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

Abstract

The invention 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. The secondary battery comprises an outer package, an electrode assembly and a gel electrolyte, wherein the electrode assembly and the gel electrolyte are accommodated in the outer package; the gel electrolyte comprises a polymer, a solvent and an electrolyte salt; the polymer includes a copolymer of cyclophosphazene and ether oxygen segments. The secondary battery has a relatively long cycle life.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a secondary battery and its preparation method, gel electrolyte, and electrical device. Background Technology

[0002] With the increasing use of rechargeable batteries in electric vehicles, electric aviation, energy storage power systems, power tools, electric bicycles, electric motorcycles, military equipment and other fields, the public has also raised higher requirements for the performance and safety of rechargeable battery products.

[0003] Currently, most rechargeable batteries use liquid electrolytes. However, on the one hand, liquid electrolytes are prone to side reactions with the negative electrode of the rechargeable battery, leading to decreased battery performance and increased safety hazards; on the other hand, liquid electrolytes are prone to forming dendrites at the negative electrode during cycling, causing short circuits and, in severe cases, battery explosions. Liquid electrolytes are difficult to maintain stable long-term cycling in rechargeable batteries. Summary of the Invention

[0004] In view of the above problems, this application provides a secondary battery and its preparation method, gel electrolyte and power device to extend the cycle life of the secondary battery.

[0005] In a first aspect, this application provides a secondary battery, comprising: an outer packaging and an electrode assembly and a gel electrolyte contained within the outer packaging, wherein: the gel electrolyte comprises a polymer, a solvent and an electrolyte salt; the polymer comprises a copolymer of cyclophosphonitrile and ether oxygen segments.

[0006] The aforementioned secondary battery exhibits a long cycle life. This may be because the copolymer of cyclophosphonitrile and ether oxygen segments can anchor the solvent, preventing it from flowing to the negative electrode and coming into contact with it to cause side reactions.

[0007] In some embodiments, the cyclophosphonitrile includes one of a first functional group and a second functional group; the ether oxygen segment 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; and the second functional group includes an isocyanate group.

[0008] Therefore, the first and second functional groups can undergo polymerization under mild conditions to obtain copolymers.

[0009] In some embodiments, the molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1–3:2–4.

[0010] Using the above molar ratio can further extend the cycle life of the secondary battery. This may be because the above molar ratio facilitates the acquisition of copolymers with suitable three-dimensional network structures, which helps reduce the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0011] In some embodiments, the solid content of the gel electrolyte is 2% to 15%.

[0012] Setting the solid content of the gel electrolyte within the aforementioned range can further extend the cycle life of the secondary battery. This is likely because a lower solid content allows the gel electrolyte to exhibit better ionic conductivity, thus resulting in a longer cycle life for the secondary battery, while also maintaining good kinetic performance.

[0013] In some embodiments, the cyclophosphonitrile comprises the compound shown in Formula 1:

[0014]

[0015] In Formula 1, R1, R2, and R3 are each independently a C1-C20 alkylene, C1-C20 alkyleneoxy, or C1-C20 fluoroalkylene; M1, M2, and M3 are each independently one of the first functional group and the second functional group; R4, R5, and R6 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a hydroxyl-substituted C1-C5 alkyl chain, an amino-substituted C1-C5 alkyl chain, a C1-C5 fluoroalkyl chain, or a C1-C5 alkoxy chain; wherein, when any one of R4, R5, and R6 includes the first functional group, M1, M2, and M3 are each independently the first functional group; when any one of R4, R5, and R6 includes the second functional group, M1, M2, and M3 are each independently the second functional group.

[0016] In some embodiments, in Formula 1: R1, R2, and R3 are each independently methyleneoxy, butylene, or propylene; R4, R5, and R6 are each independently hydrogen, fluorine, or chlorine atoms.

[0017] In some embodiments, the compound represented by Formula 1 includes at least one of the following compounds:

[0018]

[0019] Using the aforementioned cyclophosphonitrile can further extend the cycle life of secondary batteries. This is likely because the cyclophosphonitrile has a cyclic structure composed of flame-retardant elements such as phosphorus (P) and nitrogen (N), which can provide excellent flame retardant properties and strength to the gel electrolyte, thereby extending the cycle life of the secondary battery.

[0020] In some embodiments, the ether oxygen segment comprises the compound shown in Formula 2:

[0021]

[0022] In Formula 2, n is a positive integer between 1 and 1000; X is a C1-C10 alkylene group; M4 and M5 are each the other of the first functional group and the second functional group.

[0023] In some embodiments, in Formula 2: n is a positive integer between 50 and 200; X is a C1-C5 alkylene group.

[0024] In some embodiments, the compound represented by Formula 2 includes at least one of the following compounds:

[0025]

[0026] Using the aforementioned ether-oxygen segments can further extend the cycle life of secondary batteries. This is likely because these ether-oxygen segments are soft segments, which can further improve the interfacial contact between the gel electrolyte and the positive and negative electrodes, thereby mitigating severe polarization caused by poor interfacial contact.

[0027] In some embodiments, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0028] The above-mentioned electrolyte salt has good compatibility with copolymers of cyclophosphonitrile and ether oxygen segments, making it suitable for almost all lithium secondary batteries and with a wide range of applications.

[0029] In some embodiments, the secondary battery is a lithium-ion battery, and the solvent includes ester solvents, which include one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, polycarbonate, ethyl formate, ethyl acetate, methyl acetate, fluoroethylene carbonate, difluoroethylene carbonate, methyl methyl fluorocarbonate, diethyl fluorocarbonate, ethyl fluoroformate, ethyl fluoroacetate, and methyl fluoroacetate.

[0030] In some embodiments, the secondary battery is a lithium-ion battery, and the gel electrolyte further includes additives, which include one or more of the following: ethylene carbonate, propane sulpholactone, vinyl sulfate, vinyl sulfite, tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilane) borate, dimethyl maleic anhydride, and butyl 1,4-diisocyanate.

[0031] The ester solvents and additives mentioned above have good compatibility with the copolymers of cyclophosphonitrile and ether oxygen segments, making them well applicable to lithium-ion batteries. This allows for the acquisition of lithium-ion batteries with long cycle life without significantly affecting other performance characteristics.

[0032] 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%.

[0033] By setting the electrolyte salt, ester solvent, and additives within the above range, lithium-ion batteries can be further made to have a longer cycle life.

[0034] In some embodiments, the secondary battery is a lithium metal battery, and the solvent includes ether solvents, specifically one or more of the following: diethyl ether, dipropyl ether, ethylpropyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxopentane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0035] In some embodiments, the secondary battery is a lithium metal battery, and the gel electrolyte further includes a diluent, which includes 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, and bis(2,2,2-trifluoroethyl) ether. One or more of the following: bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropylethyl 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, perfluoroisopropylmethyl 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.

[0036] The above-mentioned ether solvents and diluents have good compatibility with the copolymer of cyclophosphonitrile and ether oxygen segments, and can be well applied to lithium metal batteries. Under the premise of hardly affecting other performance, lithium metal batteries with long cycle life can be obtained.

[0037] 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%.

[0038] Setting the electrolyte salt, ether solvent, and diluent within the above range can further extend the cycle life of lithium metal batteries.

[0039] In a second aspect, this application provides a method for preparing the secondary battery described in the first aspect, comprising: mixing cyclophosphonitrile, ether oxygen segment, solvent and electrolyte salt to obtain a precursor solution; placing an electrode assembly in an outer packaging to obtain a dry cell; injecting the precursor solution into the dry cell and then sealing the outer packaging, and allowing the precursor solution to solidify in situ to obtain the secondary battery.

[0040] The method described in this application is simple, reliable, and highly reproducible, with broad prospects for industrial application, and the prepared secondary batteries have a longer cycle life.

[0041] In some embodiments, the in-situ curing temperature is 40°C to 80°C.

[0042] The above-mentioned in-situ curing temperature is conducive to the full progress of the polymerization reaction and has a high reaction efficiency.

