一种基于商业电池进行三电极电池改造的制作测试方法

Abstract

This invention relates to a method for manufacturing and testing a three-electrode battery based on commercial batteries. The method mainly includes a process for modifying a commercial battery into a three-electrode battery and a process for detecting whether the manufacturing process is successful. The process for modifying a commercial battery into a three-electrode battery includes steps such as disassembling the battery casing and welding the tabs, fabricating a reference electrode, embedding the reference electrode into a core, and encapsulating it using an aluminum-plastic film. The process for detecting whether the manufacturing process is successful includes: determining whether the difference between the measured potential of the positive and negative electrodes relative to the reference potential and their respective theoretical values ​​is within the error range, and whether the difference between the positive and negative electrode potentials and the voltage difference of the entire battery meets the allowable error range, to determine whether the initial modification is successful; and determining whether the long-term changes and short-term fluctuations in the lithium plating potential are within the allowable range, to determine whether the final modification is successful. Compared with existing technologies, this invention is applicable to the modification of different types of commercial batteries, while fully ensuring the accuracy and reliability of the modified three-electrode battery.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing and testing technology, and in particular to a manufacturing and testing method for modifying a commercial battery into a three-electrode battery. Background Technology

[0002] Lithium-ion batteries have been widely used in various industries due to their advantages such as high energy density, good cycle performance, and low self-discharge. However, commercial lithium-ion batteries are usually in the form of two electrodes, making it difficult to analyze the positive and negative electrode reactions. The introduction of a reference electrode makes it possible to observe the positive and negative electrode reactions in situ. How to modify commercial batteries into reliable three-electrode batteries has become a current research hotspot. Because commercial lithium-ion batteries come in various shapes, the modification of commercial batteries into three-electrode batteries presents many difficulties. Therefore, there is an urgent need to design a method for modifying commercial batteries into three-electrode batteries applicable to various types of commercial batteries.

[0003] In existing technologies, most three-electrode battery designs begin with the battery manufacturing process. This approach doesn't involve modifying commercial batteries and makes it impossible to monitor batteries during actual service. Furthermore, while some three-electrode batteries are manufactured by modifying commercial batteries, the modification methods are cumbersome and usually only applicable to one type of battery, not others. Moreover, current technologies typically only provide instructions on how to manufacture three-electrode batteries, lacking indicators for evaluating their success. This leads to situations where manufactured three-electrode batteries exhibit significant measurement errors or are even unusable during actual use. Therefore, identifying potential risks early in the manufacturing process and discarding problematic batteries is crucial for improving the accuracy and reliability of subsequent three-electrode battery use. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology by providing a manufacturing and testing method for modifying a three-electrode battery based on a commercial battery. This method is applicable to the modification of different types of commercial batteries. At the same time, by designing a testing process, the accuracy and reliability of the modified three-electrode battery are guaranteed.

[0005] The objective of this invention can be achieved through the following technical solution: a method for manufacturing and testing a three-electrode battery based on a commercial battery, comprising the following steps:

[0006] S1. For the corresponding type of commercial battery, disassemble the casing and weld the tabs of the commercial battery.

[0007] S2. Fabricate the reference electrode;

[0008] S3. Peel open the core section, place a small piece of diaphragm and reference electrode, add electrolyte, reassemble the core and stick it tightly with green glue.

[0009] S4. Re-encapsulate the core implanted with the reference electrode using aluminum-plastic film and clamp it with a fixture.

[0010] S5. Measure the positive electrode relative to the reference potential and the negative electrode relative to the reference potential respectively, and determine whether the difference between the positive electrode relative to the reference potential and the corresponding theoretical value is within the set corresponding error range, whether the difference between the negative electrode relative to the reference potential and the corresponding theoretical value is within the set corresponding error range, and whether the difference between the positive electrode relative to the reference potential and the negative electrode relative to the reference potential and the difference between the full cell voltage is within the set corresponding error range. If all three judgment results are yes, it indicates that the preliminary modification is successful and proceed to step S6; otherwise, it indicates that the preliminary modification has failed and the current process ends.

