Composite flame-retardant additive, electrolyte and battery
By using composite flame retardant additives in the battery electrolyte, the synergistic effect of F, N, P elements and vinyl silane is used to solve the problem of high fire risk after battery thermal runaway, achieving higher flame retardant effect and battery safety.
Patent Information
- Application Number
- CN202510170039.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2025-05-23
AI Technical Summary
The existing batteries have a high risk of fire when thermally runaway, the existing flame retardant additives are average and require high content to delay combustion. The sensors and BMS are inaccurate in identifying the thermally runaway time points, which leads to the spread of the fire and is costly.
A composite flame retardant additive is used, which consists of organic compounds containing F, N, P elements and vinyl silane. Through the synergistic effect between each flame retardant element, even if it is added in a small amount in the electrolyte, it can effectively prevent the battery from getting fired after thermal runaway.
It improves the flame retardant characteristics of the battery in thermal runaway situations, delays or prevents the battery from burning, reduces the risk of damage to personnel and property, and maintains the excellence of other battery performance.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of batteries, and in particular to a composite flame retardant additive, an electrolyte and a battery. Background Art
[0002] The battery electrolyte contains a large amount of flammable organic solvents. When the battery thermally runs away due to heating or other factors, the huge heat released will cause the battery to burn, which poses a serious threat to the personal and property safety of users. Therefore, it is necessary to find an effective solution to reduce the risk of fire in the case of thermal runaway.
[0003] At present, the commonly used improvement strategies for battery thermal runaway fires include: (1) adding flame retardant additives to the electrolyte; (2) using gas sensors to identify fire smoke to automatically spray fire extinguishing agents; (3) using BMS to identify voltage, temperature and other signals during thermal runaway to activate the fire extinguishing system. However, the above three solutions have certain defects to varying degrees, and the flame retardant effect is average. Specifically: (1) Existing flame retardant electrolytes usually use a single flame retardant additive, which has a general flame retardant effect and requires a high content of flame retardant to achieve the effect of delaying combustion; (2) The solution of identifying thermal runaway through gas sensors and BMS is difficult to accurately identify the time point of thermal runaway, causing the fire to spread, and the price is also expensive.
[0004] Based on this, it is necessary to seek a solution that can reduce the risk of fire during battery thermal runaway and improve the safety of battery use. Summary of the invention
[0005] The present application provides a composite flame retardant additive, an electrolyte and a battery. The composite flame retardant additive can effectively prevent the battery from catching fire after thermal runaway even if a small amount is added to the electrolyte through the synergistic effect of various flame retardant elements, thereby improving the safety of the battery.
[0006] In a first aspect, the present application provides a composite flame retardant additive, including a first flame retardant additive and a second flame retardant additive, wherein the first flame retardant additive includes an organic compound containing at least one element of F, N, and P, and the second flame retardant additive includes vinyl silane.
[0007] In the composite flame retardant additive provided in the first aspect, an organic compound introduces at least one element of F, N, and P, and another organic compound vinyl silane introduces the element Si. When the first flame retardant additive contains F, it can generate fluorine-containing gas when heated, thereby isolating the air and capturing the surrounding hydrogen free radicals, delaying the development of thermal runaway; when the first flame retardant additive contains N, it can generate non-flammable gases such as ammonia and nitrogen when heated, diluting the combustible gas released when the lithium battery is thermally runaway; when the first flame retardant additive contains P, it can generate phosphoric acid, metaphosphoric acid, and polyphosphoric acid when heated, isolating the air and capturing the surrounding hydrogen free radicals, delaying the development of thermal runaway; when the first flame retardant additive contains two or more elements of F, N, and P, it can play a synergistic effect between F, N, and P, and better inhibit further combustion after the occurrence of thermal runaway. The second flame retardant additive includes vinyl silane, and the decomposition temperature of vinyl silane is higher than the decomposition temperature of the first flame retardant additive. When the vinyl silane decomposes, an inorganic oxygen-insulating protective layer containing Si-Si bonds and Si-C bonds can be formed. This stable and strong solid protective layer covers the surface of the positive and negative electrode materials of the battery, preventing the further development of thermal runaway of the lithium battery.
