Method for recovering failure positive pole capacity of lithium ion battery by utilizing controllable external magnetic field
By applying a controllable external magnetic field during the charging and discharging phase of a lithium-ion battery, the movement of electrolyte ions is driven, polarization is eliminated, and the problem of battery capacity decay in existing technologies is solved, achieving in-situ recovery of battery capacity and extension of battery life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-03-24
AI Technical Summary
Existing technologies cannot restore battery capacity in situ, reversibly, and with low loss throughout the entire life cycle of lithium-ion batteries. Furthermore, existing processes are complex and costly, making them difficult to implement after packaging.
By applying a controllable external magnetic field during the charging and discharging phases of a lithium-ion battery, the movement of electrolyte ions is driven by the magnetic field, eliminating concentration polarization, electrochemical polarization, and ohmic polarization, thereby restoring battery capacity.
Without disassembling the battery structure, the battery capacity can be restored in situ. The process is simple and inexpensive, applicable to various types of lithium-ion batteries, and improves the reversible capacity and cycle life of the battery.
Smart Images
Figure CN121726565A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium ion batteries, in particular to a method for recovering the capacity of a failed positive electrode of a lithium ion battery by using a controllable external magnetic field. BACKGROUND
[0002] Lithium ion batteries have high energy density, long cycle life, green environmental protection and other characteristics, and have been widely used in electronic products, electric vehicles and other fields. However, in the cycle process, the ion / electron transmission speed in the internal chemical reaction of the lithium battery cannot keep up with the demand of the electrochemical reaction, which will cause the generation of polarization. The diffusion of lithium ions inside the positive electrode particles is blocked to produce concentration polarization, and the charge transfer is slow when passing through the solid-liquid interface to form electrochemical polarization, and the overall resistance of the electrolyte and the electrode brings Ohmic polarization. The superposition of the three types of polarization makes the battery voltage lag, the capacity decay, the rate performance decrease and brings safety risks. The existing technology can inhibit the polarization of the battery to a certain extent by doping, coating or electrolyte modification strategy of the lithium ion battery, but these processes are relatively complex, high cost, and difficult to implement after the battery is packaged.
[0003] Therefore, there is an urgent need for a depolarization method that can be in situ, reversible and low loss in the whole life cycle of the lithium ion battery to recover the capacity of the lithium ion battery that has already decayed. SUMMARY
[0004] In view of the fact that the existing technology cannot recover the capacity of the lithium ion battery in situ, reversibly and with low loss in the whole life cycle, the present application proposes a method for recovering the capacity of the battery by using a controllable external magnetic field, which can eliminate the concentration polarization, electrochemical polarization and Ohmic polarization synchronously or in stages during the charging and discharging stage of the battery, thereby recovering the reversible capacity and cycle life of the battery.
[0005] According to the embodiment of the present application, a method for recovering the capacity of a failed positive electrode of a lithium ion battery by using a controllable external magnetic field is provided, comprising: S1: obtaining a lithium ion battery to be processed, the lithium ion battery having experienced a cycle number, accumulated polarization degree and capacity decay; S2: evaluating the charging rate of the lithium ion battery according to the polarization degree and capacity decay degree of the lithium ion battery to be processed, for adjusting the magnetic field strength of the controllable external magnetic field; S3: preparing a controllable external magnetic field applied to the lithium ion battery, placing the lithium ion battery on a magnetic field platform without disassembling the lithium ion battery, making the magnetic field direction perpendicular to the battery electrode plane, and the uniformity ≥ 90%, setting the magnetic field strength range of the controllable external magnetic field as 300mT-800mT, and the single action time of the controllable external magnetic field as 1-10 charging and discharging cycles; S4: Apply a magnetic field to the lithium-ion battery on the magnetic field platform using the prepared controllable external magnetic field. During the application of the magnetic field, provide a temperature range of 20℃–45℃ and charge and discharge the battery at a rate of 0.01C–0.5C until the preset single action time of the controllable external magnetic field is completed, and a lithium-ion battery with restored battery capacity is obtained.
