Fast-charging electrolyte for lithium ion battery and preparation method thereof

Abstract

The application discloses a fast-charging electrolyte for lithium ion batteries and a preparation method thereof, and relates to the technical field of lithium batteries. The fast-charging electrolyte is composed of lithium salt, solvent, diluent and additive; the lithium salt is lithium bistrifluoromethanesulfonylimide and lithium difluoro(oxalato)borate, the solvent is acetonitrile and 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane, the diluent contains methyl nonafluorobutyl ether and fluorinated ether, and the additive contains silane modified composite nano oxide, lithium nitrate, lithium difluorophosphate, FEC and boron-containing / phosphorus-containing additives. The application can improve the flame retardance of the electrolyte, widen the electrochemical window, construct a stable composite SEI film in situ, inhibit lithium dendrites, and has the characteristics of high ionic conductivity, low polarization, fast-charging performance, long cycle life and high safety, and is suitable for fast-charging lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to fast-charging electrolytes for lithium-ion batteries and their preparation methods. Background Technology

[0002] In recent years, with the continuous development of lithium-ion battery technology, new energy vehicles have experienced rapid growth. However, the long charging time has limited the further market promotion of new energy vehicles, and charging experience has become one of the decision-making factors for consumers when purchasing them. Therefore, improving the charging speed of lithium-ion batteries has become one of its important development directions.

[0003] Traditional electrolytes (lithium hexafluorophosphate as the lithium salt and linear carbonates such as ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate as the solvent) are prone to dendrite formation and excessive heat generation during fast charging due to their low ionic conductivity and high desolvation barrier, leading to increased safety hazards and shortened lifespan. Currently, the fast-charging performance of electrolytes is mainly improved by increasing ionic conductivity, increasing lithium-ion transference number, lowering the lithium-ion desolvation barrier, and optimizing the SEI film. Locally concentrated fast-charging electrolytes using organic lithium salts / acetonitrile solvents have attracted considerable attention due to their high ionic conductivity, large lithium-ion transference number, and low desolvation barrier. However, acetonitrile's low flash point (closed cup, 6°C), its flammability, and the instability of the positive electrode interface under high voltage limit its application.

[0004] Therefore, developing a fast-charging electrolyte for lithium-ion batteries that combines high ionic conductivity, high flame retardancy, interface stability, and long cycle life has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a fast-charging electrolyte for lithium-ion batteries and its preparation method. Adding 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane to acetonitrile solvent not only improves the flame retardancy of the electrolyte but also broadens the oxidation window voltage to 5.2V, while having minimal impact on the electrolyte viscosity. Simultaneously, using composite modified nano-oxides as additives allows for the in-situ formation of a Li4SiO5-Li2TiO3 / LiAlO2 composite SEI film on the negative electrode surface. This improves ionic conductivity while enhancing the mechanical strength and thermal stability of the SEI film, significantly suppressing lithium dendrite formation and improving cycle life.

[0006] The technical solution of this invention is as follows: On one hand, the present invention provides a fast-charging electrolyte for lithium-ion batteries, comprising a lithium salt, a solvent, a diluent, and additives; wherein the lithium salt is composed of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluorooxalate borate (LiDFOB); the solvent is a mixed solvent of acetonitrile (AN) and 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane (FDMB); the diluent comprises a first diluent and a second diluent, the first diluent being methyl nonafluorobutyl ether (MFE), and the second diluent being perfluorobutyl methyl ether (PFBE) and 1,1,2,2-tetrafluoroethyl ether. One or more of methyl ether (TFEME) and bis(2,2,2-trifluoroethyl) ether (BTFE); the additive consists of composite modified nano-oxide, lithium nitrate, lithium difluorophosphate, fluoroethylene carbonate (FEC) and boron-containing / phosphorus-containing auxiliaries, wherein the composite modified nano-oxide is a first oxide and a second oxide modified with a silane coupling agent, the first oxide being SiO2 and the second oxide being one or two of TiO2 and Al2O3; the boron-containing / phosphorus-containing auxiliaries are one or two of lithium bis(oxalate-borate) and tri(2,2,2-trifluoroethyl) phosphite.

