JP6550729B2 - Electrolytic manganese dioxide, method for producing the same, and use thereof - Google Patents

Description

  The present invention relates to electrolytic manganese dioxide, a method for producing the same, and uses thereof. More specifically, the present invention relates to electrolytic manganese dioxide used as a positive electrode active material in, for example, a manganese dry battery, particularly an alkaline manganese dry battery, and a method for producing the same.

  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).

  In addition, electrolytic manganese dioxide produced by suspension electrolysis at a relatively high electrolysis temperature has been proposed as an electrolytic manganese dioxide improved with a middle rate smaller than the high rate (Patent Document 6).

  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.

Japanese Patent Application Publication No. 2007-141643 U.S. Patent 6,527,941 JP, 2009-135067, A JP, 2009-289728, A JP 2005-520290 A JP, 2013-199422, A

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

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

The inventors of the present invention conducted extensive studies on electrolytic manganese dioxide used particularly as a positive electrode active material of an alkaline manganese dry battery, and as a result, the volume of pores having a pore diameter of 5 nm or more and 100 nm or less is 0.003 cm ³ / g or more. The electrolytic manganese dioxide was found to be a positive electrode material having excellent high rate discharge characteristics, and the present invention was completed. That is, the present invention is an electrolytic manganese dioxide characterized by having a pore volume of more than 5 nm and a pore diameter of 100 nm or less of 0.003 cm ³ / g or more.

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

The electrolytic 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 0.003 cm ³ / g or more. It is characterized by 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. When the mesopore volume is less than 0.003 cm ³ / g, the high-rate discharge characteristics are insufficient. In order to obtain particularly good high-rate discharge characteristics, is preferably at least 0.007cm ³ / g volume of mesopores, more preferably 0.01 cm ³ / g or more. 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 the electrolytic manganese dioxide of the present invention, the volume of pores having a pore diameter of 2 nm or more and 5 nm or less (hereinafter sometimes referred to as “micropore”) is less than 0.004 cm ³ / g in order to perform battery reaction more efficiently. Is preferably 0.003 cm ³ / g or less, and particularly preferably less than 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 speculated 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 electrolytic manganese dioxide of the present invention, the mesopore area is preferably 0.1 m ² / g or more, more preferably 0.5 m ² / g or more, and 2.0 m ² / g or more. More preferably, it is particularly preferably 5.5 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 electrolytic manganese dioxide 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 alkaline potential is measured on a mercury / mercury oxide reference electrode in a 40 wt% KOH aqueous solution.

The electrolytic manganese dioxide 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 electrolytic manganese dioxide of the present invention does not particularly limit the full width at half maximum (FWHM) of the (110) plane diffraction line having 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 4.0 ° or less, more preferably 1.7 ° or more and 3.8 ° or less, and 2.1 ° or more and 3 or less. More preferably, it is 7 ° or less. By such FWHM, the chargeability is enhanced and the discharge capacity is increased.

  The average crystallite diameter of the electrolytic manganese dioxide of the present invention is obtained by conversion according to Scherrer's formula from the FWHM and the (110) peak position, and the average crystallite diameter corresponds to 20 to 50 mm.

The electrolytic manganese dioxide of the present invention is not particularly limited with respect to the BET specific surface area, but in order to further increase the discharge capacity, it is preferably 30 m ² / g or more and 80 m ² / g or less, and 40 m ² / g or more and 70 m or less. ² / g or less is more preferable, and 45 m ² / g or more and 65 m ² / g or less is further preferable.

  The electrolytic manganese dioxide of the present invention preferably has an X-ray diffraction (110) / (021) peak intensity ratio of 0.3 or more and 1.0 or less, more preferably 0.35 or more and 0.55 or less. Preferably it is 0.4 or more and 0.5 or less.

  In the X-ray diffraction of electrolytic manganese dioxide, the (110) plane appears in the vicinity of 22 ± 1 ° and the (021) plane appears in the vicinity of 37 ± 1 °, which are the main X-ray diffraction peaks of the manganese dioxide crystal.