[0006] Optionally, in S3, the duration of a single application of the controllable external magnetic field is determined based on the magnetic field strength of the controllable external magnetic field:
[0007] in, This refers to the magnetic field strength, measured in mT. The duration of a single action is expressed in revolutions. This represents the function for rounding up.
[0008] Alternatively, the controllable external magnetic field may be provided in one of the following three ways: Method 1: A steady magnetic field of 0.01T–1T is generated by a permanent magnet array or electromagnet; Method 2: A pulsed magnetic field is generated by an electromagnet. The frequency range of the pulsed magnetic field is 10Hz–10kHz, the duty cycle range is 5%–100%, and the pulse rise / fall time range is less than or equal to 100µs. Method 3 is a combination of Method 1 and Method 2.
[0009] Optionally, during the charge and discharge cycles of S4, the charging cutoff voltage is set to be in the range of 4.2 V–5.0 V, and the discharging cutoff voltage is set to be in the range of 0 V–3.0 V.
[0010] Optionally, in S4, the stage in which a magnetic field is applied to the lithium-ion battery is the cycling stage after the lithium-ion battery has been formed.
[0011] Optionally, the lithium-ion battery to be processed is one of the following: lithium nickel cobalt manganese oxide battery, lithium-rich manganese-based battery, lithium iron phosphate battery, and lithium manganese iron phosphate battery.
[0012] Optionally, the lithium-ion battery to be processed is a cylindrical battery, a pouch battery, or a prismatic battery.
[0013] According to another embodiment of the present invention, a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field includes the following steps: Obtain a lithium-ion battery to be processed, wherein the lithium-ion battery is a battery that has undergone a certain number of cycles, accumulated a certain degree of polarization, and has capacity decay. Based on the polarization and capacity decay of the lithium-ion battery, the magnetic field strength is adjusted and the charging rate of the lithium-ion battery is evaluated. The controllable external magnetic field application device uses a permanent magnet array or electromagnet to generate a steady magnetic field of 0.01–1T, or uses an electromagnet to generate a pulsed magnetic field with a frequency of 10Hz–10kHz and a duty cycle of 5%–100%, with a pulse rise / fall time ≤100µs, and the magnetic field direction is perpendicular to the electrode plane and the uniformity is greater than 90%. The magnetic field strength is preferably 300mT–800mT, the operating temperature is 20℃–45℃, and the application stage is a specific stage after the lithium-ion battery is formed. The duration of a single application depends on the type and strength of the magnetic field.
[0014] This invention provides a method for restoring the capacity of a lithium-ion battery using a controllable external magnetic field. The method uses the Lorentz force generated by the magnetic field to drive the electrolyte to undergo eddy current motion, thereby weakening concentration polarization. The method also utilizes the magnetic field to induce Zeeman splitting of transition metal eg orbitals (Zeeman effect) to reduce charge transfer impedance. Simultaneously, the method refreshes the interface contact through magnetostrictive micro-vibrations induced by the magnetic field, thereby reducing contact resistance.
[0015] Compared with the prior art, the method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field provided by the present invention has at least the following beneficial effects.
[0016] 1) Without disassembling the battery, the capacity of the degraded battery can be restored in situ without damaging the battery structure.
[0017] 2) By providing a controllable external magnetic field, the movement of ions in the electrolyte of the battery is driven to form convection; this convection breaks the concentration gradient and reduces the concentration polarization on the electrode surface; and the charged ions are subjected to Lorentz force under the combined action of electric and magnetic fields, which changes the trajectory of ions in the electrolyte and promotes the uniform distribution of ions.
[0018] 3) During charging or discharging under an external magnetic field, the movement of ions in the electrolyte is driven in real time by the external magnetic field to reduce the concentration gradient, thereby eliminating concentration polarization, electrochemical polarization and ohmic polarization simultaneously or in stages, and thus restoring the reversible capacity of the battery.
