JP2006108083A - Manganese oxide for anode active substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manganese oxide which can realize a battery more excellent in high rate performance than a conventional battery. <P>SOLUTION: The manganese oxide is expressed by a composition formula, MnS<SB>a</SB>H<SB>b</SB>Me<SB>x</SB>O<SB>c</SB>zH<SB>2</SB>O, where Me is one kind of Ti, Ca, Mg, Ln or a combination of two or more kinds of them, an open circuit potential is 250 mV or more, and the open circuit potential is measured at a temperature of 20°C by using a mercury oxide (Hg/HgO) as a reference electrode and 40% KOH as an electrolyte. If the open circuit voltage is 250 mV or more, the manganese oxide used as an anode active substance can realize the battery excellent in the high rate performance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a manganese oxide used as a positive electrode active material for a battery.

  Manganese oxides are widely used as positive electrode active materials such as nickel manganese batteries, alkaline batteries, and manganese lithium batteries. Among them, electrolytic manganese dioxide is relatively inexpensive and can realize a battery with a high discharge capacity. In recent years, alkaline batteries using this as a positive electrode active material are digital cameras, digital video cameras, cellular phones, PDAs, and the like. It is widely used as a drive power source for electronic equipment.

  Recently, with higher performance of electronic devices, manganese oxides used as positive electrode active materials have been required to have higher high-rate characteristics, that is, continuous discharge characteristics at high rates. When the electrolytic manganese dioxide is used as a positive electrode active material of a battery, there is a problem that when the discharge current is increased, the utilization rate of the electrolytic manganese dioxide is reduced and a large current cannot be efficiently extracted. Therefore, various proposals have been made for improving the high rate characteristics.

  For example, in Patent Document 1, α-type manganese dioxide having ammonia obtained by electrolyzing an electrolytic solution in which ammonium salt is added to manganese sulfate and a sulfuric acid solution is neutralized with an aqueous lithium salt solution, or mixed with a lithium salt. Thus, it has been proposed to be used as a positive electrode material for a lithium secondary battery.

  Patent Document 2 proposes that electrolytic manganese dioxide having a mole number of water removed by heat treatment in a range not less than 120 ° C. and not exceeding 400 ° C. be 0.16 or more per mole of Mn atoms is used for the positive electrode. Has been.

Patent Document 3 discloses an electrolytic manganese dioxide powder having a maximum particle size of 100 μm or less, a number of particles of 1 μm or less of less than 15%, and a median diameter in the range of 20 to 60 μm. An electrolytic manganese dioxide powder having a specific surface area of 50 m ² / g or more measured by a mixed gas adsorption method of nitrogen and helium after deaeration at 150 ° C. has been proposed.

  Patent Document 4 discloses an electrolytic manganese dioxide powder having a maximum particle diameter of 100 μm or less, the number of particles of 1 μm or less being less than 15%, and a median diameter in the range of 20 to 60 μm. In the measurement using CuKα as the X-ray source, an electrolytic manganese dioxide powder having a large microcrystal size in which the half width of the diffraction surface having a Miller index of (110) is less than 3.5 ° has been proposed.

  In Patent Document 5, as a positive electrode mixture for an alkaline manganese battery with improved high-rate intermittent performance, the surface sulfuric acid amount is 0.10% by weight or more, and the surface alkali metal amount is less than 0.20% by weight. Manganese dioxide is disclosed.

  Patent Document 6 proposes a method for enhancing high-rate characteristics by increasing the specific surface area of electrified manganese dioxide and increasing the reaction area by containing titanium in electrolytic manganese dioxide in an amount of 0.001 to 3.0% by weight. .

  Furthermore, Patent Document 7 discloses an electrolytic manganese dioxide capable of improving the high rate characteristics, containing 1.3 to 1.6% by weight of sulfate radicals.

Japanese Patent Laid-Open No. 5-21062 Japanese Patent Laid-Open No. 5-174841 JP 2002-289185 A JP 2002-289186 A JP 2002-304990 A JP2003-163003 JP 2004-47445 A

  The present invention aims to provide a manganese oxide capable of realizing excellent high-rate characteristics based on new knowledge obtained as a result of research on manganese oxide from a point of view different from conventional ones. .

The invention, formula _{MnS a H b Me x O c} · zH 2 O ( However, Me: Ti, Ca, Mg , Ln ( one or two or more combinations of lanthanoid)) manganese oxide represented by There,
a is 0.010 or more and 0.015 or less,
b is 0.30 or more and 0.40 or less,
c is 1.8 or more and 2.3 or less,
x is 0 or greater than 0 and less than or equal to 0.015;
z is a value greater than 0;
Using mercury oxide (Hg / HgO) as the reference electrode and 40% KOH as the electrolyte, the open circuit potential of the manganese oxide measured at 20 ° C. is 250 mV or more, or manganese oxide: graphite = 94: 6 When graphite was mixed at a ratio, the open circuit potential of the mixture of manganese oxide and graphite measured at 20 ° C. using mercury oxide (Hg / HgO) for the reference electrode and 40% KOH for the electrolyte was A manganese oxide characterized by being 230 mV or higher is proposed.

