Preparation of battery positive material precursor iron phosphate by using titanium white waste acid

Abstract

The application discloses a kind of preparation battery positive grade material precursor iron phosphate using titanium white waste acid, comprising the following steps: step one first utilizes titanium white waste acid to prepare iron phosphate initial body, realizes the comprehensive utilization of titanium white waste acid;Step two is that iron phosphate initial body is modified, then 10-15% of bentonite complexing agent of step two product total amount, 10% of lithium carbonate of step two product total amount, 5% of composite carbon source are added to step two product, composite carbon source is 1:1 mixed grape sugar, citric acid, ball mill modification processing is sent into ball mill, ball mill is ended, washing, the raw material between the adjusting liquid in the application can enhance the activity degree and dispersity of bentonite, in the coordination of carbon fluoride, silane coupling agent KH560, lignin liquid coordination agent, so as to optimize the improvement effect of bentonite complexing agent on iron phosphate initial body, and then the product can not only have excellent capacity retention rate, but also the acid corrosion resistance, temperature resistance of product can reach coordinated improvement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium white waste acid recycling, in particular to a method for preparing battery positive material precursor iron phosphate by using titanium white waste acid. BACKGROUND

[0002] Since lithium ion batteries have the characteristics of high specific energy, long service life, no pollution, etc., they have been rapidly popularized and developed since their inception. Currently, lithium battery positive materials mainly include lithium cobaltate, lithium iron phosphate, lithium manganate and ternary materials. Compared with other lithium battery positive materials, lithium iron phosphate positive material has the advantages of high safety, long cycle life and low manufacturing cost, and is the most potential lithium ion battery positive material. Therefore, iron phosphate lithium is prepared by using precursor iron phosphate.

[0003] The existing titanium white waste acid is rarely utilized, resulting in waste of resources, and even less for preparing precursor iron phosphate. Chinese patent document CN106379946A discloses a method for producing ferrous magnesium sulfate by using titanium white waste acid and phosphate ore flotation tailings. The document provides a method for producing ferrous magnesium sulfate, but how to produce iron phosphate from ferrous magnesium sulfate still needs to be researched and improved. Based on this, the present application further researches and provides a method for preparing battery positive material precursor iron phosphate by using titanium white waste acid. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a method for preparing battery positive material precursor iron phosphate by using titanium white waste acid to solve the problems raised in the background art.

[0005] The technical problem solved by the present application adopts the following technical scheme:

[0006] The present application provides a method for preparing battery positive material precursor iron phosphate by using titanium white waste acid, comprising the following steps:

[0007] Step 1: Add concentrated sulfuric acid to the titanium white waste acid supernatant, adjust the mass concentration of sulfuric acid in the titanium white waste acid to 70%, fully stir, then cool to below 80℃, crystallize, mature, add titanium white waste acid, reduce the mass concentration of sulfuric acid therein to 55%, fully stir, and perform solid-liquid separation to obtain concentrated sulfuric acid and ferrous slag;

[0008] Add 5-10% by mass of ferrous salt solution to the total amount of ferrous salt solution, stir and uniformly disperse, then add 10-15% of the total amount of ferrous salt solution to 25% by mass of sodium phosphate solution, and then inject 1×10 5ppm ozone, then adjust pH value to 2.6 by sodium hydroxide, then react at 50-55℃ for 1-2h, end the reaction, wash with water, dry, then calcine at 700℃ for 8-12h to obtain the initial iron phosphate;

[0009] Step two: put the initial iron phosphate of step one into 5-10 times of the modification liquid for modification treatment, after stirring, wash with water, dry;

[0010] Step three: preparation of bentonite reconditioning agent:

[0011] S01: put the bentonite into heat treatment at 210-230℃ for 10-20min, then heat to 300-350℃ at a rate of 2-5℃ / min, keep for 5-10min, then cool to 45-50℃ at a rate of 1-3℃ / min, keep, ready for use;

[0012] S02: put the product of S01 into the adjusting liquid of 2-5 times of the total amount of S01 product for ultrasonic dispersion for 10-20min, the ultrasonic power is 450-500W, after ultrasonic, wash with water, dry;

[0013] S03: add the complexing agent of 5-10% of the total amount of S02 product into the product of S02, continue to stir fully to obtain the bentonite reconditioning agent.

