Reference electrode, long-life three-electrode battery preparation and battery capacity recovery method

Abstract

This invention belongs to the field of rechargeable battery technology, specifically relating to a reference electrode, a method for preparing a long-life three-electrode battery, and a method for restoring battery capacity. This invention proposes a method for preparing, processing, and applying a sheet-like reference electrode, enabling large-scale mass production. It allows for stable monitoring of the positive and negative electrode potentials within the battery during long-term service, improves battery cycle life, and allows for the replenishment of additional active lithium / sodium to restore battery capacity after aging is determined. Therefore, this method can directly obtain internal battery information and improve battery cycle performance, providing a solution for the development and commercial application of novel battery management systems and cells.

Description

Technical Field

[0001] This invention belongs to the field of rechargeable battery technology, specifically relating to a method for preparing a reference electrode, a long-life three-electrode battery, and restoring battery capacity. Background Technology

[0002] Developing clean energy, especially rechargeable batteries, is a major research focus in the current new energy industry. Lithium-ion batteries, with their advantages of high energy density, high coulombic efficiency, and long cycle life, are widely used in energy storage, electric vehicles, consumer electronics, and transportation. Currently, with the increase in battery capacity and the expansion of application scenarios, traditional battery management systems are unable to meet the needs of efficient information acquisition and management at the individual cell level, and have shortcomings in improving battery safety and reliability.

[0003] In existing technologies, most battery three-electrode designs involve embedding a reference electrode between the positive and negative electrodes. These designs fall into two categories: embedding during initial battery manufacturing and modification during service. The main research focus for these batteries is on monitoring the positive and negative electrode potentials and impedance analysis. First, embedding a reference electrode during initial battery manufacturing requires using electrochemically stable materials as the active material, such as LTO and LFP. These materials are typically coated onto copper wire or porous metal mesh, and after battery formation, the positive and negative electrodes are activated by forming current loops with the reference electrode. This process is cumbersome and not conducive to large-scale mass production. Second, modifying batteries during service often requires operation in a glove box to prevent oxidation of the electrodes and electrolyte. This modification process also faces challenges such as electrode damage, uneven electrode surfaces caused by the additional separator used for embedding the reference electrode, and difficulties in large-scale production. Finally, the above-mentioned solutions all focus on using a reference electrode to improve the monitoring of the positive and negative electrode potentials inside the battery and the evaluation of battery parameters such as SOC and SOH obtained from subsequent data processing. Furthermore, the reference electrode has a low active material loading, making it difficult to operate stably for extended periods. More importantly, current technical solutions do not yet include a method for fabricating a reference electrode during battery manufacturing that is stable in air and simultaneously capable of monitoring the positive and negative electrode potentials inside the battery during cycling and restoring the capacity of aged batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a reference electrode, a long-life three-electrode battery, and restoring battery capacity, so as to overcome the problems of low loading of active material in the reference electrode, unstable potential, difficulty in implantation, capacity-induced damage to battery performance, and inability to improve battery cycle performance and restore capacity in the existing technical solutions.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a reference electrode, comprising a current collector and an active layer and an antioxidant layer sequentially wrapped around the surface of the current collector;

[0007] The active layer material includes active materials used in lithium-ion batteries or sodium-ion batteries; the content of the active layer material in the reference electrode is 0.05–0.08 g / cm³. 2 ;

[0008] The material of the antioxidant layer includes a solid electrolyte.

[0009] Preferably, the thickness of the active layer is ≥6μm; the thickness of the antioxidant layer is 2-3μm.

[0010] Preferably, one end of the reference electrode further includes a reference electrode tab; the reference electrode tab is a nickel tab with a copper-plated surface.

[0011] The present invention also provides a long-life three-electrode battery, comprising a cell body, an electrolyte and a battery casing;

[0012] The battery cell body includes a positive electrode, a negative electrode, a separator, and a reference electrode;

[0013] The reference electrode is the reference electrode described in the above technical solution.

