JPS6090827A - Permanganic acid process for manufacturing manganese dioxide from manganous salt - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an improved process for producing manganese dioxide from manganous salts (ie, Mn+2). The method includes the step of intimately contacting at least one manganous salt with at least one compound selected from the group consisting of alkali gold M permanganate and ammonium permanganate. The materials brought into intimate contact undergo a two-stage heating schedule to produce electrochemically active manganese dioxide.

BACKGROUND OF THE INVENTION The use of manganese dioxide as a positive electrode active material (depolarizer) in non-aqueous batteries is known.

Easily available manganese compounds that have been used as raw materials for manganese dioxide include salts (tJ--Z:#n, manganous sulfate, manganous carbonate, etc.). The salt is thermally decomposed to produce manganese dioxide. For example, Advanced Ino
rganic Chemlmtry, F. A. Cotton and G. Wilkinson, Interscience - published by John Wiley and Sons (3rd edition 1972)
states in p. 852 that manganese dioxide is produced in principle by heating hexahydrated manganese nitrate in air at a temperature of about 530°C.

However, such a method does not produce highly crystalline beta-form manganese dioxide.

Leading to the production of loose ore. This material is used in Leclanchier-type aqueous solutions, but like other types of manganese dioxide, it generally does not produce satisfactory results.

European Patent No. 27,076 discloses a process for the pyrolysis of manganese tetrahydrate nitrate to form fully beta manganese dioxide. More specifically, this method uses Mn (NO3)2 4H20 at 150”Cf
t+n play l-, I+small? The material was washed with warm distilled water, then with 1% ammonium hydroxide solution, and then the material was heated at 400°C to 40°C.
including drying at a temperature on the order of 50°C. but,
When the moisture-resistant manganese dioxide made using the method of this patent is used in lithium/non-aqueous batteries, these types of batteries do not produce commercially useful efficiencies at temperatures between 21°C and 35°C. The inventor believes that the reason for the poor performance of thermally decomposed manganous nitrate at these temperatures is due to
It is believed that the beta-manganese dioxide produced has a highly crystalline form.

Other approaches have also been adopted to produce electrochemically effective manganese dioxide from manganous salts.

Among the most effective of these approaches are:
There are methods such as those described in US Pat. No. 4,048,027. This consists in producing amorphous electrolytic manganese dioxide ('EMD') by electrolysis of manganese hexahydrate nitrate. EMD is generally known as British Patent No. 1.199,426
and US Pat. No. 4,133,856 to reduce its moisture content and have desirable electrochemical properties for non-aqueous batteries. However, even heat-treated NO absorbs moisture when exposed to ambient humidity, even in a dry room with a relative humidity of 1 to 3 inches, so lithium batteries using NO as the positive electrode material retain their capacity. is difficult to assemble. As is known in the industry, the water in MnO2 reacts with the lithium and/or the non-aqueous electrolyte, resulting in bulging from the initial height of the cell.

U.S. Patent Application No. 451.877, December 31, 1981
U.S. patent application Ser. No. 476.639, filed March 1983, U.S. Pat. There is. This new manganese dioxide has a low area combined with a high degree of amorphism.

More specifically, this type of manganese dioxide has a surface area of less than about 15 m27 g and a d-value of about 3.12 AK when compared to crystalline beta manganese dioxide (I, C, sample FF16). % or less, d value 2.
It has an X-ray diffraction pattern showing a relative intensity of about 8°C or less at 41K, about 65% or less at d value of 1.63K, and about 65% or less at d value of 1.31X. Such properties are believed to be the reason why this type of manganese dioxide has high water absorption resistance and high electrochemical activity. Crystalline beta-manganese dioxide (I, C9Il & 16) is
In Proceedings of the 1st Manganese Dioxide Conference, P, 4, vl, Cleveland, Published by Electrochemical Society, A, Kozawa and R, A/'? 1 written by
, C, refers to sample-6. This type of manganese dioxide occurs in an Xl11 diffraction engraving essentially identical to that reported in ASTM Card 11 24-735.

However, although the manganese dioxide of this patent has desirable properties, the described method for producing such manganese dioxide is limited to the use of manganese hexahydrate nitrate-containing feedstocks.

