Secondary battery capacity repair method, secondary battery, and electrical equipment

Abstract

The present application relates to the field of secondary batteries, and provides a capacity repair method for a secondary battery, a secondary battery, and an electrical device, which are at least beneficial for repairing the capacity of a decayed secondary battery. The capacity repair method includes: providing a secondary battery to be repaired; discharging the secondary battery to be repaired to a safe capacity; evacuating the secondary battery to be repaired to expel residual gas in the secondary battery to be repaired; injecting a capacity repair agent into the secondary battery to be repaired, wherein the material of the capacity repair agent includes a chemically active material, the structure of the chemically active material satisfies α-β…γ, the α group and the β group are connected in the form of a covalent bond, the β group and the γ group are connected in the form of a covalent bond or an ionic bond, and the β group is used to provide a site for an electrochemical reaction; charging and discharging the secondary battery to be repaired; and encapsulating the secondary battery to be repaired to obtain a repaired secondary battery.

Description

Technical Field

[0001] The present application relates to the field of secondary batteries, and in particular to a capacity repair method of a secondary battery, a secondary battery, and an electrical device. Background Art

[0002] During the use of secondary batteries, the capacity of the battery will decay to varying degrees due to many factors such as the dissolution of electrode active materials, thickening of electrochemical impedance spectroscopy, and decomposition of the electrolyte, which seriously affects the battery's cycle performance and service life.

[0003] In response to the above situation, researchers have conducted extensive research from various perspectives to improve the comprehensive performance of secondary batteries. Currently, common approaches include improving the performance of secondary batteries through material preparation and assembly processes. For example, efforts are underway to prepare electrode materials with higher capacity and more stable structures, improve the material's conductivity through coating and doping, and thus increase its cycle performance and service life. Alternatively, efforts are underway to prepare electrolytes with superior electrical conductivity to reduce electron loss during transmission, improve electrode slurry coating processes, and optimize process flows.

[0004] Currently, there is a lack of in-depth research on the capacity repair of secondary batteries with capacity decay. Summary of the Invention

[0005] The embodiments of the present application provide a method for repairing the capacity of a secondary battery, a secondary battery, and an electrical device, which are at least beneficial for repairing the capacity of a decayed secondary battery.

[0006] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a method for repairing the capacity of a secondary battery, comprising: providing a secondary battery to be repaired; discharging the secondary battery to be repaired to a safe capacity; vacuuming the secondary battery to be repaired by opening micropores on the shell of the secondary battery to be repaired or the original liquid injection port of the secondary battery to be repaired to discharge residual gas in the secondary battery to be repaired; injecting a capacity repair agent into the secondary battery to be repaired through the liquid injection port or the micropores, wherein the material of the capacity repair agent comprises a chemically active material, the structure of the chemically active material satisfies α-β…γ, the α group and the β group are connected in the form of a covalent bond, the β group and the γ group are connected in the form of a covalent bond or an ionic bond, and the β group is used to provide a site for an electrochemical reaction; performing charge and discharge treatment on the secondary battery to be repaired, discharging the secondary battery to be repaired after charging it to a cutoff potential, wherein the cutoff potential is greater than the oxidation potential of the chemically active material; packaging the secondary battery to be repaired to obtain a repaired secondary battery.

[0007] In some embodiments, injecting the capacity repair agent into the secondary battery to be repaired includes: injecting the capacity repair agent into the secondary battery to be repaired in a pulse mode, with the injection volume of each pulse being 0.1 mL to 0.5 mL and the interval time being 5 s to 15 s.

[0008] In some embodiments, after injecting the capacity repair agent into the secondary battery to be repaired, the method further includes: ultrasonically treating the secondary battery to be repaired, wherein the process parameters of the ultrasonic treatment include: ultrasonic frequency of 20kHz~5MHz, ultrasonic power of 1W~150W, and ultrasonic time of 5min~30min.

