JP5625880B2 - Method for producing positive electrode slurry and apparatus for producing positive electrode slurry - Google Patents

Description

  The present invention relates to a method for producing a positive electrode slurry and an apparatus for producing a positive electrode slurry.

  In recent years, the development of electric vehicles (EV), hybrid electric vehicles (HEV), and fuel cell vehicles (FCV) has been promoted against the background of the increasing environmental protection movement. As these motor driving power sources, secondary batteries that can be repeatedly charged and discharged have attracted attention. A secondary battery generally includes a positive electrode in which a positive electrode active material layer is formed on a positive electrode current collector, a negative electrode in which a negative electrode current collector is formed with a negative electrode active material layer, and a positive electrode and a negative electrode. Is provided in a battery case.

  The positive electrode active material layer is composed of a positive electrode slurry applied to a positive electrode current collector. The positive electrode slurry is produced by mixing a powder material composed of a positive electrode active material, a conductive aid, and the like and then kneading with a liquid solvent.

  Patent Document 1 discloses a technique for improving the dispersibility of the powder material in the positive electrode slurry. While kneading the powder material and the solvent, a shearing force is applied to the kneaded product, and the powder particles of the powder material are refined to improve dispersibility.

JP 2000-353516 A

  In the above prior art, since the work of applying a shearing force to the powder particles whose surface is covered with a liquid film is performed, it is possible to apply a sufficient shearing force required for the refinement of the powder particles. It is difficult and a lot of time is spent adjusting the powder particle size. For this reason, there is a problem that it is difficult to shorten the working time of the manufacturing work of the positive electrode slurry. In addition, it is difficult to uniformly apply a shearing force to the powder particles, and the powder particle size becomes non-uniform, which causes a problem in that the quality of the positive electrode slurry varies.

  The present invention has been made to solve the above-mentioned problems, and shortens the work time of the kneading work for kneading the powder material and the solvent used for the positive electrode active material layer of the battery, and thus the work for producing the positive electrode slurry. An object of the present invention is to provide a positive electrode slurry manufacturing method and a positive electrode slurry manufacturing apparatus that can reduce working time and suppress variations in the quality of the positive electrode slurry.

The manufacturing method of the positive electrode slurry which concerns on this invention includes the adjustment process which adjusts the powder particle size of the powder material used for the positive electrode active material layer of a battery with a dry system. Furthermore, it includes a kneading step of kneading the powder material with the adjusted particle size and the solvent by a wet method. In the dry method, a shearing force is applied while applying a compressive force to the powder particles of the powder material held in the mixing space formed so as to increase in size from the upstream side to the downstream side in the powder material supply direction. This is due to the mortar mechanism. In the adjusting step, the powder particles of the powder material are crushed by rotation of a blade provided in the stone mill mechanism.

  According to the present invention, after the powder particles of the powder material are crushed by the dry method and the particle size is adjusted, the kneading operation by the wet method is performed. There is no need to do it sometimes. Therefore, it is possible to shorten the work time of the kneading work and, in turn, shorten the work time of the manufacturing process of the positive electrode slurry, as compared with the case where the method of adjusting the particle size of the powder particles by the wet method is adopted. Furthermore, the particle size of the powder particles can be homogenized, and variations in the quality of the positive electrode slurry can be suppressed.

It is a figure which simplifies and shows the manufacturing apparatus of the positive electrode slurry which concerns on embodiment. It is a figure for demonstrating the stone mill mechanism which concerns on embodiment, and is a figure which expands and shows the broken-line part II of FIG. It is the elements on larger scale for demonstrating the stone mill mechanism which concerns on a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  The constituent material of the positive electrode slurry according to the embodiment will be described.

  The powder material 50 is a composition material of the positive electrode slurry used for the positive electrode active material layer of the battery, and is in a state before the solvent is added. The powder material 50 contains a positive electrode active material and a conductive additive for enhancing electrical conductivity in the positive electrode active material layer. In the drawing, the positive electrode active material powder particles included in the powder material 50 are indicated by reference numeral 51, and the conductive auxiliary agent powder particles included in the powder material 50 are indicated by reference numeral 53 (see FIG. 2). ).

Examples of the positive electrode active material include lithium-transition metal composite oxides used for lithium ion secondary batteries, Li-Mn composite oxides such as LiMn ₂ O _4, and Li—Ni composite oxides such as LiNiO ₂ . Li-Co based composite oxides such as LiCoO ₂ and Li-Fe based composite oxides such as LiFePO ₄ .

  Examples of the conductive aid include a carbon material. Examples of the carbon material include acetylene black, vulcan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon, hard carbon, and fullerene.

