CN116692815A - Method for preparing titanium doped lithium iron phosphate by taking synthetic rutile mother liquor as raw material - Google Patents

Abstract

The invention relates to the technical field of new energy material preparation, and discloses a method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as a raw material, adding reduced titanium to the synthetic rutile mother liquor and filtering to obtain the filtered mother liquor, adding sodium carbonate to adjust pH, and filtering acid After adjustment, the purified ferrous sulfate solution is marked as solution A; metatitanic acid is added to solution A to obtain solution B; solution B, phosphate solution and _H2O2 solution are added to the solvent at the same time for _hydrothermal React and filter to obtain a solid product; wash and dry the solid product to obtain titanium-doped iron phosphate; prepare titanium-doped iron phosphate with lithium carbonate and carbon source by sand milling, spraying, sintering, crushing, and sieving to demagnetize Heterolithium iron phosphate. Turn the synthetic rutile mother liquor from waste into treasure, and convert its iron source into ferric phosphate with high added value, which can realize ferro-titanium coupling and clean production of titanium dioxide; the process is simple, the cost of ferric phosphate doping is reduced and the doping is uniform Good sex.

Description

Method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material

technical field

The invention relates to the technical field of preparation of new energy materials, in particular to a method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as a raw material.

Background technique

In recent years, lithium iron phosphate batteries have been widely used in UPS, electric tools, electric vehicles, energy storage batteries and other fields due to their rich resources, good cycle stability, and high safety factor. However, the intrinsic conductivity of lithium iron phosphate Defects such as low efficiency and slow kinetics caused by the one-dimensional diffusion of lithium ions have seriously hindered its further development and application. At present, it is generally used in the industry for doping modification to improve the conductivity of the surface and between particles of lithium iron phosphate particles. .

However, most of the current titanium doping methods for lithium iron phosphate are doped during the synthesis of lithium iron phosphate, but the melting point of titanium dioxide is too high to be easily doped, and the presence of doped particles will affect the growth of primary particles of lithium iron phosphate , ultimately failed to effectively improve the electrochemical performance of lithium iron phosphate.

In view of this, the present invention is proposed.

Contents of the invention

Purpose of the invention The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for preparing titanium-doped lithium iron phosphate using synthetic rutile mother liquor as a raw material.

To achieve the above object, the present invention is implemented according to the following technical solutions:

The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material comprises the following steps:

S1, add reduced titanium to the synthetic rutile mother liquor, filter after the reaction to obtain the filtered mother liquor; add sodium carbonate to the filtered mother liquor to adjust the pH to 5.0-6.5, and after reaction and filtration, add phosphoric acid to adjust the pH to 1.8-2.0 to obtain the purified The ferrous sulfate solution; The phosphoric acid used is that the phosphoric acid solution of 85wt% adds with concentration;

S2, configuring the purified ferrous sulfate solution into a solution with a concentration of 60-90g/L in terms of iron, which is marked as solution A;

S3, adding metatitanic acid to solution A to obtain solution B;

S4, adding solution B, phosphate solution, and H ₂ O ₂ solution to the solvent at the same time for hydrothermal reaction, and filtering to obtain a solid product after the reaction is completed; the solvent is an organic alcohol;

S5, the solid product is washed and dried to obtain the titanium-doped iron phosphate precursor of titanium-doped lithium iron phosphate; the titanium-doped iron phosphate, lithium carbonate, and carbon source are removed by sand milling, spraying, sintering, crushing, and sieving The magnetic preparation obtains the titanium-doped lithium iron phosphate as the cathode material of the lithium-ion battery.

Preferably, in the step S1, the reduced titanium is added under the condition of 60-80°C; the molar ratio of the added amount of the reduced titanium to the H ⁺ in the synthetic rutile mother liquor is 1.2-1.5:1.

The synthetic rutile mother liquor in the present invention is titanium dioxide waste by-product, and its main component is ferrous sulfate, also contains a large amount of trace elements such as Al, Mn, Ca, Na, V, Cr.

Preferably, in the step S4, the concentration of the H ₂ O ₂ solution is 25-28 wt %; the molar ratio of the amount of H ₂ O ₂ used in the H ₂ O ₂ solution to the Fe element is 1.5-1.8:1.

