Method for preparing anhydrous ferric phosphate

Abstract

Provided is a method for preparing anhydrous ferric phosphate, comprising: adding an oxidant and phosphoric acid to a first solution containing ferrous salt to obtain a first mixture containing ferric salt, wherein the oxidant is at least one of air or oxygen, and the oxidant is added at a pressure of 0.6 to 1.2 MPa and an oxygen flow rate of 350 to 1350 ml / min per liter of a reaction system; adding monoammonium phosphate to the first mixture to obtain a second mixture containing a first precipitate; slurrying the first precipitate to obtain a slurry; acidizing the slurry by phosphoric acid; ageing the acidized slurry to obtain a second precipitate containing ferric phosphate dehydrate; and calcinating the second precipitate, to obtain the anhydrous ferric phosphate.

Description

[0001] P139984-LG

[0002] METHOD FOR PREPARING ANHYDROUS FERRIC PHOSPHATE

[0003] FIELD

[0004] The present disclosure relates to the technical field of a battery material, and more particularly to a method for preparing anhydrous ferric phosphate.

[0005] BACKGROUND

[0006] With the development of lithium-ion batteries, the demand for anhydrous ferric phosphate as a raw material for cathode active materials is increasing. Methods for preparing anhydrous ferric phosphate in the related arts involve using hydrogen peroxide as an oxidizing agent to oxidize iron or ferrous salts. However, these methods pose safety and environmental concerns, limiting the production capacity of anhydrous ferric phosphate. Additionally, using air as an oxidizing agent complicates the process and results in low oxidation efficiency.

[0007] Therefore, there is an urgent need for an efficient and eco-friendly method to prepare anhydrous ferric phosphate.

[0008] SUMMARY

[0009] Embodiments of the present disclosure seek to solve at least one of the problems existing in the related art to at least some extent.

[0010] In view of the above, the present disclosure provides in embodiments a method for preparing anhydrous ferric phosphate, including: adding an oxidant and phosphoric acid to a first solution containing ferrous salt, to obtain a first mixture containing ferric salt, wherein the oxidant is at least one of air or oxygen, and the oxidant is added at a pressure of 0.6 tol.2 MPa and an oxygen flow rate of 350 to 1350 ml / min per liter of a reaction system; adding monoammonium phosphate to the first mixture, to obtain a second mixture containing a first precipitate; slurrying the first precipitate, to obtain a slurry; acidizing the slurry by phosphoric acid; ageing the acidized slurry, to obtain a second precipitate containing ferric phosphate dihydrate; and calcinating the second precipitate, to obtain the anhydrous ferric phosphate.

[0011] According to the embodiments of the present disclosure, the method for preparing anhydrous ferric phosphate uses air as an oxidant instead of hydrogen peroxide and controls the oxidation conditions, reducing the safety and environmental constraints associated with the use of hazardous chemicals like hydrogen peroxide P139984-LG in the production of ferric phosphate. At the same time, it addresses the problems of low solubility of pure air in liquids, low oxidation efficiency, and reduced production capacity due to long reaction times.

[0012] In some embodiments of the present disclosure, the first solution contains ferrous ion at an amount of 5.5% to 6.5% based on a total mass of the first solution.

[0013] In some embodiments of the present disclosure, the ferrous salt is at least one of ferrous chloride or ferrous sulfate.

[0014] In some embodiments of the present disclosure, the first solution is prepared by: dissolving a by-product of titanium dioxide production by a sulfate process in water, to obtain a second solution; adjusting the second solution to a pH of 4 to 5 by an alkaline compound, to obtain a third solution; and diluting a supernatant of the third solution to obtain the first solution containing ferrous ion at an amount of 5.5% to 6.5% based on a total mass of the first solution, wherein the alkaline compound is at least one of ammonia or ammonium hydroxide.

[0015] According to the embodiments of the present disclosure, the method for preparing anhydrous ferric phosphate enables the preparation of anhydrous ferric phosphate starting from the by-product of titanium dioxide production by the sulfate process. The method can significantly reduce production costs while offering both economic and environmental benefits.

