JP2017197406A - Method for producing nickel-manganese complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing nickel-manganese complex in which a nickel to manganese ratio can be freely set, and nickel and manganese are uniformly distributed, and which is suitable as a raw material of a cathode active material for a lithium secondary battery.SOLUTION: There is provided the method for producing a nickel-manganese complex having a chemical composition represented by a formula NiMnO(OH)(where, 0.225≤x≤0.775 and 0.5≤a≤0.9). The method for producing a nickel-manganese complex comprises: mixing an aqueous solution of a metal salt containing nickel, an aqueous solution of a metal salt containing manganese, an aqueous solution of sodium hydroxide and an oxidant, or an aqueous solution of metal salts containing nickel and manganese, an aqueous solution of sodium hydroxide and an oxidant; and crystallizing a nickel-manganese complex in an atmosphere in which Ni becomes divalent and Mn becomes trivalent.SELECTED DRAWING: Figure 3

Description

  The present invention is suitable as a raw material for a positive electrode material having nickel and manganese, such as a lithium-nickel-manganese composite oxide suitable for a positive electrode material of a lithium secondary battery, and a lithium-nickel-cobalt-manganese composite oxide. The present invention also relates to a method for producing a nickel-manganese composite in which nickel and manganese are uniformly distributed.

  In recent years, lithium-nickel-manganese composite oxides and lithium-nickel-cobalt-manganese composite oxides have attracted attention as high-energy materials as positive electrode active materials for lithium secondary batteries.

These composite oxides are preferably produced using a nickel-manganese composite material in which nickel and manganese are uniformly distributed. For example, an oxidant is used as a precursor of a lithium-nickel-manganese composite oxide. Nickel-manganese composite oxyhydroxide obtained by the coprecipitation method and having a chemical composition formula represented by Ni _{0.25 + α} Mn _0.75-α OOH (where −0.025 ≦ α ≦ 0.025). The thing was disclosed (patent document 1). The nickel-manganese composite oxyhydroxide consists of a single crystal phase with a cadmium hydroxide structure, is stable in the atmosphere, and does not cause segregation of manganese components in general processes such as coprecipitation, washing and drying. That it is a precursor.

  On the other hand, lithium-nickel-cobalt-manganese composite oxides as positive electrode active materials for lithium secondary batteries have been studied in a wide range of compositions with a molar ratio of nickel to manganese of 1: 1 to 5: 3. Therefore, a nickel-manganese composite material that can freely set the ratio of nickel and manganese has been desired.

WO2015 / 008863

  An object of the present invention is to provide a method for producing a nickel-manganese composite in which the ratio of nickel and manganese can be freely set and nickel and manganese are uniformly distributed.

As a result of intensive studies on the method for producing a nickel-manganese composite material, the inventors crystallized the nickel-manganese composite in an atmosphere in which Ni is divalent and Mn is trivalent. It was found that a nickel-manganese composite in which nickel and manganese were uniformly distributed was obtained, and the present invention was completed. That is, the present invention mixes a metal salt aqueous solution containing nickel, a metal salt aqueous solution containing manganese, a caustic soda aqueous solution and an oxidizing agent, or a metal salt aqueous solution containing nickel and manganese, a caustic soda aqueous solution and an oxidizing agent, and Ni is divalent. And the chemical composition formula is characterized in that the nickel-manganese composite is crystallized in an atmosphere where Mn is trivalent, and the chemical composition formula is Ni _x Mn _1-x O _a (OH) _2-a (where, 0.225 ≦ x ≦ 0.775 and 0.5 ≦ a ≦ 0.9).

  Hereinafter, the present invention will be described in detail.

The method for producing a nickel-manganese composite of the present invention comprises mixing a metal salt aqueous solution containing nickel, a metal salt aqueous solution containing manganese, a caustic soda aqueous solution, and an oxidizing agent, so that the chemical composition formula is Ni _x Mn _1-x O _a. (OH) The nickel-manganese composite represented by _2-a crystallizes out.

  In the method for producing a nickel-manganese composite of the present invention, a nickel-containing metal salt aqueous solution, a manganese-containing metal salt aqueous solution, a caustic soda aqueous solution, and an oxidizing agent are mixed to obtain a nickel-manganese composite slurry. The nickel-manganese composite slurry is filtered, washed with water, and dried to obtain a nickel-manganese composite.

  In the method for producing a nickel-manganese composite of the present invention, for example, a metal salt aqueous solution containing nickel, a metal salt aqueous solution containing manganese, a caustic soda aqueous solution, and an oxidizing agent are supplied to a reaction vessel having a certain volume and mixed. Then, after obtaining a nickel-manganese composite, for example, the supply is stopped when the amount of liquid in the reaction vessel reaches a desired value, and a method of extracting the entire amount of the nickel-manganese composite after a certain time is applicable. .

  However, the continuous method of supplying continuously and continuously extracting the produced nickel-manganese composite is a preferable method in terms of economy, for example, the equipment cost is reduced.

