CN116577682A - Decomposition test method for direct current internal resistance of secondary battery - Google Patents
Decomposition test method for direct current internal resistance of secondary battery Download PDFInfo
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- 238000000354 decomposition reaction Methods 0.000 title claims abstract description 28
- 238000010998 test method Methods 0.000 title claims abstract description 18
- 238000012546 transfer Methods 0.000 claims abstract description 61
- 238000009792 diffusion process Methods 0.000 claims abstract description 60
- 238000000034 method Methods 0.000 claims abstract description 44
- 239000003792 electrolyte Substances 0.000 claims abstract description 15
- 238000012360 testing method Methods 0.000 claims description 64
- 238000000576 coating method Methods 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 13
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- 239000012528 membrane Substances 0.000 claims description 12
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- 238000001035 drying Methods 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 238000007599 discharging Methods 0.000 claims description 6
- 239000011149 active material Substances 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 description 66
- 238000000157 electrochemical-induced impedance spectroscopy Methods 0.000 description 16
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 13
- 229910001416 lithium ion Inorganic materials 0.000 description 13
- 239000010410 layer Substances 0.000 description 11
- 239000002994 raw material Substances 0.000 description 9
- 239000007773 negative electrode material Substances 0.000 description 7
- 230000010287 polarization Effects 0.000 description 7
- 238000003466 welding Methods 0.000 description 5
- 239000011888 foil Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
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- 230000032683 aging Effects 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000003292 glue Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000006183 anode active material Substances 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- 238000012827 research and development Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
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- 229910052759 nickel Inorganic materials 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention relates to a decomposition test method of direct current internal resistance of a secondary battery, which comprises the following steps: acquiring an ohmic resistance R1 of the positive structural member and an ohmic resistance R2 of the negative structural member; calculating an anode current collector resistor R3 and a cathode current collector resistor R4; calculating an anode diaphragm resistance R5 and a cathode diaphragm resistance R6; acquiring a negative electrode charge transfer resistor R7, a positive electrode charge transfer resistor R8, a positive electrode ion diffusion resistance R10, a negative electrode ion diffusion resistance R11 and a negative electrode SEI film resistance R12; obtaining diaphragm ion impedance R9 of electrolyte in a diaphragm; the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5, the negative electrode diaphragm resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the diaphragm ion resistor R9, the positive electrode ion diffusion resistor R10, the negative electrode ion diffusion resistor R11 and the negative electrode SEI film resistor R12 are respectively converted into corresponding resistors of the secondary battery. The method is simple, and the direct current internal resistance of the secondary battery is accurately decomposed and tested.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a decomposition test method for direct current internal resistance of a secondary battery.
Background
Under the pressure pushing of energy conservation and emission reduction, the lithium ion battery plays an extremely important role in the energy storage and energy utilization fields. At present, lithium ion batteries become the main stream of secondary batteries for vehicles, and the safety of the lithium ion batteries is more and more important, especially, the battery pack formed by connecting a plurality of batteries in series and parallel is particularly important because of high energy, high power and safety. Among the many factors affecting the safety performance of the battery, the internal resistance is one of the important factors; meanwhile, the internal resistance is also an important factor affecting the power performance and the discharge efficiency of the battery, and is also an important parameter for evaluating the service life of the lithium battery. In recent years, the overall electrification process of the automobile industry is accelerated, the requirements of the new energy automobile on the high-rate charge and discharge performance of the secondary battery are higher and higher, and how to reduce the internal resistance of the battery is an important research subject in the battery industry, so that the cruising ability of the new energy automobile can be directly and effectively enhanced.
The conventional method for obtaining the internal resistance of the battery, such as the method for decomposing the direct current internal resistance of the lithium ion battery based on a numerical model disclosed in Chinese patent No. 114280480A, belongs to the technical field of electricity, and specifically comprises the following steps: the control equation and boundary conditions related to the lithium ion battery numerical model are classified, combined and coupled according to mass conservation, charge conservation and energy conservation; determining electrochemical parameters associated with the decomposition of the internal resistance of the battery in a corresponding control equation aiming at the lithium ion battery to be decomposed to obtain an integrated scheme corresponding to the electrochemical parameters; the lithium ion battery to be decomposed is divided into infinite units according to an integrated scheme, internal resistance generated on each battery unit is subjected to averaging treatment according to ohm law, an internal resistance source is determined according to a battery structure, the average internal resistance is subjected to deformation treatment in a structural interval, and then the internal resistances of different components are obtained through integration.
By adopting the method, the decomposition of the resistor is realized, but the lithium ion battery is divided into a plurality of infinite units, the average polarization of each area is calculated according to ohm law, and the internal resistances of different components are obtained by integrating the average polarization within different structural intervals in the battery after the average polarization is deformed according to the difference of electrochemical principles generating the internal resistances, so that the method is complex and the direct current internal resistances of the secondary battery cannot be accurately decomposed and tested.
Disclosure of Invention
Therefore, the invention aims to solve the technical problem that the direct current internal resistance of the lithium ion battery cannot be accurately decomposed in the prior art, so that the iteration speed of the battery core is low, and further provides an accurate decomposition test method for decomposing the direct current internal resistance of the lithium ion battery, which effectively reduces the cost and improves the iteration speed of the battery core.