Preferably, in the step S3, the amount of metatitanic acid added is calculated as Ti element, and Ti element/Fe element=2700-8000ppm.

Preferably, in the step S4, the amount of the solvent added is 3-6 wt% of the mass of the Fe element in the solution B; the organic alcohol is at least one of n-butanol, propylene alcohol and benzyl alcohol.

Preferably, in the step S4, the phosphate solution is at least one of sodium phosphate salt solution and ammonium phosphate solution; the pH of the phosphate solution is 6.5-7.5; the Fe element in solution B and the phosphate solution The molar ratio of P element in is 1.1-1.4:1.

Preferably, in the step S4, the hydrothermal temperature of the hydrothermal reaction is 150-200° C., and the hydrothermal time is 10-20 h.

Preferably, in the step S5, the molar ratio between the Fe element in the titanium-doped iron phosphate, the Li element in the lithium carbonate, and the C element in the carbon source is 1: (1.0-1.15): (0.25-0.45 ).

Preferably, in the step S5, the carbon source is at least one of glucose, sucrose and polyethylene glycol.

Preferably, in the step S5, the sintering process is: calcining at 700-850° C. for 9-12 hours under nitrogen atmosphere.

Beneficial effects of the present invention:

1. The present invention adopts the process of reducing titanium and sodium carbonate to purify the synthetic rutile mother liquor, which can further reduce the content of Mn in the synthetic rutile mother liquor, so that the Mn content in iron phosphate is less than 10ppm, and reduces the battery life when the rear end is prepared into a lithium iron phosphate battery. The risk of self-discharge improves the safety performance of the battery;

2. In the present invention, the hydrolyzed product of titanium liquid, metatitanic acid, is used as the titanium source. On the one hand, the transformation of metatitanic acid from amorphous to anatase can be realized in the hydrothermal process, and at the same time, the presence of organic alcohol solvent can control the ferric phosphate crystal nucleus The formation rate and growth rate make the formation and growth rate of iron phosphate nuclei uniform. At the same time, one end of the dispersant is adsorbed on the surface of iron phosphate crystals, and the hydroxyl group at the other end is connected with titanium ions in the form of covalent bonds to achieve titanium and iron phosphate Co-precipitation has the same uniform doping effect, so that titanium elements can be uniformly doped into the iron phosphate lattice, which can further improve the electrochemical performance of lithium iron phosphate.

3. At present, the conventional treatment process of synthetic rutile mother liquor is to add calcium carbide mud for neutralization, and generate a large amount of solid waste residue and waste liquid. The solid waste residue is generally treated by stacking, and the waste liquid is discharged outside, causing certain environmental pollution. The by-product ferrous sulfate crystals can be sold directly through takeout. This process turns the synthetic rutile mother liquor into treasure, and converts its iron source into ferric phosphate with high added value, which can realize the coupling of titanium and iron, and realize the clean production of titanium dioxide. High degree of resource utilization.

4. The process flow is simple, the cost of iron phosphate doping is reduced and the doping uniformity is good.

Description of drawings

Fig. 1 is the SEM morphology figure of the titanium-doped iron phosphate obtained in Example 1 of the present invention;

Fig. 2 is the EDS layered image of the titanium-doped ferric phosphate obtained in Example 1 of the present invention;

Fig. 3 is the EDS layered image of O element in the titanium-doped ferric phosphate obtained in Example 1 of the present invention;

Fig. 4 is the EDS layered image of P element in the titanium-doped ferric phosphate obtained in Example 1 of the present invention;

Fig. 5 is the EDS layered image of the Ti element in the titanium-doped ferric phosphate obtained in Example 1 of the present invention;

Fig. 6 is the EDS layered image of Fe element in titanium-doped ferric phosphate obtained in Example 1 of the present invention;

Fig. 7 is the EDS layered image of the titanium-doped ferric phosphate that comparative example 2 of the present invention obtains;

Fig. 8 is the EDS layered image of O element in the titanium-doped ferric phosphate that comparative example 2 of the present invention obtains;

Fig. 9 is the EDS layered image of P element in the titanium-doped ferric phosphate that comparative example 2 of the present invention obtains;

Fig. 10 is the EDS layered image of the Ti element in the titanium-doped ferric phosphate that comparative example 2 of the present invention obtains;

Fig. 11 is an EDS layered image of Fe element in titanium-doped iron phosphate obtained in Comparative Example 2 of the present invention.