  As the powder material 50, for example, a powder material having powder particles having a particle size of about D10 to D90 and a submicron to about 40 microns can be prepared. When using such a powder material, it is desirable to adjust to a particle size of about submicron to about 20 microns by using an adjusting mechanism 20 described later at about D10 to D90.

  The solvent 60 to be kneaded with the powder material 50 may appropriately include, for example, NMP (N-methylpyrrolidone) as a slurry viscosity adjusting solvent, PVDF (polytetrafluoroethylene) as a binder, and the like.

  An apparatus for producing a positive electrode slurry will be described.

  Referring to FIGS. 1 and 2, positive electrode slurry manufacturing apparatus 10 includes adjustment mechanism 20 that adjusts the powder particle size of powder material 50 by a dry method, and powder material 50 and solvent 60 with adjusted powder particle size. And a kneading mechanism 40 for kneading them by a wet method. An inlet 11 for introducing the powder material 50 into the apparatus is provided on the upstream side where the manufacturing operation proceeds. On the downstream side where the manufacturing operation proceeds, a discharge port 13 for sending the powder material 50 including the powder particles 51 and 53 after the particle size adjustment to the kneading mechanism 40 is provided.

  The powder material 50 input from the input port 11 passes through the material mixing zone 30 including the adjusting mechanism 20. When passing through the material mixing zone 30, the powder particles 51 and 53 are crushed by the adjusting mechanism 20 to adjust the particle diameters of the powder particles 51 and 53. When the powder material includes two or more different constituent materials, an operation of adjusting the particle diameter and an operation of mixing the powder particles of the powder material are performed. The powder material 50 that has passed through the material mixing zone 30 is sent to the kneading mechanism 40 through the discharge port 13.

  The adjusting mechanism 20 is configured by a stone mill mechanism capable of applying a shearing force while applying a compressive force to the powder particles 51 and 53 of the powder material 50. The stone mill mechanism includes a rotatable rotating shaft 21 (the rotating direction of the rotating shaft 21 is indicated by an arrow a in FIG. 1) and a plurality of rotating blades 23 (see FIG. 1) spaced apart from each other in the axial direction of the rotating shaft 21. Equivalent to a blade). The rotating shaft 21 is attached so as to penetrate the rotating blade 23.

  Between the plurality of rotating blades 23, fixed blades 25 attached to the main body portion of the positive electrode slurry manufacturing apparatus 10 are installed. A recess (mixing space) 29 that holds the powder particles 51 and 53 is defined between the rotating blade 23 and the fixed blade 25.

  The powder material 50 fed into the material mixing zone 30 is poured little by little between the rotary blade 23 and the fixed blade 25 and is held between the blades 23 and 25. A compressive force acts on the powder particles 51 and 53 with the inflow of the powder material 50 sequentially fed (indicated by an arrow p in FIG. 2). When the rotating shaft 21 is rotated and the rotating blade 23 is rotated in this state, a shearing shear force is applied to the powder particles 51 and 53. The powder particles 51 and 53 are crushed by the applied shear force.

  It is desirable that the mixing space formed between the rotating blade 23 and the fixed blade 25 is designed to have a maximum of about 10 zones. By carrying out such a design, it is possible to suppress an increase in the size of the entire apparatus while satisfactorily exerting the function of crushing the powder particles 51 and 53.

  An adjustment member 27 for adjusting the distance between the blades 23 and 25 is provided on the side surface of the rotating blade 23 and the side surface of the fixed blade 25. By installing the adjusting member 27, the holding amount of the powder material 50 held between the blades 23 and 25 is adjusted. By adjusting the holding amount, the compressive force acting on the powder particles 51 and 53 can be adjusted. The interval between the rotary blade 23 and the fixed blade 25 can be adjusted as appropriate according to the particle size of the powder material 50. For example, the particle size of the powder particles 51 and 53 of the powder material 50 can be adjusted to 100 microns or less. It is desirable to design the dimensions so that they are possible.

  The kneading mechanism 40 includes a mixer 41 that mixes the powder material 50 and the liquid solvent 60, and a supply unit 43 that supplies the solvent 60. The mixer 41 employs a known planetary mixer used for mixing and stirring the powder and the solution. The powder material 50 that has passed through the material mixing zone 30 and the solvent 60 are kneaded by the mixer 41, and the powder material 50 is dispersed in the solvent 60, so that a positive electrode slurry can be produced.

  Next, the manufacturing method of the positive electrode slurry which concerns on embodiment is demonstrated.

  Referring to FIG. 1, a powder material 50 containing a positive electrode active material and a conductive auxiliary agent is charged from a charging port 11. The powder material 50 is poured into the material mixing zone 30.

