A method for preparing a reference electrode and a three-electrode lithium-ion battery

Abstract

This invention discloses a method for preparing a reference electrode and a three-electrode lithium-ion battery, relating to the field of lithium-ion battery preparation technology. The method includes: disassembling a pre-conditioned pouch cell in a vacuum glove box environment to obtain a positive electrode sheet; removing the active coating from both sides of the positive electrode sheet, retaining only a portion of the active coating on one side; uniformly slicing the coated positive electrode sheet to obtain an initial reference electrode with an upper section consisting of a single-sided active coating area and a lower section consisting of an inactive conductive aluminum foil area; taking a copper wire of a predetermined length and removing a portion of the polyurethane coating from the surface of the copper wire; placing the coated end of the copper wire in the aluminum foil area of ​​the initial reference electrode, and then winding and folding the aluminum foil area to wrap and fix the copper wire, thus preparing the reference electrode. The reference electrode prepared by this invention exhibits superior strength, stability, and a longer service life.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, and in particular to a method for preparing a reference electrode and a three-electrode lithium-ion battery. Background Technology

[0002] Lithium-ion batteries, due to their advantages such as small size, high energy density, and environmental friendliness, have been increasingly widely used in various electronic products and new energy vehicles. To study the electrochemical performance of lithium-ion batteries, a three-electrode battery is typically fabricated from the lithium-ion battery under test for performance testing and analysis. A three-electrode battery is formed by introducing a reference electrode as the third electrode into a complete lithium-ion battery. Three-electrode battery technology is widely used in potential monitoring, impedance analysis, and electrochemical reaction principle analysis of lithium-ion batteries. Currently, the most commonly used reference electrode in three-electrode batteries is a lithium metal sheet and copper wire lithium plating scheme. However, lithium metal is chemically reactive and often undergoes rapid side reactions with the electrolyte, leading to performance failure and making long-term monitoring of the internal electrochemical reactions of the battery impossible.

[0003] To address this, various reference electrodes and their preparation methods have been proposed in existing technologies. One approach involves designing a lithium-intercalated compound with a wide potential plateau, such as lithium iron phosphate or lithium titanate, as the reference electrode for a three-electrode system. These lithium-intercalated compounds possess stable potentials and electrochemical activity, are not easily contaminated or passivated by the electrolyte, and theoretically can be used as reference electrodes for long-term monitoring of the battery's internal state. However, this approach has not been widely adopted due to electrode manufacturing and encapsulation issues. For example, coating the surface of a metal wire with lithium titanate slurry is problematic because the extremely fine wire has a very small surface area, making the coating prone to peeling off. Furthermore, the metal wire carrier itself has very low mechanical strength, making it extremely easy to break during encapsulation and transfer. Additionally, lithium titanate requires a certain degree of lithium intercalation / deintercalation reaction. Due to its extremely small surface area, even a small charge / discharge current can cause a significant polarization effect on the reference electrode, resulting in poor performance.

[0004] Another method for preparing a reference electrode for a three-electrode battery is to implant pre-modified lithium titanate and lithium iron phosphate electrodes into the battery as reference electrodes. However, this method also has many problems. The choice of electrode size greatly affects the performance of the reference electrode. If the size and thickness of the reference electrode are too large, it may even affect the normal lithium insertion and extraction reaction of the battery itself, resulting in lithium deposition around the reference electrode in the first few cycles, affecting the judgment of battery performance. If the size of the reference electrode is too small, it is easy to tear at the contact point between the active and inactive conductive areas due to stress concentration. In addition, the inactive conductive area of ​​the reference electrode is usually only a thin single-layer metal foil, which is very easy to break when welding with the external leads. The success rate of three-electrode batteries prepared in this way is low and the reliability is poor.

