Sintering device for positive electrode material of lithium ion battery

Abstract

The utility model discloses a sintering device for a positive electrode material of a lithium ion battery, which belongs to a sintering device and completes a sintering process of precursor powder in an inert gas environment. Comprising a base, a feeding assembly located on the base, a heating wire used for increasing the temperature of the feeding assembly to the reaction temperature and a vibrator fixedly connected with the feeding assembly, and the two ends of the feeding assembly are the feeding end and the discharging end respectively; precursor powder enters the feeding assembly from the feeding end, is flatly laid on the feeding assembly under the vibration effect of the vibrator, moves towards the discharging end and falls out of the discharging end; the problems that static stacking type sintering is adopted in a high-temperature solid-phase method, due to material stacking, the sintering temperature is high, the sintering period is long, energy consumption is large, and due to material stacking, the sintering reaction is incomplete, half-cooked or the material performance is unstable are solved.

Description

Technical Field

[0001] The utility model relates to a sintering device, in particular to a sintering device for positive electrode materials of a lithium ion battery. Background Art

[0002] With the rapid development of electric vehicles and renewable energy storage technology, the demand for lithium iron phosphate batteries continues to increase. In the preparation process of lithium iron phosphate, sintering is one of the key steps.

[0003] The existing lithium iron phosphate sintering process adopts a high-temperature solid-phase method, which is to mix the raw materials of lithium iron phosphate (such as lithium iron phosphate salt, iron phosphate, etc.) in a certain proportion, grind, dry and other processes, and then put them into a muffle furnace or a tubular high-temperature furnace for calcination to obtain lithium iron phosphate material.

[0004] However, the above technical solution has the following problems: the high-temperature solid-phase method adopts static stacking sintering. Due to the accumulation of materials, in addition to the problems of high sintering temperature, long sintering cycle and high energy consumption, the accumulation of materials also leads to inconsistent internal and external temperatures, resulting in incomplete sintering reaction, undercooked or unstable material properties, etc., which needs to be improved. Utility Model Content

[0005] In order to overcome the deficiencies of the prior art, the utility model provides a sintering device for positive electrode materials of lithium ion batteries to solve the above-mentioned technical problems.

[0006] The technical solution adopted by the utility model to solve its technical problems is:

[0007] A sintering device for positive electrode materials of lithium-ion batteries, the sintering device completes the sintering process of precursor powder in an inert gas environment, comprises a base, a feeding assembly located on the base, a heating wire for raising the temperature of the feeding assembly to a reaction temperature, and a vibrator fixedly connected to the feeding assembly, wherein the two ends of the feeding assembly are a feeding end and a discharging end respectively; the precursor powder enters the feeding assembly from the feeding end, and under the vibration of the vibrator, is spread on the feeding assembly and moves toward the discharging end and falls out from the discharging end.

[0008] By adopting the above technical scheme, a proper amount of precursor powder is taken and put into a vacuum oven for preheating treatment, and then the sintering device is placed in an inert gas environment. The heating wire raises the temperature of the feeding component to the required reaction temperature, and the pretreated precursor powder is added to the feeding end of the feeding component, and the vibrator is turned on. Under the action of the vibrator, the precursor powder will be spread on the feeding component to form a very thin layer of powder, and gradually move toward the discharge end. During the movement, the temperature of the feeding component is transmitted to the precursor powder and causes it to react. Finally, the powder that has completed the reaction falls out from the discharge end to complete the sintering process. In the sintering process of the sintering device of the utility model, the vibrator can produce two technical effects. First, under the action of vibration, the precursor powder can be spread on the feeding component more evenly and flatly, and second, under the action of vibration, the precursor powder can be slowly moved toward the discharge end, so that each part of the precursor powder can be evenly heated, thereby effectively avoiding the problem of inconsistent internal and external temperatures due to material accumulation in the high-temperature solid phase method, resulting in incomplete sintering reaction, undercooked or unstable material properties.

[0009] Preferably, the vibrator is a magnetic vibrator, comprising a fixed seat, a leaf spring with one end fixed to the fixed seat and the other end against a feeding assembly, a magnet fixed to the free end of the leaf spring, an electromagnetic coil fixed to the fixed seat and arranged opposite to the magnet, and a power supply for supplying power to the electromagnetic coil; the leaf spring is arranged at an angle, and its fixed end is closer to the discharge end than its free end in a vertical plane; when the electromagnetic coil is energized, the free end of the leaf spring applies a vibration force to the feeding assembly toward the discharge end.

