Method and device for determining expansive force of battery

Abstract

The embodiment of the invention discloses a method and a device for determining expansion force of a battery. The method for determining the expansion force of the battery comprises the steps of obtaining working parameters of a target battery; according to the working parameters, establishing an electrothermal coupling model of the charge-discharge cycle life of the target battery, and a cell mechanical equivalent model and a reverse coupling relationship of the target battery; and determining the charge-discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the cell mechanical equivalent model and the reverse coupling relationship. According to the method and the device for determining the expansion force of the battery provided by the embodiment of the invention, the expansion force determination reliability can be ensured.

Description

Technical Field

[0001] The embodiments of the present invention relate to battery technology, and more particularly to a method and device for determining the expansion force of a battery. Background Art

[0002] Batteries such as soft-pack batteries have the characteristics of small size, light weight, good safety performance, flexible design, and low self-discharge. They are widely used and the demand is increasing. During the charge and discharge process of soft-pack batteries, the embedding and extraction of ions in the electrode active materials will cause the battery to expand and shrink. Ideally, the volume change of the material during the embedding and extraction process should be reversible. However, in actual situations, some ions cannot be completely extracted from the anode due to changes in battery balance, or are deposited on the anode surface as insoluble byproducts during the cycle, causing the battery to expand irreversibly and causing serious consequences. Therefore, battery expansion has become a very important reliability issue in battery applications, and it is particularly important to predict the expansion process.

[0003] Currently, the existing method for determining the expansion force of a battery usually directly predicts the expansion force of the battery based on the health status of the battery, but the application of such method has the problem of low reliability. Summary of the invention

[0004] The embodiments of the present invention provide a method and device for determining the expansion force of a battery to ensure the reliability of the expansion force determination.

[0005] In a first aspect, an embodiment of the present invention provides a method for determining an expansion force of a battery, comprising:

[0006] Obtain the operating parameters of the target battery;

[0007] According to the operating parameters, an electrothermal coupling model of the charge-discharge cycle life of the target battery, as well as a cell mechanical equivalent model and a reverse coupling relationship of the target battery are established;

[0008] The charge-discharge cycle life and expansion displacement of the target battery are determined according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship.

[0009] Optionally, establishing an electrothermal coupling model of the charge-discharge cycle life of the target battery, and a cell mechanical equivalent model and a reverse coupling relationship of the target battery according to the operating parameters includes:

[0010] According to the operating parameters, the consumption rate of different components in the electrolyte of the target battery, the volume strain of the target battery, and the porosity and electrode thickness of the target battery are determined to determine the capacity retention rate of the target battery.

[0011] Optionally, the consumption rates of the different components include consumption rates of at least two components, wherein the consumption rates of the two components are respectively related to A and B, and are both related to C and D, wherein A, B, C, and D are all target parameters.

[0012] Optionally, determining the charge-discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship includes:

[0013] The target parameter AD is adjusted until the capacity retention rate of the target battery reaches a target value, at which time the capacity retention rate is the charge-discharge cycle life, and the expansion displacement is determined according to the volume strain at this time.

[0014] Optionally, the volume strain includes the positive electrode volume strain and the negative electrode volume strain, and the formula of the negative electrode volume strain is ΔV / V0=fvol(a(l.c_a) / csmax_p)+fsoh(cycle_no), wherein ΔV and V0 are the volume change rate and initial volume of the negative electrode respectively, fvol is the negative electrode volume strain function, a(l.c_a) is the real-time solid phase concentration of the negative electrode, csmax_p is the maximum solid phase concentration of the negative electrode, fsoh is the function of the solid electrolyte interface film thickness, and cycle_no is the number of charge and discharge cycles.

[0015] Optionally, the porosity of the target battery is Φ, Φ=(g-1)*Φ a,0 * Li +Φ0 / (Φ a,0 * Li +1), f ± =t / (R ion *S*k l,0 ), where g is the battery expansion coefficient, Φ a,0 is the initial volume fraction of active material, Li is the relative volume change rate, Φ0 is the initial porosity, f ± is the effective ion transfer factor, t is the electrode thickness, R ion is the ionic resistance related to the electrode stress, S is the cross-sectional area of ​​the electrode, k l,0 is the electrolyte conductivity.

[0016] Optionally, the values ​​of the target parameters AD are all greater than zero.

[0017] Optionally, the target battery is a soft-pack lithium-ion battery.