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

The electrolytic manganese dioxide of the present invention is a method for producing electrolytic manganese dioxide in which manganese oxide particles are suspended in a sulfuric acid-manganese sulfate mixed solution, and the manganese oxide particles are continuously mixed in a sulfuric acid-manganese sulfate mixed solution. The concentration of manganese oxide particles in the sulfuric acid-manganese sulfate mixed solution is 5 mg / L or more and 100 mg / L or less, the electrolysis temperature is 80 ° C. or more and less than 96 ° C., and the electrolysis current density is 0.5 A / dm ² or more and 1.7 A. / dm ² by electrolysis in the following, can be produced. By conducting electrolysis under the above conditions, some suspended manganese oxide particles become primary particle nuclei, and further by conducting electrolysis at a low temperature, primary particle growth is suppressed and primary particles of electrolytic manganese dioxide are deposited. Mesopores are formed between them, and the electrolytic manganese dioxide of the present invention having a pore diameter of more than 5 nm and a pore size of 100 nm or less of 0.003 cm ³ / g or more can be obtained.

  In the method for producing electrolytic manganese dioxide of the present invention, manganese oxide particles are continuously mixed in a sulfuric acid-manganese sulfate mixed solution. As a result, the concentration of manganese oxide particles in the sulfuric acid-manganese sulfate mixed solution during the electrolysis period can be stabilized, and electrolytic dioxide that electrolyzes an electrolytic solution containing manganese oxide particles at a constant concentration throughout the electrolysis period. It becomes a manufacturing method of manganese. As a result, the physical properties of electrolytic manganese dioxide obtained throughout the entire electrolysis, particularly the state of the pores, become uniform. In addition, the manganese oxide particles may be directly mixed into a sulfuric acid-manganese sulfate mixed solution, or added to a replenished manganese sulfate solution supplied to the sulfuric acid-manganese sulfate mixed solution and then mixed into the sulfuric acid-manganese sulfate mixed solution. Alternatively, it may be mixed as a slurry to a sulfuric acid-manganese sulfate mixed solution.

When manganese oxide particles are mixed in a sulfuric acid-manganese sulfate mixed solution, examples of manganese oxide particles to be mixed include manganese dioxide (MnO ₂ ), manganese trioxide (Mn ₂ O ₃ ), and manganese trioxide (Mn). ₃ at least one selected from the group consisting of ₃ O ₄ ) can be used, and preferably, manganese dioxide (MnO ₂ ) can be used.

  The manganese oxide particles preferably have an average particle size of 5 μm or less, more preferably 3 μm or less, still more preferably 1 μm or less, and particularly preferably 0.9 μm or less. When the average particle size is 5 μm or less, the manganese oxide particles are less likely to settle and are easily dispersed uniformly in the sulfuric acid-manganese sulfate mixed solution. Thus, it is preferable that the manganese oxide particles have an average particle size such that the dispersibility does not decrease, but a practical value thereof may be 0.5 μm or more.

  The concentration of manganese oxide particles in the sulfuric acid-manganese sulfate mixed solution is 5 mg / L or more and 100 mg / L or less. When the concentration of the manganese oxide particles is less than 5 mg / L, the number of primary particle nuclei is small and the effect of the manganese oxide particles is insufficient. When the concentration exceeds 100 mg / L, the manganese oxide particles aggregate and settle, The effect is reduced. In order to ensure a more appropriate amount of manganese oxide particles as primary particle nuclei, it is preferably 5 mg / L or more and 50 mg / L or less, more preferably 5 mg / L or more and 20 mg / L.

