A lithium ion battery alternating current internal resistance calculation method based on physical parameter analysis

Abstract

The application discloses a lithium ion battery AC internal resistance calculation method based on physical parameter analysis, and total internal resistance is obtained by adding internal resistances of a positive pole piece, a negative pole piece, a connecting piece and a structural piece, that is, the lithium ion battery AC internal resistance. The application has the following beneficial effects: high efficiency: without battery manufacturing, internal resistance evaluation can be completed in the design stage, and the cycle is shortened to 1-2 days; high precision: compared with actual detection data, the step-by-step calculation model error is less than 6%; universality: compatible with different materials (ternary, lithium iron phosphate, etc.) and battery types; accurate positioning of internal resistance problem points, reduction of optimization cost, and benefit to improvement of the internal resistance of the battery structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery AC internal resistance calculation method based on physical parameter analysis. BACKGROUND

[0002] As a core energy storage device in the field of new energy, the AC internal resistance of a lithium ion battery is one of the key parameters for measuring the performance of the battery, directly affects the energy conversion efficiency, cycle life and safety, and is an important basis for battery design optimization and performance evaluation.

[0003] At present, the test of the AC internal resistance of a lithium ion battery in the industry mainly relies on the actual measurement method after the completion of the physical battery: the designer needs to make a complete battery according to different material formulas (such as ternary, lithium iron phosphate, etc.) or structural designs (such as cylindrical, soft package, square), and then test it through an internal resistance meter to compare the influence of different schemes on the internal resistance of the battery. However, this method has significant limitations:

[0004] Long cycle: from the preparation of the pole piece, the winding of the battery core / sheet, the packaging to the liquid injection and formation, the complete battery production cycle is as long as 7-15 days, which seriously restricts the research and development iteration efficiency;

[0005] High cost: a large amount of raw materials (such as positive and negative active materials, current collector foil, electrolyte, etc.) and equipment resources are consumed for each design verification, and multiple sample preparation will greatly increase the research and development cost;

[0006] Insufficient flexibility: if the test results do not meet the expectations, the design needs to be adjusted and the test needs to be repeated, which leads to an inefficient cycle of the "design-verification-optimization" process.

[0007] For example, the invention application with the publication number CN117110922A discloses a lithium battery AC internal resistance test method and system, which includes: detecting the lithium battery to be tested, collecting the initial AC voltage of the lithium battery to be tested when no predetermined excitation current is injected, and collecting the sampling AC voltage when the predetermined excitation current is injected; detecting the compensation circuit, collecting the compensation AC voltage when the predetermined excitation current is injected; inverting and superimposing the compensation AC voltage and the sampling AC voltage to obtain the final AC voltage, and calculating the AC internal resistance of the lithium battery according to the final AC voltage, the predetermined excitation current and the initial AC voltage.

[0008] The application with the publication number CN109799392A discloses a lithium battery AC internal resistance testing method, which comprises the following steps: a positive half cycle sinusoidal voltage signal is generated by a sinusoidal signal generation circuit and input into a signal conversion circuit; the signal conversion circuit converts the positive half cycle sinusoidal voltage signal into a sinusoidal current and inputs the sinusoidal current into a sampling channel switching circuit; the sampling channel switching circuit selects a channel through which the sinusoidal current flows, and the generated sinusoidal voltage signal is input into a phase comparison and measurement circuit and a DSP sampling and control circuit; the phase comparison and measurement circuit generates two capture signals and inputs the two capture signals into the DSP sampling and control circuit; the DSP sampling and control circuit samples the sinusoidal voltage signal, and the DSP sampling and control circuit captures and calculates the time difference of the high level of the two capture signals; the impedance and the power factor are calculated by using the AD values and the time difference of the different channels, and the AC internal resistance is calculated by using the impedance and the power factor.

