Method for manufacturing composite positive electrode active material powder

Abstract

To provide a method for efficiently manufacturing high-quality composite positive electrode active material powder.SOLUTION: A manufacturing method includes mixing a powder of a positive electrode active material and a powder of a coating agent in a mixing device to obtain a composite positive electrode active material powder in which particle surfaces of the powder of the positive electrode active material are coated with the coating agent, the mixing device includes a container and two stirring blades for stirring the powder of the positive electrode active material and the powder of the coating agent in the container, the distance between each of the two stirring blades and the bottom surface of the container is 0 to 5.40 mm, the distance between each of the two stirring blades and the side surface of the container is 0 to 4.36 mm, the distance between one of the two stirring blades and the other of the two stirring blades is 4.11 to 9.00 mm, and during the mixing, a shear force applied by the two stirring blades to the powder of the positive electrode active material and the powder of the coating agent is 60 N or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a composite cathode active material powder.

Background Art

[0002] In an all-solid-state battery using a sulfide solid electrolyte, there has been a problem that the sulfide solid electrolyte deteriorates or the interfacial resistance between the cathode active material and the sulfide solid electrolyte is high due to direct contact between the cathode active material and the sulfide solid electrolyte.

[0003] To improve this, for example, Patent Document 1 discloses a method for manufacturing a composite cathode active material powder in which a powder of a cathode active material and a powder of an oxide solid electrolyte are mechanically mixed by mechanochemical treatment to coat the particle surface of the powder of the cathode active material with the oxide solid electrolyte.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Not limited to the case of coating the particle surface of the powder of the cathode active material with the oxide solid electrolyte, when the powder of the cathode active material and the powder of the coating agent are mechanically mixed to coat the particle surface of the powder of the cathode active material with the coating agent, desired quality and efficiency may not be obtained.

[0006] The present disclosure has been made to solve the above problems. An object of the present disclosure is to provide a method for manufacturing a composite cathode active material powder capable of efficiently manufacturing a high-quality composite cathode active material powder.

Means for Solving the Problems

[0007] The method for manufacturing the composite positive electrode active material powder of the present disclosure is as follows: Mix the powder of the positive electrode active material and the powder of the coating agent in a mixing device to obtain a composite positive electrode active material powder in which the particle surface of the powder of the positive electrode active material is coated with the coating agent. including The mixing device includes a container for storing the powder of the positive electrode active material and the powder of the coating agent, and two stirring blades for stirring the powder of the positive electrode active material and the powder of the coating agent in the container. The distance between each of the two stirring blades and the bottom surface of the container is 0 to 5.40 mm, the distance between each of the two stirring blades and the side surface of the container is 0 to 4.36 mm, and the distance between one of the two stirring blades and the other of the two stirring blades is 4.11 to 9.00 mm, and when mixing the powder of the positive electrode active material and the powder of the coating agent, the shear force applied to the powder of the positive electrode active material and the powder of the coating agent by the two stirring blades is 60 N or less.

Advantages of the Invention

[0008] According to the present disclosure, by setting the distances between each of the two stirring blades and the bottom surface and the side surface of the container, and the distance between one stirring blade and the other stirring blade within a predetermined range, the shear force applied to the powder of the positive electrode active material and the powder of the coating agent can be made equal to or less than a predetermined value. As a result, according to the present disclosure, it is possible to provide a method for manufacturing a composite positive electrode active material powder that can efficiently manufacture a high-quality composite positive electrode active material powder.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the method for producing the composite positive electrode active material powder of the present disclosure (hereinafter referred to as "the production method of the present disclosure") will be described. The following embodiments do not limit the production method of the present disclosure.

[0011] Although not bound by theory, the findings obtained by the inventor regarding the reason why high-quality composite positive electrode active material powder can be efficiently produced by the production method of the present disclosure will be described.

[0012] When powder is loaded into a powder layer shear force measuring device and a pushing load is applied to the powder, the shear force applied to the powder can be measured. For the measurement, for example, a powder layer shear force measuring device NS-S500 manufactured by NanoSeeds Co., Ltd. can be used.

[0013] FIG. 1 is a graph showing the relationship between the pushing load applied to the powder of the coating agent and the shear force applied to the powder of the coating agent obtained using a powder layer shear force measuring device. FIG. 2 is a graph showing the relationship between the pushing load applied to the mixed powder of the positive electrode active material and the coating agent and the shear force applied to the mixed powder of the positive electrode active material and the coating agent obtained using a powder layer shear force measuring device.

[0014] From FIG. 1, it can be understood that in the powder of the coating agent, when the pushing load applied to the powder of the coating agent is increased, the shear force also increases, but when the shear force exceeds 60 N, the increase in the shear force becomes slow. And in the powder of the coating agent to which a shear force exceeding 60 N is applied, some particles in the powder of the coating agent are significantly spread (plastically deformed).

