Battery regeneration method and regeneration liquid

Abstract

The application relates to a battery regeneration method and a regeneration liquid. The battery regeneration method comprises the following steps: S1, perforating a battery to be retired and injecting a regeneration liquid; and S2, sealing and standing for more than 36 hours. The battery to be retired is a lithium ion battery, the adding amount of the regeneration liquid is 0.3-1.1 g / Ah. The regeneration method provided by the application can activate the battery capacity and prolong the service life by simply injecting the regeneration liquid, does not produce gas, does not damage the battery structure, maintains the safety of the battery, is environment-friendly, the composition of the regeneration liquid is simple, the lithium salt and the organic solvent used are common upstream products in the battery industry, the preparation process is mature, the cost is low, and the regeneration liquid is beneficial to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a battery regeneration method and regeneration solution. Background Technology

[0002] The new energy vehicle and energy storage markets have experienced rapid growth, driving a significant increase in demand for power batteries. However, after a period of use, when the capacity of power batteries decreases by more than 20%, their performance will decline sharply, specifically manifested as increased internal resistance, capacity decline, and increased safety risks, necessitating retirement. A wave of retirements is already gradually emerging.

[0003] Currently, the recycling and reuse of retired lithium batteries mainly falls into two categories: secondary use and dismantling recycling. Secondary use involves applying batteries that still have usable value to energy storage systems, low-speed electric vehicles, or electric bicycles, where battery performance requirements are relatively low. However, this process requires high battery consistency, detailed testing and classification of batteries to be retired, resulting in high costs, insufficient automation, and an imbalance between market supply and demand. Consequently, few companies actually adopt this approach, and its development is still immature. In contrast, dismantling recycling utilizes hydrometallurgy, pyrometallurgy, and physical dismantling techniques to effectively recover valuable elements such as lithium, phosphorus, iron, cobalt, nickel, and manganese from the batteries, making it the mainstream recycling method. However, the dismantling process may pose safety risks and requires complex physical and chemical treatments. While it improves resource utilization compared to direct disposal, it also presents challenges such as high costs, high energy consumption, and environmental pollution.

[0004] CN108574124A discloses a method for recycling lithium-ion batteries and a lithium-ion battery prepared using this method. However, this paper requires the extraction of the electrolyte using supercritical fluid before adding it, which is a complex process.

[0005] In conclusion, there is currently no effective recycling method for retired power batteries that simultaneously meets the requirements of environmental protection, economic efficiency, and resource sustainability. New methods are urgently needed to address the key issues facing the industry. Summary of the Invention

[0006] To address the shortcomings of existing technologies for recycling batteries awaiting retirement, this invention proposes a battery regeneration method and a regeneration solution.

[0007] One object of the present invention is to provide a battery regeneration method.

[0008] Another object of the present invention is to provide a regeneration solution for the method described herein.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A battery regeneration method includes the following steps:

[0011] S1: Drill holes in the batteries to be retired and inject regeneration fluid;

[0012] S2: After vacuuming, seal and let stand for more than 36 hours;

[0013] The batteries to be decommissioned are lithium-ion batteries.

[0014] The amount of the regenerated liquid added is 0.3 to 1.1 g / Ah, preferably 0.5 to 0.8 g / Ah, and more preferably 0.5 to 0.7 g / Ah.

[0015] According to one embodiment of the present invention, the positive electrode material of the lithium-ion battery is lithium iron phosphate, ternary layered oxide, lithium-rich manganese-based material, or lithium cobalt oxide, etc., the negative electrode material is graphite, hard carbon, or silicon / carbon composite material, etc., and the electrolyte is a commercial electrolyte in which lithium hexafluorophosphate is dissolved in a mixed carbonate organic solvent and a small amount of additives are added, with a concentration typically of 1 mol / L.

[0016] The electrolyte can be a commercially available electrolyte, such as 1.0M LiPF6 / EC:DEC+5%FEC (product number LB-015) purchased from Duoduo Chemical.

[0017] According to one embodiment of the present invention, the capacity of the battery to be retired is 70% to 90% of its initial rated capacity, preferably 80%.

[0018] According to one embodiment of the present invention, the battery regeneration solution comprises lithium salt and organic solvent.

[0019] According to another aspect of the present invention, a battery regeneration solution is provided, characterized in that the regeneration solution contains a solute and a solvent; the solute is a lithium salt; the solvent is an organic reagent; and the molar ratio of the solute to the solvent is 1:5 to 1:200, preferably 1:15 to 1:50.

[0020] Furthermore, the lithium salt is selected from any one or more of lithium phosphates, borates, boron group cluster compounds, imine salts, aluminates, heterocyclic anionic salts, halide salts, sulfonates and their derivatives, mixed in any proportion.

[0021] Furthermore, the lithium salt is selected from any one or more of lithium trifluoromethanesulfonylimide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), and lithium perchlorate (LiClO4) in any proportion.

[0022] Furthermore, the solvent is selected from any one or more of esters, nitriles, sulfones, and their derivatives, mixed in any proportion.

