High energy density rechargeable lithium ion batteries

Abstract

The application discloses high-energy-density rechargeable lithium ion batteries and belongs to the technical field of lithium ion battery preparation. The high-energy-density rechargeable lithium ion battery is composed of a positive electrode material, a negative electrode material, an electrolyte and a porous polyethylene film. The positive electrode material is prepared from lithium cobaltate, carbon black, polyvinylidene fluoride, N-methylpyrrolidone and an aluminum foil. The negative electrode material is prepared from graphite, a negative electrode material additive, carbon black, carboxymethyl cellulose, deionized water and a copper foil. The electrolyte is prepared from dimethyl carbonate, lithium hexafluorophosphate and an electrolyte additive. The lithium ion battery prepared by the method has high energy density, excellent cycle performance and safety.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery manufacturing technology, specifically relating to high-energy-density rechargeable lithium-ion batteries. Background Technology

[0002] With the rapid development of the global economy and the continuous growth of the population, energy demand is experiencing explosive growth. Traditional fossil fuels, such as coal, oil, and natural gas, are not only limited in resources, but also produce large amounts of carbon dioxide and other greenhouse gases during combustion, leading to serious problems such as global warming and environmental pollution. Lithium-ion batteries, as a highly efficient and environmentally friendly energy storage technology, have emerged and rapidly developed into the mainstay of the energy storage field.

[0003] Lithium-ion batteries possess significant advantages such as high energy density, long cycle life, low self-discharge rate, and no memory effect, and have been widely used in various fields including portable electronic devices, electric vehicles, smart grids, and aerospace. Particularly in the electric vehicle sector, the high energy density of lithium-ion batteries translates to longer driving range and lighter battery weight, which is crucial for enhancing the competitiveness of electric vehicles and promoting the development of the new energy vehicle industry. Furthermore, with the large-scale development and utilization of renewable energy, lithium-ion batteries are increasingly being used in energy storage power stations, becoming a key means of addressing the intermittency and instability issues of renewable energy sources.

[0004] Patent CN110137467A discloses a high-energy-density lithium-ion battery, including a cell and a battery membrane encapsulating the cell. The cell includes a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is located between the positive and negative electrodes, and the electrolyte is placed between the positive electrode and the separator, and between the negative electrode and the separator. The positive electrode includes a positive electrode composite material and a positive electrode current collector, and the negative electrode includes a negative electrode composite material and a negative electrode current collector. This invention can reduce weight, improve initial charge-discharge efficiency, and increase energy density. However, there is still room for improvement in the energy density, cycle performance, and safety of the lithium-ion battery prepared by this method. Summary of the Invention

[0005] The purpose of this invention is to provide a high-energy-density empty-charge lithium-ion battery to solve the technical problems of poor energy density, cycle performance and safety of lithium-ion batteries in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a high-energy-density rechargeable lithium-ion battery, comprising a positive electrode material, a negative electrode material, an electrolyte, and a porous polyethylene film. The positive electrode material is prepared from lithium cobalt oxide, carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and aluminum foil. The negative electrode material is prepared from graphite, negative electrode material additives, carbon black, carboxymethyl cellulose, deionized water, and copper foil. The electrolyte is prepared from dimethyl carbonate, lithium hexafluorophosphate, and electrolyte additives.

[0008] Preferably, the preparation method of the negative electrode material additive includes the following steps:

[0009] Q1: 3,5-Dibromoaniline, 1-bromohexane, tetrabutylammonium bromide, and potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of sodium hydroxide and acetonitrile, the mixture was stirred, extracted, washed, dried, and purified to obtain compound 1; Compound 1, bis(pinacolyl)diboron, potassium acetate, and DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of N,N-dimethylformamide, the mixture was stirred, and after the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2;

[0010] Q2: 2-Bromophenazine, compound 2, potassium carbonate, and tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, tetrahydrofuran, deionized water, and toluene were added. The mixture was stirred in an oil bath, dried, and purified to obtain compound 3. Compound 3 was added to a container containing ethanol, and nitrogen was purged. Then, distilled water containing dissolved sodium dithionite was added to the container, and the mixture was heated to react. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4.

[0011] Q3: Compound 4, 2-bromoanthraquinone, 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, sodium tert-butoxide and tris(dibenzylideneacetone)palladium were added to a container, nitrogen gas was introduced, and then 1,4-dioxane was added. The container was sealed, heated and magnetically stirred to react. After the reaction was completed, the container was cooled, filtered, washed and dried to obtain the negative electrode material additive.

