Method, device and equipment for predicting swelling force of roll core of battery
By calculating the expansion strain and stress quotient of the battery coil core under the constraints of the shell and fixture as the elastic modulus, the expansion force of the next charge and discharge cycle is predicted, and the development progress delay caused by the monitoring of the expansion force of the battery coil core in the prior art is solved, and a rapid and accurate expansion force prediction is achieved.
Patent Information
- Application Number
- CN202311774914.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-21
- Publication Date
- 2025-06-24
AI Technical Summary
In the prior art, the expansion force monitoring of the battery coil core mainly relies on actual measurement, resulting in a long cycle time of the battery life cycle and delaying product development progress.
By obtaining the expansion strain and expansion stress of the core under the constraints of the housing and fixture, the quotient is calculated as the elastic modulus, and the expansion force of the next charge and discharge cycle is predicted.
This method can accurately predict the expansion force of the next charge and discharge cycle without waiting for the battery to enter the next charge and discharge cycle cycle and conduct actual measurements, greatly speeding up product development progress.
Smart Images
Figure CN120197328A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of batteries, and particularly to the technical field of predicting the swelling force of battery cores. Background Art
[0002] At present, the lithium negative electrode materials of batteries are mainly graphite-based, accounting for up to 98%. The specific capacities of graphite-based negative electrodes are all above 350 mAh / g, which is close to the upper limit of the theoretical specific capacity of 372 mAh / g. The theoretical specific capacity of silicon-based negative electrodes is up to 4200 mAh / g, which is more than 10 times that of graphite materials. Moreover, silicon can provide channels for lithium ions to embed and extract in all directions, and has excellent fast charging performance, which is the future development direction of negative electrodes. However, the serious volume expansion of silicon-based negative electrodes during the lithium embedding process restricts their commercial applications. The cycle life of battery cores is closely related to the swelling force caused by the expansion of negative electrode materials. Excessive or too small swelling force is not conducive to the cycle performance.
[0003] However, the current monitoring of the swelling force of battery cores still mainly relies on actual measurement, that is, charge and discharge cycles are carried out under the clamping of a fixture, and the swelling force data is obtained through real-time monitoring of the fixture force sensor. Its disadvantage is that the cycle time of the full life cycle of the battery is very long, ranging from several months to one year. Therefore, the current method of actually measuring the swelling force throughout the full life cycle of the battery greatly delays the product development progress. Summary of the Invention
[0004] The present disclosure provides a method, device, equipment, storage medium and vehicle for predicting the swelling force of a battery core.
[0005] According to a first aspect of the present disclosure, a method for predicting the swelling force of a battery core is provided. The method includes:
[0006] Obtaining the swelling strain of the core under the constraints of the housing and the fixture during a preset charge and discharge cycle; wherein, the battery includes a core and a housing wrapped around the core, and the fixture is arranged outside the housing for constraining the battery;
[0007] Obtaining the swelling stress of the core under the constraints of the housing and the fixture during a preset charge and discharge cycle;
[0008] Taking the quotient of the swelling stress and the swelling strain as the elastic modulus of the core in the next charge and discharge cycle of the preset charge and discharge cycle;
[0009] Predicting the swelling force of the core in the next charge and discharge cycle according to the elastic modulus of the core.
[0010] For the aspects and any possible implementation described above, a further implementation is provided. Obtaining the expansion strain of the core under the constraints of the housing and the fixture over a preset number of charge-discharge cycles includes:
[0011] Obtaining the reduction strain of the core under the constraints of the housing and the fixture, where the reduction strain is used to characterize the amount of expansion reduction of the core under the constraints of the housing and the fixture compared to without the constraints of the housing and the fixture.
[0012] Obtaining the edge thickness of the core and the thickness of the core's return frame, where the return frame is arranged between the housing and the fixture and is used to limit the expansion range of the core.
[0013] Substituting the reduction strain, the edge thickness of the core, and the thickness of the core's return frame into a preset strain calculation formula to obtain the expansion strain over a preset number of charge-discharge cycles.
[0014] For the aspects and any possible implementation described above, a further implementation is provided. Obtaining the reduction strain of the core under the constraints of the housing and the fixture includes:
[0015] Obtaining the actual unilateral expansion amount of the core under the constraint of the housing when it reaches a preset remaining battery charge.
[0016] Performing an expansion simulation of the core without the fixture constraint using the elastic modulus of a preset number of charge-discharge cycles to obtain the corresponding unilateral simulated expansion amount when the expansion amount of the core reaches the actual unilateral expansion amount. The initial value of the elastic modulus of the preset number of charge-discharge cycles is a preset value, and afterwards, the elastic modulus of the preset number of charge-discharge cycles can be updated to the elastic modulus of the next charge-discharge cycle.
[0017] Performing an expansion simulation of the core with the fixture constraint using the elastic modulus of the preset number of charge-discharge cycles to obtain the thickness of the return frame when the expansion force of the core reaches the preset maximum measured fixture force over the preset number of charge-discharge cycles.
[0018] Performing calculations using the thickness of the return frame and the unilateral simulated expansion amount to obtain the reduction strain of the core.
