Secondary battery and manufacturing method therefor, gel electrolyte and electrical apparatus

Abstract

A secondary battery and a manufacturing method therefor, a gel electrolyte, and an electrical apparatus. The secondary battery comprises an outer package, and an electrode assembly and a gel electrolyte accommodated in the outer package; the gel electrolyte comprises a polymer, a solvent and an electrolyte salt; the polymer comprises an acrylate group and a disulfide bond.

Description

Secondary battery and preparation method thereof, gel electrolyte and electric device TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a secondary battery and a preparation method thereof, a gel electrolyte and an electric device. BACKGROUND

[0002] With the popularity of secondary batteries in the fields of electric vehicles, electric aviation, energy storage power systems, electric tools, electric bicycles, electric motorcycles, military equipment, etc., the public has also put forward higher requirements for the performance of secondary battery products.

[0003] At present, most secondary batteries use liquid electrolytes, but liquid electrolytes are prone to side reactions with the negative electrode of the secondary battery, leading to a decrease in battery performance; and liquid electrolytes are prone to generating dendrites at the negative electrode during the cycling process, leading to short circuits in the battery and affecting the cycle life of the secondary battery. Liquid electrolytes are difficult to maintain the stable long cycle of the secondary battery. SUMMARY

[0004] In view of the above problems, the present application provides a secondary battery and a preparation method thereof, a gel electrolyte and an electric device to prolong the cycle life of the secondary battery.

[0005] In a first aspect, the present application provides a secondary battery, which comprises an outer package and an electrode assembly and a gel electrolyte contained in the outer package, the gel electrolyte comprising a polymer, a solvent and an electrolyte salt; the polymer comprises an acrylate group and a disulfide bond.

[0006] The above-mentioned secondary battery has a longer cycle life. The reason may be that the acrylate group in the copolymer of acrylate-based oligomer and diphenyl disulfide-based monomer can interact with anions, O, F in the solvent (such as forming hydrogen bonds, polyurethane bonds, polyurea bonds, etc.), anchoring the solvent, so that the solvent does not flow to the negative electrode to contact the negative electrode and cause side reactions; and when the gel electrolyte is damaged during the charge and discharge cycling of the secondary battery, the disulfide bond in the diphenyl disulfide-based monomer can repair it under the working conditions of the secondary battery.

[0007] In some embodiments, the polymer comprises a copolymer of acrylate-based oligomer and diphenyl disulfide-based monomer.

[0008] In some embodiments, the acrylate-based oligomer comprises one of a first functional group and a second functional group;

[0009] The diphenyl disulfide-based monomer comprises the other of the first functional group and the second functional group;

[0010] The first functional group comprises at least one of a hydroxyl group and an amino group;

[0011] The second functional group comprises an isocyanate group.

[0012] Thus, the first functional group and the second functional group can occur polymerization under mild conditions to obtain a copolymer.

[0013] In some embodiments, the solid content of the gel electrolyte is 2% to 15%.

[0014] The solid content of the gel electrolyte is set in the above range, which can further prolong the cycle life of the secondary battery. The reason can be that a lower solid content makes the gel electrolyte have better ionic conductivity, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0015] In some embodiments, the acrylate-based oligomer comprises a copolymer of a first acrylate-based monomer and a second acrylate-based monomer; the first acrylate-based monomer does not comprise a functional group; and the second acrylate-based monomer comprises one of a first functional group and a second functional group.

[0016] Thus, the cycle life of the secondary battery can be further prolonged. The reason can be that by pre-polymerizing the first acrylate-based monomer and the second acrylate-based monomer, the molecular weight of the acrylate-based oligomer can be increased, the solid content of the gel electrolyte can be reduced, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0017] In some embodiments, the first acrylate-based monomer comprises a compound represented by Formula I:

[0018] In Formula I, R1 is a C1-C10 alkyl group, a C1-C10 fluoroalkyl group, a C1-C10 alkoxy-substituted alkyl group, or a C1-C10 fluoroalkoxy-substituted fluoroalkyl group;

[0019] R2 is a hydrogen atom or a methyl group.

[0020] In some embodiments, the compound represented by Formula I comprises at least one of the following compounds:

[0021] The use of the above first acrylate-based monomer can further prolong the cycle life of the secondary battery.

[0022] In some embodiments, the second acrylate-based monomer comprises a compound represented by Formula II:

[0023] In Formula II, R3 is C1-C20 alkylene, C1-C20 fluoroalkylene, C1-C20 alkyleneoxy-substituted alkylene, C1-C20 fluoroalkyleneoxy-substituted fluoroalkylene;

[0024] R4 is a hydrogen atom or a methyl group;

[0025] R5 is one of a first functional group and a second functional group.

[0026] In some embodiments, the compound of Formula II includes at least one of the following compounds:

[0027] The use of the above-mentioned second acrylate monomer can further prolong the cycle life of the secondary battery.

[0028] In some embodiments, the diphenyl disulfide monomer includes a compound of Formula III:

[0029] wherein R6, R7, R8, R9, R 10 , R 11 each independently is a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyl-oxy group, a substituted or unsubstituted C1-C20 fluoroalkyl group; and at least one of R6, R7, R8 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyl-oxy group containing a substituent, or a C1-C20 fluoroalkyl group containing a substituent; at least one of R9, R 10 , R 11 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyl-oxy group containing a substituent, or a C1-C20 fluoroalkyl group containing a substituent, the substituent being the other of the first functional group and the second functional group.

[0030] In some embodiments, the compound of Formula III includes at least one of the following compounds:

[0031] The use of the above-mentioned diphenyl disulfide monomer can further prolong the cycle life of the secondary battery. The reason can be that the benzene ring of the above-mentioned diphenyl disulfide monomer can provide a steric hindrance effect, better guaranteeing the exertion of the disulfide bond repair function.

[0032] In some embodiments, the electrolyte salt includes one or more of lithium bisfluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bistrifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium bisoxalate borate, lithium difluorooxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0033] The electrolyte salt has good compatibility with the copolymer of the acrylate oligomer and the diphenyl disulfide monomer, and is almost suitable for all lithium secondary batteries, and has a wide application range.

[0034] In some embodiments, the secondary battery is a lithium ion battery, the solvent includes an ester solvent, and the ester solvent includes one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoro-vinyl carbonate, difluoro-vinyl carbonate, fluoro-methyl ethyl carbonate, fluoro-diethyl carbonate, fluoro-ethyl formate, fluoro-ethyl acetate, and fluoro-methyl acetate.

[0035] In some embodiments, the secondary battery is a lithium ion battery, and the gel electrolyte further includes an additive, and the additive includes one or more of ethylene carbonate, propane sultone, ethylene sulfate, ethylene sulfite, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilyl) borate, dimethyl maleic anhydride, and 1,4-diisocyanate butyl.

[0036] The ester solvent in the above range and the additive have good compatibility with the copolymer of the acrylate oligomer and the diphenyl disulfide monomer, and can be better suitable for the lithium ion battery, and on the premise of almost not affecting other performances, a lithium ion battery with a longer cycle life is obtained.

[0037] In some embodiments, the content of the electrolyte salt in the gel electrolyte is 8% to 15%; and / or the content of the ester solvent in the gel electrolyte is 80% to 90%; and / or the content of the additive in the gel electrolyte is 0.2% to 5%.

[0038] The electrolyte salt, the ester solvent, and the additive are arranged in the above range, and the lithium ion battery can have a longer cycle life.

[0039] In some embodiments, the secondary battery is a lithium metal battery, the solvent includes an ether solvent, and the ether solvent includes one or more of diethyl ether, dipropyl ether, ethyl propyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol methyl ethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyl tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0040] In some embodiments, the secondary battery is a lithium metal battery, and the gel electrolyte further comprises a diluent, the diluent comprising one or more of benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, bis(1,1,2,2-tetrafluoroethyl) ether.

[0041] The ether solvent, the diluent, the copolymer of the acrylate oligomer and the diphenyl disulfide monomer have good compatibility, can be well applied to the lithium metal battery, and the lithium metal battery with long cycle life is obtained without affecting other performances.

[0042] In some embodiments, the content of the electrolyte salt in the gel electrolyte is 12% to 20%; and / or the content of the ether solvent in the gel electrolyte is 8% to 15%; and / or the content of the diluent in the gel electrolyte is 60% to 75%.

[0043] The electrolyte salt, the ether solvent and the diluent are arranged in the above range, so that the lithium metal battery has a longer cycle life.

[0044] In a second aspect, the application provides a method for preparing the secondary battery of the first aspect, comprising:

[0045] The raw material for forming a polymer, a solvent and an electrolyte salt are mixed to obtain a precursor solution, the raw material for forming a polymer having an acrylate group and a disulfide bond;

[0046] The electrode assembly is placed in an outer package to obtain a dry battery;

[0047] The precursor solution is injected into the dry battery, the outer package is sealed, and the precursor solution is cured in situ to obtain the secondary battery.

[0048] The above method of the application has simple and reliable preparation process, good repeatability, and wide industrial application prospect, and the prepared secondary battery has long cycle life.

[0049] In some embodiments, the raw material for forming the polymer comprises an acrylate oligomer and a diphenyl disulfide monomer.

[0050] In some embodiments, the step of preparing the acrylate oligomer comprises:

[0051] The first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent are mixed to obtain an oligomer precursor solution;

[0052] The oligomer precursor solution is stirred at 50-70°C for 8-12 hours to obtain the acrylate oligomer.

[0053] The above reaction conditions are easy to realize and control, and the reaction is relatively complete.

[0054] In some embodiments, the mass ratio of the first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent is 18-54:2-10:0.1-2:40-80.

[0055] The mass ratio of the first acrylate monomer and the second acrylate monomer in the above range can further prolong the cycle life of the secondary battery. The reason can be that the mass ratio of the first acrylate monomer and the second acrylate monomer can adjust the molecular weight of the acrylate oligomer and the number of functional groups in the acrylate oligomer, and then adjust the crosslinking sites and positions in the copolymer of the acrylate oligomer and the diphenyl disulfide monomer, so as to adjust the pore size and pore volume of the copolymer, so as to reduce the solid content of the gel electrolyte, alleviate the deterioration of the ionic conductivity of the gel electrolyte and the influence on its kinetic performance, thereby prolonging the cycle life of the secondary battery.

[0056] In some embodiments, the initiator comprises at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, acetyl peroxide, and hydrogen peroxide.

[0057] In some embodiments, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoroethylene carbonate, difluoroethylene carbonate, fluoro methyl ethyl carbonate, fluoro diethyl carbonate, fluoro ethyl formate, fluoro ethyl acetate, fluoro methyl acetate, diethyl ether, dipropyl ether, ethyl propyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butylene glycol dimethyl ether, butylene glycol methyl ethyl ether, butylene glycol diethyl ether, benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluoromethyl benzene, trifluoromethoxy benzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, bis(1,1,2,2-tetrafluoroethyl) ether.