[0009] In some embodiments, during the process of injecting the capacity repair agent into the secondary battery to be repaired, the secondary battery to be repaired is maintained at an environment of 40°C~50°C; after the capacity repair agent is injected into the secondary battery to be repaired, the secondary battery to be repaired is cooled to 20°C~25°C.

[0010] In some embodiments, the safe capacity refers to a state of charge of 0% to 20%.

[0011] In some embodiments, charging and discharging the secondary battery to be repaired includes: charging the secondary battery to be repaired to above the oxidation potential of the chemically active material using a preset charging rate, and discharging the secondary battery to be repaired to a safe capacity using a preset discharge rate, wherein the preset charging rate is less than the preset discharge rate.

[0012] In some embodiments, the secondary battery to be repaired is charged to above the oxidation potential of the chemically active material using a preset charging rate, and the secondary battery to be repaired is discharged to a safe capacity using a preset discharge rate as one charge and discharge cycle, and the charge and discharge treatment of the secondary battery to be repaired includes at least three charge and discharge cycles.

[0013] In some embodiments, the difference between the cutoff potential and the oxidation potential of the chemically active material is greater than or equal to 0.3V.

[0014] In some embodiments, after the secondary battery to be repaired is charged and discharged, and before the secondary battery to be repaired is packaged, it also includes: exhaust treatment and static treatment, the secondary battery to be repaired is vacuumed to discharge the gas generated by the decomposition of the chemically active material, and the secondary battery to be repaired is left to stand at a pressure of 0.5Mpa~2Mpa for 12h~24h.

[0015] In some embodiments, the mass of the chemically active material is M, and M satisfies the following relationship: M=Q / C, where Q is the lost capacity of the secondary battery to be repaired, and C is the gram capacity of the chemically active material.

[0016] In some embodiments, the capacity repair agent includes a solvent, and the solvent is the same as the original solvent in the secondary battery to be repaired.

[0017] In some embodiments, the concentration of the chemically active material in the solvent is 1 wt % to 30 wt %.

[0018] In some embodiments, the α group is selected from -CN, -C n H 2n+1 、-C n F 2n+1 、-C n+1 F3H 2n 、 or One of the following; β group is selected from -CO2-, -CO2 - 、-SO2 - 、-SO3 - 、-NO2 - One of the following; γ group is selected from -CN, -C n H 2n+1 、-C n F 2n+1 、-C n+1 F3H 2n 、 、 、Li + 、Zn 2+ 、[C x mim] + , N-alkylpyridine, tetraalkylammonium, tetraalkylphosphonium; wherein n is independently a positive integer between 0 and 16, and x is a positive integer between 1 and 4.

[0019] According to some embodiments of the present application, on the other hand, embodiments of the present application further provide a secondary battery, and the capacity of the secondary battery is repaired using the capacity repair method of the secondary battery in the above embodiment.

[0020] According to some embodiments of the present application, on the other hand, embodiments of the present application further provide an electrical device, which includes a secondary battery as in the above embodiments, or the electrical device includes an energy storage system, which includes a secondary battery as in the above embodiments.

[0021] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0022] In the capacity repair method of a secondary battery provided in the embodiment of the present application, the capacity repair of the secondary battery is achieved through a full-process design of screening-pretreatment-capacity repair agent injection-activation-encapsulation. After discharging its voltage to a safe capacity, vacuum is first performed to remove residual gases (such as CO2, H2) in the secondary battery to prevent gas blockage from affecting the diffusion of the capacity repair agent. The capacity repair agent is then injected. The capacity repair agent contains a chemically active material with an α-β…γ structure. The β group serves as an electrochemical reaction site. The chemically active material is activated and uniformly distributed through charge and discharge treatment. After charging to a high potential, the β group in the capacity repair agent is forced to oxidize on the electrode surface. During the charge and discharge process, the reciprocating migration of metal ions drives the diffusion of the capacity repair agent to avoid local agglomeration. Finally, the secondary battery is encapsulated to ensure the structural integrity and long-term stability of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is a flowchart corresponding to a method for repairing the capacity of a secondary battery provided in one embodiment of the present application. DETAILED DESCRIPTION

[0025] As can be seen from the background technology, there is currently a lack of in-depth research on capacity restoration of secondary batteries with capacity decay.

