Composite material and preparation method thereof, electrolyte composition and preparation method thereof, battery and electric equipment

Abstract

The invention provides a composite material and a preparation method thereof, an electrolyte composition and a preparation method thereof, a battery and electric equipment. The composite material comprises an inner core; the invention discloses a high-temperature-resistant flame-retardant material which comprises an inner core and a shell, the surface of the inner core is coated with the shell, the shell comprises an organic additive, and the organic additive comprises at least one of 4, 4 '-dichloromethyl biphenyl, triethyl phosphite and a nitrile group compound. When the electrolyte composition obtained after the composite material adsorbs the electrolyte is used for the battery, the interface impedance can be effectively reduced, so that the long cycle performance of the battery is improved.

Description

Technical Field

[0001] The present application belongs to the field of electrochemical technology, and specifically relates to a composite material and a preparation method thereof, an electrolyte composition and a preparation method thereof, a battery and an electrical device. Background Art

[0002] Lithium-ion batteries, with their environmentally friendly, high operating voltage, and zero memory effect, are widely used in the automotive, energy storage, power, and military aerospace sectors. As the "blood" of lithium-ion batteries, electrolytes play a vital role in their performance. As the scope of battery applications expands, the requirements for battery performance are also increasing. The effective use of organic electrolyte additives is one way to improve the overall performance of batteries. However, the high concentration of organic additives in existing multifunctional electrolytes increases viscosity. While this improves certain electrolyte properties, it also introduces problems such as high interfacial impedance and degraded cycle performance. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a composite material with better cycle performance and a preparation method thereof, an electrolyte composition and a preparation method thereof, a battery and an electrical device.

[0004] In the first aspect of the present application, a composite material is proposed, comprising: a core; a shell, the shell being coated on the surface of the core, the shell comprising an organic additive, the organic additive comprising at least one of 4,4'-dichloromethylbiphenyl, triethyl phosphite and a nitrile compound. When the composite material of the present application comes into contact with an electrolyte, it can adsorb the electrolyte, or in other words, the electrolyte can penetrate into the molecular chain structure of the shell and / or core of the composite material to form gel particles. When the gel particles are used as the electrolyte of a battery, they can gradually release the electrolyte and the organic additive during the operation of the battery, thereby changing the traditional method of mixing, adding and releasing organic additives in composite electrolytes, enabling the electrolyte and the organic additive to be gradually released, giving full play to the advantages of each component of the organic additive, and thus solving the problems of increased impedance and reduced cycle performance caused by organic additives in existing electrolytes.

[0005] In some embodiments, the core comprises at least one of titanium dioxide particles and polyvinyl pyrrolidone (PVP) particles. The core can serve as a template for composite material formation, facilitating the formation of a shaped composite material. Furthermore, polyvinyl pyrrolidone can also serve as an electrolyte additive, increasing battery stability and improving electrochemical performance when used in batteries.

[0006] In some embodiments, the organic additive includes 4,4'-dichloromethylbiphenyl, triethyl phosphite (TEP), and a nitrile compound in a mass ratio of 0.1-8:0.1-8:0.1-8. This results in a better slow release of the electrolyte and the organic additive. Furthermore, the synergistic effect of 4,4'-dichloromethylbiphenyl, TEP, and the nitrile compound, combined with their strong binding energy for HF, effectively removes HF and water generated in side reactions of the electrolyte, improving interfacial stability and thus enhancing the long-cycle performance of the battery.

[0007] In some embodiments, the nitrile compound includes at least one of ethylene glycol dipropionitrile, 1,3,6-hexanetrinitrile, 1,3,5-pentanetrinitrile, tris(2-cyanoethyl)borate, and 3-(trifluoromethyl)benzoylacetonitrile. This can improve the thermodynamic stability of the positive electrode and reduce the migration of transition metal ions.

[0008] In some embodiments, the mass ratio of the core to the organic additive is 0.05-4.5:0.05-6.5, thereby forming a core-shell structured composite material with better electrolyte storage and slow electrolyte release effects.

[0009] In some embodiments, the housing can absorb the electrolyte to swell at a first temperature, and can release the electrolyte and the organic additive under the action of an external force and / or at a second temperature, where the second temperature is greater than the first temperature.

[0010] In some embodiments, the first temperature is 10°C to 60°C; and / or the second temperature is 20°C to 70°C.

[0011] A second aspect of this application provides a method for preparing a composite material, comprising: mixing an organic additive, a core, and a solvent to obtain a mixture; aging the mixture to obtain an aged product in which the organic additive is coated on the surface of the core; and calcining the aged product to obtain the composite material. This method can be used to prepare a core-shell composite material, and the method is simple to operate and readily applicable to industrial production.

