Ultralow-temperature battery aging method
By using three-stage aging method and electrolytes with different additives in lithium-ion batteries, the problem of poor performance of lithium-ion batteries at ultra-low temperatures is solved, which significantly improves the circulation performance and rate performance, and avoids the increase in battery internal resistance.
Patent Information
- Application Number
- CN202510322947.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-10
AI Technical Summary
The prior art is difficult to effectively improve the cycling performance and rate performance of lithium-ion batteries at ultra-low temperatures, and the aging method is not suitable for the performance differences between different electrolytes.
Three-stage aging methods are used to aging at 60~65℃, below 15℃ and 50~55℃, and electrolytes with different additives are injected into each stage of aging, including acetonitrile, N,N-dimethyltrifluoroacetamide and methyl formate.
By selecting the appropriate additives and aging temperature, the circulation and rate performance of lithium-ion batteries at ultra-low temperatures is significantly improved, avoiding the increase in battery internal resistance and helping to reduce battery internal resistance.
Smart Images
Figure CN120127357A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of batteries, and in particular to a method for aging ultra-low temperature batteries. Background Art
[0002] The activity of the internal chemical substances of newly produced lithium-ion batteries is relatively high, which may lead to unstable battery performance. Through the aging process, the internal chemical reactions of the battery can reach a relatively balanced state, thereby improving the consistency and stability of the battery. At the same time, during the aging process, defective products or potential faulty batteries can also be screened out (by undergoing charge and discharge cycles in the aging test, batteries with short life, low capacity or potential safety hazards can be detected in advance). At the same time, the aging process is also an opportunity to calibrate the battery performance parameters; by testing the aged battery, the optimal working conditions of the battery (such as charging rate, discharge depth, etc.) can be determined more accurately. In short, aging is an important link in the production of lithium-ion batteries and is crucial for ensuring the safety, reliability and long life of the batteries.
[0003] Since the performance of different battery electrolytes is different, a unified standard formation and aging method cannot be applied. Therefore, the applicant has specifically designed a battery aging method for ultra-low temperature lithium-ion batteries. Summary of the Invention
[0004] The purpose of the present invention is to propose a method for aging ultra-low temperature batteries to improve the cycle performance and rate performance of lithium batteries at ultra-low temperatures.
[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A method for aging ultra-low temperature batteries, comprising the following steps: S1. Inject a first electrolyte containing a first additive into the lithium-ion battery to be filled with liquid; S2. Age at a first predetermined temperature of 60-65°C for 10-16 hours; S3. Inject a second electrolyte containing a second additive; S4. Age at a second predetermined temperature below 15°C for 10-16 hours; S5. Inject a third electrolyte containing a third additive; S6. Age at a third predetermined temperature of 50-55°C for 10-16 hours; S7. Perform charge and discharge formation on the lithium-ion battery after three-stage aging.
[0006] In some embodiments, the original electrolyte of the first electrolyte is LiBOB-SL / EC; The second electrolyte is: adding a second additive to the first electrolyte; The third electrolyte is: adding a third additive to the second electrolyte; The volume ratio of the first electrolyte, the second electrolyte, and the third electrolyte is 94-95: 3-4: 1-3.
[0007] In some embodiments, the first additive is any one of acetonitrile, dichloromethane, dichloroethane, dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoric triamide.
[0008] In some embodiments, the addition amount of the first additive is 8.0-10% of the volume of the first electrolyte.
[0009] In some embodiments, the second additive is any one of N, N-dimethyltrifluoroacetamide, N, N-dimethylformamide, N-formyldimethylamine, fluoroethylene carbonate, propylene sulfate, vinylene sulfate, ethylene sulfite, and propylene sulfite.
[0010] In some embodiments, the addition amount of the second additive is 2.5-3.0% of the volume of the second electrolyte.
[0011] In some embodiments, the third additive is any one of methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethyl butyrate, and butyl acrylate.
[0012] In some embodiments, the addition amount of the third additive is 1.5-2.0% of the volume of the third electrolyte.
[0013] In some embodiments, the second predetermined temperature is 10-15°C.
[0014] In some embodiments, in step S7, the following steps are included: A1. Constant current charge to 3.55-3.60V; A2. Constant voltage charge until the charging current is lower than the charging cut-off current; A3. Vacuum exhaust and seal; A4. Constant current charge and discharge 3-5 times between the charging cut-off voltage and the discharging cut-off voltage.
[0015] Compared with the prior art, the present invention provides a method for aging a super-low temperature battery, having the following beneficial effects.
[0016] 1. In the present invention, by selecting additives and cooperating with each other, the cycle performance and rate performance of the battery at ultra-low temperatures are effectively improved.
