New energy lithium battery with excellent cycle performance and preparation method thereof

Abstract

The application discloses a new energy lithium battery with excellent cycle performance and a preparation method thereof, and belongs to the technical field of battery preparation. The new energy lithium battery with excellent cycle performance comprises a positive electrode structure, a negative electrode structure, a diaphragm layer, an electrolyte and a packaging material, the electrolyte is located between the positive electrode structure and the negative electrode structure, the diaphragm layer is soaked in the electrolyte, and the packaging material wraps the positive electrode structure, the negative electrode structure, the diaphragm layer and the electrolyte. The positive electrode structure is prepared from a composite positive electrode material, an aluminum foil and a modified binder, and the negative electrode structure is prepared from graphite, a copper foil and a modified binder. The new energy lithium battery prepared by the method has excellent cycle performance, energy density and rate performance.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery preparation technology, specifically relating to new energy lithium batteries with excellent cycle performance and their preparation methods. Background Technology

[0002] With increasing global concern over the energy crisis and environmental pollution, the development of new energy technologies has become a crucial approach to addressing these challenges. Among these, lithium batteries, as a highly efficient, environmentally friendly, and renewable energy storage device, have attracted significant attention for their research and application. Among numerous new energy technologies, lithium batteries, with their high energy density, long lifespan, and fast charging speed, have gradually become the core power source for electronic products such as mobile phones, laptops, and tablets, as well as electric vehicles, drones, and spacecraft.

[0003] However, despite significant progress in energy storage, lithium batteries still face numerous challenges in terms of cycle performance. Cycle performance is a crucial indicator of a lithium battery's lifespan and stability, directly impacting device lifespan and maintenance costs. Traditional lithium batteries often experience capacity decay, increased internal resistance, and decreased thermal stability during prolonged charge-discharge cycles, severely affecting their application effectiveness and market competitiveness. To overcome these challenges, researchers are dedicated to developing new energy lithium batteries with superior cycle performance.

[0004] Patent CN 107464953 A discloses a lithium battery electrolyte and a lithium battery. The lithium battery electrolyte of this invention comprises the following components by weight: lithium hexafluorophosphate 48-60, lithium dioxaborate 30-35, carbodiimide 0.1-1.2, phenyl ether or haloalkanes 0.3-2, ortho- or para-dimethoxy-substituted benzene 0.1-1, haloalkyl phosphates 0.1-4, chain carbonates 2-8, cyclic carbonates 1.5-7, and acrylamide 0.5-0.7. Due to its reasonable composition and optimal ratio of components, it has high conductivity, and lithium batteries using this electrolyte exhibit good cycle performance. However, there is still room for improvement in the cycle performance, conductivity, and safety stability of the lithium batteries prepared by this method. Summary of the Invention

[0005] The purpose of this invention is to provide a new energy lithium battery with excellent cycle performance and its preparation method, in order to solve the technical problems of poor cycle performance, conductivity and safety stability of lithium batteries in the prior art.

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

[0007] This invention provides a new energy lithium battery with excellent cycle performance, comprising a positive electrode structure, a negative electrode structure, a separator layer, an electrolyte, and an encapsulation material. The electrolyte is located between the positive electrode structure and the negative electrode structure, the separator layer is immersed in the electrolyte, and the encapsulation material encapsulates the positive electrode structure, the negative electrode structure, the separator layer, and the electrolyte. The positive electrode structure is prepared from a composite positive electrode material, aluminum foil, and a modified binder, and the negative electrode structure is prepared from graphite, copper foil, and a modified binder.

[0008] Preferably, the method for preparing the composite cathode material includes the following steps:

[0009] Q1: Under a nitrogen atmosphere, formic acid was added to dichloromethane containing diphenyl ether and stirred at low temperature. Then titanium chloride was added. After the reaction was complete, sodium bicarbonate aqueous solution was added, and the mixture was allowed to stand and separate into layers. The aqueous layer was extracted with dichloromethane, the organic layers were combined, dried, rotary evaporated, and purified by chromatography to obtain intermediate product 1.

[0010] Q2: Dissolve intermediate 1 in dichloromethane, add distilled water containing cerium ammonium nitrate, stir, extract, dry, rotary evaporate, and purify by chromatography to obtain intermediate 2;

[0011] Q3: After mixing intermediate product 2, p-phenylenediamine and anhydrous ethanol, the mixture is stirred and heated under reflux. After reflux, the mixture is cooled, filtered, washed, and dried to obtain the composite cathode material.