[0043] In some embodiments, the molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1–3:2–4.

[0044] Using the above molar ratio can further extend the cycle life of the secondary battery. This may be because the above molar ratio facilitates the acquisition of copolymers with suitable three-dimensional network structures, which helps reduce the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0045] In some embodiments, the sum of the mass percentages of the cyclophosphonitrile and the ether oxygen segment is 2% to 15% based on the total mass of the precursor solution.

[0046] Using cyclophosphonitrile and ether oxygen segments within the aforementioned content range can further extend the cycle life of the secondary battery. This may be because the sum of the mass percentages of the cyclophosphonitrile and ether oxygen segments helps to mitigate the deterioration of the ionic conductivity of the gel electrolyte, thereby resulting in a longer cycle life for the secondary battery.

[0047] In some embodiments, the secondary battery is a lithium-ion battery and satisfies at least one of the following conditions: in the mixture of the solvent and the electrolyte salt, the concentration of the electrolyte salt is 1M to 3M; the precursor solution further includes 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 to 5:100.

[0048] Setting the concentration of electrolyte salts and / or the mass content of additives in lithium-ion batteries within the above-mentioned range is beneficial to the performance of lithium-ion batteries and can further improve their cycle life.

[0049] In some embodiments, the secondary battery is a lithium metal battery, and the precursor solution further includes a diluent, wherein the mass ratio of the electrolyte salt, the solvent and the diluent is 10-30:5-20:50-85.

[0050] Setting the mass ratio of electrolyte salt, solvent, and diluent in lithium metal batteries within the above-mentioned range is beneficial to the performance of lithium metal batteries and can further improve their cycle life.

[0051] Thirdly, this application provides a gel electrolyte comprising a polymer, a solvent, and an electrolyte salt; wherein the polymer comprises a copolymer of cyclophosphonitrile and ether oxygen segments.

[0052] The secondary battery using the aforementioned gel electrolyte exhibits a long cycle life. This may be because the copolymer of cyclophosphonitrile and ether oxygen segments can anchor the solvent, preventing it from flowing to the negative electrode and causing side reactions.

[0053] In some embodiments, the cyclophosphonitrile includes one of a first functional group and a second functional group, and the ether oxygen segment 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.

[0054] Therefore, the first and second functional groups can undergo polymerization under mild conditions to obtain copolymers.

[0055] In some embodiments, the molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1–3:2–4.

[0056] Using the above molar ratio can further extend the cycle life of the secondary battery. This may be because the above molar ratio facilitates the acquisition of copolymers with suitable three-dimensional network structures, which helps reduce the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0057] In some embodiments, the solid content of the gel electrolyte is 2% to 15%.

[0058] Setting the solid content of the gel electrolyte within the aforementioned range can further extend the cycle life of the secondary battery. This is likely because a lower solid content results in better ionic conductivity in the gel electrolyte, leading to a longer cycle life for the secondary battery, while also maintaining good kinetic performance.

[0059] In some embodiments, the cyclophosphonitrile comprises the compound shown in Formula 1:

[0060]

[0061] In Formula 1, R1, R2, and R3 are each independently a C1-C20 alkylene, C1-C20 alkyleneoxy, or C1-C20 fluoroalkylene; M1, M2, and M3 are each independently one of the first functional group and the second functional group; R4, R5, and R6 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a hydroxyl-substituted C1-C5 alkyl chain, an amino-substituted C1-C5 alkyl chain, a C1-C5 fluoroalkyl chain, or a C1-C5 alkoxy chain; wherein, when any one of R4, R5, and R6 includes the first functional group, M1, M2, and M3 are each independently the first functional group; when any one of R4, R5, and R6 includes the second functional group, M1, M2, and M3 are each independently the second functional group.

[0062] In some embodiments, in Formula 1: R1, R2, and R3 are each independently methyleneoxy, butylene, or propylene; R4, R5, and R6 are each independently hydrogen, fluorine, or chlorine atoms.

[0063] In some embodiments, the compound represented by Formula 1 includes at least one of the following compounds:

[0064]

[0065] Using the aforementioned cyclophosphonitrile can further extend the cycle life of secondary batteries. This is likely because the cyclophosphonitrile, with its cyclic structure composed of flame-retardant elements P and N, can provide excellent flame retardant properties and strength to the gel electrolyte, thereby extending the cycle life of the secondary battery.

[0066] In some embodiments, the ether oxygen segment comprises the compound shown in Formula 2:

[0067]

[0068] In Formula 2, n is a positive integer between 1 and 1000; X is a C1-C10 alkylene group; M4 and M5 are each the other of the first functional group and the second functional group.

[0069] In some embodiments, in Formula 2: n is a positive integer between 50 and 200; X is a C1-C5 alkylene group.

[0070] In some embodiments, the compound represented by Formula 2 includes at least one of the following compounds:

[0071]

[0072] Using the aforementioned ether-oxygen segments can further extend the cycle life of secondary batteries. This is likely because these ether-oxygen segments can further improve the interfacial contact between the gel electrolyte and the positive and negative electrodes, thereby mitigating severe polarization caused by poor interfacial contact.

[0073] Fourthly, this application provides an electrical device including the secondary battery described in the first aspect.

[0074] The electrical device of this application includes the secondary battery provided in this application, and therefore has at least the same advantages as the secondary battery, which will not be elaborated further here.

[0075] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0076] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0077] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of this application.

[0078] Figure 2 This is an exploded structural diagram of a battery cell according to an embodiment of this application.

[0079] Figure 3 This is a schematic diagram of the structure of a battery module according to an embodiment of this application.

[0080] Figure 4 This is a schematic diagram of the structure of a battery pack according to an embodiment of this application.

[0081] Figure 5 yes Figure 4 The diagram shows the exploded structure of the battery pack.

[0082] Figure 6This is a schematic diagram of the structure of an electrical device according to an embodiment of this application.

[0083] The accompanying drawings are not necessarily drawn to scale. The reference numerals are explained as follows: 1 Battery pack, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Individual battery cell, 51 Housing, 52 Electrode assembly, 53 Cover plate. Detailed Implementation

[0084] The secondary battery, its preparation method, gel electrolyte, and power application device of this application will be described in detail below with appropriate reference to the accompanying drawings. 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 to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0085] 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.

[0086] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0087] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0088] 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.

[0089] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0090] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: 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).

[0091] Unless otherwise specified, in this application, the terms "first," "second," "third," "fourth," "fifth," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0092] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0093] Throughout this specification, substituents of compounds are disclosed by groups or ranges. It is expressly intended that such description include each individual sub-combination of members of these groups and ranges. For example, it is expressly intended that the term "C1-C6 alkyl" individually discloses 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-C6 alkyl.

[0094] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0095] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0096] Unless otherwise stated, all ratio parameters involved in this application are compared under the condition that the units are the same. For example, if the ratio of the volumetric particle size distribution of A to B is 1:1, then the units of the volumetric particle size distribution of A and B are the same.

[0097] In this paper, ionic conductivity is mainly used to characterize the ability of a gel electrolyte composition to transport ions. It can reflect the ability of a gel electrolyte composition to transport ions and can be tested by any known method.

[0098] Currently, most rechargeable batteries use liquid electrolytes. On one hand, the unstable solvent and anions in the electrolyte salt in liquid electrolytes can easily contact the negative electrode interface of the rechargeable battery, causing side reactions that consume active lithium, leading to a decrease in the coulombic efficiency and cycle life of the rechargeable battery. On the other hand, liquid electrolytes are prone to forming dendrites at the negative electrode during cycling, leading to short circuits in the rechargeable battery, and in severe cases, battery explosions. All of these problems reduce the cycle life of rechargeable batteries.

[0099] To extend the cycle life of secondary batteries, this application proposes using a gel electrolyte comprising a copolymer of cyclophosphonitrile and ether oxygen segments, a solvent, and an electrolyte salt. This may be because the copolymer of cyclophosphonitrile and ether oxygen segments can anchor the solvent, preventing it from flowing to the negative electrode and causing side reactions.