Since the manganese oxide of the present invention has a high open circuit potential (also referred to as OCP), it has a high rate characteristic that can maintain a long discharge duration even when the discharge voltage is high, that is, even in the use of a high rate region. .
By incorporating a predetermined amount of “S” and “H” into the manganese oxide, protons (H ⁺ ) are supplied directly and quickly from the manganese oxide during the discharge reaction, and the discharge reaction ( It is considered that a battery (for example, an alkaline battery) excellent in high rate characteristics can be realized.
Further, when “S” to “Me” are incorporated during the crystal growth of the manganese oxide, this acts as a control factor during the crystal growth, and the high rate characteristics are further improved. Although the detailed mechanism is unknown, it is likely that “S” and “Me” incorporated during the crystal growth of manganese oxide act as regulators during crystal growth, and supply of discharge reactants including protons (H ⁺ ) It is considered that excellent high-rate characteristics can be realized because the discharge product is also smoothly diffused at the same time. However, if “S” or “Me” above a certain amount is present, diffusion of protons (H ⁺ ) is inhibited, so it is considered that it is important to make the amounts of “S” and “Me” appropriate. .
As described above, the manganese oxide of the present invention has a high open circuit potential in a predetermined composition and has a high potential as a positive electrode active material. Therefore, by using this as a positive electrode active material of a battery, high output is expressed. In addition to being able to construct a possible battery, the selection range of the negative electrode active material and the electrolyte can be greatly expanded.

  In the present invention, the term “high rate” refers to a high rate in the use area of 400 mA or more (corresponding to about 1300 mA in LR06 and ZR06) in the case of an alkaline battery (LR06) and a nickel manganese battery (ZR06). In the test described later, the high rate characteristic was examined by continuously discharging a current of 25 mA while maintaining a predetermined voltage in the half cell.

In the composition formula MnS _a H _b Me _x O _c · zH ₂ O of the present invention, “S”, “H” and “Me” are different from those added after the fact and present in a mixed state. Means a state in which peaks of “S”, “H”, and “Me” are not observed in X-ray diffraction, and a state in which the peaks are contained integrally with manganese oxide.

Further, "z" in the composition formula _{MnS a H b Me x O c} · zH 2 O is the weight loss per mole of manganese oxide when manganese oxide is dried for 2 hours at 110 ° C. in H ₂ O It is the value converted into the number of moles. This “H ₂ O” is water that can be evaporated by heat drying at 110 ° C., that is, water contained in the manganese oxide in the H ₂ O state. Is different. Moreover, although the water | moisture content which evaporates when a manganese oxide is heated at 200-400 degreeC is called combined water etc., since this combined water does not evaporate by the heat drying at 110 degreeC, it differs from combined water.

In this specification, “X to Y” (X and Y are arbitrary numbers) means “X or more and Y or less” unless otherwise specified, and “preferably larger than X and smaller than Y”. Is included.

  Next, embodiments of the present invention will be described, but the scope of the present invention is not limited to the embodiments described below.

The manganese oxide of the present invention is a manganese oxide represented by the composition formula MnS _a H _b Me _x O _c · zH ₂ O.

  The manganese oxide of the present invention may be any of natural manganese oxide, chemically synthesized manganese oxide, electrolytic manganese oxide, and other manganese oxides as long as the above composition is satisfied. From the viewpoint of easy realization, a manganese oxide obtained by electrolysis of a manganese sulfate solution (precipitation) is preferable.

In the above composition formula, “a” as the molar ratio of S is important to be 0.010 or more and 0.015 or less, and preferably 0.012 or more and 0.014 or less. If the molar ratio a of S is a case where manganese oxide is produced by an electrolytic method, for example, the design of an electrolytic device (including the case where the upper layer of the electrolytic solution is a high temperature layer and the lower layer is a low temperature layer), It can be adjusted according to sulfuric acid concentration, electrolysis conditions, and the like. However, it is not limited to this method.
The quantification of S element can be measured using an ICP analyzer (JIS K 1467: 2003).

In the above composition formula, “b” as the molar ratio of H is important to be 0.30 or more and 0.4 or less, and preferably 0.33 or more and 0.37 or less. The molar ratio b of H is, for example, the design of an electrolysis apparatus (including the case where the upper layer of the electrolyte is a high temperature layer and the lower layer is a low temperature layer), if the manganese oxide is produced by an electrolytic method, It can be adjusted according to sulfuric acid concentration, electrolysis conditions, and the like. However, it is not limited to this method.
The amount of H element is determined by measuring the amount of water released from the sample when heated from 110 to 500 ° C. in a nitrogen atmosphere with a Karl Fischer moisture meter, and then heating and drying at 110 ° C. from the obtained amount of water. It can be calculated based on a value excluding the amount of water released.
In addition, H ⁺ , OH ⁻ , and H ₂ O can be considered as the existence state of H in the manganese oxide. However, when the sample is heated to 500 ° C., no significant decrease is observed in the MnOx value. the absolute amount will almost no protons evaporation oxygen as the capture H ₂ O (H ^+), mainly OH ^-, is believed to be present as H ₂ O.

Furthermore, it is preferable that the amount of H with respect to S is a predetermined ratio. Specifically, the ratio b / a of H to S is preferably 35 or less, more preferably 20 or more and 35 or less, and particularly preferably 24 or more and 33 or less.
The ratio b / a of H to S is, for example, the design of an electrolytic device (including the case where the upper layer of the electrolytic solution is a high temperature layer and the lower layer is a low temperature layer), and electrolysis. It can be adjusted according to the sulfuric acid concentration of the liquid, electrolysis conditions, and the like. However, it is not limited to this method.

