A quick-charging lithium ion battery electrolyte and a preparation method thereof

Abstract

The application relates to the technical field of lithium ion battery electrolyte, and discloses a fast-charging type lithium ion battery electrolyte and a preparation method thereof, which comprises the following raw materials in parts by mass: 12-15 parts of lithium salt, 1-2 parts of a composite additive, 0.5-1 part of a film forming agent, 0.3-0.5 part of an anti-explosion agent, 0.5-0.7 part of an acid and water removing agent and 75-80 parts of an organic solvent. The multilayer structure in the composite additive can participate in the formation of a solid electrolyte phase interface (SEI) film, so that the multilayer structure serves as a physical barrier of the SEI film, effectively blocks or inhibits the irreversible parasitic reaction of lithium metal and solvent, guarantees the uniformity of the surface charge distribution of the negative electrode, and the high lithium ion transmission can reduce the interface impedance of the SEI film, promote the rapid transmission of lithium ions, and further inhibit the growth of lithium dendrites.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery electrolyte technology, specifically to a fast-charging lithium-ion battery electrolyte and its preparation method. Background Technology

[0002] Lithium-ion batteries consist of a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte is usually liquid, also known as the electrolyte solution. In lithium-ion batteries, the electrolyte solution plays the role of conducting electrons. During this process, the reciprocating motion of lithium ions in the electrolyte solution is figuratively called the "rocking chair" battery effect. To achieve fast charging of lithium-ion batteries, the key is to improve the lithium-ion transport efficiency. The quality of the electrolyte solution directly affects the overall performance of the lithium-ion battery. Therefore, a good electrolyte solution should meet the requirements of good chemical stability, high ionic conductivity, wide temperature range, and safety and non-toxicity.

[0003] Lithium-ion battery electrolyte is a mixture of lithium salt, organic solvent and additives. It plays the role of conducting ions between the positive and negative electrodes of the lithium battery, enabling the lithium-ion battery to have high voltage, high specific energy and high electrochemical performance. However, the reaction between the metallic lithium negative electrode and the electrolyte forms lithium dendrites, which can cause internal short circuits in the lithium-ion battery, release a large amount of heat, and pose a risk of thermal runaway and ignition of the electrolyte, thus affecting the battery's charge and discharge performance. Summary of the Invention

[0004] This invention provides a fast-charging lithium-ion battery electrolyte and its preparation method, which solves the problems of poor adhesion between organosilicon waterproofing agents and fabrics, as well as poor washability and weather resistance.

[0005] The technical solution of the present invention:

[0006] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 12-15 parts lithium salt, 1-2 parts composite additives, 0.5-1 part film-forming agent, 0.3-0.5 parts explosion-proof agent, 0.5-0.7 parts acid and water removal agent, and 75-80 parts organic solvent;

[0007] The composite additive is obtained by mixing and reacting modified inorganic layered materials, alumina whiskers, tannic acid and organosilicon.

[0008] The modified inorganic layered material is obtained by surface-treating carboxymethyl cellulose with sheet graphene oxide, intercalating montmorillonite, and then reacting it with zinc salt and dimethylimidazole.

[0009] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0010] S1. Add lithium salt to organic solvent and stir at 100-150 r / min for 30-40 min to obtain premix;

[0011] S1. Mix the composite additive, film-forming agent and premixed liquid evenly, add explosion-proof agent and deacidifying and dehydrating agent, mix evenly to obtain electrolyte.

[0012] Furthermore, the lithium salt is selected from any one of lithium hexafluorophosphate, lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium di(oxalato)borate, and lithium di(fluorosulfonyl)imide.

[0013] Furthermore, the film-forming agent is selected from any one of vinylene carbonate, vinyl sulfate, fluorovinyl carbonate, and propane-carbonate lactone.

[0014] Furthermore, the explosion retardant is selected from ethylene sulfate or vinylene sulfate.

[0015] Furthermore, the acid and water removal agent is selected from any one of dicyclohexylcarbodiimide, hexamethyldisilazane, and heptamethyldisilazane.