[0012] The synthesis reaction formula for the negative electrode material additive in the above process is as follows:

[0013]

[0014] The mass spectrometry analysis results of compound 1 were: m / z: 419.06 (100.0%), 417.07 (51.4%), 421.06 (48.6%), 420.07 (19.8%), 418.07 (10.2%), 422.07 (9.7%), 421.07 (1.9%), 419.07 (1.0%); the mass spectrometry analysis results of compound 2 were... The results were: m / z: 513.42 (100.0%), 512.42 (42.7%), 514.42 (28.9%), 511.42 (5.3%), 515.42 (5.2%), 514.43 (2.3%), 512.43 (1.8%); The mass spectrometry analysis results for compound 3 were: m / z: 617.35 (100.0%), 618... 0.36 (45.9%), 619.36 (10.3%), 618.35 (1.8%), 620.36 (1.7%); The mass spectrometry analysis results of compound 4 were: m / z: 625.41 (100.0%), 626.42 (46.0%), 627.42 (10.3%), 626.41 (1.8%), 628.42 (1.6%); The mass spectrometry analysis results of the anode material additives were as follows: m / z: 1450.56 (100.0%), 1449.56 (92.7%), 1451.57 (54.2%), 1452.57 (21.1%), 1453.57 (5.8%), 1451.56 (1.8%), 1454.58 (1.3%), 1450.57 (1.1%).

[0015] Preferably, in Q1, the ratio of 3,5-dibromoaniline, 1-bromohexane, tetrabutylammonium bromide, potassium iodide, sodium hydroxide, and acetonitrile is (6.218-6.668) g : (1.024-1.232) g : (0.782-0.866) g : (0.342-0.506) g : (8.564-8.844) g : (18-24) mL, and the stirring reaction temperature is 60-80 °C. The reaction was carried out at 0℃ for 6-8 hours. The ratio of compound 1, bis(pinacol)diboron, potassium acetate, DPPF palladium dichloride, and N,N-dimethylformamide was (1.046-1.15) g : (1.11-1.55) g : (1.212-1.366) g : (0.15-0.23) g : (20-30) mL. The reaction temperature was 90-110℃ and the reaction time was 6-8 hours.

[0016] Preferably, in Q2, the ratio of 2-bromophenazine, compound 2, potassium carbonate, tetra(triphenylphosphine)palladium, tetrahydrofuran, deionized water, and toluene is (0.04-0.06)g:(0.03-0.07)g:(0.06-0.102)g:(0.008-0.014)g:(8-11)mL:(4-8)mL:(8-10)mL, the oil bath stirring temperature is 90-105℃, and the reaction time is 20-24h; the ratio of compound 3, ethanol, sodium dithionite, and distilled water is (3.1-4.1)g:(45-55)mL:(31.2-37.6)g:(100-120)mL, the heating reaction temperature is 80-90℃, and the reaction time is 1-2h.

[0017] Preferably, in Q3, the ratio of compound 4, 2-bromoanthraquinone, 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, sodium tert-butoxide, tris(dibenzylacetone)palladium, and 1,4-dioxane is (0.166-0.208) g : (0.552-0.654) g : (0.111-0.117) g : (0.188-0.234) g : (0.05-0.07) g : (18-22) mL, the reaction is carried out with magnetic stirring at a temperature of 100-120℃, and the reaction time is 60-80 h.

[0018] Preferably, the method for preparing the electrolyte additive includes the following steps:

[0019] S1: Add phosphonyl chloride trimer, N-hydroxyethylaniline, triethylamine and chlorobenzene to a container equipped with a thermometer, mechanical stirrer and reflux condenser, and heat and stir in an oil bath to react;

[0020] S2: After the reaction is complete, the temperature is lowered, ammonia gas is introduced, the mixture is filtered, washed, dried, polycondensed, cooled, dissolved, filtered, washed, and dried to obtain the electrolyte additive.

[0021] In the above process, phosphonyl chloride trimer and N-hydroxyethyl aniline are used as raw materials, and triethylamine is used as a catalyst and acid-binding agent. The electrolyte additive is obtained by reacting phosphonyl chloride trimer and N-hydroxyethyl aniline, followed by amination and then polycondensation.

[0022] Preferably, in step S1, the ratio of phosphonyl chloride trimer, N-hydroxyethyl aniline, triethylamine, and chlorobenzene is (15-19.8)g:(6.02-6.24)g:(6.48-6.64)g:(58-64)g, the oil bath heating temperature is 90-95℃, and the reaction time is 8-12h; in step S2, the temperature is lowered to -5℃~5℃, ammonia gas is introduced for 20-24h, the polycondensation temperature is 160-190℃, the time is 10-30min, it is added to deionized water for dissolution, washed with deionized water, and dried at 90-110℃ for 12-18h.

[0023] Preferably, the method for preparing the lithium-ion battery includes the following steps:

[0024] Step 1: Mix lithium cobalt oxide, carbon black and polyvinylidene fluoride, then add N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material.

[0025] Step 2: Mix graphite and negative electrode material additives, then mix with carbon black and carboxymethyl cellulose, add deionized water and stir to obtain negative electrode slurry, coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain negative electrode material.