[0014] Step four: add the bentonite reconditioning agent of 10-15% of the total amount of step two product, lithium carbonate of 10% of the total amount of step two product, and the composite carbon source of 5% into the product of step two, the composite carbon source is a mixture of glucose and citric acid at a ratio of 1:1, put into the ball mill for modification treatment, after ball milling, wash with water, dry, then calcine at 700℃ for 10h to obtain the lithium battery positive electrode material.

[0015] Preferably, the preparation method of the modification liquid is:

[0016] S11: add the chitosan aqueous solution of 10-15% of the total amount of hydrochloric acid solution into the hydrochloric acid solution, then stir uniformly;

[0017] S12: soak the viscose fiber in the sodium hydroxide solution with a mass fraction of 5% for 10-12h, then filter, wash with water until the washing liquid is neutral, then react in the permanganate with a concentration of 1-2mol / L for 20h, the reaction temperature is 65-75℃, then filter, wash with water, freeze-dry to obtain the cellulose nanospheres;

[0018] S13: add 1-3 parts of sodium dodecyl sulfate into 5-10 parts of deionized water, then add 2-5 parts of cellulose nanospheres, stir fully to obtain the additive;

[0019] S14: the additive is sent into the product of S11 to be stirred evenly, and a modified liquid is obtained.

[0020] Preferably, the mass fraction of the hydrochloric acid solution is 5-8%.

[0021] Preferably, the mass fraction of the chitosan aqueous solution is 6-9%.

[0022] Preferably, the stirring time of the stirring modification is 20-30 min, the stirring temperature is 40-45 DEG C, and the stirring time is 550-650 r / min.

[0023] Preferably, the specific preparation steps of the adjusting liquid are as follows:

[0024] The lanthanum sulfate solution and the yttrium nitrate solution are subjected to primary stirring treatment at a weight ratio of 3:1, then 10-15% of the total amount of the lanthanum sulfate solution is added into 5% of a sodium alginate aqueous solution and 1-5% of a silica sol, and secondary stirring treatment is carried out, so that the adjusting liquid is obtained after the stirring is completed.

[0025] Preferably, the mass fractions of the lanthanum sulfate solution and the yttrium nitrate solution are 5-8% and 1-3% respectively.

[0026] Preferably, the rotating speed of the primary stirring treatment is 450-550 r / min, and the stirring time is 20-30 min; the rotating speed of the secondary stirring treatment is 1050-1250 r / min, and the stirring time is 5-10 min.

[0027] Preferably, the preparation method of the complexing agent is as follows:

[0028] S101: lignin is sent into 2-3 times of a mass fraction 5% sodium hydroxide solution to be subjected to reaction treatment, the reaction temperature is 100-110 DEG C, the reaction time is 10-20 min, and a lignin liquid is obtained;

[0029] S102: carbon fluoride is sent into 3-5 times of an ethanol solvent, then 5-10% of the total amount of the carbon fluoride is added into a silane coupling agent KH560 and 1-3% of the lignin liquid, the mixture is stirred evenly, and then water washing and drying are carried out, so that the complexing agent is obtained.

[0030] Preferably, the rotating speed of the ball milling modification treatment is 1000-1500 r / min, and the ball milling time is 35-45 min.

[0031] Compared with the prior art, the present application has the beneficial effects as follows:

[0032] This invention utilizes waste acid from titanium dioxide as a raw material to prepare a precursor of iron phosphate, achieving comprehensive utilization of the waste acid and reducing the production cost of iron phosphate battery materials. The precursor is then modified by stirring in a modifying solution, and further optimized through ball milling with a bentonite compounding agent. The resulting product exhibits excellent capacity retention, while its performance, including temperature resistance and acid corrosion resistance, is synergistically improved. The modifying solution uses hydrochloric acid solution combined with chitosan aqueous solution as a matrix, with cellulose nanospheres and sodium dodecyl sulfate added as additives. This optimized solution effectively activates the interfacial structure of the precursor of iron phosphate. The high specific surface area of ​​the nanospheres facilitates better ball milling modification with the bentonite compounding agent. The bentonite compounding agent is then heat-treated at 210-230℃ for 10-20 minutes using bentonite. Then, the temperature is increased to 300-350℃ at a rate of 2-5℃ / min and held for 5-10 minutes. Subsequently, it is cooled to 45-50℃ at a rate of 1-3℃ / min to increase the interlayer spacing and optimize the interlayer space capacity. At a constant temperature of 45-50℃, the product is treated with a conditioning solution. The lanthanum sulfate solution, yttrium nitrate solution, sodium alginate aqueous solution, and silica sol in the conditioning solution are stirred in stages to optimize the mixing degree of the conditioning solution. At the same time, the raw materials in the conditioning solution are coordinated to enhance the activity and dispersibility of bentonite. With the coordination of fluorinated carbon, silane coupling agent KH560, and lignin solution as a coordinating agent, the improvement effect of the bentonite compounding agent on the primary iron phosphate is coordinated and optimized. As a result, the product not only has excellent capacity retention, but also achieves coordinated improvement in acid resistance and temperature resistance. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. 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] This embodiment describes a method for preparing iron phosphate, a precursor for battery cathode materials, using waste acid from titanium dioxide. The method includes the following steps:

