Electrolyte, battery, battery pack, and electric device

Abstract

The application provides an electrolyte, a battery, a battery pack and a power utilization device, the electrolyte comprising a quinoline additive, the quinoline additive having a quinoline ring structure, and at least one isocyanate group being directly covalently bonded to a carbon atom of the quinoline ring structure. The application can efficiently remove trace moisture and acidic substances inside the battery, inhibit electrode-electrolyte interface side reactions, and thus improve long-term stability of the electrolyte and high-temperature cycle performance of the battery.

Description

[0001] This invention claims priority to Chinese Patent No. 2025118735439, filed with the Chinese Patent Office on December 11, 2025, entitled "An Electrolyte, Battery, Battery Pack and Electrical Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of battery technology, specifically relating to an electrolyte, a battery, a battery pack, and an electrical device. Background Technology

[0003] It is difficult to completely avoid the introduction of trace amounts of water during battery manufacturing, transportation, and use (such as residual moisture from electrolyte production, water of crystallization in electrode materials, and moisture carried by the separator and structural components). This trace water can react with electrolyte salts in the electrolyte (such as...). The reaction generates acidic substances (such as HF), which further corrode the positive electrode material and cause the transition metal to dissolve and deposit at the negative electrode interface, triggering irreversible side reactions, thereby reducing the high-temperature cycle performance of the battery. Summary of the Invention

[0004] This invention provides an electrolyte, a battery, a battery pack, and an electrical device. This invention can efficiently remove trace amounts of moisture and acidic substances inside the battery and suppress side reactions at the electrode-electrolyte interface, thereby improving the long-term stability of the electrolyte and the high-temperature cycle performance of the battery.

[0005] The present invention provides an electrolyte comprising a quinoline additive having a quinoline ring structure, wherein at least one isocyanate group is directly covalently bonded to the carbon atom of the quinoline ring structure.

[0006] In the electrolyte described above, the quinoline additive comprises the structure shown in Formula 1:

[0007] Formula 1,

[0008] R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen atoms, halogen atoms, alkyl groups, haloalkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryl groups, benzyl groups, heterocyclic groups, thionitryl groups, carboxyl groups, aldehyde groups, ketyl groups, amino groups, ether groups, alcohol groups, phenolic groups, ester groups, carbonate groups, nitro groups, isocyanate groups, imino groups, phosphate ester groups, cyano groups, urea groups, azo groups, isothiocyanate groups, silyl groups, siloxane groups, sulfonic acid groups, sulfonyl groups, amide groups, and sulfone groups.

[0009] In the electrolyte described above, the quinoline ring structure includes quinoline and / or acridine.

[0010] In the electrolyte as described above, the quinoline additive includes one or more of 4-isocyanate quinoline, 9-isocyanate acridine, 2-methoxy-4-isocyanate quinoline, and 2-phenyl-4-isocyanate-6-ethoxyquinoline.

[0011] The electrolyte as described above, wherein the mass percentage of quinoline additives in the electrolyte is 0.1% to 10%, preferably 0.5% to 1%; and / or, the electrolyte further comprises a second additive, an electrolyte salt, and a solvent; the second additive comprises at least one of carbonate additives, sulfonate additives, and phosphate additives.

[0012] The electrolyte as described above, wherein the mass percentage of the second additive in the electrolyte is 0.1%-5%; and / or, the mass percentage of the electrolyte salt in the electrolyte is 0.1%-15%; and / or, the mass percentage of the solvent in the electrolyte is 10%-90%.

[0013] The electrolyte as described above, wherein the electrolyte salt comprises a lithium salt, and the lithium salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate; and / or, the solvent comprises an organic solvent, and the organic solvent comprises at least one of carbonate solvents, carboxylic acid ester solvents, ether solvents, sulfone solvents, and nitrile solvents.

[0014] The present invention also provides a battery comprising the electrolyte described above.

[0015] The present invention also provides a battery pack comprising at least two batteries as described above that are interconnected.

[0016] The present invention also provides an electrical device, including the battery or the battery pack described above.