[0016] Furthermore, the organic solvent is selected from any one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, and dimethyl carbonate.

[0017] Furthermore, the composite additive is prepared by the following steps:

[0018] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred until the reaction was complete. Montmorillonite was added and ultrasonically treated at 40-60KHz. After filtration, washing and drying, an inorganic layered material was obtained.

[0019] A2. Add zinc nitrate hexahydrate and dimethylimidazole to methanol and stir until completely dissolved. Add inorganic layered material, purge with nitrogen, and stir at 60-70℃ for 3-5 hours. Collect the product by centrifugation, wash the product, and dry it to obtain the modified inorganic layered material.

[0020] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir evenly. Add alumina whiskers and continue stirring. Add organosilicon and stir evenly. Add hydrochloric acid and stir until the reaction is complete. After filtration, washing, and drying, obtain the composite additive.

[0021] Furthermore, during the A1 reaction process described above, carboxymethyl cellulose dissolves in deionized water to form a solution with adhesive properties, which allows carboxymethyl cellulose to adhere to the surface of sheet graphene oxide, thus obtaining functionalized sheet graphene oxide.

[0022] After ultrasonic treatment, the interlayer bonding force of montmorillonite is weakened, allowing functionalized sheet graphene oxide to be intercalated into the interlayer of montmorillonite, thereby increasing the interlayer spacing of montmorillonite while preserving the layered structure of montmorillonite, resulting in an inorganic layered material.

[0023] Furthermore, during the A2 reaction process described above, the hydroxyl groups on the surface of the inorganic layered material can combine with zinc ions in zinc nitrate hexahydrate, causing zinc ions to be deposited on the surface of the inorganic layered material. 2-Methylimidazole acts as an organic ligand, and the zinc ions react with the organic ligand to form a zinc-based metal-organic framework on the surface of the inorganic layered material, thus obtaining the modified inorganic layered material.

[0024] Furthermore, in the A3 reaction process described above, tannic acid acts as a binder, allowing the composite to be deposited onto the surface of alumina whiskers via tannic acid deposition; the remaining tannic acid acts as a crosslinking agent, causing the organosilicon trimethylethoxysilane to undergo a hydrolysis-condensation reaction. During the reaction, the silanol groups contained therein can undergo a crosslinking reaction with tannic acid to form a crosslinked network structure of organosilicon resin, allowing the modified inorganic layered material to be embedded in the organosilicon resin network structure as a composite additive.

[0025] Further, in step A1, the mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide and montmorillonite is (0.5-1):(60-70):(2.5-3):(2-2.5).

[0026] Further, in step A2, the mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol and inorganic layered material is (1-1.5):(2-3):(45-50):(3.5-4).

[0027] Further, in step A3, the mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, organosilicon and hydrochloric acid is (0.8-1.2):(35-45):(1-1.5):(2-2.2):(1-1.4):(1-2).

[0028] Furthermore, the sheet-like graphene oxide has a sheet diameter of 0.5-1 μm.

[0029] Furthermore, the montmorillonite is sodium-based montmorillonite with a particle size of 1-2 µm.

[0030] Furthermore, the alumina whiskers have a diameter of 2-5 μm and a length of 10-15 μm.

[0031] Furthermore, the organosilicon is trimethylethoxysilane.

[0032] The present invention has the following beneficial effects:

[0033] (1) In the technical solution of the present invention, after functionalizing the sheet graphene oxide on the surface of carboxymethyl cellulose, montmorillonite is then intercalated. On the one hand, the functionalized sheet graphene oxide intercalates into the interlayer of montmorillonite to form a multilayer structure. Lithium ions can increase the migration number of lithium ions through interlayer ion exchange, thereby improving the charge and discharge performance of the battery. On the other hand, the multilayer structure can participate in the formation of the solid electrolyte interphase (SEI) film, so that the multilayer structure acts as a physical barrier of the SEI film, effectively blocking or inhibiting the irreversible parasitic reaction between lithium metal and solvent, ensuring the uniformity of charge distribution on the surface of the negative electrode, and the high lithium ion transport can reduce the interfacial impedance of the SEI film, promote the rapid transport of lithium ions, and thus inhibit the growth of lithium dendrites. In addition, the carboxyl groups contained in the carboxymethyl cellulose in the interlayer improve the adsorption performance of lithium ions, further increase the migration number of lithium ions, and thus improve the charge and discharge performance of the battery.

