JPH029722A - Production of manganese oxide powder - Google Patents

Abstract

PURPOSE:To produce spherical manganese oxide powder having excellent filling ability and dispersibility by spraying an aq. soln. of manganese compd. to make droplets and by heating the droplets. CONSTITUTION:The aq. soln. of manganese compd. having 50-400g/l concn. is prepd. by dissolving manganese compd. (e.g., manganese nitrate, manganese chloride) in pure water, etc. At that time, lithium compd. such as lithium hydroxide, lithium carbonate may be dissolved in the soln. and in the case, the concn. of manganese is about 50-300g/l. Then, the aq. soln. of manganese compd. is sprayed with a sprayer to make droplets and the droplets are heated at about 150-900 deg.C for about 1-5min to product the spherical manganese oxide powder. Thereby, the spherical manganese oxide useful as active material for a positive electrode of lithium secondary battery, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing manganese oxide powder, and more specifically, for example, to improve filling properties and dispersion of manganese oxide powder, which is used as a positive electrode active material for lithium secondary batteries. The present invention relates to a method for producing spherical manganese oxide powder with excellent properties.

[Prior art and problems to be solved by the invention] Currently,
In order to obtain manganese oxide powder, the general method is to mechanically crush the amorphous manganese oxide obtained by oxidizing manganese oxide or manganese compound obtained by electrolysis, and then classify and collect the dust. It is.

However, the above-mentioned method has drawbacks such as not only complicated steps but also a low yield of collected manganese oxide, a large amount of impurities, and low filling properties because the shape is not spherical but amorphous.

Since the manganese oxide powder that has been crushed and classified in this way has an amorphous shape, it has poor filling properties, and when used as a positive electrode material for lithium secondary batteries, its performance is limited.
Further, there were also problems such as high manufacturing cost and a large amount of impurities as mentioned above.

In view of the above circumstances, the present invention aims to provide a method for producing manganese oxide powder that is spherical and has good filling properties without degrading quality and physical properties.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted intensive research and found that by spraying an aqueous solution of a manganese compound into droplets using a sprayer and thermally decomposing them in the air. The present invention was achieved based on the finding that the obtained spherical manganese oxide powder has superior filling properties and dispersibility compared to manganese oxide powder obtained by conventional manufacturing methods.

That is, the present invention provides spraying 17 of an aqueous solution of a manganese compound.
, a method for producing spherical manganese oxide powder, characterized by heating the obtained droplets.

The manufacturing method of the present invention will be explained below.

In the present invention, a manganese compound is used as a starting material. Manganese nitrate and manganese carbonate are mainly used as the manganese compound, but manganese sulfate, manganese chloride, etc. may also be used. These raw manganese compounds are dissolved in pure water or the like to obtain an aqueous solution of the manganese compound. The manganese concentration at this time is preferably about 50 to 400 g/i.

Further, in the present invention, a lithium compound such as lithium hydroxide, lithium carbonate, or lithium nitrate may be dissolved in the aqueous solution of the manganese compound.

The manganese concentration at this time is preferably about 50 to 300 gz#. By adding such a lithium compound, lithium ions can most easily diffuse into the manganese oxide.

In the present invention, this aqueous solution of the manganese compound is sprayed using a sprayer to obtain droplets. The sprayer used here is not particularly limited, but examples include, for example, an ultrasonic sprayer.

Next, the obtained droplets are heated to obtain spherical manganese dioxide or a composite oxide of manganese and lithium. Appropriate heat treatment conditions are 150-900''C11-5 minutes.

The first device used for heating such droplets is
A heating device as shown in the figure is shown by way of example. In the figure, 1 is an ultrasonic humidifier, 2 is a reaction tube, 3 is an electric furnace, 4 is a temperature controller, 5 is a collector, 6 is water, and 7
indicates a suction fan, respectively.

[Effects] Although the effects of the present invention have not been fully elucidated, they are presumed to be due to the following factors.

■ Since there is no sintering and only spherical particles are dispersed, the filling property is good.

■ Uniform composition with few impurities.

In the present invention, a highly pure spherical manganese oxide with excellent filling properties and dispersibility can be obtained by the synergistic effect of these respective actions.

[Examples] The present invention will be specifically described below based on Examples and Comparative Examples.

Example 1 Manganese nitrate was dissolved in pure water to give a manganese concentration of -64,
5g/J aqueous solution was obtained, and this aqueous solution was sprayed at a spray rate of 1
The droplets obtained were heated at 500°C for 1 minute using the apparatus shown in Figure 1, and the micrograph shown in Figure 2 (
A spherical manganese oxide powder as shown in (X 3000) was obtained.