[0011] 6) After the set time of rest, lithium plating is performed on the implanted reference electrode. When the lithium plating potential drops for the first time, it is determined whether the long-term change and short-term fluctuation of the potential are less than the corresponding preset threshold. If both of the above judgment results are yes, it indicates that the modification is successful; otherwise, it indicates that the modification has failed.

[0012] Furthermore, in step S1, if the commercial battery type is a pouch battery, the electrode tabs are welded first, and then the battery casing is disassembled.

[0013] If the commercial battery type is square or cylindrical, the battery casing should be disassembled first, and then the tabs should be soldered.

[0014] Furthermore, the position of the electrode tab welding in step S1 corresponds to the original positive and negative electrode tabs of the commercial battery, in order to extend the positive and negative electrode tabs to facilitate subsequent sealing treatment.

[0015] Further, the specific process of step S2 is as follows: immerse both ends of the enameled wire of a set length in concentrated sulfuric acid and wait for a first set time; then rinse repeatedly with deionized water until the immersed area is neutral according to pH test paper; then rinse clean with anhydrous ethanol to remove impurities; finally, bake the treated enameled wire in an oven at a set temperature and a second set time; the treated enameled wire has bare copper wires at both ends, and a tab is welded to either end to complete the fabrication of the reference electrode.

[0016] Furthermore, the core in step S3 includes a stacking process and a winding process.

[0017] Furthermore, step S5 specifically includes the following steps:

[0018] S51. Determine the theoretical values ​​of the positive electrode relative to the reference electrode and the theoretical values ​​of the negative electrode relative to the reference electrode based on the standard electrode potentials corresponding to the positive electrode material, the negative electrode material and the reference electrode material.

[0019] S52. Measure the positive electrode relative to the reference potential and the negative electrode relative to the reference potential respectively;

[0020] S53. Determine whether the difference between the measured positive electrode-to-reference potential and the theoretical value of the positive electrode-to-reference electrode is within the set corresponding error range;

[0021] Determine whether the difference between the measured negative electrode-to-reference potential and the theoretical value of the negative electrode-to-reference electrode is within the set corresponding error range;

[0022] Determine whether the difference between the positive electrode and the reference potential and the difference between the negative electrode and the reference potential and the full cell voltage are within the set corresponding error range;

[0023] If all three judgment results are yes, it indicates that the initial modification was successful and step S6 is executed; otherwise, it indicates that the initial modification failed and the current process ends.

[0024] Furthermore, the theoretical values ​​of the positive electrode to the reference electrode and the theoretical values ​​of the negative electrode to the reference electrode in step S51 are specifically as follows:

[0025] U ca_th =U ca_st -U re_st

[0026] U an_th =U an_st -U re_st

[0027] Among them, U ca_th and U an_th These are the theoretical values ​​of the positive and negative electrodes relative to the reference electrode, U. ca_st and U an_st These are the standard electrode potentials for the positive and negative electrode materials, U, respectively. re_st This is the standard electrode potential of the reference electrode material.

[0028] Further, step S53 specifically involves determining whether the following three conditions are met simultaneously:

[0029] U ca -U cath ∈ΔU ca

[0030] U an -U an_th ∈ΔU an

[0031] U ca -U an -Uall ∈ΔU all

[0032] Wherein, ΔU ca , ΔU an and ΔU all These are the corresponding error ranges for the positive electrode potential, negative electrode potential, their respective theoretical potentials, and the total cell voltage. These values ​​are obtained from statistical results. When the voltage exceeds the corresponding error range, it indicates that the battery has an internal short circuit fault, and the initial modification of the three-electrode battery has failed. When all voltages meet the corresponding error range, it can be determined that the three-electrode battery has no obvious short circuit fault, that is, the initial modification has been successful.