  Hereinafter, the present invention will be described in detail by taking a continuous manufacturing method as an example.

  In the method for producing a nickel-manganese composite of the present invention, it is preferable to continuously supply a metal salt aqueous solution containing nickel and a metal salt aqueous solution containing manganese. Further, the ratio of nickel to manganese: X can be controlled by the supply ratio of the metal salt aqueous solution containing nickel and the metal salt aqueous solution containing manganese.

  The supply method of the metal salt aqueous solution containing nickel and the metal salt aqueous solution containing manganese is not particularly limited, and a metal salt aqueous solution in which nickel salt is dissolved and a metal salt aqueous solution in which manganese salt is dissolved are manufactured. Can be charged into the reaction vessel at a constant ratio. At this time, each metal salt aqueous solution may be put into an individual place of the reaction vessel, but is preferably put into the same place, and particularly preferably, before the reaction vessel is put, a metal salt aqueous solution containing nickel and a metal containing manganese. Mix the brine solution.

  The method of mixing the metal salt aqueous solution containing nickel and the metal salt aqueous solution containing manganese is performed by putting the metal salt aqueous solution containing nickel and the metal salt aqueous solution containing manganese in a mixing container, and stirring them with a stirrer or the like. Moreover, it is also preferable to mix and homogenize using a line mixer.

  The concentrations of the nickel-containing metal salt aqueous solution and the manganese-containing metal salt aqueous solution are not particularly limited, but it is economically preferable that the resulting nickel-manganese composite slurry concentration is high. Therefore, it is preferable that the concentration be as high as possible. . Since both the solubility of nickel and manganese is 2 to 3 mol / L, it is usually set to 1.9 to 2.1 mol / L. For example, a metal salt aqueous solution containing 2.0 mol / L of nickel and a metal salt aqueous solution containing 2.0 mol / L of manganese are manufactured, and by volume ratio, nickel metal salt aqueous solution: manganese metal salt aqueous solution = X: 1−X What is necessary is just to supply.

  There are no particular restrictions on the type of salt between the aqueous metal salt solution containing nickel and the aqueous metal salt solution containing manganese used in the present invention, but considering the raw material cost, corrosiveness, and stability, the aqueous nickel sulfate solution and the aqueous manganese sulfate solution It is preferable to use it.

Another method for producing the nickel-manganese composite of the present invention is to mix a metal salt aqueous solution containing nickel and manganese, an aqueous caustic soda solution, and an oxidizing agent, so that the chemical composition formula is Ni _x Mn _1-x O _a (OH). _The nickel-manganese composite represented by _2-a crystallizes out. A mixed aqueous solution of nickel salt and manganese salt in which nickel salt and manganese salt are dissolved in a certain ratio may be manufactured, and the mixed aqueous solution of nickel salt and manganese salt may be supplied to the reaction vessel. In this case, the total concentration of nickel and manganese may be 1.9 to 2.1 mol / L, and the molar ratio of nickel and manganese may be X: 1-X.

  In the method for producing a nickel-manganese composite of the present invention, it is essential to supply a caustic soda aqueous solution to a reaction vessel. Examples of the sodium hydroxide aqueous solution include aqueous solutions of sodium hydroxide, lithium hydroxide, potassium hydroxide, and the like. The concentration of the aqueous caustic soda solution is not particularly limited, but the slurry concentration of the resulting nickel-manganese composite slurry is kept high, the production efficiency is improved, the load of the filtration process can be reduced, and the tolerance of the caustic supply rate is reduced. Since it can be made wide and stable production and production costs are improved, it is preferably 1 to 48 wt%, more preferably 10 to 30 wt%. As the caustic soda aqueous solution, for example, a solution obtained by dissolving solid sodium hydroxide in water or a solution prepared by adjusting the concentration of a sodium hydroxide aqueous solution generated from salt electrolysis can be used.

  In the method for producing a nickel-manganese composite of the present invention, it is essential to supply an oxidizing agent to the reaction vessel. The oxidizing agent is used to form an atmosphere where the Ni valence in the metal salt aqueous solution is divalent and the Mn valence is trivalent and stable. The oxidizing agent used in the present invention is not particularly limited as long as it has a Ni valence of 2 and a Mn valence of 3 and can form a stable atmosphere. In view of economy, usually, an oxygen-containing gas, hydrogen peroxide water or the like is preferably used. Examples of the oxygen-containing gas include air, pure oxygen, and a mixture of oxygen and an inert gas (for example, nitrogen). It is done. Of these, air is particularly preferable. Air may be supplied to the reaction vessel using a compressor or the like.

  The reaction vessel used in the present invention can supply a metal salt aqueous solution containing nickel, a metal salt aqueous solution containing manganese, a caustic soda aqueous solution and an oxidizing agent, or a metal salt aqueous solution containing nickel and manganese, a caustic soda aqueous solution and an oxidizing agent. As long as it can be mixed uniformly. In general, the mixing may be performed with a stirrer at a constant rotational speed.