Manganese hexahydrate nitrate can be prepared by means known in the art (e.g. 'hydrated nitrate of divalent metal', D,
Th1g5l, B, Imelik and M, Pr
ettre.

Bull, 8oe, α-, Fr, 836 (1964)
Although made from commercially available materials, it would be desirable to provide a process by which manganese dioxide of this type and/or manganese dioxide with similar properties can be produced from a wide range of raw materials. Also, patent application No. 4
The process described in No. 76.639 tends to produce manganese dioxide with a very low surface area of about 1.2 square meters or less per duram unless carefully monitored. This low surface area appears to adversely affect the pulsing performance of this manganese dioxide at ambient and lower temperatures, i.e., 21° C. and below. By slightly increasing the surface area of the manganese dioxide produced, i.e., to more than about 3.0 square meters/gram, the pulse performance is improved to an acceptable level without significantly adversely affecting the water absorption resistance of the manganese dioxide. It seems likely that it will be possible.

It is therefore an object of the present invention to provide a process for the production of manganese dioxide having a relatively low surface area combined with a high degree of amorphism, in which a wide variety of raw materials can be used.

Another object of the invention is to provide a method for producing manganese dioxide having a relatively low surface area combined with a high degree of amorphousness, which manganese dioxide exhibits desirable e-rus properties in non-aqueous batteries at room temperature. It is on offer.

The above objects and additional objects will become apparent from the examples below.

SUMMARY OF THE INVENTION The present invention provides (a) at least one manganous salt in intimate contact with at least one compound selected from the group consisting of ammonium permanganate and alkali metal permanganates. (b) bringing the manganous salts/permanganates brought into contact with each other in step (a) above to a temperature of 120°C to 180°C, preferably about 150°C, in an oxygen-containing gas; (c) heating the material produced in step (b) above in an oxygen-containing gas at a temperature of about 10°C to heating at a temperature of about 300°C, preferably about 250°C, until at least about 85% of the manganese present as oxide is present as MnO2.

The water absorption rate of a particular form of manganese dioxide appears to be related to the surface area of this manganese dioxide.

However, a certain minimum surface area appears to be desirable to obtain the desired pulsing performance at or below ambient temperatures (ie, about 21° C.). Although some embodiments of the present invention may yield manganese dioxide with a slightly higher surface area (e.g., up to about 50 m2/g), preferred embodiments of the process of the present invention have a surface area of about 3 m27g to 15 m2
/ g of manganese dioxide. Therefore, manganese dioxide made by the process of the present invention appears to have desirable water absorption resistance with acceptable Norms performance.

Furthermore, compared to manganese dioxide, which has a highly crystalline structure,
It is theorized that manganese dioxide with a more disordered structure has higher electrochemical properties. It is therefore believed that the manganese dioxide produced by the method of the present invention has a relatively amorphous structure and is therefore highly suitable for use in electrochemical cells.

Terms used in this specification 1 Manganous salt (
5alt)' refers to a compound containing manganese in a +2-valent state. Representative examples of manganous salts used in the method of the invention are manganous nitrate, manganous chloride, manganous sulfate, manganous carbonate, and mixtures thereof. However, care must be taken when manganous chloride is used since chlorine gas is released during the formation of manganese dioxide.

The manganous salt raw material can be in an aqueous phase or in an anhydrous state. The preferred manganous salt source is a 50% aqueous solution of manganous nitrate because of its commercial availability and the desirability of the resulting product properties.

Typical examples of alkali metal permanganates used are potassium permanganate, lithium permanganate and sodium permanganate. Ammonium permanganate may also be used, but the use of this compound is undesirable due to its explosive properties.

Alkali metal permanganate and/or ammonium permanganate (2) Weight ratio of anhydrous alkali metal permanganate and/or ammonium permanganate to anhydrous tg-manganate (about 1 to 20% by weight in -s, preferably is added in an amount of about 5 to about 10% by weight based on the manganese salt raw material.

The method of the invention is typically carried out as follows. The manganous salt raw material is brought into intimate contact with the alkali metal permanganate by any means known to those skilled in the art, such as milling, rolling, mixing, etc.

