A method for measuring resistance of battery pole piece and battery

Abstract

The present invention discloses a method for measuring the resistance of a battery electrode sheet and a battery, the method comprising: obtaining two slices of the same area size of the battery electrode sheet to be tested, assembling the two slices into a symmetrical battery, and determining the electrochemical AC impedance spectrum of the symmetrical battery; determining the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested based on the electrochemical AC impedance spectrum; determining the ohmic resistance value R of each slice of the battery electrode sheet to be tested based on the electronic resistance value and the ionic resistance value. Ω0 ; Determine the area A0 of each slice of the battery electrode to be tested and the area A1 of the battery electrode to be tested; Based on the area A0 of each slice of the battery electrode to be tested and the ohmic resistance value R Ω0 , and the area A1 of the battery electrode to be tested, determine the ohmic resistance value R of the battery electrode to be tested Ω1 The present invention can simplify the test method of the battery electrode sheet resistance, reduce material cost and test time, and simplify data processing.

Description

Technical Field

[0001] The present invention relates to the technical field of battery performance testing, and in particular to a method for measuring the resistance of a battery pole piece and a battery. Background Art

[0002] The current method for testing the electrode sheet resistance is mainly based on multi-probe testing of the membrane resistance. The resistance results measured include the collector resistance, probe contact resistance and electrode sheet resistance at the same time. The electrode sheet resistance cannot be obtained alone, and measurement errors may be caused by test pressure, poor contact and other issues. In addition, the multi-probe method measures the electronic resistance of the electrode sheet and cannot obtain the ionic resistance in the electrode.

[0003] The prior art records the test method of the ionic resistance of the electrode plate in the test battery. For example, the Chinese patent document with publication number CN115218778A discloses a test method for the tortuosity of the porous electrode of a lithium battery, which includes the following steps: assembling two identical electrode plates and a diaphragm into a symmetrical battery, injecting an electrolyte and then soaking, and then performing an electrochemical impedance test to obtain the electrode ionic resistance R by fitting. ion , the tortuosity τ of the lithium battery electrode is calculated.

[0004] For another example, a Chinese patent document with publication number CN116400240A discloses a method for measuring the ionic resistance per unit thickness of a liquid phase and a method for measuring the electrode tortuosity, comprising the following steps: combining the electrodes to be tested into a symmetrical battery; analyzing the obtained impedance spectrum to obtain the ionic resistance and electronic resistance of the electrode to be tested, and separating them to obtain the ionic resistance per unit thickness of the liquid phase in the electrode to be tested.

[0005] However, the existing method for testing the electrode resistance is complicated and the test results are inaccurate. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the existing method for testing the resistance of a battery plate is complicated and the test results are inaccurate. The present invention provides a method for measuring the resistance of a battery plate, which can simplify the test method of the battery plate resistance, reduce material costs and test time, and simplify data processing.

[0007] In order to solve the above technical problems, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode sheet, the method comprising: obtaining two slices of the same area size of the battery electrode sheet to be tested, assembling the two slices of the battery electrode sheet to be tested into a symmetrical battery, and determining the electrochemical AC impedance spectrum of the symmetrical battery; based on the electrochemical AC impedance spectrum, determining the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested; based on the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested, determining the ohmic resistance value R of each slice of the battery electrode sheet to be tested Ω0; Determine the area A0 of each slice of the battery electrode sheet to be tested and the area A1 of the battery electrode sheet to be tested; Based on the area A0 of each slice of the battery electrode sheet to be tested and the ohmic resistance value R Ω0 , and the area A1 of the battery electrode to be tested, determine the ohmic resistance value R of the battery electrode to be tested Ω1 , where R Ω1 =R Ω0 ·A0 / A1.

[0008] By adopting the above technical solution, the embodiment of the present application can calculate the ionic resistance (R) of the battery electrode sheet to be tested according to the area relationship between the slice of the battery electrode sheet to be tested (for example, the negative electrode battery electrode sheet to be tested or the positive electrode battery electrode sheet to be tested) and the complete battery electrode sheet to be tested. ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ).

[0009] Thus, the present embodiment can obtain the required slice parameters of the battery electrode to be tested (for example, the ionic resistance R ion 、Electronic resistance R e and ohmic resistance R Ω ), and according to the area relationship between the slice of the battery electrode to be tested and the complete battery electrode to be tested, the ohmic resistance (R Ω ). In other words, the resistance calculation method of the battery electrode sheet of the embodiment of the present application only needs to test the battery electrode sheet to be tested, and is not affected by other factors that affect the results, such as the resistance of the structural parts, contact resistance, welding resistance, etc. in the whole battery. The measurement error is small and the test result is accurate.

[0010] Furthermore, the resistance measurement method of the battery electrode of the embodiment of the present application can be used for the performance of electrodes of different systems and different batches to optimize the design of the battery electrode system, and can be used to evaluate the performance of electrodes under different working conditions, which is helpful for the study of electrode performance.

[0011] Moreover, since the resistance measurement method of the battery electrode of the embodiment of the present application only requires an electrochemical workstation (such as an electrochemical impedance tester), it has the advantages of simple operating steps, easy standardization, simple data processing, few consumables required, and low testing time and material costs.

[0012] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode sheet, wherein obtaining two slices of the battery electrode sheet to be tested includes: obtaining a battery electrode sheet, removing the active material coating on one side surface of the battery electrode sheet to obtain a battery electrode sheet to be tested having a single-sided active material coating; and cutting the battery electrode sheet to be tested into two slices of the same area along the thickness direction of the battery electrode sheet to be tested.

[0013] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode sheet, wherein the two slices of the battery electrode sheet to be tested are assemble into a symmetrical battery, comprising: placing the two slices of the battery electrode sheet to be tested and a diaphragm in a battery shell, the two slices of the battery electrode sheet to be tested are stacked on opposite sides of the diaphragm along the thickness direction, and the active material coating of each slice of the battery electrode sheet to be tested faces the diaphragm; injecting an electrolyte into the battery shell and then heat-sealing the battery shell to obtain the symmetrical battery.

[0014] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode, wherein determining the electrochemical AC impedance spectrum of the symmetrical battery comprises: performing an electrochemical impedance test on the symmetrical battery to obtain the electrochemical AC impedance spectrum of the symmetrical battery.

[0015] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode sheet, wherein determining the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested comprises: fitting the electrochemical AC impedance spectrum of the symmetrical battery using an equivalent circuit corresponding to a transmission line model, wherein the equivalent circuit comprises an ion transmission pathway and an electron transmission pathway, and obtaining parameter values ​​of the resistance of the ion transmission pathway and parameter values ​​of the resistance of the electron transmission pathway; determining the ionic resistance value and the electronic resistance value of each slice of the battery electrode sheet to be tested based on the parameter values ​​of the resistance of the ion transmission pathway and the parameter values ​​of the resistance of the electron transmission pathway.

