Performance repairing method of lithium ion battery, lithium ion battery and electric device

Abstract

The application discloses a performance repairing method of a lithium ion battery, the lithium ion battery and an electric equipment. The performance repairing method comprises the following steps: (1) screening the retired batteries to screen the repairable retired batteries; (2) performing specific discharge treatment on the repairable retired batteries; (3) performing exhaust on the retired batteries, and adding a functional additive liquid, wherein the functional additive liquid comprises acid; (4) charging the retired batteries; (5) discharging at least part of electrolyte and waste gas in the retired batteries; (6) adding a functional repairing electrolyte into the retired batteries; and (7) aging and forming. According to the method, the metal impurities deposited on the electrode surface are removed, and the SEI film is repaired, so that the capacity expression and stability of the retired batteries are greatly improved, the impedance of the retired batteries is reduced, and the safety performance and cycle life performance of the retired batteries are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium ion batteries, and particularly relates to a performance repair method of a lithium ion battery, a lithium ion battery and an electric device. BACKGROUND

[0002] Power batteries will produce gas in the battery due to the factors such as the mixing of moisture in the production and manufacturing process, high-temperature use, overcharging, over-discharging, and side reactions in the cycle process, resulting in a decrease in battery performance. In order to improve the electrical performance of retired batteries, the prior art adopts a method of directly discharging the by-product gas in the battery, vacuum drying, and then injecting electrolyte to complete sealing, thereby repairing the used performance-degraded battery or the gas-swollen battery. The prior art also adopts a step of first supplementing liquid and then removing gas.

[0003] However, the prior art can only restore the size change of the battery and add a relatively single component of lithium salt electrolyte to supplement the loss of lithium ions in the battery, and cannot improve the existing structure of the SEI in the battery, so the improvement effect on the capacity and cycle stability of the battery is not obvious. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, the present application aims to provide a performance repair method of a lithium ion battery, a lithium ion battery and an electric device. The method of the present application can greatly improve the capacity expression and stability of the retired battery, reduce the impedance of the retired battery, and improve the safety performance and cycle life performance of the retired battery by repairing the electrical performance of the retired battery and removing the metal impurities deposited on the electrode surface while repairing the SEI film.

[0005] In one aspect of the present application, the present application provides a performance repair method of a lithium ion battery. According to an embodiment of the present application, the sulfide solid-state electrolyte includes:

[0006] (1) screening the retired battery to select a repairable retired battery;

[0007] (2) performing a specific discharge treatment on the repairable retired battery;

[0008] (3) discharging the retired battery, adding a functional additive liquid, the functional additive liquid including an acid;

[0009] (4) charging the retired battery;

[0010] (5) at least partially discharging the electrolyte and waste gas in the retired battery;

[0011] (6) adding a functional repair electrolyte to the retired battery;

[0012] (7) To age and become.

[0013] According to the performance repair method of lithium-ion batteries of an embodiment of the present invention, retired batteries are first screened according to their capacity, gas production, and internal resistance to select repairable retired batteries. The repairable retired batteries are then subjected to a specific discharge treatment to promote the decomposition of the SEI layer on the surface of the battery's negative electrode sheet to a certain extent, reducing the thickness of the SEI layer to facilitate the reformation of the SEI layer composition and structure in subsequent steps. The retired batteries are then vented under negative pressure, functional additive liquid is added, and the retired batteries are charged. During this process, the functional additive liquid reacts with the metal layer on the surface of the battery's negative electrode SEI film to remove metal impurity deposits, forming a dense LiF thin layer, and improving the uniformity of Li + The process improves the battery's flux capacity and inhibits the growth of lithium crystals, while simultaneously reforming and repairing the SEI film composition and structure in the first phase. The electrolyte and exhaust gas in the retired battery are then at least partially discharged, and a functional repair electrolyte is added to the retired battery. Finally, the battery is aged and formed, and the SEI film composition and structure are reformed and repaired in the second phase, constructing an electrode interface film with a stable structure and excellent performance. This effectively protects the electrode surface and prevents the precipitation of lithium dendrites, ultimately achieving performance repair of the retired battery. This significantly improves the capacity expression and stability of the retired battery, reduces the impedance of the retired battery, and enhances the safety performance and cycle life performance of the retired battery.

[0014] In addition, the performance repair method of the lithium-ion battery according to the above embodiment of the present invention may also have the following additional technical features:

[0015] In some embodiments of the present invention, in step (1), the retired batteries are graded and screened according to their capacity, gas production, and internal resistance; the retired batteries are graded A1 if their current capacity is more than 60% of their factory capacity, graded A2 if their current capacity is 40% to 60% of their factory capacity but not equal to 60%; the retired batteries are scrapped if their current capacity is less than 40% of their factory capacity; the retired batteries are graded B1 if their thickness increases by no more than 25% compared to their factory thickness; and graded B2 if their thickness increases by more than 20% compared to their factory thickness. 5% but not more than 35%, which is B2 grade; compared with the thickness of the factory battery, the thickness of the retired battery increases by more than 35% but not more than 45%, which is B3 grade; compared with the thickness of the factory battery, the thickness of the retired battery increases by more than 45%, it is scrapped; the DC impedance of the retired battery is within 2.5 times of the factory battery DC impedance, which is C1 grade; the DC impedance of the retired battery is 2.5 times to 3.5 times but not equal to 2.5 times that of the factory battery DC impedance, which is C2 grade; the DC impedance of the retired battery is more than 3.5 times but not equal to 3.5 times that of the factory battery DC impedance, which is scrapped.

