Preparation method of aluminum-titanium co-doped lithium iron phosphate positive electrode material
By using an aluminum-titanium co-doped lithium iron phosphate cathode material preparation method and a graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive, the problems of uneven doping and low compaction density of lithium iron phosphate cathode materials were solved, achieving efficient electron transport and high energy density.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG LINGYI NEW ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2026-03-16
- Publication Date
- 2026-05-19
AI Technical Summary
Existing lithium iron phosphate cathode materials suffer from problems such as uneven doping, coarse particles, or low compaction density, which affect their performance and applications.
A method for preparing aluminum-titanium co-doped lithium iron phosphate cathode material was adopted. By grafting graphene with maleic anhydride-acrylate-vinylthiophene composite additives, combined with ball milling, calcination and coating treatment, a uniform carbon coating layer was formed, a continuous conductive network was constructed, and the material particle flowability and structural stability were optimized.
It improves the electron transport efficiency of materials, reduces polarization during charge and discharge, enhances high-rate discharge capability and battery energy density, and strengthens structural stability during cycling.
Smart Images
Figure CN122068017A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium iron phosphate cathode material technology, and in particular to a method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material. Background Technology
[0002] Lithium iron phosphate (LFP), as an important cathode material for lithium-ion batteries, boasts numerous advantages such as low cost, high safety, long cycle life, and environmental friendliness, leading to its widespread attention and application in fields like new energy vehicles and energy storage systems. However, LFP also has some significant drawbacks that limit its further development and application.
[0003] Chinese Patent CN120149384B discloses a uniformly carbon-coated lithium iron phosphate cathode material and its preparation method, relating to the field of lithium iron phosphate cathode material technology. The material includes lithium iron phosphate matrix particles, the outer surface of which is coated with a composite carbon layer, and the composite carbon layer is doped with cerium-modified tantalum carbide nanocrystals. The preparation method of the cerium-modified tantalum carbide nanocrystals is as follows: tantalum pentaethoxy and cerium nitrate are dissolved in ethylene glycol, urea is added as a precipitant, and a Ta-Ce-O precursor is synthesized by microwave-assisted solvothermal method; the Ta-Ce-O precursor is mixed with phenolic resin and ball-milled, and then sintered to obtain cerium-modified tantalum carbide nanocrystals.
[0004] Chinese Patent CN120172377B discloses a method for preparing lithium iron phosphate cathode material, cathode material, electrode sheet, and battery. The method includes uniformly mixing a lithium source, iron source, phosphorus source, carbon source, and solvent, and grinding them to obtain a first slurry; wherein the molar ratio of Fe to P in the first slurry is y:z; uniformly mixing the lithium source, iron source, phosphorus source, carbon source, and solvent, and grinding them to obtain a second slurry; wherein the molar ratio of Fe to P in the second slurry is b:c; and y and b satisfy: y:z≥b:c; drying the first slurry once to obtain a first spray material; using the first spray material as a base material and the second slurry as a coating liquid to coat the first spray material, and drying it a second time to obtain a second spray material; sintering and pulverizing the second spray material to obtain the lithium iron phosphate cathode material.
[0005] Existing technologies improve performance through carbon coating or single metal doping, but these technologies suffer from problems such as uneven doping, coarse particles, or low compaction density. Summary of the Invention
[0006] To address the above problems, this invention provides a method for preparing aluminum-titanium co-doped lithium iron phosphate cathode material, the operation steps of which are as follows: S1 First mixing: Add 30-40 parts lithium carbonate, 200-280 parts ferrous sulfate, 95-115 parts phosphoric acid, 3.5-7.5 parts aluminum nitrate, and 1.8-3.4 parts tetrabutyl titanate to a ball mill, add 140-170 parts deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry is dried at 100-120℃ for 8-12 hours to obtain precursor powder; the precursor powder is placed in a muffle furnace for the first calcination. S3 Coating Treatment: After the first calcination, the product is cooled to room temperature and dispersed in 100-200 parts of a deionized aqueous solution containing 5-10 parts of glucose. The ultrasonic power is 200-250W and the ultrasonic time is 30-40min. Then, it is stirred at 70-80℃ for 4-5h, followed by drying at 120-130℃ for 8-12h. Finally, the dried product is coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary Mixing: The coated product, along with 1-5 parts of conductive carbon black and 1-3 parts of graphene-grafted maleic anhydride-acrylate copolymer additive, is added to a planetary ball mill and ball-milled. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: After the product is calcined twice, it is naturally cooled to room temperature and then ground in a grinder for 30-40 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0007] The S1 single-stage mixing ball milling speed is 300-400 r / min, and the ball milling time is 8-12 h.