[0007] Preferably, in the fast charging electrolyte, the concentration of lithium bis(trifluoromethanesulfonyl)imide is 1-1.5M and the concentration of lithium difluorooxalateborate is 0.2-0.5M.

[0008] Preferably, in the mixed solvent, the volume percentage of acetonitrile is 60-80%, and the volume percentage of 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane is 20-40%.

[0009] Preferably, the first diluent accounts for 10-30% of the total volume of the solvent and diluent, and the second diluent accounts for 1-10% of the total volume of the solvent and diluent.

[0010] Preferably, based on the mass of the fast-charging electrolyte, the additives contain 0.1-2% of the first oxide, 0.1-1% of the second oxide, 0.1-2% of the lithium nitrate, 0.1-2% of the lithium difluorophosphate, 0.1-5% of the fluoroethylene carbonate, and 0.1-2% of the boron- or phosphorus-containing additives.

[0011] Preferably, the preparation method of the composite modified nano-oxide is as follows: the first oxide and the second oxide are dispersed in anhydrous ethanol, a silane coupling agent is added, and the mixture is refluxed at 60-80℃ for 3-5 hours. After centrifugation, washing and drying, the composite modified nano-oxide is obtained.

[0012] Preferably, the particle size of the first oxide and the second oxide is 5-30 nm.

[0013] Preferably, the silane coupling agent is KH-550.

[0014] Preferably, the total mass ratio of the first oxide and the second oxide to the silane coupling agent is 1:(0.01-0.1).

[0015] On the other hand, the present invention provides a method for preparing the above-mentioned fast-charging electrolyte for lithium-ion batteries. In an argon-filled glove box, a diluent, lithium salt, lithium nitrate, lithium difluorophosphate, fluoroethylene carbonate, and boron / phosphorus-containing additives are added sequentially to a solvent and stirred until completely dissolved. Then, composite modified nano-oxides are added and stirred to obtain an electrolyte. The electrolyte is then placed into a sealed bottle, sealed with a vacuum sealing bag, transferred outside the glove box, and dispersed by pulsed ultrasonication in an ice bath environment to obtain a fast-charging electrolyte.

[0016] This invention, through the synergistic design of a specific lithium salt, fluorinated mixed solvent, composite diluent, and composite additive system, yields a fast-charging electrolyte with high ionic conductivity, low viscosity, high flame retardancy, wide electrochemical window, interface stability, excellent fast-charging performance, long cycle life, and high safety. Compared with existing technologies, it has the following significant technical advantages: 1. This invention uses a mixed solvent of acetonitrile and FDMB. FDMB has a high flash point (>80℃) and good flame retardancy, which significantly improves the flame retardant performance of the electrolyte and reduces the safety risks caused by heat generation during fast charging. At the same time, FDMB has a relatively low viscosity (about 0.6 cP), and the overall viscosity increases only slightly after being compounded with acetonitrile, which has little impact on ionic conductivity, thus balancing high-rate conduction and low polarization. The fluorinated structure can broaden the electrochemical window of the electrolyte to 5.2 V, making it compatible with high-voltage cathode materials and meeting the requirements of high-energy-density fast-charging batteries.

[0017] 2. This invention uses a composite lithium salt of LiTFSI and LiDFOB: LiTFSI provides high ionic conductivity and high concentration stability, while LiDFOB promotes the formation of a dense, stable, boron-containing SEI film, reduces interfacial impedance, suppresses side reactions, and improves cycle stability. The two work synergistically to significantly improve ion conduction efficiency and interfacial stability during fast charging.

[0018] 3. This invention modifies the SiO2-TiO2 / Al2O3 composite nano-oxide with a silane coupling agent, enabling the in-situ formation of a Li4SiO5-Li2TiO3 / LiAlO2 composite SEI film on the negative electrode surface. Li4SiO5 exhibits superior ionic conductivity, mechanical strength, dendrite suppression ability, and high-temperature stability compared to traditional SEI films (LiF / Li2CO3), thereby accelerating lithium-ion migration and improving fast-charging performance. Li2TiO3 / LiAlO2 further enhances the mechanical strength and thermal stability of the SEI film, effectively suppressing lithium dendrite growth, SEI film rupture, and side reactions, significantly improving fast-charging cycle life.

