Battery cell anomaly detection method and device and battery cell manufacturing method

Abstract

The invention discloses a battery cell anomaly detection method, a battery cell anomaly detection device and a battery cell manufacturing method. The battery cell anomaly detection method comprises the steps that a capacitance measurement value of a discharged battery cell after hot pressing treatment is obtained, the battery cell comprises a plurality of pole piece combinations, and each pole piece combination comprises a positive pole piece and a negative pole piece which are equivalent to an equivalent capacitor; and carrying out comparative calculation on the capacitance measurement value and a preset threshold value, and judging whether the pole piece distance between a positive pole piece and a negative pole piece included in the pole piece combination of the battery cell is abnormal or not according to a comparative result. According to the battery cell anomaly detection method, the capacitance measurement value of the discharged battery cell is obtained, comparison calculation is performed according to the capacitance measurement value, and whether the pole piece distance of the battery cell is abnormal or not can be judged according to the comparison result, so that screening monitoring of the pole piece distance of the battery cell in the manufacturing process of the battery cell is realized, the manufacturing quality risk of the manufacturing process is avoided, and the production efficiency is improved. Abnormal products are prevented from flowing out.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method and device for detecting abnormality of a battery cell, an electronic device, a storage medium and a method for manufacturing a battery cell. Background Art

[0002] In the manufacturing process of thin-film batteries, such as lithium-ion batteries, after the positive and negative electrodes and separators are wound and stacked, the inside of the winding core is affected by the electrode stress and the separator tension, which will cause the battery cell to expand and deform during the later charging and discharging process. To solve this problem, the existing technology usually preheats and hot presses after winding or stacking, releases the tension of the positive and negative electrodes and separators under high temperature and pressure conditions, and ensures the consistency of the spacing between the electrodes by shaping the battery cell to ensure the consistency of battery performance.

[0003] The existing technology for detecting the effect of hot pressing is currently usually carried out by pressure thickness measurement, but this method has poor response sensitivity to changes in the distance between the pole pieces, and cannot sensitively reflect the changes in the distance between the pole pieces and the diaphragm inside the battery cell. There is no applicable monitoring model and the recognition accuracy is low. When the distance between the pole pieces is too large, the lithium insertion path is lengthened, which will lead to problems such as lithium deposition. Summary of the invention

[0004] Based on this, it is necessary to provide a battery cell abnormality detection method, device, electronic device, storage medium and battery cell manufacturing method to address the technical problem that the existing technology cannot determine whether the electrode distance is abnormal during battery cell detection.

[0005] The present invention provides a method for detecting abnormality of a battery cell, comprising:

[0006] Obtaining a capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell comprises a plurality of electrode sheet assemblies, each of which comprises a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0007] The capacitance measurement value is compared with a preset threshold value, and according to the comparison result, it is determined whether the electrode distance between the positive electrode and the negative electrode included in the electrode combination of the battery cell is abnormal.

[0008] Further, the preset threshold is a preset spacing threshold, and the comparison and calculation based on the capacitance measurement value is performed, and according to the comparison result, whether the distance between the pole pieces of the battery cell is abnormal is judged, specifically including:

[0009] Calculate the average distance between pole pieces of a single layer based on the capacitance measurement value, where the average distance between pole pieces of a single layer is the average distance between the equivalent capacitors;

[0010] If the single-layer average pole piece spacing is greater than a preset spacing threshold, it is determined that the pole piece distance of the battery cell is abnormal.

[0011] Furthermore, the calculation of the single-layer average electrode spacing based on the capacitance measurement value specifically includes:

[0012] Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0013] The average single-layer pole piece spacing is calculated based on the average capacitance between the single-layer pole pieces.

[0014] Furthermore, the calculating the single-layer average pole piece spacing based on the average capacitance between the single-layer pole pieces specifically includes:

[0015] The average pole piece spacing of a single layer is calculated as:

[0016] d 均 =εS / C 均 4Πk, where C 均 is the average capacitance between the single-layer electrodes, d 均 is the average pole piece spacing of a single layer, ε is the dielectric constant, and k is the electrostatic force constant.

[0017] Further, the preset threshold is a preset average capacitance threshold, and the comparison and calculation based on the capacitance measurement value is performed, and according to the comparison result, whether the electrode distance of the battery cell is abnormal is judged, specifically including:

[0018] Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0019] If the average capacitance between the single-layer electrode pieces is less than a preset average capacitance threshold, it is determined that the electrode piece distance of the battery cell is abnormal.

[0020] Further, the preset threshold is a preset cell capacitance threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the electrode distance of the cell is abnormal according to the comparison result, specifically includes:

[0021] If the capacitance measurement value is less than a preset cell capacitance threshold, it is determined that the electrode distance of the cell is abnormal.