[0017] The electrolyte provided by this invention contains quinoline additives, which include a quinoline ring structure and isocyanate groups attached to the quinoline ring structure. The isocyanate groups in the quinoline additives can rapidly react with trace amounts of water, HF, and other acidic impurities to generate stable amide / urea products, significantly reducing the content of water and acidic substances in the electrolyte. The conjugated large π-bond system of the quinoline ring inhibits the decomposition of the isocyanate groups at high temperatures, avoiding problems such as electrolyte discoloration and precipitation, thus ensuring the long-term stability of the quinoline additives during high-temperature cycling. After reduction at the negative electrode interface, the quinoline additives form a mixture rich in inorganic components (such as… The SEI film improves lithium-ion transport efficiency and suppresses interfacial side reactions, thereby improving the high-temperature cycle performance of the battery. In quinoline additives, the quinoline ring structure and isocyanate groups work synergistically to efficiently remove trace amounts of moisture and acidic substances from inside the battery, suppressing electrode-electrolyte interfacial side reactions, thus improving the long-term stability of the electrolyte and the high-temperature cycle performance of the battery. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] In related technologies, electrolyte salts in the electrolyte (such as...) It readily reacts with trace amounts of water in the battery to generate acidic substances (such as HF), which further corrode the positive electrode material and cause transition metals to dissolve and deposit at the negative electrode interface, triggering irreversible side reactions, thereby reducing the battery's high-temperature cycle performance.

[0020] Taking lithium-ion batteries as an example, lithium-ion batteries experience problems such as capacity reduction, increased impedance, and gas generation during high-temperature cycling. This is due to the dissolution of transition metals from the positive electrode, which deposit on the negative electrode side, inducing a series of side reactions at the negative electrode interface. The main reason for the dissolution of transition metals from the positive electrode is the presence of trace amounts of water in the battery and lithium salts in the electrolyte. The reaction produces HF, which further corrodes the positive electrode material, causing the transition metal to dissolve. The sources of water in lithium-ion batteries are numerous, mainly including: ① trace water carried over from the production process of solvents, lithium salts, and additives in the electrolyte; ② trace water or water of crystallization that has not been dried out in the positive electrode nanomaterials; ③ trace water or water of crystallization that has not been dried out in the negative electrode; ④ trace water attached to the porous material of the separator; ⑤ trace water carried over from the cell structural components (such as aluminum-plastic film, tape, etc.); ⑥ trace water that still exists in the environment at low dew points. Trace water cannot be completely avoided during battery manufacturing.

[0021] The simplest and most effective way to remove trace water from battery cells is to introduce dehydrating and acid-suppressing additives into the electrolyte. These additives can quickly bind trace water during battery cycling to prevent it from affecting the battery's subsequent use. Currently, commonly used dehydrating and acid-suppressing additives in electrolytes are mainly silazanes, siloxanes, imides, nitriles, and isocyanates. Silazanes and siloxanes are unstable at high temperatures and easily precipitate during use, increasing battery impedance. Imides and amines have a slower dehydrating and acid-suppressing effect, and some only achieve their effect at high temperatures. Isocyanate-based dehydrating and acid-suppressing additives can react with water to form amides, which can quickly remove water from the electrolyte. However, common isocyanate-based additives and the pollutants they produce after reacting with water are unstable at high temperatures, easily causing electrolyte discoloration and precipitation, offering limited improvement in high-temperature performance.

[0022] In view of this, the present invention provides an electrolyte comprising a quinoline additive having a quinoline ring structure, wherein at least one isocyanate group is directly covalently bonded to the carbon atom of the quinoline ring structure.