[0033] Furthermore, in step S6, determining whether the long-term change and short-term fluctuation of the potential are less than the corresponding preset threshold specifically involves:

[0034] U a <U L

[0035] U b <U s

[0036] Among them, U a For the long-term time-scale variation of potential, U b U represents the maximum value of the change over a short time scale. L and U s These are preset long-term time-scale change thresholds and short-term time-scale fluctuation thresholds, respectively. Their values ​​are obtained from statistical results. When the potential change during the lithium plating process exceeds the preset thresholds of the above constraints, it indicates that the reference electrode is unstable inside the battery, and the three-electrode battery modification fails. When the potential change during the lithium plating process meets the preset thresholds of the above constraints, it indicates that the three-electrode battery modification is successful.

[0037] Furthermore, in step S6, the long time scale specifically refers to the entire lithium plating process time excluding the first 20 minutes, and the short time scale specifically refers to the 1-minute time interval within the entire lithium plating time excluding the first 20 minutes.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] I. This invention addresses different types of commercial batteries by disassembling the casing and welding the tabs, then fabricating and implanting a reference electrode. The positive and negative electrode potentials relative to a reference are measured to initially determine the success of the modification. The implanted reference electrode is then lithium-plated. Once the lithium plating potential initially decreases, the success of the modification is determined by assessing whether the long-term potential change and short-term fluctuations are below corresponding preset thresholds. This approach is applicable to the modification of various types of commercial batteries and, based on the designed testing process, can accurately evaluate the success of three-electrode battery modification, thereby ensuring the accuracy and reliability of the manufactured three-electrode batteries.

[0040] Second, this invention first determines whether the difference between the measured positive and negative electrode potentials and their respective theoretical values ​​is within the error range, and whether the difference between the two and the difference of the full cell is within the error range, thereby determining whether the preliminary modification is successful. It can detect in advance whether there are short circuits between the reference electrode and the positive and negative electrodes, as well as between the positive and negative electrodes of the full cell. Furthermore, after the lithium plating operation, it further determines whether the long-term potential changes and short-term fluctuations are less than their respective preset thresholds, to determine whether the reference electrode is stable inside the battery. Thus, by fully exploring battery characteristic phenomena and conducting corresponding tests during the modification process, it can accurately identify unsuccessful three-electrode batteries in advance, fully ensuring the accuracy and reliability of the modified three-electrode batteries. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0042] Figure 2 This is a schematic diagram of the internal structure of the modified three-electrode battery in the embodiment;

[0043] Figure 3 This is a schematic diagram of the modified three-electrode battery in the embodiment;

[0044] Figure 4a This is a schematic diagram illustrating the normal potential changes during the lithium plating process.

[0045] Figure 4b This is a schematic diagram illustrating the significant potential fluctuations during the lithium plating process.

[0046] Figure 5 This is a schematic diagram of the impedance test of the successfully modified three-electrode battery in the embodiment;

[0047] Figure 6 This is a schematic diagram of the voltage change during the charge and discharge test of the successfully modified three-electrode battery in the embodiment. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0049] Example

[0050] like Figure 1 As shown, a method for manufacturing and testing a three-electrode battery based on a commercial battery includes the following steps:

[0051] I. For different types of commercial batteries, perform disassembly of the battery casing and welding of the electrode tabs:

[0052] For pouch batteries—weld the tabs first, then disassemble the battery casing;

[0053] For square and cylindrical batteries—disassemble the battery casing first, then weld the tabs.

[0054] The welding tabs are located at the original positive and negative tabs of the battery. The main purpose is to extend the positive and negative tabs to facilitate sealing later.

[0055] II. Preparation of reference electrode: Immerse about 1 cm from both ends of a certain length of enameled wire in concentrated sulfuric acid and wait for 20 minutes;

[0056] Rinse repeatedly with deionized water until the soaked area is neutral according to pH test paper.

[0057] Then rinse thoroughly with anhydrous ethanol to remove impurities;

[0058] Finally, the treated enameled wire was baked in an oven at 60°C for 20 minutes. The treated enameled wire has bare copper wires at both ends and a tab welded to either end.

[0059] 3. Peel off the core section, place a small piece of diaphragm and reference electrode, add electrolyte, reassemble the core and glue it tightly with green glue.