[0009] With the rapid growth of demand for high energy density and long life batteries in the field of new energy vehicles and energy storage systems, the traditional internal resistance evaluation method relying on physical testing has been difficult to meet the urgent requirements of the industry for research and development efficiency. Therefore, a rapid internal resistance calculation method based on material parameters and structural characteristics without manufacturing physical batteries is urgently needed to shorten the verification period, reduce the research and development cost, and promote the rapid innovation of lithium ion battery technology. SUMMARY

[0010] The present application provides a lithium ion battery AC internal resistance calculation method based on physical parameter analysis to solve the above problems in the prior art.

[0011] A lithium ion battery AC internal resistance calculation method based on physical parameter analysis, the lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, a connecting piece and a structural piece, the positive electrode sheet comprises a positive electrode current collector, a positive electrode coating and a positive electrode tab, the negative electrode sheet comprises a negative electrode current collector, a negative electrode coating and a negative electrode tab, and the lithium ion battery AC internal resistance calculation method comprises the following steps: obtaining the internal resistance of the positive electrode sheet, the negative electrode sheet, the connecting piece and the structural piece respectively and adding them to obtain the total internal resistance, which is the lithium ion battery AC internal resistance;

[0012] Wherein, when obtaining the internal resistance of the positive electrode sheet and the negative electrode sheet, the internal resistance of the positive electrode current collector and the negative electrode current collector is calculated based on the tab current distribution thermodynamic model; the internal resistance of the positive electrode coating and the negative electrode coating is calculated based on the double-sided parallel model and the interface resistance theory by actually measuring the coating layer resistivity and the interface surface resistivity; the internal resistance of the positive electrode sheet is the sum of the internal resistances of the positive electrode current collector, the positive electrode coating and the positive electrode tab, and the internal resistance of the negative electrode sheet is the sum of the internal resistances of the negative electrode current collector, the negative electrode coating and the negative electrode tab;

[0013] The internal resistance of the connecting piece is the product of the resistivity of the connecting piece and the length of the connecting piece divided by the cross-sectional area of the connecting piece;

[0014] The internal resistance of the structural member is obtained by actual measurement.

[0015] Preferably, the connecting member comprises a single welding tab or an adapter connected with the cover plate.

[0016] The structural member comprises a shell, a cap and a cover plate, and the shell is a steel shell or an aluminum shell.

[0017] Preferably, the positive electrode tab and the negative electrode tab are full-tab or tab-free structures, and the internal resistance calculation formula of the positive electrode current collector and the negative electrode current collector is: R 集流体 =ρ 集流体 L 集流体 / (3S 集流体 ), wherein R 集流体 is the internal resistance of the current collector, ρ 集流体 is the resistivity of the current collector, L 集流体 is the length of the current collector, and S 集流体 is the cross-sectional area of the current collector, and each parameter is the corresponding parameter of the positive electrode current collector when calculating the positive electrode current collector, and each parameter is the corresponding parameter of the negative electrode current collector when calculating the negative electrode current collector.

[0018] Preferably, the positive electrode tab and the negative electrode tab are multi-tab structures, and the internal resistance calculation formula of the positive electrode current collector and the negative electrode current collector is: Rx=R 集流体 / (4X 2 ), wherein R 集流体 is the internal resistance of the current collector, X is the number of tabs on the current collector, Rx represents the internal resistance value of the current collector under X tabs, and each parameter is the corresponding parameter of the positive electrode current collector when calculating the positive electrode current collector, and each parameter is the corresponding parameter of the negative electrode current collector when calculating the negative electrode current collector.

[0019] Preferably, the material ratio, surface density and thickness of the double-sided dressing layer in the double-sided parallel model are consistent.

[0020] Preferably, the internal resistance calculation formula of the positive electrode dressing and the negative electrode dressing is: R 涂敷 =(1 / 2) ×(ρ 敷料 / S 敷料 +ρ 界面 / S 敷料 ), wherein R 涂敷 is the sum of the internal resistance of the dressing layer and the interface resistance, ρ 敷料 is the surface resistivity of the dressing layer, ρ 界面 is the interface surface resistivity, S 敷料 is the area of the dressing layer, and each parameter is the corresponding parameter of the positive electrode dressing when calculating the positive electrode dressing, and each parameter is the corresponding parameter of the negative electrode dressing when calculating the negative electrode dressing.