[0016] In some embodiments of the present disclosure, adding an oxidant and phosphoric acid to a first solution containing ferrous salt includes: acidizing the first solution to a pH of 1.8 to 2.20 by phosphoric acid; and oxidating the acidized first solution for 1 to 5 hours at a temperature of 30 to 60°C, a pressure of 0.6 to 1.2 MPa, an agitation speed of 100 to 500 rpm, and an oxygen flow rate of 350 to 1350 ml / min per liter of the acidized first solution.

[0017] According to the embodiments of the present disclosure, the efficiency of the oxidation reaction is improved by controlling the parameters of the oxidation reaction, such as the oxygen flow rate, the pH of the acidized first solution, the temperature, time, and pressure of the oxidation reaction.

[0018] In some embodiments of the present disclosure, adding monoammonium phosphate to the first mixture includes: adding monoammonium phosphate to the first mixture at a temperature of 35 to 60°C, to obtain the second mixture with a total molar ratio of iron to phosphorus of 1: (1-1.2).

[0019] In some embodiments of the present disclosure, before slurrying the first precipitate, the method further includes: alkalizing the second mixture to a pH of 2.0 to 2.2 by an alkaline compound, wherein the alkaline compound is at least one of ammonia or ammonium hydroxide.

[0020] In some embodiments of the present disclosure, slurrying the first precipitate includes: slurrying the first precipitate in water, to obtain the slurry with a solid content of 10% to 20%.

[0021] In some embodiments of the present disclosure, slurrying the first precipitate includes: washing the first P139984-LG precipitate until a conductivity of a washing solution is less than or equal to 1000 ps / cm; and slurrying the washed first precipitate by water, to obtain the slurry with a solid content of 10% to 20%.

[0022] In some embodiments of the present disclosure, acidizing the slurry by phosphoric acid includes: adding phosphoric acid to the slurry in an amount corresponding to 5% to 60% of a molar amount of iron contained in the slurry.

[0023] In some embodiments of the present disclosure, ageing the acidized slurry includes: ageing the acidized slurry at 70°C to 95°C for 2 to 6 hours.

[0024] In some embodiments of the present disclosure, before calcinating the second precipitate, the method further includes: washing the second precipitate until a conductivity of a washing solution is less than or equal to 500 ps / cm; and drying the second precipitate washed at a temperature of 90 to 120°C for 4 to 6 hours.

[0025] In some embodiments of the present disclosure, calcinating the second precipitate includes: calcinating the second precipitate at a temperature of 500 to 750°C for 3 to 6 hours.

[0026] It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory only and shall not be construed to limit the present disclosure.

[0027] DETAILED DESCRIPTION

[0028] Reference will now be made in detail to embodiments. The implementations set forth in the following description of the embodiments do not represent all implementations consistent with the present disclosure.

[0029] Terms used herein in embodiments of the present disclosure are only for the purpose of describing specific embodiments, but should not be construed to limit the present disclosure. As used in the embodiments of the present disclosure and the appended claims, “a / an”, and “the” in singular forms are intended to include plural forms, unless clearly indicated in the context otherwise. It should also be understood that, the term “and / or” used herein represents and contains any or all possible combinations of one or more associated listed items.

[0030] When term “about” is used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.

[0031] Term “range” disclosed in the present disclosure is defined in the form of a lower limit and an upper limit, a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The range defined in this way can be inclusive or exclusive, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is understood that ranges of 60- 110 and 80-120 are also obtained. In addition, if the listed minimum values are 1 and 2, and if the listed maximum values are 3, 4 and 5, the ranges of 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 may be obtained. In the present disclosure, P139984-LG unless otherwise specified, the numerical range “a-b” means the abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range “0-5” means that all the real numbers between “0-5” have been listed, and “0-5” is only the abbreviated representation of these numerical combinations. In addition, when a parameter is an integer >2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] Method for preparing anhydrous ferric phosphate