[0016] In some embodiments of the present application, step (2) comprises: (2-1) discharging the retired battery to 2.0 V; (2-2) discharging the retired battery to 0.8 V-1.5 V, the discharge cutoff capacity being 2%-10% of the current capacity of the retired battery, and the discharge current being less than or equal to 0.1 C.

[0017] In some embodiments of the present application, in step (3), the functional additive solution comprises an acid, a first solvent and a first film-forming additive, the mass content of the acid being less than or equal to 0.5%, and the mass content of the first film-forming additive being 0.5%-3%, based on the total mass of the functional additive solution.

[0018] In some embodiments of the present application, in step (3), the retired battery is divided into G1 batteries, G2 batteries, G3 batteries and G4 batteries, the G1 batteries comprising A1B1C1 batteries, A1B1C2 batteries and A1B2C1 batteries, the G2 batteries comprising A1B2C2 batteries, A2B1C2 batteries and A2B1C1 batteries, the G3 batteries comprising A2B2C1 batteries and A1B3C1 batteries, and the G4 batteries comprising A1B3C2 batteries, A2B2C2 batteries, A2B3C1 batteries and A2B3C2 batteries; the addition amount of the functional additive solution for the G1 batteries is 0.8-1.0 times the capacity value of the factory battery, the unit of the addition amount of the functional additive solution being g, and the unit of the capacity of the factory battery being Ah; the addition amount of the functional additive solution for the G2 batteries is 1.0-1.3 times the capacity value of the factory battery and not equal to 1.0 times, the unit of the addition amount of the functional additive solution being g, and the unit of the capacity of the factory battery being Ah; the addition amount of the functional additive solution for the G3 batteries is 1.3-1.6 times the capacity value of the factory battery and not equal to 1.3 times, the unit of the addition amount of the functional additive solution being g, and the unit of the capacity of the factory battery being Ah; and the addition amount of the functional additive solution for the G4 batteries is 1.6-1.8 times the capacity value of the factory battery and not equal to 1.6 times, the unit of the addition amount of the functional additive solution being g, and the unit of the capacity of the factory battery being Ah.

[0019] In some embodiments of the present application, the acid comprises HF; and / or, the first solvent comprises at least one of EC and EMC; and / or, the first film-forming additive comprises at least one of VC and FEC.

[0020] In some embodiments of the present application, in step (3), after the functional additive solution is added, the retired battery is placed at 30-45℃ for 10-24 h.

[0021] In some embodiments of the present application, in step (4), the retired battery is charged at a current less than or equal to 0.1C, and the cut-off capacity is 1% to 10% of the current capacity of the retired battery.

[0022] In some embodiments of the present application, after at least partially discharging the electrolyte and waste gas in the retired battery, and before adding the functional repair electrolyte into the retired battery, further comprising: adding an electrolyte solvent into the retired battery, and after standing for 12 to 18 hours at 45 to 55°C, discharging at least part of the flowing liquid in the retired battery.

[0023] In some embodiments of the present application, in step (6), the functional repair electrolyte comprises a second solvent, a lithium salt, and a second film-forming additive, the mass content of the lithium salt is 8% to 13%, and the mass content of the second film-forming additive is 0.4% to 6%, based on the total mass of the functional repair electrolyte.

[0024] In some embodiments of the present application, in step (6), the added amount of the functional repair electrolyte for the G1 battery is 0.5 times to 1.0 times the current capacity value of the retired battery, the unit of the added amount of the functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah; the added amount of the functional repair electrolyte for the G2 battery is 1.0 times to 1.5 times and not equal to 1.0 the current capacity value of the retired battery, the unit of the added amount of the functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah; the added amount of the functional repair electrolyte for the G3 battery is 1.5 times to 2.0 times and not equal to 1.5 the current capacity value of the retired battery, the unit of the added amount of the functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah; the added amount of the functional repair electrolyte for the G4 battery is 2.0 times to 2.8 times and not equal to 2.0 the current capacity value of the retired battery, the unit of the added amount of the functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah.

[0025] In some embodiments of the present application, the second solvent comprises at least one of EC and DMC; and / or, the second film-forming additive comprises at least one of VC and FEC.

[0026] In some embodiments of the present application, the aging is standing the retired battery for 12 to 48 hours; and the charging is charging the retired battery at a current less than or equal to 0.35C, and the cut-off capacity is 5% to 35% of the current capacity of the retired battery.

[0027] In a second aspect, the present application provides a lithium ion battery. According to an embodiment of the present application, the lithium ion battery is repaired by the performance repairing method described above. Thus, compared with the lithium ion battery before repair (i.e. the retired battery), the capacity expression and stability of the retired battery are greatly improved, the impedance of the retired battery is reduced, and the safety performance and cycle life performance of the retired battery are improved.

[0028] In a third aspect, the present application provides an electrical equipment. According to an embodiment of the present application, the electrical equipment has the lithium ion battery as above. Thus, the electrical equipment has all the advantages of the sodium ion lithium ion battery, which are not repeated here.

[0029] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0031] Figure 1 Flowchart of the performance repairing method of the lithium ion battery of the embodiment of the present application;

[0032] Figure 2 Charge-discharge curve of the retired battery 1 of Example 1 before and after repair;

[0033] Figure 3 Lifetime curve of the retired battery 1 of Example 1 before and after repair. DETAILED DESCRIPTION

[0034] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which like reference numerals indicate like elements or elements having the same or similar function throughout the several views. The embodiments described below are exemplary and are intended to explain the present application, and should not be understood as limiting the present application.

