Electrolytes, electrochemical devices and electronic devices comprising the same

Abstract

The application discloses an electrolyte, an electrochemical device and an electronic device comprising the same. The electrolyte comprises an electrolyte base, the electrolyte base comprises a lithium salt, a diluent, an additive and a solvent, the lithium salt comprises a sulfonimide lithium salt and a lithium borate compound based on an oxalate ligand; the diluent comprises a fluorine-containing ether compound; the additive comprises a nitrogen-containing compound; the solvent comprises a fluorine-free ether compound and a fluorine-containing ketone compound; the mass percentage of the lithium salt is a, the mass percentage of the diluent is b, the mass percentage of the additive is c, and the mass percentage of the solvent is d based on the mass of the electrolyte base, and 0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c 0.5 The electrolyte system of the application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and more specifically, to electrolytes and electrochemical and electronic devices comprising the same. Background Technology

[0002] Electrolyte is the sole medium for ion transport within electrochemical devices such as lithium-ion secondary batteries. Ionic conductivity reflects the efficiency of ion migration in the electrolyte. Increasing ionic conductivity can improve the power density of the electrochemical device, reduce its internal resistance and energy loss, and broaden its operating temperature range. Improving the cycle stability of the electrochemical device can extend its lifespan and ensure its long-term safety. It is important to note that high ionic conductivity does not equate to high cycle stability. Therefore, if only ionic conductivity is pursued while neglecting the chemical stability of the electrolyte, a highly active electrolyte system may accelerate the corrosion of the positive and negative electrode materials and the destruction of the SEI film, thereby reducing the cycle stability of the electrochemical device.

[0003] Therefore, it is of great significance to develop an electrolyte that can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device. Summary of the Invention

[0004] The purpose of this application is to solve the problem of simultaneously improving the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device, and to provide an electrolyte and an electrochemical and electronic device comprising the electrolyte.

[0005] To achieve the above objectives, this application provides an electrolyte comprising an electrolyte matrix, wherein the electrolyte matrix includes a lithium salt, a diluent, an additive, and a solvent. The lithium salts include sulfonylimide lithium salts and lithium borate compounds based on oxalate ligands; The diluent includes fluorinated ether compounds; The additives include nitrogen-containing compounds; The solvents include non-fluorinated ether compounds and fluorinated ketone compounds; Based on the mass of the electrolyte matrix, the mass percentage of the lithium salt is a, the mass percentage of the diluent is b, the mass percentage of the additive is c, and the mass percentage of the solvent is d. 0.015 ≤ (a × b) / (d × β) ≤ 0.095, β = 1 + 0.07 × c 0.5 .

[0006] In the electrolyte system of this application, by controlling "0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c" 0.5 This can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0007] Specifically, when the electrolyte system of this application uses specific lithium salts, diluents, additives, and solvents, and satisfies "0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c", 0.5 "At the same time, specific additives can promote the dissociation of specific lithium salts, increase the number of free lithium ions in the electrolyte, and specific combinations of diluents, additives and solvents can reduce the viscosity of the electrolyte and optimize the lithium ion transport channel by participating in the formation of a highly ionicly conductive SEI film, thereby improving the ionic conductivity of the electrolyte; at the same time, specific combinations of diluents, additives and solvents not only optimize the structure of the SEI film and reduce the migration resistance of lithium ions in the SEI film, but also suppress the interfacial side reactions of the positive electrode, constructing a stable electrode-electrolyte interface, thereby improving the cycle stability of the electrochemical device."

[0008] In some implementations, 0.020 ≤ (a×b) / (d×β) ≤ 0.093.

[0009] In some implementations, 0.030 ≤ (a×b) / (d×β) ≤ 0.068.

[0010] In some implementations, 0.150 ≤ a ≤ 0.250.

[0011] In some implementations, 0.100 ≤ b ≤ 0.200.

[0012] In some implementations, 0.005 ≤ c ≤ 0.020.

[0013] In some implementations, 0.530 ≤ d ≤ 0.745.

[0014] In some embodiments, the mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound is (0.5-6):1.

[0015] In some embodiments, the mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound is (2-4):1.

[0016] In some embodiments, the mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound is (1-7):1.

[0017] In some embodiments, the mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound is (3-5):1.

[0018] In some embodiments, the sulfonamide lithium salt includes at least one of lithium bis(fluorosulfonamide)imide (LiFSI, CAS No.: 171611-11-3) and lithium bis(trifluoromethanesulfonamide)imide (LiTFSI, CAS No.: 90076-65-6).

[0019] In some embodiments, the lithium borate compounds based on oxalate ligands include at least one of lithium difluorooxalate borate (LiDFOB, CAS No.: 409071-16-5) and lithium dioxalate borate (LiBOB, CAS No.: 244761-29-3).

[0020] In some embodiments, the fluorinated ether compound includes at least one selected from 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458, CAS No.: 16627-68-2), 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether (HFE-6512, CAS No.: 16627-71-7), 1,1,2,2,3,3,4,4-octafluoro-5-methoxypentane (CAS No.: 77527-96-9), and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE-347, CAS No.: 406-78-0).

[0021] In some embodiments, the nitrogen-containing compound includes at least one of quaternary ammonium salts, nitrate esters, nitrates, and nitrogen-containing organic compounds.

[0022] In some embodiments, the quaternary ammonium salt compound includes at least one of hexadecyltrimethylammonium chloride (CTAC, CAS No.: 112-02-7), hexadecyltrimethylammonium bromide (CTAB, CAS No.: 57-09-0), tetradecyltrimethylammonium bromide (TTAB, CAS No.: 1119-97-7), and tetrabutylammonium chloride (TBAC, CAS No.: 1112-67-0).

[0023] In some embodiments, the nitrate ester compound includes at least one of methyl nitrate, ethyl nitrate, propyl nitrate, isopropyl nitrate, butyl nitrate, amyl nitrate, isosorbide dinitrate (ISDN, CAS No.: 87-33-2), nitroglycerin, pentaerythritol tetranitrate, and nitrocellulose.

[0024] In some embodiments, the nitrate compound includes at least one of lithium nitrate, potassium nitrate, and sodium nitrate.

[0025] In some embodiments, the nitrogen-containing organic compound includes at least one of pyridine, imidazole, 1-(trimethylsilyl)benzotriazole (CAS No.: 43183-36-4), triethanolamine, ethylenediamine, and hexamethylenetetramine.

[0026] In some embodiments, the fluorine-free ether compound includes at least one of ethylene glycol dimethyl ether (DME, CAS No.: 110-71-4), 1,2-dimethoxypropane (DMP, CAS No.: 7778-85-0), and diethylene glycol dimethyl ether (DEGDME, CAS No.: 111-96-6).

[0027] In some embodiments, the fluorinated ketone compound includes perfluorohexanone (DTS, CAS No.: 756-13-8).

[0028] In some embodiments, the electrolyte further includes a polymer comprising structural units derived from acrylate monomer A and structural units derived from nitrile monomer B. The acrylate monomer A includes at least one of bis(trimethylolpropane)acrylate (DTPTA, CAS No.: 94108-97-1) and monomers having the structure shown in Formula I. The nitrile monomer B includes at least one of acrylonitrile (CH2=CHCN, CAS No.: 107-13-1), methacrylonitrile (CAS No.: 126-98-7), monomers having the structure shown in Formula II, trans-butenedionitrile (CNCH=CHCN, CAS No.: 764-42-1), and monomers having the structure shown in Formula III. R1 is selected from any one of CH2=CHCOOCH2-, CH2=C(CH3)COOCH2-, and CH2=CHCOOCH2CH2OCH2-. R2, R3, and R4 are each independently selected from H, unsubstituted C1-C20 alkyl groups, CH2=CHCOOCH2-, CH2=C(CH3)COOCH2-, and CH2=CHCOOCH2CH2OCH2-. R5, R6, and R7 are each independently selected from any one of unsubstituted C1-C20 alkyl, fluorinated C1-C20 alkyl, unsubstituted C6-C20 aryl, and fluorinated C6-C20 aryl.