[0010] By adopting the above technical scheme, by changing the current direction of the electromagnetic coil, the magnetic pole of the electromagnetic coil is changed to attract or repel the magnet, so as to drive the free end of the leaf spring to vibrate back and forth, and give the feeding component an upward vibration force toward the discharge end. The vibration force can be divided into a vertical upward force and a lateral force toward the discharge end. The lateral force is transmitted to the precursor powder, so that the precursor powder moves slowly toward the discharge end, and the sintering process is carried out during the movement. In this scheme, even if the feeding component is in a horizontal state, the directional movement of the precursor powder can still be achieved.

[0011] Preferably, the feed end of the feeding assembly is higher than the discharge end thereof on a horizontal plane.

[0012] By adopting the above technical solution, a gasket can be added under the base at the bottom of the feed end of the feeding component, so that the feed end of the feeding component is higher than its discharge end on the horizontal plane, and the feeding component is in a slightly inclined state, which can further control the movement of the precursor powder toward the discharge end.

[0013] Preferably, the feeding assembly includes a supporting steel plate, mullite arranged on the supporting steel plate and arranged in a U shape, a feeding track clamped by the mullite, and a graphite strip located below the feeding track, and the heating wire is embedded in the graphite strip.

[0014] By adopting the above technical solution, the heating wire can be directly laid at the bottom of the feeding track, but embedded in the graphite strip, and then the graphite strip is used to conduct heat to the feeding track, so that the feeding track can be heated more evenly and the problem of uneven heating of the precursor powder caused by inconsistent temperature can be avoided.

[0015] Preferably, the graphite strip is shorter than the feeding track and is located in the middle of the feeding track.

[0016] By adopting the above technical solution, the temperature in the middle section of the feeding track is the highest, and the temperature gradually decreases from the middle section to the feeding end or the discharging end, so that the cold material just falling into the feeding track has a gradual temperature increase transition, preventing the cold material from directly contacting the high-temperature feeding track after falling, generating airflow or splashing.

[0017] Preferably, the feeding track is a molybdenum track or a tungsten steel track.

[0018] By adopting the above technical solution, the high temperature resistance of molybdenum can reach 1600 degrees, and the high temperature resistance of tungsten steel can reach more than 900 degrees. The feeding tracks made of these two materials can reach above the reaction temperature and meet the temperature requirements; at the same time, the structures of these two materials are stable, can be used repeatedly for a long time, and do not have side reactions with the precursor.

[0019] Preferably, the base comprises a bottom plate, a support column and a U-shaped steel plate which are arranged in sequence from bottom to top, and the U-shaped steel plate clamps the vibrator and a condenser for cooling the vibrator.

[0020] By adopting the above technical solution, the U-shaped steel plate can well fix the vibrator and the condenser to prevent the displacement of parts caused by long-term vibration; the condenser can effectively control the temperature of the vibrator when it is in working state.

[0021] Preferably, the amplitude and frequency of the vibrator are adjustable.

[0022] By adopting the above technical solution, common vibrators can achieve adjustable amplitude and frequency, and in the utility model, the moving speed of the precursor powder on the feeding track can be increased or decreased by adjusting the amplitude and frequency of the vibrator, thereby controlling the sintering time.

[0023] Preferably, the sintering device completes the sintering process in a glove box filled with argon.

[0024] Preferably, the reaction temperature is 600-900 degrees.

[0025] The beneficial effects of the utility model are:

[0026] 1. The use of a vibrator can make the precursor powder more evenly and flatly spread on the feeding component, and can also make the precursor powder slowly move toward the discharge end, so that each part of the precursor powder can be heated evenly, thereby effectively avoiding the high-temperature solid phase method due to material accumulation resulting in inconsistent internal and external temperatures, resulting in incomplete sintering reaction, undercooked or unstable material properties.

[0027] 2. The utility model provides two methods of using a vibrator to slowly move the precursor powder toward the discharge end. One is to use a magnetic vibrator to give the feeding component an oblique upward vibration force toward the discharge end. The vibration force can be divided into a vertical upward force and a lateral force toward the discharge end. The lateral force is transmitted to the precursor powder to slowly move the precursor powder toward the discharge end. The other is to add a gasket under the base at the bottom of the feeding end of the feeding component to make the feeding end of the feeding component higher than its discharge end on the horizontal plane. These two methods can be used simultaneously in one embodiment to flexibly adjust the rate at which the precursor powder moves slowly.

