Electrolyte composition, secondary battery and method for manufacturing the same, and electric device comprising the same

Abstract

The application provides an electrolyte composition, a secondary battery and a preparation method thereof and an electric device comprising the same. The preparation method of the secondary battery comprises the following steps: pre-polymerizing raw materials including an electrolyte, an A component and a B component to form a gel electrolyte precursor, the A component comprising a polyhydric alcohol and / or a polyamine, the B component comprising a trifunctional isocyanate, the viscosity of the A component being below 1000 mPa·s, and the viscosity of the trifunctional isocyanate being below 500 mPa·s; injecting the gel electrolyte precursor into an inner cavity of a shell, and polymerizing the gel electrolyte precursor in the inner cavity of the shell to form a gel electrolyte, and an electrode assembly is arranged in the inner cavity of the shell.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrolyte composition, a secondary battery, a method for preparing the same, and an electrical device comprising the same. Background Technology

[0002] As the number of electric vehicles on the road gradually increases, a large number of consumers still hesitate between gasoline and electric cars, mainly due to "range anxiety" and battery life issues. In addition to the booming electrification of the automotive industry, the "low-altitude economy" brought about by electric aircraft is gradually attracting the attention of major investors. Both the "range anxiety" problem of automobiles and the huge potential of the "low-altitude economy" of electric aircraft point to the key issue of battery energy density. Currently, improving battery energy density is mainly achieved by using high-energy-density positive and negative electrodes, such as high-nickel ternary cathodes and high-energy-density negative electrodes such as silicon and lithium metal anodes.

[0003] However, during battery cycling, problems such as oxygen release in high-nickel ternary cathodes, pulverization in silicon anodes, and dendrite formation in lithium metal anodes can all shorten battery life. To address these issues, current research is focusing on gel electrolytes to improve battery life. Summary of the Invention

[0004] To address the problem that the preparation of gel electrolytes in the prior art is difficult to control, this application provides an electrolyte composition, a secondary battery, a method for preparing the same, and an electrical device containing the same.

[0005] The first aspect of this application provides a method for preparing a secondary battery, comprising:

[0006] A gel electrolyte precursor solution is formed by prepolymerizing raw materials including an electrolyte, component A, and component B. Component A includes polyols and / or polyamines, component B includes trifunctional isocyanates, and the viscosity of component A is 1000. Below, the viscosity of trifunctional isocyanates is 500. the following;

[0007] The gel electrolyte precursor solution is injected into the inner cavity of the shell, where it polymerizes to form a gel electrolyte. An electrode assembly is also provided in the inner cavity of the shell.

[0008] This application enables the in-situ polymerization of component A (comprising polyols and / or polyamines) and component B (comprising trifunctional isocyanates) in an electrolyte. By controlling the viscosity of components A and B and utilizing the amount of isocyanate in the trifunctional isocyanate as a rate-limiting condition for polymerization, the degree of polymerization is controlled. This achieves excellent control over the viscosity of the gel electrolyte precursor solution, allowing for a smooth and efficient injection process. Because the gel electrolyte precursor solution used for injection has a suitable viscosity, it exhibits good wettability of the electrodes and separators in the electrode assembly after injection into the battery casing cavity. This effectively controls problems such as localized lithium plating during battery cell cycling, thereby extending the battery cell's lifespan.

[0009] In any embodiment of the first aspect, the viscosity of the gel electrolyte precursor solution is 3 before it is injected into the inner cavity of the housing. -50 The lower viscosity of the gel electrolyte precursor solution better meets the requirements of the injection viscosity and provides a good foundation for the further curing of the prepolymer in the gel electrolyte precursor solution after injection, thus shortening the time required for further crosslinking.

[0010] In any embodiment of the first aspect, the viscosity of the gel electrolyte precursor solution after being placed at 25°C for 24 hours is 5. - 25 .

[0011] In any embodiment of the first aspect, the trifunctional isocyanate includes one or more of triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, and trifunctional isocyanate prepolymer.

[0012] In any embodiment of the first aspect, the viscosity of the trifunctional isocyanate prepolymer is 30. -2700 .

[0013] In any embodiment of the first aspect, the trifunctional isocyanate prepolymer includes any one or more of the following: trifunctional isocyanate prepolymers formed by polymerizing triols and difunctional isocyanates, and trifunctional isocyanate prepolymers formed by polymerizing triamines and difunctional isocyanates. The aforementioned triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, and hexamethylene diisocyanate trimer are essentially small molecules, thus exhibiting good mixing with component A, which is beneficial for the uniform in-situ polymerization. Controlling the viscosity of the trifunctional isocyanate prepolymer is beneficial both for ensuring uniform mixing with component A and for controlling the viscosity of the gel electrolyte precursor solution formed by the prepolymer.

[0014] In any embodiment of the first aspect, the polyol includes one or more of polyether polyols and polyester polyols; and / or the polyamine includes polyether polyamines.

[0015] In any embodiment of the first aspect, the polyol and the polyamine each independently have one or more of the following characteristics:

[0016] Number-average molecular weight is 400 to 5000 Daltons;

[0017] Viscosity 5 Up to 1000 ;

[0018] The hydroxyl functionality of polyols is ≥2;

[0019] The amino functionality of polyamines is ≥2.