[0035] Step 1: Add concentrated sulfuric acid to the titanium dioxide waste acid solution to adjust the mass concentration of sulfuric acid in the titanium dioxide waste acid to 70%, stir thoroughly, then cool to below 80℃ for crystallization and aging. Add titanium dioxide waste acid to reduce the mass concentration of sulfuric acid to 55%, stir thoroughly, and perform solid-liquid separation to obtain concentrated sulfuric acid and ferrous slag; this is the existing technology.

[0036] The ferrous salt solution with mass fraction of 5-10% is stirred and uniformly dispersed with 5% of the total amount of ferrous salt solution of alkylol amide, then 10-15% of the total amount of ferrous salt solution of 25% mass fraction of sodium phosphate solution is added, then 1×10 5 ppm ozone, then the pH value is adjusted to 2.6 by sodium hydroxide, then the reaction is carried out at 50-55℃ for 1-2h, after the reaction is completed, water washing and drying, calcination at 700℃ for 8-12h, to obtain the initial body of iron phosphate;

[0037] Step two: the initial body of iron phosphate in step one is stirred and modified in 5-10 times of the modified solution, after stirring, water washing and drying;

[0038] Step three: preparation of bentonite reconditioning agent:

[0039] S01: the bentonite is heated at 210-230℃ for 10-20min, then heated to 300-350℃ at a rate of 2-5℃ / min, and kept for 5-10min, then cooled to 45-50℃ at a rate of 1-3℃ / min, and kept for 5-10min, and standby;

[0040] S02: the product of S01 is added to 2-5 times of the total amount of S01 product of adjusting solution and ultrasonically dispersed for 10-20min, the ultrasonic power is 450-500W, after ultrasonic, water washing and drying;

[0041] S03: 5-10% of the total amount of S02 product of complexing agent is added to the product of S02, and stirred fully, to obtain the bentonite reconditioning agent.

[0042] Step four: 10-15% of the total amount of step two product of bentonite reconditioning agent, 10% of the total amount of step two product of lithium carbonate and 5% of the composite carbon source which is 1:1 mixture of glucose and citric acid are added to the product of step two, and sent to the ball mill for modification, after ball milling, water washing and drying, calcination at 700℃ for 10h, to obtain the lithium battery positive electrode material.

[0043] The preparation method of the modified solution in the embodiment is:

[0044] S11: chitosan aqueous solution is added to the total amount of 10-15% of hydrochloric acid solution, and then stirred uniformly;

[0045] S12: the viscose fiber is soaked in 5% mass fraction of sodium hydroxide solution for 10-12h, then filtered, water washed until the water washing liquid is neutral, then placed in 1-2mol / L of permanganate solution for 20h, the reaction temperature is 65-75℃, then filtered, water washed and freeze-dried, to obtain the cellulose nanospheres;

[0046] S13: 1-3 parts of sodium dodecyl sulfate is added to 5-10 parts of deionized water, then 2-5 parts of cellulose nanospheres are added, and stirred thoroughly to obtain an additive;

[0047] S14: The additive is added into the product of S11 and stirred uniformly to obtain a modified liquid.

[0048] The mass fraction of the hydrochloric acid solution in this embodiment is 5-8%.

[0049] The mass fraction of the chitosan aqueous solution in this embodiment is 6-9%.

[0050] The stirring time of the stirring modification in this embodiment is 20-30 min, the stirring temperature is 40-45℃, and the stirring speed is 550-650 r / min.