[0034] (2) In the technical solution of the present invention, a zinc-based metal-organic framework is formed on the surface of an inorganic layered material. On the one hand, the formed zinc-based metal-organic framework has a porous structure and lithium-loving properties, which can reduce the nucleation potential of lithium metal, realize the uniform deposition of lithium ions at the zinc-based metal-organic framework, effectively inhibit the formation and growth of lithium dendrites, and improve the charging and discharging performance of the battery. On the other hand, the porous structure of the zinc-based metal-organic framework can adsorb electrolyte components, so that the inorganic materials are uniformly dispersed in the electrolyte, and reduce electrolyte leakage, thereby improving the safety of the battery. In addition, the zinc-based metal-organic framework and the inorganic layered material have good mechanical properties and thermal stability, which, as the framework of the electrolyte, reduce the deformation and expansion of the battery cell.

[0035] (3) In the technical solution of the present invention, tannic acid is used as a binder, so that the composite is deposited on the surface of alumina whiskers through tannic acid. On the one hand, alumina whiskers have excellent aspect ratio, which can load more modified inorganic layered materials, further improving the dispersibility of inorganic layered materials in electrolyte. On the other hand, alumina whiskers are randomly distributed on the surface of negative electrode material, serving as the skeleton of the SEI film, increasing the migration number of lithium ions, suppressing lithium dendrites, and improving the charge and discharge performance of the battery. The randomly distributed whiskers can also absorb and weaken external stress, improving the mechanical strength of the SEI film.

[0036] The remaining tannic acid acts as a crosslinking agent, and the organosilicon trimethylethoxysilane undergoes a hydrolysis-condensation reaction. During the reaction, the silanol groups can crosslink with the tannic acid to form a crosslinked network structure of organosilicon resin. This allows the modified inorganic layered material to be embedded in the organosilicon resin network structure, improving the compatibility between the composite additive and the electrolyte. This ensures that the composite additive is uniformly dispersed in the electrolyte, and the formed organosilicon crosslinked network structure has good adsorption performance for electrolyte components, which can also reduce electrolyte leakage and improve battery safety. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0039] The lithium salt is lithium hexafluorophosphate, the film-forming agent is vinylene carbonate, the explosion-proof agent is ethylene sulfate, the acid and water removal agent is dicyclohexylcarbodiimide, and the organic solvent is ethylene carbonate.

[0040] The four needle-like zinc oxide whiskers, with a diameter of 1 μm and a length of 10 μm, were purchased from Wuhan Kemic Biomedical Technology Co., Ltd.

[0041] The sheet graphene oxide has a sheet diameter of 1 μm; the montmorillonite is sodium-based montmorillonite with a particle size of 1.5 µm; the alumina whiskers have a diameter of 3 μm and a length of 13 μm.

[0042] The organosilicon is trimethylethoxysilane.

[0043] Example 1

[0044] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 12 parts lithium hexafluorophosphate, 1 part composite additive, 0.5 parts vinylene carbonate, 0.3 parts ethylene sulfate, 0.5 parts dicyclohexylcarbodiimide, and 75 parts ethylene carbonate.

[0045] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0046] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 100 r / min for 30 min to obtain a premix;

[0047] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0048] The composite additive is prepared by the following steps:

[0049] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added, and the mixture was stirred and reacted at 60°C for 10 min. Montmorillonite was added, and the mixture was sonicated at 40 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 0.5:60:2.5:2.

[0050] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 60°C for 3 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1:2:45:3.5.

