Fluorinated eutectic gel electrolyte for lithium battery and preparation method of fluorinated eutectic gel electrolyte
By adopting fluorinated eutectic gel electrolyte in lithium batteries, the problems of electrolyte leakage and interface instability in lithium battery systems are solved through in-situ thermal polymerization technology, and higher safety and battery performance are achieved.
Patent Information
- Application Number
- CN202510234249.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-05-27
AI Technical Summary
In existing lithium battery systems, liquid electrolytes are prone to leakage, combustion and even explosion, resulting in safety problems, and eutectic gel electrolytes have challenges in interface stability and reaction kinetics.
Using a fluorinated eutectic gel electrolyte, by mixing a fluorinated amide solid with a solid lithium salt to form a homogeneous eutectic precursor solution, and performing in-situ thermal polymerization in the battery cell, an electrolyte with a stable SEI layer and low binding energy was prepared.
This electrolyte can form a stable SEI layer on the lithium metal negative electrode, promote the compactness of lithium deposition, prevent the growth of lithium dendrites, significantly enhance the reaction kinetics, and improve the cycling capacity and capacity retention rate of the battery.
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Figure CN120048989A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of lithium - ion batteries, and particularly to a fluorinated eutectic gel electrolyte for lithium batteries and a preparation method thereof. Background Art
[0002] The information disclosed in the background art of the present invention is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or an indication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.
[0003] Due to its great potential in achieving high energy density, lithium batteries have become a research hotspot for next - generation rechargeable batteries. However, the currently commonly used battery system with a lithium - metal anode and a liquid electrolyte has serious safety problems. The electrolyte is prone to leakage, combustion, or even explosion, which limits its practical application. Therefore, it is particularly important to develop solid - state or quasi - solid - state electrolytes with high ionic conductivity, excellent interfacial stability, a wide electrochemical window, and high safety, aiming to balance the requirements of safety and performance.
[0004] Among various electrolyte systems, the eutectic gel electrolyte (DEGE) is a non - flowable material formed by fixing a eutectic electrolyte (DEE) within a polymer framework. It has excellent electrochemical properties, including a relatively high ionic conductivity at room temperature, a wide electrochemical window, good thermal stability, and characteristics of being non - volatile and non - flammable. These advantages stem from its precursor, the eutectic electrolyte (DEE), which is a eutectic mixture formed by the interaction of a hydrogen - bond acceptor (HBA) and a hydrogen - bond donor (HBD). Compared with single components, DEE reduces the melting point through intermolecular hydrogen - bond interactions, enabling a mixture of two solid components to remain liquid at room temperature. Currently, DEGEs based on different HBAs (such as LiTFSI and LiDFOB), HBDs (such as succinonitrile and amide), and polymer matrices (such as pentaerythritol tetraacrylate) have been developed. However, due to the complex interaction between DEGE and lithium metal, the fragile solid - electrolyte interface (SEI) is prone to rupture during the lithium deposition / stripping process, resulting in the consumption of active lithium and the electrolyte, significantly shortening the battery life. In addition, the binding energy of HBD with Li + is significantly higher than that of traditional solvents, increasing the desolvation barrier of Li + and severely hindering the reaction kinetics in lithium - metal batteries. Therefore, DEGE still faces great challenges in terms of interfacial stability and reaction kinetics. Summary of the Invention
[0005] In view of this, the present invention provides a fluorinated eutectic gel electrolyte for lithium batteries and a preparation method thereof. The fluorinated eutectic gel electrolyte provided by the present invention can form a stable SEI layer on the lithium metal anode, promote the compactness of lithium deposition, and prevent the growth of lithium dendrites. At the same time, the binding energy between the molecule and Li + is reduced, and the desolvation process is accelerated, thereby significantly enhancing the reaction kinetics in the lithium metal battery, improving the cycle ability and capacity retention rate of the battery, and having broad application prospects.