[0026] Step 3: Mix dimethyl carbonate and lithium hexafluorophosphate, then add electrolyte additives, stir evenly, and filter to obtain electrolyte;

[0027] Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

[0028] Preferably, in step one, the mass ratio of lithium cobalt oxide, carbon black, and polyvinylidene fluoride is (88-92):(4-6):(3-7); in step two, the mass ratio of graphite, negative electrode material additive, carbon black, and carboxymethyl cellulose is (86-89):(2.58-2.67):(2-8):(3-7); and in step three, the mass ratio of dimethyl carbonate, lithium hexafluorophosphate, and electrolyte additive is (30-53):(8-13):(0.24-0.39).

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. This invention first uses 3,5-dibromoaniline, 1-bromohexane, bis(pinacol)diboron, 2-bromophenazine, and 2-bromoanthraquinone as raw materials to prepare a negative electrode material additive. Subsequently, using phosphonyl chloride trimer and N-hydroxyethylaniline as raw materials, an electrolyte additive is prepared. Adding these additives to the lithium-ion battery manufacturing process can effectively improve the energy density, cycle performance, and safety of the lithium-ion battery.

[0031] 2. This invention applies the obtained negative electrode material additive to the preparation process of lithium-ion batteries, which can effectively improve the energy density and cycle performance of the battery. The nitrogen atoms contained in the negative electrode material additive have lone pairs of electrons, which can form coordination bonds with lithium ions, providing additional lithium ion storage sites. The presence of anthraquinone structure provides stable lithium ion storage sites, further increasing the capacity of the negative electrode material. The presence of the negative electrode material additive can provide more lithium ion storage sites, significantly improving the theoretical capacity of the negative electrode material. At the same time, the conjugated π electron system of the negative electrode material additive can move freely within and between molecules, forming a continuous electron conduction path. It can also reduce the internal resistance of the electrode, improve the electron transport efficiency, and thus improve the energy density. The rigid molecular structure of the negative electrode material additive can effectively alleviate volume changes during lithium ion insertion / extraction, reduce the pulverization and shedding of electrode materials, and improve the mechanical stability of the electrode. The presence of this substance also helps to form a stable solid electrolyte interface film on the electrode surface, effectively isolating the electrode and the electrolyte, improving the cycle stability of the battery, and increasing the cycle life of the battery.

[0032] 3. The electrolyte additive obtained in this invention can be applied to the preparation process of lithium-ion batteries, which can effectively improve the safety of the battery. The conjugated structure of nitrogen and phosphorus alternating six-membered rings can effectively disperse the heat generated inside the battery, prevent local overheating, and improve its thermal stability. The synergistic effect of nitrogen and phosphorus elements can effectively inhibit combustion and prevent battery thermal runaway. The molecular structure of the electrolyte additive does not hinder the transport of lithium ions, and the conjugated structure it contains can also interact with lithium ions through polar bonds to promote the rapid diffusion of lithium ions. At the same time, the electrolyte additive has high electrochemical stability within the battery's operating voltage range and will not undergo oxidation or reduction reactions, ensuring the high efficiency and safety of the battery during charging and discharging. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1: This example discloses a method for preparing an additive for a negative electrode material, including the following steps:

[0035] Q1: 6.439 g of 3,5-dibromoaniline, 1.128 g of 1-bromohexane, 0.828 g of tetrabutylammonium bromide, and 0.424 g of potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 8.651 g of sodium hydroxide and 21 mL of acetonitrile. The mixture was stirred at 70 °C for 8 h, extracted, washed, dried, and purified to obtain compound 1. 1.098 g of compound 1, 1.33 g of bis(pinacol)diboron, 1.289 g of potassium acetate, and 0.19 g of DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 25 mL of N,N-dimethylformamide. The mixture was stirred at 100 °C for 8 h. After the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2.

[0036] Q2: 0.05 g of 2-bromophenazine, 0.05 g of compound 2, 0.081 g of potassium carbonate and 0.011 g of tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, 9.5 mL of tetrahydrofuran, 6 mL of deionized water and 9 mL of toluene were added. The mixture was stirred in an oil bath at 95 °C for 24 h, dried and purified to obtain compound 3. 3.6 g of compound 3 was added to a container containing 50 mL of ethanol. Nitrogen was purged, and then 110 mL of distilled water containing 34.3 g of sodium dithionite was added to the container. The mixture was heated at 90 °C for 2 h. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4.

[0037] Q3: 0.187g of compound 4, 0.603g of 2-bromoanthraquinone, 0.114g of 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 0.216g of sodium tert-butoxide, and 0.06g of tris(dibenzylacetone)palladium were added to a container. After purging with nitrogen, 20mL of 1,4-dioxane was added. The container was sealed and heated at 110℃ with magnetic stirring for 72h. After the reaction was completed, the container was cooled, filtered, washed, and dried to obtain the negative electrode material additive.