[0058] The above initiator and organic solvent facilitate the reaction, making it easy to prepare and obtain an oligomer with suitable performance.

[0059] In some embodiments, the in-situ curing temperature is 40-80°C.

[0060] The above in-situ curing temperature facilitates the sufficient progress of the addition reaction and has a high reaction efficiency.

[0061] In some embodiments, the mass ratio of the acrylate-based oligomer to the diphenyl disulfide-based monomer is 5-30:0.5-5.

[0062] The above mass ratio can further prolong the cycle life of the secondary battery. The reason can be that the above mass ratio facilitates the obtaining of a copolymer with a suitable three-dimensional network structure, which facilitates the reduction of the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0063] In some embodiments, the sum of the mass percentage of the acrylate-based oligomer and the diphenyl disulfide-based monomer is 5.5% to 35% based on the total mass of the precursor solution.

[0064] The use of the acrylate-based oligomer and the diphenyl disulfide-based monomer in the above content range can further prolong the cycle life of the secondary battery. The reason can be that the sum of the mass percentage of the acrylate-based oligomer and the diphenyl disulfide-based monomer is beneficial to alleviate the deterioration of the ionic conductivity of the gel electrolyte, thereby making the secondary battery have a longer cycle life.

[0065] In some embodiments, the secondary battery is a lithium ion battery, and at least one of the following conditions is met:

[0066] In the mixture of the solvent and the electrolyte salt, the concentration of the electrolyte salt is 1M to 3M;

[0067] The precursor solution further includes an additive, and the ratio of the mass of the additive to the sum of the mass of the solvent and the mass of the electrolyte salt is 0.5 to 5:100.

[0068] Setting the concentration of the electrolyte salt and / or the mass content of the additive in the lithium ion battery in the above range is beneficial to the performance of the lithium ion battery and can further improve the cycle life of the lithium ion battery.

[0069] In some embodiments, the secondary battery is a lithium metal battery, and the precursor solution further includes a diluent, and the mass ratio of the electrolyte salt, the solvent, and the diluent is 10 to 30:5 to 20:50 to 85.

[0070] Setting the mass ratio of the electrolyte salt, the solvent, and the diluent in the lithium metal battery in the above range is beneficial to the performance of the lithium metal battery and can further improve the cycle life of the lithium metal battery.

[0071] In a third aspect, the present application provides a gel electrolyte, including a polymer, a solvent, and an electrolyte salt; the polymer includes an acrylate group and a disulfide bond.

[0072] According to embodiments of the present application, the polymer includes a copolymer of an acrylate-based oligomer and a diphenyl disulfide-based monomer.

[0073] The secondary battery using the above gel electrolyte has a long cycle life. The reason can be that the acrylate groups in the copolymer of the acrylate oligomer and the diphenyl disulfide monomer can interact with the anions, O, F in the solvent (such as forming hydrogen bonds, polyurethane bonds, polyurea bonds, etc.), anchoring the solvent, so that the solvent does not flow to the negative electrode to contact the negative electrode and cause side reactions; and when the gel electrolyte is damaged during the charge and discharge cycle of the secondary battery, the disulfide bond in the diphenyl disulfide monomer can repair it under the working conditions of the secondary battery.

[0074] In some embodiments, the acrylate oligomer comprises one of the first functional group and the second functional group;

[0075] The diphenyl disulfide monomer comprises the other of the first functional group and the second functional group;

[0076] The first functional group comprises at least one of a hydroxyl group and an amino group;

[0077] The second functional group comprises an isocyanate group.

[0078] Thus, the first functional group and the second functional group can undergo a polymerization reaction under mild conditions to obtain a copolymer.

[0079] In some embodiments, the solid content of the gel electrolyte is 2% to 15%.

[0080] The solid content of the gel electrolyte is set in the above range, which can further prolong the cycle life of the secondary battery. The reason can be that a lower solid content makes the gel electrolyte have better ionic conductivity, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0081] In some embodiments, the acrylate oligomer comprises a copolymer of a first acrylate monomer and a second acrylate monomer; the first acrylate monomer does not comprise a functional group; and the second acrylate monomer comprises one of a first functional group and a second functional group.

[0082] Thus, the cycle life of the secondary battery can be further prolonged. The reason can be that by pre-polymerizing the first acrylate monomer and the second acrylate monomer, the molecular weight of the acrylate oligomer can be increased, the solid content of the gel electrolyte can be reduced, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0083] In some embodiments, the first acrylate monomer comprises a compound represented by Formula I:

[0084] R1is a C1-C10 alkyl group, a C1-C10 fluoroalkyl group, a C1-C10 alkoxy-substituted alkyl group, or a C1-C10 fluoroalkoxy-substituted fluoroalkyl group;

[0085] R2is a hydrogen atom or a methyl group.

[0086] In some embodiments, the compound of Formula I includes at least one of the following compounds:

[0087] The use of the above-described first acrylate monomer can further extend the cycle life of the secondary battery.

[0088] In some embodiments, the second acrylate monomer includes a compound of Formula II:

[0089] R3is a C1-C20 alkylene group, a C1-C20 fluoroalkylene group, a C1-C20 alkylenyloxy-substituted alkylene group, or a C1-C20 fluoroalkylenyloxy-substituted fluoroalkylene group.

[0090] R4is a hydrogen atom or a methyl group.

[0091] R5is one of a first functional group and a second functional group.

[0092] In some embodiments, the compound of Formula II includes at least one of the following compounds:

[0093] The use of the above-described second acrylate monomer can further extend the cycle life of the secondary battery.

[0094] In some embodiments, the diphenyl disulfide monomer includes a compound of Formula III:

[0095] wherein R6, R7, R8, R9, R 10 , R 11 each independently is a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyloxy group, or a substituted or unsubstituted C1-C20 fluoroalkyl group; and at least one of R6, R7, R8is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyloxy group containing a substituent, or a C1-C20 fluoroalkyl group containing a substituent; at least one of R9, R 10 , R 11 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyloxy group containing a substituent, or a C1-C20 fluoroalkyl group containing a substituent, the substituent being the other of the first functional group and the second functional group.

[0096] In some embodiments, the compound of Formula III includes at least one of the following compounds:

[0097] The above-mentioned diphenyl disulfide monomer can further prolong the cycle life of the secondary battery. The reason can be that the benzene ring of the above-mentioned diphenyl disulfide monomer can provide a steric hindrance effect, which better guarantees the function of disulfide bond repair.

[0098] In a fourth aspect, the present application provides a power device, which includes the secondary battery of the first aspect or the secondary battery prepared by the method of the second aspect.

[0099] The power device of the present application includes the secondary battery provided by the present application, and thus at least has the same advantages as the secondary battery, which will not be described in detail here.

[0100] In a fifth aspect, the present application provides a secondary battery, which includes an outer package and an electrode assembly and a gel electrolyte contained in the outer package, wherein: the gel electrolyte includes a polymer, a solvent and an electrolyte salt; the polymer includes a copolymer of an acrylate oligomer and a diphenyl disulfide monomer.

[0101] In a sixth aspect, the present application provides a gel electrolyte, which includes a polymer, a solvent and an electrolyte salt; the polymer includes a copolymer of an acrylate oligomer and a diphenyl disulfide monomer.

[0102] The above description is only a summary of the technical solutions of the present application. In order to enable the technical means of the present application to be more clearly understood, and to be implemented according to the content of the description, and in order to enable the above and other purposes, characteristics and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0103] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not meant to limit the present application. Moreover, the same reference numerals in the attached drawings indicate the same or similar components. In the drawings:

[0104] FIG. 1 is a structural schematic diagram of a battery cell according to an embodiment of the present application.

[0105] FIG. 2 is an exploded structural schematic diagram of a battery cell according to an embodiment of the present application.

[0106] FIG. 3 is a structural schematic diagram of a battery module according to an embodiment of the present application.

[0107] FIG. 4 is a structural schematic diagram of a battery pack according to an embodiment of the present application.

[0108] FIG. 5 is an exploded structural schematic view of the battery pack shown in FIG. 4.

[0109] FIG. 6 is a structural schematic view of an electric device according to an embodiment of the present application.

[0110] In the drawings, the drawings are not necessarily drawn to scale. Reference signs are explained as follows: 1 battery pack, 2 upper case, 3 lower case, 4 battery module, 5 battery cell, 51 case, 52 electrode assembly, 53 cover plate. DETAILED DESCRIPTION

[0111] Hereinafter, a secondary battery and a method of manufacturing the same, a gel electrolyte, and an electric device according to the present application are explained in detail with appropriate reference to the accompanying drawings. However, there can be cases where unnecessary detailed explanations are omitted. For example, there can be cases where detailed explanations of matters well known in the art, repeated explanations of actually identical structures are omitted. This is to avoid the following explanation from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following explanations are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0112] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if a minimum range value of 1 and 2 is listed, and if a maximum range value of 3, 4, and 5 is listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise stated, a numerical range "a-b" represents a shorthand manner of describing each and every numerical value that is contained in the range between "a" and "b," wherein "a" and "b" are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed herein, and "0-5" is merely a shorthand manner of describing these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0113] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0114] If not otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions shall be considered to be included in the disclosure of the present application.

[0115] If not otherwise specified, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method further comprises step (c), which means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0116] If not otherwise specified, the terms “comprise” and “contain” mentioned in the present application are open-ended, and can also be closed-ended. For example, the terms “comprise” and “contain” can mean that other components not listed can also be included, or can mean that only the listed components are included.

[0117] If not otherwise specified, in the present application, the term “or” is inclusive. For example, the phrase “A or B” means “A, B, or both A and B.” More specifically, any of the following satisfy the condition “A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0118] If not otherwise specified, in the present application, the terms “first”, “second”, “third”, “fourth”, “fifth” and the like are used to distinguish different objects, and are not used to describe a specific order or primary and secondary relationship.

[0119] In the present application, the terms “plurality” and “plural” mean two or more.

[0120] Throughout the present specification, substituents of compounds are disclosed in groups or ranges. Each individual subcombination of members of these groups and ranges is explicitly contemplated. For example, the term “C1-C6alkyl” is explicitly disclosed to individually disclose C1, C2, C3, C4, C5, C6, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C6, C2-C5, C2-C4, C2-C3, C3-C6, C3-C5, C3-C4, C4-C6, C4-C5, and C5-C6alkyl.

[0121] The terms used in the present application have the generally understood meanings known to those skilled in the art, unless otherwise specified.

[0122] The values of the parameters mentioned in the present application can be measured by various test methods commonly used in the art, unless otherwise specified, for example, according to the test methods given in the examples of the present application. The test temperature of each parameter is 25℃, unless otherwise specified.