[0020] Having a functionality ≥2 in polyols or an amino functionality ≥2 in polyamines has two advantages: firstly, it provides more chemical bonds during the crosslinking process, thereby increasing the degree of crosslinking of the crosslinking network and enabling the formation of a crosslinking network even at lower viscosities; secondly, it facilitates the formation of a polymer network framework while achieving chain extension, thus enhancing the strength of the gel polymer.

[0021] In any embodiment of the first aspect, the polyol and the polyamine each independently have one or more of the following characteristics:

[0022] Number-average molecular weight is 2000 to 5000 Daltons;

[0023] Viscosity 200 Up to 900 ;

[0024] The hydroxyl functionality of polyols is 2 or 3;

[0025] The amino functionality of polyamines is 2 or 3.

[0026] In any embodiment of the first aspect, component A and component B are mixed in a molar ratio of -NH2 or -OH functional groups in component A to isocyanate functional groups in component B of 1:(1.5-0.8). By controlling the molar amounts of amino and hydroxyl functional groups to isocyanate functional groups within a similar range, crosslinking at an appropriate rate can be ensured, which is beneficial for maintaining a stable and uniform crosslinking reaction rate and thus making the reaction more controllable. In addition, by adjusting this molar ratio, the viscoelasticity of the final gel electrolyte can be adjusted, thereby improving the shock resistance of the gel electrolyte and thus improving the stability of the battery cell.

[0027] In any embodiment of the first aspect, the raw materials further include a catalyst, which includes one or more of organotin catalysts, organobismuth catalysts, and organobase catalysts.

[0028] In any embodiment of the first aspect, the catalyst comprises dibutyltin dilaurate and / or triethylenediamine.

[0029] In any embodiment of the first aspect, the weight of the catalyst is 0.3%-3% of the total weight of components A and B.

[0030] In any embodiment of the first aspect, the process of polymerizing the gel electrolyte precursor solution to form the gel electrolyte includes:

[0031] After the casing containing the gel electrolyte precursor solution is encapsulated, it is sequentially allowed to stand at 20℃-30℃ for 12h-24h and at 45℃-60℃ for 12h-48h. Standing at 20℃-30℃ for 12h-24h allows the gel electrolyte precursor solution to fully wet the electrode and fill the entire battery, while standing at 45℃-60℃ for 12h-48h allows the gel electrolyte precursor solution to fully solidify.

[0032] In any embodiment of the first aspect, the process of forming the gel electrolyte precursor solution includes:

[0033] Component A and electrolyte are mixed to form a mixture;

[0034] The mixture is combined with component B and an optional catalyst and prepolymerized to form a gel electrolyte precursor solution. Component A is first dispersed in the electrolyte, which improves the contact effect between components A and B, thereby improving the mixing uniformity of components A and B. This helps control the rate and process of interaction between components A and B, resulting in the polymerization of a homogeneous polymer. It also improves the uniformity of components A and B in the electrolyte, thus enhancing the dispersion uniformity of the formed gel electrolyte in the electrode assembly.

[0035] In any embodiment of the first aspect, the solid content of the gel electrolyte is 3%-15%.

[0036] A second aspect of this application provides an electrolyte composition comprising an electrolyte, a component A, and a component B, wherein component A comprises a polyol and / or a polyamine, component B comprises a trifunctional isocyanate, and the viscosity of component A is 1000. Below, the viscosity of trifunctional isocyanates is 3000. the following.

[0037] When the above-mentioned electrolyte composition is polymerized in situ in the electrolyte, the viscosity of components A and B is controlled, and the amount of isocyanate in the trifunctional isocyanate is used as the rate-limiting condition for polymerization. This allows for control of the degree of polymerization, i.e., good control of the viscosity of the gel electrolyte precursor solution. This enables the smooth and efficient injection process of the gel electrolyte precursor solution, which is beneficial for its application in the industrial preparation of battery cells. Because the gel electrolyte precursor solution used for injection has a suitable viscosity, it exhibits good wettability of the electrodes and separators in the electrode assembly after being injected into the battery casing cavity. This effectively controls problems such as local lithium plating during battery cell cycling, thereby extending the battery cell's lifespan.

[0038] In any embodiment of the second aspect, the trifunctional isocyanate includes one or more of triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, and trifunctional isocyanate prepolymer.

[0039] In any embodiment of the second aspect, the viscosity of the trifunctional isocyanate prepolymer is 30. -2700 .

[0040] In any embodiment of the second aspect, the trifunctional isocyanate prepolymer includes any one or more of the following: a trifunctional isocyanate prepolymer formed by polymerizing a triol and a difunctional isocyanate, and a trifunctional isocyanate prepolymer formed by polymerizing a triamine and a difunctional isocyanate.

[0041] In any embodiment of the second aspect, the polyol includes one or more of polyether polyols and polyester polyols; and / or the polyamine includes polyether polyamines.