  Referring to FIG. 2, the powder material 50 is pushed into a concave / convex recess 29 formed between the rotating blade 23 and the fixed blade 25. A compressive force acts on the powder particles 51 of the positive electrode active material and the powder particles 53 of the conductive additive.

  The rotating shaft 21 is rotated with the powder material 50 held between the blades 23 and 25. The rotating blade 23 rotates as the rotating shaft 21 rotates. While mixing the powder particles 51 of the positive electrode active material and the powder particles 53 of the conductive additive, a shearing shear force is applied to each of the powder particles 51 and 53. The powder particles 51 of the positive electrode active material and the powder particles 53 of the conductive additive are crushed to reduce the particle size. In order to adjust the particle size of the powder particles 51 and 53 of the powder material 50 by a dry method, a particle size adjustment method by a wet method in which shear force is applied to the powder particles whose surface is covered with a liquid film is adopted. Compared with the case where it does, the shear force required for crushing can be provided easily. Furthermore, a shearing force can be equally applied to the powder particles 51 and 53, and the particle size can be homogenized.

  In a conductive additive made of a carbon material or the like, carbons constituting powder particles are connected in a granular form and in a chain form to form a network (chain structure) to form an aggregate (duck) state. In addition, a chain network may be formed between the aggregate and the powder particles of the positive electrode active material, and these may be integrated to form a larger aggregate. When the aggregate is formed, the mixing property of the powder particles of the positive electrode active material and the powder particles of the conductive additive is lowered, and the quality of the positive electrode slurry is deteriorated. Further, it is necessary to crush the chain structure during the kneading operation for kneading with the solvent, and it is necessary to spend more time for the kneading operation.

  In the particle size adjustment method using a stone mortar mechanism, mechanical energy capable of applying a shearing force while applying a compressive force to the powder particles 51 of the positive electrode active material and the powder particles 53 of the conductive additive is provided. Can act. Thus, the chain structure between the conductive auxiliary agent powder particles 53 and the chain structure between the conductive auxiliary agent powder particles 53 and the positive electrode active material powder particles 51 can be easily crushed. The powder particles 53 of the auxiliary agent can be evenly dispersed in the positive electrode active material.

  Next, the powder material 50 including the powder particles 51 and 53 with the adjusted particle size and the solvent 60 are kneaded by the mixer 41. The powder material 50 is dispersed in the solvent 60 to obtain a positive electrode slurry. Since the chain structure of the powder material 50 is crushed in advance, the dispersibility of the powder particles 51 and 53 in the solvent 60 can be improved.

  After crushing the powder particles 51 and 53 of the powder material 50 by the dry method and adjusting the particle size, a kneading operation by the wet method is performed, and therefore, a large shearing force for crushing the powder particles 51 and 53 is applied. There is no need to carry out the kneading operation. For this reason, the working time required for the kneading work can be shortened.

  When kneading is carried out while adjusting the particle size of the powder material by a wet method using a conventionally known solvent containing a binder component, the solid content after slurrying is generally in the range of about 60 ± 5%. Adjusted. On the other hand, after crushing and crushing in a powder state by a dry method, if the powder material is dispersed in a solvent and slurried, the solid content after slurrying is in the range of about 70 ± 5%. It becomes possible to adjust. Thus, since solid content after slurrying can be increased as compared with conventionally known methods, it is possible to disperse while applying greater shear in wet-type kneading.

  As described above, according to the above-described embodiment, the powder particles 51 and 53 of the powder material 50 are crushed by the dry method to adjust the particle size, and then the powder particles 51 and 53 are crushed to perform the kneading operation by the wet method. Therefore, it is not necessary to perform the work of applying a shearing force for the kneading operation. Therefore, it is possible to shorten the work time required for the kneading work, and in turn shorten the work time of the production work of the positive electrode slurry. Furthermore, the particle size of the powder particles can be homogenized, and variations in the quality of the positive electrode slurry can be suppressed.

  Further, while mixing the positive electrode active material powder particles 51 and the conductive additive powder particles 53 by a dry method, the chain structure between the conductive additive powder particles 53 and the conductive auxiliary powder particles 53 and the positive electrode active material are mixed. The chain structure between the powder particles 51 of the substance can be crushed. Since the conductive additive powder particles 53 are uniformly dispersed in the positive electrode active material, the dispersibility of the powder particles 51 and 53 in the positive electrode slurry can be improved. As a result, the quality of the positive electrode slurry can be further improved, and the working time of the kneading operation can be further shortened.

  Further, by utilizing a stone mortar mechanism, mechanical energy capable of applying a shearing force can be applied to the powder particles 51 of the positive electrode active material and the powder particles 53 of the conductive additive while applying a compressive force. it can.