[0005] In other words, existing reference electrodes used in three-electrode systems suffer from problems such as limited lifespan, poor stability (i.e., poor performance), and low strength (extremely prone to breakage), which in turn can significantly affect the success rate and reliability of three-electrode lithium-ion batteries, as well as the accuracy of lithium-ion battery potential monitoring, impedance analysis, and electrochemical reaction principle analysis. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a method for preparing a reference electrode and a three-electrode lithium-ion battery. By limiting the size and thickness of the long-term effective lithium iron phosphate reference electrode, a special-shaped reference electrode that is conducive to lead-out packaging is formed, thereby enhancing the strength and stability of the reference electrode. Furthermore, through verification of a three-electrode lithium-ion battery using this reference electrode, the lifespan of the reference electrode is also significantly improved, solving the problems of slow development process, poor lead-out packaging, and very limited lifespan of existing reference electrodes.

[0007] In a first aspect, the present invention provides a method for preparing a reference electrode.

[0008] A method for preparing a reference electrode, comprising:

[0009] Disassemble the pre-conditioned pouch cell in a vacuum glove box environment to obtain the positive electrode sheet;

[0010] The active coating on both sides of the positive electrode is wiped off, leaving only a portion of the active coating on one side;

[0011] The positive electrode sheet after the coating is wiped off is uniformly slit to obtain an initial reference electrode with an upper section of single-sided active coating area and a lower section of inactive conductive aluminum foil area;

[0012] Take a copper wire of a set length and remove part of the polyurethane coating from the surface of the copper wire;

[0013] One end of the copper wire with the surface coating removed is placed in the aluminum foil area of ​​the initial reference electrode, and the copper wire is wrapped and fixed by winding and folding the aluminum foil area to prepare the reference electrode.

[0014] Further technical solutions, including pre-regulated pouch batteries, include:

[0015] Fresh pouch batteries are charged and discharged in an ambient temperature chamber to adjust the battery's state of charge (SOC) to a preset value; the preset value is 50%.

[0016] A further technical solution involves using N-methylpyrrolidone to remove the coating from the obtained positive electrode sheet.

[0017] In a further technical solution, the length of the single-sided active coating area is 1-2.5cm and the width is 0.1-3mm; the length of the non-active conductive aluminum foil area is 1-2cm and the width is 2-6mm.

[0018] A further technical solution involves taking a copper wire with a polyurethane coating of a specified specification and length, immersing one end of the copper wire in a concentrated sulfuric acid environment for 1 cm in length and 30-40 minutes.

[0019] After soaking and removing the copper wires, the exposed copper wires were ultrasonically cleaned with deionized water and ethanol respectively. After cleaning, they were dried in an oven at 80°C for later use.

[0020] In a further technical solution, the length of the copper wire selected is 10 to 15 meters.

[0021] A further technical solution involves wrapping and fixing the copper wire in the folded aluminum foil area, and then using insulating adhesive to initially fix the shape of the wrapping.

[0022] Secondly, the present invention provides a method for preparing a three-electrode lithium-ion battery.

[0023] A method for preparing a three-electrode lithium-ion battery, comprising:

[0024] A reference electrode is prepared using the reference electrode preparation method described in the first aspect. The reference electrode is then implanted between the positive and negative electrode plates of a lithium-ion battery cell, and at least one separator is used to isolate the reference electrode from the positive and negative electrode plates.

[0025] After the reference electrode is implanted into the battery cell, it is packaged. During the packaging process, the aluminum foil area of ​​the lower section of the reference electrode is placed in the heat-sealing area to heat-seal the copper wire, thus completing the secondary reinforcement.

[0026] The encapsulated lithium-ion battery with a reference electrode is baked, injected with electrolyte, and formed to finally prepare a three-electrode lithium-ion battery.

[0027] In a further technical solution, positive electrode plates and negative electrode plates are continuously spaced apart inside the lithium-ion battery cell, and an original separator is provided between adjacent positive and negative electrode plates.

[0028] A reference electrode is implanted into the battery cell. A short diaphragm is placed between the active coating side of the reference electrode and the electrode sheet, while the original diaphragm is placed between the other side of the reference electrode and the electrode sheet.

[0029] A further technical solution involves welding a nickel strip to one end of the copper wire extending from the reference electrode.