[0038] This embodiment discloses a method for preparing an electrolyte additive, including the following steps:

[0039] S1: Add 17.4g of phosphonyl chloride trimer, 6.13g of N-hydroxyethyl aniline, 6.56g of triethylamine and 62g of chlorobenzene to a container equipped with a thermometer, mechanical stirrer and reflux condenser, and heat and stir in an oil bath at 90°C for 12 hours.

[0040] S2: After the reaction is complete, the temperature is lowered to 5°C, ammonia gas is introduced for 24 hours, filtered, washed, dried, polycondensed at 190°C for 30 minutes, cooled, added to deionized water for dissolution, filtered, washed with deionized water, and dried at 100°C for 18 hours to obtain the electrolyte additive.

[0041] This embodiment discloses a method for preparing a lithium-ion battery, including the following steps:

[0042] Step 1: Mix 90g lithium cobalt oxide, 5g carbon black and 5g polyvinylidene fluoride, then add 150mL N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material.

[0043] Step 2: Mix 87.5g of graphite and 2.64g of negative electrode material additive, then mix with 5g of carbon black and 5g of carboxymethyl cellulose, add 80mL of deionized water and stir to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain the negative electrode material.

[0044] Step 3: Mix 41.5g of dimethyl carbonate and 10.5g of lithium hexafluorophosphate, then add 0.28g of electrolyte additive, stir well, and filter to obtain the electrolyte;

[0045] Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

[0046] Example 2: This example discloses a method for preparing an additive for a negative electrode material, including the following steps:

[0047] Q1: 6.218 g of 3,5-dibromoaniline, 1.024 g of 1-bromohexane, 0.782 g of tetrabutylammonium bromide, and 0.342 g of potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 8.564 g of sodium hydroxide and 18 mL of acetonitrile. The mixture was stirred at 70 °C for 8 h, extracted, washed, dried, and purified to obtain compound 1. 1.046 g of compound 1, 1.11 g of bis(pinacol)diboron, 1.212 g of potassium acetate, and 0.15 g of DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 20 mL of N,N-dimethylformamide. The mixture was stirred at 100 °C for 8 h. After the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2.

[0048] Q2: 0.04 g of 2-bromophenazine, 0.03 g of compound 2, 0.06 g of potassium carbonate and 0.008 g of tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, 8 mL of tetrahydrofuran, 4 mL of deionized water and 8 mL of toluene were added. The mixture was stirred in an oil bath at 95 °C for 24 h, dried and purified to obtain compound 3. 3.1 g of compound 3 was added to a container containing 45 mL of ethanol. Nitrogen was purged, and then 100 mL of distilled water containing 31.2 g of sodium dithionite was added to the container. The mixture was heated at 90 °C for 2 h. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4.

[0049] Q3: 0.166g of compound 4, 0.552g of 2-bromoanthraquinone, 0.111g of 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 0.188g of sodium tert-butoxide, and 0.05g of tris(dibenzylideneacetone)palladium were added to a container. After purging with nitrogen, 18mL of 1,4-dioxane was added. The container was sealed and heated at 110℃ with magnetic stirring for 72h. After the reaction was completed, the container was cooled, filtered, washed, and dried to obtain the negative electrode material additive.

[0050] This embodiment discloses a method for preparing an electrolyte additive, including the following steps:

[0051] S1: Add 15g of phosphonyl chloride trimer, 6.02g of N-hydroxyethyl aniline, 6.48g of triethylamine and 58g of chlorobenzene to a container equipped with a thermometer, a mechanical stirrer and a reflux condenser, and heat and stir in an oil bath at 90°C for 12 hours.

[0052] S2: After the reaction is complete, the temperature is lowered to 5°C, ammonia gas is introduced for 24 hours, filtered, washed, dried, polycondensed at 190°C for 30 minutes, cooled, added to deionized water for dissolution, filtered, washed with deionized water, and dried at 100°C for 18 hours to obtain the electrolyte additive.

[0053] This embodiment discloses a method for preparing a lithium-ion battery, including the following steps:

[0054] Step 1: Mix 88g lithium cobalt oxide, 4g carbon black and 3g polyvinylidene fluoride, then add 150mL N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material.

[0055] Step 2: Mix 86g of graphite and 2.58g of negative electrode material additive, then mix with 2g of carbon black and 3g of carboxymethyl cellulose, add 80mL of deionized water and stir to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain the negative electrode material.