[0021] Preferably, when calculating the internal resistance of the positive tab and the negative tab, the internal resistance of a single tab is R 单极耳, multiple tab superimposed parallel resistance R 极耳 , R 单极耳 =ρ 极耳 L 极耳 / S 极耳 , wherein, ρ 极耳 is the tab foil resistivity, L 极耳 is the tab length, S 极耳 is the tab cross-sectional area, R 极耳 =R 单极耳 / X, X is the number of tabs,

[0022] When calculating the positive tab, each parameter is the corresponding parameter of the positive tab, and when calculating the negative tab, each parameter is the corresponding parameter of the negative tab.

[0023] Preferably, the material of the positive current collector and the negative current collector is independently selected from at least one of aluminum foil, copper foil and stainless steel foil.

[0024] Preferably, the lithium ion battery is a ternary lithium battery, a lithium iron phosphate battery, a lithium manganate battery, a lithium iron manganese phosphate battery or a lithium-rich manganese-based battery.

[0025] Preferably, the lithium ion battery is a cylindrical battery, a soft package battery or a square battery.

[0026] Advantages of the present application:

[0027] 1. High efficiency: without making the battery, the internal resistance evaluation can be completed in the design stage, and the cycle is shortened to 1-2 days.

[0028] 2. High precision: compared with the actual detection data, the step-by-step calculation model error is less than 6%.

[0029] 3. Universality: compatible with different materials (ternary, lithium iron phosphate, etc.) and battery types.

[0030] 4. Accurate positioning of internal resistance problem points, reducing optimization cost, beneficial to the improvement of cell structure internal resistance. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a lithium ion battery internal resistance composition diagram.

[0032] Figure 2 is an electrode sheet schematic diagram. DETAILED DESCRIPTION

[0033] A lithium ion battery AC internal resistance fast calculation method based on physical parameter analysis, the lithium ion battery includes a current collector, a pole piece coating layer (i.e. the active material layer of the positive or negative electrode) material, a tab, a connecting piece, a structural piece; the current collector is an aluminum foil, a copper foil or a stainless steel foil; the pole piece coating layer material is a ternary, lithium iron phosphate, lithium manganate, lithium iron manganate or lithium-rich manganese-based positive electrode material, graphite, hard carbon, soft carbon or silicon-carbon negative electrode material; the connecting piece includes a single-welded tab or an adapter connected with a cover plate; the structural piece is a shell, a cap or a cover plate.

[0034] As Figure 1 shown is the composition diagram of the lithium ion battery AC internal resistance.

[0035] The calculation method includes the following steps:

[0036] Step 1: Based on the current distribution thermodynamic model derivation, the current collector internal resistance is calculated.

[0037] (1) Full tab structure: R 集流体 =ρ 集流体 L 集流体 / (3S 集流体 ), wherein R 集流体 is the current collector internal resistance, ρ 集流体 is the resistivity, L 集流体 is the length, S 集流体 is the cross-sectional area, and when calculating the positive electrode current collector, each parameter is the corresponding parameter of the positive electrode current collector; when calculating the negative electrode current collector, each parameter is the corresponding parameter of the negative electrode current collector.

[0038] The heat generation calculation derivation formula includes the following steps:

[0039] Full tab, such as large cylindrical battery, after coating, there will be a certain height of current collector for rubbing flat; no tab, such as 18650 battery, adopts the way of single-welded tab. The current flow of full tab and no tab structure is different.

[0040] Full tab or no tab structure calculation formula:

[0041] Q=I 2 R 集流体 t;

[0042] Q=Q1+Q2+……+Q n ;

[0043] I 2 R 集流体 t=((I / n) 2 +(2I / n) 2 ……+(nI / n) 2 )×ρL / (nS)×t;

[0044] R 集流体 = =ρL / (3S).