Detailed ways

All raw materials in the present invention have no particular limitation on their sources, they can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

All the raw materials in the present invention have no special limitation on their purity, and the present invention preferably adopts industrial purity or conventional purity used in the field of lithium iron phosphate preparation.

The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material comprises the following steps:

1. Take titanium dioxide waste by-products to synthesize rutile mother liquor, add a certain amount of reduced titanium at 60-80°C to remove aluminum and chromium ions in the solution, react for 1-3 hours and filter to obtain filtered mother liquor; filtered mother liquor Add a certain amount of sodium carbonate to adjust the pH value to between 5.0-6.5, further reduce the manganese ion content in the solution, react at room temperature for 2-4h and then filter, after the reaction is filtered, add 85wt% phosphoric acid solution to adjust the pH to 1.8-2.0 Between, obtain the purified ferrous sulfate solution, wherein the addition of reduced titanium is, reduced titanium: H ⁺ =1.2-1.5: 1 (molar ratio);

2. Add water to the purified ferrous sulfate solution to form a solution with a concentration of 60-90g/L in terms of iron. At this time, the solution is marked as solution A;

3. Add a certain amount of metatitanic acid, a hydrolyzed product of titanium solution, to solution A under stirring, wherein the amount of metatitanic acid added is Ti element/Fe element=2700-8000ppm, and the solution is marked as solution B at this time;

4. Add solution B, phosphate solution, and H ₂ O ₂ solution with a concentration of 25-28wt% into a hydrothermal kettle with a certain solvent at the same time for hydrothermal reaction; wherein the phosphate solution is phosphoric acid with a pH of 6.5-7.5 One or two of sodium salt solution and ammonium phosphate solution, the solvent is one or more of n-butanol, propylene alcohol, and benzyl alcohol, and the Fe element is controlled: P element=1.1-1.4:1 (molar ratio) , between mixed solution pH=1.8-2.1 (the mixed solution here refers to solution B in the hydrothermal kettle, phosphate solution, H ₂ O ₂ solution, the mixed solution obtained after solvent mixing), the add-on of solvent is 3-6wt% of Fe element in solution B; hydrothermal temperature 150-200°C, hydrothermal time 10-20h; after the reaction is completed, filter to obtain a solid product; the amount of H ₂ O ₂ added: Fe element = 1.5-1.8: 1 (molar ratio);

5. Wash the above solid product until it is neutral, and dry it in a vacuum drying oven at 100-120°C for 6-9 hours to obtain the precursor of titanium-doped lithium iron phosphate, titanium-doped iron phosphate, the precursor and lithium carbonate, carbon The source is measured in proportion, and the lithium-ion battery positive electrode material titanium-doped lithium iron phosphate can be prepared by sand milling, spraying, sintering, crushing, and sieving to demagnetize, wherein titanium is doped with Fe in iron phosphate and Li in lithium carbonate. The molar ratio between elements and C elements in the carbon source is 1: (1.0-1.15): (0.25-0.45), and the carbon source is one, two or three mixtures of glucose, sucrose and polyethylene glycol , The sintering process is: calcining at 700-850°C for 9-12h under nitrogen atmosphere.

The present invention will be further described below with specific examples, and the schematic examples and illustrations of the present invention are used to explain the present invention, but not as a limitation to the present invention.