[0023] The electrolyte provided by this invention can efficiently remove trace amounts of water and acidic substances inside the battery, and suppress side reactions at the electrode-electrolyte interface, thereby improving the long-term stability of the electrolyte and the high-temperature cycling performance of the battery. The reasons are as follows: (1) The isocyanate groups in quinoline additives can quickly react with trace amounts of water, HF and other acidic impurities to generate stable amide / urea products, which significantly reduces the content of water and acidic substances in the electrolyte. (2) The conjugated large π bond system of the quinoline ring inhibits the decomposition of the isocyanate groups at high temperatures, avoiding problems such as electrolyte discoloration and precipitation, and improving the long-term stability of quinoline additives in high-temperature cycling. (3) After reduction at the negative electrode interface, quinoline additives form a mixture rich in inorganic components (such as... The SEI film enhances lithium-ion transport efficiency and suppresses interfacial side reactions, thereby improving the high-temperature cycling performance of the battery. Thus, the above electrolyte can efficiently remove trace amounts of moisture and acidic substances from inside the battery, suppress electrode-electrolyte interfacial side reactions, and improve the long-term stability of the electrolyte and the high-temperature cycling performance of the battery.

[0024] In some embodiments, the quinoline additive includes the structure shown in Formula 1:

[0025] Formula 1,

[0026] R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen atoms, halogen atoms, alkyl groups, haloalkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryl groups, benzyl groups, heterocyclic groups, thionitryl groups, carboxyl groups, aldehyde groups, ketyl groups, amino groups, ether groups, alcohol groups, phenolic groups, ester groups, carbonate groups, nitro groups, isocyanate groups, imino groups, phosphate ester groups, cyano groups, urea groups, azo groups, isothiocyanate groups, silyl groups, siloxane groups, sulfonic acid groups, sulfonyl groups, amide groups, and sulfone groups.

[0027] In this invention, the compound with the structure shown in Formula 1 can better improve the long-term stability of the electrolyte, remove trace amounts of water inside the battery, suppress side reactions at the electrode-electrolyte interface, and form a stable SEI film on the surface of the negative electrode, thereby further improving the high-temperature cycle performance of the battery.

[0028] In this embodiment of the invention, the quinoline ring structure includes quinoline and / or acridine, which is beneficial for further enhancing the reactivity of the isocyanate group, while utilizing the structural rigidity of the heterocycle to improve the high-temperature stability of the additive. The conjugated system of the acridine ring can enhance the binding ability with trace amounts of water, thereby achieving a more efficient dehydration and acid suppression effect at lower concentrations.

[0029] In some embodiments, the quinoline additives include one or more of 4-isocyanate quinoline (as shown in Formula 1-1 below), 9-isocyanate acridine (as shown in Formula 1-2 below), 2-methoxy-4-isocyanate quinoline (as shown in Formula 1-3 below), and 2-phenyl-4-isocyanate-6-ethoxyquinoline (as shown in Formula 1-4 below).

[0030] Equation 1-1,

[0031] Equation 1-2,

[0032] Equation 1-3,

[0033] Equations 1-4.

[0034] In some embodiments, the mass percentage of quinoline additives in the electrolyte is 0.1% to 10%, preferably 0.2% to 5%, and more preferably 0.5% to 1%, which helps to better improve the long-term stability of the electrolyte, remove trace amounts of moisture inside the battery, and form a stable SEI film on the surface of the negative electrode, thereby further improving the high-temperature cycle performance of the battery.

[0035] For example, the mass percentage of quinoline additives in the electrolyte can be 0.1%, 1%, 3%, 5%, 7%, 9%, or 10%, etc.

[0036] In some embodiments, the electrolyte further includes a second additive, an electrolyte salt, and a solvent. The second additive includes at least one of carbonate additives, sulfonate additives, and phosphate additives. The aforementioned second additive can synergistically form a film with quinoline additives to create a stable and dense SEI film on the electrode surface. This effectively protects the electrode material, reduces side reactions, lowers interfacial impedance, and further improves the high-temperature cycling performance of the battery.

[0037] Electrolyte salts provide high ionic conductivity, ensuring efficient ion conduction in the battery. They also help form a stable SEI film on the electrode surface, protecting the electrode material and extending battery life.

[0038] Solvents can effectively dissolve electrolyte salts, forming a uniform electrolyte and improving ionic conductivity. They can also improve battery performance at low temperatures, maintain chemical stability at high temperatures, reduce decomposition and side reactions, and enhance battery safety.