[0012] In some embodiments, the method for preparing the composite material satisfies at least one of the following conditions:

[0013] (1) Mixing the organic additive and the core includes:

[0014] Under magnetic stirring, 0 to 8 parts by weight of 4,4'-dichloromethylbiphenyl, 0 to 8 parts by weight of triethyl phosphite, and 0 to 8 parts by weight of a nitrile compound are mixed and dissolved, and the core is added according to a mass ratio of the core to the organic additive of 0.05 to 4.5:0.05 to 6.5, and ultrasonic treatment is performed for 0.1 to 1 hour to obtain the mixture; wherein the weight parts of the 4,4'-dichloromethylbiphenyl, triethyl phosphite, and the nitrile compound are not all 0;

[0015] (2) Mixing the organic additive and the core to obtain a mixture further includes adding a solvent to the mixture for mixing, wherein the solvent includes anhydrous ethanol and ammonia water, and the volume ratio of the anhydrous ethanol to the ammonia water is 0.2-6:0.1-2;

[0016] (3) The aging treatment is performed at room temperature for 0.5 to 6 hours;

[0017] (4) subjecting the aged product to solid-liquid separation, washing the obtained solid product with distilled water and anhydrous ethanol 2 to 6 times respectively, and drying at 20 to 90° C. for 2 to 8 hours;

[0018] (5) The calcination includes: heating to 20°C to 800°C and calcining for 2h to 8h.

[0019] In some embodiments, the core includes titanium dioxide particles, and the preparation steps of the titanium dioxide particles include: mixing a titanium source, a pH regulator and a solvent to obtain a first mixture; mixing the first mixture and an acid to obtain a second mixture; and heat-insulating the second mixture and then performing solid-liquid separation to obtain the titanium dioxide particles.

[0020] According to an embodiment of the present application, the method for preparing titanium dioxide particles satisfies at least one of the following conditions:

[0021] (1) mixing 0.05 to 2.0 parts by weight of a titanium source, 0.02 to 3.0 parts by weight of a pH adjuster, and a solvent to obtain a first mixture;

[0022] (2) mixing the first mixture and an acid, and waiting for the solution to become clear to obtain a second mixture; the molar ratio of the titanium element in the first mixture to the hydrogen element in the acid is 0.35 to 0.5:1;

[0023] (3) The heat preservation treatment includes: heating the second mixture to 20°C to 200°C and keeping the temperature for 4 hours to 20 hours.

[0024] In some embodiments, the titanium source includes at least one of titanyl sulfate, tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, titanium chloride, titanium nitrate, and titanium oxalate.

[0025] In some embodiments, the pH adjuster includes at least one of urea, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonia water.

[0026] In some embodiments, the solvent includes deionized water.

[0027] In some embodiments, the acid comprises at least one of hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, tartaric acid, and citric acid.

[0028] The third aspect of the present application proposes an electrolyte composition, comprising: gel particles and a first electrolyte, wherein the gel particles include a composite material and a second electrolyte contained in the composite material, wherein the composite material includes the composite material described above or the composite material prepared by the preparation method described above. The electrolyte composition is generally injected into the outer packaging of the battery through the injection hole by an injection device (such as an injection needle) under a certain pressure. The force exerted on the electrolyte during the injection process can cause the gel particles to release the electrolyte and organic additives; after the electrolyte composition is injected into the battery, the gel particles can also slowly release the electrolyte and organic additives under the action of temperature during the high-temperature infiltration of the battery, thereby improving the long-cycle performance of the battery. Specifically, the electrolyte composition contains the electrolyte in the shell and / or the core, and releases the electrolyte in the gel particles under the action of the injection process. When the battery enters the high-temperature infiltration process, under the action of temperature, the shell and / or the core of the composite material ruptures to release the organic additives, and reacts chemically with HF and water to form hydrogen bonds and ionic bonds, which can effectively inhibit the occurrence of electrolyte side reactions and improve the long-cycle performance of the battery.

[0029] In some embodiments, based on the total mass of the gel particles, the mass percentage of the composite material is 0.05% to 40.5%.

[0030] In some embodiments, the first electrolyte and the second electrolyte both include a solvent and an electrolyte salt, the solvent including at least one of propylene carbonate, diethyl carbonate, tetrahydrofuran, dimethyl carbonate, and ethylene carbonate; and / or the electrolyte salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium bis(oxalatoborate) (LiBOB), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0031] In a fourth aspect, the present application provides a method for preparing an electrolyte composition, comprising: providing a composite material, the composite material being the composite material described above or a composite material prepared by the method described above; mixing the composite material with a second electrolyte to obtain gel particles; and mixing the gel particles with the first electrolyte to obtain the electrolyte mixture. This method is simple to operate and readily adaptable to industrial production.

[0032] According to an embodiment of the present application, the first electrolyte and the second electrolyte are the same and are defined as a third electrolyte. The method includes: mixing the composite material and the third electrolyte to obtain the electrolyte composition.

[0033] According to an embodiment of the present application, the mass ratio of the composite material to the second electrolyte is 0.05-40.5:59.5-99.5.

[0034] In a fifth aspect, the present application provides a battery comprising the electrolyte composition of the third aspect or the electrolyte composition prepared by the method of the fourth aspect. Thus, the battery has low impedance and good long cycle performance.

[0035] The sixth aspect of the present application provides an electrical device comprising the battery described in the fifth aspect. The electrical device has all the features and advantages of the battery described above, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the appearance of gel particles in an embodiment of the present application.

[0037] Figure 2 Schematic diagram of the cross-sectional structure of the gel particles of the embodiment of the present application.

[0038] Figure 3 2 is a schematic diagram of the injection process of the electrolyte composition of the embodiment of the present application into the battery outer packaging.

[0039] Figure 4 Schematic diagram of the synthesis process of the composite material of the embodiment of the present application. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0041] In the first aspect of the present application, a composite material is proposed, comprising: a core; a shell, wherein the shell is coated on the surface of the core, and the shell comprises an organic additive, wherein the organic additive comprises at least one of 4,4'-dichloromethylbiphenyl, triethyl phosphite and a nitrile compound.