[0100] In the embodiments of this application, the secondary battery refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the secondary battery mentioned in this application may include battery cells, battery modules, or battery packs.

[0101] A battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. A battery cell can be cylindrical, flat, cuboid, or other shapes, etc., and the embodiments of this application are not limited in this respect. Figure 1 The example shown is a rectangular battery cell 5.

[0102] When there are multiple battery cells, they are connected in series, parallel, or mixed via a busbar. In some embodiments, the secondary battery can be a battery module; when there are multiple battery cells, they are arranged and fixed to form a battery module. In some embodiments, the secondary battery can be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed within the housing. In some embodiments, the housing can be part of the vehicle's chassis structure. For example, a portion of the housing can be at least part of the vehicle's floor, or a portion of the housing can be at least part of the vehicle's crossbeams and longitudinal beams.

[0103] In some embodiments, the secondary battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0104] The battery cells mentioned in the embodiments of this application include lithium-ion secondary battery cells, lithium metal secondary battery cells, etc., but the embodiments of this application are not limited to this.

[0105] A single battery cell generally includes an electrode assembly. The electrode assembly typically includes a positive electrode, a negative electrode, and a separator between the positive and negative electrode. The electrode assembly can be a wound structure or a stacked structure, and the embodiments of this application are not limited to this.

[0106] The battery cell may also include an outer packaging, which can be used to encapsulate the aforementioned electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0107] In some embodiments, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted as needed.

[0108] In some embodiments, individual battery cells can be assembled into a battery module, and the number of individual battery cells contained in the battery module can be multiple, the specific number of which can be adjusted according to the application and capacity of the battery module. Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3As shown, 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.

[0109] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0110] 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 adjusted according to the application and capacity of the battery pack.

[0111] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3. The upper housing 2 covers the lower housing 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the housing.

[0112] [Rechargeable Battery]

[0113] According to some embodiments of this application, this application provides a secondary battery, including: an outer packaging and an electrode assembly and a gel electrolyte contained in the outer packaging, wherein: the gel electrolyte includes a polymer, a solvent and an electrolyte salt; the polymer includes a copolymer of cyclophosphonitrile and ether oxygen segments.

[0114] It is understood that an electrode assembly typically includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode. Specifically, it can be a stacked electrode assembly or a wound electrode assembly.

[0115] The gel electrolyte can be disposed on at least one of the negative electrode, positive electrode, and separator.

[0116] The aforementioned secondary battery exhibits a long cycle life. This may be because the copolymer of cyclophosphonitrile and ether oxygen segments can anchor the solvent, preventing it from flowing to the negative electrode and coming into contact with it to cause side reactions.

[0117] According to some embodiments of this application, the cyclophosphonitrile includes one of a first functional group and a second functional group; the ether oxygen segment 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; and the second functional group includes an isocyanate group.

[0118] The first and second functional groups can react to polymerize the cyclophosphonitrile and the ether oxygen segment. Specifically, hydroxyl and / or amino groups can react with isocyanate groups, for example, hydroxyl reacts with isocyanate groups, or amino reacts with isocyanate groups, or both hydroxyl and amino groups react with isocyanate groups. To ensure successful polymerization, neither the cyclophosphonitrile nor the ether oxygen segment can simultaneously contain the first and second functional groups. The statement "the cyclophosphonitrile contains one of the first and second functional groups; the ether oxygen segment contains the other of the first and second functional groups" means that if the cyclophosphonitrile contains the first functional group, then the ether oxygen segment contains the second functional group; if the cyclophosphonitrile contains the second functional group, then the ether oxygen segment contains the first functional group.

[0119] Therefore, the first and second functional groups can undergo polymerization under mild conditions to obtain copolymers.

[0120] According to some embodiments of this application, the molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1-3:2-4.

[0121] For example, the molar ratio of cyclophosphonitrile to ether oxygen segments can be 1:2, 1:3, 1:4, 2:2, 2:3, 2:4, 3:2, 3:3, 3:4, or any of the above values ​​within any range.

[0122] Using the above molar ratio can further extend the cycle life of the secondary battery. This may be because the above molar ratio facilitates the acquisition of copolymers with suitable three-dimensional network structures, which helps reduce the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0123] According to some embodiments of this application, the solid content of the gel electrolyte is 2% to 15%.

[0124] The term "solid content" refers to the mass percentage of the polymer (a copolymer of cyclophosphonitrile and ether oxygen segments) in the gel electrolyte.

[0125] 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 any range of the above values.

[0126] Setting the solid content of the gel electrolyte within the aforementioned range can further extend the cycle life of the secondary battery. This is likely because a lower solid content allows the gel electrolyte to exhibit better ionic conductivity, thus resulting in a longer cycle life for the secondary battery, while also maintaining good kinetic performance.

[0127] According to some embodiments of this application, the cyclophosphonitrile includes compounds of Formula 1:

[0128]

[0129] In Formula 1, R1, R2, and R3 are each independently a C1-C20 alkylene, C1-C20 alkyleneoxy, or C1-C20 fluoroalkylene; M1, M2, and M3 are each independently one of the first functional group and the second functional group; R4, R5, and R6 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a hydroxyl-substituted C1-C5 alkyl chain, an amino-substituted C1-C5 alkyl chain, a C1-C5 fluoroalkyl chain, or a C1-C5 alkoxy chain; wherein, when any one of R4, R5, and R6 includes the first functional group, M1, M2, and M3 are each independently the first functional group; when any one of R4, R5, and R6 includes the second functional group, M1, M2, and M3 are each independently the second functional group.

[0130] According to some embodiments of this application, in Formula 1: R1, R2, and R3 are each independently methyleneoxy, butylene, or propylene; R4, R5, and R6 are each independently hydrogen, fluorine, or chlorine atoms.

[0131] According to some embodiments of this application, the compound shown in Formula 1 includes at least one of the following compounds:

[0132]

[0133] Using the aforementioned cyclophosphonitrile can further extend the cycle life of secondary batteries. This is likely because the cyclophosphonitrile has a cyclic structure composed of flame-retardant elements such as phosphorus (P) and nitrogen (N), which can provide excellent flame retardant properties and strength to the gel electrolyte, thereby extending the cycle life of the secondary battery.

[0134] According to some embodiments of this application, the ether oxygen segment includes the compound shown in Formula 2:

[0135]

[0136] In Formula 2, n is a positive integer between 1 and 1000; X is a C1-C10 alkylene group; M4 and M5 are each the other of the first functional group and the second functional group.

[0137] "M4 and M5 are each independently the other of the first functional group and the second functional group" means that if cyclophosphonitrile includes the first functional group, then M4 and M5 are each independently the second functional group; if cyclophosphonitrile includes the second functional group, then M4 and M5 are each independently the first functional group.

[0138] According to some embodiments of this application, in Formula 2: n is a positive integer between 50 and 200; X is a C1-C5 alkylene group.

[0139] According to some embodiments of this application, the compound shown in Formula 2 includes at least one of the following compounds:

[0140]

[0141] Using the aforementioned ether-oxygen segments can further extend the cycle life of secondary batteries. This is likely because these ether-oxygen segments can further improve the interfacial contact between the gel electrolyte and the positive and negative electrodes, thereby mitigating severe polarization caused by poor interfacial contact.

[0142] According to some embodiments of this application, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0143] The above-mentioned electrolyte salt has good compatibility with copolymers of cyclophosphonitrile and ether oxygen segments, making it suitable for almost all lithium secondary batteries and with a wide range of applications.

[0144] It is understandable that different types of lithium batteries have different requirements for electrolytes in order to achieve better electrochemical performance. Therefore, different electrolytes often need to be developed for different types of lithium batteries. For example, in lithium-ion batteries, ester solvent systems are more conducive to the performance of the electrolyte, while in lithium metal batteries, ether solvent systems are more conducive to the performance of the electrolyte. In order to meet the above-mentioned usage requirements, the gel electrolyte in the embodiments of this application takes into account the applicability of different solvent systems. The copolymer used has good compatibility and synergistic effects with both ester and ether solvents, and can be widely used in different types of lithium batteries.

