JP4401185B2 - Manufacturing method and manufacturing apparatus for electrode material for secondary battery - Google Patents

Description

  The present invention relates to a method and an apparatus for producing an electrode material for a secondary battery comprising spheroidized graphite particles.

  Recently, with the miniaturization of electronic devices and the like, a battery serving as a power source is also required to be miniaturized. In particular, a lithium ion secondary battery has attracted attention from the viewpoint of increasing the capacity of the battery. Among lithium ion secondary batteries, those using a carbon material for the negative electrode are also useful in that a large capacity can be obtained and a safe and high voltage can be obtained.

  By the way, as carbon materials used for batteries, there are natural graphite and artificial graphite. When forming an electrode, a mixture of pulverized natural graphite or artificial graphite, a solvent and a binder (binder) is mixed with a slurry. It is common to apply what has been applied to an object. However, when the shape of the graphite is scaly, the fluidity of the slurry is deteriorated, and there is a problem that the coating workability is remarkably impaired.

Thus, as a result of repeated research aimed at improving these problems, the present inventors maintained the advantages of scaly graphite by pulverizing and re-aggregating scaly natural graphite. However, a technique that improves slurry characteristics and suppresses a decrease in discharge capacity at a large discharge current value has been developed and proposed previously (see, for example, Patent Document 1).
JP-A-11-263612

  However, a problem remains in the technique for effectively crushing and spheroidizing the flake graphite. That is, in the case of the proposed method described above, the peak intensity ratio, which is an index indicating the degree of roundness (degree of spheroidization) of the spheroidized graphite particles that contributes to the improvement of cycle characteristics when charging and discharging the secondary battery, Although it is possible to increase by increasing the gas blowing time, the upper limit value is low and there is room for improvement.

  The present invention has been made in view of such problems, and provides a method and apparatus for producing an electrode material for a secondary battery made of spheroidized graphite particles capable of further increasing the peak intensity ratio. With the goal.

  The method for producing an electrode material for a secondary battery according to claim 1 of the present invention supplies a granulated raw material containing at least scaly graphite into a circulation container configured to circulate the granulated raw material, and When producing an electrode material for a secondary battery by spraying a granulating gas from a plurality of surrounding locations toward the middle of the circulation region of the granulated raw material and aggregating the scaly graphite. The granulating gas is sprayed at two or more positions along the moving direction of the granulated raw material with respect to the circulation region of the granulated raw material.

  An apparatus for producing an electrode material for a secondary battery according to claim 2 of the present invention comprises a circulation container configured to circulate a granulation raw material containing at least scaly graphite, and the granulation raw material in the circulation container. Supplying means for supplying, and gas blowing for blowing a granulating gas from a plurality of locations around each position to two or more positions along the moving direction of the granulated raw material in the circulation region of the granulated raw material Means.

  In the case of the inventions of claims 1 and 2, by increasing the spraying position of the granulating gas, the collision range of the granulated raw material or the collision point of the granulated raw material per unit time (during one circulation) The number of granulated raw material collision points) increases. Thereby, the frequency | count of collision of the granulation raw material per unit time increases, and the peak intensity ratio showing the roundness degree of spheroidized graphite particle | grains is raised more. In addition, since it becomes possible to reach a certain peak intensity ratio in a shorter time than in the past, the production efficiency can be increased.

  Embodiments of the present invention will be specifically described below.

  FIG. 1 is a front view showing an apparatus for producing an electrode material for a secondary battery according to this embodiment, and FIG. 2 is a plan view showing the periphery of a blowing nozzle.

  The manufacturing apparatus includes a circulation container 1, a feeder 2 for supplying a granulated raw material containing at least scaly graphite in the circulation container 1, and a plurality of, six in this embodiment, attached to the side wall of the circulation container 1. The nozzle 3 for spraying, the classifier 4 provided in the upper part of the circulation container 1, and the nozzle 5 for blowing provided in the bottom part of the circulation container 1 are provided.