(Due to its explosive nature, ammonium permanganate is not included within the description of this representative embodiment of the invention. However, if it is desired to use this compound, it is suitable for alkali metal permanganate.) The preferred method of making such close contact when manganese is used as a raw material is to melt the manganese hexahydrate nitrate (used exactly in the same manner as salt). The method consists of heating a mixture of this compound and an alkali metal permanganate to a sufficient temperature, i.e., about 100° C. The mixture is then allowed to cool to form a solid mass, and the mass is ground. , forming a manganese/alkali metal permanganate material in intimate contact with the nitric acid.The melting must be carried out in an oxygen-containing gas.

The heating step of the process of the invention is typically carried out in a closed reactor to control the moisture in the reactor. The reactor is equipped with an inlet for pumping oxygen or oxygen-containing gas.

The reactor must also have a degassing port through which gases released by the reaction can escape. The degassing means must also include an oil-filled trap to prevent back diffusion of air or water vapor.

Place the manganous salt/alkali metal permanganate material in intimate contact into the reactor and begin a continuous flow of dry or wet oxygen-containing gas.

In this case, the term 1 dry oxygen-containing gas' means a gas that has not been bubbled into water before entering the reactor.

Conversely, the term 1 wet oxygen-containing gas' means a gas that is bubbled through water before entering the reactor. The reactor is then heated, preferably slowly, to about 20°C to about 180°C, preferably about 150°C.

Such heating step occurs for about 1 to 4 hours, although longer or shorter times can be used.

When the desired temperature is reached, the reaction system is maintained within this temperature range until substantially complete conversion of the manganous salt to the manganese dioxide-containing compound is achieved. This conversion is typically indicated by the formation of a black mass. Typically, such temperature is maintained for about 1 to 4 hours, preferably about 2 hours. As will be apparent to those skilled in the art, this period will likely depend on the temperature selected, reaction patch size, composition of the raw materials, and other similar factors. The oxygen-containing gas introduced into the reactor during this isothermal period can be a wet gas or a dry gas.

After the first heating stage described above is completed, the reaction product of this stage is further heated to about 10°C to about 300°C, preferably about 250°C. This second temperature increase, when carried out as a single step, is preferably carried out for about 15 minutes to about a minute, and most preferably for about an additional minute. This second heating step can occur in the presence of wet or dry oxygen-containing gas.

When the desired temperature of this second heating stage is reached, the amount of manganese present as an oxide in the manganese dioxide-containing material produced in the first heating stage is reduced such that approximately 85% of this material is present as MnO2. The reaction is maintained at the temperature for a period sufficient to alter the properties of the reaction mixture.Typically, this time will be from about 1 hour to about 4 hours, preferably about 2 hours.

Care must be taken to ensure that this high temperature holding period is not too long. Otherwise, the product will be too crystalline and the electrochemical percentage will be undesirable. The crystallinity of the manganese dioxide during this second heating stage is monitored by periodically performing X# diffraction analysis on a sample of the produced manganese dioxide. The product is then allowed to cool to room temperature. This cooling is preferably carried out in dry oxygen-containing gas.

The produced crude manganese dioxide is preferably washed with an acidic solution to remove alkali metal ions.

Most preferably, in many cases of the manganous salts of the present invention, the acid used for such washing corresponds to the anion of the manganous salt used. That is, when manganous chloride is used as a raw material, hydrochloric acid is preferably used, when manganese sulfate is used, sulfuric acid is preferred, and when manganous nitrate is used, nitric acid is preferred. In the case of manganous carbonate, hydrochloric acid, nitric acid or sulfuric acid can be used. This pickling is preferably carried out at an elevated temperature of about ω°C to about 70°C. The pickled manganese dioxide is washed with water and then dried by heating at a temperature of about 25°C to about 150°C.

Manganese dioxide produced by the inventive method exhibits desirable electrochemical properties, including desirable pulsability at ambient temperatures. Also, many embodiments of the present invention are 15 m27
Produce manganese dioxide with a surface area of less than g. Therefore, the manganese dioxide should be dried in a dry tank (approximately 50 p
pm to about 100 ppm moisture content), but can be operated in a drying chamber (having a relative humidity of about 1 to about 3 inches).