[0016] According to another specific embodiment of the present invention, the embodiment of the present invention discloses a method for measuring the resistance of a battery electrode sheet, wherein the method for determining the ohmic resistance value of each slice of the battery electrode sheet to be tested based on the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested comprises: the ohmic resistance value of each slice of the battery electrode sheet to be tested is R Ω0 , R Ω0 =R e0 ·R ion0 / (R e0 +R ion0 ), where R e0Indicates the determination of the electronic resistance value of each slice of the battery electrode to be tested, R ion0 It indicates determining the ionic resistance value of each slice of the battery electrode to be tested.

[0017] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode, wherein the battery electrode to be measured includes any one or more of a fresh electrode that has not been cycled, a electrode obtained by disassembling a full battery after formation, and a electrode obtained by disassembling at different charge states after constant capacity or cycling.

[0018] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery electrode sheet, wherein the symmetrical battery includes a button-type symmetrical battery or a soft-pack symmetrical battery.

[0019] An embodiment of the present invention further discloses a method for measuring the resistance of a battery, comprising: using the method for measuring the resistance of a battery electrode sheet described in any of the above embodiments to determine the ohmic resistance value of the positive electrode sheet and the negative electrode sheet of the battery to be tested; based on the ohmic resistance value of the positive electrode sheet and the negative electrode sheet of the battery to be tested, determining the ohmic resistance value of the battery to be tested.

[0020] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a method for measuring the resistance of a battery, wherein the ohmic resistance value of the battery to be tested is determined based on the ohmic resistance value of the positive electrode sheet and the negative electrode sheet of the battery to be tested, and the ohmic resistance value of the battery to be tested is determined by: determining the area of ​​the positive electrode sheet to be tested and the area of ​​the negative electrode sheet to be tested; determining the total area of ​​the positive electrode sheet and the total area of ​​the negative electrode sheet in the battery to be tested; the ohmic resistance value of the battery to be tested is R Ω,full , R Ω,full =R Ω,a ·A a,sym / A a,full +R Ω,c ·A c,sym / A c,full , where R Ω,a Represents the ohmic resistance value of the negative electrode of the battery to be tested, R Ω,c Indicates the ohmic resistance value of the positive electrode of the battery to be tested, A a,sym Represents the area of ​​the negative electrode to be tested, A c,sym Represents the area of ​​the positive electrode to be tested, A a,full Represents the total area of ​​the negative electrode sheet in the battery to be tested, A c,full Represents the total area of ​​the positive electrode sheet in the battery to be tested.

[0021] By adopting the above technical solution, the resistance calculation method of the battery provided in the embodiment of the present application can obtain the resistance data of the whole battery core (for example, the complete battery to be tested) by testing the pole piece resistance in the battery. Therefore, the resistance calculation method of the battery in the embodiment of the present application can be used to predict the battery performance of the whole battery assembled with the pole piece to be tested.

[0022] In order to make the above contents of the present invention more clearly understood, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A Flow chart 1 showing a method for calculating resistance of a battery electrode sheet according to an embodiment of the present invention;

[0024] Figure 1B The process of the method for measuring the resistance of a battery electrode sheet according to an embodiment of the present invention is shown as follows Figure 2 ;

[0025] Figure 2 A schematic diagram showing a battery electrode sheet to be tested and two slices according to an embodiment of the present invention;

[0026] Figure 3 An equivalent circuit diagram of a transmission line model showing a fitted EIS spectrum of an embodiment of the present invention is shown;

[0027] Figure 4 A schematic diagram showing an electrochemical impedance spectrum of a symmetrical battery measured in an embodiment of the present invention is shown;

[0028] Figure 5 A linear relationship diagram showing the ionic resistance, electronic resistance and ohmic resistance of a slice of a negative electrode battery electrode sheet to be tested in Examples 1 to 4 of the present invention and the reciprocal of the area of ​​the corresponding slice of the negative electrode battery electrode sheet to be tested;

[0029] Figure 6 A linear relationship diagram showing the ionic resistance, electronic resistance and ohmic resistance of a slice of a positive electrode battery electrode sheet to be tested and the reciprocal of the area of ​​a slice of a corresponding negative electrode battery electrode sheet to be tested in Examples 5 to 7 of the present invention;

[0030] Figure 7 Flow chart 1 showing a method for calculating resistance of a battery according to an embodiment of the present invention;

[0031] Figure 8 The process of the method for calculating the resistance of a battery according to an embodiment of the present invention is shown as follows Figure 2 . DETAILED DESCRIPTION

[0032] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0033] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0034] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0035] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0036] In the description of this embodiment, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] Example 1

[0039] Figure 1A A flow chart of a method for calculating the resistance of a battery electrode sheet according to an embodiment of the present application is shown. Figure 1AThe resistance calculation method of the battery electrode in the embodiment of the present application is described in detail.

[0040] It can be understood that the battery electrode is an important component of the lithium battery, and it is the key area for the battery to carry out electrochemical reactions. The battery electrode resistance includes electronic resistance (R e ) and ionic resistance (R ion ), which together affect the ohmic internal resistance of the battery cell (R Ω ). Battery internal resistance is the core characteristic parameter that affects battery performance. It affects the voltage polarization during battery charging and discharging, reduces battery efficiency and shortens battery life, and is a factor that restricts battery performance. Therefore, ohmic internal resistance (R Ω ) is an important component of the battery DC internal resistance, reducing the ohmic internal resistance (R Ω ) can reduce battery energy loss, increase power output and charge and discharge rates, extend battery life, and help improve battery performance.

[0041] refer to Figure 1A A method for measuring the resistance of a battery electrode provided in an embodiment of the present application includes the following steps.

[0042] S1: obtaining two slices of the battery electrode to be tested with the same area, assembling the two slices of the battery electrode to be tested into a symmetrical battery, and determining the electrochemical AC impedance spectrum of the symmetrical battery.

[0043] Here, in the embodiment of the present application, the battery electrode sheet to be tested is cut to obtain battery electrode sheet slices, and after being assembled into a symmetrical battery, an electrochemical impedance test is performed on the symmetrical battery to determine the electrochemical impedance spectrum (EIS) of the symmetrical battery.

[0044] Exemplarily, the symmetrical battery in the embodiment of the present application is a soft-pack symmetrical battery, but is not limited thereto. The embodiment of the present application does not limit the structure of the symmetrical battery, for example, it may also be a button-type symmetrical battery.

[0045] For ease of understanding, the embodiments of the present application are described below using a soft-pack symmetrical battery as an example.

[0046] refer to Figure 1B In the embodiment of the present application, step S1 specifically includes:

[0047] S101: Obtain a battery electrode sheet, remove the active material coating on one side of the battery electrode sheet, and obtain a battery electrode sheet to be tested having a single-sided active material coating.

[0048] Here, first, the present embodiment obtains an untreated battery electrode sheet, that is, the opposite sides of the battery electrode sheet have active material coatings. Then, the present embodiment removes the active material coating on one side of the untreated battery electrode sheet, so that only one side of the battery electrode sheet has active material coating, thereby obtaining a battery electrode sheet to be tested with single-sided active material coating (see Figure 2 ).