[0017] 2. In the present invention, the three-stage aging method, combined with the additives, not only improves the cycle performance but also avoids the increase in the internal resistance of the battery.
[0018] 3. The present invention performs constant voltage formation at a specific voltage, which helps the slow discharge of battery gas. Compared with direct charge and discharge cycling, it helps reduce the internal resistance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a flowchart of the present invention.
[0020] Figure 2 It is a flowchart of charge and discharge formation. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.
[0022] Refer to Figure 1-2 ; A method for ultra-low temperature battery aging, comprising the following steps: S1. Inject a first electrolyte containing a first additive into the lithium-ion battery to be filled with liquid; S2. Age at a first predetermined temperature of 60-65 °C for 10-16 hours; S3. Inject a second electrolyte containing a second additive; S4. Age at a second predetermined temperature below 15 °C for 10-16 hours; Preferably, the second predetermined temperature is 10-15 °C; S5. Inject a third electrolyte containing a third additive; S6. Age at a third predetermined temperature of 50-55 °C for 10-16 hours; S7. Perform charge and discharge formation on the lithium-ion battery after three-stage aging.
[0023] Among them, the ultra-low temperature battery targeted by this application is a high specific energy and high rate ultra-low temperature battery.
[0024] The original electrolyte is LiBOB-SL / EC (lithium bis(oxalato)borate - sulfolane / ethylene carbonate).
[0025] The first electrolyte is: adding a first additive to the original electrolyte.
[0026] The second electrolyte is: adding a second additive to the first electrolyte.
[0027] The third electrolyte is: adding a third additive to the second electrolyte.
[0028] The volume ratio of the first electrolyte, the second electrolyte, and the third electrolyte is 94-95 : 3-4 : 1-3.
[0029] This battery has good low-temperature working performance; combined with the aging method of this application, it can effectively improve the cycle performance and rate performance at ultra-low temperatures.
[0030] In some embodiments: The first additive is any one of acetonitrile, dichloromethane, dichloroethane, dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoric triamide.
[0031] The addition amount of the first additive is 8.0 - 10% of the volume of the first electrolyte.
[0032] Preferably, the first additive is acetonitrile.
[0033] In some embodiments: The second additive is any one of N,N-dimethyltrifluoroacetamide, N,N-dimethylformamide, N-formyldimethylamine, fluoroethylene carbonate, propylene sulfate, vinylene sulfate, ethylene sulfite, and propylene sulfite.
[0034] The addition amount of the second additive is 2.5 - 3.0% of the volume of the second electrolyte.
[0035] Preferably, the second additive is N,N-dimethyltrifluoroacetamide.
[0036] In some embodiments: The third additive is any one of methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethyl butyrate, and butyl acrylate.
[0037] The addition amount of the third additive is 1.5 - 2.0% of the volume of the third electrolyte.
[0038] Preferably, the third additive is methyl formate.
[0039] In some embodiments: In step S7, it includes the following steps: A1. Constant current charge to 3.55 - 3.60 V; A2. Constant voltage charge until the charging current is lower than the charging cut-off current; A3. Vacuum exhaust and seal; A4. Constant current charge and discharge 3 - 5 times between the charging cut-off voltage and the discharging cut-off voltage.
[0040] Preferably, in step A4, constant current charge and discharge are performed 3 times.
[0041] Example 1.
[0042] The volume ratio of the first electrolyte, the second electrolyte, and the third electrolyte is 94:3:3.
[0043] S1. Inject a first electrolyte solution containing a first additive into the lithium-ion battery to be filled with liquid. Among them, the first additive is dichloromethane, and the addition amount is 8%.
[0044] S2. Age at 60 °C for 10 hours.
[0045] S3. Inject a second electrolyte solution containing a second additive. Among them, the second additive is N,N-dimethylformamide, and the addition amount is 2.5%.
[0046] S4. Age at 10 °C for 10 hours.
[0047] S5. Inject a third electrolyte solution containing a third additive. Among them, the third additive is butyl acrylate, and the addition amount is 1.5%.
[0048] S6. Age at 50 °C for 10 hours.
[0049] S7. Perform charge and discharge formation on the lithium-ion battery after three-stage aging.
[0050] Specifically, charge at a constant current to 3.60 V; then, charge at a constant voltage until the charging current is lower than the charging cut-off current of 0.02C; then, evacuate and seal; then, perform constant current charge and discharge 3 times between the charging cut-off voltage of 3.60 V and the discharging cut-off voltage of 2.8 V.
[0051] Example 2.
[0052] The volume ratio of the first electrolyte solution, the second electrolyte solution, and the third electrolyte solution is 95:3:2.
[0053] S1. Inject a first electrolyte solution containing a first additive into the lithium-ion battery to be filled with liquid. Among them, the first additive is dimethyl sulfoxide, and the addition amount is 8%.
