Application of potassium di-tert-butyl phosphate
By using potassium di-tert-butyl phosphate electrolyte in lithium-ion batteries, the problem of limited improvement in the cycle performance of lithium-ion batteries has been solved, enabling capacity restoration and performance improvement of old batteries, and reducing usage costs.
Patent Information
- Application Number
- CN202411117969.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-15
- Publication Date
- 2026-03-03
AI Technical Summary
Existing lithium-ion batteries have limited improvement in cycle performance, especially after 70 cycles when the discharge capacity drops significantly, rendering the battery unusable. How can we effectively slow down the rate of discharge capacity decay to reduce usage costs?
Adding potassium di-tert-butyl phosphate or an electrolyte containing potassium di-tert-butyl phosphate to old lithium-ion batteries, with the electrolyte composition being EC, EMC, and lithium hexafluorophosphate at a concentration of 1.0 mol/L, improves battery performance by adding it directly to the battery or by pre-complementing it.
It slows down the rate of discharge capacity decline of old lithium-ion batteries, improves the cycle performance and lifespan of batteries, allows old batteries to be reused, and reduces usage costs.
Smart Images
Figure CN121601847A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery technology, and in particular to the application of potassium di-tert-butyl phosphate in the capacity restoration of old lithium-ion batteries and its application in lithium-ion battery electrolytes. Background Technology
[0002] With increasing global emphasis on environmental protection, lithium-ion batteries are playing an increasingly important role as a clean energy source in the power and automotive industries. Currently, lithium-ion batteries are widely used in power grids and for energy storage in wind and solar power, as well as for backup power for residential and commercial use and for powering two-wheeled, three-wheeled, and automobile vehicles.
[0003] Currently, whether in energy storage or automotive power applications, with relatively stable battery energy density, improving the cycle performance of lithium-ion batteries is fundamental to reducing their operating costs and increasing user satisfaction. Lithium-ion batteries mainly consist of a casing, positive and negative electrodes, a separator, and an electrolyte. Existing literature and patents have disclosed methods for improving the cycle performance of lithium-ion batteries through improvements in positive electrode materials, negative electrode materials, and electrolytes.
[0004] Regarding electrolytes, adding additives can effectively slow down the rate of capacity decay of lithium-ion batteries and improve their cycle performance. However, current additives have limited effect on improving the cycle performance of lithium-ion batteries. After about 70 cycles, the battery's discharge capacity drops from 100% to about 98.5%. After several thousand cycles, the battery's discharge capacity will drop significantly, and it will be considered a waste battery, thus becoming unusable.
[0005] How to effectively slow down the rate of capacity decay of lithium-ion batteries, improve their cycle performance, and further reduce their usage costs is an urgent problem to be solved. Summary of the Invention
[0006] Therefore, there is an urgent need to provide an additive that can improve the performance of lithium-ion battery electrolytes, thereby slowing down the discharge decay rate of lithium-ion batteries and improving their cycle performance; there is also an urgent need to provide an electrolyte additive that can restore the discharge capacity of old batteries, so that old batteries can be reused.
[0007] One of the objectives of this invention is to provide the application of potassium di-tert-butyl phosphate in the capacity restoration of old lithium-ion batteries.
[0008] Furthermore, the repair electrolyte containing potassium di-tert-butyl phosphate is prepared in advance and then added to the old lithium-ion battery.
[0009] Furthermore, the remediation electrolyte containing potassium di-tert-butyl phosphate includes a solvent, a lithium salt, and potassium di-tert-butyl phosphate; the solvent includes EC and EMC; and the lithium salt is lithium hexafluorophosphate.
[0010] The electrolyte for repair contains EC, EMC, and potassium di-tert-butyl phosphate in a mass ratio of 9:21:10, and lithium hexafluorophosphate at a concentration of 1.0 mol / L.
[0011] Furthermore, the potassium di-tert-butyl phosphate salt was directly added to an existing lithium-ion battery.
[0012] Another object of the present invention is to provide the application of potassium di-tert-butyl phosphate in lithium-ion battery electrolytes.
[0013] Furthermore, after the lithium-ion battery is formed, an electrolyte containing potassium di-tert-butyl phosphate is added.