[0022] The present invention provides a battery cell abnormality detection device, comprising:

[0023] A capacitance measurement value acquisition module, used to obtain the capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell includes a plurality of electrode sheet combinations, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0024] The judgment module is used to compare and calculate the capacitance measurement value with a preset threshold value, and judge whether the electrode distance between the positive electrode and the negative electrode included in the electrode combination of the battery cell is abnormal according to the comparison result.

[0025] The present invention provides an electronic device, comprising:

[0026] at least one processor; and,

[0027] a memory communicatively connected to at least one of the processors; wherein,

[0028] The memory stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors so that the at least one processor can execute the battery cell abnormality detection method as described above.

[0029] The present invention provides a storage medium, wherein the storage medium stores computer instructions, and when a computer executes the computer instructions, it is used to execute all steps of the battery cell abnormality detection method as described above.

[0030] The present invention provides a method for manufacturing a battery core, comprising:

[0031] Performing a plurality of manufacturing processes before final welding of the battery core, wherein the manufacturing process before final welding of the battery core at least includes a hot pressing process;

[0032] Performing a final welding process to obtain a final welded battery cell, wherein the battery cell includes a layer or layers of electrode sheet assemblies subjected to a hot pressing process, wherein the electrode sheet assemblies include a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0033] After discharging the battery cell after final welding, measuring the capacitance value of the battery cell;

[0034] Execute all steps of the battery cell abnormality detection method as described above, and when it is determined that the electrode distance is abnormal, perform an alarm operation.

[0035] The battery cell abnormality detection method of the present invention obtains the capacitance measurement value of the battery cell after discharge. Since the battery cell includes a layer or a plurality of electrode pieces that are subjected to heat pressing treatment, the electrode piece combination includes a positive electrode piece and a negative electrode piece that are equivalent to an equivalent capacitor, and the capacitance value of the equivalent capacitor is affected by the electrode piece distance. Therefore, the capacitance measurement value is used for comparison and calculation. According to the comparison result, it is possible to determine whether the electrode piece distance of the battery cell is abnormal, thereby realizing the screening and monitoring of the electrode piece distance of the battery cell during the battery cell manufacturing process, avoiding the process manufacturing quality risk, and preventing the outflow of abnormal products. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flowchart of a method for detecting abnormality of a battery cell according to an embodiment of the present invention;

[0037] Figure 2 This is a working flow chart of a method for detecting abnormality of a battery cell according to another embodiment of the present invention;

[0038] Figure 3 The schematic diagram of the battery cell being equivalent to capacitors in parallel;

[0039] Figure 4 This is a working flow chart of a method for detecting abnormality of a battery cell in yet another embodiment of the present invention;

[0040] Figure 5 This is a working flow chart of a method for detecting abnormality of a battery cell in another embodiment of the present invention;

[0041] Figure 6 A flowchart of a method for manufacturing a battery cell according to the present invention;

[0042] Figure 7 is a curve diagram of capacitance value change before and after pressure release;

[0043] Figure 8 It is a curve diagram showing the change of capacitance value before and after releasing the pressure after applying different pressure values ​​to the battery cell;

[0044] Fig. 9 A flowchart of a method for manufacturing a battery cell according to a preferred embodiment of the present invention;

[0045] Fig.10 A schematic diagram of a battery cell abnormality detection device according to an embodiment of the present invention;

[0046] Fig.11 The figure is a schematic diagram of the hardware structure of an electronic device of the present invention. DETAILED DESCRIPTION

[0047] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. The same components are represented by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0048] like Figure 1 The flowchart of a method for detecting abnormality of a battery cell according to an embodiment of the present invention is shown, comprising:

[0049] Step S101, obtaining a capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell includes a plurality of electrode sheet assemblies, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0050] Step S102, comparing and calculating the capacitance measurement value with a preset threshold value, and judging whether the electrode distance between the positive electrode and the negative electrode included in the electrode assembly of the battery cell is abnormal according to the comparison result.

[0051] Specifically, the present invention can be applied to electronic devices having processing capabilities.

[0052] After the battery cell is discharged, the capacitance value of the battery cell is measured and input into the electronic device to execute step S101. The battery cell is pre-heated and pressed to heat-press one or more electrode sheets of the battery cell.

[0053] In some embodiments, the battery cell is a thin film battery cell.

[0054] Preferably, the battery cell is a lithium-ion battery cell.

[0055] Among them, thin film batteries, such as lithium-ion batteries, include a multi-layer electrode assembly, each electrode assembly includes a positive electrode and a negative electrode, and the positive electrode and the negative electrode can be equivalent to an equivalent capacitor, more specifically, the positive electrode and the negative electrode are equivalent to a parallel plate capacitor. The multi-layer electrode assembly is equivalent to multiple equivalent capacitors in parallel.