[0014] Preferably, the cell body includes a laminated cell body or a wound cell body;

[0015] The stacked cell body includes a positive electrode, a reference electrode, and a negative electrode stacked sequentially, with a separator provided between the reference electrode and the positive electrode, and between the reference electrode and the negative electrode;

[0016] The wound cell body includes a positive electrode, a reference electrode, and a negative electrode that are stacked and wound in sequence, and a separator is provided between the reference electrode and the positive electrode, and between the reference electrode and the negative electrode.

[0017] Preferably, one end of the positive electrode further includes a positive electrode tab, which is an aluminum electrode tab;

[0018] One end of the negative electrode also includes a negative electrode tab, which is a nickel electrode tab;

[0019] The positive and negative electrode tabs are located on the same side of the battery cell body;

[0020] The reference electrode tab is located on the same side or opposite side of the positive electrode tab.

[0021] Preferably, the long-life three-electrode battery includes a pouch battery or a prismatic battery; the pouch battery casing is an aluminum-plastic film casing.

[0022] This invention also provides a method for preparing the long-life three-electrode battery described above, comprising the following steps:

[0023] Provide battery cell body;

[0024] After the cell body is placed in the battery case for liquid injection and encapsulation, the long-life three-electrode battery is obtained after formation and sorting.

[0025] The present invention also provides a method for restoring the capacity of a battery, comprising the following steps:

[0026] The battery is the long-life three-electrode battery described in the above technical solution or the long-life three-electrode battery prepared by the preparation method described in the above technical solution;

[0027] The battery is subjected to charge-discharge cycles. When the cycle capacity of a single battery cell is lower than 80% of its initial capacity, a current loop is formed by sequentially connecting the reference electrode with the negative or positive electrode. A pulse current is applied to the battery to replenish lithium or sodium to the negative or positive electrode, thereby restoring the battery capacity.

[0028] Preferably, the pulse current includes a matrix pulse current, the program of which is: charging at 3μA for 10 minutes, resting for 10 minutes, then charging again at 3μA for 10 minutes, resting for 10 minutes, then charging at 5μA for 10 minutes, resting for 5 minutes, then charging at 4μA for 10 minutes, and resting for 10 minutes, then charging at 2μA for 20 minutes.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] I. This invention innovatively improves the design, processing, and use of reference electrodes for batteries, solving current problems such as difficulties in applying reference electrodes in batteries, damage to battery performance after implantation, and inability to scale up applications. Through designs such as high-load active material coating, planar reference electrode processing, anti-oxidation coating preparation, integrated electrode implantation, and sealing, it ensures that the reference electrode can be mass-produced and assembled in existing production lines, and can efficiently and stably monitor the positive and negative electrode potentials of the battery.

[0031] Second, by designing a sheet-like reference electrode and embedding it within the battery cell, combined with a double-sided coating of active materials, a good ion transport pathway can be maintained between the reference electrode and other electrodes in the battery, thus improving the monitoring reliability of the reference electrode. The relatively large area and high active material loading ensure long-term, stable monitoring of the battery's positive and negative electrode potentials and calculation of the battery's state of charge and aging status during service.

[0032] Third, this invention innovatively replenishes the active lithium / sodium ions in the battery after aging by utilizing the active material in the reference electrode, thereby restoring battery capacity and repairing the battery. This integrates secondary capacity recovery and intelligent battery monitoring functions, realizing the multi-functional application of the reference electrode and enhancing its application value. Furthermore, this invention innovatively designs a pulse excitation method and application example for repairing battery capacity damage through the reference electrode. This method is universal and can be modified and improved according to actual application scenarios. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the reference electrode obtained in Example 1;

[0034] Figure 2 This is a schematic diagram of the battery cell obtained by assembling the reference electrode in a stacked structure in Example 2;

[0035] Figure 3 This is a schematic diagram illustrating the working principle of a reference electrode in a lithium-ion battery.

[0036] Figure 4 This is a schematic diagram of the structure of the reference electrode of the present invention in a high-capacity prismatic battery;

[0037] Figure 5 This is a schematic diagram of the sealing process of the reference electrode of the present invention in a high-capacity prismatic battery.