[0035] The inventors found that after a period of use, the metal impurities inside the raw materials of the lithium battery, especially the lithium iron phosphate battery, would precipitate and deposit on the surface of the negative electrode sheet. Therefore, the SEI layer at the negative electrode interface inside the lithium battery would continuously thicken under high temperature, cycling and other working conditions, causing the impedance to increase and affecting the safety performance of the battery. The prior art only adds lithium salt with single function, which can only improve the lithium concentration inside the battery and does not involve functional repair of the SEI layer, so the improvement of the battery performance is limited.

[0036] In view of this, in one aspect of the present application, a performance repair method of a lithium ion battery is provided. According to an embodiment of the present application, referring to the accompanying drawings Figure 1 The performance repair method comprises: S100: screening the retired batteries to screen repairable retired batteries; S200: performing specific discharge treatment on the repairable retired batteries; S300: performing exhaust on the retired batteries, adding a functional additive liquid, and the functional additive liquid comprising an acid; S400: charging the retired batteries; S500: at least partially discharging the electrolyte and waste gas in the retired batteries; S600: adding a functional repair electrolyte to the retired batteries; and S700: aging and formation. Thus, the present application first screens the retired batteries according to the capacity, gas production, and internal resistance of the retired batteries to screen repairable retired batteries. Then, the repairable retired batteries are subjected to specific discharge treatment to promote the decomposition of the SEI layer on the surface of the negative electrode sheet to a certain extent and reduce the thickness of the SEI layer, so as to facilitate the composition and structure of the SEI layer in the subsequent steps. Then, the retired batteries are subjected to negative pressure exhaust, and a functional additive liquid is added and left for a period of time. The functional additive liquid reacts with the metal layer on the surface of the negative electrode SEI film in the process to remove metal impurity deposits and form a dense LiF thin layer, thereby improving the uniformity of Li + flux capacity and inhibiting the growth of lithium crystals, while the composition and structure of the SEI film are repaired and restored in the first stage. Then, the electrolyte and waste gas in the retired batteries are discharged, a functional repair electrolyte is added to the retired batteries, and finally, the composition and structure of the SEI film are repaired and restored in the second stage, thereby constructing an electrode interface film with stable structure and excellent performance, effectively protecting the electrode surface, avoiding the precipitation of lithium dendrites, and ultimately achieving the performance repair of the retired batteries, greatly improving the capacity expression and stability of the retired batteries, reducing the impedance of the retired batteries, and improving the safety performance and cycle life performance of the retired batteries.

[0037] The principle of the performance repair method of the lithium ion battery according to the present application will be described in detail as follows:

[0038] Specifically, referring to the accompanying drawings Figure 1 The performance repair method comprises:

[0039] S100: screening the retired batteries

[0040] In this step, the retired batteries are classified and screened according to the capacity, gas production, and internal resistance of the retired batteries to screen repairable retired batteries.

[0041] Specifically, the retired batteries are graded according to the capacity of the retired batteries: the retired batteries with a current capacity of more than 60% of the factory capacity are A1 grade, the retired batteries with a current capacity of 40%-60% of the factory capacity and not equal to 60% are A2 grade, and the retired batteries with a current capacity of less than 40% of the factory capacity are directly scrapped.

[0042] The retired batteries are graded according to the thickness growth of the retired batteries: the retired batteries with a thickness growth of not more than 25% compared with the thickness of the factory batteries are B1 grade, the retired batteries with a thickness growth of more than 25% and not more than 35% compared with the thickness of the factory batteries are B2 grade, the retired batteries with a thickness growth of more than 35% and not more than 45% compared with the thickness of the factory batteries are B3 grade, and the retired batteries with a thickness growth of more than 45% compared with the thickness of the factory batteries are directly scrapped. The gas production of the retired batteries is reflected by the thickness growth of the retired batteries.

[0043] The retired batteries are graded according to the internal resistance of the retired batteries: the retired batteries with a direct current impedance of not more than 2.5 times of the direct current impedance of the factory batteries are C1 grade, the retired batteries with a direct current impedance of 2.5-3.5 times of the direct current impedance of the factory batteries and not equal to 2.5 times are C2 grade, and the retired batteries with a direct current impedance of more than 3.5 times of the direct current impedance of the factory batteries and not equal to 3.5 times are directly scrapped.

[0044] It should be noted that the current capacity of the retired batteries refers to the actual capacity of the repaired retired batteries before repair.

[0045] S200: performing specific discharge treatment on the repairable retired batteries

[0046] In this step, the repairable retired batteries graded are subjected to specific discharge treatment, which can effectively promote the decomposition of the SEI layer on the surface of the negative plate of the battery to a certain extent, reduce the thickness of the SEI layer, and facilitate the composition and structure of the SEI layer in the subsequent steps.

[0047] According to some specific embodiments of the present application, step S200 includes:

[0048] S210: first discharging the retired batteries to 2.0V;

[0049] Specifically, the retired batteries can be discharged at a constant current of 0.5C rate, and the cut-off voltage is 2.0V.

[0050] S220: then discharging the retired batteries to 0.8-1.5V, the discharge cut-off capacity is 2%-10% of the current capacity of the retired batteries, and the discharge current is less than or equal to 0.1C. After a period of time, the batteries with a voltage lower than 1.5V are screened out and directly scrapped.

[0051] S300: degassing the retired battery, and adding a functional additive liquid

[0052] In this step, after the rubber peg is pulled out through the battery liquid injection hole position, negative pressure degassing is performed, and in the dew point environment required by the battery, a functional additive liquid is added to react with the metal layer on the surface of the SEI film of the negative electrode of the battery, remove the metal impurity deposits, form a dense LiF thin layer, and restore and repair the composition and structure of the SEI film.