[0008] The composite flame retardant additive composed of the first flame retardant additive and the second flame retardant additive can exert the synergistic effect of the two flame retardant additives. When used, only a small amount of addition is required to decompose and release the flame retardant at different temperatures to achieve a flame retardant effect. In addition, F, N, and P are introduced from one compound, and Si is introduced from another compound. The amount of Si introduced and the amount of F, N, and P introduced can be controlled separately. When the amounts of the two compounds introduced do not affect each other, the amount of any one compound added can be controlled to control the introduced element of the compound to achieve a better flame retardant effect.
[0009] In addition, compared to the method of combining F, N, P and Si in the same compound as a flame retardant additive, the present application introduces Si and F, N, P through different flame retardant additives respectively, which can prevent the gaseous flame retardant substances generated by F, N, P from overflowing and destroying the solid insulation protective layer composed of Si-Si bonds and Si-C bonds, thereby further achieving better flame retardant effect.
[0010] In one possible design, the first flame retardant additive includes a fluorinated phosphazene or a fluorine-containing phosphate or phosphate ester.
[0011] Through the above scheme, the fluorinated phosphazene contains F, N and P elements at the same time, and the F, N and P in the first flame retardant can exert a synergistic effect to the greatest extent, and can further synergize with the second flame retardant to achieve a better flame retardant effect; the fluorinated phosphate contains F and P elements at the same time, and F, P and Si in the second flame retardant cooperate with each other to achieve a flame retardant effect; the phosphate contains P element, and P and Si in the second flame retardant cooperate with each other to achieve a flame retardant effect.
[0012] In one possible design, the fluorinated phosphazene includes at least one of hexafluorocyclotriphosphazene (HFPN), (ethoxy)pentafluorocyclotriphosphazene (PFPN), (phenoxy)pentafluorocyclotriphosphazene (FPPN), (trifluoroethoxy)pentafluorocyclotriphosphazene (TFPN), and hexamethoxyphosphazene (HMPN).
[0013] Through the above scheme, each of the above compounds contains F, N and P, so the synergistic effect between the three elements can be maximized, and at the same time, it can further synergize with the second flame retardant to achieve a better flame retardant effect.
[0014] In a possible design, the fluorine-containing phosphate includes at least one of trifluoroethoxy phosphate (TFP), bis(2,2,2-trifluoroethyl)phosphonate (TFEP), and tris(2,2,2-trifluoroethyl)phosphate (TTFEP).
[0015] Through the above scheme, the above compounds contain F and P elements at the same time, and F, P and Si in the second flame retardant cooperate with each other to achieve a better flame retardant effect.
[0016] In one possible design, the phosphate ester includes at least one of tris(m-methylphenoxy)methyl phosphate (TMMP), trimethyl phosphate (TMP), dimethyl methylphosphonate (DMMP), diethyl ethyl phosphate (DEEP), and triethyl phosphite (TEP).
[0017] Through the above scheme, the above compounds contain P element, and P and Si in the second flame retardant cooperate with each other to achieve a flame retardant effect.
[0018] In one possible design, the vinyl silane includes at least one of vinyl tris(trimethylsiloxy)silane (VTSS), vinyl trimethylsilane (VTS), vinyl tris(2-methoxyethoxy)silane (VTMS), vinyl triethoxysilane (VTES), and vinyl tris(2-methoxyethoxy)silane (VTMES).
[0019] Through the above scheme, each of the above compounds contains Si element, and the Si content in its structural formula is relatively high, which helps to quickly form an inorganic oxygen-isolating and heat-insulating protective layer containing Si-Si bonds and Si-C bonds after thermal decomposition, and the formed protective layer is harder and denser, and has a better flame retardant effect.
[0020] In a second aspect, the present application provides an electrolyte comprising the composite flame retardant additive in the above embodiment.
[0021] Through the above scheme, the above-mentioned composite flame retardant additive is used in the electrolyte. Only a small amount of the composite flame retardant additive needs to be added to greatly improve the flame retardant properties of the battery. When the battery has thermal runaway, it can better prevent and stop the battery from burning, or delay the time from thermal runaway to burning, thereby reducing the possibility of damage to personnel and property.
[0022] In a possible design, the mass fraction of the first flame retardant additive in the electrolyte is 0.5%-8%, the mass fraction of the second flame retardant additive in the electrolyte is 0.5%-8%, and the total mass fraction of the first flame retardant additive and the second flame retardant additive in the electrolyte is 1%-10%.
