Spray pyrolysis oxide precursor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of precursor battery novel materials, in particular to a spray pyrolysis oxide precursor and a preparation method and application thereof, and the method comprises the following steps: preparing a metal salt solution; adding alcohol into the metal salt solution, and heating; the method comprises the following steps: preparing a metal salt solution with a certain concentration, atomizing the metal salt solution under a certain high-speed carrier gas, feeding atomized fog drops into a furnace body under a certain carrier gas flow, and sequentially reacting through each temperature zone. Alcohol is added while the temperature of the metal salt solution is increased, so that the concentration of the metal salt solution is greatly increased, the evaporation time of atomized liquid drops in the spraying furnace body is shortened, the viscous-viscous and viscous-dry condensation volume ratio of the fog drops is reduced, the output in unit time is increased, the particle wall thickness is increased, product particles are more uniform, and the product quality is improved. The fogdrop hollow forming probability is reduced, and the compaction is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of novel precursor battery materials, and in particular to a spray pyrolysis oxide precursor and a preparation method and application thereof. Background Art

[0002] In recent years, a lot of investment has been made in the research of using spray pyrolysis technology to produce ternary oxide precursors. Compared with the co-precipitation ternary precursor technology, this technology does not produce wastewater, has low energy consumption, a short production process, and high efficiency. It has obvious advantages in manufacturing costs. However, spray pyrolysis has a short research and development time in the industrial field and is not mature enough.

[0003] Due to the low solubility of metal salts, crystal precipitation often occurs, blocking pipes and nozzles, affecting production. The general solvent is deionized water, and the atomized droplets are in a sticky state for a long time, and there is a stick-stick, stick-dry condensation phenomenon between the droplets, and even a sticking phenomenon, resulting in poor morphology, uneven particles, irregular surface, and more broken spheres.

[0004] Usually the size and distribution of the droplets directly affect the size and distribution of the subsequent powder particles, while the spray efficiency, droplet size and initial velocity depend on the characteristics of the precursor and the spray technology. It is difficult to obtain uniform, micron and submicron droplets using conventional nozzle atomization methods. The evaporation of droplets includes the evaporation of the liquid phase on the droplet surface, the diffusion of the gas phase in the droplet and the contraction of the droplet, so other methods are used to change this situation.

[0005] Moreover, the segmented temperature control technology can effectively control the evaporation rate of the droplets, thereby controlling the generated morphology of the powder. The main principle is that the droplets mainly undergo a salt precipitation process during the drying stage. When the solute begins to precipitate, the vapor diffuses through the pores of the deposition layer, and its diffusion rate is less than the diffusion rate of the solvent vapor in the air. The resistance to mass mobility increases accordingly, and the volatilization rate is significantly reduced. At this time, the temperature of the droplets increases significantly until it reaches the ambient temperature. The temperature control area of ​​the existing technology is usually 2-3 sections, and the temperature control is relatively high, which often causes the primary grains to be larger. Summary of the invention

[0006] The present invention provides a spray pyrolysis oxide precursor and a preparation method and application thereof, which overcome the deficiencies of the above-mentioned prior art and can effectively solve the problems of uneven oxide particles, low activity, much wall sticking material and low yield in the co-precipitation preparation method of the existing oxide precursor.

[0007] To solve the above problems, one of the technical solutions of the present invention is achieved in the following manner: A method for preparing a spray pyrolysis oxide precursor comprises the following steps: preparing a metal salt solution; Add alcohol to the metal salt solution and heat it; The metal salt solution is atomized under high-speed carrier gas, and the atomized droplets are sent into a high-temperature pyrolysis furnace under high-speed carrier gas flow; The atomized droplets react in turn in the five temperature zones in the high-temperature pyrolysis furnace to obtain precursor materials; the reactions include evaporation, precipitation, drying, pyrolysis / solid phase and calcination process reactions.

[0008] The above also includes: separating the precursor material from the gas and the material through the cyclone and the bag dust collection equipment, and collecting the precursor material; wherein the bag dust collection equipment is a high temperature resistant dust collection bag, the temperature of the high temperature resistant bag is 100-300℃, and there is a pulse purge device in the dust collection bag, and the purge frequency is 5-10 times / h.

[0009] The above-mentioned metal salt solution includes chloride, nitrate and sulfate, wherein the metal element in the metal salt solution is one or two or more metal elements selected from nickel, cobalt, manganese, aluminum, tungsten, lithium, sodium, magnesium and titanium.

[0010] The concentration of the metal salt solution is 400-500 g / L, and the temperature of the metal salt solution is 80-100°C.