[0030] The above one or more technical solutions have the following beneficial effects:

[0031] 1. This invention provides a method for preparing a reference electrode and a three-electrode lithium-ion battery. By limiting the size and thickness of the long-term effective lithium iron phosphate reference electrode, a special-shaped reference electrode that is conducive to lead-out packaging is made, thereby enhancing the strength and stability of the reference electrode. Furthermore, by verifying the three-electrode lithium-ion battery using this reference electrode, an ideal three-electrode potential curve is obtained, further verifying that the lifespan of the reference electrode is also significantly improved. This solves the problems of slow development process of existing reference electrodes, poor lead-out packaging of reference electrodes, and very limited lifespan of reference electrodes.

[0032] 2. The preparation method of the reference electrode and three-electrode lithium-ion battery proposed in this invention has been well applied in lithium iron phosphate-graphite and high-nickel ternary-silicon-carbon systems. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0034] Figure 1 This is a schematic diagram of the preparation method of the reference electrode in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the reference electrode being implanted into the battery cell in an embodiment of the present invention;

[0036] Figure 3 This is a potential monitoring diagram of the reference electrode of the implanted dry cell in an embodiment of the present invention;

[0037] Figure 4 This is a potential monitoring diagram of a reference electrode implanted with a cycle-stabilized battery cell and encapsulated in an embodiment of the present invention, and an existing reference electrode.

[0038] Among them, 1. Existing three-electrode soft-pack battery; 2. Coarse copper wire; 3. Inactive conductive aluminum foil area in the lower section of the reference electrode; 4. Single-sided active coating area in the upper section of the reference electrode; 5. Improved three-electrode soft-pack battery; 6. Heat-sealed area at the junction of aluminum foil and copper wire; 7. Lithium iron phosphate reference electrode; 8. Short separator; 9. Original separator; 10. Negative electrode sheet. Detailed Implementation

[0039] It should be noted that the following detailed descriptions are exemplary and are intended only to describe specific embodiments and to provide further explanation of the invention, and are not intended to limit the scope of exemplary embodiments of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Example 1

[0041] To address the problems of slow development processes, poor lead-out packaging, and limited lifespan of existing reference electrodes, this embodiment proposes a method for preparing a reference electrode. The method involves pre-modulating the state of charge (SOC) of a pouch cell and disassembling it to obtain the positive electrode sheet. The extracted positive electrode sheet is then slitted, cleaned, and cut, with specific limitations on its size and thickness. This results in a uniquely shaped reference electrode that facilitates lead-out packaging. A thick copper wire is then used to contact the upper aluminum foil portion of the reference electrode, which is then wound and fixed before undergoing two hot-pressing processes. After packaging, an external potential monitoring instrument is used to verify its effectiveness, further validating the improved lifespan and performance of the reference electrode prepared in this embodiment.

[0042] Specifically, the method for preparing a reference electrode provided in this embodiment includes the following steps:

[0043] Disassemble the pre-conditioned pouch cell in a vacuum glove box environment to obtain the positive electrode sheet;

[0044] The active coating on both sides of the positive electrode is wiped off, leaving only a portion of the active coating on one side;

[0045] The positive electrode sheet after the coating is wiped off is uniformly slit to obtain an initial reference electrode with an upper section of single-sided active coating area and a lower section of inactive conductive aluminum foil area;

[0046] Take a copper wire of a set length and remove part of the polyurethane coating from the surface of the copper wire;

[0047] One end of the copper wire with the surface coating removed is placed in the aluminum foil area of ​​the initial reference electrode, and the copper wire is wrapped and fixed by winding and folding the aluminum foil area to prepare the reference electrode.

[0048] The following content provides a more detailed description of the preparation method of the reference electrode proposed in this embodiment.

[0049] Step S1: Take a fresh pouch cell (i.e., an existing three-electrode pouch cell 1) and place it in a room temperature incubator. Charge and discharge the fresh pouch cell in this incubator to adjust the battery's SOC (State of Charge, reflecting the battery's remaining capacity) to a preset value. In this embodiment, considering that lithium iron phosphate is in a plateau region with a very stable potential when the SOC is 50%, this preset value is set to 50%.

[0050] Step S2: In a vacuum glove box environment, disassemble the pouch cell that has been pre-adjusted to SOC in step S1 to obtain the positive electrode.