[0042] In any embodiment of the second aspect, the polyol and the polyamine each independently have one or more of the following characteristics:

[0043] Number-average molecular weight is 400 to 5000 Daltons;

[0044] Viscosity 5 Up to 1000 ;

[0045] The hydroxyl functionality of polyols is ≥2;

[0046] The amino functionality of polyamines is ≥2.

[0047] In any embodiment of the second aspect, the polyol and the polyamine each independently have one or more of the following characteristics:

[0048] Number-average molecular weight is 2000 to 5000 Daltons;

[0049] Viscosity 200 Up to 900 ;

[0050] The hydroxyl functionality of polyols is 2 or 3;

[0051] The amino functionality of polyamines is 2 or 3.

[0052] In any embodiment of the second aspect, component A and component B are mixed in a molar ratio of -NH2 or -OH functional groups in component A to isocyanate functional groups in component B of 1:(1.5-0.8).

[0053] In any embodiment of the second aspect, the electrolyte composition further includes a catalyst, which includes one or more of organotin catalysts, organobismuth catalysts, and organic base catalysts.

[0054] In any embodiment of the second aspect, the catalyst comprises dibutyltin dilaurate and / or triethylenediamine.

[0055] In any embodiment of the second aspect, the weight of the catalyst is 0.3%-0.5% of the total weight of components A and B.

[0056] In any embodiment of the second aspect, the total weight content of components A and B in the electrolyte composition is 3%-15%.

[0057] The third aspect of this application provides a secondary battery prepared using the preparation method provided in any embodiment of the first aspect described above.

[0058] The fourth aspect of this application provides an electrical device that includes a battery cell from the third aspect of this application. Attached Figure Description

[0059] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0060] Figure 1 This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0061] Figure 2 yes Figure 1 An exploded view of a secondary battery according to one embodiment of this application is shown.

[0062] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0063] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0064] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0065] Figure 6 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0066] The accompanying drawings are not drawn to scale. Explanation of reference numerals in the attached figures:

[0067] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0068] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0069] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its preparation method, and an electrical device comprising the same. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0070] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, 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 specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0071] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0072] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0073] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0074] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" may mean that other components not listed may also be included or contained.

[0075] Unless otherwise specified, the term "or" is inclusive in this application. For example, any of the following conditions satisfies 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).

[0076] [Preparation methods for secondary batteries]

[0077] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after being discharged to activate the active materials and continue to be used.

[0078] Typically, a secondary battery consists of an electrode assembly, an electrolyte, and a casing. The electrode assembly and electrolyte are located within the casing's inner cavity. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During charging and discharging, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing active ions to pass through. The electrolyte, also located between the positive and negative electrodes, mainly conducts the active ions.

[0079] Currently, gel electrolytes mainly include polyurethane gel electrolytes or polyurea gel electrolytes. These primarily utilize monomers and crosslinking agents to form prepolymers through in-situ polymerization, which are then injected into electrode assemblies via liquid injection. However, in industrial applications, it has been found that the viscosity of the prepolymer formed through in-situ polymerization is difficult to control; excessive viscosity prevents successful liquid injection.

[0080] To control the degree of in-situ polymerization, a first embodiment of this application provides an electrolyte composition comprising an electrolyte, component A, and component B. Component A comprises a polyol and / or a polyamine, component B comprises a trifunctional isocyanate, and the viscosity of component A is 1000. Below, the viscosity of trifunctional isocyanates is 3000. the following.

[0081] When the above-mentioned electrolyte composition is polymerized in situ in the electrolyte, the viscosity of components A and B is controlled, and the amount of isocyanate in the trifunctional isocyanate is used as the rate-limiting condition for polymerization. This allows for control of the degree of polymerization, i.e., good control of the viscosity of the gel electrolyte precursor solution. This enables the smooth and efficient injection process of the gel electrolyte precursor solution, which is beneficial for its application in the industrial preparation of battery cells. Because the gel electrolyte precursor solution used for injection has a suitable viscosity, it exhibits good wettability of the electrodes and separators in the electrode assembly after being injected into the battery casing cavity. This effectively controls problems such as local lithium plating during battery cell cycling, thereby extending the battery cell's lifespan.

[0082] The second embodiment of this application provides a method for preparing a secondary battery, comprising:

[0083] A gel electrolyte precursor solution is formed by prepolymerizing raw materials including an electrolyte, component A, and component B. Component A includes polyols and / or polyamines, component B includes trifunctional isocyanates, and the viscosity of component A is 1000. Below, the viscosity of trifunctional isocyanates is 3000. the following;

[0084] The gel electrolyte precursor solution is injected into the inner cavity of the shell, where it polymerizes to form a gel electrolyte. An electrode assembly is also provided in the inner cavity of the shell.

[0085] This application enables the in-situ polymerization of component A (comprising polyols and / or polyamines) and component B (comprising trifunctional isocyanates) in an electrolyte. By controlling the viscosity of components A and B and utilizing the amount of isocyanate in the trifunctional isocyanate as a rate-limiting condition for polymerization, the degree of polymerization is controlled. This achieves excellent control over the viscosity of the gel electrolyte precursor solution, allowing for a smooth and efficient injection process. Because the gel electrolyte precursor solution used for injection has a suitable viscosity, it exhibits good wettability of the electrodes and separators in the electrode assembly after injection into the battery casing cavity. This effectively controls problems such as localized lithium plating during battery cell cycling, thereby extending the battery cell's lifespan.