[0038] Figure 6 This is a schematic diagram of the sealing process of the soft-pack battery obtained in Example 2;

[0039] Figure 7 This is a schematic diagram of monitoring the positive and negative electrode potentials in a graphite negative electrode lithium-ion battery before sorting using a reference electrode in Example 2.

[0040] Figure 8 A schematic diagram of the positive and negative electrode potentials of a lithium-ion battery during long-cycle monitoring, serving as a reference electrode.

[0041] Figure 9 A schematic diagram of the positive and negative electrode potentials of a lithium-ion battery during cyclic testing under different rate conditions, serving as a reference electrode.

[0042] Figure 10 A schematic diagram showing the application of a pulsed current to the current loop formed by the reference electrode and the positive / negative electrodes in the battery in Example 3 to restore battery capacity;

[0043] Figure 11 This is a schematic diagram of restoring battery capacity loss by releasing active material through a reference electrode in Example 3. Detailed Implementation

[0044] This invention provides a reference electrode, comprising a current collector and an active layer and an antioxidant layer sequentially wrapped around the surface of the current collector;

[0045] The active layer material includes active materials used in lithium-ion batteries or sodium-ion batteries; the content of the active layer material in the reference electrode is 0.05–0.08 g / cm³. 2 ;

[0046] The material of the antioxidant layer includes a solid electrolyte.

[0047] In this invention, the material of the current collector preferably includes one or more of copper, aluminum, nickel and gold; the form of the current collector preferably includes a planar metal foil or a porous metal foil sheet.

[0048] In this invention, the active material for lithium-ion batteries preferably includes one or more of pure lithium, lithium alloys, lithium iron phosphate, and lithium titanate; the active material for sodium-ion batteries preferably includes one or more of pure sodium and sodium alloys. In this invention, the thickness of the active layer is preferably ≥6 μm. In this invention, the porosity of the active layer is preferably ≤5%.

[0049] In this invention, the solid electrolyte preferably comprises a hybrid solid electrolyte or an oxide solid electrolyte. The hybrid solid electrolyte is preferably obtained by UV-initiated in-situ polymerization of a eutectic system composed of a methacrylate-terminated organic / inorganic hybrid polyurethane precursor (m-PPS) and LiTFSI / NMAc. In this invention, the oxide solid electrolyte preferably comprises one or more of lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum zirconium oxide (LLZO), and lithium aluminum titanium phosphate (LATP). In this invention, the thickness of the antioxidant layer is preferably 2–3 μm.

[0050] In this invention, one end of the reference electrode preferably includes a reference electrode tab; the reference electrode tab is preferably a nickel tab with a copper-plated surface.

[0051] In this invention, the method for preparing the reference electrode preferably includes the following steps:

[0052] An active layer material is pressed onto both sides of the current collector and then rolled to obtain the active layer.

[0053] An antioxidant layer is prepared on the surface of the active layer.

[0054] In this invention, the pressing temperature is preferably 150°C, the pressure is preferably 0.5 MPa, and the holding time is preferably 3 seconds. In this invention, the pressing is preferably carried out under an inert atmosphere. This invention does not impose any special limitations on the rolling process; any desired thickness and porosity are acceptable.

[0055] In this invention, when the material of the antioxidant layer is a hybrid solid electrolyte, the preferred method for preparing the antioxidant layer is as follows: a methacrylate-terminated organic / inorganic hybrid polyurethane precursor (m-PPS) is mixed with a eutectic system composed of LiTFSI / NMAc and then in situ polymerized on the surface of the active layer by UV initiation (for specific steps, see YXJiang, YDSong, X.Chen, HJWang, LJDeng, G.Yang, In situ formed self-healable quasi-solid hybrid electrolyte network coupled with eutectic mixture towards ultra-long cycle life lithium metal batteries, Energy Storage Materials, 2022, 52, 514-523).

