Flaky manganese-iron-titanium-zinc phosphate positive electrode material precursor and preparation method thereof

Abstract

The invention discloses a flaky manganese-iron-titanium-zinc phosphate positive electrode material precursor and a preparation method thereof. The preparation method comprises the following steps: carrying out precipitation reaction on a mixed salt solution and a precipitator in a reaction kettle under certain conditions; and aging the precipitate, pulping, centrifugally washing, drying, crushing, pre-sintering to remove ammonium, mixing, screening and the like. According to the flaky manganese iron titanium zinc phosphate positive electrode material precursor prepared by the method, the production consistency and the electrochemical performance of the lithium ion battery positive electrode material manganese iron titanium zinc phosphate are improved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a sheet-like manganese iron titanium zinc phosphate positive electrode material precursor and a preparation method thereof. Background Art

[0002] Lithium-ion batteries have been widely used in large power batteries such as portable electronic products and hybrid power due to their high capacity, long service life, and environmental protection. In lithium-ion batteries, the positive electrode material is one of the key factors that determine the performance of lithium-ion batteries. Moreover, the positive electrode materials currently available on the market are difficult to meet the needs of power batteries for high cycle performance and high safety performance. Therefore, the research on positive electrode materials for lithium-ion batteries is crucial. Lithium-ion battery manganese iron titanium zinc phosphate material has many advantages over ternary positive electrode materials, and also makes up for the defects of lithium iron phosphate. Therefore, manganese iron titanium zinc phosphate is considered to be the most promising positive electrode material for lithium-ion batteries. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a sheet-shaped manganese iron titanium zinc phosphate positive electrode material precursor and a preparation method thereof. Compared with the iron phosphate positive electrode material precursor, it has a larger specific surface area, a more stable structure, and higher capacity, rate and cycle performance.

[0004] The present invention provides a sheet-like manganese iron titanium zinc phosphate positive electrode material precursor, wherein the positive electrode material precursor is a sheet-like structure, and is composed of Mn with a particle size of 10-15 μm. x Fe y Ti z Zn n HPO4 flake crystals are connected to each other, among which 0 <x<0.5, 0<y<0.5, 0.01<z<0.05, 0.01<n<0.05,x+y+z+n=1。

[0005] The present invention also provides a method for preparing the above-mentioned sheet-like manganese iron titanium zinc phosphate positive electrode material precursor, comprising the following steps: Step 1: prepare a mixed salt solution of manganese salt, ferrous salt, titanium salt and zinc salt in a certain proportion; dissolve phosphate salt in pure water at 20-60°C to prepare a solution; Step 2: Add the phosphate solution into the reactor to prepare the base liquid, adjust the pH value of the base liquid to between 4.5-7.0 with ammonia water, and heat it to 40-70℃; inject the mixed salt solution and ammonia water into the reactor at the same time to react with the base liquid to generate flake NH4Mn x Fe y Ti z Zn n PO4·H2O particles, the slurry is kept in reaction conditions and aged for 8-24 hours; Step 3: The product of step 2 is pumped into a centrifuge for dehydration through a diaphragm pump. After dehydration, it is put into a pulping tank equipped with a phosphoric acid solution for pulping. Then the pulp is pumped into a centrifuge and washed with pure water at 20-90°C to wash away the ammonium salt attached to the surface of the particles and between the gaps of the particles to obtain NH4Mn containing a certain amount of free water. x Fe y Ti z Zn n PO4·H2O block crystals; Step 4: NH4Mn obtained in step 3 x Fe y Ti z Zn n PO4·H2O crystals are dried at 100-200℃ to obtain NH4Mn free of free water. x Fe y Ti z Zn n PO4·H2O block crystals; then use a high-speed mixer to grind the material into powder; Step 5: NH4Mn obtained in step 4 x Fe y Ti z Zn n PO4·H2O powder is put into a sagger and pre-sintered at 280-800℃ under the protection of inert gas to obtain anhydrous deammonium Mn x Fe y Ti z Zn n HPO4 powder.