  The obtained nickel-manganese composite slurry of the present invention is continuously extracted. The method for extracting is not particularly limited, but it is preferable to extract so as to maintain a constant amount of liquid in the reaction vessel. For example, when the liquid level exceeds a certain height, the so-called overflow type in which the liquid exceeding the liquid level is discharged by its own weight is simple and particularly preferable. Of course, it is also preferable to measure the liquid level constantly and extract the slurry with a pump or the like so that the liquid level is constant.

  The present invention neutralizes an aqueous metal salt solution containing nickel and an aqueous metal salt solution containing manganese, or an aqueous metal salt solution containing nickel and manganese, and provides an appropriate oxidizing power to Ni and Mn. A nickel-manganese composite is produced.

  Giving an appropriate oxidizing power to Ni and Mn means that the atmosphere is stable in which Ni is divalent and Mn is trivalent. Since the stable valence of the metal depends on the pH of the aqueous solution and the oxidation-reduction potential (hereinafter referred to as ORP), for example, by controlling the ORP to a predetermined value under a desired temperature and pH condition, Ni Can be formed in an atmosphere in which Mn is trivalent and stable.

  From the relationship between the temperature and pH of the aqueous solution and the standard electrode potential, the stable valence of the metal in the aqueous solution can be calculated. This is known as a potential-pH diagram. For example, "Basic Course for Chemists 11 Chemistry of Electron Transfer, Tadashi Watanabe, Seiichiro Nakabayashi, Asakura Shoten September 10, 199 4th Print" The origin of the potential-pH diagram is described on pages 72-73.

  Preferred methods for crystallizing the nickel-manganese composite in an atmosphere in which Ni is divalent and Mn is trivalent include nickel-containing metal salt aqueous solution, manganese-containing metal salt aqueous solution, and caustic soda aqueous solution. And an oxidizing agent, or a metal salt aqueous solution containing nickel and manganese, a caustic soda aqueous solution, and a slurry liquid after mixing the oxidizing agent have a temperature of 60 to 80 ° C., a pH of 8.5 to 10.0, and an ORP. Can crystallize the nickel-manganese composite with 0.15-0.21 V vs SHE.

  In the method for producing a nickel-manganese composite of the present invention, the composition of nickel and manganese in the nickel-manganese composite can be adjusted by the supply ratio of the metal salt aqueous solution containing nickel and the metal salt aqueous solution containing manganese. Moreover, what is necessary is just to adjust the mixing ratio of nickel and manganese, when using the metal salt aqueous solution containing nickel and manganese.

  The pH can be controlled by the ratio of the supply amount of the metal salt aqueous solution containing nickel and the metal salt aqueous solution containing manganese or the supply amount of the metal salt aqueous solution containing nickel and manganese and the supply flow rate of the caustic soda aqueous solution. Since the supply amount of the metal salt aqueous solution containing nickel, the metal salt aqueous solution containing manganese, and the metal salt aqueous solution containing nickel and manganese is directly related to the production amount of the nickel-manganese composite of the present invention, usually the metal salt containing nickel The supply amount of the aqueous solution and the metal salt aqueous solution containing manganese is supplied at a desired flow rate, and the supply flow rate of the aqueous caustic soda solution is adjusted so that the pH of the nickel-manganese composite slurry becomes a predetermined value.

  ORP is controlled by the supply amount of the oxidizing agent. The ORP of the nickel-manganese composite slurry is measured, and the supply amount of the oxidizing agent is adjusted so that the ORP becomes a predetermined value.

  The particularly preferred oxidant of the present invention is air, which can be controlled by the amount of oxidant supplied, but the inventors have found that the present invention cannot be achieved simply by determining the amount of air supplied. For example, it has been found that when the stirring speed of the stirrer that stirs the reaction vessel changes, the ORP changes even if other conditions are the same, and the effects of the present invention may not be exhibited. Therefore, in the present invention, it is preferable to keep the stirring state constant.

  Even if the supply amount of air as an oxidant is constant, it is not always clear why the ORP changes depending on the rotation speed of stirring, but the inventors consider as follows.

  Oxygen gas in the air dissolves in the nickel-manganese composite slurry, and dissolved oxygen oxidizes Ni and Mn. On the other hand, the dissolved rate of oxygen gas is affected by temperature, pressure, bubble surface area, dissolved oxygen transfer rate, etc., in addition to the amount of air supplied to the slurry. For example, when the rotation speed of stirring is changed, the bubble diameter and the like are changed, so that the oxygen dissolution rate is changed.

By applying the above nickel-manganese composite manufacturing method, the chemical composition formula is Ni _x Mn _1-x O _a (OH) _2-a (however, 0.225 ≦ X ≦ 0.775, 0.5 ≦ a ≦ 0.9) is obtained.