[0086] Unless otherwise specified, the viscosities in this application are all obtained by testing at 25°C and stirring at 12 rpm.

[0087] After mixing the raw materials, the resulting gel electrolyte precursor solution may be left to stand for a short time before injection. According to current standard industrial operating procedures, in some embodiments, the viscosity of the gel electrolyte precursor solution is 3 before injection into the inner cavity of the casing. -50 The lower viscosity of the gel electrolyte precursor solution can better meet the requirements of the injection viscosity, and provides a good foundation for the further curing of the prepolymer in the gel electrolyte precursor solution after injection, thus shortening the time required for further crosslinking.

[0088] During the storage of the gel electrolyte precursor solution, polymerization also occurs simultaneously. As time progresses, the viscosity of the gel electrolyte precursor solution increases. The viscosity of the gel electrolyte precursor solution after storage at 25°C for 24 hours is 5. -25 Compared to the viscosity increase of conventional gel electrolyte precursor solutions, the viscosity increase of the gel electrolyte precursor solution in this application is relatively gradual, which is more conducive to meeting the injection requirements.

[0089] In some embodiments, the trifunctional isocyanate includes one or more of triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, and trifunctional isocyanate prepolymer.

[0090] In some embodiments, the viscosity of the trifunctional isocyanate prepolymer is 30. -2700 300 is optional -2600 .

[0091] In some embodiments, the trifunctional isocyanate prepolymer includes any one or more of the following: trifunctional isocyanate prepolymers formed by polymerizing triols and difunctional isocyanates, and trifunctional isocyanate prepolymers formed by polymerizing triamines and difunctional isocyanates. The aforementioned triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, and hexamethylene diisocyanate trimer are essentially small molecules, thus exhibiting good mixing with component A, which is beneficial for the uniform in-situ polymerization. Controlling the viscosity of the trifunctional isocyanate prepolymer is beneficial both for ensuring uniform mixing with component A and for controlling the viscosity of the gel electrolyte precursor solution formed by the prepolymer.

[0092] The polyols and polyamines used in this application can be those commonly used in the preparation of polyurethanes or polyureas. Referring to some embodiments, the polyols include one or more of polyether polyols and polyester polyols; and / or the polyamines include polyether polyamines. The polyether segments in the aforementioned polyols or polyamines are flexible segments, thus improving the elasticity of the formed polyurethane or polyurea, thereby buffering the compressive stress caused by the expansion of the active material during battery cell charging, and improving the structural stability and cycle performance of the battery cell.

[0093] In some embodiments, the polyol and polyamine each independently have one or more of the following characteristics: a number-average molecular weight of 400 to 5000 Daltons (e.g., 400-500 Daltons, or 2000-5000 Daltons); a viscosity of 5... Up to 1000 The hydroxyl functionality of polyols is ≥2; the amino functionality of polyamines is ≥2.

[0094] By controlling the molecular weight and viscosity of polyols and polyamines, it is beneficial to improve the mixing uniformity with trifunctional isocyanates, thereby improving the homogenization of the formed gel polymer. In addition, having a functionality greater than or equal to 2 in the polyol or an amino functionality greater than or equal to 2 in the polyamine is beneficial in two ways: firstly, it provides more chemical bonds during the crosslinking process, thereby increasing the degree of crosslinking of the crosslinking network, enabling the formation of a crosslinking network even at lower viscosities; secondly, it facilitates the formation of a polymer network framework while achieving chain extension, thereby improving the strength of the gel polymer.

[0095] In some embodiments, the polyol and polyamine each independently have one or more of the following characteristics: a number-average molecular weight of 2000 to 5000 Daltons; a viscosity of 200... Up to 900 The hydroxyl functionality of polyols is 2 or 3; the amino functionality of polyamines is 2 or 3.

[0096] In some embodiments, components A and B are mixed in a molar ratio of -NH2 or -OH functional groups in component A to isocyanate functional groups in component B of 1:(1.5-0.8). By controlling the molar amounts of amino and hydroxyl functional groups to isocyanate functional groups within a similar range, crosslinking at an appropriate rate can be ensured, which is beneficial for maintaining a stable and uniform crosslinking reaction rate and thus achieving a more controllable reaction. In addition, by adjusting this molar ratio, the viscoelasticity of the final gel electrolyte can be adjusted, thereby improving the shock resistance of the gel electrolyte and thus enhancing the stability of the battery cell.

[0097] In some embodiments, when forming a gel electrolyte using the electrolyte composition of this application, no catalyst is used during the curing process of the gel electrolyte, that is, the electrolyte composition does not contain a catalyst, and a good curing effect can still be achieved by appropriately extending the standing time.

[0098] In some embodiments, in-situ polymerization is carried out in the presence of a catalyst, i.e., the electrolyte composition includes a catalyst, which includes one or more of organotin catalysts, organobismuth catalysts, and organobase catalysts, to increase the in-situ polymerization rate.