Example 1

The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material comprises the following steps:

1. Take titanium dioxide waste by-products to synthesize rutile mother liquor, add a certain amount of reduced titanium at 60°C to remove aluminum and chromium ions in the solution, react for 3 hours and filter to obtain the filtered mother liquor; add a certain amount of rutile to the filtered mother liquor Sodium carbonate, adjust the pH of the solution to 5.0, further reduce the manganese ion content in the solution, filter after reacting at normal temperature for 4h, after reacting and filtering, add 85wt% phosphoric acid to adjust the pH of the solution=1.8, obtain the ferrous sulfate solution after purification, The amount of reduced titanium added is: reduced titanium: H ⁺ = 1.2: 1 (molar ratio);

2. Add water to the purified ferrous sulfate solution to form a solution with a concentration of 60g/L in terms of iron, which is now marked as solution A;

3. Add a certain amount of metatitanic acid, the hydrolyzed product of titanium solution, to solution A under stirring, wherein the amount of metatitanic acid added is Ti element/Fe element = 2700ppm, and the solution is marked as solution B at this time;

4. Add solution B, phosphate solution, and _H2O2 solution with _a concentration of 25 wt% to a hydrothermal kettle with a certain solvent at the same time for hydrothermal reaction, wherein the phosphate solution is a sodium phosphate solution with pH=6.5, Solvent is n-butanol, control Fe element: P element=1.1:1 (molar ratio), mixed solution pH=1.8 (the mixed solution here refers to solution B, phosphate solution, H ₂ O ₂ solution, the mixed solution obtained after the mixing of the solvent), the addition of the solvent is 3wt% of the Fe element in the solution B, and the H ₂ O ₂ addition: Fe element=1.5:1 (molar ratio), hydrothermal temperature 150 ℃ , hydrothermal time 20h; After the reaction is completed, filter to obtain a solid product;

5. Wash the above solid product until it is neutral, and dry it in a vacuum oven at 100°C for 9 hours to obtain the titanium-doped iron phosphate precursor, which is proportional to lithium carbonate and carbon source. , through sand milling, spraying, sintering, crushing, sieving and demagnetization, the lithium-ion battery positive electrode material titanium-doped lithium iron phosphate can be prepared, wherein titanium-doped iron phosphate Fe element, Li element in lithium carbonate, carbon source The molar ratio of the C elements in the mixture is 1:1.0:0.45, the carbon source is a mixture of sucrose and polyethylene glycol, and the sintering process is as follows: calcination at 700°C for 12h under a nitrogen atmosphere.

Example 2

The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material comprises the following steps:

1. Take titanium dioxide waste by-products to synthesize rutile mother liquor, add a certain amount of reduced titanium at 80°C to remove aluminum and chromium ions in the solution, react for 1 hour and filter to obtain the filtered mother liquor; add a certain amount of rutile to the filtered mother liquor Sodium carbonate, adjust the pH of the solution to 6.5, further reduce the manganese ion content in the solution, filter after reacting at normal temperature for 2h, after reacting and filtering, add 85% phosphoric acid to adjust the pH of the solution=2.0, obtain the ferrous sulfate solution after purification, The amount of reduced titanium added is reduced titanium: H ⁺ = 1.5: 1 (molar ratio);

2. Add water to the purified ferrous sulfate solution to form a solution with a concentration of 90g/L in terms of iron, and this solution is marked as solution A;

3. Add a certain amount of metatitanic acid, the hydrolyzed product of titanium solution, to solution A under stirring, wherein the amount of metatitanic acid added is Ti element/Fe element = 8000ppm, and the solution is marked as solution B at this time;

4. Add solution B, phosphate solution, and _H2O2 solution with _a concentration of 28wt% to a hydrothermal kettle with a certain solvent at the same time for hydrothermal reaction, wherein the phosphate solution is an ammonium phosphate solution with pH=7.5, Solvent is two kinds of mixtures in allyl alcohol, benzyl alcohol (wherein the mass ratio of allyl alcohol and benzyl alcohol is 1: 1), control Fe element: P element=1.4:1 (molar ratio), mixed solution pH=2.1 (here The mixed solution refers to the solution B in the hydrothermal kettle, the phosphate solution, the H ₂ O ₂ solution, the mixed solution obtained after the solvent is mixed), the addition of the solvent is 6wt% of the Fe element in the solution B, and the H ₂ O _Addition amount: Fe element=1.8:1 (molar ratio), hydrothermal temperature 200 ℃, hydrothermal time 10h; After the reaction is completed, filter to obtain a solid product;

5. Wash the above solid product until neutral, and dry it in a vacuum drying oven at 120°C for 6 hours to obtain the precursor of titanium-doped lithium iron phosphate. Titanium-doped iron phosphate is measured in proportion to lithium carbonate and carbon source , through sand milling, spraying, sintering, crushing, sieving and demagnetization processes, the lithium-ion battery cathode material titanium-doped lithium iron phosphate can be prepared, wherein titanium is doped with Fe element in iron phosphate, Li element in lithium carbonate, carbon The molar ratio between the C elements in the source is 1:1.15:0.45, the carbon source is glucose, and the sintering process is: calcining at 850°C for 9h under nitrogen atmosphere.