[0018] In a second aspect, an embodiment of the present invention provides a device for determining expansion force of a battery, comprising:

[0019] A parameter acquisition module, used to obtain the operating parameters of the target battery;

[0020] A model building module, used to establish an electrothermal coupling model of the charge-discharge cycle life of the target battery, as well as a cell mechanical equivalent model and a reverse coupling relationship of the target battery according to the operating parameters;

[0021] The expansion force determination module is used to determine the charge and discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship.

[0022] Optionally, the model building module is specifically used to determine the consumption rate of different components in the electrolyte of the target battery, the volume strain of the target battery, and the porosity and electrode thickness of the target battery according to the operating parameters, so as to determine the capacity retention rate of the target battery.

[0023] The expansion force determination method and device of the battery provided by the embodiment of the present invention comprises: obtaining the working parameters of the target battery; establishing the electrothermal coupling model of the charge and discharge cycle life of the target battery, and the battery cell mechanical equivalent model and reverse coupling relationship of the target battery according to the working parameters; determining the charge and discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship. The expansion force determination method and method of the battery provided by the embodiment of the present invention determines the charge and discharge cycle life and expansion displacement of the target battery according to the established electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship, such as determining the volume strain and irreversible capacity loss of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship, thereby determining the available capacity based on the battery capacity and the irreversible capacity loss, and determining the capacity retention rate, i.e., the charge and discharge cycle life, according to the available capacity, and determining the expansion displacement according to the volume strain, which can ensure the reliability of the expansion force, i.e., the charge and discharge cycle life and the expansion displacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of a method for determining expansion force of a battery provided in Embodiment 1 of the present invention;

[0025] Figure 2 is a schematic diagram of the electrical-thermal-mechanical coupling relationship of a battery provided in the first embodiment of the present invention;

[0026] Figure 3 is a schematic diagram of a battery cell mechanical equivalent model provided in the first embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of the local structure of a battery core mechanical equivalent model provided in the first embodiment of the present invention;

[0028] Figure 5 It is a schematic diagram of the local structure of another battery cell mechanical equivalent model provided in the first embodiment of the present invention;

[0029] Figure 6 is a flow chart of a method for determining expansion force of a battery provided in Embodiment 2 of the present invention;

[0030] Figure 7 is a schematic diagram of an expansion characteristic curve of a positive electrode material of a battery provided in the second embodiment of the present invention;

[0031] Figure 8 is a schematic diagram of a charge-discharge cycle life provided by the second embodiment of the present invention;

[0032] Fig. 9 is a schematic diagram of a curve of the relationship between expansion displacement and time provided in the second embodiment of the present invention;

[0033] Fig.10 is a schematic diagram of expansion displacement and number of cycles provided by the second embodiment of the present invention;

[0034] Fig.11 It is a structural block diagram of a device for determining expansion force of a battery provided in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0036] Embodiment 1

[0037] Figure 1 1 is a flow chart of a method for determining the expansion force of a battery provided in Embodiment 1 of the present invention. This embodiment can be applied to determining the expansion force of a battery such as a soft-pack battery. The method can be performed by a battery expansion force determination device, which can be integrated in an electronic device such as a computer. The device can be implemented in the form of software and / or hardware. The method specifically includes the following steps:

[0038] Step 110: Obtain operating parameters of the target battery.

[0039] Among them, the target battery is a soft-pack battery such as a soft-pack lithium-ion battery, and the operating parameters include the local current density of the negative electrode of the battery, aging parameters, SOC (State of Charge)-related expansion coefficient, SEI (solidelectrolyte interface) membrane exchange current density, temperature, temperature-related attenuation factor, negative electrode specific surface area, negative electrode temperature, negative electrode interface potential, number of charge and discharge cycles, battery liquid volume fraction, ionic conductivity, liquid volume fraction of SEI membrane and other required parameters.

[0040] Step 120: Establish an electrothermal coupling model of the charge-discharge cycle life of the target battery, as well as a cell mechanical equivalent model and reverse coupling relationship of the target battery according to the operating parameters.

[0041] Specifically, the battery capacity Q of the target battery is equal to the available capacity Q a The sum of the irreversible capacity loss ΔQ, that is, ΔQ = QQ a As the cycle progresses, Q a The capacity loss is decreasing while ΔQ is increasing. For the irreversible capacity loss ΔQ, the attenuation mechanism includes: 1) SEI film growth; 2) active lithium consumption of electrolyte; 3) lithium precipitation reaction. In the electrothermal coupling model, the reaction current density of the battery charge and discharge cycle process is characterized by adding the electrode reaction equation of the negative electrode, and the electrothermal coupling model is formed by the electrode reaction equation.

