JP6508018B2 - Granule mixing device - Google Patents

Description

  The present invention relates to, for example, a powder-particle mixing apparatus that mixes powder particles such as active material granules used for forming an active material layer of a lithium ion secondary battery.

In forming an active material layer of a positive electrode or a negative electrode of a lithium ion secondary battery, a wet active material granule containing an active material and a solvent may be used. As a prior art relevant to the active material granule for such a lithium ion secondary battery, patent document 1 is mentioned, for example.
By the way, there are cases where it is desired to mix powder particles such as such active material granules. As a mixing apparatus which performs this mixing, the mixing apparatus which has arrange | positioned the stirring blade which carries out stirring mixing of the granular material in the inside of the container which accommodates a granular material is known.

JP-A-9-225281

  However, when powdery particles such as active material granules for a lithium ion secondary battery are mixed using a mixing apparatus provided with the above-mentioned stirring blade, the powdery particles are compressed and aggregated by the shear force generated by the stirring blade. I tend to do it.

  This invention is made in view of this present condition, and it aims at providing the mixing device of the granular material which can control that granular material is compressed and aggregated at the time of mixing.

  One aspect of the present invention for solving the above-mentioned problems is a mixing device of powder and granular material which mixes powder and granular material, and is a funnel which makes an inverted truncated cone-like slope and has a slope including an outlet at the center. And a hopper group comprising a plurality of hoppers disposed above the funnel for storing the granular material and discharging the granular material toward the slope of the funnel, and the hopper group for the funnel And a rotating mechanism for relatively rotating around the axis of the funnel.

According to the above-described mixing apparatus of powdery and granular materials, the powdery and granular materials discharged respectively from the plurality of hoppers to the slope of the funnel are mixed when sliding down on the slope and being discharged from the central discharge port It becomes a state. In this mixing apparatus, the powder particles are not compressed or aggregated by mechanical stress such as a stirring blade. For this reason, it is possible to obtain a mixed powder which suppresses the compression and aggregation of the powder at the time of mixing.
In addition, it is used for formation of the active material layer of the positive electrode of a lithium ion secondary battery, or a negative electrode as "particulate matter" mixed by the above-mentioned mixing apparatus. (The active material granulated body is consolidated to form an active material layer In some cases, a wet active material granule containing an active material and a solvent may be used. Moreover, the active material granulated body used for formation of an active material layer in another type of battery is mentioned. Moreover, the above-mentioned mixing apparatus can also be used for mixing of the granular material used except batteries.

  Also, in the configuration “rotate the hopper group relative to the funnel relative to the funnel axis”, the funnel is fixed while the hopper group is rotated about the funnel axis, or the hopper group is fixed. On the other hand, there is a configuration in which the funnel is rotated about its axis. Alternatively, the funnel and hopper group may be separately rotated, and the funnel and hopper group may be rotated in the same direction with different rotational speeds, or the funnel and hopper group may be rotated in opposite directions.

  Furthermore, it is preferable that the mixing apparatus of the above-mentioned powdery particles be provided as the mixing apparatus of the powdery particles, wherein the plurality of hoppers are disposed equidistantly and equiangularly around the axis of the funnel. .

  In the above-described granular material mixing apparatus, since the plurality of hoppers are respectively disposed equidistantly and equiangularly around the axis of the funnel, the granular material discharged from each hopper has the same height of the slope of the funnel. Falls to the site of For this reason, the granular material discharged | emitted from each hopper can be mixed more uniformly.

  Furthermore, in the powder and granular material mixing apparatus described in any of the above, the funnel is fixed, and the rotating mechanism is configured to rotate the hopper group around the axis of the funnel. Preferably it is a mixing device.

  In the above-described powder and granular material mixing apparatus, the funnel is fixed, and the rotation mechanism rotates the hopper group, so that the rotation mechanism can be simplified as compared with the case where the funnel and the hopper group are rotated together.