[0123] The ratio parameters involved in the present application are compared under the same unit, unless otherwise specified. For example, the ratio of the volume distribution particle size of A and B is 1:1, at this time the units of the volume distribution particle size of A and B are the same.

[0124] In the present application, the ionic conductivity is mainly used to characterize the ability of the gel electrolyte composition to transport ions, which can reflect the ability of the gel electrolyte composition to transport ions, which can be tested by any known method.

[0125] At present, most of the secondary batteries use liquid electrolyte. On the one hand, the unstable solvent in the liquid electrolyte and the anion in the electrolyte salt are easy to contact with the negative electrode interface of the secondary battery and cause side reactions of active lithium consumption, resulting in the decrease of the coulomb efficiency and the cycle life of the secondary battery; on the other hand, the liquid electrolyte is easy to generate dendrites at the negative electrode during the cycle process, resulting in short circuit of the secondary battery, and even explosion in serious cases. In order to solve the problems of the liquid electrolyte in the traditional technology, the related technology has developed solid electrolyte and quasi-solid electrolyte (such as gel electrolyte, etc.). Among them, the gel polymer electrolyte has attracted much attention of researchers.

[0126] It is found that the gel electrolyte uses high content of polymer to maintain its liquid retention capacity, but the high content of polymer deteriorates the ionic conductivity of the gel electrolyte, and the gel electrolyte is easy to be damaged by swelling and extrusion during the charge and discharge cycle, thereby reducing the cycle life of the secondary battery.

[0127] In order to prolong the cycle life of the secondary battery, the present application proposes to use a gel electrolyte including a copolymer of an acrylate-based oligomer and a diphenyl disulfide-based monomer, a solvent and an electrolyte salt in the secondary battery, which can prolong the cycle life of the secondary battery. The reason can be that the acrylate groups in the copolymer of the acrylate-based oligomer and the diphenyl disulfide-based monomer can interact with the anions, O and F in the solvent (such as forming hydrogen bonds, polyurethane bonds, polyurea bonds, etc.), anchoring the solvent, so that the solvent does not flow to the negative electrode to contact the negative electrode and cause side reactions; and when the gel electrolyte is damaged during the charge and discharge cycle of the secondary battery, the copolymer in the gel electrolyte has a three-dimensional spatial network structure, which can realize the binding of the liquid phase solvent (liquid binding), so that it cannot flow freely, reduces the side reactions of the unstable solvent in the electrolyte and the anions in the electrolyte salt contacting the negative electrode interface of the secondary battery to consume active lithium, improves the coulomb efficiency of the secondary battery, and prolongs the cycle life of the secondary battery.

[0128] And the disulfide bond in the diphenyl disulfide-based monomer can repair it under the working conditions of the secondary battery.

[0129] The secondary battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the secondary battery mentioned in the present application can include battery cells, battery modules or battery packs, etc.

[0130] The battery cell is the smallest unit that makes up the battery, which can realize the function of charging and discharging by itself. The battery cell can be in the shape of a cylinder, a flat body, a cuboid or other shapes, etc., which is not limited in the embodiments of the present application. For example, FIG. 1 is a battery cell 5 in the shape of a cuboid as an example.

[0131] When there are multiple battery cells, the multiple battery cells are connected in series, parallel or mixed connection through the busbar. In some embodiments, the secondary battery can be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. In some embodiments, the secondary battery can be a battery pack, which includes a box body and battery cells, and the battery cells or battery modules are contained in the box body. In some embodiments, the box body can be part of the chassis structure of the vehicle. For example, part of the box body can be at least part of the floor of the vehicle, or part of the box body can be at least part of the cross beam and longitudinal beam of the vehicle.

[0132] In some embodiments, the secondary battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0133] The battery cell mentioned in the embodiments of the present application includes a lithium ion secondary battery cell, a lithium metal secondary battery cell, etc., which is not limited in the embodiments of the present application.

[0134] The battery cell generally includes an electrode assembly. The electrode assembly generally includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet, and the electrode assembly can be in a jelly-roll structure or a stack structure, and the embodiments of the present application are not limited thereto.

[0135] The battery cell can further include an outer package for packaging the electrode assembly and the electrolyte. The outer package can be a hard case such as a hard plastic case, an aluminum case, a steel case, etc. The outer package can also be a soft pack such as a pouch type soft pack. The soft pack can be made of plastic such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0136] In some embodiments, as shown in FIG. 2, the outer package can include a case 51 and a cover plate 53. The case 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The electrode assembly 52 is packaged in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to requirements.

[0137] In some embodiments, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. FIG. 3 is a schematic view of a battery module 4 as an example. As shown in FIG. 3, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0138] Optionally, the battery module 4 can further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0139] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0140] FIGS. 4 and 5 are schematic views of a battery pack 1 as an example. As shown in FIGS. 4 and 5, the battery pack 1 can include a box body and a plurality of battery modules 4 arranged in the box body. The box body includes an upper box body 2 and a lower box body 3, and the upper box body 2 is used to cover the lower box body 3 and form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the box body in any manner.

[0141] [Secondary battery]

[0142] According to some embodiments of the present application, the present application provides a secondary battery, comprising: an outer package and an electrode assembly and a gel electrolyte contained in the outer package, wherein: the gel electrolyte comprises a polymer, a solvent and an electrolyte salt; the polymer comprises a copolymer of an acrylate-based oligomer and a diphenyl disulfide-based monomer.

[0143] It can be understood that the electrode assembly generally comprises a positive electrode sheet, a negative electrode sheet and a separator film arranged between the positive electrode sheet and the negative electrode sheet, and can be a stacked electrode assembly or a wound electrode assembly.

[0144] The gel electrolyte can be arranged on at least one of the negative electrode sheet, the positive electrode sheet and the separator film.

[0145] The secondary battery described above has a long cycle life. The reason can be that the acrylate groups in the copolymer of the acrylate-based oligomer and the diphenyl disulfide-based monomer can interact with the anions, O, F in the solvent (such as forming hydrogen bonds, polyurethane bonds, polyurea bonds, etc.), anchoring the solvent, so that the solvent does not flow to the negative electrode to contact the negative electrode and cause side reactions; and when the gel electrolyte is damaged during the charge and discharge cycle of the secondary battery, the disulfide bond in the diphenyl disulfide-based monomer can repair it under the working conditions of the secondary battery.

[0146] According to some embodiments of the present application, the acrylate-based oligomer comprises one of a first functional group and a second functional group; the diphenyl disulfide-based monomer comprises the other of the first functional group and the second functional group; the first functional group comprises at least one of a hydroxyl group and an amino group; the second functional group comprises an isocyanate group.

[0147] The first functional group and the second functional group can react to cause the acrylate-based oligomer and the diphenyl disulfide-based monomer to polymerize, that is, the hydroxyl group and / or the amino group can react with the isocyanate group, for example, the hydroxyl group reacts with the isocyanate group, or the amino group reacts with the isocyanate group, or the hydroxyl group and the amino group together react with the isocyanate group. In order to ensure the smooth progress of the polymerization reaction, either the acrylate-based oligomer or the diphenyl disulfide-based monomer cannot simultaneously comprise the first functional group and the second functional group. Herein, "the acrylate-based oligomer comprises one of a first functional group and a second functional group; the diphenyl disulfide-based monomer comprises the other of the first functional group and the second functional group" means that if the acrylate-based oligomer comprises the first functional group, then the diphenyl disulfide-based monomer comprises the second functional group; and if the acrylate-based oligomer comprises the second functional group, then the diphenyl disulfide-based monomer comprises the first functional group.

[0148] Thus, the first functional group and the second functional group can undergo a polymerization reaction under mild conditions to obtain a copolymer.

[0149] According to some embodiments of the present application, the solid content of the gel electrolyte is 2% to 15%.

[0150] The term "solid content" refers to the mass ratio of the polymer (copolymer of acrylate-based oligomer and diphenyl disulfide-based monomer) in the gel electrolyte.

[0151] For example, the solid content of the gel electrolyte can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or in any range of any of the above values.

[0152] The solid content of the gel electrolyte is set in the above range, which can further prolong the cycle life of the secondary battery. The reason can be that a lower solid content makes the gel electrolyte have better ionic conductivity, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0153] According to some embodiments of the present application, the acrylate-based oligomer comprises a copolymer of a first acrylate-based monomer and a second acrylate-based monomer;

[0154] The first acrylate-based monomer does not comprise a functional group;

[0155] The second acrylate-based monomer comprises one of a first functional group and a second functional group.

[0156] "The second acrylate-based monomer comprises one of a first functional group and a second functional group" means that the second acrylate-based monomer comprises a first functional group, or the second acrylate-based monomer comprises a second functional group, and the second acrylate-based monomer cannot simultaneously comprise a first functional group and a second functional group.

[0157] Thus, the cycle life of the secondary battery can be further prolonged. The reason can be that by pre-polymerizing the first acrylate-based monomer and the second acrylate-based monomer, the molecular weight of the acrylate-based oligomer can be increased, the solid content of the gel electrolyte can be reduced, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0158] According to some embodiments of the present application, the first acrylate-based monomer comprises a compound represented by Formula I:

[0159] In Formula I, R1 is C1-C10 alkyl, C1-C10 fluoroalkyl, C1-C10 alkoxy-substituted alkyl, or C1-C10 fluoroalkoxy-substituted fluoroalkyl; and R2 is a hydrogen atom or a methyl group.

[0160] According to some embodiments of the present application, the compound of Formula I includes at least one of the following compounds:

[0161] The use of the above-described first acrylate monomer can further extend the cycle life of the secondary battery.

[0162] According to some embodiments of the present application, the second acrylate monomer includes a compound of Formula II:

[0163] In Formula II, R3 is a C1-C20 alkylene group, a C1-C20 fluoroalkylene group, a C1-C20 alkyleneoxy-substituted alkylene group, or a C1-C20 fluoroalkyleneoxy-substituted fluoroalkylene group.

[0164] R4 is a hydrogen atom or a methyl group.

[0165] R5 is one of a first functional group and a second functional group.

[0166] "R5 is one of a first functional group and a second functional group" means that R5 is the first functional group, or R5 is the second functional group, and R5 cannot include both the first functional group and the second functional group.

[0167] According to some embodiments of the present application, the compound of Formula II includes at least one of the following compounds:

[0168] The use of the above-described second acrylate monomer can further extend the cycle life of the secondary battery.