[0042] For example, Figure 2 Schematic diagram of the electrical-thermal-mechanical coupling relationship of a battery provided in Example 1 of the present invention. Figure 2 The electric-thermal-mechanical coupling of the battery is related to the battery's temperature, heat generation, relative volume change, porosity, etc. The above reverse coupling relationship is the reverse coupling relationship between solid mechanics and electrochemistry, that is, force and electricity. Figure 3 is a schematic diagram of a battery cell mechanical equivalent model provided in the first embodiment of the present invention, Figure 4 is a schematic diagram of a local structure of a battery cell mechanical equivalent model provided in the first embodiment of the present invention, Figure 5 Schematic diagram of the local structure of another battery cell mechanical equivalent model provided by the first embodiment of the present invention. Figure 3-Figure 5 , a three-dimensional solid mechanics equivalent model of the battery cell is established based on finite element simulation, namely the above-mentioned battery cell mechanics equivalent model, Figure 3 Boundaries 11, 12, 13, and 14 of the middle battery are fixed constraint boundaries, and boundaries 15 and 16 are normal fixed displacement boundaries; Figure 5 The structure in is Figure 4 In the enlarged structure of area A, materials 1, 2, 3, and 4 are materials with basic physical property parameters, among which materials 2 and 3 give the intercalation strain properties.

[0043] Step 130: Determine the charge-discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship.

[0044] Specifically, according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship, the volume strain and irreversible capacity loss ΔQ of the target battery are determined, so that the available capacity Q is determined based on the battery capacity Q and the irreversible capacity loss ΔQ. a , and according to the available capacity Q a Determine the capacity retention rate, i.e., the charge-discharge cycle life, and determine the expansion displacement based on the volume strain.

[0045] It should be noted that the specific value of the above preset offset step can be determined according to actual control requirements and is not limited here.

[0046] The method for determining the expansion force of a battery provided in the present embodiment determines the charge and discharge cycle life and expansion displacement of a target battery according to the established electrothermal coupling model, battery cell mechanical equivalent model and reverse coupling relationship. For example, the volume strain and irreversible capacity loss of the target battery are determined according to the electrothermal coupling model, battery cell mechanical equivalent model and reverse coupling relationship, thereby determining the available capacity based on the battery capacity and the irreversible capacity loss, and determining the capacity retention rate, i.e., the charge and discharge cycle life, according to the available capacity, and determining the expansion displacement according to the volume strain, thereby ensuring the reliability of the determination of the expansion force, i.e., the charge and discharge cycle life and the expansion displacement.

[0047] Embodiment 2

[0048] Figure 6 1 is a flow chart of a method for determining the expansion force of a battery provided in the second embodiment of the present invention. This embodiment can be applied to determining the expansion force of a battery such as a soft-pack battery. The method can be executed by a battery expansion force determination device, which can be integrated in an electronic device such as a computer. The device can be implemented in the form of software and / or hardware. The method specifically includes the following steps:

[0049] Step 210: Obtain operating parameters of the target battery.

[0050] Among them, the target battery is a soft-pack battery such as a soft-pack lithium-ion battery, and the operating parameters include the local current density of the negative electrode of the battery, aging parameters, SOC (State of Charge)-related expansion coefficient, SEI (solidelectrolyte interface) membrane exchange current density, temperature, temperature-related attenuation factor, negative electrode specific surface area, negative electrode temperature, negative electrode interface potential, number of charge and discharge cycles, battery liquid volume fraction, ionic conductivity, liquid volume fraction of SEI membrane and other required parameters.

[0051] Step 220: Determine the consumption rate of different components in the electrolyte of the target battery, the volume strain of the target battery, and the porosity and electrode thickness of the target battery according to the operating parameters to determine the capacity retention rate of the target battery.

