JP2012069517A - Manufacturing method of cathode material powder for fine lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing cathode material powder for fine lithium secondary batteries which can prevent the breakage of a mesh screen which is used to classify cathode material powder for source lithium secondary batteries.SOLUTION: A classifier used in a manufacturing method of cathode material powder for source lithium secondary batteries includes a cylindrical mesh screen for screening base powder and a rotor which rotates coaxially with the mesh screen. The rotor has a blade 44 for dispersing the base material provided along the rotation axis thereof. The blade 44 is provided with a tip-curved surface 441 whose corners along the longer direction formed with an opposite face 44x to the mesh screen and a side face 44y and corners on the front and rear sides of rotation have been chamfered and an end-curved surface 442 whose two corners formed with an opposite face 44x to the mesh screen and an end face 44z have been chamfered, allowing shock load on the mesh screen to be reduced.

Description

  The present invention relates to a method for producing a positive electrode material powder for a fine lithium secondary battery, and more specifically, by classifying the positive electrode material powder for a raw material lithium secondary battery containing a coarse powder according to the size using a mesh screen. The present invention relates to a method for producing a positive electrode powder for a secondary battery.

  The positive electrode material powder for a fine lithium secondary battery is a fine powder that becomes a positive electrode material for a lithium secondary battery and does not contain coarse powder due to aggregation, and as a manufacturing method thereof, a raw material lithium secondary battery containing coarse powder due to aggregation A method of removing coarse powder from a positive electrode material powder using a classifier is known (Patent Documents 1 and 2).

  In Patent Document 1, raw materials are mixed, granulated, fired, and pulverized as necessary to obtain a positive electrode powder for a raw material lithium secondary battery, and the powder is pressed against a mesh screen with a blade that rotates at high speed. A method for producing a positive electrode material powder for a fine lithium secondary battery by classifying the positive electrode powder for a raw material lithium secondary battery by using a classifier that sifts by passing is described.

  Patent Document 2 describes a classification device using a polyester screen having an inner diameter of 125 mm, an effective length of 200 mm, and an opening of 45 μm as a mesh screen. Inside this mesh screen, three blades (blades) having a length of 200 mm rotate at a rotational speed of 1400 rpm to classify the positive electrode material powder for a lithium secondary battery. In Patent Document 2, as a problem in such a classification apparatus, when the powder is pressed against the mesh screen by the blade, the blade may damage the mesh screen. Particularly, in the powder used for the positive electrode material, etc. It is mentioned that since the resistance at the time of passing through the mesh screen is large, the load is further increased and is easily damaged.

  Therefore, in the classification device described in Patent Document 2, a blade corresponding to the outer peripheral portion of the rotor has a shape in which the front end and the rear end of the long side portion are chamfered. Since this blade gradually narrows the gap formed between the blade and the mesh screen in the chamfered portion at the rear end of the long side of the blade as it goes forward, the raw material powder captured in the gap is reduced by the blade. It can be transmitted gradually while being moved by being pressed against the mesh screen. Thereby, even if it is a positive electrode material which has a property which is easy to become a lump, the impact load with respect to the rear-end attachment part of a mesh screen can be reduced, and the failure | damage of a mesh screen is reduced.

JP 2006-278031 A JP 2010-64049 A

  However, even if the blade is chamfered at both ends described in Patent Document 2, the impact load on the mesh screen is not sufficiently reduced, and the mesh screen may not be damaged.

  Then, an object of this invention is to provide the manufacturing method of the positive electrode material powder for fine lithium secondary batteries which can prevent the failure | damage of the mesh screen which classifies the positive electrode material powder for raw material lithium secondary batteries.

The method for producing a positive electrode material powder for a fine lithium secondary battery according to the present invention produces a positive electrode material powder for a fine lithium secondary battery by removing the coarse powder from the raw material positive electrode powder for the lithium secondary battery containing the coarse powder. The method includes the following supply step, distribution step, and fractionation step.
Supply step: a blade having a cylindrical mesh screen for screening the raw material lithium secondary battery positive electrode powder and a rotor rotating coaxially with the mesh screen, the rotor being formed in a long plate shape The front part of the main body is directed to the mesh screen, is disposed along the rotation axis of the rotor, and the front part of the blade main body is chamfered at the corner on the front side of the rotation along the longitudinal direction. Supplying the positive electrode material powder for a raw material lithium secondary battery to a classifier provided with a chamfered surface and a blade provided with an end chamfered surface chamfered at each corner in the longitudinal direction .
Classification step: a step of dispersing the positive electrode material powder for a raw material lithium secondary battery on the inner surface of the mesh screen by the blade.
Separation step: a step of separating, by the mesh screen, fine powder having a particle size smaller than the mesh screen and coarse powder.