[0023] Furthermore, the solvent is selected from any one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl methyl carbonate (EMC), ethylene carbonate (EC), methyl propionate (MP), trimethyl borate (TMB), ethyl acetate (EA), ethylene sulfite (ES), acetonitrile (AN), adiponitrile (HN), and sulfolane (SUL) in any proportion.

[0024] According to one embodiment of the present invention, the solute in the battery regeneration solution is LiPF6, and the solvent is one or a mixture of two selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), sulfolane (SUL), ethylene sulfite (ES), acetonitrile (AN), adiponitrile (HN), methyl propionate (MP), ethyl acetate (EA), and trimethyl borate (TMB).

[0025] According to one embodiment of the present invention, when the solvent is a mixture of two solvents, the mixing ratio is any molar ratio, preferably 1:10 to 10:1, more preferably 1:1.5 to 1.5:1.

[0026] According to one embodiment of the present invention, the solute in the battery regeneration solution is lithium hexafluorophosphate (LiPF6), and the solvent is dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), sulfolane (SUL), ethylene sulfite (ES), acetonitrile (AN), adiponitrile (HN), methyl propionate (MP), ethyl acetate (EA), trimethyl borate (TMB), a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC), a mixture of dimethyl carbonate (DMC) and ethylene carbonate (EC), a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC), or a mixture of acetonitrile (AN) and ethylene carbonate (EC), wherein the molar ratio of the mixtures is arbitrary, preferably 1:10 to 10:1, more preferably 1:1.5 to 1.5:1.

[0027] According to one embodiment of the present invention, the solvent in the battery regeneration solution is dimethyl carbonate (DMC), and the solute is one or a mixture of two selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium trifluoromethanesulfonate (LiOTf).

[0028] According to one embodiment of the present invention, when the solvent is a mixture of two solvents, the mixing ratio is any molar ratio, preferably 1:10 to 10:1, more preferably 1:1.5 to 1.5:1.

[0029] According to one embodiment of the present invention, the solvent in the battery regeneration solution is dimethyl carbonate (DMC), and the solute is selected from lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiOTf), a mixture of lithium hexafluorophosphate (LiPF6) and lithium tetrafluoroborate (LiBF4), and lithium hexafluorophosphate (Li... Mixtures of lithium hexafluorophosphate (LiPF6) and lithium difluorooxalate borate (LiDFOB), mixtures of lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI), mixtures of lithium hexafluorophosphate (LiPF6) and lithium bis(fluoromethanesulfonyl)imide (LiTFSI), mixtures of lithium hexafluorophosphate (LiPF6) and lithium trifluoromethanesulfonate (LiOTf), mixtures of lithium tetrafluoroborate (LiBF4) and lithium difluorooxalate borate (LiDFOB), and mixtures of lithium tetrafluoroborate (LiBF4) and lithium bis(fluorosulfonyl)imide (LiTFSI). Mixtures of lithium imide (LiFSI), mixtures of lithium tetrafluoroborate (LiBF4) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI), mixtures of lithium tetrafluoroborate (LiBF4) and lithium trifluoromethanesulfonate (LiOTf), mixtures of lithium difluorooxalate borate (LiDFOB) and lithium bis(trifluoromethanesulfonylimide) (LiFSI), mixtures of lithium difluorooxalate borate (LiDFOB) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI ... bis(trifluoromethanesulfonylimide) (LiTFSI) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI), mixtures of lithium difluorooxalate borate (LiDFOB) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI), mixtures of lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI), mixtures of lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI), mixtures of lithium bis(trifluoromethanesulfonylimide) (LiTFSI) and The mixtures are: a mixture of lithium fluoromethanesulfonate (LiOTf), a mixture of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a mixture of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium trifluoromethanesulfonate (LiOTf), or a mixture of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium trifluoromethanesulfonate (LiOTf), wherein the molar ratio of the mixtures is arbitrary, preferably 1:10 to 10:1, more preferably 1:1.5 to 1.5:1.

[0030] Beneficial effects

[0031] The regeneration method provided by this invention activates battery capacity and extends battery life through simple operation by injecting a regenerating solution. It does not generate gas, does not damage the battery structure, maintains battery safety, and is environmentally friendly. The regenerating solution provided by this invention has a simple composition; the lithium salt and organic solvent used are common upstream products in the battery industry. The preparation process is mature, low-cost, and conducive to large-scale production. Attached Figure Description

[0032] Figure 1 This is a schematic diagram showing the cycle life of batteries to be retired after being treated in different ways according to the methods of Comparative Examples 1 to 3.

[0033] Figure 2 The graph shows the lifespan extension rate after injecting regenerants with different salt / solvent molar ratios according to Examples 1 to 7, as a result of the salt / solvent molar ratio.

[0034] Figure 3 The graph shows the lifespan extension rate versus the amount of regenerated liquid added after adding different amounts (0.3–1.1 g / Ah) of regenerated liquid according to Examples 8 to 12.