[0023] Through the above scheme, it is possible to ensure that the first flame retardant additive and the second flame retardant additive have a certain addition amount in the electrolyte, and prevent the first flame retardant additive and the second flame retardant additive from being added in excessive amounts in the electrolyte to affect the amount of other functional substances in the electrolyte. At the same time, since the first flame retardant additive and the second flame retardant additive can synergistically exert a flame retardant effect, even if the amount added is not large, a good flame retardant effect can be achieved, thereby ensuring that the battery using the electrolyte has good flame retardant properties while maintaining the superiority of other properties.
[0024] In one possible design, when the first flame retardant additive includes phosphate ester, the electrolyte further includes fluoroethylene carbonate (FEC).
[0025] Through the above scheme, vinyl silane, phosphate ester, and FEC can form a synergistic effect. FEC helps the electrolyte containing phosphate ester to form a stable SEI film on the surface of graphite negative electrode particles, and can provide fluorine element for generating hydrogen fluoride gas, thereby enhancing the flame retardant effect.
[0026] In a third aspect, the present application provides a battery, comprising the electrolyte in the above-mentioned embodiment.
[0027] Through the above scheme, only a small amount of composite flame retardant additives in the electrolyte is needed to significantly improve the flame retardant properties of the battery. When the battery has thermal runaway, it can better prevent and stop the battery from burning, or delay the time from thermal runaway to burning, thereby reducing the possibility of damage to personnel and property. At the same time, it can also ensure the addition amount of other functional substances in the electrolyte, so that the battery has excellent performance in various aspects such as cycle performance. DETAILED DESCRIPTION
[0028] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with examples and comparative examples. It should be understood that the embodiments described in this specification are only for explaining the present invention, not for limiting the present invention, and the formulas, proportions, etc. of the embodiments can be selected according to local conditions without substantial effect on the results.
[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.
[0030] In the description of the present application, unless otherwise specified, "plurality" means more than two (including two), and similarly, "multiple groups" means more than two groups (including two).
[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0032] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and similarly, any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.
[0033] The above summary of the invention of the present invention is not intended to describe each disclosed embodiment or each implementation in the present invention. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example and, enumeration is only as a representative group and should not be interpreted as exhaustive.
[0034] For existing flame-retardant electrolytes, a single flame-retardant additive is usually used, which has a general flame-retardant effect and requires a high content of flame retardant to achieve the effect of delaying combustion. The large amount of flame-retardant additive added will inevitably affect the amount of other substances in the electrolyte, such as the amount of lithium salt and film-forming additives. Therefore, the improvement of the flame-retardant performance of the electrolyte is often at the expense of the reduction of other basic properties.
[0035] In order to solve the above problems, the present application provides a composite flame retardant additive, which can release flame retardant substances in different temperature ranges, has a wider effective temperature, and better achieves the purpose of preventing battery fire after thermal runaway.
[0036] Specifically, the composite flame retardant additive provided in the present application includes a first flame retardant additive and a second flame retardant additive, wherein the first flame retardant additive includes an organic compound containing at least one element of F, N, and P, and the second flame retardant additive includes vinyl silane.
[0037] In the above-mentioned composite flame retardant additive, the first flame retardant additive introduces at least one element of F, N, and P, and its flame retardant principle includes:
[0038] When the first flame retardant additive contains F, it can generate fluorine-containing gas when heated, thereby isolating the air and capturing surrounding hydrogen radicals, delaying the development of thermal runaway.
[0039] When the first flame retardant additive contains P, it can generate phosphoric acid, metaphosphoric acid, and polyphosphoric acid when heated, isolate the air and capture surrounding hydrogen radicals, and delay the development of thermal runaway.
[0040] When the first flame retardant additive contains N, it can generate non-flammable gases such as ammonia and nitrogen when heated to dilute the flammable gas released when the lithium battery has thermal runaway.
[0041] When the first flame retardant additive contains two or more elements of F, N, and P, it can exert a synergistic effect among F, N, and P to better inhibit further combustion after the occurrence of thermal runaway of the battery.
[0042] The second flame retardant additive, vinyl silane, introduces the element Si. The decomposition temperature of vinyl silane is higher than that of the first flame retardant additive. When vinyl silane decomposes, it can form an inorganic oxygen-isolating and heat-insulating protective layer containing Si-Si bonds and Si-C bonds. This stable and strong solid protective layer covers the surface of the positive and negative electrode materials of the battery, preventing the thermal runaway of the lithium battery from further developing.