[0011] The volume of the alcohol added is 0.5-10% of the prepared metal salt solution.

[0012] The high-speed carrier gas is a mixed gas of one or more of nitrogen, compressed air and oxygen; the high-speed carrier gas flow rate is 2-40m³ / h.

[0013] The high-speed carrier gas is a mixed gas of nitrogen and compressed air, and the volume ratio of nitrogen to compressed air is 3:1.

[0014] The temperatures of the five temperature zones in the above-mentioned high-temperature pyrolysis furnace are: the temperature of the first temperature zone is 50-400°C; the temperature of the second temperature zone is 300-600°C; the temperature of the third temperature zone is 450-550°C; the temperature of the fourth temperature zone is 600-800°C; and the temperature of the fifth temperature zone is 700-1000°C.

[0015] The second technical solution of the present invention is achieved by the following method: an oxide precursor is prepared using a method for preparing an oxide precursor by spray pyrolysis.

[0016] The third technical solution of the present invention is achieved in the following way: an application of an oxide precursor in a lithium-ion battery, which is characterized in that it includes mixing the oxide precursor with a lithium source and sintering to obtain a battery positive electrode material.

[0017] Compared with the prior art, the present invention has the following advantages: 1. The present invention prepares a metal salt solution of a certain concentration, atomizes the metal salt solution under a certain high-speed carrier gas, and delivers the atomized droplets into a furnace body under a certain carrier gas flow rate, and sequentially undergoes evaporation, precipitation, drying, pyrolysis / solid phase reaction and calcination through various temperature zones, and then passes through a cyclone and a bag dust collector for gas-material separation and material collection. Compared with the co-precipitation method, the spray pyrolysis method of the oxide precursor proposed in the present invention increases the temperature of the metal salt solution while adding alcohol, thereby greatly increasing the concentration of the metal salt solution, shortening the evaporation time of the atomized droplets in the spray furnace body, reducing the proportion of the droplet stick-stick and stick-dry condensation volumes, increasing the output per unit time, increasing the particle wall thickness, making the product particles more uniform, reducing the probability of hollow droplet formation, and improving compaction.

[0018] 2. The present invention adopts a mixed gas of inert gas and compressed air as a carrier gas and solves the danger of alcohol flash explosion in spray pyrolysis by adjusting the appropriate ratio. At the same time, the addition of inert gas prevents the phenomenon of overburning of atomized droplets and lower activity of products. Through precise carrier gas flow rate and multi-stage temperature zone control, the residence time of droplets in the spray pyrolysis furnace is more stable, and drying, pyrolysis and calcination are more sufficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0020] Figure 1 This is a method flow chart of Example 1 of the present invention.

[0021] Figure 2 In the figure, a is a scanning electron micrograph of the spray-pyrolyzed oxide precursor of Example 4 of the present invention, and b is a scanning electron micrograph of the spray-pyrolyzed oxide precursor grains of Example 4.

[0022] Figure 3 In the figure, a is a scanning electron micrograph of the spray-pyrolyzed oxide precursor of Example 5 of the present invention, and b is a scanning electron micrograph of the spray-pyrolyzed oxide precursor grains of Example 5.

[0023] Figure 4 In the figure, a is a scanning electron micrograph of the spray-pyrolyzed oxide precursor of Example 6 of the present invention, and b is a scanning electron micrograph of the spray-pyrolyzed oxide precursor grains of Example 6.

[0024] Figure 5 In the figure, a is a scanning electron micrograph of the spray-pyrolyzed oxide precursor of Example 7 of the present invention, and b is a scanning electron micrograph of the spray-pyrolyzed oxide precursor grains of Example 7.

[0025] Figure 6 In the figure, a is a scanning electron micrograph of the spray-pyrolyzed oxide precursor of comparative example 1 of the present invention, and b is a scanning electron micrograph of the grains of the spray-pyrolyzed oxide precursor of comparative example 1. DETAILED DESCRIPTION

[0026] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0027] Example 1: Figure 1 As shown, the embodiment of the present invention discloses a method for preparing a spray pyrolysis oxide precursor, comprising the following steps: S101, prepare a metal salt solution; wherein the metal salt solution includes chloride, nitrate and sulfate, but is not limited to other metal salt solutions; wherein the metal element in the metal salt solution is one or two or more metal elements selected from nickel, cobalt, manganese, aluminum, tungsten, lithium, sodium, magnesium and titanium, but is not limited to salt solutions of the above metal elements; the concentration of the prepared metal salt solution is 400-500g / L, and the temperature of the metal salt solution is 80-100°C. By controlling the temperature of the metal salt solution to 80-100°C, the metal salt is prevented from precipitating and the viscosity of the metal salt solution is reduced.