[0060] Fourth, the core with the implanted reference electrode is repackaged with aluminum-plastic film and clamped with a fixture. The core process includes both stacking and winding processes.

[0061] Fifth, determine whether the difference between the measured positive and negative electrode potentials and their respective theoretical values ​​is within the error range, and whether the difference between the two and the difference of the full cell is within the error range, and then determine whether the preliminary modification is successful;

[0062] Specifically, the calculation methods for the theoretical values ​​of the positive and negative electrodes relative to the reference electrode are as follows:

[0063] U ca_th =U ca_st -U re_st

[0064] U an_th =U an_st -U re_st

[0065] In the formula U ca_thand U an_th These represent the theoretical values ​​of the positive and negative electrodes relative to the reference electrode, respectively; U ca_st and U an_st U represents the standard electrode potentials of the positive and negative electrode materials, respectively; re_st This indicates the standard electrode potential of the reference electrode material.

[0066] Then measure the voltage U between the positive electrode and the reference electrode respectively. ca The voltage U between the negative electrode and the reference electrode an The voltage U between the positive and negative terminals all The measured voltage should meet the following error conditions:

[0067] U ca -U ca_th ∈ΔU ca

[0068] U an -U an_th ∈ΔU an

[0069] U ca -U an -U all ∈ΔU all

[0070] In the formula ΔU ca , ΔU an and ΔU all These represent the reasonable error ranges between the positive electrode potential, negative electrode potential, and their respective theoretical potentials, as well as the total cell voltage. These values ​​are obtained from statistical results. If the voltage exceeds these ranges, it indicates an internal short circuit fault in the battery, and the three-electrode battery modification has failed. If each voltage meets the above error ranges, it can be preliminarily determined that the three-electrode battery has no obvious short circuit fault, and further testing is required.

[0071] 6. After the set time for settling, lithium plating is performed on the reference electrode. After the lithium plating potential drops for the first time, it is determined whether the long-term change and short-term fluctuation of the potential are within their respective allowable ranges to determine whether the fabrication is successful.

[0072] Specifically, the long-time scale change in potential is U a The maximum value of the short-time scale change is U b Both should meet the following threshold conditions:

[0073] U a <U L

[0074] U b <U s

[0075] In the formula U L and Us These represent the long-term timescale variation threshold and the short-term timescale fluctuation threshold, respectively, and their values ​​are obtained from statistical results or other methods. When the potential change during the lithium plating process exceeds the above-mentioned constraint thresholds, it indicates that the reference electrode is unstable inside the battery, and the three-electrode battery modification fails. When the potential change during the lithium plating process meets the above-mentioned constraint thresholds, it indicates that the three-electrode battery modification is successful.

[0076] The long timescale refers to the entire lithium plating process excluding the first 20 minutes, while the short timescale refers to a 1-minute interval within the entire lithium plating time excluding the first 20 minutes. The above lithium plating method involves a constant current lithium plating process, and the constant current lithium plating duration is greater than 21 minutes.

[0077] This embodiment applies the above technical solution to modify commercial soft-pack batteries. The main process is as follows:

[0078] 1) First, select a commercial pouch battery with nickel-cobalt-manganese positive electrode and graphite negative electrode for modification. The internal core of this pouch battery has a wound structure, such as... Figure 2 A schematic diagram of the unfolding of the core;

[0079] 2) Weld two new nickel tabs to the positive and negative terminals of the battery, respectively;

[0080] 3) Disassemble the aluminum-plastic film casing of commercial soft-pack batteries in the glove box. During disassembly, the aluminum-plastic film seal at the tab end is difficult to remove; retain it. Figure 2 The image shows the residual aluminum-plastic film after disassembling the battery casing.

[0081] 4) Fabricate a reference electrode.

[0082] Select an enameled wire of suitable length with a diameter of 20 μm. Immerse approximately 1 cm of both ends in concentrated sulfuric acid for 20 minutes. After immersion, rinse repeatedly with deionized water and test the pH using pH paper until the immersed area is neutral. Then rinse thoroughly with anhydrous ethanol to remove impurities. After rinsing, place the treated enameled wire in an oven and bake at 60°C for 20 minutes. The treated enameled wire will have bare copper wire at both ends. Finally, solder a tab to either end to complete the reference electrode fabrication.