[0012] In the above process, p-phenylenedimethyl ether is first used as a raw material and undergoes a cyclization reaction under the catalysis of formic acid and titanium chloride to obtain intermediate product 1. Then, it is oxidized with cerium ammonium nitrate to obtain intermediate product 2. Intermediate product 2 and p-phenylenedimethyl ether undergo Michael addition polymerization to obtain composite cathode material.

[0013] Preferably, in Q1, the molar ratio of formic acid, diphenyl ether, and titanium chloride is 3-3.9:1-1.3:1.13-1.47, the low-temperature stirring temperature is 0-1℃, the stirring time is 10-15 min, and the mixture is dried with magnesium sulfate.

[0014] Preferably, in Q2, the molar ratio of intermediate product 1 to cerium ammonium nitrate is 1-1.2:23-27.6, the stirring temperature is 28-30℃, the stirring time is 5-7h, and it is dried with magnesium sulfate; in Q3, the molar ratio of intermediate product 2 to p-phenylenediamine is 1-2:4-6, the stirring and heating reflux temperature is 70-80℃, the time is 12-14h, it is washed 3-5 times with anhydrous ethanol and distilled water respectively, and the drying temperature is 80-85℃.

[0015] Preferably, the method for preparing the modified adhesive includes the following steps:

[0016] S1: Sodium tetraborate (decahydrate) and levodopa were added to a container. Under a nitrogen atmosphere, distilled water was added and stirred to dissolve the mixture. Then sodium carbonate was added. Methacrylamide chloride and tetrahydrofuran were mixed and then added dropwise to the container. The reaction was stirred continuously under a nitrogen atmosphere. After the reaction was completed, the mixture was extracted, the pH was adjusted, the mixture was rotary evaporated, washed, and vacuum dried to obtain intermediate product A.

[0017] S2: Add intermediate product A and azobisisobutyronitrile to a container, add N,N-dimethylformamide to dissolve, then replace the atmosphere in the container with nitrogen, heat the reaction, cool, and introduce air to obtain a polymer. Then mix the polymer with N,N-dimethylformamide, and then add it dropwise to diethyl ether for precipitation. Filter, dry, dialyze, and freeze dry to obtain intermediate product B.

[0018] S3: Dissolve intermediate product B in hydrochloric acid, stir magnetically, then add poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), and continue stirring to obtain the modified binder.

[0019] The synthesis reaction formula for the modified binder in the above process is as follows:

[0020]

[0021] Preferably, in S1, the molar ratio of sodium tetraborate (decahydrate), levodopa, and methacryloyl chloride is 1-2:2-4:1.2-2.4, the stirring and dissolution time is 10-20 min, the dropping rate is 100 mL / h, the stirring reaction time is 20-24 h, extraction is performed with ethyl acetate, the pH is adjusted to 1-1.2 with 1 mol / L hydrochloric acid, and the vacuum drying temperature is 50-55 °C.

[0022] Preferably, in S2, the molar ratio of intermediate product A to azobisisobutyronitrile is 10-20:0.45-0.9, the heating reaction temperature is 70-75℃, and the reaction time is 22-24h.

[0023] Preferably, in step S3, the ratio of intermediate product B, hydrochloric acid, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) is 1-2g:10-12mL:2-4g, the concentration of hydrochloric acid is 1mol / L, the magnetic stirring time is 4-6h, and the stirring time is continued for 3-5h.

[0024] Preferably, the method for preparing the new energy lithium battery with excellent cycle performance includes the following steps:

[0025] Step (1): Mix the composite positive electrode material, modified binder and distilled water, grind them to obtain a positive electrode slurry, and then use a film stretcher to uniformly coat the positive electrode slurry onto the surface of an aluminum foil. After vacuum drying, a positive electrode structure is obtained. Mix the graphite, modified binder and distilled water, grind them to obtain a negative electrode slurry, and then use a film stretcher to uniformly coat the negative electrode slurry onto the surface of a copper foil. After vacuum drying, a negative electrode structure is obtained.

[0026] Step (2): Assemble the positive electrode structure, negative electrode structure, separator layer and electrolyte to obtain a lithium battery cell, connect the lithium battery cells and encapsulate them with encapsulation material to obtain a new energy lithium battery with excellent cycle performance.