[0042] When the composite material of the present application comes into contact with the electrolyte, it can absorb the electrolyte, or the electrolyte can penetrate into the molecular chain structure of the shell and / or core of the composite material to form gel particles. When the gel particles are used in a battery, they can gradually release the electrolyte and organic additives during the operation of the battery, thereby changing the traditional method of mixing, adding and releasing organic additives in composite electrolytes, so that the electrolyte and organic additives can be gradually released, giving full play to the advantages of each component of the organic additives, thereby solving the problems of increased impedance and reduced cycle performance caused by existing organic additives in electrolytes.

[0043] In some embodiments, the core comprises at least one of titanium dioxide particles and polyvinyl pyrrolidone particles. This results in a core with a smaller particle size, less agglomeration, easier dispersion, and greater stability, providing an effective support for core-shell structure formation. Furthermore, the titanium dioxide and polyvinyl pyrrolidone particles have a larger specific surface area, providing greater contact area with the organic additive, further facilitating composite material formation and subsequent release of the electrolyte and organic additive.

[0044] In some embodiments, the organic additives include 4,4'-dichloromethylbiphenyl, triethyl phosphite, and a nitrile compound in a mass ratio of 0.1-8:0.1-8:0.1-8. The mass ratio of the three can be, for example, 1:1:1, 1:2:3, 2:5:6, 1:4:8, 1:1:6, 1:6:6, or 1:2:1. Such a ratio facilitates the construction of a composite material housing and fully leverages the advantages of each component, effectively improving the overall performance of the battery.

[0045] Specifically, 4,4'-dichloromethylbiphenyl can effectively reduce capacity loss caused by transition metal ion migration. This is primarily due to the fact that the introduction of biphenyl organic additives can reduce the charge density of transition metal ions (primarily from the dissolution of the cathode material), reducing the polarization effect on the electrolyte salt anions in the electrolyte, thereby preventing the transition metal ions from catalyzing the decomposition of the electrolyte salt anions in the electrolyte and reducing the generation of HF in side reactions. The addition of triethyl phosphite can effectively reduce interfacial impedance and form an effective interface layer between the electrolyte and the cathode. This is primarily due to the generation of lattice oxygen during lithium ion migration. The P atoms in triethyl phosphite, which contain electron-deficient centers, can capture active oxygen, effectively removing oxygen free radicals. Furthermore, triethyl phosphite can promote the dissolution of decomposition byproducts such as LiF, Li2O2, and Li2O, reducing interfacial impedance. The introduction of nitrile compounds can improve the thermodynamic stability of the cathode and reduce the migration of transition metal ions. This is primarily due to the strong coordination between nitrile compounds and transition metal ions and their strong binding energy with H in water, which effectively reduces the generation of HF and water in side reactions in the electrolyte.

[0046] In some embodiments, the nitrile compound includes at least one of ethylene glycol dipropionitrile, 1,3,6-hexanetrinitrile, 1,3,5-pentanetrinitrile, tris(2-cyanoethyl)borate, and 3-(trifluoromethyl)benzoylacetonitrile. The use of these specific compounds has a strong coordination effect with transition metal ions and a strong ability to bind H in water, which can effectively reduce the generation of HF and water in electrolyte side reactions, thereby further improving the thermodynamic stability of the positive electrode and reducing the migration of transition metal ions.

[0047] In some embodiments, the mass ratio of the core to the organic additive is 0.05-4.5:0.05-6.5, such as 0.05:0.05, 0.05:1, 0.05:1.5, 0.05:2, 0.05:2.5, 0.05:3, 0.05:3.5, 0.05:4, 0.0.5:4.5, 0.05:5, 0.05:5.5, 0.05:6, 0.05:6.5, 0.15:6, 0.25:6.5, 4.0:6, 4.5:6.5, etc. Within the above ratio range, the core to the organic additive can form a stable composite material with better electrolyte retention.

[0048] In some embodiments, the outer shell can absorb and swell the electrolyte at a first temperature and release the electrolyte and the organic additive under the action of an external force and / or at a second temperature, the second temperature being greater than the first temperature. In some embodiments, the first temperature is between 10°C and 60°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C. In some embodiments, the second temperature is between 20°C and 70°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C. The first temperature within this range allows the composite material to absorb the electrolyte at a lower temperature, matching the temperature range currently used in electrolyte preparation. The second temperature within this range facilitates the release of the electrolyte and organic additive during the battery's injection and high-temperature infiltration processes, providing compatibility with existing processes and making it easier to implement.

[0049] In a second aspect of this application, a method for preparing a composite material is provided, comprising: mixing an organic additive and a core to obtain a mixture; aging the mixture to obtain an aged product in which the organic additive is coated on the core surface; and calcining the aged product to obtain the composite material. Specifically, the organic additive can react with groups on the core surface to form ionic bonds, covalent bonds, or intermolecular forces, thereby coating the core surface with the organic additive. The calcination step effectively removes volatile components such as solvents from the aged product, resulting in a high-quality composite material. This method is simple to operate, operates under mild conditions, and is suitable for large-scale production.