[0145] According to some embodiments of this application, the secondary battery is a lithium-ion battery, and the solvent includes ester solvents, which include 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, methyl ethyl fluorocarbonate, diethyl fluorocarbonate, ethyl fluorocarbonate, ethyl fluoroformate, ethyl fluoroacetate, and methyl fluoroacetate.

[0146] According to some embodiments of this application, the secondary battery is a lithium-ion battery, and the gel electrolyte further includes additives, which include one or more of the following: ethylene carbonate, propane sulpholactone, vinyl sulfate, vinyl sulfite, tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilane) borate, dimethyl maleic anhydride, and butyl 1,4-diisocyanate.

[0147] Because the operating voltage of a secondary battery is much higher than the decomposition voltage of water, organic solvents are often used as the electrolyte in a secondary battery. Lithium-ion secondary batteries primarily rely on lithium ions (Li... + It works by moving between the positive and negative electrodes. During charging and discharging, Li... + Intercalation and deintercalation back and forth between the two electrodes: During charging, Li + Lithium ions are extracted from the positive electrode, inserted into the negative electrode via the electrolyte, and the negative electrode is in a lithium-rich state; the process is reversed during discharge. The electrolyte in a lithium-ion secondary battery typically includes lithium salts, organic solvents, and additives. Lithium salts ensure a sufficient number of lithium ions travel between the positive and negative electrodes during charge-discharge cycles, enabling reversible cycling. Organic solvents act as carriers for lithium ions and form the main component of the electrolyte. Additives improve the stability and electrochemical performance of the electrolyte. Ester solvents possess advantages such as high dielectric constant, strong dissolving power for lithium salts, low melting point, high boiling point, low viscosity (facilitating lithium ion transport), good chemical stability, good safety, and low cost. Using organic solvents in lithium-ion battery electrolytes can effectively enhance the electrical performance of lithium-ion batteries.

[0148] The ester solvents and additives mentioned above have good compatibility with copolymers of cyclophosphonitrile and ether oxygen segments, making them well-suited for lithium-ion batteries. This allows for the production of lithium-ion batteries with long cycle life without significantly affecting other performance characteristics.

[0149] According to some embodiments of this 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%.

[0150] The content of electrolyte salts in the gel electrolyte is 8% to 15%. For example, the content of electrolyte salts in the gel electrolyte can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any range of the above values.

[0151] The content of ester solvent in the gel electrolyte is 80% to 90%. For example, the content of ester solvent in the gel electrolyte can be 80%, 82%, 84%, 86%, 88%, 90%, or any range of the above values.

[0152] The additive content in the gel electrolyte is 0.2% to 5%. For example, the additive content in the gel electrolyte can be 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range of the above values.

[0153] By setting the electrolyte salt, ester solvent, and additives within the above range, lithium-ion batteries can be further made to have a longer cycle life.

[0154] According to some embodiments of this application, the secondary battery is a lithium metal battery, and the solvent includes ether solvents, specifically one or more of the following: diethyl ether, dipropyl ether, ethylpropyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxopentane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0155] According to some embodiments of this application, the secondary battery is a lithium metal battery, and the gel electrolyte further includes a diluent, which includes 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) One or more of the following: ether, bis(2,2-difluoroethyl) ether, 1,1,2,3,3,3-hexafluoropropylethyl 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, perfluoroisopropylmethyl 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.

[0156] A lithium metal secondary battery is a type of secondary battery that uses lithium metal as the negative electrode material. During charging, Li... + The lithium metal migrates to the interface between the lithium metal anode and the electrolyte and deposits there; during discharge, the lithium metal loses electrons at the interface and becomes Li. + However, lithium dissolves into the electrolyte. Consequently, during charge and discharge, some lithium undergoes irreversible deposition / stripping, losing its activity and becoming "lithium dendrites." Using ether solvents can improve lithium dendrite growth, thereby enhancing the coulombic efficiency and cycle performance of lithium metal secondary batteries.

[0157] Using ether solvents and diluents within the above range, copolymers of cyclophosphonitrile and ether oxygen segments have good compatibility and can be well applied to lithium metal batteries, obtaining lithium metal batteries with long cycle life with almost no impact on other performance.

[0158] According to some embodiments of this 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%.

[0159] The content of electrolyte salt in the gel electrolyte is 12% to 20%. For example, the content of electrolyte salt in the gel electrolyte can be 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or any range of the above values.

[0160] The content of ether solvents in the gel electrolyte is 8% to 15%. For example, the content of ether solvents in the gel electrolyte can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any range of the above values.

[0161] The diluent content in the gel electrolyte is 60% to 75%. For example, the diluent content in the gel electrolyte can be 60%, 63%, 66%, 69%, 70%, 72%, 75%, or any range of the above values.

[0162] Setting the electrolyte salt, ether solvent, and diluent within the above range can further extend the cycle life of lithium metal batteries.

[0163] It is understood that an electrode assembly typically includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode. Specifically, it can be a stacked electrode assembly or a wound electrode assembly.

[0164] The positive electrode 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 active material. 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.

[0165] Positive electrode active materials include, but are not limited to, lithium transition metal oxides and / or lithium-containing phosphates with olivine structures.

[0166] In some embodiments, the positive electrode active material comprises 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), and lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) or combinations thereof.

[0167] In some embodiments, the positive electrode active material comprises a lithium phosphate with an olivine structure. Optionally, it includes, but is not limited to, lithium iron phosphate (e.g., LiFePO4), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composites, and lithium manganese iron phosphate (e.g., LiMn...). x Fe 1-x At least one of PO4 (0 < x < 1) and a composite material of lithium manganese iron phosphate and carbon.

[0168] The positive electrode film may also include a conductive agent. As an example, the positive electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and the embodiments of this application are not limited thereto.

[0169] The positive electrode film layer may also include a binder to firmly bond the positive electrode active material and the conductive agent to the positive electrode current collector. The binder may 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).

[0170] The positive electrode film may also include functional additives, which may include one or more of the following: dispersants, plasticizers, pore-forming agents, dehydrating additives, deacidifying additives, and lithium supplementing agents.

[0171] The dispersant may include an abc type block copolymer, wherein block A includes polyvinylpyrrolidone, block B includes polyacrylic acid, and block C includes one or more of the following: polytetrahydrofuran chain, polyethylene oxide chain, polyethylene glycol chain, polypropylene glycol chain, and polypropylene triol chain. Optionally, the ratio of the average degree of polymerization of block A to block B is greater than 10:1. Optionally, the ratio of the average degree of polymerization of block A to block C is (0.1-10):1. Optionally, the weight-average molecular weight of the dispersant is from 2,000 to 100,000.

[0172] Plasticizers may include one or more of the following: strong solvent type (PP-SS) plasticizer, low temperature resistant type (PP-LT) plasticizer, low volatility type (PP-LV) plasticizer, low diffusion type (SP-LD) plasticizer, heat stable type (SP-Stab) plasticizer, and flame retardant type (SP-FR) plasticizer.

[0173] Strong solvent-based (PP-SS) plasticizers can provide strong plasticizing properties, and may include phthalates and non-phthalates (such as benzoates, tricresyl phosphate, etc.).

[0174] Low-temperature resistant (PP-LT) plasticizers can also provide good low-temperature resistance, for example, they may include aliphatic diesters.

[0175] Low-volatility (PP-LV) plasticizers also have lower volatility and may include, for example, trimellitates and polyesters.

[0176] Low-diffusion (SP-LD) plasticizers also have lower diffusion properties, and may include, for example, polyesters.

[0177] Heat-stabilized (SP-Stab) plasticizers also have heat-stabilizing properties, and may include, for example, epoxy compounds.