[0051] The specific preparation steps of the adjusting liquid in this embodiment are as follows:

[0052] The lanthanum sulfate solution and the yttrium nitrate solution are first stirred at a weight ratio of 3:1, then 10-15% of the total amount of the lanthanum sulfate solution, 5% of a sodium alginate aqueous solution, and 1-5% of a silica sol are added, and the second stirring treatment is performed, to obtain the adjusting liquid.

[0053] The mass fraction of the lanthanum sulfate solution and the yttrium nitrate solution in this embodiment is 5-8% and 1-3%, respectively.

[0054] The first stirring treatment in this embodiment is performed at a speed of 450-550 r / min for 20-30 min, and the second stirring treatment is performed at a speed of 1050-1250 r / min for 5-10 min.

[0055] The preparation method of the complexing agent in this embodiment is as follows:

[0056] S101: The lignin is added into 2-3 times of a 5% mass fraction sodium hydroxide solution for reaction treatment, the reaction temperature is 100-110℃, and the reaction time is 10-20 min, to obtain a lignin liquid;

[0057] S102: The carbon fluoride is added into 3-5 times of an ethanol solvent, then 5-10% of the total amount of the carbon fluoride, a silane coupling agent KH560, and 1-3% of the lignin liquid are added, and stirred uniformly, then washed with water and dried, to obtain the complexing agent.

[0058] The ball milling speed of the ball milling modification treatment in this embodiment is 1000-1500 r / min, and the ball milling time is 35-45 min.

[0059] Embodiment 1

[0060] The preparation of the battery positive material precursor iron phosphate by using titanium white waste acid in the embodiment comprises the following steps:

[0061] Step one: 5% ferrous salt solution is added with 5% alkylolamide of the total amount of ferrous salt solution, and then 25% sodium phosphate solution of the total amount of 10% ferrous salt solution is added, and then 1×10 5 ppm ozone, and then the pH value is adjusted to 2.6 by using sodium hydroxide, and then the reaction is carried out at 50℃ for 1h, and then the reaction is ended, and then water washing and drying are carried out, and then calcination is carried out at 700℃ for 8-12h to obtain the iron phosphate primary body;

[0062] Step two: the iron phosphate primary body in step one is sent into 5 times of the modified liquid for stirring and modification treatment, and then stirring is ended, and then water washing and drying are carried out;

[0063] Step three: preparation of bentonite complex modifier:

[0064] S01: bentonite is sent into heat treatment at 210℃ for 10min, and then the temperature is increased to 300℃ at a rate of 2℃ / min, and then the temperature is kept for 5min, and then the temperature is cooled to 45℃ at a rate of 1℃ / min, and then the temperature is kept, and then the product is prepared for use;

[0065] S02: the product in S01 is added into the adjusting liquid of 2 times of the total amount of the product in S01 for ultrasonic dispersion for 10min, and then the ultrasonic power is 450W, and then the ultrasonic dispersion is ended, and then water washing and drying are carried out;

[0066] S03: the product in S02 is added with 5% complexing agent of the total amount of the product in S02, and then stirring is continuously carried out to obtain the bentonite complex modifier.

[0067] Step four: 10% bentonite complex modifier of the total amount of the product in step two, 10% lithium carbonate of the total amount of the product in step two and 5% composite carbon source which is a mixture of glucose and citric acid in a ratio of 1:1 are added into the product in step two, and then the mixture is sent into a ball mill for ball milling modification treatment, and then the ball milling is ended, and then water washing and drying are carried out, and then calcination is carried out at 700℃ for 10h to obtain the lithium battery positive material.

[0068] The preparation method of the modified liquid in the embodiment is as follows:

[0069] S11: chitosan aqueous solution of 10% of the total amount of hydrochloric acid solution is added into the hydrochloric acid solution, and then stirring is uniformly carried out;

[0070] S12: viscose fibers are soaked in 5% sodium hydroxide solution for 10h, and then the fibers are filtered, and then water washing is carried out until the water washing liquid is neutral, and then the fibers are placed in permanganate with a concentration of 1mol / L for reaction for 20h, and then the reaction temperature is 65℃, and then the fibers are filtered, and then water washing and freeze-drying are carried out to obtain the cellulose nanospheres.

[0071] S13: 1 part of sodium dodecyl sulfate is added to 5 parts of deionized water, then 2 parts of cellulose nanospheres are added, and stirred thoroughly to obtain an additive;

[0072] S14: The additive is added into the product of S11 and stirred uniformly to obtain a modified liquid.