[0056] In this invention, when the material of the antioxidant layer is an oxide solid electrolyte, the preparation method of the antioxidant layer preferably includes: mixing the oxide solid electrolyte, organic solvent, binder and lithium salt to obtain a slurry; coating the slurry onto the surface of the active layer, and obtaining the antioxidant layer after solvent evaporation.

[0057] In this invention, the lithium salt preferably includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, and lithium hexafluoroarsenate; the binder preferably includes one or more of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, and polyvinylidene chloride; and the organic solvent preferably includes succinic anionyl nitrile. In this invention, the mass ratio of the oxide solid electrolyte, organic solvent, binder, and lithium salt is preferably 45–60:4–24:30–40:0.4–3. This invention does not impose any special limitations on the coating and solvent evaporation processes; any process well known to those skilled in the art can be used.

[0058] In this invention, after the reference electrode is prepared, it is preferable to further perform charge-discharge testing and voltage monitoring on the reference electrode to ensure the accuracy of the reference electrode's potential. This invention does not impose any particular limitations on the process of charge-discharge testing and voltage monitoring; any process well-known to those skilled in the art can be used.

[0059] The present invention also provides a long-life three-electrode battery, comprising a cell body, an electrolyte and a battery casing;

[0060] The battery cell body includes a positive electrode, a negative electrode, a separator, and a reference electrode;

[0061] The reference electrode is the reference electrode described in the above technical solution.

[0062] In this invention, the diaphragm preferably includes a substrate and a ceramic particle layer covering the surface of the substrate; the substrate preferably includes a single-layer membrane or a multilayer composite membrane; the single-layer membrane includes a PP single-layer membrane or a PE single-layer membrane, and the multilayer composite membrane is preferably a multilayer composite membrane composed of a PP single-layer membrane and / or a PE single-layer membrane; the material of the ceramic particle layer preferably includes alumina; the thickness of the ceramic particle layer is preferably 0.7 μm.

[0063] In this invention, the cell body preferably comprises a laminated cell body or a wound cell body. In this invention, the laminated cell body preferably comprises a positive electrode, a reference electrode, and a negative electrode stacked sequentially, and a separator is preferably provided between the reference electrode and the positive electrode, and between the reference electrode and the negative electrode. In this invention, the size of the reference electrode in the laminated cell body is preferably not smaller than the size of the negative electrode.

[0064] In this invention, the wound cell body preferably includes a positive electrode, a reference electrode, and a negative electrode that are sequentially stacked and wound. A separator is preferably provided between the reference electrode and the positive electrode, and between the reference electrode and the negative electrode. In this invention, the size of the reference electrode in the wound cell body is preferably consistent with the size of the positive or negative electrode.

[0065] In this invention, one end of the positive electrode preferably includes a positive electrode tab, which is preferably an aluminum electrode tab; one end of the negative electrode preferably includes a negative electrode tab, which is preferably a nickel electrode tab; the positive electrode tab and the negative electrode tab are preferably located on the same side of the cell body; the reference electrode tab is preferably located on the same side or opposite side of the positive electrode tab.

[0066] In this invention, the long-life three-electrode battery preferably includes a pouch cell or a prismatic cell; the battery casing of the pouch cell is preferably an aluminum-plastic film casing. This invention does not impose any particular limitation on the type of battery casing for the prismatic cell; any casing well-known to those skilled in the art can be used.

[0067] This invention also provides a method for preparing the long-life three-electrode battery described above, comprising the following steps:

[0068] Provide battery cell body;

[0069] After the cell body is placed in the battery case for liquid injection and encapsulation, the long-life three-electrode battery is obtained after formation and sorting.

[0070] The present invention does not impose any special limitation on the preparation method of the battery cell body; any method known to those skilled in the art can be used.

[0071] This invention does not impose any special limitations on the type or amount of electrolyte used for electrolyte injection; adjustments can be made appropriately based on the type of battery required. The packaging process is also not particularly limited; any process well-known to those skilled in the art can be used.