[0051] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70℃ for 40 min. Add alumina whiskers and continue stirring for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60℃ for 1 h. After filtration, wash three times with deionized water and dry in a 70℃ oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, trimethylethoxysilane and hydrochloric acid is 0.8:35:1:2:1:1.

[0052] Example 2

[0053] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 13 parts lithium hexafluorophosphate, 1.5 parts composite additives, 0.8 parts vinylene carbonate, 0.4 parts ethylene sulfate, 0.6 parts dicyclohexylcarbodiimide, and 78 parts ethylene carbonate;

[0054] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0055] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 130 r / min for 35 min to obtain a premix;

[0056] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0057] The composite additive is prepared by the following steps:

[0058] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added, and the mixture was stirred and reacted at 60°C for 10 min. Montmorillonite was added, and the mixture was sonicated at 50 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 0.8:65:2.8:2.3.

[0059] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 65°C for 4 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.3:2.5:48:3.8.

[0060] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70℃ for 40 min. Add alumina whiskers and continue stirring for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60℃ for 1 h. After filtration, wash three times with deionized water and dry in a 70℃ oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, trimethylethoxysilane and hydrochloric acid is 1:40:1.3:2.1:1.2:1.5.

[0061] Example 3

[0062] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0063] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0064] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0065] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0066] The composite additive is prepared by the following steps:

[0067] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred at 60°C for 10 min. Montmorillonite was added and ultrasonically treated at 60 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 1:70:3:2.5.

[0068] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 70°C for 5 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.5:3:50:4.

[0069] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70°C for 40 min. Add alumina whiskers and continue stirring for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60°C for 1 h. After filtration, wash three times with deionized water and dry in a 70°C oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, trimethylethoxysilane, and hydrochloric acid is 1.2:45:1.5:2.2:1.4:2.

[0070] Comparative Example 1

[0071] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0072] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0073] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0074] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0075] The composite additive is prepared by the following steps:

[0076] A1. Mix deionized water and sheet graphene oxide, stir evenly, add montmorillonite, sonicate at 60 kHz for 10 min, filter, wash 3 times with deionized water, and dry in an oven at 70 ℃ for 10 min to obtain inorganic layered material; the mass ratio of deionized water, sheet graphene oxide and montmorillonite is 70:4:2.5.

[0077] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 70°C for 5 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.5:3:50:4.

[0078] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70°C for 40 min. Add alumina whiskers and continue stirring for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60°C for 1 h. After filtration, wash three times with deionized water and dry in a 70°C oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, trimethylethoxysilane, and hydrochloric acid is 1.2:45:1.5:2.2:1.4:2.

[0079] Comparative Example 2

[0080] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0081] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0082] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0083] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0084] The composite additive is prepared by the following steps:

[0085] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Montmorillonite was added, and the mixture was ultrasonically treated at 60 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70 ℃ for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water and montmorillonite was 1:70:5.5.

[0086] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 70°C for 5 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.5:3:50:4.

[0087] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70°C for 40 min. Add alumina whiskers and continue stirring for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60°C for 1 h. After filtration, wash three times with deionized water and dry in a 70°C oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, trimethylethoxysilane, and hydrochloric acid is 1.2:45:1.5:2.2:1.4:2.

[0088] Comparative Example 3

[0089] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0090] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0091] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0092] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0093] The composite additive is prepared by the following steps:

[0094] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred at 60°C for 10 min. Montmorillonite was added and ultrasonically treated at 60 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 1:70:3:2.5.

[0095] A2. Add tannic acid to deionized water and stir until completely dissolved. Add inorganic layered material and stir at 70°C for 40 min. Add alumina whiskers and continue stirring for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60°C for 1 h. After filtration, wash three times with deionized water and dry in a 70°C oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, inorganic layered material, alumina whiskers, trimethylethoxysilane, and hydrochloric acid is 1.2:45:1.5:2.2:1.4:2.

[0096] Comparative Example 4

[0097] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0098] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0099] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0100] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0101] The composite additive is prepared by the following steps:

[0102] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred at 60°C for 10 min. Montmorillonite was added and ultrasonically treated at 60 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 1:70:3:2.5.

