JP2018075566A - Method for producing lithium-adsorbing material and lithium-adsorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a lithium manganese oxide-based lithium-adsorbing material that can suppress the elution of manganese without severely impairing the adsorption characteristics to lithium ions.SOLUTION: The method for producing a lithium-adsorbing material comprises the steps of: (1) adding a basic solution to a first aqueous solution including ions of metals so as to prepare a second aqueous solution including hydroxide oligomers of the metals; (2) adding particles of lithium manganese oxide to the second aqueous solution so as to prepare a suspension; (3) drying the suspension to form a dried product and (4) heating the dried product in an oxidative atmosphere. After the step (4), a particulate lithium-adsorbing material is produced and the particulate lithium-adsorbing material includes a lithium manganese oxide particle and a metal oxide covering at least a part of the surface of the lithium manganese oxide particle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lithium adsorbing material capable of adsorbing and desorbing lithium ions, and a method for producing such a lithium adsorbing material.

  Lithium ion secondary batteries with high output and energy density are used in a wide range of applications, from portable IT equipment to electric vehicles, and the demand is growing year by year not only in Japan but worldwide.

  Conventionally, in order to produce lithium raw materials, it has been widely collected from salt lake brine resources. However, salt lake brine resources are rich in impurities such as sulfates and magnesium salts. For this reason, in the salt lake brine resources, there is a problem that it is difficult to apply the existing technology such as sun concentration at the time of lithium ion recovery.

  On the other hand, in recent years, as a method for recovering lithium ions from brine, it has been proposed to use a lithium adsorbing material capable of adsorbing and desorbing lithium ions. Since this lithium adsorbing material has many lithium ion-sized ion exchange sites, only lithium ions can be selectively adsorbed in brine. When recovering lithium ions, lithium ions can be eluted by immersing the lithium adsorbing material in an acid solution and exchanging protons and lithium ions.

  Various material systems are conceivable as the lithium adsorbing material having such characteristics. Among them, lithium manganese oxide (especially spinel type) has high lithium ion selectivity, and therefore has good adsorption / desorption characteristics. It is expected as an adsorbing material.

JP 2001-157838 A JP 2003-245542 A JP 2000-325779 A JP-A-6-31159

  However, in the method for collecting lithium using the lithium manganese oxide-based lithium adsorbing material as described above, when the lithium adsorbing material after the lithium ion adsorption treatment is immersed in an acid solution, the lithium ion is recovered. There is a problem that manganese is eluted from the lithium adsorbing material (Patent Documents 1 and 2).

  On the other hand, in order to suppress such elution of manganese, it has been proposed to add magnesium, antimony, niobium or the like to the skeleton of the lithium manganese oxide (Patent Documents 3 and 4).

  However, in these countermeasures, even if the elution of manganese from the lithium adsorbing material is suppressed, the lithium ion adsorption / desorption sites in the material are reduced, and lithium that can be adsorbed on the lithium adsorbing material. There may be a problem that the amount of ions decreases.

  As described above, since the lithium ion adsorption characteristics and the manganese elution amount suppressing effect are basically in a contradictory relationship, there is a problem that it is difficult to realize a lithium manganese oxide-based lithium adsorbing material having both.

  The present invention has been made in view of such a background, and in the present invention, lithium manganese oxide-based lithium capable of significantly suppressing elution of manganese without significantly impairing the adsorption property to lithium ions. An object is to provide an adsorbing material and a method for producing such a lithium adsorbing material.

In the present invention, a method for producing a lithium adsorbing material capable of adsorbing and desorbing lithium ions,
(1) adding a basic solution to the first aqueous solution containing metal ions to prepare a second aqueous solution containing the metal hydroxide oligomer;
(2) adding lithium manganese oxide particles to the second aqueous solution to prepare a suspension;
(3) drying the suspension to form a dry matter;
(4) heating the dried product in an oxidizing atmosphere;
Have
After the step (4), a particulate lithium adsorbing material is obtained, and the particulate lithium adsorbing material comprises lithium manganese oxide particles and a metal oxide covering at least a part of the surface of the lithium manganese oxide particles. The manufacturing method characterized by including is provided.

  Here, in the manufacturing method according to the present invention, the metal may be one or more selected from the group consisting of aluminum, magnesium, nickel, iron, and other transition metals.

In the production method according to the present invention, the concentration of the metal ions in the first aqueous solution ranges from 1 mmol / liter to 1 mol / liter,
The concentration of the basic solution may be in the range of 1 mmol / liter to 10 mol / liter.

  In the production method according to the present invention, the pH of the second aqueous solution may be in the range of 7 to 12.

In the production method according to the present invention, in the step (2), the lithium manganese oxide has a general formula of LiMn ₂ O ₄ , Li _1.33 Mn _1.67 O ₄ , and Li _1.6 Mn _1. It may be one or more selected from the group consisting of lithium manganese oxides represented by _.6 O ₄ .

  In the manufacturing method according to the present invention, in the step (2), the lithium manganese oxide may be a spinel type (λ type).

  In the production method according to the present invention, the step (3) may be performed by drying the suspension while wet-kneading.

  In the production method according to the present invention, in the particulate lithium adsorbing material obtained after the step (4), the ratio of the metal oxide to the lithium manganese oxide particles is 0.5 wt% to 20 wt%. It may be a range.