In the classifying apparatus according to the present invention, an end chamfered surface and a tip chamfered surface are provided on a blade that rotates within a mesh screen. By this end chamfered surface, the raw material lithium secondary battery positive electrode powder smoothly enters between the mesh screen and both ends of the blade, fine powder having a particle size smaller than the mesh screen mesh passes through the mesh screen, Large coarse powder comes out between the mesh screen and the blade and is conveyed in the discharge direction. In addition, the raw material powder smoothly enters between the mesh screen and the blade other than the end portion of the blade by the chamfered surface of the tip portion chamfered on the front side of the rotation, and is classified. Therefore, by reducing the impact load on the mesh screen due to the rotation of the rotor, the raw material powder can be classified efficiently while preventing the mesh screen from being damaged.
In the present specification, the positive electrode material powder for fine lithium secondary batteries obtained by classification is smaller than the mesh screen opening, and “fine powder” is used as the positive electrode material powder for fine lithium secondary batteries. It is called “powder”. In addition, the coarse powder having a large particle size includes not only a particle having a large particle size but also a particle having a large particle size due to aggregation. The fine powder does not contain a coarse powder, but may be aggregated with each other as long as the particle size is small.

  In addition, it is desirable that the chamfered surface of the front part is also formed at a corner on the rear side of the rotation. If the front chamfered surface is provided at the corner on the rear side of the rotation, it will enter between the mesh screen and the blade, and the coarse powder that has not been classified because the particle size is larger than the mesh screen openings will be discharged smoothly. can do.

  The front chamfered surface is preferably a curved surface (hereinafter referred to as a front curved surface). If the tip chamfered surface is a curved surface, the raw material powder can be pressed against the mesh screen by a smooth curved surface, so that the impact load with the mesh screen can be further reduced. Here, the “curved surface” only needs to be formed by a continuous curved surface, and includes a curved surface whose curvature is not constant.

  When the thickness in the rotation direction is T, the front curved surface is formed into a convex arcuate surface by equally cutting away the opposing surface and side surface facing the mesh screen by an arcuate surface having a radius of T / 2. Therefore, the front arc surface and the rear arc surface are connected to each other, and the front curved surface can be easily formed while reducing the impact load on the mesh screen. . The “arc surface” means a curved surface having a curve obtained by cutting off a part of a perfect circle (perfect circle).

  The end chamfered surface is preferably a curved surface (hereinafter referred to as an end curved surface). If the end chamfered surface is a curved surface, the raw material powder can be pressed against the mesh screen by a smooth curved surface, so that the impact load with the mesh screen can be further reduced. Here, when the length of the end curved surface is L in the rotational radius direction, the opposing surface and the end surface facing the mesh screen are evenly cut by the arc surface of the radius L, and the convex arc surface Can be formed.

  In the manufacturing method of the present invention, the blade that disperses the positive electrode material powder for the raw material lithium secondary battery in the mesh screen is provided with the front chamfered surface and the end chamfered surface. Can reduce the impact load. Therefore, according to the present invention, the raw material powder can be efficiently classified while preventing the mesh screen from being damaged.

It is sectional drawing which shows the classification apparatus which concerns on embodiment of this invention. It is a perspective view which shows the braid | blade of the classification device shown in FIG. It is the figure which looked at the longitudinal direction of the braid | blade shown in FIG. FIG. 3 is a side view of the blade shown in FIG. 2. FIG. 3 is a partially enlarged view for explaining a tip curved surface of the blade shown in FIG. 2. FIG. 3 is a partially enlarged view for explaining an end curved surface of the blade shown in FIG. 2. It is a perspective view which shows the modification of the braid | blade shown in FIG. FIG. 6 is a partially enlarged view showing a modified example of the tip curved surface of the blade shown in FIG. 5. It is a partially expanded view which shows the modification of the edge part curved surface of the braid | blade shown in FIG.