[0103] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 70°C for 5 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.5:3:50:4.

[0104] A3. Deionized water and modified inorganic layered material were stirred at 70℃ for 40 min. Alumina whiskers were added, and stirring was continued for another 40 min. Trimethylethoxysilane was then added and stirred until homogeneous. Hydrochloric acid with a concentration of 1 mol / L was added, and the mixture was stirred at 60℃ for 1 h. After filtration, the mixture was washed three times with deionized water and dried in a 70℃ oven for 10 min to obtain a composite additive. The mass ratio of deionized water, modified inorganic layered material, alumina whiskers, trimethylethoxysilane, and hydrochloric acid was 45:2.7:2.2:1.4:2.

[0105] Comparative Example 5

[0106] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0107] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0108] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0109] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0110] The composite additive is prepared by the following steps:

[0111] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred at 60°C for 10 min. Montmorillonite was added and ultrasonically treated at 60 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 1:70:3:2.5.

[0112] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 70°C for 5 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.5:3:50:4.

[0113] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70℃ for 40 min. Add trimethylethoxysilane and stir evenly. Add 1 mol / L hydrochloric acid and stir at 60℃ for 1 h. After filtration, wash three times with deionized water and dry in a 70℃ oven for 10 min to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, trimethylethoxysilane and hydrochloric acid is 1.2:45:3.7:1.4:2.

[0114] Comparative Example 6

[0115] A fast-charging lithium-ion battery electrolyte comprises the following raw materials in parts by weight: 15 parts lithium hexafluorophosphate, 2 parts composite additives, 1 part vinylene carbonate, 0.5 parts ethylene sulfate, 0.7 parts dicyclohexylcarbodiimide, and 80 parts ethylene carbonate.

[0116] A method for preparing a fast-charging lithium-ion battery electrolyte includes the following preparation steps:

[0117] S1. Add lithium hexafluorophosphate to ethylene carbonate and stir at 150 r / min for 40 min to obtain a premix;

[0118] S1. Mix the composite additive, vinylene carbonate and premixed solution evenly, add ethylene sulfate and dicyclohexylcarbodiimide, mix evenly to obtain the electrolyte.

[0119] The composite additive is prepared by the following steps:

[0120] A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred at 60°C for 10 min. Montmorillonite was added and ultrasonically treated at 60 kHz for 10 min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 70°C for 10 min to obtain an inorganic layered material. The mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide, and montmorillonite was 1:70:3:2.5.

[0121] A2. Zinc nitrate hexahydrate and dimethylimidazole were added to methanol and stirred until completely dissolved. Inorganic layered material was added, nitrogen gas was introduced, and the mixture was stirred at 70°C for 5 hours. The product was collected by centrifugation at 8000 r / min. The product was washed three times with methanol and three times with deionized water, and dried in an oven at 70°C for 12 hours to obtain the modified inorganic layered material. The mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol, and inorganic layered material was 1.5:3:50:4.

[0122] A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir at 70°C for 40 minutes. Add alumina whiskers and continue stirring for 40 minutes. After filtration, wash three times with deionized water and dry in a 70°C oven for 10 minutes to obtain the composite additive. The mass ratio of tannic acid, deionized water, modified inorganic layered material, and alumina whiskers is 1.2:45:2.9:2.2.

[0123] The performance of the electrolytes prepared in Examples 1-3 and Comparative Examples 1-6 was then tested.

[0124] Electrochemical performance testing: Using artificial graphite as the negative electrode material (thickness of 15μm) and lithium metal (Li) as the positive electrode material, coin cells were assembled with the electrolyte prepared above. The cells were charged and discharged at a constant current at a voltage of 3V and a rate of 1C for 100 cycles. The discharge capacity and discharge efficiency at 20℃, 40℃ and 60℃ were recorded.

[0125] As shown in Table 1 below.