[0056] Step 3: Mix 30g of dimethyl carbonate and 8g of lithium hexafluorophosphate, then add 0.24g of electrolyte additive, stir well, and filter to obtain the electrolyte;

[0057] Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

[0058] Example 3: This example discloses a method for preparing an additive for a negative electrode material, including the following steps:

[0059] Q1: 6.668 g of 3,5-dibromoaniline, 1.232 g of 1-bromohexane, 0.866 g of tetrabutylammonium bromide, and 0.506 g of potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 8.844 g of sodium hydroxide and 24 mL of acetonitrile. The mixture was stirred at 70 °C for 8 h, extracted, washed, dried, and purified to obtain compound 1. 1.15 g of compound 1, 1.55 g of bis(pinacol)diboron, 1.366 g of potassium acetate, and 0.23 g of DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 30 mL of N,N-dimethylformamide. The mixture was stirred at 100 °C for 8 h. After the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2.

[0060] Q2: 0.06 g of 2-bromophenazine, 0.07 g of compound 2, 0.102 g of potassium carbonate and 0.014 g of tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, 11 mL of tetrahydrofuran, 8 mL of deionized water and 10 mL of toluene were added. The mixture was stirred in an oil bath at 95 °C for 24 h, dried and purified to obtain compound 3. 4.1 g of compound 3 was added to a container containing 55 mL of ethanol. Nitrogen was purged, and then 120 mL of distilled water containing 37.6 g of sodium dithionite was added to the container. The mixture was heated at 90 °C for 2 h. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4.

[0061] Q3: 0.208g of compound 4, 0.654g of 2-bromoanthraquinone, 0.117g of 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 0.234g of sodium tert-butoxide, and 0.07g of tris(dibenzylideneacetone)palladium were added to a container. After purging with nitrogen, 22mL of 1,4-dioxane was added. The container was sealed and heated at 110℃ with magnetic stirring for 72h. After the reaction was completed, the container was cooled, filtered, washed, and dried to obtain the negative electrode material additive.

[0062] This embodiment discloses a method for preparing an electrolyte additive, including the following steps:

[0063] S1: Add 19.8g of phosphonyl chloride trimer, 6.24g of N-hydroxyethyl aniline, 6.64g of triethylamine and 64g of chlorobenzene to a container equipped with a thermometer, mechanical stirrer and reflux condenser, and heat and stir in an oil bath at 90°C for 12 hours.

[0064] S2: After the reaction is complete, the temperature is lowered to 5°C, ammonia gas is introduced for 24 hours, filtered, washed, dried, polycondensed at 190°C for 30 minutes, cooled, added to deionized water for dissolution, filtered, washed with deionized water, and dried at 100°C for 18 hours to obtain the electrolyte additive.

[0065] This embodiment discloses a method for preparing a lithium-ion battery, including the following steps:

[0066] Step 1: Mix 92g lithium cobalt oxide, 6g carbon black and 7g polyvinylidene fluoride, then add 150mL N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material.

[0067] Step 2: Mix 89g of graphite and 2.67g of negative electrode material additive, then mix with 8g of carbon black and 7g of carboxymethyl cellulose, add 80mL of deionized water and stir to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain the negative electrode material.

[0068] Step 3: Mix 53g of dimethyl carbonate and 13g of lithium hexafluorophosphate, then add 0.39g of electrolyte additive, stir well, and filter to obtain the electrolyte;

[0069] Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

[0070] Example 4: This example discloses a method for preparing an additive for a negative electrode material, including the following steps:

[0071] Q1: 6.371g of 3,5-dibromoaniline, 1.117g of 1-bromohexane, 0.793g of tetrabutylammonium bromide, and 0.387g of potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 8.593g of sodium hydroxide and 19mL of acetonitrile. The mixture was stirred at 70℃ for 8 hours, extracted, washed, dried, and purified to obtain compound 1. 1.067g of compound 1, 1.22g of bis(pinacol)diboron, 1.247g of potassium acetate, and 0.17g of DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 22mL of N,N-dimethylformamide. The mixture was stirred at 100℃ for 8 hours. After the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2.

[0072] Q2: 0.045 g of 2-bromophenazine, 0.04 g of compound 2, 0.07 g of potassium carbonate and 0.009 g of tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, 9 mL of tetrahydrofuran, 5 mL of deionized water and 8.5 mL of toluene were added. The mixture was stirred in an oil bath at 95 °C for 24 h, dried and purified to obtain compound 3. 3.2 g of compound 3 was added to a container containing 48 mL of ethanol. Nitrogen was purged, and then 105 mL of distilled water containing 33.8 g of sodium dithionite was added to the container. The mixture was heated at 90 °C for 2 h. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4.

[0073] Q3: 0.171g of compound 4, 0.581g of 2-bromoanthraquinone, 0.112g of 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 0.191g of sodium tert-butoxide, and 0.055g of tris(dibenzylideneacetone)palladium were added to a container. After purging with nitrogen, 19mL of 1,4-dioxane was added. The container was sealed and heated at 110℃ with magnetic stirring for 72h. After the reaction was completed, the container was cooled, filtered, washed, and dried to obtain the negative electrode material additive.