A classification device according to an embodiment of the present invention will be described with reference to the drawings.
A classifying apparatus 10 shown in FIG. 1 supplies a positive electrode material for a raw material lithium secondary battery (hereinafter, may be simply referred to as “raw material powder”), and classifies the raw material powder that has been agglomerated and solidified while being crushed. Thus, a powder having a predetermined size is obtained.
As a positive electrode material for a raw material lithium secondary battery supplied as a raw material powder, a composite metal oxide, phosphate, sulfate, borate containing at least one transition metal of Ni, Mn, Co, Fe and Li And silicates and mixtures thereof.
The positive electrode material for a raw material lithium secondary battery is preferably a composite metal oxide represented by the following formula.
Li _x MO ₂
Here, M is one or more elements selected from the group consisting of Ni, Mn, Co, and Fe, and x is 0.9 or more and 1.3 or less. M is preferably two or more elements selected from the above group. In this case, combinations of M include (1) a combination of Ni and Mn, (2) a combination of Ni and Co, and (3) Ni , Mn and Co, (4) Ni, Mn and Fe, and (5) Ni, Mn, Co and Fe. Among these, it is more preferable that M is (3) a combination of Ni, Mn and Co, (4) a combination of Ni, Mn and Fe, and (5) a combination of Ni, Mn, Co and Fe.
The positive electrode material powder for a raw material lithium secondary battery preferably has a BET specific surface area of 2 m ² / g or more and 30 m ² / g or less. When the BET specific surface area is in this range, both the yield of the classification step and the ease of operation of the raw material powder can be achieved. The BET specific surface area of the positive electrode material powder for a raw material lithium secondary battery is more preferably 3 m ² / g or more, and further preferably 5 m ² / g or more. Further, the BET specific surface area of the raw material positive electrode material powder for a lithium secondary battery is more preferably 15 m ² / g or less. The BET specific surface area of the powder can be measured, for example, by drying about 1 g of the powder in a nitrogen atmosphere at 150 ° C. for 15 minutes, and then using “Flowsorb III 2310” manufactured by Micromeritics.

  The classification device 10 includes a housing 20, a mesh screen 30, a rotor 40, and a motor 50.

  The casing 20 includes a main body part 21 for classifying the raw material powder, a supply part 22 to which the raw material powder is supplied, a first discharge part 23 for discharging the classified fine powder, and the fine powder is classified from the raw material powder. And a second discharge unit 24 for discharging the coarse powder selected.

The main body 21 is formed in a cylindrical shape, and the mesh screen 30 and the rotor 40 are disposed therein.
The supply unit 22 is provided on one side of the main body unit 21. The supply part 22 is formed in a cylindrical shape, is coaxially connected to the main body part 21, and has a connection part 22a in which a space for guiding the supplied raw material powder into the main body part 21 is formed. It is formed by a funnel-shaped supply port 22b connected to the upper part of 22a.

The first discharge part 23 is a funnel-shaped outlet having an upper end connected to the lower part of the main body part 21.
The second discharge part 24 is connected to the other side of the main body part 21, and is connected to a connection part 24a formed so as to gradually become thinner toward the opening at the lower end, and a discharge pipe 24b connected to the lower end of the connection part 24a. Formed from.

  The mesh screen 30 is a net-like sieve for classifying the raw material powder. The mesh screen 30 is formed in a cylindrical shape and is arranged coaxially with the main body portion 21. The mesh screen 30 can be made of metal, but nylon (registered trademark), polyester, polyarylate are used in order to prevent the metal fine powder from the mesh screen from being mixed into the fine powder (positive electrode powder for fine lithium secondary battery). It is desirable to use resin such as.

The rotor 40 is connected to a drive shaft (not shown) of the motor 50, and is disposed so as to be inserted through the coaxial center of the connecting portion 22 a of the supply portion 22 and the main body portion 21.
The rotor 40 includes a rotating shaft 41 that transmits rotational driving from the motor 50, a conveying screw 42 that is spirally wound around the rotating shaft 41 and moves the raw material powder to the main body 21, and the mesh screen 30 from the rotating shaft 41. A support portion 43 that is arranged radially toward the front and a blade 44 that is arranged at the tip of the support portion 43 are provided.