[0052] Specifically, the consumption rates of different components include the consumption rates of at least two components, wherein the consumption rates of the two components are respectively related to A and B, and are both related to C and D, wherein A, B, C, and D are all target parameters, and the values ​​of the target parameters AD are all greater than zero. Exemplarily, I_SEI_dmc = -(1-H1*(liion.iloc_per1<0)*liion.iloc_per1 / i1C_loc*K(liion.cs_average / liion.csmax))*J*i1C_loc / (exp(alpha*(eta_DMC)*F_const / (R_const*T))+Q_DMC / Av_neg*f*J / i1C_loc)*exp(E_R_SEI / R_const*(1 / 298.15-1 / dom1)), I_SEI_ec =-(1-H2*(liion.iloc_per1<0)*liion.iloc_per1 / i1C_loc*K(liion.cs_average / liion.csmax))*J*i1C_loc / (exp(alpha*(eta_E C)*F_const / (R_const*T))+Q_EC / Av_neg*f*J / i1C_loc)*exp(E_R_SEI / R_const*(1 / 298.15-1 / dom1)), I_Li=ppb3*(ppb3<0&&cycle_ no>0)*20 / liion.epsl*(Ks_li), H1=A*1.394e–5 / epsl_SEI*exp(-(800 / R_const)*(1 / dom1-1 / 298.15)*exp(liion.cdc1.cycle_cou nter*0.2*t_factor / no_cycles), H2=B*1.394e-5 / epsl_SEI*exp(-(800 / R_const)*(1 / dom1-1 / 298.15))*exp(liion.cdc1.cycle_c ounter*0.2*t_factor / no_cycles), alpha=C*exp(-(30[kJ / mol] / R_const)*(1 / dom1-1 / 298.15[K])), f=D*exp(-(100[kJ / mol] / R_const)*(1 / dom1-1 / 298.15[K])), where I_SEI_dmc, I_SEI_ec, and I_Li are the consumption rates of different components, liion.iloc_per1 is the local current density of the negative electrode, i1C_loc is the 1C aging parameter, and K(liion.cs_average / liion.csmax) is the expansion coefficient related to the battery SOC, J is the exchange current density of the SEI film, alpha and f are both attenuation factors related to temperature, eta_DMC is the overpotential of DMC (dimethyl carbonate) in the battery, F_const is the Faraday constant, R_const is the gas constant, T is the temperature, Q_DMC is the reaction capacity of DMC, Av_neg is the specific surface area of ​​the negative electrode, E_R_SEI is the activation energy of SEI, 298.15K is the ambient temperature, dom1 is the negative electrode temperature, eta_EC is the EC (ethylene carbonate, ethylene carbonate), Q_EC is the reaction capacity of EC, ppb3 is the negative electrode interface potential, cycle_no is the number of cycles, liion.epsl is the volume fraction of the battery liquid phase, Ks_li is the Li ion conductivity, epsl_SEI is the liquid phase volume fraction of the SEI membrane, liion.cdc1.cycle_counter is the cycle count value, t_factor is the time factor, and no_cycles is the total number of cycles. The above equations form an electrothermal coupling model.

[0053] Furthermore, the stacked core part of the battery is equivalent to five layers, and the thickness of each layer is the equivalent thickness of the corresponding component. In addition to the conventional physical properties of the positive and negative electrode materials, the intercalation strain performance needs to be added to the material properties of the positive and negative electrodes. For the graphite negative electrode, it is regarded as a linear expansion, and due to the growth of the SEI film at the negative electrode interface, the expansion relationship of the negative electrode should be equal to the sum of the reversible expansion related to the concentration and the irreversible expansion related to the loss capacity. Therefore, the formula for the negative electrode volume strain is ΔV / V0=fvol(a(l.c_a) / csmax_p)+fsoh(cycle_no), where ΔV and V0 are the volume change rate and initial volume of the negative electrode, respectively, fvol is the negative electrode volume strain function, a(l.c_a) is the real-time solid phase concentration of the negative electrode, csmax_p is the maximum solid phase concentration of the negative electrode, fsoh is a function of the solid electrolyte interface film thickness, and cycle_no is the number of charge and discharge cycles. For the lithium iron phosphate positive electrode, it is considered to be a linear expansion and there is no irreversible expansion, so the positive electrode intercalation strain formula needs to be changed. The formula for the positive electrode volume strain is ΔV′ / V0′=2.2[cm^3 / mol]*(c-elpot.cEeqref), where ΔV′ and V0′ are the volume change rate and initial volume of the positive electrode, c is the positive electrode solid phase concentration, and elpot.cEeqref is the positive electrode reference concentration. The porosity of the target battery is Φ, Φ=(g-1)*Φ a,0 * Li +Φ0 / (Φ a,0 * Li+1), f ± =t / (R ion *S*k l,0 ), where g is the battery expansion coefficient, Φ a,0 is the initial volume fraction of active material, Li is the relative volume change rate, Φ0 is the initial porosity, f ± is the effective ion transfer factor, t is the electrode thickness, R ion is the ionic resistance related to the electrode stress, S is the cross-sectional area of ​​the electrode, k l,0 The above reverse coupling relationship can be expressed by the formula of electrolyte conductivity, porosity Φ and electrode thickness t.