Example 3

The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material comprises the following steps:

1. Take titanium dioxide waste by-products to synthesize rutile mother liquor, add a certain amount of reduced titanium at 70°C to remove aluminum and chromium ions in the solution, react for 2 hours and filter to obtain the filtered mother liquor; add a certain amount of rutile to the filtered mother liquor Sodium carbonate, adjust the pH 6.0 of solution, further reduce the manganese ion content in the solution, filter after reaction 3h at normal temperature, after reaction filter, add 85% phosphoric acid and adjust solution pH=1.9, promptly obtain the ferrous sulfate solution after the purification, wherein The added amount of reduced titanium is reduced titanium: H ⁺ = 1.35: 1 (molar ratio);

2. Add water to the purified ferrous sulfate solution to form a solution with a concentration of 75g/L in terms of iron. At this time, the solution is marked as solution A;

3. Add a certain amount of metatitanic acid, a hydrolyzed product of titanium solution, to solution A under stirring, wherein the amount of metatitanic acid added is T element/Fe element=5600ppm, and the solution is marked as solution B at this time;

4. Add solution B, phosphate solution, and _H2O2 solution with a concentration of 26wt% to a hydrothermal kettle with _a certain solvent at the same time for hydrothermal reaction, wherein the phosphate solution is sodium phosphate and phosphoric acid with pH=7.0 The mixture of ammonium salt solution, the solvent is three kinds of mixtures in n-butanol, allyl alcohol and benzyl alcohol (wherein the mass ratio of n-butanol, allyl alcohol and benzyl alcohol is 1:2:1), control Fe element: P element =1.3:1 (molar ratio), mixed solution pH=1.95 (the mixed solution here refers to solution B in the hydrothermal kettle, phosphate solution, H _{2 O} solution, the mixed solution obtained after the solvent is mixed), solvent The addition amount is 4wt% of the Fe element in solution B, and the _H2O2 addition amount: Fe element=1.65:1 (molar ratio), hydrothermal temperature 180 ℃, hydrothermal time 15h; After the reaction _is completed, filter to obtain solid product;

5. Wash the above solid product until it is neutral, and dry it in a vacuum drying oven at 110°C for 8 hours to obtain the titanium-doped iron phosphate precursor, which is proportional to lithium carbonate and carbon source , through sand milling, spraying, sintering, crushing, sieving and demagnetization, the lithium-ion battery positive electrode material titanium-doped lithium iron phosphate can be prepared, wherein titanium-doped iron phosphate Fe element, Li element in lithium carbonate, carbon source The molar ratio of the C elements in the mixture is 1:1.05:0.3, the carbon source is three mixtures of glucose, sucrose and polyethylene glycol, and the sintering process is as follows: calcining at 750°C for 10h under a nitrogen atmosphere.

Comparative example 1

Take iron phosphate, titanium dioxide, lithium carbonate, and carbon source to measure in proportion, and prepare titanium-doped lithium iron phosphate, the anode material of lithium ion battery, through sand milling, spraying, sintering, crushing, and sieving demagnetization, wherein the Fe element in iron phosphate , Li element in lithium carbonate, the molar ratio of the C element in the carbon source is 1:1.15:0.45, and the carbon source is glucose, and the addition amount of titanium dioxide is calculated with titanium, makes Ti element/Fe element=2000ppm, and the sintering process is: Calcined at 700°C for 12h under nitrogen atmosphere.