[0027] Preferably, in step (1), the ratio of composite cathode material, modified binder and distilled water is 8-10g:0.4-0.6g:10-20mL, the vacuum drying temperature is 80-90℃, and the time is 14-16h. Alternatively, the ratio of graphite, modified binder and distilled water is 8-10g:0.4-0.6g:10-20mL, the vacuum drying temperature is 80-90℃, and the time is 14-16h.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] 1. This invention first prepares a composite cathode material using terephthalic dimethyl ether, cerium ammonium nitrate, and terephthalic dimethylamine as raw materials, and then prepares a modified binder using sodium tetraborate (decahydrate), levodopa, methacryloyl chloride, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) as raw materials. Using the composite cathode material and the modified binder in lithium batteries can effectively improve the cycle performance, energy density, and rate performance of lithium batteries.

[0030] 2. This invention uses p-phenylenediamine as a raw material. Under the catalysis of formic acid and titanium chloride, intermediate product 1 is obtained. Then, intermediate product 1 is oxidized using cerium ammonium nitrate as an oxidant to obtain intermediate product 2. Subsequently, intermediate product 2 reacts with p-phenylenediamine to obtain a composite cathode material. Applying this material to lithium batteries can effectively improve the energy density, cycle performance, and rate performance of lithium batteries. The cyclization structure in the composite cathode material facilitates the insertion and extraction of lithium ions, making lithium ion transport more efficient and improving energy density. Simultaneously, the composite cathode material maintains excellent structural stability and electrochemical performance during charge-discharge cycles, reducing capacity decay. The cyclization reaction enhances the structural rigidity of the material, making it more resistant to volume changes during charging and discharging. Furthermore, the oxidation of cerium ammonium nitrate introduces more active sites, which helps in the rapid transport of lithium ions and also alleviates the problem of uneven lithium ion distribution. The conductive network and lithium ion transport channels inside the composite cathode material enable faster electron and lithium ion transport within the material, supporting higher-rate charge-discharge processes and improving the rate performance of the battery.

[0031] 3. This invention uses sodium tetraborate (decahydrate), levodopa, azobisisobutyronitrile, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) as raw materials to prepare a modified binder. When used in the preparation of the positive and negative electrode structures of lithium batteries, it can effectively improve the bonding strength, electrochemical stability, and cycle performance of the lithium battery. Sodium tetraborate (decahydrate) and levodopa can form intermolecular forces such as hydrogen bonds and ionic bonds. These forces still exist after the modified binder is cured, which helps to enhance the bonding strength between the binder and the electrode material. Furthermore, sodium tetraborate (decahydrate) and levodopa have stable chemical structures and can maintain their properties unchanged in the working environment of the lithium battery. The addition of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) further improves the chemical stability of the binder. The improved bonding strength and electrochemical stability help reduce the capacity decay of the lithium battery during cycling, and the excellent lithium-ion conductivity also helps maintain the stable performance of the battery after long-term use. Detailed Implementation

[0032] 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.

[0033] Example 1

[0034] This embodiment discloses a method for preparing a composite cathode material, including the following steps:

[0035] Q1: Under a nitrogen atmosphere, 1.13 g formic acid was added to 250 mL of dichloromethane containing 1.15 g p-phenylenediamine, and stirred at 0 °C for 15 min. Then, 1.34 g titanium chloride was added. After the reaction was complete, 5 mL of sodium bicarbonate aqueous solution with a concentration of 0.5 g / mL was added. The mixture was allowed to stand and separate into layers. The aqueous layer was extracted with dichloromethane, and the organic layers were combined. The mixture was dried with magnesium sulfate, rotary evaporated, and purified by chromatography to obtain intermediate product 1.

[0036] Q2: Dissolve 0.83g of intermediate product 1 in 75mL of dichloromethane, add 25mL of distilled water containing 13.75g of cerium ammonium nitrate, stir at 30℃ for 7h, extract, dry with magnesium sulfate, rotary evaporate, and purify by chromatography to obtain intermediate product 2;

[0037] Q3: Mix 1.5g of intermediate product 2, 1.02g of p-phenylenediamine and 150mL of anhydrous ethanol, stir, heat at 70℃ and reflux for 12h. After reflux, cool, filter, wash three times with anhydrous ethanol and distilled water respectively, and dry at 80℃ to obtain composite cathode material.

[0038] This embodiment discloses a method for preparing a modified adhesive, including the following steps:

[0039] S1: 1.5g sodium tetraborate (decahydrate) and 1.55g levodopa were added to a container. Under a nitrogen atmosphere, 500mL of distilled water was added and stirred for 20min to dissolve the mixture. Then, 2.78g sodium carbonate was added. 0.49g methacryloyl chloride was mixed with 1.7mL tetrahydrofuran and then added dropwise to the container at a rate of 100mL / h. The mixture was stirred continuously under a nitrogen atmosphere for 24h. After the reaction was completed, the mixture was extracted with ethyl acetate, and the pH was adjusted to 1 with 1mol / L hydrochloric acid. The mixture was then rotary evaporated, washed, and dried under vacuum at 50℃ to obtain intermediate product A.