[0033] The embodiments of the present disclosure provide a method for preparing anhydrous ferric phosphate. Comparing methods in the related arts, method for preparing anhydrous ferric phosphate provided in embodiments of the present disclosure uses air as an oxidant instead of hydrogen peroxide and controls the oxidation conditions, reducing the safety and environmental constraints associated with the use of hazardous chemicals like hydrogen peroxide in the production of ferric phosphate. At the same time, it addresses the problems of low solubility of pure air in liquids, low oxidation efficiency, and reduced production capacity due to long reaction times.

[0034] In a first aspect, there is provided in embodiments a method includes the following steps of S200 to S700.

[0035] S200: adding an oxidant and phosphoric acid to a first solution containing ferrous salt, to obtain a first mixture containing ferric salt.

[0036] In the embodiments of the present disclosure, the oxidant is at least one of air or oxygen.

[0037] In the embodiments of the present disclosure, the oxidant is added at a pressure of 0.6 tol.2 MPa and an oxygen flow rate of 350 to 1350 ml / min per liter of a reaction system. For example, the oxidant is added at a pressure of 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, or 1.2 MPa and an oxygen flow rate of 350, 450, 550, 650, 750, 850, 950, 1050, 1150, 1250, or 1350 ml / min per liter of a reaction system.

[0038] It can be understood that when the oxidant is solely oxygen, the term 'oxygen flow rate' refers to a total gas flow rate. When the oxidant is a gas containing oxygen, the 'oxygen flow rate' refers to a flow rate of oxygen in the gas. It can also be understood that the 'pressure' refers to a pressure within the reactor.

[0039] In some embodiments of the present disclosure, the first solution contains ferrous ion at an amount of 5.5% to 6.5% based on a total mass of the first solution. For example, the first solution contains ferrous ion at an amount of 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, or 6.5% based on a total mass of the first solution

[0040] In some embodiments of the present disclosure, the ferrous salt is at least one of ferrous chloride or ferrous sulfate.

[0041] In the embodiments of the present disclosure, the step of S200 comprises S201 to S202,

[0042] S201: acidizing the first solution to a pH of 1.8 to 2.20 by phosphoric acid (for example, acidizing the first P139984-LG solution to a pH of 1.8 to 2.20 by phosphoric acid);

[0043] S202: oxidating the acidized first solution for 1 to 5 hours at a temperature of 30 to 60°C, a pressure of 0.6 to 1.2 MPa, an agitation speed of 100 to 500 rpm, and an oxygen flow rate of 350 to 1350 ml / min per liter of the acidized first solution (for example, oxidating the acidized first solution for 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours, at a temperature of 30°C, 40°C, 50°C, or 60°C, a pressure of 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, or 1.2 MPa, an agitation speed of 100 rpm, 200 rpm, 300 rpm, 400 rpm, or 500 rpm, and an oxygen flow rate of 350, 450, 550, 650, 750, 850, 950, 1050, 1150, 1250, or 1350 ml / min per liter of the acidized first solution).

[0044] S300: adding monoammonium phosphate to the first mixture, to obtain a second mixture containing a first precipitate.

[0045] In the embodiments of the present disclosure, the step of S300 comprises S301,

[0046] S301: adding monoammonium phosphate to the first mixture at a temperature of 35 to 60°C, to obtain a second mixture with a total molar ratio of iron to phosphorus of 1 :(1-1.2). For example, adding monoammonium phosphate to the first mixture at a temperature of 35 °C, 40°C, 45 °C, 50°C, 55 °C, or 60°C, to obtain a second mixture with a total molar ratio of iron to phosphorus of 1 :(1-1.2).

[0047] In the embodiments of the present disclosure, the step of S300 further comprises S302,

[0048] S302: alkalizing the second mixture to a pH of 2.0 to 2.2 by an alkaline compound.

[0049] In the embodiments of the present disclosure, the alkaline compound is at least one of ammonia or ammonium hydroxide.