[0049] Exemplarily, the battery electrode to be tested in the embodiment of the present application is a fresh electrode that has not been cycled, but is not limited to this. The embodiment of the present application does not limit the operating conditions of the battery electrode to be tested. For example, it can also be a electrode obtained by disassembling a full battery after formation, or a electrode obtained by disassembling at different charge states after constant capacity or cycling.

[0050] Exemplarily, the battery electrode sheet of the embodiment of the present application is a negative electrode sheet, but is not limited thereto. The embodiment of the present application does not limit the type of battery electrode sheet, for example, it can also be a positive electrode sheet. For ease of understanding, the following embodiment of the present application is described using a fresh negative electrode sheet that has not been cycled as an example.

[0051] S102: Cut the electrode sheet of the battery to be tested into two slices of the same size along the thickness direction of the electrode sheet of the battery to be tested.

[0052] Here, reference Figure 2 In the embodiment of the present application, a slicing device (e.g., a pole piece cutting machine) is used to cut the battery pole piece 10 to be tested with a single-sided active material coating obtained in step S101 into two slices 11 of the same size (i.e., the slices 11 of the battery pole piece 10 to be tested). For example, Figure 2 As shown, along the thickness direction of the battery electrode 10 to be tested (such as Figure 2 The battery electrode 10 to be tested is cut into two slices of the same size. Figure 2 The dotted box area indicates the original position of the two slices 11 in the battery electrode sheet 10 to be tested. Moreover, each slice 11 of the battery electrode sheet 10 to be tested in the embodiment of the present application is a square slice with a side length of 3 cm. However, the embodiment of the present application does not limit the shape and size of the slice 11 of the battery electrode sheet to be tested. For example, the slice 11 of the battery electrode sheet to be tested in the embodiment of the present application can also be a square slice with a side length of 1 cm, 2 cm, 4 cm, 5 cm or other lengths; or, the slice 11 of the battery electrode sheet to be tested in the embodiment of the present application can also be a circular slice or other shapes.

[0053] S103: Place two slices of two battery electrodes to be tested and a diaphragm in a battery shell, wherein the two slices of the battery electrodes to be tested are stacked on opposite sides of the diaphragm in the thickness direction, and the active material coating of each slice of the battery electrode to be tested faces the diaphragm, inject electrolyte into the battery shell and heat-seal the battery shell to obtain a symmetrical battery.

[0054] Here, the embodiment of the present application uses a laminating device (e.g., an automatic laminating machine) to place the two slices of the battery electrode sheet to be tested and the diaphragm obtained in step S102 into the battery case in a stacked manner. Figure 2 (shown in the Z direction), the two slices of the battery electrode sheet to be tested are stacked on opposite sides of the diaphragm, and the surface of one side of each slice of the battery electrode sheet to be tested having the active material coating is arranged toward the diaphragm. In other words, the diaphragm of the embodiment of the present application is located between the two slices of the battery electrode sheet to be tested, and the active material coatings of the two slices of the battery electrode sheet to be tested are arranged inwardly toward the diaphragm along the stacking direction (i.e., the thickness direction of the diaphragm). Next, the embodiment of the present application injects the electrolyte into the battery shell containing the two slices of the battery electrode sheet to be tested and the diaphragm. Finally, a vacuum packaging machine is used to seal the battery shell by vacuum heat sealing to obtain the soft-pack symmetrical battery of the embodiment of the present application.

[0055] Exemplarily, the battery shell of the embodiment of the present application is an aluminum-plastic film, but is not limited thereto. The embodiment of the present application does not limit the material of the battery shell, as long as it can be used to accommodate the slices of the battery electrode to be tested, the diaphragm and the electrolyte to form a symmetrical battery.

[0056] S104: Performing an electrochemical impedance test on the symmetrical battery to obtain an electrochemical AC impedance spectrum of the symmetrical battery.

[0057] Here, the embodiment of the present application uses an electrochemical workstation (for example, an electrochemical impedance tester) to perform an electrochemical impedance test on the soft-pack symmetrical battery obtained in steps S101 to S103 to obtain an electrochemical impedance spectrum (EIS) of the soft-pack symmetrical battery of the embodiment of the present application.

[0058] Figure 3 The following is a schematic diagram showing the characteristic data of the electrochemical impedance spectroscopy (EIS) of the soft-pack symmetrical battery of the embodiment of the present application. Figure 3As shown in the figure, EIS spectra a, b, and c of three symmetrical batteries with different slice areas are shown, wherein spectrum line a represents the EIS spectrum line of the soft-pack symmetrical battery (referred to as symmetrical battery 3X3) of the embodiment of the present application, and the slice of the embodiment of the present application is a square slice with a side length of 3 cm; spectrum line b represents the EIS spectrum line of the soft-pack symmetrical battery of Example 2 (referred to as symmetrical battery 4X4), and the slice of Example 2 is a square slice with a side length of 4 cm; spectrum line c represents the EIS spectrum line of the soft-pack symmetrical battery of Example 3 (referred to as symmetrical battery 5X5), and the slice of Example 3 is a square slice with a side length of 5 cm.

[0059] For ease of understanding, the EIS spectrum line (ie, spectrum line a) of the symmetrical battery 3X3 of the embodiment of the present application is used as an example for explanation below.

[0060] refer to Figure 3 In the figure, the horizontal axis (Z' / Ω) is the real impedance of the symmetrical battery 3X3, and the vertical axis (-Z" / Ω) is the imaginary impedance of the symmetrical battery 3X3. Among them, the real impedance (also called resistance R) represents the actual resistance caused by charge transfer and ion migration in the electrochemical reaction of the soft-pack symmetrical battery of the embodiment of the present application. That is, the electronic resistance (R e ) and ionic resistance (R ion Those skilled in the art will appreciate that the electronic resistance (R e ) are all related to the high frequency end (such as Figure 3 The real impedance of the spectrum line a within the dashed box A is shown in the 45° straight line area near 0,0, and the ionic resistance (R ion ) and low frequency end (such as Figure 3 The real impedance of the spectrum line a within the dotted box B is shown in the straight line area away from the 0,0 point.

[0061] Specifically, Figure 3 The scattered dots in the spectrum a shown in the figure represent the impedance data of the symmetrical battery 3X3 obtained after the electrochemical impedance test. Figure 3 The continuous line in the spectrum a shown in FIG. 1 represents a curve formed by fitting the impedance data of the scattered dots through the equivalent circuit corresponding to the transmission line model of the embodiment of the present application. Figure 3 It can be seen that the curve of the equivalent circuit fitting corresponding to the transmission line model of the embodiment of the present application is very consistent with the impedance data obtained by the electrochemical impedance test, and the fitting effect is good.

[0062] S2: Based on the electrochemical impedance spectroscopy, determine the electronic resistance and ionic resistance of each slice of the battery electrode to be tested.