[0026] In the capacity repair method of a secondary battery provided in an embodiment of the present application, the capacity repair of the secondary battery is achieved through a full process design of screening-pretreatment-capacity repair agent injection-activation-packaging.

[0027] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0028] In the description of the embodiments of the present application, “multiple” means more than two, unless otherwise clearly and specifically defined.

[0029] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] In the description of the embodiments of the present application, when a component “includes” another component, unless otherwise stated, other components are not excluded, and other components may be further included.

[0031] The terms used in the description of the various embodiments described herein are for describing specific embodiments only and are not intended to be limiting. As used in the description of the various embodiments described and the appended claims, "components" are also intended to include plural forms unless the context clearly indicates otherwise.

[0032] The following detailed description of the various embodiments of the present application is provided in conjunction with the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present application to facilitate a better understanding of the present application. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0033] Figure 1 This is a flowchart corresponding to a method for repairing the capacity of a secondary battery provided in one embodiment of the present application.

[0034] refer to Figure 1 The capacity repair method of the secondary battery provided in the embodiment of the present application is as follows.

[0035] S101. Provide a secondary battery to be repaired.

[0036] S102: Discharge the secondary battery to be repaired to a safe capacity.

[0037] S103 , vacuuming the secondary battery to be repaired by opening microholes on the shell of the secondary battery to be repaired or the original liquid injection port of the secondary battery to be repaired, so as to discharge residual gas in the secondary battery to be repaired.

[0038] S104. Inject a capacity repair agent into the secondary battery to be repaired through the injection port or micropores. The material of the capacity repair agent includes a chemically active material. The structure of the chemically active material satisfies α-β...γ. The α group and the β group are connected by a covalent bond, and the β group and the γ group are connected by a covalent bond or an ionic bond. The β group is used to provide a site for an electrochemical reaction.

[0039] S105 , performing charge and discharge processing on the secondary battery to be repaired, charging the secondary battery to be repaired to a cut-off potential and then discharging the battery, wherein the cut-off potential is greater than the oxidation potential of the chemically active material.

[0040] S106: Encapsulate the secondary battery to be repaired to obtain a repaired secondary battery.

[0041] In the capacity repair method of a secondary battery provided in the embodiment of the present application, the capacity repair of the secondary battery is achieved through a full-process design of screening-pretreatment-capacity repair agent injection-activation-encapsulation. After discharging its voltage to a safe capacity, vacuum is first performed to remove residual gases (such as CO2, H2) in the secondary battery to prevent gas blockage from affecting the diffusion of the capacity repair agent. The capacity repair agent is then injected. The capacity repair agent contains a chemically active material with an α-β…γ structure. The β group serves as an electrochemical reaction site. The chemically active material is activated and uniformly distributed through charge and discharge treatment. After charging to a high potential, the β group in the capacity repair agent is forced to oxidize on the electrode surface. During the charge and discharge process, the reciprocating migration of metal ions drives the diffusion of the capacity repair agent to avoid local agglomeration. Finally, the secondary battery is encapsulated to ensure the structural integrity and long-term stability of the secondary battery.

[0042] In this embodiment, the secondary battery to be repaired refers to a secondary battery with a state of health (SOH) below 80% or a charge-discharge cycle count greater than 2000. The secondary battery capacity repair method provided in this embodiment can at least repair the capacity of severely aged or highly cycled secondary batteries.

[0043] In other embodiments, the secondary battery to be repaired may also be a secondary battery after the first formation process and before the second liquid injection formation process, that is, the capacity repair agent is added to the secondary battery after the first liquid injection formation and before the second liquid injection formation.

[0044] In other embodiments, the secondary battery to be repaired may be a new secondary battery that has not undergone the first formation process, that is, the capacity repair agent is added to the secondary battery when the electrolyte is first injected into the secondary battery.