[0099] To minimize the impact of residual catalyst after in-situ polymerization on the performance of the battery cells, in some embodiments, the catalyst includes dibutyltin dilaurate (DBTDL) and / or triethylenediamine (DABCO). Both of these catalysts exhibit good catalytic performance and have stable chemical structures, allowing them to remain stably in the gel electrolyte without negatively affecting the performance of the battery cells.

[0100] In some embodiments using the catalyst, the weight of the catalyst is 0.3%-3% of the total weight of components A and B.

[0101] In some embodiments, the process of polymerizing the gel electrolyte precursor solution to form the gel electrolyte includes: encapsulating the shell containing the gel electrolyte precursor solution, and then allowing it to stand at 20℃-30℃ for 12h-24h, and then at 45℃-60℃ for 12h-48h. Standing at 20℃-30℃ for 12h-24h allows the gel electrolyte precursor solution to fully wet the electrode and fill the entire battery, while standing at 45℃-60℃ for 12h-48h allows the gel electrolyte precursor solution to fully solidify.

[0102] In some embodiments, the process of forming the gel electrolyte precursor solution includes: (1) mixing component A and electrolyte to form a mixture; (2) mixing the mixture with component B and optional catalyst and prepolymerizing to form the gel electrolyte precursor solution. Firstly, dispersing component A in the electrolyte improves the contact effect between component A and component B, thereby improving the mixing uniformity of component A and component B. This helps control the speed and process of interaction between component A and component B, and polymerizes to form a homogeneous polymer. It also improves the uniformity of component A and component B in the electrolyte, thus improving the dispersion uniformity of the formed gel electrolyte in the electrode assembly.

[0103] In some embodiments, the solid content of the gel electrolyte is 3%-15%, optionally 3%-8%, 5%-7%, 8%-15%, or 8%-12%. A suitable solid content can improve the mechanical strength and conductivity of the gel electrolyte while giving it good fluidity, thus improving the charge-discharge performance and cycle life of the battery cells, especially the cycle performance of batteries with silicon-carbon anodes. When the molecular weight of component A is low, the degree of molecular entanglement after polymerization is relatively small. To improve the gel stability of the cured gel electrolyte, the amounts of components A and B can be appropriately increased, thereby increasing the solid content of the gel electrolyte within the aforementioned range. For example, when the number average molecular weight of component A is below 2000 Daltons, the solid content of the gel electrolyte can be increased to above 8%.

[0104] The solid content can be adjusted by changing the total weight ratio of component A and component B in the raw materials to the weight ratio of the electrolyte. In some embodiments, the total weight content of component A and component B in the electrolyte composition is 3%-15%.

[0105] The solid content of a gel electrolyte can be obtained by testing the ratio of the mass of the dried gel electrolyte to the mass of the gel electrolyte itself.

[0106] The electrolyte used in this application can be a conventional electrolyte in the art. In some embodiments, the electrolyte includes an electrolyte salt and a solvent.

[0107] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0108] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0109] In some embodiments, the electrolyte may optionally include additives. As examples, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0110] [Positive electrode plate]

[0111] A positive electrode typically includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0112] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0113] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0114] In some embodiments, the positive electrode active material may be a known positive electrode active material for batteries. As an example, when the battery cell is a lithium-ion battery cell, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNiO2). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0115] When the battery cell is a sodium-ion battery cell, as an example, the positive electrode active material of the sodium-ion battery cell may include at least one of the following materials: sodium transition metal oxide, polyanionic compound, and Prussian blue-like compound. However, this application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium-ion batteries may also be used.

[0116] As an optional technical solution in this application, the transition metal in the sodium transition metal oxide can be at least one selected from Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, the sodium transition metal oxide is Na. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x ≤ 1.

[0117] As an optional technical solution in this application, the polyanionic compound can be a compound containing sodium ions, transition metal ions, and tetrahedral structures. A class of compounds with an anionic unit. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents The price state.

[0118] Polyanionic compounds can also contain sodium ions, transition metal ions, or tetrahedral structures. A class of compounds containing anionic units and halide anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, where n represents... The valence state; the halogen can be at least one of F, Cl and Br.

[0119] Polyanionic compounds can also be those containing sodium ions or tetrahedral structures. Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, and n represents The valence state; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents (ZO) y ) m+ The valence state; the halogen can be at least one of F, Cl and Br.

[0120] Polyanionic compounds include, for example, NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F (where M' is one or more of V, Fe, Mn, and Ni) and At least one of (0≤y≤1).

[0121] Prussian blue compounds can be a class of compounds containing sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Examples of Prussian blue compounds include Na. a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0122] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0123] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0124] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0125] [Negative electrode plate]

[0126] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0127] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0128] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0129] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0130] In some embodiments, the negative electrode film layer may optionally include a binder. As an example, the binder may be selected from at least one 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).

[0131] In some embodiments, the negative electrode film may optionally include a conductive agent. As an example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0132] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0133] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0134] [Isolation membrane]

[0135] In some embodiments, the battery cell also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0136] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0137] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0138] In some implementations, a battery cell may include a battery cell, or a battery module and a battery pack.