[0019] For the aspects and any possible implementation described above, a further implementation is provided. Obtaining the expansion stress of the core under the constraints of the housing and the fixture over a preset number of charge-discharge cycles includes:
[0020] Obtaining the fixture constraint force applied to the core.
[0021] Obtain the housing constraint force exerted on the core under the constraint of the housing;
[0022] Take the sum of the fixture constraint force exerted on the core and the housing constraint force exerted on the core as the expansion force exerted on the core under the constraints of the housing and the fixture;
[0023] Substitute the expansion force and the area of the side surface of the core in contact with the housing into a preset strain force calculation formula to obtain the expansion stress under a preset charge-discharge cycle.
[0024] For the aspects and any possible implementation manners as described above, a further implementation manner is provided. The obtaining of the housing constraint force exerted on the core under the constraint of the housing includes:
[0025] Perform an expansion simulation of the core without fixture constraint using the elastic modulus of a preset charge-discharge cycle to obtain the housing constraint force exerted on the core when the expansion amount of the core reaches the thickness of the core's return frame.
[0026] For the aspects and any possible implementation manners as described above, a further implementation manner is provided. The preset strain force calculation formula includes:
[0027] σ expan = F JR / S JR , where σ expan is the expansion stress under the preset charge-discharge cycle, F JR is the expansion force exerted on the core under the constraints of the housing and the fixture, and S JR is the area of the side surface of the core in contact with the housing, and S JR = the length of the non-wound part of the core * the width of the positive electrode tab.
[0028] For the aspects and any possible implementation manners as described above, a further implementation manner is provided. Calculate the elastic modulus difference between the elastic modulus of the core in the next charge-discharge cycle and the elastic modulus of the preset charge-discharge cycle;
[0029] Judge whether the elastic modulus difference is less than a preset modulus threshold;
[0030] If it is not less than, repeat the above steps until the elastic modulus difference is less than the preset modulus threshold, and then obtain the final elastic modulus of the core;
[0031] The predicting of the expansion force of the core in the next charge-discharge cycle according to the elastic modulus of the core includes:
[0032] Multiply the final elastic modulus of the core by the unilateral simulated expansion amount to obtain the expansion force of the core in the next charge-discharge cycle.
[0033] According to a second aspect of the present disclosure, there is provided a device for predicting the expansion force of a battery core. The device includes:
[0034] A first acquisition module for acquiring the expansion strain of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle; wherein, the battery includes a core and a housing wrapped around the core, and the fixture is arranged outside the housing for constraining the battery;
[0035] A second acquisition module for acquiring the expansion stress of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle;
[0036] A determination module for taking the quotient of the expansion stress and the expansion strain as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle;
[0037] A prediction module for predicting the expansion force of the core in the next charge-discharge cycle according to the elastic modulus of the core.
[0038] According to a third aspect of the present disclosure, there is provided an electronic device. The electronic device includes: a memory and a processor, and a computer program is stored on the memory, and when the processor executes the program, the method as described above is implemented.
[0039] According to a fourth aspect of the present disclosure, there is provided a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the method according to the first aspect of the present disclosure is implemented.
[0040] According to a fifth aspect of the present disclosure, there is provided a vehicle, which includes the device for predicting the expansion force of the battery core as described in the second aspect and / or the electronic device as described in the third aspect.
[0041] In the present disclosure, after calculating the expansion strain and expansion stress of the core at a preset charge-discharge cycle, the quotient of the expansion stress and the expansion strain can be used as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle. Then, by using the elastic modulus of the core, the expansion force of the core in the next charge-discharge cycle can be accurately predicted. Thus, the expansion force in the next charge-discharge cycle can be predicted by using the data of the previous charge-discharge cycles, and it is not necessary to continuously measure the expansion force in each charge-discharge cycle of the entire life cycle of the battery. In this way, without waiting for the battery to enter the next charge-discharge cycle and actually measuring the expansion force of the next charge-discharge cycle, the expansion force of the next charge-discharge cycle can be obtained, which greatly accelerates the product development progress.
[0042] It should be understood that the content described in the summary of the invention section is not intended to limit the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] With reference to the accompanying drawings and the following detailed description, the above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent. The drawings are used to better understand the solution and do not constitute a limitation to the present disclosure. In the drawings, the same or similar reference numerals represent the same or similar elements, where:
[0044] Figure 1 shows a flowchart of a method for predicting the expansion force of the core of a battery according to an embodiment of the present disclosure;
[0045] Figure 2 shows a force decomposition diagram of the core according to an embodiment of the present disclosure;
[0046] Figure 3 shows a flowchart of another method for predicting the expansion force of the core of a battery according to an embodiment of the present disclosure;
[0047] Figure 4 shows a schematic diagram of the corresponding relationship between the expansion force and the battery capacity according to an embodiment of the present disclosure;
[0048] Figure 5 shows a block diagram of a device for predicting the expansion force of the core of a battery according to an embodiment of the present disclosure;
[0049] Figure 6 shows a block diagram of an exemplary electronic device capable of implementing the embodiments of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.
[0051] In addition, the term "and / or" in this document is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally represents an "or" relationship between the preceding and following associated objects.