In order to solve the technical problems, the decomposition test method of the direct current internal resistance of the secondary battery comprises the following steps: step S1: testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery to obtain the ohmic resistance R1 of the positive structural member and the ohmic resistance R2 of the negative structural member; respectively calculating a positive current collector resistor R3 and a negative current collector resistor R4 according to the sizes of the positive current collector and the negative current collector; measuring positive plate resistance and negative plate resistance, and respectively calculating positive plate resistance R5 and negative plate resistance R6 according to the positive plate resistance and the negative plate resistance, and positive current collector resistance R3 and negative current collector resistance R4; manufacturing a three-electrode card battery, charging the three-electrode card battery, and performing EIS test on the three-electrode card battery with set electric quantity to obtain a negative electrode charge transfer resistor R7, a positive electrode charge transfer resistor R8, positive electrode ion diffusion resistance R10, negative electrode ion diffusion resistance R11 and negative electrode SEI film resistance R12; manufacturing symmetrical card batteries with different diaphragm layers, and testing the ohmic impedance of the symmetrical card batteries through EIS to obtain diaphragm ion impedance R9 of electrolyte in the diaphragm;
step S2: the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5, the negative electrode diaphragm resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the diaphragm ion resistor R9, the positive electrode ion diffusion resistor R10, the negative electrode ion diffusion resistor R11 and the negative electrode SEI film resistor R12 are respectively converted into corresponding resistors of the secondary battery.
In one embodiment of the invention, the method for testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery comprises the following steps: the method comprises the steps of respectively testing positive and negative electrode area connecting pieces and connecting resistance by using a resistance meter, wherein when the positive electrode area connecting pieces and the connecting resistance are tested, one probe of the resistance meter is contacted with a positive electrode bus bar of a battery, and the other probe is contacted with a positive electrode tab group of the battery, so that an ohmic resistance R1 of a positive electrode structural member is obtained; when the negative electrode area connecting piece and the connecting resistor are tested, one probe of the resistor is contacted with a negative electrode busbar of the battery, and the other probe is contacted with a negative electrode tab group of the battery, so that the ohmic resistor R2 of the negative electrode structural member is obtained.
In one embodiment of the present invention, the method for calculating the positive current collector resistance R3 and the negative current collector resistance R4 according to the sizes of the positive current collector and the negative current collector respectively includes: according to the formula，/>，Calculating the positive current collector resistance R3, wherein +.>Is the resistivity of the positive current collector, +.>Is the width of the positive current collector tab, d1 is the length of the positive current collector tab, THK1 is the thickness of the positive current collector, +.>Is the width of the positive current collector excluding the tab, wid1 is the length of the positive current collector excluding the tab, +.>Is the resistance of the positive current collector tab,the positive current collector does not comprise a resistance of a lug; according to the formula->，/>，Calculating a negative current collector resistance R4, wherein +.>Is the resistivity of the negative current collector, +.>Is the width of the lug of the negative current collector, +.>Is the length of the tab of the negative current collector, THK2 is the thickness of the negative current collector, +.>Is the width of the negative current collector excluding the tab, wid2 is the length of the negative current collector excluding the tab, R41 is the resistance of the negative current collector tab, and R42 is the resistance of the negative current collector excluding the tab.
In one embodiment of the present invention, the positive plate resistance and the negative plate resistance are measured, and the method for calculating the positive plate resistance R5 and the negative plate resistance R6 according to the positive plate resistance and the negative plate resistance and the positive current collector resistance R3 and the negative current collector resistance R4 respectively comprises: measuring positive plate resistance using a diaphragm resistance test systemThe positive sheet resistance r5=positive sheet resistance +.>-a positive current collector resistance R3; measuring the negative plate resistance by using a diaphragm resistance test system>The negative electrode sheet resistance r6=negative electrode sheet resistance +.>-a negative current collector resistance R4.
In one embodiment of the invention, the method of making a three electrode card cell is: sequentially stacking the dried positive plate, the two first diaphragms, the reference electrode and the negative plate, wherein the reference electrode is positioned between the adjacent first diaphragms to prepare a reference electrode-inserted battery cell, packaging the reference electrode-inserted battery cell by using a shell, and injecting electrolyte to obtain a battery; and (5) carrying out battery formation and capacity division to obtain the card battery with the reference electrode.
In one embodiment of the present invention, the method for obtaining the dried positive plate, the first separator and the negative plate comprises: disassembling the battery, discharging the battery to an empty state, disassembling the battery core under a dry condition, and separating the top cover from the battery core; and obtaining a set amount of positive plate, negative plate and first diaphragm, and drying the positive plate, the negative plate and the first diaphragm.
In one embodiment of the present invention, the method for obtaining the negative electrode charge transfer resistor R7, the negative electrode ion diffusion resistance R11, and the negative electrode SEI film resistance R12 includes: and (3) performing EIS test on the three-electrode card battery with the set electric quantity by using an electrochemical workstation, connecting a negative electrode and a reference electrode of the three-electrode card battery with the electrochemical workstation during the test, and fitting test results to obtain a negative electrode charge transfer resistor R7, a negative electrode ion diffusion impedance R11 and a negative electrode SEI film resistance R12.
In one embodiment of the present invention, the method for obtaining the positive electrode charge transfer resistor R8 and the positive electrode ion diffusion resistance R10 is as follows: and (3) performing EIS test on the three-electrode card battery with the set electric quantity by using an electrochemical workstation, connecting the positive electrode and the reference electrode of the three-electrode card battery with the electrochemical workstation during the test, and fitting the test result to obtain a positive electrode charge transfer resistor R8 and a positive electrode ion diffusion impedance R10.