[0139] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0140] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0141] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 The example shown is a square-structured battery cell 5.

[0142] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a top cover assembly 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can cover the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. The electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0143] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0144] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0145] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0146] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0147] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0148] In addition, this application also provides an electrical device, which includes the battery cell provided in this application. The battery cell can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0149] As an electrical device, you can choose individual battery cells, battery modules, or battery packs according to your usage requirements.

[0150] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of individual battery cells, a battery pack or battery module can be used. Example

[0151] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0152] The test formulations used in the examples are as follows: Example 1

[0153] Positive electrode preparation: The positive electrode active material, lithium nickel cobalt manganese oxide (LiNiO), is prepared... 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 98:1:1. N-methylpyrrolidone (NMP) solvent was added and stirred until the system was homogeneous, yielding a positive electrode slurry (70% solids content). The positive electrode slurry was then subjected to a reaction at approximately 12.5 mg / cm³. 2 The 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 rectangles of 40mm×50mm as positive electrode sheets.

[0154] Separation membrane: Polyethylene porous membrane is selected and cut into rectangles of 45mm × 55mm for later use.

[0155] Negative electrode preparation: A silicon-carbon composite material (silicon content 60% by mass), conductive agent acetylene black, dispersant carboxymethyl cellulose (CMC), and binder polyacrylic acid (PAA) are mixed in a mass ratio of 95:1:1:2. Water is added and stirred until the system is homogeneous to obtain a negative electrode slurry (solid content 60%). The negative electrode slurry is then mixed with approximately 2 mg / cm³ of water. 2 The loading is uniformly coated on one side of the negative electrode current collector copper foil, dried at room temperature, transferred to an oven for further drying, and then cut into rectangles of 41mm × 51mm as negative electrode sheets.

[0156] Preparation of gel electrolyte precursor solution:

[0157] The electrolyte composition consisted of a solvent made by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 4:2:4. The ratio of lithium salt LiFSI to solvent was 2.244 g:5 mL. Ethyl carbonate (VC) was used as an additive in the electrolyte, with a mass content of 0.5%. Polyether diol N230 (component A) was then added to a certain amount of the prepared electrolyte to form a mixture. This mixture was then combined with trifunctional isocyanate TUL-100 (component B) and DBTDL catalyst to form a gel electrolyte precursor solution. N230 and TUL-100 were combined at a molar ratio of -OH functional groups to isocyanate functional groups of 1:1.1. The DBTDL catalyst accounted for 0.5% of the total weight of N230 and TUL-100. After thorough stirring, a gel electrolyte precursor solution was formed. A portion of the gel electrolyte precursor solution was allowed to stand at 25°C for 24 h, and its viscosity was tested and recorded in Table 1. The molar ratios in Table 1 represent the molar ratios of -NH2 or -OH functional groups in component A to isocyanate functional groups in component B.

[0158] Secondary battery assembly: Take a cut positive electrode and match it with two cut negative electrodes. Use the above-mentioned separator to isolate the positive and negative electrodes to form a stacked electrode assembly. Place the stacked electrode assembly in the inner cavity of the shell and inject the prepared gel electrolyte precursor solution into it. After encapsulation, let it stand at 25°C for 24 hours, and then let it stand at 60°C for 24 hours to solidify, and obtain the corresponding gel electrolyte.

[0159] Secondary battery performance test:

[0160] Set the ambient temperature to 25. o C. The rechargeable battery prepared above is charged and discharged at a rate of 0.33C (23mA) and discharged at 0.33C for charge-discharge cycles. The cutoff voltages for charge and discharge are set to 4.2V and 3V, respectively. A constant current-constant voltage charging method is used during the charging process. Specifically, after the 0.33C constant current charging reaches the cutoff voltage of 4.2V, constant voltage charging at 4.2V is continued until the current decays to 0.1C (7mA). The battery life is considered to have ended when the discharge capacity decays to 80% of the first discharge capacity. Examples 2-6

[0161] The difference from Example 1 lies in the alteration of the types and contents of polyols and / or polyamines during the preparation of the gel electrolyte precursor solution, as detailed in Table 1. Furthermore, Examples 3 to 6 differ from Example 1 in that no catalyst is used.

[0162] Comparative Examples 1-5

[0163] The difference between Comparative Example 1 and Example 1 is that hexamethylene diisocyanate (HDI) was used to replace component B in Example 1 during the preparation of the gel electrolyte precursor solution, the amount of component B was adjusted, and an additional crosslinking agent was added, as detailed in Table 1. Similarly, Comparative Example 2, Comparative Example 3, and Comparative Example 4 are also compared to Example 4. The difference between Comparative Example 5 and Example 1 is that DL-8000D was used to replace component A in Example 1, and the amounts of components A and B were adjusted, as detailed in Table 1.

[0164] Table 1

[0165] As shown in Table 1, the viscosity of the gel electrolyte precursor solution is controllable and more uniform during the in-situ formation of gel electrolyte by combining polyols or polyamines with trifunctional isocyanates, meeting the viscosity requirements of the injection process. Because the gel electrolyte precursor solution used for injection has a suitable viscosity, it provides good wettability to the electrodes and separators in the electrode assembly after injection into the battery casing cavity. This effectively controls problems such as localized lithium plating during battery cell cycling, thereby extending the battery cell lifespan.

