Main chain fluorinated cross-linked polymer solid-state electrolyte and preparation method and application thereof

Abstract

The application provides a main chain fluorinated cross-linked polymer solid electrolyte and a preparation method and application thereof. The main chain fluorinated cross-linked polymer solid electrolyte is obtained through a cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated polycyclic epoxy compound, a first lithium salt and an organic solvent; the main chain fluorinated polycyclic epoxy compound is at least one of the following compounds: wherein n is independently an integer between 1 and 10 at each occurrence; the first lithium salt is at least one of lithium difluoro(oxalato)borate, lithium tetrafluoroborate and lithium hexafluorophosphate. The main chain fluorinated cross-linked polymer solid electrolyte provided by the application has excellent ionic conductivity and oxidation stability, and a battery comprising the main chain fluorinated cross-linked polymer solid electrolyte has excellent capacity retention rate and high discharge capacity. Therefore, the main chain fluorinated cross-linked polymer solid electrolyte is of great significance for promoting the development of solid-state batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemistry, in particular to a main chain fluorinated cross-linked polymer solid-state electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Solid-state electrolytes are one of the key materials in modern energy storage devices, especially in solid-state lithium batteries. With the increasing demand for high energy density and safety performance, solid-state electrolytes, as an ideal alternative to liquid electrolytes, have received extensive attention. Solid-state electrolytes not only effectively avoid the leakage and flammability problems of liquid electrolytes, but also provide higher safety in high-temperature environments. Among them, polymer solid-state electrolytes have become one of the ideal electrolyte materials in solid-state batteries due to their good flexibility and processability.

[0003] However, the existing polymer solid-state electrolytes still have some problems: (1) the ionic conductivity of the polymer solid-state electrolyte is low, which reduces the performance of the battery (such as discharge capacity, capacity retention, etc.); (2) the polymer solid-state electrolyte exhibits poor oxidation stability in high working potential environment, which may cause decomposition of the polymer solid-state electrolyte or reaction with the electrode material during the battery charging and discharging process, thereby reducing the performance of the battery (such as discharge capacity, capacity retention, etc.).

[0004] Therefore, how to obtain a polymer solid-state electrolyte with excellent ionic conductivity and oxidation stability is a technical problem to be solved in the field. SUMMARY

[0005] The present application provides a main chain fluorinated cross-linked polymer solid-state electrolyte, which has excellent ionic conductivity and oxidation stability, and a battery comprising the main chain fluorinated cross-linked polymer solid-state electrolyte has excellent capacity retention and high discharge capacity. Therefore, the main chain fluorinated cross-linked polymer solid-state electrolyte is of great significance for promoting the development of solid-state batteries.

[0006] The present application also provides a preparation method of a main chain fluorinated cross-linked polymer solid-state electrolyte, which can prepare a main chain fluorinated cross-linked polymer solid-state electrolyte with excellent ionic conductivity and oxidation stability. The preparation method is simple in process and suitable for wide application.

[0007] The present application also provides a battery comprising the above-mentioned main chain fluorinated cross-linked polymer solid-state electrolyte, so that the battery has excellent capacity retention and high discharge capacity.

[0008] The first aspect of the present application provides a main chain fluorinated cross-linked polymer solid electrolyte, which is obtained after a cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated polyepoxy compound, a first lithium salt and an organic solvent;

[0009] The main chain fluorinated polyepoxy compound is at least one of the compounds shown in formula 1, formula 2, formula 3, formula 4:

[0010]

[0011] In formula 1-4, n is independently an integer between 1-10 at each occurrence;

[0012] The first lithium salt is at least one of lithium difluoro(oxalato)borate, lithium tetrafluoroborate, lithium hexafluorophosphate.

[0013] The main chain fluorinated cross-linked polymer solid electrolyte as described above, the content of the main chain fluorinated polyepoxy compound is 1wt%-50wt% based on the total mass of the main chain fluorinated polyepoxy compound and the organic solvent;

[0014] And / or, the concentration of the first lithium salt is 0.1mol / L-5mol / L based on the total volume of the main chain fluorinated polyepoxy compound and the organic solvent;

[0015] And / or, the organic solvent is at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, methyl ethyl carbonate, dimethoxy carbonate, vinylene carbonate, dimethyl ether of carbonic acid, fluorinated ethylene carbonate, fluorinated methyl ethyl carbonate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3-trifluoroethyl ether.

[0016] The main chain fluorinated cross-linked polymer solid electrolyte as described above, the reaction system further comprises an epoxy compound;

[0017] The epoxy compound is at least one of the compounds shown in formula 5, formula 6, formula 7, formula 8, formula 9, formula 10:

[0018]

[0019] In formula 5-10, R1 is independently selected from -H, -F, -Cl, -Br, -I, -(CF2) x CF3, -CH2OCH2(CF2) x CHF2, -C y H 2y+1 Or -OC y H 2y+1wherein x is an integer between 0 and 10, and y is an integer between 1 and 5.

[0020] The main-chain fluorinated cross-linked polymer solid-state electrolyte as described above, wherein the molar content of the main-chain fluorinated polyepoxy compound is 1 mol% to 100 mol%, and the molar content of the epoxy compound is 0 mol% to 99 mol%, based on the total molar content of the main-chain fluorinated polyepoxy compound and the epoxy compound.

[0021] The main-chain fluorinated cross-linked polymer solid-state electrolyte as described above, wherein the reaction system further comprises a second lithium salt.

[0022] The second lithium salt is at least one of lithium bistrifluoromethylsulfonylimide, lithium bisfluorosulfonylimide, lithium bisfluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium bistrifluoromethylsulfonylamide, and lithium perchlorate.