[0056] During the manufacturing process, the positive and negative electrodes of the battery cell are preheated and hot-pressed after winding or lamination. The electrode distance is the distance between the positive electrode and the negative electrode. During hot pressing, the electrode distance is small. After hot pressing, the electrode distance becomes larger due to the release of pressure. The change in the electrode distance will cause a change in the capacitance value of the equivalent capacitor equivalent to each layer of electrode combination. Therefore, step S102 is executed to compare and calculate the capacitance measurement value with the preset threshold value, and based on the comparison result, it is determined whether the electrode distance of the battery cell is abnormal.

[0057] The comparison and calculation of the capacitance measurement value may be performed by directly comparing the capacitance measurement value with a preset threshold, or the capacitance measurement value may be calculated and then the calculated value is compared with the preset threshold.

[0058] The battery cell abnormality detection method of the present invention obtains the capacitance measurement value of the battery cell after discharge. Since the battery cell includes a layer or a plurality of electrode pieces that are subjected to heat pressing treatment, the electrode piece combination includes a positive electrode piece and a negative electrode piece that are equivalent to an equivalent capacitor, and the capacitance value of the equivalent capacitor is affected by the electrode piece distance. Therefore, the capacitance measurement value is used for comparison and calculation. According to the comparison result, it is possible to determine whether the electrode piece distance of the battery cell is abnormal, thereby realizing the screening and monitoring of the electrode piece distance of the battery cell during the battery cell manufacturing process, avoiding the process manufacturing quality risk, and preventing the outflow of abnormal products.

[0059] like Figure 2 The flowchart of a method for detecting abnormality of a battery cell according to another embodiment of the present invention is shown, comprising:

[0060] Step S201, obtaining a capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell includes a plurality of electrode sheet combinations, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0061] Step S202, calculating a single-layer average electrode spacing based on the capacitance measurement value, wherein the single-layer average electrode spacing is an average spacing of the equivalent capacitor;

[0062] In one embodiment, the calculating the single-layer average electrode spacing based on the capacitance measurement value specifically includes:

[0063] Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0064] The average single-layer pole piece spacing is calculated based on the average capacitance between the single-layer pole pieces.

[0065] In one embodiment, the calculating the single-layer average pole piece spacing based on the average capacitance between the single-layer pole pieces specifically includes:

[0066] The average pole piece spacing of a single layer is calculated as:

[0067] d 均 =εS / C 均 4Πk, where C 均 is the average capacitance between the single-layer electrodes, d 均 is the average pole piece spacing of a single layer, ε is the dielectric constant, and k is the electrostatic force constant.

[0068] Step S203: If the single-layer average electrode spacing is greater than a preset spacing threshold, it is determined that the electrode spacing of the battery cell is abnormal.

[0069] Specifically, firstly, step S201 is executed to obtain the capacitance measurement value.

[0070] like Figure 3 As shown in the figure, the multi-layer electrode assembly of the battery cell is equivalent to multiple equivalent capacitors connected in parallel. Therefore, the capacitance measurement value C0 = C1 + C2 + ... + C n .

[0071] For each equivalent capacitor, its capacitance value is C = εS / 4πkd, where ε is the dielectric constant, which is related to the material system and can be defaulted to a fixed value, and k is the electrostatic force constant, generally k = 8.987551×10^9N·m 2 / C 2 , which is also a constant. S is the contact area of ​​the pole piece, and d is the distance between the pole pieces. Since the contact area of ​​the pole pieces is equal, and the difference in the distance between the pole pieces of different pole piece combinations is very small, it can be considered that C1=C2=C3=....=Cn , that is, C0 = nC 均 , where C 均 is the average capacitance between single-layer electrodes, and n is the number of positive electrode layers, that is, the number of equivalent capacitors.

[0072] Therefore, the average electrode spacing of a single layer can be calculated based on the capacitance measurement value C0.

[0073] In one embodiment, the calculating the single-layer average electrode spacing based on the capacitance measurement value specifically includes:

[0074] Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0075] The average single-layer pole piece spacing is calculated based on the average capacitance between the single-layer pole pieces.

[0076] Specifically, first calculate the average capacitance C between the single-layer electrodes 均 =C0 / n, where C0 is the capacitance measurement value.

[0077] Then, according to C 均 =εS / 4πkd 均 , we can calculate d 均 =εS / C 均 4Πk, where d 均 is the average pole piece spacing of a single layer.

[0078] Then, step S203 is executed, and if the single-layer average electrode spacing is greater than a preset spacing threshold, it is determined that the electrode spacing of the battery cell is abnormal.

[0079] The specific spacing threshold can be calibrated through experiments.

[0080] Among them, since the excessive pole piece distance is actually caused by the abnormality of the hot pressing process, the battery cell with abnormal pole piece distance is called the abnormal hot pressing battery cell, and the battery containing the abnormal hot pressing battery cell is called the abnormal hot pressing battery.

[0081] This embodiment establishes a model of the average single-layer pole piece spacing, thereby calculating the average single-layer pole piece spacing based on the capacitance measurement value, and screening out cells with excessive pole piece spacing based on the comparison between the average single-layer pole piece spacing and the spacing threshold.

