the water tank is not particularly limited. For example, water can be contained. Alternatively, a liquid such as ethanol can be used, or an electrically insulating liquid such as silicone oil can be used.

[0060] The battery cell clamp secures the battery cells to prevent them from moving during volume measurement. As described above, the battery cell clamp includes: a first plate and a second plate; a bolt and a nut that secure the first and second plates with the battery cells interposed between them; and a spacer positioned between the first and second plates to define a separation distance, the spacer surrounding the bolt. The spacer includes a slit element that opens longitudinally.

[0061] Furthermore, the battery cell may be a pouch-type unit cell. Specifically, the pouch-type unit cell may have a structure in which an electrode assembly having a positive electrode / separator / negative electrode structure is embedded in an outer material of a laminate sheet while being connected to an electrode lead formed on the outer side of the outer material. The electrode lead may be led to the outer side of the sheet and may extend in the same or opposite directions.

[0062] Furthermore, the scale is used to measure the weight of the battery cell fixture containing the battery cells, and to measure the weight of the battery cell fixture outside the water tank and the weight of the battery cell fixture submerged in liquid. Here, the weight outside the water tank refers to the weight of the battery cell fixture in air. The scale can be a conventional scale for measuring weight. For example, the scale can be a spring scale or an electronic scale.

[0063] In one example, the battery cell volume measuring device further includes a charging and discharging unit that is electrically connected to the battery cell. The charging and discharging unit can supply power for charging to the secondary battery or receive discharge power from the secondary battery. Here, supplying power to the secondary battery is not limited to supplying power sufficient to fully charge the secondary battery. Supplying power to the secondary battery can also mean supplying power sufficient to measure the voltage of the first electrode lead and the second electrode lead to evaluate the performance of the secondary battery. This can also apply to the meaning of receiving discharge power from the secondary battery, so its repeated description is omitted here.

[0064] Furthermore, the present invention provides a battery cell volume measuring method performed by using the above-mentioned battery cell volume measuring device.

[0065] In one embodiment, the method of measuring the volume of a battery cell according to the present invention is performed by interposing the battery cell in a battery cell jig and then measuring the weight before and after the volume of the battery cell is changed, respectively.

[0066] In a specific embodiment, the method for measuring the volume of a battery cell according to the present invention includes: placing a battery cell in a battery cell fixture, and then measuring the weight of the battery cell fixture in the air; placing the battery cell fixture in a water tank containing a liquid, and then measuring the weight of the battery cell fixture in the liquid; and calculating the volume of the battery cell after the volume change using the following formula 1:

[0067] [Formula 1]

[0068]

[0069] Here, V represents the volume of the battery cell after the volume change, W1 represents the weight of the battery cell jig in the air, W2 represents the weight of the battery cell jig accommodated in the liquid, and ρ represents the density of the liquid.

[0070] As described above, the method for measuring the volume of a battery cell according to the present invention utilizes Archimedes' principle. Specifically, the difference between the weight of the battery cell before and after immersion in the liquid contained in the water tank can be the weight of the liquid, which increases in volume as the battery cell is immersed. In this case, since the weight of the liquid displaced by the battery cell as it immerses is equal to the buoyancy, the volume of the battery cell can be determined based on the measured buoyancy.

[0071] Likewise, according to the battery cell volume measurement method of the present invention, the volume of the battery cell can be measured in a non-destructive manner under normal pressure by measuring only the weight of the battery cell without punching the battery.

[0072] Furthermore, the steps of interposing the battery cell in the battery cell jig and then measuring the weight of the battery cell jig in the air are performed. At this time, the battery cell jig in which the battery cell is interposed may be weighed using a scale such as a spring scale.

[0073] Furthermore, the battery cell fixture is housed in a water tank containing a liquid. The type of liquid contained in the water tank is not particularly limited. For example, water can be used. Alternatively, a liquid such as ethanol or an electrically insulating liquid such as silicone oil can be used.

[0074] In another embodiment, measuring the weight of the battery cell fixture contained in the liquid includes heating the liquid to a predetermined temperature. In a specific example, the step of measuring the weight of the battery cell fixture in the liquid includes a process of charging and discharging the battery cell. During the charging and discharging process, the battery cell can be activated by charging and discharging the battery cell via a charging and discharging unit electrically connected to the battery cell.

[0075] Furthermore, by measuring the weight of the battery cell contained in the liquid, it is possible to measure the volume of internal gas generated during charging / discharging through the charging / discharging process.

[0076] Thereafter, in the method of measuring the volume of the battery cell according to the present invention, the volume change amount of the battery cell can be calculated by Formula 1 by using the weight of the battery cell measured in the air and the weight of the battery cell measured in the liquid.