The obtained nickel-manganese composite has a cadmium hydroxide crystal structure. On the other hand, since the α-type nickel hydroxide structure has a relatively wide transition metal layer, it easily takes in anions that can be impurities such as SO ₄ . If it is a cadmium hydroxide type structure, an anion is not taken in between transition metal layers. The cadmium hydroxide structure is a crystal structure in which hydroxide ions are arranged at the positions of iodide ions of a hexagonal cadmium iodide structure. The hydroxide ions are arranged in a nearly hexagonal close-packed structure, and metal ions are located in the octahedral hexacoordinate gaps every other layer in the c-axis direction. In addition, the obtained nickel-manganese composite may not have all the atoms regularly arranged, and may have a so-called stacking fault, that is, a portion where the order of surface overlap is disordered.

Moreover, the obtained nickel-manganese composite may contain a cadmium hydroxide structure having a stacking fault and a hydrotalcite-like structure. The hydrotalcite-like structure is composed of divalent Ni and trivalent Mn, and has a chemical composition formula: Ni _y Mn _(1-y) (OH) ₂ (SO ₄ ) _{(1-y) / 2} (where 0 <Y <1).

As a preferred production method of the present invention, a nickel-manganese composite can be produced by bringing the nickel-manganese composite obtained by the above production method into contact with an aqueous caustic soda solution, followed by filtration and washing with water. When this production method is used, particularly the amount of SO ₄ in the nickel-manganese composite is reduced, so that a particularly preferable raw material for the positive electrode active material of the lithium secondary battery can be produced.

When not contacting with the caustic soda aqueous solution, the amount of SO ₄ in the nickel-manganese composite is usually 0.6 wt% or more. In addition, the SO ₄ amount increases as the nickel ratio in the nickel-manganese composite increases.

On the other hand, for example, in the XRD pattern of the nickel-manganese composite obtained in Example 3 shown in FIG. 3, in addition to the peak attributed to the nickel-manganese composite, the peak of the hydrotalcite-like structure (in the figure) It is a peak indicated by an arrow). The hydrotalcite-like structure consists of divalent Ni and trivalent Mn, and is represented by the chemical composition formula: Ni _Y Mn _(1-Y) (OH) ₂ (SO ₄ ) _{(1-Y) / 2} . The inventors speculate that the higher the nickel ratio, the greater the amount of SO _{4 as} a result of the increased hydrotalcite-like structure.

When this nickel-manganese composite having a hydrotalcite-like crystal phase is brought into contact with an aqueous caustic soda solution and then filtered and washed with water, SO ₄ becomes less than 0.5 wt%. Further, after contacting with an aqueous caustic soda solution and then filtering and washing with water, the peak due to the hydrotalcite-like structure is similar to the XRD pattern of the nickel-manganese composite obtained in Example 8 shown in FIG. A single phase of nickel-manganese composite having a cadmium hydroxide structure was not observed.

The reason why the amount of SO ₄ can be reduced by bringing the nickel-manganese composite into contact with an aqueous caustic soda solution is not necessarily clear, but the inventors consider as follows.

The presence of hydrotalcite-like crystal phase increases SO ₄ ²⁻ in the nickel-manganese composite, but contact with caustic soda quickly replaces SO ₄ ²⁻ with OH ⁻ and reduces the amount of SO _4. At the same time, the hydrotalcite-like crystal phase disappears.

Apart from this, since a large amount of sodium sulfate is present in the nickel-manganese composite slurry obtained in the present invention, SO ₄ is the main anion in the slurry. For this reason, part of OH ⁻ which is an anion of the nickel-manganese composite is substituted with SO ₄ ²⁻ , and the amount of SO ₄ becomes 0.6 wt% or more.

However, after removing SO ₄ around the nickel-manganese composite by ordinary filtration and washing with water, contact with caustic soda replaces SO ₄ ²⁻ with OH ^−, and the amount of SO ₄ is less than 0.6 wt%. It is estimated that it will be possible.

  In any case, a nickel-manganese composite excellent in purity can be produced by bringing the nickel-manganese composite provided by the present invention into contact with an aqueous caustic soda solution, followed by filtration and washing with water.

  Next, a preferred method for bringing the nickel-manganese composite into contact with an aqueous caustic soda solution will be described in detail.

  The nickel-manganese composite to be contacted with an aqueous caustic soda solution is an aqueous metal salt solution containing nickel sulfate, an aqueous metal salt solution containing manganese sulfate, an aqueous caustic soda solution and an oxidizing agent, or an aqueous metal salt solution containing nickel and manganese, an aqueous caustic soda solution and an oxidizing agent. It is preferable to use a wet cake of nickel-manganese composite obtained by filtering and washing the nickel-manganese composite slurry obtained by mixing the above. If a nickel-manganese composite slurry or an unwashed nickel-manganese composite cake is used, the effect of the present invention will be insufficient.