[0082] like Figure 4 The flowchart of a method for detecting abnormality of a battery cell in another embodiment of the present invention is shown, comprising:

[0083] Step S401, obtaining a capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell includes a plurality of electrode sheet combinations, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0084] Step S402, using the capacitance measurement value, calculating the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0085] Step S403: If the average capacitance between the single-layer electrode pieces is less than a preset average capacitance threshold, it is determined that the electrode piece distance of the battery cell is abnormal.

[0086] Specifically, firstly, step S401 is executed to obtain the capacitance measurement value. Since the multi-layer electrode assembly of the battery cell is equivalent to multiple equivalent capacitors connected in parallel, and the capacitance value of each equivalent capacitor is equal, step S402 is executed to calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of the equivalent capacitors, that is:

[0087] Calculate the average capacitance C between single-layer electrodes 均 =C0 / n, where C0 is the capacitance measurement value.

[0088] And because C 均 =εS / 4πkd 均 Therefore, when the thermal pressure is abnormal, the distance between the battery cell electrodes changes. When the average distance between the single-layer electrodes is d 均 When C 均 Become smaller.

[0089] Therefore, step S403 is executed, and if the average capacitance between the single-layer electrode pieces is less than the preset average capacitance threshold, it is determined that the electrode piece distance of the battery cell is abnormal.

[0090] The specific average capacitance threshold can be calibrated through experiments.

[0091] This embodiment calculates the average capacitance between single-layer pole pieces based on the capacitance measurement value, and screens out cells with excessive pole piece distances based on a comparison between the average capacitance between single-layer pole pieces and the average capacitance threshold, thereby simplifying the calculation and improving the calculation efficiency.

[0092] like Figure 5 The flowchart of a method for detecting abnormality of a battery cell in another embodiment of the present invention is shown, comprising:

[0093] Step S501, obtaining a capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell includes a plurality of electrode sheet combinations, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0094] Step S502: If the capacitance measurement value is less than a preset cell capacitance threshold, it is determined that the electrode distance of the cell is abnormal.

[0095] Specifically, step S501 is executed to obtain the capacitance measurement value. Since the multi-layer electrode assembly of the battery cell is equivalent to multiple equivalent capacitors connected in parallel, the capacitance value of each equivalent capacitor is equal. 均 =εS / 4πkd 均 Therefore, when the thermal pressure is abnormal, the distance between the battery cell electrodes changes. When the average distance between the single-layer electrodes is d 均 When C 均 The capacitance measurement value C0=nC 均 Therefore, when the average pole piece spacing d 均 When C 均 Therefore, step S502 can directly determine the comparison result between the capacitance measurement value and the cell capacitance threshold, and if the capacitance measurement value is less than the preset cell capacitance threshold, it is determined that the electrode distance of the cell is abnormal.

[0096] This embodiment screens out cells with excessively large electrode distances based on the comparison between the capacitance measurement value and the cell capacitance threshold, thereby simplifying the calculation and improving the calculation efficiency.

[0097] like Figure 6 The flowchart of a method for manufacturing a battery cell according to the present invention is shown, comprising:

[0098] Step S601, executing a plurality of manufacturing processes before final welding of the battery cell, wherein the manufacturing process before final welding of the battery cell at least includes a hot pressing process;

[0099] Step S602, performing a final welding process to obtain a battery cell after final welding, wherein the battery cell includes a layer or layers of electrode sheet assemblies subjected to a hot pressing process, wherein the electrode sheet assembly includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0100] Step S603, discharging the battery cell after final welding, and measuring the capacitance value of the battery cell;

[0101] Step S604, executing all steps of the battery cell abnormality detection method as described above, and executing an alarm operation when it is determined that the electrode distance is abnormal.

[0102] Specifically, the battery cell manufacturing method of this embodiment first performs step S601 to perform a plurality of battery cell pre-final welding manufacturing processes.

[0103] In some embodiments, the battery cell is a thin film battery cell.

[0104] Preferably, the battery cell is a lithium-ion battery cell.

[0105] Among them, thin film batteries, such as lithium-ion batteries, include a multi-layer electrode assembly, each electrode assembly includes a positive electrode and a negative electrode, and the positive electrode and the negative electrode can be equivalent to an equivalent capacitor, more specifically, the positive electrode and the negative electrode are equivalent to a parallel plate capacitor. The multi-layer electrode assembly is equivalent to multiple equivalent capacitors in parallel.

[0106] In some embodiments, the manufacturing process before the final welding of the battery cell includes a winding / stacking process, a hot pressing process, a withstand voltage test (Hi-pot) process, and a pre-welding process in sequence.