[0019] 4) Addressing the limitation of existing magnetic field technologies that use weak magnetic fields to assist battery formation, which cannot repair the capacity of degraded batteries, this invention provides a significantly different improvement. Furthermore, the method of this invention is simple, low-cost, and can eliminate polarization in situ throughout the entire lifespan of various types of lithium-ion batteries, reducing overall polarization and increasing capacity. It is applicable to various types of batteries, including pouch, cylindrical, prismatic, and solid-state batteries, and has promising prospects for industrial applications. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the accompanying drawings. The accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a schematic diagram of a device for providing a controllable external magnetic field in a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field, according to an embodiment of the present invention.
[0022] Figure 2 The figures show the cycle performance curves before and after capacity recovery in Example 1.
[0023] Figure 3 The figures show the cycling performance curves before and after capacity gradient recovery in Example 1.
[0024] Figure 4 The figures show the cycling performance curves before and after capacity gradient recovery in Example 2. Detailed Implementation
[0025] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.
[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.
[0027] The following detailed description, with reference to the accompanying drawings, illustrates a method for restoring the capacity of a failed positive electrode in a lithium-ion battery using a controllable external magnetic field, according to an embodiment of the present invention. This method applies a controllable external magnetic field to the battery, simultaneously or in stages eliminating concentration polarization and electrochemical polarization. The key innovation of this invention lies in: driving the movement of ions in the electrolyte through the external magnetic field, forming convection to break the concentration gradient and reduce concentration polarization on the electrode surface. Simultaneously, charged ions, under the combined action of the electric and magnetic fields, experience Lorentz forces, altering their ionic trajectories and promoting uniform ion distribution. During charging or discharging, the ion movement is driven in real-time, reducing the concentration gradient and thus simultaneously eliminating concentration polarization. By charging and discharging under an external magnetic field, concentration polarization, electrochemical polarization, and ohmic polarization can be eliminated simultaneously or in stages, thereby restoring the reversible capacity of the battery. Compared to existing technologies, this invention allows for in-situ repair of degraded battery cells through a non-destructive process.
[0028] According to one embodiment of the present invention, a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field includes the following steps.
[0029] S1: Obtain the lithium-ion battery to be processed. The lithium-ion battery has undergone a certain number of cycles, accumulated a certain degree of polarization, and experienced capacity decay. Optionally, the positive electrode material of the lithium-ion battery can be selected from lithium nickel cobalt manganese oxide, lithium-rich manganese-based lithium, lithium iron phosphate, or lithium manganese iron phosphate. The lithium-ion battery can be in the form of a pouch, cylindrical, or prismatic battery.
[0030] S2: Based on the polarization and capacity decay of the lithium-ion battery to be processed, the charge rate of the lithium-ion battery is evaluated to adjust the strength of the applied controllable external magnetic field. This evaluation is used to predict the charge / discharge rate when a magnetic field is applied, based on the polarization and capacity decay of the lithium-ion battery.
[0031] S3: Prepare a controllable external magnetic field to be applied to the lithium-ion battery. Without disassembling the lithium-ion battery, place it on a magnetic field platform, ensuring the magnetic field direction is perpendicular or parallel to the battery electrode plane, and the uniformity of the battery electrode plane is greater than or equal to 90%. The controllable external magnetic field can be generated using one of the following three methods: Method 1: Generating a steady magnetic field of 0.01–1T using a permanent magnet array or electromagnet; Method 2: Generating a pulsed magnetic field using an electromagnet, with a frequency range of 10Hz–10kHz, a duty cycle range of 5%–100%, and a pulse rise / fall time range of less than or equal to 100µs; Method 3: A combination of Method 1 and Method 2. A stable parallel magnetic field can be generated using either Method 1 or Method 2. Figure 1 The diagram shows a schematic of a device that provides a controllable external magnetic field.