[0023] The main-chain fluorinated cross-linked polymer solid-state electrolyte as described above, wherein the concentration of the second lithium salt is 0 mol / L to 5 mol / L, based on the total volume of the main-chain fluorinated polyepoxy compound and the organic solvent.

[0024] The main-chain fluorinated cross-linked polymer solid-state electrolyte as described above, wherein the reaction system further comprises an electrolyte additive.

[0025] The electrolyte additive is at least one of lithium difluorophosphate, lithium difluorobisoxalate phosphate, 2,3,4,5,6-pentafluorophenylboric acid, diphenylsulfonylimide, and tris(trimethylsilyl)phosphate.

[0026] The main-chain fluorinated cross-linked polymer solid-state electrolyte as described above, wherein the content of the electrolyte additive is 0 wt% to 10 wt%, based on the total mass of the main-chain fluorinated polyepoxy compound, the first lithium salt, and the organic solvent.

[0027] The second aspect of the present application provides a preparation method of the main-chain fluorinated cross-linked polymer solid-state electrolyte, comprising:

[0028] mixing a first raw material system comprising a main chain fluorinated polyepoxy compound, a first lithium salt and an organic solvent to obtain a first precursor solution; or, mixing a second raw material system comprising a main chain fluorinated polyepoxy compound, an epoxy compound, a first lithium salt and an organic solvent to obtain a second precursor solution; or, mixing a third raw material system comprising a main chain fluorinated polyepoxy compound, a first lithium salt, a second lithium salt and an organic solvent to obtain a third precursor solution; or, mixing a fourth raw material system comprising a main chain fluorinated polyepoxy compound, a first lithium salt, an organic solvent and an electrolyte additive to obtain a fourth precursor solution; or, mixing a fifth raw material system comprising a main chain fluorinated polyepoxy compound, an epoxy compound, a first lithium salt, an organic solvent and an electrolyte additive to obtain a fifth precursor solution; or, mixing a sixth raw material system comprising a main chain fluorinated polyepoxy compound, a first lithium salt, a second lithium salt, an organic solvent and an electrolyte additive to obtain a sixth precursor solution; or, mixing a seventh raw material system comprising a main chain fluorinated polyepoxy compound, an epoxy compound, a first lithium salt, a second lithium salt, an organic solvent and an electrolyte additive to obtain a seventh precursor solution;

[0029] subjecting the first precursor solution, the second precursor solution, the third precursor solution, the fourth precursor solution, the fifth precursor solution, the sixth precursor solution, the seventh precursor solution to crosslinking polymerization, respectively, to obtain the main chain fluorinated crosslinking polymer solid-state electrolyte.

[0030] A third aspect of the present application provides a battery comprising the main chain fluorinated crosslinking polymer solid-state electrolyte.

[0031] The main chain fluorinated crosslinking polymer solid-state electrolyte provided by the present application is obtained by subjecting a reaction system comprising a main chain fluorinated polyepoxy compound, a first lithium salt and an organic solvent to crosslinking polymerization. The main chain fluorinated crosslinking polymer solid-state electrolyte prepared by the present application has excellent ionic conductivity and oxidation stability, and a battery comprising the main chain fluorinated crosslinking polymer solid-state electrolyte has excellent capacity retention rate and high discharge capacity. Therefore, the main chain fluorinated crosslinking polymer solid-state electrolyte is of great significance for promoting the development of solid-state batteries. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort.

[0033] Figure 1State of the reaction precursor solution of Example 4 of the present application before and after performing the crosslinking polymerization reaction, wherein, Figure 1 A is the state of the reaction precursor solution before performing the crosslinking polymerization reaction, Figure 1 B is the state of the reaction precursor solution after performing the crosslinking polymerization reaction;

[0034] Figure 2 Ion conductivity test graph and linear sweep voltammogram of the main chain fluorinated crosslinking polymer solid electrolyte of Example 4 of the present application, wherein, Figure 2 A is the ion conductivity test graph of the main chain fluorinated crosslinking polymer solid electrolyte of Example 4, Figure 2 B is the linear sweep voltammogram of the main chain fluorinated crosslinking polymer solid electrolyte of Example 4;

[0035] Figure 3 Rate graph of the battery containing the main chain fluorinated crosslinking polymer solid electrolyte of Example 4 of the present application;

[0036] Figure 4 Cycle graph of the battery containing the main chain fluorinated crosslinking polymer solid electrolyte of Example 4 of the present application at a rate of 1C;

[0037] Figure 5 Cycle graph of the battery containing the uncured electrolyte of Comparative Example 1 of the present application at a rate of 1C. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0039] The raw materials and reagents used in the following examples can be obtained from commercial channels unless otherwise specified; the processes used are conventional processes in the art unless otherwise specified.

[0040] It should be noted that the descriptions of "first", "second", "third", "fourth", "fifth", "sixth", "seventh" and the like in the present application are only for the purpose of description, and therefore cannot be understood as a limitation on the present application.

[0041] In the following examples, the term "epoxy compound" refers to a compound in which one or more of the ring-forming atoms of a cyclic compound is an oxygen atom.

[0042] The term "backbone-fluorinated polyepoxy compound" refers to an ether compound that satisfies both requirements of containing a fluorine atom or a fluorinated functional group in the backbone and containing two or more epoxy groups.

[0043] The term "high-voltage cathode" refers to a cathode having a charge termination voltage greater than 4 V, such as a nickel cobalt manganese lithium 811 cathode.