[0043] The composite flame retardant additive composed of the first flame retardant additive and the second flame retardant additive can exert the synergistic effect of the two flame retardant additives. When used, only a small amount of addition is required to decompose and release the flame retardant at different temperatures to achieve a flame retardant effect. In addition, F, N, and P are introduced from one compound, and Si is introduced from another compound. The amount of Si introduced and the amount of F, N, and P introduced can be controlled separately. When the amounts of the two compounds introduced do not affect each other, the amount of any one compound added can be controlled to control the introduced element of the compound to achieve a better flame retardant effect.
[0044] Furthermore, compared to the method of combining F, N, P and Si in the same compound as a flame retardant additive, the present application introduces Si and F, N, P respectively through different flame retardant additives, which can prevent the gaseous flame retardant substances generated by F, N, P from overflowing and destroying the solid insulation protective layer composed of Si-Si bonds and Si-C bonds, thereby further achieving better flame retardant effect.
[0045] In one possible design, the first flame retardant additive includes a fluorinated phosphazene or a fluorine-containing phosphate or phosphate ester.
[0046] Through the above scheme, the fluorinated phosphazene contains F, N and P elements at the same time, and the F, N and P in the first flame retardant can exert a synergistic effect to the greatest extent, and can further synergize with the second flame retardant additive to better achieve a flame retardant effect; the fluorinated phosphate contains F and P elements at the same time, and F, P and Si in the second flame retardant cooperate with each other to achieve a flame retardant effect; the phosphate contains P element, and P and Si in the second flame retardant cooperate with each other to achieve a flame retardant effect.
[0047] It can be understood that in the structural formula of the first flame retardant additive, the more effective elements (i.e., F, N, P) are contained, the more flame retardant substances will be produced by decomposition at high temperatures. Even if the first flame retardant additive is added in a small amount to the composite flame retardant additive, a good flame retardant effect can be achieved.
[0048] Specific substances of each type of the first flame retardant additive are exemplified below.
[0049] Exemplarily, when the first flame retardant additive is a fluorinated phosphazene, the fluorinated phosphazene includes at least one of hexafluorocyclotriphosphazene (HFPN), (ethoxy)pentafluorocyclotriphosphazene (PFPN), (phenoxy)pentafluorocyclotriphosphazene (FPPN), (trifluoroethoxy)pentafluorocyclotriphosphazene (TFPN), and hexamethoxyphosphazene (HMPN).
[0050] The above various types of fluorinated phosphazenes all contain F, N and P, and thus can maximize the synergistic effect between the three elements, and can also further synergize with the second flame retardant to achieve a better flame retardant effect.
[0051] Exemplarily, when the first flame retardant additive is a fluorine-containing phosphate, the fluorine-containing phosphate includes at least one of trifluoroethoxy phosphate (TFP), bis(2,2,2-trifluoroethyl)phosphonate (TFEP), and tris(2,2,2-trifluoroethyl)phosphate (TTFEP).
[0052] The above-mentioned various types of fluorine-containing phosphates contain both F and P elements. F, P and Si in the second flame retardant work together to achieve a better flame retardant effect.
[0053] Exemplarily, the phosphate ester includes at least one of tris(m-methylphenoxy)methyl phosphate (TMMP), trimethyl phosphate (TMP), dimethyl methylphosphonate (DMMP), diethyl ethyl phosphate (DEEP), and triethyl phosphite (TEP).
[0054] Through the above scheme, the above types of phosphate esters contain P element, and P and Si in the second flame retardant cooperate with each other to achieve a flame retardant effect.
[0055] In one possible design, the vinyl silane includes at least one of vinyl tris(trimethylsiloxy)silane (VTSS), vinyl trimethylsilane (VTS), vinyl tris(2-methoxyethoxy)silane (VTMS), vinyl triethoxysilane (VTES), and vinyl tris(2-methoxyethoxy)silane (VTMES).
[0056] All of the above types of vinyl silane contain Si element, and the Si content in their structural formula is relatively high, which helps to quickly form an inorganic oxygen-isolating and heat-insulating protective layer containing Si-Si bonds and Si-C bonds after thermal decomposition. The formed protective layer is harder and denser, and has a better flame retardant effect.
[0057] The present application also provides an electrolyte comprising the composite flame retardant additive in the above embodiment.