[0063] Here, the embodiment of the present application adopts the transmission line model to fit the EIS spectrum of the soft-pack symmetrical battery measured in step S104 to obtain the electronic resistance (R e ) value is 0.13Ω, and the ionic resistance (R ion ) value is 0.95Ω.

[0064] For example, Figure 4 As shown, the embodiment of the present application adopts an equivalent circuit corresponding to the transmission line model to fit the EIS spectrum of the soft-pack symmetrical battery, and the equivalent circuit of the embodiment of the present application includes an ion transmission path 20 and an electron transmission path 30. That is, the equivalent circuit of the embodiment of the present application divides the above-mentioned symmetrical battery into multiple regions, each of which has an electronic resistor R in parallel. e and an ionic resistance R ion , and the two ionic resistances R between adjacent regions ion are connected in series to form an ion transmission path 20, and the two electronic resistors R between adjacent regions e are connected in series to form an electron transport path 30. e represents the electronic resistance of the soft-pack symmetrical battery of the embodiment of the present application, R ion represents the ionic resistance of the soft-pack symmetrical battery of the embodiment of the present application, and Zeta represents the Warburg impedance of the soft-pack symmetrical battery of the embodiment of the present application.

[0065] Therefore, the above step S2 in the embodiment of the present application further includes: obtaining the parameter value of the resistance of the ion transmission path 20 (i.e. Figure 4 Each ionic resistance R ion The sum of the parameter values ​​of the electron transport path 30 and the parameter value of the resistance of the electron transport path 30 (i.e. Figure 4 Each ionic resistance R e The parameter value of the resistance of the ion transmission path 20 is determined to be the ionic resistance (R ion ) value, R ion0 =0.95Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0 =0.13Ω.

[0066] Exemplarily, the embodiment of the present application uses ZView software to fit the EIS spectrum of the soft-pack symmetrical battery using an equivalent circuit corresponding to the transmission line model, but is not limited to this, and other fitting software such as Circuitfit or Impedance Spectroscopy Software may also be used.

[0067] S3: Based on the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested, determine the ohmic resistance value of each slice of the battery electrode sheet to be tested.

[0068] Here, through the above step S2, the electronic resistance (R e ) value and ionic resistance (R ion ) value, so that the ohmic resistance (R Ω )value.

[0069] For example, the method used in the present application to calculate the ohmic resistance (R Ω ) value is:

[0070] R Ω0 =R e0 ·R ion0 / (R e0 +R ion0 ) (1)

[0071] Among them, R e0 Represents the electronic resistance value of each slice of the battery electrode to be tested, R ion0 Indicates the ionic resistance value of each slice of the battery electrode to be tested.

[0072] The electronic resistance value R of each slice of the battery electrode sheet to be tested obtained in step S2 of the present invention is e0 =0.13Ω, ionic resistance value R ion0 = 0.95Ω Substituting into formula (1), we can get the ohmic resistance value R of each slice of the battery electrode to be tested. Ω0 =0.11Ω.

[0073] Therefore, the embodiment of the present application measures the electronic resistance (R e ) and ionic resistance (R ion ) is connected in parallel to calculate the ohmic resistance (R Ω ), the test method has simple operation steps, requires few consumables, and has low test time and material costs.

[0074] S4: Determine the area A0 of each slice of the battery electrode sheet to be tested and the area A1 of the battery electrode sheet to be tested, and calculate the area A0 of each slice of the battery electrode sheet to be tested and the ohmic resistance R Ω0 , and the area A1 of the battery electrode to be tested, determine the ohmic resistance value R of the battery electrode to be tested Ω1 , where R Ω1 =RΩ0 ·A0 / A1.

[0075] Here, after multiple tests and fitting analysis, the applicant found that the ohmic resistance (R Ω ) has a certain relationship with its area. Therefore, the ohmic resistance (R Ω )value.

[0076] For example, the method used in the present application to calculate the ohmic resistance (R Ω ) value is:

[0077] R Ω1 =R Ω0 ·A0 / A1 (2)

[0078] Wherein, A0 represents the area of ​​each slice of the battery electrode to be tested, and A1 represents the determined area of ​​the battery electrode to be tested.

[0079] The ohmic resistance value R of each slice of the battery electrode sheet to be tested in the embodiment of the present application obtained in step S3 is Ω0 = 0.11Ω and slice area A0 = 9cm 2 , and the area of ​​the battery electrode to be tested is A1 = 900cm 2 Substituting into formula (2), we can get the ohmic resistance value R of the battery electrode to be tested. Ω1 =1.2 mΩ. Exemplarily, the calculation process and results of the above formula in the embodiment of the present application are obtained by computer equipment (such as a personal computer, a server or a network device, etc.).

[0080] In addition, the applicant also designed several other tests to detect the electronic resistance (R e ) value and ionic resistance (R ion ) value, and the corresponding ohmic resistance (R Ω ) values, as described below.

[0081] Example 2

[0082] The embodiment of the present application provides a method for measuring the resistance of a battery electrode sheet, wherein, except that each slice of the negative electrode battery electrode sheet to be tested is a square slice with a side length of 4 cm, the rest is the same as the above-mentioned embodiment 1.

[0083] Specifically, first, Figure 4As shown, according to the above-mentioned step S104, the electrochemical impedance test is performed on the soft-pack symmetrical battery of the embodiment of the present application to obtain the EIS spectrum of the soft-pack symmetrical battery (referred to as symmetrical battery 4X4) of the embodiment of the present application.

[0084] Secondly, according to the above step S2, the parameter value of the resistance of the ion transmission path 20 and the parameter value of the resistance of the electron transmission path 30 are obtained by fitting the equivalent circuit corresponding to the transmission line model, so as to determine the parameter value of the resistance of the ion transmission path 20 as the ionic resistance (R ion ) value, R ion0 =0.49Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0 =0.09Ω.

[0085] Finally, according to the above step S3, the electronic resistance (R e ) value and ionic resistance (R ion ) value into formula (1) to calculate the ohmic resistance value R of each slice of the battery electrode to be tested Ω0 =0.07Ω.

[0086] In addition, according to the above step S4, the ohmic resistance (R Ω ) value and the slice area A0, as well as the area A1 of the battery electrode to be tested are substituted into formula (2) to calculate the ohmic resistance value R of the battery electrode to be tested. Ω1 =1.2mΩ.

[0087] Example 3

[0088] The embodiment of the present application provides a method for measuring the resistance of a battery electrode sheet, wherein, except that each slice of the negative electrode battery electrode sheet to be tested is a square slice with a side length of 5 cm, the rest is the same as the above-mentioned embodiment 1.

[0089] Specifically, first, Figure 4 As shown, according to the above step S104, the electrochemical impedance test is performed on the soft-pack symmetrical battery of the embodiment of the present application to obtain the EIS spectrum of the soft-pack symmetrical battery (referred to as symmetrical battery 5X5) of the embodiment of the present application.