[0050] S400: slurrying the first precipitate, to obtain a slurry.

[0051] In the embodiments of the present disclosure, the slurry is of a solid content of 10% to 20%. For example, the slurry is of a solid content of 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0052] In the embodiments of the present disclosure, the step of S400 comprises S401 to S402,

[0053] S401: washing the first precipitate until a conductivity of a washing solution is less than or equal to 1000 ps / cm;

[0054] S402: slurrying the washed first precipitate by water, to obtain the slurry with a solid content of 10% to 20%.

[0055] S500: acidizing the slurry by phosphoric acid.

[0056] In the embodiments of the present disclosure, the phosphoric acid is added to the slurry in an amount corresponding to 5% to 60% of a molar amount of iron contained in the slurry. For example, the phosphoric acid is added to the slurry in an amount corresponding to 5%, 10%, 20%, 30%, 40%, 50%, 60% of a molar amount of iron contained in the slurry. P139984-LG

[0057] S600: ageing the acidized slurry, to obtain a second precipitate containing ferric phosphate dehydrate.

[0058] In the embodiments of the present disclosure, the acidized slurry is aged at 70°C to 95°C for 2 to 6 hours to obtain a second precipitate containing ferric phosphate dehydrate. For example, the acidized slurry is aged at 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C for 2 hours, 3 hours, 4 hours, 5 hours, 6 hours to obtain the second precipitate containing ferric phosphate dehydrate.

[0059] In the embodiments of the present disclosure, the second precipitate is washed until a conductivity of a washing solution is less than or equal to 500 ps / cm.

[0060] In the embodiments of the present disclosure, the second precipitate washed is dried at a temperature of 90 to 120°C for 4 to 6 hours. For example, the second precipitate washed is dried at a temperature of 90°C, 100°C, 110°C, or 120°C for 4 hours, 5 hours, 6 hours.

[0061] S700: calcinating the second precipitate, to obtain the anhydrous ferric phosphate.

[0062] In the embodiments of the present disclosure, the second precipitate is calcinated at a temperature of 500 to 750°C for 3 to 6 hours. For example, the second precipitate is calcinated at a temperature of 500°C, 550°C, 600°C, 650°C, 700°C, or 750°C for 3 hours, 4 hours, 5 hours, or 6 hours.

[0063] In a second aspect, there is provided in embodiments a method includes the following steps of SI 00 to S700.

[0064] A step of SI 00 comprises S 101 to S 103,

[0065] S101: dissolving a by-product of titanium dioxide production by the sulfate process in water, to obtain a second solution;

[0066] SI 02: adjusting the second solution to a pH of 4 to 5 by an alkaline compound, to obtain a third solution;

[0067] SI 03: diluting a supernatant of the third solution to obtain the first solution containing ferrous ion at an amount of 5.5% to 6.5% based on a total mass of the first solution. For example, diluting a supernatant of the third solution to obtain the first solution containing ferrous ion at an amount of 5.5% 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, or 6.5% based on a total mass of the first solution.

[0068] It should be noted that "by-product of titanium dioxide production by the sulfate process" refers to the byproducts generated during the industrial production of titanium dioxide, primarily consisting of ferrous sulfate heptahydrate, with impurities including titanium, magnesium, manganese, etc. As an example, the by-product components used in some embodiments of the present disclosure are shown in Table 1 below, with data obtained using ICP testing.

[0069] Table 1 P139984-LG

[0070] In the embodiments of the present disclosure, the alkaline compound is at least one of ammonia or ammonium hydroxide.

[0071] For the description of S200 to S700, please refer to any of the embodiments provided in the first aspect above, which will not be elaborated further here.

[0072] Experimental Section

[0073] Raw material used in the examples

[0074] The raw material for preparing the first solution is a by-product of titanium dioxide production by the sulfate process, whose components is shown in the Table 1 above.