[0073] The mass fraction of the hydrochloric acid solution in this embodiment is 5%.

[0074] The mass fraction of the chitosan aqueous solution in this embodiment is 6%.

[0075] The stirring time of the stirring modification in this embodiment is 20 min, the stirring temperature is 40℃, and the stirring speed is 550 r / min.

[0076] The specific preparation steps of the adjusting liquid in this embodiment are as follows:

[0077] The lanthanum sulfate solution and the yttrium nitrate solution are first stirred at a weight ratio of 3:1, then 10% of the total amount of the lanthanum sulfate solution, 5% of the mass fraction of the sodium alginate aqueous solution, and 1% of the silica sol are added, and the second stirring treatment is performed, to obtain the adjusting liquid.

[0078] The mass fractions of the lanthanum sulfate solution and the yttrium nitrate solution in this embodiment are 5% and 1%, respectively.

[0079] The first stirring treatment in this embodiment is performed at a speed of 450 r / min for 20 min, and the second stirring treatment is performed at a speed of 1050 r / min for 5 min.

[0080] The preparation method of the complexing agent in this embodiment is as follows:

[0081] S101: The lignin is added into 2 times of the mass fraction 5% sodium hydroxide solution for reaction treatment, the reaction temperature is 100℃, and the reaction time is 10 min, to obtain a lignin liquid;

[0082] S102: The carbon fluoride is added into 3 times of the ethanol solvent, then 5% of the total amount of the carbon fluoride, the silane coupling agent KH560, and 1% of the lignin liquid are added, and stirred uniformly, then washed with water and dried, to obtain the complexing agent.

[0083] The ball milling speed of the ball milling modification treatment in this embodiment is 1000 r / min, and the ball milling time is 35 min.

[0084] Embodiment 2

[0085] The embodiment for preparing the battery positive material precursor iron phosphate from titanium white waste acid includes the following steps:

[0086] Step one: add 10% ferrous salt solution to the total amount of 5% alkyl alcohol amide, stir evenly, then add 25% sodium phosphate solution to the total amount of 15% ferrous salt solution, then inject 1×10 5 ppm ozone, then adjust the pH value to 2.6 with sodium hydroxide, then react at 55℃ for 2h, after the reaction, wash with water, dry, and then calcine at 700℃ for 12h to obtain the initial iron phosphate body;

[0087] Step two: put the initial iron phosphate body of step one into 10 times the modified liquid for stirring modification, after stirring, wash with water and dry;

[0088] Step three: preparation of bentonite reconditioning agent:

[0089] S01: put the bentonite into a heat treatment at 230℃ for 20min, then heat to 350℃ at a rate of 5℃ / min, keep for 10min, then cool to 50℃ at a rate of 3℃ / min, keep, and reserve;

[0090] S02: add the product of S01 to the adjusting liquid which is 5 times the total amount of S01 product, ultrasonic dispersion for 20min, ultrasonic power is 500W, after ultrasonic, wash with water and dry;

[0091] S03: add 10% complexing agent to the total amount of S02 product, continue to stir fully to obtain the bentonite reconditioning agent.

[0092] Step four: add 15% bentonite reconditioning agent to the total amount of step two product, 10% lithium carbonate to the total amount of step two product, and 5% composite carbon source to the total amount of step two product, the composite carbon source is a 1:1 mixture of glucose and citric acid, put into the ball mill for modification, after ball milling, wash with water and dry, then calcine at 700℃ for 10h to obtain the lithium battery positive electrode material.

[0093] The preparation method of the modified liquid in this embodiment is:

[0094] S11: add chitosan aqueous solution to the total amount of 15% hydrochloric acid solution, then stir evenly;

[0095] S12: soak the viscose fiber in 5% sodium hydroxide solution for 12h, then filter, wash with water until the washing liquid is neutral, then react in 2mol / L permanganate solution for 20h, the reaction temperature is 75℃, then filter, wash with water and freeze-dry to obtain the cellulose nanospheres;

[0096] S13: add 3 parts of sodium dodecyl sulfate to 10 parts of deionized water, then add 5 parts of cellulose nanospheres, stir fully to obtain the additive;

[0097] S14: The additive is added into the product of S11 and stirred to obtain a modified solution.

[0098] The mass fraction of the hydrochloric acid solution in this embodiment is 8%.

[0099] The mass fraction of the chitosan aqueous solution in this embodiment is 9%.