[0006] In a first aspect, the present invention provides a preparation method of a fluorinated eutectic gel electrolyte for lithium batteries, comprising the following steps:
[0007] Mix a fluorinated amide solid with a solid lithium salt to form a homogeneous eutectic precursor solution;
[0008] Add an initiator and a high-pressure resistant polymerizable monomer to the homogeneous eutectic precursor solution to obtain a second precursor solution;
[0009] Inject the second precursor solution into the battery cell and let it stand for in-situ thermal polymerization to obtain the product.
[0010] In a second aspect, the present invention provides a fluorinated eutectic gel electrolyte for lithium batteries prepared by the above preparation method.
[0011] In a third aspect, the present invention provides a lithium metal battery comprising the above fluorinated eutectic gel electrolyte for lithium batteries.
[0012] Compared with the prior art, the present invention has achieved the following beneficial effects:
[0013] (1) The present invention prepares a fluorinated amide-based eutectic gel electrolyte matching a lithium metal battery (LMB) with a simple preparation method and raw materials. The fluorinated amide forms a stable SEI rich in LiF and Li 3 N between the lithium metal anode and DEGE, which helps to deposit lithium uniformly and compactly on the interface, effectively prevents the growth of lithium dendrites, protects the anode, and improves the interface stability.
[0014] (2) For the fluorinated amide-based eutectic gel electrolyte designed by the present invention, the electrolyte molecule and Li + achieve a lower binding energy, which can accelerate desolvation and significantly enhance the reaction kinetics in the LMB.
[0015] (3) The eutectic gel electrolyte prepared by the present invention has excellent non-flammability and high ionic conductivity at room temperature, which can be as high as 1.2 mS·cm -1 or more.
[0016] (4) The fluorinated deep eutectic gel electrolyte prepared by the present invention for lithium metal batteries can be matched with high-voltage, high-capacity cathodes and high-capacity anodes, and can be assembled into a solid-state battery with high room-temperature ionic conductivity, wide electrochemical window, good thermal stability, ultra-long stable cycling, and ultra-high capacity retention rate. The assembled Li||LFP button battery can still maintain a capacity retention rate of more than 95% after cycling 300 times at 80 °C and 2C. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0018] Figure 1 It is a diagram of the formation process and formation mechanism of the homogeneous deep eutectic precursor solution (DEE) in Example 1 of the present invention;
[0019] Figure 2 It is an optical picture (a) of the homogeneous deep eutectic precursor solution in a vial at room temperature and an optical picture (b) of the polymerized deep eutectic gel electrolyte in Example 1 of the present invention;
[0020] Figure 3 It is a diagram of the Coulombic efficiency test results of the Li||Cu half-cell assembled from the second homogeneous precursor solution in Example 1 of the present invention and obtained by in-situ thermal polymerization;
[0021] Figure 4 It is a cycling diagram of the Li||Li symmetric battery assembled from the second homogeneous precursor solutions in Examples 1, Comparative Examples 1-4 of the present invention and obtained by in-situ thermal polymerization at a constant current density of 0.2 mA·cm -2 ;
[0022] Figure 5 It is a constant potential floating test diagram of the Li||LFP button battery assembled from the second homogeneous precursor solution in Example 1 of the present invention and obtained by in-situ thermal polymerization at 3.8-5.0 V;
[0023] Figure 6 It is a charge-discharge specific capacity-voltage curve (a) and a discharge specific capacity-cycling diagram (b) of the Li||LFP button battery assembled from the second homogeneous precursor solution in Example 1 of the present invention and obtained by in-situ thermal polymerization at a 1C rate;
[0024] Figure 7 It is a room-temperature rate performance test diagram of the Li||LFP button battery assembled from the second homogeneous precursor solution in Example 1 of the present invention and obtained by in-situ thermal polymerization;
[0025] Figure 8 It is the long - cycle test chart of the Li||LFP button battery assembled from the second homogeneous precursor solution of Example 1 of the present invention and obtained by in - situ thermal polymerization at 80 °C under a 2C rate.