[0178] Flame-retardant (SP-FR) plasticizers also have flame-retardant properties, and may include, for example, phosphate esters and halogenated hydrocarbons.

[0179] Lithium supplements may include one or more of lithium-rich oxides (such as Li2NiO2, Li5FeO4, etc.), nanocomposites and binary lithium compounds. Optionally, the number of Li atoms in the molecular formula of the lithium supplement may be ≥1.5.

[0180] The positive electrode current collector can be a metal foil or a composite current collector. For example, aluminum foil can 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 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0181] The positive electrode sheet does not exclude other additional functional layers besides the positive electrode film layer. For example, in some embodiments, the positive electrode sheet may also include a functional coating, which may be located between the positive current collector and the positive electrode film layer and / or on the surface of the positive electrode film layer facing away from the positive current collector. As an example, the functional coating may include one or more of conductive carbon, dehydrating additives, deacidifying additives, and lithium replenishing agents, and the embodiments of this application are not limited thereto.

[0182] It is understandable that the above-mentioned positive electrode sheet is suitable for both lithium-ion batteries and lithium metal batteries.

[0183] 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.

[0184] Depending on the type of secondary battery, different structures and negative electrode materials can be selected for the negative electrode sheet.

[0185] Taking a lithium-ion battery as an example, 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. As an example, the negative 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 current collector.

[0186] The negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can 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 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0187] The negative electrode active material may include one or more of carbon-based materials, silicon-based materials, tin-based materials, and lithium titanate. Carbon-based materials may include one or more of graphite (e.g., artificial graphite, natural graphite, etc.), soft carbon, and hard carbon. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys.

[0188] The negative electrode film layer may include a negative electrode binder. As an example, the negative electrode binder may 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), and the embodiments of this application are not limited thereto.

[0189] The negative electrode film layer may also include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, and the embodiments of this application are not limited thereto.

[0190] The negative electrode film may also include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC)).

[0191] The negative electrode sheet does not exclude additional functional layers besides the negative electrode film layer. In some embodiments, the negative electrode sheet may also include a functional coating, which may 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 may include carbon.

[0192] The negative electrode film may also include a lithium replenishing material. Optionally, the lithium replenishing material includes one or more of lithium foil, lithium strip, lithium powder, and pre-lithiation reagent. Optionally, the pre-lithiation reagent may include one or more of Li-aromatic hydrocarbons, complexes of Li-aromatic hydrocarbons and ether solvents, and may be selected as one or more of lithium naphthalene and lithium biphenyl dimethyl ether (DME).

[0193] The negative electrode sheet may include a negative current collector and a first negative electrode film layer and a second negative electrode film layer respectively disposed on two surfaces of the negative current collector. The composition of the first negative electrode film layer and the second negative electrode film layer may be the same or different; the thickness of the first negative electrode film layer and the second negative electrode film layer may be the same or different.

[0194] 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, negative electrode conductive agent, 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 onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0195] In some embodiments, the negative electrode may not include a negative electrode active material capable of lithium ion intercalation / deintercalation. For example, the negative electrode may include a lithium sheet or a lithium alloy sheet, wherein the lithium alloy sheet is an alloy of lithium with various other metals or non-metals, optionally 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 may include a mesh or foam-like three-dimensional framework layer; or, the negative electrode may include a negative current collector and a lithium-containing layer disposed on at least one surface of the negative current collector.

[0196] Taking lithium metal batteries as an example, the negative electrode is lithium metal. In some embodiments, lithium metal foil can be placed on the negative electrode current collector (such as copper foil) to form a negative electrode sheet.

[0197] The secondary battery also includes a separator. This application does not impose any particular restriction on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0198] In some embodiments, the separator includes a porous substrate. The porous substrate may be made of at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, polyester, and polyimide. The porous substrate can be a single-layer film or a multi-layer composite film, without particular limitation. When the porous substrate is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0199] In some embodiments, the separator may further include a coating on at least one surface of the porous substrate. Optionally, the coating may include one or more of inorganic heat-resistant particles and organic heat-resistant particles.

[0200] [Preparation methods for secondary batteries]

[0201] According to some embodiments of this application, this application also provides a method for preparing a secondary battery according to any of the above schemes, comprising: mixing cyclophosphonitrile, ether oxygen segment, solvent and electrolyte salt to obtain a precursor solution; placing an electrode assembly in an outer packaging to obtain a dry cell; injecting the precursor solution into the dry cell and then sealing the outer packaging, and allowing the precursor solution to solidify in situ to obtain the secondary battery.

[0202] There are no restrictions on the order in which cyclophosphonitrile, ether oxygen segments, solvent, and electrolyte salt are mixed when preparing the precursor solution. Specifically, the solvent and electrolyte salt can be mixed first to form a solution, and then the solution can be mixed with cyclophosphonitrile and ether oxygen segments to form the precursor solution.

[0203] When preparing a secondary battery, the order of "mixing cyclophosphonitrile, ether oxygen segments, solvent and electrolyte salt to obtain a precursor solution" and "placing the electrode assembly in the outer packaging to obtain a dry cell" is not important.

[0204] It is understood that electrode assemblies typically include a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode. They can be prepared by a lamination process or a winding process. This application does not have any particular limitations, and the specific operations can be carried out with reference to conventional techniques, which will not be elaborated here.

[0205] The method described in this application is simple, reliable, and highly reproducible, with broad prospects for industrial application, and the prepared secondary batteries have a longer cycle life.

[0206] According to some embodiments of this application, the in-situ curing temperature is 40°C to 80°C.

[0207] For example, the in-situ curing temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, or any range of the above values.

[0208] The above-mentioned in-situ curing temperature is conducive to the full progress of the polymerization reaction and has a high reaction efficiency.

[0209] According to some embodiments of this application, the molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1-3:2-4.

[0210] The molar ratio of cyclophosphonitrile to ether oxygen segment is 1 to 3: 2 to 4. For example, the molar ratio of cyclophosphonitrile to ether oxygen segment can be 1:2, 1:3, 1:4, 2:2, 2:3, 2:4, 3:2, 3:3, 3:4, or any range of the above values.

[0211] Using the above molar ratio can further extend the cycle life of the secondary battery. This may be because the above molar ratio facilitates the acquisition of copolymers with suitable three-dimensional network structures, which helps reduce the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0212] According to some embodiments of this application, based on the total mass of the precursor solution, the sum of the mass percentages of the cyclophosphonitrile and the ether oxygen segment is 2% to 15%.

[0213] The sum of the mass percentages of cyclophosphonitrile and ether oxygen segments is 2% to 15%. For example, the sum of the mass percentages of cyclophosphonitrile and ether oxygen segments can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any range of the above values.

[0214] Using cyclophosphonitrile and ether oxygen segments within the aforementioned content range can further extend the cycle life of the secondary battery. This may be because the sum of the mass percentages of the cyclophosphonitrile and ether oxygen segments helps to mitigate the deterioration of the ionic conductivity of the gel electrolyte, thereby resulting in a longer cycle life for the secondary battery.

[0215] According to some embodiments of this application, the secondary battery is a lithium-ion battery and satisfies at least one of the following conditions: in the mixture of the solvent and the electrolyte salt, the concentration of the electrolyte salt is 1M to 3M; the precursor solution further includes 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 to 5:100.

[0216] The concentration of the electrolyte salt is 1M to 3M. For example, the concentration of the electrolyte salt can be 1M, 2M, 3M, or any range of the above values.

[0217] The additives can be the same as described above, and will not be repeated here.

[0218] The ratio of the mass of the additive to the sum of the masses of the solvent and the electrolyte salt is 0.5 to 5:100. For example, the ratio of the mass of the additive to the sum of the masses 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 any range of the above values.

[0219] Setting the concentration of electrolyte salts and / or the mass content of additives in lithium-ion batteries within the above-mentioned range is beneficial to the performance of lithium-ion batteries and can further improve their cycle life.