EXAMPLES The following examples are intended to further illustrate the invention and are not intended to limit the scope of the invention in any way.

Example 1 Fixed bar tightly combined manganese hexahydrate nitrate/
Potassium permanganate was made as follows. (Capital) weight% (19.24g) of Mn(No3)2.6H
20 and weighted i1% (3 g) of KMnO4 were placed in a 500 ml conical flask equipped with a 20 rubber stopper. One neck of this flask is connected to the oxygen tank and the other neck forms the gas outlet (these weight percentages are
(based on anhydrous Mn(NO3)2:KMnO4 ratio).

Boil the mixture for 10 minutes until the hydrated manganese nitrate has melted.
Heat at 0°C. Almost no KMnO4 dissolved in the molten manganese hexahydrate nitrate, and the solidified arms were cooled, removed from the flask, and ground.

This milled mixed material was placed into the same flask assembly as above. The temperature of this flask is raised from room temperature to 150° C. over a period of about 10 minutes. During this period, dry oxygen is pumped directly from the tank into the flask at a flow rate of about 1 cubic foot per hour.

When the temperature reaches 150°C, the system is heated to this temperature by about 2
Holds time. The temperature was then increased to about 250°C over half an hour. During this entire period (i.e., the 2-hour hold at 150°C and the subsequent temperature ramp to 250°C), dry oxygen flows directly from the tank into the flask at a flow rate of approximately 1 cubic foot per hour. I continued to do so.

The temperature of the flask was maintained at 250° C. for 2 hours and then allowed to cool to room temperature. During this period, dry oxygen was continuously pumped into the reactor.

The crude manganese dioxide obtained in this way was heated to 70°C.
Washed with 10% aqueous nitric acid, filtered, and washed several times with water. The final product was dried by heating for 16 hours at a temperature of about 25°C to about 150°C.

As a result of elemental analysis, this product was found to be 9% of the total weight of the product.
8.63% by weight manganese dioxide,
The manganese dioxide has a molecular formula of MnO2, o.

It had In the formula MnOx, %X' is defined as the total manganese content in valent form. The surface area of this product, determined by the BET method, was 10.7 m2/g. The method is J, Am, Chem.

See, Vol. 60. pp, 309-31
6 (193B) by S. Solnauer, P. Emmett and E. Teller.

Example 2 Using the apparatus used in Example 1, manganous hexahydrate nitrate was used as the manganous salt, and the ratio of manganese nitrate to potassium permanganate was 90:10. Several grams of manganese dioxide were produced using the same method as in Example 1 except for this.

This product was determined to be 94.92% by weight of manganese dioxide based on its total weight, and this manganese dioxide was Mn0
It had 1.6g. Its surface area was determined to be 6.70 square meters/gram.

Example 3 Several grams of manganese dioxide were produced in the same manner as in Example 2 using the equipment used in Example 1 but using trihydrate lithium permanganate instead of potassium permanganate. did. The ratio of hexahydrated manganese nitrate to trihydrated lithium permanganate is Mn(NO3)2
:90:10 based on LiMnO4. This product has a temperature of 88.8531 fm based on its total weight.
% manganese dioxide. The manganese dioxide has the formula Mn01, gg. The surface area is 3.15 square meters/gram and there are four constant breath flames.Example 4 Using the apparatus of Example 1, the ratio of manganese hexahydrate nitrate to trihydrate lithium permanganate is 95:5 (Mn(
Several grams of manganese hexahydrate nitrate were treated using a method similar to Example 3, except that NO3)2: LiMnO4 based). The product was determined to contain 93.36% by weight of manganese dioxide, based on its total weight, and this manganese dioxide had the formula Mno 599.

Example 5 8.25 g KMnO4 and 150 ml 50% Mn
(No. 3) 2 in the air in an evaporating dish for about 13
Heated at 0°C until oxidation occurred. then 150 in the air
℃ for 2 hours, followed by heating at 250℃ for 2 hours.

Obtaining MnO2 containing 3.06% potassium,
This was treated with a 10% nitric acid solution, washed with distilled water, and then dried at 110° C. overnight. The analysis is 97 for all 1f.
．． It showed a product containing 38% manganese dioxide. This manganese dioxide has the formula Mn0□,98. The surface area was 5.1 square meters/gram.