[0029] In this application, when a polymer with a specific structure is combined with the aforementioned specific electrolyte matrix, the three-dimensional network structure of the polymer can reduce the migration resistance of lithium ions in the electrolyte matrix, which is beneficial to improving the ionic conductivity of the electrolyte. At the same time, the micropores of the polymer's gel framework can also fix the solvated small molecular clusters of the electrolyte matrix, achieving "in-situ locking" of the solvated clusters, enhancing the stability of the electrolyte matrix, and thus improving the cycle stability of the electrochemical device.

[0030] In some embodiments, the monomer having the structure shown in Formula I includes at least one of ethoxylated trimethylolpropane triacrylate (ETPTA, CAS No.: 28961-43-5), pentaerythritol tetraacrylate (PETEA, CAS No.: 4986-89-4), and trimethylolpropane trimethacrylate (TMPTMA, CAS No.: 3290-92-4).

[0031] In some embodiments, the monomer having the structure shown in Formula II includes at least one of 4-pentenonitrile (CAS No.: 592-51-8), 5-hexenonitrile (CAS No.: 5048-19-1), and 3-butenonitrile (CAS No.: 109-75-1).

[0032] In some embodiments, the monomer having the structure shown in Formula III includes trans-1,4-dicyano-2-butene (CAS No.: 1119-85-3).

[0033] In some embodiments, the polymer has a weight-average molecular weight (Mw) of M g / mol, a porosity of P, and a crosslinking density of X mol / cm³. 3 ,2.00≤P×[lg(M)-10X]≤5.00.

[0034] In this application, when the polymer satisfies "2.00≤P×[lg(M)-10X]≤5.00", it can better reduce the migration resistance of lithium ions in the electrolyte matrix, which is beneficial to further improve the ionic conductivity of the electrolyte. At the same time, it can also better enhance the stability of the electrolyte matrix, which is beneficial to further improve the cycle stability of the electrochemical device.

[0035] In some implementations, 2.40 ≤ P × [lg(M) - 10X] ≤ 4.80.

[0036] In some implementations, 3.20 ≤ P × [lg(M) - 10X] ≤ 4.40.

[0037] In some implementations, 0.92 ≤ P ≤ 0.98.

[0038] In some implementations, 1.0 × 10 5 ≤M≤5.0×10 5 .

[0039] In some implementations, 0.05 ≤ X ≤ 0.25.

[0040] In some embodiments, the mass percentage of the electrolyte matrix is ​​f, where 0.69 ≤ f < 1.00.

[0041] In some embodiments, the mass percentage of the polymer is in g, based on the mass of the electrolyte, where 0 < g ≤ 0.31.

[0042] In some embodiments, the electrolyte further includes an initiator.

[0043] In some embodiments, the electrolyte further includes at least one initiator selected from azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), dicumyl peroxide (DCP), and ammonium persulfate (APS).

[0044] In some embodiments, the initiator has a mass percentage content of 0.1-8% based on the mass of the electrolyte.

[0045] This application also provides an electrochemical device, including the electrolyte described above.

[0046] This application also provides an electronic device that includes the electrochemical device described above.

[0047] Compared with the prior art, the beneficial effects of this application are as follows: In the electrolyte system of this application, by controlling "0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c" 0.5 This can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0048] Specifically, when the electrolyte system of this application uses specific lithium salts, diluents, additives, and solvents, and satisfies "0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c", 0.5"At the same time, specific additives can promote the dissociation of specific lithium salts, increase the number of free lithium ions in the electrolyte, and specific combinations of diluents, additives and solvents can reduce the viscosity of the electrolyte and optimize the lithium ion transport channel by participating in the formation of a highly ionicly conductive SEI film, thereby improving the ionic conductivity of the electrolyte; at the same time, specific combinations of diluents, additives and solvents not only optimize the structure of the SEI film and reduce the migration resistance of lithium ions in the SEI film, but also suppress the interfacial side reactions of the positive electrode, constructing a stable electrode-electrolyte interface, thereby improving the cycle stability of the electrochemical device."

[0049] In this application, when a polymer with a specific structure is combined with the aforementioned specific electrolyte matrix, the three-dimensional network structure of the polymer can reduce the migration resistance of lithium ions in the electrolyte matrix, which is beneficial to improving the ionic conductivity of the electrolyte. At the same time, the micropores of the polymer's gel framework can also fix the solvated small molecular clusters of the electrolyte matrix, achieving "in-situ locking" of the solvated clusters, enhancing the stability of the electrolyte matrix, and thus improving the cycle stability of the electrochemical device.

[0050] In this application, when the polymer satisfies "2.00≤P×[lg(M)-10X]≤5.00", it can better reduce the migration resistance of lithium ions in the electrolyte matrix, which is beneficial to further improve the ionic conductivity of the electrolyte. At the same time, it can also better enhance the stability of the electrolyte matrix, which is beneficial to further improve the cycle stability of the electrochemical device. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] <General Definition> The term "average molecular weight of polymer" refers to the weight-average molecular weight (Mw) obtained by testing polymer gel particles obtained according to the "gel separation method," denoted as M, with units of g / mol. The "gel separation method" includes: disassembling a lithium-ion secondary battery (electrochemical device), subjecting the positive and negative electrodes, separator, and aluminum-plastic membrane to repeated soaking and filtration treatments with NMP (N-methylpyrrolidone) followed by toluene, repeating the process three times, acid washing (HCl) of the filtered cake, swelling the filter cake with toluene after acid washing, passing it through a 10 μm sieve, and drying the solid particles that are trapped on the 10 μm sieve surface and cannot pass through the sieve to constant weight, which are then polymer gel particles.

[0053] The term "porosity of polymer" refers to the percentage of the internal pore volume of polymer gel particles obtained by the "gel separation method" to their total volume, denoted as P. The "gel separation method" includes: disassembling a lithium-ion secondary battery (electrochemical device), subjecting the positive and negative electrodes, separator, and aluminum-plastic membrane to a series of soaking and filtration treatments, first with NMP (N-methylpyrrolidone) and then with toluene, repeating the process three times, acid washing (HCl) of the filter cake obtained by filtration, swelling the filter cake with toluene after acid washing, passing it through a 10μm pore size sieve, and drying the solid particles that are trapped on the surface of the 10μm sieve and cannot pass through the sieve to constant weight, which are then polymer gel particles.

[0054] The term "polymer crosslink density" refers to the molar concentration of effective crosslinks or crosslinking points per unit volume of polymer gel particles obtained by the "gel separation method," denoted as X, with units of mol / cm³. 3 The “gel separation method” includes: disassembling a lithium-ion secondary battery (electrochemical device); soaking and filtering the positive and negative electrodes, separator, and aluminum-plastic membrane in NMP (N-methylpyrrolidone) followed by toluene in stages, repeating the process three times; acid washing (HCl) of the filtered cake; swelling the filter cake with toluene after acid washing; passing the cake through a 10μm pore size sieve; and drying the solid particles that are trapped on the 10μm sieve surface and cannot pass through the sieve to a constant weight to obtain polymer gel particles.