[0019] 4. This invention introduces boron- and phosphorus-containing additives, which can form a dense flame-retardant protective layer containing B / P at high temperatures, achieving both flame retardancy and interface stabilization, reducing heat generation, improving thermal stability, and further enhancing safety. At the same time, it synergistically promotes the formation of Li3N with lithium nitrate, forming multiple composite interfaces with the Li4SiO5-Li2TiO3 / LiAlO2 composite SEI film, further improving the ionic conductivity of the negative electrode interface, reducing interface impedance, and improving fast charging performance and cycle stability.

[0020] 5. This invention employs a composite diluent of MFE+PFBE / TFEME / BTFE, wherein MFE exhibits good chemical stability, which is beneficial for high-pressure stability and long-term cycling; PFBE has low viscosity, high flame retardancy, and good interfacial compatibility; TFEME has a small molecular weight and low viscosity, resulting in excellent performance at low temperatures and high rates; and BTFE has low volatility, is process-friendly, and facilitates the formation of a stable interfacial film. This composite diluent system can significantly improve the overall performance of the electrolyte. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0022] Example 1 The preparation method of the fast-charging electrolyte for lithium-ion batteries in this embodiment is as follows: Preparation of composite modified nano-oxides: 6g of SiO2 with a particle size of 5nm and 0.3g of TiO2 with a particle size of 15nm were selected and dispersed in 56.7g of anhydrous ethanol; 0.315g of silane coupling agent KH-550 was added, and the mixture was refluxed at 70℃ for 4h. After centrifugation, washing and drying, aminated SiO2 and TiO2 were obtained, which are the composite modified nano-oxides.

[0023] The electrolyte was prepared in an argon-filled glove box: 22.45 g of acetonitrile and 20.57 g of 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane were mixed to obtain a mixed solvent. Then, 19.3 g of methyl nonafluorobutyl ether and 4.79 g of perfluorobutyl methyl ether were added for dilution. Next, 18.22 g of LiTFSI and 4.56 g of LiDFOB were added, followed by 1 g of lithium nitrate, 1 g of lithium difluorophosphate, 5 g of FEC, 0.5 g of lithium bis(oxalate-borate), and 0.5 g of tris(2,2,2-trifluoroethyl) phosphite, and the mixture was stirred until completely dissolved. Then, 2.1 g of the composite modified nano-oxide was added and stirred for 30 min. The resulting electrolyte was poured into a sealed bottle, sealed with a vacuum bag, and transferred outside the glove box. Pulsed ultrasonic dispersion was performed in an ice bath environment for 30 min at a power of 300 W, with a 5 s working time followed by a 2 s interval, to obtain a fast-charging electrolyte.

[0024] Example 2 The preparation method of the fast-charging electrolyte for lithium-ion batteries in this embodiment is as follows: Preparation of composite modified nano-oxides: 3g of SiO2 with a particle size of 15nm and 1.5g of TiO2 with a particle size of 30nm were selected and dispersed in 40.5g of anhydrous ethanol; 0.045g of silane coupling agent KH-550 was added, and the mixture was refluxed at 60℃ for 5h. After centrifugation, washing and drying, aminated SiO2 and TiO2 were obtained, which are the composite modified nano-oxides.

[0025] The electrolyte was prepared in an argon-filled glove box: 27.6 g of acetonitrile and 9.48 g of 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane were mixed to obtain a mixed solvent. Then, 29.01 g of methyl nonafluorobutyl ether, 0.48 g of perfluorobutyl methyl ether, and 0.41 g of 1,1,2,2-tetrafluoroethyl methyl ether were added for dilution. Next, 27.39 g of LiTFSI and 1.83 g of LiDFOB were added, followed by 0.1 g of lithium nitrate, 2 g of lithium difluorophosphate, 0.1 g of FEC, and 0.1 g of lithium bis(oxalate-borate), and the mixture was stirred until completely dissolved. Then, 1.5 g of the composite modified nano-oxide was added and stirred for 30 min. The resulting electrolyte was poured into a sealed bottle, sealed using a vacuum sealing bag, and transferred outside the glove box. Pulsed ultrasonic dispersion was performed in an ice bath environment for 30 min at a power of 300 W, with a 5 s working time followed by a 2 s interval, to obtain a fast-charging electrolyte.