[0008] The S2 is first calcined by raising the temperature from room temperature to 300-350℃ at a rate of 3-5℃ / min and holding it at that temperature for 2-4 hours; then it is raised to 600-650℃ at a rate of 1-3℃ / min and held at that temperature for 4-8 hours.
[0009] The S3 coating and calcination temperature is 480-520℃, and the time is 3-4 hours.
[0010] The S4 secondary mixing ball milling speed is 400-500 r / min, and the ball milling time is 5-6 h.
[0011] The second calcination temperature of S5 is 750-780℃, and the time is 6-7h.
[0012] The preparation method of the graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive is as follows: H1: Add 30-50 parts of maleic anhydride, 40-60 parts of copper acrylate, 9-16 parts of 2-vinylthiophene, and 300-360 parts of DMF to the reactor, dissolve them at 60-70℃ under nitrogen protection, add 0.5-1.5 parts of AIBN, and react at 75-85℃ for 5-7 hours. H2: After the reaction is complete, cool down to 50-60℃, add 5-10 parts of graphene oxide and ultrasonically disperse for 30-40 min, then react at 80-90℃ for 3-6 h to obtain graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive.
[0013] Reaction mechanism AIBN decomposition initiates the copolymerization of maleic anhydride, copper acrylate, and 2-vinylthiophene with -C=CH2, forming a copolymer backbone containing a thiophene ring. The -OH group of graphene oxide rings ring-opens with the anhydride group of the copolymer to form -COO- bonds, and the thiophene rings and graphene form π-π stacking, constructing a continuous conductive network.
[0014] Technical effect The present invention discloses a method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material. Compared with the prior art, the present invention has the following significant advantages: 1. The graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive prepared by the present invention can reduce the electron transport resistance of aluminum-titanium co-doped lithium iron phosphate, weaken the polarization phenomenon during charging and discharging, and improve the high-rate discharge capability.
[0015] 2. The graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive prepared by the present invention optimizes the flowability of material particles, makes the particles more tightly packed during the compaction process, which is beneficial to improving the energy density of the battery, and enhances the structural stability during the cycle.
[0016] 3. The aluminum-titanium co-doped lithium iron phosphate cathode material prepared by this invention has high discharge specific capacity and high compaction density, and has good market application prospects. Attached Figure Description
[0017] Figure 1 This is the SEM image of Example 1. Detailed Implementation
[0018] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description is provided in conjunction with embodiments and comparative examples: Battery assembly: Using N-methylpyrrolidone as a solvent, aluminum-titanium co-doped lithium iron phosphate cathode material, polyvinylidene fluoride, and conductive carbon black prepared in the examples and comparative examples were mixed evenly at a mass ratio of 90:5:5 to obtain a slurry. The slurry was evenly coated on aluminum foil, vacuum dried, rolled, die-cut, selected, and weighed to obtain the cathode sheet. The cathode sheet and lithium sheet were used as the negative electrode, and lithium iron phosphate electrolyte was used to assemble the battery.
[0019] Electrochemical performance testing: The assembled battery was tested using the Blue Electric testing system at room temperature and with a voltage range of 2.0-3.75V. The discharge specific capacity at 0.1C was also tested.