[0026] Figure 9 It is the rate performance test chart of the Li||LFP button battery assembled from the second homogeneous precursor solution of Example 1 of the present invention and obtained by in - situ thermal polymerization at 80 °C.
[0027] Figure 10 It is the charge - discharge specific capacity - voltage curve (a) and discharge specific capacity - cycle diagram (b) of the Li||LFP button battery assembled from the second homogeneous precursor solution of Comparative Example 1 of the present invention and obtained by in - situ thermal polymerization.
[0028] Figure 11 It is the charge - discharge specific capacity - voltage curve (a) and discharge specific capacity - cycle diagram (b) of the Li||LFP button battery assembled from the second homogeneous precursor solution of Comparative Example 2 of the present invention and obtained by in - situ thermal polymerization.
[0029] Figure 12 It is the charge - discharge specific capacity - voltage curve (a) and discharge specific capacity - cycle diagram (b) of the Li||LFP button battery assembled from the second homogeneous precursor solution of Comparative Example 3 of the present invention and obtained by in - situ thermal polymerization.
[0030] Figure 13 It is the charge - discharge specific capacity - voltage curve (a) and discharge specific capacity - cycle diagram (b) of the Li||LFP button battery assembled from the second homogeneous precursor solution of Comparative Example 4 of the present invention and obtained by in - situ thermal polymerization.
[0031] Figure 14 It is the cycle curve diagram of the 1Ah soft - pack battery assembled from the second homogeneous precursor solution of Example 1 of the present invention and obtained by in - situ thermal polymerization. Detailed Description of the Invention
[0032] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.
[0033] The present invention provides a preparation method of a fluorinated eutectic gel electrolyte for lithium batteries, comprising the following steps:
[0034] Mix a fluorinated amide solid with a solid lithium salt to form a homogeneous eutectic precursor solution;
[0035] An initiator and a high-pressure resistant polymerization monomer are added to the homogeneous eutectic precursor solution to obtain a second precursor solution;
[0036] The second precursor solution is injected into the battery cell and left standing for in-situ thermal polymerization to obtain the product.
[0037] In the present invention, a fluorinated amide solid is used as a hydrogen bond donor and a solid lithium salt is used as a hydrogen bond acceptor. After mixing the two, due to the hydrogen bond interaction between them, a homogeneous eutectic precursor solution can be formed. This solution has intrinsic advantages such as high thermal stability, wide voltage window, and high ionic conductivity. Then, an initiator and a high-pressure resistant polymerization monomer are added to the homogeneous eutectic precursor solution. The initiator can initiate the thermal polymerization of the high-pressure resistant polymerization monomer during the subsequent standing process to form a eutectic gel electrolyte, in which the high-pressure resistant polymer presents a cross-linked spatial network structure, and the homogeneous eutectic precursor solution fills the pores in its structure. Through the technical solution of the present invention, a fluorinated eutectic gel electrolyte with strong reaction kinetics can be prepared, which can match the lithium metal negative electrode, thereby realizing a solid-state battery with ultra-long stable cycling and ultra-high capacity retention rate.
[0038] In the present invention, the fluorinated amide solid is selected from one or more of 2,2,2-trifluoro-N-methylacetamide (C=Oα3F), 2,2-difluoro-N-methylacetamide (C=Oα2F), 2-fluoro-N-methylacetamide (C=Oα1F), 3,3-difluoro-N-methylpropanamide (C=Oβ2F), 3-fluoro-N-methylpropanamide (C=Oβ1F), N-(trifluoromethyl)acetamide (N-Hα3F), N-(difluoromethyl)acetamide (N-Hα2F), N-(fluoromethyl)acetamide (N-Hα1F), N-(2,2,2-trifluoroethyl)acetamide (N-Hβ3F), N-(2,2-difluoroethyl)acetamide (N-Hβ2F), or N-(2-fluoroethyl)acetamide (N-Hβ1F), and most preferably 2,2,2-trifluoro-N-methylacetamide. The present invention finds that the type of fluorinated amide has a great influence on the performance of the obtained electrolyte.