[0055] The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0056] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0057] In this application, a list of items connected by the term "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0058] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0059] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0060] Throughout this specification, references to "implementation," "partial implementation," "one implementation," "some implementations," "another implementation," "specific implementation," or "partial implementation" mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0061] I. Electrolyte This application provides an electrolyte comprising an electrolyte matrix, wherein the electrolyte matrix includes a lithium salt, a diluent, an additive, and a solvent. The lithium salts include sulfonylimide lithium salts and lithium borate compounds based on oxalate ligands; The diluent includes fluorinated ether compounds; The additives include nitrogen-containing compounds; The solvents include non-fluorinated ether compounds and fluorinated ketone compounds; Based on the mass of the electrolyte matrix, the mass percentage of the lithium salt is a, the mass percentage of the diluent is b, the mass percentage of the additive is c, and the mass percentage of the solvent is d. 0.015 ≤ (a × b) / (d × β) ≤ 0.095, β = 1 + 0.07 × c 0.5 .

[0062] In the electrolyte system of this application, by controlling "0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c" 0.5 This can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0063] Specifically, when the electrolyte system of this application uses specific lithium salts, diluents, additives, and solvents, and satisfies "0.015≤(a×b) / (d×β)≤0.095, β=1+0.07×c", 0.5 "At the same time, specific additives can promote the dissociation of specific lithium salts, increase the number of free lithium ions in the electrolyte, and specific combinations of diluents, additives and solvents can reduce the viscosity of the electrolyte and optimize the lithium ion transport channel by participating in the formation of a highly ionicly conductive SEI film, thereby improving the ionic conductivity of the electrolyte; at the same time, specific combinations of diluents, additives and solvents not only optimize the structure of the SEI film and reduce the migration resistance of lithium ions in the SEI film, but also suppress the interfacial side reactions of the positive electrode, constructing a stable electrode-electrolyte interface, thereby improving the cycle stability of the electrochemical device."

[0064] In some implementations, (a×b) / (d×β) can be 0.015, 0.016, 0.017, 0.018, 0.019, 0.020, 0.021, 0.022, 0.023, 0.025, 0.027, 0.028, 0.029, 0.030, 0.031, 0.032, 0.033, 0.035, 0.040, 0.043, 0.043, 0.045, 0.046, 0.047, 0.048, or 0.04. 9. 0.050, 0.055, 0.060, 0.061, 0.062, 0.063, 0.064, 0.065, 0.066, 0.067, 0.068, 0.069, 0.070, 0.075, 0.080, 0.085, 0.086, 0.087, 0.088, 0.089, 0.090, 0.091, 0.092, 0.093, 0.094 or 0.095, or within the range of any two of the above values.

[0065] In some implementations, 0.020 ≤ (a×b) / (d×β) ≤ 0.093.

[0066] In some implementations, 0.030 ≤ (a×b) / (d×β) ≤ 0.068.

[0067] In some implementations, 0.150 ≤ a ≤ 0.250. For example, a can be 0.150, 0.160, 0.170, 0.180, 0.190, 0.200, 0.210, 0.220, 0.230, 0.240 or 0.250, or fall within the range of any two of the above values.

[0068] In some implementations, 0.100 ≤ b ≤ 0.200. For example, b can be 0.100, 0.110, 0.120, 0.130, 0.140, 0.150, 0.160, 0.170, 0.180, 0.190 or 0.200, or fall within the range of any two of the above values.

[0069] In some implementations, 0.005 ≤ c ≤ 0.020. For example, c can be 0.005, 0.006, 0.007, 0.008, 0.009, 0.010, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, or 0.020, or fall within the range of any two of the above values.

[0070] In some implementations, 0.530 ≤ d ≤ 0.745. For example, d can be 0.530, 0.535, 0.560, 0.565, 0.570, 0.575, 0.580, 0.585, 0.590, 0.595, 0.600, 0.610, 0.620, 0.630, 0.635, 0.637, 0.638, 0.639, 0.640, 0.650, 0.660, 0.670, 0.680, 0.690, 0.700, 0.710, 0.720, 0.730, 0.740, 0.741, 0.742, 0.743, 0.744, or 0.745, or fall within the range of any two of the above values.

[0071] In some embodiments, the mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound is (0.5-6):1. Exemplarily, the mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.3:1, 1.5:1, 1.8:1, 2:1, 2.3:1, 2.5:1, 2.8:1, 3:1, 3.3:1, 3.5:1, 3.8:1, 4:1, 4.3:1, 4.5:1, 4.8:1, 5:1, 5.3:1, 5.5:1, 5.8:1, or 6:1, or fall within the range of any two of the above values.

[0072] In some embodiments, the mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound is (2-4):1.

[0073] In some embodiments, the mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound is (1-7):1. Exemplarily, the mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound can be 1:1, 1.3:1, 1.5:1, 1.8:1, 2:1, 2.3:1, 2.5:1, 2.8:1, 3:1, 3.3:1, 3.5:1, 3.8:1, 4:1, 4.3:1, 4.5:1, 4.8:1, 5:1, 5.3:1, 5.5:1, 5.8:1, 6:1, 6.3:1, 6.5:1, 6.8:1, or 7:1, or fall within the range of any two of the above values.

[0074] In some embodiments, the mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound is (3-5):1.

[0075] In some embodiments, the sulfonamide lithium salt includes at least one of lithium bis(fluorosulfonamide)imide (LiFSI, CAS No.: 171611-11-3) and lithium bis(trifluoromethanesulfonamide)imide (LiTFSI, CAS No.: 90076-65-6).

[0076] In some embodiments, the lithium borate compounds based on oxalate ligands include at least one of lithium difluorooxalate borate (LiDFOB, CAS No.: 409071-16-5) and lithium dioxalate borate (LiBOB, CAS No.: 244761-29-3).

[0077] In some embodiments, the fluorinated ether compound includes at least one selected from 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458, CAS No.: 16627-68-2), 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether (HFE-6512, CAS No.: 16627-71-7), 1,1,2,2,3,3,4,4-octafluoro-5-methoxypentane (CAS No.: 77527-96-9), and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE-347, CAS No.: 406-78-0).

[0078] In some embodiments, the nitrogen-containing compound includes at least one of quaternary ammonium salts, nitrate esters, nitrates, and nitrogen-containing organic compounds.

[0079] In some embodiments, the quaternary ammonium salt compound includes at least one of hexadecyltrimethylammonium chloride (CTAC, CAS No.: 112-02-7), hexadecyltrimethylammonium bromide (CTAB, CAS No.: 57-09-0), tetradecyltrimethylammonium bromide (TTAB, CAS No.: 1119-97-7), and tetrabutylammonium chloride (TBAC, CAS No.: 1112-67-0).

[0080] In some embodiments, the nitrate ester compound includes at least one of methyl nitrate, ethyl nitrate, propyl nitrate, isopropyl nitrate, butyl nitrate, amyl nitrate, isosorbide dinitrate (ISDN, CAS No.: 87-33-2), nitroglycerin, pentaerythritol tetranitrate, and nitrocellulose.

[0081] In some embodiments, the nitrate compound includes at least one of lithium nitrate, potassium nitrate, and sodium nitrate.

[0082] In some embodiments, the nitrogen-containing organic compound includes at least one of pyridine, imidazole, 1-(trimethylsilyl)benzotriazole (CAS No.: 43183-36-4), triethanolamine, ethylenediamine, and hexamethylenetetramine.