[0045] In step S102, the safe capacity refers to the state of charge (SOC) of the secondary battery to be repaired being between 0% and 20%, for example, 0%, 1%, 3%, 5%, 8%, 10%, 13%, 16%, 18%, or 20%. A low charge state can prevent problems such as short circuits, gassing, or lithium deposition. It also prevents side reactions between the capacity repair agent and the electrode material at high potential after the subsequent injection of the capacity repair agent, thereby improving the stability of the secondary battery.

[0046] In step S103, a negative pressure environment is created by opening micropores on the shell of the secondary battery to be repaired or vacuuming the original liquid injection port of the secondary battery to be repaired, thereby optimizing the subsequent penetration path of the capacity repair agent and accelerating the penetration of the capacity repair agent into the electrode pores through the capillary action formed by the micropores.

[0047] In step 104, a capacity repair agent is injected into the secondary battery to be repaired, wherein the capacity repair agent contains a chemically active material with an α-β...γ structure.

[0048] Wherein, the α group is selected from -CN, -C n H 2n+1 、-C n F 2n+1 、-C n+1 F3H 2n 、 ,or One of the following. The β group is selected from -CO2-, -CO2 - 、-SO2 - 、-SO3 - 、-NO2 - One of the following. The γ group is selected from -CN, -C n H 2n+1 、-C n F 2n+1 、-C n+1 F3H 2n 、 、 、Li + 、Zn 2+ (The secondary battery to be repaired is a zinc ion battery), [C x mim] + , N-alkylpyridine, tetraalkylammonium, and tetraalkylphosphonium. wherein n is independently a positive integer between 0 and 16, and x is a positive integer between 1 and 4.

[0049] For example, the chemically active material is selected from one or more of the following compounds:

[0050] 、CF3NO2Li、CF3SO2 - [C2mim] + 、CF3SO3Li、CH3COOCH3、 、 、 、 、 、 .

[0051] In one example, injecting the capacity repair agent into the secondary battery to be repaired includes injecting the capacity repair agent into the secondary battery to be repaired in a pulsed mode. The pulsed mode injection allows the capacity repair agent to be injected into the secondary battery to be repaired in batches at different angles, thereby improving the uniformity of the capacity repair agent injection and preventing accumulation of the capacity repair agent in localized areas.

[0052] The injection volume of each pulse is 0.1 mL to 0.5 mL, for example, 0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL or 0.5 mL; the pulse interval is 5 s to 15 s, for example, 5 s, 6 s, 7 s, 8 s, 9 s, 10 s, 11 s, 12 s, 13 s, 14 s or 15 s.

[0053] In another example, after injecting the capacity repair agent into the secondary battery to be repaired, the method further includes: subjecting the secondary battery to be repaired to ultrasonic treatment. Ultrasonic treatment after injection of the capacity repair agent disrupts interfacial tension, thereby improving the uniformity of the capacity repair agent injection and preventing accumulation of the capacity repair agent in localized areas.

[0054] The process parameters of the ultrasonic treatment include: an ultrasonic frequency of 20kHz to 5MHz, for example, it can be 20kHz, 50kHz, 100kHz, 300kHz, 500kHz, 800kHz, 1MHz, 1.3MHz, 1.8MHz, 2MHz, 3MHz or 5MHz; an ultrasonic power of 1W to 150W, for example, it can be 1W, 10W, 30W, 50W, 80W, 100W, 130W or 150W; and an ultrasonic time of 5min to 30min, for example, it can be 5min, 10min, 15min, 20min, 25min or 30min.

[0055] It is understandable that different injection methods can be selected for different capacity repair agents, such as pulse injection or ultrasonic treatment after injection, and the corresponding process parameters can be adjusted according to the characteristics of the capacity repair agent.

[0056] During step S104, while injecting the capacity repair agent into the secondary battery to be repaired, the secondary battery to be repaired can be maintained at a temperature of 40°C to 50°C, for example, 40°C, 43°C, 45°C, 48°C, or 50°C. Before step S105, after injecting the capacity repair agent into the secondary battery to be repaired, the secondary battery to be repaired can be cooled to 20°C to 25°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, or 25°C. During the injection of the capacity repair agent, a higher temperature is beneficial for reducing the viscosity of the electrolyte. After the capacity repair agent is injected, cooling is performed to enhance the mixing effect of the electrolyte through hot and cold convection.