X-ray analysis showed a /guirolucite pattern with achromatic saturation as defined in U.S. Pat. No. 476,639.

Example 6 About 40 units of 1,3-dioxolane, about I volume of 1,2-dimethoxyethane, about I volume of 3-methyl-2-oxazolidone, and about 0.2 units of dimethyliso xazole, 1 mol/liter of solvent Li
The material of Example 1 was introduced into a cell filled with a non-aqueous electrolyte containing CF3SO3. The contents of the battery were 40 milligrams of lithium as a negative electrode, about 1.5 ml of the electrolyte described above, a nonwoven polypropylene separator with a portion of the electrolyte adsorbed, and 86.2% by weight MnO2 (as in Example 1). produced) and 8.5% by weight
of graphite and 2.11j! % acetylene blank and 0.35 g of a positive electrode mix consisting of 3.2% by weight polytetrafluoroethylene binder.

Tests were conducted at 21°C and 35°C until a 2-zelt cutoff was reached. A load resistance of 30,000 ohms (0,1 mA/em2 positive electrode density) was used for continuous discharge, and 2 seconds for 2 seconds once every 3 days for A pulse discharge.
A weight load of 50 ohms was used. This MnO2 is 2
It showed an efficiency of 83.7% (1 electron reduction pace) up to 2-zero cutoff at 1°C, and an efficiency of 94.0% at 35°C.

The Arus behavior of manganese dioxide produced by the method of the present invention was approximately equivalent to that exhibited by heat treated kosher at these temperatures.

Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] 1. (al) At least one manganous salt is closely combined with at least one compound selected from the group consisting of alkali gold JpA permanganate and ammonium permanganate. (b) the intimately contacted manganous salt/permanganate material made in step (a) until substantially complete conversion of the manganous salt to the manganese dioxide-containing material; 120℃ to approx. 18℃
(c) heating the material produced in step (b) in an oxygen-containing gas such that at least about 90% of the manganese present as an oxide is present as MnO2; A method for producing manganese dioxide, comprising the steps of: 2. The alkali metal permanganate and/or ammonium permanganate are used at a weight ratio of anhydrous alkali gold Xi manganate and/or ammonium permanganate to anhydrous manganous salt, from about 1 to 1 Approximately 2
2. The method of claim 1, wherein a lid in the range of -0 weight is brought into contact with the manganese salt. 3. The alkali metal permanganate and/or ammonium permanganate is used in an amount of about 5% by weight to about 5% by weight based on the weight ratio of anhydrous alkali metal permanganate and/or ammonium permanganate to anhydrous manganous salt. 10
2. The method of claim 2, wherein an amount in the range of - by weight is contacted with the manganese salt. 4. The method of claim 1, wherein the temperature in step (b) is maintained for about 1 hour to about 4 hours. 5. The method of claim 4, wherein the temperature of step (a) is maintained for about 1 hour to about 4 hours. 6 mother 1 haiku/+, lmebe 1 toge ne 51^nr ma wo nine
, ν for about 2 hours. 7. The method of claim 6, wherein in step (,) the temperature is raised to 250°C and held at this temperature for about 2 hours. 8. The method of claim 1, wherein the manganous salt is selected from the group consisting of manganous nitrate, manganous chloride, manganous sulfate, manganous carbonate, and mixtures thereof. 9. The method of claim 8, wherein the manganous salt is a 50% water bath solution of manganese nitrate. 10. The method of claim 1, wherein the alkali metal permanganate is selected from the group consisting of sodium permanganate, lithium permanganate, potassium permanganate and mixtures thereof. 11. The g-manganese salt is manganous hexahydrate, and in step (a), this compound and the permanganate are combined at a temperature sufficient to melt the manganese hexahydrate. The manganese hexahydrate nitrate is brought into intimate contact with the alkali metal permanganate and/or ammonium permanganate by heating the molten manganese material with salt, cooling the molten manganese material into a mass, and crushing this material. A method according to claim 1, wherein the contacting method is as claimed in claim 1.