JP2016108212A - Manganese dioxide and manganese dioxide mixture, and method for producing the same and use for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manganese dioxide mixture that has excellent electrochemical reactivity and excellent high-rate discharge properties when used as a positive electrode material for an alkali battery, and also provide a manganese dioxide for obtaining the manganese dioxide mixture.SOLUTION: A manganese dioxide is characterized in that the volume of a pore with a pore diameter of more than 5 nm and 100 nm or less is 0.07 cm/g or more. A manganese dioxide mixture is characterized by comprising the manganese dioxide and an electrolytic manganese dioxide. There are also provided a method for producing the same and a use for the same.SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to manganese dioxide and manganese dioxide mixtures and methods for producing them, and more specifically, for example, manganese dioxide mixtures used as positive electrode active materials in manganese dry batteries, particularly alkaline manganese dry batteries, and methods for producing the same. And its use, manganese dioxide used in a manganese dioxide mixture and a method for producing the same, and manganese dioxide adsorbent use.

  Manganese dioxide is known as a positive electrode active material of, for example, a manganese dry battery or an alkaline manganese dry battery, and has an advantage of being excellent in storage stability and being inexpensive. In particular, alkaline manganese batteries using manganese dioxide as the positive electrode active material have excellent discharge characteristics under heavy loads, so they are widely used in electronic cameras, portable tape recorders, portable information devices, game machines, and toys. In recent years, the demand has been increasing rapidly.

  However, the alkaline manganese battery has a problem that the substantial discharge capacity is greatly impaired because the utilization rate of manganese dioxide, which is a positive electrode active material, decreases as the discharge current increases and cannot be used in a state where the discharge voltage decreases. was there. In other words, when an alkaline manganese battery is used in a device that uses a large current (high rate discharge), the charged positive electrode active material manganese dioxide is not fully utilized, and the usable time is short. It was.

  Thus, an excellent manganese dioxide capable of exhibiting a high capacity and a long life under high-rate discharge conditions in which a large current is taken out in a short time, that is, manganese dioxide excellent in so-called high-rate discharge characteristics has been desired.

  So far, in order to improve the high-rate discharge characteristics, it has been studied to produce electrolytic manganese dioxide having a high potential (hereinafter referred to as alkali potential) when measured with a mercury / mercury oxide reference electrode as a standard in a 40 wt% KOH aqueous solution. (Patent Documents 1 to 3, Non-Patent Document 1).

Further, also for the high-rate discharge characteristics improved, the volume of the fine pore area of 3~5nm discloses that the use of electrolytic manganese dioxide of 0.011cm ³ / g from 0.005 cm ³ / g (Patent Document 4 ). Furthermore, as a method for increasing such a fine pore volume, a method of synthesizing electrolytic manganese dioxide under high temperature and pressure exceeding 100 ° C. is also disclosed (Patent Document 5).

  However, even with these electrolytic manganese dioxide having a high alkali potential and electrolytic manganese dioxide having a large fine pore volume, the high rate discharge characteristics are not sufficient.

On the other hand, it is disclosed that manganese dioxide, for example, δ-type MnO ₂ synthesized by reaction of permanganate ion (Mn ⁷⁺ ) and manganese ion (Mn ²⁺ ) is used as an adsorbent (Patent Document 6, 7).

  However, sufficient adsorption characteristics have not been obtained yet.

JP 2007-141463 A US Pat. No. 6,527,941 JP 2009-135067 A JP 2009-289728 A JP 2005-520290 Gazette JP 2008-18312 A JP 2009-254932 A

Furukawa Electric Times, No. 43, p. 91-102 (May 1967)

  An object of the present invention is manganese dioxide used as a positive electrode active material of an alkaline manganese dry battery particularly excellent in high-rate discharge characteristics, and particularly a manganese dioxide mixture having an unprecedented large pore volume in an alkaline electrolyte and its A manufacturing method and its use are provided.

As a result of intensive studies on manganese dioxide used as a positive electrode active material for alkaline manganese dry batteries, the present inventors have found that the volume of pores having a pore diameter of more than 5 nm and not more than 100 nm is 0.07 cm ³ / g or more. It has been found that a manganese dioxide mixture in which manganese dioxide and electrolytic manganese dioxide are mixed becomes a positive electrode material having excellent high-rate discharge characteristics, and the present invention has been completed. That is, the present invention is characterized by containing manganese dioxide, a manganese dioxide characterized by having a pore diameter of more than 5 nm and a pore diameter of 100 nm or less being 0.07 cm ³ / g or more, the manganese dioxide, and electrolytic manganese dioxide. Manganese dioxide mixture.

  Hereinafter, the present invention will be described in more detail.

The manganese dioxide of the present invention has an extremely large mesopore with a volume of pores having a pore diameter of more than 5 nm and not more than 100 nm (hereinafter sometimes referred to as “mesopore”) of 0.07 cm ³ / g or more. Features. When the mesopore volume is less than 0.07 cm ³ / g, the high-rate discharge characteristics are insufficient. In order to obtain particularly good high-rate discharge characteristics, 0.1 cm ³ / g or more is preferable, and 0.15 cm ³ / g or more is more preferable.

The manganese dioxide of the present invention has a pore volume with a pore diameter of 2 nm or more and 5 nm or less (hereinafter sometimes referred to as “micropore”) of less than 0.004 cm ³ / g in order to perform battery reaction more efficiently. It is preferable that it is 0.003 cm ³ / g or less, particularly preferably less than 0.001 cm ³ / g.

As will be described later, the manganese dioxide of the present invention can be obtained by treating a low-valent Mn oxide such as Mn ₃ O ₄ under concentrated sulfuric acid and performing a disproportionation reaction.