[0107] During the hot pressing process, pressure is applied to the battery cell. Therefore, during hot pressing, the distance between the pole pieces is small. After hot pressing, the distance between the pole pieces becomes larger due to the release of pressure. The change in the distance between the pole pieces will cause the change in the capacitance value of the equivalent capacitor equivalent to each layer of pole piece combination.

[0108] Then, step S602 is executed to continue the final welding process. After the final welding process is completed, step S603 is executed to discharge the battery cell and measure the capacitance value.

[0109] Afterwards, step S603 is executed to execute the aforementioned battery cell abnormality detection method, and whether the electrode distance of the battery cell is abnormal is determined by the battery cell abnormality detection method.

[0110] Specifically, if Figure 7 The graph shows the change of capacitance value before and after the pressure is released, wherein the first capacitance curve 71 is a capacitance value change curve during and after the pressure is applied when the battery cell is hot pressed with a pressure of 1.5 tons for 15 minutes, and the second capacitance curve 72 is a capacitance value change curve during and after the pressure is applied when the battery cell is hot pressed with a pressure of 1.5 tons for 15 minutes at room temperature.

[0111] like Figure 8 The figure shows the change curves of the capacitance value before and after the pressure is released after different pressure values ​​are applied to the battery cell. The third capacitance curve 81 is the capacitance value change curve of applying 1.0 ton pressure to the battery cell for 10 minutes of hot pressing, the fourth capacitance curve 82 is the capacitance value change curve of applying 1.5 ton pressure to the battery cell for 10 minutes of hot pressing, and the fifth capacitance curve 83 is the capacitance value change curve of applying 2.0 ton pressure to the battery cell for 10 minutes of hot pressing.

[0112] It can be seen that after the pressure is released, the capacitance value of the battery cell drops significantly due to the increase in the distance between the electrodes. Therefore, the capacitance measurement value can be used to determine whether the distance between the electrodes is abnormal. When the distance between the electrodes is abnormal, an alarm operation is performed. The alarm operation includes but is not limited to: sound and light alarm, voice alarm, etc.

[0113] If there is no alarm, the final welding process is continued for the battery cell that is not judged to have abnormal electrode distance to obtain a finished product.

[0114] In some embodiments, the post-final welding process includes: a connecting piece welding process, a core joining process, a mylar wrapping process, and a shelling process.

[0115] The present invention adds a cell abnormality detection process to the existing cell manufacturing process, compares and calculates the capacitance measurement values, and judges whether the electrode distance of the cell is abnormal based on the comparison result, thereby realizing the screening and monitoring of the cell electrode distance in the cell manufacturing process, avoiding process manufacturing quality risks, and preventing abnormal products from flowing out.

[0116] In one embodiment, the manufacturing process before the final welding of the battery cell includes a withstand voltage test process, and after discharging the battery cell after the final welding, measuring the capacitance value of the battery cell specifically includes:

[0117] The battery cell after final welding is short-circuited and discharged within the discharge time through a short-circuit resistor, the resistance value of the short-circuit resistor is 0-1mΩ, and the discharge time is 0-60 seconds;

[0118] The capacitance value of the battery cell is measured after discharge.

[0119] After the withstand voltage test process is performed in this embodiment, the battery cell is fully discharged by discharging the short-circuit resistance value of 0-1 mΩ and the discharge time of 0-60s to avoid residual charge interference.

[0120] like Fig. 9 As shown, a working flow chart of a battery cell manufacturing method according to a preferred embodiment of the present invention includes:

[0121] Step S901, winding / lamination process;

[0122] Step S902, hot pressing process;

[0123] Step S903, Hi-pot process;

[0124] Step S904, pre-welding process;

[0125] Step S905, final welding process;

[0126] Step S906, discharging process;

[0127] Step S907, capacitance measurement process;

[0128] Step S908, connecting piece welding process;

[0129] Step S909, core closing process;

[0130] Step S910, Mylar film packaging process;

[0131] Step S911, shelling process.

[0132] Specifically, this embodiment adds a discharge and capacitance measurement process after the final welding process based on the existing implementation process of the battery cell mass production line. Among them, the winding / stacking process, hot pressing process, Hi-pot process, pre-welding process, final welding process, connecting piece welding process, core assembly process, Mylar packaging process, and shelling process are implemented using existing processes.

[0133] Among them, the discharge process short-circuits the positive and negative ears of the battery cell through the ear contact probes of the discharge equipment tooling.