[0169] According to some embodiments of the present application, the diphenyl disulfide monomer includes a compound of Formula III:

[0170] R6, R7, R8, R9, R 10 , R 11 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyl-oxy group, or a substituted or unsubstituted C1-C20 fluoroalkyl group; and at least one of R6, R7, R8 is a C1-C20 alkyl group, a C1-C20 alkyl-oxy group, or a C1-C20 fluoroalkyl group containing a substituent; and at least one of R9, R 10 , R 11 is a C1-C20 alkyl group, a C1-C20 alkyl-oxy group, or a C1-C20 fluoroalkyl group containing a substituent, the substituent being the other of the first functional group and the second functional group.

[0171] According to some embodiments of the present application, the compound shown in the formula III includes at least one of the following compounds:

[0172] The above-mentioned diphenyl disulfide monomer can further prolong the cycle life of the secondary battery. The reason may be that the benzene ring of the above-mentioned diphenyl disulfide monomer can provide a steric hindrance effect, which better guarantees the function of disulfide bond repair.

[0173] According to some embodiments of the present application, the electrolyte salt includes one or more of lithium bisfluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis-trifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium bisoxalate borate, lithium difluoro oxalate borate, lithium difluoro bisoxalate phosphate, and lithium tetrafluoro oxalate phosphate.

[0174] The above-mentioned electrolyte salt has good compatibility with the copolymer of the acrylate oligomer and the diphenyl disulfide monomer, and is almost suitable for all lithium secondary batteries, and has a wide application range.

[0175] It can be understood that in order to achieve better electrochemical performance, different types of lithium batteries have different requirements for electrolytes, and therefore different electrolytes need to be developed for different types of lithium batteries. For example, in lithium ion batteries, the use of an ester solvent system in the electrolyte is beneficial to the performance of the battery, while in lithium metal batteries, the use of an ether solvent system is more beneficial to the performance of the battery. In order to meet the above use requirements, the gel electrolyte in the embodiments of the present application considers the applicability of different solvent systems, and the copolymer used has good coordination and synergistic effect with ester solvents and ether solvents, and can be widely used in different types of lithium batteries.

[0176] According to some embodiments of the present application, the secondary battery is a lithium ion battery, the solvent includes an ester solvent, and the ester solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoroethylene carbonate, difluoroethylene carbonate, fluoro methyl ethyl carbonate, fluoro diethyl carbonate, fluoro ethyl formate, fluoro ethyl acetate, and fluoro methyl acetate.

[0177] According to some embodiments of the present application, the secondary battery is a lithium ion battery, and the gel electrolyte further includes an additive, and the additive includes one or more of ethylene carbonate, propane sulfone lactone, ethylene sulfate, ethylene sulfite, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite, tris (trifluoroethyl) phosphate, tris (trifluoroethyl) phosphite, tris (trimethylsilyl) borate, dimethyl maleic anhydride, and 1, 4-diisocyanate butyl.

[0178] Since the working voltage of secondary batteries is much higher than the decomposition voltage of water, the electrolyte of secondary batteries usually adopts organic solvents. Lithium-ion secondary batteries mainly rely on the movement of lithium ions (Li + ) between the positive electrode and the negative electrode to work. During the charging and discharging process, Li + is embedded and de-embedded between the two electrodes: when charging, Li + is de-embedded from the positive electrode, embedded into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; when discharging, the opposite is true. The electrolyte of lithium-ion secondary batteries usually includes lithium salt, organic solvent and additive. Lithium salt is used to ensure that there is sufficient lithium ion between the positive and negative electrodes during the charging and discharging cycle of lithium-ion battery, so as to realize reversible cycle; the organic solvent is used as the carrier of lithium ion, which is the main part of the electrolyte; the additive is used to improve the stability of the electrolyte and enhance the electrochemical performance of the electrolyte. The ester solvent has the advantages of high dielectric constant, strong solubility to lithium salt, low melting point, high boiling point, small viscosity, convenient transportation of lithium ion, good chemical stability, good safety and low cost, and can effectively improve the electrical performance of lithium-ion battery when used as the organic solvent of the electrolyte of lithium-ion battery.

[0179] The ester solvent in the above range has good compatibility with the copolymer of the acrylate oligomer and the diphenyl disulfide monomer, and can be well applied to lithium-ion batteries to obtain lithium-ion batteries with long cycle life without affecting other performances.

[0180] According to some embodiments of the present application, the content of the electrolyte salt in the gel electrolyte is 8% to 15%; and / or the content of the ester solvent in the gel electrolyte is 80% to 90%; and / or the content of the additive in the gel electrolyte is 0.2% to 5%.

[0181] The content of the electrolyte salt in the gel electrolyte is 8% to 15%. For example, the content of the electrolyte salt in the gel electrolyte can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or in any range of any of the above values.

[0182] The content of the ester solvent in the gel electrolyte is 80% to 90%. For example, the content of the ester solvent in the gel electrolyte can be 80%, 82%, 84%, 86%, 88%, 90%, or in any range of any of the above values.

[0183] The content of the additive in the gel electrolyte is 0.2% to 5%. For example, the content of the additive in the gel electrolyte can be 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or in any range of any of the above values.

[0184] The electrolyte salt, ester solvent and additive are arranged in the above range, which can further make the lithium ion battery have a longer cycle life.

[0185] According to some embodiments of the present application, the secondary battery is a lithium metal battery, the solvent includes an ether solvent, and the ether solvent includes one or more of diethyl ether, dipropyl ether, ethyl propyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol methyl ethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyl tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0186] According to some embodiments of the present application, the gel electrolyte further includes a diluent, and the diluent includes one or more of benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, and bis(1,1,2,2-tetrafluoroethyl) ether.

[0187] A lithium metal secondary battery is a secondary battery that uses lithium metal as a negative electrode material. When charged, Li + migrates to the interface between the lithium metal negative electrode and the electrolyte and is deposited; when discharged, the lithium metal loses electrons at the interface and becomes Li + and dissolves into the electrolyte. Thus, during charging and discharging, part of the lithium undergoes irreversible deposition / detachment, loses activity, and becomes "lithium dendrites". The use of an ether solvent can improve lithium dendrite growth and improve the coulombic efficiency and cycle performance of the lithium metal secondary battery.

[0188] The copolymer of the ether solvent, the diluent, and the acrylate oligomer and the diphenyl disulfide monomer has good compatibility, can be well applied to the lithium metal battery, and under the premise of almost not affecting other performances, a lithium metal battery with long cycle life is obtained.

[0189] According to some embodiments of the present application, the content of the electrolyte salt in the gel electrolyte is 12% to 20%; and / or the content of the ether solvent in the gel electrolyte is 8% to 15%; and / or the content of the diluent in the gel electrolyte is 60% to 75%.

[0190] The content of the electrolyte salt in the gel electrolyte is 12% to 20%. For example, the content of the electrolyte salt in the gel electrolyte can be 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or in any range of any of the above values.

[0191] The content of the ether solvent in the gel electrolyte is 8% to 15%. For example, the content of the ether solvent in the gel electrolyte can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or in any range of any of the above values.

[0192] The content of the diluent in the gel electrolyte is 60% to 75%. For example, the content of the diluent in the gel electrolyte can be 60%, 63%, 66%, 69%, 70%, 72%, 75%, or in any range of any of the above values.

[0193] By setting the electrolyte salt, the ether solvent, and the diluent in the above range, the lithium metal battery can have a longer cycle life.

[0194] It can be understood that the electrode assembly generally includes a positive electrode sheet, a negative electrode sheet, and a separator film disposed between the positive electrode sheet and the negative electrode sheet, and can be a stacked electrode assembly or a wound electrode assembly.

[0195] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material. The positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0196] The positive electrode active material includes, but is not limited to, a lithium transition metal oxide and / or an olivine structure lithium-containing phosphate.

[0197] In some embodiments, the positive active material includes a lithium transition metal oxide. Optionally, the lithium transition metal oxide includes lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., NCM333, NCM523, NCM211, NCM622, NCM811), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) or a combination thereof.

[0198] In some embodiments, the positive active material includes a lithium-containing phosphate with an olivine structure. Optionally, the lithium-containing phosphate with an olivine structure includes at least one of lithium iron phosphate (e.g., LiFePO4), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate (e.g., LiMn x Fe 1-x PO4, 0 < x < 1), a composite of lithium manganese iron phosphate and carbon.

[0199] The positive electrode film layer can further include a conductive agent. As an example, the positive electrode conductive agent can include one or more of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, without limitation to the present embodiments.

[0200] The positive electrode film layer can further include a binder to firmly bind the positive active material and the conductive agent to the positive current collector. The binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0201] The positive electrode film layer can further include a functional additive, which can include one or more of a dispersant, a plasticizer, a pore-forming agent, a water-removing additive, an acid-removing additive, and a lithium supplement.

[0202] The dispersant can include an abc-type block copolymer, the a block including polyvinylpyrrolidone, the b block including polyacrylic acid, and the c block including one or more of a polytetrahydrofuran chain, a polyethylene oxide chain, a polyethylene glycol chain, a polypropylene glycol chain, and a polypropylene oxide triol chain. Optionally, a ratio of an average polymerization degree of the a block to the b block is greater than 10:1. Optionally, a ratio of an average polymerization degree of the a block to the c block is (0.1-10):1. Optionally, the dispersant has a weight average molecular weight of 2,000 to 100,000.

[0203] The plasticizer can include one or more of strong solvent type (PP-SS) plasticizers, low temperature resistant type (PP-LT) plasticizers, low volatile type (PP-LV) plasticizers, low diffusion type (SP-LD) plasticizers, heat stable type (SP-Stab) plasticizers, and flame retardant type (SP-FR) plasticizers.

[0204] The strong solvent type (PP-SS) plasticizer can provide strong plasticizing performance, and for example, can include phthalates, non-phthalates (e.g., benzoates, trimethylphenyl phosphates, etc.).

[0205] The low temperature resistant type (PP-LT) plasticizer can also provide good low temperature resistance, and for example, can include aliphatic dibasic acid esters.

[0206] The low volatile type (PP-LV) plasticizer can also have low volatility, and for example, can include trimellitates and polyesters.

[0207] The low diffusion type (SP-LD) plasticizer can also have low diffusion, and for example, can include polyesters.

[0208] The heat stable type (SP-Stab) plasticizer can also have a heat stable function, and for example, can include epoxy compounds.

[0209] The flame retardant type (SP-FR) plasticizer can also have a flame retardant function, and for example, can include phosphates and halogenated hydrocarbons.

[0210] The lithium supplement can include one or more of lithium-rich oxides (e.g., Li2NiO2, Li5FeO4, etc.), nanocomposites, and binary lithium compounds, and optionally, the number of Li atoms in the molecular formula of the lithium supplement is ≥ 1.5.