[0052] Figure 1 The flowchart of the core expansion force prediction method 100 of the battery according to the embodiment of the present disclosure is shown. The method 100 may include:
[0053] Step 110: Obtain the expansion strain of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle; wherein, the battery includes a core and a housing wrapped around the core, and the fixture is disposed outside the housing for constraining the battery;
[0054] When predicting the core expansion force, a fixture will be placed outside the battery cell to fix the battery cell.
[0055] In fact, there are many battery cells in the battery, and each battery cell is a core with a housing. Without the housing, it is a core. Of course, only one battery cell is used during the process of predicting the core expansion force.
[0056] Step 120: Obtain the expansion stress of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle;
[0057] One charge-discharge cycle refers to charging from 0% remaining power to 100% power, and then discharging from 100% power to 0% power; or discharging from 100% power to 0% power, and then charging from 0% remaining power to 100% power.
[0058] The preset charge-discharge cycle is the charge and discharge of the vehicle battery for a certain period. The preset charge-discharge cycle may be a mid-term charge-discharge cycle (such as charging and discharging to 80% of the rated capacity of the battery), and the next charge-discharge cycle may be an end-term charge-discharge cycle. Or the preset charge-discharge cycle may be an initial charge-discharge cycle (such as charging and discharging to 90% of the rated capacity of the battery), and the next charge-discharge cycle may be a mid-term charge-discharge cycle;
[0059] Specifically, the preset charge-discharge cycle can also be the i-th charge-discharge cycle in the middle charge-discharge cycle. At this time, the next charge-discharge cycle can be the i-th charge-discharge cycle in the end charge-discharge cycle; or the preset charge-discharge cycle can be the i-th charge-discharge cycle in the initial charge-discharge cycle. At this time, the next charge-discharge cycle can be the i-th charge-discharge cycle in the middle charge-discharge cycle. To reduce the calculation, i can be the last or the penultimate charge-discharge cycle in its corresponding (initial, middle or end) charge-discharge cycle.
[0060] The expansion strain refers to the amount of expansion of the core after charge and discharge. The expansion stress refers to the expansion force acting on a unit area.
[0061] The expansion strain is used to characterize the amount of expansion of the core under the constraints of the housing and the fixture during the preset charge-discharge cycle.
[0062] Step 130: Take the quotient of the expansion stress and the expansion strain as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle.
[0063] The general definition of "elastic modulus" is: stress divided by the strain in that direction under unidirectional stress state. Therefore, elastic modulus = expansion stress / expansion strain.
[0064] Since the elastic modulus remains generally unchanged under different charge-discharge cycles, the quotient of the expansion stress and the expansion strain under the preset charge-discharge cycle can be used as the elastic modulus of the next charge-discharge cycle.
[0065] Step 140: Predict the expansion force of the core in the next charge-discharge cycle according to the elastic modulus of the core.
[0066] After calculating the expansion strain and the expansion stress of the core under the preset charge-discharge cycle, the quotient of the expansion stress and the expansion strain can be taken as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle. Then, using the elastic modulus of the core, the expansion force of the core in the next charge-discharge cycle can be accurately predicted. Thus, the expansion force of the next charge-discharge cycle can be predicted using the data of the previous charge-discharge cycles, and it is not necessary to continuously measure the expansion force during each charge-discharge cycle of the entire life cycle of the battery. In this way, without waiting for the battery to enter the next charge-discharge cycle and measuring the expansion force of the next charge-discharge cycle, the expansion force of the next charge-discharge cycle can be obtained, which greatly accelerates the product development progress.
[0067] In some embodiments, obtaining the expansion strain of the core under the constraints of the housing and the fixture over a preset charge-discharge cycle period includes:
[0068] Obtaining the reduction strain of the core under the constraints of the housing and the fixture; wherein, the reduction strain is used to characterize the amount of expansion reduction of the core under the constraints of the housing and the fixture relative to the case without the constraints of the housing and the fixture.
[0069] The reduction strain is as Figure 2 Δh in JR
[0070] Obtaining the edge thickness of the core and the thickness of the core's return frame; wherein, the return frame is arranged between the housing and the fixture and is used to limit the expansion range of the core.
[0071] The function of the return frame is to reduce the expansion force of the core, thereby reducing F fixture and F fixture-end , avoiding excessive battery expansion force from affecting lithium plating, and avoiding excessive expansion force from affecting the assembly and stability of the battery.
[0072] Substituting the reduction strain, the edge thickness of the core, and the thickness of the core's return frame into a preset strain calculation formula to obtain the expansion strain over a preset charge-discharge cycle period.
[0073] Since the reduction strain is used to characterize the amount of expansion reduction of the core under the constraints of the housing and the fixture relative to the case without constraints (i.e., without the constraints of the housing and the fixture), and the expansion of the core is also closely related to the edge thickness of the core itself and the thickness of the outer return frame of the core, thus, substituting the reduction strain, the edge thickness of the core, and the thickness of the core's return frame into the preset strain calculation formula can automatically and accurately obtain the expansion strain over a preset charge-discharge cycle period.
[0074] The preset strain calculation formula can be:
[0075] ε expan = ΔL / L 当前值 , L 当前值 = h frame + h shell / 2, ΔL = Δh JR / 2, h frame is the thickness of the return frame (unit: mm), h shell is the edge thickness of the core (unit: mm), Δh JR is the reduction strain (unit: mm), ε expan is the expansion strain (unit: mm).