[0077] In another embodiment, measuring the weight of the battery cell fixture in the liquid may include heating the liquid to a predetermined temperature. This process may be performed by a temperature control unit of the battery cell volume measuring device. For example, it may be performed by heating an iron plate surrounding the water tank. Here, the process of heating the liquid should be performed before the step of measuring the weight of the battery cell contained in the liquid. The temperature of the liquid may be measured by a temperature measuring unit such as a thermocouple, by which the liquid may be heated to a predetermined temperature.

[0078] Therefore, the method for measuring the volume of a battery cell according to the present invention also includes the step of calculating the volume change of the battery cell according to the temperature of the liquid. For example, after setting the temperature of the liquid to 45°C, 60°C, or 80°C and measuring the volume of the battery cell at each temperature, the volume change trend of the battery cell according to temperature can be obtained.

[0079] The present invention will be described in more detail below with reference to the accompanying drawings and other figures. Since the present invention allows for various variations and numerous embodiments, specific embodiments will be shown in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific forms disclosed, and should be understood to encompass all variations, equivalents, and alternatives within the spirit and scope of the invention.

[0080] (First embodiment)

[0081] Figure 3 is a right side cross-sectional view of a battery cell clamp including a spacer according to one embodiment of the present invention.

[0082] refer to Figure 3 The battery cell fixture 100 according to the present invention includes: a first plate 120 and a second plate 130; a bolt 140 and a nut 150 for fixing the first and second plates with the battery cell 110 interposed therebetween; and a spacer 160 positioned between the first and second plates to specify a separation distance and having a structure surrounding the bolt 140. The spacer 160 includes a slit unit 161 that opens in a longitudinal direction of the spacer 160.

[0083] Specifically, the spacer 160 is used to maintain a constant distance between the first plate 120 and the second plate 130, and has a structure that surrounds the bolt 140. At this time, the slit unit 161 of the spacer 160 is open from one side to the other side along the longitudinal direction of the spacer 160. That is, since the spacer 160 has a structure that is open along the longitudinal direction, it is possible to prevent water from stagnating in the spacer 160 or prevent gas from filling the spacer 160 when measuring the volume of the battery cell 110 using the Archimedes principle.

[0084] At this time, the height of spacer 160 corresponds to the height of battery cell 110 between first plate 120 and second plate 130. Therefore, the space between first plate 120 and second plate 130 can be easily adjusted. More specifically, the user allows battery cell 110 to be positioned on second plate 130 coupled with bolt 140, and spacer 160 is inserted into bolt 140. Thereafter, first plate 120 is coupled and fastened using nut 150.

[0085] The battery cell clamp 100 according to the present invention includes a plurality of bolts 140 and nuts 150. Specifically, the battery cell clamp 100 according to the present invention includes 4 to 12 bolts 140 and nuts 150, respectively. For example, the battery cell clamp 100 includes 10 bolts 140 and nuts 150, respectively. However, the present invention is not limited thereto.

[0086] Furthermore, the battery cell fixture 100 according to the present invention may have a structure in which the spacer 160 is fastened by at least one bolt 140. For example, by inserting the spacer 160 having the same height into each bolt 140, deviation pressure or fastening error at each position can be minimized.

[0087] (Second embodiment)

[0088] Figure 4 is a right side cross-sectional view of a battery cell clamp including a spacer according to another embodiment of the present invention.

[0089] refer to Figure 4 The battery cell fixture 200 according to the present invention includes: a first plate 220 and a second plate 230; a bolt 240 and a nut 250 for fixing the first and second plates with the battery cell 210 interposed therebetween; and a spacer 260 located between the first and second plates to specify a separation distance and having a structure surrounding the bolt 240. The spacer 260 includes a slit unit 261 that opens in a longitudinal direction of the spacer 260.

[0090] Specifically, the spacer 260 serves to maintain a constant distance between the first plate 220 and the second plate 230 and has a structure surrounding the bolt 240. At this time, the slit unit 261 of the spacer is opened from one side to the other side along the longitudinal direction of the spacer 260.

[0091] Specifically, the angle between the slit unit 261 and the center of the axis is within a range of 10 to 70 degrees (θ). Based on the cross-section of the spacer 260, the slit unit 261 of the spacer 260 is open within a range of 10 to 70 degrees (θ) relative to the center of the axis. For example, the slit unit 261 is open at an average of 60 degrees based on the axis of the spacer 260. Since the slit unit 261 is open at this angle, it is possible to prevent water from stagnating in the space between the battery cell clamp 200 and the spacer 260, or to prevent gas from filling the space.

[0092] In addition, the space between the first plate 220 and the second plate 230 can be adjusted by using the spacer 260, and when the volume change of the battery cell 210 is measured using the Archimedes principle, because the spacer 260 is opened at the above-mentioned angle, the volume change of the battery cell 210 can be measured after the spacer 260 is separated from the battery cell clamp 200.