[0026] Example 3 The preparation method of the fast-charging electrolyte for lithium-ion batteries in this embodiment is as follows: Preparation of composite modified nano-oxides: 0.3g of SiO2 with a particle size of 30nm, 1.5g of TiO2 with a particle size of 5nm and 1.5g of Al2O3 with a particle size of 15nm were selected and dispersed in 29.7g of anhydrous ethanol; 0.33g of silane coupling agent KH-550 was added, and the mixture was refluxed at 80℃ for 3h. After centrifugation, washing and drying, aminated SiO2, TiO2 and Al2O3 were obtained, which are the composite modified nano-oxides.

[0027] The electrolyte was prepared in an argon-filled glove box: 29.28 g of acetonitrile and 17.24 g of 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane were mixed to obtain a mixed solvent. Then, 10.11 g of methyl nonafluorobutyl ether, 4.02 g of perfluorobutyl methyl ether, 2.58 g of 1,1,2,2-tetrafluoroethyl methyl ether, and 2.8 g of bis(2,2,2-trifluoroethyl) ether were added for dilution. Then, 22.91 g of LiTFSI and 2.87 g of LiDFOB were added, followed by 2 g of lithium nitrate, 0.1 g of lithium difluorophosphate, 3 g of FEC, 1 g of lithium bis(oxalate-borate), and 1 g of tris(2,2,2-trifluoroethyl) phosphite, and the mixture was stirred until completely dissolved. Then, 1.1 g of the composite modified nano-oxide was added and stirred for 30 min. The resulting electrolyte was poured into a sealed bottle, sealed using a vacuum sealing bag, and transferred outside the glove box. The fast-charging electrolyte was obtained by pulsed ultrasonic dispersion for 30 minutes in an ice bath environment with an ultrasonic power of 300W, a working time of 5 seconds and an interval of 2 seconds.

[0028] Comparative Example 1 The difference from Example 1 is that 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane solvent is not added.

[0029] Comparative Example 2 The difference from Example 1 is that no composite modified nano-oxide is added.

[0030] Comparative Example 3 The difference from Example 1 is that equimolar LiTFSI is used instead of LiDFOB.

[0031] Comparative Example 4 The difference from Example 1 is that an equal volume of methyl nonafluorobutyl ether is used instead of perfluorobutyl methyl ether.

[0032] Comparative Example 5 The difference from Example 1 is that lithium bis(oxalate)borate and tris(2,2,2-trifluoroethyl) phosphite are not added.

[0033] Comparative Example 6 The difference from Example 1 is that no aminated TiO2 is added to the composite modified nano-oxide.

[0034] The flame retardancy of the electrolytes prepared in Examples 1-3 and Comparative Examples 1-6 was characterized using the self-extinguishing time method. At 25°C, uniform ceramic fiber paper was selected as the electrolyte carrier. The self-extinguishing time per unit weight of electrolyte was calculated by measuring the weight of the adsorbed electrolyte and the combustion time. A shorter self-extinguishing time indicates a more flammable electrolyte; a longer self-extinguishing time indicates better flame retardancy.

[0035] A simulated battery was assembled and tested using a 2032 button cell casing. A 20μm thick separator was clamped between two 1mm thick, 15mm diameter stainless steel spacers, and electrolyte was dropped into the separator to completely wet it. The electrochemical window of the electrolyte was tested using cyclic voltammetry at 25°C, the ionic conductivity of the electrolyte was tested using AC impedance spectroscopy, and the viscosity of the electrolyte was tested using rotational viscometer.