[0028] 3. Use mullite to clamp the feeding track, and set a graphite strip under the feeding track. Use the graphite strip to heat the feeding track to make the heating of the feeding track more uniform. At the same time, the length of the graphite strip is shorter than the feeding track and is located in the middle of the feeding track, so that the temperature of the feeding end and the discharging end is not high. The cold material that has just fallen into the feeding track has a gradual temperature increase transition to prevent the cold material from directly contacting the high-temperature feeding track after falling, generating airflow or splashing. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0030] Figure 1 It is a structural schematic diagram of the utility model;

[0031] Figure 2 It is an explosion diagram of the utility model;

[0032] Figure 3 for Figure 2 The local schematic diagram of the A in the middle;

[0033] Figure 4 It is a structural schematic diagram of the feeding assembly and the vibrator in the utility model.

[0034] The descriptions of the reference numerals in the figures are as follows:

[0035] 1. base; 101. bottom plate; 102. support column; 103. U-shaped steel plate;

[0036] 2. Feeding assembly; 201. Feeding end; 202. Discharging end; 203. Supporting steel plate; 204. Mullite; 205. Feeding track; 206. Graphite strip;

[0037] 3. vibrator; 301. fixing seat; 302. leaf spring; 303. magnet; 304. electromagnetic coil;

[0038] 4. Condenser. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the concept, specific structure and technical effects of the utility model in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the utility model. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the creation of the utility model can be combined interchangeably without conflicting with each other.

[0040] A sintering device for lithium-ion battery positive electrode materials, such as Figure 1 and Figure 2 As shown, the sintering device completes the sintering process of the precursor powder in an inert gas environment. Specifically, the sintering device completes the sintering process in a glove box filled with argon.

[0041] The sintering device includes a base 1, a feeding assembly 2 located on the base 1, a heating wire for raising the temperature of the feeding assembly 2 to the reaction temperature, and a vibrator 3 fixedly connected to the feeding assembly 2, wherein the two ends of the feeding assembly 2 are a feeding end 201 and a discharging end 202, respectively; the precursor powder enters the feeding assembly 2 from the feeding end 201, and under the vibration action of the vibrator 3, is spread on the feeding assembly 2 and moves toward the discharging end 202 and falls out from the discharging end 202.

[0042] The base 1 includes a bottom plate 101, a support column 102 and a U-shaped steel plate 103 arranged in sequence from bottom to top, and the U-shaped steel plate 103 clamps the vibrator 3 and a condenser 104 for cooling the vibrator 3. The U-shaped steel plate 103 can well fix the vibrator 3 and the condenser 104 to prevent the displacement of parts caused by long-term vibration; the condenser 104 can effectively control the temperature of the vibrator 3 when it is in working state.

[0043] The feeding assembly 2 includes a supporting steel plate 203, mullite 204 arranged on the supporting steel plate 203 and arranged in a U shape, a feeding track 205 clamped by the mullite 204, and a graphite strip 206 located below the feeding track. The heating wire can be directly laid at the bottom of the feeding track 205, but for further optimization, the heating wire can be embedded in the graphite strip 206. The heating wire first conducts heat to the graphite strip 206, and then the graphite strip 206 conducts heat to the feeding track 205. In this way, the heating of the feeding track 205 can be more uniform, avoiding the problem of uneven heating of the precursor powder caused by inconsistent temperature (since the heating wire is embedded in the graphite strip, the heating wire is not shown in the figure). Mullite 204 can effectively isolate heat loss and play a role in heat preservation and heat insulation.

[0044] Further optimization is that the length of the graphite strip 206 is shorter than the feeding track 205 and is located in the middle of the feeding track 205; so that the temperature in the middle of the feeding track 205 is the highest, and the temperature gradually decreases from the middle to the feeding end 201 or the discharging end 202, so that the cold material just falling into the feeding track 205 has a gradual temperature increase transition, preventing the cold material from directly contacting the high-temperature feeding track 205 after falling, generating airflow or splashing. Specifically, the temperature in the middle of the feeding track 205 can reach the reaction temperature of the precursor powder of 600-900 degrees.