It is a perspective view of the mixing device of the granular material concerning an embodiment. It is a graph which shows the bulk density ratio of the granular material after mixing about Examples 1-4 and Comparative Examples 1 and 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the perspective view of the mixing apparatus of the granular material (it is also only hereafter called a "mixing apparatus") 1 which concerns on this embodiment is shown. The mixing apparatus 1 mixes active material granules (powder and particles) PT used for forming an active material layer (active material layer formed by compacting the active material granules) of a lithium ion secondary battery described later. The apparatus is an apparatus, and a plurality of (five in the present embodiment) powder particles PT (PT1, PT2, PT3, PT4, PT5) different in production lot etc. can be mixed. The mixing device 1 comprises a funnel 10, a hopper group 20, a rotation mechanism 30, a container 40 and the like.

  Among them, the funnel 10 is made of metal (specifically, made of stainless steel) and has an axis AX, and includes a slope portion 11, an upper cylindrical portion 13, a lower cylindrical portion 15, and two projecting portions 17 and 17. Among them, the sloped portion 11 is an inverted truncated cone having a circular upper end edge 11c in the upper direction AS in the axial direction AH and a small circular outlet 11h in the lower direction AT in the axial direction AH. is there. The slope portion 11 has a slope 11m extending in the form of an inverted truncated cone on the inner side thereof.

  The upper cylindrical portion 13 is a cylindrical portion having the same diameter as the upper end edge 11 c extending from the upper end edge 11 c of the sloped portion 11 to the upper side AS in the axial direction AH. On the other hand, the lower cylindrical portion 15 is a cylindrical portion having the same diameter as the discharge port 11 h extending downward from the discharge port 11 h of the inclined surface 11 in the axial direction AH. Further, the two projecting portions 17 and 17 each have a rectangular plate shape, and horizontally project radially outward from the outer periphery of the upper cylindrical portion 13. These protrusions 17 and 17 are fixed to a support member (not shown). The funnel 10 is thereby fixed to the support member.

  The powder particles PT (PT 1, PT 2, PT 3, PT 4, PT 5) discharged from the plurality of hoppers 21 (21 a, 21 b, 21 c, 21 d, 21 e) constituting the hopper group 20 described below It enters into the slope 11 through the cylindrical portion 13 and falls to a portion of a predetermined height of the slope 11m. The granular material PT slides down the slope 11m and is discharged from the discharge port 11h, and is further accommodated in a container 40 described later through the lower cylindrical portion 15.

  The hopper group 20 is composed of a plurality of (five in the present embodiment) hoppers 21 (21a, 21b, 21c, 21d, 21e) for storing powdery particles PT (PT1, PT2, PT3, PT4, PT5). . Each of the hoppers 21 a, 21 b, 21 c, 21 d and 21 e is disposed above AS in the axial direction AH of the funnel 10. Each hopper 21 is made of metal (specifically, stainless steel), and includes a slope portion 23, an upper cylindrical portion 25, a lower cylindrical portion 27, and a collar portion 29. Among them, the sloped portion 23 is an inverted truncated cone having a circular upper end 23c in the upper direction AS in the axial direction AH and a lower lower end 23h in the lower direction in the axial direction AH. is there.

  The upper cylindrical portion 25 is a cylindrical portion having the same diameter as the upper end edge 23 c extending from the upper end edge 23 c of the sloped portion 23 upward AS in the axial direction AH. On the other hand, the lower cylindrical portion 27 is a cylindrical portion having the same diameter as the lower end edge 23 h extending downward in the axial direction AH from the lower end edge 23 h of the sloped portion 23. In addition, the collar portion 29 has an annular plate shape, and protrudes horizontally outward from the outer periphery of the upper cylindrical portion 25 in the radial direction. The collar portion 29 is fixed to a disc portion 35 of the rotation mechanism 30 described next. Thereby, each hopper 21 is fixed to the disc part 35 of the rotation mechanism 30. The granular materials PT1, PT2, PT3, PT4, PT5 stored in the hoppers 21a, 21b, 21c, 21d, 21e are discharged from the lower cylindrical portion 27 toward the slope 11m of the funnel 10, respectively.

  The rotation mechanism 30 has a drive unit 31, a rotation shaft 33, and a disk unit 35. Among them, the drive unit 31 is an electric motor and rotates the rotating shaft 33. The rotation axis 33 is vertically disposed such that its axis coincides with the axis AX of the funnel 10. The upper end of the rotary shaft 33 is coupled to the drive unit 31, and the lower end of the rotary shaft 33 is connected to the center of the disc portion 35. The disc portion 35 is in the form of a horizontally expanding disc and has five openings 35 h equidistantly and equiangularly (specifically every 72 degrees) around its center (axis AX of the funnel 10). Is provided.