[0076] In some embodiments, obtaining the reduced strain of the core under the constraints of the housing and the fixture includes:
[0077] Obtaining the actual unilateral expansion amount of the core when reaching the preset remaining power under the constraint of the housing;
[0078] When the preset remaining power SOC is 100%, the predicted expansion force of the core in the next charge-discharge cycle is the maximum expansion force; as Figure 4 shown, the predicted is the maximum expansion force (i.e., the maximum expansion force obtained by simulation)
[0079] When the preset remaining power SOC is 0%, the predicted expansion force of the core in the next charge-discharge cycle is the minimum expansion force.
[0080] Performing expansion simulation of the core without fixture constraint using the elastic modulus of the preset charge-discharge cycle to obtain the corresponding unilateral simulation expansion amount when the expansion amount of the core reaches the actual unilateral expansion amount; among them, the initial value of the elastic modulus of the preset charge-discharge cycle is a preset value and then the elastic modulus of the preset charge-discharge cycle can be updated to the elastic modulus of the next charge-discharge cycle;
[0081] That is, the elastic modulus of the preset charge-discharge cycle can be preset or calculated. Specifically, the elastic modulus of the preset charge-discharge cycle is E i , E i 's initial value is preset according to experience. After that, E i can be continuously updated, and E i can be updated to E i+1 .
[0082] The actual unilateral expansion amount refers to the distance that the core expands in the direction of one side in contact with the housing (such as the upper surface direction in contact with the housing or the lower surface direction in contact with the housing), such as Figure 2 Δh in shell . Similarly, the unilateral simulation expansion amount is the corresponding theoretical expansion amount Δh output by the simulation software when reaching the actual unilateral expansion amount in the expansion simulation state free .
[0083] The specific simulation process is as follows: Input the elastic modulus Ei of the preset charge-discharge cycle and the theoretical expansion amount (i.e., the unilateral simulation expansion amount) into the simulation software. The simulation software will output an actual unilateral expansion amount, and then judge whether the actual unilateral expansion amount is consistent with the actual unilateral expansion amount Δh when the core reaches the preset remaining power shell . If not, readjust the input theoretical expansion amount until they are consistent, and take the theoretical expansion amount at this time as the final Δh freeThe simulation software for the core includes, but is not limited to, finite element analysis software.
[0084] Perform expansion simulation of the core under the constraint of the fixture using the elastic modulus of the preset charge-discharge cycle to obtain the thickness of the return frame when the expansion force of the core reaches the preset maximum measured force of the fixture under the preset charge-discharge cycle.
[0085] This simulation process can be: input the elastic modulus E of the preset charge-discharge cycle into the simulation software i and the expansion amount, and then continuously increase the expansion amount to make the core expand continuously, so that the expansion force also increases continuously until the expansion force corresponding to the expansion amount = the preset maximum measured force F of the fixture under the preset charge-discharge cycle fixture-end At this time, output the thickness h of the return frame frame .
[0086] Use the thickness of the return frame and the unilateral simulation expansion amount to perform calculations to obtain the reduction strain of the core.
[0087] The formula for obtaining the reduction strain of the core can be Δh free -h frame =Δh JR / 2, where Δh free is the unilateral simulation expansion amount of the core without the constraint of the fixture, h frame is the thickness of the return frame, and Δh JR is the reduction strain of the core.
[0088] In some embodiments, obtaining the expansion stress of the core under the constraints of the housing and the fixture under the preset charge-discharge cycle includes:
[0089] Obtain the fixture constraint force received by the core;
[0090] The fixture constraint force on the core is the increment of the expansion force ΔF recorded by the fixture force sensor fixture =F fixture-end -F fixture , where F fixture-end is the maximum value measured by the fixture force sensor under the preset charge-discharge cycle, and F fixture is the force applied by the fixture to the core.
[0091] Obtain the housing constraint force received by the core under the constraint of the housing;
[0092] Take the sum of the fixture constraint force received by the core and the housing constraint force received by the core as the expansion force received by the core under the constraints of the housing and the fixture;
[0093] Substitute the expansion force and the area of the side surface of the core in contact with the housing into a preset strain force calculation formula to obtain the expansion stress under a preset charge-discharge cycle.
[0094] The sum of the clamping force on the core and the housing force on the core under the housing constraint is exactly the expansion force on the core under the constraints of the housing and the clamp. Then, substitute this expansion force and the area of the side surface of the core in contact with the housing into the preset strain force calculation formula, and the expansion stress under the preset charge-discharge cycle can be accurately and automatically obtained.
[0095] The expansion stress σ of the core under the constraints of the clamp and the housing expan = F JR / S JR , where F JR is the expansion force (unit: N), and S JR = the length of the non-wound part * the width of the positive electrode tab, and S JR is the upper surface area of the core (unit: mm 2 ), in other words, S JR is the area of the upper surface of the core close to the housing side, and it is also the effective extrusion area of one side surface of the core (such as Figure 2 the upper side surface of the core close to the housing or the lower side surface of the core close to the housing in
[0096] ) under the action of the housing. The units of the length of the non-wound part and the width of the positive electrode tab are both mm.