  In the method for producing electrolytic manganese dioxide of the present invention, the electrolysis temperature is 80 ° C. or more and less than 96 ° C. When the electrolysis temperature is less than 80 ° C., the current efficiency is lowered, so that the production efficiency is lowered. When the electrolysis temperature is 96 ° C. or more, the evaporation of the electrolyte is increased and the heating cost is increased. The electrolysis temperature is preferably 80 ° C. or higher and 94 ° C. or lower, more preferably 80 ° C. or higher and lower than 90 ° C., and further preferably 80 ° C. or higher and 88 ° C. or lower in order to further suppress the growth of primary particles.

  In the method for producing electrolytic manganese dioxide of the present invention, the end voltage is preferably 2.7 V or more, more preferably 3.0 V or more, and further preferably 5.0 V or more. If the electrolysis voltage becomes too high, electrolysis becomes unstable and continuous operation becomes difficult, so that the upper limit of the end voltage can be exemplified by 10 V or less.

  The method for producing electrolytic manganese dioxide of the present invention uses a sulfuric acid-manganese sulfate mixed solution as an electrolytic solution. Unlike the electrolytic method using a manganese sulfate aqueous solution as an electrolytic solution, the sulfuric acid concentration during the electrolysis period is controlled. It becomes possible. 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 in the electrolytic solution is preferably controlled in the range of more than 25 g / L and not more than 55 g / L as the sulfuric acid concentration, and more preferably not less than 32 g / L and not more than 45 g / L. 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 of the present invention, 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 of the present invention, the electrolytic current density is 0.5 A / dm ² or more and 1.7 A / dm ² or less. If it is less than 0.5 A / dm ² , an appropriate amount of mesopore that is easily penetrated by the electrolyte cannot be secured, and if it exceeds 1.7 A / dm ² , the electrolysis voltage becomes unstable, which is not preferable in production. In order to maintain an appropriate BET specific surface area, it is preferably 0.5 A / dm ² or more and 1.65 A / dm ² or less. This facilitates the efficient and stable production of the electrolytic manganese dioxide of the present invention. In order to obtain the electrolytic manganese dioxide of the present invention more stably, the electrolysis current density is more preferably 0.6 A / dm ² or more and 1.6 A / dm ² or less, and 1.0 A / dm ² or more and 1.55 A. More preferably, it is less than / dm ² .

  Although there is no limitation in the manganese ion density | concentration in the replenishment manganese sulfate liquid in this invention, For example, 25-60 g / L can be illustrated.

The large mesopore (mesopore volume is 0.003 cm ³ / g or more) electrolytic manganese dioxide of the present invention can be used alone, but is mixed with electrolytic manganese dioxide having a mesopore volume of less than 0.003 cm ³ / g It can also be used as an electrolytic manganese dioxide mixture.

As a manufacturing method of the above-mentioned electrolytic manganese dioxide mixture, electrolytic manganese dioxide having a mesopore volume of 0.003 cm ³ / g or more obtained by the above-described method and electrolytic manganese dioxide of less than 0.003 cm ³ / g and 0.5 The method of mixing in the ratio of the weight% or more and 10 weight% or less is mentioned. Examples of the method for mixing electrolytic manganese dioxide include methods such as physical mixing and wet mixing, and the mixing ratio of the electrolytic manganese dioxide of the present invention is 0.5 wt% or more and 10 wt% or less. If it is less than 0.5% by weight, the high-rate discharge characteristics are not sufficient, and if it exceeds 10% by weight, the density becomes low, and the filling property is lowered.

  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 in which carbon or the like is added to provide conductivity to electrolytic manganese dioxide or an electrolytic manganese dioxide mixture is prepared, and this is used as a battery positive electrode as a powder molded body that is pressure-molded into a disk shape or a ring shape. Can do.

  The electrolytic manganese dioxide of the present invention is excellent in electrochemical reactivity and high-rate discharge characteristics when used as a positive electrode material for an alkaline battery, and the electrolytic manganese dioxide of the present invention can be obtained by the synthesis method of the present invention. .