[0040] S2: 33.98g of intermediate product A and 0.074g of azobisisobutyronitrile were added to a container, and 5mL of N,N-dimethylformamide was added to dissolve them. Then, the atmosphere in the container was replaced with nitrogen, and the reaction was heated at 70℃ for 24h. After cooling, air was introduced to obtain the polymer. Then, 3g of the polymer was mixed with 5mL of N,N-dimethylformamide, and then added dropwise to 50mL of diethyl ether for precipitation. After filtration, drying, dialyzing, and lyophilization, intermediate product B was obtained.

[0041] S3: Dissolve 1.5g of intermediate product B in 11mL of 1mol / L hydrochloric acid, stir magnetically for 6h, then add 3g of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), and continue stirring for 4h to obtain the modified binder.

[0042] This embodiment discloses a method for preparing a new energy lithium battery with excellent cycle performance, including the following steps:

[0043] Step (1): Mix 9g of composite positive electrode material, 0.5g of modified binder and 15mL of distilled water, grind to obtain positive electrode slurry, then use a film stretcher to uniformly coat the positive electrode slurry onto the surface of aluminum foil, and vacuum dry at 85℃ for 16h to obtain positive electrode structure; Mix 9g of graphite, 0.5g of modified binder and 15mL of distilled water, grind to obtain negative electrode slurry, then use a film stretcher to uniformly coat the negative electrode slurry onto the surface of copper foil, and vacuum dry at 85℃ for 16h to obtain negative electrode structure;

[0044] Step (2): Assemble the positive electrode structure, negative electrode structure, separator layer and electrolyte to obtain a lithium battery cell, connect the lithium battery cells and encapsulate them with encapsulation material to obtain a new energy lithium battery with excellent cycle performance.

[0045] Example 2

[0046] This embodiment discloses a method for preparing a composite cathode material, including the following steps:

[0047] Q1: Under a nitrogen atmosphere, 0.98 g formic acid was added to 250 mL of dichloromethane containing 1 g p-phenylenediamine, and stirred at 0 °C for 15 min. Then, 1.16 g titanium chloride was added. After the reaction was complete, 5 mL of sodium bicarbonate aqueous solution with a concentration of 0.5 g / mL was added. The mixture was allowed to stand and separate into layers. The aqueous layer was extracted with dichloromethane, and the organic layers were combined. The mixture was dried with magnesium sulfate, rotary evaporated, and purified by chromatography to obtain intermediate product 1.

[0048] Q2: Dissolve 0.75g of intermediate product 1 in 75mL of dichloromethane, add 25mL of distilled water containing 12.5g of cerium ammonium nitrate, stir at 30℃ for 7h, extract, dry with magnesium sulfate, rotary evaporate, and purify by chromatography to obtain intermediate product 2;

[0049] Q3: Mix 1g of intermediate product 2, 0.81g of p-phenylenediamine and 150mL of anhydrous ethanol, stir, heat and reflux at 70℃ for 12h. After reflux, cool, filter, wash three times with anhydrous ethanol and distilled water respectively, and dry at 80℃ to obtain composite cathode material.

[0050] This embodiment discloses a method for preparing a modified adhesive, including the following steps:

[0051] S1: Add 1g sodium tetraborate (decahydrate) and 1.03g levodopa to a container. Under a nitrogen atmosphere, add 500mL distilled water and stir to dissolve for 20min. Then add 2.78g sodium carbonate. Then mix 0.33g methacryloyl chloride with 1.7mL tetrahydrofuran and add it dropwise to the container at a rate of 100mL / h. Stir continuously under a nitrogen atmosphere for 24h. After the reaction is complete, extract with ethyl acetate, adjust pH=1 with 1mol / L hydrochloric acid, rotary evaporate, wash, and dry under vacuum at 50℃ to obtain intermediate product A.

[0052] S2: 22.65g of intermediate product A and 0.049g of azobisisobutyronitrile were added to a container, and 5mL of N,N-dimethylformamide was added to dissolve them. Then, the atmosphere in the container was replaced with nitrogen. After heating at 70℃ for 24h, the mixture was cooled and air was introduced to obtain a polymer. Then, 3g of the polymer was mixed with 5mL of N,N-dimethylformamide and then added dropwise to 50mL of diethyl ether for precipitation. The mixture was filtered, dried, dialyzed, and lyophilized to obtain intermediate product B.