[0074] This embodiment discloses a method for preparing an electrolyte additive, including the following steps:

[0075] S1: Add 16.7g phosphonyl chloride trimer, 6.07g N-hydroxyethyl aniline, 6.51g triethylamine and 59g chlorobenzene to a container equipped with a thermometer, mechanical stirrer and reflux condenser, and heat and stir in an oil bath at 90°C for 12h.

[0076] S2: After the reaction is complete, the temperature is lowered to 5°C, ammonia gas is introduced for 24 hours, filtered, washed, dried, polycondensed at 190°C for 30 minutes, cooled, added to deionized water for dissolution, filtered, washed with deionized water, and dried at 100°C for 18 hours to obtain the electrolyte additive.

[0077] This embodiment discloses a method for preparing a lithium-ion battery, including the following steps:

[0078] Step 1: Mix 89g lithium cobalt oxide, 4.5g carbon black and 4g polyvinylidene fluoride, then add 150mL N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material.

[0079] Step 2: Mix 87g of graphite and 2.59g of negative electrode material additive, then mix with 3g of carbon black and 4g of carboxymethyl cellulose, add 80mL of deionized water and stir to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain the negative electrode material.

[0080] Step 3: Mix 35g of dimethyl carbonate and 9g of lithium hexafluorophosphate, then add 0.26g of electrolyte additive, stir well, and filter to obtain the electrolyte;

[0081] Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

[0082] Example 5: This example discloses a method for preparing an additive for a negative electrode material, including the following steps:

[0083] Q1: 6.528 g of 3,5-dibromoaniline, 1.118 g of 1-bromohexane, 0.841 g of tetrabutylammonium bromide, and 0.483 g of potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 8.715 g of sodium hydroxide and 23 mL of acetonitrile. The mixture was stirred at 70 °C for 8 h, extracted, washed, dried, and purified to obtain compound 1. 1.108 g of compound 1, 1.44 g of bis(pinacol)diboron, 1.328 g of potassium acetate, and 0.21 g of DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of 28 mL of N,N-dimethylformamide. The mixture was stirred at 100 °C for 8 h. After the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2.

[0084] Q2: 0.055g of 2-bromophenazine, 0.06g of compound 2, 0.091g of potassium carbonate and 0.013g of tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, 10mL of tetrahydrofuran, 7mL of deionized water and 9.5mL of toluene were added. The mixture was stirred in an oil bath at 95℃ for 24h, dried and purified to obtain compound 3. 3.8g of compound 3 was added to a container containing 52mL of ethanol. Nitrogen was purged, and then 115mL of distilled water containing 36.5g of sodium dithionite was added to the container. The mixture was heated at 90℃ for 2h. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4.

[0085] Q3: 0.193g of compound 4, 0.623g of 2-bromoanthraquinone, 0.116g of 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 0.223g of sodium tert-butoxide, and 0.065g of tris(dibenzylacetone)palladium were added to a container. After purging with nitrogen, 21mL of 1,4-dioxane was added. The container was sealed and heated at 110℃ with magnetic stirring for 72h. After the reaction was completed, the container was cooled, filtered, washed, and dried to obtain the negative electrode material additive.

[0086] This embodiment discloses a method for preparing an electrolyte additive, including the following steps:

[0087] S1: Add 18.3g of phosphonyl chloride trimer, 6.18g of N-hydroxyethyl aniline, 6.61g of triethylamine and 61g of chlorobenzene to a container equipped with a thermometer, a mechanical stirrer and a reflux condenser, and heat and stir in an oil bath at 90°C for 12 hours.

[0088] S2: After the reaction is complete, the temperature is lowered to 5°C, ammonia gas is introduced for 24 hours, filtered, washed, dried, polycondensed at 190°C for 30 minutes, cooled, added to deionized water for dissolution, filtered, washed with deionized water, and dried at 100°C for 18 hours to obtain the electrolyte additive.

[0089] This embodiment discloses a method for preparing a lithium-ion battery, including the following steps:

[0090] Step 1: Mix 91g of lithium cobalt oxide, 5.5g of carbon black and 6g of polyvinylidene fluoride, then add 150mL of N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material.

[0091] Step 2: Mix 88g of graphite and 2.66g of negative electrode material additive, then mix with 7g of carbon black and 6g of carboxymethyl cellulose, add 80mL of deionized water and stir to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain the negative electrode material.

[0092] Step 3: Mix 48g of dimethyl carbonate and 11g of lithium hexafluorophosphate, then add 0.34g of electrolyte additive, stir well, and filter to obtain the electrolyte;

[0093] Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

[0094] Comparative Example 1: Compared with Example 1, Comparative Example 1 did not add any negative electrode material additives during the preparation of a high-energy-density rechargeable lithium-ion battery, and all other conditions remained unchanged.