[0044] A first aspect of the present application provides a backbone-fluorinated crosslinked polymer solid electrolyte obtained by performing a crosslinking polymerization reaction on a reaction system including a backbone-fluorinated polyepoxy compound, a first lithium salt, and an organic solvent;

[0045] The backbone-fluorinated polyepoxy compound is at least one of the compounds represented by Formula 1, Formula 2, Formula 3, or Formula 4:

[0046]

[0047] In Formulae 1 to 4, n is independently an integer between 1 and 10 at each occurrence.

[0048] The first lithium salt is at least one of lithium difluoro(oxalato)borate, lithium tetrafluoroborate, or lithium hexafluorophosphate.

[0049] In the present application, the backbone-fluorinated crosslinked polymer solid electrolyte is obtained by uniformly mixing a backbone-fluorinated polyepoxy compound and a first lithium salt in an organic solvent to obtain a precursor solution, and then performing a crosslinking polymerization reaction on the precursor solution.

[0050] The present application applies the above-mentioned backbone-fluorinated polyepoxy compound to a backbone-fluorinated crosslinked polymer solid electrolyte, which has excellent ionic conductivity and oxidation stability, and enables a battery to have excellent capacity retention and high discharge capacity.

[0051] In some embodiments, the first lithium salt can be preferably at least one of lithium difluoro(oxalato)borate or lithium tetrafluoroborate.

[0052] When the first lithium salt is the above-mentioned substance, the main-chain fluorinated cross-linked polymer solid electrolyte has more excellent ionic conductivity and oxidation stability. The inventors analyzed the principle and considered that the reason might be that the first lithium salt can dissociate lithium ions as carriers in the main-chain fluorinated cross-linked polymer solid electrolyte, thereby improving the ionic conductivity and oxidation stability of the main-chain fluorinated cross-linked polymer solid electrolyte; the first lithium salt can decompose Lewis acid to initiate ring-opening polymerization of the main-chain fluorinated polycyclic epoxy compound, thereby realizing in-situ preparation of the main-chain fluorinated cross-linked polymer solid electrolyte in the battery, which is conducive to improving the ionic conductivity and oxidation stability of the main-chain fluorinated cross-linked polymer solid electrolyte.

[0053] In a specific embodiment, the content of the main-chain fluorinated polycyclic epoxy compound is 1wt% to 50wt% based on the total mass of the main-chain fluorinated polycyclic epoxy compound and the organic solvent.

[0054] When the content of the main-chain fluorinated polycyclic epoxy compound is within the above-mentioned range, a main-chain fluorinated cross-linked polymer solid electrolyte with high ionic conductivity can be obtained. In addition, the inventors found through a large number of studies that when the content of the main-chain fluorinated polycyclic epoxy compound is less than 1wt%, the electrolyte after cross-linking polymerization reaction is in a liquid state and cannot be solidified; when the content of the main-chain fluorinated polycyclic epoxy compound is greater than 50wt%, the ionic conductivity of the fluorinated cross-linked polymer solid electrolyte prepared is relatively low.

[0055] Exemplarily, the content of the main-chain fluorinated polycyclic epoxy compound can be any one of 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt% or 50wt% and a range consisting of any two thereof, based on the total mass of the main-chain fluorinated polycyclic epoxy compound and the organic solvent.

[0056] In a specific embodiment, the concentration of the first lithium salt is 0.1mol / L to 5mol / L based on the total volume of the main-chain fluorinated polycyclic epoxy compound and the organic solvent.

[0057] When the concentration of the first lithium salt is within the above range, a main chain fluorinated cross-linked polymer solid electrolyte with high ionic conductivity can be obtained. In addition, the present inventors have found through research that when the concentration of the first lithium salt is less than 0.1 mol / L, the electrolyte after the cross-linking polymerization reaction is in a liquid state and cannot be solidified, and the cycle stability of the battery is poor; when the concentration of the first lithium salt is greater than 5 mol / L, lithium dendrites are easily formed, leading to poor stability of the electrolyte interface (SEI) of the main chain fluorinated cross-linked polymer solid electrolyte.

[0058] In a specific embodiment, the organic solvent is at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, methyl ethyl carbonate, dimethoxy carbonate, vinylene carbonate, dimethyl ether carbonate, fluoroethylene carbonate, fluoro methyl ethyl carbonate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3-trifluoroethyl ether.

[0059] In a specific embodiment, the reaction system further comprises an epoxy compound;

[0060] The epoxy compound is at least one of the compounds represented by formula 5, formula 6, formula 7, formula 8, formula 9, formula 10:

[0061]

[0062] In formula 5 to formula 10, R1 is independently selected from -H, -F, -Cl, -Br, -I, -(CF2) x CF3, -CH2OCH2(CF2) x CHF2, -C y H 2y+1 or -OC y H 2y+1 wherein x is an integer between 0 and 10, and y is an integer between 1 and 5.

[0063] In the present application, the main chain fluorinated cross-linked polymer solid electrolyte can be obtained by a reaction system comprising a main chain fluorinated epoxy compound, an epoxy compound, a first lithium salt and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte has excellent ionic conductivity and oxidation stability.

[0064] In one embodiment, the mole content of the main-chain fluorinated polyepoxide compound is 1 mol% to 100 mol% and the mole content of the epoxy compound is 0 mol% to 99 mol%, based on the total mole content of the main-chain fluorinated polyepoxide compound and the epoxy compound. Further, the mole content of the main-chain fluorinated polyepoxide compound is 50 mol% to 100 mol% and the mole content of the epoxy compound is 0 mol% to 50 mol%.