[0083] In some embodiments, the additive further includes at least one of sulfur-containing compounds, phosphorus-containing compounds, boron-containing compounds, and halogenated carbonate compounds.

[0084] In some embodiments, the sulfur-containing compound includes at least one of 1,3-propanesulfonate lactone (PS), vinyl sulfate (DTD), vinyl sulfite (ES), 1,4-butanesulfonate lactone (BS), dimethyl sulfoxide (DMSO), and diphenyl sulfide.

[0085] In some embodiments, the phosphorus-containing compound includes at least one of trimethyl phosphate (TMP), triethyl phosphate (TEP), triphenyl phosphate (TPP), triphenyl phosphite, hexafluorocyclotriphosphazene, and tris(trimethylsilyl)phosphite (TMSPi).

[0086] In some embodiments, the boron-containing compound includes at least one of lithium tetrafluoroborate (LiBF4), tris(pentafluorophenyl)borane (TPFPB), and tris(trimethylsilane)borate (TMSB).

[0087] In some embodiments, the halocarbonate compound includes at least one of fluoroethylene carbonate (FEC) and vinylene carbonate (VC).

[0088] In some embodiments, the fluorine-free ether compound includes at least one of ethylene glycol dimethyl ether (DME, CAS No.: 110-71-4), 1,2-dimethoxypropane (DMP, CAS No.: 7778-85-0), and diethylene glycol dimethyl ether (DEGDME, CAS No.: 111-96-6).

[0089] In some embodiments, the fluorinated ketone compound includes perfluorohexanone (DTS, CAS No.: 756-13-8).

[0090] In some embodiments, the electrolyte further includes a polymer comprising structural units derived from acrylate monomer A and structural units derived from nitrile monomer B. The acrylate monomer A includes at least one of bis(trimethylolpropane)acrylate (DTPTA, CAS No.: 94108-97-1) and monomers having the structure shown in Formula I. The nitrile monomer B includes at least one of acrylonitrile (CH2=CHCN, CAS No.: 107-13-1), methacrylonitrile (CAS No.: 126-98-7), monomers having the structure shown in Formula II, trans-butenedionitrile (CNCH=CHCN, CAS No.: 764-42-1), and monomers having the structure shown in Formula III. R1 is selected from any one of CH2=CHCOOCH2-, CH2=C(CH3)COOCH2-, and CH2=CHCOOCH2CH2OCH2-. R2, R3, and R4 are each independently selected from H, unsubstituted C1-C20 alkyl groups, CH2=CHCOOCH2-, CH2=C(CH3)COOCH2-, and CH2=CHCOOCH2CH2OCH2-. R5, R6, and R7 are each independently selected from any one of unsubstituted C1-C20 alkyl, fluorinated C1-C20 alkyl, unsubstituted C6-C20 aryl, and fluorinated C6-C20 aryl.

[0091] In this application, when a polymer with a specific structure is combined with the aforementioned specific electrolyte matrix, the three-dimensional network structure of the polymer can reduce the migration resistance of lithium ions in the electrolyte matrix, which is beneficial to improving the ionic conductivity of the electrolyte. At the same time, the micropores of the polymer's gel framework can also fix the solvated small molecular clusters of the electrolyte matrix, achieving "in-situ locking" of the solvated clusters, enhancing the stability of the electrolyte matrix, and thus improving the cycle stability of the electrochemical device.

[0092] In some embodiments, the monomer having the structure shown in Formula I includes at least one of ethoxylated trimethylolpropane triacrylate (ETPTA, CAS No.: 28961-43-5), pentaerythritol tetraacrylate (PETEA, CAS No.: 4986-89-4), and trimethylolpropane trimethacrylate (TMPTMA, CAS No.: 3290-92-4).

[0093] In some embodiments, the monomer having the structure shown in Formula II includes at least one of 4-pentenonitrile (CAS No.: 592-51-8), 5-hexenonitrile (CAS No.: 5048-19-1), and 3-butenonitrile (CAS No.: 109-75-1).

[0094] In some embodiments, the monomer having the structure shown in Formula III includes at least one of trans-1,4-dicyano-2-butene (CAS No.: 1119-85-3).

[0095] In some embodiments, the polymer has a weight-average molecular weight (Mw) of M g / mol, a porosity of P, and a crosslinking density of X mol / cm³. 3 ,2.00≤P×[lg(M)-10X]≤5.00.

[0096] In this application, when the polymer satisfies "2.00≤P×[lg(M)-10X]≤5.00", it can better reduce the migration resistance of lithium ions in the electrolyte matrix, which is beneficial to further improve the ionic conductivity of the electrolyte. At the same time, it can also better enhance the stability of the electrolyte matrix, which is beneficial to further improve the cycle stability of the electrochemical device.

[0097] In some implementations, P×[lg(M)-10X] can be 2.00, 2.10, 2.20, 2.30, 2.40, 2.45, 2.60, 2.70, 2.80, 2.90, 3.00, 3.10, 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, 3.80, 3.81, 3.82, 3.83, or 3. 84, 3.85, 3.90, 4.00, 4.10, 4.20, 4.30, 4.31, 4.32, 4.33, 4.34, 4.35, 4.40, 4.50, 4.60, 4.70, 4.75, 4.76, 4.77, 4.78, 4.79, 4.80, 4.90 or 5.00, or within the range of any two of the above values.

[0098] In some implementations, 2.40 ≤ P × [lg(M) - 10X] ≤ 4.80.

[0099] In some implementations, 3.20 ≤ P × [lg(M) - 10X] ≤ 4.40.

[0100] In some implementations, 0.92 ≤ P ≤ 0.98. For example, P can be 0.92, 0.93, 0.94, 0.95, 0.96, 0.97 or 0.98, or fall within the range of any two of the above values.

[0101] In some implementations, 1.0 × 10 5 ≤M≤5.0×10 5 For example, M can be 1.0 × 10⁻⁶. 5 1.1×10 5 1.2×10 5 1.3×10 5 1.4×10 5 1.5×10 5 1.8×10 5 2×10 5 2.3×10 5 2.5×10 5 2.8×10 5 3×10 5 3.3×10 5 3.5×10 5 3.6×10 5 3.7×10 5 3.8×10 5 3.9×10 5 4×10 5 4.1×10 5 4.2×10 5 4.3×10 5 4.4×10 5 4.5×10 5 4.6×10 5 4.7×10 5 4.8×10 5 4.9×10 5 Or 5.0×10 5 , or within the range of any two of the above values.

[0102] In some implementations, 0.05 ≤ X ≤ 0.25. For example, X can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, or 0.25, or fall within the range of any two of the above values.

[0103] In some embodiments, the mass percentage of the electrolyte matrix is ​​f, where 0.69 ≤ f < 1.00, based on the mass of the electrolyte.

[0104] In some implementations, f can be 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, or 0.99, or fall within the range of any two of the above values.

[0105] In some embodiments, the mass percentage of the polymer is in g, based on the mass of the electrolyte, where 0 < g ≤ 0.31.

[0106] In some implementations, g can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or 0.31, or fall within the range of any two of the above values.

[0107] In some embodiments, the electrolyte further includes an initiator.

[0108] In some embodiments, the electrolyte further includes at least one initiator selected from azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), dicumyl peroxide (DCP), and ammonium persulfate (APS).

[0109] In some embodiments, the initiator has a mass percentage content of 0.1-8% based on the mass of the electrolyte.

[0110] In some embodiments, the initiator is present in the following mass percentages based on the mass of the electrolyte: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%. %, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9% or 8.0%, or within the range of any two of the above values.