[0050] In some embodiments, mixing the organic additive with the core comprises: mixing and dissolving 0 to 8 parts by weight of 4,4'-dichloromethylbiphenyl, 0 to 8 parts by weight of triethyl phosphite, and 0 to 8 parts by weight of a nitrile compound under magnetic stirring, adding the core to the organic additive in a mass ratio of 0.05 to 4.5:0.05 to 6.5, and ultrasonically treating the core for 0.1 to 1 hour (e.g., 0.2 hours, 0.4 hours, 0.6 hours, 0.8 hours, or 1 hour) to obtain the mixture, wherein the weight ratios of 4,4'-dichloromethylbiphenyl, triethyl phosphite, and the nitrile compound are not all zero. Thus, the organic additive and the core can be evenly mixed, facilitating coating of the organic additive on the surface of the core.

[0051] In some embodiments, a solvent is added to the mixture under magnetic stirring. For example, an alkaline solvent can be added dropwise to the mixture to promote a more complete reaction.

[0052] In some embodiments, the solvent includes anhydrous ethanol and aqueous ammonia, wherein the volume ratio of the anhydrous ethanol to the aqueous ammonia is 0.2-6:0.1-2.0. For example, the volume ratio of the anhydrous ethanol to the aqueous ammonia can be 1:0.5, 2:0.5, 3:0.5, 4:0.5, or 5:0.5. This facilitates full contact and interaction between the organic additive and the core, thereby allowing the organic additive to be fully coated on the surface of the core, thereby obtaining a composite material with better coating quality.

[0053] In some embodiments, the aging treatment is performed at room temperature for 0.5 to 6 hours (e.g., 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours). This time range allows the organic additive to be well coated on the surface of the core to form a core-shell composite material. If the time is too short, the coating effect may be poor, and if the time is too long, it may waste time and reduce efficiency.

[0054] In some embodiments, the solution after the aging treatment is subjected to solid-liquid separation, and the resulting solid product is washed 2 to 6 times (such as 2 times, 3 times, 4 times, 5 times or 6 times) with distilled water and anhydrous ethanol, respectively, and dried at 20 to 90° C. (such as 20° C., 30° C., 40° C., 50° C., 60° C., 70° C., 80° C. or 90° C., etc.) for 2 h to 8 h (such as 2 h, 3 h, 4 h, 5 h, 6 h, 7 h or 8 h, etc.). In this way, the obtained product can contain fewer impurities, and the operation is simple and convenient, and easy to implement. In some embodiments, solid-liquid separation is performed by centrifugation.

[0055] In some embodiments, the calcination includes heating to 20°C to 800°C (e.g., 20°C, 100°C, 180°C, 260°C, 340°C, 420°C, 500°C, 580°C, 640°C, 72°C, or 800°C) and calcining for 2h to 8h (e.g., 2h, 4h, 6h, or 8h). Specifically, the heating rate can be 0.01°C / min to 6°C / min (e.g., 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or 6°C / min). Specifically, the calcination operation can be performed using a muffle furnace. In this way, volatile components in the aged product can be effectively removed, resulting in a composite material with better quality and fewer impurities.

[0056] According to an embodiment of the present application, the core may be prepared using a hydrothermal method.

[0057] In some embodiments, the core is titanium dioxide particles, which can be prepared by a hydrothermal method. The steps of preparing the titanium dioxide particles include: mixing a titanium source, a pH adjuster, and a solvent to obtain a first mixture; mixing the first mixture with an acid to obtain a second mixture; and heat-treating the second mixture followed by solid-liquid separation to obtain the titanium dioxide particles.

[0058] In some embodiments, the specific preparation steps of titanium dioxide particles include: mixing 0.05 to 2.0 parts by weight of a titanium source, 0.02 to 3.0 parts by weight of a pH adjuster, and deionized water to obtain a first mixture.

[0059] In some embodiments, the first mixture and the acid are mixed according to a molar ratio of titanium element to hydrogen element in the acid of 0.35 to 0.5:1 (such as 0.35:1, 0.45:1 or 0.5:1, etc.), and the second mixture is obtained when the solution becomes clear.

[0060] In some embodiments, the second mixture is heated to 20°C to 200°C (such as 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, 180°C or 200°C, etc.) and kept warm for 4h to 20h (such as 4h, 8h, 10h, 12h, 14h, 16h, 18h or 20h, etc.); the solid product is separated to obtain the titanium dioxide particles. Specifically, the heating rate can be 5°C / min to 10°C / min (such as 5°C / min, 5.5°C / min, 6°C / min, 8°C / min or 10°C / min, etc.); specifically, the titanium source reacts with water under the above reaction conditions to generate titanium dioxide (taking the titanium source as titanyl sulfate as an example, the specific reaction process is: TiOSO4+2H2O→TiO2+H2SO4). The titanium dioxide particles prepared by this method have nanometer-scale particle size, are not easy to agglomerate, have good stability, and are easier to form a core-shell structured composite material.

[0061] Specifically, the second mixture can be reacted in a reactor lined with tetrafluoroethylene; thereby, no side reactions occur with the reactants (such as HF), and the reactor has good sealing properties, which is conducive to the reaction. In some embodiments, the solid product can be separated by filtration and washed with ethanol and deionized water.

[0062] It is understood that the method for preparing the composite material may include: preparing a core by a hydrothermal method, and then coating the core surface with an organic additive to form a shell. Figure 4 .

[0063] In some embodiments, the titanium source includes at least one of titanyl sulfate, tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, titanium chloride, titanium nitrate, and titanium oxalate; as an example, the titanium source is titanyl sulfate.