  The hoppers 21 described above are respectively inserted from the upper AS into the openings 35 h, and the collar portion 29 of the hopper 21 is engaged with and fixed to the peripheral portion of the opening 35 h in the disc portion 35. Thus, the plurality of hoppers 21a, 21b, 21c, 21d and 21e are arranged equidistantly and equiangularly (every 72 degrees in the present embodiment) around the axis AX. In the rotation mechanism 30, when the drive unit 31 is driven, the rotation shaft 33 and the disk unit 35 connected thereto rotate around the axis AX as shown by the arrows in FIG. The hopper group 20 which consists of a plurality of hoppers 21 fixed to can be rotated about the axis AX.

  The container 40 is arranged at the lower AT in the axial direction AH of the funnel 10. The container 40 is made of metal (specifically, stainless steel) and has a bottomed cylindrical shape. The container 40 accommodates the granular material PT mixed in the funnel 10 and discharged from the lower cylindrical portion 15.

Next, a method of mixing the granular material PT using the mixing device 1 will be described. For example, five powdery particles PT (PT1, PT2, PT3, PT4, PT5) different in production lot are prepared. In this embodiment, the active state in the wet state is used to form a positive electrode active material layer (a positive electrode active material layer formed by compacting the active material granules) of the lithium ion secondary battery as the powder particles PT. A granular material was prepared. Specifically, after dry mixing of the positive electrode active material, the conductive material, and the carboxyl group-containing polymer, a solvent (water in the present embodiment) is added thereto so that the moisture content is 30% by weight, and the particle size is 1 mm A wet-state active material granulated body granulated to a certain degree was prepared. In this embodiment, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ as a positive electrode active material, acetylene black (AB) as a conductive material, and polyacrylic acid (PAA) as a carboxyl group-containing polymer Using.

Then, powder particles (active material granules) PT1, PT2, PT3, PT4, and PT5 different in production lot from each other are charged into the five hoppers 21a, 21b, 21c, 21d, and 21e. At the same time, the drive unit 31 of the rotation mechanism 30 is driven to rotate the hopper group 20 around the axis AX of the funnel 10 at 10 to 30 rpm (20 rpm in the present embodiment).
Then, the powder particles PT1, PT2, PT3, PT4, PT5 stored in the hoppers 21a, 21b, 21c, 21d, 21e are little by little from the lower cylindrical portion 27 of the hoppers 21a, 21b, 21c, 21d, 21e. It is discharged into the funnel 10. These granular materials PT 1, PT 2, PT 3, PT 4 and PT 5 fall to a predetermined height of a slope 11 m of the funnel 10 and slide down the slope 11 m to be discharged from the discharge port 11 h. It is in a state of being The granular material PT is discharged toward the container 40 through the lower cylindrical portion 15. Thus, the powder particles PT in which five powder particles PT1, PT2, PT3, PT4, and PT5 different from each other in the production lot are mixed are accommodated in the container 40.

Next, a positive electrode plate using the above-described powder (particles of active material) PT mixed in the mixing apparatus 1 and a method of manufacturing a lithium ion secondary battery using the positive electrode plate will be described. First, the mixed powder PT is supplied to a roll press, and the powder PT is compacted between the rolls and formed into a sheet. Subsequently, the sheet made of the active material granules is pressure-bonded to a predetermined position on one main surface of a separately prepared strip-like aluminum foil and made of a positive electrode current collector foil, to obtain a non-dried positive electrode active material layer. Form. Thereafter, the undried positive electrode active material layer is dried by heating to form a positive electrode active material layer. Further, similarly, the sheet made of the active material granules is pressure-bonded also to the other main surface of the positive electrode current collector foil to form a non-dried positive electrode active material layer, which is heated and dried to obtain a positive electrode active material. Form a layer. Thereafter, the positive electrode plate is pressed by a roll press to increase the density of the positive electrode active material layer. As a result, a positive electrode plate for a lithium ion secondary battery, which has a positive electrode active material layer in which the powder particles PT are compacted, is formed.
Next, the strip-shaped positive electrode plate and a strip-shaped negative electrode plate formed separately are wound via a separator to form an electrode body. Next, a battery is assembled using this electrode body. Thus, a lithium ion secondary battery is obtained.