[0057] In some embodiments, the mass of the chemically active material is M, and M satisfies the following relationship: M=Q / C, where Q is the lost capacity of the secondary battery to be repaired, and C is the gram capacity of the chemically active material.

[0058] In other implementations, the mass M of the chemically active material may not be equal to Q / C, for example, (Q / C)×0.9≤M≤(Q / C)×1.1. In other words, the mass M of the chemically active material may fluctuate within a certain range based on the value calculated based on Q / C.

[0059] It should be noted that when the secondary battery to be repaired undergoes the initial formation process but before the secondary liquid injection and formation process, that is, the capacity repair agent is added to the secondary battery after the initial liquid injection and formation process but before the secondary liquid injection and formation process, the lost capacity Q of the secondary battery to be repaired is the lost capacity after the initial liquid injection and formation process. When the secondary battery is a new secondary battery that has not undergone the initial formation process, that is, the capacity repair agent is added to the secondary battery during the initial injection of electrolyte into the secondary battery, the lost capacity Q of the secondary battery to be repaired can be a predicted value.

[0060] In some embodiments, the capacity repair agent includes a solvent that is the same as the original solvent in the secondary battery to be repaired. This can avoid phase separation between the newly introduced capacity and the original capacity, and improve the compatibility between the original electrolyte and the capacity repair agent.

[0061] In some embodiments, the concentration of the chemically active material in the solvent is 1 wt% to 30 wt%, for example, 1 wt%, 3 wt%, 5 wt%, 10 wt%, 12 wt%, 16 wt%, 18 wt%, 20 wt%, 23 wt%, 25 wt%, 28 wt% or 30 wt%.

[0062] In step S105, the battery to be repaired is charged and discharged, including: charging the battery to a level above the oxidation potential of the chemically active material at a preset charge rate, and discharging the battery to a safe capacity at a preset discharge rate, wherein the preset charge rate is lower than the preset discharge rate. Low-rate charging facilitates uniform metal ion generation and migration to the electrode surface, preventing uneven current flow across the electrode due to varying metal ion concentrations in different regions. High-rate discharge improves charge and discharge efficiency, thereby increasing activation efficiency.

[0063] The preset charge rate is 0.05C to 0.1C, for example, 0.05C, 0.06C, 0.07C, 0.08C, 0.09C, or 0.1C. The preset discharge rate is 0.2C to 1C, for example, 0.2C, 0.3C, 0.4C, 0.5C, 0.6C, 0.7C, 0.8C, 0.9C, or 1C.

[0064] In some embodiments, charging the repaired secondary battery to a level above the oxidation potential of the chemically active material using a preset charge rate and discharging the repaired secondary battery to a safe capacity using a preset discharge rate constitutes one charge-discharge cycle, and the charge-discharge treatment of the repaired secondary battery comprises at least three charge-discharge cycles. In some embodiments, the number of charge-discharge treatments performed on the repaired secondary battery is greater than or equal to three times. Multiple charge-discharge cycles avoid uneven decomposition of the active material in a single charge, resulting in insufficient activation, and improve the stability of the secondary battery after capacity repair.

[0065] The difference between the cutoff potential and the oxidation potential of the chemically active material is greater than or equal to 0.3 V, which can be beneficial for fully activating the electrochemically active material.