[0166] Specifically, based on the comparison of Examples 1-4 and Comparative Examples 1-4 in Table 1, it can be seen that the reaction degree of in-situ polymerization using HDI based on the examples is not easy to control. After standing for 24 hours, the viscosity increases significantly, making it difficult to inject liquid and unable to wet the electrode components, thus making it impossible to perform charge-discharge cycle tests.

[0167] As can be seen from the comparison of the embodiments and Comparative Example 5 in Table 1, using component A with a viscosity greater than that of this application results in an excessively high viscosity of the gel electrolyte, which cannot wet the electrode assembly and thus cannot perform charge-discharge cycle tests.

[0168] It should be noted that the lower cycle counts in Examples 2 and 5 are due to the fact that, in order to fully demonstrate the effect of changes in gel electrolyte viscosity on the battery, Examples 2 and 5 selected a higher solid content, which increased battery polarization in the later stages of cycling, leading to cycle degradation. However, compared to the comparison, they still achieved sufficient wetting of the electrode components.

[0169] The following examines the performance of different trifunctional isocyanates in the preparation of gel electrolytes and in secondary battery cycling tests. Examples 7-9

[0170] The only difference from Example 3 is that the type and content of trifunctional isocyanate are changed during the preparation of the gel electrolyte precursor solution, as shown in Table 2.

[0171] Table 2

[0172] As can be seen from the data in Table 2, when the trifunctional isocyanates that meet the viscosity requirements of this application are used as component B, they can effectively control the polymerization progress of components A and B, thereby controlling viscosity growth, ensuring smooth liquid injection, and achieving a good wetting effect on the electrode assembly. Examples 10-12

[0173] The only difference from Example 1 is that the type and content of the catalyst are changed during the preparation of the gel electrolyte precursor solution (the content in Table 3 is the percentage of the weight of the catalyst relative to the total weight of components A and B), as detailed in Table 3.

[0174] Table 3

[0175] As can be seen from the data in Table 3, as the catalyst content increases, the viscosity of the gel electrolyte precursor solution increases more rapidly, thus affecting the wetting of the electrode assembly and consequently impacting the improvement of the cycle performance. Examples 13-14

[0176] The only difference from Example 3 is that the ratio of component A and component B is adjusted to change the molar ratio of the -NH2 or -OH functional group in component A to the isocyanate functional group in component B (i.e., the molar ratio in Table 4), as shown in Table 4.

[0177] Table 4

[0178] It is evident that when the molar ratio is controlled within the range of 1:0.8 to 1:1.5, good cross-linking of components A and B can be achieved, while the viscosity of the gel electrolyte precursor solution can be effectively controlled, thereby improving the cycle performance of the battery. Example 15

[0179] The only difference from Example 3 is that the ratio of the total mass of component A and component B to the mass of electrolyte is adjusted, thereby adjusting the solid content of the gel electrolyte, as shown in Table 5. Example 16

[0180] The only difference from Example 5 is that the ratio of the total mass of component A and component B to the mass of electrolyte is adjusted, thereby adjusting the solid content of the gel electrolyte, as shown in Table 5.

[0181] Table 5

[0182] As can be seen from the data in Tables 1 and 5, when the amount of electrolyte is reduced, the viscosity of the gel electrolyte precursor solution increases significantly after standing for 24 hours, and the solid content of the electrolyte increases, which will affect the improvement effect on battery cycle performance. Examples 17-20

[0183] The only difference from Example 3 is that the standing conditions were changed during the preparation of the gel electrolyte precursor solution, as detailed in Table 6.

[0184] Table 6

[0185] As can be seen from the data in Table 6, extending the standing time at 60℃ is beneficial to improving the gel stability of the gel electrolyte, thereby improving the cycling performance.

[0186] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This 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 method for preparing a secondary battery, comprising: A gel electrolyte precursor solution is formed by prepolymerizing raw materials including an electrolyte, component A, and component B. Component A comprises polyols and / or polyamines, component B comprises trifunctional isocyanates, and the viscosity of component A is 1000. The viscosity of the trifunctional isocyanate is below 3000. the following; The gel electrolyte precursor solution is injected into the inner cavity of the housing, where it polymerizes to form the gel electrolyte. An electrode assembly is also provided in the inner cavity of the housing.

2. The preparation method according to claim 1, wherein, The viscosity of the gel electrolyte precursor solution before injection into the inner cavity of the shell is 3. Up to 50 The viscosity of the gel electrolyte precursor solution after being placed at 25°C for 24 hours is 5. Up to 25 .

3. The preparation method according to claim 1 or 2, wherein, The trifunctional isocyanate includes one or more of triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, and trifunctional isocyanate prepolymer.

4. The preparation method according to claim 3, wherein, The viscosity of the trifunctional isocyanate prepolymer is 30. Up to 2700 .