[0211] The positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0212] The positive electrode tab does not exclude other additional functional layers in addition to the positive electrode film layer. For example, in some embodiments, the positive electrode tab can further include a functional coating, which can be located between the positive electrode current collector and the positive electrode film layer and / or on the surface of the positive electrode film layer away from the positive electrode current collector. As an example, the functional coating can include one or more of conductive carbon, water removal additives, acid removal additives, lithium supplementing agents, without limitation to the embodiments of the present application.

[0213] It can be understood that the above-mentioned positive electrode tab is suitable for both lithium ion batteries and lithium metal batteries.

[0214] The positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode tab can be obtained.

[0215] Depending on the type of secondary battery, the negative electrode tab can have different structures and negative electrode materials.

[0216] Taking a lithium ion battery as an example, the negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material. As an example, the negative electrode current collector has two opposite surfaces in the thickness direction of itself, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0217] The negative electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0218] The negative electrode active material can include one or more of carbon-based materials, silicon-based materials, tin-based materials and lithium titanate. The carbon-based material can include one or more of graphite (such as artificial graphite, natural graphite, etc.), soft carbon, hard carbon. The silicon-based material can include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites and silicon alloys. The tin-based material can include one or more of elemental tin, tin oxide compounds and tin alloys.

[0219] The negative electrode film layer can include a negative electrode binder. As an example, the negative electrode binder can include one or more of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS), without limitation to embodiments of the present application.

[0220] The negative electrode film layer can further include a negative electrode conductive agent. As an example, the negative electrode conductive agent can include one or more of super P, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, without limitation to embodiments of the present application.

[0221] The negative electrode film layer can further include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC)), etc.

[0222] The negative electrode tab does not exclude other additional functional layers other than the negative electrode film layer. In some embodiments, the negative electrode tab can further include a functional coating, which can be located between the negative electrode current collector and the negative electrode film layer and / or on the surface of the negative electrode film layer facing away from the negative electrode current collector. Optionally, the functional coating can include carbon.

[0223] The negative electrode film layer can further include a lithium supplementing material. Optionally, the lithium supplementing material includes one or more of lithium foil, lithium ribbon, lithium powder, prelithiation reagent. Optionally, the prelithiation reagent can include one or more of Li-arene, complex of Li-arene and ether solvent, optionally including one or more of naphthalene lithium, diphenyl lithium-dimethyl ether (DME).

[0224] The negative electrode tab can include a negative electrode current collector and first and second negative electrode film layers respectively disposed on both surfaces of the negative electrode current collector. The first and second negative electrode film layers can have the same or different compositions; the first and second negative electrode film layers can have the same or different thicknesses.

[0225] The negative electrode tab can be prepared by dispersing the above-mentioned components for preparing the negative electrode tab, such as the negative electrode active material, the negative electrode conductive agent, the negative electrode binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on the negative electrode current collector, and after drying, cold pressing, etc., the negative electrode tab can be obtained.

[0226] In some embodiments, the negative electrode tab can further not include a negative active material capable of deintercalating lithium ions. For example, the negative electrode tab can include a lithium sheet or a lithium alloy sheet, the lithium alloy sheet being an alloy of lithium and other various metal or non-metal elements, the metal elements including one or more of tin (Sn), zinc (Zn), aluminum (Al), magnesium (Mg), silver (Ag), gold (Au), gallium (Ga), indium (In), or foil (Pt); or, the negative electrode tab can include a reticular or foamed three-dimensional skeleton layer; or, the negative electrode tab can include a negative current collector and a lithium-containing layer disposed on at least one surface of the negative current collector.

[0227] Taking a lithium metal battery as an example, the negative electrode is lithium metal, and in some embodiments, a lithium metal foil can be placed on a negative current collector (such as a copper foil) to form a negative electrode tab.

[0228] The secondary battery further includes a separator. The type of the separator is not particularly limited in the present application, and any known porous separator having good chemical stability and mechanical stability can be selected.

[0229] In some embodiments, the separator includes a porous substrate. The material of the porous substrate can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyester, and polyimide. The porous substrate can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the porous substrate is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0230] In some embodiments, the separator can further include a coating layer on at least one surface of the porous substrate. Optionally, the coating layer includes one or more of inorganic heat-resistant particles and organic heat-resistant particles.

[0231] [Method for preparing a secondary battery]

[0232] According to some embodiments of the present application, the present application provides a method for preparing the above-mentioned secondary battery, comprising: mixing an acrylate oligomer, a diphenyl disulfide monomer, a solvent, and an electrolyte salt to obtain a precursor solution; placing an electrode assembly in an outer package to obtain a dry battery cell; injecting the precursor solution into the dry battery cell, sealing the outer package, and allowing the precursor solution to solidify in situ to obtain the secondary battery.

[0233] When preparing the precursor solution, the order of mixing the acrylate oligomer, the diphenyl disulfide monomer, the solvent, and the electrolyte salt is not limited. Specifically, the solvent and the electrolyte salt can be mixed to form a solution, and then the solution can be mixed with the acrylate oligomer and the diphenyl disulfide monomer to form the precursor solution.

[0234] In the preparation of the secondary battery, the mixing of the acrylate oligomer, the diphenyl disulfide monomer, the solvent and the electrolyte salt to obtain the precursor solution and the placement of the electrode assembly in the outer package to obtain the dry battery cell are not in a specific order.

[0235] It can be understood that the electrode assembly generally comprises a positive electrode sheet, a negative electrode sheet and a separator film arranged between the positive electrode sheet and the negative electrode sheet, and can be prepared by a stacking process or a winding process. The present application does not have specific limitations, and the specific operations can also be carried out according to conventional techniques. Here, it will not be described one by one.

[0236] The above method of the present application has simple and reliable preparation process, good repeatability, and wide industrial application prospect. The prepared secondary battery has a long cycle life.

[0237] According to some embodiments of the present application, the step of preparing the acrylate oligomer comprises:

[0238] The first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent are mixed to obtain an oligomer precursor solution.

[0239] The oligomer precursor solution is stirred at 50-70°C for 8-12 hours to obtain the acrylate oligomer.

[0240] The reaction temperature of the oligomer precursor solution is 50-70°C, for example, the reaction temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, or in any range of any of the above values.

[0241] The stirring time (reaction time) of the oligomer precursor solution is 8-12 hours, for example, the stirring time can be 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or in any range of any of the above values.

[0242] The above reaction conditions are easy to realize and control, and the reaction is relatively complete.

[0243] According to some embodiments of the present application, the mass ratio of the first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent is 18-54:2-10:0.1-2:40-80.

[0244] For example, the mass ratio of the first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent can be 44.5:5:0.5:50, 34.5:10:0.5:50, 18:2:1:79, 54:5.9:0.1:40, 38:10:2:50, or in any range of any of the above values.

[0245] By setting the mass ratio of the first acrylate monomer and the second acrylate monomer in the above range, the cycle life of the secondary battery can be further prolonged. The reason can be that the mass ratio of the first acrylate monomer and the second acrylate monomer can adjust the molecular weight of the acrylate oligomer and the number of functional groups in the acrylate oligomer, and then adjust the crosslinking sites and positions in the copolymer of the acrylate oligomer and the diphenyl disulfide monomer, thereby adjusting the pore size and pore volume of the copolymer, to reduce the solid content of the gel electrolyte, alleviate the deterioration of the ionic conductivity of the gel electrolyte and its impact on the kinetic performance, thereby prolonging the cycle life of the secondary battery.

[0246] According to some embodiments of the present application, the initiator includes at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, acetyl peroxide, and hydrogen peroxide.

[0247] According to some embodiments of the present application, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoroethylene carbonate, difluoroethylene carbonate, fluoromethyl ethyl carbonate, fluorodiethyl carbonate, fluorinated ethyl formate, fluorinated ethyl acetate, fluorinated methyl acetate, diethyl ether, dipropyl ether, ethyl propyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butylene glycol dimethyl ether, butylene glycol methyl ethyl ether, butylene glycol diethyl ether, benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, bis(1,1,2,2-tetrafluoroethyl) ether.

[0248] The initiator and the organic solvent are conducive to the reaction, and the oligomer is easy to prepare and has suitable performance.

[0249] According to some embodiments of the present application, the in-situ curing temperature is 40-80℃.

[0250] For example, the in-situ curing temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, or in any range of any of the above values.

[0251] The in-situ curing temperature is conducive to the full addition reaction and has high reaction efficiency.

[0252] According to some embodiments of the present application, the mass ratio of the acrylate-based oligomer to the diphenyl disulfide-based monomer is 5-30:0.5-5; for example, the mass ratio of the acrylate-based oligomer to the diphenyl disulfide-based monomer can be 11:2, 5:0.5, 5:5, 10:0.5, 10:5, 30:0.5, 30:5, 10:2, or in any range of any of the above values.

[0253] The above mass ratio can further prolong the cycle life of the secondary battery. The reason can be that the above mass ratio is conducive to obtaining a copolymer with a suitable three-dimensional network structure, reducing the solid content of the gel electrolyte, and thus improving the cycle life of the secondary battery.

[0254] According to some embodiments of the present application, the sum of the mass percentage contents of the acrylate-based oligomer and the diphenyl disulfide-based monomer is 5.5%-35% based on the total mass of the precursor solution; for example, the sum of the mass percentage contents of the acrylate-based oligomer and the diphenyl disulfide-based monomer can be 5.5%, 10%, 13%, 15%, 20%, 25%, 30%, 35%, or in any range of any of the above values.

[0255] The use of the acrylate-based oligomer and the diphenyl disulfide-based monomer in the above content range can further prolong the cycle life of the secondary battery. The reason can be that the sum of the mass percentage contents of the acrylate-based oligomer and the diphenyl disulfide-based monomer is conducive to alleviating the deterioration of the ionic conductivity of the gel electrolyte, and thus making the secondary battery have a longer cycle life.

[0256] According to some embodiments of the present application, the secondary battery is a lithium ion battery, and at least one of the following conditions is met: the concentration of the electrolyte salt in the mixture of the solvent and the electrolyte salt is 1M-3M; the precursor solution further includes an additive, and the mass ratio of the mass of the additive to the sum of the masses of the solvent and the electrolyte salt is 0.5-5:100.

[0257] The concentration of the electrolyte salt is 1M-3M, for example, the concentration of the electrolyte salt can be 1M, 2M, 3M, or in any range of any of the above values.

[0258] The additive can be consistent with the description above, and will not be repeated here.

[0259] The ratio of the mass of the additive to the sum of the mass of the solvent and the electrolyte salt is 0.5-5:100, for example, the ratio of the mass of the additive to the sum of the mass of the solvent and the electrolyte salt can be 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, or in any range of any of the above values.

[0260] Setting the concentration of the electrolyte salt and / or the mass content of the additive in the lithium ion battery in the above range is conducive to the performance of the lithium ion battery, and can further improve the cycle life of the lithium ion battery.