[0015] On the one hand, as can be seen from FIG. 2, in the mixed powder of the positive electrode active material and the coating agent, when the pressing load applied to the mixed powder is increased, the shear force also increases. However, as in the case shown in FIG. 1, it can be understood that the increase in the shear force does not become sluggish. And in the mixed powder to which a shear force exceeding 60 N is applied, the significantly extended (plastic deformed) coating agent entraps a plurality of particles of the positive electrode active material powder, forming coarse particles.

[0016] In the coarse particles, since the significantly extended (plastic deformed) coating agent entraps a plurality of particles in the positive electrode active material powder, it cannot be said that the coating agent is uniformly coated on the surface of each particle of the positive electrode active material powder, and the quality of the composite positive electrode active material powder deteriorates. Also, due to the formation of coarse particles, the efficiency of uniformly coating the coating agent on the surface of each particle of the positive electrode active material powder also decreases.

[0017] From these facts, the inventor has found that in order to efficiently produce a high-quality composite positive electrode active material powder by mixing the positive electrode active material powder and the coating agent powder, the shear force applied to the positive electrode active material powder and the coating agent powder may be 60 N or less. Also, when mixing the positive electrode active material powder and the coating agent powder using an actual mixing device instead of a powder shear force measuring device, the inventor has found that to apply a shear force of 60 N or less, it is sufficient to mix using a predetermined mixing device under predetermined conditions.

[0018] The constituent requirements of the method for manufacturing the composite positive electrode active material powder of the present disclosure, which are completed based on the findings described so far, will be described below.

[0019] 《Method for Manufacturing Composite Positive Electrode Active Material Powder》 The method for manufacturing the composite positive electrode active material powder of the present disclosure mixes the positive electrode active material powder and the coating agent powder in a mixing device to obtain a composite positive electrode active material powder in which the particle surface of the positive electrode active material powder is coated with the coating agent. Hereinafter, the positive electrode active material, the coating agent, the composite positive electrode active material, and the mixing device will be described.

[0020] (Positive Electrode Active Material) The material of the positive electrode active material is not particularly limited. Examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganate (LiMn2O4), lithium nickel cobalt manganate (NCM), LiCO 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, lithium nickel cobalt aluminate (NCA; LiNi x Co y Al z O2), Li 1+x Mn 2-x-y M y O4 (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn), such as hetero-element substituted Li-Mn spinel having a composition represented by the above, but not limited thereto.

[0021] (Coating agent) The coating agent is not particularly limited, but a solid electrolyte can be used. Examples of the material of the solid electrolyte include, but are not limited to, sulfide solid electrolytes, oxide solid electrolytes, etc. When a sulfide solid electrolyte is used as the separator layer of the battery, the coating agent is preferably an oxide solid electrolyte.

[0022] Examples of the sulfide solid electrolyte include, but are not limited to, sulfide-based amorphous solid electrolytes, sulfide-based crystalline solid electrolytes, or argyrodite-type solid electrolytes. Examples of the sulfide solid electrolyte include Li2S-P2S5-based (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 (Li 13 GeP3S 16 , Li 10 GeP2S 12 , etc.), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x , etc., or combinations thereof, but not limited thereto.

[0023] As the oxide solid electrolyte, Li7La3Zr2O 12 , Li 7-x La3Zr 1-x Nb x O 12 , Li 7-3x La3Zr2Al x O 12 , Li 3x La 2 / 3-x TiO3, Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, Li3PO4, Li 3+x PO 4-x N x (LiPON) etc., or combinations thereof can be mentioned, but are not limited thereto.

[0024] As the oxide solid electrolyte, in addition to the above, for example, phosphates containing any one or more elements of Al, Sc, Ti, V, Y, Zr, Nb, Ca, Sr, Ba, Hf, Ta, Cr, Mo, W and Li, and composite oxides represented by the general formula Li x AO (A is B, C, Al, Si, P, S, Ti, Zr, Nb, Mo, Ta, La, Zr, or W, and x and y are positive numbers.) can be mentioned. Among them, phosphate compounds are preferable, and particularly NASICON-type Li 1+x Al x Ti 2-x P3O 12 (0≦x≦1, preferably x = 0.3) is preferable.

[0025] The sulfide solid electrolyte and the oxide solid electrolyte may be glass or crystallized glass (glass ceramics).

[0026] (Composite positive electrode active material) The content ratio of the coating agent in the composite positive electrode active material is not particularly limited, but it may be 0.01 mol% or more, 0.02 mol% or more, 0.04 mol% or more, 0.06 mol% or more, 0.08 mol% or more, or 0.10 mol% or more, and may be 4.00 mol% or less, 3.5 mol% or less, 3.0 mol% or less, 2.5 mol% or less, or 2.0 mol% or less.

[0027] The coating agent is preferably coated on the particle surface of the positive electrode active material powder with a uniform film thickness, but may have a non-uniform film thickness as long as the effects of the manufacturing method of the present disclosure are not inhibited. The film thickness of the coating agent may be, for example, 0.1 nm or more, 0.5 nm or more, or 1 nm or more, and may be 100 nm or less, 80 nm or less, 60 nm or less, or 40 nm or less.