[0032] Optionally, the magnetic field strength of the controllable external magnetic field applied to the lithium-ion battery in this step is preferably 300mT–800mT, the operating temperature can be set to 20℃–45℃, and the application stage can be any stage after the lithium-ion battery has undergone cycle decay following formation. The duration of a single application of the controllable external magnetic field can be determined according to the type and strength of the magnetic field. The above parameter values can be selected according to different battery types.
[0033] Optionally, the duration of a single action can be 1–10 charge-discharge cycles, which can be obtained from the following formula:
[0034] in, This refers to the magnetic field strength, measured in mT. This is the duration of a single action, measured in revolutions. It needs to be rounded up during calculation, with a boundary of 1–10 revolutions. This represents the function for rounding up.
[0035] For example: For =300mT: ;but = 10 laps; for =500 mT: ;but = 5 laps; for =800 mT: ;but = 3 laps.
[0036] Prepare a controllable external magnetic field, including using a permanent magnet array or electromagnet to generate a steady magnetic field of 0.01–1T; or using an electromagnet to generate a pulsed magnetic field with a frequency range of 10Hz–10kHz, a duty cycle range of 5%–100%, and a rise / fall time range of less than or equal to 100μs; or a combination of the above two magnetic fields. Optionally, the magnetic field strength range of the controllable external magnetic field is set to 300–800mT, and the duration of a single action is determined based on the magnetic field strength using the above formula.
[0037] S4: Apply a magnetic field to the lithium-ion battery on the magnetic field platform using the prepared controllable external magnetic field. During the application of the magnetic field, maintain a temperature range of 20℃–45℃ and perform at least one charge-discharge cycle on the battery at a rate of 0.01C–0.5C. The charging cutoff voltage is 4.2–5.0V, and the discharging cutoff voltage is 0–3.0V, until the preset duration of a single application of the controllable external magnetic field is completed, thereby obtaining a lithium-ion battery with restored capacity. The stage of applying the magnetic field to the lithium-ion battery can be any cycle stage after the lithium-ion battery formation, and the duration of a single application can be 1–10 charge-discharge cycles, which can be calculated according to the formula in S3.
[0038] As shown in the figure, a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to another embodiment of the present invention includes the following steps.
[0039] S1: Provide a set of lithium-ion batteries that have undergone 50–1000 cycles, with a capacity decay of ≥10% and a total polarization of ≥50mV, and are selected from the following systems: lithium nickel cobalt manganese oxide, lithium-rich manganese-based, lithium iron phosphate, and lithium manganese iron phosphate. Optionally, the lithium-ion battery can be cylindrical, pouch, or prismatic. For example, the lithium-ion battery is a pouch battery.
[0040] S2: Place the lithium-ion battery on a controllable magnetic field platform, setting the temperature to 25℃–45℃ and the magnetic field strength to 300mT–800mT. The magnetic field direction can also be set perpendicular to the battery electrode plane, ensuring that the magnetic field lines pass through the thickness direction of the active material. Ensure that the device providing the controllable external magnetic field is parallel to the electrode and that the magnetic field lines are perpendicular to the electrode.
[0041] S3: Set the magnetic field mode, which can be selected from one of the following three modes: ① steady magnetic field; ② pulsed magnetic field (10Hz–10kHz, duty cycle 5%–100%); ③ combination mode of steady magnetic field + pulsed magnetic field.
[0042] S4: Perform a specific rate charge and discharge on a lithium-ion battery on a controllable magnetic field platform in a magnetic field (without disassembling the lithium-ion battery). The set conditions include a set temperature range and a magnetic field strength range. The set temperature range is between 25-45℃, and the magnetic field strength is 300mT–800mT. During the above charging and discharging process, a constant current at a specific rate can be used to charge the lithium-ion battery, and the charge can be cut off when a first set voltage is reached. A constant current at a specific rate can also be used to discharge the lithium-ion battery, and the discharge can be cut off when a second set voltage is reached. The first set voltage indicates when charging will stop at this first set voltage, and can be set to the rated voltage of the lithium-ion battery, which is 4.2-5.0V. The second set voltage indicates when discharging will stop at this second set voltage, and can be set between 0-3.0V. In the above charging and discharging process, the specific multiplier of the constant current used can be set to 0.01-0.5C. The direction of the magnetic field can also be set to be parallel to the lithium-ion battery electrode. To better understand the present invention, the following describes an embodiment of a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field, provided by an embodiment of the present invention.