[0014] Furthermore, an electrolyte containing potassium di-tert-butyl phosphate is prepared in advance and then added to the lithium-ion battery casing during the manufacturing process to serve as the electrolyte for the lithium-ion battery.
[0015] Furthermore, the electrolyte containing potassium di-tert-butyl phosphate includes a solvent, a lithium salt, and potassium di-tert-butyl phosphate; the solvent includes EC and EMC; the lithium salt is lithium hexafluorophosphate.
[0016] The electrolyte for repair contains EC, EMC, and potassium di-tert-butyl phosphate in a mass ratio of 9:21:10, and lithium hexafluorophosphate at a concentration of 1.0 mol / L.
[0017] Furthermore, the potassium di-tert-butyl phosphate is directly added to the lithium-ion battery electrolyte.
[0018] The present invention has the following advantages and effects:
[0019] This invention achieves effective capacity restoration of old lithium-ion batteries by adding potassium di-tert-butyl phosphate or an electrolyte containing potassium di-tert-butyl phosphate.
[0020] Furthermore, the rate of decline in discharge capacity of the repaired lithium-ion battery is slower than before repair, thereby effectively improving the discharge capacity retention rate of the old lithium-ion battery, reducing the cost of using lithium-ion batteries, and enabling the old batteries to be reused, which is economical and environmentally friendly.
[0021] This invention slows down the rate of capacity loss in lithium-ion batteries by adding potassium di-tert-butyl phosphate to the electrolyte of new lithium-ion batteries, thereby effectively improving the cycle performance of the batteries and reducing the cost of using lithium-ion batteries. Attached Figure Description
[0022] Figure 1 This is a comparison chart of the battery cycle-discharge capacity retention rates of Examples 1 and 2. Detailed Implementation
[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0024] In the embodiments, the used lithium-ion battery refers to an old battery whose discharge capacity has dropped to about 95% or less of the nominal capacity.
[0025] The following examples 1-2 illustrate the application of potassium di-tert-butyl phosphate in used lithium-ion battery electrolytes.
[0026] It should be noted that: Potassium di-tert-butyl phosphate has a melting point of 252℃, a boiling point of 252℃, a CAS number of 33494-80-3, and a molecular formula of C8H. 18 KO4P, with a molecular weight of 250, is potassium di-tert-butyl phosphate (PTB), typically appearing as white crystals or a crystalline powder. Its unique chemical structure is due to the presence of phosphorus, oxygen, potassium, carbon, and hydrogen elements linked together by specific chemical bonds to form a stable molecular structure. This structure endows PPB with unique properties in chemical reactions, such as good solubility, stability, and reactivity. PPB is commonly used as a chemical reagent in laboratories for certain organic synthesis reactions. In agriculture, it can serve as a substitute for phosphate fertilizers, providing phosphorus to plants and promoting their growth and development. In the chemical industry, PPB is also an important raw material. It can be used to synthesize other organic compounds, such as esters and amides. Furthermore, PPB can be used to prepare certain functional materials, such as flame retardants and antioxidants. This invention is the first to propose adding potassium di-tert-butyl phosphate as an electrolyte additive to old lithium-ion batteries. This additive can restore the capacity of old batteries to a certain extent, improve their cycle life, and can also be added to new batteries to increase their capacity. To fully demonstrate this effect of potassium di-tert-butyl phosphate, the following examples illustrate this capability.
[0027] Example 1
[0028] Take one commercially available used lithium iron phosphate battery with a nominal capacity of 20Ah as Sample 1 in Example 1 (the initial discharge capacity of Sample 1 battery was tested to be 93.65% of the nominal capacity). First, test the initial discharge capacity of the battery. Then, add an electrolyte containing potassium ditert-butyl phosphate to Sample 1 battery in a glove box. Then test the discharge capacity after charge and discharge cycles. Finally, calculate the discharge capacity retention rate of the battery.
[0029] (1) Preparation of electrolyte containing additives: The electrolyte was prepared in a glove box. The concentration of lithium hexafluorophosphate in the prepared electrolyte was 1 mol / L. The composition of additives and solvents is shown in Table 1.