[0006] Furthermore, in step one, the manganese salt is at least one of manganese chloride, manganese bromide, manganese sulfate or manganese oxalate; the ferrous salt is at least one of ferrous chloride, ferrous bromide, ferrous sulfate or ferrous oxalate; the titanium salt is titanyl sulfate or titanium sulfate, and the zinc salt is zinc chloride, zinc sulfate or zinc oxalate.

[0007] Furthermore, in the step 2, the base liquid is prepared with monoammonium phosphate and ammonia water, and no monoammonium phosphate solution is added during the reaction.

[0008] The present invention provides a lithium ion battery, comprising a positive electrode material, wherein the positive electrode material is prepared by using the above-mentioned sheet-like manganese iron phosphate titanium zinc positive electrode material precursor.

[0009] The present invention also provides the use of the above-mentioned sheet-like manganese iron titanium zinc phosphate positive electrode material precursor in a lithium ion battery.

[0010] The present invention has the following beneficial effects: Relevant test characterizations show that the manganese iron titanium zinc phosphate positive electrode material precursor prepared by this method has a larger specific surface area and a looser microstructure, so that the positive electrode material prepared therefrom provides a wider diffusion channel during the extraction and embedding process of lithium ions, thereby improving the rate performance of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a SEM image of the manganese iron titanium zinc phosphate precursor taken using a scanning electron microscope. DETAILED DESCRIPTION

[0012] The present invention is described in detail below with reference to the embodiments. Example 1

[0013] The specific preparation process of the manganese iron titanium zinc phosphate precursor of this embodiment is as follows: Step 1: Mix manganese sulfate, ferrous sulfate, titanyl sulfate and zinc sulfate in a ratio of 6:3.7:0.2:0.1, dissolve in water and prepare a 2 mol / L mixed salt solution.

[0014] Step 2: Add 200kg-500kg of monoammonium phosphate into the reactor, add water and stir until it is completely dissolved, and add ammonia solution to adjust the pH to 4.5-7.0.

[0015] Step 3: Use a metering pump to pump 500-1300L of the mixed salt solution in step 1 and 200-1000L of ammonia solution into the reactor in 0.5-3 hours, control the temperature between 40-70°C, and then age the slurry generated by the reaction for 8-24 hours while keeping the temperature and liquid phase environment unchanged.

[0016] Step 4: After the aged slurry in step 3 is removed from the mother liquor by a filter press, it is put into a pulping tank with 3-5m³ of 0.01-0.5mol / L phosphoric acid solution to pulp the material. After pulping for half an hour, the slurry is put into a centrifuge for water washing. The water washing temperature is 20-90°C and the water consumption is about 3000-5000L. After washing, the material is dried.

[0017] Step 5: Spread the solid material in step 4 to an oven at 110-190° C. and dry for 10-30 hours, and then put the dry material into a high-speed mixer for light crushing at a speed of 150-500 rpm for 15-30 minutes.

[0018] Step 6: Put the powder material in step 5 into a sagger, push it into a push plate kiln, set the temperature to 280-800°C for pre-burning, and obtain the finished product of manganese iron titanium zinc phosphate.

[0019] The structure and performance of the manganese iron titanium zinc phosphate precursor of this embodiment are characterized as follows: Figure 1 This is a SEM image of the manganese iron titanium zinc phosphate precursor taken with a scanning electron microscope. It can be seen that the particles are thin and uniform and have a large layered structure.

[0020] The prepared manganese iron titanium zinc phosphate precursor was prepared into a 604062 type soft pack battery, which was conventionally formed with a formation voltage of 3.0-4.3V and a formation rate of 0.2C. The formation results are shown in Table 1. The rate performance test of the formed battery was performed, and the results are shown in Table 1; the cycle performance test of the formed battery was performed; the battery was charged and discharged at a rate of 1C at a constant temperature of 45°C, and the process step was set to cycle 100 weeks to record the capacity retention rate, and the results are shown in Table 1. Comparative Example 1

[0021] Compared with the embodiment, comparative example 1 is a ferromanganese phosphate precursor material; Step 1: Evenly mix manganese sulfate and ferrous sulfate in a ratio of 6:4, dissolve in water, and prepare a 2 mol / L mixed salt solution.