[0051] Step S3: Remove the active coating from both sides of the positive electrode sheet, leaving only a portion of the active coating on one side. Considering the fixed specifications and extremely thinness of the aluminum foil used in battery production, thickness reduction is achieved by removing the coating. Specifically, in a glove box environment, N-methylpyrrolidone (NMP) is used to remove the surface active coating from the removed positive electrode sheet, removing one side of the coating and half of the coating on the other side, leaving only a portion of the coating on one side. This reduces the thickness of the reference electrode, which helps to mitigate the impact on the normal lithium insertion / extraction of the battery. In this embodiment, the thickness of the reference electrode is controlled to be between 22 and 72 μm through removal.

[0052] Step S4: After the coating is removed, the positive electrode sheet is uniformly slit to obtain an initial reference electrode with an upper section being a single-sided active coating area and a lower section being an inactive conductive aluminum foil area.

[0053] Specifically, such as Figure 1 As shown, the positive electrode sheet after partial removal of the active coating is uniformly slit to obtain an initial reference electrode. The reference electrode includes a lower section of inactive conductive aluminum foil region 3 and an upper section of single-sided active coating region 4. The upper section of single-sided active coating region is a narrow strip with a length of 1 to 2.5 cm and a width of 0.1 to 3 mm. The lower section of inactive conductive aluminum foil region is divided into square areas with a length of 1 to 2 cm and a width of 2 to 6 mm.

[0054] Step S5: Take a copper wire of a set length and remove part of the polyurethane coating from the surface of the copper wire.

[0055] Specifically, copper wires with a polyurethane coating and a specification of 60-120 mm and a set length of 10-15 m are selected. One end of the copper wire is immersed in concentrated sulfuric acid for 30-40 minutes for a length of 1 cm. After immersion, the exposed copper wire is ultrasonically cleaned with deionized water and ethanol, respectively. After cleaning, it is dried in an oven at 80°C for later use, thus obtaining coarse copper wire 2. In this embodiment, copper wire with a specification of 120 mm and a polyurethane coating is used. The tail 1 cm length is immersed in concentrated sulfuric acid for 30 minutes and ultrasonically cleaned, then dried at 80°C for later use.

[0056] Step S6: Place the copper wire with the surface coating removed at one end on the aluminum foil area of ​​the initial reference electrode, and wrap and fix the copper wire by winding and folding the aluminum foil area to prepare the reference electrode.

[0057] Specifically, in a glove box environment, one end of a copper wire with its surface coating removed is placed on the surface of the aluminum foil area of ​​the reference electrode. The folded aluminum foil area wraps and fixes one end of the copper wire, ensuring close contact between the conductive area of ​​the copper wire and the aluminum foil. Furthermore, the folding and wrapping method effectively improves the strength of the reference electrode. Preferably, after wrapping and fixing the copper wire with the folded aluminum foil area, insulating adhesive is used to initially fix the wrapping shape.

[0058] In this embodiment, the SOC of the electrode to be used is prepared according to the above steps, the single-sided coating is wiped off, and the electrode is evenly slit. The thickness of the reference electrode is controlled to be 25 μm, the active area is a narrow strip area of ​​2 cm × 2 mm, and the inactive conductive area is a rectangular area of ​​1 cm × 2 mm. Then, a copper wire of specification 120 with a polyurethane coating is used. The tail 1 cm length is soaked in concentrated sulfuric acid for 30 min and ultrasonically cleaned. After drying at 80°C, it is ready for use. In a glove box environment, the treated tail part of the copper wire is placed on the upper conductive area of ​​the reference electrode. The excess aluminum foil is folded to wrap the copper wire, and the contact area between the two is pressed. Insulating glue is used for preliminary fixation. The reference electrode is thus prepared.

[0059] Example 2

[0060] This embodiment proposes a method for preparing a three-electrode lithium-ion battery. A reference electrode is prepared using the method for preparing a reference electrode proposed in Embodiment 1 above. This reference electrode is then introduced into the lithium-ion battery as the third electrode, thus obtaining a three-electrode lithium-ion battery. The specific preparation method includes:

[0061] A reference electrode is prepared using the reference electrode preparation method proposed in Example 1. The reference electrode is then implanted between the positive and negative electrode plates of a lithium-ion battery cell, and at least one separator is used to isolate the reference electrode from the positive and negative electrode plates.