[0045] Where Q represents heat generation, I represents current, and R... 集流体 The current collector represents the internal resistance, t represents time, and n represents the current collector being divided into n groups.

[0046] (2) Multipole structure (X poles): Rx = R 集流体 / (4X 2 ).

[0047] Formula for calculating the structure of a multi-electrode (equally divided into X electrodes):

[0048] One electrode internal resistance R1:

[0049] 1 / R1=1 / (R 集流体 / (4X);

[0050] R1=R 集流体 / (4X 2 )=R 集流体 / 4.

[0051] Multiple electrode internal resistance Rx:

[0052] 1 / Rx=1 / (R 集流体 / (4X))+1 / (R 集流体 / (4X))+……+1 / (R 集流体 / (4X)), a total of X groups 1 / (R) 集流体 Add (4X) together;

[0053] Rx=R 集流体 / (4X 2 );

[0054] Rx represents the internal resistance of the current collector under X tabs. When calculating the positive current collector, all parameters are the corresponding parameters of the positive current collector; when calculating the negative current collector, all parameters are the corresponding parameters of the negative current collector.

[0055] Step 2: Bifacial parallel model + theoretical estimation of interface resistance

[0056] like Figure 2 The diagram shows the structure of the electrode sheet. Both sides of the current collector in the positive and negative electrodes of a lithium battery are coated with a coating layer, hence the term "double-sided." Similarly, the interface is formed between the coating layer and both sides of the current collector. The internal resistance of the coating areas on both sides of the current collector is connected in parallel through the current collector itself. The interface resistance refers to the resistance between the coating layer and the current collector.

[0057] In step 2, the material ratio, surface density, and thickness of the double-sided parallel model are consistent.

[0058] The positive / negative electrode sheet surface resistivity ρ is measured by a four-probe electrode resistance test system (four-probe resistance tester) 敷料 And the interface surface resistivity (the resistivity between the electrode sheet and the current collector) ρ 界面 The electrode sheet and interface internal resistance and are R 涂覆 .

[0059] R 涂敷 = (1 / 2) × ((ρ 敷料 / L 敷料 ) × L 敷料 / S 敷料 + (ρ 界面 / L 界面 ) × L 界面 / S 敷料 ) = (1 / 2) × (ρ 敷料 / S 敷料 + ρ 界面 / S 敷料 );

[0060] Wherein, L 敷料 is the thickness of the electrode sheet, L 界面 is the distance of the electron transport interface, S 敷料 is the area of the electrode sheet, and each parameter is the corresponding parameter of the positive electrode sheet when calculating the positive electrode sheet, and each parameter is the corresponding parameter of the negative electrode sheet when calculating the negative electrode sheet.

[0061] Step 3: Calculate the internal resistance of the punched tab

[0062] The internal resistance of a single tab is R 单极耳 , and the internal resistance of multiple tabs in parallel is R 极耳 .

[0063] R 单极耳 = ρ 极耳 L 极耳 / S 极耳 , R 极耳 = R 单极耳 / X, X is the number of tabs.

[0064] Wherein, ρ 极耳 is the resistivity of the tab foil, L 极耳 is the length of the tab, S 极耳 is the cross-sectional area of the tab, and each parameter is the corresponding parameter of the positive tab when calculating the positive tab, and each parameter is the corresponding parameter of the negative tab when calculating the negative tab.

[0065] Step 4: The internal resistance of the electrode sheet composed of the current collector, the electrode sheet, and the internal resistance of the punched tab

[0066] The internal resistance of the positive electrode sheet is R 正极 , and the internal resistance of the negative electrode sheet is R负极 The internal resistance of the positive current collector is R 正极集流体 The internal resistance of the negative current collector is R 负极集流体 , obtained by the method in Step 1. The internal resistance of the positive coating layer and interface is R 正极涂敷 The internal resistance of the negative coating layer and interface is R 负极涂敷 , obtained by the method in Step 2. The internal resistance of the positive tab is R 正极耳 The internal resistance of the negative tab is R 负极耳 , obtained by the method in Step 3.