[0134] The discharge equipment tooling has the following functions:

[0135] 1) The discharge equipment tooling is an existing discharge equipment. Since the battery cell needs to be fully discharged after hot pressing Hi-pot to avoid residual charge interference, a discharge equipment tooling with good conductivity and stability and its tab contact probe are selected, and the front end of the probe is needle-shaped to ensure that the contact resistance between the probe and the tab is ≤1mΩ, and the measurement resolution is required to be 0.1mΩ; and the discharge equipment tooling has the contact internal resistance measurement and specification setting, and exceeds the upper and lower limit alarm function;

[0136] 2) The discharge equipment tooling has the function of test time control, and the test time can be adjusted within 0-60S; it has the function of test time setting and exceeding the upper and lower limits alarm;

[0137] 3) The discharge equipment tooling can ensure and detect whether the battery cell is fully discharged, and has an automatic short-circuit verification function. It can automatically calibrate the equipment under no-load conditions regularly to eliminate measurement errors caused by the equipment's own contact internal resistance and residual charge;

[0138] 4) Each test line must have a separate metal (shielded) cable trough to prevent interference between wires;

[0139] The capacitance measurement process measures the battery cell through the capacitance measurement tooling equipment to obtain the capacitance measurement value of the battery cell, and based on the aforementioned battery cell abnormality detection method, determines whether the battery cell has an abnormal electrode distance. When measuring the battery cell capacitance, the battery cell should be kept in a natural state without stress to prevent the electrode distance from being disturbed by external forces.

[0140] Among them, the capacitance measurement tooling equipment has the following functions;

[0141] 1) Capacitance measurement requires the battery to be placed in a natural state. Therefore, the capacitance measurement equipment tooling selected has a range of 0-5000NF for measuring the capacitance of the battery cell (the actual range is selected according to the capacitance size). Each 1000NF is used as a gear, and the range is adjustable in 5 gears. The capacitor probe of the capacitance measurement equipment tooling is used to contact the positive and negative poles to measure the capacitance measurement value C0;

[0142] 2) Capacitance measurement can set the capacitance specification value, output the actual capacitance value record table, and have an alarm function if it exceeds the upper and lower limits of the capacitance specification;

[0143] 3) Capacitance measurement accuracy requirements: set value * 0.05% ± 1NF range, measurement resolution is 0.1NF; each test line must have a separate metal (shielded) wire trough to prevent interference between wires;

[0144] The capacitance measuring equipment has the function of setting compensation fitting by software formula. In addition to capacitance measurement control, it executes the battery cell abnormality detection method mentioned above, automatically converts the capacitance measurement value into the electrode spacing, and sets control and upper and lower limit alarms for the electrode spacing.

[0145] The conversion formula is C 均 =εS / 4πkd 均 , that is, d 均 =εS / C 均 4Πk, where C 均 is the average capacitance between single-layer electrodes, C 均 =C0 / n, where C0 is the capacitance measurement value and n is the number of positive electrode layers, i.e. the number of equivalent capacitors. 均 is the average electrode spacing of a single layer. ε is the dielectric constant, k is the electrostatic force constant, therefore, ε, π, k are constants, and S is the electrode contact area and is related to the battery cell project. Therefore, these four values ​​can be set and maintained, and the device can automatically perform C according to the above formula based on the capacitance strategy value. 均 , C0 and d.

[0146] The above monitoring variables are the average capacitance C of a single-layer electrode. 均 Or the distance between single-layer pole pieces d 均 To optimize the detection sensitivity, an external high-level signal amplifier can be connected to increase the recognition sensitivity and screen out batteries with abnormal quality.

[0147] This embodiment is preferably applicable to a case where the process is stable, that is, the relative area of ​​the electrode pieces remains stable, and the corresponding positive and negative electrode piece size alignment (overhang CPK) is ≥ 1.33.

[0148] Different from the existing hot pressing effect, which is measured by monitoring thickness with low sensitivity and large measurement error. This embodiment directly monitors the change of the pole piece spacing through the capacitance value, and has high responsiveness. At the same time, different from the defects of the hot pressing effect in the prior art that cannot be 100% detected for the microscopic pole piece spacing, this embodiment provides a measurement method that directly monitors the pole piece spacing 100%. This solution is sensitive to the fluctuation of the pole piece spacing, so it can effectively screen out batteries with abnormal hot pressing quality, avoid process manufacturing quality risks, and prevent abnormal products from flowing out.

[0149] The thermal pressure detection capacitor of this embodiment has high response sensitivity and can output the average pole piece spacing of a single layer. Thermal pressure anomaly detection can use an external signal amplifier to optimize the sensitivity of the first established model to improve detection reliability. This embodiment is simple to implement and is suitable for abnormal product screening and monitoring in the manufacturing process of soft-pack and aluminum-shell power batteries in winding and lamination methods.

[0150] Based on the same inventive concept, Fig.10 FIG. 1 is a schematic diagram of a battery cell abnormality detection device according to an embodiment of the present invention, comprising:

[0151] The capacitance measurement value acquisition module 1001 is used to obtain the capacitance measurement value of the battery cell after being subjected to heat pressing treatment and discharged, wherein the battery cell includes a plurality of electrode sheet combinations, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor;

[0152] The judgment module 1002 is used to compare and calculate the capacitance measurement value with a preset threshold value, and judge whether the electrode distance between the positive electrode and the negative electrode included in the electrode combination of the battery cell is abnormal according to the comparison result.