[0039] In this embodiment of the invention, by adjusting the mass percentage content of the second additive, electrolyte salt, and solvent in the electrolyte, a more stable and dense SEI film is formed on the electrode surface, thereby further improving the high-temperature cycle performance of the battery. In some embodiments, the mass percentage content of the second additive in the electrolyte is 0.1%-5%, the mass percentage content of the electrolyte salt in the electrolyte is 0.1%-15%, and the mass percentage content of the solvent in the electrolyte is 10%-90%.

[0040] For example, the mass percentage of the second additive in the electrolyte can be 0.1%, 1%, 2%, 3%, 4%, or 5%, etc.

[0041] For example, the mass percentage of electrolyte salts in the electrolyte can be 0.1%, 3%, 5%, 8%, 11%, or 15%, etc.

[0042] For example, the mass percentage of solvent in the electrolyte can be 10%, 30%, 50%, 70%, or 90%, etc.

[0043] In some embodiments, the electrolyte salt includes a lithium salt, which includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate phosphate, lithium difluorooxalate borate, and lithium tetrafluorooxalate phosphate.

[0044] In some embodiments, the solvent includes an organic solvent, which includes at least one of carbonate solvents, carboxylic acid ester solvents, ether solvents, sulfone solvents, and nitrile solvents.

[0045] By further limiting the types of electrolyte salts and solvents, a synergistic effect can be achieved with the electrolyte additives provided by this invention, further improving the high-temperature cycle performance of the battery.

[0046] The present invention also provides a battery comprising the electrolyte as described above, which has advantages corresponding to the electrolyte described above, and will not be described in detail hereafter.

[0047] This invention does not limit the specific type of battery. For example, it can be a lithium cobalt oxide battery, a lithium iron phosphate battery, a ternary lithium-ion battery, a sodium-ion battery (e.g., a sodium iron sulfate battery, a sodium iron pyrophosphate battery, a nickel-iron-manganese-based sodium battery), a solid-state battery, etc.

[0048] In addition to the electrolyte, the battery of the present invention also includes a positive electrode, a negative electrode, and a separator. The present invention does not limit the specific types and structures of the positive electrode, negative electrode, and separator in the battery.

[0049] Optionally, the positive electrode sheet includes a positive current collector and a layer of positive active material located on one or both sides of the positive current collector, the positive active material layer including positive active material. The positive current collector used includes aluminum foil; the positive active material includes at least one of lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, sodium iron pyrophosphate, and sodium iron sulfate; other positive active materials used include binders, conductive agents, or other optional additives, the positive electrode binder may be selected from styrene-butadiene rubber (SBR), polyvinylidene fluoride, and water-based acrylic resin. The positive electrode conductive agent may be selected from at least one of the following: resin, polyacrylonitrile, polyvinylidene fluoride (PVDF), polyvinylpyrrolidone, hydroxypropyl methylcellulose, polytetrafluoroethylene (PTFE), polyacryl alcohol, ethylene-vinyl acetate copolymer (EVA), polyethylene ether, polyacrylate, polyacrylic acid (PAA), polyurethane, polyacrylate, styrene-acrylate copolymer, carboxymethyl cellulose (CMC), epoxy resin, polyvinyl alcohol (PVA), polyhexafluoropropylene, styrene-butadiene copolymer, sodium polymethyl cellulose, and polyvinyl butyral (PVB); the positive electrode conductive agent may be selected from at least one of superconducting carbon, graphene, acetylene black, conductive carbon black, Ketjen black, carbon dots, conductive graphite, carbon nanotubes, Super P (SP), and carbon nanofibers. In one specific embodiment, the positive electrode active material includes lithium iron phosphate.