  In addition, it is possible to use a nickel-manganese composite that has been filtered, washed with water, and dried. However, drying is necessary after contact with caustic soda, and drying before contact with caustic soda is wasted because drying energy is wasted. Absent.

  The aqueous caustic soda solution to be brought into contact with the nickel-manganese composite is not particularly limited, and may be the same as the aqueous caustic soda used for crystallization of the nickel-manganese composite.

  There is no particular limitation on the method of contacting the nickel-manganese composite with the caustic soda aqueous solution, and any method can be preferably applied as long as the surface of the nickel-manganese composite particles is brought into contact with the caustic soda aqueous solution. Usually, the nickel-manganese composite can be brought into contact with an aqueous caustic soda solution using an apparatus used for filtration and washing.

  For example, a filter press type filtration device, a suction filtration device, or the like is used for filtration and washing of the slurry. After filtering and washing with these devices, it is changed to a washing solution for washing, supplying caustic soda, and nickel. -Caustic soda solution may be passed through the manganese composite cake, followed by filtration, followed by washing with a washing solution.

  Since the caustic soda aqueous solution has sufficient effects of the present invention and is excellent in economy with respect to the weight of the nickel-manganese composite to be treated, the amount of the caustic soda aqueous solution may be 0.8-2 times.

  Other manufacturing conditions are not particularly limited, and a conventionally known method may be used as appropriate, and can be, for example, as follows.

  The total concentration (metal concentration) of all metals of nickel and manganese in the metal salt aqueous solution is arbitrary, but the metal concentration affects productivity, and is preferably 1.0 mol / L or more, and 2.0 mol / L or more. Is more preferable. Usually 2 mol / L.

  The caustic soda aqueous solution is an aqueous sodium hydroxide solution, and for example, an aqueous solution of solid sodium hydroxide or an aqueous solution of sodium hydroxide generated from salt electrolysis can be used.

  The mixing temperature when mixing the aqueous metal salt solution and the oxidizing agent is not particularly limited, but the oxidation reaction of the aqueous metal salt solution is likely to proceed, and the nickel-manganese composite is more likely to precipitate. Preferably, 60 degreeC or more is more preferable.

  The nickel-manganese composite slurry obtained in the present invention is subsequently filtered, washed and dried. These methods are not particularly limited, and for example, the following methods are applicable.

  The nickel-manganese composite slurry is filtered to remove moisture, and then washed and dried.

  A conventionally known method can be used as appropriate for the apparatus and conditions used for filtration. For example, pressure filtration may be performed using a filter press type filter, or vacuum filtration may be performed using a buch funnel or a belt filter.

  In the cleaning, impurities adhering to and adsorbing to the nickel-manganese composite are removed. Examples of the washing method include a method of washing by pouring water (for example, pure water, tap water, river water, etc.) into the nickel-manganese composite cake. Usually, it is possible to carry out washing using the same apparatus following filtration.

  In the drying, the moisture of the nickel-manganese composite is removed. Examples of the drying method include drying the nickel-manganese composite at 110 to 150 ° C. for 2 to 15 hours.

  By applying the present invention, a nickel-manganese composite suitable for a raw material of a positive electrode active material for a lithium secondary battery in which the ratio of nickel and manganese can be freely set and nickel and manganese are uniformly distributed is obtained. Manufacturable.

Moreover, the nickel-manganese composite obtained by the production method of the present invention is excellent in purity, such as a low SO ₄ content.

It is an XRD pattern of the nickel-manganese composite of Example 1 and Example 8. 2 is an XRD pattern of a nickel-manganese composite of Example 2. FIG. It is an XRD pattern of the nickel-manganese composite of Example 3 and Example 9 (the arrow in the figure indicates the peak of the hydrotalcite-like structure). It is an XRD pattern of the nickel-manganese composite of Example 4 (the arrow in the figure indicates the peak of the hydrotalcite-like structure). It is an XRD pattern of the nickel-manganese composite of Example 5 and Example 10 (the arrow in the figure indicates the peak of the hydrotalcite-like structure). It is an XRD pattern of the nickel-manganese composite of Example 6 (the arrow in the figure indicates the peak of the hydrotalcite-like structure). It is an XRD pattern of the nickel-manganese composite of Example 7 (the arrow in the figure indicates the peak of the hydrotalcite-like structure). 3 is an XRD pattern of a nickel-manganese composite of Comparative Example 1. 3 is an XRD pattern of a nickel-manganese composite of Comparative Example 2. 4 is an XRD pattern of a nickel-manganese composite of Comparative Example 3.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it is not limited to these.

<Powder X-ray diffraction measurement>
Using an X-ray diffractometer (sample horizontal multipurpose X-ray diffractometer, trade name: Ultimate IV, manufactured by Rigaku), powder X-ray diffraction measurement of the sample was performed. 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 8 seconds, and the measurement range is in the range of 5 to 90 ° as 2θ. Measured with

<Identification of crystal phase>
In the XRD pattern obtained by the XRD measurement under the above conditions, having a sharp peak at 2θ = 19.0 ± 0.5 ° and a broad XRD peak at 36.9 ± 1.5 °, The cadmium hydroxide structure was assumed. The peak shape other than the lowest angle is broad because of stacking faults.