[0054] Step 230, adjust the target parameter AD until the capacity retention rate of the target battery reaches the target value, where the capacity retention rate is the charge-discharge cycle life, and determine the expansion displacement based on the volume strain at this time.

[0055] Specifically, the consumption rates of different components include consumption rates of at least two components, wherein the consumption rates of the two components are respectively related to A and B, and are both related to C and D, wherein A, B, C, and D are all target parameters. Figure 7 is a schematic diagram of an expansion characteristic curve of a positive electrode material of a battery provided in the second embodiment of the present invention, Figure 8 is a schematic diagram of a charge-discharge cycle life provided by the second embodiment of the present invention, Fig. 9 is a schematic diagram of a curve of expansion displacement and time provided in the second embodiment of the present invention, Fig.10 Schematic diagram of expansion displacement and cycle number provided by the second embodiment of the present invention. Figure 7-10 , the expansion rate increases with the increase of SOC, the capacity retention rate decreases with the increase of the number of cycles, and the expansion displacement increases with the increase of the number of cycles. The target parameter AD is adjusted so that Figure 8 The simulation curve in is close to the test curve, so that the capacity retention rate obtained by the above-mentioned model simulation is close to the real value, ensuring the reliability of the expansion force determination. Figure 8 The target parameters corresponding to the charge and discharge cycle life are A 0.8, B 1.2, C 0.75, and D 1.3e 3 , the ambient temperature is 298.15K, and the charge and discharge cycle rate is 1C.

[0056] It should be noted that the specific size of each parameter in this embodiment can be determined according to actual control requirements and is not limited here.

[0057] The method for determining the expansion force of a battery provided in the present embodiment determines, based on the operating parameters, the consumption rate of different components in the electrolyte of the target battery (related to the target parameter AD), the volume strain of the target battery, and the porosity and electrode thickness of the target battery to determine the capacity retention rate of the target battery, and adjusts the target parameter AD until the capacity retention rate of the target battery reaches the target value. At this time, the capacity retention rate is the charge and discharge cycle life, and the expansion displacement is determined based on the volume strain at this time, which can ensure the reliability of determining the expansion force, i.e., the charge and discharge cycle life and the expansion displacement.

[0058] Embodiment 3

[0059] Fig.11 1 is a structural block diagram of a device for determining the expansion force of a battery provided by Embodiment 3 of the present invention. Fig.11 The battery expansion force determination device includes: a parameter acquisition module 310, a model building module 320 and an expansion force determination module 330. The parameter acquisition module 310 is used to acquire the working parameters of the target battery; the model building module 320 is used to establish the electric-thermal coupling model of the charge-discharge cycle life of the target battery, as well as the battery cell mechanical equivalent model and reverse coupling relationship of the target battery according to the working parameters; the expansion force determination module 330 is used to determine the charge-discharge cycle life and expansion displacement of the target battery according to the electric-thermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship.

[0060] Based on the above implementation, the model building module 320 is specifically used to determine the consumption rate of different components in the electrolyte of the target battery, the volume strain of the target battery, and the porosity and electrode thickness of the target battery according to the operating parameters to determine the capacity retention rate of the target battery.

[0061] In one embodiment, the consumption rates of the above-mentioned different components include the consumption rates of at least two components, wherein the consumption rates of the two components are respectively related to A and B, and are both related to C and D, wherein A, B, C, and D are all target parameters. The expansion force determination module 330 is specifically used to adjust the target parameter AD until the capacity retention rate of the target battery reaches the target value, at which time the capacity retention rate is the charge and discharge cycle life, and the expansion displacement is determined according to the volume strain at this time.