[0066] The oxidation potential of chemically active materials can be measured using cyclic voltammetry. Specifically, an electrochemical workstation is used, with a platinum electrode as the working electrode, a lithium sheet as the counter electrode, and an electrolyte containing the chemically active material. The platinum electrode, polished with a 0.05 μm alumina slurry, is rinsed with ultrapure water, ultrasonicated in ethanol for 1 minute, and then air-dried. The surface passivation layer of the lithium sheet is scraped off using sandpaper or a brush. In a dry environment, the platinum electrode and lithium sheet are mounted in an electrolytic cell and the electrolyte containing the chemically active material is poured in, completely immersing the electrode surfaces. The electrochemical workstation is connected and the test parameters are set: scan window: 2.5 V to 4.3 V; scan rate: 50 mV / s; number of scan cycles: 2. The electrochemical workstation is then started and the current-voltage curve is recorded. The voltage corresponding to the oxidation peak of the chemically active material on the current-voltage curve is used as the oxidation potential of the chemically active material.

[0067] After the secondary battery to be repaired is charged and discharged in step S105, and before the secondary battery to be repaired is packaged in step S106, the process further includes: exhaust treatment and standing treatment, wherein the secondary battery to be repaired is vacuumed to exhaust gas generated by the decomposition of chemically active materials, and the secondary battery to be repaired is stood at a pressure of 0.5 MPa to 2 MPa (for example, specifically 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.2 MPa, 1.4 MPa, 1.6 MPa, 1.8 MPa or 2 MPa) for 12 h to 24 h (for example, specifically 12 h, 16 h, 18 h, 20 h, 21 h, 23 h or 24 h).

[0068] Correspondingly, another aspect of the embodiment of the present application further provides a secondary battery, and the capacity of the secondary battery is repaired using the capacity repair method of the secondary battery in the above embodiment.

[0069] Correspondingly, another aspect of the embodiments of the present application further provides an electrical device, which includes a secondary battery as in the above embodiments, or the electrical device includes an energy storage system, which includes a secondary battery as in the above embodiments.

[0070] In the capacity repair method of a secondary battery provided in the embodiment of the present application, the capacity repair of the secondary battery is achieved through a full-process design of screening-pretreatment-capacity repair agent injection-activation-encapsulation. After discharging its voltage to a safe capacity, vacuum is first performed to remove residual gases (such as CO2, H2) in the secondary battery to prevent gas blockage from affecting the diffusion of the capacity repair agent. The capacity repair agent is then injected. The capacity repair agent contains a chemically active material with an α-β…γ structure. The β group serves as an electrochemical reaction site. The chemically active material is activated and uniformly distributed through charge and discharge treatment. After charging to a high potential, the β group in the capacity repair agent is forced to oxidize on the electrode surface. During the charge and discharge process, the reciprocating migration of metal ions drives the diffusion of the capacity repair agent to avoid local agglomeration. Finally, the secondary battery is encapsulated to ensure the structural integrity and long-term stability of the secondary battery.

[0071] The following are specific examples of this application.

[0072] Example 1

[0073] (1) A lithium-ion secondary battery (solvent EC / DMC) with a SOH of 70% and a cycle count of 2500 was selected and discharged to 1.5 V. The residual gas was exhausted by vacuuming the original injection port.

[0074] (2) A capacity repair agent (concentration of 10 wt %, solvent: EC / DMC) containing CF3NO2Li (oxidation potential of 4.1 V) was injected in a pulsed manner (0.3 mL / pulse, interval time of 10 s).

[0075] (3) Charge at 0.05C to 4.6V (oxidation potential 4.1+0.5V), discharge at 0.5C, and cycle 3 times.

[0076] (4) After exhausting, let it stand (1Mpa, 18h) and then package.

[0077] Example 2

[0078] (1) The battery to be repaired is the same as that in Example 1. It is discharged to 2V and vacuumed through the original liquid injection port to discharge the residual gas.

[0079] (2) Inject CF3SO2 in a pulsed manner (0.2 mL / pulse, 5 s interval) - [C2mim] + (oxidation potential of 3.7V) capacity repair agent (concentration of 20wt%, solvent is EC / DMC).

[0080] (3) Charge to 4.1V (oxidation potential 3.7V+0.4V) at 0.1C, discharge at 0.8C, and cycle 5 times.

[0081] (4) After exhausting, let it stand (1Mpa, 18h) and then package.

[0082] Example 3

[0083] (1) The battery to be repaired is the same as that in Example 1. It is discharged to 1V and vacuumed through the original liquid injection port to discharge the residual gas.