[0053] According to still some specific embodiments of the present application, the functional additive liquid comprises an acid, a first solvent and a first film-forming additive, the mass content of the acid is less than 0.5% and the mass content of the first film-forming additive is 0.5% to 3% based on the total mass of the functional additive liquid. By limiting the content of each component of the functional additive liquid within the above range, it is further beneficial to remove the metal impurity deposits, form a dense LiF thin layer, and restore and repair the composition and structure of the SEI film.

[0054] According to still some specific embodiments of the present application, the retired battery is first divided into G1 type batteries, G2 type batteries, G3 type batteries and G4 type batteries, the G1 type batteries comprise A1B1C1 grade batteries, A1B1C2 grade batteries and A1B2C1, the G2 type batteries comprise A1B2C2 grade batteries, A2B1C2 and A2B1C1 grade batteries, the G3 type batteries comprise A2B2C1 grade batteries and A1B3C1 grade batteries, and the G4 type batteries comprise A1B3C2 grade batteries, A2B2C2 grade batteries, A2B3C1 grade batteries and A2B3C2 grade batteries. It can be understood that the degree of loss of each type of battery is: G1 type batteries < G2 type batteries < G3 type batteries < G4 type batteries.

[0055] Then, different quality of the functional additive liquid is added according to different grades of the battery to be repaired, the more serious the loss degree of the retired battery is, the more the functional additive liquid is added, specifically, the added amount of the functional additive liquid of the G1 battery is 0.8-1.0 times of the capacity value of the factory battery, the unit of the added amount of the functional additive liquid is g, and the unit of the capacity of the factory battery is Ah; the added amount of the functional additive liquid of the G2 battery is 1.0-1.3 times of the capacity value of the factory battery and is not equal to 1.0 times, the unit of the added amount of the functional additive liquid is g, and the unit of the capacity of the factory battery is Ah; the added amount of the functional additive liquid of the G3 battery is 1.3-1.6 times of the capacity value of the factory battery and is not equal to 1.3 times, the unit of the added amount of the functional additive liquid is g, and the unit of the capacity of the factory battery is Ah; the added amount of the functional additive liquid of the G4 battery is 1.6-1.8 times of the capacity value of the factory battery and is not equal to 1.6 times, the unit of the added amount of the functional additive liquid is g, and the unit of the capacity of the factory battery is Ah. Thus, different quality of the functional additive liquid is added according to different grades of the battery to be repaired, that is, different quality of the functional additive liquid is added according to the loss degree of the battery to be repaired, which is more targeted and further helps to remove the metal impurity deposits and repair the SEI film composition and structure.

[0056] According to still some specific embodiments of the present application, the acid can include HF. And / or, the first solvent can include at least one of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), preferably a mixed solvent of EC and EMC. And / or, the first film-forming additive can include at least one of vinylene carbonate (VC) and fluoroethylene carbonate (FEC), preferably a combination of VC and FEC. As a preferred scheme, the functional additive liquid includes the EC / EMC solvent, 0.01wt%-0.5wt% of HF, 0.2wt%-2wt% of VC and 0.3wt%-1wt% of FEC. Thus, the metal impurity deposits can be further effectively removed and the SEI film composition and structure can be further repaired.

[0057] After the functional additive liquid is added, S300 further includes the following steps:

[0058] The retired battery is placed at 30-45℃ and is left for 10-24h for high-temperature soaking.

[0059] S400: charging the retired battery

[0060] In this step, the retired battery is charged at a current less than or equal to 0.1C, and the cut-off capacity is 1%-10% of the current capacity of the retired battery, so that the functional additive liquid can react with the metal layer on the surface of the negative electrode SEI film of the battery in this process, remove the metal impurity deposits, form a dense LiF thin layer, and improve the homogenization of Li +The flux capacity is improved and the growth of lithium crystals is inhibited, while the composition and structure of the SEI film are first-stage reformed and repaired.

[0061] S500: at least partially discharging electrolyte and waste gas in the retired battery

[0062] In this step, under the dew point environment required by the battery, vacuum is performed to discharge waste gas, dissolved impurities and flowable residual electrolyte.

[0063] According to some embodiments of the present application, after at least partially discharging electrolyte and waste gas in the retired battery, step S500 further comprises the following steps:

[0064] An electrolyte solvent (such as an EC solvent) is added to the retired battery, and after standing at 45-55°C for 12-18h, vacuum is performed to discharge at least part of the flowable liquid in the retired battery, so as to sufficiently discharge residual substances affecting battery performance.

[0065] S600: adding a functional repair electrolyte to the retired battery

[0066] In this step, different amounts of functional repair electrolyte are added according to G1, G2, G3 and G4 gears, which are used for second-stage reformation and repair of the composition and structure of the SEI film, and for constructing an electrode interface film with stable structure and excellent performance.

[0067] According to some embodiments of the present application, the functional repair electrolyte comprises a second solvent, a lithium salt and a second film-forming additive, and the mass content of the lithium salt can be 8-13% and the mass content of the second film-forming additive can be 0.4-6% based on the total mass of the functional repair electrolyte. According to still other embodiments of the present application, the second solvent can comprise at least one of ethylene carbonate (EC) and (DMC); and / or, the second film-forming additive can comprise at least one of vinylene carbonate (VC) and FEC. Thus, the reformation and repair of the composition and structure of the SEI film are further facilitated, and an electrode interface film with more stable structure and more excellent performance is constructed.

[0068] The lithium salt contained in the functional repair electrolyte can complete the balanced distribution of lithium concentration inside the electrode, improve the performance consistency of the battery cell during subsequent recombination, better promote the cascade utilization of the retired battery, and realize efficient and recyclable utilization of resources.