[0083] 5) In the glove box, the reference electrode is implanted inside the battery.

[0084] like Figure 2As shown, first, a small piece of separator is cut, large enough to cover the exposed copper wire of the reference electrode. Then, part of the core is unrolled, separating the positive electrode, negative electrode, and separator. In this example, the outermost core is unrolled, and the reference electrode is implanted between the separator and the positive electrode. First, the small piece of separator is placed on the positive electrode, and a small amount of electrolyte is added to fix the small piece of separator. Then, the unwelded end of the reference electrode is placed on the small piece of separator, ensuring that the exposed copper wire is completely placed on the small piece of separator. To compensate for the electrolyte evaporating during the unrolling of the core, electrolyte is added to the positive and negative electrode plates after the core is unrolled, and the core is rerolled. Usually, there is a core covering material on the outside of the core, and finally, the core covering material is glued in place using green adhesive.

[0085] 6) Inside the glove box, the battery core after the reference electrode has been implanted is resealed using aluminum-plastic film. To ensure tight contact between the positive and negative electrodes and to prevent exposed copper wires from shifting inside the core, the resealed battery is finally clamped securely with clamps and dovetail clips. Figure 3 As shown.

[0086] 7) Use a multimeter to measure the potential of the positive electrode relative to the reference and the negative electrode relative to the reference. Compare the measured results with the theoretical values ​​to preliminarily determine whether the three-electrode battery modification was successful. This measurement procedure was introduced mainly to consider whether the implanted reference electrode damaged the separator during the three-electrode battery modification process, causing short circuits between the reference electrode and the positive and negative electrodes, as well as between the positive and negative electrodes.

[0087] Considering copper as the reference electrode, the theoretical value of its standard potential, as found in the literature, is U. re_st = +0.337V. If the negative electrode is lithium-intercalated graphite, its standard potential is close to that of lithium. Therefore, the theoretical value of the negative electrode standard potential is U. an_st = -3.04V. The positive electrode is a nickel-cobalt-manganese material for lithium intercalation. According to the literature, its theoretical electrode standard potential U... ca_st Approximately +0.7V. The calculation method using the positive and negative electrodes relative to the reference electrode.

[0088] U ca_th =U ca_st -U re_st

[0089] U an_th =U an_st -U re_st

[0090] The theoretical value U of the positive electrode relative to the reference electrode is obtained. ca_th The theoretical value U of the negative electrode relative to the reference electrode is 0.363V. an_th The value is -2.703V. Furthermore, in this example, based on statistical results, the error range is determined to be ΔU. ca = [-0.2, 0.2], ΔUan = [-0.4, 0.4], ΔU all = [-0.5, 0.5]. A multimeter measured the positive electrode of the modified three-electrode battery to be 0.3V, the negative electrode to be -2.5V, and the total cell voltage to be 3.1V. Therefore, the following conditions are met:

[0091] U ca -U ca_th ∈ΔU ca

[0092] U an -U an_th ∈ΔU an

[0093] U ca -U an -U all ∈ΔU all

[0094] This indicates that the initial modification of the three-electrode battery has been successful.

[0095] 8) After standing for 24 hours, lithium is plated onto the reference electrode. After 20 minutes of lithium plating, the long-term change and short-term fluctuation of the potential are less than their respective thresholds to determine whether the modification is successful.

[0096] During lithium plating, the change in potential reflects the changes in the battery's internal structure and materials. Initially, due to lithium deposition on the reference electrode surface and polarization, the electrode potential initially rises significantly. As the plating process stabilizes, the polarization gradually decreases, causing the plating potential to gradually decline and stabilize. Furthermore, the reference electrode may experience instability for a period during the initial lithium plating stage; therefore, this criterion does not process data from the first 20 minutes.