[0039] In the present invention, the solid lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium difluoro(oxalato)borate (LiDFOB), or lithium tetrafluoroborate (LiBF 4 )), and most preferably lithium bis(trifluoromethanesulfonyl)imide.
[0040] In the present invention, the molar ratio of the fluorinated amide solid to the solid lithium salt is (50-90):(10-50), and more preferably (80-86):(14-20).
[0041] In the present invention, the initiator is an azo thermal initiator, and preferably azobisisobutyronitrile (AIBN) in the present invention. The high-pressure resistant polymerization monomers in the present invention are a mixed monomer of diallyl carbonate (DAC), ethylene carbonate (VEC) and N,N-methylenebisacrylamide (MBA) or a mixed monomer of polyethylene glycol diacrylate (PEGDA) and butyl acrylate (BA). After polymerization, a DAC-VEC-MBA copolymer or a PEGDA-BA copolymer can be formed, and preferably a PEGDA-BA copolymer is formed in the present invention.
[0042] In the second precursor solution of the present invention, the mass fraction of the homogeneous eutectic precursor solution is 84-98.4 wt%, more preferably 90-98.4 wt%; the mass fraction of the initiator is 0.1-1 wt%, more preferably 0.1-0.2 wt%; the mass fraction of the high-pressure resistant polymerization monomer is 1.5-15 wt%, more preferably 1.5-9.9 wt%.
[0043] In the present invention, the temperature of the in-situ thermal polymerization is 55-120 °C, more preferably 60-80 °C; the time of the in-situ thermal polymerization is 30-200 min; more preferably 30-60 min.
[0044] The present invention also provides a fluorinated eutectic gel electrolyte for lithium batteries prepared by the above preparation method. In the present invention, a stable SEI rich in LiF and Li 3 N is formed between the lithium metal anode and the eutectic gel electrolyte, which helps to form uniform and compact lithium deposition on the interface, effectively prevents the growth of lithium dendrites, protects the anode, and improves the interface stability; at the same time, the binding energy between the electrolyte molecules and Li + is relatively low, which can accelerate the desolvation and significantly enhance the reaction kinetics in the lithium metal anode.
[0045] The present invention also provides a lithium metal battery including the above fluorinated eutectic gel electrolyte for lithium batteries.
[0046] The present invention does not impose special restrictions on the cathode material of the above lithium metal battery, including but not limited to any one of lithium iron phosphate, nickel cobalt manganese-based, and lithium cobalt oxide. The present invention also does not impose special restrictions on the anode of the lithium metal battery, including but not limited to any one of high-capacity lithium metal, lithium-based alloy, and silicon carbon.
[0047] The technical solution of the present invention will be further elaborated below in conjunction with specific embodiments. The present invention does not impose special restrictions on the sources of the reagents used in the following embodiments, and commercially available products well-known to those skilled in the art can be used.
[0048] Example 1
[0049] This embodiment provides a fluorinated eutectic gel electrolyte for a lithium metal battery and a preparation method thereof.
[0050] (1) In a glove box filled with argon, 0.54 g of the lithium salt LiTFSI and 0.96 g of 2,2,2-trifluoro-N-methylacetamide (C=Oα3F) were mixed to form a homogeneous eutectic precursor solution (DEE).
[0051] (2) 30 mg of a mixed monomer of PEGDA and BA (mass ratio 1:1.25) and 2.0 mg of the initiator AIBN were added to the eutectic precursor solution, and after stirring evenly, a second homogeneous precursor solution was obtained.
[0052] (3) The second homogeneous precursor solution was placed in a vial and in-situ thermal polymerization was carried out in an oven at 80 °C for 40 minutes to obtain a eutectic gel electrolyte (DEGE), and an optical photo was taken.