[0064] In some embodiments, the pH adjuster includes at least one of urea, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonia water. For example, the pH adjuster includes urea. Urea decomposes during heating to produce ammonia (NH3) and carbon dioxide (CO2). Ammonia gas dissolves in water to form ammonia water, which can act as an alkaline substance to adjust the pH of the solution, facilitating the control of the acidity and alkalinity of the hydrothermal reaction system and effectively obtaining titanium dioxide particles.

[0065] In some embodiments, the solvent includes deionized water.

[0066] In some embodiments, the acid includes at least one of hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, tartaric acid, and citric acid. For example, the acid includes hydrofluoric acid. Hydrofluoric acid can dissolve certain insoluble impurities, such as metal oxides or hydroxides, formed during the titanyl sulfate preparation process. It can also form complexes with certain metal ions in the solution. These complexes can dissolve in the solution, thereby reducing suspended matter and precipitation, helping to make the solution clearer and promoting efficient reaction.

[0067] In a third aspect of the present application, an electrolyte composition is provided, comprising gel particles and a first electrolyte, wherein the gel particles comprise the composite material and a second electrolyte contained in the composite material, wherein the composite material comprises the composite material described above or a composite material prepared by the preparation method described above. The appearance of the gel particles can be seen in Figure 1 , the cross-section of the gel particles can be found in Figure 2 .

[0068] Specifically, in the electrolyte composition, the shell and / or core of the composite material can absorb the electrolyte and swell, thereby forming gel particles. Under the action of the injection needle force, the gel particles can release the electrolyte and organic additives in the shell and / or core. When the battery enters the high-temperature infiltration process, under the action of temperature, the shell and / or core ruptures to release the electrolyte and organic additives and reacts chemically with HF and water to form hydrogen bonds and ionic bonds, which can effectively inhibit the occurrence of electrolyte side reactions and improve the long-cycle performance of the battery. The process of injecting the electrolyte composition into the battery outer packaging and the high-temperature infiltration process can be found in Figure 3 .

[0069] In some embodiments, the composite material has a mass percentage of 0.05% to 40.5% based on the total mass of the gel particles, specifically 0.05%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc. Within this range, the composite material can effectively absorb electrolyte to form gel particles, which can then slowly release electrolyte and organic additives during subsequent battery injection and high-temperature impregnation processes, thereby improving battery performance.

[0070] In some embodiments, both the first and second electrolytes include a solvent and an electrolyte salt. The solvent includes at least one of propylene carbonate, diethyl carbonate, tetrahydrofuran, dimethyl carbonate, and ethylene carbonate; and / or the electrolyte salt includes at least one of LiPF6, LiBOB, and LiTFSI. These solvents and electrolyte salts exhibit superior ion conductivity, stability, and compatibility with positive and negative electrode materials, improving the overall performance of the battery.

[0071] In a fourth aspect of the present application, a method for preparing an electrolyte composition is proposed, comprising: providing a composite material, wherein the composite material is the composite material described above or a composite material prepared by the method described above; mixing the composite material with a second electrolyte to obtain gel particles; and mixing the gel particles with the first electrolyte to obtain the electrolyte mixture. This method can simply and quickly prepare an electrolyte composition, and the gel particles in the electrolyte composition can slowly release the electrolyte and organic additives during the injection and high-temperature infiltration stages of the battery, effectively alleviating the impedance increase caused by the organic additives, thereby increasing the battery's service life.

[0072] It is understood that the first electrolyte and the second electrolyte may be the same or different. In some embodiments, the first electrolyte and the second electrolyte are the same. In this case, during the preparation of the electrolyte composition, the composite material and the electrolyte (the amount used is the sum of the amounts of the first electrolyte and the second electrolyte) can be directly mixed to obtain the electrolyte composition. Therefore, in some embodiments, the first electrolyte and the second electrolyte are the same and are defined as a third electrolyte. The method includes: mixing the composite material and the third electrolyte to obtain the electrolyte composition.

[0073] According to an embodiment of the present application, the mass ratio of the composite material to the second electrolyte is 0.05-40.5:59.5-99.5, specifically 0.05:99.5, 10:90, 20:80, 30:70, 40.5:59.5, etc.

[0074] In the fifth aspect of this application, a battery is provided, comprising the aforementioned electrolyte composition, or an electrolyte composition prepared using the aforementioned method. It should be noted that the features and effects described for the electrolyte composition of the third aspect of this application also apply to the battery of the fifth aspect of this application and will not be further elaborated here. Overall, the battery exhibits good long-cycle performance and low impedance, resulting in excellent overall performance.

[0075] It can be understood that there is no special restriction on the specific type of the battery, which can be a primary battery or a secondary battery (including but not limited to lithium-ion batteries, sodium-ion batteries, etc.); the shape of the battery can be a cylindrical battery or a square battery, and the outer packaging classification can be a hard shell battery, a soft pack battery, etc.

[0076] Typically, a battery comprises a positive electrode, a negative electrode, the aforementioned electrolyte composition, and a separator. During the battery's charge and discharge processes, active ions are intercalated and released between the positive and negative electrodes. The electrolyte composition conducts ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0077] In the sixth aspect of the present application, an electrical device is provided, comprising the aforementioned battery. It should be noted that the features and effects described for the battery in the fifth aspect of the present application are also applicable to the electrical device, and will not be described in detail here.