[0069] As before, the degree of loss of the retired battery in different gears is different, so different quality of functional repair electrolyte can be added according to G1, G2, G3, G4 gears, specifically, the addition amount of functional repair electrolyte of G1 battery is 0.5-1.0 times of the current capacity value of the retired battery, the unit of the addition amount of functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah; the addition amount of functional repair electrolyte of G2 battery is 1.0-1.5 times of the current capacity value of the retired battery and not equal to 1.0, the unit of the addition amount of functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah; the addition amount of functional repair electrolyte of G3 battery is 1.5-2.0 times of the current capacity value of the retired battery and not equal to 1.5, the unit of the addition amount of functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah; the addition amount of functional repair electrolyte of G4 battery is 2.0-2.8 times of the current capacity value of the retired battery and not equal to 2.0, the unit of the addition amount of functional repair electrolyte is g, and the unit of the current capacity of the retired battery is Ah. Thus, different quality of functional repair electrolyte is added according to the different gears of the battery to be repaired, that is, different quality of functional repair electrolyte is added according to the degree of loss of the battery to be repaired, which is more targeted and further helps to repair the SEI film composition and structure, and to build an electrode interface film with more stable structure and better performance.

[0070] S700: aging and formation

[0071] In this step, first, aging is performed, and the retired battery is left for 12-48 h; then, formation is performed, and the retired battery is charged at a current less than or equal to 0.35C, and the cut-off capacity is 5%-35% of the current capacity of the retired battery. This process performs the second stage of repair and repair of the SEI film composition and structure, and builds an electrode interface film with stable structure and excellent performance, thereby effectively protecting the electrode surface, avoiding the precipitation of lithium dendrites, greatly improving the capacity expression and stability of the retired battery, reducing the impedance of the retired battery, and improving the safety performance and cycle life performance of the retired battery.

[0072] The above completes the battery repair process.

[0073] In the second aspect of the present application, a lithium ion battery is provided. According to the embodiments of the present application, the lithium ion battery is repaired by the performance repair method described in the above embodiments. Thus, compared with the lithium ion battery before repair (i.e. the retired battery), the capacity expression and stability of the retired battery are greatly improved, the impedance of the retired battery is reduced, and the safety performance and cycle life performance of the retired battery are improved.

[0074] Specifically, the specific type of the above lithium ion battery is not particularly limited, and can be a lithium iron phosphate battery or other types of batteries. Especially for the repair effect of lithium iron phosphate-graphite system battery is better.

[0075] In a third aspect of the present application, the present application provides a power consuming device. According to embodiments of the present application, the power consuming device has the above lithium ion battery. Thus, the power consuming device has all the advantages of the lithium ion battery, which will not be repeated here.

[0076] Specifically, the above power consuming device can include but is not limited to mobile phones, tablets, laptops, electric toys, power tools, electric cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric plane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0077] The embodiments of the present application are described in detail below. It should be noted that the embodiments described below are exemplary and are used to explain the present application, and cannot be understood as a limitation of the present application. In addition, if not specifically stated, all reagents used in the following examples are commercially available or can be synthesized according to the methods described herein or known methods, and the reaction conditions not listed are also easily obtained by those skilled in the art.

[0078] Example 1

[0079] 1) According to the capacity, gas production, and internal resistance of the retired battery, retired batteries 1-8 were respectively graded and screened, wherein the factory capacity of retired battery 1 was 279.0738 Ah, the factory thickness was 49.8 mm, the factory battery direct current impedance was 0.52 mΩ, the actual capacity of retired battery 1 was 175.428 Ah, the actual thickness was 58.76 mm, and the actual battery direct current impedance was 0.858 mΩ; by calculation, retired battery 1 was A1B1C1 grade battery, which belonged to G1 type battery.

[0080] The factory capacity of retired battery 2 was 278.8432 Ah, the factory thickness was 50.00 mm, the factory battery direct current impedance was 0.53 mΩ, the actual capacity of retired battery 2 was 189.6134 Ah, the actual thickness was 64.00 mm, and the actual battery direct current impedance was 1.3356 mΩ; by calculation, retired battery 2 was A1B2C2 grade battery, which belonged to G2 type battery.

[0081] The factory capacity of the retired battery 3 is 277.0212 Ah, the factory thickness is 50.20 mm, the factory battery DC impedance is 0.51 mΩ, the actual capacity of the retired battery 3 is 160.6723 Ah, the actual thickness is 64.256 mm, and the actual battery DC impedance is 0.8415 mΩ; it is calculated that the retired battery 3 is an A2B2C1 battery, which belongs to a G3 battery.

[0082] The factory capacity of the retired battery 4 is 276.8188 Ah, the factory thickness is 49.9 mm, the factory battery DC impedance is 0.50 mΩ, the actual capacity of the retired battery 4 is 152.2504 Ah, the actual thickness is 63.872 mm, and the actual battery DC impedance is 1.305 mΩ; it is calculated that the retired battery 4 is an A2B2C2 battery, which belongs to a G4 battery.

[0083] The factory capacity of the retired battery 5 is 278.3469 Ah, the factory thickness is 49.8 mm, the factory battery DC impedance is 0.52 mΩ, the actual capacity of the retired battery 5 is 153.0908 Ah, the actual thickness is 64.74 mm, and the actual battery DC impedance is 1.04 mΩ; it is calculated that the retired battery 5 is an A2B1C1 battery, which belongs to a G2 battery.

[0084] The factory capacity of the retired battery 6 is 280.734 Ah, the factory thickness is 50.10 mm, the factory battery DC impedance is 0.53 mΩ, the actual capacity of the retired battery 6 is 179.6698 Ah, the actual thickness is 63.627 mm, and the actual battery DC impedance is 1.325 mΩ; it is calculated that the retired battery 6 is an A1B2C1 battery, which belongs to a G2 battery.