[0095] Comparative Example 2: Compared with Example 1, Comparative Example 2 did not add electrolyte additives during the preparation of high energy density rechargeable lithium-ion batteries, and all other conditions remained unchanged.

[0096] Experimental Example: The high-energy-density rechargeable lithium-ion batteries prepared in Examples 1-5 and Comparative Examples 1-2 were tested for energy density and cycle performance. The energy density test method was as follows: the prepared samples were charged at 0.3C constant current and constant voltage to a voltage of 4.25V in a 25℃ constant temperature chamber, with a cutoff current of 0.05C. After standing for 10 minutes, they were discharged at 0.3C constant current to 2.5V, and then stood for 10 minutes. This process was repeated, and the battery energy density was recorded. The cycle performance test method was as follows: the prepared samples were charged at 1C constant current and constant voltage to 4.25V. The cutoff current was 0.05C, and the sample was left to stand for 10 minutes. It was then discharged at a constant current of 1C to 2.5V, left to stand for 10 minutes, and this discharge cycle was repeated 120 times. The prepared sample was then charged at 0.3C to a voltage of 4.25V, with a cutoff current of 0.05C. A 3mm diameter steel needle was inserted completely into the center of the battery at a speed of 50mm / s, and kept in the inserted state. The experimental phenomena were observed until the battery surface temperature dropped by 50℃, at which point the test was terminated. The prepared sample was then placed in a drying oven and heated to 160℃ for 30 minutes. The test results are shown in Table 1.

[0097] Table 1

[0098] project <![CDATA[Energy density Wh·kg -1 > Capacity retention rate / % Needle prick test Furnace temperature experiment Example 1 337 97.4 No fire No fire Example 2 335 97.1 No fire No fire Example 3 328 96.8 No fire No fire Example 4 324 96.5 No fire No fire Example 5 327 96.4 No fire No fire Comparative Example 1 295 92.7 No fire No fire Comparative Example 2 325 96.5 fire fire

[0099] As shown in Table 1, the rechargeable lithium-ion batteries prepared in Examples 1-5 of this invention exhibit high energy density, excellent cycle stability, and safety. A comparison between Comparative Example 1 and Examples 1-5 shows that the addition of additives to the negative electrode material can effectively improve the energy density and cycle stability of the rechargeable lithium-ion battery; a comparison between Comparative Example 2 and Examples 1-5 shows that the addition of electrolyte additives can effectively improve the safety of the rechargeable lithium-ion battery.

[0100] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0101] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-energy-density rechargeable lithium-ion battery, characterized in that, It is composed of a positive electrode material, a negative electrode material, an electrolyte, and a porous polyethylene film. The positive electrode material is prepared from lithium cobalt oxide, carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and aluminum foil. The negative electrode material is prepared from graphite, negative electrode material additives, carbon black, carboxymethyl cellulose, deionized water, and copper foil. The electrolyte is prepared from dimethyl carbonate, lithium hexafluorophosphate, and electrolyte additives. The preparation method of the negative electrode material additive includes the following steps: Q1: 3,5-Dibromoaniline, 1-bromohexane, tetrabutylammonium bromide, and potassium iodide were added sequentially to a container, nitrogen gas was introduced, followed by the addition of sodium hydroxide and acetonitrile, the mixture was stirred, extracted, washed, dried, and purified to obtain compound 1; Compound 1, bis(pinacolyl)diboron, potassium acetate, and DPPF palladium dichloride were added sequentially to a container, nitrogen gas was introduced, followed by the addition of N,N-dimethylformamide, the mixture was stirred, and after the reaction was completed, the mixture was extracted, washed, dried, and purified to obtain compound 2; Q2: 2-Bromophenazine, compound 2, potassium carbonate, and tetra(triphenylphosphine)palladium were added sequentially to a container. After purging with nitrogen, tetrahydrofuran, deionized water, and toluene were added. The mixture was stirred in an oil bath, dried, and purified to obtain compound 3. Compound 3 was added to a container containing ethanol, and nitrogen was purged. Then, distilled water containing dissolved sodium dithionite was added to the container, and the mixture was heated to react. After the reaction was completed, the mixture was cooled, washed, filtered, and dried to obtain compound 4. Q3: Compound 4, 2-bromoanthraquinone, 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, sodium tert-butoxide and tris(dibenzylideneacetone)palladium were added to a container, nitrogen gas was introduced, and then 1,4-dioxane was added. The container was sealed, heated and magnetically stirred to react. After the reaction was completed, the container was cooled, filtered, washed and dried to obtain the negative electrode material additive.