  The manganese dioxide mixture of the present invention contains the manganese dioxide of the present invention and electrolytic manganese dioxide.

The manganese dioxide mixture of the present invention has a very large volume in which the manganese dioxide of the present invention contained therein has a very large volume of pores (mesopores) having a pore diameter of more than 5 nm and not more than 100 nm of 0.07 cm ³ / g or more. This is based on the finding that a mixture obtained by mixing manganese dioxide with electrolytic manganese dioxide becomes a positive electrode material having extremely excellent high rate characteristics in an alkaline manganese dry battery.

  The manganese dioxide mixture of the present invention does not particularly limit the ratio of the manganese dioxide of the present invention to the electrolytic manganese dioxide, but in order to maintain a higher bulk density, the manganese dioxide of the present invention is electrolyzed with the manganese dioxide. It is preferably 0.5% by weight or more and 10% by weight or less, more preferably 2% by weight or more and 10% by weight or less, based on the total amount of manganese dioxide.

In the electrolytic manganese dioxide contained in the manganese dioxide mixture of the present invention, the volume of pores (mesopores) having a pore diameter of more than 5 nm and not more than 100 nm is preferably less than 0.005 cm ³ / g, and 0.004 cm ³ / g. The following is more preferable.

In order to obtain sufficient high-rate discharge characteristics, the manganese dioxide mixture of the present invention preferably has a volume of pores (mesopores) having a pore diameter of more than 5 nm and not more than 100 nm of 0.003 cm ³ / g or more, and 0.008 cm ³ / g or more is more preferable, 0.01 cm ³ / g or more is further preferable, and 0.02 cm ³ / g or more is particularly preferable. In pores (mesopores) having a pore diameter of more than 5 nm and not more than 100 nm, it is considered that the electrolyte solution easily penetrates and a favorable battery reaction proceeds. The upper limit of the total amount of the mesopore volume is exemplified by 0.2 cm ³ / g or less in order to maintain the filling density, obtain high battery reactivity and filling properties, and develop good high-rate characteristics. In mesopores, the electrolyte solution is likely to permeate and a good battery reaction is considered to proceed.

In the manganese dioxide mixture of the present invention, the volume of pores (micropores) having a pore diameter of 2 nm or more and 5 nm or less is preferably less than 0.004 cm ³ / g in order to perform a battery reaction more efficiently. more preferably ³ / is less than g, more preferably less than 0.002 cm ³ / g, and particularly preferably less than 0.000Cm ³ / g or more 0.001 cm ³ / g.

It is not clear how the micropore range of the present invention contributes to improving the high-rate characteristics, but it is interpreted as follows. First, electrolytic manganese dioxide in an alkaline battery reacts electrochemically with water as shown in the following formula 1, and H and electrons (e ⁻ ) are exchanged at the manganese dioxide surface and the alkaline electrolyte interface. ing.

MnO ₂ + H ₂ O + e ⁻ → MnOOH + OH ⁻ Formula 1
The more the interface between the manganese dioxide surface and the electrolyte solution (water), the more smoothly the reaction proceeds. However, in the micropore region or smaller pore regions, the electrolyte does not easily penetrate into the pores due to the effect of surface tension. As a result, it is presumed that the pores hardly contribute to the reaction.

  In addition, it is presumed that the more the micropores in the cavity that the electrolyte does not penetrate, the more the electron transfer is inhibited.

For the above reasons, it is considered preferable that the micropore volume is less than 0.004 cm ³ / g because better high-rate characteristics are exhibited.

In the manganese dioxide mixture of the present invention, the volume of the pores exceeding 100 nm is only required to be able to smoothly transfer the electrolyte solution into and out of the mesopore, and can be exemplified as 3 cm ³ / g or less. The manganese dioxide mixture of the present invention tends to have a high filling property.

In the manganese dioxide mixture of the present invention, the mesopore area is preferably 0.1 m ² / g or more, more preferably 0.2 m ² / g or more, and 0.5 m ² / g or more. More preferably, it is particularly preferably 0.6 m ² / g or more.

As described above, it is considered that the battery reaction shown in Formula 1 proceeds favorably because the electrolyte easily penetrates into the mesopore and has a large pore surface area. The upper limit of the pore area of the mesopore is exemplified by 30 m ² / g or less because the packing density is maintained, high battery reactivity and filling properties are obtained, and good high-rate discharge characteristics are exhibited.

  The manganese dioxide mixture of the present invention preferably has an alkali potential of 270 mV or more and less than 350 mV. When the alkaline potential is 270 mV or more and less than 350 mV, when used as a positive electrode material of an alkaline manganese battery, the open circuit voltage of the battery increases, and the discharge time to the lower limit of the usable discharge voltage can be extended. The alkali potential is more preferably 270 mV to 330 mV, further preferably 280 mV to 320 mV, and particularly preferably 290 mV to 310 mV. The alkali potential is measured in a 40 wt% KOH aqueous solution with a mercury / mercury oxide reference electrode as a standard.

The manganese dioxide mixture of the present invention preferably has a bulk density of 1.6 g / cm ³ or more, more preferably 1.8 g / cm ³ or more in order to maintain high filling properties. More preferably, it is 2.0 g / cm ³ or more. On the other hand, the bulk density does not need to be extremely high, and examples thereof include 3.0 g / cm ³ or less, and further 2.5 g / cm ³ or less.

  The manganese dioxide mixture of the present invention does not particularly limit the full width at half maximum (FWHM) of the (110) plane diffraction line with 2θ of around 22 ± 1 ° in a normal XRD measurement pattern using CuKα rays as a light source. However, in order to increase the packing density and increase the discharge capacity, it is preferably 1.6 ° or more and 3.2 ° or less, more preferably 1.7 ° or more and 3.0 ° or less, and 2.1 ° or more and 2 ° or less. More preferably, it is 8 ° or less. By being such FWHM, the filling property is increased and the discharge capacity is increased.