[0084] (2) Injection containing The capacity repair agent (concentration of 10wt%, solvent of EC / DMC) with an oxidation potential of 4V was subjected to ultrasonic treatment (frequency 40kHz, power 100W, time 5min).

[0085] (3) Charge at 0.05C to 4.4V (oxidation potential 4+0.4V), discharge at 0.5C, and cycle 3 times.

[0086] (4) After exhausting, let it stand (1Mpa, 18h) and then package.

[0087] Example 4

[0088] The difference between Example 4 and Example 1 is that the capacity repair agent is directly injected in step (2), and the battery temperature is raised to 50°C and then cooled to 25°C.

[0089] Example 5

[0090] The difference between Example 5 and Example 1 is that the secondary battery to be repaired is a secondary battery after the first liquid injection and formation (solvent EC / DMC), and the SOH is 98%.

[0091] Comparative Example 1

[0092] The difference between Comparative Example 1 and Example 1 is that the charging potential in step (3) is 4V.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Example 1 is that the vacuuming is omitted in step (1) and step (2) is directly performed.

[0095] The secondary batteries after capacity repair in the above embodiments and comparative examples were tested to obtain the SOH of the secondary batteries after capacity repair. The results are shown in the following table.

[0096]

[0097] According to Examples 1 to 4, the capacity restoration method for secondary batteries provided in the embodiments of the present application can achieve a restoration of over 80% of the battery life of the secondary battery by first discharging and evacuating the battery after the battery life has declined, then charging the secondary battery to above the oxidation potential after injecting the capacity restoration agent, and then discharging the secondary battery, and then encapsulating the secondary battery. Depending on the choice of chemically active material in the capacity restoration agent, the injection method of the capacity restoration agent, the concentration of the chemically active material, the battery temperature, the charge and discharge parameters, the number of cycles, etc. can be adjusted accordingly.

[0098] According to Example 5, it can be found that the SOH of the secondary battery after the first liquid injection and formation is 98% based on the theoretical maximum capacity. According to the capacity repair method of the secondary battery provided in the embodiment of the present application, the capacity repair of the secondary battery after the first liquid injection and formation can be performed, and the SOH of the secondary battery after the first liquid injection and formation can be repaired to 100%.

[0099] According to the comparison between Example 1 and Comparative Example 1, it can be found that when the charging potential is lower than the oxidation potential of the chemically active material, the chemically active material may not react fully, thereby causing the capacity repair effect of the secondary battery to be unobvious.

[0100] According to the comparison between Example 1 and Comparative Example 2, it can be found that the exhaust treatment is not performed before the injection of the capacity repair agent, which results in the diffusion of the capacity repair agent being hindered, which is not conducive to the capacity repair agent taking effect.

[0101] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present application, and that in actual applications, various changes in form and detail may be made thereto without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A method for restoring the capacity of a secondary battery, characterized in that: include: Provide secondary batteries to be repaired; Discharging the secondary battery to be repaired to a safe capacity; By opening a microhole on the shell of the secondary battery to be repaired or the original liquid injection port of the secondary battery to be repaired, the secondary battery to be repaired is vacuumed to discharge residual gas in the secondary battery to be repaired; A capacity repair agent is injected into the secondary battery to be repaired through the injection port or the micropore. The material of the capacity repair agent includes a chemically active material. The structure of the chemically active material satisfies α-β...γ. The α group and the β group are connected in the form of a covalent bond, and the β group and the γ group are connected in the form of a covalent bond or an ionic bond. The β group is used to provide a site for electrochemical reaction. The α group is selected from -CN, -C n H 2n+1 、-C n+1 F3H 2n 、 or One of the following; the β group is selected from -CO2-, -SO2 - 、-NO2 - One of the following; the γ group is selected from -CN, -C n H 2n+1 、-C n F 2n+1 、-C n+1 F3H 2n 、 、 、Li + 、Zn 2+ 、[C x mim] + , one of N-alkylpyridine, tetraalkylammonium, and tetraalkylphosphonium; wherein n is independently a positive integer between 0 and 16, and x is a positive integer between 1 and 4; performing a charge-discharge process on the secondary battery to be repaired, charging the secondary battery to be repaired to a cut-off potential and then discharging the battery, wherein the cut-off potential is greater than the oxidation potential of the chemically active material; The secondary battery to be repaired is packaged to obtain a repaired secondary battery.