[0261] According to some embodiments of the present application, the secondary battery is a lithium metal battery, and the precursor solution further comprises a diluent, and the mass ratio of the electrolyte salt, the solvent and the diluent is 10-30:5-20:50-85.

[0262] The diluent can be consistent with the description above, and will not be repeated here.

[0263] The mass ratio of the electrolyte salt, the solvent and the diluent can be specifically 10:5:85, 20:5:75, 30:5:65, 10:10:80, 20:10:70, 30:10:60, 10:15:75, 20:15:65, 30:15:55, 10:20:70, 20:20:60, 30:20:50, or in any range of any of the above values.

[0264] Setting the mass ratio of the electrolyte salt, the solvent and the diluent in the lithium metal battery in the above range is conducive to the performance of the lithium metal battery, and can further improve the cycle life of the lithium metal battery.

[0265] [gel electrolyte]

[0266] According to some embodiments of the present application, the present application provides a gel electrolyte comprising a polymer, a solvent and an electrolyte salt; the polymer comprises a copolymer of an acrylate-based oligomer and a diphenyl disulfide-based monomer.

[0267] The secondary battery using the above gel electrolyte has a long cycle life. The reason can be that the acrylate groups in the copolymer of the acrylate-based oligomer and the diphenyl disulfide-based monomer can interact with the anions, O, F in the solvent (such as forming hydrogen bonds, polyurethane bonds, polyurea bonds, etc.), anchoring the solvent, so that the solvent does not flow to the negative electrode to contact the negative electrode and cause side reactions; and when the gel electrolyte is damaged during the charge-discharge cycle of the secondary battery, the disulfide bond in the diphenyl disulfide-based monomer can repair it under the working conditions of the secondary battery.

[0268] According to some embodiments of the present application, the acrylate-based oligomer comprises one of the first functional group and the second functional group;

[0269] The diphenyl disulfide-based monomer comprises the other of the first functional group and the second functional group;

[0270] The first functional group comprises at least one of a hydroxyl group and an amino group;

[0271] The second functional group comprises an isocyanate group.

[0272] The first functional group and the second functional group can react to polymerize the acrylate-based oligomer and the diphenyl disulfide-based monomer, i.e. the hydroxyl group and / or the amino group can react with the isocyanate group, such as the hydroxyl group reacting with the isocyanate group, or the amino group reacting with the isocyanate group, or the hydroxyl group and the amino group together reacting with the isocyanate group. In order to ensure the smooth progress of the polymerization reaction, either the acrylate-based oligomer or the diphenyl disulfide-based monomer cannot simultaneously comprise the first functional group and the second functional group, i.e. the above "the acrylate-based oligomer comprises one of the first functional group and the second functional group; the diphenyl disulfide-based monomer comprises the other of the first functional group and the second functional group" means that if the acrylate-based oligomer comprises the first functional group, then the diphenyl disulfide-based monomer comprises the second functional group; and if the acrylate-based oligomer comprises the second functional group, then the diphenyl disulfide-based monomer comprises the first functional group.

[0273] Thus, the first functional group and the second functional group can undergo a polymerization reaction under mild conditions to obtain a copolymer.

[0274] According to some embodiments of the present application, the solid content of the gel electrolyte is 2% to 15%.

[0275] For example, the solid content of the gel electrolyte can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or within any range of any of the above values.

[0276] The solid content of the gel electrolyte is set in the above range, which can further prolong the cycle life of the secondary battery. The reason can be that the lower solid content makes the gel electrolyte have better ionic conductivity, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0277] According to some embodiments of the present application, the acrylate-based oligomer comprises a copolymer of a first acrylate-based monomer and a second acrylate-based monomer;

[0278] The first acrylate-based monomer does not comprise a functional group;

[0279] The second acrylate-based monomer comprises one of a first functional group and a second functional group.

[0280] The "second acrylate-based monomer comprises one of a first functional group and a second functional group" means that the second acrylate-based monomer comprises the first functional group, or the second acrylate-based monomer comprises the second functional group, and the second acrylate-based monomer cannot comprise both the first functional group and the second functional group.

[0281] Thus, the cycle life of the secondary battery can be further prolonged. The reason can be that by pre-polymerizing the first acrylate-based monomer and the second acrylate-based monomer, the molecular weight of the acrylate-based oligomer can be increased, the solid content of the gel electrolyte can be reduced, thereby making the secondary battery have a longer cycle life, while also taking into account better kinetic performance.

[0282] According to some embodiments of the present application, the first acrylate-based monomer comprises a compound represented by Formula I:

[0283] In Formula I, R1 is a C1-C10 alkyl group, a C1-C10 fluoroalkyl group, a C1-C10 alkoxy-substituted alkyl group, or a C1-C10 fluoroalkoxy-substituted fluoroalkyl group;

[0284] R2 is a hydrogen atom or a methyl group.

[0285] According to some embodiments of the present application, the compound represented by Formula I comprises at least one of the following compounds:

[0286] The use of the above first acrylate-based monomer can further prolong the cycle life of the secondary battery.

[0287] According to some embodiments of the present application, the second acrylate-based monomer comprises a compound represented by Formula II:

[0288] In Formula II, R3 is C1-C20 alkylene, C1-C20 fluoroalkylene, C1-C20 alkyleneoxy-substituted alkylene, C1-C20 fluoroalkyleneoxy-substituted fluoroalkylene;

[0289] R4 is a hydrogen atom or a methyl group;

[0290] R5 is one of a first functional group and a second functional group.

[0291] According to some embodiments of the present application, the compound shown in Formula II includes at least one of the following compounds:

[0292] The use of the above-mentioned second acrylate monomer can further prolong the cycle life of the secondary battery.

[0293] According to some embodiments of the present application, the diphenyl disulfide monomer includes a compound shown in Formula III:

[0294] R6, R7, R8, R9, R 10 , R 11 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyl-oxy group, or a substituted or unsubstituted C1-C20 fluoroalkyl group; and at least one of R6, R7, R8 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyl-oxy group containing a substituent, or a C1-C20 fluoroalkyl group containing a substituent; and at least one of R9, R 10 , R 11 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyl-oxy group containing a substituent, or a C1-C20 fluoroalkyl group containing a substituent, the substituent being the other of the first functional group and the second functional group.

[0295] According to some embodiments of the present application, the compound shown in Formula III includes at least one of the following compounds:

[0296] The use of the above-mentioned diphenyl disulfide monomer can further prolong the cycle life of the secondary battery. The reason can be that the above-mentioned diphenyl disulfide monomer can provide a steric hindrance effect by the benzene ring, and better guarantee the function of disulfide bond repair.

[0297] The solvent and the electrolyte salt in the gel electrolyte can be consistent with the foregoing description, and will not be repeated here.

[0298] [Power-using device]

[0299] According to some embodiments of the present application, the present application also provides a power consuming device comprising the secondary battery provided by the present application. The secondary battery can be used as a power source of the power consuming device, or can be used as an energy storage unit of the power consuming device. The power consuming device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0300] As the power consuming device, the secondary battery can be selected according to the use requirement thereof.

[0301] FIG. 6 is a power consuming device as an example. The power consuming device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirement of high power and high energy density of the power consuming device, a battery pack or a battery module can be used.

[0302] As another example of the power consuming device, a mobile phone, a tablet computer, a notebook computer, etc. can be used. The power consuming device usually requires thin and light, and a battery monomer can be used as a power source.

[0303] Embodiments

[0304] The following examples more specifically describe the present disclosure, which are merely illustrative and not restrictive, since various modifications and changes can be made in the scope of the present disclosure, which will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods, and can be used directly without further treatment, and the instruments used in the examples are commercially available.

[0305] The lithium ion batteries of Examples 1-18 and Comparative Example 1 were prepared according to the following method.

[0306] Preparation of the positive electrode sheet

[0307] The positive electrode active material lithium nickel cobalt manganese oxide LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), a conductive agent acetylene black, and a binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 98:1:1, a solvent N-methyl pyrrolidone (NMP) was added, and stirring was performed until the system was uniform, to obtain a positive electrode slurry (solid content of 70%); the positive electrode slurry was coated on the positive electrode current collector at a thickness of about 12.5 mg / cm 2The load is evenly coated on both sides of the positive current collector aluminum foil, dried at room temperature, transferred to an oven for further drying, and then cut into 40mm×50mm rectangles as positive electrode sheets.

[0308] Preparation of negative electrode sheet

[0309] The negative electrode active material silicon powder, conductive agent acetylene black, dispersant sodium carboxymethyl cellulose (CMC), and binder polyacrylic acid (PAA) were mixed in a mass ratio of 95:1:1:2. Water was added as a solvent and stirred until the system was homogeneous to obtain a negative electrode slurry (solid content 60%). The negative electrode slurry was then mixed with approximately 2 mg / cm³ of water. 2 The load is evenly coated on the negative electrode current collector copper foil, dried at room temperature, transferred to an oven for further drying, and then cut into 41mm×51mm rectangles as negative electrode sheets.

[0310] Preparation of gel electrolyte precursor solution

[0311] The first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent in Table 3 are mixed to obtain an oligomer precursor solution; the oligomer precursor solution is stirred at 50℃~70℃ for 8 hours~12 hours to obtain acrylate oligomer 1-acrylate oligomer 12.

[0312] Mix the electrolyte salts, ester solvents and additives in Table 4 and stir thoroughly to form solutions 1-8.

[0313] Mix the acrylate oligomers, diphenyl disulfide monomers, and solutions from Table 7 and stir thoroughly to form a gel electrolyte precursor solution.

[0314] Separating membrane

[0315] Polyethylene porous membrane was selected and cut into rectangles of 45mm × 55mm.

[0316] Preparation of lithium-ion batteries

[0317] The cut positive electrode sheet, separator, and negative electrode sheet are stacked in sequence to obtain an electrode assembly. The electrode assembly is placed in an aluminum-plastic film outer packaging bag to obtain a dry cell. The gel electrolyte precursor liquid is injected into the dry cell, and the aluminum-plastic film outer packaging bag is vacuum heat-sealed. It is left to stand at room temperature for 6 hours, and then transferred to 60°C for 12 hours to allow the gel electrolyte precursor liquid to solidify in situ, forming a gel electrolyte, and obtaining a lithium-ion battery with a rated capacity of 70mAh.

[0318] Comparative Example 1

[0319] The lithium metal battery of Example 19-34 and Comparative Example 2 were prepared according to the following method.

[0320] The lithium metal battery of Example 19-34 and Comparative Example 2 were prepared according to the following method.