[0054] S2. Age at 63 °C for 10 hours.
[0055] S3. Inject a second electrolyte solution containing a second additive. Among them, the second additive is ethylene sulfite, and the addition amount is 2.5%.
[0056] S4. Age at 12 °C for 10 hours.
[0057] S5. Inject a third electrolyte solution containing a third additive. Among them, the third additive is methyl butyrate, and the addition amount is 1.5%.
[0058] S6. Age at 53 °C for 10 hours.
[0059] S7. Perform charge and discharge formation on the lithium-ion battery after three-stage aging.
[0060] Specifically, charge at a constant current to 3.60 V; then, charge at a constant voltage until the charging current is lower than the charging cut-off current of 0.02 C; then, evacuate and seal; then, perform constant current charge and discharge 3 times at 0.2 C between the charging cut-off voltage of 3.60 V and the discharging cut-off voltage of 2.8 V.
[0061] Example 3.
[0062] The volume ratio of the first electrolyte, the second electrolyte, and the third electrolyte is 94:3:3.
[0063] S1. Inject the first electrolyte containing the first additive into the lithium-ion battery to be filled with electrolyte. Among them, the first additive is acetonitrile, and the addition amount is 8%.
[0064] S2. Age at 65 °C for 10 hours.
[0065] S3. Inject the second electrolyte containing the second additive. Among them, the second additive is N,N-dimethyltrifluoroacetamide, and the addition amount is 2.5%.
[0066] S4. Age at 15 °C for 10 hours.
[0067] S5. Inject the third electrolyte containing the third additive. Among them, the third additive is methyl formate, and the addition amount is 1.5%.
[0068] S6. Age at 55 °C for 10 hours.
[0069] S7. Perform charge and discharge formation on the lithium-ion battery after three-stage aging.
[0070] Specifically, charge at a constant current to 3.60 V; then, charge at a constant voltage until the charging current is lower than the charging cut-off current of 0.02 C; then, evacuate and seal; then, perform constant current charge and discharge 3 times at 0.2 C between the charging cut-off voltage of 3.60 V and the discharging cut-off voltage of 2.8 V.
[0071] Comparative Example 1.
[0072] The electrolyte is LiBOB-SL / EC; no additives are added during the aging process.
[0073] The volume ratio of the electrolyte added for the first, second, and third times is 94:3:3.
[0074] S1. Inject the electrolyte into the lithium-ion battery to be filled with electrolyte for the first time.
[0075] S2. Age at 60 °C for 10 hours.
[0076] S3. Inject electrolyte for the second time.
[0077] S4. Age at 10 °C for 10 hours.
[0078] S5. Inject electrolyte for the third time.
[0079] S6. Age at 50 °C for 10 hours.
[0080] S7. Charge and discharge the lithium-ion battery after three-stage aging.
[0081] Specifically, charge at a constant current to 3.60 V; then, charge at a constant voltage until the charging current is lower than the charging cut-off current of 0.02C; then, evacuate and seal; then, perform constant-current charge and discharge at 0.2C three times between the charging cut-off voltage of 3.60 V and the discharging cut-off voltage of 2.8 V.
[0082] Comparative Example 2.
[0083] The electrolyte is LiPF 6 +EC / DMC; no additives are added during the aging process.
[0084] The volume ratios of the electrolyte added for the first, second, and third times are 95:3:2.
[0085] S1. Inject electrolyte into the lithium-ion battery to be filled for the first time.
[0086] S2. Age at 60 °C for 10 hours.
[0087] S3. Inject electrolyte for the second time.
[0088] S4. Age at 10 °C for 10 hours.
[0089] S5. Inject electrolyte for the third time.
[0090] S6. Age at 50 °C for 10 hours.
[0091] S7. Charge and discharge the lithium-ion battery after three-stage aging.
[0092] Specifically, charge at a constant current to 3.60 V; then, charge at a constant voltage until the charging current is lower than the charging cut-off current of 0.02C; then, evacuate and seal; then, perform constant-current charge and discharge at 0.2C three times between the charging cut-off voltage of 3.60 V and the discharging cut-off voltage of 2.8 V.
[0093] Testing and results.
[0094] Lithium ion secondary batteries after preparation of Test Examples 1-3 and Comparative Examples 1-3; Charge at 0.1C and 1C rates at 25°C and freeze in a low-temperature cabinet at -40°C for 4 hours; Then, discharge at 0.1C and 1C rates, cycle 400 times, and measure the capacity retention rate of the lithium ion secondary battery. The results are shown in the following table.
[0095] Through Examples 1, 2, 3 and Comparative Example 1, it was found that when the original electrolyte was the same, adding additives had a significant effect on improving the low-temperature rate performance and capacity retention rate of the aged battery.