[0020] Compacted density test: The compacted density test was conducted using a Sansi powder compactor, referring to the national standard GB / T24533-2009. Example 1
[0021] A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 30g lithium carbonate, 200g ferrous sulfate, 95g phosphoric acid, 3.5g aluminum nitrate, and 1.8g tetrabutyl titanate to a ball mill, add 140g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 100℃ for 8 hours to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 100g of deionized water containing 5g of glucose. The ultrasonic power was 200W and the ultrasonic time was 30min. Then, it was stirred at 70℃ for 4h and then dried at 120℃ for 8h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary Mixing: The coated product, along with 1g of conductive carbon black and 1g of graphene-grafted maleic anhydride-acrylate copolymer additive, is added to a planetary ball mill and ball-milled. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 30 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0022] The S1 single-stage mixing ball milling speed is 300 r / min, and the ball milling time is 8 h.
[0023] The S2 is first calcined by heating from room temperature to 300°C at a heating rate of 3°C / min and holding for 2 hours; then it is heated to 600°C at a heating rate of 1°C / min and held for 4 hours.
[0024] The S3 coating and calcination temperature is 480℃ and the time is 3h.
[0025] The S4 secondary mixing ball milling speed is 400 r / min, and the ball milling time is 5 h.
[0026] The second calcination temperature of S5 is 750℃, and the time is 6 hours.
[0027] The preparation method of the graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive is as follows: H1: Add 30g maleic anhydride, 40g copper acrylate, 9g 2-vinylthiophene, and 300g DMF to the reactor, dissolve them at 60℃ under nitrogen protection, add 0.5g AIBN, and react at 75℃ for 5h. H2: After the reaction is complete, the temperature is lowered to 50℃, 5g of graphene oxide is added and ultrasonically dispersed for 30min, and then reacted at 80℃ for 3h to obtain graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive. Example 2
[0028] A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 33g lithium carbonate, 220g ferrous sulfate, 100g phosphoric acid, 4.5g aluminum nitrate, and 2.4g tetrabutyl titanate to a ball mill, add 150g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 105℃ for 9 hours to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 140g of deionized water containing 6g of glucose. The ultrasonic power was 200W and the ultrasonic time was 35min. Then, it was stirred at 75℃ for 4.5h and then dried at 125℃ for 9h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary Mixing: The coated product, along with 2g of conductive carbon black and 2g of graphene-grafted maleic anhydride-acrylate copolymer additive, is added to a planetary ball mill and ball-milled. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 35 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0029] The S1 single-stage mixing ball milling speed is 350 r / min, and the ball milling time is 9 h.
[0030] The S2 is first calcined by raising the temperature from room temperature to 310°C at a rate of 4°C / min and holding it at that temperature for 3 hours; then it is raised to 610°C at a rate of 2°C / min and held at that temperature for 5 hours.
[0031] The S3 coating calcination temperature is 490℃ and the time is 3.5h.
[0032] The S4 secondary mixing ball milling speed is 450 r / min, and the ball milling time is 5.5 h.
[0033] The second calcination temperature of S5 is 760℃, and the time is 6.5h.
[0034] The preparation method of the graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive is as follows: H1: Add 35g maleic anhydride, 45g copper acrylate, 11g 2-vinylthiophene, and 320g DMF to the reactor, dissolve them at 65℃ under nitrogen protection, add 0.8g AIBN, and react at 80℃ for 6h. H2: After the reaction is complete, the temperature is lowered to 55℃, 6g of graphene oxide is added and ultrasonically dispersed for 35min, and then reacted at 85℃ for 4h to obtain graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive. Example 3
[0035] A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 38g lithium carbonate, 260g ferrous sulfate, 110g phosphoric acid, 6.5g aluminum nitrate, and 3g tetrabutyl titanate to a ball mill, add 160g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 115℃ for 11h to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 180g of deionized water containing 8g of glucose. The ultrasonic power was 250W and the ultrasonic time was 35min. Then, it was stirred at 75℃ for 4.5h and then dried at 125℃ for 11h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary Mixing: The coated product, along with 4g of conductive carbon black and 2g of graphene-grafted maleic anhydride-acrylate copolymer additive, is added to a planetary ball mill and ball-milled. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 35 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0036] The S1 single-stage mixing ball milling speed is 350 r / min, and the ball milling time is 11 h.