[0078] According to an embodiment of the present application, the battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (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, satellites, energy storage systems, etc.

[0079] The embodiments of the present application are described in detail below.

[0080] Example 1

[0081] 1. Preparation of organic additives

[0082] The raw materials include the following parts by weight: 5 parts by weight of 4,4'-dichloromethylbiphenyl, 3 parts by weight of triethyl phosphite and 3 parts by weight of a nitrile compound (ethylene glycol dipropionitrile ether), which are uniformly mixed according to the mass ratio and set aside.

[0083] 2. Preparation of Titanium Dioxide

[0084] Dissolve 1.5 parts by weight of titanyl sulfate and 2 parts by weight of urea in 50 parts by volume of deionized water and stir evenly for 30 minutes;

[0085] Different amounts of hydrofluoric acid (1.35 parts by volume, corresponding to an nTi / nH ratio of 0.40) were slowly added dropwise to the above solution and stirred for about 30 minutes until the solution became clear.

[0086] The above solution was transferred to a 100 mL tetrafluoroethylene-lined reactor, and the temperature was programmed to 180°C at 10°C / min and kept at this temperature for 8 h.

[0087] After cooling, the obtained product was filtered, washed with ethanol 5 times, and then washed with deionized water 4 times. The sample was placed in a vacuum drying oven and dried at 50° C. for 24 h to obtain a TiO2 nanocompound.

[0088] 3. Preparation of Electrolyte

[0089] In a glove box filled with high-purity argon, measure propylene carbonate PC and diethyl carbonate DME in a volume ratio of 1:1, mix them evenly, add LiPF6 to a concentration of 1 mol / L, and take the electrolyte mass as 100%, mix them evenly and set aside.

[0090] 4. Preparation of Composite Materials

[0091] Under magnetic stirring, 5 parts by weight of the organic additive and 20 parts by weight of the TiO2 nanocompound prepared above were mixed and ultrasonically treated for 1 hour to obtain a dispersion;

[0092] 5 parts by volume of anhydrous ethanol containing 0.5 parts by volume of ammonia solution was added dropwise to the above dispersion under magnetic stirring; and aged at room temperature for 6 hours;

[0093] The aged solution was centrifuged and washed 5 times with distilled water and 5 times with anhydrous ethanol respectively; the washed samples were dried at 60°C for 6 hours;

[0094] The dried sample was placed in a muffle furnace, heated to 30° C. at a heating rate of 6° C. / min, and calcined for 4 h to obtain a composite material.

[0095] The composite material prepared above and 100 parts by weight of an electrolyte were fully mixed under ultrasonic action to obtain an electrolyte composition.

[0096] 5. Preparation of Lithium-ion Battery A

[0097] Lithium iron phosphate (LIFP) was used as the active material, mixed with a conductive agent, activated carbon (Super P), and a binder, polyvinylidene fluoride (PVDF), in a nitrogen-methylpyrrolidone (NMP) solution. The mass ratio of active material, activated carbon (Super P), and binder was 80:10:10, respectively. The positive electrode sheet was then coated and pressed onto aluminum foil to produce the negative electrode. The negative electrode active material was a composite of silicon oxide and artificial graphite, with silicon oxide comprising 5% of the total mass of the negative electrode active material. A mixture of the negative electrode active material, carbon black, sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) was uniformly mixed in a mass ratio of 96.5:0.5:1.2:1.8, coated onto copper foil, and then dried at 90°C to produce the negative electrode sheet. The positive and negative electrodes, along with a ceramic separator, were stacked to form a 1.1Ah soft-pack battery. The electrolyte composition prepared above was then injected and the battery was subjected to charge, discharge, and aging processes to produce the lithium-ion battery S1.

[0098] Example 2

[0099] The same as Example 1, except that the amount of the organic additive is 10 parts by weight, to prepare a lithium ion battery S2.

[0100] Example 3

[0101] Same as Example 1, except that the organic additive includes 5 parts by weight of 4,4'-dichloromethylbiphenyl, 4 parts by weight of triethyl phosphite, and 2 parts by weight of ethylene glycol dipropylene glycol ether; a lithium ion battery S3 is prepared.

[0102] Example 4

[0103] The same as Example 3, except that the amount of the organic additive is 10 parts by weight, and a lithium ion battery S4 is prepared.

[0104] Example 5

[0105] Same as Example 1, except that the organic additive includes 3 parts by weight of 4,4'-dichloromethylbiphenyl, 2 parts by weight of triethyl phosphite, and 1 part by weight of ethylene glycol bis(propylene glycol nitrile) ether; a lithium ion battery S5 is prepared.

[0106] Example 6

[0107] The same as Example 5, except that the amount of the organic additive is 10 parts by weight, and a lithium ion battery S6 is prepared.

[0108] Example 7

[0109] The same as Example 1, except that the nitrile compound is 1,3,6-hexanetrinitrile, and a lithium ion battery S7 is prepared.

[0110] Example 8

[0111] The same as Example 1, except that the nitrile compound is tris(2-cyanoethyl)borate, and a lithium ion battery S8 is prepared.

[0112] Examples 9 to 29

[0113] Same as Example 1, specific differences are shown in Table 1.