[0100] The stirring time of the stirring modification in this embodiment is 30 min, the stirring temperature is 45°C, and the stirring speed is 650 r / min.

[0101] The specific preparation steps of the adjusting solution in this embodiment are as follows:

[0102] The lanthanum sulfate solution and the yttrium nitrate solution are first stirred at a weight ratio of 3:1, then 15% of the total amount of the lanthanum sulfate solution is added into 5% of a sodium alginate aqueous solution and 5% of a silica sol, and the second stirring treatment is performed, to obtain the adjusting solution.

[0103] The mass fractions of the lanthanum sulfate solution and the yttrium nitrate solution in this embodiment are 8% and 3%, respectively.

[0104] The rotating speed of the first stirring treatment in this embodiment is 550 r / min, and the stirring time is 30 min; the rotating speed of the second stirring treatment is 1250 r / min, and the stirring time is 10 min.

[0105] The preparation method of the complexing agent in this embodiment is as follows:

[0106] S101: The lignin is added into 3 times of a 5% mass fraction sodium hydroxide solution for reaction treatment, the reaction temperature is 110°C, the reaction time is 20 min, and a lignin solution is obtained;

[0107] S102: The carbon fluoride is added into 5 times of an ethanol solvent, then 10% of the total amount of the carbon fluoride is added into a silane coupling agent KH560 and 3% of the lignin solution, the mixture is stirred uniformly, and then washed with water and dried, to obtain the complexing agent.

[0108] The rotating speed of the ball milling modification in this embodiment is 1500 r / min, and the ball milling time is 45 min.

[0109] Embodiment 3

[0110] The embodiment for preparing the battery positive material precursor iron phosphate from titanium white waste acid includes the following steps:

[0111] Step one: 5% of the total amount of the ferrous salt solution is added into an alkylolamide, stirred and uniformly dispersed, then 12.5% of the total amount of the ferrous salt solution is added into a 25% mass fraction sodium phosphate solution, and then 1×105 ppm ozone, then adjust pH value to 2.6 by sodium hydroxide, then react at 52℃ for 1.5h, end the reaction, wash with water, dry, then calcine at 700℃ for 10h, to obtain the initial iron phosphate;

[0112] Step two: put the initial iron phosphate of step one into 7.5 times of the modification liquid for stirring modification treatment, end the stirring, wash with water, dry;

[0113] Step three: preparation of bentonite re-adjusting agent:

[0114] S01: put the bentonite into heat treatment at 220℃ for 15min, then heat up to 325℃ at a rate of 3℃ / min, keep for 5-10min, then cool down to 47℃ at a rate of 2℃ / min, keep, standby;

[0115] S02: put the product of S01 into the adjusting liquid of 3.5 times of the total amount of the product of S01 for ultrasonic dispersion for 15min, ultrasonic power is 470W, end the ultrasonic, wash with water, dry;

[0116] S03: put 12.5% of the bentonite re-adjusting agent of the total amount of the product of step two, 10% of lithium carbonate of the total amount of the product of step two, 5% of the composite carbon source of the total amount of the product of step two into the product of step two, the composite carbon source is 1:1 mixture of glucose and citric acid, put into the ball mill for ball milling modification treatment, end the ball milling, wash with water, dry, then calcine at 700℃ for 10h, to obtain the positive electrode material for lithium battery.

[0117] Step four: put 12% of the bentonite re-adjusting agent of the total amount of the product of step two into the product of step two, put into the ball mill for ball milling modification treatment, end the ball milling, wash with water, dry, to obtain the precursor iron phosphate.

[0118] The preparation method of the modification liquid of the embodiment is:

[0119] S11: add the chitosan aqueous solution of 12% of the total amount of the hydrochloric acid solution into the hydrochloric acid solution, then stir uniformly;

[0120] S12: soak the viscose fiber in the sodium hydroxide solution of mass fraction 5% for 11h, then filter, wash with water until the washing liquid is neutral, then put into the permanganate of concentration 1.1mol / L for reaction for 20h, reaction temperature is 70℃, then filter, wash with water, freeze-dry, to obtain the cellulose nanospheres;

[0121] S13: add 2 parts of sodium dodecyl sulfate into 7.5 parts of deionized water, then add 3.5 parts of cellulose nanospheres, stir fully, to obtain the additive;

[0122] S14: put the additive into the product of S11 for stirring uniformly, to obtain the modification liquid.