[0065] When the mole content of the main-chain fluorinated polyepoxide compound and the mole content of the epoxy compound are within the above ranges, respectively, a main-chain fluorinated cross-linked polymer solid electrolyte having high ionic conductivity can be obtained. In addition, the present inventors have found through research that when the mole content of the main-chain fluorinated polyepoxide compound is less than 1 mol%, the electrolyte after the cross-linking polymerization reaction is in a liquid state and cannot be solidified.

[0066] Illustratively, when the mole content of the main-chain fluorinated polyepoxide compound is 50 mol%, the mole content of the epoxy compound is 50 mol%, based on the total mole content of the main-chain fluorinated polyepoxide compound and the epoxy compound; when the mole content of the main-chain fluorinated polyepoxide compound is 60 mol%, the mole content of the epoxy compound is 40 mol%; when the mole content of the main-chain fluorinated polyepoxide compound is 70 mol%, the mole content of the epoxy compound is 30 mol%; when the mole content of the main-chain fluorinated polyepoxide compound is 80 mol%, the mole content of the epoxy compound is 20 mol%; when the mole content of the main-chain fluorinated polyepoxide compound is 90 mol%, the mole content of the epoxy compound is 10 mol%; when the mole content of the main-chain fluorinated polyepoxide compound is 100 mol%, the mole content of the epoxy compound is 0 mol%, and the like.

[0067] In one embodiment, the reaction system further comprises a second lithium salt.

[0068] The second lithium salt is at least one of lithium bistrifluoromethylsulfonylimide, lithium bisfluorosulfonylimide, lithium bisfluoromethanesulfonate, lithium trifluoromethanesulfonate, lithium bistrifluoromethylsulfonylamide, and lithium perchlorate.

[0069] In the present application, the main chain fluorinated cross-linked polymer solid electrolyte can be obtained by cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated multi-epoxy compound, a first lithium salt, a second lithium salt and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte has excellent ionic conductivity and oxidation stability. The main chain fluorinated cross-linked polymer solid electrolyte can also be obtained by cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated multi-epoxy compound, an epoxy compound, a first lithium salt, a second lithium salt and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte also has excellent ionic conductivity and oxidation stability.

[0070] In a specific embodiment, the concentration of the second lithium salt is 0 mol / L to 5 mol / L, for example, 0 mol / L, 0.1 mol / L, 0.5 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, etc., based on the total volume of the main chain fluorinated multi-epoxy compound and the organic solvent.

[0071] In a specific embodiment, the reaction system further comprises an electrolyte additive.

[0072] The electrolyte additive is at least one of lithium difluorophosphate, lithium difluorobisoxalate phosphate, 2,3,4,5,6-pentafluorophenylboric acid, diphenylsulfonylimide and tris(trimethylsilyl) phosphate.

[0073] In the present application, the main chain fluorinated cross-linked polymer solid electrolyte can be obtained by cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated multi-epoxy compound, a first lithium salt, an electrolyte additive and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte has excellent ionic conductivity and oxidation stability. The main chain fluorinated cross-linked polymer solid electrolyte can also be obtained by cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated multi-epoxy compound, a first lithium salt, an epoxy compound, an electrolyte additive and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte also has excellent ionic conductivity and oxidation stability. The main chain fluorinated cross-linked polymer solid electrolyte can also be obtained by cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated multi-epoxy compound, a first lithium salt, a second lithium salt, an electrolyte additive and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte also has excellent ionic conductivity and oxidation stability. The main chain fluorinated cross-linked polymer solid electrolyte can also be obtained by cross-linking polymerization reaction of a reaction system comprising a main chain fluorinated multi-epoxy compound, a first lithium salt, a second lithium salt, an epoxy compound, an electrolyte additive and an organic solvent, and the obtained main chain fluorinated cross-linked polymer solid electrolyte also has excellent ionic conductivity and oxidation stability.

[0074] In one specific embodiment, based on the total mass of the main-chain fluorinated polyepoxy compound, the first lithium salt, and the organic solvent, the content of the electrolyte additive is 0 wt% to 10 wt%, for example, it can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, etc.

[0075] A second aspect of the present invention provides a method for preparing the aforementioned main-chain fluorinated crosslinked polymer solid electrolyte, comprising:

[0076] A first precursor solution is obtained by mixing a first raw material system comprising a main-chain fluorinated polyepoxy compound, a first lithium salt, and an organic solvent.

[0077] The first precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0078] In another specific embodiment, a second raw material system comprising a main-chain fluorinated polyepoxy compound, an epoxy compound, a first lithium salt and an organic solvent is mixed to obtain a second precursor solution.

[0079] The second precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0080] In another specific embodiment, a third raw material system comprising a main-chain fluorinated polyepoxy compound, a first lithium salt, a second lithium salt, and an organic solvent is mixed to obtain a third precursor solution.

[0081] The third precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0082] In another specific embodiment, a fourth raw material system comprising a main-chain fluorinated polyepoxy compound, a first lithium salt, an organic solvent, and an electrolyte additive is mixed to obtain a fourth precursor solution.

[0083] The fourth precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0084] In another specific embodiment, a fifth raw material system comprising a main-chain fluorinated polyepoxy compound, an epoxy compound, a first lithium salt, an organic solvent, and an electrolyte additive is mixed to obtain a fifth precursor solution.

[0085] The fifth precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0086] In another specific embodiment, a sixth raw material system comprising a main-chain fluorinated polyepoxy compound, a first lithium salt, a second lithium salt, an organic solvent, and an electrolyte additive is mixed to obtain a sixth precursor solution.

[0087] The sixth precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0088] In another specific embodiment, a seventh raw material system comprising a main-chain fluorinated polyepoxy compound, an epoxy compound, a first lithium salt, a second lithium salt, an organic solvent, and an electrolyte additive is mixed to obtain a seventh precursor solution.