  In the above composition formula, it is important that “c” as the molar ratio of O is 1.8 or more and 2.3 or less. The molar ratio c of O can be adjusted by changing the contents of S, H, and Me. However, it is not limited to this method.

In the above composition formula, “Me” is one or a combination of two or more of Ti, Ca, Mg, and Ln (lanthanoid), and distinguishes the inevitable impurities contained in the raw material from those intentionally added. It is not a thing.
It is important that “x” as the molar ratio of “Me” is 0 or more than 0 and 0.015 or less, preferably 0.000001 or more and 0.013 or less, more preferably 0.00001 or more and 0.0. 013 or less. That is, Me does not necessarily need to be contained, but if it is contained in a small amount, it acts as a control factor during crystal growth and can further improve the high rate characteristics. However, as described above, if there is too much “Me”, diffusion of protons (H ⁺ ) is inhibited, so it is important to make the amount appropriate.

In the above composition formula, “z” means the molar ratio of water contained in the state of H ₂ O in the manganese oxide, and the weight loss when sufficiently heated and dried at 110 ° C. It is a value converted to the number of moles of H ₂ O per mole, and if it exists even slightly, that is, a value exceeding 0 is sufficient, but it is preferably 0.2 or less, particularly preferably 0.15 or less.

  Among the manganese oxides having the above composition, the ratio of the peak intensity I (310) on the (310) plane and the peak intensity I (221) on the (221) plane measured by X-ray diffraction (XRD) is I It is preferred that (310) / I (221) <0.4, especially <0.38, especially <0.35. The ratio of the peak intensity I (310) to the peak intensity I (221) is smaller than 0.4 is an index of how much the crystal structure is disturbed, in other words, S, H and Me are contained in the manganese oxide. It is an index of how much is contained. Therefore, if I (310) / I (221) <0.4, it is one indication that S, H, and Me are sufficiently taken into the manganese oxide. There are exceptions.

Further, the (110) plane spacing d value measured by X-ray diffraction (XRD) is 4.01 mm or more, particularly 4.01 to 4.09, and particularly 4.01 to 4.08. preferable.
The (110) plane spacing d value is a value that changes due to the bonding state of Mn and O. Although the detailed reason is unknown, it has been confirmed that the high rate characteristic is further improved if the inter-surface distance d value is 4.01 mm or more.

In the manganese oxide of the present invention, it is important that the open circuit potential of the manganese oxide measured at 20 ° C. is 250 mV or more by using mercury oxide (Hg / HgO) for the reference electrode and 40% KOH for the electrolytic solution. And preferably has a characteristic of 250 mV to 350 mV, particularly preferably 260 mV to 350 mV.
Further, when mixed with graphite to form a positive electrode mixture, mercury oxide (Hg / HgO) is used for the reference electrode and 40% for the electrolytic solution when graphite is mixed at a ratio of manganese oxide: graphite = 94: 6. It is important that the open circuit potential of the mixture of manganese oxide and graphite measured at 20 ° C. using KOH is 230 mV or more, preferably 230 mV or more and 330 mV or less, particularly preferably 240 mV or more and 330 mV or less. It has the characteristics of.

(Manufacturing method of manganese oxide)
The method for producing a manganese oxide according to the present invention includes, for example, a method of electrolyzing an electrolytic solution composed of manganese sulfate and a sulfuric acid solution, and forming a high temperature upper electrolyte layer and a low temperature lower electrolyte layer in an electrolytic cell. At the same time, by adjusting the electrolytic current density, the sulfuric acid concentration of the electrolytic solution, etc., a manganese oxide having a target composition can be produced. Hereinafter, this manufacturing method will be described in more detail.

As the electrode, titanium, a titanium alloy, a lead plate, a graphite plate, or the like may be used for the anode, and carbon or the like may be used for the cathode. However, it is not limited to these.
The temperature of the upper electrolyte layer is 90 to 100 ° C., and the temperature of the low temperature lower electrolyte layer is preferably 60 to 85 ° C., particularly 65 to 84 ° C. The means for forming the high-temperature upper electrolyte layer and the low-temperature lower electrolyte layer in this way is not particularly limited, but as an example, the replenisher is fed upward from the bottom of the electrolytic cell. A means for adjusting the position of the heat exchanger and its heating temperature can be introduced while an introduction pipe is provided to supply an electrolyte solution at a predetermined temperature at a predetermined liquid feeding speed.

It is preferable to adjust the sulfuric acid concentration, manganese concentration, and electrolytic current density of the electrolytic solution so as to obtain a desired composition by balancing these. Each value is not limited as an absolute value, but as one guideline, the sulfuric acid concentration of the electrolytic solution is preferably 30 to 100 g / L, particularly 55 to 75 g / L, and the manganese concentration in the electrolytic solution is It is preferably 10 to 39 g / L, particularly 10 to 35 g / L, and the electrolysis current density is preferably 20 to 100 A / m ² , particularly preferably 30 to 70 A / m ² .
The liquid feeding speed, that is, the replenishing speed of the electrolytic solution may be set so that the sulfuric acid concentration of the electrolytic solution is maintained at a predetermined concentration.

  When Me is contained, a raw material containing a large amount of Me may be selected, or a Me compound may be added to the electrolytic solution. In this case, examples of the Me compound include a sulfate compound, a nitrate compound, and a chloride compound. Specifically, a method of dissolving and adding these Me compounds in a manganese sulfate solution as a replenisher is preferable.