[0062] Optionally, the volume strain includes the positive electrode volume strain and the negative electrode volume strain. The formula of the negative electrode volume strain is ΔV / V0=fvol(a(l.c_a) / csmax_p)+fsoh(cycle_no), where ΔV and V0 are the volume change rate and initial volume of the negative electrode, respectively, fvol is the negative electrode volume strain function, a(l.c_a) is the real-time solid phase concentration of the negative electrode, csmax_p is the maximum solid phase concentration of the negative electrode, fsoh is the function of the solid electrolyte interface film thickness, and cycle_no is the number of charge and discharge cycles. The porosity of the target battery is Φ, Φ=(g-1)*Φ a,0 * Li +Φ0 / (Φ a,0 * Li +1), f ± =t / (R ion *S*k l,0 ), where g is the battery expansion coefficient, Φ a,0 is the initial volume fraction of active material, Li is the relative volume change rate, Φ0 is the initial porosity, f ± is the effective ion transfer factor, t is the electrode thickness, R ion is the ionic resistance related to the electrode stress, S is the cross-sectional area of ​​the electrode, k l,0 is the electrolyte conductivity.

[0063] The battery expansion force determination device and system provided in this embodiment and the battery expansion force determination method provided in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the battery expansion force determination method provided in any embodiment of the present invention.

[0064] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for determining the expansion force of a battery, characterized in that: include: Obtain the operating parameters of the target battery; According to the operating parameters, an electrothermal coupling model of the charge-discharge cycle life of the target battery, as well as a cell mechanical equivalent model and a reverse coupling relationship of the target battery are established; The charge-discharge cycle life and expansion displacement of the target battery are determined according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship.

2. The method for determining the expansion force according to claim 1, characterized in that: The step of establishing an electrothermal coupling model of the charge-discharge cycle life of the target battery and a cell mechanical equivalent model and a reverse coupling relationship of the target battery according to the operating parameters includes: According to the operating parameters, the consumption rate of different components in the electrolyte of the target battery, the volume strain of the target battery, and the porosity and electrode thickness of the target battery are determined to determine the capacity retention rate of the target battery.

3. The method for determining the expansion force according to claim 2, characterized in that: The consumption rates of the different components include consumption rates of at least two components, wherein the consumption rates of the two components are respectively related to A and B, and are both related to C and D, wherein A, B, C, and D are all target parameters.

4. The method for determining the expansion force according to claim 3, characterized in that: Determining the charge-discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship includes: The target parameter AD is adjusted until the capacity retention rate of the target battery reaches a target value, at which time the capacity retention rate is the charge-discharge cycle life, and the expansion displacement is determined according to the volume strain at this time.

5. The method for determining expansion force according to claim 2, characterized in that: The volume strain includes the positive electrode volume strain and the negative electrode volume strain. The formula of the negative electrode volume strain is ΔV / V0=fvol(a(l.c_a) / csmax_p)+fsoh(cycle_no), wherein ΔV and V0 are the volume change rate and initial volume of the negative electrode respectively, fvol is the negative electrode volume strain function, a(l.c_a) is the real-time solid phase concentration of the negative electrode, csmax_p is the maximum solid phase concentration of the negative electrode, fsoh is a function of the solid electrolyte interface film thickness, and cycle_no is the number of charge and discharge cycles.

6. The expansion force determination method according to claim 2, characterized in that: The porosity of the target battery is Φ, Φ = (g-1) * Φ a,0 * Li +Φ0 / (Φ a,0 * Li +1), f ± =t / (R ion *S*k l,0 ), where g is the battery expansion coefficient, Φ a,0 is the initial volume fraction of active materials, Li is the relative volume change rate, Φ0 is the initial porosity, f ± is the effective ion transfer factor, t is the electrode thickness, R ion is the ionic resistance related to the electrode stress, S is the cross-sectional area of ​​the electrode, k l,0 is the electrolyte conductivity.

7. The method for determining expansion force according to claim 3, characterized in that: The values ​​of the target parameters AD are all greater than zero.

8. The method for determining expansion force according to claim 1, characterized in that: The target battery is a soft-pack lithium-ion battery.

9. A device for determining the expansion force of a battery, characterized in that: include: A parameter acquisition module, used to obtain the operating parameters of the target battery; A model building module, used to establish an electrothermal coupling model of the charge-discharge cycle life of the target battery, as well as a cell mechanical equivalent model and a reverse coupling relationship of the target battery according to the operating parameters; The expansion force determination module is used to determine the charge and discharge cycle life and expansion displacement of the target battery according to the electrothermal coupling model, the battery cell mechanical equivalent model and the reverse coupling relationship.

10. The battery expansion force determination device according to claim 9, characterized in that: The model building module is specifically used to determine the consumption rate of different components in the electrolyte of the target battery, the volume strain of the target battery, and the porosity and electrode thickness of the target battery according to the operating parameters, so as to determine the capacity retention rate of the target battery.

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