[0153] The battery cell abnormality detection method of the present invention obtains the capacitance measurement value of the battery cell after discharge. Since the battery cell includes a layer or a plurality of electrode pieces that are subjected to heat pressing treatment, the electrode piece combination includes a positive electrode piece and a negative electrode piece that are equivalent to an equivalent capacitor, and the capacitance value of the equivalent capacitor is affected by the electrode piece distance. Therefore, the capacitance measurement value is used for comparison and calculation. According to the comparison result, it is possible to determine whether the electrode piece distance of the battery cell is abnormal, thereby realizing the screening and monitoring of the electrode piece distance of the battery cell during the battery cell manufacturing process, avoiding the process manufacturing quality risk, and preventing the outflow of abnormal products.

[0154] In one embodiment, the preset threshold is a preset spacing threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the electrode distance of the battery cell is abnormal according to the comparison result, specifically includes:

[0155] Calculate the average distance between pole pieces of a single layer based on the capacitance measurement value, where the average distance between pole pieces of a single layer is the average distance between the equivalent capacitors;

[0156] If the single-layer average pole piece spacing is greater than a preset spacing threshold, it is determined that the pole piece distance of the battery cell is abnormal.

[0157] In one embodiment, the calculating the single-layer average electrode spacing based on the capacitance measurement value specifically includes:

[0158] Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0159] The average single-layer pole piece spacing is calculated based on the average capacitance between the single-layer pole pieces.

[0160] In one embodiment, the calculating the single-layer average pole piece spacing based on the average capacitance between the single-layer pole pieces specifically includes:

[0161] The average pole piece spacing of a single layer is calculated as:

[0162] d 均 =εS / C 均 4Πk, where C 均 is the average capacitance between the single-layer electrodes, d 均 is the average pole piece spacing of a single layer, ε is the dielectric constant, and k is the electrostatic force constant.

[0163] In one embodiment, the preset threshold is a preset average capacitance threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the electrode distance of the battery cell is abnormal according to the comparison result, specifically includes:

[0164] Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors;

[0165] If the average capacitance between the single-layer electrode pieces is less than a preset average capacitance threshold, it is determined that the electrode piece distance of the battery cell is abnormal.

[0166] In one embodiment, the preset threshold is a preset cell capacitance threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the electrode distance of the cell is abnormal according to the comparison result, specifically includes:

[0167] If the capacitance measurement value is less than a preset cell capacitance threshold, it is determined that the electrode distance of the cell is abnormal.

[0168] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0169] like Fig.11 The figure shows a hardware structure diagram of an electronic device of the present invention, including:

[0170] at least one processor 1101; and,

[0171] A memory 1102 is communicatively connected to at least one of the processors 1101; wherein:

[0172] The memory 1102 stores instructions that can be executed by at least one of the processors. The instructions are executed by at least one of the processors so that the at least one processor can execute the battery cell abnormality detection method as described above.

[0173] Fig.11 A processor 1101 is taken as an example.

[0174] The electronic device may further include: an input device 1103 and a display device 1104 .

[0175] The processor 1101, the memory 1102, the input device 1103 and the display device 1104 may be connected via a bus or other means, and the figure takes the connection via a bus as an example.

[0176] The memory 1102 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the battery cell abnormality detection method in the embodiment of the present application, for example, Figure 1 , Figure 2 , Figure 4 , Figure 5 The processor 1101 executes various functional applications and data processing by running the non-volatile software programs, instructions and modules stored in the memory 1102, that is, the battery cell abnormality detection method in the above embodiment is implemented.

[0177] The memory 1102 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created according to the use of the battery cell abnormality detection method, etc. In addition, the memory 1102 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 1102 may optionally include a memory remotely arranged relative to the processor 1101, and these remote memories may be connected to a device for executing the battery cell abnormality detection method via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0178] The input device 1103 can receive user clicks and generate signal inputs related to user settings and function control of the battery cell abnormality detection method. The display device 1104 can include display devices such as a display screen.

[0179] The one or more modules are stored in the memory 1102 , and when executed by the one or more processors 1101 , the cell abnormality detection method in any of the above method embodiments is executed.

[0180] The battery cell abnormality detection method of the present invention obtains the capacitance measurement value of the battery cell after discharge. Since the battery cell includes a layer or a plurality of electrode pieces that are subjected to heat pressing treatment, the electrode piece combination includes a positive electrode piece and a negative electrode piece that are equivalent to an equivalent capacitor, and the capacitance value of the equivalent capacitor is affected by the electrode piece distance. Therefore, the capacitance measurement value is used for comparison and calculation. According to the comparison result, it is possible to determine whether the electrode piece distance of the battery cell is abnormal, thereby realizing the screening and monitoring of the electrode piece distance of the battery cell during the battery cell manufacturing process, avoiding the process manufacturing quality risk, and preventing the outflow of abnormal products.