[0028] The metal salt solution is heated by steam or electricity, and the heating device should reach 1 / 3-2 / 3 of the height of the metal salt mixed solution storage tank to increase the contact area between the heating area and the metal salt mixed solution, so as to enable rapid heating.

[0029] S102, adding alcohol to the metal salt solution and heating it; wherein the volume of the alcohol added is 0.5-10% of the prepared metal salt solution; when in use, the alcohol is mixed with water as a solvent, and industrial alcohol can be selected. The alcohol is added in a small amount in a quantitative manner to prevent the alcohol from burning quickly inside the furnace body and exploding.

[0030] S103, atomizing the metal salt solution under high-speed carrier gas, and sending the atomized droplets into the high-temperature pyrolysis furnace under the high-speed carrier gas flow rate; wherein the high-speed carrier gas is a mixed gas of one or more of nitrogen, compressed air, and oxygen; the high-speed carrier gas flow rate is 2-40m³ / h; when the high-speed carrier gas is selected as a mixed gas of nitrogen and compressed air, the volume ratio of nitrogen to compressed air is 3:1.

[0031] Inert gas nitrogen is added to the above-mentioned high-speed carrier gas to prevent alcohol from flashing, and the addition of a large amount of inert gas can reduce the phenomenon of overburning of droplets.

[0032] The above-mentioned high-speed carrier gas flow rate can be selected to be 20-30m³ / h. The carrier gas flow rate cannot be too large. Too large a carrier gas flow rate will quickly take the material out of the furnace body, resulting in incomplete drying. Too small a carrier gas flow rate will cause the material to stay in the furnace body for a long time, resulting in overburning of the material.

[0033] Among them, the atomizer is arranged on the top of the furnace body, and the appropriate temperature can make the atomized droplets reasonably transition from evaporation, precipitation, drying, pyrolysis / solid phase reaction and calcination stages. For example, the length of the temperature zone of the evaporation section and the appropriate temperature can not only make the water evaporate quickly, but also reduce the initial droplets due to excessive temperature, causing air flow disturbance and droplet condensation. At the same time, the water in the droplets evaporates quickly, the droplets run in an orderly manner, and a thin wall is formed before entering the high-temperature pyrolysis, reducing particle explosion. The reasonable length and temperature of the temperature zone of the drying section can increase the probability of solid droplets and improve compaction.

[0034] S104, the atomized droplets react in the five temperature zones in the high-temperature pyrolysis furnace in sequence to obtain a precursor material; wherein the reaction includes evaporation, precipitation, drying, pyrolysis / solid phase and calcination process reactions; wherein the temperatures of the five temperature zones in the high-temperature pyrolysis furnace are: the temperature of the first temperature zone is 50-400°C; the temperature of the second temperature zone is 300-600°C; the temperature of the third temperature zone is 450-550°C; the temperature of the fourth temperature zone is 600-800°C; the temperature of the fifth temperature zone is 700-1000°C. wherein the heating devices of the first temperature zone and the fifth temperature zone are both electric heating, with a power of 20-200Kw.

[0035] This also includes passing the precursor material through a cyclone and bag-type dust collector for gas-material separation and collection; the bag-type dust collector is a high-temperature resistant dust collector bag, the temperature of which the high-temperature resistant dust collector bag can withstand is 100-300°C, and there is a pulse purge device in the dust collector bag, with a purge frequency of 5-10 times / h.

[0036] In summary, the present invention configures a metal salt solution of a certain concentration, atomizes the metal salt solution under a certain high-speed carrier gas, and delivers the atomized droplets into a furnace body under a certain carrier gas flow rate, and passes through each temperature zone to sequentially undergo evaporation, precipitation, drying, pyrolysis / solid phase reaction and calcination process reactions, and then passes through a cyclone and a bag dust collector to separate the gas and material, and collect the material. Compared with the co-precipitation method, the spray pyrolysis method of the oxide precursor proposed in the present invention increases the temperature of the metal salt solution while adding alcohol, which greatly increases the concentration of the metal salt solution, shortens the evaporation time of the atomized droplets in the spray furnace body, reduces the proportion of the sticky-sticky and sticky-dry condensation volume of the droplets, increases the output per unit time, increases the particle wall thickness, makes the product particles more uniform, reduces the probability of hollow formation of droplets, and improves compaction.