[0058] Through the above scheme, the above-mentioned composite flame retardant additive is used in the electrolyte. Only a small amount of the composite flame retardant additive needs to be added to greatly improve the flame retardant properties of the battery. When the battery has thermal runaway, it can better prevent and stop the battery from burning, or delay the time from thermal runaway to burning, thereby reducing the possibility of damage to personnel and property.
[0059] In a possible design, the mass fraction of the first flame retardant additive in the electrolyte is 0.5%-8%, the mass fraction of the second flame retardant additive in the electrolyte is 0.5%-8%, and the total mass fraction of the first flame retardant additive and the second flame retardant additive in the electrolyte is 1%-10%.
[0060] According to the specific types of the first flame retardant additive and the second flame retardant additive, the addition amounts of the first flame retardant additive and the second flame retardant additive may fluctuate within the above range.
[0061] For example, in a specific example, the composition of the composite flame retardant additive and its mass fraction in the electrolyte are: 3% PFPN+3% VTMS.
[0062] In another specific embodiment, the composition of the composite flame retardant additive and its mass fraction in the electrolyte are: 5% TFEP+3% VTMS.
[0063] In another specific embodiment, the composition of the composite flame retardant additive and its mass fraction in the electrolyte are: 7% TMMP + 3% VTMS.
[0064] Through the above scheme, it is possible to ensure that the first flame retardant additive and the second flame retardant additive have a certain addition amount in the electrolyte, and prevent the first flame retardant additive and the second flame retardant additive from being added in excessive amounts in the electrolyte to affect the amount of other functional substances in the electrolyte. At the same time, since the first flame retardant additive and the second flame retardant additive can synergistically exert a flame retardant effect, even if the amount added is not large, a good flame retardant effect can be achieved, thereby ensuring that the battery using the electrolyte has good flame retardant properties while maintaining the superiority of other properties.
[0065] In one possible design, when the first flame retardant additive includes phosphate ester, the electrolyte further includes fluoroethylene carbonate (FEC).
[0066] Through the above scheme, vinyl silane, phosphate ester, and FEC can form a synergistic effect. FEC helps the electrolyte containing phosphate ester to form a stable SEI on the surface of graphite negative electrode particles, and can provide F element for generating hydrogen fluoride gas to enhance the flame retardant effect.
[0067] Optionally, when the first flame retardant additive includes phosphate ester and the electrolyte includes FEC, the mass fraction of the first flame retardant additive in the electrolyte is 0.5%-10%, the mass fraction of the second flame retardant additive in the electrolyte is 0.5%-8%, the mass fraction of FEC in the electrolyte is 0.5%-8%, and the total mass fraction of the first flame retardant additive, the second flame retardant additive and FEC in the electrolyte is 1.5%-25%.
[0068] For example, in a specific example, the composition of the composite flame retardant additive and its mass fraction in the electrolyte are: 7% TMMP+3% VTMS+8% FEC.
[0069] Optionally, the electrolyte also includes a solvent, a lithium salt and other additives, wherein the mass fraction of the solvent in the electrolyte is 50%-90%, the mass fraction of the lithium salt in the electrolyte is 5%-20%, the mass fraction of other additives in the electrolyte is 4%-30%, and the sum of the content fractions of the solvent + lithium salt + composite flame retardant additive + other additives is 100%.
[0070] The solvent includes linear carbonates and cyclic carbonates, wherein the linear carbonates include one or more of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC); the cyclic carbonates include any one of ethylene carbonate (EC) and propylene carbonate (PC) or a combination of both.
[0071] In some examples, linear carbonate: cyclic carbonate = 6-8: 2-4, so that the battery has better charge and discharge performance.
[0072] More specifically, linear carbonate:cyclic carbonate=7:3.
[0073] The lithium salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium bis(oxalatoborate) (LiBOB), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and lithium bis(fluorooxalatoborate) (LiODFB).
[0074] Other additives are a general term for other types of additives other than composite flame retardant additives. Specifically, other additives may be film-forming additives, overcharge prevention additives or high voltage resistance additives, etc. Specifically, other additives include one or more of FEC, tris(trimethylsilyl)phosphite (TMSP), tris(trimethylsilyl)borate (TMSB), 1,3-propane sultone (PS), vinylene carbonate (VC), vinyl sulfate (DTD), 1,3-propylene sultone (PST), lithium difluorophosphate (LiP02F2), lithium bis(oxalatoborate) (LiBOB), succinonitrile (SN), adiponitrile (AND) and vinyl sulfate (VEC).