[0111] II. Electrochemical Device This application also provides an electrochemical device, including the electrolyte described above.

[0112] In this application, an electrochemical device includes any device in which an electrochemical reaction occurs to interconvert chemical energy and electrical energy.

[0113] In some embodiments, the electrochemical device also includes a positive electrode, a negative electrode, and a diaphragm.

[0114] 1. Positive electrode In some embodiments, the positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector.

[0115] In some embodiments, the positive current collector is a metal foil or a composite current collector. In some embodiments, the metal foil is aluminum foil. The composite current collector may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate. In some embodiments, the conductive layer may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon nanotubes, carbon nanotubes, activated carbon, and mesoporous carbon.

[0116] In some embodiments, the positive electrode active material layer may include a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent.

[0117] In some embodiments, the positive electrode active material is selected from LiCoO2, LiNiO2, and LiNi x Mn y O2, Li 1+ z Ni x Mn y Co 1-x-y O2, LiNi x Co y Al z The group consisting of O2, LiV2O5, LiTiS2, LiMoS2, LiMnO2, LiCrO2, LiMn2O4, Li2MnO3, LiFeO2, LiFePO4, LiMnPO4, and combinations thereof, wherein each x is independently 0.2 to 0.9; each y is independently 0.1 to 0.45; and each z is independently 0 to 0.2. The positive electrode active material of this application is not limited to the above-mentioned materials, but also includes other materials that can be used as positive electrode active materials.

[0118] In some embodiments, the positive electrode binder includes at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer. The positive electrode binder of this application is not limited to the above materials, but also includes other materials that can be used as battery positive electrode binders.

[0119] In some embodiments, the positive electrode conductive agent may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, superconducting carbon, acetylene black, Ketjen black, carbon dots, carbon fibers, carbon nanofibers, graphitized carbon sheets, carbon nanotubes, activated carbon, and mesoporous carbon. The positive electrode conductive agent in this application is not limited to the above materials, but also includes other materials that can be used as positive electrode conductive agents in batteries.

[0120] 2. Negative electrode In some embodiments, the negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector.

[0121] In some embodiments, the negative current collector is a metal foil or a composite current collector. In some embodiments, the metal foil is a copper foil. The composite current collector may include a metal foil substrate and a conductive layer disposed on at least one side of the metal foil substrate.

[0122] In some embodiments, the conductive layer may include at least one of carbon, carbon black, graphite, expanded graphite, graphene, graphene nanosheets, carbon fiber, carbon nanofiber, graphitized carbon sheet, carbon tube, carbon nanotube, activated carbon, and mesoporous carbon.

[0123] In some implementations, the negative electrode active material layer comprises lithium metal.

[0124] 3. Diaphragm This application does not impose any particular limitation on the diaphragm, as long as it can achieve the purpose of this application. The diaphragm used in this application can be any diaphragm known in the prior art. For example, the type of diaphragm can include, but is not limited to, at least one of woven membranes, nonwoven membranes, microporous membranes, composite membranes, rolled membranes, and spun membranes. The material of the diaphragm can include, but is not limited to, at least one of polyethylene (PE), polyolefins (PO) mainly composed of polypropylene (PP), polyester, cellulose, polyimide (PI), polyamide (PA), spandex, and aramid. Polyester can include, but is not limited to, polyethylene terephthalate (PET) film.

[0125] In some embodiments, the diaphragm includes a substrate layer. The substrate layer may include, but is not limited to, at least one of a nonwoven fabric, membrane, or composite membrane having a porous structure. The material of the substrate layer may include, but is not limited to, at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. In some embodiments, the substrate layer may include, but is not limited to, at least one of a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite membrane.

[0126] In some embodiments, the diaphragm further includes a surface treatment layer disposed on at least one surface of the substrate layer. The surface treatment layer may include, but is not limited to, at least one of a polymer layer, an inorganic layer, and a layer formed by a mixture of polymers and inorganic substances. The polymer layer includes polymers. This application does not particularly limit the polymer, as long as it achieves the purpose of this application. For example, the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymers, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene). The inorganic layer includes inorganic particles and a binder. This application does not particularly limit the inorganic particles and binder, as long as they achieve the purpose of this application. For example, the inorganic particles may include, but are not limited to, at least one of alumina, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. For example, the adhesive may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyacrylic acid, polyacrylonitrile, polyimide, polyurethane, polyvinyl butyral, polyvinylpyrrolidone (PVP), acrylic acid-acrylonitrile-acrylamide copolymer, and acrylic acid-acrylonitrile-acrylate copolymer.

[0127] In some embodiments, the present application does not have a particular limitation on the thickness of the diaphragm, as long as the purpose of the present application can be achieved. For example, the thickness of the diaphragm is from 1 μm to 500 μm.

[0128] III. Electronic Devices This application also provides an electronic device that includes the electrochemical device described above.

[0129] The electronic device described in this application is not particularly limited and can be any electronic device known in the prior art. The electrochemical device described in this application is also not particularly limited in its use and can be used in any electronic device known in the prior art. According to some embodiments of this application, the electronic device includes, but is not limited to, mobile phones, smartphones, laptops, tablets, wearable devices, smartwatches, smart bracelets, smart glasses, power banks, televisions, game consoles, game controllers, digital cameras, smart speakers, headphones, keyboards, mice, monitors, drones, audio equipment, home appliances, toys, power tools, automobiles, motorcycles, electric bicycles, bicycles, robots, robot dogs, industrial robots, and android robots.

[0130] IV. Testing Methods 1. Polymer weight-average molecular weight (Mw) test (1) Disassemble the lithium-ion secondary battery (electrochemical device), and soak and filter the positive and negative electrodes, separator and aluminum-plastic membrane in NMP (N-methylpyrrolidone) and then in toluene in stages, and repeat the process three times. The filter cake obtained by filtration is acid washed (0.14mol / L HCl solution). After acid washing, the filter cake is swollen with toluene and passed through a 10μm sieve. The solid particles that are trapped on the 10μm sieve surface and cannot pass through the sieve are dried at 60℃ to constant weight, which are polymer gel particles. (2) Take 0.1g of polymer gel particles, dissolve them in 10mL of tetrahydrofuran, filter them through a 0.22μm polytetrafluoroethylene filter membrane, and use a gel permeation chromatograph coupled with a multi-angle laser light scattering detector to test the weight-average molecular weight (Mw). The test temperature is set at 40℃ and the flow rate is 1.0 mL / min. The experiment is repeated 3 times and the arithmetic mean is taken.

[0131] 2. Polymer porosity testing (1) Disassemble the lithium-ion secondary battery (electrochemical device), and soak and filter the positive and negative electrodes, separator and aluminum-plastic membrane in NMP (N-methylpyrrolidone) and then in toluene in stages, and repeat the process three times. The filter cake obtained by filtration is acid washed (0.14mol / L HCl solution). After acid washing, the filter cake is swollen with toluene and passed through a 10μm sieve. The solid particles that are trapped on the 10μm sieve surface and cannot pass through the sieve are dried at 60℃ to constant weight, which are polymer gel particles. (2) Take polymer gel particles and determine the porosity of the polymer by gas adsorption method; by measuring the adsorption isotherm of nitrogen gas on the polymer at low temperature, calculate the specific surface area using the BET (Brunauer-Emmett-Teller) model, and analyze the pore size distribution and pore volume through adsorption data. The test conditions are based on standard GB / T19587-2017. Finally, the porosity of the polymer is calculated.