  The blade 44 is formed in a long plate shape, is disposed along the rotation shaft 41 of the rotor 40, and has a function of dispersing the raw material powder by rotating on the inner surface of the mesh screen 30. In the classifying device 10 according to the present embodiment, the support portion 43 is provided around the rotation shaft 41 every 120 °, and therefore, three blades 44 are provided in the mesh screen 30. Here, the blade 44 will be described in detail with reference to FIGS.

  As shown in FIGS. 2 to 4, the blade 44 includes a blade body 44a having a tip 440 directed to the mesh screen 30, and a blade body 44a for connecting the blade body 44a to the support portion 43 (see FIG. 1). The leg portion 44b provided at the base portion is integrally formed. In the present embodiment, the blade body 44a has a longitudinal length of about 210 cm, a rotational thickness T of about 0.5 cm, and a rotational radial length L of about 2 cm. Opposing surfaces (hereinafter, this surface is referred to as an opposing surface) are formed as rounded curved surfaces as a whole. The length and thickness of the blade 44 can be adjusted as appropriate according to the amount of processing and the scale of the apparatus. The length in the longitudinal direction is, for example, in the range of 10 to 300 cm, and the length L in the rotational radius direction is, for example, 1. The range of ˜5 cm and the thickness T in the rotational direction may be, for example, a range of 0.1 to 1 cm.

Specifically, the tip portion 440 of the blade 44 is chamfered with a corner portion C1 along the longitudinal direction of the facing surface 44x and the side surface 44y facing the mesh screen 30 and on the front side in the rotational direction F1. A tip chamfer is provided. In the present embodiment, not only the front corner C1 but also the rear corner C2 is provided with a front chamfered surface, and the front chamfered surfaces chamfered at angles C1 and C2 are curved surfaces. The tip curved surface 441 is used.
As shown in FIG. 5, when the thickness in the rotation direction F1 is T, the tip curved surface 441 is an arc having a radius of T / 2 between the opposing surface 44x and the side surface 44y with respect to the chamfering of the corner portions C1 and C2. The surface is cut out evenly to form a convex arc surface. By cutting both corners C1 and C2 equally with a circular arc surface having a radius of T / 2, the leading curved surface 441 is a single circular arc surface in which the circular arc surface on the front side and the circular arc surface on the rear side are connected. It has become. Although the tip curved surface 441 of the present embodiment is an arc surface having a radius T / 2, an effect can be obtained if the corners C1 and C2 are chamfered. It is also possible to do.

Further, the tip portion 440 of the blade 44 is provided with an end chamfered surface in which both corner portions C3 are chamfered by the facing surface 44x facing the mesh screen 30 and the end surface 44z. In the present embodiment, this end chamfered surface is an end curved surface 442 having a curved surface. The end curved surface 442 has a tip curved surface 441 (a circular arc surface of the opposing surface 44x) continuously extending to the tip of the end portion, so that the end contour seen from the opposing surface 44x side has a contour. It is formed in an arc shape.
As shown in FIG. 6, the end curved surface 442 is an arcuate surface having a radius of L between the opposing surface 44x and the end surface 44z with respect to the chamfered corner C3 when the length in the rotational radius direction F1 is L. And is formed into a convex arcuate surface. Although the end curved surface 442 of the present embodiment is an arc surface having a radius L, an effect can be obtained if the corner portion C3 is chamfered, and thus an arc surface having a radius of L / 50 or more is also possible. It is.

A method for producing a positive electrode material powder for a fine lithium secondary battery using the classifier according to the embodiment of the present invention configured as described above will be described with reference to the drawings.
A predetermined amount of raw material powder is supplied to the supply port 22b of the supply unit 22 by a raw material supply device (not shown). The raw material falls from the supply port 22b to the connecting portion 22a. Since the rotating shaft 41 rotated by the rotation drive of the motor 50 is rotating in the connecting portion 22a, the dropped raw material powder is conveyed into the main body portion 21 by the conveying screw 42 provided on the rotating shaft 41 of the rotor 40. Is done.

  In the main body 21, the raw material powder is stirred and scattered by the rotation of the rotor 40, thereby finely pulverizing the aggregated raw material powder. Further, the rotor 40 disperses the raw material powder into the mesh screen 30 while finely pulverizing the raw material powder.