[0067] R 正极 = R 正极集流体 + R 正极涂敷 + R 正极耳 ;

[0068] R 负极 = R 负极集流体 + R 负极涂敷 + R 负极耳 .

[0069] Step 5: The connecting piece includes a single welded tab or an adapter connected with the cover plate; the internal resistance of the connecting piece is R 连接件 , and the calculation method is as follows:

[0070] Formula: R 连接件 = p 连接件 L 连接件 / S 连接件 ; R 连接件 is the internal resistance of the connecting piece, p 连接件 is the resistivity of the connecting piece, L 连接件 is the length of the connecting piece, and S 连接件 is the cross-sectional area of the connecting piece.

[0071] Step 6: Internal resistance measurement of structural parts

[0072] The internal resistance of the steel shell, aluminum shell, cap, cover plate and other structural parts is directly measured using an internal resistance meter, and the sum of the internal resistances of each structural part is the internal resistance of the structural part R 结构件 .

[0073] The total internal resistance of the lithium ion battery is R 总 , R 总 = R 正极 + R 负极 + R 连接件 + R 结构件 .

[0074] The following examples are calculated according to the above method steps.

[0075] Example 1

[0076] Cylindrical 26700 battery, positive current collector is 15 μm aluminum foil, negative current collector is 8 μm copper foil; positive electrode material is lithium iron phosphate, negative electrode material is graphite; the core adopts the structure of welding positive electrode bipolar lug and negative electrode bipolar lug and connecting with the cap structure; the shell is 26×74 mm steel shell, the cap is 25.4×4.45 mm four-hole cap; the positive electrode plate width is 62 mm, the coating layer length is 460 mm, the negative electrode width is 64 mm, and the coating layer length is 1468 mm.

[0077] The positive electrode lug is located at the three-equal position, X=2; the two edges of the negative electrode plate are welded with lugs, which is equivalent to that the plate is divided into two sections, X=1.

[0078] (1) The internal resistance of the current collector:

[0079]

[0080] (2) The internal resistance of the coating area:

[0081]

[0082] (3) The internal resistance of the plate:

[0083] R 正极 =0.89+0.0291=0.9191 mΩ;

[0084] R 负极 =4.27+0.00282=4.27282 mΩ.

[0085] (4) The connecting piece:

[0086]

[0087] (5) The internal resistance of the structure:

[0088]

[0089] (6) The total internal resistance:

[0090]

[0091] Among them, the actual median internal resistance after liquid injection is obtained by using the internal resistance instrument, and the error is positive error when the error is greater than the predicted value, and negative error when the error is less than the predicted value, and the same below.

[0092] The error between the calculated total internal resistance value and the actually detected total internal resistance value is 4.78%.

[0093] Example 2

[0094] Cylindrical 26700 battery, positive current collector is aluminum foil, negative current collector is copper foil; positive material is lithium iron phosphate, negative material is graphite; the core adopts positive and negative bipolar ear structure welding and cover cap connection structure; the shell is 26x74mm steel shell, the cover cap is 25.4x4.45mm four-hole cover cap; the positive plate width is 62mm, the coating layer length is 460mm, the negative width is 64mm, and the coating layer length is 489mm.

[0095] The positive tab is located at the three-equal position, X=2; the negative tab is located at the three-equal position, X=2.

[0096] (1) Current collector resistance:

[0097]

[0098] (2) Coating area resistance:

[0099]

[0100] (3) Plate resistance:

[0101] R 正极 =0.89+0.0291=0.919mΩ;

[0102] R 负极 =1.06+0.00282=1.063mΩ.