5. The preparation method according to claim 3 or 4, wherein, The trifunctional isocyanate prepolymer includes any one or more of the following: trifunctional isocyanate prepolymers formed by polymerizing triols and difunctional isocyanates, and trifunctional isocyanate prepolymers formed by polymerizing triamines and difunctional isocyanates.

6. The preparation method according to any one of claims 1 to 5, wherein, The polyol includes one or more of polyether polyols and polyester polyols; and / or the polyamine includes polyether polyamines.

7. The preparation method according to any one of claims 1 to 6, wherein, The polyol and polyamine each independently possess one or more of the following characteristics: Number-average molecular weight is 400 to 5000 Daltons; Viscosity 5 Up to 1000 ; The hydroxyl functionality of the polyol is ≥2; The amino functionality of the polyamine is ≥2.

8. The preparation method according to claim 7, wherein, The polyol and polyamine each independently possess one or more of the following characteristics: Number-average molecular weight is 2000 to 5000 Daltons; Viscosity 200 Up to 900 ; The hydroxyl functionality of the polyol is 2 or 3; The amino functionality of the polyamine is 2 or 3.

9. The preparation method according to any one of claims 1 to 8, wherein, The components A and B are mixed in a molar ratio of -NH2 or -OH functional groups in component A to isocyanate functional groups in component B of 1:(1.5-0.8).

10. The preparation method according to any one of claims 1 to 9, wherein, The raw materials also include catalysts, which include one or more of organotin catalysts, organobismuth catalysts, and organic base catalysts.

11. The preparation method according to claim 10, wherein, The catalyst comprises dibutyltin dilaurate and / or triethylenediamine.

12. The preparation method according to claim 10 or 11, wherein, The weight of the catalyst is 0.3%-3% of the total weight of component A and component B.

13. The preparation method according to any one of claims 1 to 12, wherein, The process of polymerizing the gel electrolyte precursor solution to form the gel electrolyte includes: After the shell containing the gel electrolyte precursor solution is encapsulated, it is left to stand at 20℃-30℃ for 12h-24h and at 45℃-60℃ for 12h-48h.

14. The preparation method according to any one of claims 1 to 13, wherein, The process of forming the gel electrolyte precursor solution includes: The component A and the electrolyte are mixed to form a mixture; The mixture is combined with component B and an optional catalyst and prepolymerized to form the gel electrolyte precursor solution.

15. The preparation method according to any one of claims 1 to 14, wherein, The solid content of the gel electrolyte is 3%-15%.

16. An electrolyte composition comprising an electrolyte, a component A, and a component B, wherein component A comprises a polyol and / or a polyamine, component B comprises a trifunctional isocyanate, and the viscosity of component A is 1000. The viscosity of the trifunctional isocyanate is below 3000. the following.

17. The electrolyte composition according to claim 16, wherein, The trifunctional isocyanate includes one or more of triphenylmethane triisocyanate, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, and trifunctional isocyanate prepolymer.

18. The electrolyte composition according to claim 17, wherein, The viscosity of the trifunctional isocyanate prepolymer is 30. Up to 2700 .

19. The electrolyte composition according to claim 17 or 18, wherein, The trifunctional isocyanate prepolymer includes any one or more of the following: trifunctional isocyanate prepolymers formed by polymerizing triols and difunctional isocyanates, and trifunctional isocyanate prepolymers formed by polymerizing triamines and difunctional isocyanates.

20. The electrolyte composition according to any one of claims 16 to 19, wherein, The polyol includes one or more of polyether polyols and polyester polyols; and / or the polyamine includes polyether polyamines.

21. The electrolyte composition according to any one of claims 16 to 20, wherein, The polyol and polyamine each independently possess one or more of the following characteristics: Number-average molecular weight is 400 to 5000 Daltons; Viscosity 5 Up to 1000 ; The hydroxyl functionality of the polyol is ≥2; The amino functionality of the polyamine is ≥2.

22. The electrolyte composition according to claim 20, wherein, The polyol and polyamine each independently possess one or more of the following characteristics: Number-average molecular weight is 2000 to 5000 Daltons; Viscosity 200 Up to 900 ; The hydroxyl functionality of the polyol is 2 or 3; The amino functionality of the polyamine is 2 or 3.

23. The electrolyte composition according to any one of claims 16 to 22, wherein, The components A and B are mixed in a molar ratio of -NH2 or -OH functional groups in component A to isocyanate functional groups in component B of 1:(1.5-0.8).

24. The electrolyte composition according to any one of claims 1 to 23, wherein, The electrolyte composition further includes a catalyst, which includes one or more of organotin catalysts, organobismuth catalysts, and organic base catalysts.

25. The electrolyte composition according to claim 24, wherein, The catalyst comprises dibutyltin dilaurate and / or triethylenediamine.

26. The electrolyte composition according to claim 24 or 25, wherein, The weight of the catalyst is 0.3%-0.5% of the total weight of component A and component B.

27. The electrolyte composition according to claim 22 or 23, wherein, In the electrolyte composition, the total weight content of component A and component B is 3%-15%.

28. A secondary battery, prepared by any one of the preparation methods described in claims 1 to 15.

29. An electrical appliance, wherein, Includes the battery cell as described in claim 28.

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