  Further, a relatively sharp peak of 10 to 12 ° and a broad peak of 21 to 24 ° are assumed to have a hydrotalcite-like structure.

<Measurement of chemical composition>
The chemical composition in the nickel-manganese composite is measured by dissolving it in a mixed solution of hydrochloric acid and hydrogen peroxide. Nickel is quantified by a nickel densitometer (Ni-5Z, manufactured by Kasahara Chemical Co., Ltd.). Quantification is performed with an automatic titrator (AT-610, manufactured by Kyoto Electronics Industry Co., Ltd.), and the amount of S and Na are determined using an inductively coupled plasma emission spectrometer (trade name: OPTIMA5300DV, manufactured by PERKIN ELMER). The ratio of Ni and Mn in the nickel-manganese composite oxyhydroxide, and the S and Na amounts were calculated. The SO ₄ amount was converted from the S amount.

Example 1
Nickel sulfate and manganese sulfate were dissolved in pure water to obtain an aqueous solution containing 0.5 mol / L nickel sulfate and 1.5 mol / L manganese sulfate. The total concentration of metals is 2.0 mol / L, nickel: manganese = 1: 3 mol ratio).

  Pure water was charged to an overflow level in a reaction vessel having an internal volume of 10 L, and the temperature was raised to 70 ° C. while stirring with a stirrer at a stirring rotation speed of 800 rpm. The reaction vessel has a structure in which the liquid is discharged by overflow when the liquid volume exceeds 6L.

  The metal salt aqueous solution was added to the reaction vessel at 0.45 L / H, and at the same time, air as an oxidant was bubbled into the reaction vessel at a supply rate of 1.8 NL / min. When supplying an aqueous metal salt solution and air, a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) is intermittently added so that the pH is 9.25 to produce a nickel-manganese composite slurry. It was continuously discharged from the reaction vessel.

  The ORP of the nickel-manganese composite slurry in the reactor was stable at 0.20V. A temperature of 70 ° C., pH: 9.25, and ORP: 0.20 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered and washed to obtain a wet cake of nickel-manganese composite.

The obtained wet cake of the nickel-manganese composite was dried at 115 ° C. for 5 hours to obtain a nickel-manganese composite (Ni _0.25 Mn _0.75 OOH).

  Since the XRD pattern of the obtained nickel-manganese composite has a sharp peak at 2θ = 19.0 ° and a broad peak after 2θ = 40 °, the crystal structure is a water with stacking faults. It was a cadmium oxide structure.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 0.6 wt%, and Na was 930 ppm.

Example 2
A nickel-manganese composite slurry was produced in the same manner as in Example 1 except that a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) was intermittently added so that the pH was 9.5.

  The ORP of the nickel-manganese composite slurry in the reactor remained stable at 0.18 V after 4 hours from the start of the reaction. The temperature was 70 ° C., pH: 9.5, and ORP: 0.18 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered, washed and dried, and the XRD pattern of the nickel-manganese composite obtained was 2θ = 19.0 °. Since it has a sharp peak and a broad peak after 2θ = 40 °, its crystal structure was a cadmium hydroxide structure having a stacking fault.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 0.2 wt%, and Na was 2,400 ppm.

Example 3
Nickel sulfate and manganese sulfate were dissolved in pure water to obtain an aqueous solution containing 1.0 mol / L nickel sulfate and 1.0 mol / L manganese sulfate. A nickel-manganese composite slurry was produced in the same manner as in Example 1 except that the total concentration of metals was 2.0 mol / L and nickel: manganese = 1: 1 mol ratio.

  The ORP of the nickel-manganese composite slurry in the reactor remained stable at 0.19 V after 4 hours from the start of the reaction. The temperature was 70 ° C., pH: 9.25, and ORP: 0.19 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered, washed, and dried, and the XRD pattern of the nickel-manganese composite obtained was hydroxylated with stacking faults. The cadmium structure and the hydrotalcite-like structure were mixed.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 4.6 wt% and Na was 320 ppm.

Example 4
A nickel-manganese composite slurry was produced in the same manner as in Example 3 except that a 20 wt% aqueous sodium hydroxide solution (caustic soda solution) was intermittently added so that the pH was 9.5.

  The ORP of the nickel-manganese composite slurry in the reactor remained stable at 0.18 V after 4 hours from the start of the reaction. The temperature was 70 ° C., pH: 9.5, and ORP: 0.18 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered, washed, and dried, and the XRD pattern of the nickel-manganese composite obtained was hydroxylated with stacking faults. The cadmium structure and the hydrotalcite-like structure were mixed.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 3.9 wt% and Na was 460 ppm.