2. The high-energy-density rechargeable lithium-ion battery according to claim 1, characterized in that, In Q1, the ratio of 3,5-dibromoaniline, 1-bromohexane, tetrabutylammonium bromide, potassium iodide, sodium hydroxide, and acetonitrile is (6.218-6.668) g : (1.024-1.232) g : (0.782-0.866) g : (0.342-0.506) g : (8.564-8.844) g : (18-24) mL, and the reaction temperature is 60-80℃. The reaction time was 6-8 h; the ratio of compound 1, bis(pinacol)diboron, potassium acetate, DPPF palladium dichloride and N,N-dimethylformamide was (1.046-1.15) g : (1.11-1.55) g : (1.212-1.366) g : (0.15-0.23) g : (20-30) mL, the stirring temperature was 90-110℃, and the reaction time was 6-8 h.

3. The high-energy-density rechargeable lithium-ion battery according to claim 1, characterized in that, In Q2, the ratio of 2-bromophenazine, compound 2, potassium carbonate, tetra(triphenylphosphine)palladium, tetrahydrofuran, deionized water, and toluene is (0.04-0.06) g : (0.03-0.07) g : (0.06-0.102) g : (0.008-0.014) g : (8-11) mL : (4-8) mL : (8-10) mL, the oil bath stirring temperature is 90-105℃, and the reaction time is 20-24 h; the ratio of compound 3, ethanol, sodium dithionite, and distilled water is (3.1-4.1) g : (45-55) mL : (31.2-37.6) g : (100-120) mL, the heating reaction temperature is 80-90℃, and the reaction time is 1-2 h.

4. The high-energy-density rechargeable lithium-ion battery according to claim 1, characterized in that, In Q3, the ratio of compound 4, 2-bromoanthraquinone, 2-bicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, sodium tert-butoxide, tris(dibenzylideneacetone)palladium, and 1,4-dioxane is (0.166-0.208) g : (0.552-0.654) g : (0.111-0.117) g : (0.188-0.234) g : (0.05-0.07) g : (18-22) mL. The reaction temperature is 100-120℃ with magnetic stirring, and the reaction time is 60-80 h.

5. The high-energy-density rechargeable lithium-ion battery according to claim 1, characterized in that, The preparation method of the electrolyte additive includes the following steps: S1: Add phosphonyl chloride trimer, N-hydroxyethylaniline, triethylamine and chlorobenzene to a container equipped with a thermometer, mechanical stirrer and reflux condenser, and heat and stir in an oil bath to react; S2: After the reaction is complete, the temperature is lowered, ammonia gas is introduced, the mixture is filtered, washed, dried, polycondensed, cooled, dissolved, filtered, washed, and dried to obtain the electrolyte additive.

6. The high-energy-density rechargeable lithium-ion battery according to claim 5, characterized in that, In step S1, the ratio of phosphonyl chloride trimer, N-hydroxyethyl aniline, triethylamine, and chlorobenzene is (15-19.8) g : (6.02-6.24) g : (6.48-6.64) g : (58-64) g, the oil bath heating temperature is 90-95℃, and the reaction time is 8-12 h. In step S2, the temperature is lowered to -5℃ to 5℃, ammonia gas is introduced for 20-24 h, the polycondensation temperature is 160-190℃, the time is 10-30 min, it is added to deionized water for dissolution, washed with deionized water, and dried at 90-110℃ for 12-18 h.

7. The high-energy-density rechargeable lithium-ion battery according to any one of claims 1-6, characterized in that, The method for preparing the lithium-ion battery includes the following steps: Step 1: Mix lithium cobalt oxide, carbon black and polyvinylidene fluoride, then add N-methylpyrrolidone and stir to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on aluminum foil, dry, press into sheets, and cut to obtain the positive electrode material. Step 2: Mix graphite and negative electrode material additives, then mix with carbon black and carboxymethyl cellulose, add deionized water and stir to obtain negative electrode slurry, coat the negative electrode slurry evenly on copper foil, dry, press into sheets, and cut to obtain negative electrode material. Step 3: Mix dimethyl carbonate and lithium hexafluorophosphate, then add electrolyte additives, stir evenly, and filter to obtain electrolyte; Step 4: Stack the positive electrode material, porous polyethylene film and negative electrode material to obtain the battery cell. Then, put the battery cell into the metal shell, inject the electrolyte into the battery, seal it, and obtain a high-energy-density rechargeable lithium-ion battery.

8. The high-energy-density rechargeable lithium-ion battery according to claim 7, characterized in that, In step one, the mass ratio of lithium cobalt oxide, carbon black, and polyvinylidene fluoride is (88-92):(4-6):(3-7); in step two, the mass ratio of graphite, anode material additive, carbon black, and carboxymethyl cellulose is (86-89):(2.58-2.67):(2-8):(3-7); in step three, the mass ratio of dimethyl carbonate, lithium hexafluorophosphate, and electrolyte additive is (30-53):(8-13):(0.24-0.39).

Images