[0053] S3: Dissolve 1g of intermediate product B in 10mL of 1mol / L hydrochloric acid, stir magnetically for 6h, then add 2g of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), and continue stirring for 4h to obtain the modified binder.

[0054] This embodiment discloses a method for preparing a new energy lithium battery with excellent cycle performance, including the following steps:

[0055] Step (1): Mix 8g of composite positive electrode material, 0.4g of modified binder and 10mL of distilled water, grind to obtain positive electrode slurry, then use a film stretcher to uniformly coat the positive electrode slurry onto the surface of aluminum foil, and vacuum dry at 85℃ for 16h to obtain positive electrode structure; Mix 8g of graphite, 0.4g of modified binder and 10mL of distilled water, grind to obtain negative electrode slurry, then use a film stretcher to uniformly coat the negative electrode slurry onto the surface of copper foil, and vacuum dry at 85℃ for 16h to obtain negative electrode structure;

[0056] Step (2): Assemble the positive electrode structure, negative electrode structure, separator layer and electrolyte to obtain a lithium battery cell, connect the lithium battery cells and encapsulate them with encapsulation material to obtain a new energy lithium battery with excellent cycle performance.

[0057] Example 3

[0058] This embodiment discloses a method for preparing a composite cathode material, including the following steps:

[0059] Q1: Under a nitrogen atmosphere, 1.27 g formic acid was added to 250 mL of dichloromethane containing 1.3 g p-phenylenediamine, and stirred at 0 °C for 15 min. Then, 1.51 g titanium chloride was added. After the reaction was complete, 5 mL of sodium bicarbonate aqueous solution with a concentration of 0.5 g / mL was added. The mixture was allowed to stand and separate into layers. The aqueous layer was extracted with dichloromethane, and the organic layers were combined. The mixture was dried with magnesium sulfate, rotary evaporated, and purified by chromatography to obtain intermediate product 1.

[0060] Q2: Dissolve 0.9g of intermediate product 1 in 75mL of dichloromethane, add 25mL of distilled water containing 15g of cerium ammonium nitrate, stir at 30℃ for 7h, extract, dry with magnesium sulfate, rotary evaporate, and purify by chromatography to obtain intermediate product 2;

[0061] Q3: Mix 2g of intermediate product 2, 1.22g of p-phenylenediamine and 150mL of anhydrous ethanol, stir, heat at 70℃ and reflux for 12h. After reflux, cool, filter, wash three times with anhydrous ethanol and distilled water respectively, and dry at 80℃ to obtain composite cathode material.

[0062] This embodiment discloses a method for preparing a modified adhesive, including the following steps:

[0063] S1: Add 2g sodium tetraborate (decahydrate) and 2.07g levodopa to a container. Under a nitrogen atmosphere, add 500mL distilled water and stir to dissolve for 20min. Then add 2.78g sodium carbonate. Then mix 0.66g methacryloyl chloride with 1.7mL tetrahydrofuran and add it dropwise to the container at a rate of 100mL / h. Stir continuously under a nitrogen atmosphere for 24h. After the reaction is complete, extract with ethyl acetate, adjust pH=1 with 1mol / L hydrochloric acid, rotary evaporate, wash, and dry under vacuum at 50℃ to obtain intermediate product A.

[0064] S2: 45.3g of intermediate product A and 0.098g of azobisisobutyronitrile were added to a container, and 5mL of N,N-dimethylformamide was added to dissolve them. Then, the atmosphere in the container was replaced with nitrogen, and the reaction was heated at 70℃ for 24h. After cooling, air was introduced to obtain the polymer. Then, 3g of the polymer was mixed with 5mL of N,N-dimethylformamide, and then added dropwise to 50mL of diethyl ether for precipitation. After filtration, drying, dialyzing, and lyophilization, intermediate product B was obtained.

[0065] S3: Dissolve 2g of intermediate product B in 12mL of 1mol / L hydrochloric acid, stir magnetically for 6h, then add 4g of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), and continue stirring for 4h to obtain the modified binder.