[0037] In addition, the embodiment of the present invention solves the danger of alcohol flash explosion in spray pyrolysis by using a mixed gas of inert gas and compressed air as a carrier gas and adjusting the ratio appropriately. At the same time, the addition of inert gas prevents the phenomenon of overburning of atomized droplets and lower activity of products. Moreover, through precise carrier gas flow rate and multi-stage temperature zone control, the residence time of droplets in the spray pyrolysis furnace is more stable, and drying, pyrolysis and calcination are more complete.

[0038] Example 2: The embodiment of the present invention discloses an oxide precursor prepared by a method for preparing an oxide precursor by spray pyrolysis.

[0039] Example 3: The embodiment of the present invention discloses an application of an oxide precursor in a lithium-ion battery, including mixing the oxide precursor with a lithium source and sintering to obtain a battery positive electrode material.

[0040] Embodiment 4: The embodiment of the present invention discloses a method for preparing a spray pyrolysis oxide precursor, comprising the following steps: (1) Prepare 50L of a mixed solution of nickel chloride, cobalt chloride and manganese chloride, with the molar percentage of nickel, cobalt and manganese being 6:2:2, and the concentration of the metal salt solution being 480g / L. Add 10% alcohol solution, and raise the temperature of the metal salt solution to 80°C. (2) Inject the mixed solution into the atomizer, adjust the mixed gas flow ratio of carrier gas nitrogen and compressed air to 3:1, and the spray carrier gas flow rate to 20m / h; (3) Control the temperature of the first temperature zone to 250°C, the temperature of the second temperature zone to 400°C, the temperature of the third temperature zone to 500°C, the temperature of the fourth temperature zone to 650°C, and the temperature of the fifth temperature zone to 750°C; (4) Collect the atomized oxide precursor material and take a scanning electron microscope photo. Figure 2 The electrochemical performance of the prepared positive electrode material was tested, see Table 1.

[0041] Embodiment 5: The embodiment of the present invention discloses a method for preparing a spray pyrolysis oxide precursor, comprising the following steps: (1) Prepare 50L of a mixed solution of nickel chloride, cobalt chloride and manganese chloride, with the molar percentage of nickel, cobalt and manganese elements being 6:2:2 and the concentration of the metal salt solution being 450g / L. Add 6% alcohol solution and raise the temperature of the metal salt solution to 85°C.

[0042] (2) Inject the mixed solution into the atomizer, adjust the mixed gas flow ratio of carrier gas nitrogen and compressed air to 3:1, and the spray carrier gas flow rate to 24m³ / h.

[0043] (3) The temperature of the first temperature zone is raised to 300°C, the temperature of the second temperature zone is raised to 450°C, the temperature of the third temperature zone is raised to 550°C, the temperature of the fourth temperature zone is raised to 700°C, and the temperature of the fifth temperature zone is raised to 800°C.

[0044] (4) Collect the atomized oxide precursor material and take a scanning electron microscope photo. Figure 3 The electrochemical performance of the prepared positive electrode material was tested, see Table 1.

[0045] Embodiment 6: The embodiment of the present invention discloses a method for preparing a spray pyrolysis oxide precursor, comprising the following steps: (1) Prepare 50L of a mixed solution of nickel chloride, cobalt chloride and manganese chloride, with the molar percentage of nickel, cobalt and manganese elements being 6:2:2 and the concentration of the metal salt solution being 400g / L. Add 4% alcohol solution and raise the temperature of the metal salt solution to 90°C.

[0046] (2) Adjust the mixed gas flow ratio of carrier gas nitrogen and compressed air to 3:1, and the spray carrier gas flow rate to 26m³ / h.

[0047] (3) The temperature of the first temperature zone is raised to 350°C, the temperature of the second temperature zone is raised to 500°C, the temperature of the third temperature zone is raised to 550°C, the temperature of the fourth temperature zone is raised to 750°C, and the temperature of the fifth temperature zone is raised to 850°C.

[0048] (4) Collect the atomized oxide precursor material and take a scanning electron microscope photo. Figure 4 The electrochemical performance of the prepared positive electrode material was tested, see Table 1.

[0049] Embodiment 7: The embodiment of the present invention discloses a method for preparing a spray pyrolysis oxide precursor, comprising the following steps: (1) Prepare 50L of a mixed solution of nickel chloride, cobalt chloride and manganese chloride, with the molar percentage of nickel, cobalt and manganese elements being 6:2:2 and the concentration of the metal salt solution being 400g / L. Add 1% alcohol solution and raise the temperature of the metal salt solution to 95°C.

[0050] (2) Inject the mixed solution into the atomizer, adjust the mixed gas flow ratio of carrier gas nitrogen and compressed air to 3:1, and the spray carrier gas flow rate to 28m³ / h.