In general, the deposit of manganese oxide electrodeposited on the anode is peeled off, and pulverized and classified as necessary. However, pulverization and classification are not necessarily required.
As a pulverization method at this time, it is roughly pulverized by a jaw crusher or the like to be pulverized into a mass of several centimeters, and further pulverized by a roller mill or the like for further pulverization. The pulverization may be performed by pulverization, dry ball milling, or the like.
The classification method may be a method of removing fine powder by dispersing the manganese oxide powder obtained by pulverization in pure water, filtering the precipitated powder and drying, etc. it can.
The finely pulverized manganese oxide powder is washed and dried using water or alkali in order to remove free acid remaining on the surface, if necessary.

There are various methods for increasing the open circuit potential. In the manganese oxide represented by the composition formula MnS _a H _b Me _x O _c .zH ₂ O, the amount of S is increased, and H Reduce the amount of. That is, if b / a is relatively small, preferably b / a is 35 or less, especially 20 or more and 35 or less, particularly 24 or more and 33 or less, there is an exception, but generally OCP is increased. Can do. As specific means, in the production conditions in which the electrolytic oxidation reaction of Mn is performed slowly or in a small amount, adjusting these balances in the direction of increasing the sulfuric acid concentration, decreasing the Mn concentration, or decreasing the current density, As the pure manganese dioxide increases, b / a decreases, and OCP can be increased.
OCP can also be increased by treating manganese oxide obtained by electrolysis with an oxidizing agent. As a method of treating manganese oxide with an oxidizing agent, for example, a method of immersing manganese oxide in a permanganese aqueous solution and washing with water can be given.

  In addition, the manufacturing method mentioned above is an example for manufacturing the manganese oxide of this invention, and is not limited to this. It is considered that the manganese oxide can be produced by another method capable of producing manganese oxide so that a predetermined amount of S, H, and, in some cases, Me is contained in the manganese oxide.

(Use)
The manganese oxide of the present invention can be suitably used as a positive electrode active material for nickel manganese batteries, alkaline batteries, manganese lithium batteries, and the like. In particular, since the manganese oxide of the present invention has an open circuit potential of 250 mV or more, it has excellent high rate characteristics. Batteries using this as a positive electrode active material include digital cameras, digital video cameras, cellular phones, PDAs, and the like. It can be suitably used as a drive power source for electronic equipment.

  In addition, the manganese oxide of the present invention has an open circuit potential of 230 mV or more when graphite is mixed, and is therefore suitable as a positive electrode active material material for nickel manganese batteries. That is, if a nickel manganese battery is constituted by using a mixed material obtained by adding nickel oxyhydroxide and graphite to the manganese oxide of the present invention as a positive electrode active material, a battery capable of realizing high output and high output can be provided. can do.

The negative electrode active material of the battery may be a conventionally known material, and is not particularly limited, but zinc or the like is generally used for a manganese battery or an alkaline manganese battery, and lithium or the like is generally used for a lithium battery.
The electrolyte constituting the battery may also be a conventionally known electrolyte, and is not particularly limited. For example, a manganese battery uses zinc chloride or ammonium chloride, an alkaline battery uses potassium hydroxide, and a lithium battery uses an organic solvent solution of a lithium salt. It is common.

An example of constituting an alkaline manganese battery using the manganese oxide of the present invention will be described. For example, manganese oxide and graphite as a conductive agent are kneaded, and this is compression molded and placed inside the positive electrode can. Moreover, it can comprise so that the negative electrode material which consists of gelatinous zinc powder may be provided inside a positive electrode active material through a separator. However, it is not limited to this configuration example.
In the case of constituting a nickel manganese battery, for example, manganese oxide, nickel oxyhydroxide, and graphite as a conductive agent may be kneaded and used as a positive electrode mixture.

Example 1
Using a 5L beaker as an electrolytic cell, a titanium plate as an anode and a graphite plate as a cathode are alternately suspended in the electrolytic cell. The introduction pipe was provided. At this time, an electrode having a length such that the distance from the bottom of the electrolytic cell to the lower end of the electrode plate is 0.2 with respect to the length 1 of the electrode plate immersed in the electrolytic solution.
The electrolytic replenisher adjusted to 60 ° C. is poured into the electrolytic cell through the introduction tube, and the electrolysis is adjusted so that the composition of the electrolytic solution is 35 g / L manganese and 60 g / L sulfuric acid. While adjusting the installation position and heating temperature, the temperature of the upper layer of the electrolyte (upper layer including the entire electrode plate immersed in the electrolyte) is maintained at 95 to 98 ° C., while the lower layer of the electrolyte (lower layer than the electrode plate) ) Was maintained for 10 days at a current density of 55 A / m ² while maintaining the temperature at 65-80 ° C.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

  Manganese oxide obtained by electrolytic deposition was coarsely pulverized, washed with hot water at 90 ° C. for 30 minutes, decanted, further stirred and washed with the same amount of water for 24 hours, and decanted again. The manganese oxide obtained here is neutralized with caustic soda so that the JIS pH of the manganese oxide becomes 3.5, then dried by heating at 95 ° C. for 0.5 hour, and the average particle size becomes about 35 μm. Finely pulverized to obtain a manganese oxide powder.