[0035] Figure 4 The diagram shows the regeneration effect of batteries injected with regenerable fluid when the batteries have decayed to different levels (90-60%) according to Examples 13 to 16.

[0036] Figure 5 The graph shows the life extension effect of adding regenerable fluid to the batteries of different specifications (0.2Ah, 1Ah) to be retired in Examples 50 and 51.

[0037] Figure 6 The figure shows the liquid replenishment effect of the batteries to be decommissioned, in Example 52 and Comparative Example 20, where the cathode material is a ternary layered oxide system.

[0038] Figure 7 and Figure 8 The figures show the safety test results for Examples 53 and 54.

[0039] Figure 9 The ultrasonic test results show the wettability of the battery after replenishment in Example 55.

[0040] Figure 10 This is a schematic diagram showing the method of the present invention, and a graph showing the capacity retention rate versus normalized lifetime after regeneration and repair according to the present invention, based on continuous testing according to the prior art. Detailed Implementation

[0041] The present invention will become clearer from the following detailed description with reference to the accompanying drawings and preferred embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0042] Unless otherwise specified, all raw materials used in this invention were purchased from Suzhou Duoduo Chemical Technology Co., Ltd., the dry cell batteries were purchased from Hunan Lifang New Energy Technology Co., Ltd., and the instrument used was the CT-4008-5V6A battery charge / discharge tester from Shenzhen Xinwei Electronics Co., Ltd. The abbreviations used have the following meanings:

[0043] EC: Ethylene carbonate; DEC: Diethyl carbonate; FEC: Fluorinated ethylene carbonate; DMC: Dimethyl carbonate; EMC: Ethyl methyl carbonate; SUL: Sulfolane; ES: Ethyl sulfite; AN: Acetonitrile; HN: Adiponitrile; MP: Methyl propionate; TMB: Trimethyl borate; EA: Ethyl acetate; PC: Propylene carbonate; DME: Dimethyl glycol ether; G3: Triethylene glycol dimethyl ether; G4: Tetraethylene glycol dimethyl ether; THF: Tetrahydrofuran; DOL: 1,3-Dioxolane; D MSO: Dimethyl sulfoxide; TMP: Trimethyl phosphate; TEP: Triethyl phosphate; DMF: N,N-dimethylformamide; NMP: N-methylpyrrolidone; TEB: Triethyl borate; LiPF6: Lithium hexafluorophosphate; LiBF4: Lithium tetrafluoroborate; LiDFOB: Lithium difluorooxalate borate; LiFSI: Lithium bis(fluorosulfonyl)imide; LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide; LiOTf: Lithium trifluoromethanesulfonate; LFP: Lithium iron phosphate; Gr: Graphite; Std: 1.0M LiPF6 / EC:DEC+5%FEC.

[0044] Comparative Example 1

[0045] To cycle the battery continuously until its performance degrades, follow these steps:

[0046] S1: Battery Cycling. A commercial lithium-ion battery (LFP / Gr, 200mAh, purchased from Hunan Lifang New Energy Technology Co., Ltd., hereinafter the same) was used. Its positive electrode was lithium iron phosphate (LFP), the negative electrode was graphite (Gr), and the electrolyte was 1.0M LiPF6 / EC:DEC+5% FEC (purchased from Duoduo Chemical), denoted as Std. The addition amount was E / C = 5.3g / Ah. For ease of comparison, normalized lifespan (NCL) was used to represent the battery's cycle performance. NCL is calculated as the actual number of cycles divided by the number of cycles at 80% capacity decay. That is, NCL at 80% capacity decay is 1. The LFP / Gr battery was charged and discharged at a 2C rate until the normalized lifespan reached 2.0, at which point its capacity decayed to 9.6% of its initial capacity.

[0047] Comparative Example 2

[0048] After the retired batteries have been stored and processed, continue the recycling process by following these steps:

[0049] S1: Battery Pre-Cycling. A commercial lithium-ion battery (LFP / Gr) with lithium iron phosphate (LFP) as the positive electrode, graphite (Gr) as the negative electrode, and Std electrolyte as the electrolyte, with an electrolyte addition rate of E / C = 5.3 g / Ah. The LFP / Gr battery was subjected to charge-discharge cycle testing at a 2C rate until NCL = 1, at which point the battery was deemed ready for retirement.

[0050] S2: Batteries to be retired should be left to stand for 48 hours under open-circuit voltage conditions.

[0051] S3: After the LFP / Gr battery has been left to stand, it is subjected to charge-discharge cycle test at a 2C rate to monitor capacity changes until it decays to 80% of its initial capacity again. The life extension rate is calculated as the number of cycles after the battery has been left to stand and decays to 80% again / the number of cycles after the battery has decayed to 80% during the first run * 100%.