[0123] The mass fraction of the hydrochloric acid solution of this embodiment is 6.5%.

[0124] The mass fraction of the chitosan aqueous solution of this embodiment is 7.5%.

[0125] The stirring time of the stirring modification of this embodiment is 25 min, the stirring temperature is 42℃, and the stirring speed is 600 r / min.

[0126] The specific preparation steps of the adjusting solution of this embodiment are as follows:

[0127] The lanthanum sulfate solution and the yttrium nitrate solution are first stirred at a weight ratio of 3:1, and then 12% of the total amount of the lanthanum sulfate solution is added to the adjusting solution, and the stirring speed is 500 r / min, the stirring time is 25 min; the stirring speed of the second stirring treatment is 1150 r / min, and the stirring time is 7.5 min.

[0128] The mass fraction of the lanthanum sulfate solution and the yttrium nitrate solution of this embodiment is 6.5% and 2% respectively.

[0129] The stirring speed of the first stirring treatment of this embodiment is 500 r / min, and the stirring time is 25 min; the stirring speed of the second stirring treatment is 1150 r / min, and the stirring time is 7.5 min.

[0130] The preparation method of the complexing agent of this embodiment is as follows:

[0131] S101: The lignin is sent into 2.5 times of the mass fraction 5% sodium hydroxide solution for reaction treatment, the reaction temperature is 105℃, the reaction time is 15 min, and the lignin solution is obtained;

[0132] S102: The carbon fluoride is sent into 4 times of the ethanol solvent, and then 7.5% of the total amount of the carbon fluoride is added to the complexing agent KH560 and 2% of the lignin solution, and then stirred uniformly, and then washed with water and dried to obtain the complexing agent.

[0133] The ball milling speed of the ball milling modification treatment of this embodiment is 1250 r / min, and the ball milling time is 40 min.

[0134] Comparative Example 1.

[0135] Different from Example 3 is that the modifying solution is not used.

[0136] Comparative Example 2.

[0137] Different from Example 3 is that the cellulose nanospheres are not added in the preparation of the modifying solution.

[0138] Comparative Example 3.

[0139] Different from Example 3 is that the adjusting solution is replaced by deionized water.

[0140] Comparative Example 4.

[0141] Unlike Example 3, no ligand treatment was used.

[0142] Comparative Example 5.

[0143] Unlike Example 3, no lignin solution was added during the preparation of the coordination agent.

[0144] Comparative Example 6.

[0145] The difference from Example 3 is the preparation method of the conditioning solution;

[0146] Add 12.5% ​​(w / w) of sodium alginate aqueous solution to a 6.5% (w / w) lanthanum sulfate solution. After stirring, the conditioning solution is obtained. The stirring speed is 1100 r / min and the stirring time is 25 min.

[0147] The products of Examples 1-3 and Comparative Examples 1-6 were subjected to performance tests.

[0148]

[0149] As can be seen from Comparative Examples 1-6 and Examples 1-3, the product of Example 3 has excellent capacity retention after 100 cycles. At the same time, the capacity retention of the product can play a role in coordinating and improving efficiency under acidic and high-temperature conditions.

[0150] The performance of the products showed a significant deterioration trend when no modified liquid treatment, complexing agent treatment, or deionized water was used instead of conditioning liquid.

[0151] Different preparation methods for the conditioning liquid, the absence of lignin solution in the preparation of the coordination agent, and the absence of cellulose nanospheres in the preparation of the modification liquid all lead to a deterioration in the performance of the products. Only the conditioning liquid, coordination agent, and modification liquid prepared using the method of this invention show a significant improvement in product performance.

[0152] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0153] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature or implementation described herein. The specification can include implicit combinations of explicitly mentioned features and / or implicit combinations of implicitly mentioned features. Such combinations are also expressly included within the scope of the specification and an embodiment.