[0089] The seventh precursor solution is subjected to a crosslinking polymerization reaction to obtain the main-chain fluorinated crosslinked polymer solid electrolyte.

[0090] The present invention can prepare solid electrolytes with excellent ionic conductivity and oxidative stability by using the above preparation methods.

[0091] In some embodiments, the temperature for the crosslinking polymerization reaction is 30°C to 80°C and the time is 6 hours to 48 hours.

[0092] When the temperature and time parameters for the crosslinking polymerization reaction are within the above-mentioned ranges, a main-chain fluorinated crosslinked polymer solid electrolyte with superior ionic conductivity and oxidative stability can be prepared.

[0093] For example, the temperature for the crosslinking polymerization reaction can be any one of 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, or 80°C, or a range of any two of these.

[0094] The time can be any one of 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, or 48 hours, and a range consisting of any two of them.

[0095] A third aspect of the present application provides a battery including the main chain fluorinated cross-linked polymer solid electrolyte described above. Thus, the main chain fluorinated cross-linked polymer solid electrolyte has excellent ionic conductivity and oxidation stability, and the battery containing the main chain fluorinated cross-linked polymer solid electrolyte has excellent capacity retention rate and high discharge capacity.

[0096] In a specific embodiment, the battery further includes a positive electrode, a negative electrode, and a separator.

[0097] In some embodiments, the positive electrode is at least one of lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium-rich manganese-based.

[0098] In some embodiments, the negative electrode is at least one of lithium metal, graphite, silicon-carbon, silicon.

[0099] In some embodiments, the separator is at least one of a polyethylene film, a polypropylene film, a nylon non-woven film, a seaweed fiber non-woven film, a cellulose film, a bacterial cellulose film, a glass fiber film, a polyethylene terephthalate film, a polyimide non-woven film, a polyamide film, a spandex film, an aramid film.

[0100] Hereinafter, the present application will be further described through specific examples.

[0101] Example 1

[0102] This example prepares the main chain fluorinated cross-linked polymer solid electrolyte and the battery containing the main chain fluorinated cross-linked polymer solid electrolyte by the following process:

[0103] In an argon-filled glove box, 1,4-bis(2',3'-epoxypropyl)perfluorobutane (BEPFB), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in fluorinated ethylene carbonate (FEC) and stirred uniformly to obtain a reaction precursor solution; the reaction precursor solution was added to a battery shell with lithium nickel cobalt manganese oxide 811 as the positive electrode, lithium metal as the negative electrode, and a polyethylene film as the separator, and then the reaction precursor solution in the battery shell was allowed to undergo a crosslinking polymerization reaction at 60°C for 24 hours to obtain a main-chain fluorinated crosslinked polymer solid-state electrolyte and a battery containing the main-chain fluorinated crosslinked polymer solid-state electrolyte.

[0104] The raw materials and the amounts of addition for preparing the main-chain fluorinated crosslinked polymer solid-state electrolyte in this example are shown in Table 1:

[0105] Table 1 Raw materials and amounts of addition for the main-chain fluorinated crosslinked polymer solid-state electrolyte

[0106]

[0107] Example 2

[0108] The main-chain fluorinated crosslinked polymer solid-state electrolyte and the battery containing the main-chain fluorinated crosslinked polymer solid-state electrolyte were prepared by the following process in this example:

[0109] In an argon-filled glove box, 1,4-bis(2',3'-epoxypropyl)perfluorobutane (BEPFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in fluorinated ethylene carbonate (FEC) and stirred uniformly to obtain a reaction precursor solution; the reaction precursor solution was added to a battery shell with lithium nickel cobalt manganese oxide 811 as the positive electrode, lithium metal as the negative electrode, and a polyethylene film as the separator, and then the reaction precursor solution in the battery shell was allowed to undergo a crosslinking polymerization reaction at 60°C for 24 hours to obtain a main-chain fluorinated crosslinked polymer solid-state electrolyte and a battery containing the main-chain fluorinated crosslinked polymer solid-state electrolyte.

[0110] The raw materials and the amounts of addition for preparing the main-chain fluorinated crosslinked polymer solid-state electrolyte in this example are shown in Table 2:

[0111] Table 2 Raw materials and amounts of addition for the main-chain fluorinated crosslinked polymer solid-state electrolyte

[0112]

[0113] Example 3

[0114] The process for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte and the battery comprising the main-chain fluorinated cross-linked polymer solid-state electrolyte of this example is basically the same as that of Example 2, except that:

[0115] 1,4-bis(2',3'-epoxypropyl) perfluorobutane (BEPFB), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluorinated ethylene carbonate (FEC) and fluorinated methyl ethylene carbonate (FEMC) and stirred uniformly to obtain a reaction precursor solution.

[0116] The raw materials and the amounts of addition for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte of this example are shown in Table 3:

[0117] Table 3 Raw materials and amounts of addition for the main-chain fluorinated cross-linked polymer solid-state electrolyte

[0118]

[0119]

[0120] Example 4

[0121] The process for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte and the battery comprising the main-chain fluorinated cross-linked polymer solid-state electrolyte of this example is basically the same as that of Example 2, except that:

[0122] 1,4-bis(2',3'-epoxypropyl) perfluorobutane (BEPFB), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluorinated ethylene carbonate (FEC) and fluorinated methyl ethylene carbonate (FEMC) and stirred uniformly to obtain a reaction precursor solution.