  The average crystallite size of the manganese dioxide mixture of the present invention can be obtained by conversion from the FWHM and the (110) peak position using the Scherrer equation, and is preferably in the range of FWHM (from 1.6 ° to 3.2 °). Then, it is 20-50cm.

The manganese dioxide mixture of the present invention is not particularly limited with respect to the BET specific surface area, but is preferably 12 m ² / g or more and 40 m ² / g or less in order to increase the packing density and increase the discharge capacity. 14 m ² / g or more and 32 m ² / g or less is more preferable, and 20 m ² / g or more and 30 m ² / g or less is more preferable.

  The manganese dioxide mixture of the present invention preferably has an X-ray diffraction (110) / (021) peak intensity ratio of 0.5 or more and 1.05 or less, more preferably 0.55 or more and 1.0 or less. Preferably they are 0.6 or more and 0.96 or less.

  As described above, the (110) plane in the X-ray diffraction of the manganese dioxide mixture appears in the vicinity of 22 ± 1 ° and the (021) plane in the vicinity of 37 ± 1 °, which are the main X-ray diffraction peaks of the manganese dioxide crystal. It is.

  Next, the manufacturing method of the manganese dioxide mixture of this invention is demonstrated.

  The manganese dioxide mixture of the present invention is composed of the manganese dioxide of the present invention and electrolytic manganese dioxide.

  First, the manganese dioxide of the present invention can be obtained by treating a low-valence Mn oxide with a concentrated acid and subjecting it to a disproportionation reaction.

The low-valent Mn oxide is, for example, a mixed manganese trioxide (Mn ₃ O ₄ ) obtained by mixing a solution containing divalent manganese ions and an alkaline solution and oxidizing the obtained mixed solution. And manganese oxides such as manganese sesquioxide (dimanganese trioxide (Mn ₂ O ₃ )) or a mixture thereof. In addition, you may use oxidizing agents, such as air and oxygen, for the oxidation of a mixed solution.

Formulas 2 to 3 show disproportionation reaction formulas when trimanganese tetraoxide (Mn ₃ O ₄ ) is used as the low-valent Mn oxide.

Mn ₃ O ₄ + 8H ⁺ → Mn ²⁺ + 2Mn ³⁺ + 4H ₂ O Formula 2
2Mn ³⁺ + 2H ₂ O → MnO ₂ + Mn ²⁺ + 4H ⁺ Formula 3
In addition, the formula 4 formula (5), as Mn oxide low valence, showing the disproportionation reaction formula in the case of using a three-manganese dioxide _(Mn 2 _{O 3).}

Mn ₂ O ₃ + 6H ⁺ → 2Mn ³⁺ + 3H ₂ O Formula 4
2Mn ³⁺ + 2H ₂ O → MnO ₂ + Mn ²⁺ + 4H ⁺ Formula 5
The manganese dioxide of the present invention can be obtained by a method in which a low-valent Mn oxide is immersed in a concentrated acid solution and then stirred for a certain period of time under heating, followed by filtration and separation. For example, sulfuric acid, nitric acid or the like is used, and the concentration of the acid solution includes, for example, 1 mol / L or more and 8 mol / L or less. For example, it is performed for 1 hour or more and 72 hours or less.

On the other hand, for electrolytic manganese dioxide, for example, a sulfuric acid-manganese sulfate mixed solution is used as the electrolytic solution. For example, the sulfuric acid concentration in the sulfuric acid-manganese sulfate mixed solution is more than 25 g / L and not more than 55 g / L, and the electrolytic current density is It can be produced by electrolysis at 0.5 A / dm ² or more and 1.0 A / dm ² or less and an electrolysis temperature of 90 ° C. or more and 98 ° C. or less. In addition, as an electrode disposed in the electrolytic cell, a lead electrode, a copper electrode, a carbon electrode, or the like can be used as an anode on which electrolytic manganese dioxide is deposited, but a titanium electrode having high strength and high stability is preferably used. A carbon electrode can be used as the cathode.

  When a sulfuric acid-manganese sulfate mixed solution is used as the electrolytic solution in the method for producing electrolytic manganese dioxide, unlike the electrolytic method using a manganese sulfate aqueous solution as the electrolytic solution, the sulfuric acid concentration during the electrolysis period can be controlled. As a result, the sulfuric acid concentration can be arbitrarily set even when electrolysis is performed for a long period of time, so that not only can electrolytic manganese dioxide be stably produced, but the state of the pores of the obtained electrolytic manganese dioxide tends to be uniform. .

  The sulfuric acid-manganese sulfate mixed solution used in the method for producing electrolytic manganese dioxide is preferably controlled to a sulfuric acid concentration in the range of more than 25 g / L and not more than 55 g / L, and not less than 32 g / L and not more than 45 g / L. Is more preferable.

  It is also effective to arbitrarily change the sulfuric acid concentration during the electrolysis period, in particular, to control the sulfuric acid concentration at the end of electrolysis higher than the sulfuric acid concentration at the start of electrolysis. In this case, the sulfuric acid concentration at the start of electrolysis is preferably more than 30 g / L and not more than 40 g / L, more preferably more than 30 g / L and not more than 35 g / L. The sulfuric acid concentration at the end of electrolysis is preferably 32 g / L or more and 55 g / L or less, more preferably 35 g / L or more and 50 g / L or less, and more preferably 40 g / L or more and 45 g / L or less.