  On the other hand, the blade 44 presses the raw material powder against the mesh screen 30 while rotating along the inner peripheral surface of the mesh screen 30 by the rotation of the rotating shaft 41 of the rotor 40. At this time, the raw materials located at both ends of the blade 44 are sandwiched between the mesh screen 30 and the end of the blade 44. Since the end curved surfaces 442 are provided at both ends of the blade 44, even if coarse powder having a particle size larger than that of the mesh screen 30 and fine powder having a smaller particle size are mixed, they are also aggregated and lump. Even if it becomes, it can be made to enter smoothly between the mesh screen 30 and the end curved surface 442. Then, the fine powder passes through the mesh screen, and the large coarse powder passes through between the mesh screen and the blade and is conveyed to the second discharge unit 24 which is the discharge direction.

In addition, since the blade 44 is provided with the tip curved surface 441, the raw material powder positioned between the ends of the blade 44 first enters from the tip curved surface 441 side on the rotation front side.
The raw material powder is gradually pressed against the mesh screen 30 by the curved front surface 441 that gradually narrows the gap with the mesh screen 30, and the agglomerated raw material is crushed while the fine powder is passed through the mesh screen 30 for classification. To do. Further, the coarse powder does not pass through the mesh screen 30 and falls out between the mesh screen and the blade. When the coarse powder escapes from the rotation rear side of the blade 44, the front curved surface 441 is also provided on the rotation rear side of the blade 44, and the gap is gradually widened so that the coarse powder can be smoothly removed. .

As described above, by providing the blade 44 with the tip curved surface 441 and the end curved surface 442, the raw material powder can smoothly enter the mesh screen 30 and be discharged.
In addition, by providing the tip curved surface 441 and the end curved surface 442, the area of the portion where the distance between the blade 44 and the mesh screen 30 is the smallest is reduced compared to the case where chamfering is not performed. Can do. Therefore, the impact load on the mesh screen 30 can be reduced.

  As described above, the classifying device 10 includes the blade 44 provided with the tip curved surface 441 and the end curved surface 442, so that the raw material powder is smoothly positioned between the blade 44 and the mesh screen 30. Since the impact load on the mesh screen 30 can be reduced, the mesh screen can be prevented from being damaged. Therefore, since the frequency of work stoppage due to breakage of the mesh screen 30 can be reduced, work efficiency can be improved.

As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment. For example, in the present embodiment, the contour of the tip of the end is formed in an arc shape so that the end curved surface 442 gradually becomes narrower toward the tip, but a straight line as shown in FIG. It may be formed automatically. Moreover, since the corner | angular part C3 (refer FIG. 4) should just be chamfered, a part of end curved surface 442 may be a flat surface.
Further, although the tip curved surface 441 and the end curved surface 442 are arcuate surfaces having a predetermined radius, the gap between the facing surface 44x of the blade 44 and the mesh screen 30 is not at the corner C1 on the rotation front side. Any plane or curved surface (curved surface) that gradually decreases and gradually increases at the corner C2 on the rear side of the rotation may be used.

For example, the blade 451 shown in FIG. 8A is provided with a chamfered surface 451a by a flat surface on which the gap with the mesh screen 30 is gradually narrowed on the front side of the rotation. A blade 452 shown in FIG. 8B is provided with a chamfered surface 452a having a chamfered surface 451a shown in FIG. 8A as a curved surface.
In the blade 453 shown in FIG. 8C, not only a chamfered surface 453a is provided on the front side of the rotation but also a chamfered surface 453b is provided on the rear side of the rotation. The connection position between the chamfered surface 453a and the chamfered surface 453b is the center position in the rotation direction F1.
The blade 454 shown in FIG. 8D is provided with chamfered surfaces 454a and 454b in which the chamfered surfaces 453a and 453b of the flat surface of the blade 453 shown in FIG. 8C are curved.
A blade 455 illustrated in FIG. 8E is a modification of the blade 453 illustrated in FIG. In the blade 455, the connection position between the chamfered surface 455a and the chamfered surface 455b is not the center position in the rotation direction F1 of the blade 455, but is slightly shifted backward.
The blade 456 illustrated in FIG. 8F is provided with chamfered surfaces 456a and 456b having curved surfaces as the chamfered surfaces 455a and 455b illustrated in FIG.
A blade 457 shown in FIG. 8G is a modification of the blade 455 shown in FIG. In the blade 457, the connection position between the chamfered surface 457a and the chamfered surface 457b by the flat surface is not the center position in the rotation direction F1 of the blade 457, but is slightly shifted forward.
A blade 458 shown in FIG. 8H is provided with chamfered surfaces 458a and 458b having curved surfaces as the chamfered surfaces 457a and 457b shown in FIG. 8G.
Thus, the front chamfered surface can be a flat surface or an arc surface having a curve obtained by cutting a part of a perfect circle. Moreover, it can also be set as the curved surface from which a curvature changes.