(Example 2)
In the same electrolytic cell as in Example 1, for the length 1 of the electrode plate immersed in the electrolytic solution, an electrode having a length from which the distance from the electrolytic cell bottom to the lower electrode plate is 0.4 is used. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed (see Table 1 for details).

(Example 3)
A manganese sulfate electrolytic replenisher composed of a manganese raw material containing a large amount of Ca was prepared and supplied, and electrolytic deposition, pulverization, washing, and drying were performed so that the other conditions were the same as in Example 1 (for details, see Table 1). checking).

Example 4
In addition to adjusting and supplying a manganese sulfate electrolytic replenisher composed of a manganese raw material containing a large amount of Ln, the composition of the electrolytic solution is adjusted to 30 g / L manganese and 70 g / L sulfuric acid when electrolyzing, and the heat exchanger By adjusting the arrangement position and the heating temperature, electrolysis was performed at a current density of 55 A / m ² for 10 days while maintaining the temperature of the upper layer of the electrolyte at 95 to 98 ° C. and the temperature of the lower layer at 65 to 80 ° C. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed. (See Table 1 for details).

(Example 5)
While adding 0.25 g / L of Ti and 0.25 g / L of Ln to the electrolytic solution and the electrolytic replenisher, the composition of the electrolytic solution is adjusted to 20 g / L of manganese and 80 g / L of sulfuric acid when electrolyzing, By adjusting the position of the heat exchanger and the heating temperature, the temperature of the upper layer of the electrolytic solution is kept at 95 to 98 ° C., and the temperature of the lower layer is kept at 65 to 80 ° C., while the current density is 10 A at 55 A / m ² . Electrolyzed for days. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed (see Table 1 for details).

(Example 6)
In the electrolysis, the composition of the electrolytic solution is adjusted to 20 g / L of manganese and 80 g / L of sulfuric acid, the position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (soaked in the electrolytic solution) while keeping the temperature of the upper layer portion) containing the entire are electrode plates 87 to 93 ° C., while maintaining the temperature of the lower layer (lower layer portion from the electrode plate) in the electrolyte 65-80 ° C., a current density of 30A / m ² 10 The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Example 7)
During electrolysis, the composition of the electrolytic solution is adjusted to 10 g / L of manganese and 30 g / L of sulfuric acid, and the arrangement position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (immersed in the electrolytic solution) 10) at a current density of 30 A / m ² while maintaining the temperature of the lower layer of the electrolyte (lower layer from the electrode plate) at 65 to 80 ° C. The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Example 8)
During electrolysis, the composition of the electrolytic solution is adjusted to 10 g / L of manganese and 30 g / L of sulfuric acid, and the arrangement position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (immersed in the electrolytic solution) while keeping the temperature of the upper layer portion) containing the entire are electrode plates 87 to 93 ° C., while maintaining the temperature of the lower layer (lower layer portion from the electrode plate) in the electrolyte 65-80 ° C., a current density of 30A / m ² 10 The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

Example 9
During electrolysis, the composition of the electrolytic solution is adjusted to 30 g / L of manganese and 60 g / L of sulfuric acid, and the arrangement position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (immersed in the electrolytic solution) 10) at a current density of 60 A / m ² while maintaining the temperature of the lower layer of the electrolyte (lower layer from the electrode plate) at 65 to 80 ° C. The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Example 10)
When 0.25 g / L of Ti is added to the electrolytic solution and the electrolytic replenishing solution, and the electrolysis is performed, the composition of the electrolytic solution is adjusted to 30 g / L of manganese and 60 g / L of sulfuric acid. By adjusting the heating temperature, electrolysis was performed at a current density of 60 A / m ² for 10 days while maintaining the temperature of the upper layer of the electrolyte at 95 to 98 ° C. and the temperature of the lower layer at 65 to 80 ° C. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed (see Table 1 for details).

(Example 11)
When electrolyzing, the composition of the electrolytic solution was adjusted to 40 g / L of manganese and 55 g / L of sulfuric acid, and electrolysis was carried out at a current density of 55 A / m ² for 10 days. Manganese oxide was obtained. Next, 50 g of manganese oxide obtained by electrolytic deposition was put into 300 ml of 0.05 mol KMnO 4 aqueous solution (oxidant aqueous solution, 30 ° C.) and stirred for 1 hour with a magnetic stirrer, then washed with water, 107 ° C. And dried. After drying, coarsely pulverized, washed with hot water at 90 ° C. for 30 minutes, decanted, further stirred and washed with the same amount of water for 24 hours, and decanted again. The manganese oxide obtained here is neutralized with caustic soda so that the JIS pH of the manganese oxide becomes 3.5, then dried by heating at 95 ° C. for 0.5 hour, and the average particle size becomes about 35 μm. Finely pulverized to obtain a manganese oxide powder.
The measured values of manganese concentration, sulfuric acid concentration, and current density are shown in Table 1.

(Example 12)
A manganese sulfate electrolytic replenisher composed of a manganese raw material containing a large amount of Mg was prepared and supplied, and electrolytic deposition, pulverization, washing, and drying were performed so that other conditions were the same as in Example 1 (for details, see Table 1). checking).

(Example 13)
Compared to Example 12, a manganese sulfate electrolytic replenisher composed of a manganese raw material further containing Mg is prepared and supplied, and electrolytic deposition, pulverization, washing, and drying are performed so that other conditions are the same as in Example 12. (See Table 1 for details).