[0097] In some embodiments, obtaining the housing force on the core under the housing constraint includes:
[0098] Performing expansion simulation of the core without clamp constraint using the elastic modulus of a preset charge-discharge cycle to obtain the housing force on the core when the expansion amount of the core reaches the thickness of the core's return frame. i Performing battery expansion simulation without clamp constraint using the elastic modulus E frame of a preset charge-discharge cycle, and obtaining the cross-sectional force F shell (the constraint force of the housing on the core)
[0099] The expansion simulation here can be: inputting the elastic modulus E i of a preset charge-discharge cycle and the expansion amount into the simulation software, and continuously adjusting the expansion amount until the expansion amount reaches the thickness h frame of the return frame. At this time, the force exerted by the core on the housing measured is the constraint force on the core.
[0100] In some embodiments, the preset strain force calculation formula includes:
[0101] σ expan = F JR / S JR , where σ expan is the swelling stress (unit: MPa) under the preset charge-discharge cycle, F JR is the swelling force (unit: N) exerted on the core under the constraints of the housing and the fixture, and S JR (unit: mm 2 ) is the area of the side of the core in contact with the housing, and S JR = the length of the non-wound part of the core * the width of the positive electrode tab.
[0102] In some embodiments, calculate the modulus of elasticity difference between the modulus of elasticity of the core in the next charge-discharge cycle and the modulus of elasticity of the preset charge-discharge cycle;
[0103] Determine whether the modulus of elasticity difference is less than a preset modulus threshold; the preset modulus threshold is the allowable iterative error value;
[0104] If it is not less than, repeat the above steps and update the modulus of elasticity of the preset charge-discharge cycle to the modulus of elasticity of the next charge-discharge cycle until the modulus of elasticity difference is less than the preset modulus threshold, then stop updating to obtain the final modulus of elasticity of the core;
[0105] Specifically, if the modulus of elasticity difference between the modulus of elasticity E i+1 in the next charge-discharge cycle and the modulus of elasticity E i in the preset charge-discharge cycle is not less than the preset modulus threshold ΔE, then let i = i + 1 (where i is the i-th charge-discharge cycle) and E i = E i+1 , and re-iterate and loop the above steps until the modulus of elasticity difference between the modulus of elasticity in the (m + 1)-th (at this time i = m + 1) charge-discharge cycle and the modulus of elasticity in its adjacent m-th charge-discharge cycle is less than the preset modulus threshold, then stop updating i and E i , and take the modulus of elasticity in this (m + 1)-th charge-discharge cycle as the final modulus of elasticity.
[0106] Predicting the swelling force of the core in the next charge-discharge cycle based on the modulus of elasticity of the core includes:
[0107] Multiplying the final modulus of elasticity of the core by the one-sided simulation swelling amount to obtain the swelling force of the core in the next charge-discharge cycle.
[0108] After calculating the elastic modulus obtained from two iterations, it is possible to determine whether the difference in elastic modulus is less than a preset modulus threshold. If it is not less than, it indicates that the difference in the elastic modulus calculated twice is large and inaccurate. Therefore, repeat the above steps, that is, take the next charge-discharge cycle as the preset charge-discharge cycle, and update the elastic modulus of the preset charge-discharge cycle to the elastic modulus of the next charge-discharge cycle, so as to re-iteratively calculate a new elastic modulus, and then obtain a new difference in elastic modulus until the difference in elastic modulus is less than the preset modulus threshold, then stop updating, and take the elastic modulus of the last obtained core as the final elastic modulus. Then multiply the final elastic modulus of the core by the unilateral simulation expansion amount to obtain the expansion force of the core in the next charge-discharge cycle.
[0109] Specifically, the unilateral simulation expansion amount Δh of the mid-term charge-discharge cycle free corresponds to 90% SOH. Therefore, if the final elastic modulus of the core * the unilateral simulation expansion amount Δh corresponding to 90% SOH free (that is, the mid-term Δh free ) is equal to the expansion force of the end-stage charge-discharge cycle.
[0110] The unilateral simulation expansion amount Δh of the initial charge-discharge cycle free corresponds to 100% SOH. Therefore, if the final elastic modulus of the core * the unilateral simulation expansion amount Δh corresponding to the initial 100% SOH free (that is, the initial Δh free ) is equal to the expansion force of the mid-term charge-discharge cycle.
[0111] As Figure 2 shown, during the battery expansion process, there are two sources of constraints on the core: the housing constraint force and the fixture loop frame constraint force, where the fixture and loop frame constraint force is the measured value of the force sensor on the fixture. Under the action of these two constraint forces, the reduced expansion amount due to the limited expansion deformation of the core is the main source of the expansion force. Based on the known core constraint force and the reduced expansion amount of the core under force, the elastic modulus during the core expansion process can be calculated according to the geometric dimensions of the core.