[0037] The S2 is first calcined by raising the temperature from room temperature to 340°C at a rate of 4°C / min and holding it at that temperature for 3 hours; then it is raised to 640°C at a rate of 2°C / min and held at that temperature for 7 hours.
[0038] The S3 coating calcination temperature is 510℃ and the time is 3.5h.
[0039] The S4 secondary mixing ball milling speed is 450 r / min, and the ball milling time is 5.5 h.
[0040] The second calcination temperature of S5 is 770℃, and the time is 6.5h.
[0041] The preparation method of the graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive is as follows: H1: Add 45g maleic anhydride, 55g copper acrylate, 14g 2-vinylthiophene, and 350g DMF to the reactor, dissolve them at 65℃ under nitrogen protection, add 1.3g AIBN, and react at 80℃ for 6h. H2: After the reaction is complete, the temperature is lowered to 55℃, 8g of graphene oxide is added and ultrasonically dispersed for 35min, and then reacted at 85℃ for 5h to obtain graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive. Example 4
[0042] A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 40g lithium carbonate, 280g ferrous sulfate, 115g phosphoric acid, 7.5g aluminum nitrate, and 3.4g tetrabutyl titanate to a ball mill, add 170g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 120℃ for 12h to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 200g of deionized water containing 10g of glucose. The ultrasonic power was 250W and the ultrasonic time was 40min. Then, it was stirred at 80℃ for 5h and then dried at 130℃ for 12h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary Mixing: The coated product, along with 5g of conductive carbon black and 3g of graphene-grafted maleic anhydride-acrylate copolymer additive, is added to a planetary ball mill and ball-milled. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 40 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0043] The S1 single-stage mixing ball milling speed is 400 r / min, and the ball milling time is 12 h.
[0044] The S2 is first calcined by raising the temperature from room temperature to 350°C at a rate of 5°C / min and holding it at that temperature for 4 hours; then it is raised to 650°C at a rate of 3°C / min and held at that temperature for 8 hours.
[0045] The S3 coating and calcination temperature is 520℃ and the time is 4h.
[0046] The S4 secondary mixing ball milling speed is 500 r / min, and the ball milling time is 6 h.
[0047] The second calcination temperature of S5 is 780℃, and the time is 7h.
[0048] The preparation method of the graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive is as follows: H1: Add 50g maleic anhydride, 60g copper acrylate, 16g 2-vinylthiophene, and 360g DMF to the reactor, dissolve them at 70℃ under nitrogen protection, add 1.5g AIBN, and react at 85℃ for 7h. H2: After the reaction is complete, the temperature is lowered to 60℃, 10g of graphene oxide is added and ultrasonically dispersed for 40min, and then reacted at 90℃ for 6h to obtain graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive.
[0049] Comparative Example 1 A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 30g lithium carbonate, 200g ferrous sulfate, 95g phosphoric acid, 3.5g aluminum nitrate, and 1.8g tetrabutyl titanate to a ball mill, add 140g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 100℃ for 8 hours to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 100g of deionized water containing 5g of glucose. The ultrasonic power was 200W and the ultrasonic time was 30min. Then, it was stirred at 70℃ for 4h and then dried at 120℃ for 8h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary mixing: Add the coated product and 1g of conductive carbon black into a planetary ball mill and ball mill; S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 30 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0050] The S1 single-stage mixing ball milling speed is 300 r / min, and the ball milling time is 8 h.