  The circulation container 1 has a cylindrical shape in which the ceiling and the bottom are closed, and is arranged with the axis centering in the vertical direction, and is configured with the vertical direction being vertically long. The feeder 2 is provided in the middle of the side surface in the height direction. The feeder 2 is disposed in a cylindrical shape so as to be inclined, and its lower end is provided in a state of penetrating the side surface of the circulation container 1, and an open / close valve is provided at the top. When the opening / closing valve of the feeder 2 is opened, a predetermined amount of the mixed powder is supplied into the circulation container 1 as indicated by a one-dot chain line. In addition, the feeder 2 is also used as an outlet in the present embodiment.

  The granulation raw material supplied into the circulation container 1 is circulated by convection in the vertical direction by the blowing gas from the blowing nozzle 5 and the granulating gas from the blowing nozzle 3. The circulation is performed, for example, so as to rise along the axial center of the circulation container 1, spread outward near the ceiling, and descend along the side surface toward the axial center near the bottom surface. Thereafter, the granulated raw material is circulated through a similar circulation path.

  The blowing nozzle 5 is used not only for the circulation described above but also for discharging. At the time of discharge, the nozzle 5 is used to blow up the granulated raw material and take out the granulated raw material from the feeder 2 to the outside.

  The classifier 4 is provided in the upper part of the circulation container 1 and is configured to separate the granulated raw material and gas and discharge the gas to the outside of the circulation container 1.

  The spray nozzle 3 has a function of aggregating the scaly graphite constituting the granulated raw material, in addition to being used for the circulation described above, and the two sets are shifted in the vertical direction as one set of three. Arranged.

  Each nozzle 3 is attached to the side wall of the circulation container 1 as shown in FIG. Specifically, the nozzle 3 is inserted from the outside into a cylindrical mounting portion 1a provided outside the side wall of the circulation container 1, and the flange portion 3a formed on the outer periphery of the nozzle 3 is used as an end surface of the mounting portion 1a. The fixture 10 is attached from the outside of the nozzle 3 in the set state by being brought into contact with the attachment portion 1a. The fixing tool 10 is formed with an outer insertion portion 10b projecting laterally on the outer peripheral edge of a circular ring-shaped pressing portion 10a. On the inner peripheral surface of the outer insertion portion 10b, a cylindrical mounting portion 1a is provided. A female screw that is screwed into a male screw formed on the outer peripheral surface is formed. Therefore, when the fixture 10 is rotated in a predetermined direction, the extrapolated portion 10b goes deep into the mounting portion 1a, the inner surface of the pressing portion 10a presses the flange portion 3a, and the nozzle 3 is mounted on the side wall of the circulation container 1. . In addition, 11 in FIG. 3 is the packing pinched | interposed between the attaching part 1a and the collar part 3a.

  Each of the nozzles 3 in each group is arranged toward the annular region where the granulated raw material rises along the axis of the circulation container 1, and the jet gas from these nozzles 3 is directed toward the center of the annular region. It is sprayed to form a collision zone. In the present embodiment, two sets of three nozzles 3 are provided in a state of being separated in the vertical direction, so that two collision areas are formed in the vertical direction. For example, air, nitrogen, or water vapor is used as the gas.

  As the granulation raw material to be granulated by the production apparatus according to the present embodiment configured as described above, the above-described one composed only of flaky graphite or a mixed powder of flaky graphite and fine particles is used. It is done. As the fine particles, those described in Japanese Patent Application No. 2002-269096 by the applicant of the present application are used. Here, the case where only the former scaly graphite is used as a granulation raw material will be described as an example.

  As the flaky graphite, flaky natural graphite or artificial graphite can be used. For example, flaky natural graphite can be used as it is because it is generally available in a purity exceeding 85% to 99%. If necessary, it is also preferred to further increase the purity by a known method. There are various particle sizes of graphite as a raw material, but it is preferable to use scaly graphite (raw material) having an average particle diameter of about 10 to 200 μm before spheroidization.