[0090] Secondly, according to the above step S2, the parameter value of the resistance of the ion transmission path 20 and the parameter value of the resistance of the electron transmission path 30 are obtained by fitting the equivalent circuit corresponding to the transmission line model, so as to determine the parameter value of the resistance of the ion transmission path 20 as the ionic resistance (R ion ) value, R ion0 =0.32Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0 =0.05Ω.

[0091] Finally, according to the above step S3, the electronic resistance (R e ) value and ionic resistance (R ion ) value into formula (1) to calculate the ohmic resistance value R of each slice of the battery electrode to be tested Ω0 =0.05Ω.

[0092] In addition, according to the above step S4, the ohmic resistance (R Ω ) value and the slice area A0, as well as the area A1 of the battery electrode to be tested are substituted into formula (2) to calculate the ohmic resistance value R of the battery electrode to be tested. Ω1 =1.3mΩ.

[0093] Example 4

[0094] The embodiment of the present application provides a method for measuring the resistance of a battery electrode, wherein, except that each slice of the negative electrode battery electrode to be tested is a circular slice with a diameter of 6 mm and the battery structure is a button-type symmetrical battery, the rest is the same as the above-mentioned embodiment 1.

[0095] Specifically, first, according to the above-mentioned step S104, an electrochemical impedance test is performed on the button-type symmetrical battery of the embodiment of the present application to obtain an EIS spectrum of the button-type symmetrical battery of the embodiment of the present application.

[0096] Secondly, according to the above step S2, the parameter value of the resistance of the ion transmission path 20 and the parameter value of the resistance of the electron transmission path 30 are obtained by fitting the equivalent circuit corresponding to the transmission line model, so as to determine the parameter value of the resistance of the ion transmission path 20 as the ionic resistance (R ion ) value, R ion0 =10.46Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0=0.78Ω.

[0097] Finally, according to the above step S3, the electronic resistance (R e ) value and ionic resistance (R ion ) value into formula (1) to calculate the ohmic resistance value R of each slice of the battery electrode to be tested Ω0 =0.73Ω.

[0098] In addition, according to the above step S4, the ohmic resistance (R Ω ) value and the slice area A0, as well as the area A1 of the battery electrode to be tested are substituted into formula (2) to calculate the ohmic resistance value R of the battery electrode to be tested. Ω1 =1.1mΩ.

[0099] The resistance calculation method of the battery electrode provided in Examples 1 to 4 was repeated three times to obtain the area (cm2) of each slice of the battery electrode to be tested. 2 ), ionic resistance (Ω), electronic resistance (Ω) and ohmic resistance (Ω) are shown in Table 1:

[0100] Table 1 Parameter comparison of negative electrode plates of different sizes and different battery structures

[0101] <![CDATA[Area (cm 2 )]]> Ionic resistance (Ω) Electronic resistance (Ω) Ohm resistance (Ω) Example 1 9 0.95 0.13 0.11 Example 2 16 0.49 0.09 0.07 Example 3 25 0.32 0.05 0.05 Example 4 1.13 10.46 0.78 0.73

[0102] It can be seen from Table 1 that the ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) have an obvious linear relationship with the inverse of the area of ​​each slice of the corresponding negative electrode battery electrode to be tested, and different battery structures have different ionic resistances (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) has no effect. In addition, the present embodiment of the present invention has no effect on the ionic resistance (R ion ) value and electronic resistance (R e ) value is not limited, as long as it can be used to calculate the ohmic resistance of the slice of the battery electrode to be tested.

[0103] Further, Figure 5 The ionic resistance (R) of the slices of the negative electrode battery pole pieces of different sizes in Examples 1 to 4 is shown. ion )、Electronic resistance (R e ) and ohmic resistance (RΩ ) and the inverse of the area of ​​the slice of the corresponding negative electrode battery electrode to be tested. Figure 5 As shown in the figure, the resistance (i.e., ionic resistance R) of slices of three different sizes of negative electrode battery plates to be tested is shown. ion 、Electronic resistance R e and ohmic resistance R Ω ) and the slice area, where the relationship curve d represents the ionic resistance R ion The relationship curve with the slice area, Figure 5 The relationship curve e represents the electronic resistance R e The relationship curve with the slice area, Figure 5 The relationship curve f represents the ohmic resistance R Ω The relationship curve with the slice area, Figure 5 The scattered points are shown in the form of triangles.

[0104] For ease of understanding, the following is an example of an ohmic resistor R Ω The relationship curve with the slice area (ie, relationship curve f) is used as an example for explanation.

[0105] refer to Figure 5 The vertical axis (ohm) in the figure is the ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) resistance value, the horizontal axis is the slice area (cm 2 ). For example, the ordinate of the scattered point F located on the far right of the relationship curve f (ohm resistance (R Ω ) value) is 0.73, and the abscissa (the inverse of the slice area) is 1 / 1.13.

[0106] like Figure 5 As shown, the relationship curve f shows a straight line trend upward along the horizontal axis, which indicates that the ohmic resistance R of the slices of the negative electrode battery electrode to be tested of different sizes Ω There is an obvious linear relationship between the slice area and the inverse of the slice area. As the slice area decreases, the slice ohmic resistance R Ω In other words, combined Figure 5 Verify the ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) has a linear relationship with the inverse of the area of ​​each slice of the corresponding negative electrode battery electrode to be tested.

[0107] Therefore, the embodiment of the present application can calculate the ionic resistance (R) of the negative electrode electrode sheet to be tested according to the area relationship between each slice of the negative electrode electrode sheet to be tested and the complete negative electrode electrode sheet to be tested. ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ).

[0108] Thus, the embodiment of the present application can obtain the slice parameters (for example, the ionic resistance R ion 、Electronic resistance R e and ohmic resistance R Ω ), and according to the area conversion, the ohmic resistance of the complete negative electrode battery electrode to be tested (R Ω ). Furthermore, the resistance calculation method of the battery pole piece of the embodiment of the present application can be used to evaluate the performance of battery pole pieces in different systems and batches and the performance of battery pole pieces under different working conditions.

[0109] Moreover, since the resistance measurement method of the battery electrode of the embodiment of the present application only requires an electrochemical workstation (such as an electrochemical impedance tester), it has the advantages of simple operating steps, easy standardization, simple data processing, few consumables required, and low testing time and material costs.

[0110] In addition, in order to further verify the above inference, the following experiments were also carried out in the examples of the present application.

[0111] Example 5

[0112] The embodiment of the present application provides a method for measuring the resistance of a battery electrode, wherein, except that the battery electrode to be tested in the embodiment of the present application is a positive electrode battery electrode to be tested, the rest is the same as the above-mentioned embodiment 1.

[0113] Specifically, first, according to the above-mentioned step S104, an electrochemical impedance test is performed on the soft-pack symmetrical battery of the embodiment of the present application to obtain an EIS spectrum of the soft-pack symmetrical battery of the embodiment of the present application.

[0114] Secondly, according to the above step S2, the parameter value of the resistance of the ion transmission path 20 and the parameter value of the resistance of the electron transmission path 30 are obtained by fitting the equivalent circuit corresponding to the transmission line model, so as to determine the parameter value of the resistance of the ion transmission path 20 as the ionic resistance (R ion ) value, R ion0 =0.53Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0=0.15Ω.