[0052] Comparative Example 3

[0053] To repair batteries awaiting retirement using commercial electrolyte std, follow these steps:

[0054] S1: Battery Pre-Cycling. A commercial lithium-ion battery (LFP / Gr) with lithium iron phosphate (LFP) as the positive electrode, graphite (Gr) as the negative electrode, and Std electrolyte as the electrolyte, with an electrolyte addition rate of E / C = 5.3 g / Ah. The LFP / Gr battery was subjected to charge-discharge cycle testing at a 2C rate until NCL = 1, at which point the battery was deemed ready for retirement.

[0055] S2: Regeneration treatment of batteries to be retired. Take the LFP / Gr batteries to be retired obtained in S1, inject commercial electrolyte Std at a dosage of 0.3 g / Ah, seal and let stand for 48 hours.

[0056] S3: After replenishing with commercial electrolyte, the LFP / Gr battery was subjected to charge-discharge cycle testing at a 2C rate to monitor capacity changes until it decayed to 80% of its initial capacity again. The life extension rate was calculated as the number of cycles after replenishment and decay to 80% / the number of cycles during the initial operation and decay to 80% * 100%.

[0057] Each comparative example used five identical batteries for testing, and the results were relatively consistent. Data from one battery in each comparative example was plotted. Figure 1 The figure shows the difference in cycle life after different treatments for LFP / Gr batteries that have reached 80% capacity and are considered retired. It can be seen that without any treatment, continuing to cycle at a 2C rate results in a rapid decline in battery capacity, making it difficult to meet the capacity requirements of equipment. This is the main reason why batteries need to be retired prematurely when they still retain 80% of their capacity. This invention compares different methods of treating batteries to be retired and finds that:

[0058] 1. After a 48-hour resting period, the capacity of a battery awaiting retirement was restored to approximately 81.5% of its initial capacity. This may be due to polarization, where lithium ions reach the cutoff voltage before migrating to the electrode surface, leading to capacity loss. After a period of rest, lithium ions have sufficient time to slowly diffuse to the electrode surface, eliminating polarization and allowing for partial capacity recovery. However, the capacity recovered during the resting process is very limited and will quickly decay back to 80%, resulting in a lifespan extension of only about 5%.

[0059] 2. After injecting Std electrolyte into batteries awaiting retirement and performing charge-discharge cycles, the capacity recovered to approximately 84.7% of the initial capacity, but the lifespan extension was only about 5%. This suggests that introducing active lithium ions helps with capacity recovery. However, the Std electrolyte composition is too complex, containing multiple film-forming components, which can easily lead to side reactions and form a thick interface on the negative electrode surface, hindering lithium ion migration. Therefore, the composition of the regenerated electrolyte needs to be redesigned.

[0060] Examples 1-7

[0061] A regeneration solution was prepared using lithium hexafluorophosphate (LiPF6) as the salt and dimethyl carbonate (DMC) as the solvent for the repair of batteries awaiting retirement. The procedure is as follows:

[0062] S1: Battery Pre-Cycling. A commercial lithium-ion battery (LFP / Gr, 200mAh, purchased from Hunan Lifang New Energy Technology Co., Ltd., hereinafter the same) was used. Its positive electrode was lithium iron phosphate (LFP), the negative electrode was graphite (Gr), and the electrolyte was Std, with an addition amount of E / C = 5.3g / Ah. The LFP / Gr battery was subjected to charge-discharge cycle testing at a 2C rate until NCL = 1, at which point the battery was deemed ready for retirement.

[0063] S2: Preparation of regenerated solution. Lithium hexafluorophosphate (LiPF6) was used as the salt and dimethyl carbonate (DMC) as the solvent. The preparation method was as follows: LiPF6 and DMC were mixed uniformly at molar ratios of 1:5, 1:7, 1:10, 1:15, 1:50, 1:100, and 1:200, respectively, corresponding to Examples 1, 2, 3, 4, 5, 6, and 7.

[0064] S3: Regeneration treatment of batteries to be retired. Take the LFP / Gr batteries to be retired obtained in S1 and inject them into the regeneration solution prepared in S2. Five batteries to be retired are repaired with the regeneration solution with the same salt / solvent molar ratio. After vacuum sealing, the content of the regeneration solution is 0.2-0.4 g / Ah. After sealing, let stand for 48 hours.

[0065] S4: After resting, the LFP / Gr battery is subjected to a charge-discharge cycle test at a 2C rate, and capacity changes are monitored until it decays back to 80% of its initial capacity. The lifespan extension rate is calculated as: (Number of cycles after replenishment and decay back to 80% / Number of cycles during initial operation and decay to 80%) * 100%.

[0066] Comparative Example 4

[0067] Except for modifying the salt / solvent molar ratio of the regenerated solution to 1:2.5, the batteries to be decommissioned were repaired in the same manner as in Examples 1 to 7, and the life extension rate was calculated.