  The granulated raw material is granulated as follows.

  The on-off valve of the feeder 2 is opened to supply the granulated raw material into the circulation container 1. At this time, it is preferable that gas is blown in advance from the blowing nozzle 5 and the blowing nozzle 3 so that the gas moves along the circulation path. That is, the amount of the granulated material stored in the bottom of the circulation container 1 can be reduced, and the granulated material can be circulated smoothly.

  The granulated raw material supplied into the circulation container 1 moves on the circulation path like the gas through the circulating gas. In the middle of the movement, first, when passing through a collision zone formed by a set of three nozzles 3 on the lower side, the granulated raw material collides and aggregates and spheroidizes. Then, when passing through the collision area formed by the upper set of three nozzles 3, the scaly graphite collides and aggregates as before. After that, it moves on the circulation path, and agglomeration is repeated again by the two sets of nozzles 3, and the degree of circularity of the gradually spheroidized graphite is increased, and the peak intensity ratio is improved. At this time, the gas is discharged to the outside of the circulation container 1 through the classifier 4, and in addition, fine powder below the classification limit is also discharged to the outside of the circulation container 1 through the classifier 4.

  Thereafter, for example, after a lapse of 30 minutes or longer, gas blowing from the blowing nozzle 5 and the blowing nozzle 3 is stopped. Thereby, the spheroidized graphite particles are stored at the bottom of the circulation container 1. Thereafter, the open / close valve of the feeder 2 is changed from the closed state to the open state, the gas is blown out from the blowing nozzle 5, and the granulated raw material is taken out from the feeder 2 and collected. The recovered spheroidized graphite particles are formed on the electrode of the secondary battery by pressing or the like.

Note that the nozzle discharge pressure, the amount of blowing gas, the internal pressure of the circulation container, etc. when the gas is blown from the nozzle 3 are set to substantially constant values that can achieve smooth collision and flow, and the processing time is set appropriately. To spheroidize the flake graphite. For example, the nozzle discharge pressure may be about 0.01 to 0.50 MPa, the amount of blowing gas may be about 0.2 to 10.0 Nm ³ / min, the internal pressure of the circulation container may be about −10 to 30 kPa, and the processing time may be 30 minutes or more. Moreover, what is necessary is just to let the temperature in the circulation container 1 be about 0-60 degreeC.

  FIG. 4 is a graph showing the results (black circles) of investigating changes in the peak intensity ratio when the processing time is changed at 10, 20, 30, 40, and 50 minutes. In addition, this figure also shows the results (white circles) obtained by processing in 20 minutes, 30 minutes, 35 minutes, 40 minutes, 50 minutes, and 60 minutes by the conventional method. Table 1 also summarizes similar results.

  As can be seen from FIG. 4 and Table 1, in the case of the conventional method, it was difficult to make the peak intensity ratio 0.011 or more even if the processing time was lengthened. The peak intensity ratio can be made 0.011 or more by setting the treatment time to 30 minutes or more. In addition, since it becomes possible to reach a certain peak intensity ratio in a shorter time than in the past, the production efficiency can be increased.

  The reason is as follows. That is, by changing the amount of the granulating gas blown from the nozzles 3 and 5, the circulation time of the granulated raw material carried by the gas and the gas in the circulation container is affected. However, in the present embodiment, the amount of gas blown from the nozzles 3 and 5 is substantially constant regardless of the processing time, and therefore the circulation time of the granulated raw material is substantially constant. Thus, even if the circulation time of the granulated raw material is substantially constant, by increasing the spraying position of the granulating gas as in this embodiment, the number of collisions of the granulated raw material per unit time increases, For example, since the number of collisions of the granulated raw material during one circulation of the granulated raw material increases, the peak intensity representing the degree of roundness of the spheroidized graphite particles that could not be obtained when the processing time was simply increased The ratio can be improved.