(Example 14)
When 0.56 g / L of Ti is added to the electrolytic solution and the electrolytic replenisher, and the electrolysis is performed, the composition of the electrolytic solution is adjusted to 30 g / L manganese and 60 g / L sulfuric acid. By adjusting the heating temperature, electrolysis was performed at a current density of 60 A / m ² for 10 days while maintaining the temperature of the upper layer of the electrolyte at 95 to 98 ° C. and the temperature of the lower layer at 65 to 80 ° C. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed (see Table 1 for details).

(Example 15)
Compared to Example 4, a manganese sulfate electrolytic replenisher composed of a manganese raw material further containing Ln is prepared and supplied, and the composition of the electrolytic solution is adjusted to 30 g / L manganese and 70 g / L sulfuric acid during electrolysis. At the same time, by adjusting the arrangement position of the heat exchanger and the heating temperature, the temperature of the upper layer of the electrolytic solution is maintained at 95 to 98 ° C., and the temperature of the lower layer is maintained at 65 to 80 ° C. ² for 10 days. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed. (See Table 1 for details).

(Example 16)
During electrolysis, the composition of the electrolytic solution is adjusted to 20 g / L of manganese and 90 g / L of sulfuric acid, the position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (immersed in the electrolytic solution) while keeping the temperature of the upper layer portion) containing the entire are electrode plates 87 to 93 ° C., while maintaining the temperature of the lower layer (lower layer portion from the electrode plate) in the electrolyte 65-80 ° C., a current density of 30A / m ² 10 The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Example 17)
In the electrolysis, the composition of the electrolytic solution is adjusted to be 30 g / L of manganese and 30 g / L of sulfuric acid, the position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (soaked in the electrolytic solution) 10) at a current density of 30 A / m ² while maintaining the temperature of the lower layer of the electrolyte (lower layer part from the electrode plate) at 65 to 80 ° C. The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Comparative Example 1)
In the electrolysis, the composition of the electrolytic solution is adjusted to 50 g / L of manganese and 20 g / L of sulfuric acid, and the temperature of the upper layer of the electrolytic solution is adjusted to 95 to 95 by adjusting the position of the heat exchanger and the heating temperature. Electrolysis was performed at a current density of 55 A / m ² for 10 days while maintaining the temperature at 98 ° C. and the temperature of the lower layer at 65 to 80 ° C. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed (see Table 1 for details).

(Comparative Example 2)
In the electrolysis, the composition of the electrolytic solution was adjusted to 45 g / L manganese and 30 g / L sulfuric acid, the current density was set to 55 A / m ² , and the other conditions were the same as in Comparative Example 1. It was discharged and crushed, washed and dried (see Table 1 for details).

(Comparative Example 3)
In the electrolysis, the composition of the electrolytic solution was adjusted to 40 g / L manganese and 50 g / L sulfuric acid, and the current density was set to 55 A / m ² , and the other conditions were the same as in Comparative Example 1. It was discharged and crushed, washed and dried (see Table 1 for details).

(Comparative Example 4)
0.25 g / L of Ti is added to the electrolytic solution and the electrolytic replenishing solution, and the composition of the electrolytic solution is adjusted to 40 g / L manganese and 30 g / L sulfuric acid when electrolyzing, and the current density is set to 55 A / m ² . Then, electrolytic deposition and pulverization / washing / drying were performed so that the other conditions were the same as those in Comparative Example 1 (see Table 1 for details).

(Comparative Example 5)
Compared to Example 13, a manganese sulfate electrolytic replenisher composed of a manganese raw material further containing Mg is prepared and supplied, and electrolytic deposition and pulverization / washing / drying are performed so that other conditions are the same as in Example 13. (See Table 1 for details).

(Comparative Example 6)
4. 4. 30 g / L of Ti was added to the electrolytic solution and the electrolytic replenisher, and the composition of the electrolytic solution was adjusted to 30 g / L of manganese and 60 g / L of sulfuric acid when electrolyzing, and the position of the heat exchanger and By adjusting the heating temperature, electrolysis was performed at a current density of 60 A / m ² for 10 days while maintaining the temperature of the upper layer of the electrolyte at 95 to 98 ° C. and the temperature of the lower layer at 65 to 80 ° C. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed (see Table 1 for details).

(Comparative Example 7)
Compared to Example 15, a manganese sulfate electrolytic replenisher composed of a manganese raw material further containing Ln is adjusted and supplied, and the composition of the electrolytic solution is adjusted to 30 g manganese and 70 g sulfuric acid when electrolyzing. At the same time, by adjusting the arrangement position of the heat exchanger and the heating temperature, the temperature of the upper layer of the electrolytic solution is maintained at 95 to 98 ° C., and the temperature of the lower layer is maintained at 65 to 80 ° C., while the current density is 55 A / m. ² for 10 days. The other conditions were the same as in Example 1, and electrolytic deposition and pulverization / washing / drying were performed. (See Table 1 for details).