[0075] Method for preparing a cathode active material

[0076] The anhydrous ferric phosphate prepared from the inventive examples (IEs) and comparative examples (CEs) in the present disclosure was prepared as the cathode active material to test the electrochemical performance of each group of anhydrous iron phosphate.

[0077] The cathode active material was prepared by: dispersing 50.2 g of lithium carbonate, 200 g of anhydrous ferric phosphate, 19.2 g of glucose, 7.2 g of PEG 6000, and 1.0 g of titanium dioxide in 500 mL of water to obtain the first slurry, at a total molar ratio of Li:Fe = 1.02; grinding the first slurry at a speed of 1500 r / min, until the particle size D^TTOO nm; then calcinating the dried first slurry at 720 °C for 10 hours, after drying and crushing, and sieving through a 200-mesh sieve to obtain the cathode active material (a lithium iron phosphate / carbon composite material).

[0078] Method for preparing a battery

[0079] The cathode active material (the lithium iron phosphate / carbon composite material) was used to prepare a CR2016 button type battery.

[0080] The CR2016 button type battery was prepared by: grinding and mixing 1.6 g of the cathode active material with 0.2 g of acetylene black, dissolving 0.2 g of polyvinylidene fluoride (PVDF) in 4 ml of N-methyl-2-pyrrolidone (NMP), then slowly adding the mixture of the cathode active material and acetylene black to obtaining a second slurry, after stirring uniformly, coating the second slurry onto a 20 pm thick aluminum foil; drying the coated aluminum foil at 80°C for 12 hours to obtain an electrode plate, punching the electrode plate into small discs with a diameter of 12 mm (approximately containing 6 mg of active material) to serve as the positive electrode plate of the CR2016 button type battery; P139984-LG assembling the CR2016 button type battery using a lithium metal foil as the counter electrode, ND525 separator as the separator, and a solution consisting of LiPF(,. EC, and DMC (1 mol / L LiPF(,. the volum of EC and DMC=1:1) as the electrolyte, all within an argon-fdled glove box.

[0081] Test methods

[0082] Capacity Test

[0083] The first discharge specific capacity was tested according to a standard of formula D shown on page 13 of 20202915-T-610 (http: / / www.cnsmq.com / uploadfile / 2022 / 0510 / 20220510015338530.pdf).

[0084] The first discharge specific capacity was tested using the BTS-5 V / 5 mA battery testing system, with a voltage range of 3.65 to 2.5 V.

[0085] It should be noted that the present disclosure only describes some test method and conditions. Materials, measurements and processes that are known in the art are not described herein.

[0086] Examples

[0087] The following Examples are included to demonstrate certain aspects and embodiments of the present disclosure. It should be appreciated by those of skill in the art, however, that the following description is illustrative only and should not be taken in any way as a restriction of the present disclosure.

[0088] Inventive Example 1 (IE1)

[0089] The anhydrous iron phosphate for IE1 was prepared by:

[0090] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0091] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0092] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0093] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0094] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.6 MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0095] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0096] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0097] S401 : filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0098] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of P139984-LG

[0099] 15%;

[0100] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0101] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0102] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0103] The cathode active material and CR2016 button type battery for IE1 were prepared according to the corresponding method above.

[0104] Inventive Example 2 (IE2)

[0105] The anhydrous iron phosphate for IE2 was prepared by:

[0106] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0107] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0108] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0109] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0110] S202: oxidating the acidized first solution for 3 hours at a temperature of 35°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0111] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0112] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0113] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0114] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0115] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0116] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours P139984-LG to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0117] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0118] The cathode active material and CR2016 button type battery for IE2 were prepared according to the corresponding method above.

[0119] Inventive Example 3 (IE3)

[0120] The anhydrous iron phosphate for IE3 was prepared by:

[0121] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0122] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0123] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0124] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0125] S202: oxidating the acidized first solution for 3 hours at a temperature of 60°C, a pressure of 1.2MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0126] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0127] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0128] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 ps / cm;

[0129] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0130] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0131] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0132] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous P139984-LG iron phosphate.