[0051] (3) The temperature of the first temperature zone is raised to 350°C, the temperature of the second temperature zone is raised to 550°C, the temperature of the third temperature zone is raised to 550°C, the temperature of the fourth temperature zone is raised to 750°C, and the temperature of the fifth temperature zone is raised to 950°C.

[0052] (4) Collect the atomized oxide precursor material and take a scanning electron microscope photo. Figure 5 The electrochemical performance of the prepared positive electrode material was tested, see Table 1.

[0053] Comparative Example 1: (1) Prepare 50 L of a mixed solution of nickel chloride, cobalt chloride and manganese chloride, with the molar percentage of nickel, cobalt and manganese elements being 6:2:2, the concentration of the metal salt solution being 350 g / L, and the temperature of the metal salt solution being raised to 70 °C.

[0054] (2) Inject the mixed solution into the atomizer. The carrier gas is compressed air and the spray carrier gas flow rate is 15m³ / h.

[0055] (3) The temperature of the first temperature zone is raised to 600°C, the temperature of the second temperature zone is raised to 800°C, and the temperature of the third temperature zone is raised to 900°C.

[0056] (4) Collect the atomized oxide precursor material and take a scanning electron microscope photo. Figure 6 The electrochemical performance of the prepared positive electrode material was tested, see Table 1.

[0057] From the above, we can see that Figure 2 a, 3a, 4a, 5a and Figure 6 Compared with a, by adding alcohol to the metal salt solution, the condensation phenomenon of the atomized droplets is significantly reduced, and the amount of broken spheres is relatively small, the interior is denser, and there is no obvious hollow phenomenon. The vibration compaction is increased from 1.05g / cc in the comparative example to about 2.00g / cc in the embodiment. Figure 2 b, 3b, 4b, 5b and Figure 6 b. Under the protection of nitrogen, the grain size on the surface of the droplet sphere is smaller, indicating that the precursor activity is higher. It can be seen from Table 1 that the discharge capacity of the positive electrode material prepared in the embodiment is significantly higher than that of the comparative example, and the rate performance is also about 10% higher than that of the comparative example. Figure 2 Comparing b, 3b, 4b, and 5b, the reasonable gas flow rate and precise temperature control make the grain size on the surface more uniform, and there is no obvious inconsistency in grain size between batches.

Claims

1. A method for preparing a spray pyrolysis oxide precursor, characterized in that: The following steps are involved: preparing a metal salt solution; Add alcohol to the metal salt solution and heat it; The metal salt solution is atomized under high-speed carrier gas, and the atomized droplets are sent into a high-temperature pyrolysis furnace under high-speed carrier gas flow; The atomized droplets react in turn in the five temperature zones in the high-temperature pyrolysis furnace to obtain precursor materials; the reactions include evaporation, precipitation, drying, pyrolysis / solid phase and calcination process reactions.

2. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: Also includes: The precursor material is passed through a cyclone and a bag dust collector for gas-material separation and collection; the bag dust collector is a high-temperature resistant dust collector bag that can withstand a temperature of 100-300°C. The dust collector bag is equipped with a pulse purge device with a purge frequency of 5-10 times / h.

3. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: The metal salt solution includes chloride, nitrate and sulfate, wherein the metal element in the metal salt solution is one or two or more metal elements selected from the group consisting of nickel, cobalt, manganese, aluminum, tungsten, lithium, sodium, magnesium and titanium.

4. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: The concentration of the metal salt solution is 400-500 g / L, and the temperature of the metal salt solution is 80-100°C.

5. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: The volume of the alcohol added is 0.5-10% of the prepared metal salt solution.

6. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: The high-speed carrier gas is a mixed gas of one or more of nitrogen, compressed air and oxygen; the high-speed carrier gas flow rate is 2-40m³ / h.

7. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: The high-speed carrier gas is a mixed gas of nitrogen and compressed air, and the volume ratio of nitrogen to compressed air is 3:

1.

8. The method for preparing a spray pyrolysis oxide precursor according to claim 1, characterized in that: The temperatures of the five temperature zones in the high-temperature pyrolysis furnace are: the temperature of the first temperature zone is 50-400°C; the temperature of the second temperature zone is 300-600°C; the temperature of the third temperature zone is 450-550°C; the temperature of the fourth temperature zone is 600-800°C; and the temperature of the fifth temperature zone is 700-1000°C.

9. An oxide precursor prepared by the method for preparing an oxide precursor by spray pyrolysis according to any one of claims 1 to 8.

10. Use of the oxide precursor as claimed in claim 9 in a lithium ion battery, wherein: The method comprises mixing an oxide precursor with a lithium source and sintering the mixture to obtain a positive electrode material for a battery.

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