[0112] Specifically, the implementation manner of the present disclosure can be as Figure 3 shown:
[0113] Step 1: Take the battery (a prismatic battery can be taken as an example) with a fixture and cycle it to the mid-life stage. The pre-tightening force of the fixture at the BOL stage (the initial stage of the power battery life) is F fixture , and obtain the expansion force increment ΔF of the fixture force sensor during the mid-term cycle fixture = F fixture-end - F fixture , where F fixture-endThe maximum value (minimum value) of the clamp force sensor value measured in the last cycle of the mid-term cycle, that is, the preset maximum clamp measured force under the preset charge and discharge cycle period;
[0114] Step 2: Remove the fixture and measure the actual expansion of one side Δh when the remaining power of the battery reaches 100% SOC (or 0% SOC) in the unconstrained state (i.e. without the fixture but with the shell constrained) shell ;
[0115] Step 3: Preset the elastic modulus of the core expansion (the elastic modulus of the preset charge and discharge cycle) Ei, and use the elastic modulus of the preset charge and discharge cycle to perform expansion simulation without fixture constraints to obtain the actual expansion of one side of the battery to reach Δh xhell When the single-side simulation expansion is Δh free ;
[0116] Step 4: Use the preset elastic modulus E i Perform battery expansion simulation with fixture constraints and obtain the simulated fixture expansion force as F fixture-end When the thickness of the return frame is h frame ;
[0117] Step 5: Calculate the expansion and contraction strains of the core clamp and shell constraints in the last cycle of the mid-term cycle:
[0118] a) Under the constraints of the shell and the fixture, the shrinkage deformation Δh during the expansion of the core JR ;
[0119] b) The expansion strain ε of the core constrained by the fixture and shell during the last cycle of the mid-term cycle expan .
[0120] Step 6: Calculate the expansion stress of the core clamp and shell constraints in the last round of the mid-term cycle:
[0121] a) The clamping force on the core is the expansion force increment ΔF recorded by the clamp force sensor fixture ;
[0122] b) Use the preset elastic modulus Ei to simulate the battery expansion without fixture constraints, and obtain the actual expansion of the battery on one side to reach h frame When the core is subjected to the shell constraint force F shell ;
[0123] c) The last circle of the mid-term cycle, the expansion force F of the winding core constrained by the clamp and the shell JR =F shell +ΔF fixture ;
[0124] d) The last cycle of the mid-term cycle, the expansion stress σ of the winding core constrained by the clamp and the shell expan= F JR / S JR , where S JR = non - winding part length * positive electrode tab width, which is the effective squeezed area of the core.
[0125] Step 7: Calculate the core expansion elastic modulus E i+1 = σ expan / ε expan And iterate until E i+1 - E i < ΔE, where ΔE is the allowable iteration error value;
[0126] Step 8: Output the final estimated value of the core expansion elastic modulus E i+1 .
[0127] The following combines specific examples to further illustrate this technical solution.
[0128] Step 1: Cycle the battery (taking a square - shell battery as an example) with a fixture to the mid - life stage (89% SOH), and obtain the expansion force increment ΔF of the mid - cycle fixture force sensor fixture = F fixture-end - F fixture = 3556.84 N - 938.84 N = 2618 N;
[0129] Step 2: Remove the fixture and measure the unilateral actual expansion amount Δh when the remaining battery charge reaches 100% SOC under the unconstrained state (i.e., no fixture but with shell constraint) shell = 2.177 mm;
[0130] Step 3: Calibrate the material of the return - type frame through a unidirectional compression test and the material of the aluminum shell through a unidirectional tensile test. Preset the core expansion elastic modulus Ei = 8 MPa, and use this elastic modulus to perform battery expansion simulation without fixture constraint to obtain the unilateral actual expansion amount Δh shell When it is 2.177 mm, the unilateral unconstrained expansion amount Δh free (i.e., the unilateral simulation expansion amount) = 3.583 mm;
[0131] Step 4: Use the preset core elastic modulus of 8 MPa to perform battery expansion simulation with fixture constraint. When the simulation fixture expansion force F fixture-end is 3556.84 N, the thickness h frame of the return - type frame is 1.29 mm;
[0132] Step 5, Estimate the expansion reduction strain of the core under the fixture and shell constraint in the last turn of the mid - cycle:
[0133] a) Under the shell and fixture constraints, the reduction deformation Δh during the core expansion JR= f1(Δh free , h JR , h shell ,, h frrame ) = 2.586 mm, where h JR is the thickness of the BOL core, and h shell is the thickness of the edge of the large surface of the housing;
[0134] b) In the last lap of the mid-term cycle, the expansion strain ε of the core under the constraints of the fixture and the housing expan = f2(Δh JR , h shell , h frame ) = 0.4845 mm.
[0135] Step 6, Estimate the expansion stress of the core under the constraints of the fixture and the housing in the last lap of the mid-term cycle:
[0136] a) The force exerted by the fixture on the core is the increment of the expansion force λF recorded by the fixture force sensor fixture = 2618 N;
[0137] b) Use the preset elastic modulus Ei to perform a battery expansion simulation without fixture constraints to obtain the actual unilateral expansion amount h of the battery frame When it is 1.29 mm, the sectional force F of the core under the constraint of the housing shell = 685 N;
[0138] c) In the last lap of the mid-term cycle, the expansion force F of the core under the constraints of the fixture and the housing JR = F shell + ΔF fixture = 685 N + 2618 N = 3303 N;
[0139] d) In the last lap of the mid-term cycle, the expansion stress σ of the core under the constraints of the fixture and the housing expan = F JR / S JR = 3303 N / 125.6 mm / 87 mm = 0.3 MPa, where S JR = the length of the non-wound part * the width of the positive electrode tab = 125.6 mm * 87 mm = 10927.2 mm 2 , which is the effective extrusion area of the core.