[0036] A 5Ah lithium iron phosphate pouch battery was fabricated. At 25℃, the empty battery was charged to 3.65V at a constant current of 25A. The ratio of the 25A constant current charging capacity to the rated capacity was calculated, which is the 5C charging capacity ratio. Simultaneously, a 1C cycle life test was performed on the battery. The test results are shown in Table 1. Table 1 Performance test results of the electrolytes in Examples 1-3 and Comparative Examples 1-6

[0037] As shown in Table 1, the fast-charging electrolytes prepared in Examples 1-3 exhibit a longer self-extinguishing time, higher ionic conductivity, and a 5C charging capacity exceeding 85% of the rated capacity, demonstrating good fast-charging capability. It can also be seen that with increasing proportions of 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane, the self-extinguishing time and electrochemical window of the fast-charging electrolytes prepared in Examples 1-3 increase, but the viscosity change is relatively small. This indicates that 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane not only improves the flame retardancy of the electrolyte but also broadens the oxidation window voltage to 5.2V, with minimal impact on the electrolyte viscosity. Although 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane slightly reduces the ionic conductivity of the electrolyte, it has little impact on the rate-charging performance.

[0038] Compared to Example 1, Comparative Example 1 did not include 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane solvent. The self-extinguishing time of the electrolyte was significantly reduced, indicating more intense combustion, demonstrating that 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane solvent can effectively improve the flame retardancy of the electrolyte. Furthermore, 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane has a relatively low viscosity, resulting in a small increase in the overall viscosity of the mixed solvent after blending with acetonitrile, with minimal impact on ionic conductivity. This balances high-rate conductivity with low polarization, and the fluorinated structure also broadens the electrochemical window of the electrolyte.

[0039] Compared to Example 1, Comparative Example 2 did not include the composite modified nano-oxide. The ionic conductivity of the electrolyte decreased slightly. This is because the surface of the composite modified nano-oxide is positively charged, which can weakly adsorb anions, locally reducing the degree of cation-anion pairing and slightly increasing the number of free lithium ions. At the same time, the rate charging performance and cycle performance of the battery both decreased, indicating that the composite modified nano-oxide can form a Li4SiO5-Li2TiO3 composite SEI film in situ on the negative electrode surface. While improving the ionic conductivity, it also enhances the mechanical strength and thermal stability of the SEI film, thereby improving the fast charging performance and cycle performance.

[0040] Compared to Example 1, Comparative Example 3 did not include LiDFOB lithium salt. The ionic conductivity of the electrolyte was relatively lower, and the rate charging performance and cycle performance of the battery were correspondingly reduced. This is because LiDFOB can promote the formation of a dense, stable, boron-containing SEI film, reduce interfacial impedance, suppress side reactions, improve cycle stability, and significantly enhance ion conduction efficiency and interfacial stability during fast charging.

[0041] Compared to Example 1, Comparative Example 4 used only methyl nonafluorobutyl ether as a diluent. Methyl nonafluorobutyl ether has a high fluorine content, good chemical stability, which is beneficial for high-voltage stability and long cycling, and a longer self-extinguishing time. However, its low ionic conductivity reduces its rate charging performance. This is because perfluorobutyl methyl ether (PFME) has low viscosity, high flame retardancy, and good interfacial compatibility, which can improve the ionic conductivity of the electrolyte. The composite diluent of methyl nonafluorobutyl ether and PFME used in Example 1 can significantly improve the overall performance of the electrolyte.

[0042] Compared to Example 1, Comparative Example 5 did not include boron / phosphorus additives. The electrolyte had a shorter self-extinguishing time, resulting in relatively lower battery cycle performance. This is because boron / phosphorus additives can form a dense, B / P-containing flame-retardant protective layer on the electrode surface, providing both flame retardancy and interfacial stability, reducing heat generation, and improving thermal stability, thereby enhancing battery cycle performance. Furthermore, the boron / phosphorus additives undergo thermal dehydration and cross-linking to form an expanded carbon layer, which to some extent inhibits the release of flammable volatile products.

[0043] Compared to Example 1, Comparative Example 6 did not include aminated TiO2 in the composite modified nano-oxide. The rate charging performance and cycle performance of the battery both decreased slightly. This indicates that the addition of aminated TiO2 can form a Li4SiO5-Li2TiO3 composite SEI film with SiO2. Li2TiO3 can further enhance the mechanical strength and thermal stability of the SEI film, effectively suppress lithium dendrite growth, SEI film rupture and side reactions, and significantly improve fast-charging cycle life.