[0115] Finally, according to the above step S3, the electronic resistance (R e ) value and ionic resistance (R ion ) value into formula (1) to calculate the ohmic resistance value R of each slice of the battery electrode to be tested Ω0 =0.12Ω.

[0116] In addition, according to the above step S4, the ohmic resistance (R Ω ) value and the slice area A0, and the area of ​​the battery electrode to be tested A1 = 850cm 2 Substitute into formula (2) to calculate the ohmic resistance value R of the battery electrode to be tested Ω1 =1.2mΩ.

[0117] Example 6

[0118] An embodiment of the present application provides a method for measuring the resistance of a battery electrode, wherein, except that the battery electrode to be tested in the embodiment of the present application is a positive electrode battery electrode to be tested, and each slice of the positive electrode battery electrode to be tested is a square slice with a side length of 4 cm, the rest is the same as the above-mentioned embodiment 1.

[0119] Specifically, first, according to the above-mentioned step S104, an electrochemical impedance test is performed on the soft-pack symmetrical battery of the embodiment of the present application to obtain an EIS spectrum of the soft-pack symmetrical battery of the embodiment of the present application.

[0120] Secondly, according to the above step S2, the parameter value of the resistance of the ion transmission path 20 and the parameter value of the resistance of the electron transmission path 30 are obtained by fitting the equivalent circuit corresponding to the transmission line model, so as to determine the parameter value of the resistance of the ion transmission path 20 as the ionic resistance (R ion ) value, R ion0 =0.40Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0 =0.13Ω.

[0121] Finally, according to the above step S3, the electronic resistance (R e ) value and ionic resistance (R ion ) value into formula (1) to calculate the ohmic resistance value R of the slice of the battery electrode to be tested Ω0 =0.10Ω.

[0122] In addition, according to the above step S4, the ohmic resistance (R Ω ) value and the slice area A0, as well as the area A1 of the battery electrode to be tested are substituted into formula (2) to calculate the ohmic resistance value R of the battery electrode to be tested. Ω1 =1.9mΩ.

[0123] Example 7

[0124] An embodiment of the present application provides a method for measuring the resistance of a battery electrode, wherein, except that the battery electrode to be tested in the embodiment of the present application is a positive electrode battery electrode to be tested, and each slice of the positive electrode battery electrode to be tested is a square slice with a side length of 5 cm, the rest is the same as the above-mentioned embodiment 1.

[0125] Specifically, first, according to the above-mentioned step S104, an electrochemical impedance test is performed on the soft-pack symmetrical battery of the embodiment of the present application to obtain an EIS spectrum of the soft-pack symmetrical battery of the embodiment of the present application.

[0126] Secondly, according to the above step S2, the parameter value of the resistance of the ion transmission path 20 and the parameter value of the resistance of the electron transmission path 30 are obtained by fitting the equivalent circuit corresponding to the transmission line model, so as to determine the parameter value of the resistance of the ion transmission path 20 as the ionic resistance (R ion ) value, R ion0 =0.24Ω; the parameter value of the resistance of the electron transmission path 30 is determined to be the electronic resistance (R e ) value, R e0 =0.10Ω.

[0127] Finally, according to the above step S3, the electronic resistance (R e ) value and ionic resistance (R ion ) value into formula (1) to calculate the ohmic resistance value R of the slice of the battery electrode to be tested Ω0 =0.07Ω.

[0128] In addition, according to the above step S4, the ohmic resistance (R Ω ) value and the slice area A0, as well as the area A1 of the battery electrode to be tested are substituted into formula (2) to calculate the ohmic resistance value R of the battery electrode to be tested. Ω1 =2.0mΩ.

[0129] Thus, the resistance calculation method of the battery electrode provided in Examples 5 to 7 was repeated three times to obtain the area (cm2) of each slice of the positive electrode battery electrode to be tested.2 ), ionic resistance (Ω), electronic resistance (Ω) and ohmic resistance (Ω) are shown in Table 2:

[0130] Table 2 Parameter comparison of different sizes of positive electrode battery electrodes

[0131] Area (cm2) Ionic resistance (Ω) Electronic resistance (Ω) Ohm resistance (Ω) Example 5 9 0.53 0.15 0.12 Example 6 16 0.40 0.13 0.10 Example 7 25 0.24 0.10 0.07

[0132] It can be seen from Table 2 that the ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) have an obvious linear relationship with the inverse of the area of ​​each slice of the corresponding positive electrode battery electrode sheet to be tested. In addition, the ionic resistance (R ion ) value and electronic resistance (R e ) value is not limited, as long as it can be used to calculate the ohmic resistance of the slice of the battery electrode to be tested.

[0133] Further, Figure 6 The ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) and the inverse of the area of ​​each slice of the corresponding positive electrode battery electrode to be tested. Figure 6 As shown in the figure, the resistance (i.e., ionic resistance R) of slices of three different sizes of positive electrode battery electrodes to be tested is shown. ion 、Electronic resistance R e and ohmic resistance R Ω ) and the slice area, where the relationship curve g represents the ionic resistance R ion The relationship curve with the slice area, Figure 6 The relationship curve h represents the electronic resistance R e The relationship curve with the slice area, Figure 6 The relationship curve i represents the ohmic resistance R Ω The relationship curve with the slice area, Figure 6 The scattered points are shown in the form of triangles.

[0134] For ease of understanding, the following is an example of an ohmic resistor R Ω The relationship curve with the slice area (ie, relationship curve i) is used as an example for explanation.

[0135] refer to Figure 6The vertical axis (ohm) in the figure is the ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) resistance value, the horizontal axis is the slice area (cm 2 ). For example, the ordinate of the rightmost scattered point I on the relationship curve i (ohm resistance (R Ω ) value) is 0.12, and the abscissa (the inverse of the slice area) is 1 / 9.

[0136] like Figure 6 As shown, the relationship curve i shows a straight line trend upward along the horizontal axis, which indicates that the ohmic resistance R of the slices of the positive electrode battery electrode to be tested of different sizes Ω There is an obvious linear relationship between the slice area and the inverse of the slice area. As the slice area decreases, the slice ohmic resistance R Ω In other words, combined Figure 6 Verify the ionic resistance (R ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ) has a linear relationship with the inverse of the area of ​​each slice of the corresponding positive electrode battery electrode to be tested.

[0137] Therefore, the embodiment of the present application can calculate the ionic resistance (R) of the positive electrode electrode sheet to be tested in the embodiment of the present application according to the area relationship between each slice of the positive electrode electrode sheet to be tested and the complete positive electrode electrode sheet to be tested. ion )、Electronic resistance (R e ) and ohmic resistance (R Ω ), which is the same as the conclusion of the negative electrode battery electrode sheet to be tested obtained in the above-mentioned embodiments 1 to 4, indicating that the resistance measurement method of the battery electrode sheet provided in the embodiment of the present application uses the slice fitting of the battery electrode sheet to be tested to calculate the ohmic resistance (R Ω In other words, it is reasonable for the embodiment of the present application to evaluate the performance of a complete battery electrode in a battery by using a slice of the battery electrode to be tested.