[0133] The cathode active material and CR2016 button type battery for IE3 were prepared according to the corresponding method above.

[0134] Inventive Example 4 (IE4)

[0135] The anhydrous iron phosphate for IE4 was prepared by:

[0136] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0137] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0138] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0139] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0140] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 500 ml / min, obtaining a first mixture containing ferric salt;

[0141] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0142] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0143] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 ps / cm;

[0144] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0145] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0146] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0147] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0148] The cathode active material and CR2016 button type battery for IE4 were prepared according to the corresponding method above.

[0149] Inventive Example 5 (IE5) P139984-LG

[0150] The anhydrous iron phosphate for IE5 was prepared by:

[0151] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0152] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0153] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0154] S201 : acidizing 1000g of the first solution to a pH of 1.82 by adding 66.6g of phosphoric acid;

[0155] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0156] S301: adding and stirring 57.08g of monoammonium phosphate solved in 327.6g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0157] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0158] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 ps / cm;

[0159] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0160] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0161] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0162] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0163] The cathode active material and CR2016 button type battery for IE5 were prepared according to the corresponding method above.

[0164] Inventive Example 6 (IE6)

[0165] The anhydrous iron phosphate for IE6 was prepared by:

[0166] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0167] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution; P139984-LG

[0168] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0169] S201 : acidizing 1000g of the first solution to a pH of 2.20 by adding 56.9g of phosphoric acid;

[0170] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 2000 ml / min, obtaining a first mixture containing ferric salt;

[0171] S301: adding and stirring 66.76g of monoammonium phosphate solved in 383.1g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0172] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0173] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0174] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0175] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0176] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0177] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0178] The cathode active material and CR2016 button type battery for IE2 were prepared according to the corresponding method above.

[0179] Comparative Example 1 (CE1)

[0180] The anhydrous iron phosphate for CE1 was prepared by:

[0181] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0182] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0183] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0184] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0185] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.3MPa, an P139984-LG agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0186] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0187] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0188] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0189] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0190] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0191] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0192] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0193] The cathode active material and CR2016 button type battery for CE1 were prepared according to the corresponding method above.

[0194] Comparative Example 2 (CE2)

[0195] The anhydrous iron phosphate for CE2 was prepared by:

[0196] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0197] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0198] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0199] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0200] S202: oxidating the acidized first solution for 3 hours at a temperature of 80°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0201] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture; P139984-LG

[0202] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0203] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0204] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0205] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0206] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0207] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0208] The cathode active material and CR2016 button type battery for CE2 were prepared according to the corresponding method above.

[0209] Comparative Example 3 (CE3)

[0210] The anhydrous iron phosphate for CE3 was prepared by:

[0211] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0212] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0213] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0214] S201: acidizing 1000g of the first solution to a pH of 1.51 by adding 74.3g of phosphoric acid;

[0215] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 1000 ml / min, obtaining a first mixture containing ferric salt;

[0216] S301: adding and stirring 49.4g of monoammonium phosphate solved in 283.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0217] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0218] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0219] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of P139984-LG

[0220] 15%;

[0221] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0222] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0223] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0224] The cathode active material and CR2016 button type battery for CE3 were prepared according to the corresponding method above.

[0225] Comparative Example 4 (CE4)

[0226] The anhydrous iron phosphate for CE1 was prepared by:

[0227] S101: dissolving 700g of the by-product whose components is shown in Table 1 above in 1000g of deionized water, obtaining a second solution;

[0228] S102: adjusting the second solution to a pH of 4.5 by ammonium hydroxide, obtaining a third solution;

[0229] SI 03: diluting a supernatant of the third solution by 368g of deionized water, obtaining a first solution containing ferrous ion at an amount of 6.0% based on a total mass of the first solution;

[0230] S201: acidizing 1000g of the first solution to a pH of 1.96 by adding 61.8g of phosphoric acid;