The peak intensity ratio is the peak intensity ratio between the 002 plane (plane parallel to the graphite layer) and the 110 plane (plane perpendicular to the graphite layer) [Ih ₁₁₀ / Ih], which is an index of randomness of orientation. ₀₀₂ ], which is calculated from the peak area of the 002 plane peak (26.5 °) and the 110 plane peak (77.5 °) and the following equation.

Peak intensity ratio [Ih ₁₁₀ / Ih ₀₀₂ ]
= [Net Int (110) plane] / [net Int (002) plane]
The measurement conditions for the peak intensity ratio are as follows.
・ Device: “RINT2000” manufactured by Rigaku Corporation
・ Cell: Inner diameter 2.4cm, Height 0.315cm
Filling of the sample to the cell: the powder was 2.3g weighed, placed in a mold having a radius of 1.2 cm, - sample density thickness at load 1000kg is pressed until 0.315cm: 2.3g / [(1.2) 2 cm ² × π × 0.315 cm] = 1.6 g / cm ³
・ Measurement angle: 3 ~ 90 °
・ Scanning speed: 9 ° / min
・ Rotation speed: 60rpm
-Data processing: integral intensity calculation, 9 smoothing points, automatic background removal.

  In the above-described embodiment, two sets of three nozzles for spraying are provided on the side surface of the annular container, but the present invention is not limited to this. For example, the number of nozzles for spraying may be two or four or more. In short, the number and angle of the nozzles are not limited as long as the gas discharged from the nozzles collides to form a collision zone. Moreover, although 2 sets are arrange | positioned in the state separated in the up-down direction, you may arrange | position in the state (state in which the height position was varied in each set) which separated 3 sets or more in the up-down direction.

  Moreover, in embodiment mentioned above, it was made to form the cyclic | annular airflow which moves a granulation raw material circularly by blowing gas also from the nozzle for blowing provided in the bottom part of the cyclic | annular container in addition to the nozzle for blowing. However, the present invention is not limited to this. For example, you may make it form annular airflow only with the gas from the nozzle for spraying. In this case, the blowing nozzle is used only for taking out the granulated raw material after processing.

  Further, in the above-described embodiment, a cylindrical container whose ceiling and bottom are closed is used as the annular container, but the present invention is not limited to this. For example, you may use the ring-shaped annular container which curved the long cylinder in the ring shape and joined both ends. In this case, since the granulated raw material flows along the shape of the annular container, two or more sets of spray nozzles may be arranged at arbitrary locations.

It is front sectional drawing which shows the manufacturing apparatus of the electrode material for secondary batteries which concerns on one Embodiment of this invention. It is a top view which shows arrangement | positioning of the nozzle for spraying with which the manufacturing apparatus of FIG. 1 was equipped. It is sectional drawing which shows the attachment state of the nozzle for spraying of FIG. It is a graph which shows the result (black circle mark) which investigated the change of the peak intensity ratio at the time of processing by the method of this invention (black circle mark), and the result (white circle mark) processed by the conventional method.

Explanation of symbols

1 annular container 2 feeder 3 nozzle for spraying 4 classifier 5 nozzle for blowing up

Claims (2)

  A granulated raw material containing at least scaly graphite is supplied into a circulation container configured so that the granulated raw material circulates, and the granulated raw material is fed from a plurality of surrounding locations toward the middle of the circulation region of the granulated raw material. When producing a secondary battery electrode material by spraying a gas for granulation on the middle part and agglomerating the flake graphite, the gas for granulation is sprayed on the circulation region of the granulation raw material. The method for producing an electrode material for a secondary battery, which is performed at two or more positions along the moving direction of the granulated raw material. A circulation container configured to circulate a granulated raw material containing at least scaly graphite;
Supply means for supplying the granulated raw material into the circulation container;
Gas spraying means for spraying a granulating gas from a plurality of locations around each position with respect to two or more positions along the moving direction of the granulated raw material in the circulation region of the granulated raw material An apparatus for producing an electrode material for a secondary battery.

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