[0093] Since each component has been described above, a detailed description of each component will be omitted here.

[0094] (Third embodiment)

[0095] Figure 5 is a block diagram illustrating each component of a battery cell volume measuring device according to still another embodiment of the present invention.

[0096] refer to Figure 5 The battery cell volume measurement device according to the present invention includes: a battery cell fixture 300; a water tank 370 containing liquid; and a scale 380 for measuring the weight of the battery cell fixture 300 containing the battery cell 310, both outside and inside the water tank 370. The battery cell volume measurement device according to the present invention uses Archimedes' principle to measure the volume change of the battery cell 310. More specifically, the volume change of the battery cell 310 can be calculated by calculating the difference between the weight of the battery cell 310 measured before the battery cell 310 is immersed in the liquid contained in the water tank 370 and the weight of the battery cell 310 after the battery cell 310 is immersed in the liquid.

[0097] The water tank 370 has a space capable of containing liquid therein. The type of liquid contained in the water tank 370 is not particularly limited. For example, water can be contained. Alternatively, a liquid such as ethanol can be used, or an electrically insulating liquid such as silicone oil can be used.

[0098] The battery cell jig 300 secures the battery cells 310 to prevent them from moving during volume measurement. As described above, the battery cell jig 300 includes: a first plate 320 and a second plate 330; bolts 340 and nuts 350 that secure the first and second plates with the battery cells 310 interposed therebetween; and a spacer (not shown) positioned between the first and second plates to define a separation distance and surrounding the bolts 340. The spacer includes a slit unit that opens in the longitudinal direction.

[0099] Furthermore, the scale 380 is used to measure the weight of the battery cell fixture 300 containing the battery cell 310 therein, and to measure the weight outside the water tank 370 and the weight in the liquid. Here, the weight outside the water tank 370 refers to the weight of the battery cell fixture 300 in air. The scale 380 can be a conventional scale for measuring weight. For example, the scale 380 can be a spring scale or an electronic scale. In the drawings, a spring scale is shown as the scale 380, but the present invention is not limited to this example.

[0100] In addition, the battery cell volume measurement device further includes a charging and discharging unit 390, which is electrically connected to the battery cell. The charging and discharging unit 390 can activate the battery cell by charging / discharging the electrode assembly electrically connected to the battery cell 310. At this time, the charging and discharging unit 390 can be electrically connected to the electrode lead of the battery cell 310 through a charging / discharging line (not shown).

[0101] Furthermore, the volume of internal gas generated during charging / discharging through the charging / discharging process can be measured by measuring the weight of the battery cells 310 accommodated in the liquid.

[0102] The present invention also provides a method for measuring the volume of a battery cell using the above-mentioned battery cell volume measuring device. In a specific example, the method for measuring the volume of a battery cell according to the present invention is performed by placing a battery cell in a battery cell fixture and then measuring the weight of the battery cell before and after the volume change.

[0103] As described above, the method for measuring the volume of a battery cell according to the present invention uses the Archimedes principle. Hereinafter, the method will be described in detail.

[0104] Figure 6 is a flow chart illustrating a method for measuring the volume of a battery cell according to yet another embodiment of the present invention.

[0105] refer to Figure 6 The method for measuring the volume of a battery cell according to the present invention includes: placing a battery cell in a battery cell fixture, and then measuring the weight of the battery cell fixture in the air (S10); placing the battery cell fixture in a water tank containing liquid, and then measuring the weight of the battery cell fixture in the liquid (S20); and calculating the volume change of the battery cell by the following formula 1 (S30):

[0106] [Formula 1]

[0107] V=(W1-W2) / ρ

[0108] Here, V represents the volume of the battery cell after the volume change, W1 represents the weight of the battery cell jig in the air, W2 represents the weight of the battery cell jig accommodated in the liquid, and ρ represents the density of the liquid.

[0109] As described above, the method for measuring the volume of a battery cell according to the present invention utilizes Archimedes' principle. Specifically, the difference between the weight of the battery cell before and after immersion in the liquid contained in the water tank can be the weight of the liquid, which increases in volume as the battery cell is immersed. In this case, since the weight of the liquid displaced by the battery cell as it immerses in the liquid is equal to the buoyancy, the volume of the battery cell can be determined based on the measured buoyancy.

[0110] Likewise, according to the battery cell volume measurement method of the present invention, the volume of the battery cell can be measured in a non-destructive manner under normal pressure by measuring only the weight of the battery cell without punching the battery.

[0111] Specifically, the weight W1 of the battery cell jig in which the battery cells in the air are interposed is measured, and after the charge / discharge process is performed in a state in which the battery cells are immersed in ethanol, the weight W2 of the battery cell jig accommodated in the liquid is measured.