In one embodiment of the present invention, the method for converting the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode sheet resistor R5, the negative electrode sheet resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the separator ion resistor R9, the positive electrode ion diffusion resistor R10, the negative electrode ion diffusion resistor R11, and the negative electrode SEI film resistor R12 into corresponding resistors of the secondary battery respectively comprises: when the positive current collector resistor R3, the negative current collector resistor R4, the positive diaphragm resistor R5 and the negative diaphragm resistor R6 are converted into the resistances of the secondary batteries, respectively performing resistance conversion according to the areas of the positive current collector, the negative current collector, the positive diaphragm and the negative diaphragm; when the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the positive electrode ion diffusion resistance R10, the negative electrode ion diffusion resistance R11 and the negative electrode SEI film resistance R12 are converted into the resistances of the secondary batteries, the resistances are converted according to the areas of the three-electrode card batteries and the secondary batteries; when the diaphragm ion impedance R9 is converted into the resistance of the secondary battery, the conversion of the resistance is performed according to the areas of the symmetrical card battery and the secondary battery.
In one embodiment of the invention, the method for obtaining the diaphragm ion impedance R9 of the electrolyte in the diaphragm is as follows: and (3) testing the ohmic impedance of the symmetrical card battery through the EIS, fitting the data according to the obtained test result to obtain a linear slope, and obtaining the diaphragm ion impedance R9 according to the linear slope.
In one embodiment of the invention, the ohmic resistance of the symmetrical card battery is RWherein n is the number of membrane layers, ">Is the membrane ion impedance R9,is the current collector resistance>Is the resistance of the active material coating.
Compared with the prior art, the technical scheme of the invention has the following advantages:
in the step S1, the ohmic resistance R1 of the positive structural member and the ohmic resistance R2 of the negative structural member are obtained by testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery; the positive electrode current collector, the negative electrode current collector, the positive electrode plate and the negative electrode plate of the disassembled battery are obtained, so that the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5 and the negative electrode diaphragm resistor R6 can be calculated, and raw materials can be directly obtained from the disassembled battery or the existing raw materials can be directly utilized, so that the material obtaining mode is convenient, and the calculation is simple and convenient; manufacturing a three-electrode card battery, so that a negative electrode charge transfer resistor R7, a positive electrode charge transfer resistor R8, a positive electrode ion diffusion resistance R10, a negative electrode ion diffusion resistance R11 and a negative electrode SEI film resistance R12 can be obtained; manufacturing symmetrical card batteries with different diaphragm layers, so that diaphragm ion impedance R9 of electrolyte in the diaphragm can be obtained; in the whole process, the secondary battery, namely the large battery, is converted into the disassembled small battery, so that the calculation of each internal resistance is facilitated, the method is simple, and the accurate decomposition test of the direct-current internal resistance of the lithium ion battery is facilitated; in the step S2, the positive current collector resistor R3, the negative current collector resistor R4, the positive diaphragm resistor R5, the negative diaphragm resistor R6, the negative charge transfer resistor R7, the positive charge transfer resistor R8, the diaphragm ion resistor R9, the positive ion diffusion resistor R10, the negative ion diffusion resistor R11 and the negative SEI film resistor R12 are respectively converted into corresponding resistors of the secondary battery, so that decomposition of the large battery is completed, and each part of resistors are accurately obtained, so that the ratio of the resistance values and the total resistance values of different components can be obtained, and the battery cell design and the battery cell direct current internal resistance optimization are used as references, and the electrical performance and the safety performance of the battery cell are improved; meanwhile, the ratio of the resistance of each component in the battery cell is clearly determined through decomposition of the DCR of the battery cell, and a battery cell designer can specifically optimize the DCR of the battery cell through the decomposition test result, so that the research and development test investment is reduced, the research and development period is shortened, the development cost is reduced, and the iteration speed of the battery cell is improved.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings, in which
Fig. 1 is a flowchart of a decomposition test method of the direct current internal resistance of the secondary battery of the present invention;
FIG. 2 is an equivalent circuit of the cell of the present invention;
FIG. 3 is a schematic view of the structure of the cover plate connector and the corresponding weld zone of the present invention;
FIG. 4 is a schematic view of a positive current collector of the present invention;
FIG. 5 is a schematic view of a negative current collector of the present invention;
FIG. 6 is a schematic view of a three electrode card cell of the present invention;
FIG. 7 is a side view of the internal structure of a three electrode card cell of the present invention;
FIG. 8 is a schematic view of a symmetrical card cell of the present invention having different numbers of separator layers;
FIG. 9 is a graphical representation of the EIS test results of symmetrical card cells of the present invention having different numbers of membrane layers.
Reference numerals in the specification: 11. a positive bus bar; 12. a positive electrode conductive block; 13. a positive electrode post; 14. a positive electrode connecting sheet; 15. a positive electrode tab group; 21. a negative electrode bus bar; 22. a negative electrode conductive block; 23. a negative electrode post; 24. a negative electrode connecting sheet; 25. a negative electrode tab group; 31. a positive plate; 311. a first positive electrode current collector; 312. a first positive electrode active material coating layer; 32. a first diaphragm; 33. a reference electrode; 34. a negative electrode sheet; 341. a first negative electrode current collector; 342. a first negative active material coating layer; 35. a positive electrode tab; 36. a negative electrode tab; 37. a housing; 41. a second negative electrode current collector; 42. a second negative active material coating; 43. and a second diaphragm.