[0140] Step 7: Calculate the expansion elastic modulus of the core.
[0141] E i+1 = σ expan / ε expan= 0.3 MPa / 0.4845 = 6.23 MPa and iterate. During the iteration process, it is found that when the battery expands freely, the center of the core is not restricted by the shell, and mainly the edge of the core supports the expansion of the shell. The actual expansion amount Δh on one side shell is not sensitive to the elastic modulus of the core, and the shell restraint force is slightly sensitive to the elastic modulus of the core.
[0142] Step 8: Set the allowable iteration error value ΔE = 0.1 MPa, and output the final estimated value E of the expansion elastic modulus of the core i+1 = 6.10 MPa, and then E i+1 * Δh in the middle stage frree = the expansion force at the end stage. The specific prediction results of the expansion force during the entire life cycle of the battery are as follows Figure 4 shown. As can be seen from Figure 4 it, the difference between the expansion force predicted by using the method of the present disclosure and the measured expansion force is not large, and the accuracy is high.
[0143] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present disclosure is not limited by the described action sequence, because according to the present disclosure, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present disclosure.
[0144] The above is the introduction of the method embodiments. The following further illustrates the solution of the present disclosure through device embodiments.
[0145] Figure 5 The block diagram of the core expansion force prediction device 500 of a battery according to an embodiment of the present disclosure is shown. As Figure 5 shown, the device 500 includes:
[0146] A first acquisition module 510, configured to acquire the expansion strain of the core under the constraints of the shell and the fixture during a preset charge-discharge cycle; wherein, the battery includes a core and a shell wrapped outside the core, and the fixture is arranged outside the shell to constrain the battery;
[0147] A second acquisition module 520, configured to acquire the expansion stress of the core under the constraints of the shell and the fixture during a preset charge-discharge cycle;
[0148] A determination module 530, configured to use the quotient of the expansion stress and the expansion strain as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle;
[0149] A prediction module 540, configured to predict the expansion force of the core in the next charge and discharge cycle according to the elastic modulus of the core.
[0150] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the described modules can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.
[0151] According to an embodiment of the present disclosure, the present disclosure further provides an electronic device, including:
[0152] At least one processor; and
[0153] A memory communicatively connected to the at least one processor; wherein,
[0154] The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute any one of the foregoing method embodiments.
[0155] According to an embodiment of the present disclosure, the present disclosure further provides a vehicle, including: the core expansion force prediction device of the battery as described in the foregoing embodiment or the electronic device as described in the foregoing embodiment.
[0156] According to an embodiment of the present disclosure, the present disclosure further provides a non-transitory computer-readable storage medium storing computer instructions, and the computer instructions are used to cause the computer to execute any one of the foregoing method embodiments.
[0157] Figure 6 FIG. shows a schematic block diagram of an electronic device 600 that can be used to implement the embodiments of the present disclosure. The electronic device is intended to represent various forms of digital computers, such as, a laptop computer, a desktop computer, a workbench, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, a personal digital processor, a cellular phone, a smart phone, a wearable device, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present disclosure described and / or claimed herein.
[0158] Device 600 includes a computing unit 601, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 602 or a computer program loaded from a storage unit 608 into a random access memory (RAM) 603. In the RAM 603, various programs and data required for the operation of the device 600 can also be stored. The computing unit 601, the ROM 602, and the RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.
[0159] Multiple components in the device 600 are connected to the I / O interface 605, including: an input unit 606, such as a keyboard, a mouse, etc.; an output unit 607, such as various types of displays, speakers, etc.; a storage unit 608, such as a magnetic disk, an optical disc, etc.; and a communication unit 609, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 609 allows the device 600 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.
[0160] The computing unit 601 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 601 include but are not limited to a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 601 executes the various methods and processes described above, such as method 100. For example, in some embodiments, method 100 can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as the storage unit 608. In some embodiments, part or all of the computer program can be loaded and / or installed onto the device 600 via the ROM 602 and / or the communication unit 609. When the computer program is loaded into the RAM 603 and executed by the computing unit 601, one or more steps of the method 100 described above can be executed. Alternatively, in other embodiments, the computing unit 601 can be configured to execute method 100 in any other appropriate way (e.g., by means of firmware).
[0161] The various embodiments of the systems and techniques described above in this specification can be implemented in digital electronic circuitry, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems-on-chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: being implemented in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which can be a special-purpose or general-purpose programmable processor that receives data and instructions from, and transmits data and instructions to, a storage system, at least one input device, and at least one output device.
[0162] The program code for implementing the methods of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowchart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine, or entirely on the remote machine or server.
[0163] In the context of this disclosure, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
[0164] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).
[0165] The systems and techniques described herein can be implemented in a computing system including backend components (e.g., as a data server), or a computing system including middleware components (e.g., an application server), or a computing system including frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system including any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected by digital data communication in any form or medium (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), and the Internet.
[0166] The computing system can include a client and a server. The client and the server are generally remote from each other and typically interact through a communication network. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, or a server of a distributed system, or a server incorporating a blockchain.
[0167] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps recited in this disclosure can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this is not limited herein.