[0126] Table 1 Performance testing of electrolytes prepared in Examples 1-3 and Comparative Examples 1-6

[0127]

[0128] As can be seen from the data in Table 1, the electrolytes prepared in Examples 1-3 have high electrochemical performance.

[0129] Comparative Example 1 showed that when carboxymethyl cellulose was replaced by a composite additive made of sheet graphene oxide, its electrochemical performance decreased. This demonstrates that the adhesion of carboxymethyl cellulose to the surface of sheet graphene oxide facilitates the formation of a multilayer structure with carboxyl groups between the layers, which improves the adsorption performance of lithium ions, further increases the lithium ion transport number, and thus improves the charge and discharge performance of the battery. In addition, the higher lithium ion transport can reduce the interfacial impedance of the SEI film, promote the rapid transport of lithium ions, and thus inhibit the growth of lithium dendrites.

[0130] Comparative Example 2 showed that when the same amount of sheet graphene oxide was replaced with a composite additive prepared from montmorillonite and added to the electrolyte, its electrochemical performance decreased. This demonstrates that when functionalized sheet graphene oxide is intercalated into the montmorillonite layers to form a multilayer structure, lithium ions can increase their migration number through interlayer ion exchange, thereby improving the charge and discharge performance of the battery. Furthermore, the multilayer structure can participate in the formation of the solid electrolyte interphase (SEI) film, making the multilayer structure a physical barrier of the SEI film, effectively blocking or inhibiting irreversible parasitic reactions between lithium metal and the solvent, thereby inhibiting lithium dendrite growth.

[0131] Comparative Example 3 showed that replacing the modified inorganic layered material with a composite additive prepared from the inorganic layered material and adding it to the electrolyte resulted in a decrease in electrochemical performance. This demonstrates that a zinc-based metal-organic framework is formed on the surface of the inorganic layered material. The formed zinc-based metal-organic framework has a porous structure and lithium-affinity properties, which can reduce the nucleation potential of lithium metal, achieve uniform deposition of lithium ions at the zinc-based metal-organic framework, effectively inhibit the formation and growth of lithium dendrites, and improve the charge and discharge performance of the battery. Furthermore, the porous structure of the zinc-based metal-organic framework can adsorb electrolyte components, allowing the inorganic material to be uniformly dispersed in the electrolyte. In addition, the zinc-based metal-organic framework and the inorganic layered material have good mechanical properties and thermal stability, serving as the electrolyte framework and reducing cell deformation and expansion.

[0132] In Comparative Example 4, when tannic acid was replaced by a composite additive prepared from modified inorganic layered materials and added to the electrolyte, the electrochemical performance decreased. This demonstrates that tannic acid acts as a binder, allowing the composite to deposit onto the surface of alumina whiskers. Alumina whiskers have an excellent aspect ratio, enabling them to support a larger amount of modified inorganic layered materials, further improving the dispersibility of the inorganic layered materials in the electrolyte, thereby suppressing lithium dendrites and improving the charge-discharge performance of the battery.

[0133] In Comparative Example 5, when aluminum oxide whiskers were replaced by a composite additive prepared from modified inorganic layered materials and added to the electrolyte, the electrochemical performance decreased. This demonstrates that the random distribution of aluminum oxide whiskers on the surface of the negative electrode material serves as the framework for the SEI film, increasing the lithium ion migration number, suppressing lithium dendrites, and improving the charge and discharge performance of the battery. Furthermore, the random distribution of whiskers can also absorb and weaken external stress, thereby improving the mechanical strength of the SEI film.

[0134] In Comparative Example 6, when trimethylethoxysilane was replaced by a composite additive prepared from a modified inorganic layered material, the electrochemical performance of the electrolyte decreased. This demonstrates that the modified inorganic layered material, embedded in the organosilicon resin network structure, improves the compatibility between the composite additive and the electrolyte, allowing the composite additive to be uniformly dispersed in the electrolyte. Furthermore, the formed organosilicon cross-linked network structure exhibits good adsorption performance for electrolyte components, reduces electrolyte leakage, and improves battery safety.