[0132] 3. Polymer crosslinking density test (1) Disassemble the lithium-ion secondary battery (electrochemical device), and soak and filter the positive and negative electrodes, separator and aluminum-plastic membrane in NMP (N-methylpyrrolidone) and then in toluene in stages, and repeat the process three times. The filter cake obtained by filtration is acid washed (0.14mol / L HCl solution). After acid washing, the filter cake is swollen with toluene and passed through a 10μm sieve. The solid particles that are trapped on the 10μm sieve surface and cannot pass through the sieve are dried at 60℃ to constant weight, which are polymer gel particles. (2) Accurately weigh the mass m0 (g) of the polymer gel particles after drying to constant weight at 60℃. Place the polymer gel particles into a weighing bottle or glass bottle containing sufficient solvent (e.g., toluene), ensuring that the solvent completely submerges the polymer sample. Seal the container to prevent solvent evaporation. Place the container in a water bath or incubator at a constant temperature of 25℃ to allow swelling. Remove the polymer gel particles every 12 hours, quickly absorb excess solvent from the surface of the polymer gel particles with filter paper, and weigh the swollen mass m. t (g), then immediately return to the solvent to continue swelling until the mass difference between two consecutive weighings is less than 0.5%, at which point the polymer gel particles are considered to have reached swelling equilibrium. Record the equilibrium swelling mass m of the polymer gel particles at this point. z (g), and calculate the mass swelling ratio Q using the following formula. m And the volume fraction of the polymer, v2: Q m =m z / m0, v2=1 / [1+(Q m -1)ρ p / ρ e ], Where, ρ e Density (g / cm³) of solvent (toluene) 3 );ρ p Density (g / cm³) of the polymer before swelling and in a completely dry state. 3 ), ρ p The density was obtained by testing with a true density analyzer using the gas displacement method. Substitute the calculated v2 into the formula below to calculate the crosslinking density J (mol / cm²) of the polymer. 3 ): J = -[ln(1-v2)+v2+Sv2] 2 ] / [V1(v2 1 / 3 -v2 / 2)]; Where S is the interaction parameter correction factor of the polymer-toluene system, which is taken as 0.45; V1 is the molar volume (cm³) of the solvent (toluene). 3 / mol).

[0133] 4. Electrolyte ionic conductivity test The ionic conductivity of the electrolyte was measured at 25℃ using a Shanghai Leici DDSJ-308F conductivity meter (unit: mS / cm).

[0134] 5. Cyclic stability testing of electrochemical devices In an environment of 25°C, the electrochemical device is charged to 4.6V at a constant current of 0.5C, charged to the cutoff current of 0.05C at a constant voltage, and then discharged to 3.0V at a constant current of 0.5C. This constitutes one charge-discharge cycle. This charge-discharge cycle is repeated multiple times until the capacity retention of the electrochemical device drops to 80%. The number of charge-discharge cycles at this point is recorded as the number of cycles at 80% capacity retention (unit: cycles). The greater the number of cycles with 80% capacity retention, the stronger the cycling stability of the electrochemical device. 6. Interface impedance test In the frequency range 10 -2 -10 5 Electrochemical impedance spectroscopy (EIS) was performed on the electrochemical device using a Zahner electrochemical workstation under the conditions of Hz and 5mV amplitude: First, select EIS mode, enter the parameter setting interface, select different impedance test modes, and then set the test frequency range (10 Hz, 5mV). -2 -10 5 The test results are obtained by taking parameters such as the starting frequency (Hz), the frequency test sequence, and the sampling interval. Next, the impedance spectrum was fitted to the equivalent circuit (EEC) using Zsimpwin fitting software: First, open the impedance spectrum to be fitted. Here, you can modify the color, thickness, and format of the spectral lines. Select Nyquist graphical representation, and then click the "Model Circuit" icon to create an equivalent circuit model. You can add the required circuit components by clicking "Add" and then connect them through connection points. Provide the frequency range to generate a simulation graph. After simulation, open the simulation graph in the graphics window. In order to fit the simulated spectral lines to the measured EIS impedance spectrum, there are three simulation options: Original, Smoothed, and Z-HIT. Select Original and then click "Fit" to perform the fitting. After the fitting is completed, the impedance values ​​and errors of each component will be provided. Finally, save and export the fitting data to obtain the interface impedance (unit: Ω) data of the electrochemical device.

[0135] V. Examples It should be noted that, in the specific embodiments of this application, a sulfide all-solid-state battery is used as an example of an electrochemical device to explain this application, but the electrochemical device of this application is not limited to a sulfide all-solid-state battery.

[0136] Unless otherwise specified, all reagents, materials, and instruments used in the following examples and comparative examples are commercially available. Furthermore, unless otherwise specified, "parts" and "%" refer to mass measurements.

[0137] Example 1 This embodiment provides an electrolyte, including an electrolyte matrix comprising a lithium salt, a diluent, additives, and a solvent. The lithium salts include sulfonylimide lithium salts (lithium difluorosulfonylimide, LiFSI, CAS No.: 171611-11-3) and lithium borate compounds based on oxalate ligands (lithium difluorooxalate borate, LiDFOB, CAS No.: 409071-16-5). The diluent includes fluorinated ether compounds (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, HFE-458, CAS No.: 16627-68-2); The additives include nitrogen-containing compounds (hexadecyltrimethylammonium chloride, CTAC, CAS No.: 112-02-7); The solvents include non-fluorinated ether compounds (ethylene glycol dimethyl ether, DME, CAS No.: 110-71-4) and fluorinated ketone compounds (perfluorohexanone, DTS, CAS No.: 756-13-8); Based on the mass of the electrolyte matrix, the mass percentage of the lithium salt is a, a = 0.200, the mass percentage of the diluent is b, b = 0.150, the mass percentage of the additive is c, c = 0.013, and the mass percentage of the solvent is d, d = 0.637. (a × b) / (d × β) = 0.047, β = 1 + 0.07 × c 0.5 =1.008; The mass ratio of the sulfonylimide lithium salt (LiFSI) to the oxalate-ligand-based lithium borate compound (LiDFOB) is 3:1; the mass ratio of the non-fluorinated ether compound (DME) to the fluorinated ketone compound (DTS) is 4:1. This embodiment also provides a lithium-ion secondary battery (electrochemical device), the preparation method of which includes the following steps: 1. Preparation of the positive electrode LiCoO2, conductive carbon black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97:1.5:1.5. N-methylpyrrolidone (NMP) was added and the mixture was stirred evenly under vacuum to obtain a positive electrode slurry with a solid content of 70 wt%. A 9 µm aluminum foil was used as the positive electrode current collector, and the positive electrode slurry was uniformly coated on both surfaces of the current collector. After drying, cold pressing, and cutting, a positive electrode sheet with a positive electrode active material layer on both sides was obtained, with a thickness of 100 μm. 2. Preparation of the negative electrode Lithium metal is used as the active material with an active material loading of 100 wt%; 8 μm copper foil is used as the negative electrode current collector, and lithium metal is uniformly rolled onto the two surfaces of the negative electrode current collector. After cutting, a negative electrode sheet with a negative electrode active material layer on both sides is obtained, and the thickness of the negative electrode active material layer is 100 μm. 3. Preparation of electrolyte In a dry argon atmosphere glove box, the above-mentioned diluent, additives and solvents are mixed to obtain a non-aqueous solvent. Then, the above-mentioned lithium salt is added to the non-aqueous solvent to dissolve and mix evenly to obtain an electrolyte. 4. Preparation of lithium-ion secondary batteries (electrochemical devices) The positive electrode, separator (8μm polyethylene porous membrane), and negative electrode prepared above are stacked in sequence and wound to obtain an electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, dried, and then injected with electrolyte. After vacuum sealing, standing, formation, degassing, and edge trimming, a lithium-ion secondary battery is obtained.