[0168] The above specific embodiments do not constitute a limitation on the protection scope of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of this disclosure shall be included within the protection scope of this disclosure.
Claims
1. A method for predicting the swelling force of a battery core, characterized in that, Including: Obtaining the expansion strain of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle; wherein, the battery includes a core and a housing wrapped around the core, and the fixture is arranged outside the housing to constrain the battery; Obtaining the expansion stress of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle; Taking the quotient of the expansion stress and the expansion strain as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle; Predicting the expansion force of the core in the next charge-discharge cycle according to the elastic modulus of the core.
2. The method according to claim 1, wherein The obtaining of the expansion strain of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle includes: Obtaining the reduction strain of the core under the constraints of the housing and the fixture; wherein, the reduction strain is used to characterize the amount of expansion reduction of the core under the constraints of the housing and the fixture compared to without the constraints of the housing and the fixture; Obtaining the edge thickness of the core and the thickness of the core's return frame; wherein, the return frame is arranged between the housing and the fixture to limit the expansion range of the core; Substituting the reduction strain, the edge thickness of the core, and the thickness of the core's return frame into a preset strain calculation formula to obtain the expansion strain during a preset charge-discharge cycle.
3. The method according to claim 2, wherein The obtaining of the reduction strain of the core under the constraints of the housing and the fixture includes: Obtaining the actual unilateral expansion amount of the core when it reaches a preset remaining battery charge under the constraint of the housing; Performing an expansion simulation of the core without fixture constraint using the elastic modulus of the preset charge-discharge cycle to obtain the corresponding unilateral simulated expansion amount when the expansion amount of the core reaches the actual unilateral expansion amount; wherein, the initial value of the elastic modulus of the preset charge-discharge cycle is a preset value and the elastic modulus of the preset charge-discharge cycle can be updated to the elastic modulus of the next charge-discharge cycle later; Performing an expansion simulation of the core with fixture constraint using the elastic modulus of the preset charge-discharge cycle to obtain the thickness of the return frame when the expansion force of the core reaches the preset maximum measured fixture force in the preset charge-discharge cycle; Performing an operation using the return frame thickness and the unilateral simulated expansion amount to obtain the reduction strain of the core.
4. The method according to claim 1, characterized in that, The obtaining of the expansion stress of the core under the constraints of the housing and the fixture during a preset charge-discharge cycle includes: Obtaining the fixture constraint force received by the core; Obtaining the housing constraint force received by the core under the constraint of the housing; Taking the sum of the fixture constraint force received by the core and the housing constraint force received by the core as the expansion force received by the core under the constraints of the housing and the fixture; Substituting the expansion force and the area of the side surface of the core in contact with the housing into a preset stress calculation formula to obtain the expansion stress during a preset charge-discharge cycle.
5. The method according to claim 4, wherein The obtaining of the housing constraint force received by the core under the constraint of the housing includes: Using the elastic modulus of the preset charge-discharge cycle, perform an expansion simulation of the core under no fixture constraint to obtain the shell constraint force on the core when the expansion amount of the core reaches the thickness of the core's return frame.
6. The method according to claim 4, wherein The formula for the preset strain force includes: σ expan = F JR / S JR , where σ expan is the swelling stress under the preset charge-discharge cycle period, F JR is the swelling force exerted on the winding core under the constraints of the housing and the fixture, and S JR is the area of the side surface of the winding core in contact with the housing, and S JR = the length of the non-wound part of the winding core * the width of the positive electrode tab.
7. The method according to any one of claims 1 to 6, characterized in that Calculate the difference in elastic modulus between the elastic modulus of the core in the next charge-discharge cycle and the elastic modulus of the preset charge-discharge cycle; Determine whether the difference in elastic modulus is less than a preset modulus threshold; If it is not less than, repeat the above steps and update the elastic modulus of the preset charge-discharge cycle to the elastic modulus of the next charge-discharge cycle until the difference in elastic modulus is less than the preset modulus threshold, then stop the update to obtain the final elastic modulus of the core; Predicting the expansion force of the core in the next charge-discharge cycle according to the elastic modulus of the core includes: Multiply the final elastic modulus of the core by the unilateral simulation expansion amount to obtain the expansion force of the core in the next charge-discharge cycle.
8. A device for predicting the swelling force of a battery core, characterized in that, Includes: A first acquisition module for acquiring the expansion strain of the core under the constraint of the shell and the fixture in a preset charge-discharge cycle; wherein, the battery includes a core and a shell wrapped around the core, and the fixture is arranged outside the shell for constraining the battery; A second acquisition module for acquiring the expansion stress of the core under the constraint of the shell and the fixture in a preset charge-discharge cycle; A determination module for taking the quotient of the expansion stress and the expansion strain as the elastic modulus of the core in the next charge-discharge cycle of the preset charge-discharge cycle; A prediction module for predicting the expansion force of the core in the next charge-discharge cycle according to the elastic modulus of the core.
9. An electronic device, characterized in that, Includes: At least one processor; And A memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1-7.
10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that, The computer instructions are used to cause the computer to execute the method according to any one of claims 1-7.
11. A vehicle, characterized in that, Includes: The device according to claim 8, and / or the electronic device according to claim 9, and / or the readable storage medium according to claim 10.