  As described above, the effect of arbitrarily changing the sulfuric acid concentration is not clear, but electrolysis under the condition of a relatively low sulfuric acid concentration in the first half not only directly reduces the corrosion damage to the electrode substrate. In the first half, manganese dioxide having a large crystallite size and a low BET specific surface area and high filling properties was obtained, and in the latter half, electrolysis was carried out under the condition of a relatively high sulfuric acid concentration, so that the electrolytic manganese dioxide deposited layer was already covered. Therefore, the electrode base material is less susceptible to corrosion damage, the potential is further increased, and electrolytic manganese dioxide excellent in high-rate characteristics is easily obtained.

  In the method for producing electrolytic manganese dioxide, it is preferable to switch the sulfuric acid concentration between the first half electrolysis and the second half electrolysis instead of gradually changing the sulfuric acid concentration during electrolysis from the start of electrolysis to the end of electrolysis.

  The ratio of the electrolysis in the first half and the electrolysis in the second half is not limited. For example, the ratio of electrolysis time at low sulfuric acid concentration and high sulfuric acid concentration is in the range of 1: 9 to 9: 1, particularly 3: 7 to 7: 3. preferable. In addition, the sulfuric acid concentration here is a value excluding the divalent anion of manganese sulfate.

In the method for producing electrolytic manganese dioxide, the electrolytic current density is not particularly limited, but is preferably 0.5 A / dm ² or more and 1.0 A / dm ² or less in order to maintain an appropriate BET specific surface area. Thereby, it becomes easy to produce the electrolytic manganese dioxide of the present invention efficiently and stably. To obtain a more stable electrolytic manganese dioxide of the present invention, the electrolysis current density is more preferably 0.55 A / dm ² or more 0.88A / dm ² or less, 0.58A / dm ² or more 0.8A More preferably, it is less than / dm ² .

  Although the manganese ion concentration in the electrolytic replenisher in the present invention is not limited, for example, 40 to 60 g / L can be exemplified, and 40 to 50 g / L is preferable. The manganese ion concentration can be measured by ICP emission spectroscopic analysis of a manganese sulfate solution.

  The electrolysis temperature may be 90 ° C or higher and 98 ° C or lower. The higher the electrolysis temperature, the higher the production efficiency of electrolytic manganese dioxide. Therefore, the electrolysis temperature preferably exceeds at least 93 ° C.

  As a method for producing the manganese dioxide mixture of the present invention, a method in which manganese dioxide obtained by the above method is mixed with electrolytic manganese dioxide obtained by the above method at a ratio of 0.5 wt% to 10 wt%, Examples include a method in which manganese dioxide obtained by the above-described method is electrolyzed while being added to a sulfuric acid-manganese sulfate mixed solution and co-deposited with the electrolytic manganese dioxide obtained by the above-described method.

  Examples of the method for mixing manganese dioxide and electrolytic manganese dioxide include methods such as physical mixing and wet mixing. The mixing ratio of manganese dioxide is 0.5 wt% or more and 10 wt% or less, preferably 2 wt% or more and 10 wt% or less. When the content is less than 0.5% by weight, the high-rate discharge characteristics are not sufficient, and when the content exceeds 10% by weight, the density is lowered and the filling property is lowered.

  It is also effective to continuously add the manganese dioxide of the present invention in the form of powder or slurry to the sulfuric acid-manganese sulfate mixed solution used when electrolytically synthesizing electrolytic manganese dioxide and co-deposit it. Here, co-deposition means that the manganese dioxide of the present invention is continuously added to a sulfuric acid-manganese sulfate mixed solution, so that when electrolytic manganese dioxide is electrolytically deposited, The manganese dioxide of the invention is taken in at the same time.

  There is no restriction | limiting in particular in the method used as a positive electrode active material of an alkaline manganese battery, It can mix and use with an additive by a well-known method.

  For example, a mixed powder obtained by adding carbon or the like in order to impart conductivity to a manganese dioxide mixture can be prepared, and this can be used as a battery positive electrode as a powder molded body that is pressure-molded into a disk shape or a ring shape.

Further, the manganese dioxide of the present invention has an extremely large mesopore than manganese dioxide used as an adsorbent, for example, δ-type MnO ₂ synthesized by reaction of permanganate ion (Mn ⁷⁺ ) and manganese ion (Mn ²⁺ ). Therefore, for example, it is excellent in the property of adsorbing and separating valuable metal ions, heavy metal ions, and anions in water. Examples of such valuable metal ions include platinum groups such as Pt and Pd, and alkali metals such as Li, and examples of heavy metal ions include Pb, Cd, Hg, Zn, Cu, Ni, and Cr. , As, Se, Sb, Mo and the like, and examples of the anion include halogenate ions such as chlorate ions and bromate ions.

  The manganese dioxide of the present invention acts as an adsorbent even in the powder form as it is, but it can be used as an adsorbent even if it is molded, granulated by mixing with a binder.

  The manganese dioxide mixture of the present invention is excellent in electrochemical reactivity when used as a positive electrode material of an alkaline battery, excellent in high-rate discharge characteristics, and further, the manganese dioxide mixture of the present invention is obtained by the manganese dioxide of the present invention. be able to.