[0051] The S2 is first calcined by heating from room temperature to 300°C at a heating rate of 3°C / min and holding for 2 hours; then it is heated to 600°C at a heating rate of 1°C / min and held for 4 hours.
[0052] The S3 coating and calcination temperature is 480℃ and the time is 3h.
[0053] The S4 secondary mixing ball milling speed is 400 r / min, and the ball milling time is 5 h.
[0054] The second calcination temperature of S5 is 750℃, and the time is 6 hours.
[0055] Comparative Example 2 A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 30g lithium carbonate, 200g ferrous sulfate, 95g phosphoric acid, 3.5g aluminum nitrate, and 1.8g tetrabutyl titanate to a ball mill, add 140g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 100℃ for 8 hours to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 100g of deionized water containing 5g of glucose. The ultrasonic power was 200W and the ultrasonic time was 30min. Then, it was stirred at 70℃ for 4h and then dried at 120℃ for 8h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary mixing: Add the coated product, 1g of conductive carbon black, and 1g of additives to a planetary ball mill and ball mill. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 30 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0056] The S1 single-stage mixing ball milling speed is 300 r / min, and the ball milling time is 8 h.
[0057] The S2 is first calcined by heating from room temperature to 300°C at a heating rate of 3°C / min and holding for 2 hours; then it is heated to 600°C at a heating rate of 1°C / min and held for 4 hours.
[0058] The S3 coating and calcination temperature is 480℃ and the time is 3h.
[0059] The S4 secondary mixing ball milling speed is 400 r / min, and the ball milling time is 5 h.
[0060] The second calcination temperature of S5 is 750℃, and the time is 6 hours.
[0061] The preparation method of the aforementioned auxiliary agent is as follows: H1: Add 30g maleic anhydride, 9g 2-vinylthiophene, and 300g DMF to the reactor, dissolve them at 60℃ under nitrogen protection, add 0.5g AIBN, and react at 75℃ for 5h. H2: After the reaction is complete, the temperature is lowered to 50℃, 5g of graphene oxide is added and ultrasonically dispersed for 30min, and then reacted at 80℃ for 3h to obtain the auxiliary agent.
[0062] Comparative Example 3 A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 30g lithium carbonate, 200g ferrous sulfate, 95g phosphoric acid, 3.5g aluminum nitrate, and 1.8g tetrabutyl titanate to a ball mill, add 140g deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry was dried at 100℃ for 8 hours to obtain precursor powder; the precursor powder was placed in a muffle furnace for the first calcination. S3 Coating Treatment: The product after the first calcination was cooled to room temperature and dispersed in 100g of deionized water containing 5g of glucose. The ultrasonic power was 200W and the ultrasonic time was 30min. Then, it was stirred at 70℃ for 4h and then dried at 120℃ for 8h. Finally, the dried product was coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary mixing: Add the coated product, 1g of conductive carbon black, and 1g of additives to a planetary ball mill and ball mill. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: The product after secondary calcination was naturally cooled to room temperature and then ground in a grinder for 30 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
[0063] The S1 single-stage mixing ball milling speed is 300 r / min, and the ball milling time is 8 h.
[0064] The S2 is first calcined by heating from room temperature to 300°C at a heating rate of 3°C / min and holding for 2 hours; then it is heated to 600°C at a heating rate of 1°C / min and held for 4 hours.
[0065] The S3 coating and calcination temperature is 480℃ and the time is 3h.
[0066] The S4 secondary mixing ball milling speed is 400 r / min, and the ball milling time is 5 h.
[0067] The second calcination temperature of S5 is 750℃, and the time is 6 hours.
[0068] The preparation method of the aforementioned auxiliary agent is as follows: H1: Add 30g maleic anhydride, 40g copper acrylate and 300g DMF to the reactor, dissolve them at 60℃ under nitrogen protection, add 0.5g AIBN, and react at 75℃ for 5h. H2: After the reaction is complete, the temperature is lowered to 50℃, 5g of graphene oxide is added and ultrasonically dispersed for 30min, and then reacted at 80℃ for 3h to obtain the auxiliary agent.