Detailed Description
As shown in fig. 1 and 2, the present embodiment provides a decomposition test method for dc internal resistance of a secondary battery, including the steps of:
step S1: testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery to obtain the ohmic resistance R1 of the positive structural member and the ohmic resistance R2 of the negative structural member; respectively calculating a positive current collector resistor R3 and a negative current collector resistor R4 according to the sizes of the positive current collector and the negative current collector; measuring positive plate resistance and negative plate resistance, and respectively calculating positive plate resistance R5 and negative plate resistance R6 according to the positive plate resistance and the negative plate resistance, and positive current collector resistance R3 and negative current collector resistance R4; manufacturing a three-electrode card battery, charging the three-electrode card battery, and performing EIS (electrochemical impedance spectroscopy) test on the three-electrode card battery with set electric quantity to obtain a negative electrode charge transfer resistor R7, a positive electrode charge transfer resistor R8, a positive electrode ion diffusion resistor R10, a negative electrode ion diffusion resistor R11 and a negative electrode SEI film resistor R12; manufacturing symmetrical card batteries with different diaphragm layers, and testing the ohmic impedance of the symmetrical card batteries through EIS to obtain diaphragm ion impedance R9 of electrolyte in the diaphragm;
step S2: and the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5, the negative electrode diaphragm resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the diaphragm ion impedance R9, the positive electrode ion diffusion impedance R10, the negative electrode ion diffusion impedance R11 and the negative electrode SEI film resistor R12 are respectively converted into corresponding resistors of the secondary battery.
In the method for testing the decomposition of the direct current internal resistance of the secondary battery, in the step S1, the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery are tested, and the ohmic resistance R1 of the positive structural member and the ohmic resistance R2 of the negative structural member are obtained; the positive electrode current collector, the negative electrode current collector, the positive electrode plate and the negative electrode plate of the disassembled battery are obtained, so that the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5 and the negative electrode diaphragm resistor R6 can be calculated, and raw materials can be directly obtained from the disassembled battery or the existing raw materials can be directly utilized, so that the material obtaining mode is convenient, and the calculation is simple and convenient; manufacturing a three-electrode card battery, so that a negative electrode charge transfer resistor R7, a positive electrode charge transfer resistor R8, a positive electrode ion diffusion resistance R10, a negative electrode ion diffusion resistance R11 and a negative electrode SEI film resistance R12 can be obtained; manufacturing symmetrical card batteries with different diaphragm layers, so that diaphragm ion impedance R9 of electrolyte in the diaphragm can be obtained; in the whole process, the secondary battery, namely the large battery, is converted into the disassembled small battery, so that the calculation of each internal resistance is facilitated, the method is simple, and the accurate decomposition test of the direct-current internal resistance of the lithium ion battery is facilitated; in the step S2, the positive current collector resistor R3, the negative current collector resistor R4, the positive sheet resistor R5, the negative sheet resistor R6, the negative charge transfer resistor R7, the positive charge transfer resistor R8, the diaphragm ion resistor R9, the positive ion diffusion resistor R10, the negative ion diffusion resistor R11, and the negative SEI film resistor R12 are respectively converted into corresponding resistors of the secondary battery, so that decomposition of the large battery is completed, and each part of resistors is accurately obtained, so that the ratio of the resistance values of different components to the total resistance value can be obtained, and the battery cell design and the battery cell direct current internal resistance (DCR for short) are optimized as references, and the electrical performance and the safety performance of the battery cell are improved.
In this embodiment, the DCR is divided into two types, i.e., a charging DCR and a discharging DCR, where the DCR can be characterized as an ohmic resistance (Rs) and a polarization resistance; the ohmic resistor (Rs) comprises: cover plate connector and corresponding land resistor (R mechanical ) Current collector resistance (R) foil ) Resistance of pole piece (R) film ) Ion resistance (R) of electrolyte in separator sep,ele ) The method comprises the steps of carrying out a first treatment on the surface of the The polarization resistor comprises: SEI film resistance (R) sei ) Charge transfer impedance (R) ct ) Diffusion resistance (R) w ). As shown in fig. 2, wherein R1 is the ohmic resistance of the positive structural member; r2 is the ohmic resistance of the negative structural member; r3 is the positive current collector resistance; r4 is the negative current collector resistance; r5 is the positive diaphragm resistance; r6 is the negative diaphragm resistance; r7 is a negative charge transfer resistor; r8 is the positive charge transfer resistance; r9 is the membrane ion impedance; r10 is the positive ion diffusion resistance; r11 is the negative ion diffusion resistance; r12 is the negative electrode SEI film resistance.
As shown in fig. 3, the positive electrode structural member includes a positive electrode bus bar 11, a positive electrode conductive block 12, a positive electrode post 13, a positive electrode connection piece 14 and a positive electrode tab group 15, wherein the positive electrode bus bar 11 is connected to the positive electrode post 13 through the positive electrode conductive block 12, and the positive electrode post 13 is connected to the positive electrode tab group 15 through the positive electrode connection piece 14.
The negative electrode structure member comprises a negative electrode busbar 21, a negative electrode conductive block 22, a negative electrode pole 23, a negative electrode connecting sheet 24 and a negative electrode pole lug group 25, wherein the negative electrode busbar 21 is connected to the negative electrode pole 23 through the negative electrode conductive block 22, and the negative electrode pole 23 is connected with the negative electrode pole lug group 25 through the negative electrode connecting sheet 24.