[0072] This invention does not impose any particular limitation on the formation and sorting processes; any process well-known to those skilled in the art can be used. In this invention, the formation process preferably includes continuous monitoring of the voltage signals between the positive electrode and the reference electrode, as well as the voltage signals between the negative electrode and the reference electrode. In this invention, monitoring the voltage signals during the formation process allows for monitoring battery performance, which can then be used as a basis for sorting.

[0073] In a specific embodiment of the present invention, when the long-life three-electrode battery is a pouch cell, the preparation preferably includes:

[0074] The battery cell body is installed in an aluminum-plastic film shell, and the tab side and the bottom of the battery cell body are sealed with a heat sealer. The length of the bottom aluminum-plastic film seal in the soft-pack battery is preferably not less than 6 mm. After drying and cooling, electrolyte is injected under negative pressure. During the drying and electrolyte injection process, attention is paid to the electrical insulation treatment and protection of the electrodes. Then, a first vacuuming and sealing is performed. After the obtained battery is formed and sorted, a second vacuuming and sealing is performed to obtain the soft-pack battery.

[0075] In this invention, when the long-life three-electrode battery is a prismatic battery, Figure 4 This is a schematic diagram of the structure of the reference electrode of the present invention in a high-capacity prismatic battery; Figure 5 This is a schematic diagram of the sealing process of the reference electrode in a high-capacity prismatic battery according to the present invention.

[0076] The present invention also provides a method for restoring the capacity of a battery, comprising the following steps:

[0077] The battery is the long-life three-electrode battery described in the above technical solution or the long-life three-electrode battery prepared by the preparation method described in the above technical solution;

[0078] The battery is subjected to charge-discharge cycles. When the cycle capacity of a single battery cell is lower than 80% of its initial capacity, a current loop is formed by sequentially connecting the reference electrode with the negative or positive electrode. A pulse current is applied to the battery to replenish lithium or sodium to the negative or positive electrode, thereby restoring the battery capacity.

[0079] In this invention, the charge / discharge cycle preferably includes continuous monitoring of the voltage signals of the positive electrode relative to the reference electrode and the negative electrode relative to the reference electrode. In this invention, the battery's state of charge is determined and charge / discharge management is performed by monitoring the voltage signal of the negative electrode relative to the reference electrode, and the battery's aging state is determined by the differential voltage method; simultaneously, the potential fluctuations of the battery's positive / negative electrodes relative to the reference electrode can serve as a reference indicator for safety management. This invention first monitors and analyzes the potentials of the positive and negative electrodes relative to the reference electrode in the battery, and then assesses and manages the battery's health status based on the negative electrode potential during charge / discharge, the relaxation process of the positive and negative electrode potentials during battery resting, and the peak values ​​of the curves obtained through incremental capacity or differential selection calculations during charge / discharge. The working principle diagram of the reference electrode in a lithium-ion battery in this invention is shown below. Figure 3 As shown.

[0080] In this invention, it is preferable to stop charging immediately when the potential of the negative electrode approaches 0V.

[0081] In this invention, the cycle capacity of the battery cell is preferably detected by the ampere-hour integration method. This invention does not impose any special limitations on the ampere-hour integration method detection process; any method well-known to those skilled in the art can be used.

[0082] In this invention, the pulse current preferably includes a matrix pulse current, and the preferred procedure of the matrix pulse current is: charging at 3μA for 10 minutes, resting for 10 minutes, then charging again at 3μA for 10 minutes, resting for 10 minutes, then charging at 5μA for 10 minutes, resting for 5 minutes, then charging at 4μA for 10 minutes, and resting for 10 minutes, then charging at 2μA for 20 minutes.

[0083] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0084] This invention pioneers a method for the preparation, processing, and application of a sheet-like reference electrode, enabling large-scale mass production. It allows for stable monitoring of the positive and negative electrode potentials within the battery during long-term service, improves battery cycle life, and allows for the replenishment of additional active lithium / sodium to restore battery capacity after aging is identified. Therefore, this method can directly acquire internal battery information and improve battery cycle performance, providing a solution for the development and commercial application of novel battery management systems and cells.