[0066] This embodiment discloses a method for preparing a new energy lithium battery with excellent cycle performance, including the following steps:

[0067] Step (1): Mix 10g of composite positive electrode material, 0.6g of modified binder and 20mL of distilled water, grind to obtain positive electrode slurry, then use a film stretcher to uniformly coat the positive electrode slurry onto the surface of aluminum foil, and vacuum dry at 85℃ for 16h to obtain positive electrode structure; Mix 10g of graphite, 0.6g of modified binder and 20mL of distilled water, grind to obtain negative electrode slurry, then use a film stretcher to uniformly coat the negative electrode slurry onto the surface of copper foil, and vacuum dry at 85℃ for 16h to obtain negative electrode structure;

[0068] Step (2): Assemble the positive electrode structure, negative electrode structure, separator layer and electrolyte to obtain a lithium battery cell, connect the lithium battery cells and encapsulate them with encapsulation material to obtain a new energy lithium battery with excellent cycle performance.

[0069] Example 4

[0070] This embodiment discloses a method for preparing a composite cathode material, including the following steps:

[0071] Q1: Under a nitrogen atmosphere, 1.05 g formic acid was added to 250 mL of dichloromethane containing 1.28 g p-phenylenediamine, and stirred at 0 °C for 15 min. Then, 1.25 g titanium chloride was added. After the reaction was complete, 5 mL of sodium bicarbonate aqueous solution with a concentration of 0.5 g / mL was added. The mixture was allowed to stand and separate into layers. The aqueous layer was extracted with dichloromethane, and the organic layers were combined. The mixture was dried with magnesium sulfate, rotary evaporated, and purified by chromatography to obtain intermediate product 1.

[0072] Q2: Dissolve 0.77g of intermediate product 1 in 75mL of dichloromethane, add 25mL of distilled water containing 13.13g of cerium ammonium nitrate, stir at 30℃ for 7h, extract, dry with magnesium sulfate, rotary evaporate, and purify by chromatography to obtain intermediate product 2;

[0073] Q3: Mix 1.3g of intermediate product 2, 1.12g of p-phenylenediamine and 150mL of anhydrous ethanol, stir, heat and reflux at 70℃ for 12h. After reflux, cool, filter, wash three times with anhydrous ethanol and distilled water respectively, and dry at 80℃ to obtain composite cathode material.

[0074] This embodiment discloses a method for preparing a modified adhesive, including the following steps:

[0075] S1: 1.2 g sodium tetraborate (decahydrate) and 1.29 g levodopa were added to a container. Under a nitrogen atmosphere, 500 mL of distilled water was added and stirred for 20 min to dissolve the mixture. Then, 2.78 g sodium carbonate was added. 0.41 g methacryloyl chloride was mixed with 1.7 mL tetrahydrofuran and then added dropwise to the container at a rate of 100 mL / h. The mixture was stirred continuously under a nitrogen atmosphere for 24 h. After the reaction was completed, the mixture was extracted with ethyl acetate, and the pH was adjusted to 1 with 1 mol / L hydrochloric acid. The mixture was then rotary evaporated, washed, and dried under vacuum at 50 °C to obtain intermediate product A.

[0076] S2: 28.32g of intermediate product A and 0.086g of azobisisobutyronitrile were added to a container, and 5mL of N,N-dimethylformamide was added to dissolve them. Then, the atmosphere in the container was replaced with nitrogen. After heating at 70℃ for 24h, the mixture was cooled and air was introduced to obtain a polymer. Then, 3g of the polymer was mixed with 5mL of N,N-dimethylformamide and then added dropwise to 50mL of diethyl ether for precipitation. The mixture was filtered, dried, dialyzed, and lyophilized to obtain intermediate product B.

[0077] S3: Dissolve 1.2g of intermediate product B in 10.5mL of 1mol / L hydrochloric acid, stir magnetically for 6h, then add 2.5g of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid), and continue stirring for 4h to obtain the modified binder.

[0078] This embodiment discloses a method for preparing a new energy lithium battery with excellent cycle performance, including the following steps:

[0079] Step (1): Mix 8.5g of composite positive electrode material, 0.45g of modified binder and 12mL of distilled water, grind to obtain positive electrode slurry, then use a film stretcher to uniformly coat the positive electrode slurry onto the surface of aluminum foil, and vacuum dry at 85℃ for 16h to obtain positive electrode structure; Mix 8.5g of graphite, 0.45g of modified binder and 12mL of distilled water, grind to obtain negative electrode slurry, then use a film stretcher to uniformly coat the negative electrode slurry onto the surface of copper foil, and vacuum dry at 85℃ for 16h to obtain negative electrode structure;

[0080] Step (2): Assemble the positive electrode structure, negative electrode structure, separator layer and electrolyte to obtain a lithium battery cell, connect the lithium battery cells and encapsulate them with encapsulation material to obtain a new energy lithium battery with excellent cycle performance.