The method for testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery comprises the following steps: the method comprises the steps of respectively testing positive and negative electrode area connecting pieces and connecting resistance by using a resistance meter, wherein when the positive electrode area connecting pieces and the connecting resistance are tested, one probe of the resistance meter is contacted with a positive electrode busbar 11 of a battery, the other probe is contacted with a positive electrode tab group 15 of the battery, and a positive electrode structural member ohmic resistance R1 is obtained, wherein the positive electrode structural member ohmic resistance R1 also refers to positive electrode mechanical resistance; when the negative electrode area connecting piece and the connecting resistance are tested, one probe of the resistance meter is contacted with the negative electrode busbar 21 of the battery, the other probe is contacted with the negative electrode tab group 25 of the battery, and the ohmic resistance R2 of the negative electrode structural member is obtained, wherein the ohmic resistance R2 of the negative electrode structural member also refers to the mechanical resistance of the negative electrode, and the mechanical resistance R of the secondary battery can be obtained by the testing method mechanical 。
As shown in fig. 4, the method for calculating the positive electrode current collector resistance R3 according to the size of the positive electrode current collector is as follows: according to the formula，/>，/>Calculating a positive current collector resistance R3, whereinIs the resistivity of the positive current collector, +.>Is the width of the positive current collector tab, d1 is the length of the positive current collector tab, THK1 is the thickness of the positive current collector, < >>Is the width of the positive current collector excluding the tab, wid1 is the length of the positive current collector excluding the tab, +.>Resistance of positive current collector tab, < >>Is the resistance of the positive current collector excluding the tab.
As shown in fig. 5, the method for calculating the negative electrode current collector resistance R4 according to the size of the negative electrode current collector is as follows: according to the formula，/>，/>Calculating a negative current collector resistance R4, whereinIs the resistivity of the negative current collector, +.>Is the width of the lug of the negative current collector, +.>Is the length of the tab of the negative current collector, THK2 is the thickness of the negative current collector, +.>Is the width of the negative current collector excluding the tab, wid2 is the length of the negative current collector excluding the tab, R41 is the resistance of the negative current collector tab, and R42 is the resistance of the negative current collector excluding the tab.
The positive current collector resistance R3 and the negative current collector resistance R4 can be obtained by the method, so that a current collector can be obtainedResistance R of fluid foil . In this embodiment, the positive current collector and the negative current collector may obtain raw materials from the disassembled battery, or may directly use the existing raw materials, so that the material obtaining method is convenient, the calculation is simple, and the current collector resistance R may be accurately obtained foil 。
The positive plate resistor comprises a positive current collector resistor and a positive diaphragm resistor; the negative plate resistor comprises a negative current collector resistor and a negative diaphragm resistor, so that the positive diaphragm resistor can be obtained through the positive plate resistor and the positive current collector resistor, and the negative diaphragm resistor can be obtained through the negative plate resistor and the negative current collector resistor.
The method for measuring the resistance of the positive plate and calculating the resistance R5 of the positive plate according to the resistance of the positive plate and the resistance R3 of the positive current collector comprises the following steps: measuring positive plate resistance using a diaphragm resistance test systemThe positive sheet resistance r5=positive sheet resistance +.>-a positive current collector resistance R3;
the method for measuring the resistance of the negative electrode sheet and calculating the resistance R6 of the negative electrode diaphragm according to the resistance R4 of the negative electrode sheet and the resistance R4 of the negative electrode current collector comprises the following steps: measuring negative plate resistance using diaphragm resistance test systemThe negative electrode sheet resistance r6=negative electrode sheet resistance +.>-a negative current collector resistance R4.
The positive electrode diaphragm resistance R5 and the negative electrode diaphragm resistance R6 can be obtained by the method, so that the diaphragm resistance R of the pole piece can be obtained film . In the embodiment, the positive electrode membrane and the negative electrode membrane can obtain raw materials from the disassembled battery, and can directly utilize the existing raw materials, so that the material obtaining mode is convenient, the calculation is simple and convenient,can accurately obtain the diaphragm resistance R film 。
As shown in fig. 6 and 7, the method for manufacturing the three-electrode card comprises the following steps: sequentially stacking the dried positive electrode plate 31, the two first diaphragms 32, the reference electrode 33 and the negative electrode plate 34, wherein the reference electrode 33 is positioned between the adjacent first diaphragms 32, and a battery cell inserted with the reference electrode 33 is manufactured, wherein a positive electrode tab 35 is connected with the positive electrode plate 31, a negative electrode tab 36 is connected with the negative electrode plate 34, and the battery cell inserted with the reference electrode 33 is packaged by a shell 37 and electrolyte is injected to obtain the battery; the cell was formed and partitioned to give a card cell with a reference electrode 33. The three-electrode card is favorable for obtaining the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the positive electrode ion diffusion resistance R10, the negative electrode ion diffusion resistance R11 and the negative electrode SEI film resistance R12 through EIS test.
Wherein the positive electrode sheet 31 includes a first positive electrode current collector 311 and a first positive electrode active material coating 312 attached to the first positive electrode current collector 311; the negative electrode tab 34 includes a first negative electrode current collector 341 and a first negative electrode active material coating 342 attached to the first negative electrode current collector 341.
Specifically, the dried pole piece is transferred into a glove box, and the card battery with the reference electrode 33 is manufactured after the steps of rubberizing, die cutting, pole lug wiping, ultrasonic welding, pole lug rubberizing, assembling, top sealing, bottom sealing, vacuum baking, liquid injection, vacuum standing, vacuum side sealing, high-temperature standing, hot and cold pressing, ageing and formation and capacity separation. Wherein the rubberizing refers to covering one side of the double-sided coating pole piece with an adhesive tape. The die cutting is performed along the alignment of the reference surface position, and the tab position is reserved. The electrode wiping tab is used for wiping off the double-sided paint on the electrode tab of the experimental electrode sheet to expose the foil, and meanwhile, the paint on the electrode sheet cannot be wiped off. The ultrasonic welding refers to welding an external tab on an experimental pole piece; note that the anode corresponds to a nickel tab and the cathode corresponds to an aluminum tab. The tab rubberizing is to paste green glue at the spot welding position of the tab, prevent welding slag and strengthen the hardness of the tab. The first diaphragm 32 is horizontally placed on new dust-free paper, the positive plate 31 is centrally placed on one first diaphragm 32, and the four corners of the pole piece are fixed by green glue; a reference electrode 33 is provided between adjacent first diaphragms 32, a negative electrode sheet 34 is placed on the other first diaphragm 32 in the middle, and it is ensured that the negative electrode sheet 34 does not exceed the range of the positive electrode sheet 31, and the positive and negative electrode ear glue remains high. The top seal is that the battery tabs are placed along two notches of the packaging machine, and the top edge of the shell 37 is tightly attached to the notch walls. The bottom seal is formed by enabling the bottom edge of the battery to exceed the appointed range of the sealing machine, and the three-electrode battery bottom seal cannot be pressed to a copper wire. The vacuum baking is to open the cell. And the liquid injection is that after the pole piece is baked, the pole piece is stood at room temperature for cooling, and then the liquid is injected by a liquid transfer device. The vacuum standing is generally carried out in a vacuum standing box body for a set time. The vacuum side seal is sealed under vacuum condition; and the aging is to put the battery cell into an aging furnace for standing for a specified time.