[0220] According to some embodiments of this application, the secondary battery is a lithium metal battery, and the precursor solution further includes a diluent, wherein the mass ratio of the electrolyte salt, the solvent and the diluent is 10-30:5-20:50-85.

[0221] The diluent can be the same as described above, and will not be repeated here.

[0222] The mass ratio of electrolyte salt, solvent, and diluent is 10–30:5–20:50–85. For example, the mass ratio of electrolyte salt, solvent, and diluent can be 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 any range of the above values.

[0223] Setting the mass ratio of electrolyte salt, solvent, and diluent in lithium metal batteries within the above-mentioned range is beneficial to the performance of lithium metal batteries and can further improve their cycle life.

[0224] [Gel Electrolyte]

[0225] According to some embodiments of this application, this application also provides a gel electrolyte, comprising a polymer, a solvent, and an electrolyte salt; wherein the polymer comprises a copolymer of cyclophosphonitrile and ether oxygen segments.

[0226] The secondary battery using the aforementioned gel electrolyte exhibits a long cycle life. This may be because the copolymer of cyclophosphonitrile and ether oxygen segments can anchor the solvent, preventing it from flowing to the negative electrode and causing side reactions.

[0227] According to some embodiments of this application, the cyclophosphonitrile includes one of a first functional group and a second functional group, and the ether oxygen segment includes the other of the first functional group and the second functional group; the first functional group includes at least one of hydroxyl and amino groups; and the second functional group includes an isocyanate group.

[0228] The first and second functional groups can react to polymerize the cyclophosphonitrile and the ether oxygen segment. Specifically, hydroxyl and / or amino groups can react with isocyanate groups, for example, hydroxyl reacts with isocyanate groups, or amino reacts with isocyanate groups, or both hydroxyl and amino groups react with isocyanate groups. To ensure successful polymerization, neither the cyclophosphonitrile nor the ether oxygen segment can simultaneously contain the first and second functional groups. The statement "the cyclophosphonitrile contains one of the first and second functional groups; the ether oxygen segment contains the other of the first and second functional groups" means that if the cyclophosphonitrile contains the first functional group, then the ether oxygen segment contains the second functional group; if the cyclophosphonitrile contains the second functional group, then the ether oxygen segment contains the first functional group.

[0229] Therefore, the first and second functional groups can undergo polymerization under mild conditions to obtain copolymers.

[0230] According to some embodiments of this application, the molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1-3:2-4.

[0231] For example, the molar ratio of cyclophosphonitrile to ether oxygen segments can be 1:2, 1:3, 1:4, 2:2, 2:3, 2:4, 3:2, 3:3, 3:4, or any of the above values ​​within any range.

[0232] Using the above molar ratio can further extend the cycle life of the secondary battery. This may be because the above molar ratio facilitates the acquisition of copolymers with suitable three-dimensional network structures, which helps reduce the solid content of the gel electrolyte, thereby improving the cycle life of the secondary battery.

[0233] According to some embodiments of this application, the solid content of the gel electrolyte is 2% to 15%.

[0234] 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 any range of the above values.

[0235] Setting the solid content of the gel electrolyte within the aforementioned range can further extend the cycle life of the secondary battery. This is likely because a lower solid content results in better ionic conductivity of the gel electrolyte, leading to a longer cycle life for the secondary battery, while also maintaining good kinetic performance.

[0236] According to some embodiments of this application, the cyclophosphonitrile includes compounds of Formula 1:

[0237]

[0238] In Formula 1, R1, R2, and R3 are each independently a C1-C20 alkylene, C1-C20 alkyleneoxy, or C1-C20 fluoroalkylene; M1, M2, and M3 are each independently one of the first functional group and the second functional group; R4, R5, and R6 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a hydroxyl-substituted C1-C5 alkyl chain, an amino-substituted C1-C5 alkyl chain, a C1-C5 fluoroalkyl chain, or a C1-C5 alkoxy chain; wherein, when any one of R4, R5, and R6 includes the first functional group, M1, M2, and M3 are each independently the first functional group; when any one of R4, R5, and R6 includes the second functional group, M1, M2, and M3 are each independently the second functional group.

[0239] According to some embodiments of this application, in Formula 1: R1, R2, and R3 are each independently methyleneoxy, butylene, or propylene; R4, R5, and R6 are each independently hydrogen, fluorine, or chlorine atoms.

[0240] According to some embodiments of this application, the compound shown in Formula 1 includes at least one of the following compounds:

[0241]

[0242] Using the aforementioned cyclophosphonitrile can further extend the cycle life of secondary batteries. This is likely because the cyclophosphonitrile, with its cyclic structure composed of flame-retardant elements P and N, can provide excellent flame retardant properties and strength to the gel electrolyte, thereby extending the cycle life of the secondary battery.

[0243] According to some embodiments of this application, the ether oxygen segment includes the compound shown in Formula 2:

[0244]

[0245] In Formula 2, n is a positive integer between 1 and 1000; X is a C1-C10 alkylene group; M4 and M5 are each the other of the first functional group and the second functional group.

[0246] According to some embodiments of this application, in Formula 2: n is a positive integer between 50 and 200; X is a C1-C5 alkylene group.

[0247] According to some embodiments of this application, the compound shown in Formula 2 includes at least one of the following compounds:

[0248]

[0249] Using the aforementioned ether-oxygen segments can further extend the cycle life of secondary batteries. This is likely because these ether-oxygen segments can further improve the interfacial contact between the gel electrolyte and the positive and negative electrodes, thereby mitigating severe polarization caused by poor interfacial contact.

[0250] The solvent and electrolyte salt in gel electrolytes can be the same as described above, and will not be repeated here.

[0251] [Electrical appliances]

[0252] According to some embodiments of this application, this application also provides an electrical device, which includes the secondary battery provided in this application. The secondary battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., 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.

[0253] As an electrical device, a rechargeable battery can be selected based on its usage requirements.

[0254] 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 device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0255] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0256] Example

[0257] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0258] The lithium-ion batteries of Examples 1-24 and Comparative Example 1 were all prepared according to the following method.

[0259] Preparation of positive electrode sheet

[0260] Lithium nickel cobalt manganese oxide (LiNi) is used as the positive electrode active material. 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% solid content). The positive electrode slurry was then subjected to a reaction at approximately 12.5 mg / cm³. 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.

[0261] Preparation of negative electrode sheet

[0262] 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.

[0263] Preparation of gel electrolyte precursor solution

[0264] Mix the electrolyte salts, ester solvents, and additives from Table 1 to form a solution;

[0265] Mix the cyclophosphonitrile, ether oxygen segment, and solution shown in Table 5, and stir thoroughly to form a precursor solution.

[0266] Separating membrane

[0267] Polyethylene porous membrane was selected and cut into rectangles of 45mm × 55mm.

[0268] Preparation of lithium-ion batteries

[0269] 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 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 70°C for 12 hours to allow the precursor liquid to solidify in situ, forming a gel electrolyte, thus obtaining a lithium-ion battery with a rated capacity of 70mAh.

[0270] Comparative Example 1

[0271] The preparation method of the lithium-ion battery is the same as that in Example 1, except for the gel electrolyte.

[0272] The solutions shown in Table 3 are used as electrolytes for lithium-ion batteries.

[0273] The lithium metal batteries of Examples 25-48 and Comparative Example 2 were all prepared according to the following method.

[0274] Preparation of positive electrode sheet

[0275] Lithium nickel cobalt manganese oxide (LiNi) is used as the positive electrode active material. 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% solid 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 40mm×50mm rectangles as positive electrode sheets.

[0276] Preparation of negative electrode sheet

[0277] A 50μm thick lithium foil is rolled onto a 12μm thick copper foil and then cut into a 41mm×51mm rectangle as the negative electrode.

[0278] Preparation of gel electrolyte precursor solution

[0279] Mix the electrolyte salts, ether solvents, and diluents from Table 2 to obtain a solution;

[0280] Mix the cyclophosphonitrile, ether oxygen segment, and solution shown in Table 6, and stir thoroughly to form a precursor solution.