[0114] Comparative Example 1

[0115] The same as Example 1, except that no composite material was used, and the electrolyte was directly used as the electrolyte composition of the lithium ion battery to prepare a lithium ion battery RS1.

[0116] Comparative Example 2

[0117] The same as Example 1, except that no composite material was used, and 5 parts by weight of the organic additive (same as Example 1) was directly added to 100 parts by weight of the electrolyte to form the electrolyte composition for the lithium ion battery. A lithium ion battery RS2 was prepared.

[0118] Comparative Example 3

[0119] The same as Example 3, except that no composite material was used, and 5 parts by weight of the organic additive was directly added to 100 parts by weight of the electrolyte to form the electrolyte composition for the lithium ion battery, thereby preparing the lithium ion battery RS3.

[0120] Comparative Example 4

[0121] The same as Example 5, except that 5 parts by weight of the organic additive was directly added to 100 parts by weight of the electrolyte to form the electrolyte composition for the lithium ion battery, thereby preparing a lithium ion battery RS4.

[0122] Table 1 Parameter settings for each embodiment and comparative example

[0123]

[0124]

[0125] The cycle performance, internal resistance and composition of the batteries obtained in Examples 1 to 29 and Comparative Examples 1 to 4 were tested. The test methods are shown below, and the test results are shown in Tables 2 and 3.

[0126] 1. Cycle performance test:

[0127] The above battery was pre-cycled: constant current and constant voltage charging was performed at 25°C, after charging to 3.5V at a constant current of 0.03C, it was then charged to 3.8V at a constant current of 0.5C. After the pre-cycle, the air bag part was cut off in an inert gas glove box, and the battery was finally sealed. After final sealing, a charge and discharge cycle test was performed in a constant temperature box at 25°C. Specifically, within the range of 2.0-3.8V, the battery was first charged to 3.8V at 0.1C, and after standing for 1 minute, it was discharged at a constant current of 0.1C, with a cut-off voltage of 2.0V. This was considered a cycle, and other conditions remained unchanged for 300 cycles. The capacity retention rate after 300 cycles was calculated. The results are shown in Table 1.

[0128] Capacity retention after 300 cycles = (discharge capacity after corresponding number of cycles / discharge capacity of the first cycle) × 100%.

[0129] 2. Internal resistance test

[0130] The batteries obtained in the examples and comparative examples were subjected to one charge-discharge cycle test at room temperature at a charge-discharge rate of 3 C / 10 s and a time of 3 C / 10 s, and the battery internal resistance T was recorded. The recorded results are shown in Table 2.

[0131] 3. Component analysis test

[0132] The batteries obtained in the Examples and Comparative Examples were disassembled in an inert gas glove box to remove the residual electrolyte. The samples were diluted with ethyl acetate to an appropriate dilution, and 1 μL was aspirated with a microsyringe for nuclear magnetic resonance (NMR) analysis. The results are recorded in Table 3.

[0133] The test results of the above experiment are shown in the following table:

[0134] Table 2 Test results of capacity retention and internal resistance of each embodiment and comparative example

[0135]

[0136]

[0137] It can be seen from the test results in Table 1 above that by comparing Examples 1 to 29 and Comparative Examples 1 to 4, it can be found that the capacity retention rate of the comparative example battery is low and the internal resistance is large, while the battery using the electrolyte composition containing the composite material of the present application has a better capacity retention rate and internal resistance than the comparative example, indicating that the electrolyte composition of the present application can effectively reduce the interfacial impedance of the battery and improve the cycle performance of the battery.

[0138] Table 3 Analysis and test results of organic additive components in various embodiments and comparative examples

[0139]

[0140]

[0141] Note: The substance contents in Table 3 are the mass percentages in the electrolyte.

[0142] As can be seen from the test results in Table 3 above, by comparing Examples 1 to 29 with Comparative Examples 1 to 4, it can be found that the electrolyte composition of the present invention can be detected at the product end, and the content of each organic additive is higher than that of the comparative example, further indicating that the composite material with this structural design effectively releases the organic additives in the subsequent process and plays a role.

[0143] In general, the composite material and electrolyte composition provided in this application change the traditional method of mixing, adding and releasing organic additives in composite electrolytes, so that the electrolyte and organic additives are gradually released, giving full play to the advantages of each component of the organic additives, thereby reducing the impedance of the battery and improving the cycle performance.

[0144] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0145] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0146] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A composite material, characterized in that include: kernel; The shell is coated on the surface of the core, and the shell includes an organic additive, and the organic additive includes at least one of 4,4'-dichloromethylbiphenyl, triethyl phosphite and a nitrile compound.

2. The composite material according to claim 1, characterized in that The core includes at least one of titanium dioxide particles and polyvinyl pyrrolidone particles.

3. The composite material according to claim 1 or 2, characterized in that The organic additives include 4,4'-dichloromethylbiphenyl, triethyl phosphite and nitrile compounds.

4. The composite material according to claim 3, characterized in that The mass ratio of the 4,4'-dichloromethylbiphenyl, triethyl phosphite and nitrile compound is 0.1-8:0.1-8:0.1-8.

5. The composite material according to any one of claims 1 to 4, characterized in that The nitrile compound includes at least one of ethylene glycol dipropionitrile, 1,3,6-hexanetrinitrile, 1,3,5-pentanetrinitrile, tris(2-cyanoethyl)borate and 3-(trifluoromethyl)benzoylacetonitrile.