(Example and Comparative Example)
Next, the results of tests conducted to verify the effects of the present invention will be described. As Examples 1-4, using the mixing apparatus 1 of the above-mentioned granular material, as shown in the following Table 1, changing the number of rotations of the hopper group 20, the above-mentioned granular material (active material granulated body ) PT1, PT2, PT3, PT4 and PT5 were mixed. Specifically, the rotation speed of the hopper group 20 was set to 3 rpm (Example 1), 10 rpm (Example 2), 20 rpm (Example 3), and 30 rpm (Example 4).
In addition, as Comparative Example 2, a manufacturing lot is manufactured using a conventional mixing apparatus of powdery particles, that is, a mixing apparatus in which a stirring blade for stirring and mixing powdery particles is disposed in a container for containing powdery particles. Different granular materials PT1, PT2, PT3, PT4, and PT5 were mixed. Note that Comparative Example 1 will be described later.

  First, bulk density was measured for powder particles PT1, PT2, PT3, PT4, and PT5 different in production lot before mixing. Specifically, in the bottomed cylindrical cup having a volume Vo (ml), using a funnel, the powder PT is introduced until the powder PT overflows from the cup. The spatula is then brought into vertical contact with the upper surface of the cup, and the blade of the spatula is smoothly moved along the upper surface of the cup to remove excess granular material PT that has exceeded the upper surface of the cup. After that, the weight (g) of the cup containing the powder PT is measured, the weight (g) of the powder PT contained in the cup is determined, and this is divided by the volume Vo to obtain the bulk density ( Calculate g / ml). Further, this measurement is repeated three times (n = 3) to calculate an average value of bulk density, and this average value is set as the bulk density of the production lot. Furthermore, the five bulk densities obtained for each production lot were averaged to determine the average bulk density before mixing. This average bulk density was used as the bulk density of Comparative Example 1, and was used as a standard (= 1.00) for obtaining the bulk density ratio.

  Next, with respect to the powder particles PT after mixing in Examples 1 to 4 and Comparative Example 2 described above, the bulk density is measured in the same manner as above, and the bulk density ratio based on the bulk density of Comparative Example 1 is measured. I asked for each. Those with a bulk density ratio of 1.05 or less are "good" (indicated by ○ in Table 1), and those with a bulk density ratio exceeding 1.05 are "poor" (indicated by a × mark in Table 1). evaluated. The results are shown in Table 1 and FIG.

Moreover, about the granular material PT after the mixing in Examples 1-4 and the comparative example 2, the quality determination of the mixing degree (the degree of mixing) was performed, respectively. Since the granular material PT differs in the following solid content rate for every production lot, the solid content ratio of the sample extract | collected from it is disperse | distributed to a large extent, as the granular material PT in which mixing is inadequate. Therefore, it is possible to judge whether the degree of mixing is good or not by examining the variation of the solid fraction for the granular material PT after mixing. Specifically, about 2 g of the mixed powder PT is collected and dried at 160 ° C. for 30 minutes. The weight of the powder particles PT was measured before and after drying, and the solid fraction was calculated by the following equation.
Solid content rate (%) = (weight of powder and granule after drying) / (weight of powder and granule before drying) × 100

  The measurement of the solid fraction is carried out by sampling 10 times each for the powder particles PT after the mixing in Examples 1 to 4 and Comparative Example 2 to determine the variation (standard deviation σ) of the solid fraction. The Then, when the standard deviation σ is σ ≦ 0.3, “good” (indicated by ○ in Table 1), and when 0.3 <σ ≦ 0.7, “good” (Table 1) The case where it was shown by (triangle | delta mark) and (sigma)> 0.7 was judged as "defect" (it shows by * mark in Table 1) in it. The results are shown in Table 1.