This is an evaluation cell for high rate discharge characteristics. 2 is an XRD pattern of trimanganese tetraoxide (Mn ₃ O ₄ ) obtained in Example 1. FIG. It is a XRD pattern of the manganese dioxide of Example 1, the electrolytic manganese dioxide of the synthesis example 1, and the manganese dioxide mixture of Examples 2-4. 2 is a pore area (cumulative) distribution chart of manganese dioxide of Example 1, manganese dioxide mixtures of Examples 2 to 4, and electrolytic manganese dioxide of Comparative Example 1. FIG. 6 is an XRD pattern of dimanganese trioxide (Mn ₂ O ₃ ) obtained in Example 5. It is a XRD pattern of manganese dioxide of Examples 5-8. It is a pore area (cumulative) distribution map of the manganese dioxide of Examples 5-8. It is an XRD pattern of the manganese dioxide mixture of Examples 9-12. It is a pore area (cumulative) distribution map of the manganese dioxide mixture of Examples 9-12 and the electrolytic manganese dioxide of Comparative Example 1. 4 is an XRD pattern of manganese dioxide of Comparative Example 2. 6 is a pore area (cumulative) distribution chart of manganese dioxide of Example 8 and Comparative Example 2. FIG.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited to these Examples.

<Measurement of alkali potential of manganese dioxide and manganese dioxide mixture>
The alkali potential of manganese dioxide and manganese dioxide mixture was measured in a 40 wt% KOH aqueous solution as follows.

  0.9 g of carbon as a conductive agent is added to 3 g of manganese dioxide (manganese dioxide mixture) to obtain a mixed powder. To this mixed powder is added 4 ml of 40 wt% KOH aqueous solution, and manganese dioxide (manganese dioxide mixture), carbon and KOH aqueous solution are added. A mixture slurry was obtained. The alkaline potential of manganese dioxide (manganese dioxide mixture) was measured based on the mercury / mercury oxide reference electrode.

<Measurement of pore volume, area and bulk density of manganese dioxide and manganese dioxide mixture>
The volume, area, and bulk density of secondary pores, micropores, and mesopores were determined by mercury porosimetry (Pore Sizer 9510, manufactured by Micromeritics).

  As a pretreatment for the measurement, the sample was left to dry at 80 ° C. Thereafter, the measurement was performed by changing the pressure range of mercury stepwise from atmospheric pressure to 414 MPa. By this measurement, pore distribution (volume distribution and area distribution) is obtained, and pores having a pore diameter of 2 nm or more and 200 nm or less are defined as “secondary pores”. “Micropores”, and pores having a pore diameter of more than 5 nm and not more than 100 nm were called “mesopores”.

  The bulk density was determined from the amount of mercury when mercury was introduced at atmospheric pressure.

<Measurement of full width at half maximum (FWHM) in XRD measurement>
The full width at half maximum (FWHM) of a diffraction line having 2θ of around 22 ± 1 ° of manganese dioxide and a mixture of manganese dioxide was measured using a general X-ray diffractometer (MXP-3 manufactured by Mac Science). A CuKα ray (λ = 1.5405 mm) is used as the radiation source, the measurement mode is step scan, the scan condition is 0.04 ° per second, the measurement time is 3 seconds, and the measurement range is 2 ° to 5 ° to 80 ° Measured with

<Calculation of (110) / (021)>
In the XRD pattern obtained in the same manner as FWHM, a diffraction line with 2θ around 22 ± 1 ° is a peak corresponding to the (110) plane, and a diffraction line around 37 ± 1 ° is a peak corresponding to the (021) plane. It was. (110) / (021) was obtained by dividing the peak intensity of the (110) plane by the peak intensity of the (021) plane.

<Measurement of BET specific surface area>
The BET specific surface area of manganese dioxide and manganese dioxide mixture was measured by nitrogen adsorption according to the BET one-point method. A gas adsorption specific surface area measuring device (Flowsorb III, manufactured by Shimadzu Corporation) was used as the measuring device. Prior to the measurement, the measurement sample was deaerated by heating at 150 ° C. for 40 minutes.

<Evaluation of high-rate discharge characteristics>
A positive electrode mixture was prepared by weighing and mixing so that the manganese dioxide mixture was 80 wt%, the conductive material was 5 wt%, and the 40 wt% KOH aqueous solution was 15 wt%. The positive electrode mixture was weighed and formed to be 1.0 g in terms of manganese dioxide mixture, molded, and the discharge characteristics were evaluated by the evaluation cell for high rate discharge characteristics shown in FIG. 1 using zinc wire for the negative electrode. did. The cell for evaluation was allowed to stand at room temperature for 1 hour and then subjected to a discharge test. The discharge conditions were as follows: a pulse discharge cycle in which the current was stopped for 50 seconds after being discharged at a current of 100 mA / g for 10 seconds, and the high-rate discharge characteristic was evaluated by the number of cycles up to a final voltage of 0.9 V; The discharge capacity was obtained as a relative value with respect to the measurement result of Comparative Example 1 as 100%.

<Evaluation of adsorption properties for valuable metal ions>
100 mg of manganese oxide was added to each of an Erlenmeyer flask containing 100 mL of an aqueous solution containing 8.8 mg / L of palladium (Pd) and an Erlenmeyer flask containing 100 mL of an aqueous solution containing 8.0 mg / L of lithium (Li). After stirring for 16 hours, the manganese oxide was separated by filtration with a disposable filter (25HP020AN, manufactured by Advantech Toyo) and evaluated by measuring the Pd concentration and the Li concentration in the aqueous solution.

<Evaluation of adsorption properties for heavy metal ions>
To an Erlenmeyer flask containing 100 mL of an aqueous solution containing 10.1 mg / L of lead (Pb), 100 mg of manganese oxide was added and stirred at room temperature for 16 hours, and then the manganese oxide was removed with a disposable filter (25HP020AN, manufactured by Advantech Toyo). It filtered and isolate | separated and evaluated by measuring Pb density | concentration in aqueous solution.