Example 5
Nickel sulfate and manganese sulfate were dissolved in pure water to obtain an aqueous solution containing 1.25 mol / L nickel sulfate and 0.75 mol / L manganese sulfate, and this was used as a metal salt aqueous solution (the total amount in the metal salt aqueous solution). A nickel-manganese composite slurry was produced in the same manner as in Example 1 except that the total concentration of metals was 2.0 mol / L and nickel: manganese = 5: 3 mol ratio.

  The ORP of the nickel-manganese composite slurry in the reactor remained stable at 0.19 V after 4 hours from the start of the reaction. The temperature was 70 ° C., pH: 9.25, and ORP: 0.19 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered, washed, and dried, and the XRD pattern of the nickel-manganese composite obtained was hydroxylated with stacking faults. The cadmium structure and the hydrotalcite-like structure were mixed.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 7.4 wt%, and Na was 40 ppm.

Example 6
A nickel-manganese composite slurry was produced in the same manner as in Example 5 except that a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) was intermittently added so that the pH was 9.0.

  The ORP of the nickel-manganese composite slurry in the reactor remained stable at 0.19 V after 4 hours from the start of the reaction. The temperature was 70 ° C., pH: 9.0, and ORP: 0.19 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered, washed, and dried, and the XRD pattern of the nickel-manganese composite obtained was hydroxylated with stacking faults. The cadmium structure and the hydrotalcite-like structure were mixed.

Further, the obtained nickel-manganese composite had SO ₄ of 7.4 wt% and Na of 140 ppm.

Example 7
A nickel-manganese composite slurry was produced in the same manner as in Example 5 except that a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) was intermittently added so that the pH was 9.0.

  The ORP of the nickel-manganese composite slurry in the reactor remained stable at 0.19 V after 4 hours from the start of the reaction. The temperature was 70 ° C., pH: 9.0, and ORP: 0.19 V was an atmosphere in which Ni was divalent and Mn was trivalent.

  After about 50 hours from the start of the reaction, the nickel-manganese composite slurry discharged from the reaction vessel was collected, filtered, washed, and dried, and the XRD pattern of the nickel-manganese composite obtained was hydroxylated with stacking faults. The cadmium structure and the hydrotalcite-like structure were mixed.

Further, the obtained nickel-manganese composite had SO ₄ of 7.4 wt% and Na of 140 ppm.

Comparative Example 1
A nickel-manganese composite slurry was produced in the same manner as in Example 1, and the air supply rate was changed to 13.0 NL / min after about 72 hours had elapsed since the start of production.

  After changing the air supply speed, the ORP increased to 0.22V. After about 24H from the change of the air supply rate, the nickel-manganese composite slurry discharged from the reaction vessel was separated, filtered, washed, and dried, and the XRD pattern of the nickel-manganese composite obtained was a cadmium hydroxide structure. It was a mixture with a nickel-manganese composite having a structure different from the cadmium hydroxide structure and the hydrotalcite-like structure. The temperature of 70 ° C., pH: 9.25, and ORP: 0.22 V were out of the atmosphere in which Ni was divalent and Mn was trivalent.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 1.3 wt%, and Na was 950 ppm.

Comparative Example 2
A nickel-manganese composite slurry was produced by the same operation as in Example 1, and after about 72 hours had elapsed from the start of production, the stirring rotation speed was reduced to 400 rpm.

  The ORP decreased to 0.12 V after the stirring rotational speed decreased. After about 24H from the decrease in the stirring speed, the nickel-manganese composite slurry discharged from the reaction vessel was separated, filtered, washed, and dried. The XRD pattern of the nickel-manganese composite obtained was a cadmium hydroxide structure, It was a mixture with a nickel-manganese composite having a structure different from the cadmium hydroxide structure and the hydrotalcite-like structure. The temperature of 70 ° C., pH: 9.25, and ORP: 0.12 V were outside the atmosphere in which Ni was divalent and Mn was trivalent.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 1.8 wt%, and Na was 1,080 ppm.

Comparative Example 3
A nickel-manganese composite was obtained in the same manner as in Example 1 except that the pH was 8.3.

  The ORP at this time was 0.16V. The temperature of 70 ° C., pH: 8.3, and ORP: 0.16 V were out of the atmosphere in which Ni was divalent and Mn was trivalent.

  The XRD pattern of the obtained nickel-manganese composite was a mixture of a cadmium hydroxide structure and a nickel-manganese composite having a structure different from the cadmium hydroxide structure and the hydrotalcite-like structure.

Further, the obtained nickel-manganese composite had SO ₄ of 2.7 wt% and Na of 690 ppm.

Example 8
The wet cake of the nickel-manganese composite obtained in Example 1 was poured from above onto 10% by weight of caustic soda having the same weight as the solid content in the wet cake.

  The poured caustic soda was filtered, washed with water, and then dried at 115 ° C. for 5 hours to obtain a nickel-manganese composite.