[0231] S202: oxidating the acidized first solution for 3 hours at a temperature of 45°C, a pressure of 0.8MPa, an agitation speed of 300 rpm, and an oxygen flow rate of 450 ml / min, obtaining a first mixture containing ferric salt;

[0232] S301: adding and stirring 61.6g of monoammonium phosphate solved in 353.5g of water to the first mixture at an agitation speed of 200 rpm, and a temperature of 50°C, obtaining the second mixture;

[0233] S302: alkalizing the second mixture to a pH of 2.1 by ammonium hydroxide;

[0234] S401: filtrating the alkalized second mixture, obtaining a first precipitate, and washing the first precipitate until the conductivity of the washing solution is 800 p.s / cm;

[0235] S402: slurrying the washed first precipitate by deionized water, obtaining a slurry with a solid content of 15%;

[0236] S500: acidizing the slurry by 24.7g of phosphoric acid (about 20% of the molar amount of iron contained in the slurry);

[0237] S600: heating the acidized slurry to a temperature of 90 °C, and then keeping the temperature for 3 hours P139984-LG to age the acidized slurry, obtaining a second precipitate containing ferric phosphate dehydrate; washing the second precipitate until the conductivity of the washing solution is 350 ps / cm; drying the second precipitate washed at 105°C for 4 hours;

[0238] S700: calcinating the second precipitate after washing and drying at 550°C for 5h, obtaining the anhydrous iron phosphate.

[0239] The cathode active material and CR2016 button type battery for CE4 were prepared according to the corresponding method above.

[0240] Table 2

[0241] Table 3 By comparing the results of IE1- IE3 and CE1, it is apparent that when the pressure in S202 is between 0.6 P139984-LG and 1.2 Mpa, a higher yield of the anhydrous iron phosphate and a higher Capacity of the CR2016 button type battery are obtained.

[0242] By comparing the results of IE1-IE3 and CE2, it is apparent that when the temperature in S202 is between 35 and 60°C, a higher yield of the anhydrous iron phosphate and a higher Capacity of the CR2016 button type battery are obtained.

[0243] By comparing the results of IE1- IE3 and CE3, it is apparent that when the PH of the acidized first solution in S201 is between 1.80 and 2.20, a higher yield of the anhydrous iron phosphate and a higher Capacity of the CR2016 button type battery are obtained.

[0244] By comparing the results of IE1-IE3 and CE4, it is apparent that when the oxygen flow rate in S202 is between 350 and 1350 ml / min per liter of the acidized first solution, a higher yield of the anhydrous iron phosphate and a higher Capacity of the CR2016 button type battery are obtained.

[0245] Comparing methods in the related arts, method for preparing anhydrous ferric phosphate provided in embodiments of the present disclosure uses air as an oxidant instead of hydrogen peroxide and controls the oxidation conditions, reducing the safety and environmental constraints associated with the use of hazardous chemicals like hydrogen peroxide in the production of ferric phosphate. At the same time, it addresses the problems of low solubility of pure air in liquids, low oxidation efficiency, and reduced production capacity due to long reaction times. The efficiency of the oxidation reaction (S201-S202) is improved by controlling the parameters of the oxidation reaction, such as the oxygen flow rate, the pH of the acidized first solution, the temperature, time, and pressure of the oxidation reaction.

[0246] Reference throughout this specification to “an embodiment,” “some embodiments,” “one embodiment”, “another example,” “an example,” “a specific example,” or “some examples,” means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as “in some embodiments,” “in one embodiment”, “in an embodiment”, “in another example,” “in an example,” “in a specific example,” or “in some examples,” in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0247] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed here. This application is intended to cover any variations, uses, or adaptations of the disclosure following the general principles thereof and including such P139984-LG departures from the present disclosure as come within known or customary practice in the art. It is intended that the specification and examples be considered as illustrative only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

P139984-LGCLAIMS1. A method for preparing anhydrous ferric phosphate, comprising: adding an oxidant and phosphoric acid to a first solution containing ferrous salt, to obtain a first mixture containing ferric salt, wherein the oxidant is at least one of air or oxygen, and the oxidant is added at a pressure of 0.6 tol.2 MPa and an oxygen flow rate of 350 to 1350 ml / min per liter of a reaction system; adding monoammonium phosphate to the first mixture, to obtain a second mixture containing a first precipitate; slurrying the first precipitate, to obtain a slurry; acidizing the slurry by phosphoric acid; ageing the acidized slurry, to obtain a second precipitate containing ferric phosphate dehydrate; and calcinating the second precipitate, to obtain the anhydrous ferric phosphate.