Example 1
A manganese sulfate aqueous solution having a manganese ion concentration of 90 g / L was stirred, and a 1 mol / L sodium hydroxide aqueous solution was added thereto while blowing air to obtain a manganese sulfate aqueous solution containing manganese oxide. The obtained manganese oxide was a single phase of trimanganese tetraoxide (Mn ₃ O ₄ ).

The XRD pattern of the obtained trimanganese tetraoxide (Mn ₃ O ₄ ) is shown in FIG.

51 g of the obtained trimanganese tetraoxide (Mn ₃ O ₄ ) was immersed in a beaker containing 260 g of a 3 mol / L sulfuric acid solution, and stirred at 60 ° C. for 4 hours to obtain a black precipitate slurry. After filtering this slurry solution with a membrane filter, the operation of placing the filtrate in a beaker containing 500 mL of pure water and washing with water for 1 hour was repeated twice. Next, after filtering again with a membrane filter, the filtrate was again placed in a beaker containing 500 mL of pure water, neutralized with a 1 mol / L NaOH solution until the slurry pH reached 5.6, filtered and dried. As a result, manganese oxide was obtained. The obtained manganese oxide showed an XRD pattern attributed to manganese dioxide (γMnO ₂ ). The physical properties of this manganese dioxide are shown in Table 1, the XRD pattern is shown in FIG. 3, and the pore area (cumulative) distribution chart is shown in FIG.

合成例１
硫酸−硫酸マンガン混合溶液の入った電解槽内に、マンガンイオン濃度４５ｇ／Ｌの補給硫酸マンガン液を連続的に添加しながら電解し、二酸化マンガンの電析する陽極にはチタン電極を用い、陰極にはカーボン電極を用いて、電解二酸化マンガンを製造した。電解中は、電解電流密度を０．５９Ａ／ｄｍ^２、電解温度を９６℃とした。なお、補給硫酸マンガン液は電解槽内の硫酸濃度が３５．０ｇ／Ｌとなるよう添加し、１４日間電解し、電解終了時の電解電圧は、２．６Ｖであった。

Synthesis example 1
In an electrolytic cell containing a sulfuric acid-manganese sulfate mixed solution, electrolysis is performed while continuously adding a supplemental manganese sulfate solution having a manganese ion concentration of 45 g / L. A titanium electrode is used as an anode for manganese dioxide electrodeposition, A carbon electrode was used to produce electrolytic manganese dioxide. During electrolysis, the electrolysis current density was 0.59 A / dm ² , and the electrolysis temperature was 96 ° C. The replenished manganese sulfate solution was added so that the sulfuric acid concentration in the electrolytic cell was 35.0 g / L, electrolyzed for 14 days, and the electrolysis voltage at the end of the electrolysis was 2.6V.

  The obtained electrodeposit was peeled from the electrode, pulverized to an average particle size of 40 μm, neutralized with water and dried to obtain electrolytic manganese dioxide. The obtained electrolytic manganese dioxide was a γ phase. The physical properties of this electrolytic manganese dioxide are shown in Table 1, and the XRD pattern is shown in FIG.

Example 2
A manganese dioxide mixture was obtained by taking 0.5 g of manganese dioxide obtained in Example 1 and 4.5 g of electrolytic manganese dioxide obtained in Synthesis Example 1 in an agate mortar and stirring with a pestle. The evaluation results of the physical properties and high-rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 2, the XRD pattern is shown in FIG. 3, and the pore area (cumulative) distribution chart is shown in FIG.

実施例３
実施例１で得られた二酸化マンガン０．２ｇと合成例１で得られた電解二酸化マンガン４．８ｇとした以外は、実施例２に従って、二酸化マンガン混合物を得た。得られた二酸化マンガン混合物の物性及びハイレート放電特性の評価結果を表２に、ＸＲＤパターンを図３に、細孔面積（累積）分布図を図４に示した。

Example 3
A manganese dioxide mixture was obtained according to Example 2, except that 0.2 g of manganese dioxide obtained in Example 1 and 4.8 g of electrolytic manganese dioxide obtained in Synthesis Example 1 were used. The evaluation results of the physical properties and high-rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 2, the XRD pattern is shown in FIG. 3, and the pore area (cumulative) distribution chart is shown in FIG.

Example 4
A manganese dioxide mixture was obtained according to Example 2, except that 0.1 g of manganese dioxide obtained in Example 1 and 4.9 g of electrolytic manganese dioxide obtained in Synthesis Example 1 were used. The evaluation results of the physical properties and high-rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 2, the XRD pattern is shown in FIG. 3, and the pore area (cumulative) distribution chart is shown in FIG.

Comparative Example 1
The evaluation results of the high rate discharge characteristics of the electrolytic manganese dioxide obtained in Synthesis Example 1 are shown in Table 2, the XRD pattern is shown in FIG. 3 (Synthesis Example 1), and the pore area (cumulative) distribution diagrams are shown in FIGS. It was.

Example 5
The electrolytic manganese dioxide obtained in Synthesis Example 1 was fired at 600 ° C. for 4 hours to obtain dimanganese trioxide (Mn ₂ O ₃ ). The XRD pattern of the obtained dimanganese trioxide (Mn ₂ O ₃ ) is shown in FIG.

50.6 g of the obtained dimanganese trioxide (Mn ₂ O ₃ ) was immersed in a beaker containing 260 g of a 3 mol / L sulfuric acid solution, and stirred at 60 ° C. for 4 hours to obtain a slurry solution of a black precipitate. After filtering this slurry solution with a membrane filter, the operation of placing the filtrate in a beaker containing 500 mL of pure water and washing with water for 1 hour was repeated twice. Next, after filtering again with a membrane filter, the filtrate was again placed in a beaker containing 500 mL of pure water, neutralized with a 1 mol / L NaOH solution until the slurry pH reached 5.6, filtered and dried. As a result, manganese oxide was obtained. The obtained manganese oxide showed an XRD pattern attributed to manganese dioxide containing both an α phase and a γ phase. The physical properties of this manganese dioxide are shown in Table 3, the XRD pattern is shown in FIG. 6, and the pore area (cumulative) distribution chart is shown in FIG.