[0050] Optionally, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector. The negative electrode current collector includes at least one of copper foil, nickel foil, or carbon-based current collector. The negative electrode active material layer includes at least one of natural graphite, artificial graphite, mesophase micro carbon spheres, hard carbon, soft carbon, silicon, silicon-carbon composite material, silicon-oxygen-carbon material, Li-Sn alloy, Li-Sn-O alloy, silicon-oxygen material, Sn, SnO, SnO2, and lithium-aluminum alloy. The negative electrode binder can be selected from styrene-butadiene rubber (SBR), polyvinylidene fluoride, waterborne acrylic resin, polyacrylonitrile, polyvinylidene fluoride (PVDF), and polyvinylpyrrolidone. The anode conductive agent may be selected from at least one of the following: hydroxypropyl methylcellulose, polytetrafluoroethylene (PTFE), polyacryl alcohol, ethylene-vinyl acetate copolymer (EVA), polyethylene ether, polyacrylate, polyacrylic acid (PAA), polyurethane, polyacrylate, styrene-acrylate copolymer, carboxymethyl cellulose (CMC), epoxy resin, polyvinyl alcohol (PVA), polyhexafluoropropylene, styrene-butadiene copolymer, sodium polymethyl cellulose, and polyvinyl butyral (PVB); the anode conductive agent may be selected from at least one of the following: superconducting carbon, graphene, acetylene black, conductive carbon black, Ketjen black, carbon dots, conductive graphite, carbon nanotubes, Super P (SP), and carbon nanofibers.

[0051] Optionally, the diaphragm can be selected from well-known porous material diaphragms or coated diaphragms with good chemical and mechanical stability. The material of the diaphragm can be selected from at least one of non-woven fabric, glass fiber, polytetrafluoroethylene, polyethersulfone, polypropylene, polyolefin, aromatic polyamide, and polyethylene. The diaphragm can be a single-layer or multi-layer composite film.

[0052] The battery of the present invention can be prepared using conventional methods in the art. Specifically, the positive electrode, separator and negative electrode can be stacked in sequence, and the cell can be obtained by stacking or winding. Then, the battery can be obtained by baking, liquid injection, formation and packaging.

[0053] It should be noted that during the preparation process of the battery provided by the present invention, the amount of each substance added may deviate from the content of each substance obtained from the electrolyte obtained after disassembling the battery, but it is within the error range. Therefore, the amount of each substance added during the battery preparation process is basically consistent with the content of each substance in the electrolyte.

[0054] This invention also provides a battery pack comprising at least two batteries as described above that are interconnected. This battery pack has advantages corresponding to the batteries described above, which will not be elaborated further.

[0055] The battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0056] This invention also provides an electrical device, including the battery or battery pack described above. This electrical device has advantages corresponding to the battery described above, which will not be elaborated further.

[0057] The electrical equipment used in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., and there are no particular limitations on this.

[0058] The present invention will be further described below through specific embodiments.

[0059] Example 1

[0060] The electrolyte is prepared in an environment with a dew point ≤ -50℃, and its raw material composition and proportions are as follows: Organic solvent: composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a mass ratio of 1:1:1, accounting for 84 wt% of the total mass of the electrolyte; Lithium salt: lithium hexafluorophosphate (… The electrolyte consists of: lithium salt (13 wt%), vinylene carbonate (VC) (2 wt%), and quinoline additive (4-isocyanate quinoline (Formula 1-1, CAS No.: 1260672-84-1) (1 wt%).

[0061] The preparation of the electrolyte includes the following steps: the above organic solvent, lithium salt, second additive and quinoline additive are mixed evenly, and then 200 ppm water is added and mixed evenly to obtain the electrolyte.

[0062] Example 2

[0063] The difference between this embodiment and Example 1 is that 4-isocyanate quinoline is replaced in equal amounts with 9-isocyanate acridine (Formula 1-2, CAS No.: 194540-01-7), while the remaining steps and conditions are the same as in Example 1.

[0064] Example 3

[0065] The difference between this embodiment and Example 1 is that 4-isocyanate quinoline is replaced in equal amounts with 2-methoxy-4-isocyanate quinoline (Formula 1-3, CAS No.: 1260664-83-2), while the remaining steps and conditions are the same as in Example 1.