It is an evaluation cell for high rate discharge characteristics. It is a XRD pattern of manganese dioxide of Examples 1-3 and Comparative Examples 1-4. 4 is an FE-SEM image (300,000 times) of Example 2. 4 is an FE-SEM image (300,000 times) of Comparative Example 1.

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

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

  0.9 g of carbon as a conductive agent was added to 3 g of electrolytic manganese dioxide to obtain a mixed powder, and 4 ml of 40% KOH aqueous solution was added to this mixed powder to obtain a mixture slurry of electrolytic manganese dioxide, carbon and KOH aqueous solution. The alkaline potential of the electrolytic manganese dioxide was measured with respect to the potential of the mixture slurry with reference to a mercury / mercury oxide reference electrode.

<Measurement of pore volume, area and bulk density of electrolytic manganese dioxide>
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”.

  Moreover, bulk density was calculated | required from the mercury amount at the time of introduce | transducing mercury 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 about 22 ± 1 ° of electrolytic 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 °. It measured by.

<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. And (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 electrolytic manganese dioxide was measured by nitrogen adsorption of the BET one-point method. As a measuring device, a gas adsorption type specific surface area measuring device (Flowsorb III, manufactured by Shimadzu Corporation) was used. Prior to measurement, the measurement sample was degassed by heating at 150 ° C. for 40 minutes.

<Evaluation of high rate discharge characteristics>
A positive electrode mixture was prepared by weighing and mixing electrolytic manganese dioxide at 80 wt%, conductive material at 5 wt%, and 40 wt% KOH aqueous solution at 15 wt%. The positive electrode mixture is weighed to 0.09 g in terms of electrolytic manganese dioxide, molded, and the discharge characteristics are 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. As the discharge conditions, the discharge capacity was evaluated when the final voltage was 0.9 V at a current of 100 mA / g. The discharge capacity was determined as a relative value with the measurement result of Comparative Example 2 being 100%.

Example 1
Manganese oxide particles as manganese oxide particles are contained in an electrolytic cell containing a sulfuric acid-manganese sulfate mixed solution, and electrolysis is performed for 23 hours while continuously adding a replenishing manganese sulfate solution having a manganese ion concentration of 45 g / L. Manganese was produced. During electrolysis, the electrolytic current density is 1.5 A / dm ² , the electrolysis temperature is 88 ° C., the electrolysis voltage at the end of electrolysis is 5.5 V, and manganese dioxide particles in the sulfuric acid-manganese sulfate mixed solution in the electrolytic cell Was 50 mg / L and the sulfuric acid concentration was 32.0 g / L.

  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 evaluation results of the physical properties of this electrolytic manganese dioxide are shown in Table 1, and the XRD pattern is shown in FIG.

実施例２
実施例１において、電解温度が８４℃、電解槽内の硫酸−硫酸マンガン混合溶液中の硫酸濃度が４０ｇ／Ｌで５時間電解したことを除き、実施例１と同様な電解を行った。この時の電解終了時の電解電圧は７．６Ｖであった。

Example 2
In Example 1, electrolysis was performed in the same manner as in Example 1 except that electrolysis was performed at an electrolysis temperature of 84 ° C. and a sulfuric acid concentration in the sulfuric acid-manganese sulfate mixed solution in the electrolytic bath at 40 g / L for 5 hours. The electrolysis voltage at the end of electrolysis at this time was 7.6V.

  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 evaluation results of the physical properties and high-rate discharge characteristics of this electrolytic manganese dioxide are shown in Table 1, the XRD pattern is shown in FIG. 2, and the FE-SEM image (300,000 times) is shown in FIG.

Example 3
In Example 1, electrolysis was performed in the same manner as in Example 1 except that electrolysis was performed at 84 ° C. for 3 hours. The electrolysis voltage at the end of electrolysis at this time was 9.3V.

  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.