Comparative example 2

1. Take titanium dioxide waste by-products to synthesize rutile mother liquor, add a certain amount of reduced titanium at 70°C to remove aluminum and chromium ions in the solution, react for 2 hours and filter to obtain the filtered mother liquor, add a certain amount of rutile to the filtered mother liquor Sodium carbonate, adjust the pH of the solution to 6.0, further reduce the manganese ion content in the solution, filter after reacting at normal temperature for 3h, after reacting and filtering, add 85% phosphoric acid to adjust the pH of the solution=1.8, obtain the ferrous sulfate solution after purification, The amount of reduced titanium added is reduced titanium: H ⁺ = 1.35: 1 (molar ratio);

2. Add water to the purified ferrous sulfate solution to form a solution with a concentration of 75g/L in terms of iron. At this time, the solution is marked as solution A;

3. Add a certain amount of metatitanic acid, the hydrolyzed product of titanium solution, to solution A under stirring, wherein the amount of metatitanic acid added is Ti element/Fe element = 5600ppm, and the solution is marked as solution B at this time;

4. Add solution B, phosphate solution, and _H2O2 solution with a concentration of 26wt% to a hydrothermal kettle with _a certain solvent at the same time for hydrothermal reaction, wherein the phosphate solution is sodium phosphate and phosphoric acid with pH=7.0 The mixture of ammonium salt solution, control Fe element: P element = 1.3:1 (molar ratio), mixed solution pH = 1.95 (the mixed solution here refers to solution B, phosphate solution, H ₂ O ₂ solution, the mixed solution obtained after mixing the solvent), the addition of the solvent is 4wt% of the Fe element in the solution B, and the H ₂ O ₂ addition: Fe element=1.65:1 (molar ratio), hydrothermal temperature 180 ℃ , hydrothermal time 15h; After the reaction is completed, filter to obtain a solid product;

5. Wash the above solid product until it is neutral, and dry it in a vacuum drying oven at 110°C for 8 hours to obtain the titanium-doped iron phosphate precursor, which is proportional to lithium carbonate and carbon source , through sand milling, spraying, sintering, crushing, sieving and demagnetization, the lithium-ion battery positive electrode material titanium-doped lithium iron phosphate can be prepared, wherein titanium-doped iron phosphate Fe element, Li element in lithium carbonate, carbon source The molar ratio of the C elements in the mixture is 1:1.05:0.3, the carbon source is three mixtures of glucose, sucrose and polyethylene glycol, and the sintering process is as follows: calcining at 750°C for 10h under a nitrogen atmosphere.

As shown in Figure 1, it is the SEM topography figure of the titanium-doped iron phosphate obtained in Example 1 of the present invention; it can be known from the figure that the titanium-doped iron phosphate obtained in Example 1 has a primary particle size of 50-100nm Coral porous secondary aggregates composed of spherical particles.

As shown in Fig. 2 to Fig. 6, it is the energy spectrum analysis diagram (EDS) of the titanium-doped ferric phosphate obtained in Example 1 of the present invention; It can be known from the figure that: the bright spot of titanium element is evenly dispersed in the whole scanning surface, The uniform distribution of titanium element on the surface of lithium iron phosphate is realized.

As shown in Fig. 7 to Fig. 11, it is the energy spectrum analysis diagram (EDS) of the titanium-doped iron phosphate obtained in comparative example 2 of the present invention; Can know from the figure: the titanium-doped lithium iron phosphate surface obtained in comparative example 2 The titanium element is unevenly distributed on the lithium iron phosphate.

test:

The titanium-doped lithium iron phosphate obtained in Examples 1 to 3 of the present invention and the titanium-doped lithium iron phosphate obtained in Comparative Example 1 were electrochemically tested, and the test results are shown in Table 1.

Table 1

It can be seen from Table 1 that the titanium-doped lithium iron phosphate prepared by the method of the present invention has a relatively high compaction density and excellent electrochemical performance.

The titanium-doped iron phosphate prepared in Examples 1 to 3 of the present invention and the iron phosphate used in Comparative Example 1 were tested for trace elements, and the test results are shown in Table 2.