[0066] Example 4

[0067] The difference between this embodiment and Example 1 is that 4-isocyanate quinoline is replaced in equal amounts with 2-phenyl-4-isocyanate-6-ethoxyquinoline (Formula 1-4, CAS No.: 856083-27-7), while the remaining steps and conditions are the same as in Example 1.

[0068] Example 5

[0069] The difference between this embodiment and Example 1 is that the mass percentage of 4-isocyanate quinoline in the electrolyte is 0.1%, while the remaining steps and conditions are the same as in Example 1.

[0070] Example 6

[0071] The difference between this embodiment and Example 1 is that the mass percentage of 4-isocyanate quinoline in the electrolyte is 10%, while the remaining steps and conditions are the same as in Example 1.

[0072] Example 7

[0073] The difference between this embodiment and Example 1 is that the mass percentage of 4-isocyanate quinoline in the electrolyte is 13%, while the remaining steps and conditions are the same as in Example 1.

[0074] Example 8

[0075] The difference between this embodiment and Example 1 is that the mass percentage of 4-isocyanate quinoline in the electrolyte is 0.5%, while the remaining steps and conditions are the same as in Example 1.

[0076] Comparative Example 1

[0077] The difference between this embodiment and Example 1 is that no quinoline additive, 4-isocyanate quinoline, was added to the electrolyte; the remaining steps and conditions are the same as in Example 1.

[0078] Experimental example:

[0079] A small pouch battery with a capacity of 1.8Ah is formed by stacking commercially available lithium iron phosphate positive electrode sheets, graphite negative electrode sheets, and separators.

[0080] Preparation of lithium iron phosphate positive electrode sheet: Lithium iron phosphate (LFP), conductive agent Super-P and binder polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of LFP:Super-P:PVDF=100:20:3, and then uniformly coated on the positive electrode current collector aluminum foil and dried under vacuum at 100℃ for 24h to obtain lithium iron phosphate positive electrode sheet.

[0081] Preparation of graphite negative electrode sheet: Graphite (Gr), carbon nanotubes (CNT), styrene-butadiene rubber (SBR) binder and sodium carboxymethyl cellulose (CMC) thickener are mixed evenly in mass ratio Gr:CNT:SBR:CMC=100:2:3:2 and then uniformly coated on copper foil of negative electrode current collector and dried under vacuum at 80℃ for 24h to obtain graphite negative electrode sheet.

[0082] Battery fabrication: The separator is Celgard2400 model. The positive and negative electrodes and the separator are sequentially die-cut, stacked, hot-pressed, baked, injected with electrolyte (that is, the electrolyte prepared in the above examples and comparative examples is injected into the dried bare cell), sealed, formed, and aged to obtain the finished battery.

[0083] The electrolytes in the above embodiments and comparative examples were subjected to dehydration and acid suppression tests: the electrolytes were sealed and placed in a dew point environment (-50℃ and below) for different times of 0h, 3h, 1 day (1D), and 3 days (3D). The moisture content was measured using a Mettler coulomb moisture analyzer, and the hydrofluoric acid content was measured using a sodium methoxide / methanol manual titration method. The results are shown in Table 1.

[0084] Table 1

[0085]

[0086] As shown in Table 1, compared to Comparative Example 1, the electrolytes in Examples 1-4 with added quinoline additives showed a significant reduction in moisture content after 3 hours, essentially meeting the electrolyte moisture standard requirement (≤25 ppm). After standing at room temperature for 1 day, the moisture content in all examples was below 25 ppm. Comparing Examples 1-4, it is evident that 4-isocyanate quinoline in Example 1 has a better water removal effect. Comparing Examples 1 and Examples 5-8, it is clear that insufficient addition results in poor water removal and acid suppression. In contrast, the initial moisture content of the electrolyte in Comparative Example 1 was around 200 ppm, and it gradually decreased while the acidity gradually increased over time. This indicates that the moisture in Comparative Example 1 underwent a hydrolysis reaction with lithium salt LiPF6, and the longer the reaction time, the higher the acidity in the electrolyte. All of the above demonstrates that the aforementioned quinoline additives can efficiently remove trace amounts of moisture inside the battery and suppress side reactions at the electrode-electrolyte interface.