[0045] The feed track 205 is a molybdenum track or a tungsten steel track; the high temperature resistance of molybdenum can reach 1600 degrees, and the high temperature resistance of tungsten steel can also reach more than 900 degrees. The feed tracks 205 made of these two materials can reach above the reaction temperature and meet the temperature requirements. At the same time, these two materials have stable structures, can be used repeatedly for a long time, and have no side reactions with the precursor.

[0046] The preparation process of the precursor powder is as follows: using ferrous sulfate as an iron source, phosphoric acid as a phosphorus source, hydrogen peroxide as an oxidant, and ammonia water as a precipitant, first preparing amorphous iron phosphate, adding phosphoric acid and ammonia water simultaneously to adjust the pH value of the slurry during the aging process, raising the temperature and keeping the temperature to obtain basic ammonium iron phosphate with a crystal structure of NH4Fe2(OH)(PO4)2·2H2O, and calcining to obtain anhydrous iron phosphate;

[0047] Industrial-grade lithium carbonate and deionized water are mixed, high-purity carbon dioxide gas is introduced into the mixed aqueous solution, and the mixture is stirred at a certain temperature for a certain period of time to obtain a high-purity lithium bicarbonate solution after removing calcium and magnesium impurities, and then high-purity lithium hydroxide is added to react and precipitate to obtain battery-grade lithium carbonate;

[0048] Anhydrous iron phosphate, battery-grade lithium carbonate and citric acid are fully mixed in a certain proportion to obtain a lithium iron phosphate positive electrode material precursor.

[0049] The sintering process flow of the utility model is as follows: take an appropriate amount of precursor powder and put it into a vacuum oven for preheating treatment, then place the sintering device in a glove box, evacuate the air in the glove box and inject argon gas, and use a heating wire to raise the temperature of the feeding component 2 to the required reaction temperature, add the pretreated precursor powder to the feeding end 201 of the feeding component 2, and turn on the vibrator 3. Under the action of the vibrator 3, the precursor powder will be spread on the feeding component 2 to form a very thin layer of powder, and gradually move toward the discharge end 202. During the movement, the temperature of the feeding component 2 is transmitted to the precursor powder to make it react, and finally the powder after the reaction is completed falls out from the discharge end 202 to complete the sintering process.

[0050] The technical effect achieved by the utility model is as follows: in the sintering process, the vibrator 3 can produce two technical effects. First, under the action of vibration, the precursor powder can be spread more evenly and flatly on the feeding component 2; second, under the action of vibration, the precursor powder can be slowly moved toward the discharge end 202, so that each part of the precursor powder can be heated evenly, thereby effectively avoiding the problems of incomplete sintering reaction, undercookedness or unstable material properties caused by inconsistent internal and external temperatures due to material accumulation in the high-temperature solid phase method.

[0051] like Figure 3 and Figure 4 As shown, in order to enable the vibration of the vibrator 3 to make the precursor powder move slowly and directional toward the discharge end 202, the utility model provides two solutions.

[0052] The first type: the vibrator 3 is a magnetic vibrator, including a fixed base 301, a leaf spring 302 with one end fixed to the fixed base 301 and the other end against the feeding component 2, a magnet 303 fixed to the free end of the leaf spring 302, an electromagnetic coil 304 fixed to the fixed base 301 and arranged opposite to the magnet 303, and a power supply (not shown in the figure) for powering the electromagnetic coil 304; the top of the fixed base 301 is fixedly connected to the supporting steel plate 203; the leaf spring 302 is inclined, and its fixed end is closer to the discharge end 202 than its free end in the vertical plane; when the electromagnetic coil 304 is energized, the free end of the leaf spring 302 gives the feeding component 2 a vibration force toward the discharge end 202.

[0053] By changing the current direction of the electromagnetic coil 304, the magnetic pole of the electromagnetic coil 304 is changed to attract or repel the magnet 303, so as to drive the free end of the leaf spring 302 to vibrate back and forth, and give the feeding component 2 an upward vibration force toward the discharge end 202. The vibration force can be divided into a vertical upward force and a lateral force toward the discharge end 202. The lateral force is transmitted to the precursor powder, so that the precursor powder moves slowly toward the discharge end 202, and the sintering process is carried out during the movement. In this scheme, even if the feeding component 2 is in a horizontal state, the directional movement of the precursor powder can still be achieved.