[0138] Examples 2-5 and Comparative Examples 1-4 The differences between Examples 2-5 and Comparative Examples 1-4 and Example 1 lie in the mass percentages of lithium salt (a), diluent (b), additives (c), and solvent (d) in the electrolyte matrix, as shown in Table 1. All other aspects are consistent with Example 1. The amounts of lithium salt, diluent, additives, and solvents in the electrolyte matrix were adjusted to achieve the following results: a) as shown in Table 1; b) as shown in Table 1; c) as shown in Table 1; and d) as shown in Table 1.

[0139] Examples 6-9 and Comparative Examples 5-6 The differences between Examples 6-9 and Comparative Examples 5-6 and Example 1 are as follows: the mass ratios of the sulfonylimide lithium salt (lithium difluorosulfonylimide, LiFSI, CAS No.: 171611-11-3) and the lithium borate compound based on the oxalate ligand (lithium difluorooxalate borate, LiDFOB, CAS No.: 409071-16-5) are different, as shown in Table 2. All other aspects are the same as in Example 1.

[0140] Examples 10-13 and Comparative Examples 7-8 The differences between Examples 10-13 and Comparative Examples 7-8 and Example 1 are that the mass ratios of the non-fluorinated ether compound (ethylene glycol dimethyl ether, DME, CAS No.: 110-71-4) and the fluorinated ketone compound (perfluorohexanone, DTS, CAS No.: 756-13-8) are different, as shown in Table 3. All other aspects are the same as in Example 1.

[0141] Examples 14-16 and Comparative Example 9 Examples 14-16 and Comparative Example 9 differ from Example 1 in that the types of additives are different, as shown in Table 4. All other aspects are the same as in Example 1.

[0142] Example 17 The difference between Example 17 and Example 1 is as follows: (1) The lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, CAS No.: 90076-65-6) of the sulfonylimide lithium salt was replaced with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, CAS No.: 90076-65-6) in Example 1; (2) Lithium borate compounds based on oxalate ligands were replaced with lithium difluorooxalate borate (LiDFOB) in Example 1 by lithium dioxalate borate (LiBOB, CAS No.: 244761-29-3); (3) Fluorinated ether compounds were replaced with 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether (HFE-6512, CAS No.: 16627-71-7) instead of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458, CAS No.: 16627-68-2) in Example 1; (4) The quaternary ammonium salt was replaced by hexadecyltrimethylammonium bromide (CTAB, CAS No.: 57-09-0) instead of hexadecyltrimethylammonium chloride (CTAC, CAS No.: 112-02-7) in Example 1; (5) The fluorine-free ether compounds were replaced with 1,2-dimethoxypropane (DMP, CAS No.: 7778-85-0) instead of ethylene glycol dimethyl ether (DME, CAS No.: 110-71-4) in Example 1; Everything else is the same as in Example 1.

[0143] Example 18 This embodiment provides an electrolyte comprising an electrolyte matrix, a polymer, and an initiator (azobisisobutyronitrile, AIBN). The electrolyte matrix includes a lithium salt, a diluent, additives, and a solvent. The lithium salts include sulfonylimide lithium salts (lithium difluorosulfonylimide, LiFSI, CAS No.: 171611-11-3) and lithium borate compounds based on oxalate ligands (lithium difluorooxalate borate, LiDFOB, CAS No.: 409071-16-5). The diluent includes fluorinated ether compounds (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, HFE-458, CAS No.: 16627-68-2); The additives include nitrogen-containing compounds (hexadecyltrimethylammonium chloride, CTAC, CAS No.: 112-02-7); The solvents include non-fluorinated ether compounds (ethylene glycol dimethyl ether, DME, CAS No.: 110-71-4) and fluorinated ketone compounds (perfluorohexanone, DTS, CAS No.: 756-13-8); Based on the mass of the electrolyte matrix, the mass percentage of the lithium salt is a, a = 0.200, the mass percentage of the diluent is b, b = 0.150, the mass percentage of the additive is c, c = 0.013, and the mass percentage of the solvent is d, d = 0.637. (a × b) / (d × β) = 0.047, β = 1 + 0.07 × c 0.5 =1.008; The mass ratio of the sulfonylimide lithium salt (LiFSI) to the oxalate-ligand-based lithium borate compound (LiDFOB) is 3:1; the mass ratio of the non-fluorinated ether compound (DME) to the fluorinated ketone compound (DTS) is 4:1. The polymer comprises structural units derived from acrylate monomer A and structural units derived from nitrile monomer B. The acrylate monomer A comprises bis(trimethylolpropane) acrylate (DTPTA, CAS No.: 94108-97-1) and ethoxylated trimethylolpropane triacrylate (ETPTA, CAS No.: 28961-43-5) in a mass ratio of 1:1.2. The nitrile monomer B comprises acrylonitrile (CAS No.: 107-13-1). The polymer has a weight-average molecular weight (Mw) of M g / mol, where M = 3.0 × 10⁻⁶. 5 The polymer has a porosity of P, P = 0.96, a crosslinking density of X, X = 0.15, and P × [lg(M) - 10X] = 3.82; based on the mass of the electrolyte, the mass percentage of the electrolyte matrix is ​​f, f = 0.94, the mass percentage of the polymer is g, g = 0.05, and the mass percentage of the initiator (azobisisobutyronitrile, AIBN) is 0.01, i.e., 1%; This embodiment also provides a lithium-ion secondary battery (electrochemical device), the preparation method of which includes the following steps: 1. Preparation of the positive electrode LiCoO2 (positive electrode active material), conductive carbon black (positive electrode conductive agent), and polyvinylidene fluoride (PVDF) (positive electrode binder) were mixed in a mass ratio of 97:1.5:1.5. N-methylpyrrolidone (NMP) was added, and the mixture was stirred evenly under vacuum to obtain a positive electrode slurry with a solid content of 70 wt%. A 9 µm aluminum foil was used as the positive electrode current collector, and the positive electrode slurry was uniformly coated on both surfaces of the current collector. After drying, cold pressing, and cutting, a positive electrode sheet with a positive electrode active material layer on both sides was obtained, with a thickness of 100 µm. 2. Preparation of the negative electrode Lithium metal is used as the active material with an active material loading of 100 wt%; 8 μm copper foil is used as the negative electrode current collector, and lithium metal is uniformly rolled onto the two surfaces of the negative electrode current collector. After cutting, a negative electrode sheet with a negative electrode active material layer on both sides is obtained, and the thickness of the negative electrode active material layer is 100 μm. 3. Preparation of electrolyte precursor In a dry argon atmosphere glove box, the above-mentioned diluent, additives and solvents are mixed to obtain a non-aqueous solvent. Then, the above-mentioned lithium salt is added to the non-aqueous solvent to dissolve and mix evenly to obtain the electrolyte matrix. Then, the electrolyte matrix, acrylate monomer A, nitrile monomer B and initiator (azobisisobutyronitrile, AIBN) are mixed at a mass ratio of 94:3.5:1.5:1 to obtain the electrolyte precursor. 4. Preparation of lithium-ion secondary batteries (electrochemical devices) The positive electrode, separator (8μm polyethylene porous membrane), and negative electrode prepared above are stacked in sequence and wound to obtain an electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, dried, and then injected with an electrolyte precursor. It is then allowed to stand at 65°C for 12 hours to initiate the polymerization of acrylate monomer A and nitrile monomer B to obtain a polymer. The polymer is then obtained through vacuum sealing, standing, formation, degassing, and edge trimming to obtain a lithium-ion secondary battery.