[0097] In this embodiment, the lithium plating current is 2uA. During the lithium plating process, the change in lithium plating potential is observed. Based on the statistical results, the long-term time scale change threshold U is determined. L and short-timescale fluctuation threshold U S The values ​​are 30mV and 0.5mV, respectively. Figure 4a and 4b This demonstrates the potential change during the lithium plating process at the cathode, with the long-time potential change being U. a The maximum short-term fluctuation is U. b It satisfies U a L U b S Therefore, the three-electrode modification can be considered successful. For the problematic battery, this embodiment demonstrates two scenarios: Figure 4a Demonstrating the first visible potential on a long time scale U a >U​​L Despite short-term fluctuations U b1 S However, during the short-term fluctuations of U in the intermediate process b2 >U S Therefore, the maximum short-term fluctuation U b Satisfy U b S ; Figure 4b The second scenario is shown, where the potential fluctuations are significantly greater than the threshold regardless of the long-term or short-term time scale. Therefore, both scenarios are judged as modification failures.

[0098] Figure 5 and Figure 6 The diagrams show the impedance and voltage during the charging and discharging process of the three-electrode battery successfully modified in this embodiment.

[0099] In summary, this technical solution is based on the modification of commercial lithium-ion batteries into three-electrode batteries and is applicable to all types of commercial lithium-ion batteries. The three-electrode battery modification process is simple, convenient, and yields reliable results. Furthermore, to identify unsuccessful three-electrode batteries in advance, a testing procedure was designed during the manufacturing process to evaluate the success of the modification, which greatly improves the reliability of the test results. The method proposed in this technical solution is simple to operate and applicable to pouch, cylindrical, and prismatic batteries. The designed testing procedure ensures the accuracy and reliability of the modified three-electrode batteries.​​

Claims

1. A method for fabricating and testing a three-electrode battery based on a commercial battery, characterized in that, Includes the following steps: S1. For the corresponding type of commercial battery, disassemble the casing and weld the tabs of the commercial battery. S2. Fabricate the reference electrode; S3. Peel open the core section, place a small piece of diaphragm and reference electrode, add electrolyte, reassemble the core and stick it tightly with green glue. S4. Re-encapsulate the core implanted with the reference electrode using aluminum-plastic film and clamp it with a fixture. S5. Measure the positive electrode relative to the reference potential and the negative electrode relative to the reference potential respectively, and determine whether the difference between the positive electrode relative to the reference potential and the corresponding theoretical value is within the set corresponding error range, whether the difference between the negative electrode relative to the reference potential and the corresponding theoretical value is within the set corresponding error range, and whether the difference between the positive electrode relative to the reference potential and the negative electrode relative to the reference potential and the difference between the full cell voltage is within the set corresponding error range. If all three judgment results are yes, it indicates that the preliminary modification is successful and proceed to step S6; otherwise, it indicates that the preliminary modification has failed and the current process ends. S6. After the set time of rest, perform lithium plating on the implanted reference electrode. When the lithium plating potential drops for the first time, determine whether the long-term change and short-term fluctuation of the potential are less than the corresponding preset threshold. If both of the above judgment results are yes, it indicates that the modification is successful; otherwise, it indicates that the modification has failed.

2. The method for manufacturing and testing a three-electrode battery based on a commercial battery, as described in claim 1, is characterized in that... In step S1, if the commercial battery type is a pouch battery, the electrode tabs are welded first, and then the battery casing is disassembled. If the commercial battery type is square or cylindrical, the battery casing should be disassembled first, and then the tabs should be soldered.

3. The method for fabricating and testing a three-electrode battery based on a commercial battery, as described in claim 1, is characterized in that... In step S1, the position of the electrode tab welding corresponds to the original positive and negative electrode tabs of the commercial battery. The purpose is to extend the positive and negative electrode tabs to facilitate subsequent sealing treatment.

4. The method for manufacturing and testing a three-electrode battery based on a commercial battery, as described in claim 1, is characterized in that... The specific process of step S2 is as follows: Immerse both ends of the enameled wire of a set length in concentrated sulfuric acid and wait for the first set time; then rinse it several times with deionized water until the pH test paper shows that the immersed part is neutral; then rinse it clean with anhydrous ethanol to remove impurities; finally, use an oven to bake the treated enameled wire at a set temperature and a second set time; the treated enameled wire has bare copper wires at both ends, and a tab is welded to either end to complete the fabrication of the reference electrode.