[0085] Next, the performance of the retired battery 1 is repaired:

[0086] 2) First, according to the requirements of the standard, the retired battery 1 is discharged to 2.0 V, and then the retired battery 1 is discharged to 0.8 V, the discharge cutoff capacity is 4% of the actual capacity of the retired battery 1, and the discharge current is equal to 0.08C. After a period of time, the batteries with a voltage lower than 1.5 V are selected and directly discarded.

[0087] 3) After the rubber nail is pulled out through the battery liquid injection hole position, negative pressure exhaust is performed, and in the required dew point environment of the battery, functional additive liquid is added, which includes EC / EMC solvent, 0.05wt% of HF, 1.1wt% of VC and 0.6wt% of FEC. The amount of functional additive liquid added is 0.9 times the capacity value of the factory battery, and the unit of the amount of functional additive liquid added is g, and the unit of the factory battery capacity is Ah.

[0088] 4) First, the retired battery 1 is placed at 33°C, and left for 24h, high temperature soaking; then the retired battery 1 is charged at 0.08C current, and the cut-off capacity is 2% of the actual capacity of the retired battery 1.

[0089] 5) In the dew point environment required by the battery, vacuum is performed to discharge waste gas, dissolved impurities and flowable residual electrolyte.

[0090] 6) The electrolyte solvent EC is added to the retired battery, and after being left at 45°C for 18h, vacuum is performed to discharge the flowable liquid in the retired battery.

[0091] 7) The functional repair electrolyte is added to the retired battery 1, and the functional repair electrolyte includes EC / DMC solvent, 10.0wt% lithium salt, 1.5wt% VC and 1.5wt% FEC. The added amount of the functional repair electrolyte is 0.7 times the actual capacity value of the retired battery 1, and the unit of the added amount of the functional repair electrolyte is g, and the unit of the current capacity of the retired battery 1 is Ah.

[0092] 8) First, the retired battery 1 is left for 18h for aging; then the retired battery 1 is charged at 0.25C current, and the cut-off capacity is 10% of the actual capacity of the retired battery 1.

[0093] Example 2

[0094] In this embodiment, the performance of the retired battery 2 is repaired:

[0095] 2) First, the retired battery 2 is discharged to 2.0V according to the requirements of the national standard, and then the retired battery 2 is discharged to 1.2V, and the discharge cut-off capacity is 6% of the actual capacity of the retired battery 2, and the discharge current is equal to 0.1C. After a period of time, the batteries with voltage lower than 1.5V are selected and directly scrapped.

[0096] 3) After the rubber peg is pulled out through the battery filling hole position, negative pressure exhaust is performed, and the functional additive liquid is added in the dew point environment required by the battery, and the functional additive liquid includes EC / EMC solvent, 0.05wt% HF, 1.1wt% VC and 0.6wt% FEC. The added amount of the functional additive liquid is 1.2 times the capacity value of the factory battery, and the unit of the added amount of the functional additive liquid is g, and the unit of the factory battery capacity is Ah.

[0097] 4) First, the retired battery 2 is placed at 38°C, and left for 17h, high temperature soaking; then the retired battery 2 is charged at 0.1C current, and the cut-off capacity is 5% of the actual capacity of the retired battery 2.

[0098] 5) In the dew point environment required by the battery, vacuum is performed to discharge waste gas, dissolved impurities and flowable residual electrolyte.

[0099] 6) Add electrolyte solvent EC to the retired battery, and after standing at 50°C for 16 h, perform vacuum extraction to remove the flowable liquid in the retired battery.

[0100] 7) Add functional repair electrolyte to the retired battery 2, the functional repair electrolyte comprising EC / DMC solvent, 10.0 wt% lithium salt, 1.5 wt% VC, and 1.5 wt% FEC. The added amount of the functional repair electrolyte is 1.2 times the actual capacity value of the retired battery 2, the added amount of the functional repair electrolyte being in g, and the current capacity of the retired battery 2 being in Ah.

[0101] 8) First, perform aging by standing the retired battery 2 for 24 h; then perform formation by charging the retired battery 2 at a current of 0.35C, and the cutoff capacity is 20% of the actual capacity of the retired battery 2.

[0102] Example 3

[0103] In this example, the performance of the retired battery 3 is repaired.

[0104] 2) First, discharge the retired battery 3 to 2.0 V according to the requirements of the national standard, and then discharge the retired battery 3 to 1.5 V, the discharge cutoff capacity being 8% of the actual capacity of the retired battery 3, and the discharge current being equal to 0.05C. After standing for a period of time, the batteries with a voltage lower than 1.5 V are selected and directly discarded.

[0105] 3) Perform negative pressure exhaust by pulling out the rubber peg at the position of the battery liquid injection hole, and in the dew point environment required by the battery, add functional additive liquid, the functional additive liquid comprising EC / EMC solvent, 0.05 wt% HF, 1.1 wt% VC, and 0.6 wt% FEC. The added amount of the functional additive liquid is 1.45 times the capacity value of the factory battery, the added amount of the functional additive liquid being in g, and the capacity of the factory battery being in Ah.

[0106] 4) First, immerse the retired battery 3 in 43°C for 12 h for high-temperature soaking; then charge the retired battery 3 at a current of 0.05C, and the cutoff capacity is 8% of the actual capacity of the retired battery 3.

[0107] 5) Perform vacuum extraction in the dew point environment required by the battery to remove waste gas, dissolved impurities, and flowable residual electrolyte.