[0138] Example 8

[0139] Figure 7 The flowchart of the method for calculating the resistance of a battery in an embodiment of the present application is shown. Figure 7 The resistance calculation method of the battery in the embodiment of the present application is described in detail.

[0140] It can be understood that in the existing technology for detecting the ohmic resistance of a full battery, the actual ohmic resistance (R Ω,full) In addition to the ohmic resistance of the electrode, it also includes the resistance of the structural parts, contact resistance, welding resistance, etc. Therefore, it is currently impossible to directly obtain the accurate ohmic resistance of the electrode by testing the full battery.

[0141] To solve the above problem, the present invention uses the measured electronic resistance (R e ) and ionic resistance (R ion ) in parallel to obtain the ohmic internal resistance of the electrode plate (R Ω ), and the accurate ohmic resistance of the battery (R Ω ).

[0142] refer to Figure 7 The embodiment of the present application also provides a method for calculating the resistance of a battery, which includes the following steps.

[0143] S5: Using the battery electrode resistance measurement method, determine the ohmic resistance value of the positive electrode and the negative electrode of the battery to be tested.

[0144] Here, the embodiment of the present application adopts the battery electrode resistance measurement method described in steps S1 to S4 to obtain the ohmic resistance (R Ω )value.

[0145] S6: Determine the ohmic resistance value of the battery based on the ohmic resistance values ​​of the positive electrode plate and the negative electrode plate of the battery to be tested.

[0146] Here, according to the ohmic resistance (R Ω ) value and the electrode area, calculate and determine the battery's ohmic resistance (R Ω )value.

[0147] refer to Figure 8 In the embodiment of the present application, step S6 specifically includes:

[0148] S601: Determine the area of ​​the positive electrode sheet to be tested and the area of ​​the negative electrode sheet to be tested; and S602: Determine the total area of ​​the positive electrode sheets and the total area of ​​the negative electrode sheets in the battery to be tested.

[0149] Illustratively, the three different sizes of negative electrode sheets in the embodiments of the present application are respectively a slice of the negative electrode battery sheet to be tested in the above-mentioned embodiments 1, 2, and 3, and the three different sizes of positive electrode sheets are respectively a slice of the positive electrode battery sheet to be tested in the above-mentioned embodiments 5, 6, and 7.

[0150] Specifically, the area A of the negative electrode sheet a,sym =9cm 2 , the ohmic resistance of the negative electrode R Ω,a=0.11Ω, the corresponding positive electrode area A c,sym =9cm 2 , the ohmic resistance R of the positive electrode Ω,c =0.12Ω, then the total area of ​​the negative electrode in the battery to be tested is A a,full =9cm 2 , the total area of ​​the positive electrode sheet is A c,full =9cm 2 ;

[0151] The area of ​​the negative electrode Aa ,sym =16cm 2 , the ohmic resistance of the negative electrode R Ω,a =0.07Ω, the corresponding positive electrode area A c,sym =16cm 2 , the ohmic resistance R of the positive electrode Ω,c =0.10Ω, then the total area of ​​the negative electrode in the battery to be tested is A a,full =16cm 2 , the total area of ​​the positive electrode sheet is A c,full =16cm 2 ;

[0152] The area of ​​the negative electrode Aa ,sym =25cm 2 , the ohmic resistance of the negative electrode R Ω,a =0.05Ω, the corresponding positive electrode area A c,sym =25cm 2 , the ohmic resistance R of the positive electrode Ω,c =0.07Ω, then the total area of ​​the negative electrode in the battery to be tested is A a,full =25cm 2 , the total area of ​​the positive electrode sheet is A c,full =25cm 2 .

[0153] For example, the method used in the present embodiment to calculate the ohmic resistance (R Ω ) value is:

[0154] R Ω,full =R Ω,a ·A a,sym / A a,full +R Ω,c ·A c,sym / A c,full (3)

[0155] Among them, R Ω,a Indicates the ohmic resistance value of the negative electrode of the battery to be tested, R Ω,c Indicates the ohmic resistance value of the positive electrode of the battery to be tested, A a,symIndicates the area of ​​the negative electrode to be tested, A c,sym Indicates the area of ​​the positive electrode to be tested, A a,full Indicates the total area of ​​the negative electrode in the battery to be tested, A c,full Represents the total area of ​​the positive electrode in the battery under test.

[0156] Substituting the ohmic resistance value and total area of ​​the negative electrode sheet of the battery to be tested in steps S601 and S602, and the ohmic resistance value and total area of ​​the positive electrode sheet of the battery to be tested into formula (3), the ohmic resistance value R of the battery to be tested can be obtained. Ω,full They are 0.23Ω, 0.13Ω and 0.08Ω respectively. For example, the calculation process and results of the above formula in the embodiment of the present application are obtained by computer equipment (such as a personal computer, a server or a network device, etc.).

[0157] In addition, the applicant designed several other tests to detect the electronic resistance (R e ) value and ionic resistance (R ion ) value, and the corresponding ohmic resistance (R Ω ) values, as described below.

[0158] Illustratively, the battery to be tested in the embodiment of the present application is a soft-pack symmetrical battery, but is not limited thereto. The battery structure of the battery to be tested in the embodiment of the present application may also be a square shell battery or a cylindrical battery.

[0159] Example 9

[0160] In addition, the present embodiment also adopts the existing full battery ohmic resistance measurement method, and adopts a square battery electrode with a side length of 3 cm for the negative electrode to be tested and a square battery electrode with a side length of 3 cm for the positive electrode to be tested to prepare a soft-pack full battery. And by performing an electrochemical impedance test on the soft-pack symmetrical battery of the present embodiment, the EIS spectrum of the soft-pack battery of the present embodiment is obtained, and then the ohmic resistance value R is obtained by fitting according to the EIS spectrum. Ω,full =0.24Ω.

[0161] Example 10

[0162] In addition, the embodiment of the present application also adopts the existing method for measuring the ohmic resistance of a full battery, wherein, except for the negative electrode battery plate to be tested being a square battery plate with a side length of 4 cm and the positive electrode battery plate to be tested being a square battery plate with a side length of 4 cm to make a soft-pack battery, the rest is the same as the above-mentioned embodiment 9.

[0163] The electrochemical impedance spectroscopy (EIS) spectrum of the soft-pack symmetrical battery of the embodiment of the present application is obtained by performing an electrochemical impedance spectroscopy test on the soft-pack symmetrical battery of the embodiment of the present application, and then the ohmic resistance value R is obtained by fitting the EIS spectrum. Ω,full =0.13Ω.