[0103] (4) Connecting piece:

[0104]

[0105] (5) Structure resistance:

[0106]

[0107] (6) Total resistance:

[0108]

[0109] The error between the calculated total resistance value and the actually detected total resistance value is 5.27%.

[0110] Example 3

[0111] Soft package 133204 lithium iron phosphate battery, positive current collector is 13 μm aluminum foil, negative current collector is 6 μm copper foil; positive material is lithium iron phosphate, negative material is graphite; the core adopts the laminated structure, the number of positive sheet is 25, the number of negative sheet is 26, one tab on each sheet; the size of positive tab is 43.5 mm x 30 mm x 0.2 mm, the size of negative tab is 43.5 mm x 30 mm x 0.15 mm; the size of positive sheet is 180 x 127 mm, the size of negative sheet is 184 x 130 mm.

[0112] (1) The resistance of current collector:

[0113]

[0114] (2) The resistance of coated area:

[0115] The resistance of coating and interface:

[0116]

[0117] The resistance of tab:

[0118]

[0119] (3) The resistance of sheet:

[0120] R 正极 = 0.0412 + 0.16 + 0.065 = 0.2662 mΩ;

[0121] R 负极 = 0.0529 + 0.011 + 0.073 = 0.1369 mΩ.

[0122] (4) The resistance of connecting sheet (positive 43.5 mm x 30 mm x 0.2 mm, negative 43.5 mm x 30 mm x 0.15 mm):

[0123]

[0124] (5) The total resistance:

[0125]

[0126] The error between the calculated total resistance value and the actually detected total resistance value is -0.59%.

[0127] Example 4

[0128] Square 54173207-206Ah lithium iron phosphate battery, the positive current collector is 15 μm aluminum foil, the negative current collector is 8 μm copper foil; the positive electrode material is lithium iron phosphate, and the negative electrode material is graphite; the winding structure is adopted for the winding core, the number of positive electrode tabs is 37, the number of negative electrode tabs is 38, the positive electrode tab width is 187 mm, and the positive electrode length is 11.701 m; the negative electrode width is 192 mm, and the length is 12.047 m.

[0129] (1) The internal resistance of the current collector:

[0130]

[0131] (2) The internal resistance of the coated area:

[0132] The internal resistance of the coating and the interface resistance:

[0133]

[0134] The internal resistance of the tab:

[0135]

[0136] (3) The internal resistance of the electrode tab:

[0137] R 正极 = 0.0072 + 0.0014 + 0.04 = 0.0486 mΩ;

[0138] R 负极 = 0.0079 + 0.00011 + 0.048 = 0.056 mΩ.

[0139] (4) The connecting piece:

[0140]

[0141] (5) The internal resistance of the structural piece:

[0142]

[0143] (6) The total internal resistance:

[0144]

[0145] The error between the calculated total internal resistance value and the actually detected total internal resistance value is 0.67%.

[0146] In summary, the lithium ion battery AC internal resistance obtained by the theoretical calculation method of the application is close to the actual detection value, and the error is <6%, which proves the accuracy of the theoretical calculation method of the application.