[0081] Comparative Example 1

[0082] Compared with Example 1, Comparative Example 1 did not add p-phenylenedimethyl ether during the preparation of the composite cathode material, while all other conditions remained unchanged.

[0083] Comparative Example 2

[0084] Compared with Example 1, Comparative Example 2 did not add p-phenylenediamine during the preparation of the composite cathode material, while all other conditions remained unchanged.

[0085] Comparative Example 3

[0086] Compared with Example 1, Comparative Example 3 did not add levodopa during the preparation of the modified adhesive, and all other conditions remained unchanged.

[0087] Comparative Example 4

[0088] Compared with Example 1, Comparative Example 4 did not add poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) during the preparation of the modified adhesive, and all other conditions remained unchanged.

[0089] Comparative Example 5

[0090] Compared with Example 1, Comparative Example 5 uses lithium iron phosphate instead of composite cathode material in the lithium battery preparation process, while keeping other conditions unchanged.

[0091] Comparative Example 6

[0092] Compared with Example 1, Comparative Example 6 used polyvinylidene fluoride instead of the modified binder in the lithium battery preparation process, while keeping other conditions unchanged.

[0093] The samples prepared according to Examples 1-4 and Comparative Examples 1-6 were subjected to performance tests. The cycle performance of the samples was tested according to GB / T 31484-2015, and the energy density was tested according to GB / T 31486-2015. A charge-discharge tester (Shenzhen Xinwei Company) was used to perform rate tests on the samples under the following conditions: 2.5V-4.0V, 25℃, with current densities of 0.2C, 0.5C, and 5C, respectively, increasing from 0.2C to 5C and then returning to 0.2C. The test results are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] As can be seen from the test results in Table 1, the new energy lithium batteries prepared in Examples 1-4 of this invention have excellent cycle performance, energy density and rate performance. Comparing Comparative Example 1 with Examples 1-4, it is evident that adding p-phenylenediamine can give the resulting new energy lithium battery excellent cycle performance, energy density, and rate performance. Comparing Comparative Example 2 with Examples 1-4, it is evident that adding p-phenylenediamine can give the resulting new energy lithium battery excellent cycle performance, energy density, and rate performance. Comparing Comparative Example 3 with Examples 1-4, it is evident that adding levodopa can give the resulting new energy lithium battery excellent cycle performance and rate performance. Comparing Comparative Example 4 with Examples 1-4, it is evident that adding poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) can give the resulting new energy lithium battery excellent cycle performance and rate performance. Comparing Comparative Example 5 with Examples 1-4, it is evident that the use of composite cathode materials can give the resulting new energy lithium battery excellent cycle performance, energy density, and rate performance. Comparing Comparative Example 6 with Examples 1-4, it is evident that the use of modified binders can give the resulting new energy lithium battery excellent cycle performance, energy density, and rate performance.

[0098] 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.

[0099] 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 new energy lithium battery with excellent cycle performance, characterized in that, The device includes a positive electrode structure, a negative electrode structure, a separator layer, an electrolyte, and an encapsulation material. The electrolyte is located between the positive electrode structure and the negative electrode structure. The separator layer is immersed in the electrolyte. The encapsulation material encapsulates the positive electrode structure, the negative electrode structure, the separator layer, and the electrolyte. The positive electrode structure is prepared from a composite positive electrode material, aluminum foil, and a modified binder. The negative electrode structure is prepared from graphite, copper foil, and a modified binder. The preparation method of the composite cathode material includes the following steps: Q1: Under a nitrogen atmosphere, formic acid was added to dichloromethane containing diphenyl ether and stirred at low temperature. Then titanium chloride was added. After the reaction was complete, sodium bicarbonate aqueous solution was added, and the mixture was allowed to stand and separate into layers. The aqueous layer was extracted with dichloromethane, the organic layers were combined, dried, rotary evaporated, and purified by chromatography to obtain intermediate product 1. Q2: Dissolve intermediate 1 in dichloromethane, add distilled water containing cerium ammonium nitrate, stir, extract, dry, rotary evaporate, and purify by chromatography to obtain intermediate 2; Q3: After mixing intermediate product 2, p-phenylenediamine and anhydrous ethanol, the mixture is stirred and heated under reflux. After reflux, the mixture is cooled, filtered, washed, and dried to obtain the composite cathode material. The method for preparing the modified adhesive includes the following steps: S1: Sodium tetraborate decahydrate and levodopa were added to a container. Under a nitrogen atmosphere, distilled water was added and stirred to dissolve the mixture. Then sodium carbonate was added. Methacrylamide chloride and tetrahydrofuran were mixed and then added dropwise to the container. The reaction was stirred continuously under a nitrogen atmosphere. After the reaction was completed, the mixture was extracted, the pH was adjusted, the mixture was rotary evaporated, washed, and vacuum dried to obtain intermediate product A. S2: Add intermediate product A and azobisisobutyronitrile to a container, add N,N-dimethylformamide to dissolve, then replace the atmosphere in the container with nitrogen, heat the reaction, cool, and introduce air to obtain a polymer. Then mix the polymer with N,N-dimethylformamide, and then add it dropwise to diethyl ether for precipitation. Filter, dry, dialyze, and freeze dry to obtain intermediate product B. S3: Dissolve intermediate product B in hydrochloric acid, stir magnetically, then add poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid, and continue stirring to obtain the modified binder.