[0053] Figure 1 Shows the formation process and formation mechanism of the homogeneous eutectic precursor solution (DEE) in Example 1. Figure 2 Shows the optical picture (a) of the homogeneous eutectic precursor solution in the vial at room temperature in Example 1 and the optical picture (b) of the eutectic gel electrolyte after polymerization, and it can be seen that the preparation of the fluorinated eutectic electrolyte and the polymerization of the gel electrolyte are completed.
[0054] Comparative Example 1
[0055] Compared with Example 1, the difference in this comparative example is that N-methylacetamide (NMA) is used to replace 2,2,2-trifluoro-N-methylacetamide.
[0056] Comparative Example 2
[0057] Compared with Example 1, the difference in this comparative example is that N-(trifluoromethyl)acetamide (N-Hα3F) is used to replace 2,2,2-trifluoro-N-methylacetamide.
[0058] Comparative Example 3
[0059] Compared with Example 1, the difference in this comparative example is that 3,3,3-trifluoro-N-methylpropanamide (C=Oβ3F) is used to replace 2,2,2-trifluoro-N-methylacetamide.
[0060] Comparative Example 4
[0061] Compared with Example 1, the difference in this comparative example is that N-(2,2,2-trifluoroethyl)acetamide (N-Hβ3F) is used to replace 2,2,2-trifluoro-N-methylacetamide.
[0062] Test Example
[0063] 1. Li||Cu half-cell Coulombic efficiency test:
[0064] Assemble the Li||Cu half-cell with the second homogeneous precursor solution in step (2) of Example 1. The positive electrode is copper foil (Cu), and the negative electrodes are all Li sheets with a diameter of 14 mm and a thickness of 150 μm. Assemble the Li||Cu half-cell and conduct the Coulombic efficiency test. The dosage of the second homogeneous precursor solution is 50 μL. After the battery is assembled with a pressure of 0.65 tons, it is left standing in an 80 °C oven for 40 minutes until in-situ thermal polymerization is completed. The separator is a 16-μm-thick polypropylene separator, and the injection tool is a pipette gun with a measuring range of 100 μL. Conduct EIS on an Autolab302N electrochemical workstation, with a frequency range of 10 -1 ~10 6 Hz and a perturbation amplitude of 10 mV.
[0065] Figure 3 Figure showing the Coulombic efficiency test results of the Li||Cu half-cell in Example 1 using the Aurbach method. The Coulombic efficiency can reach 98.7%.
[0066] 2. Li||Li symmetric battery
[0067] Assemble the Li||Li symmetric battery with the second homogeneous precursor solutions in Example 1 and Comparative Examples 1-4. Assemble the Li||Li symmetric battery with both the positive and negative electrodes being Li sheets with a diameter of 14 mm and a thickness of 150 μm to conduct the long-cycle stability test. The dosage of the second homogeneous precursor solution is 50 μL. The battery case is a commercial CR2032. After the battery is assembled with a pressure of 0.65 tons, it is left standing in an 80 °C oven for 40 minutes until in-situ thermal polymerization is completed. The separator is a 16-μm-thick polypropylene separator, and the injection tool is a pipette gun with a measuring range of 100 μL. After assembly, cycle at a constant current density of 0.2 mA·cm -2 constant current density.