[0085] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0086] Example 1

[0087] For the current collector required for the reference electrode, a copper sheet current collector of appropriate size is obtained by laser cutting;

[0088] Lithium-rich alloy particles (containing more than 95% lithium by mass) were spread evenly on the current collector. Then, under an inert gas protective atmosphere at 150°C, the active material was compacted and bonded to the current collector using a press at a pressure of 0.5 MPa for 3 seconds. The above operation was repeated on the back side of the current collector. Then, the material was rolled in a roller press to obtain an active layer with a thickness of 6 μm and a porosity of 5%.

[0089] A eutectic layer with a thickness of 2 μm was obtained by spin-coating a eutectic mixture of an inorganic hybrid polyurethane precursor (m-PPS) and LiTFSI / NMAc onto both sides of the active layer using a coating machine, followed by UV curing (for details on the composition and curing conditions of the eutectic mixture, see YXJiang, YDSong, X.Chen, HJWang, LJDeng, G.Yang, In situ formed self-healable quasi-solid hybrid electrolyte network coupled with eutectic mixture towards ultra-long cycle life lithium metal batteries, Energy Storage Materials, 2022, 52, 514-523). This yielded the reference electrode, in which the lithium-rich alloy content was 0.07 g / cm³. 2 .

[0090] The schematic diagram of the reference electrode is shown below. Figure 1 As shown.

[0091] Example 2

[0092] A three-electrode battery was prepared using the reference electrode obtained in Example 1;

[0093] The three-electrode battery in this embodiment is a stacked soft-pack battery; a 1.2Ah capacity battery is prepared by using an NCM523 positive electrode combined with a graphite negative electrode through a stacking process.

[0094] The battery capacity is determined based on requirements, which in turn determines the number of positive and negative electrode plates and their areal capacity. For example, a 1.2Ah battery requires 11 positive electrode plates and 12 negative electrode plates. Based on the cell dimensions in the pouch cell and subsequent battery management requirements, the two-dimensional dimensions of the reference electrode are determined to be 45×58mm. By rationally designing the functional requirements of the internal reference electrode and considering the battery's manufacturing process, the areal capacity, assembly process, and stacking sequence of the reference electrode are determined.

[0095] A Z-shaped lamination process is employed (i.e., the reference electrode tab is located opposite the positive electrode tab), and the reference electrode is stacked with other electrodes. It is particularly important that the two electrodes adjacent to the reference electrode are coated on only one side and are simultaneously either positive or negative electrodes; the electrodes in other positions maintain a cross-lamination arrangement of positive and negative electrodes. After the cell lamination is completed, it is secured with adhesive tape. The assembled cell is shown below. Figure 2 As shown.

[0096] The reference electrode's tab lead is led out from below the cell and soldered to it with a copper-plated nickel tab. The aluminum tab and nickel tab are soldered to the positive and negative electrodes respectively to obtain the laminated cell body;

[0097] The battery cell is then installed into an aluminum-plastic film casing, and the tab side and the area below the tab are sealed using a heat sealer. The reference electrode tab is also sealed and connected to an external device. To ensure battery sealing performance, the length of the bottom aluminum-plastic film seal in the soft-pack battery is no less than 6 mm.

[0098] After drying in a high-temperature vacuum chamber and cooling, an electrolyte matching the cell capacity (1M LiPF6 in a mixed solvent of EC:DMC:DEC, with a volume ratio of EC:DMC:DEC of 1:1:1) is injected into the soft-pack battery packaging bag under negative pressure. During the drying and electrolyte injection process, pay attention to the electrical insulation treatment and protection of the reference electrode and the positive and negative electrodes.

[0099] After the battery is vacuumed and sealed for the first time, it is formed and sorted, and then vacuumed and sealed for the second time to obtain a three-electrode battery. Figure 6 This is a schematic diagram of the sealing process of the soft-pack battery obtained in Example 2; the voltage signals during the entire formation process are monitored, including the voltage signals between the positive electrode and the reference electrode and the voltage signals between the negative electrode and the reference electrode, wherein the potential information obtained before sorting is as follows: Figure 7 As shown.