6. The composite material according to any one of claims 1 to 5, characterized in that The mass ratio of the core to the organic additive is 0.05-4.5:0.05-6.

5.

7. The composite material according to any one of claims 1 to 6, characterized in that The shell can absorb the electrolyte to swell at a first temperature, and can release the electrolyte and the organic additive under the action of an external force and / or at a second temperature, where the second temperature is higher than the first temperature.

8. The composite material according to claim 7, characterized in that The first temperature is 10°C to 60°C; and / or the second temperature is 20°C to 70°C.

9. A method for preparing the composite material according to any one of claims 1 to 8, characterized in that: include: mixing the organic additive and the core to obtain a mixture; performing an aging treatment on the mixture to obtain an aging product in which the organic additive is coated on the surface of the core; The aged product is calcined to obtain the composite material.

10. The method according to claim 9, characterized in that Meet at least one of the following conditions: (1) The organic additive and the core are mixed to obtain a mixture comprising: Under magnetic stirring, 0 to 8 parts by weight of 4,4'-dichloromethyl biphenyl, 0 to 8 parts by weight of triethyl phosphite, and 0 to 8 parts by weight of a nitrile compound are mixed, the core is added according to a mass ratio of the core to the organic additive of 0.05 to 4.5:0.05 to 6.5, and ultrasonic treatment is performed for 0.1 to 1 hour to obtain a mixture; wherein the weight parts of the 4,4'-dichloromethyl biphenyl, triethyl phosphite, and the nitrile compound are not all 0; (2) Mixing the organic additive and the core to obtain a mixture further includes adding a solvent to the mixture and mixing, wherein the solvent includes anhydrous ethanol and ammonia water, and the volume ratio of the anhydrous ethanol to the ammonia water is 0.2-6:0.1-2; (3) The aging treatment is performed at room temperature for 0.5 h to 6 h; (4) performing solid-liquid separation on the aged product, washing the obtained solid product with distilled water and anhydrous ethanol for 2 to 6 times respectively, and drying at 20° C. to 90° C. for 2 h to 8 h; (5) The calcination treatment includes: heating to 20°C to 800°C and calcining for 2h to 8h.

11. The method according to claim 9 or 10, wherein the core comprises titanium dioxide particles, and the steps of preparing the titanium dioxide particles comprise: mixing a titanium source, a pH adjuster, and a solvent to obtain a first mixture; combining the first mixture and an acid to obtain a second mixture; The second mixture is subjected to heat preservation treatment and then solid-liquid separation to obtain the titanium dioxide particles.

12. The method according to claim 11, characterized in that Meet at least one of the following conditions: (1) mixing 0.05 to 2.0 parts by weight of a titanium source, 0.02 to 3.0 parts by weight of a pH adjuster, and a solvent to obtain a first mixture; (2) mixing the first mixture and the acid, and waiting for the solution to become clear to obtain a second mixture; the molar ratio of the titanium element in the first mixture to the hydrogen element in the acid is 0.35 to 0.5:1; (3) The heat preservation treatment includes: heating the second mixture to 20°C to 200°C and keeping the temperature for 4 hours to 20 hours.

13. The method according to claim 11 or 12, characterized in that Meet at least one of the following conditions: The titanium source comprises at least one of titanyl sulfate, tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, titanium chloride, titanium nitrate and titanium oxalate; The solvent includes deionized water; The pH regulator includes at least one of urea, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and ammonia water; The acid includes at least one of hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, oxalic acid, tartaric acid and citric acid.

14. An electrolyte composition, characterized in that include: Gel particles and a first electrolyte, the gel particles comprising a composite material and a second electrolyte contained in the composite material, the composite material comprising the composite material according to any one of claims 1 to 8 or a composite material prepared by the preparation method according to any one of claims 9 to 13.

15. The electrolyte composition according to claim 14, characterized in that Based on the total mass of the gel particles, the mass percentage of the composite material is 0.05% to 40.5%.

16. The electrolyte composition according to claim 14 or 15, characterized in that The first electrolyte and the second electrolyte both include a solvent and an electrolyte salt, The solvent comprises at least one of propylene carbonate, diethyl carbonate, tetrahydrofuran, dimethyl carbonate, and ethylene carbonate; and / or The electrolyte salt includes at least one of lithium hexafluorophosphate, lithium bis(oxalatoborate), and lithium bis(trifluoromethanesulfonyl)imide.

17. A method for preparing the electrolyte composition according to any one of claims 14 to 16, characterized in that: include: A composite material is provided, wherein the composite material is the composite material according to any one of claims 1 to 8 or the composite material prepared by the method according to any one of claims 9 to 13; mixing the composite material with a second electrolyte to obtain the gel particles; The gel particles and the first electrolyte are mixed to obtain the electrolyte mixture.

18. The method according to claim 17, characterized in that The first electrolyte and the second electrolyte are the same and are defined as a third electrolyte, and the method includes: The composite material and the third electrolyte are mixed to obtain the electrolyte composition.

19. The method according to claim 17, wherein The mass ratio of the composite material to the second electrolyte is 0.05-40.5:59.5-99.

5.

20. A battery, characterized in that: The invention comprises the electrolyte composition according to any one of claims 14 to 16 or the electrolyte composition prepared by the method according to any one of claims 17 to 19.

21. An electrical device, characterized in that: Comprising the battery of claim 20.

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