Claims

1. A fast-charging electrolyte for lithium-ion batteries, characterized in that, The product comprises lithium salt, solvent, diluent, and additives; wherein the lithium salt is composed of lithium bis(trifluoromethanesulfonyl)imide and lithium difluorooxalate borate; the solvent is a mixed solvent of acetonitrile and 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane; the diluent includes a first diluent and a second diluent, wherein the first diluent is methyl nonafluorobutyl ether and the second diluent is one or more of perfluorobutyl methyl ether, 1,1,2,2-tetrafluoroethyl methyl ether, and bis(2,2,2-trifluoroethyl) ether; the additives consist of composite modified nano-oxides, lithium nitrate, lithium difluorophosphate, fluoroethylene carbonate, and boron / phosphorus-containing auxiliaries, wherein the composite modified nano-oxides are a first oxide and a second oxide modified with a silane coupling agent, wherein the first oxide is SiO2 and the second oxide is one or two of TiO2 and Al2O3; the boron / phosphorus-containing auxiliaries are one or two of lithium bis(oxalate borate) and tris(2,2,2-trifluoroethyl) phosphite.

2. The fast-charging electrolyte for lithium-ion batteries as described in claim 1, characterized in that, In the fast-charging electrolyte, the concentration of lithium bis(trifluoromethanesulfonyl)imide is 1-1.5M, and the concentration of lithium difluorooxalateborate is 0.2-0.5M.

3. The fast-charging electrolyte for lithium-ion batteries as described in claim 1, characterized in that, In the mixed solvent, the volume percentage of acetonitrile is 60-80%, and the volume percentage of 1,1,1-trifluoro-2-(2-methoxyethoxy)ethane is 20-40%.

4. The fast-charging electrolyte for lithium-ion batteries as described in claim 1, characterized in that, The first diluent accounts for 10-30% of the total volume of solvent and diluent, and the second diluent accounts for 1-10% of the total volume of solvent and diluent.

5. The fast-charging electrolyte for lithium-ion batteries as described in claim 1, characterized in that, Based on the mass of the fast-charging electrolyte, the additives contain 0.1-2% of the first oxide, 0.1-1% of the second oxide, 0.1-2% of lithium nitrate, 0.1-2% of lithium difluorophosphate, 0.1-5% of fluoroethylene carbonate, and 0.1-2% of boron- or phosphorus-containing additives.

6. The fast-charging electrolyte for lithium-ion batteries as described in claim 1, characterized in that, The preparation method of the composite modified nano-oxide is as follows: the first oxide and the second oxide are dispersed in anhydrous ethanol, a silane coupling agent is added, and the mixture is refluxed at 60-80℃ for 3-5 hours. After centrifugation, washing and drying, the composite modified nano-oxide is obtained.

7. The fast-charging electrolyte for lithium-ion batteries as described in claim 6, characterized in that, The particle size of the first oxide and the second oxide is 5-30 nm.

8. The fast-charging electrolyte for lithium-ion batteries as described in claim 6, characterized in that, The silane coupling agent is KH-550.

9. The fast-charging electrolyte for lithium-ion batteries as described in claim 6, characterized in that, The total mass ratio of the first oxide and the second oxide to the silane coupling agent is 1:(0.01-0.1).

10. The method for preparing the fast-charging electrolyte for lithium-ion batteries according to any one of claims 1-9, characterized in that, In an argon-filled glove box, diluent, lithium salt, lithium nitrate, lithium difluorophosphate, fluoroethylene carbonate, and boron / phosphorus-containing additives were added sequentially to the solvent and stirred until completely dissolved. Then, composite modified nano-oxides were added and stirred to obtain an electrolyte. The electrolyte was placed into a sealed bottle, sealed with a vacuum bag, and transferred outside the glove box. It was then dispersed by pulsed ultrasonication in an ice bath environment to obtain a fast-charging electrolyte.

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