[0068] The capacity retention-normalized lifetime results for Examples 1-7 are as follows: Figure 2 As shown, the regeneration solution prepared with LiPF6 and DMC exhibits superior regeneration performance compared to the Std electrolyte. Figure 2 The lifespan extension range corresponding to each salt / solvent molar ratio represents the range between the maximum and minimum lifespan extension rates of the five batteries to be decommissioned in different embodiments. When the salt / solvent molar ratio is 1:7 to 1:200, the lifespan extension rate is >10%. The lifespan extension rate shows a trend of first increasing and then decreasing with the change in salt content in the regenerated solution. The repair effect is best when the salt / solvent molar ratio is 1:15 to 1:50. However, when the salt content is too high, the viscosity of the regenerated solution increases, resulting in poor wettability of the electrodes and a worse regeneration effect. For example, when the salt / solvent molar ratio is 1:5, the measured lifespan extension rate of the battery is only 7.6% to 15%. When the salt content is further increased to a salt / solvent molar ratio of 1:2.5, the regenerated solution cannot play a role in capacity recovery; instead, the capacity decreases after injection, and the lifespan extension rate is 0, as shown in Table 1.

[0069] Table 1. Battery life extension rate after repair treatment in Comparative Example 4

[0070]

[0071]

[0072] Examples 8-12

[0073] The amount of regenerated liquid added was adjusted to 0.3 g / Ah, 0.5 g / Ah, 0.7 g / Ah, 0.8 g / Ah, and 1.1 g / Ah, corresponding to Examples 8, 9, 10, 11, and 12. LiPF6 and DMC with a molar ratio of 1:15 were used as the regenerated liquid. The batteries to be decommissioned were repaired in the same manner as in Examples 1 to 7, and the life extension rate was calculated. Under the same conditions, 5 batteries were repaired.

[0074] The lifespan extension rate versus regenerated liquid addition amount results for Examples 8 to 12 are as follows: Figure 3 As shown. Figure 3The life extension rate range corresponding to each amount of regenerated liquid added is the range between the maximum and minimum life extension rates of the five batteries to be retired in different embodiments. Figure 3 It can be seen that increasing the amount of regenerated liquid added increases the lifespan extension rate to some extent, with the best regeneration effect observed at an addition rate of approximately 0.5–0.8 g / Ah. Further increasing the addition amount did not significantly improve the lifespan extension rate, and increasing the dosage would increase costs.

[0075] Examples 13-16

[0076] The test subjects were LFP / Gr batteries that had degraded to different capacity retention rates, specifically commercial lithium batteries (LFP / Gr, 200mAh) from the same batch, with lithium iron phosphate (LFP) as the positive electrode, graphite (Gr) as the negative electrode, and Std as the electrolyte, with an addition amount of E / C = 5.3g / Ah. The LFP / Gr batteries were subjected to charge-discharge cycle tests at a 2C rate until their capacity degraded to 60%, 70%, 80%, and 90% of their initial capacity, respectively, yielding batteries to be retired. The corresponding examples are 13, 14, 15, and 16. For ease of comparison, the NCL calculation method remained consistent: the actual number of cycles divided by the number of cycles at 80% capacity degradation. That is, the NCL at 80% capacity degradation was 1.

[0077] A LiPF6 / DMC regenerated solution with a molar ratio of 1:15 was used to repair decommissioned batteries. The amount of regenerated solution added was 0.7 g / Ah, and then regeneration was carried out using the same method as in Examples 1-7. The lifespan improvement rate was calculated, and 5 batteries were repaired under the same conditions.

[0078] In Examples 13-16, the patterns observed in each degradation stage are quite similar. For each example, a battery with near-average performance is selected as a representative, and a capacity retention rate versus normalized lifetime correlation graph is plotted, as shown below. Figure 4 As shown. By Figure 4 It can be seen that replenishing electrolyte when the battery capacity decreases to 80-90% results in some capacity recovery, and the rate of capacity loss slows down in subsequent cycles, demonstrating a significant regeneration effect. However, the overall cycle life of replenishing electrolyte when the battery capacity decreases to 90% is shorter than that of replenishing when the capacity decreases to 80%. Replenishing electrolyte when the battery capacity decreases to 70% restores the capacity to approximately 80%, with a similar rate of capacity loss as replenishing when the capacity decreases to 80-90%. However, due to the limited capacity recovery, the capacity quickly falls below 80%. Replenishing electrolyte when the battery capacity decreases to 60% results in slower capacity loss in subsequent cycles, but the capacity only recovers to approximately 70%. Considering the range requirements of electric vehicles, the battery needs to recover to a higher capacity to meet later usage needs. Therefore, the preferred replenishment time is between 70% and 90% capacity retention, with 80% being a better option.

[0079] Examples 17-29

[0080] As shown in Table 2, the lithium salt was kept to be LiPF6. After modifying the solvent type, the regenerated solution was prepared at a LiPF6 / solvent molar ratio of 1:15 (in Examples 27-29, the molar ratio of the two solvents in the mixed solvent was 1:1). The amount of regenerated solution added was 0.7 g / Ah. Regeneration was carried out in the same way as in Examples 1-7, and the life extension rate was calculated. Under the same conditions, 5 batteries were repaired.