[0164] Embodiment 11

[0165] In addition, the embodiment of the present application also adopts the existing method for measuring the ohmic resistance of a full battery, wherein, except for the negative electrode battery plate to be tested being a square battery plate with a side length of 5 cm and the positive electrode battery plate to be tested being a square battery plate with a side length of 5 cm to make a soft-pack battery, the rest is the same as the above-mentioned embodiment 9.

[0166] The electrochemical impedance spectroscopy (EIS) spectrum of the soft-pack symmetrical battery of the embodiment of the present application is obtained by performing an electrochemical impedance spectroscopy test on the soft-pack symmetrical battery of the embodiment of the present application, and then the ohmic resistance value R is obtained by fitting the EIS spectrum. Ω,full =0.09Ω.

[0167] Thus, the existing full-cell resistance measurement method of the battery provided in Examples 9 to 11 was repeated three times to obtain the electrode area (cm 2 ), the calculated values ​​of ohmic resistance (Ω) and the measured values ​​of ohmic resistance (Ω) are shown in Table 3:

[0168] Table 3 Parameter comparison of batteries of different sizes under test

[0169]

[0170] It can be seen from Table 3 that the ohmic resistance (R Ω，full ) calculated value and the ohmic resistance (R Ω，full ) test value is consistent. That is to say, the embodiment of the present application uses the ohmic resistance (R Ω ) The ohmic resistance (R) of the battery to be tested is obtained by area conversion. Ω，full ) is reliable.

[0171] In summary, the resistance calculation method of the battery provided in the embodiment of the present application can obtain the resistance data of the full battery core by testing the pole piece resistance in the battery. Therefore, the resistance calculation method of the battery in the embodiment of the present application can be used to predict the battery performance of the full battery assembled with the pole piece under test.

[0172] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A method for measuring the resistance of a battery electrode, characterized in that: The method comprises: Obtaining two slices of the same area size of the battery electrode sheet to be tested, assembling the two slices of the battery electrode sheet to be tested into a symmetrical battery, and determining the electrochemical alternating current impedance spectrum of the symmetrical battery; Based on the electrochemical impedance spectroscopy, determining the electronic resistance value and the ionic resistance value of each slice of the battery electrode to be tested; Based on the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested, the ohmic resistance value R of each slice of the battery electrode sheet to be tested is determined. Ω0 ; Determine the area A0 of each slice of the battery electrode sheet to be tested and the area A1 of the battery electrode sheet to be tested; Based on the area A0 and ohmic resistance R of each slice of the battery electrode to be tested Ω0 , and the area A1 of the battery electrode to be tested, determine the ohmic resistance value R of the battery electrode to be tested Ω1 , where R Ω1 =R Ω0 ·A0 / A1.

2. The method for calculating the resistance of a battery electrode according to claim 1, characterized in that: The step of obtaining two slices of the battery electrode to be tested comprises: Obtaining a battery electrode sheet, removing an active material coating on one side of the battery electrode sheet, and obtaining a battery electrode sheet to be tested having a single-side active material coating; The battery electrode sheet to be tested is cut into two slices of the same size along the thickness direction of the battery electrode sheet to be tested.

3. The method for calculating the resistance of a battery electrode according to claim 2, characterized in that: The step of assembling the two slices of the battery electrode sheet to be tested into a symmetrical battery comprises: Placing two slices of the battery electrode sheet to be tested and a separator in a battery shell, wherein the two slices of the battery electrode sheet to be tested are stacked on opposite sides of the separator along the thickness direction, and the active material coating of each slice of the battery electrode sheet to be tested faces the separator; The electrolyte is injected into the battery shell and then the battery shell is heat-sealed to obtain the symmetrical battery.

4. The method for calculating the resistance of a battery electrode according to claim 1, characterized in that: Determining the electrochemical impedance spectrum of the symmetrical battery includes: An electrochemical impedance test is performed on the symmetrical battery to obtain an electrochemical alternating current impedance spectrum of the symmetrical battery.

5. The method for calculating the resistance of a battery electrode according to claim 1, characterized in that: Determining the electronic resistance value and the ionic resistance value of each slice of the battery electrode to be tested includes: Using an equivalent circuit corresponding to a transmission line model to fit the electrochemical AC impedance spectrum of the symmetrical battery, the equivalent circuit includes an ion transmission pathway and an electron transmission pathway, to obtain a parameter value of the resistance of the ion transmission pathway and a parameter value of the resistance of the electron transmission pathway; Based on the parameter value of the resistance of the ion transmission path and the parameter value of the resistance of the electron transmission path, the ion resistance value and the electron resistance value of each slice of the battery electrode sheet to be tested are determined.

6. The method for calculating the resistance of a battery electrode according to claim 1, characterized in that: The step of determining the ohmic resistance value of each slice of the battery electrode sheet to be tested based on the electronic resistance value and the ionic resistance value of each slice of the battery electrode sheet to be tested comprises: The ohmic resistance value of each slice of the battery electrode to be tested is R Ω0 , R Ω0 =R e0 ·R ion0 / (R e0 +R ion0 ), where R e0 Represents the electronic resistance value of each slice of the battery electrode to be tested, R ion0 Indicates the ionic resistance value of each slice of the battery electrode to be tested.

7. The method for calculating the resistance of a battery electrode according to claim 1, characterized in that: The battery electrode to be tested includes any one or more of fresh electrode that has not been cycled, electrode obtained by disassembling after full battery formation, and electrode obtained by disassembling under different charge states after constant capacity or cycling.

8. The method for calculating the resistance of a battery electrode according to claim 1, characterized in that: The symmetrical battery includes a button-type symmetrical battery or a soft-pack symmetrical battery.

9. A method for calculating resistance of a battery, characterized in that: The method comprises: The method for measuring the resistance of a battery electrode sheet according to any one of claims 1 to 8 is used to determine the ohmic resistance values ​​of the positive electrode sheet and the negative electrode sheet of the battery to be tested; The ohmic resistance value of the battery to be tested is determined based on the ohmic resistance values ​​of the positive electrode sheet and the negative electrode sheet of the battery to be tested.

10. The method for calculating the resistance of a battery according to claim 9, characterized in that: The determining the ohmic resistance value of the battery to be tested based on the ohmic resistance values ​​of the positive electrode sheet and the negative electrode sheet of the battery to be tested comprises: Determining the area of ​​the positive electrode sheet to be tested and the area of ​​the negative electrode sheet to be tested; Determine the total area of ​​the positive electrode sheets and the total area of ​​the negative electrode sheets in the battery to be tested; The ohmic resistance of the battery to be tested is R Ω,full , R Ω,full =R Ω,a ·A a,sym / A a,full +R Ω,c ·A c,sym / A c,full ,in, R Ω,a Represents the ohmic resistance value of the negative electrode of the battery to be tested, R Ω,c Indicates the ohmic resistance value of the positive electrode of the battery to be tested, A a,sym Represents the area of ​​the negative electrode to be tested, A c,sym Represents the area of ​​the positive electrode to be tested, A a,full Represents the total area of ​​the negative electrode sheet in the battery to be tested, A c,full Represents the total area of ​​the positive electrode sheet in the battery to be tested.

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