[0181] An embodiment of the present invention provides a storage medium, wherein the storage medium stores computer instructions. When a computer executes the computer instructions, the storage medium is used to execute all steps of the battery cell abnormality detection method as described above.

[0182] In the context of the present disclosure, a storage medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or apparatus. The storage medium may be a machine-readable signal medium or a machine-readable storage medium. Alternatively, the storage medium may be a non-temporary computer-readable storage medium, for example, a non-temporary computer-readable storage medium may be a ROM, a random access memory (Random Access Memory, RAM), a compact disc read-only memory (Compact Disc ROM, CD-ROM), a magnetic tape, a floppy disk, and an optical data storage device, etc.

[0183] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for detecting abnormality of a battery cell, characterized in that: include: Obtaining a capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell comprises a plurality of electrode sheet assemblies, each of which comprises a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor; The capacitance measurement value is compared with a preset threshold value, and according to the comparison result, it is determined whether the electrode distance between the positive electrode and the negative electrode included in the electrode combination of the battery cell is abnormal.

2. The method for detecting abnormality of a battery cell according to claim 1, characterized in that: The preset threshold is a preset spacing threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the distance between the pole pieces of the battery cell is abnormal according to the comparison result, specifically includes: Calculate the average distance between pole pieces of a single layer based on the capacitance measurement value, where the average distance between pole pieces of a single layer is the average distance between the equivalent capacitors; If the single-layer average pole piece spacing is greater than a preset spacing threshold, it is determined that the pole piece distance of the battery cell is abnormal.

3. The method for detecting abnormality of a battery cell according to claim 2, characterized in that: The calculating the single-layer average electrode spacing based on the capacitance measurement value specifically includes: Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors; The average single-layer pole piece spacing is calculated based on the average capacitance between the single-layer pole pieces.

4. The method for detecting abnormality of a battery cell according to claim 3, characterized in that: The calculating the single-layer average pole piece spacing based on the average capacitance between the single-layer pole pieces specifically includes: The average pole piece spacing of a single layer is calculated as: d 均 =εS / C 均 4Πk, where C 均 is the average capacitance between the single-layer electrodes, d 均 is the average pole piece spacing of a single layer, ε is the dielectric constant, and k is the electrostatic force constant.

5. The method for detecting abnormality of a battery cell according to claim 1, characterized in that: The preset threshold is a preset average capacitance threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the electrode distance of the battery cell is abnormal according to the comparison result, specifically includes: Using the capacitance measurement value, calculate the average capacitance between the single-layer electrode pieces as the capacitance measurement value divided by the number of equivalent capacitors; If the average capacitance between the single-layer electrode pieces is less than a preset average capacitance threshold, it is determined that the electrode piece distance of the battery cell is abnormal.

6. The method for detecting abnormality of a battery cell according to claim 1, characterized in that: The preset threshold is a preset cell capacitance threshold, and the comparison and calculation based on the capacitance measurement value, and judging whether the electrode distance of the cell is abnormal according to the comparison result, specifically includes: If the capacitance measurement value is less than a preset cell capacitance threshold, it is determined that the electrode distance of the cell is abnormal.

7. A battery cell abnormality detection device, characterized in that: include: A capacitance measurement value acquisition module, used to obtain the capacitance measurement value of a battery cell after hot pressing and discharge, wherein the battery cell includes a plurality of electrode sheet combinations, each of which includes a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor; The judgment module is used to compare and calculate the capacitance measurement value with a preset threshold value, and judge whether the electrode distance between the positive electrode and the negative electrode included in the electrode combination of the battery cell is abnormal according to the comparison result.

8. An electronic device, characterized in that: include: at least one processor; as well as, a memory communicatively connected to at least one of the processors; wherein, The memory stores instructions that can be executed by at least one of the processors, and the instructions are executed by at least one of the processors so that at least one of the processors can execute the battery cell abnormality detection method as described in any one of claims 1 to 6.

9. A storage medium, characterized in that: The storage medium stores computer instructions, and when a computer executes the computer instructions, it is used to execute all steps of the battery cell abnormality detection method as described in any one of claims 1 to 6.

10. A method for manufacturing a battery cell, characterized in that: include: Performing a plurality of manufacturing processes before final welding of the battery core, wherein the manufacturing process before final welding of the battery core at least includes a hot pressing process; Performing a final welding process to obtain a final welded battery cell, wherein the battery cell includes a layer or layers of electrode sheet assemblies subjected to a hot pressing process, wherein the electrode sheet assemblies include a positive electrode sheet and a negative electrode sheet that are equivalent to an equivalent capacitor; After discharging the battery cell after final welding, measuring the capacitance value of the battery cell; Execute all steps of the battery cell abnormality detection method as described in any one of claims 1 to 6, and perform an alarm operation when it is determined that the electrode distance is abnormal.

Images