The XRD pattern of the obtained nickel-manganese composite is a cadmium hydroxide structure having a sharp peak at 2θ = 19.0 °, a broad peak after 2θ = 40 °, and a stacking fault. The obtained nickel-manganese composite had an SO ₄ content of 0.2 wt% and an Na content of 680 ppm. The amounts of SO ₄ and Na decreased.

Example 9
The nickel-manganese composite wet cake obtained in Example 3 was poured onto a buch funnel from the top with 10 wt% sodium hydroxide having the same weight as the solid content in the wet cake.

  The poured caustic soda was filtered, washed with water, and then dried at 115 ° C. for 5 hours to obtain a nickel-manganese composite.

  The XRD pattern of the obtained nickel-manganese composite is a cadmium hydroxide structure having a sharp peak at 2θ = 19.0 °, a broad peak after 2θ = 40 °, and a stacking fault. The peak of the hydrotalcite-like structure disappeared.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 0.2 wt%, Na was 280 ppm, and the amount of SO ₄ was particularly greatly reduced.

Example 10
The nickel-manganese composite wet cake obtained in Example 3 was poured onto a buch funnel from the top with 10 wt% sodium hydroxide having the same weight as the solid content in the wet cake.

  The poured caustic soda was filtered, washed with water, and then dried at 115 ° C. for 5 hours to obtain a nickel-manganese composite.

  The XRD pattern of the obtained nickel-manganese composite is a cadmium hydroxide structure having a sharp peak at 2θ = 19.0 °, a broad peak after 2θ = 40 °, and a stacking fault. The peak of the hydrotalcite-like structure disappeared.

Furthermore, SO ₄ of the obtained nickel-manganese composite was 0.3 wt%, Na was 80 ppm, and the amount of SO ₄ was greatly reduced.

  The results of Examples 1 to 10 and Comparative Examples 1 to 3 are shown in Table 1.

表１、及び、図１〜１０から、本発明の製造方法で製造するニッケル−マンガン複合物は、水酸化カドミウム構造、又は、水酸化カドミウム構造とハイドロタルサイト様構造からなるが、本発明の製造方法を逸脱すると、水酸化カドミウム構造及びハイドロタルサイト様構造とは異なる構造をもつニッケル−マンガン複合物が混在する。さらに、実施例８、９、１０の結果より、本発明が提供する製造方法を適用することにより、ＳＯ_４、及び、Ｎａの含有量が少ないニッケル−マンガン複合物を得ることができる。

From Table 1 and FIGS. 1 to 10, the nickel-manganese composite produced by the production method of the present invention consists of a cadmium hydroxide structure, or a cadmium hydroxide structure and a hydrotalcite-like structure. If it deviates from a manufacturing method, the nickel-manganese composite which has a structure different from a cadmium hydroxide structure and a hydrotalcite-like structure will be mixed. Furthermore, from the results of Examples 8, 9, and 10, by applying the production method provided by the present invention, a nickel-manganese composite with a small content of SO ₄ and Na can be obtained.

  The nickel-manganese composite obtained by the method for producing a nickel-manganese composite of the present invention is most suitable as a raw material for a lithium-nickel-manganese composite oxide used for a positive electrode active material of a lithium secondary battery, A high-performance lithium secondary battery using the lithium-nickel-manganese based composite oxide as a battery positive electrode can be configured.

Claims (6)

Metal salt aqueous solution containing nickel, metal salt aqueous solution containing manganese, caustic soda aqueous solution and oxidizing agent, or metal salt aqueous solution containing nickel and manganese, caustic soda aqueous solution and oxidizing agent are mixed, Ni is bivalent, and Mn is The chemical composition formula is characterized in that the nickel-manganese composite is crystallized in a trivalent atmosphere, and the chemical composition formula is Ni _x Mn _1-x O _a (OH) _{2 -a} (where 0.225 ≦ x ≦ 0.775 and 0.5 ≦ a ≦ 0.9). The method for producing a nickel-manganese composite according to claim 1, wherein the nickel-manganese composite has a cadmium hydroxide structure having a stacking fault. 2. The method for producing a nickel-manganese composite according to claim 1, wherein the nickel-manganese composite contains a cadmium hydroxide structure having a stacking fault and a hydrotalcite-like structure. The slurry liquid after mixing has a temperature of 60 to 80 ° C., a pH of 9 to 11, and an ORP of 0.15 to 0.21 V vs SHE. The method for producing a nickel-manganese composite according to any one of the items. The metal salt aqueous solution containing nickel, the metal salt aqueous solution containing manganese, the caustic soda aqueous solution, and the oxidizing agent are continuously supplied to the reaction vessel, and the nickel-manganese composite is continuously extracted from the reaction vessel. Item 5. The method for producing a nickel-manganese composite according to any one of Items 4. The nickel-manganese composite produced by the method for producing a nickel-manganese composite according to any one of claims 1 to 5 is brought into contact with an aqueous caustic soda solution, and then filtered and washed with water. A method for producing a nickel-manganese composite.

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