2. The method for preparing anhydrous ferric phosphate according to claim 1, wherein the first solution contains ferrous ion at an amount of 5.5% to 6.5% based on a total mass of the first solution, optionally, the ferrous salt is at least one of ferrous chloride or ferrous sulfate.

3. The method for preparing anhydrous ferric phosphate according to claim 1, wherein the first solution is prepared by dissolving a by-product of titanium dioxide production by a sulfate process in water, to obtain a second solution; adjusting the second solution to a pH of 4 to 5 by an alkaline compound, to obtain a third solution; and diluting a supernatant of the third solution to obtain the first solution containing ferrous ion at an amount of 5.5% to 6.5% based on a total mass of the first solution, wherein the alkaline compound is at least one of ammonia or ammonium hydroxide.

4. The method for preparing anhydrous ferric phosphate according to claim 1, wherein adding an oxidant and phosphoric acid to a first solution containing ferrous salt comprises: acidizing the first solution to a pH of 1.8 to 2.20 by phosphoric acid; and oxidating the acidized first solution for 1 to 5 hours at a temperature of 30 to 60°C, a pressure of 0.6 tol.2 MPa, an agitation speed of 100 to 500 rpm, and an oxygen flow rate of 350 to 1350 ml / min per liter of the acidized first solution.

5. The method for preparing anhydrous ferric phosphate according to claim 1, wherein adding monoammonium phosphate to the first mixture comprises: adding monoammonium phosphate to the first mixture at a temperature of 35 to 60°C, to obtain the secondP139984-LG mixture with a total molar ratio of iron to phosphorus of 1 :(1-1.2).

6. The method for preparing anhydrous ferric phosphate according to claim 5, wherein, before slurrying the first precipitate, the method further comprises: alkalizing the second mixture to a pH of 2.0 to 2.2 by an alkaline compound; and wherein the alkaline compound is at least one of ammonia or ammonium hydroxide.

7. The method for preparing anhydrous ferric phosphate according to claim 1, wherein slurrying the first precipitate comprises: slurrying the first precipitate in water, to obtain the slurry with a solid content of 10% to 20%.

8. The method for preparing anhydrous ferric phosphate according to claim 1, wherein slurrying the first precipitate comprises: washing the first precipitate until a conductivity of a washing solution is less than or equal to 1000 ps / cm; and slurrying the washed first precipitate by water, to obtain the slurry with a solid content of 10% to 20%.

9. The method for preparing anhydrous ferric phosphate according to claim 1, wherein acidizing the slurry by phosphoric acid comprises: adding phosphoric acid to the slurry in an amount corresponding to 5% to 60% of a molar amount of iron contained in the slurry.

10. The method for preparing anhydrous ferric phosphate according to claim 1, wherein ageing the acidized slurry comprises: ageing the acidized slurry at 70°C to 95°C for 2 to 6 hours.

11. The method for preparing anhydrous ferric phosphate according to claim 1, wherein before calcinating the second precipitate, the method further comprises: washing the second precipitate until a conductivity of a washing solution is less than or equal to 500 ps / cm; and drying the second precipitate washed at a temperature of 90 to 120°C for 4 to 6 hours.

12. The method for preparing anhydrous ferric phosphate according to claim 1, wherein calcinating the second precipitate comprises: calcinating the second precipitate at a temperature of 500 to 750°C for 3 to 6 hours.

Images