[0096] Through Examples 1, 2, 3 and Comparative Example 2, it was found that using the LiBOB-SL / EC electrolyte and additives, its low-temperature performance after aging was better than that of the conventional electrolyte at low temperature rates.
[0097] Through Examples 1, 2, 3, it was found that different aging temperatures had a greater impact on the cycle performance.
[0098] Comparing the combined synergistic effects of the three additives in Comparative Examples 1, 2, 3, adding additives had an obvious effect on improving the capacity retention rate and rate performance.
[0099] In the present invention: Acetonitrile has a high dielectric constant, making it easier for lithium ions to be transported in the electrolyte; it helps the battery to perform ion exchange more quickly during charge and discharge, improving the charge and discharge efficiency and rate performance of the battery; and, in a low-temperature environment, acetonitrile can keep the electrolyte in good fluidity, which helps the battery to maintain high charge and discharge performance under low-temperature conditions; N,N-dimethyltrifluoroacetamide (DTA) has characteristics such as low viscosity (1.09 mPa•S, 25°C), high boiling point (135°C) and flash point (72°C); it has good film-forming ability on the graphite surface and good oxidation stability for the positive electrode; as an electrolyte additive, it enables the battery to have excellent cycle performance at low temperature; Methyl formate (MF) has a low melting point and small intermolecular forces, which is beneficial to improving the reaction activity, and its chemical properties are relatively stable and not prone to decomposition reactions.
[0100] Through the synergistic effect of different additives and the temperature control of three-stage aging, the main reasons for low-temperature capacity decay such as slow lithium ion diffusion, surging battery internal resistance, unstable electrode / electrolyte interface and potential lithium deposition were alleviated; at the same time, the liquid range of the electrolyte was broadened, a stable electrode / electrolyte interface was constructed and the desolvation rate was accelerated, which could effectively improve the low-temperature performance of lithium batteries.
[0101] The present invention has at least the following advantages: 1. The combination of additives such as acetonitrile, N,N-dimethyltrifluoroacetamide, and methyl formate effectively improves the cycle performance and rate performance of the battery at ultra-low temperatures; 2. By adopting a three-stage aging method and adding different additives, not only the cycle performance is improved, but also the increase in the internal resistance of the battery is avoided; 3. Constant voltage formation at a specific voltage helps the slow discharge of battery gas. Compared with direct charge and discharge cycling, it helps to reduce the internal resistance of the battery.
[0102] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.
[0103] In the description of this specification, the description of reference terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" 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 invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.
[0104] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for ultra-low temperature battery aging, characterized in that: The following steps are involved: S1, injecting a first electrolyte containing a first additive into a lithium-ion battery to be injected; S2, aging at a first predetermined temperature of 60-65°C for 10-16 hours; S3, injecting a second electrolyte containing a second additive; S4, aging for 10 to 16 hours at a second predetermined temperature below 15°C; S5, injecting a third electrolyte containing a third additive; S6, aging at a third predetermined temperature of 50-55° C. for 10-16 hours; S7. After three stages of aging, the lithium-ion battery is charged and discharged.
2. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The original electrolyte of the first electrolyte is LiBOB-SL / EC; The second electrolyte is: a first electrolyte with a second additive added thereto; The third electrolyte is: a third additive is added to the second electrolyte; The volume ratio of the first electrolyte, the second electrolyte, and the third electrolyte is 94~95: 3~4: 1~3.
3. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The first additive is any one of acetonitrile, dichloromethane, dichloroethane, dimethylformamide, dimethyl sulfoxide, and hexamethylphosphoric triamide.
4. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The amount of the first additive added is 8.0-10% of the volume of the first electrolyte.
5. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The second additive is any one of: N,N-dimethyltrifluoroacetamide, N,N-dimethylformamide, N-formyl dimethylamide, fluoroethylene carbonate, propylene sulfate, vinylene sulfate, ethylene sulfite, and propylene sulfite.
6. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The added amount of the second additive is 2.5-3.0% of the volume of the second electrolyte.
7. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The third additive is any one of methyl formate, methyl acetate, methyl butyrate, ethyl propionate, ethyl butyrate and butyl acrylate.
8. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The added amount of the third additive is 1.5-2.0% of the volume of the third electrolyte.
9. The method for ultra-low temperature battery aging according to claim 1, characterized in that: The second predetermined temperature is 10-15°C.
10. The method for ultra-low temperature battery aging according to claim 1, characterized in that: In step S7, the following steps are included: A1, constant current charging to 3.55~3.60V; A2, constant voltage charging, until the charging current is lower than the charging cut-off current; A3, vacuum exhaust and seal; A4. Between the charge cut-off voltage and the discharge cut-off voltage, charge and discharge at constant current for 3 to 5 times.