[0062] After the reference electrode is implanted into the battery cell, it is packaged. During the packaging process, the aluminum foil area of ​​the lower section of the reference electrode is placed in the heat-sealing area to heat-seal the copper wire, thus completing the secondary reinforcement.

[0063] The encapsulated lithium-ion battery with a reference electrode is baked, injected with electrolyte, and formed to finally prepare a three-electrode lithium-ion battery.

[0064] The following content provides a more detailed description of the preparation method of the three-electrode lithium-ion battery proposed in this embodiment.

[0065] Step S1: A reference electrode is prepared by steps S1 to S6 in Example 1, and the reference electrode is implanted between the positive and negative electrode plates of the lithium-ion battery cell, and at least one separator is used to isolate the reference electrode from the positive and negative electrode plates.

[0066] Furthermore, in practice, positive and negative electrode plates 10 are continuously spaced within the lithium-ion battery cell, and an original separator 9 is disposed between adjacent positive and negative electrode plates. The lithium iron phosphate reference electrode 7 prepared above is implanted into the cell. A short separator 8 covers the active coating side of the reference electrode with the electrode plate, and the original separator 9 covers the other side of the reference electrode with the electrode plate. Figure 2 As shown.

[0067] Step S2: After the implantation is completed, fix the position of the reference electrode and the adhesion of the electrode sheet, and encapsulate it with an aluminum-plastic film. At this time, place the aluminum foil area of ​​the lower section of the reference electrode and the copper wire in the heat-sealing and heat-pressing area (i.e., the heat-sealing area 6 at the junction of aluminum foil and copper wire) for heat sealing to further strengthen the connection between the two and complete the secondary reinforcement to avoid poor conductive contact.

[0068] Step S3: Since the copper wire used is thick and strong enough, there is no risk of it breaking easily when connected externally. On this basis, for the convenience of subsequent testing, a nickel strip is welded to one end of the copper wire extending out of the reference electrode. The high-temperature welding also makes the copper wire with an insulating layer conductive at the extended end.

[0069] Step S4: The packaged lithium-ion battery with reference electrode is subjected to baking, liquid injection, formation and other processes to finally obtain a three-electrode lithium-ion battery, namely the improved three-electrode soft-pack battery 5.

[0070] In this embodiment, the prepared reference electrode can be implanted into a dry cell or into a battery cell that has been cycle-stabilized. The following two examples further illustrate the fabricated three-electrode lithium-ion battery and verify the superior performance of the reference battery used for potential monitoring.

[0071] Example 1

[0072] The prepared reference electrode is implanted into the gap between the electrodes of the dry cell, and a cut separator is covered between the active surface of the reference electrode and the electrode. After implantation, the battery is packaged in the first stage. At this time, the aluminum foil area at the top of the reference electrode is connected to the copper wire in the heat-sealing area for secondary reinforcement. To facilitate subsequent testing, the protruding copper wire is welded to a nickel strip. The battery with the reference electrode is then baked, injected with electrolyte, and formed according to the normal process to obtain the final product.

[0073] The reference electrode is connected to an external multi-channel data acquisition unit via a copper wire to monitor the potential changes of the battery during battery cycling. For example... Figure 3The potential monitoring graph shown indicates that the reference electrode has been consistently monitored for potential, and the potential is consistent with the known battery state. Subsequent stable monitoring data for more than 200 cycles further demonstrate that the reference electrode prepared by this method not only has good feasibility but also excellent stability and long lifespan, which can facilitate subsequent failure analysis.

[0074] Example 2

[0075] The reference electrode prepared in this embodiment is implanted into a battery that has already been cycle-stabilized. The specific operation steps for implanting the reference electrode are basically the same as in Example 1 above. The difference is that the object implanted is not a dry cell, but a battery that has already been manufactured and cycle-stabilized, requiring disassembly and repackaging. In this example, a copper wire with a specification of 25 and an insulating layer is used. The bottom insulating layer is removed by soaking in strong acid. The bottom conductive area is placed in the center of the cell and covered with a cut separator. The two reference electrodes are placed in different layers of the cell to prevent overlap failure. After the copper wire extends, a nickel strip is welded to it to increase strength and facilitate testing. The copper wire reference electrode in the repackaged product is lithium plated. After completion, a multi-channel monitor is connected to the copper wire to monitor the potential changes of the battery during battery cycling.