Further, in the blade 461 shown in FIG. 9A, a chamfered surface 461a is formed by a flat surface in which the gap with the mesh screen 30 gradually increases toward the tip. In the blade 462 shown in FIG. 9B, an end curved surface 462a having a small curvature is formed. Further, in the blade 463 shown in FIG. 9C, an end curved surface 463a is formed so that the curvature gradually decreases toward the tip.
As described above, the end chamfered surface can also be a flat surface or an arc surface having a curve obtained by cutting off a part of a perfect circle. Moreover, it can also be set as the curved surface from which a curvature changes.

  The method for producing a positive electrode material powder for a fine lithium secondary battery according to the present invention is obtained by classifying the positive electrode material powder for a fine lithium secondary battery from a raw material positive electrode powder for a lithium secondary battery containing coarse powder by aggregation. It is suitable to obtain.

DESCRIPTION OF SYMBOLS 10 Classifier 20 Case 21 Main-body part 22 Supply part 22a Connection part 22b Supply port 23 1st discharge part 24 2nd discharge part 24a Connection part 24b Discharge pipe 30 Mesh screen 40 Rotor 41 Rotating shaft 42 Conveyance screw 43 Support part 44 Blade 44a Blade body 44b Leg portion 440 Tip portion 441 Tip curve surface 442 End curve surface 44x Opposing surface 44y Side surface 44z End surface 451-458 Blades 451a-458a, 453b-458b Chamfer surface 461-463 Blade 461a Chamfer surface 462a 46 Curved surface 50 Motor C1 to C3 Corner F1 Rotating direction F2 Rotating radial direction L Length T Thickness

Claims (6)

A method for producing a positive electrode powder for a fine lithium secondary battery by removing the coarse powder from a raw material positive electrode powder for a lithium secondary battery containing the coarse powder, including the following supply step, dispersion step and fractionation step The manufacturing method of the positive electrode material powder for fine lithium secondary batteries characterized by the above-mentioned.
Supply step: a blade having a cylindrical mesh screen for screening the raw material lithium secondary battery positive electrode powder and a rotor rotating coaxially with the mesh screen, the rotor being formed in a long plate shape The front part of the main body is directed to the mesh screen, is disposed along the rotation axis of the rotor, and the front part of the blade main body is chamfered at the corner on the front side of the rotation along the longitudinal direction. Supplying the positive electrode material powder for a raw material lithium secondary battery to a classifier provided with a chamfered surface and a blade provided with an end chamfered surface chamfered at each corner in the longitudinal direction .
Classification step: a step of dispersing the positive electrode material powder for a raw material lithium secondary battery on the inner surface of the mesh screen by the blade.
Separation step: a step of separating, by the mesh screen, fine powder having a particle size smaller than the mesh screen and coarse powder.   2. The method for producing a positive electrode material powder for a fine lithium secondary battery according to claim 1, wherein the front chamfered surface of the blade body is also formed at a corner portion on the rear side of the rotation.   The manufacturing method of the positive electrode material powder for fine lithium secondary batteries of Claim 1 or 2 with which the front part chamfering surface of the said blade main body is formed in the curved surface (henceforth a front part curved surface).   The tip curved surface of the blade body has a convex arcuate surface when the thickness in the rotational direction is T and the opposing surface and side surface facing the mesh screen are equally cut by an arcuate surface having a radius of T / 2. The manufacturing method of the positive electrode material powder for fine lithium secondary batteries of Claim 3 currently formed in this.   The positive electrode material powder for a fine lithium secondary battery according to any one of claims 1 to 4, wherein an end chamfered surface of the blade body is formed into a curved surface (hereinafter referred to as an end curved surface). Manufacturing method.   The end curved surface is formed into a convex arcuate surface, with the opposing surface and the end surface facing the mesh screen being evenly cut by an arcuate surface of radius L, where L is the length in the rotational radius direction. The manufacturing method of the positive electrode material powder for fine lithium secondary batteries of Claim 5.

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