[0123] The raw materials and the amounts of addition for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte of this example are shown in Table 4:

[0124] Table 4 Raw materials and amounts of addition for the main-chain fluorinated cross-linked polymer solid-state electrolyte

[0125]

[0126] Example 5

[0127] The process for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte and the battery comprising the main-chain fluorinated cross-linked polymer solid-state electrolyte of this example is basically the same as that of Example 4, except that:

[0128] Octafluoro-1,6-hexanediol diglycidyl ether (OFHDGE), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethyl methyl carbonate (FEMC) and stirred uniformly to obtain a reaction precursor solution.

[0129] The raw materials and the amounts of addition for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte in this example are shown in Table 5:

[0130] Table 5 Raw materials and amounts of addition for main-chain fluorinated cross-linked polymer solid-state electrolyte

[0131]

[0132] Example 6

[0133] The process for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte and the battery containing the same in this example is basically consistent with that in Example 4, except that:

[0134] 1,4-bis(2',3'-epoxypropyl)perfluorobutane (BEPFB), monomeric trifluoroepoxypropane (TFPO), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethyl methyl carbonate (FEMC) and stirred uniformly to obtain a reaction precursor solution.

[0135] The raw materials and the amounts of addition for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte in this example are shown in Table 6:

[0136] Table 6 Raw materials and amounts of addition for main-chain fluorinated cross-linked polymer solid-state electrolyte

[0137]

[0138] Example 7

[0139] The process for preparing the main-chain fluorinated cross-linked polymer solid-state electrolyte and the battery containing the same in this example is basically consistent with that in Example 4, except that:

[0140] 1,4-bis(2',3'-epoxypropyl) perfluorobutane (BEPFB), monomer 1,3-dioxolane (DOL), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethylene methyl carbonate (FEMC), and stirred uniformly to obtain a reaction precursor solution.

[0141] The raw materials and the amounts of addition for preparing the main chain fluorinated cross-linked polymer solid-state electrolyte in this example are shown in Table 7:

[0142] Table 7 Raw materials and amounts of addition for main chain fluorinated cross-linked polymer solid-state electrolyte

[0143]

[0144] Example 8

[0145] The process for preparing the main chain fluorinated cross-linked polymer solid-state electrolyte and the battery containing the same in this example is basically consistent with that of Example 4, except that:

[0146] Octafluoro-1,6-hexanediol diglycidyl ether (OFHDGE), monomer trifluoroepoxypropane (TFPO), lithium difluoro(oxalato)borate (LiDFOB), and benzene bis-sulfonyl imide (BBSI) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethylene methyl carbonate (FEMC), and stirred uniformly to obtain a reaction precursor solution.

[0147] The raw materials and the amounts of addition for preparing the main chain fluorinated cross-linked polymer solid-state electrolyte in this example are shown in Table 8:

[0148] Table 8 Raw materials and amounts of addition for main chain fluorinated cross-linked polymer solid-state electrolyte

[0149]

[0150] Example 9

[0151] The process for preparing the main chain fluorinated cross-linked polymer solid-state electrolyte and the battery containing the same in this example is basically consistent with that of Example 4, except that:

[0152] 1,4-bis(2',3'-epoxypropyl) perfluorobutane (BEPFB), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethylene methyl carbonate (FEMC), and stirred uniformly to obtain a reaction precursor solution.

[0153] The raw materials and the amounts of addition for preparing the main chain fluorinated cross-linked polymer solid-state electrolyte of the present example are shown in Table 9:

[0154] Table 9 Raw materials and amounts of addition for main chain fluorinated cross-linked polymer solid-state electrolyte

[0155]

[0156]

[0157] Comparative Example 1

[0158] The process for preparing the uncured electrolyte (an electrolyte that is in a liquid state after the cross-linking polymerization reaction and cannot be cured) and the battery containing the uncured electrolyte of the present comparative example is basically the same as that of Example 4, except that:

[0159] Ethylene glycol diglycidyl ether (EGDE), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethyl methyl carbonate (FEMC) and stirred uniformly to obtain a reaction precursor solution.

[0160] The raw materials and the amounts of addition for preparing the uncured electrolyte of the present comparative example are shown in Table 10:

[0161] Table 10 Raw materials and amounts of addition for uncured electrolyte

[0162]

[0163] Comparative Example 2

[0164] The process for preparing the uncured electrolyte (an electrolyte that is in a liquid state after the cross-linking polymerization reaction and cannot be cured) and the battery containing the uncured electrolyte of the present comparative example is basically the same as that of Example 4, except that:

[0165] Monomer trifluoropropylene oxide (TFPO), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium difluorophosphate (LiDFP) were dissolved in a mixed solvent of fluoroethylene carbonate (FEC) and fluoroethyl methyl carbonate (FEMC) and stirred uniformly to obtain a reaction precursor solution.

[0166] The raw materials and the amounts of addition for preparing the uncured electrolyte of the present comparative example are shown in Table 11:

[0167] Table 11 Raw materials and amounts of addition for uncured electrolyte

[0168]

[0169] Performance test

[0170] The batteries of Examples 1-9 containing the main-chain fluorinated cross-linked polymer solid-state electrolyte and the batteries of Comparative Examples 1-2 containing the uncured electrolyte were respectively subjected to the following performance tests under the test conditions of a rate of 1C and a test voltage range of 2.8-4.5V, and the test results are shown in Table 12.

[0171] Ionic conductivity (mS / cm): obtained by electrochemical impedance test of the battery using an electrochemical workstation;

[0172] Oxidation stable potential (V): obtained by linear sweep voltammetry test of the battery using an electrochemical workstation;

[0173] Discharge capacity (mAh cm -2 ): obtained by constant current charge-discharge test of the battery using a battery test system;

[0174] Capacity retention rate (%): calculated by dividing the discharge capacity at a specified number of cycles by the maximum discharge capacity.