[0068] Figure 4 Figure showing the comparison of constant current for the Li||Li symmetric batteries assembled in Example 1 and Comparative Examples 1-4. As can be seen from the figure, at 0.2 mA·cm -2 it maintains its performance for more than 3000 hours, with the minimum polarization, demonstrating excellent lithium metal interface compatibility. Other fluorinated amides also show better cycle stability compared to non-fluorinated amides. -2
[0069] 3. Li||LFP button battery
[0070] Assemble the Li||LFP button battery with the second homogeneous precursor solutions in Example 1 and Comparative Examples 1-4. The positive electrode is a disk with a diameter of 10 mm and a loading of 4.0 mg·cm-2 Lithium iron phosphate (LFP), with a negative electrode being a Li sheet with a diameter of 14 mm and a thickness of 150 μm, was used to assemble a Li||LFP button battery for potentiostatic floating tests, charge-discharge cycle tests, and rate performance tests. The amount of the second homogeneous precursor solution was 50 μL. The battery case was a commercial CR2032. After assembly with a pressure of 0.65 tons, the battery was left standing in an 80°C oven for 40 minutes until in-situ thermal polymerization was completed. The separator was a 16-μm-thick polypropylene separator. The injection tool was preferably a pipette gun with a measuring range of 100 μL.
[0071] The Li||LFP button battery for potentiostatic floating tests was evaluated for its electrochemical window through potentiostatic floating tests at 3.8 - 5.0 V after assembly.
[0072] Figure 5 Figure of the potentiostatic floating test of the Li||LFP button battery of Example 1 at 3.8 - 5.0 V. Under voltage floating, the battery showed negligible leakage current density, demonstrating the compatibility of the eutectic electrolyte with LFP and the potential for pairing with other high-voltage cathode materials.
[0073] The Li||LFP button battery for charge-discharge cycle tests was activated at a rate of 0.1C for 3 cycles after assembly, and then charge-discharge cycles were carried out at 0.1C and 1C respectively. 1C corresponds to 171 mAh / g. Figure 6 Figure of the long-cycle test of the Li||LFP button battery in Example 1 at a rate of 1C. Its initial discharge capacity was approximately 140 mAh / g, and the capacity retention rate after 2500 cycles was 81.7%, showing excellent stable cycling ability and capacity retention rate.
[0074] The Li||LFP button battery for rate performance tests was subjected to rate performance tests at 0.1C, 0.2C, 0.5C, 1C, 2C, and 5C respectively after assembly. Figure 7 Figure of the rate performance test of the Li||LFP button battery of Example 1 at room temperature (25°C). The figure shows excellent rate performance, and a specific capacity of 104 mAh / g can also be provided at 5C.
[0075] The Li||LFP button battery of Example 1 was used for high-temperature charge-discharge cycle tests. After assembly, it was activated at a rate of 0.1C and charge-discharge cycles were carried out at 2C. Figure 8Long cycle test chart of the Li||LFP button battery of Example 1 at 80 °C and 2C rate. The chart shows that the initial discharge capacity at 2C is 155 mAh / g, and the capacity retention rate after 300 cycles is 97.7%, with excellent high-temperature stable cycling ability and capacity retention rate. The Li||LFP button battery used for the 80 °C high-temperature rate performance test can also provide a specific capacity of 150 mAh / g at 10C, with excellent high-temperature rate performance( Figure 9 ).
[0076] Figure 10 Charge-discharge cycle test chart of the Li||LFP button battery assembled in Comparative Example 1. It can be seen that its initial discharge capacity is about 126 mAh / g, and the capacity retention rate after 8 cycles is 82.4%, with poor cycle stability.
[0077] Figure 11 Charge-discharge cycle test chart of the Li||LFP button battery assembled in Comparative Example 2. It can be seen that its initial discharge capacity is about 119 mAh / g, and the capacity retention rate after 2140 cycles is 66.8%. Its cycle stability is better, but the initial discharge capacity is low, indicating a large polarization.
[0078] Figure 12 Charge-discharge cycle test chart of the Li||LFP button battery assembled in Comparative Example 3. It can be seen that its initial discharge capacity is about 141 mAh / g, and the capacity retention rate after 40 cycles is 86.0%. Its initial discharge capacity is high, but the cycle stability is poor.
[0079] Figure 13 Charge-discharge cycle test chart of the Li||LFP button battery assembled in Comparative Example 3. It can be seen that its initial discharge capacity is about 137 mAh / g, and the capacity retention rate after 40 cycles is 83.7%. Its initial discharge capacity is high, but the cycle stability is poor.