[0028] (Mixing device) Figure 3 is a schematic diagram showing an example of the mixing device used in the manufacturing method of the present disclosure.

[0029] The mixing device 100 includes a container 10 for storing the powder of the positive electrode active material (not shown) and the powder of the coating agent (not shown). Further, the mixing device 100 includes two stirring blades 20a and 20b for stirring the powder of the positive electrode active material and the powder of the coating agent in the container 10. Each of the two stirring blades 20a and 20b is connected to a rotating shaft 30a and 30b. The rotating shafts 30a and 30b are connected to a power source (not shown), and each of the rotating shafts 30a and 30b rotates and performs a planetary motion (revolution), so that each of the two stirring blades 20a and 20b rotates and performs a planetary motion (revolution). Thereby, the powder of the positive electrode active material and the powder of the coating agent are stirred.

[0030] During stirring, the powder of the positive electrode active material and the powder of the coating agent flow between each of the stirring blades 20a and 20b and the bottom surface 12 of the container 10, between each of the stirring blades 20a and 20b and the side surface 14 of the container 10, and between one stirring blade 20a and the other stirring blade 20b. This flow applies a shearing force to the powder of the positive electrode active material and the powder of the coating agent.

[0031] If the shearing force is 60 N or less, the formation of coarse particles can be suppressed. From this perspective, the shearing force may be 50 N or less, 40 N or less, 30 N or less, 28 N or less, 26 N or less, 24 N or less, 22 N or less, or 20 N or less. On the other hand, if the shearing force is 5 N or more, 10 N or more, or 15 N or more, it does not take an excessive amount of time to apply the shearing force to the powder of the positive electrode active material and the powder of the coating agent.

[0032] In order to apply a shearing force of the magnitude as described above, the intervals Lxa and Lxb between each of the stirring blades 20a and 20b and the bottom surface 12 of the container 10, the intervals Lya and Lyb between each of the stirring blades 20a and 20b and the side surface 14 of the container 10, and the interval Lz between one stirring blade 20a and the other stirring blade 20b may be as follows. Lxa and Lxb are the shortest distances between each of the stirring blades 20a and 20b and the bottom surface 12 of the container 10, Lya and Lyb are the shortest distances between each of the stirring blades 20a and 20b and the side surface 14 of the container 10, and Lz is the shortest distance between one stirring blade 20a and the other stirring blade 20b.

[0033] Lxa and Lxb may be 0 mm or more, 0.20 mm or more, or 0.40 mm or more, and may be 5.40 mm or less, 5.00 mm or less, 4.00 mm or less, 3.00 mm or less, or 2.00 mm or less.

[0034] Lya and Lyb may be 0 mm or more, 1.00 mm or more, or 2.00 mm or more, and may be 4.36 mm or less, 4.00 mm or less, or 3.00 mm or less.

[0035] Lz may be 4.11 mm or more, 4.50 mm or more, or 5.00 mm or more, and may be 9.00 mm or less, 7.00 mm or less, or 5.00 mm or less.

Examples

[0036] Hereinafter, the manufacturing method of the present disclosure will be described more specifically with reference to examples. Note that the manufacturing method of the present disclosure is not limited to the conditions used in the following examples.

[0037] As the powder of the positive electrode active material and the powder of the coating agent, the powder of the oxide solid electrolyte was prepared, and these powders were mixed using the mixing device 100 shown in FIG. 3. Lxa, Lxb, Lya, Lyb, and Lz were changed as shown in Table 1, respectively.

[0038] In any of Examples 1 to 8, it was confirmed that the formation of coarse particles was suppressed and high-quality composite positive electrode active material powder could be efficiently produced.

[0039]

Table 1

Explanation of Signs

[0040] 10... container, 12... bottom surface, 14... side surface, 20a, 20b... stirring blades, 30a, 30b... rotating shafts, 100... mixing device

Claims

【Claim 1】 Mixing the powder of the positive electrode active material and the powder of the coating agent in a mixing device to obtain a composite positive electrode active material powder in which the particle surface of the powder of the positive electrode active material is coated with the coating agent, including, the mixing device being, a container for storing the powder of the positive electrode active material and the powder of the coating agent, two stirring blades for stirring the powder of the positive electrode active material and the powder of the coating agent in the container, being provided with, the distance between each of the two stirring blades and the bottom surface of the container being 0 to 5.40 mm, the distance between each of the two stirring blades and the side surface of the container being 0 to 4.36 mm, the distance between one of the two stirring blades and the other of the two stirring blades being 4.11 to 9.00 mm, and when mixing the powder of the positive electrode active material and the powder of the coating agent, the shearing force applied to the powder of the positive electrode active material and the powder of the coating agent by the two stirring blades being 60 N or less, A method for manufacturing a composite positive electrode active material powder.

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