2. The new energy lithium battery with excellent cycle performance according to claim 1, characterized in that, In Q1, the molar ratio of formic acid, diphenyl ether, and titanium chloride is 3-3.9:1-1.3:1.13-1.47, the low-temperature stirring temperature is 0-1℃, the stirring time is 10-15 min, and it is dried with magnesium sulfate.

3. The new energy lithium battery with excellent cycle performance according to claim 1, characterized in that, In Q2, the molar ratio of intermediate product 1 to cerium ammonium nitrate is 1-1.2:23-27.6, the stirring temperature is 28-30℃, the stirring time is 5-7h, and it is dried with magnesium sulfate. In Q3, the molar ratio of intermediate product 2 to p-phenylenediamine is 1-2:4-6, the stirring and heating reflux temperature is 70-80℃, the time is 12-14h, it is washed 3-5 times with anhydrous ethanol and distilled water respectively, and the drying temperature is 80-85℃.

4. The new energy lithium battery with excellent cycle performance according to claim 1, characterized in that, In S1, the molar ratio of sodium tetraborate decahydrate, levodopa, and methacryloyl chloride is 1-2:2-4:1.2-2.

4. The stirring and dissolution time is 10-20 min, the dropping rate is 100 mL / h, the stirring reaction time is 20-24 h, extraction is performed with ethyl acetate, the pH is adjusted to 1-1.2 with 1 mol / L hydrochloric acid, and the vacuum drying temperature is 50-55℃.

5. The new energy lithium battery with excellent cycle performance according to claim 1, characterized in that, In S2, the molar ratio of intermediate product A to azobisisobutyronitrile is 10-20:0.45-0.9, the heating reaction temperature is 70-75℃, and the reaction time is 22-24h.

6. The new energy lithium battery with excellent cycle performance according to claim 1, characterized in that, In step S3, the ratio of intermediate product B, hydrochloric acid, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid is 1-2g:10-12mL:2-4g, the concentration of hydrochloric acid is 1mol / L, the magnetic stirring time is 4-6h, and the stirring time is continued for 3-5h.

7. The method for preparing a new energy lithium battery with excellent cycle performance as described in any one of claims 1-6, characterized in that, Includes the following steps: Step (1): Mix the composite positive electrode material, modified binder and distilled water, grind them to obtain a positive electrode slurry, and then use a film stretcher to uniformly coat the positive electrode slurry onto the surface of an aluminum foil. After vacuum drying, a positive electrode structure is obtained. Mix the graphite, modified binder and distilled water, grind them to obtain a negative electrode slurry, and then use a film stretcher to uniformly coat the negative electrode slurry onto the surface of a copper foil. After vacuum drying, a negative electrode structure is obtained. Step (2): Assemble the positive electrode structure, negative electrode structure, separator layer and electrolyte to obtain a lithium battery cell, connect the lithium battery cells and encapsulate them with encapsulation material to obtain a new energy lithium battery with excellent cycle performance.

8. The method for preparing a new energy lithium battery with excellent cycle performance according to claim 7, characterized in that, In step (1), the ratio of composite cathode material, modified binder and distilled water is 8-10g: 0.4-0.6g: 10-20mL, the vacuum drying temperature is 80-90℃, and the time is 14-16h. The ratio of graphite, modified binder and distilled water is 8-10g: 0.4-0.6g: 10-20mL, the vacuum drying temperature is 80-90℃, and the time is 14-16h.

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