[0022] Step 2: Add 200kg-500kg of monoammonium phosphate into the reactor, add water and stir until it is completely dissolved, and add ammonia solution to adjust the pH to 4.5-7.0.

[0023] Step 3: Use a metering pump to pump 500-1300L of the mixed salt solution in step 1 and 200-1000L of ammonia solution into the reactor in 0.5-3 hours, control the temperature between 40-70°C, and then age the slurry generated by the reaction for 8-24 hours while keeping the temperature and liquid phase environment unchanged.

[0024] Step 4: After the aged slurry in step 3 is removed from the mother liquor by a filter press, it is put into a pulping tank with 3-5m³ of 0.01-0.5mol / L phosphoric acid solution to pulp the material. After pulping for half an hour, the slurry is put into a centrifuge for water washing. The water washing temperature is 20-90°C and the water consumption is about 3000-5000L. After washing, the material is dried.

[0025] Step 5: Spread the solid material in step 4 to an oven at 110-190° C. and dry for 10-30 hours, and then put the dry material into a high-speed mixer for light crushing at a speed of 150-500 rpm for 15-30 minutes.

[0026] Step 6: The powder material in step 5 is loaded into a sagger, pushed into a push plate kiln, and pre-fired at a temperature of 280-800° C. to obtain a sample of comparative example 1.

[0027] The prepared ferromanganese phosphate precursor was prepared into a 604062 type soft pack battery, which was conventionally formed with a formation voltage of 3.0-4.3V and a formation rate of 0.2C. The formation results are shown in Table 1. The rate performance test of the formed battery was performed, and the results are shown in Table 1; the cycle performance test of the formed battery was performed; the battery was charged and discharged at a rate of 1C at a constant temperature of 45°C, and the process step was set to cycle 100 weeks to record the capacity retention rate, and the results are shown in Table 1. Comparative Example 2

[0028] Compared with the embodiment, comparative example 2 is an iron phosphate precursor material; Step 1: Dissolve ferrous sulfate in water to prepare a 2 mol / L mixed salt solution.

[0029] Step 2: Add 200kg-500kg of monoammonium phosphate into the reactor, add water and stir until it is completely dissolved, and add ammonia solution to adjust the pH to 4.5-7.0.

[0030] Step 3: Use a metering pump to pump 500-1300L of the mixed salt solution in step 1 and 200-1000L of ammonia solution into the reactor in 0.5-3 hours, control the temperature between 40-70°C, and then age the slurry generated by the reaction for 8-24 hours while keeping the temperature and liquid phase environment unchanged.

[0031] Step 4: After the aged slurry in step 3 is removed from the mother liquor by a filter press, it is put into a pulping tank with 3-5m³ of 0.01-0.5mol / L phosphoric acid solution to pulp the material. After pulping for half an hour, the slurry is put into a centrifuge for water washing. The water washing temperature is 20-90°C and the water consumption is about 3000-5000L. After washing, the material is dried.

[0032] Step 5: Spread the solid material in step 4 to an oven at 110-190° C. and dry for 10-30 hours, and then put the dry material into a high-speed mixer for light crushing at a speed of 150-500 rpm for 15-30 minutes.

[0033] Step 6: The powder material in step 5 is loaded into a sagger, pushed into a push plate kiln, and pre-fired at a temperature of 280-800° C. to obtain a comparative example 2 sample.

[0034] The prepared iron phosphate precursor was prepared into a 604062 type soft pack battery, which was conventionally formed with a formation voltage of 3.0-4.3V and a formation rate of 0.2C. The formation results are shown in Table 1. The rate performance test of the formed battery was performed, and the results are shown in Table 1; the cycle performance of the formed battery was tested; the battery was charged and discharged at a rate of 1C at a constant temperature of 45°C, and the process step was set to cycle 100 weeks to record the capacity retention rate, and the results are shown in Table 1.