[0081] Table 2. Remediation effects of regeneration solutions prepared with different solvents

[0082] Serial Number lithium salts solvent Lifespan extension rate (%) Example 17 <![CDATA[LiPF6]]> DEC 48.6～85.1 Example 18 <![CDATA[LiPF6]]> EMC 19.5～44.1 Example 19 <![CDATA[LiPF6]]> EC 15.4～29.4 Example 20 <![CDATA[LiPF6]]> SUL 2.9～15.9 Example 21 <![CDATA[LiPF6]]> ES 35.9～49.2 Example 22 <![CDATA[LiPF6]]> AN 39.5～92.7 Example 23 <![CDATA[LiPF6]]> HN 2.9～5.1 Example 24 <![CDATA[LiPF6]]> MP 19.7～63.0 Example 25 <![CDATA[LiPF6]]> EA 10.4～59.3 Example 26 <![CDATA[LiPF6]]> TMB 4.5～11.9 Example 27 <![CDATA[LiPF6]]> DMC+EC 26.4～28.1 Example 28 <![CDATA[LiPF6]]> DEC+EC 18.6～22.8 Example 29 <![CDATA[LiPF6]]> AN+EC 28.9～42.3

[0083] Table 2 shows the regeneration effects of regenerated solutions prepared with different solvents. The life extension rate ranges for each solvent in Table 2 are the range between the maximum and minimum life extension rates of the five batteries to be retired in different embodiments. Among them, carbonate solvents such as DEC, EMC, and EC are commonly used solvents in commercial electrolytes. These solvents have stable structures, good electrochemical stability, and strong solubility for lithium salts.

[0084] Meanwhile, the inventors noted that dilute solutions of nitrile compounds (AN, HN, etc.) and carboxylic acid esters (MP, EA, etc.) are generally unsuitable for direct use as electrolytes due to their strong reactivity with the negative electrode. They are only reported as electrolytes under high concentration conditions (e.g., LiPF6 / AN > 3M; LiFSI / MP > 3M), because the solution structure changes at these conditions, forming an anion-coordinated AGG structure, which significantly increases the electrochemical window and improves electrolyte stability. However, the regenerated solution in this invention, with a molar ratio of 1:15 for such solvents, is a dilute solution and cannot be used as a conventional electrolyte, but it performs very well as a regenerated solution. This suggests that the construction mechanism of the regenerated solution formulation differs from that of the electrolyte, and it is speculated that the solvent plays a crucial role in the solubility of lithium salts.

[0085] Comparative Example 5-19

[0086] Except for the solvents used to prepare the regenerated solution as shown in Table 3 below (in Comparative Examples 17-19, the molar ratio of the two solvents in the mixed solvent was 1:1), regeneration was performed in the same manner as in Examples 17-29, and the lifetime extension rate was calculated. The results are also listed in Table 3 below.

[0087] Table 3 Examples of regenerants with no regeneration effect

[0088] Serial Number lithium salts solvent Lifespan extension rate (%) Comparative Example 5 <![CDATA[LiPF6]]> PC 0.0 Comparative Example 6 <![CDATA[LiPF6]]> DME 0.0 Comparative Example 7 <![CDATA[LiPF6]]> G3 0.0 Comparative Example 8 <![CDATA[LiPF6]]> G4 0.0 Comparative Example 9 <![CDATA[LiPF6]]> THF 0.0 Comparative Example 10 <![CDATA[LiPF6]]> DOL 0.0 Comparative Example 11 <![CDATA[LiPF6]]> DMSO 0.0 Comparative Example 12 <![CDATA[LiPF6]]> TMP 0.0 Comparative Example 13 <![CDATA[LiPF6]]> TEP 0.0 Comparative Example 14 <![CDATA[LiPF6]]> DMF 0.0 Comparative Example 15 <![CDATA[LiPF6]]> NMP 0.0 Comparative Example 16 <![CDATA[LiPF6]]> TEB 0.0 Comparative Example 17 <![CDATA[LiPF6]]> PC+EC 0.0 Comparative Example 18 <![CDATA[LiPF6]]> EC+DMF 0.0 Comparative Example 19 <![CDATA[LiPF6]]> EC+TEP 0.0

[0089] According to the results in Table 3, none of the listed solvents could extend the lifespan of the batteries to be retired. When injected into the batteries for recirculation, significant gas production was observed. Furthermore, some of these solvents are common electrolyte solvents, which indicates that adding any electrolyte cannot extend the lifespan of batteries to be retired.

[0090] Examples 30-49

[0091] Except for the lithium salt preparation regeneration solution shown in Table 4 below (where DMC is used as the solvent and the molar ratio of the two salts in the mixed salt is 1:1), the regeneration was carried out in the same manner as in Examples 17-29, and the lifetime extension rate was calculated. The results are listed in Table 4 below.