[0075] The present application provides a battery, comprising the electrolyte in the above-mentioned embodiment.
[0076] The specific structure of the battery can be the same as any battery structure in the related art, or it can be a completely new battery of any structure. As long as the above-mentioned electrolyte of the present application is used, the technical effect of the electrolyte in the above-mentioned embodiment of the present application can be achieved. Therefore, this embodiment of the present application does not limit the structure and type of the battery.
[0077] Through the above scheme, only a small amount of composite flame retardant additives in the electrolyte is needed to significantly improve the flame retardant properties of the battery. When the battery has thermal runaway, it can better prevent and stop the battery from burning, or delay the time from thermal runaway to burning, thereby reducing the possibility of damage to personnel and property. At the same time, it can also ensure the addition amount of other functional substances in the electrolyte, so that the battery has excellent performance in various aspects such as cycle performance.
[0078] The following takes the application of the composite flame retardant additive in a battery as an example, and illustrates the effects of the composite flame retardant additive through multiple groups of examples and comparative examples.
[0079] The following examples more specifically describe the disclosure of the present invention, which are intended for illustrative purposes only, as various modifications and variations within the scope of the present disclosure are apparent to those skilled in the art. Unless otherwise stated, all mass fractions, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available and can be used directly without further processing.
[0080] Square aluminum shell batteries containing the electrolytes in Table 1 below were prepared, and the capacity of each battery was 150 Ah. The positive electrode material of the battery in each embodiment and comparative example was 8-series high nickel ternary (NCM811), and the negative electrode material was graphite.
[0081] Table 1
[0082]
[0083]
[0084] The numbers in Table 1 represent the mass fraction of the corresponding column of materials in the electrolyte, and a number of 0 indicates that the corresponding material in the column is not added in the corresponding embodiment. For example, the lithium salt in the electrolyte of Example 1 is 13% LiPF6, the solvent is 23% EC + 53% EMC, the film-forming additive is 1% VC + 1% PS + 5% FEC, and the flame retardant additive is 3% VTMS + 3% PFPN.
[0085] In Table 1, the main differences between different embodiments and comparative examples are:
[0086] The flame retardant additive in the electrolyte used in Example 1 is fluorinated phosphazene + vinyl silane.
[0087] The flame retardant additive in the electrolyte used in Example 2 is fluorine-containing phosphate + vinyl silane.
[0088] The flame retardant additive in the electrolyte used in Example 3 is phosphate ester + vinyl silane.
[0089] The flame retardant additives in the electrolyte used in Example 4 are phosphate ester + vinyl silane, and the amount of FEC added is increased.
[0090] The electrolyte used in Comparative Example 1 does not contain any flame retardant additive.
[0091] The flame retardant additive in the electrolyte used in Comparative Example 2 is phosphazene fluoride.
[0092] The flame retardant additive in the electrolyte used in Comparative Example 3 is fluorine-containing phosphate.
[0093] The flame retardant additive in the electrolyte used in Comparative Example 4 is phosphate ester.
[0094] The test process is as follows: the battery manufactured in the above manner is charged to 100% SOC according to the battery pretreatment method of national standard GB-38031, and then subjected to hot box heating test. The battery is heated from room temperature to 130°C at a heating rate of 5°C / min and kept warm for 30 minutes; then, the battery is heated from 130°C to 200°C at a heating rate of 5°C / min and kept warm for 30 minutes; the heating is stopped, the battery is allowed to cool naturally, and observed for 1 hour. If the battery does not catch fire or explode, the test is considered passed.
[0095] Record the final test results in Table 2 below
[0096] Table 2
[0097] Group Hot Box Test Results Example 1 The test passed, the battery did not catch fire or explode after being kept at 200℃ for 30 minutes and then left to stand for 1 hour Example 2 The battery did not catch fire or explode after being kept at 200℃ for 30 minutes. The battery caught fire 48 minutes after the heating was stopped. Example 3 The battery did not catch fire or explode after being kept at 200℃ for 30 minutes. The battery caught fire 6 minutes after the heating was stopped. Example 4 The battery did not catch fire or explode after being kept at 200℃ for 30 minutes. The battery caught fire 14 minutes after the heating was stopped. Comparative Example 1 The battery did not catch fire or explode when kept at 130℃ for 30min. When the temperature was raised to 147℃, the battery exploded and caught fire. Comparative Example 2 The battery caught fire after being kept at 200℃ for 16 minutes Comparative Example 3 The battery caught fire after being kept at 200℃ for 4 minutes Comparative Example 4 The battery did not catch fire or explode when kept at 130℃ for 30min. When the temperature was raised to 197℃, the battery caught fire.