[0144] Examples 19-22 Examples 19-22 differ from Example 18 in that the polymer weight-average molecular weight (Mw) M g / mol, the polymer porosity P, and the polymer crosslinking density X are different, as shown in Table 6. All other parameters are the same as in Example 18. The amount of initiator (azobisisobutyronitrile, AIBN) in the electrolyte was adjusted to achieve the M values ​​shown in Table 6 for each example. The mass ratio of acrylate monomer A to nitrile monomer B was kept constant, and the ratio of the total mass of acrylate monomer A and nitrile monomer B to the mass of the electrolyte matrix was adjusted to achieve the P values ​​shown in Table 6 for each example. The mass ratio of bis(trimethylolpropane)acrylate (DTPTA) to ethoxylated trimethylolpropane triacrylate (ETPTA) in acrylate monomer A was adjusted to achieve the X values ​​shown in Table 6 for each example.

[0145] Table 1. Condition parameters and performance test results for Examples 1-5 and Comparative Examples 1-4 As shown in Table 1, the electrolyte system of this application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0146] Table 2. Condition parameters and performance test results for Examples 1, 6-9 and Comparative Examples 5-6. As shown in Table 2, the electrolyte system of this application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0147] Table 3. Condition parameters and performance test results for Examples 1, 10-13 and Comparative Examples 7-8 As shown in Table 3, the electrolyte system of this application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0148] Table 4. Condition parameters and performance test results for Examples 1, 14-16 and Comparative Example 9. As shown in Table 4, the electrolyte system of this application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0149] Table 5. Condition parameters and performance test results for Examples 1 and 17 As shown in Table 5, the electrolyte system of this application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0150] Table 6. Condition parameters and performance test results for Examples 18-22 As shown in Table 6, the electrolyte system of this application can simultaneously improve the ionic conductivity of the electrolyte and the cycle stability of the electrochemical device.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. An electrolyte, characterized in that, The electrolyte matrix includes lithium salts, diluents, additives, and solvents. The lithium salts include sulfonylimide lithium salts and lithium borate compounds based on oxalate ligands; The diluent includes fluorinated ether compounds; The additives include nitrogen-containing compounds; The solvents include non-fluorinated ether compounds and fluorinated ketone compounds; Based on the mass of the electrolyte matrix, the mass percentage of the lithium salt is a, the mass percentage of the diluent is b, the mass percentage of the additive is c, and the mass percentage of the solvent is d. 0.015 ≤ (a × b) / (d × β) ≤ 0.095, β = 1 + 0.07 × c 0.5 .

2. The electrolyte as described in claim 1, characterized in that, At least one of the following conditions (1)-(5) must be met: (1) 0.030 ≤ (a×b) / (d×β) ≤ 0.068; (2)0.150≤a≤0.250； (3)0.100≤b≤0.200； (4)0.005≤c≤0.020； (5)0.530≤d≤0.745。 3. The electrolyte as described in claim 1, characterized in that, At least one of the following conditions (1)-(3) must be satisfied: (1) The mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound is (0.5-6):1; (2) The mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound is (1-7):1; (3) The nitrogen-containing compound includes at least one of quaternary ammonium salts, nitrate esters, nitrates, and nitrogen-containing organic compounds.

4. The electrolyte as described in claim 3, characterized in that, At least one of the following conditions (1)-(6) must be satisfied: (1) The mass ratio of the sulfonylimide lithium salt to the oxalate-based lithium borate compound is (2-4):1; (2) The mass ratio of the non-fluorinated ether compound to the fluorinated ketone compound is (3-5):1; (3) The quaternary ammonium salt compound includes at least one of hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, and tetrabutylammonium chloride; (4) The nitrate ester compounds include at least one of methyl nitrate, ethyl nitrate, propyl nitrate, isopropyl nitrate, butyl nitrate, amyl nitrate, isosorbide dinitrate, nitroglycerin, pentaerythritol tetranitrate, and nitrocellulose; (5) The nitrate compounds include at least one of lithium nitrate, potassium nitrate, and sodium nitrate. (6) The nitrogen-containing organic compound includes at least one of pyridine, imidazole, 1-(trimethylsilyl)benzotriazole, triethanolamine, ethylenediamine, and hexamethylenetetramine.

5. The electrolyte as described in claim 1, characterized in that, At least one of the following conditions (1)-(5) must be met: (1) The sulfonylimide lithium salt includes at least one of lithium bis(fluorosulfonylimide) and lithium bis(trifluoromethanesulfonylimide); (2) The lithium borate compounds based on oxalate ligands include at least one of lithium difluorooxalate borate and lithium dioxalate borate; (3) The fluorinated ether compounds include at least one of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, 1,1,2,2,3,3,4,4-octafluoro-5-methoxypentane, and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; (4) The fluorine-free ether compounds include at least one of ethylene glycol dimethyl ether, 1,2-dimethoxypropane, and diethylene glycol dimethyl ether; (5) The fluorinated ketone compounds include perfluorohexanone.

6. The electrolyte as described in claim 1, characterized in that, The electrolyte further includes a polymer comprising structural units derived from acrylate monomer A and structural units derived from nitrile monomer B. Acrylate monomer A includes at least one of bis(trimethylolpropane)acrylate and monomers having the structure shown in Formula I. Nitrile monomer B includes at least one of acrylonitrile, methacrylonitrile, monomers having the structure shown in Formula II, trans-butenedionitrile, and monomers having the structure shown in Formula III. R1 is selected from any one of CH2=CHCOOCH2-, CH2=C(CH3)COOCH2-, and CH2=CHCOOCH2CH2OCH2-. R2, R3, and R4 are each independently selected from H, unsubstituted C1-C20 alkyl groups, CH2=CHCOOCH2-, CH2=C(CH3)COOCH2-, and CH2=CHCOOCH2CH2OCH2-. R5, R6, and R7 are each independently selected from any one of unsubstituted C1-C20 alkyl, fluorinated C1-C20 alkyl, unsubstituted C6-C20 aryl, and fluorinated C6-C20 aryl.

7. The electrolyte as described in claim 6, characterized in that, The polymer has a weight-average molecular weight of M g / mol, a porosity of P, and a crosslinking density of X mol / cm³. 3 ,2.00≤P×[lg(M)-10X]≤5.

00.

8. The electrolyte as described in claim 7, characterized in that, At least one of the following conditions (1)-(4) must be satisfied: (1)3.20≤P×[lg(M)-10X]≤4.40; (2)0.92≤P≤0.98； (3)1.0×10 5 ≤M≤5.0×10 5 ； (4)0.05≤X≤0.25。 9. The electrolyte as described in claim 6, characterized in that, At least one of the following conditions (1)-(3) must be satisfied: (1) The monomer having the structure shown in Formula I includes at least one of ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and trimethylolpropane trimethacrylate; (2) The monomer having the structure shown in Formula II includes at least one of 4-pentenonitrile, 5-hexenonitrile, and 3-butenonitrile; (3) The monomer having the structure shown in Formula III includes trans-1,4-dicyano-2-butene.

10. The electrolyte as described in claim 1, characterized in that, The electrolyte also includes an initiator.

11. An electrochemical device, characterized in that, Includes the electrolyte as described in any one of claims 1-10.

12. An electronic device, characterized in that, Includes the electrochemical device as described in claim 11.

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