[0100] Example 3

[0101] Battery management and capacity recovery were performed on the three-electrode battery obtained in Example 2;

[0102] The three-electrode battery obtained in Example 2 was subjected to charge-discharge cycles, and the voltage signals during the entire charge-discharge cycle process were monitored, including the voltage signals of the positive electrode to the reference electrode and the voltage signals of the negative electrode to the reference electrode. Figure 8 This diagram illustrates the positive and negative electrode potentials of a lithium-ion battery during long-term cycling, serving as a reference electrode. The top diagram shows the positive and negative electrode potential information, while the bottom diagram shows the battery's cycle capacity. Figure 9 This diagram illustrates the positive and negative electrode potentials of a lithium-ion battery during cycle testing at different rates, serving as a reference electrode. The top diagram shows the positive and negative electrode potentials at different rates, while the bottom diagram shows the battery cycle capacity.

[0103] The battery's state of charge (SOC) is determined and charge / discharge management is implemented by monitoring the voltage signal between the negative electrode and the reference electrode. The battery's aging status is determined using the differential voltage method. Simultaneously, the potential fluctuations between the positive and negative electrodes and the reference electrode serve as a reference indicator for safety management. Charging should be stopped immediately when the potential of the graphite negative electrode approaches 0V.

[0104] The cycle capacity of the battery is detected using the ampere-hour integration method. When the cycle capacity of a single battery cell falls below 80% of its initial capacity, a current loop is formed between the reference electrode and the negative electrode. By applying external excitation, active lithium ions in the reference electrode are released and transferred to the negative electrode to compensate for the capacity reduction caused by the loss of active lithium and the growth of the SEI film on the negative electrode during battery cycle aging. In this implementation case, a matrix pulse current excitation scheme is used to control the excitation current at the microampere level. The specific steps for applying the excitation are as follows: Figure 10 As shown. After lithium replenishment at the negative electrode, the reference electrode and the positive electrode are connected in a circuit, and the above steps are repeated to replenish lithium at the positive electrode. By designing external circuits and excitation steps, active lithium ions / sodium ions are released into the electrolyte and the active materials of the positive and negative electrodes to participate in the charge-discharge cycle of the battery, thereby achieving battery capacity recovery.

[0105] After current excitation, the batteries undergoing capacity recovery are subjected to electrochemical testing, and their capacity and impedance characteristics are recalibrated. The batteries are then tested, sorted, and put back into service, with their state of charge, aging state, and safety status monitored during cycle use. Figure 11 As shown, in this implementation example, the pouch cell's capacity decayed to 80% after 800 cycles at 1C. At this point, the cycle test was stopped, and active lithium was released using the reference electrode to replenish the battery's lithium. After replenishment with active lithium from the reference electrode, the battery recovered 55mAh of capacity and operated stably for the subsequent 400 cycles without significant capacity loss.

[0106] In summary, the solution of this invention has been successfully applied to rechargeable batteries. It not only enables the fabrication of cells with internally implanted reference electrodes using conventional methods, but also allows for stable monitoring of the positive and negative electrode potentials during battery formation and long-cycle operation. When battery capacity decays, external circuitry stimulates the reference electrode and releases active lithium, effectively replenishing the active lithium lost during cycling and restoring battery capacity. After capacity restoration, the battery operated stably for 400 cycles without significant capacity loss.

[0107] This invention effectively simplifies the implantation process and reduces the cost of reference electrodes in batteries, integrating multiple functions such as potential monitoring and capacity restoration within the reference electrode. In practical applications, the reference electrode proposed in this invention accurately monitors the positive and negative electrode potentials of the battery during operation and significantly reduces the cost of using the reference electrode. Therefore, the technical solution proposed in this invention can be applied to lithium-ion batteries and sodium-ion batteries, and is applicable to both pouch batteries and prismatic batteries. The designed capacity restoration method can effectively improve the cycle life and economic efficiency of the battery. The above solution ensures the large-scale fabrication of the reference electrode, achieves stable monitoring of the positive and negative electrode potentials during battery operation, and can restore battery capacity after aging.