[0087] High-temperature cycle performance tests were conducted on the batteries in the above experimental examples and comparative experimental examples: The batteries were placed in an environment of 45℃ and cycled 600 times according to the process of constant current and constant voltage charging at 1C to 3.65V (cutoff current 0.05C) and constant current discharging at 1C to 2.0V. After every 100 cycles, the batteries were allowed to stand at room temperature and a capacity recovery test was performed. Capacity retention rate after 600 cycles = (discharge capacity after 600 cycles / initial discharge capacity) × 100%. Capacity recovery rate after 600 cycles = (discharge capacity recovered at room temperature after 600 cycles / initial discharge capacity at room temperature) × 100%.

[0088] Table 2

[0089]

[0090] Analysis of Table 2 shows that, based on the 45℃ high-temperature cycle performance of the batteries, compared to the cycle performance of the lithium-ion batteries corresponding to the basic electrolyte in Comparative Test Example 1, Test Examples 1-8 containing quinoline additives significantly improve the high-temperature cycle performance. Comparing Test Examples 1-4, Test Example 1, containing 4-isocyanate quinoline, exhibits superior water removal performance and thus has the best high-temperature cycle performance. Comparing Test Examples 1 and Test Examples 5-8, an addition amount of 0.5%~1% is the preferred value.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention 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. Such 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 the present invention.

Claims

1. An electrolyte, characterized in that, The additives include quinoline-based additives, which have a quinoline ring structure and at least one isocyanate group is directly covalently bonded to the carbon atom of the quinoline ring structure.

2. The electrolyte according to claim 1, characterized in that, The quinoline additive includes the structure shown in Formula 1: Formula 1, R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen atoms, halogen atoms, alkyl groups, haloalkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, aryl groups, benzyl groups, heterocyclic groups, thionitryl groups, carboxyl groups, aldehyde groups, ketyl groups, amino groups, ether groups, alcohol groups, phenolic groups, ester groups, carbonate groups, nitro groups, isocyanate groups, imino groups, phosphate ester groups, cyano groups, urea groups, azo groups, isothiocyanate groups, silyl groups, siloxane groups, sulfonic acid groups, sulfonyl groups, amide groups, and sulfone groups.

3. The electrolyte according to claim 1 or 2, characterized in that, The quinoline ring structure includes quinoline and / or acridine.

4. The electrolyte according to claim 3, characterized in that, The quinoline additives include one or more of 4-isocyanate quinoline, 9-isocyanate acridine, 2-methoxy-4-isocyanate quinoline, and 2-phenyl-4-isocyanate-6-ethoxyquinoline.

5. The electrolyte according to any one of claims 1-4, characterized in that, The electrolyte contains quinoline additives at a mass percentage of 0.1% to 10%, preferably 0.5% to 1%. And / or, the electrolyte further includes a second additive, an electrolyte salt, and a solvent; the second additive includes at least one of carbonate additives, sulfonate additives, and phosphate additives.

6. The electrolyte according to claim 5, characterized in that, The mass percentage of the second additive in the electrolyte is 0.1%-5%; And / or, the mass percentage of the electrolyte salt in the electrolyte is 0.1%-15%; And / or, the mass percentage of the solvent in the electrolyte is 10%-90%.

7. The electrolyte according to claim 5 or 6, characterized in that, The electrolyte salt includes lithium salts, which include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate phosphate, lithium difluorooxalate borate, and lithium tetrafluorooxalate phosphate. And / or, the solvent includes an organic solvent, which includes at least one of carbonate solvents, carboxylic acid ester solvents, ether solvents, sulfone solvents, and nitrile solvents.

8. A battery, characterized in that, Includes the electrolyte according to any one of claims 1-7.

9. A battery pack, characterized in that, It includes at least two batteries as described in claim 8 that are interconnected.

10. An electrical appliance, characterized in that, It includes the battery of claim 8 or the battery pack of claim 9.

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