[0030] (2) Initial battery capacity test: At 25℃±5℃, use a 5V-40A charge-discharge tester to charge the battery at a constant current (40A) to a voltage of 3.65V, then charge it at a constant voltage of 3.65V to a cutoff current of 1.0A, let it rest for 10 minutes, then discharge it at a constant current of 40A to a voltage of 2.5V, and let it rest for 10 minutes. This is one cycle. A total of 10 cycles are performed. The average value of the battery capacity is taken as the base of the initial discharge capacity, which is 100%.
[0031] (3) Electrolyte injection: In the glove box, open the battery injection port and add the electrolyte containing potassium ditert-butyl phosphate prepared in step (1). The amount of electrolyte containing additives added is shown in Table 2. After the electrolyte injection is completed, seal the battery, let it stand for 48 hours, and then perform a charge and discharge test.
[0032] (4) Charge and discharge test: At 25℃±5℃, use a 5V-40A charge and discharge tester to charge at a constant current (40A) to a voltage of 3.65V, then charge at a constant voltage of 3.65V to a cutoff current of 1.0Ah, let it rest for 10min, then discharge at a constant current of 40A to a cutoff voltage of 2.5V, and let it rest for 10min. This is one cycle. Test the discharge capacity of the battery for the 300th, 600th, 900th, 1200th, 1500th, 1800th and 2100th cycles, and calculate the capacity retention rate.
[0033] See Table 2 for specific experimental data.
[0034] Example 2
[0035] One used lithium iron phosphate battery with a nominal capacity of 20Ah, purchased from the same batch as the battery in Example 1, was used as control sample 1 (the initial discharge capacity of control sample 1 was tested to be 89.75% of the nominal capacity). Control sample 1 was not mixed with potassium di-tert-butyl phosphate or any electrolyte. The initial discharge capacity of control sample 1 and the discharge capacity after charge-discharge cycles were tested according to the following method.
[0036] (1) Initial battery capacity test: At 25℃±5℃, use a 5V-40A charge-discharge tester to charge the battery to a constant current (40A) to a voltage of 3.65V, then charge it to a constant voltage of 3.65V until the cutoff current is 1.0A, let it rest for 10 minutes, then discharge it to a constant current of 40A until the voltage is cutoff at 2.5V, and let it rest for 10 minutes. This is one cycle, and a total of 10 cycles are performed. The average value of the tested battery capacity is taken as the base of the initial discharge capacity, which is 100%.
[0037] (2) Charge and discharge test: At 25℃±5℃, use a 5V-40A charge and discharge tester to charge at a constant current (40A) to a voltage of 3.65V, then charge at a constant voltage of 3.65V to a cutoff current of 1.0Ah, let it rest for 10min, then discharge at a constant current of 40A to a cutoff voltage of 2.5V, and let it rest for 10min. This is one cycle. Test the discharge capacity of the battery for the 300th, 600th, 900th, 1200th, 1500th, 1800th and 2100th cycles, and calculate the capacity retention rate.
[0038] See Table 2 for specific experimental data.
[0039] It should be noted that the specific formula for calculating the cyclic discharge capacity retention rate is as follows:
[0040] Battery capacity retention rate after Nth discharge cycle = Battery discharge capacity after Nth cycle / Initial discharge capacity before adding electrolyte × 100%.
[0041] The calculated data are shown in Table 2.
[0042] Sample 1 battery was supplemented with an electrolyte containing potassium di-tert-butyl phosphate, and the amount added was 2.32g.
[0043] The control sample 1 battery contained no electrolyte or additives.
[0044] The electrolyte is prepared by mixing EC (ethylene carbonate), EMC (ethyl methyl carbonate) and potassium di-tert-butyl phosphate in a mass ratio of 9:21:10, and the concentration of lithium hexafluorophosphate in the electrolyte is 1 mol / L.
[0045] From Table 2 and Figure 1As can be seen, the capacity retention rate of sample 1 battery in the first 1000 cycles is not significantly different from that of control sample 1. After the 1000th cycle, the degradation rate of sample 1 battery begins to be lower than that of control sample 1 battery. After the 1500th cycle, the degradation rate of sample 1 battery is significantly lower than that of control sample 1 battery. This indicates that adding an electrolyte containing potassium di-tert-butyl phosphate can effectively improve the battery's cycle discharge capacity, improve the capacity retention rate of lithium-ion batteries, delay battery degradation, and thus improve battery cycle performance and battery life.