Table 2

As can be known from Table 2: the content of Mn element, Al element, V element, and Cr element in the titanium-doped iron phosphate prepared by the process method of the present invention is all less than the iron phosphate in Comparative Example 1, illustrating that the method of the present invention The method can effectively remove trace elements, especially the Mn element, in the ferrous sulfate solution prepared from the synthetic rutile mother liquor.

The technical solution of the present invention is not limited to the limitations of the above-mentioned specific embodiments, and any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims (10)

1. take synthetic rutile mother liquor as the method for raw material preparation titanium-doped lithium iron phosphate, it is characterized in that: comprise the following steps: S1, add reduced titanium to the synthetic rutile mother liquor, filter after the reaction to obtain the filtered mother liquor; add sodium carbonate to the filtered mother liquor to adjust the pH to 5.0-6.5, and after reaction and filtration, add phosphoric acid to adjust the pH to 1.8-2.0 to obtain the purified ferrous sulfate solution; S2, configuring the purified ferrous sulfate solution into a solution with a concentration of 60-90g/L in terms of iron, which is marked as solution A; S3, adding metatitanic acid to solution A to obtain solution B; S4, adding solution B, phosphate solution, and H ₂ O ₂ solution to the solvent at the same time for hydrothermal reaction, and filtering to obtain a solid product after the reaction is completed; the solvent is an organic alcohol; S5, the solid product is washed and dried to obtain the titanium-doped iron phosphate precursor of titanium-doped lithium iron phosphate; the titanium-doped iron phosphate, lithium carbonate, and carbon source are removed by sand milling, spraying, sintering, crushing, and sieving The magnetic preparation obtains the titanium-doped lithium iron phosphate as the cathode material of the lithium-ion battery. 2. The method for preparing titanium-doped lithium iron phosphate with synthetic rutile mother liquor according to claim 1, characterized in that: in the step S1, reduced titanium is added under the condition of 60-80°C; The molar ratio of the added amount to the H ⁺ in the synthetic rutile mother liquor is 1.2-1.5:1. 3. the method for preparing titanium-doped lithium iron phosphate with synthetic rutile mother liquor as raw material according to claim 1, characterized in that: in the step S4, the concentration of _{the H2O2} solution is 25-28wt%; The molar ratio of the amount of H ₂ O ₂ used in the H ₂ O ₂ solution to the Fe element is 1.5-1.8:1. 4. the method for preparing titanium-doped lithium iron phosphate as raw material with synthetic rutile mother liquor according to claim 1, is characterized in that: in described step S3, the addition amount of metatitanic acid is calculated by Ti element, Ti element/Fe Elements = 2700-8000 ppm. 5. the method for preparing titanium-doped lithium iron phosphate with synthetic rutile mother liquor as raw material according to claim 1, is characterized in that: in described step S4, the add-on of solvent is the 3-6wt of Fe element quality in solution B %; the organic alcohol is at least one of n-butanol, propenyl alcohol and benzyl alcohol. 6. the method for preparing titanium-doped lithium iron phosphate with synthetic rutile mother liquor as raw material according to claim 1, is characterized in that: in described step S4, described phosphate solution is sodium phosphate salt solution, ammonium phosphate salt solution at least one of them; the pH of the phosphate solution is 6.5-7.5; the molar ratio of the Fe element in solution B to the P element in the phosphate solution is 1.1-1.4:1. 7. The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material according to claim 1, characterized in that: in the step S4, the hydrothermal temperature of the hydrothermal reaction is 150-200°C, and the hydrothermal Time 10-20h. 8. the method for preparing titanium-doped lithium iron phosphate according to claim 1 as raw material with synthetic rutile mother liquor, is characterized in that: in described step S5, the Fe element in titanium-doped iron phosphate, Li in lithium carbonate The molar ratio between the element and the C element in the carbon source is 1: (1.0-1.15): (0.25-0.45). 9. the method for preparing titanium-doped lithium iron phosphate with synthetic rutile mother liquor according to claim 1 is characterized in that: in the step S5, the carbon source is glucose, sucrose, polyethylene glycol at least one. 10. The method for preparing titanium-doped lithium iron phosphate by using synthetic rutile mother liquor as raw material according to claim 1, characterized in that: in the step S5, the sintering process is: calcining at 700-850°C for 9 -12h.