[0108] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for restoring the capacity of a battery, characterized in that, The steps are as follows: The battery is a long-life three-electrode battery; the long-life three-electrode battery includes a cell body, an electrolyte, and a battery casing; the cell body includes a positive electrode, a negative electrode, a separator, and a reference electrode; the reference electrode includes a current collector and an active layer and an antioxidant layer sequentially wrapped around the surface of the current collector; the active layer is made of lithium-rich metal; the content of the active layer material in the reference electrode is 0.07 g / cm³. 2 The material of the antioxidant layer is a hybrid solid electrolyte; the hybrid solid electrolyte is obtained by UV-initiated in-situ polymerization of a methacrylate-terminated organic / inorganic hybrid polyurethane precursor and a LiTFSI / NMAc eutectic system; the thickness of the active layer is 6 μm; the thickness of the antioxidant layer is 2 μm. The positive electrode is the NCM523 positive electrode, and the negative electrode is the graphite negative electrode; The three-electrode battery is subjected to charge-discharge cycles, and the voltage signals during the entire charge-discharge cycle process are monitored, including the voltage signals of the positive electrode to the reference electrode and the voltage signals of the negative electrode to the reference electrode. The battery's state of charge is determined by monitoring the voltage signal between the negative electrode and the reference electrode, and charging / discharging is managed accordingly. The battery's aging status is determined by using the differential voltage method. When the potential of the graphite negative electrode approaches 0V, charging should be stopped immediately. The cycle capacity of the battery is detected by the ampere-hour integration method. When the cycle capacity of a single battery cell is lower than 80% of the initial capacity, the reference electrode is sequentially connected to the negative or positive electrode to form a current loop. A pulse current is applied to the battery to replenish lithium to the negative or positive electrode respectively, thereby restoring the battery capacity. The pulse current includes a matrix pulse current, and the program of the matrix pulse current is as follows: charge at 3μA for 10 minutes, rest for 10 minutes, charge again at 3μA for 10 minutes, rest for 10 minutes, charge at 5μA for 10 minutes, rest for 5 minutes, charge at 4μA for 10 minutes, and rest for 10 minutes, then charge at 2μA for 20 minutes.

2. The capacity recovery method according to claim 1, characterized in that, One end of the reference electrode also includes a reference electrode tab; the reference electrode tab is a nickel tab with copper plating on its surface.

3. The capacity recovery method according to claim 1, characterized in that, The battery cell body includes a laminated battery cell body or a wound battery cell body; The stacked cell body includes a positive electrode, a reference electrode, and a negative electrode stacked sequentially, with a separator provided between the reference electrode and the positive electrode, and between the reference electrode and the negative electrode; The wound cell body includes a positive electrode, a reference electrode, and a negative electrode that are stacked and wound in sequence, and a separator is provided between the reference electrode and the positive electrode, and between the reference electrode and the negative electrode.

4. The capacity recovery method according to claim 1, characterized in that, One end of the positive electrode also includes a positive electrode tab, which is an aluminum electrode tab; One end of the negative electrode also includes a negative electrode tab, which is a nickel electrode tab; The positive and negative electrode tabs are located on the same side of the battery cell body; The reference electrode tab is located on the same side or opposite side of the positive electrode tab.

5. The capacity recovery method according to claim 1, characterized in that, The long-life three-electrode battery includes a pouch battery or a prismatic battery; the pouch battery casing is an aluminum-plastic film casing.

6. The capacity recovery method according to claim 1, characterized in that, The method for preparing the long-life three-electrode battery includes the following steps: Provide battery cell body; After the cell body is placed in the battery case for liquid injection and encapsulation, the long-life three-electrode battery is obtained after formation and sorting.

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