[0043] Example 1 Example 1 of a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to an embodiment of the present invention includes the following steps.
[0044] The selected lithium-ion battery (without disassembling the lithium-ion battery) is connected to the charging and discharging instrument and placed in a stable magnetic field generated by a permanent magnet array. The magnetic field strength is 300-800mT and the magnetic field direction is perpendicular to the battery electrode.
[0045] For the selected lithium-ion battery 1, the first set voltage (charging cutoff voltage) is set to 4.5V and the second set voltage (discharging cutoff voltage) is set to 2.8V. After charging to the first set voltage of 4.5V with a current of 0.1C, it is discharged to 2.5V with a current of 0.1C. It is then circulated 3 times in a 0.5T magnetic field to complete the entire capacity recovery process.
[0046] The condition for selecting lithium-ion battery 1 is: LiNi 0.8 Co 0.1 Mn 0.1 O2|Gr type soft-pack battery. Figure 2 The figures show the cycle performance curves before and after capacity recovery in Example 1. Figure 2 As shown, the capacity is 395.4mAh after 100 cycles, and 399.4mAh after being restored by the magnetic field.
[0047] For the selected lithium-ion battery 2, the first set voltage is set to 4.5V and the second set voltage is set to 2.8V. After charging to the first set voltage with a 0.1C current, it is discharged to 2.5V with a 0.1C current. It is then circulated three times in a 0.3T magnetic field to complete the first capacity recovery process. Then, it continues to circulate for 20 more times until the battery capacity shows significant decay. Finally, it is circulated three times in a 0.5T magnetic field to complete the second capacity recovery process. Then, it continues to circulate for 20 more times until the battery capacity shows significant decay. Finally, it is circulated three times in a 0.8T magnetic field to complete the third capacity recovery process.
[0048] The conditions for selecting lithium-ion battery 2 are as follows: LiNi 0.8 Co 0.1 Mn 0.1 O2|Gr type soft-pack battery.
[0049] Figure 3 The figures show the cycling performance curves before and after capacity gradient recovery in Example 1. Figure 3As shown, after 50 cycles, the capacity is 402.2 mAh, and after the first capacity recovery using a magnetic field, the capacity is 408.2 mAh. After 50 cycles of degradation, the capacity of the lithium-ion battery increases from 402.3 mAh to 408.2 mAh after capacity recovery using a magnetic field. After another 20 cycles of degradation, the capacity of the lithium-ion battery decreases to 403.1 mAh, and after capacity recovery using a magnetic field, it increases to 407.1 mAh. After another 20 cycles of degradation, the capacity of the lithium-ion battery decreases to 403.7 mAh, and after capacity recovery using a magnetic field, it increases to 411.8 mAh.
[0050] The data obtained in Example 1 shows that the controlled external magnetic field charging and discharging method of the present invention can eliminate the polarization of lithium batteries synchronously or in stages without damaging the battery structure, thereby restoring the reversible capacity of the battery.
[0051] Example 2 Example 2 of a method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to an embodiment of the present invention includes the following steps.
[0052] The selected lithium-ion battery (without disassembling the lithium-ion battery) is connected to the charging and discharging instrument and placed in a steady magnetic field generated by a permanent magnet array. The magnetic field strength is 300mT-500mT and the magnetic field direction is perpendicular to the battery electrode.
[0053] The first set voltage (charging cutoff voltage) is set to 4.5V, and the second set voltage (discharging cutoff voltage) is set to 2.0V. After charging to the first set voltage with a 0.1C current, the battery is discharged to 2.5V with a 0.1C current. The battery is then circulated in a 0.3T magnetic field for 3 cycles to complete the first capacity recovery process. This process is then repeated 50 times until the battery capacity shows significant degradation. Finally, the battery is circulated in a 0.5T magnetic field for 3 cycles to complete the second capacity recovery process.