In this embodiment, the housing 37 is made of an aluminum plastic film. The battery is not limited to a square aluminum case battery, but may be a cylindrical battery, a plastic case battery, or the like.
The method for obtaining the dried positive plate 31, the first diaphragm 32 and the negative plate 34 comprises the following steps: disassembling the battery, discharging the battery to an empty state, disassembling the battery core under a dry condition, and separating the top cover from the battery core; the positive electrode sheet 31, the negative electrode sheet 34, and the first separator 32 are obtained in predetermined amounts, and dried.
Specifically, when the battery is disassembled, discharging the battery to the empty electricity, disassembling the battery core in a drying room, wherein the humidity of the drying room is required to be 15+/-5, separating a top cover of the battery from the battery core, and naturally drying the top cover in the drying room for 1 hour; and taking a proper amount of positive electrode plate 31, negative electrode plate 34 and first diaphragm 32, drying in a drying room for 1 hour, and scrapping the rest diaphragms and electrolyte.
The method for obtaining the negative electrode charge transfer resistor R7, the negative electrode ion diffusion resistance R11 and the negative electrode SEI film resistance R12 comprises the following steps: and (3) performing EIS test on the three-electrode card battery with the set electric quantity by using an electrochemical workstation, connecting a negative electrode of the three-electrode card battery and a reference electrode 33 with the electrochemical workstation during the test, and fitting test results to obtain a negative electrode charge transfer resistor R7, a negative electrode ion diffusion resistance R11 and a negative electrode SEI film resistance R12.
Specifically, an electrochemical workstation is used for carrying out EIS test on a 50% SOC (residual electric quantity) three-electrode card battery, an instrument for specially testing alternating current impedance of the battery is used for carrying out test, a test result is subjected to aftertreatment by special software, and the test result is fitted to obtain a negative electrode charge transfer resistor R7, a negative electrode ion diffusion impedance R11 and a negative electrode SEI film impedance R12.
The method for obtaining the positive electrode charge transfer resistor R8 and the positive electrode ion diffusion resistance R10 comprises the following steps: and (3) performing EIS test on the three-electrode card battery with the set electric quantity by using an electrochemical workstation, connecting the positive electrode and the reference electrode 33 of the three-electrode card battery with the electrochemical workstation during the test, and fitting the test result to obtain a positive electrode charge transfer resistor R8 and a positive electrode ion diffusion impedance R10.
In the above way, the SEI mode impedance R can be obtained sei Charge transfer impedance R ct And diffusion resistance R w Is used for the polarization resistance of the crystal (C).
Specifically, an electrochemical workstation is used for carrying out EIS test on a 50% SOC three-electrode card battery, an instrument for specially testing alternating current impedance of the battery is used for carrying out test, a test result is subjected to aftertreatment by special software, and the test result is fitted to obtain an anode charge transfer resistor R8 and an anode ion diffusion impedance R10.
As shown in fig. 8, in order to test the ionic resistance of the electrolyte in the separator, a symmetrical card battery is fabricated, wherein the symmetrical card battery includes a second negative electrode current collector 41 and a second negative electrode active material coating 42, the second negative electrode current collector 41 is adhered to the second negative electrode active material coating 42, and the second negative electrode current collector 41 and the second negative electrode active material coating 42 are symmetrically designed on both sides of the card battery, and a plurality of layers of second separators 43 are disposed between the two second negative electrode active material coatings 42, thereby forming a symmetrical card battery.
In this embodiment, the second anode current collector 41, the second anode active material coating 42, and the second separator 43 are obtained by: disassembling the battery, discharging the battery to an empty state, disassembling the battery core under a dry condition, and separating the top cover from the battery core; a set amount of the second anode current collector 41, the second anode active material coating 42, and the second separator 43 are obtained, and subjected to a drying process.
The method for obtaining the diaphragm ion impedance R9 of the electrolyte in the diaphragm comprises the following steps: and (3) testing the ohmic impedance of the symmetrical card battery through the EIS, fitting the data according to the obtained test result to obtain a linear slope, and obtaining the diaphragm ion impedance R9 according to the linear slope.
If the ohmic impedance of the symmetrical card battery is R, thenWherein n is the number of membrane layers, ">Is the diaphragm ion impedance R9, ">Is the current collector resistance>Is the resistance of the active material coating. From the EIS test results of the symmetrical cells with different numbers of membrane layers, a data graph as shown in fig. 9 can be obtained, where x represents the different numbers of membrane layers, y represents the ohmic resistance of the symmetrical card cell, b=k×x+bObtaining a linear slope k through data fitting, and finally obtaining the diaphragm ion impedance R9, namely the ion resistance R of the electrolyte in the diaphragm sep,ele 。
Finally, by obtaining ohmic resistance (Rs) and polarization resistance, the obtaining of all the resistances of the DCR is achieved.