[0281] Separating membrane

[0282] Polyethylene porous membrane was selected and cut into rectangles of 45mm × 55mm.

[0283] Preparation of lithium metal batteries

[0284] 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 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 70°C for 12 hours to allow the precursor liquid to solidify in situ, forming a gel electrolyte, thus obtaining a lithium metal battery with a rated capacity of 70mAh.

[0285] Comparative Example 2

[0286] The preparation method of the lithium metal battery is the same as that in Example 25, except for the gel electrolyte.

[0287] The solutions shown in Table 4 are used as electrolytes for lithium metal batteries.

[0288] Test section

[0289] 1. Flammability test of gel electrolytes

[0290] Take 2g of the gel electrolyte precursor solution and place it in a glove box at 70℃ for 12 hours to obtain the gel electrolyte. Take 0.3g of the gel electrolyte, transfer it to the positive electrode shell of a 2032 coin cell, and burn it with the outer flame of a lighter for 5 seconds to observe the combustion of the electrolyte. The flammability test results of the gel electrolyte are shown in Tables 5 and 6.

[0291] 2. Long-cycle testing of lithium-ion batteries

[0292] The prepared lithium-ion battery was subjected to a charge-discharge cycle at an ambient temperature of 25°C, using a charging rate of 0.33C (23mA) and a discharging rate of 0.33C. The cutoff voltages for charging and discharging were set to 4.2V and 3V, respectively. A constant current-constant voltage charging method was used; specifically, after reaching the cutoff voltage of 4.2V with constant current charging at 0.33C, constant voltage charging at 4.2V was continued until the current decreased to 0.1C (7mA). The number of cycles completed when the discharge capacity decreased to 80% of the initial discharge capacity was taken as the battery's cycle life. The long-cycle test results of the lithium-ion battery are shown in Table 5.

[0293] 3. Long-cycle testing of lithium metal secondary batteries

[0294] The prepared lithium metal battery was subjected to a charge-discharge cycle at an ambient temperature of 25°C using a charging rate of 0.2C (14mA) and a discharging rate of 1C (70mA). The cutoff voltages for charging and discharging were set to 4.3V and 2.8V, respectively. A constant current-constant voltage charging method was used; specifically, after reaching the cutoff voltage of 4.3V with 0.2C constant current charging, constant voltage charging at 4.3V was continued until the current decreased to 0.1C (7mA). The number of cycles completed when the discharge capacity decreased to 80% of the initial discharge capacity was taken as the battery's cycle life. The long-cycle test results of the lithium metal battery are shown in Table 6.

[0295] Table 1 Composition of Solutions 1-8

[0296]

[0297] Note: In Table 1, LiFSI (lithium bisfluorosulfonylimide), LiPF6 (lithium hexafluorophosphate), EC (ethylene carbonate), EMC (ethyl methyl carbonate), DEC (diethyl carbonate), FEC (fluoroethylene carbonate), PC (propylene carbonate), FEMC (fluoroethyl methyl carbonate), VC (ethylene carbonate), and PS (propane sulpholactone) are commercially available.

[0298] In Table 1, the unit M for lithium salt concentration refers to mol / L; the volume ratio of ester solvents is the volume ratio of ester solvent 1, ester solvent 2 and ester solvent 3; the mass fraction of additives is the ratio of the mass of the additive to the sum of the masses of the additive, ester solvent and electrolyte salt.

[0299] Table 2 Composition of Solutions 9-16

[0300]

[0301]

[0302] Note: In Table 2, LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), DME (ethylene glycol dimethyl ether), TTE (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether), and Bz (benzene) are commercially available.

[0303] In Table 2, the mass fraction of electrolyte salt refers to the ratio of the mass of electrolyte salt to the sum of the masses of electrolyte salt, ether solvent, and diluent; the mass fraction of ether solvent refers to the ratio of the mass of ether solvent to the sum of the masses of electrolyte salt, ether solvent, and diluent; and the mass fraction of diluent refers to the ratio of the mass of diluent to the sum of the masses of electrolyte salt, ether solvent, and diluent.

[0304] Table 3 Cyclophosphazenes

[0305]

[0306] Note: Items I-1, I-2, I-3, I-4, I-5, and I-7 in Table 3 can be purchased commercially.

[0307] Table 4 Ether Oxygen Segments

[0308]

[0309] Note: In Table 4, Ⅱ-1, Ⅱ-2, Ⅱ-3, Ⅱ-4, Ⅱ-5, Ⅱ-6, Ⅱ-7, and Ⅱ-8 can be purchased commercially.

[0310] Table 5

[0311]

[0312]

[0313] Note: In Table 5, the composition of solutions 1-8 is as shown in Table 1. The solutions include electrolyte salts and solvents; I-1, I-2, I-3, I-4, I-5, and I-7 are shown in Table 3; II-1, II-2, II-3, II-4, II-5, II-6, II-7, and II-8 are shown in Table 4; the solid content of the gel electrolyte is the mass percentage of the polymer (a copolymer of cyclophosphonitrile and ether oxygen segments) in the gel electrolyte.

[0314] As can be seen from Examples 1-24 and Comparative Example 1, the gel electrolyte of this application cannot be ignited by a lighter, is a non-flammable electrolyte, has good flame retardancy, has excellent safety performance when applied to lithium-ion batteries, and has a long cycle life.

[0315] As can be seen from Examples 1-3, within the molar ratio range of cyclophosphonitrile and ether oxygen segments in this application, lithium-ion batteries can have a longer cycle life.

[0316] As can be seen from Examples 1 and 4-14, the use of the cyclophosphonitrile and ether oxygen segments of this application can enable lithium-ion batteries to have a longer cycle life.

[0317] As can be seen from Examples 1 and 15-21, the copolymers, solvents and electrolyte lithium salts of this application can improve the long cycle life of lithium-ion batteries.

[0318] As can be seen from Examples 1 and 22-24, the gel electrolyte in the secondary battery of this application can achieve a low solid content, and the lithium-ion battery using it has a long cycle life.

[0319] Table 6

[0320]

[0321]

[0322]

[0323] Note: In Table 6, the composition of solutions 9-16 is shown in Table 2, and the solutions include electrolyte salts and solvents; I-1, I-2, I-3, I-4, I-5, and I-7 are shown in Table 3; II-1, II-2, II-3, II-4, II-5, II-6, II-7, and II-8 are shown in Table 4; the solid content of the gel electrolyte is the mass percentage of the polymer (a copolymer of cyclophosphonitrile and ether oxygen segments) in the gel electrolyte.

[0324] As can be seen from Examples 25-45 and Comparative Example 2, the gel electrolytes of the present invention cannot be ignited by a lighter, are non-flammable electrolytes, have good flame retardancy, and have excellent safety performance when applied to lithium metal batteries, and have a long cycle life.

[0325] As can be seen from Examples 25-27, within the molar ratio range of cyclophosphonitrile and ether oxygen segments in this application, lithium metal batteries can have a longer cycle life.

[0326] As can be seen from Examples 25 and 28-38, the use of the cyclophosphonitrile and ether oxygen segments of this application can enable lithium metal batteries to have a longer cycle life.

[0327] As can be seen from Examples 25 and 39-45, the copolymers, solvents and electrolyte lithium salts of this application can improve the long cycle life of lithium metal batteries.

[0328] As can be seen from Examples 25 and 46-48, the gel electrolyte in the secondary battery of this application can achieve a low solid content, and the lithium metal battery using it has a long cycle life.

[0329] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. 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 secondary battery, characterized in that, include: The outer packaging and the electrode assembly and gel electrolyte contained within the outer packaging, wherein: The gel electrolyte comprises a polymer, a solvent, and an electrolyte salt; The polymer comprises a copolymer of cyclophosphonitrile and ether oxygen segments.