[0035] Table 1

[0036] The 0.2C discharge gram capacity in Table 1 indicates that the manganese iron titanium zinc phosphate precursor prepared in Example 1 has a higher initial discharge gram capacity than that of Comparative Example 1 and Comparative Example 2; at the same time, in Table 1, its rate performance indicates that the example has better rate performance than the two comparative examples; the cycle capacity retention rate of the lithium ion battery assembled with the positive electrode materials prepared in the example and the comparative example shows that the material prepared in the example has better cycle performance.

Claims

1. A sheet-like manganese iron titanium zinc phosphate positive electrode material precursor, characterized in that: The positive electrode material precursor is a sheet structure, composed of Mn with a particle size of 10-15 μm. x Fe y Ti z Zn n HPO4 flake crystals are connected to each other, among which 0 <x<0.5, 0<y<0.5, 0.01<z<0.05, 0.01<n<0.05,x+y+z+n=1。 2. The method for preparing a sheet-like manganese iron titanium zinc phosphate positive electrode material precursor according to claim 1, characterized in that: The following steps are involved: Step 1: prepare a mixed salt solution of manganese salt, ferrous salt, titanium salt and zinc salt in a certain proportion; dissolve phosphate salt in pure water at 20-60°C to prepare a solution; Step 2: Add the phosphate solution into the reactor to prepare the base liquid, adjust the pH value of the base liquid to between 4.5-7.0 with ammonia water, and heat it to 40-70℃; inject the mixed salt solution and ammonia water into the reactor at the same time to react with the base liquid to generate flake NH4Mn x Fe y Ti z Zn n PO4·H2O particles, the slurry is kept in reaction conditions and aged for 8-24 hours; Step 3: The product of step 2 is pumped into a centrifuge for dehydration through a diaphragm pump. After dehydration, it is put into a pulping tank equipped with a phosphoric acid solution for pulping. Then the pulp is pumped into a centrifuge and washed with pure water at 20-90°C to wash away the ammonium salt attached to the surface of the particles and between the gaps of the particles to obtain NH4Mn containing a certain amount of free water. x Fe y Ti z Zn n PO4·H2O block crystals; Step 4: NH4Mn obtained in step 3 x Fe y Ti z Zn n PO4·H2O crystals are dried at 100-200℃ to obtain NH4Mn free of free water. x Fe y Ti z Zn n PO4·H2O block crystals; then use a high-speed mixer to grind the material into powder; Step 5: NH4Mn obtained in step 4 x Fe y Ti z Zn n PO4·H2O powder is put into a sagger and pre-sintered at 280-800℃ under the protection of inert gas to obtain anhydrous deammonium Mn x Fe y Ti z Zn n HPO4 powder.

3. The method for preparing a sheet-like manganese iron titanium zinc phosphate positive electrode material precursor according to claim 2, characterized in that: In the step 1, the manganese salt is at least one of manganese chloride, manganese bromide, manganese sulfate or manganese oxalate; the ferrous salt is at least one of ferrous chloride, ferrous bromide, ferrous sulfate or ferrous oxalate; the titanium salt is titanyl sulfate or titanium sulfate, and the zinc salt is zinc chloride, zinc sulfate or zinc oxalate.

4. The method for preparing a sheet-like manganese iron titanium zinc phosphate positive electrode material precursor according to claim 2, characterized in that: In the step 2, the base solution is prepared with monoammonium phosphate and ammonia water, and no monoammonium phosphate solution is added during the reaction.

5. A lithium ion battery comprising a positive electrode material, characterized in that: The positive electrode material is prepared by using the flaky manganese iron titanium zinc phosphate positive electrode material precursor according to claim 1.

6. Use of the sheet-like manganese iron titanium zinc phosphate positive electrode material precursor as claimed in claim 1 in a lithium ion battery.

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