In the step S2, the method for converting the positive current collector resistor R3, the negative current collector resistor R4, the positive sheet resistor R5, the negative sheet resistor R6, the negative charge transfer resistor R7, the positive charge transfer resistor R8, the diaphragm ion resistor R9, the positive ion diffusion resistor R10, the negative ion diffusion resistor R11, and the negative SEI film resistor R12 into corresponding resistors of the secondary battery respectively includes: when the positive current collector resistor R3, the negative current collector resistor R4, the positive diaphragm resistor R5 and the negative diaphragm resistor R6 are converted into the resistances of the secondary batteries, respectively performing resistance conversion according to the areas of the positive current collector, the negative current collector, the positive diaphragm and the negative diaphragm; when the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the positive electrode ion diffusion resistance R10, the negative electrode ion diffusion resistance R11 and the negative electrode SEI film resistance R12 are converted into the resistances of the secondary batteries, the resistances are converted according to the areas of the three-electrode card batteries and the secondary batteries; when the diaphragm ion impedance R9 is converted into the resistance of the secondary battery, the conversion of the resistance is performed according to the areas of the symmetrical card battery and the secondary battery.
The obtained positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5, the negative electrode diaphragm resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the diaphragm ion impedance R9, the positive electrode ion diffusion impedance R10, the negative electrode ion diffusion impedance R11 and the negative electrode SEI film impedance R12 are all obtained from the disassembled battery, or the raw material or the newly processed small battery, so that each obtained resistance is the corresponding resistance of the small battery structure; in order to obtain the corresponding resistance of the large battery, namely the secondary battery, conversion is needed to realize the decomposition of the large battery, so that the resistances of all parts are accurately obtained.
The following describes in detail how the individual resistances are switched:
the positive current collector resistance R31 of the large cell is according to the formula: r3/r31=Calculated, wherein->Representing the area of a large cell>Representing the area of the positive current collector.
The negative current collector resistance R41 of the large cell is according to the formula: r4/r41=Calculated, wherein->Representing the area of a large cell>Representing the area of the negative electrode current collector.
The positive diaphragm resistance R51 of the large cell is according to the formula: r5/r51=Calculated, wherein->Representing the area of a large cell>Representing the area of the positive electrode membrane.
The negative electrode diaphragm resistance R61 of the large cell is according to the formula: r6/r61=Calculated, wherein->Representing the area of a large cell>Representing the area of the negative electrode membrane.
The negative charge transfer resistance R71 of the large cell is according to the formula: r7/r71= =Calculated, wherein->Representing the area of a large cell>Representing the area of the negative electrode sheet of a three-electrode card cell.
Positive charge transfer for large cellsResistor R81 is according to the formula: r8/r81=Calculated, wherein->Representing the area of a large cell>Representing the area of the positive plate of a three-electrode card cell.
The diaphragm ion impedance R91 of the large cell is according to the formula: r9/r91=Calculated, whereinRepresenting the area of a large cell>Representing the area of the positive or negative electrode sheet of a symmetrical card cell.
The positive ion diffusion resistance R101 of the large cell is according to the formula: r10/r101=Calculated, wherein->Representing the area of a large cell>Representing the area of the positive plate of a three-electrode card cell.
The negative ion diffusion resistance R111 of the large cell is according to the formula: r11/r111=Calculated, wherein->Representing the area of a large cell>Representing the area of the negative electrode sheet of a three-electrode card cell.
The negative electrode SEI film resistance R121 of the large battery is according to the formula: r12/r121=Calculated, wherein->Representing the area of a large cell>Representing the area of the negative electrode sheet of a three-electrode card cell.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. The decomposition test method of the direct current internal resistance of the secondary battery is characterized by comprising the following steps of:
step S1: testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery to obtain the ohmic resistance R1 of the positive structural member and the ohmic resistance R2 of the negative structural member; respectively calculating a positive current collector resistor R3 and a negative current collector resistor R4 according to the sizes of the positive current collector and the negative current collector; measuring positive plate resistance and negative plate resistance, and respectively calculating positive plate resistance R5 and negative plate resistance R6 according to the positive plate resistance and the negative plate resistance, and positive current collector resistance R3 and negative current collector resistance R4; manufacturing a three-electrode card battery, charging the three-electrode card battery, and performing EIS test on the three-electrode card battery with set electric quantity to obtain a negative electrode charge transfer resistor R7, a positive electrode charge transfer resistor R8, positive electrode ion diffusion resistance R10, negative electrode ion diffusion resistance R11 and negative electrode SEI film resistance R12; manufacturing symmetrical card batteries with different diaphragm layers, and testing the ohmic impedance of the symmetrical card batteries through EIS to obtain diaphragm ion impedance R9 of electrolyte in the diaphragm;
step S2: the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5, the negative electrode diaphragm resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the diaphragm ion resistor R9, the positive electrode ion diffusion resistor R10, the negative electrode ion diffusion resistor R11 and the negative electrode SEI film resistor R12 are respectively converted into direct current resistors of corresponding secondary batteries.
2. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 1, characterized in that: the method for testing the ohmic resistance of the positive structural member and the ohmic resistance of the negative structural member of the battery comprises the following steps: the method comprises the steps of respectively testing positive and negative electrode area connecting pieces and connecting resistance by using a resistance meter, wherein when the positive electrode area connecting pieces and the connecting resistance are tested, one probe of the resistance meter is contacted with a positive electrode bus bar of a battery, and the other probe is contacted with a positive electrode tab group of the battery, so that an ohmic resistance R1 of a positive electrode structural member is obtained; when the negative electrode area connecting piece and the connecting resistor are tested, one probe of the resistor is contacted with a negative electrode busbar of the battery, and the other probe is contacted with a negative electrode tab group of the battery, so that the ohmic resistor R2 of the negative electrode structural member is obtained.
3. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 1, characterized in that: the method for respectively calculating the positive current collector resistance R3 and the negative current collector resistance R4 according to the sizes of the positive current collector and the negative current collector comprises the following steps: according to the formula，/>，/>Calculating the positive current collector resistance R3, wherein +.>Is the resistivity of the positive current collector, +.>Is the width of the positive current collector tab, d1 is the length of the positive current collector tab, THK1 is the thickness of the positive current collector, +.>Is the width of the positive current collector excluding the tab, wid1 is the length of the positive current collector excluding the tab, +.>Resistance of positive current collector tab, < >>The positive current collector does not comprise a resistance of a lug; according to the formula->，/>，/>Calculating a negative current collector resistance R4, wherein +.>Is the resistivity of the negative current collector, +.>Is the width of the lug of the negative current collector, +.>Is the length of the tab of the negative current collector, THK2 is the thickness of the negative current collector, +.>Is the width of the negative current collector excluding the tab, wid2 is the length of the negative current collector excluding the tab, R41 is the resistance of the negative current collector tab, and R42 is the resistance of the negative current collector excluding the tab.
4. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 3, wherein: the method for measuring the positive plate resistance and the negative plate resistance and respectively calculating the positive plate resistance R5 and the negative plate resistance R6 according to the positive plate resistance, the negative plate resistance, the positive current collector resistance R3 and the negative current collector resistance R4 comprises the following steps: measuring positive plate resistance using a diaphragm resistance test systemThe positive sheet resistance r5=positive sheet resistance +.>-a positive current collector resistance R3; measuring the negative plate resistance by using a diaphragm resistance test system>The negative electrode sheet resistance r6=negative electrode sheet resistance +.>-a negative current collector resistance R4.
5. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 1, characterized in that: the method for manufacturing the three-electrode card battery comprises the following steps: sequentially stacking the dried positive plate, the two first diaphragms, the reference electrode and the negative plate, wherein the reference electrode is positioned between the adjacent first diaphragms to prepare a reference electrode-inserted battery cell, packaging the reference electrode-inserted battery cell by using a shell, and injecting electrolyte to obtain a battery; and (5) carrying out battery formation and capacity division to obtain the card battery with the reference electrode.
6. The decomposition test method of the direct current internal resistance of a secondary battery according to claim 5, wherein: the method for acquiring the dried positive plate, the first diaphragm and the negative plate comprises the following steps: disassembling the battery, discharging the battery to an empty state, disassembling the battery core under a dry condition, and separating the top cover from the battery core; and obtaining a set amount of positive plate, negative plate and first diaphragm, and drying the positive plate, the negative plate and the first diaphragm.
7. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 1, characterized in that: the method for obtaining the negative electrode charge transfer resistor R7, the negative electrode ion diffusion resistance R11 and the negative electrode SEI film resistance R12 comprises the following steps: and (3) performing EIS test on the three-electrode card battery with the set electric quantity by using an electrochemical workstation, connecting a negative electrode and a reference electrode of the three-electrode card battery with the electrochemical workstation during the test, and fitting test results to obtain a negative electrode charge transfer resistor R7, a negative electrode ion diffusion impedance R11 and a negative electrode SEI film resistance R12.
8. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 1, characterized in that: the method for obtaining the positive electrode charge transfer resistor R8 and the positive electrode ion diffusion resistance R10 comprises the following steps: and (3) performing EIS test on the three-electrode card battery with the set electric quantity by using an electrochemical workstation, connecting the positive electrode and the reference electrode of the three-electrode card battery with the electrochemical workstation during the test, and fitting the test result to obtain a positive electrode charge transfer resistor R8 and a positive electrode ion diffusion impedance R10.
9. The decomposition test method of the direct current internal resistance of the secondary battery according to claim 1, characterized in that: the method for converting the positive electrode current collector resistor R3, the negative electrode current collector resistor R4, the positive electrode diaphragm resistor R5, the negative electrode diaphragm resistor R6, the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the diaphragm ion resistor R9, the positive electrode ion diffusion resistor R10, the negative electrode ion diffusion resistor R11 and the negative electrode SEI film resistor R12 into corresponding resistors of the secondary battery respectively comprises the following steps: when the positive current collector resistor R3, the negative current collector resistor R4, the positive diaphragm resistor R5 and the negative diaphragm resistor R6 are converted into the resistances of the secondary batteries, respectively performing resistance conversion according to the areas of the positive current collector, the negative current collector, the positive diaphragm and the negative diaphragm; when the negative electrode charge transfer resistor R7, the positive electrode charge transfer resistor R8, the positive electrode ion diffusion resistance R10, the negative electrode ion diffusion resistance R11 and the negative electrode SEI film resistance R12 are converted into the resistances of the secondary batteries, the resistances are converted according to the areas of the three-electrode card batteries and the secondary batteries; when the diaphragm ion impedance R9 is converted into the resistance of the secondary battery, the conversion of the resistance is performed according to the areas of the symmetrical card battery and the secondary battery.
10. The decomposition test method of the direct current internal resistance of a secondary battery according to any one of claims 1 to 9, characterized in that: the ohmic impedance of the symmetrical card battery is R, thenWherein n is the number of membrane layers, ">Is the diaphragm ion impedance R9, ">Is the current collector resistance>Is the resistance of the active material coating.
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