[0076] like Figure 4 As shown, under the same battery environment and test conditions, the reference electrode prepared in this embodiment maintains stable potential monitoring throughout the process, while the copper wire lithium-plated reference electrode decays and fails at a faster rate. This is due to the rapid consumption of lithium, which further indicates that the reference electrode prepared by this method and the packaging method are greatly improved compared with the traditional reference electrode, and its performance is more stable and more operable.

[0077] The steps and methods involved in the above embodiment two correspond to those in embodiment one. For specific implementation details, please refer to the relevant description section of embodiment one.

[0078] The above description is only a preferred embodiment of the present invention. Although the specific implementation of the present invention has been described in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

Claims

1. A method for preparing a reference electrode, characterized in that, include: Disassemble the pre-conditioned pouch cell in a vacuum glove box environment to obtain the positive electrode sheet; The active coating on both sides of the positive electrode is wiped off, leaving only a portion of the active coating on one side; The positive electrode sheet after the coating is wiped off is uniformly slit to obtain an initial reference electrode with an upper section of single-sided active coating area and a lower section of inactive conductive aluminum foil area; Take a copper wire of a set length and remove part of the polyurethane coating from the surface of the copper wire; One end of the copper wire with the surface coating removed is placed in the aluminum foil area of ​​the initial reference electrode, and the copper wire is wrapped and fixed by winding and folding the aluminum foil area to prepare the reference electrode.

2. The method for preparing the reference electrode as described in claim 1, characterized in that, Pre-conditioned pouch cells, including: Fresh pouch batteries are charged and discharged in an ambient temperature chamber to adjust the battery's state of charge (SOC) to a preset value; the preset value is 50%.

3. The method for preparing the reference electrode as described in claim 1, characterized in that, The coating on the obtained positive electrode sheet was removed using N-methylpyrrolidone.

4. The method for preparing the reference electrode as described in claim 1, characterized in that, The length of the single-sided active coating area is 1~2.5cm and the width is 0.1~3mm; the length of the non-active conductive aluminum foil area is 1~2cm and the width is 2~6mm.

5. The method for preparing the reference electrode as described in claim 1, characterized in that, Take a copper wire with a polyurethane coating of a specified specification and length, immerse one end of the copper wire in a concentrated sulfuric acid environment for 30-40 minutes. After soaking and removing the copper wires, the exposed copper wires were ultrasonically cleaned with deionized water and ethanol respectively. After cleaning, they were dried in an oven at 80°C for later use.

6. The method for preparing the reference electrode as described in claim 1, characterized in that, After wrapping and fixing the copper wire in the folded aluminum foil area, use insulating glue to initially fix the shape of the wrapping.

7. A method for preparing a three-electrode lithium-ion battery, characterized in that, include: The reference electrode prepared by the method of any one of claims 1-6 is implanted between the positive and negative electrode plates of the lithium-ion battery cell, and at least one separator is used to isolate the reference electrode from the positive and negative electrode plates. After the reference electrode is implanted into the battery cell, it is packaged. During the packaging process, the aluminum foil area of ​​the lower section of the reference electrode is placed in the heat-sealing area to heat-seal the copper wire, thus completing the secondary reinforcement. The encapsulated lithium-ion battery with a reference electrode is baked, injected with electrolyte, and formed to finally prepare a three-electrode lithium-ion battery.

8. The method for preparing a three-electrode lithium-ion battery as described in claim 7, characterized in that, The lithium-ion battery cell has positive and negative electrode plates continuously spaced apart, and an original separator is provided between adjacent positive and negative electrode plates. A reference electrode is implanted into the battery cell. A short diaphragm is placed between the active coating side of the reference electrode and the electrode sheet, while the original diaphragm is placed between the other side of the reference electrode and the electrode sheet.

9. The method for preparing a three-electrode lithium-ion battery as described in claim 7, characterized in that, A nickel strip is welded to one end of the copper wire extending from the reference electrode.

Images