2. The method for restoring the capacity of a secondary battery according to claim 1, wherein: Injecting the capacity repair agent into the secondary battery to be repaired includes: injecting the capacity repair agent into the secondary battery to be repaired in a pulse mode, with the injection volume of each pulse being 0.1 mL to 0.5 mL and the interval time being 5 s to 15 s.

3. The method for restoring the capacity of a secondary battery according to claim 1, wherein: After injecting the capacity repair agent into the secondary battery to be repaired, the method further includes: performing ultrasonic treatment on the secondary battery to be repaired, wherein the process parameters of the ultrasonic treatment include: ultrasonic frequency of 20kHz~5MHz, ultrasonic power of 1W~150W, and ultrasonic time of 5min~30min.

4. The method for restoring the capacity of a secondary battery according to any one of claims 1 to 3, wherein: During the process of injecting the capacity repair agent into the secondary battery to be repaired, the secondary battery to be repaired is maintained at an environment of 40°C to 50°C; after injecting the capacity repair agent into the secondary battery to be repaired, the secondary battery to be repaired is cooled to 20°C to 25°C.

5. The method for restoring the capacity of a secondary battery according to claim 1, wherein: The safe capacity refers to the state of charge of 0% to 20%.

6. The method for restoring the capacity of a secondary battery according to claim 1, wherein: The charge and discharge processing of the secondary battery to be repaired includes: charging the secondary battery to be repaired to above the oxidation potential of the chemically active material using a preset charge rate, and discharging the secondary battery to be repaired to the safe capacity using a preset discharge rate, wherein the preset charge rate is less than the preset discharge rate.

7. The method for restoring the capacity of a secondary battery according to claim 6, wherein: Charging the secondary battery to be repaired to above the oxidation potential of the chemically active material using the preset charging rate, and discharging the secondary battery to be repaired to the safe capacity using the preset discharge rate is regarded as one charge-discharge cycle, and the charge-discharge treatment of the secondary battery to be repaired includes at least three of the charge-discharge cycles.

8. The method for restoring the capacity of a secondary battery according to claim 1, wherein: A difference between the cutoff potential and an oxidation potential of the chemically active material is greater than or equal to 0.3V.

9. The method for restoring the capacity of a secondary battery according to claim 1, wherein: After the charge and discharge treatment is performed on the secondary battery to be repaired, and before the secondary battery to be repaired is packaged, the process also includes: exhaust treatment and standing treatment, wherein the secondary battery to be repaired is vacuumed to exhaust the gas generated by the decomposition of the chemically active material, and the secondary battery to be repaired is stood at a pressure of 0.5Mpa~2Mpa for 12h~24h.

10. The method for restoring the capacity of a secondary battery according to claim 1, wherein: The mass of the chemically active material is M, and M satisfies the following relationship: M=Q / C, where Q is the lost capacity of the secondary battery to be repaired, and C is the gram capacity of the chemically active material.

11. The method for restoring the capacity of a secondary battery according to claim 1, wherein: The capacity repair agent includes a solvent, and the solvent is the same as the original solvent in the secondary battery to be repaired.

12. The method for restoring the capacity of a secondary battery according to claim 11, wherein: The concentration of the chemically active material in the solvent is 1 wt % to 30 wt %.

13. A secondary battery, characterized in that: The capacity of the secondary battery is repaired using the capacity repair method for a secondary battery according to any one of claims 1 to 12.

14. An electrical device, characterized in that: The electrical device includes the secondary battery according to claim 13, or the electrical device includes an energy storage system, and the energy storage system includes the secondary battery according to claim 13.

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