[0069] Discharge specific capacity / mAh / g <![CDATA[Compaction density / g / cm 3 > Example 1 156.8 2.61 Example 2 157.2 2.63 Example 3 158.0 2.65 Example 4 158.3 2.66 Comparative Example 1 123.5 2.23 Comparative Example 2 147.6 2.48 Comparative Example 3 148.2 2.51 Based on the data analysis of the above embodiments and comparative examples, the aluminum-titanium co-doped lithium iron phosphate cathode material prepared by the present invention has high discharge specific capacity and high compaction density, and has good market application prospects.
[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material, comprising the following steps: S1 First mixing: Add 30-40 parts lithium carbonate, 200-280 parts ferrous sulfate, 95-115 parts phosphoric acid, 3.5-7.5 parts aluminum nitrate, and 1.8-3.4 parts tetrabutyl titanate to a ball mill, add 140-170 parts deionized water, and ball mill to obtain a uniform slurry. S2 First Calcination: The mixture slurry is dried at 100-120℃ for 8-12 hours to obtain precursor powder; the precursor powder is placed in a muffle furnace for the first calcination. S3 Coating Treatment: After the first calcination, the product is cooled to room temperature and dispersed in 100-200 parts of a deionized aqueous solution containing 5-10 parts of glucose. The ultrasonic power is 200-250W and the ultrasonic time is 30-40min. Then, it is stirred at 70-80℃ for 4-5h, followed by drying at 120-130℃ for 8-12h. Finally, the dried product is coated and calcined in a muffle furnace to form a carbon coating layer. S4 Secondary Mixing: The coated product, along with 1-5 parts of conductive carbon black and 1-3 parts of graphene-grafted maleic anhydride-acrylate copolymer additive, is added to a planetary ball mill and ball-milled. S5 Second Calcination: The material after the second mixing is placed in a tube furnace and calcined under nitrogen protection. S6 Post-processing: After the product is calcined twice, it is naturally cooled to room temperature and then ground in a grinder for 30-40 minutes to obtain aluminum-titanium co-doped lithium iron phosphate cathode material.
2. The method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material according to claim 1, characterized in that: The S1 single-stage mixing ball milling speed is 300-400 r / min, and the ball milling time is 8-12 h.
3. The method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material according to claim 1, characterized in that: The S2 is first calcined by raising the temperature from room temperature to 300-350℃ at a rate of 3-5℃ / min and holding it at that temperature for 2-4 hours; then it is raised to 600-650℃ at a rate of 1-3℃ / min and held at that temperature for 4-8 hours.
4. The method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material according to claim 1, characterized in that: The S3 coating and calcination temperature is 480-520℃, and the time is 3-4 hours.
5. The method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material according to claim 1, characterized in that: The S4 secondary mixing ball milling speed is 400-500 r / min, and the ball milling time is 5-6 h.
6. The method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material according to claim 1, characterized in that: The second calcination temperature of S5 is 750-780℃, and the time is 6-7h.
7. The method for preparing an aluminum-titanium co-doped lithium iron phosphate cathode material according to claim 1, characterized in that: The preparation method of the graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive is as follows: H1: Add 30-50 parts of maleic anhydride, 40-60 parts of copper acrylate, 9-16 parts of 2-vinylthiophene, and 300-360 parts of DMF to the reactor, dissolve them at 60-70℃ under nitrogen protection, add 0.5-1.5 parts of AIBN, and react at 75-85℃ for 5-7 hours. H2: After the reaction is complete, cool down to 50-60℃, add 5-10 parts of graphene oxide and ultrasonically disperse for 30-40 min, then react at 80-90℃ for 3-6 h to obtain graphene-grafted maleic anhydride-acrylate-vinylthiophene composite additive.