The physical properties of the obtained manganese oxide powder are shown in Table 1, and the particle size and filling degree are shown in Table 2.

Note that the particle size distribution in Table 1 is determined by n1 using a Nikkiso particle size analyzer Microtrac SPA type, and the particle size is sieved from the smallest particle size to 10150.
The particle size just before reaching 90% of each weight is displayed.

Further, the degree of filling of powder is considered to be a factor affecting battery performance, and was measured by the following method.

Filling degree - Particle size by light transmission method (μ) / Particle size by air transmission method (μ) In the above formula, the particle size by light transmission method is determined by light transmission method using a Shimadzu centrifugal sedimentation type 11 particle size distribution analyzer. This is the particle size at the center value of the measured particle size distribution, and the particle size measured by the air permeation method is the particle size at the center value of the particle size distribution measured by the air permeation method using a Shimadzu powder specific surface measurement device model 5S-100. It is.

Example 2 Droplets were obtained in the same manner as in Example 1, and heated at 700°C for 1 minute using the heating device shown in Figure 1, resulting in a droplet as shown in the micrograph Q (X 3000) in Figure 3. A spherical manganese oxide powder was obtained.

The physical properties of the manganese oxide powder obtained in the same manner as in Example 1 are shown in Table 1, and the particle size and filling degree are shown in Table 2.
Each is shown in the table.

Example 3 A lithium hydroxide aqueous solution was added to a solution of manganese carbonate dissolved in excess concentrated nitric acid, and the manganese concentration was -84.5 g/
J, an aqueous solution with a lithium concentration of -3.3 g/j was obtained,
This aqueous solution was sprayed at a spray rate of IItl/min, and the resulting droplets were heated at 500°C for 1 minute using the above-mentioned device to form spherical manganese oxides as shown in the micrograph (X 3000) in Figure 4. A powder was obtained.

The physical properties of the manganese oxide powder obtained in the same manner as in Example 1 are shown in Table 1, and the particle size and filling degree are shown in Table 2.
Each is shown in the table.

Comparative Example 1 After mechanically pulverizing electrolytic manganese dioxide obtained by electrolytic method, it was classified and the micrograph g (x
3000) was obtained.

The particle size and filling degree of the manganese oxide powder obtained in the same manner as in Example 1 are shown in Table 2.

As is clear from Tables 1 and 2, the manganese oxide powders of Examples 1 to 3 have a small particle size distribution and a large filling degree compared to Comparative Example 1.

Moreover, as shown in FIGS. 2 to 5, the manganese oxide powder obtained in Comparative Example 1 has an irregular shape, whereas the manganese oxide powder of Examples 1 to 3 has a spherical shape.

Therefore, it can be seen that the manganese oxide powders of Examples 1 to 3 have excellent filling properties and dispersibility.

[Effects of the Invention] As is clear from the above description, the manganese oxide powder obtained by the production method of the present invention is spherical and has excellent filling properties and dispersibility, so it can be used as a positive electrode active material for lithium secondary batteries, etc. It can be used for a wide range of applications.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a heating device used in the heating process according to the present invention, and FIGS. 2 to 5 are example 1
3 and Comparative Example 1 are shown respectively. 1; Sonic humidifier 2; Reaction tube 3: Electric furnace 4: Temperature converter 5: Collector 6: Water 7: Suction fan troller Patent applicant: Mitsui Mining & Mining Co., Ltd., agent, patent attorney Tatsuo Ito, agent, patent attorney Tetsuya Ito* 2 FXIJ < az :3ooO(e
＞Figure (Aritutei/3000 times 3rd meat (#1 bow 3α℃ times) Figure (Shukase: 3COO times) Procedural amendment (method) % formula % 1. Indication of the case 1988 Patent Application No. 159188 2, Name of the invention Method for manufacturing manganese oxide powder 3, Relationship to the case of the person making the amendment Patent applicant address 2-1-1 Nihonbashi Muromachi, Chuo-ku, Tokyo Name (618) Mitsui Kinzoku Mining Co., Ltd. Representative Kosanbu Mashima 4, Agent 105 Address 2-8-1-6 Toranomon, Minato-ku, Tokyo Target of amendment: “Brief description of drawings in the specification” 7. Contents of amendment 1. Correct “Microphotograph indicating “Microphotograph” on page 10, line 20 of the specification.” to “Particle structure.”

Claims (1)

[Claims] 1. A method for producing manganese oxide powder, which comprises heating droplets obtained by spraying an aqueous solution of a manganese compound. 2. The method for producing manganese oxide powder according to claim 1, wherein a lithium compound is dissolved in the aqueous solution of the manganese compound.