[0092] Table 4. Regeneration effect of regenerated solutions prepared with different lithium salts

[0093] Serial Number lithium salts solvent Lifespan extension rate (%) Example 30 <![CDATA[LiBF4]]> DMC 21.2～49.2 Example 31 LiDFOB DMC 40.3～63.3 Example 32 LiFSI DMC 61.0～84.4 Example 33 LiTFSI DMC 82.2～107.8 Example 34 LiOTf DMC 18.8～23.9 Example 35 <![CDATA[LiPF6+LiBF4]]> DMC 65.7～72.6 Example 36 <![CDATA[LiPF6+LiDFOB]]> DMC 15.2～57.8 Example 37 <![CDATA[LiPF6+LiFSI]]> DMC 21.8～22.7 Example 38 <![CDATA[LiPF6+LiTFSI]]> DMC 20.7～21.6 Example 39 <![CDATA[LiPF6+LiOTf]]> DMC 12.7～32.3 Example 40 <![CDATA[LiBF4+LiDFOB]]> DMC 11.3～49.4 Example 41 <![CDATA[LiBF4+LiFSI]]> DMC 31.1～36.1 Example 42 <![CDATA[LiBF4+LiTFSI]]> DMC 12.6～27.5 Example 43 <![CDATA[LiBF4+LiOTf]]> DMC 23.9～25.1 Example 44 LiDFOB+LiFSI DMC 16.1～57.1 Example 45 LiDFOB+LiTFSI DMC 15.7～17.6 Example 46 LiDFOB+LiOTf DMC 6.9～50.0 Example 47 LiFSI+LiTFSI DMC 14.4～41.9 Example 48 LiFSI+LiOTf DMC 17.5～70.5 Example 49 LiTFSI+LiOTf DMC 35.3～61.9

[0094] Table 4 shows the lifespan extension rate ranges for each lithium salt, representing the range between the maximum and minimum lifespan extension rates of the five batteries to be retired in different embodiments. As can be seen from Table 4, LiTFSI, LiFSI, and LiPF6 used in Examples 1-16 exhibit better performance for different lithium salts, and most mixed salts are less effective than single salts.

[0095] Examples 50-51

[0096] Lithium batteries of different specifications (rated capacity of 0.2Ah and 1Ah) were used as the repair targets (0.2Ah in Example 50; 1Ah in Example 51). LiPF6 / DMC with molar ratios of 1:15 to 1:50 (1:15, 1:20, 1:50) was used as the regeneration solution, with an addition amount of approximately 0.7 g / Ah. Regeneration was performed using the same method as in Examples 1-7, and the lifespan extension rate was calculated. Five batteries were repaired under the same conditions. The results show that the same regeneration scheme has good consistency across batteries of different specifications. The regeneration effect obtained under a molar ratio of 1:20 was selected as an example. For each example, one battery with a near-average effect was selected as a representative, and the capacity retention rate versus normalized lifespan correlation graphs for Examples 50 and 51 were plotted. Figure 5 The results show that under the same conditions, the regeneration effects of lithium batteries of different specifications (0.2Ah and 1Ah capacity) are similar, which can more than double the cycle life of retired batteries. The smallest cell size of power batteries that can be used in electric vehicles is close to the above specifications (such as Tesla 4.8Ah), indicating its potential for practical application in commercial automotive batteries.

[0097] Example 52

[0098] In addition to using the ternary material LiNi in step S1 0.5 Co 0.2 Mn 0.3 A battery (NCM523 / Gr, 0.2Ah, purchased from Hunan Lifang New Energy Technology Co., Ltd.) was assembled with O2 as the positive electrode and graphite as the negative electrode. The electrolyte used was 1.0M LiPF6 / EC:DEC+2%VC, with an addition amount of E / C = 5.3g / Ah. The regeneration solution used was 1:15LiDFOB / ES, and the regeneration was carried out in the same way as in Examples 1 to 7, and the life extension rate was calculated.

[0099] Comparative Example 20

[0100] Commercially available NCM523 / Gr lithium-ion batteries were used, with an electrolyte of 1.0M LiPF6 / EC:DEC + 2% VC, and an addition amount of E / C = 5.3 g / Ah. The LPF / Gr batteries were subjected to charge-discharge cycle tests at a 2C rate until the normalized lifespan reached 2.0.

[0101] The lifetime retention-normalized lifetime results for the batteries of Example 52 and Comparative Example 20 are as follows: Figure 6 As shown. From Figure 6 The results show that the regeneration method and regeneration solution described in this invention also have a regeneration effect on ternary / graphite system batteries. However, the optimal formulation of the regeneration solution needs to be adjusted according to the type of cathode material.