実施例６
実施例１で得られた四三酸化マンガン（Ｍｎ_３Ｏ_４）５０．３ｇを、１ｍｏｌ／Ｌ硫酸溶液２６０ｇが入ったビーカーに浸漬し、８０℃で１６時間撹拌し、黒色沈殿物のスラリー液を得た。このスラリー液をメンブランフィルターでろ過した後、ろ過物を５００ｍＬの純水が入ったビーカーに入れて、１時間水洗する操作を２回繰り返した。次に再度メンブランフィルターでろ過した後、再びろ過物を５００ｍＬの純水が入ったビーカーに入れた後、スラリーｐＨが５．６になるまで１ｍｏｌ／ＬのＮａＯＨ溶液で中和し、ろ過、乾燥してマンガン酸化物を得た。得られたマンガン酸化物は二酸化マンガン（γＭｎＯ_２）に帰属されるＸＲＤパターンを示した。この二酸化マンガンの物性を表３に、ＸＲＤパターンを図６に、細孔面積（累積）分布図を図７に示した。

Example 6
50.3 g of trimanganese tetraoxide (Mn ₃ O ₄ ) obtained in Example 1 was immersed in a beaker containing 260 g of a 1 mol / L sulfuric acid solution, stirred at 80 ° C. for 16 hours, and a black precipitate slurry solution Got. After filtering this slurry solution with a membrane filter, the operation of placing the filtrate in a beaker containing 500 mL of pure water and washing with water for 1 hour was repeated twice. Next, after filtering again with a membrane filter, the filtrate was again placed in a beaker containing 500 mL of pure water, neutralized with a 1 mol / L NaOH solution until the slurry pH reached 5.6, filtered and dried. As a result, manganese oxide was obtained. The obtained manganese oxide showed an XRD pattern attributed to manganese dioxide (γMnO ₂ ). The physical properties of this manganese dioxide are shown in Table 3, the XRD pattern is shown in FIG. 6, and the pore area (cumulative) distribution chart is shown in FIG.

Example 7
51.1 g of trimanganese tetraoxide (Mn ₃ O ₄ ) obtained in Example 1 was immersed in a beaker containing 260 g of a 5 mol / L sulfuric acid solution, stirred at 60 ° C. for 4 hours, and a black precipitate slurry solution Got. After filtering this slurry solution with a membrane filter, the operation of placing the filtrate in a beaker containing 500 mL of pure water and washing with water for 1 hour was repeated twice. Next, after filtering again with a membrane filter, the filtrate was again placed in a beaker containing 500 mL of pure water, neutralized with a 1 mol / L NaOH solution until the slurry pH reached 5.6, filtered and dried. As a result, manganese oxide was obtained. The obtained manganese oxide showed an XRD pattern attributed to manganese dioxide (γMnO ₂ ). The physical properties of this manganese dioxide are shown in Table 3, the XRD pattern is shown in FIG. 6, and the pore area (cumulative) distribution chart is shown in FIG.

Example 8
50.0 g of trimanganese tetraoxide (Mn ₃ O ₄ ) obtained in Example 1 was immersed in a beaker containing 260 g of a 3 mol / L sulfuric acid solution, stirred at 40 ° C. for 24 hours, and a black precipitate slurry solution Got. After filtering this slurry solution with a membrane filter, the operation of placing the filtrate in a beaker containing 500 mL of pure water and washing with water for 1 hour was repeated twice. Next, after filtering again with a membrane filter, the filtrate was again placed in a beaker containing 500 mL of pure water, neutralized with a 1 mol / L NaOH solution until the slurry pH reached 5.6, filtered and dried. As a result, manganese oxide was obtained. The obtained manganese oxide showed an XRD pattern attributed to manganese dioxide (γMnO ₂ ). The physical properties of this manganese dioxide are shown in Table 3, the XRD pattern is shown in FIG. 6, and the pore area (cumulative) distribution charts are shown in FIGS.

Example 9
A manganese dioxide mixture was obtained according to Example 2, except that 0.2 g of manganese dioxide obtained in Example 5 and 4.8 g of electrolytic manganese dioxide obtained in Synthesis Example 1 were used. The evaluation results of the physical properties and high-rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 4, the XRD pattern is shown in FIG. 8, and the pore area (cumulative) distribution chart is shown in FIG.

実施例１０
実施例６で得られた二酸化マンガン０．２ｇと合成例１で得られた電解二酸化マンガン４．８ｇとした以外は、実施例２に従って、二酸化マンガン混合物を得た。得られた二酸化マンガン混合物の物性及びハイレート放電特性の評価結果を表４に、ＸＲＤパターンを図８に、細孔面積（累積）分布図を図９に示した。

Example 10
A manganese dioxide mixture was obtained according to Example 2, except that 0.2 g of manganese dioxide obtained in Example 6 and 4.8 g of electrolytic manganese dioxide obtained in Synthesis Example 1 were used. The evaluation results of the physical properties and high rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 4, the XRD pattern is shown in FIG. 8, and the pore area (cumulative) distribution chart is shown in FIG.

Example 11
A manganese dioxide mixture was obtained according to Example 2, except that 0.2 g of manganese dioxide obtained in Example 7 and 4.8 g of electrolytic manganese dioxide obtained in Synthesis Example 1 were used. The evaluation results of the physical properties and high rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 4, the XRD pattern is shown in FIG. 8, and the pore area (cumulative) distribution chart is shown in FIG.