[0175] Table 12 Test results

[0176]

[0177] “—” in the table indicates that no test of the ionic conductivity of the uncured electrolyte was performed.

[0178] As shown in Table 12, the ionic conductivity of the main-chain fluorinated crosslinked polymer solid electrolyte of the present invention is 1.0 mS / cm to 2.8 mS / cm at room temperature, and the oxidation stability potential is 5.4 V to 5.6 V, which can effectively improve the discharge capacity and capacity retention of the battery. This may be because: (1) the fluorine atom in the main chain is a strong electron-withdrawing group, which can reduce the highest occupied molecular energy level of the polymer, thereby enhancing the oxidation stability of the main-chain fluorinated crosslinked polymer solid electrolyte; (2) multiple epoxy functional groups can also introduce ether oxygen bonds into the chain segments, improve the lithium-ion transport capacity of the polymer, and ensure the high ionic conductivity of the main-chain fluorinated crosslinked polymer solid electrolyte; (3) multiple epoxy functional groups can act as active functional groups for ring-opening polymerization of cations, realize the in-situ preparation of polymer in the battery, ensure the close contact between the main-chain fluorinated crosslinked polymer solid electrolyte and the positive and negative electrodes, which is beneficial to improving the discharge capacity and capacity retention of the battery. Comparisons of Comparative Examples 1, 2, and 4 show that when 1,4-bis(2',3'-epoxypropyl)perfluorobutane (BEPFB) is replaced with ethylene glycol diglycidyl ether (EGDE) or monomeric trifluoropropylene oxide (TFPO), the prepared electrolyte is in an uncured state, and the oxidation stability potential of the electrolyte decreases. This results in a decrease in both the battery's discharge capacity and capacity retention rate. This indicates that adding BEPFB to the electrolyte can effectively improve the oxidation stability potential of the electrolyte and enhance the battery's discharge capacity and capacity retention rate. Therefore, the main-chain fluorinated crosslinked polymer solid electrolyte prepared in this invention exhibits excellent ionic conductivity and oxidation stability, while batteries containing this main-chain fluorinated crosslinked polymer solid electrolyte demonstrate excellent capacity retention and high discharge capacity.

[0179] in addition, Figure 1 The states of the precursor solution in Example 4 before and after the crosslinking polymerization reaction are shown below. Figure 1 A represents the state of the precursor solution before the crosslinking polymerization reaction. Figure 1 B represents the state of the precursor solution after the cross-linking polymerization reaction;

[0180] from Figure 1 It can be seen that the precursor solution before the crosslinking polymerization reaction ( Figure 1 A) is in a liquid state, but after undergoing a cross-linking polymerization reaction ( Figure 1 B) adheres firmly to the wall of the glass bottle, and even when inverted, the main-chain fluorinated crosslinked polymer solid electrolyte will not fall off the wall.

[0181] Figure 2 The figures show the ionic conductivity test diagram and linear sweep voltammetry diagram of the main-chain fluorinated crosslinked polymer solid electrolyte in Example 4. Figure 2A is the ionic conductivity test graph of the main-chain fluorinated crosslinked polymer solid electrolyte in Example 4. Figure 2 B is the linear sweep voltammogram of the main-chain fluorinated crosslinked polymer solid electrolyte of Example 4;

[0182] Depend on Figure 2 As can be seen from A, the ionic conductivity of the fluorinated crosslinked polymer solid electrolyte is 1 mS / cm. In addition, the same test was also performed on the fluorinated crosslinked polymer solid electrolytes of Examples 1-3 and Examples 5-9. The specific results are shown in Table 2. All of them can achieve a high ionic conductivity of 1.0 mS / cm to 2.8 mS / cm, which shows that the fluorinated crosslinked polymer solid electrolyte provided by the present invention has excellent ionic conductivity.

[0183] Depend on Figure 2 As can be seen from B, the oxidation stability potential of the fluorinated cross-linked polymer solid electrolyte can reach 5.6V, indicating that the fluorinated cross-linked polymer solid electrolyte has excellent oxidation stability and can withstand the positive electrode with high working potential (i.e., high voltage positive electrode lithium nickel cobalt manganese oxide 811).

[0184] Figure 3 The rate capability diagram of the battery containing the main-chain fluorinated crosslinked polymer solid electrolyte in Example 4 is shown.

[0185] Depend on Figure 3 It can be seen that the main-chain fluorinated crosslinked polymer solid electrolyte can release a high capacity even at high rates.

[0186] Figure 4 This is a cycling diagram of the battery containing a main-chain fluorinated crosslinked polymer solid electrolyte in Example 4 at a rate of 1C.

[0187] Depend on Figure 4 It can be seen that even though the cathode is lithium nickel cobalt manganese oxide 811, the battery containing the main chain fluorinated crosslinked polymer solid electrolyte can still maintain a capacity retention rate of up to 83.8% after 1000 cycles at 1C rate. This shows that the battery containing the main chain fluorinated crosslinked polymer solid electrolyte of the present invention can still exhibit excellent cycle stability for high voltage cathode.

[0188] Figure 5 The cycling diagram of the battery containing uncured electrolyte in Comparative Example 1 at a rate of 1C is shown.

[0189] Depend on Figure 5 It can be seen that the battery assembled with an uncured electrolyte obtained by in-situ polymerization of non-fluorinated polyepoxy compounds has a capacity retention rate of only 49.2% after 600 cycles at 1C rate.

[0190] In conclusion, the prepared main-chain fluorinated cross-linked polymer solid electrolyte has excellent ion conductivity and oxidation stability, and high stability to high-voltage positive electrode, so that the battery containing the main-chain fluorinated cross-linked polymer solid electrolyte has excellent cycle stability.