[0112] At this time, the weight W1 of the battery cell holder in the air is 110 g, and the weight W2 of the battery cell holder contained in the liquid is 100 g. If the density of ethanol is ρ = 0.789 g / cm 3And the volume change of the battery cell is V, then the weight change of the battery cell is the same as the weight of the ethanol that has been pushed away, and the volume of the ethanol that has been pushed away is the same as the volume change of the battery cell caused by gas generation, that is, V. Therefore, in summary, ρ is (the weight of the ethanol that has been pushed away) / (the volume of the ethanol that has been pushed away). At this time, since the volume of the ethanol that has been pushed away is (the weight of the ethanol that has been pushed away) / ρ, V can be calculated by (110-100) / 0.789. That is, the volume change of the battery cell is approximately 12.674cm 3 .

[0113] The present invention has been described in more detail above with reference to the accompanying drawings and examples. Therefore, the embodiments described in the specification and the configurations depicted in the drawings are merely the most preferred embodiments of the present invention and do not represent the entire technical concept of the present invention. It should be understood that various equivalent forms and variations may exist to replace these at the time of filing this application.

[0114] [Description of Reference Numerals]

[0115] 10, 100, 200, 300: Battery cell fixture

[0116] 11, 110, 210, 310: battery cells

[0117] 12, 120, 220, 320: First board

[0118] 13, 130, 230, 330: Second board

[0119] 14, 140, 240, 340: bolts

[0120] 15, 150, 250, 350: nuts

[0121] 16, 160, 260: spacers

[0122] 161, 261: Slit unit

[0123] 370: Water tank

[0124] 380: Scale

[0125] 390: Charging and discharging unit

Claims

1. A battery cell fixture, comprising: a first plate and a second plate; Bolts and nuts, which fix the first plate and the second plate when the battery cell is interposed between the first plate and the second plate; as well as a spacer positioned between the first plate and the second plate to specify a separation distance and having a structure surrounding the bolt, wherein the spacer comprises a slit unit, the slit unit being located on a side wall of the spacer and opening along a longitudinal direction of the spacer, and wherein, after the first plate and the second plate are fastened by the bolts and the nuts, the spacer is located between the first plate and the second plate and surrounds the bolts, and the slit unit remains open along the longitudinal direction of the spacer, thereby preventing water from being retained in the spacer or preventing gas from being filled in the spacer when the volume of the battery cell is measured using the Archimedes principle.

2. The battery cell clamp according to claim 1, wherein: The slit unit of the spacer is opened from one side to the other side along the longitudinal direction.

3. The battery cell clamp according to claim 1, wherein: The slit unit of the spacer is open within a range of 10 to 70 degrees with respect to an axis center.

4. The battery cell clamp according to claim 1, wherein: The height of the spacer corresponds to the height of the battery cell interposed between the first plate and the second plate.

5. The battery cell clamp according to claim 1, wherein The battery cell clamp includes 4 to 12 bolts and nuts, respectively, and Wherein, the spacer is fastened by at least one bolt.

6. A device for measuring the volume of a battery cell, the device comprising: The battery cell clamp according to claim 1; a water tank containing liquid; as well as A weigher is provided for measuring the weight of the battery cell holder containing the battery cell at an outer side of the water tank and an inner side of the water tank, respectively. 7 . The device of claim 6 , further comprising a charging and discharging unit electrically connected to the battery cell. 8 . A method of measuring the volume of a battery cell by interposing a battery cell in the battery cell jig according to claim 1 and then respectively measuring the weight before and after the volume of the battery cell changes.

9. The method according to claim 8, comprising: placing the battery cell in the battery cell fixture and then measuring the weight of the battery cell fixture in air; placing the battery cell clamp in a water tank containing liquid, and then measuring the weight of the battery cell clamp in the liquid; as well as The volume of the battery cell after the volume change is calculated using the following formula 1: [Formula 1] Wherein, V represents the volume of the battery cell after the volume change, W1 represents the weight of the battery cell clamp in the air, W2 represents the weight of the battery cell clamp contained in the liquid, and ρ represents the density of the liquid.

10. The method according to claim 9, wherein: Measuring the weight of the battery cell fixture in the liquid can include charging and discharging the battery cell.

11. The method according to claim 9, wherein During the measuring of the weight of the battery cell clamp in the air and the measuring of the weight of the battery cell clamp in the liquid, the weight of the battery cell clamp is measured by using a spring balance.

12. The method according to claim 9, wherein Measuring the weight of the battery cell fixture in the liquid can include heating the liquid to a predetermined temperature.

13. The method according to claim 9, wherein: Calculating the volume of the battery cell after the volume change may include calculating the volume change of the battery cell according to the temperature of the liquid.

14. The method according to claim 9, wherein The liquid contained in the water tank is water, ethanol or silicone oil.

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