Claims

1. A method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis, wherein the lithium-ion battery includes a positive electrode, a negative electrode, connectors, and structural components; the positive electrode includes a positive current collector, a positive electrode coating, and a positive electrode tab; and the negative electrode includes a negative current collector, a negative electrode coating, and a negative electrode tab; characterized in that... The method for calculating the AC internal resistance of a lithium-ion battery includes the following steps: obtaining the internal resistances of the positive electrode, negative electrode, connector, and structural component respectively, and adding them together to obtain the total internal resistance, which is the AC internal resistance of the lithium-ion battery. When obtaining the internal resistance of the positive and negative electrode sheets, the internal resistance of the positive and negative current collectors is calculated based on the thermodynamic model of the current distribution of the electrode tabs. The internal resistance of the positive and negative electrode dressings is calculated by measuring the resistivity of the dressing layer and the resistivity of the interface surface, and then based on the double-sided parallel model and the interface resistance theory. The internal resistance of the positive electrode sheet is the sum of the internal resistance of the positive current collector, the positive electrode dressing, and the positive electrode tab. The internal resistance of the negative electrode sheet is the sum of the internal resistance of the negative current collector, the negative electrode dressing, and the negative electrode tab. The internal resistance of a connector is the product of its resistivity and its length, divided by its cross-sectional area. The internal resistance of the structural components was obtained through actual measurement; The structural component includes a housing, a cap, and a cover plate, wherein the housing is a steel housing or an aluminum housing; The positive electrode tab and the negative electrode tab are full tab or tab-free structure, and the internal resistance calculation formula of the positive electrode current collector and the negative electrode current collector is: R 集流体 =ρ 集流体 L 集流体 / (3S 集流体 ), wherein R 集流体 is the internal resistance of the current collector, ρ 集流体 is the resistivity of the current collector, L 集流体 is the length of the current collector, and S 集流体 is the cross-sectional area of the current collector; when the positive electrode current collector is calculated, each parameter is the corresponding parameter of the positive electrode current collector, and when the negative electrode current collector is calculated, each parameter is the corresponding parameter of the negative electrode current collector; The positive electrode tab and the negative electrode tab are multi-tab structures, and the internal resistance calculation formula of the positive current collector and the negative current collector is: Rx=R 集流体 / (4X 2 ), wherein R 集流体 is the internal resistance of the current collector, X is the number of tabs on the current collector, Rx represents the internal resistance value of the current collector under X tabs, and when calculating the positive current collector, each parameter is the corresponding parameter of the positive current collector, and when calculating the negative current collector, each parameter is the corresponding parameter of the negative current collector. The internal resistance calculation formula of the positive electrode dressing and the negative electrode dressing is: R 涂敷 =(1 / 2) ×(ρ 敷料 / S 敷料 +ρ 界面 / S 敷料 ), wherein R 涂敷 is the sum of the dressing layer internal resistance and the interface internal resistance, ρ 敷料 is the dressing layer area specific resistance, ρ 界面 is the interface area specific resistance, and S 敷料 is the dressing layer area. When the positive electrode dressing is calculated, each parameter is the corresponding parameter of the positive electrode dressing; when the negative electrode dressing is calculated, each parameter is the corresponding parameter of the negative electrode dressing.

2. The method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis according to claim 1, characterized in that, The connector includes separately welded electrode tabs or adapters connected to the cover plate.

3. The method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis according to claim 1, characterized in that, In the double-sided parallel model, the material ratio, areal density, and thickness of the double-sided dressing layers are all the same.

4. The method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis according to claim 1, characterized in that, When calculating the internal resistance of the positive and negative tabs, the internal resistance of a single tab is R. 单极耳 The internal resistance of multiple electrodes stacked in parallel is R. 极耳 R 单极耳 =ρ 极耳 L 极耳 / S 极耳 , where ρ 极耳 L is the resistivity of the tab foil material. 极耳 S is the length of the electrode lug. 极耳 R is the cross-sectional area of ​​the electrode. 极耳 =R 单极耳 / X, where X is the number of electrodes. When calculating the positive electrode tab, all parameters are the corresponding parameters for the positive electrode tab; when calculating the negative electrode tab, all parameters are the corresponding parameters for the negative electrode tab.

5. The method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis according to claim 1, characterized in that, The materials of the positive electrode current collector and the negative electrode current collector are each independently selected from at least one of aluminum foil, copper foil and stainless steel foil.

6. The method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis according to claim 1, characterized in that, Lithium-ion batteries include ternary lithium batteries, lithium iron phosphate batteries, lithium manganese oxide batteries, lithium manganese iron phosphate batteries, or lithium-rich manganese-based batteries.

7. The method for calculating the AC internal resistance of a lithium-ion battery based on physical parameter analysis according to claim 1, characterized in that, Lithium-ion batteries can be cylindrical, pouch, or prismatic.

Images