[0321] Preparation of the positive electrode sheet

[0322] The positive electrode active material lithium nickel cobalt manganese oxide LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), a conductive agent acetylene black, and a binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 98:1:1, a solvent N-methyl pyrrolidone (NMP) was added, and stirring was performed until the system was uniform, to obtain a positive electrode slurry (solid content of 70%); the positive electrode slurry was uniformly coated on both sides of a positive electrode current collector aluminum foil at a loading of about 12.5 mg / cm 2 After air-drying at room temperature, the positive electrode current collector aluminum foil was transferred to an oven for further drying, and then cut into a 40 mm x 50 mm rectangle as a positive electrode sheet.

[0323] Preparation of the negative electrode sheet

[0324] A 50 μm thick lithium foil was coated on a 12 μm thick copper foil by rolling, and then cut into a 41 mm x 51 mm rectangle as a negative electrode sheet.

[0325] Preparation of the gel electrolyte precursor solution

[0326] The first acrylic ester monomer, the second acrylic ester monomer, the initiator, and the organic solvent in Table 3 were mixed to obtain an oligomer precursor solution; the oligomer precursor solution was stirred at 50-70 °C for 8-12 hours to obtain the acrylic ester oligomer 1-acrylic ester oligomer 12.

[0327] The electrolyte salt, the ether solvent, and the diluent in Table 5 were mixed and stirred to form a solution 1-solution 8.

[0328] The acrylic ester oligomer, the diphenyl disulfide monomer, and the solution in Table 8 were mixed and stirred to form a gel electrolyte precursor solution.

[0329] Separation film

[0330] A polyethylene porous film was selected and cut into a 45 mm x 55 mm rectangle.

[0331] Preparation of the lithium metal battery

[0332] The cut positive electrode sheet, the separator, and the negative electrode sheet are stacked in order to obtain an electrode assembly, and the electrode assembly is placed in an aluminum plastic film outer packaging bag to obtain a dry battery cell; the gel electrolyte precursor solution is injected into the dry battery cell, and the aluminum plastic film outer packaging bag is vacuum heat-pressed and packaged, and is left to stand at room temperature for 6 hours and then at 60°C for 12 hours to allow the precursor solution to solidify in situ to form a gel electrolyte, thereby obtaining a lithium metal battery. The rated capacity of the lithium metal battery is 70 mAh.

[0333] Comparative Example 2

[0334] The lithium metal battery is prepared by the same method as in Example 19, except that no acrylate oligomer or diphenyl disulfide monomer is added to the gel electrolyte precursor solution, and solution 9 shown in Table 5 is used as the electrolyte of the lithium metal battery.

[0335] Test Part

[0336] 1. Long cycle test of lithium ion battery

[0337] The lithium ion battery prepared above is used, the ambient temperature is set to 25°C, and the battery is subjected to charge-discharge cycling at a rate of 0.33C (i.e. 23 mA) charging and 0.33C discharging. The cut-off voltages for charging and discharging are set to 4.2V and 3V, respectively, and the charging process uses a constant current-constant voltage charging method. Specifically, after 0.33C constant current charging reaches the cut-off voltage of 4.2V, constant voltage charging at 4.2V is used instead until the current decays to 0.1C (i.e. 7 mA). When the discharge capacity decays to 80% of the discharge capacity of the first cycle, the number of cycles the battery has undergone is taken as the cycle life of the battery. The results of the long cycle test of the lithium ion battery are shown in Table 7.

[0338] 2. Long cycle test of lithium metal secondary battery

[0339] The lithium metal battery prepared above is used, the ambient temperature is set to 25°C, and the battery is subjected to charge-discharge cycling at a rate of 0.2C (i.e. 14 mA) charging and 1C discharging (i.e. 70 mA). The cut-off voltages for charging and discharging are set to 4.3V and 2.8V, respectively, and the charging process uses a constant current-constant voltage charging method. Specifically, after 0.2C constant current charging reaches the cut-off voltage of 4.3V, constant voltage charging at 4.3V is used instead until the current decays to 0.1C (i.e. 7 mA). When the discharge capacity decays to 80% of the discharge capacity of the first cycle, the number of cycles the battery has undergone is taken as the cycle life of the battery. The results of the long cycle test of the lithium metal battery are shown in Table 8.

[0340] Table 1 First acrylate monomer

[0341] Note: I-1, I-2, I-3, I-4, I-5, I-6, I-7, and I-8 in Table 1 are commercially available.

[0342] Table 2 Second acrylate monomer

[0343] Note: In Table 2, II-1, II-2, II-3, II-4, II-5, II-6, II-7, and II-8 can be commercially available.

[0344] Table 3 Composition of acrylate oligomer

[0345] Note: In Table 3, AIBN (azobisisobutyronitrile), EMC (methyl ethyl carbonate), and DME (dimethoxyethane) can be commercially available; I-1, I-4, and I-5 are as shown in Table 1; II-1, II-4, and II-8 are as shown in Table 2.

[0346] In Table 3, the mass fraction of the first acrylate monomer is the ratio of the mass of the first acrylate monomer to the sum of the masses of the first acrylate monomer, the second acrylate monomer, the initiator, and the organic solvent; the mass fraction of the second acrylate monomer is the ratio of the mass of the second acrylate monomer to the sum of the masses of the first acrylate monomer, the second acrylate monomer, the initiator, and the organic solvent; the mass fraction of the initiator is the ratio of the mass of the initiator to the sum of the masses of the first acrylate monomer, the second acrylate monomer, the initiator, and the organic solvent; and the mass fraction of the organic solvent is the ratio of the mass of the organic solvent to the sum of the masses of the first acrylate monomer, the second acrylate monomer, the initiator, and the organic solvent.

[0347] Table 4 Composition of solutions 1-8

[0348] Note: In Table 4, LiFSI (lithium bisfluorosulfonylimide), LiPF6 (lithium hexafluorophosphate), EC (ethylene carbonate), EMC (methyl ethyl carbonate), DEC (diethyl carbonate), FEC (fluoroethylene carbonate), PC (propylene carbonate), FEMC (fluoromethyl ethyl carbonate), VC (vinylene carbonate), and PS (propane sulfone) can be commercially available.

[0349] In Table 4, the unit M of the lithium salt concentration refers to mol / L; the volume ratio of the ester solvents refers to the volume ratio of ester solvent 1, ester solvent 2, and ester solvent 3; and the mass fraction of the additive refers to the ratio of the mass of the additive to the sum of the masses of the additive, the ester solvents, and the electrolyte salt.

[0350] Table 5 Composition of solutions 9-16

[0351] Note: In Table 5, LiFSI (lithium bisfluorosulfonylimide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), DME (dimethoxyethane), TTE (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether), Bz (benzene) are commercially available.

[0352] In Table 5, the mass fraction of the electrolyte salt refers to the ratio of the mass of the electrolyte salt to the sum of the masses of the electrolyte salt, the ether solvent and the diluent; the mass fraction of the ether solvent refers to the ratio of the mass of the ether solvent to the sum of the masses of the electrolyte salt, the ether solvent and the diluent; the mass fraction of the diluent refers to the ratio of the mass of the diluent to the sum of the masses of the electrolyte salt, the ether solvent and the diluent.

[0353] Table 6 Diphenyl disulfide monomers

[0354] Note: In Table 6, III-1, III-2, III-3, III-4, III-5, III-6, III-7, III-8 are commercially available.

[0355] Table 7

[0356] Note: In Table 7, the acrylate oligomer 1, the acrylate oligomer 4, the acrylate oligomer 5, the acrylate oligomer 6, the acrylate oligomer 7, the acrylate oligomer 8 are shown in Table 3; III-5, III-6, III-7 are shown in Table 6; the compositions of Solution 1-Solution 8 are shown in Table 4, the solutions including electrolyte salts and solvents; the mass ratio is the mass ratio of the acrylate oligomer, the diphenyl disulfide monomer and the solution; the solid content is the mass ratio of the polymer (copolymer of the acrylate oligomer and the diphenyl disulfide monomer) in the gel electrolyte.

[0357] As can be seen from Example 1 and Comparative Example 1, the lithium ion battery assembled by the gel electrolyte of the application has a longer cycle life than the lithium ion battery assembled only by the solution.

[0358] As can be seen from Examples 1-3, the lithium ion battery has a longer cycle life by using the diphenyl disulfide monomer of the application.

[0359] As can be seen from Example 1 and Example 4, the lithium ion battery has a longer cycle life by using the mass ratio of the first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent of the application.

[0360] As can be seen from Example 1 and Examples 4-8, the lithium ion battery has a longer cycle life by using the acrylate oligomer of the application.

[0361] As can be seen from Example 1 and Examples 9-15, the copolymer, solvent and electrolyte lithium salt of the present application can improve the long cycle life of the lithium ion battery.

[0362] As can be seen from Example 1 and Examples 16-18, the gel electrolyte in the secondary battery of the present application can achieve a low solid content, and the lithium ion battery using the same has a long cycle life.

[0363] Table 8

[0364] Note: In Table 8, acrylate oligomer 1, acrylate oligomer 2, acrylate oligomer 3, acrylate oligomer 9, acrylate oligomer 10, acrylate oligomer 11, acrylate oligomer 12 are as shown in Table 3; III-5, III-6, III-7 are as shown in Table 6; the composition of solution 9-solution 16 is as shown in Table 5, the solution includes an electrolyte salt and a solvent; the mass ratio is the mass ratio of the acrylate oligomer, the diphenyl disulfide monomer and the solution; the solid content is the mass ratio of the polymer (copolymer of the acrylate oligomer and the diphenyl disulfide monomer) in the gel electrolyte.

[0365] As can be seen from Example 19 and Comparative Example 2, the lithium metal battery using the gel electrolyte of the present application has a longer cycle life than the lithium metal battery using only the solution.

[0366] As can be seen from Examples 19-21, the use of the diphenyl disulfide monomer of the present application can make the lithium metal battery have a longer cycle life.

[0367] As can be seen from Example 19 and Example 22, the use of the first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent of the present application in a mass ratio can make the lithium metal battery have a longer cycle life.

[0368] As can be seen from Example 19 and Examples 23-26, the use of the acrylate oligomer of the present application can make the lithium metal battery have a longer cycle life.

[0369] As can be seen from Example 19 and Examples 27-32, the use of the copolymer, solvent and electrolyte lithium salt of the present application can improve the long cycle life of the lithium metal battery.

[0370] As can be seen from Example 19 and Examples 33-34, the gel electrolyte in the secondary battery of the present application can achieve a low solid content, and the lithium metal battery using the same has a long cycle life.

[0371] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced equivalently. Such modifications or replacements do not change the essence of the corresponding technical solutions, which should be covered in the scope of the present application. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A secondary battery, wherein, The secondary battery includes an outer package, and an electrode assembly and a gel electrolyte contained in the outer package, The gel electrolyte includes a polymer, a solvent, and an electrolyte salt; The polymer includes an acrylate group and a disulfide bond.