[0054] The conditions for selecting lithium-ion batteries are: Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2Gr type soft pack battery. Figure 4 The figures show the cycling performance curves before and after capacity gradient recovery in Example 2. Figure 4 As shown, after 50 cycles of degradation, the capacity of the lithium-ion battery increased from 97.6mAh to 101.7mAh after being restored by a magnetic field. After another 50 cycles of degradation, the capacity of the lithium-ion battery decreased to 98.5mAh, but increased to 103.0mAh after being restored by a magnetic field.
[0055] The data obtained in Example 2 shows that, by using a controllable external magnetic field to charge and discharge in situ without damaging the battery structure, the polarization of lithium-ion batteries of different systems can be eliminated simultaneously or in stages, thereby restoring the reversible capacity of the battery.
[0056] All of the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention, and will not be described in detail here.
[0057] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0058] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order and method of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for restoring the capacity of a failed positive electrode in a lithium-ion battery using a controllable external magnetic field, characterized in that, include: S1: Obtain the lithium-ion battery to be processed. The lithium-ion battery has undergone a number of cycles, accumulated polarization, and has capacity decay. S2: Based on the polarization and capacity decay of the lithium-ion battery to be processed, the charging rate of the lithium-ion battery is evaluated, which is used to adjust the magnetic field strength of the applied controllable external magnetic field. S3: Prepare a controllable external magnetic field to be applied to the lithium-ion battery. Without disassembling the lithium-ion battery, place the lithium-ion battery on the magnetic field platform, so that the direction of the magnetic field is perpendicular to the plane of the battery electrode and the uniformity is ≥90%. Set the magnetic field strength range of the controllable external magnetic field to 300mT–800mT and the duration of a single application of the controllable external magnetic field to 1–10 charge-discharge cycles. S4: Apply a magnetic field to the lithium-ion battery on the magnetic field platform using the prepared controllable external magnetic field. During the application of the magnetic field, provide a temperature range of 20℃–45℃ and charge and discharge the battery at a rate of 0.01C–0.5C until the preset single action time of the controllable external magnetic field is completed, and a lithium-ion battery with restored battery capacity is obtained.
2. The method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to claim 1, characterized in that, In S3, the duration of a single application of a controllable external magnetic field is determined based on the magnetic field strength. in, This refers to the magnetic field strength, measured in mT. The duration of a single action is expressed in revolutions. This represents the function for rounding up.
3. The method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to claim 1, characterized in that, A controllable external magnetic field is provided in one of the following three ways: Method 1: A steady magnetic field of 0.01T–1T is generated by a permanent magnet array or electromagnet; Method 2: A pulsed magnetic field is generated by an electromagnet. The frequency range of the pulsed magnetic field is 10Hz–10kHz, the duty cycle range is 5%–100%, and the pulse rise / fall time range is less than or equal to 100µs. Method 3 is a combination of Method 1 and Method 2.
4. The method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to claim 1, characterized in that, During the charge and discharge cycles of S4, the charging cutoff voltage is set in the range of 4.2 V–5.0 V, and the discharging cutoff voltage is set in the range of 0 V–3.0 V.
5. The method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to claim 1, characterized in that, In S4, the stage in which a magnetic field is applied to the lithium-ion battery is the cycling stage after the lithium-ion battery has been formed.
6. The method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to claim 1, characterized in that, The lithium-ion battery to be processed is one of the following: lithium nickel cobalt manganese oxide battery, lithium-rich manganese-based battery, lithium iron phosphate battery, and lithium manganese iron phosphate battery.
7. The method for restoring the capacity of a failed positive electrode of a lithium-ion battery using a controllable external magnetic field according to claim 1, characterized in that, The lithium-ion batteries to be processed are cylindrical, pouch, or prismatic.