  Further, by rotating the blade 23 while the powder material 50 is held between the blades 23 provided in the stone mill mechanism, the powder particles 51 and 53 of the powder material 50 are crushed and formed between the powder particles 51 and 53. The chain structure can be crushed simultaneously. Thereby, the working efficiency of manufacturing work can be improved.

  Further, by installing the adjusting member 27 on the rotating blade 23, the holding amount of the powder material 50 held between the blades 23 can be adjusted. By adjusting the holding amount, the compressive force acting on the powder particles 51 and 53 can be adjusted.

<Modification>
Next, a modification of the above-described embodiment will be described. In the description, the same members as those in the above-described embodiment are denoted by the same reference numerals, and a part of the description is omitted.

  As shown in FIG. 3, in the modification, the size of the adjusting member 27 installed on the side surface of the rotating blade 23 and the size of the adjusting member 27 installed on the side surface of the fixed blade 25 are different for each blade. Thereby, a plurality of types of concave and convex recesses 29 having different sizes are formed between the rotary blade 23 and the fixed blade 25.

  The size of the adjusting member 27 located on the downstream side (left side in the figure) is larger than the adjusting member 27 located on the upstream side (right side in the figure) in the supply direction of the powder material 50. The shearing force applied in the depression 29 located on the upstream side is larger than the shearing force applied in the depression 29 located on the downstream side.

  The particle diameters of the powder particles 51 and 53 are adjusted to be relatively small on the upstream side. Since the size of the recess 29 gradually increases as going downstream, a smooth flow of the powder particles 51 and 53 is formed. In this way, by adjusting the size of the recess 29 formed in the material mixing zone 30 using the adjusting member 27, the particle size of the powder particles 51 and 53 can be adjusted efficiently and in a short time. it can. Furthermore, the number of blades in the material mixing zone 30 can be reduced, and the space of the material mixing zone 30 can be reduced.

  The above-described embodiments can be changed as appropriate.

  The shape of the blade, the number of blades, the clearance between the blade and the device body, the blade rotation speed, the jacket temperature of the device, etc. are not particularly limited, as long as compressive force and shear shear force can be applied to the powder particles of the powder material. It is possible to design appropriately.

  The shape, installation position, and the like of the adjustment member are not particularly limited to those described in the embodiment, and can be changed as appropriate.

  The constituent materials contained in the powder material and the solvent are not particularly limited to those described in the embodiment. It can be appropriately changed according to the type of battery to which the positive electrode slurry is applied.

10 Positive electrode slurry manufacturing equipment,
20 Adjustment mechanism (stone mill mechanism),
21 rotation axis,
23 Rotating blade (blade),
25 fixed blade,
27 adjustment member,
29 Dimple,
30 material mixing zone,
40 kneading mechanism,
41 mixer,
43 supply section,
50 powder material,
51 powder particles of a positive electrode active material,
53 Powder particles of conductive aid,
60 Solvent.

Claims (3)

An adjustment step of adjusting the powder particle size of the powder material used for the positive electrode active material layer of the battery by a dry method;
A kneading step of kneading and a solvent wherein the powder material powder particle size was adjusted by a wet method, only including,
The dry method is a method in which a compressive force is applied to the powder particles of the powder material held in the mixing space formed so as to increase in size as it goes from the upstream side to the downstream side in the powder material supply direction. This is due to the mortar mechanism that gives power,
The said adjustment process crushes the powder particle of the said powder material by rotation of the blade provided in the said stone mill mechanism, The manufacturing method of the positive electrode slurry characterized by the above-mentioned . The powder material includes at least a positive electrode active material and a conductive additive,
2. The positive electrode slurry according to claim 1, wherein the adjusting step crushes a chain structure of powder particles of the conductive additive while mixing the positive electrode active material and the conductive additive. Production method.   An adjustment mechanism for adjusting the powder particle size of the powder material used for the positive electrode active material layer of the battery by a dry method;
  A kneading mechanism for kneading the powder material having a adjusted particle size with the solvent by a wet method,
  The adjustment mechanism is a mortar mechanism that applies a shear force while applying a compressive force to the powder particles of the powder material,
  The stone mortar mechanism includes a rotatable rotating shaft, a plurality of blades spaced apart from each other in the axial direction of the rotating shaft, and an interval between the plurality of blades to adjust the powder material supply direction. An adjusting member that forms a mixing space between adjacent blades, the dimension of which increases as it goes from the upstream side to the downstream side, and
  An apparatus for producing a positive electrode slurry, wherein the powder particles of the powder material are crushed by the rotation of the plurality of blades accompanying the rotation of the rotating shaft in a state where the powder material is present in the mixing space.

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