5. The method for manufacturing and testing a three-electrode battery based on a commercial battery, as described in claim 1, is characterized in that... The core in step S3 includes a stacking process and a winding process.

6. The method for manufacturing and testing a three-electrode battery based on a commercial battery, as described in claim 1, is characterized in that... Step S5 specifically includes the following steps: S51. Determine the theoretical values ​​of the positive electrode relative to the reference electrode and the theoretical values ​​of the negative electrode relative to the reference electrode based on the standard electrode potentials corresponding to the positive electrode material, the negative electrode material and the reference electrode material. S52. Measure the positive electrode relative to the reference potential and the negative electrode relative to the reference potential respectively; S53. Determine whether the difference between the measured positive electrode-to-reference potential and the theoretical value of the positive electrode-to-reference electrode is within the set corresponding error range; Determine whether the difference between the measured negative electrode-to-reference potential and the theoretical value of the negative electrode-to-reference electrode is within the set corresponding error range; Determine whether the difference between the positive electrode and the reference potential and the difference between the negative electrode and the reference potential and the full cell voltage are within the set corresponding error range; If all three judgment results are yes, it indicates that the initial modification was successful and step S6 is executed; otherwise, it indicates that the initial modification failed and the current process ends.

7. The method for fabricating and testing a three-electrode battery based on a commercial battery, as described in claim 6, is characterized in that... The theoretical values ​​of the positive electrode and the negative electrode relative to the reference electrode in step S51 are specifically as follows: IN ca_th =U ca_st -IN re_st IN an_th =U an_st -IN re_st Among them, U ca_th and U an_th These are the theoretical values ​​of the positive and negative electrodes relative to the reference electrode, U. ca_st and U an_st These are the standard electrode potentials for the positive and negative electrode materials, U, respectively. re_st This is the standard electrode potential of the reference electrode material.

8. The method for fabricating and testing a three-electrode battery based on a commercial battery, as described in claim 7, is characterized in that... Specifically, step S53 involves determining whether the following three conditions are met simultaneously: IN ca -IN ca_th ∈ΔU ca IN an -IN an_th ∈ΔU an IN ca -IN an -IN all ∈ΔU all Wherein, ΔU ca , ΔU an and ΔU all These are the corresponding error ranges for the positive electrode potential, negative electrode potential, their respective theoretical potentials, and the total cell voltage. These values ​​are obtained from statistical results. When the voltage exceeds the corresponding error range, it indicates that the battery has an internal short circuit fault, and the initial modification of the three-electrode battery has failed. When all voltages meet the corresponding error range, it can be determined that the three-electrode battery has no obvious short circuit fault, that is, the initial modification has been successful.

9. The method for fabricating and testing a three-electrode battery based on a commercial battery, as described in claim 1, is characterized in that... The specific steps in step S6, such as determining whether the long-term change and short-term fluctuation of the potential are less than the corresponding preset threshold, are as follows: IN a <In L IN b <In s Among them, U a For the long-term time-scale variation of potential, U b U represents the maximum value of the change over a short time scale. L and U S These are preset long-term time-scale change thresholds and short-term time-scale fluctuation thresholds, respectively. Their values ​​are obtained from statistical results. When the potential change during the lithium plating process exceeds the preset thresholds of the above constraints, it indicates that the reference electrode is unstable inside the battery, and the three-electrode battery modification fails. When the potential change during the lithium plating process meets the preset thresholds of the above constraints, it indicates that the three-electrode battery modification is successful.

10. The method for manufacturing and testing a three-electrode battery based on a commercial battery, as described in claim 9, is characterized in that... In step S6, the long time scale specifically refers to the entire lithium plating process time excluding the first 20 minutes, and the short time scale specifically refers to the 1-minute time interval within the entire lithium plating time excluding the first 20 minutes.

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