Example 12
A manganese dioxide mixture was obtained according to Example 2, except that 0.2 g of manganese dioxide obtained in Example 8 and 4.8 g of electrolytic manganese dioxide obtained in Synthesis Example 1 were used. The evaluation results of the physical properties and high rate discharge characteristics of the obtained manganese dioxide mixture are shown in Table 4, the XRD pattern is shown in FIG. 8, and the pore area (cumulative) distribution chart is shown in FIG.

Example 13
Using the manganese dioxide obtained in Example 8, the adsorption characteristics of valuable metal ions and heavy metal ions were evaluated. The evaluation results are shown in Table 5.

比較例２
過マンガン酸カリウム（ＫＭｎＯ_４）０．１ｍｏｌ／Ｌの水溶液に、硫酸マンガン（ＭｎＳＯ_４）０．６ｍｏｌ／Ｌの水溶液を常温下で２ｍＬ／分の速度で添加し、添加終了後、２時間の熟成反応を行った。反応終了後、ろ過、水洗を行い、その後、１０５℃で１６時間乾燥した後にマンガン酸化物を得た。得られたマンガン酸化物は、過マンガン酸イオン（Ｍｎ^７＋）とマンガンイオン（Ｍｎ^２＋）の反応で合成した際に得られる二酸化マンガン（δＭｎＯ_２）に帰属されるＸＲＤパターンを示した。

Comparative Example 2
To an aqueous solution of potassium permanganate (KMnO ₄ ) 0.1 mol / L, an aqueous solution of manganese sulfate (MnSO ₄ ) 0.6 mol / L was added at a rate of 2 mL / min at room temperature. An aging reaction was performed. After completion of the reaction, filtration and washing with water were carried out, and then after drying at 105 ° C. for 16 hours, manganese oxide was obtained. The obtained manganese oxide showed an XRD pattern attributed to manganese dioxide (δMnO ₂ ) obtained when synthesized by a reaction of permanganate ion (Mn ⁷⁺ ) and manganese ion (Mn ²⁺ ).

The volume of micropores of the manganese dioxide (pore diameter 2nm or 5nm less pores) and mesopores (less pores 100nm exceeds the pore diameter 5nm), respectively 0.011cm ³ / g and 0.020 cm ³ / g Met. The XRD pattern of this manganese dioxide is shown in FIG. 10, and the pore area (cumulative) distribution chart is shown in FIG.

  Using the resulting manganese dioxide, the adsorption characteristics of valuable metal ions and heavy metal ions were evaluated. The evaluation results are shown in Table 5.

  From Table 5, it was found that the manganese dioxide of the present invention is excellent in the adsorption characteristics of valuable metal ions and heavy metal ions.

  Since the manganese dioxide mixture of the present invention has a large reaction surface area, it can be used as a positive electrode active material for alkaline manganese dry batteries having excellent discharge characteristics, particularly high-rate discharge characteristics.

1: Zinc negative electrode 2: Positive electrode mixture 3: Upper fixture 4: KOH aqueous solution 5: Perforated plate 6: Separator 7: Ni plate 8: Ni lead

Claims (16)

A manganese dioxide characterized in that the volume of pores having a pore diameter of more than 5 nm and not more than 100 nm is 0.07 cm ³ / g or more. 2. The manganese dioxide according to claim 1, wherein the volume of pores having a pore diameter of 2 nm or more and 5 nm or less is less than 0.004 cm ³ / g. A manganese dioxide mixture comprising the manganese dioxide of claim 1 or claim 2 and electrolytic manganese dioxide. 4. The manganese dioxide mixture according to claim 3, wherein the volume of pores having a pore diameter of more than 5 nm and not more than 100 nm is 0.003 cm ³ / g or more. 5. The manganese dioxide mixture according to claim ³ , wherein the volume of pores having a pore diameter of 2 nm or more and 5 nm or less is less than 0.004 cm ³ / g. The manganese dioxide mixture according to any one of claims 3 to 5, wherein an area of pores having a pore diameter of more than 5 nm and not more than 100 nm is 0.1 m ² / g or more. The manganese dioxide mixture according to any one of claims 3 to 6, wherein an alkali potential is 270 mV or more and less than 350 mV. The manganese dioxide mixture according to any one of claims 3 to 7, wherein a bulk density is 1.6 g / cm ³ or more. 3. The method for producing manganese dioxide according to claim 1, wherein the low-valent Mn oxide is produced by a disproportionation reaction with a concentrated acid. The method for producing manganese dioxide according to claim 9, wherein the low-valent Mn oxide is trimanganese tetraoxide (Mn ₃ O ₄ ). The method for producing manganese dioxide according to claim 9, wherein the low-valent Mn oxide is dimanganese trioxide (Mn ₂ O ₃ ). The method for producing manganese dioxide according to any one of claims 9 to 11, wherein the acid is sulfuric acid having a concentration of 1 mol / L to 8 mol / L. The manganese dioxide according to claim 1 is mixed with electrolytic manganese dioxide at a ratio of 0.5 wt% to 10 wt% with respect to the total of the manganese dioxide and electrolytic manganese dioxide. The manufacturing method of the manganese dioxide mixture of any one of Claims 8-9. The manganese dioxide according to claim 1 is electrolyzed while being added to a sulfuric acid-manganese sulfate mixed solution, and is co-deposited with electrolytic manganese dioxide. The manufacturing method of the manganese dioxide mixture of description. A positive electrode active material for a battery, comprising the manganese dioxide mixture according to any one of claims 3 to 8. An adsorbent comprising the manganese dioxide according to claim 1 or 2.

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