2. The secondary battery according to claim 1, wherein The polymer includes a copolymer of an acrylate-based oligomer and a diphenyl disulfide-based monomer.

3. The secondary battery according to claim 2, wherein The acrylate-based oligomer includes one of a first functional group and a second functional group; The diphenyl disulfide-based monomer includes the other of the first functional group and the second functional group; The first functional group includes at least one of a hydroxyl group and an amino group; The second functional group includes an isocyanate group.

4. The secondary battery according to any one of claims 1 to 3, wherein The gel electrolyte has a solid content of 2% to 15%.

5. The secondary battery according to any one of claims 1-4, wherein, The acrylate-based oligomer includes a copolymer of a first acrylate-based monomer and a second acrylate-based monomer; The first acrylate-based monomer does not include a functional group; The second acrylate-based monomer includes a first functional group or a second functional group.

6. The secondary battery according to claim 5, wherein The first acrylate-based monomer includes a compound represented by Formula I: In Formula I, R1 is C1-C10 alkyl, C1-C10 fluoroalkyl, C1-C10 alkoxy-substituted alkyl, or C1-C10 fluoroalkoxy-substituted fluoroalkyl; R2 is a hydrogen atom or a methyl group.

7. The secondary battery according to claim 6, wherein The compound of Formula I includes at least one of the following compounds:

8. The secondary battery according to any one of claims 5 to 7, characterized by, The second acrylate-based monomer includes a compound represented by Formula II: In Formula II, R3 is C1-C20 alkylene, C1-C20 fluoroalkylene, C1-C20 alkyleneoxy-substituted alkylene, C1-C20 fluoroalkyleneoxy-substituted fluoroalkylene; R4 is a hydrogen atom or a methyl group; R5 is a first functional group or a second functional group.

9. The secondary battery according to claim 8, wherein The compound of Formula II includes at least one of the following compounds:

10. The secondary battery according to any one of claims 3-9, wherein, The diphenyl disulfide monomers include compounds represented by Formula III: wherein R6, R7, R8, R9, R 10 , R 11 each independently is a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyl-oxy group, a substituted or unsubstituted C1-C20 fluoroalkyl group; and At least one of R6, R7, and R8 is C1-C20 alkyl containing a substituent, C1-C20 alkyloxy containing a substituent, or C1-C20 fluoroalkyl containing a substituent; at least one of R9, R 10 , R 11 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyl-oxy group containing a substituent or a C1-C20 fluoroalkyl group containing a substituent, The substituent is the other of the first functional group and the second functional group.

11. The secondary battery according to claim 10, wherein The compound of Formula III includes at least one of the following compounds:

12. The secondary battery according to any one of claims 1-11, wherein, The electrolyte salt includes one or more of lithium bisfluorosulfonimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis-trifluoromethylsulfonimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium bisoxalate borate, lithium difluorobisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorobisoxalate phosphate.

13. The secondary battery according to any one of claims 1-12, wherein, The secondary battery is a lithium ion battery and satisfies at least one of the following conditions: The solvent includes an ester-based solvent, and the ester-based solvent includes one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoro-vinyl carbonate, difluoro-vinyl carbonate, fluoro-methyl ethyl carbonate, fluoro-diethyl carbonate, fluoro-ethyl formate, fluoro-ethyl acetate, and fluoro-methyl acetate; The gel electrolyte further includes an additive, and the additive includes one or more of ethylene carbonate, propane sultone, ethylene sulfate, ethylene sulfite, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilyl) borate, dimethyl maleic anhydride, and 1,4-diisocyanatobutane.

14. The secondary battery according to claim 13, wherein The electrolyte salt is contained in the gel electrolyte in an amount of 8% to 15%; and / or The ester-based solvent is contained in the gel electrolyte in an amount of 80% to 90%; and / or The content of the additive in the gel electrolyte is 0.2% to 5%.

15. The secondary battery according to any one of claims 1-14, wherein, The secondary battery is a lithium metal battery and satisfies at least one of the following conditions: The solvent includes one or more of ethers, including diethyl ether, dipropyl ether, ethyl propyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol methyl ethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyl tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, 1,3-dioxane, 1,4-dioxane; The gel electrolyte further includes a diluent, which includes one or more of benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluoromethylbenzene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, bis(1,1,2,2-tetrafluoroethyl) ether.

16. The secondary battery according to claim 15, wherein, The content of the diluent in the gel electrolyte is 60% to 75%.

17. The secondary battery according to any one of claims 1-16, wherein, The content of the electrolyte salt in the gel electrolyte is 12% to 20%.

18. The secondary battery according to any one of claims 1-17, wherein, The content of the ether solvent in the gel electrolyte is 8% to 15%.

19. A method of making a secondary battery, wherein, The method comprises: mixing raw materials for forming a polymer, a solvent, and an electrolyte salt to obtain a precursor solution, the raw materials for forming a polymer having an acrylate group and a disulfide bond; placing an electrode assembly in an outer package to obtain a dry battery cell; injecting the precursor solution into the dry battery cell, sealing the outer package, and allowing the precursor solution to cure in situ to obtain the secondary battery.

20. The method of claim 19, wherein, The raw materials for forming a polymer include an acrylate oligomer and a diphenyl disulfide monomer.

21. The method of claim 20, wherein, The steps of preparing the acrylate oligomer include: mixing a first acrylate monomer, a second acrylate monomer, an initiator, and an organic solvent to obtain an oligomer precursor solution; stirring the oligomer precursor solution at 50°C to 70°C for 8 hours to 12 hours to obtain the acrylate oligomer.

22. The method of claim 21, wherein, The mass ratio of the first acrylate monomer, the second acrylate monomer, the initiator and the organic solvent is 18-54:2-10:0.1-2:40-80; and / or The initiator comprises at least one of azobisisobutyronitrile, azobisisoheptyl nitrile, acetyl peroxide, hydrogen peroxide; and / or The organic solvent comprises one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoroethylene carbonate, difluoroethylene carbonate, fluoro methyl ethyl carbonate, fluoro diethyl carbonate, fluoro ethyl formate, fluoro ethyl acetate, fluoro methyl acetate, diethyl ether, dipropyl ether, ethyl propyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol methyl ethyl ether, propylene glycol diethyl ether, butylene glycol dimethyl ether, butylene glycol methyl ethyl ether, butylene glycol diethyl ether, benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl) ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoromethyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether, bis(1,1,2,2-tetrafluoroethyl) ether.

23. The method of any one of claims 19-22, wherein, The temperature of the in-situ curing is 40-80℃.

24. The method of any one of claims 20-23, wherein, The mass ratio of the acrylate oligomer and the diphenyl disulfide monomer is 5-30:0.5-5; and / or The sum of the mass percentage contents of the acrylate oligomer and the diphenyl disulfide monomer is 5.5%-35% based on the total mass of the precursor solution.

25. The method of any one of claims 19-24, wherein, The secondary battery is a lithium ion battery, and at least one of the following conditions is met: In the mixture of the solvent and the electrolyte salt, the concentration of the electrolyte salt is 1M-3M; The precursor solution further comprises an additive, and the ratio of the mass of the additive to the sum of the masses of the solvent and the electrolyte salt is 0.5-5:

100.

26. The method of any one of claims 19-24, wherein, The secondary battery is a lithium metal battery, the precursor solution further includes a diluent, and a mass ratio of the electrolyte salt, the solvent, and the diluent is 10-30:5-20:50-85.

27. A gel electrolyte, wherein, The gel electrolyte includes a polymer, a solvent, and an electrolyte salt. The polymer includes an acrylate group and a disulfide bond.

28. The gel electrolyte of claim 27, wherein, The raw material for forming the polymer includes an acrylate oligomer including one of a first functional group and a second functional group. The diphenyl disulfide monomer includes the other of the first functional group and the second functional group. The first functional group includes at least one of a hydroxyl group and an amino group. The second functional group includes an isocyanate group.

29. The gel electrolyte of claim 27 or 28, wherein, The gel electrolyte has a solid content of 2-15%.

30. The gel electrolyte of any one of claims 27-29, wherein, The raw material for forming the polymer includes an acrylate oligomer including a copolymer of a first acrylate monomer and a second acrylate monomer. The first acrylate monomer does not include a functional group. The second acrylate monomer includes one of a first functional group and a second functional group.

31. The gel electrolyte of claim 30, wherein, The first acrylate-based monomer includes a compound represented by Formula I: In Formula I, R1 is C1-C10 alkyl, C1-C10 fluoroalkyl, C1-C10 alkoxy-substituted alkyl, or C1-C10 fluoroalkoxy-substituted fluoroalkyl. R2 is a hydrogen atom or a methyl group.

32. The gel electrolyte of claim 31, wherein, The compound of Formula I includes at least one of the following compounds:

33. The gel electrolyte of any one of claims 30-32, wherein, The second acrylate-based monomer includes a compound represented by Formula II: In Formula II, R3 is C1-C20 alkylene, C1-C20 fluoroalkylene, C1-C20 alkyleneoxy-substituted alkylene, C1-C20 fluoroalkyleneoxy-substituted fluoroalkylene. R4 is a hydrogen atom or a methyl group. R5 is one of a first functional group and a second functional group.

34. The gel electrolyte of claim 33, wherein, The compound of Formula II includes at least one of the following compounds:

35. The gel electrolyte of any one of claims 28-34, wherein, The diphenyl disulfide monomers include compounds represented by Formula III: wherein R6, R7, R8, R9, R 10 , R 11 each independently is a hydrogen atom, a halogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkyl-oxy group, a substituted or unsubstituted C1-C20 fluoroalkyl group; and At least one of R6, R7, and R8 is C1-C20 alkyl containing a substituent, C1-C20 alkyloxy containing a substituent, or C1-C20 fluoroalkyl containing a substituent. at least one of R9, R 10 , R 11 is a C1-C20 alkyl group containing a substituent, a C1-C20 alkyl-oxy group containing a substituent or a C1-C20 fluoroalkyl group containing a substituent, The substituent is the other of the first functional group and the second functional group.

36. The gel electrolyte of claim 35, wherein, The compound of Formula III includes at least one of the following compounds:

37. A secondary battery wherein, The secondary battery includes: An outer package, and an electrode assembly and a gel electrolyte accommodated in the outer package, wherein: The gel electrolyte includes a polymer, a solvent, and an electrolyte salt. The polymer includes a copolymer of an acrylate oligomer and a diphenyl disulfide monomer.

38. A gel electrolyte, wherein, The gel electrolyte includes a polymer, a solvent, and an electrolyte salt. The polymer includes a copolymer of an acrylate oligomer and a diphenyl disulfide monomer.

39. An electrical device, comprising: The secondary battery includes: The secondary battery includes:

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