[0102] Examples 53-54

[0103] The test subjects were two commercially available lithium-ion batteries (LFP / Gr, 200mAh) from the same batch. The positive electrode was lithium iron phosphate (LFP), the negative electrode was graphite (Gr), and the electrolyte was Std, with an E / C ratio of 5.3 g / Ah. One battery was pre-cycled for 10 cycles at a charge / discharge cutoff voltage of 2-3.65V. The other battery, after its capacity decayed to 80%, was replenished using the same method as in Examples 1-7. The regenerated electrolyte was LiPF6:DMC with a molar ratio of 1:200, and the injection volume was 1.1 g / Ah. The impact of introducing the maximum amount of solvent on battery safety was investigated. After another 10 cycles at the 2-3.65V charge / discharge cutoff voltage, the batteries were sent to a third-party testing institution (Tianmu Lake Advanced Energy Storage Technology Research Institute Co., Ltd.) for a nail penetration test. This involved inserting a steel nail into the battery at a certain speed under 100% SOC full charge conditions, recording changes in battery voltage and surface temperature, and observing whether the battery caught fire, emitted smoke, or exploded. The results are as follows: Figure 7-8 As shown in Table 5 below.

[0104] Table 5. Needle penetration test of new battery and battery after liquid replenishment.

[0105]

[0106] from Figure 7-8 As can be seen from the results in Table 5, after the batteries to be retired are regenerated according to the method of the present invention, the regenerated batteries have good safety performance, and do not bulge, smoke, or catch fire and explode under the needle penetration condition.

[0107] Example 55

[0108] The batteries awaiting retirement were repaired using the same method as in Examples 1-7. A LiPF6:DMC regenerator with a molar ratio of 1:5 was selected, and the injection volume was 1.1 g / Ah. The effect of the injection time on wettability was investigated using an ultrasonic non-destructive intelligent diagnostic instrument (UBSC-LD50, Jiangsu Jicui Huake Intelligent Equipment Technology Co., Ltd.). The results are as follows: Figure 9 As shown, after injecting regenerated electrolyte into the retired battery, ultrasonic scanning was performed every 12 hours. Immediately after electrolyte injection, the battery was still dry, and the ultrasonic spectrum was predominantly green and blue. As the settling time increased, the red area in the ultrasonic spectrum gradually increased, indicating improved wetting. After 36 hours, the spectrum remained relatively stable. Under these conditions, the regenerated electrolyte had high viscosity and high content, theoretically requiring the longest settling time for full wetting. However, using a lower viscosity regenerated electrolyte or reducing the injection volume resulted in faster diffusion, and 36 hours of settling was sufficient for full wetting. Therefore, when regenerating retired batteries, after injecting the regenerated electrolyte, it is necessary to allow the battery to set for at least 36 hours to ensure full wetting before starting electrochemical testing to obtain good regeneration results.

[0109] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A battery regeneration method, comprising the following steps: S1: Drill holes in the batteries to be retired and inject regeneration fluid; S2: After vacuuming, seal and let stand for more than 36 hours; The batteries to be decommissioned are lithium-ion batteries. The amount of the regenerated liquid added is 0.3 to 1.1 g / Ah.

2. The method according to claim 1, wherein, The positive electrode material of the lithium-ion battery is lithium iron phosphate, ternary layered oxide, lithium-rich manganese-based, or lithium cobalt oxide, the negative electrode material is graphite, hard carbon, or silicon / carbon composite material, and the electrolyte is lithium hexafluorophosphate dissolved in a mixed carbonate organic solvent.

3. The method according to claim 1, wherein, The capacity of the batteries to be retired is 70% to 90% of their initial rated capacity.

4. The method according to claim 1, wherein, The battery regeneration solution contains lithium salt and organic solvent.

5. A battery regeneration fluid, characterized in that, The regenerated solution contains a solute and a solvent; the solute is a lithium salt; the solvent is an organic reagent; and the molar ratio of the solute to the solvent is 1:5 to 1:

200.

6. The battery regeneration solution according to claim 5, wherein... The lithium salt is selected from any one or more of lithium trifluoromethanesulfonylimide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), and lithium perchlorate (LiClO4) in any proportion.

7. The battery regeneration solution according to claim 5, wherein... The solvent is selected from any one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), methyl propionate (MP), trimethyl borate (TMB), ethyl acetate (EA), ethylene sulfite (ES), acetonitrile (AN), adiponitrile (HN), and sulfolane (SUL) in any proportion.

8. The battery regeneration solution according to claim 5, wherein... The solute in the battery regeneration solution is LiPF6, and the solvent is one or a mixture of two selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), sulfolane (SUL), ethylene sulfite (ES), acetonitrile (AN), adiponitrile (HN), methyl propionate (MP), ethyl acetate (EA), and trimethyl borate (TMB).

9. The battery regeneration solution according to claim 5, wherein... The solute in the battery regeneration solution is lithium hexafluorophosphate (LiPF6), and the solvent is dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), sulfolane (SUL), ethylene sulfite (ES), acetonitrile (AN), adiponitrile (HN), methyl propionate (MP), ethyl acetate (EA), trimethyl borate (TMB), a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC), a mixture of dimethyl carbonate (DMC) and ethylene carbonate (EC), a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC), or a mixture of acetonitrile (AN) and ethylene carbonate (EC).

10. The battery regeneration solution according to claim 5, wherein... The solvent in the battery regeneration solution is dimethyl carbonate (DMC), and the solute is one or a mixture of two of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium trifluoromethanesulfonate (LiOTf).

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