[0191] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A main-chain fluorinated cross-linked polymer solid-state electrolyte, characterized by, obtained after a cross-linking polymerization reaction by a reaction system including a main-chain-fluorinated polyepoxy compound, a first lithium salt, and an organic solvent; a content of the main-chain-fluorinated polyepoxy compound is 1 wt% to 50 wt% based on a total mass of the main-chain-fluorinated polyepoxy compound and the organic solvent; The main-chain-fluorinated polyepoxy compound is at least one of compounds represented by Formula 1, Formula 2, Formula 3, and Formula 4: ； Formula 1 Formula 2 ； Formula 3 Formula 4 In Formulae 1 to 4, n is independently an integer of 1 to 10 at each occurrence. The first lithium salt is at least one of lithium difluoro(oxalato)borate, lithium tetrafluoroborate, and lithium hexafluorophosphate.

2. The main-chain fluorinated cross-linked polymer solid-state electrolyte according to claim 1, characterized in that, A concentration of the first lithium salt is 0.1 mol / L to 5 mol / L based on a total volume of the main-chain-fluorinated polyepoxy compound and the organic solvent. The organic solvent is at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, methyl ethyl carbonate, dimethoxy carbonate, vinylene carbonate, dimethyl ether of carbonic acid, fluoroethylene carbonate, fluoromethyl ethyl carbonate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3-trifluoroethyl ether.

3. The main-chain fluorinated cross-linked polymer solid-state electrolyte according to claim 1, wherein The reaction system further includes an epoxy compound. The epoxy compound is at least one of compounds represented by Formula 5, Formula 6, Formula 7, Formula 8, Formula 9, and Formula 10: ； Formula 5 Formula 6 Formula 7 Formula 8 Formula 9 Formula 10 In Formula 5-10, R1is independently selected at each occurrence from -H, -F, -Cl, -Br, -I, -(CF2) x CF3, -CH2OCH2(CF2) x CHF2, -C y H 2y+1 or -OC y H 2y+1 wherein x is an integer between 0 and 10, and y is an integer between 1 and 5.

4. The main-chain fluorinated cross-linked polymer solid-state electrolyte according to claim 3, characterized in that, A molar content of the main-chain-fluorinated polyepoxy compound is 1 mol% to 100 mol% and a molar content of the epoxy compound is 0 mol% to 99 mol% based on a total molar content of the main-chain-fluorinated polyepoxy compound and the epoxy compound, and the molar content of the epoxy compound is not 0 mol%.

5. The main-chain fluorinated cross-linked polymer solid-state electrolyte according to claim 1 or 3, characterized in that, The reaction system further includes a second lithium salt. The second lithium salt is at least one of lithium bistrifluoromethylsulfonylimide, lithium bisfluorosulfonylimide, lithium bisfluorosulfonate, lithium trifluoromethylsulfonate, lithium bistrifluoromethylsulfonamide, and lithium perchlorate.

6. The main-chain fluorinated cross-linked polymer solid-state electrolyte according to claim 5, wherein A concentration of the second lithium salt is 0 mol / L to 5 mol / L based on a total volume of the main-chain-fluorinated polyepoxy compound and the organic solvent, and the concentration of the second lithium salt is not 0 mol / L.

7. The main-chain fluorinated cross-linked polymer solid-state electrolyte of claim 5, wherein The reaction system further includes an electrolyte additive. The electrolyte additive is at least one of lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, 2,3,4,5,6-pentafluorophenylboronic acid, diphenylsulfonylimide, and tris(trimethylsilyl)phosphate.

8. The main-chain fluorinated cross-linked polymer solid-state electrolyte according to claim 7, characterized in that, A content of the electrolyte additive is 0 wt% to 10 wt% based on a total mass of the main-chain-fluorinated polyepoxy compound, the first lithium salt, and the organic solvent, and the content of the electrolyte additive is not 0 wt%.

9. A process for the preparation of the main-chain fluorinated cross-linked polymer solid-state electrolyte according to any one of claims 1 to 8, characterized in that, The method includes: mixing a first raw material system including a main-chain-fluorinated polyepoxy compound, a first lithium salt, and an organic solvent to obtain a first precursor solution; or, mixing a second raw material system including the main chain-fluorinated polyepoxy compound, the epoxy compound, the first lithium salt, and the organic solvent to obtain a second precursor solution; or, mixing a third raw material system including the main chain-fluorinated polyepoxy compound, the first lithium salt, and the second lithium salt, and the organic solvent to obtain a third precursor solution; or, mixing a fifth raw material system including the main chain-fluorinated polyepoxy compound, the epoxy compound, the first lithium salt, the organic solvent, and the electrolyte additive to obtain a fifth precursor solution; or, mixing a sixth raw material system including the main chain-fluorinated polyepoxy compound, the first lithium salt, the second lithium salt, the organic solvent, and the electrolyte additive to obtain a sixth precursor solution; or, mixing a seventh raw material system including the main chain-fluorinated polyepoxy compound, the epoxy compound, the first lithium salt, the second lithium salt, the organic solvent, and the electrolyte additive to obtain a seventh precursor solution; subjecting the first precursor solution, the second precursor solution, the third precursor solution, the fifth precursor solution, the sixth precursor solution, and the seventh precursor solution to crosslinking polymerization, respectively, to obtain the main chain-fluorinated crosslinking polymer solid-state electrolyte.

10. A battery, characterized by The main chain-fluorinated crosslinking polymer solid-state electrolyte according to any one of claims 1 to 8.

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