(Comparative Example 8)
In the electrolysis, the composition of the electrolyte is adjusted to 15 g / L manganese and 100 g / L sulfuric acid, and the position and heating temperature of the heat exchanger are adjusted, and the upper layer of the electrolyte (immersed in the electrolyte) 10) at a current density of 30 A / m ² while maintaining the temperature of the lower layer of the electrolyte (lower layer part from the electrode plate) at 65 to 80 ° C. The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Comparative Example 9)
In the electrolysis, the composition of the electrolytic solution is adjusted to be 30 g / L of manganese and 30 g / L of sulfuric acid, the position of the heat exchanger and the heating temperature are adjusted, and the upper layer of the electrolytic solution (soaked in the electrolytic solution) 10) at a current density of 20 A / m ² while maintaining the temperature of the lower layer of the electrolyte (lower layer from the electrode plate) at 65 to 80 ° C. The electrolysis was performed for the same day, and the other points were the same as in Example 1.
Table 1 shows the average values of actually measured values of manganese concentration, sulfuric acid concentration, and current density.

(Reference Example 1)
A sample of Reference Example 1 was prepared by storing the manganese oxide powder obtained in Example 6 for 12 months at room temperature.

From the results of Example 3-5, Example 10 and Example 12-15, it can be seen that excellent characteristics (effects) can be obtained when Ti, Ca, Ln, and Mg are included. On the other hand, when the results of Comparative Examples 5 and 7 are seen, it is recognized that if the amount of Me is too large, the characteristic (effect) is lowered. From such a point, it is considered that the preferable range of the Me amount (molar ratio) is 0.015 or less, particularly 0.004 or less (see Example 13).

<Evaluation>
Measurement and evaluation of the manganese oxides obtained in the above Examples and Comparative Examples were performed by the method described below.

(Measurement of water content)
The amount of water released when the manganese oxide powder as a sample was heat-dried at 110 ° C. for 2 hours was measured.

(Quantitative method of H element)
Measure the amount of moisture released by holding the manganese oxide powder as a sample until the water count is stabilized when heated from 110 to 500 ° C. in a nitrogen atmosphere using a Karl Fischer moisture meter, From the amount of water, the amount of water released when heated at 110 ° C. was removed, and the molar ratio of element H was calculated from the amount of water removed.

(Quantitative method of S element)
Based on JIS K 1467: 2003, the amount of S element was measured with an ICP analyzer.

(Me element quantitative method)
Based on JIS K 1467: 2003, the amount of each Me element was measured with an ICP analyzer.

(Measurement of MnO ₂ content and total Mn content)
The MnO ₂ content was measured according to JIS K 1467: 2003. The total amount of Mn was measured by potentiometric titration using KMnO ₄ .

(Measurement of oxygen content)
The MnO _x value was calculated by calculating the Mn oxidation number from the MnO ₂ content and the total Mn amount. Further, assuming that the presence state of S is SO ₄ ^2- , the oxygen amount was calculated from the S amount. Furthermore, the amount of moisture released from the sample when heated from 110 ° C. to 500 ° C. in a nitrogen atmosphere is measured with a Karl Fischer moisture meter, and the obtained moisture amount is released when heated and dried at 110 ° C. The amount of oxygen was calculated based on the value excluding the amount of water. Then, the total amount of oxygen is determined from the total amount of oxygen calculated from the MnO _x value, the amount of oxygen calculated from the S amount, and the amount of water released upon heating and drying, and the molar ratio of the O element is calculated. did.

(XRD measurement method)
Using a Cu tube, an XRD chart was obtained by XRD measurement at a scan range of 0.02 ° and a scan speed of 1 ° / min over a measurement range of 10 to 80 °.
Of the peaks of the obtained XRD chart, (110) plane, (310) plane, (201) plane, (020) plane, (211) plane, (221) when attributed to Ramsdellite (space group: Pnma) Surface smoothing processing, background removal processing and Kα2 removal processing (maximum intensity ratio = 0.500) are performed, and the peak top angle is used to determine the d value of (110) plane, (310) plane / ( The peak intensity ratio I (310) / I (221) of the 221) plane was calculated and shown in Table 2.

(Measurement method of OCP)
0.3 g of the manganese oxide (sample) obtained in the above Examples and Comparative Examples was weighed and filled into a nickel-plated steel can with an open bottom of φ10 mm. This was set on a special die, and a load of 2 ton was applied for 10 seconds with a hydraulic press machine, and then a metal nickel ribbon was spot welded to the bottom.
Insert the filled steel can into a 200 mL beaker, fold and fix the nickel ribbon, inject 40% KOH aqueous solution as the electrolyte, completely immerse the steel can part and let it stand for a day and night. Mercury / mercury oxide) was immersed in the electrolyte, and the potential (open circuit potential: OCP) between the sample and the reference electrode was measured with a digital voltmeter.

(Method for measuring OCP with graphite)
Manganese oxide (sample) obtained in the above examples and comparative examples and graphite were mixed at a predetermined ratio (94: 6), and after thoroughly stirring and mixing with a spoonful in a 200 mL beaker, 0.2 g of this mixture was added. A special die was set and a load of 2 tons was applied for 10 seconds with a hydraulic press machine, and then a metal nickel ribbon was spot welded to the bottom.
Insert the filled steel can into a 200 mL beaker, fold and fix the nickel ribbon, inject 40% KOH aqueous solution as the electrolyte, completely immerse the steel can part and let it stand overnight. / Mercury oxide) was immersed in the electrolytic solution, and the potential (OCP with graphite) between the sample and the reference electrode was measured with a digital voltmeter.