[0054] The second method: add a gasket under the base 1 at the bottom of the feed end 201 of the feeding component 2, so that the feed end 201 of the feeding component 2 is higher than its discharge end 202 on the horizontal plane, and the feeding component 2 is in a slightly tilted state. The precursor powder will move toward the discharge end 202 under the action of vibration.

[0055] The above two methods can be used simultaneously in one embodiment, that is, the vibrator 3 is set as a magnetic vibrator, and the height of the feed end 201 is increased at the same time to flexibly adjust the rate at which the precursor powder moves slowly.

[0056] It is further optimized that the amplitude and frequency of the vibrator 3 are adjustable; common vibrators 3 are all capable of achieving adjustable amplitude and frequency, and in the present invention, the amplitude and frequency of the vibrator 3 can be adjusted to increase or decrease the moving speed of the precursor powder on the feeding track 205, thereby controlling the sintering time.

[0057] The above is a specific description of the preferred implementation of the utility model, but the invention of the utility model is not limited to the described embodiments. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the utility model. These equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A sintering device for lithium-ion battery positive electrode materials, the sintering device completes the sintering process of precursor powder in an inert gas environment, characterized in that: The invention comprises a base (1), a feeding assembly (2) located on the base (1), a heating wire for raising the temperature of the feeding assembly (2) to a reaction temperature, and a vibrator (3) fixedly connected to the feeding assembly (2), wherein the two ends of the feeding assembly (2) are respectively a feeding end (201) and a discharging end (202); the precursor powder enters the feeding assembly (2) from the feeding end (201), and under the vibration of the vibrator (3), is spread on the feeding assembly (2), moves toward the discharging end (202), and falls out from the discharging end (202).

2. The sintering device for lithium-ion battery positive electrode materials according to claim 1, characterized in that: The vibrator (3) is a magnetic vibrator, comprising a fixed seat (301), a leaf spring (302) with one end fixed to the fixed seat (301) and the other end abutting against the feeding assembly (2), a magnet (303) fixed to the free end of the leaf spring (302), an electromagnetic coil (304) fixed to the fixed seat (301) and arranged opposite to the magnet (303), and a power supply for supplying power to the electromagnetic coil (304); the leaf spring (302) is arranged in an inclined manner, and its fixed end is closer to the discharge end (202) than its free end on a vertical plane; when the electromagnetic coil (304) is energized, the free end of the leaf spring (302) applies a vibration force to the feeding assembly (2) toward the discharge end (202).

3. The sintering device for lithium-ion battery positive electrode material according to claim 1 or 2, characterized in that: The feeding end (201) of the feeding assembly (2) is higher than the discharging end (202) thereof on a horizontal plane.

4. The sintering device for lithium-ion battery positive electrode materials according to claim 1, characterized in that: The feeding assembly (2) comprises a supporting steel plate (203), mullite (204) arranged on the supporting steel plate (203) and arranged in a U shape, a feeding track (205) clamped by the mullite (204), and a graphite strip (206) located below the feeding track, and the heating wire is embedded in the graphite strip (206).

5. The sintering device for lithium-ion battery positive electrode materials according to claim 4, characterized in that: The graphite strip (206) is shorter than the feeding track (205) and is located in the middle of the feeding track (205).

6. The sintering device for lithium-ion battery positive electrode materials according to claim 4, characterized in that: The feeding track (205) is a molybdenum track or a tungsten steel track.

7. The sintering device for lithium-ion battery positive electrode materials according to claim 1, characterized in that: The base (1) comprises a bottom plate (101), a support column (102) and a U-shaped steel plate (103) which are arranged in sequence from bottom to top, and the U-shaped steel plate (103) clamps a vibrator (3) and a condenser (4) for cooling the vibrator (3).

8. The sintering device for lithium-ion battery positive electrode materials according to claim 1, characterized in that: The amplitude and frequency of the vibrator (3) are adjustable.

9. The sintering device for lithium-ion battery positive electrode materials according to claim 1, characterized in that: The sintering device completes the sintering process in a glove box filled with argon.

10. The sintering device for lithium-ion battery positive electrode materials according to claim 1, characterized in that: The reaction temperature is 600-900 degrees.

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