[0046] Table 1. Composition of solvents and additives in the electrolyte (mass fraction)
[0047] name EC EMC Potassium di-tert-butyl phosphate electrolyte 9 21 10
[0048] Table 2 Capacity retention rate of batteries at different cycle counts
[0049]
[0050] Example 3
[0051] By taking a commercially available 20Ah brand new lithium iron phosphate battery and directly adding potassium di-tert-butyl phosphate into the battery, the battery's discharge capacity retention rate has been improved.
[0052] Example 4
[0053] By taking a brand-new 20Ah lithium iron phosphate battery from the market and adding an electrolyte containing potassium di-tert-butyl phosphate, the battery's discharge capacity retention rate was improved.
[0054] The electrolyte containing potassium di-tert-butyl phosphate includes a solvent, a lithium salt, and potassium di-tert-butyl phosphate; the solvent includes EC and EMC; the lithium salt is lithium hexafluorophosphate.
[0055] The electrolyte for repair contains EC, EMC, and potassium di-tert-butyl phosphate in a mass ratio of 9:21:10, and lithium hexafluorophosphate at a concentration of 1.0 mol / L.
[0056] Example 5
[0057] In the lithium-ion battery manufacturing process, an electrolyte containing potassium di-tert-butyl phosphate is added to the lithium-ion battery casing, followed by sealing the casing and formation; this process improves the battery's discharge capacity retention. The electrolyte containing potassium di-tert-butyl phosphate includes a solvent, a lithium salt, and potassium di-tert-butyl phosphate; the solvent includes EC and EMC; the lithium salt is lithium hexafluorophosphate; wherein, the mass ratio of EC, EMC, and potassium di-tert-butyl phosphate in the repair electrolyte is 9:21:10, and the concentration of lithium hexafluorophosphate is 1 mol / L.
Claims
1. Application of potassium di-tert-butyl phosphate in the capacity restoration of old lithium-ion batteries.
2. The application of potassium di-tert-butyl phosphate according to claim 1 in the capacity restoration of used lithium-ion batteries, characterized in that, The repair electrolyte containing potassium di-tert-butyl phosphate is prepared in advance and then added to the old lithium-ion battery.
3. The application of potassium di-tert-butyl phosphate according to claim 1 in the capacity restoration of used lithium-ion batteries, characterized in that, The remediation electrolyte containing potassium di-tert-butyl phosphate includes a solvent, a lithium salt, and potassium di-tert-butyl phosphate; the solvent includes EC and EMC; the lithium salt is lithium hexafluorophosphate. The electrolyte for repair contains EC, EMC, and potassium di-tert-butyl phosphate in a mass ratio of 9:21:10, and lithium hexafluorophosphate at a concentration of 1.0 mol / L.
4. The application of potassium di-tert-butyl phosphate according to claim 1 in the capacity restoration of used lithium-ion batteries, characterized in that, The potassium di-tert-butyl phosphate was directly added to the old lithium-ion battery.
5. Application of potassium di-tert-butyl phosphate in lithium-ion battery electrolytes.
6. The application of potassium di-tert-butyl phosphate according to claim 5 in lithium-ion battery electrolyte, characterized in that, After the lithium-ion battery is formed, an electrolyte containing potassium di-tert-butyl phosphate is added.
7. The application of potassium di-tert-butyl phosphate according to claim 5 in lithium-ion battery electrolyte, characterized in that, An electrolyte containing potassium di-tert-butyl phosphate is prepared in advance and then added to the lithium-ion battery casing during the manufacturing process to serve as the electrolyte for the lithium-ion battery.
8. The application of potassium di-tert-butyl phosphate according to claim 6 or 7 in lithium-ion battery electrolyte, characterized in that, The electrolyte containing potassium di-tert-butyl phosphate includes a solvent, a lithium salt, and potassium di-tert-butyl phosphate; the solvent includes EC and EMC; the lithium salt is lithium hexafluorophosphate. The electrolyte for repair contains EC, EMC, and potassium di-tert-butyl phosphate in a mass ratio of 9:21:10, and lithium hexafluorophosphate at a concentration of 1 mol / L.
9. The application of potassium di-tert-butyl phosphate according to claim 5 in lithium-ion battery electrolyte, characterized in that, The potassium di-tert-butyl phosphate is added directly to the lithium-ion battery electrolyte.