2. The secondary battery according to claim 1, characterized in that, The cyclophosphonitrile includes one of a first functional group and a second functional group; The ether oxygen segment includes another of the first functional group and the second functional group; The first functional group includes at least one of hydroxyl and amino groups; The second functional group includes an isocyanate group.

3. The secondary battery according to claim 1 or 2, characterized in that, The molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1-3:2-4.

4. The secondary battery according to any one of claims 1 to 3, characterized in that, The solid content of the gel electrolyte is 2% to 15%.

5. The secondary battery according to any one of claims 1 to 4, characterized in that, The cyclophosphonitrile includes the compound shown in Formula 1: In Formula 1, R1, R2, and R3 are each independently C1-C20 alkylene, C1-C20 alkyleneoxy, or C1-C20 fluoroalkylene; M1, M2, and M3 are each independently one of the first functional group and the second functional group; R4, R5, and R6 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a hydroxyl-substituted C1-C5 chain alkyl group, an amino-substituted C1-C5 chain alkyl group, a fluorinated C1-C5 chain alkyl group, or a C1-C5 chain alkoxy group. Wherein, when any one of R4, R5, and R6 includes the first functional group, M1, M2, and M3 are each independently the first functional group; when any one of R4, R5, and R6 includes the second functional group, M1, M2, and M3 are each independently the second functional group.

6. The secondary battery according to claim 5, characterized in that, In Equation 1: R1, R2, and R3 are each independently methyleneoxy, butylene, or propylene; R4, R5, and R6 are each independently a hydrogen atom, a fluorine atom, or a chlorine atom.

7. The secondary battery according to claim 6, characterized in that, The compound shown in Formula 1 includes at least one of the following compounds:

8. The secondary battery according to any one of claims 2 to 7, characterized in that, The ether oxygen segment includes the compound shown in Formula 2: In Equation 2, n is a positive integer between 1 and 1000; X is a C1-C10 alkylene group; M4 and M5 are each independently the other of the first functional group and the second functional group.

9. The secondary battery according to claim 8, characterized in that, In Equation 2: n is a positive integer between 50 and 200; X is a C1-C5 alkylene group.

10. The secondary battery according to claim 9, characterized in that, The compound shown in Formula 2 includes at least one of the following compounds:

11. The secondary battery according to any one of claims 1 to 10, characterized in that, The electrolyte salt includes one or more of lithium difluorosulfonylimide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium ditrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

12. The secondary battery according to any one of claims 1 to 11, characterized in that, The secondary battery is a lithium-ion battery and meets at least one of the following conditions: The solvent includes ester solvents, which include one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl formate, ethyl acetate, methyl acetate, fluoroethylene carbonate, difluoroethylene carbonate, methyl ethyl fluorocarbonate, diethyl fluorocarbonate, ethyl fluoroformate, ethyl fluoroacetate, and methyl fluoroacetate. The gel electrolyte also includes additives, which include one or more of the following: ethylene carbonate, propane sulpholactone, vinyl sulfate, vinyl sulfite, tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilane) borate, dimethyl maleic anhydride, and butyl 1,4-diisocyanate.

13. The secondary battery according to claim 12, characterized in that, The electrolyte salt is present in the gel electrolyte at a concentration of 8% to 15%; and / or The ester solvent in the gel electrolyte contains 80% to 90%; and / or The additive is present in the gel electrolyte at a concentration of 0.2% to 5%.

14. The secondary battery according to any one of claims 1 to 11, characterized in that, The secondary battery is a lithium metal battery and meets at least one of the following conditions: The solvent includes ether solvents, which include one or more of the following: diethyl ether, dipropyl ether, ethylpropyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol diethyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxopentane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane. The gel electrolyte further includes a diluent, which includes 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) One or more of the following: 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, perfluoroisopropylmethyl 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.

15. The secondary battery according to claim 14, characterized in that, The electrolyte salt content in the gel electrolyte is 12% to 20%; and / or The ether solvent in the gel electrolyte is present in an amount of 8% to 15%; and / or The diluent constitutes 60% to 75% of the gel electrolyte.

16. A method for preparing a secondary battery according to any one of claims 1 to 15, characterized in that, include: The precursor solution is obtained by mixing cyclophosphonitrile, ether oxygen segment, solvent and electrolyte salt; The electrode assembly is placed in the outer packaging to obtain a dry battery cell; The precursor liquid is injected into the dry cell and then the outer packaging is sealed, and the precursor liquid is cured in situ to obtain the secondary battery.

17. The method according to claim 16, characterized in that, The in-situ curing temperature is 40℃~80℃.

18. The method according to claim 16 or 17, characterized in that, The molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1–3:2–4; and / or Based on the total mass of the precursor solution, the sum of the mass percentages of the cyclophosphonitrile and the ether oxygen segment is 2% to 15%.

19. The method according to any one of claims 16 to 18, characterized in that, The secondary battery is a lithium-ion battery and meets at least one of the following conditions: In the mixture of the solvent and the electrolyte salt, the concentration of the electrolyte salt is 1M to 3M; The precursor solution also includes additives, and the mass ratio of the additives to the sum of the masses of the solvent and the electrolyte salt is 0.5 to 5:

100.

20. The method according to any one of claims 16 to 18, characterized in that, The secondary battery is a lithium metal battery, and the precursor solution also includes a diluent. The mass ratio of the electrolyte salt, the solvent and the diluent is 10-30:5-20:50-85.

21. A gel electrolyte, characterized in that, Includes polymers, solvents, and electrolyte salts; among which, The polymer comprises a copolymer of cyclophosphonitrile and ether oxygen segments.

22. The gel electrolyte according to claim 21, characterized in that, The cyclophosphonitrile includes one of a first functional group and a second functional group, and the ether oxygen segment includes the other of the first functional group and the second functional group. The first functional group includes at least one of hydroxyl and amino groups; the second functional group includes an isocyanate group.

23. The gel electrolyte according to claim 21 or 22, characterized in that, The molar ratio of the cyclophosphonitrile to the ether oxygen segment is 1-3:2-4.

24. The gel electrolyte according to any one of claims 21 to 23, characterized in that, The solid content of the gel electrolyte is 2% to 15%.

25. The gel electrolyte according to any one of claims 22 to 24, characterized in that, The cyclophosphonitrile includes the compound shown in Formula 1: In Formula 1, R1, R2, and R3 are each independently C1-C20 alkylene, C1-C20 alkyleneoxy, or C1-C20 fluoroalkylene; M1, M2, and M3 are each independently one of the first functional group and the second functional group; R4, R5, and R6 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a hydroxyl-substituted C1-C5 chain alkyl group, an amino-substituted C1-C5 chain alkyl group, a fluorinated C1-C5 chain alkyl group, or a C1-C5 chain alkoxy group. Wherein, when any one of R4, R5, and R6 includes the first functional group, M1, M2, and M3 are each independently the first functional group; when any one of R4, R5, and R6 includes the second functional group, M1, M2, and M3 are each independently the second functional group.

26. The gel electrolyte according to claim 25, characterized in that, In Equation 1: R1, R2, and R3 are each independently methyleneoxy, butylene, or propylene; R4, R5, and R6 are each independently a hydrogen atom, a fluorine atom, or a chlorine atom.

27. The gel electrolyte according to claim 26, characterized in that, The compound shown in Formula 1 includes at least one of the following compounds:

28. The gel electrolyte according to any one of claims 22 to 27, characterized in that, The ether oxygen segment includes the compound shown in Formula 2: In Equation 2, n is a positive integer between 1 and 1000; X is a C1-C10 alkylene group; M4 and M5 are each independently the other of the first functional group and the second functional group.

29. The gel electrolyte according to claim 28, characterized in that, In Equation 2: n is a positive integer between 50 and 200; X is a C1-C5 alkylene group.

30. The gel electrolyte according to claim 29, characterized in that, The compound shown in Formula 2 includes at least one of the following compounds:

31. An electrical device, characterized in that, The secondary battery includes any one of claims 1 to 15.

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