As can be seen from Table 1 and FIG. 2, in the powder and granular material PT after mixing in Comparative Example 2, the bulk density ratio is “defective” while largely exceeding the determination criterion (1.05), while Example 1 It is understood that the bulk density ratio of the powder particles PT after mixing of -4 is lower than the judgment standard (1.05) and "good".
The reason is that in Comparative Example 2, the powder particles PT are easily compressed largely by the shear force generated by the stirring blade at the time of mixing, and the powder particles PT are easily aggregated. For this reason, it is thought that bulk density became high in the granular material PT after mixing. On the other hand, in Examples 1 to 4, large mechanical stress due to the stirring blade or the like is not applied to the powder particles PT at the time of mixing. For this reason, it is considered that the powder particles PT are difficult to be compressed at the time of mixing, and the powder particles PT do not easily aggregate.
Further, as can be seen from Table 1, in Example 1, the mixing degree of the powder particles PT is “OK”, and in Comparative Example 2 and Examples 2 to 4 other than that, the mixing degree of the powder particles PT is "It was good. From this result, it can be seen that, even when the granular material PT is mixed using the above-mentioned mixing apparatus 1, the granular material PT can be mixed uniformly.

  As described above, according to the mixing apparatus 1 for powder and granular material, the powder and particulate material PT (PT1) discharged from the plurality of hoppers 21 (21a, 21b, 21c, 21d, 21d) to the slope 11m of the funnel 10 respectively. , PT2, PT3, PT4, and PT5 are mixed when sliding down on the slope 11m and being discharged from the central outlet 11h. In the mixing device 1, the powder particles PT are not compressed or aggregated by mechanical stress of a stirring blade or the like. For this reason, it is possible to obtain a mixed powder PT which suppresses compression and aggregation of the powder PT during mixing.

Furthermore, in the present embodiment, since the plurality of hoppers 21a, 21b, 21c, 21d and 21e are disposed equidistantly and equiangularly around the axis AX of the funnel 10, each hopper 21a, 21b, 21c, 21d, The powder particles PT1, PT2, PT3, PT4, and PT5 discharged from 21e fall on the same height of the slope 11m of the funnel 10. For this reason, the powder particles PT1, PT2, PT3, PT4, PT5 discharged from the hoppers 21a, 21b, 21c, 21d, 21e can be mixed more uniformly.
Further, in the present embodiment, since the funnel 10 is fixed and the rotation mechanism 30 rotates the hopper group 20, the rotation mechanism 30 can be simplified in configuration as compared with the case where the funnel 10 and the hopper group 20 are rotated together. it can.

Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be appropriately modified and applied without departing from the scope of the invention.
For example, in the embodiment, while the funnel 10 is fixed, while rotating the hopper group 20 around the axis AX, the hopper group 20 is rotated relative to the funnel 10, but is not limited thereto. The hopper group 20 may be fixed and the funnel 10 may be rotated about its axis AX. Further, the funnel 10 and the hopper group 20 are separately rotated, and the rotational speeds of the funnel 10 and the hopper group 20 are made different and rotated in the same direction, or the funnel 10 and the hopper group 20 are rotated in the opposite direction. It is also good.

Further, in the embodiment, although the slope 11m of the funnel 10 is a slope without unevenness, it is not limited thereto. For example, a concave groove may be provided on the slope 11m of the funnel 10 in a spiral shape around the axis AX. When such a recessed groove is provided, the powder particles PT can be mixed more effectively.
Further, in the embodiment, the active material granulated body used in the production of the positive electrode active material layer of the lithium ion secondary battery is exemplified as the particulate material PT, but the present invention is not limited thereto. For example, the present invention may be applied to active material granules used for producing positive electrode active material layers of other types of batteries, and active material granules used for producing negative electrode active material layers of battery negative electrodes, or other than batteries It can also be applied to granular materials used in

DESCRIPTION OF SYMBOLS 1 Mixing apparatus of granular material 10 Funnel 11 Slope part 11 h Discharge port 11 m Slope 20 Hopper group 21, 21a, 21b, 21c, 21d Hopper 30 Rotation mechanism 40 Container PT, PT1, PT2, PT3, PT4, PT5 Powder grain Body (active material granules)
AX Axis AS Above AT Below

Claims (1)

It is a mixing apparatus of powdery particles which mix powdery particles,
A funnel having an inverted frusto-conical slope and having a slope including an outlet at the center,
A hopper group comprising a plurality of hoppers disposed above the funnel for storing the particles and discharging the particles toward the slopes of the funnel;
And a rotating mechanism for relatively rotating the hopper group relative to the funnel about the axis of the funnel.

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