Claims

1. A method for preparing lithium battery cathode materials using waste titanium dioxide, characterized in that, Includes the following steps: Step 1: Add concentrated sulfuric acid to the titanium dioxide waste acid solution to adjust the mass concentration of sulfuric acid in the titanium dioxide waste acid to 70%, stir thoroughly, then cool to below 80°C to crystallize and mature, add titanium dioxide waste acid to reduce the mass concentration of sulfuric acid to 55%, stir thoroughly, and perform solid-liquid separation to obtain concentrated sulfuric acid and ferrous slag. Add 5% (w / w) of alkylolamide to a 5-10% (w / w) ferrous salt solution and stir until evenly dispersed. Then add 10-15% (w / w) of a 25% (w / w) sodium phosphate solution, followed by injection of a solution with a concentration of... The ozone was then used to adjust the pH to 2.6 with sodium hydroxide, and then the reaction was carried out at 50-55℃ for 1-2 hours. After the reaction was completed, the mixture was washed with water, dried, and then calcined at 700℃ for 8-12 hours to obtain the primary iron phosphate. Step 2: Add the ferric phosphate precursor from Step 1 to a 5-10 times volume of the modification solution and stir to modify it. After stirring, wash with water and dry. Step 3: Preparation of Bentonite Reconditioning Agent: S01: Heat bentonite at 210-230℃ for 10-20 min, then raise the temperature to 300-350℃ at a rate of 2-5℃ / min, hold for 5-10 min, and then cool to 45-50℃ at a rate of 1-3℃ / min, hold for later use. S02: Add the SO1 product to a conditioning solution that is 2-5 times the total amount of the SO1 product and ultrasonically disperse for 10-20 minutes at an ultrasonic power of 450-500W. After ultrasonication, wash with water and dry. S03: Add 5-10% of the total amount of SO2 product as a complexing agent to the SO2 product, and continue stirring until fully mixed to obtain bentonite compounding agent; Step 4: Add 10-15% of the total amount of the product from Step 2, 10% of the total amount of the product from Step 2, and 5% of the composite carbon source (a 1:1 mixture of glucose and citric acid) to the product from Step 2. Then, put the mixture into a ball mill for ball milling modification. After ball milling, wash and dry the mixture, and then calcine it at 700℃ for 10 hours to obtain the lithium battery cathode material. The modified liquid is prepared by: S11: Add 10-15% of the total amount of hydrochloric acid solution to the hydrochloric acid solution, and then stir until homogeneous; S12: Soak viscose fibers in a 5% sodium hydroxide solution for 10-12 hours, then filter, wash with water until the washing solution is neutral, then place them in a 1-2 mol / L permanganate solution for 20 hours at a reaction temperature of 65-75℃, then filter, wash with water, and freeze dry to obtain cellulose nanospheres. S13: Add 1-3 parts sodium dodecyl sulfate to 5-10 parts deionized water, then add 2-5 parts cellulose nanospheres, stir thoroughly to obtain the additive; S14: Add the additive to the product of S11 and stir until homogeneous to obtain the modified liquid.

2. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 1, characterized in that, The hydrochloric acid solution has a mass fraction of 5-8%.

3. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 1, characterized in that, The chitosan aqueous solution has a mass fraction of 6-9%.

4. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 1, characterized in that, The stirring time for the stirring modification is 20-30 min, the stirring temperature is 40-45℃, and the stirring speed is 550-650 r / min.

5. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 1, characterized in that, The specific preparation steps of the conditioning liquid are as follows: Lanthanum sulfate solution and yttrium nitrate solution were mixed at a weight ratio of 3:1 and stirred for one stage. Then, 10-15% of the total lanthanum sulfate solution, 5% sodium alginate aqueous solution, and 1-5% silica sol were added and stirred for a second stage. After stirring, the conditioning solution was obtained.

6. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 5, characterized in that, The mass fractions of the lanthanum sulfate solution and the yttrium nitrate solution are 5-8% and 1-3%, respectively.

7. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 5, characterized in that, The primary stirring process involves a stirring speed of 450-550 r / min and a stirring time of 20-30 min; the secondary stirring process involves a stirring speed of 1050-1250 r / min and a stirring time of 5-10 min.

8. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 1, characterized in that, The method for preparing the ligand is as follows: S101: The lignin is added to 2-3 times the mass fraction of 5% sodium hydroxide solution for reaction treatment at a reaction temperature of 100-110℃ for 10-20 min to obtain lignin solution. S102: Fluorinated carbon is added to 3-5 times its volume of ethanol solvent, then 5-10% of the total amount of fluorinated carbon, silane coupling agent KH560, and 1-3% of lignin solution are added. The mixture is stirred evenly, then washed with water and dried to obtain the coordination agent.

9. The method for preparing lithium battery cathode material using waste titanium dioxide as described in claim 1, characterized in that, The ball milling modification treatment is performed at a speed of 1000-1500 r / min and a milling time of 35-45 min.

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