Comparative Example 1
Electrolyzed manganese dioxide is produced by continuously adding a replenishing manganese sulfate solution containing no manganese oxide particles and having a manganese ion concentration of 45 g / L into an electrolytic cell containing a sulfuric acid-manganese sulfate mixed solution for 14 days to produce electrolytic manganese dioxide did. During electrolysis, the electrolysis current density is 0.59 A / dm ² , the electrolysis temperature is 96 ° C., the electrolysis voltage at the end of electrolysis is 2.6 V, and the sulfuric acid concentration in the sulfuric acid-manganese sulfate mixed solution in the electrolytic cell is It was 35.0 g / L.

  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, the XRD pattern is shown in FIG. 2, and the FE-SEM image (300,000 times) is shown in FIG.

Comparative example 2
Comparative Example 1 except that the electrolysis current density was 0.5 A / dm ² , the electrolysis temperature was 92 ° C., and the sulfuric acid concentration in the sulfuric acid-manganese sulfate mixed solution in the electrolytic cell was 40 g / L, and electrolysis was performed for 24 hours. Similar electrolysis was performed. The electrolytic voltage at the end of the electrolysis at this time was 1.8V.

  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 evaluation results of the physical properties and high-rate discharge characteristics of this electrolytic manganese dioxide are shown in Table 1, and the XRD pattern is shown in FIG.

Comparative example 3
The same electrolysis as in Example 1 was performed except that the electrolysis temperature was 96 ° C. for 24 hours. The electrolysis voltage at the end of electrolysis at this time was 2.0V.

  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.

Comparative example 4
Commercially available electrolytic manganese dioxide (trade name: HH-S, manufactured by Tosoh Corporation) was pulverized with a jet mill to produce electrolytic manganese dioxide particles having an average particle size (volume average particle size) of 0.63 μm. The obtained electrolytic manganese dioxide particles were used as manganese oxide particles. The manganese oxide particles were dispersed in water to a concentration of 30 g / L to obtain a slurry liquid.

A sulfuric acid-manganese sulfate mixed solution was used as the electrolytic solution. In addition to continuously adding the slurry solution to the electrolyte solution so that the concentration of manganese oxide particles in the electrolyte solution is 30 mg / L, the sulfuric acid concentration in the electrolyte solution is 25 g / L. Thus, electrolysis was performed while adding a supplemental manganese sulfate solution having a manganese ion concentration of 40 g / L to the electrolyte solution. The electrolysis conditions were an electrolysis current density of 1.5 A / dm ² , an electrolysis temperature of 96 ° C., and an electrolysis period of 4 days. The electrolysis voltage at the end of electrolysis in this comparative example was 3.48V. The physical properties of this electrolytic manganese dioxide are shown in Table 1, and the XRD pattern is shown in FIG.

  Since the electrolytic manganese dioxide 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 (4)

Ri der following pore volume 100nm exceeds the pore diameter 5nm is 0.003 cm ³ / g or more, and, 5nm or less of the pore volume or pore diameter 2nm is Ru der less than 0.004 cm ³ / g The electrolytic manganese dioxide used for the positive electrode active material for batteries characterized by the above-mentioned . ^{2. The} electrolytic manganese dioxide used in the positive electrode active material for a battery according to claim 1, 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. A method for producing electrolytic manganese dioxide in which manganese oxide is suspended in a sulfuric acid-manganese sulfate mixed solution, wherein manganese oxide particles are continuously mixed in a sulfuric acid-manganese sulfate mixed solution, The manganese oxide particles have a concentration of 5 mg / L or more and 100 mg / L or less, an electrolysis temperature of 80 ° C. or more and less than 96 ° C., an electrolysis current density of 0.5 A / dm ² or more and 1.7 A / dm ² or less , and an end voltage. The method for producing electrolytic manganese dioxide used for the positive electrode active material for a battery according to claim 1 or 2 , wherein electrodeposition is performed at a high electrolysis voltage of 5.0 V or more . A battery positive electrode active material comprising the electrolytic manganese dioxide used in the battery positive electrode active material according to claim 1 .

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