[0080] 4. Soft-pack battery
[0081] Assemble a soft-pack battery with the second homogeneous precursor solution of Example 1. The positive electrode is lithium iron phosphate (LFP), the negative electrode is a 20-μm-thick lithium copper composite foil, the loading on each side of the positive electrode sheet is 20.15 mg·cm -2 , a total of 8 sides, the weight of each negative electrode sheet is 0.3897 g, a total of 4 sheets, the capacity of the soft-pack battery is 1 Ah, the dosage of the second homogeneous precursor solution is 3 g, the battery case is a commercial aluminum-plastic film, the battery is left standing in an 80 °C oven for 60 minutes until in-situ thermal polymerization is completed, the separator is a 16-μm-thick polypropylene separator, and the injection tool is preferably a pipette gun with a measuring range of 1000 μL.
[0082] After the assembled soft-pack battery is activated at 0.1C for 1 cycle, charge-discharge cycling is carried out at a rate of 0.5C. Figure 14 It is the cycle curve graph of the 1Ah soft-pack battery in Example 1. The picture shows that the soft-pack battery still retains 90% of its capacity after 100 cycles, indicating its potential for practical applications.
[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for preparing a fluorinated eutectic gel electrolyte for a lithium battery, characterized in that: The steps include: mixing a fluorinated amide solid with a solid lithium salt to form a homogeneous eutectic precursor solution; Adding an initiator and a high-pressure-resistant polymerization monomer to the homogeneous eutectic precursor solution to obtain a second precursor solution; The second precursor solution is injected into the battery cell, and allowed to stand for in-situ thermal polymerization to obtain the product.
2. The preparation method according to claim 1, characterized in that The fluorinated amide solid is selected from one or more of 2,2,2-trifluoro-N-methylacetamide, 2,2-difluoro-N-methylacetamide, 2-fluoro-N-methylacetamide, 3,3,3-trifluoro-N-methylpropionamide, 3,3-difluoro-N-methylpropionamide, 3-fluoro-N-methylpropionamide, N-(trifluoromethyl)acetamide, N-(difluoromethyl)acetamide, N-(fluoromethyl)acetamide, N-(2,2,2-trifluoroethyl)acetamide, N-(2,2-difluoroethyl)acetamide or N-(2-fluoroethyl)acetamide.
3. The preparation method according to claim 1, characterized in that: The solid lithium salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorooxalatoborate or lithium tetrafluoroborate.
4. The preparation method according to claim 1, characterized in that: The fluorinated amide solid is 2,2,2-trifluoro-N-methylacetamide, and the solid lithium salt is lithium bis(trifluoromethanesulfonyl imide).
5. The preparation method according to claim 1, characterized in that: The molar ratio of the fluorinated amide solid to the solid lithium salt is (50-90):(10-50).
6. The preparation method according to claim 1, characterized in that: The initiator is an azo thermal initiator; the high-pressure resistant polymerization monomer is a mixed monomer of diallyl carbonate, ethylene carbonate and N,N-methylenebisacrylamide or a mixed monomer of polyethylene glycol diacrylate and butyl acrylate.
7. The preparation method according to claim 1, characterized in that: In the second precursor solution, the mass fraction of the homogeneous eutectic precursor solution is 84-98.4wt%, the mass fraction of the initiator is 0.1-1wt%, and the mass fraction of the high-pressure resistant polymerization monomer is 1.5-15wt%.
8. The preparation method according to claim 1, characterized in that: The temperature of the in-situ thermal polymerization is 55-120° C., and the time of the in-situ thermal polymerization is 30-200 min.
9. A fluorinated eutectic gel electrolyte for lithium batteries prepared by the preparation method according to any one of claims 1 to 8.
10. A lithium metal battery, characterized in that: The invention comprises the fluorinated eutectic gel electrolyte for lithium battery as claimed in claim 9.