[0135] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0136] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A fast-charging lithium-ion battery electrolyte, characterized in that, The raw materials include the following parts by weight: 12-15 parts lithium salt, 1-2 parts composite additive, 0.5-1 part film-forming agent, 0.3-0.5 parts explosion retardant, 0.5-0.7 parts acid and water removal agent, and 75-80 parts organic solvent; The composite additive is obtained by mixing and reacting modified inorganic layered materials, alumina whiskers, tannic acid and organosilicon. The modified inorganic layered material is obtained by surface-treating carboxymethyl cellulose with sheet graphene oxide, intercalating montmorillonite, and then reacting it with zinc salt and dimethylimidazole.

2. The fast-charging lithium-ion battery electrolyte according to claim 1, characterized in that, The composite additive is prepared by the following steps: A1. Carboxymethyl cellulose was added to deionized water and stirred until completely dissolved. Sheet graphene oxide was added and stirred until the reaction was complete. Montmorillonite was added and ultrasonically treated at 40-60KHz. After filtration, washing and drying, an inorganic layered material was obtained. A2. Add zinc nitrate hexahydrate and dimethylimidazole to methanol and stir until completely dissolved. Add inorganic layered material, purge with nitrogen, and stir at 60-70℃ for 3-5 hours. Collect the product by centrifugation, wash the product, and dry it to obtain the modified inorganic layered material. A3. Add tannic acid to deionized water and stir until completely dissolved. Add modified inorganic layered material and stir evenly. Add alumina whiskers and continue stirring. Add organosilicon and stir evenly. Add hydrochloric acid and stir until the reaction is complete. After filtration, washing, and drying, obtain the composite additive.

3. The fast-charging lithium-ion battery electrolyte according to claim 2, characterized in that, In step A1, the mass ratio of carboxymethyl cellulose, deionized water, sheet graphene oxide and montmorillonite is (0.5-1):(60-70):(2.5-3):(2-2.5).

4. The fast-charging lithium-ion battery electrolyte according to claim 2, characterized in that, In step A2, the mass ratio of zinc nitrate hexahydrate, dimethylimidazole, methanol and inorganic layered material is (1-1.5):(2-3):(45-50):(3.5-4).

5. The fast-charging lithium-ion battery electrolyte according to claim 2, characterized in that, In step A3, the mass ratio of tannic acid, deionized water, modified inorganic layered material, alumina whiskers, organosilicon and hydrochloric acid is (0.8-1.2):(35-45):(1-1.5):(2-2.2):(1-1.4):(1-2).

6. The fast-charging lithium-ion battery electrolyte according to claim 1, characterized in that, The lithium salt is selected from any one of lithium hexafluorophosphate, lithium bis(oxalate)borate, lithium tetrafluoroborate, lithium di(oxalate)borate, and lithium di(fluorosulfonyl)imide.

7. The fast-charging lithium-ion battery electrolyte according to claim 1, characterized in that, The film-forming agent is selected from any one of vinylene carbonate, vinyl sulfate, fluorovinyl carbonate, and propane-carbonate lactone.

8. The fast-charging lithium-ion battery electrolyte according to claim 1, characterized in that, The explosion-proof agent is selected from ethylene sulfate or vinylene sulfate; the acid and water removal agent is selected from any one of dicyclohexylcarbodiimide, hexamethyldisilazane, and heptamethyldisilazane.

9. The fast-charging lithium-ion battery electrolyte according to claim 1, characterized in that, The organic solvent is selected from any one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, and dimethyl carbonate.

10. A method for preparing a fast-charging lithium-ion battery electrolyte as described in any one of claims 1-9, characterized in that, The preparation steps include the following: S1. Add lithium salt to organic solvent and stir at 100-150 r / min for 30-40 min to obtain premix; S2. Mix the composite additive, film-forming agent and premixed liquid evenly, add explosion-proof agent and deacidifying and dehydrating agent, mix evenly to obtain electrolyte.

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