[0108] 6) Add electrolyte solvent EC to the retired battery, and after standing at 55°C for 12 h, perform vacuum extraction to remove the flowable liquid in the retired battery.

[0109] 7) Functional repair electrolyte is added to the retired battery 3, the functional repair electrolyte including EC / DMC solvent, 10.0wt% lithium salt, 1.5wt% VC and 1.5wt% FEC. The added amount of the functional repair electrolyte is 1.8 times of the actual capacity value of the retired battery 3, the added amount of the functional repair electrolyte being in g, and the current capacity of the retired battery 3 being in Ah.

[0110] 8) First, aging is performed, and the retired battery 3 is placed for 40h; then, formation is performed, and the retired battery 3 is charged at a current of 0.15C, and the cut-off capacity is 30% of the actual capacity of the retired battery 3.

[0111] Example 4

[0112] In this example, performance repair is performed on the retired battery 4:

[0113] 2) First, the retired battery 4 is discharged to 2.0V according to the requirements of the national standard, and then the retired battery 4 is discharged to 1.2V, the discharge cut-off capacity being 6% of the actual capacity of the retired battery 4, and the discharge current being equal to 0.1C. After being placed for a period of time, the batteries with a voltage lower than 1.5V are selected and directly discarded.

[0114] 3) After the rubber pegs are pulled out through the battery liquid injection hole position, negative pressure exhaust is performed, and in the dew point environment required by the battery, functional additive liquid is added, the functional additive liquid including EC / EMC solvent, 0.05wt% HF, 1.1wt% VC and 0.6wt% FEC. The added amount of the functional additive liquid is 1.7 times of the capacity value of the factory battery, the added amount of the functional additive liquid being in g, and the capacity of the factory battery being in Ah.

[0115] 4) First, the retired battery 4 is placed at 38℃ for 17h for high-temperature soaking; then, the retired battery 4 is charged at a current equal to 0.1C, and the cut-off capacity is 5% of the actual capacity of the retired battery 4.

[0116] 5) In the dew point environment required by the battery, vacuum is drawn to discharge waste gas, dissolved impurities and flowable residual electrolyte.

[0117] 6) Electrolyte solvent EC is added to the retired battery, and after being placed at 50℃ for 16h, vacuum is drawn to discharge the flowable liquid in the retired battery.

[0118] 7) Functional repair electrolyte is added to the retired battery 4, the functional repair electrolyte including EC / DMC solvent, 10.0wt% lithium salt, 1.5wt% VC and 1.5wt% FEC. The added amount of the functional repair electrolyte is 2.4 times of the actual capacity value of the retired battery 4, the added amount of the functional repair electrolyte being in g, and the current capacity of the retired battery 4 being in Ah.

[0119] 8) First, the retired battery 4 is aged for 24 hours; then, the formation is carried out, the retired battery 4 is charged at a current equal to 0.35C, and the cut-off capacity is 20% of the actual capacity of the retired battery 4.

[0120] Example 5

[0121] In this example, the performance of the retired battery 5 is repaired, and the difference between this example and Example 2 is only that:

[0122] 3) The functional additive solution includes EC / EMC solvent, 0.15wt% HF, 1.5wt% VC, and 0.3wt% FEC.

[0123] 7) The functional repair electrolyte includes EC / DMC solvent, 13wt% lithium salt, 1.0wt% VC, and 2.0wt% FEC.

[0124] The other contents are the same as those in Example 2.

[0125] Example 6

[0126] In this example, the performance of the retired battery 6 is repaired, and the difference between this example and Example 2 is only that:

[0127] 3) The functional additive solution includes EC / EMC solvent, 0.3wt% HF, 0.5wt% VC, and 1wt% FEC.

[0128] 7) The functional repair electrolyte includes EC / DMC solvent, 8wt% lithium salt, 2.0wt% VC, and 1.0wt% FEC.

[0129] The other contents are the same as those in Example 2.

[0130] The DC impedance and capacity values of the batteries repaired in Examples 1-6 are tested respectively, and the results are shown in Table 1.

[0131] Table 1

[0132]

[0133] As can be seen from Table 1, compared with the DC impedance of the battery before repair, the impedance of the modified battery is reduced to a certain extent; compared with the capacity of the battery before repair, the capacity of the modified battery is improved to a certain extent.

[0134] Figure 2 the charge-discharge curve of the retired battery 1 of Example 1 before and after repair, Figure 3 the life curve of the retired battery 1 of Example 1 before and after repair, from Figure 2 As can be seen from the above, the capacity of the modified battery is improved to a certain extent, and the polarization impedance shown by the curve is reduced, fromFigure 3 As can be seen, the modified battery life is significantly improved compared to the battery life before repair.

[0135] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0136] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for repairing the performance of a lithium-ion battery, characterized in that: include: (1) Screening retired batteries to identify repairable retired batteries; (2) Performing a specific discharge treatment on the repairable retired battery, including: (2-1) discharging the retired battery to 2.0V; (2-2) discharging the retired battery to 0.8V~1.5V, with the discharge cut-off capacity being 2%~10% of the current capacity of the retired battery, and the discharge current being less than or equal to 0.1C; (3) exhausting the retired battery and adding a functional additive liquid, wherein the functional additive liquid comprises an acid, a first solvent, and a first film-forming additive, wherein the mass content of the acid is less than 0.5% and the mass content of the first film-forming additive is 0.5% to 3% based on the total mass of the functional additive liquid; (4) charging the retired battery at a current of less than or equal to 0.1C, with a cutoff capacity of 1% to 10% of the current capacity of the retired battery; (5) discharging at least part of the electrolyte and waste gas from the retired battery; (6) adding a functional repair electrolyte to the retired battery, wherein the functional repair electrolyte comprises a second solvent, a lithium salt, and a second film-forming additive, wherein the mass content of the lithium salt is 8% to 13% and the mass content of the second film-forming additive is 0.4% to 6% based on the total mass of the functional repair electrolyte; (7) To age and become.