  The circuit potential when graphite was mixed with the manganese oxide obtained in Example 1 at a ratio of 3% by weight, 6% by weight, 12% by weight, and 20% by weight (weight ratio with respect to the amount after mixing). When measured in the same manner as described above, they were 242 mV, 240 mV, 238 mV, and 236 mV, respectively. That is, even with the same manganese oxide, the open circuit potential decreases as the mixing amount of graphite increases, and the ratio increases by about 2 mV if it is 3% by weight, centering on 6% by weight, It was found that if it was 12% by weight, it would be about 2 mV lower. From this, even if the amount of graphite in the battery deviates up and down from 6% by weight, the potential at the amount of graphite of 6% by weight can be estimated from the above tendency.

(Measurement method of half-cell characteristics)
-Alkaline manganese battery-
The manganese oxide (sample) obtained in Examples 1 to 11 and Comparative Examples 1 to 3 and graphite were mixed at a predetermined ratio (94: 6) and thoroughly stirred and mixed with a spoonful in a 200 mL beaker. 0.2 g of the mixed agent was set on a φ10 mm disk making die, and a molded article was obtained by applying a load of 2 ton for 10 seconds with a hydraulic press. This molded product was placed in a nickel-plated steel can with a top opening bottom of φ10 mm, a φ10 mm nickel mesh was placed on the top of the molded product, and then a load of 2 ton was applied for 10 seconds with a hydraulic press to crimp the molded product. Next, the steel can on which the molded product has been pressure-bonded is attached to an acrylic resin model cell, a nickel net with a conductive tab as a counter electrode is attached to the model cell, and a 40% KOH aqueous solution is injected into the model cell. After standing, wire the sample electrode, counter electrode (nickel), and ammeter to a constant current power supply device with a preset current value, and immerse the reference electrode (Hg / HgO) in the electrolyte. The potential between the sample electrode and the reference electrode was measured and recorded with a type voltage recorder.
A 25 mA continuous discharge was performed from the constant current power supply, and when the potential reached the cut-off potential (−0.2 V), the discharge was terminated, and the discharge capacity at −0.2 V was measured.
The half cell characteristics (25 mA) of each Example and Comparative Example are shown in Table 2 in terms of the measured value (discharge capacity) of Comparative Example 3 being 100.

-Nickel manganese battery-
Manganese oxides (samples) obtained in Examples 1 and 2 and Comparative Example 3, nickel oxyhydroxide and graphite were mixed at a predetermined ratio (47: 47: 6), and sufficiently stirred with a spoonful in a 200 mL beaker. After mixing, 0.2 g of this admixture was set on a φ10 mm disk making die, and a molded article was obtained by applying a load of 2 ton for 10 seconds with a hydraulic press. This molded product was placed in a nickel-plated steel can with a top opening bottom of φ10 mm, a φ10 mm nickel mesh was placed on the top of the molded product, and then a load of 2 ton was applied for 10 seconds with a hydraulic press to crimp the molded product. Next, the steel can on which the molded product has been pressure-bonded is attached to an acrylic resin model cell, a nickel net with a conductive tab as a counter electrode is attached to the model cell, and a 40% KOH aqueous solution is injected into the model cell. After standing, wire the sample electrode, counter electrode (nickel), and ammeter to a constant current power supply device with a preset current value, and immerse the reference electrode (Hg / HgO) in the electrolyte. The potential between the sample electrode and the reference electrode was measured and recorded with a type voltage recorder.
The half-cell characteristics (25 mA) of the example are shown in Table 2 as ratios relative to the measured value (discharge capacity) of Comparative Example 3 being 100.
The nickel manganese battery has the same battery configuration as the alkaline battery except that nickel oxyhydroxide is added. In addition, from Examples 1 and 2 and Comparative Example 3, the same effect was confirmed in the nickel manganese battery. From these facts, the effect of the present invention is considered to be the same in the nickel manganese battery.

Claims (4)

A manganese oxide represented by _a composition formula MnS _a H _b Me _x O _c · zH ₂ O (where Me is one or a combination of two or more of Ti, Ca, Mg, and Ln),
a is 0.010 or more and 0.015 or less,
b is 0.30 or more and 0.40 or less,
c is 1.8 or more and 2.3 or less,
x is 0 or greater than 0 and less than or equal to 0.015;
z is a value greater than 0;
A manganese oxide characterized in that an open circuit potential of manganese oxide measured at 20 ° C. is 250 mV or more by using mercury oxide (Hg / HgO) as a reference electrode and 40% KOH as an electrolyte. A manganese oxide represented by _a composition formula MnS _a H _b Me _x O _c · zH ₂ O (where Me is one or a combination of two or more of Ti, Ca, Mg, and Ln),
a is 0.010 or more and 0.015 or less,
b is 0.30 or more and 0.40 or less,
c is 1.8 or more and 2.3 or less,
x is 0 or greater than 0 and less than or equal to 0.015;
z is a value greater than 0;
Manganese oxide: graphite = 94: 6 When graphite is mixed at a ratio of 94: 6, the manganese oxide is measured at 20 ° C. using mercury oxide (Hg / HgO) as a reference electrode and 40% KOH as an electrolyte. A manganese oxide characterized in that the open circuit potential of a mixture of graphite and graphite is 230 mV or more.   The battery provided with the structure which uses the manganese oxide of Claim 1 or 2 as a positive electrode active material. A battery comprising a structure in which a mixed material obtained by mixing nickel oxyhydroxide and graphite with the manganese oxide according to claim 1 or 2 is used as a positive electrode active material.