[0098] It can be seen from the test results recorded in Table 2 that the flame retardant effects of batteries using different electrolytes are as follows: Example 1 > Example 2 > Example 4 > Example 3 > Comparative Example 2 > Comparative Example 3 > Comparative Example 4 > Comparative Example 1.
[0099] It can be seen that the flame retardant effect of the composite flame retardant additive provided in the present application is better than the flame retardant effect of a single flame retardant additive. Moreover, among the various composite flame retardant additives provided in the present application, the best flame retardant effect is fluorinated phosphazene + vinyl silane, followed by fluorinated phosphate ester + vinyl silane, then phosphate ester + vinyl silane + FEC, and finally phosphate ester + vinyl silane.
[0100] In addition, only the battery of Example 1 passed the above test, which shows that among the composite flame retardant additives provided in the present application, the flame retardant effect of fluorinated phosphazene + vinyl silane is far superior to the flame retardant effects of other types of flame retardant additives.
[0101] In summary, the present application provides a composite flame retardant additive, an electrolyte and a battery. The composite flame retardant additive can release flame retardant substances in different temperature ranges and has a wider effective temperature. Moreover, through the synergistic effect of various flame retardant elements, even if a small amount is added to the electrolyte, it can better achieve the purpose of preventing the battery from catching fire after thermal runaway, thereby improving the safety of battery use.
Claims
1. A composite flame retardant additive, characterized in that: include: The first flame retardant additive includes an organic compound containing at least one element of F, N, and P, and The second flame retardant additive includes a vinyl silane.
2. The composite flame retardant additive according to claim 1, characterized in that: The first flame retardant additive includes fluorinated phosphazene or fluorine-containing phosphate or phosphate ester.
3. The composite flame retardant additive according to claim 2, characterized in that: The fluorinated phosphazene includes at least one of hexafluorocyclotriphosphazene (HFPN), (ethoxy)pentafluorocyclotriphosphazene (PFPN), (phenoxy)pentafluorocyclotriphosphazene (FPPN), (trifluoroethoxy)pentafluorocyclotriphosphazene (TFPN), and hexamethoxyphosphazene (HMPN).
4. The composite flame retardant additive according to claim 2, characterized in that: The fluorine-containing phosphate includes at least one of trifluoroethoxy phosphate (TFP), bis(2,2,2-trifluoroethyl)phosphonate (TFEP), and tris(2,2,2-trifluoroethyl)phosphate (TTFEP).
5. The composite flame retardant additive according to claim 2, characterized in that: The phosphate ester includes at least one of tris(m-methylphenoxy)methyl phosphate (TMMP), trimethyl phosphate (TMP), dimethyl methylphosphonate (DMMP), diethyl ethyl phosphate (DEEP), and triethyl phosphite (TEP).
6. The composite flame retardant additive according to any one of claims 1 to 5, characterized in that: The vinyl silane includes at least one of vinyl tris(trimethylsiloxy)silane (VTSS), vinyl trimethylsilane (VTS), vinyl tris(2-methoxyethoxy)silane (VTMS), vinyl triethoxysilane (VTES), and vinyl tris(2-methoxyethoxy)silane (VTMES).
7. An electrolyte, characterized in that: The composite flame retardant additive comprises the composite flame retardant additive according to any one of claims 1 to 6.
8. The electrolyte according to claim 7, characterized in that The mass fraction of the first flame retardant additive in the electrolyte is 0.5%-8%, the mass fraction of the second flame retardant additive in the electrolyte is 0.5%-8%, and the total mass fraction of the first flame retardant additive and the second flame retardant additive in the electrolyte is 1%-10%.
9. The electrolyte according to claim 7, characterized in that When the first flame retardant additive includes phosphate ester, the electrolyte further includes fluoroethylene carbonate (FEC).
10. A battery, characterized in that: The electrolyte comprising any one of claims 7 to 9.