2. The performance repair method according to claim 1, characterized in that: In step (1), the retired batteries are graded and screened according to their capacity, gas production, and internal resistance; A1 is the rating for retired batteries with a current capacity of more than 60% of the factory capacity, A2 is the rating for retired batteries with a current capacity of 40% to 60% but not equal to 60% of the factory capacity; and retired batteries with a current capacity less than 40% of the factory capacity are scrapped. Compared with the thickness of the factory-made battery, the thickness of the retired battery increases by no more than 25%, which is the B1 level; compared with the thickness of the factory-made battery, the thickness of the retired battery increases by more than 25% but no more than 35%, which is the B2 level; compared with the thickness of the factory-made battery, the thickness of the retired battery increases by more than 35% but no more than 45%, which is the B3 level; compared with the thickness of the factory-made battery, the thickness of the retired battery increases by more than 45%, it is scrapped; If the DC impedance of the retired battery is within 2.5 times of the DC impedance of the factory battery, it is in C1 grade; if the DC impedance of the retired battery is 2.5 to 3.5 times of the DC impedance of the factory battery but not equal to 2.5 times, it is in C2 grade; if the DC impedance of the retired battery is more than 3.5 times but not equal to 3.5 times of the DC impedance of the factory battery, it is scrapped.

3. The performance repair method according to claim 2, characterized in that: In step (3), the retired batteries are divided into G1 batteries, G2 batteries, G3 batteries and G4 batteries, the G1 batteries include A1B1C1 batteries, A1B1C2 batteries and A1B2C1 batteries, the G2 batteries include A1B2C2 batteries, A2B1C2 and A2B1C1 batteries, the G3 batteries include A2B2C1 batteries and A1B3C1 batteries, and the G4 batteries include A1B3C2 batteries, A2B2C2 batteries, A2B3C1 batteries and A2B3C2 batteries; The amount of the functional additive liquid added to the G1 battery is 0.8 to 1.0 times the capacity of the factory-made battery. The unit of the amount of the functional additive liquid added is g, and the unit of the factory-made battery capacity is Ah. The amount of the functional additive liquid added to the G2 battery is 1.0 times to 1.3 times the capacity of the factory-made battery and is not equal to 1.0 times. The unit of the amount of the functional additive liquid added is g, and the unit of the factory-made battery capacity is Ah; The amount of the functional additive liquid added to the G3 battery is 1.3 times to 1.6 times the capacity of the factory battery and is not equal to 1.3 times. The unit of the amount of the functional additive liquid added is g, and the unit of the factory battery capacity is Ah; The amount of the functional additive liquid added to the G4 battery is 1.6 times to 1.8 times the capacity value of the factory battery and is not equal to 1.6 times. The unit of the amount of the functional additive liquid added is g, and the unit of the factory battery capacity is Ah.

4. The performance repair method according to claim 2, characterized in that: The acid comprises HF; and / or, the first solvent comprises at least one of EC and EMC; And / or, the first film-forming additive includes at least one of VC and FEC.

5. The performance repair method according to any one of claims 1 to 4, characterized in that: In step (3), after adding the functional additive solution, the retired battery is placed at 30°C to 45°C and left for 10 hours to 24 hours.

6. The performance repair method according to any one of claims 1 to 4, characterized in that: After at least partially discharging the electrolyte and waste gas from the retired battery and before adding the function repair electrolyte to the retired battery, the method further includes: An electrolyte solvent is added to the retired battery, and after standing at 45° C. to 55° C. for 12 to 18 hours, at least part of the flowing liquid in the retired battery is discharged.

7. The performance repair method according to claim 3, characterized in that: In step (6), the amount of the functional repair electrolyte added to the G1 battery is 0.5 times to 1.0 times the current capacity value of the retired battery, the unit of the amount of the functional repair electrolyte added is g, and the unit of the current capacity of the retired battery is Ah; The amount of the functional repair electrolyte added to the G2 battery is 1.0 to 1.5 times the current capacity of the retired battery and is not equal to 1.

0. The unit of the amount of the functional repair electrolyte added is g, and the unit of the current capacity of the retired battery is Ah; The amount of the functional repair electrolyte added to the G3 battery is 1.5 times to 2.0 times the current capacity of the retired battery and is not equal to 1.

5. The unit of the amount of the functional repair electrolyte added is g, and the unit of the current capacity of the retired battery is Ah; The amount of the functional repair electrolyte added to the G4 battery is 2.0 times to 2.8 times the current capacity value of the retired battery and is not equal to 2.

0. The unit of the amount of the functional repair electrolyte added is g, and the unit of the current capacity of the retired battery is Ah.

8. The performance repair method according to any one of claims 1 to 4, characterized in that: The second solvent comprises at least one of EC and DMC; And / or, the second film-forming additive includes at least one of VC and FEC.

9. The performance repair method according to any one of claims 1 to 4, characterized in that: The aging step comprises: placing the retired battery aside for 12 to 48 hours; The charging step is as follows: charging the retired battery at a current of less than or equal to 0.35C, with a cutoff capacity of 5% to 35% of the current capacity of the retired battery.

10. A lithium ion battery, characterized in that: Repaired using the performance repair method described in any one of claims 1 to 9.

11. An electrical device, characterized in that: Including the lithium ion battery according to claim 10.

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