  Moreover, in the manufacturing method by this invention, in the said (4) step, the said heating may be implemented at the temperature of 400 to 900 degreeC.

Furthermore, in the present invention, a lithium adsorbing material capable of adsorbing and desorbing lithium ions,
The lithium adsorption material includes a particulate material,
The particulate material is configured such that at least a part of the surface of the lithium manganese oxide particles is coated with an oxide of a metal other than manganese,
A lithium adsorbing material is provided, wherein a ratio of the metal oxide to the lithium manganese oxide particles is in a range of 0.5 wt% to 20 wt%.

  Here, in the lithium adsorbing material according to the present invention, the metal other than manganese may be one or more selected from the group consisting of aluminum, magnesium, nickel, iron, and other transition metal oxides.

  Moreover, the lithium adsorption material by this invention WHEREIN: The range of 0.1 micrometer-1 mm may be sufficient as the particle size of the said lithium manganese oxide particle.

In the lithium adsorbing material according to the present invention, the lithium manganese oxide particles may be represented by the general formulas LiMn ₂ O ₄ , Li _1.33 Mn _1.67 O ₄ , and Li _1.6 Mn _1.6 O ₄ . One or more selected from the group consisting of lithium manganese oxides may be included.

  In the lithium adsorbing material according to the present invention, the lithium manganese oxide may be a spinel type (λ type).

The lithium adsorbing material according to the present invention may further include a substrate for supporting the particulate material and / or an organic bonding agent for fixing the particulate material.

The lithium adsorbing material according to the present invention may be used for recovering lithium ions from seawater, salt lake brine, or lithium-containing wastewater.

  The present invention provides a lithium manganese oxide-based lithium adsorbing material and a method for producing such a lithium adsorbing material capable of significantly suppressing the elution of manganese without significantly impairing the adsorption characteristics for lithium ions. be able to.

It is the flowchart which showed roughly the manufacturing method of the lithium adsorption material by one Example of this invention. 6 is a diagram showing an example of a transmission electron microscope (TEM) photograph of a sample according to Example 2. FIG. It is the figure which showed the manganese elution amount and lithium ion desorption amount of the lithium adsorption material which concerns on an Example compared with the lithium adsorption material which concerns on a comparative example. It is the graph which showed the manganese elution rate and lithium ion desorption rate in the same holding time of another sample when the manganese elution amount and the lithium ion desorption amount obtained in the sample according to Comparative Example 1 were set to 100. It is the figure which showed the manganese elution amount and lithium ion desorption amount of the lithium adsorption material which concerns on an Example compared with the lithium adsorption material which concerns on a comparative example. It is the graph which showed the manganese elution rate and lithium ion desorption rate in the same holding time of another sample when the manganese elution amount and the lithium ion desorption amount obtained in the sample according to Comparative Example 2 were set to 100. It is the figure which showed collectively the result of the lithium ion adsorption / desorption repetition test.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  As described above, it has been proposed to add magnesium, antimony, niobium, or the like to the skeleton of the lithium manganese oxide in order to suppress the elution of manganese in the lithium manganese oxide-based lithium adsorbing material.

  However, with such countermeasures, even if the elution of manganese from the lithium adsorbing material is suppressed, the adsorption / desorption sites of lithium ions in the material are reduced, and the lithium adsorbing material is allowed to adsorb. However, there may be a problem that the amount of lithium ions that can be reduced.

In contrast, the present invention is a method for producing a lithium adsorbing material capable of adsorbing and desorbing lithium ions,
(1) adding a basic solution to the first aqueous solution containing metal ions to prepare a second aqueous solution containing the metal hydroxide oligomer;
(2) adding lithium manganese oxide particles to the second aqueous solution to prepare a suspension;
(3) drying the suspension to form a dry matter;
(4) heating the dried product in an oxidizing atmosphere;
Have
After the step (4), a particulate lithium adsorbing material is obtained, and the particulate lithium adsorbing material comprises lithium manganese oxide particles and a metal oxide covering at least a part of the surface of the lithium manganese oxide particles. The manufacturing method characterized by including is provided.

  In the method for producing a lithium adsorbing material according to the present invention, a particulate lithium adsorbing material can be produced, and the particulate lithium adsorbing material comprises a lithium manganese oxide having at least a part of the surface coated with a metal oxide. Contains particles.

  In such a lithium adsorbing material, the elution of manganese from the lithium manganese oxide particles in the acid solution is significantly suppressed by the metal oxide present so as to cover at least a part of the surface of the lithium manganese oxide particles. be able to.

  Further, in the lithium adsorbing material according to the present invention, the metal oxide does not constitute the skeleton of the lithium adsorbing material, but is placed as a “film” on the surface of the lithium manganese oxide particles. Therefore, the problem with the conventional countermeasures, that is, the problem that the adsorption / desorption sites of lithium ions in the lithium manganese oxide decrease due to the additive substance can be significantly suppressed.

  For this reason, in the lithium adsorbing material according to the present invention, it is possible to significantly suppress the elution of manganese while maintaining the adsorption / desorption characteristics with respect to lithium ions.

  Here, it should be noted that in the present application, the “membrane” does not necessarily need to cover the entire surface of the member having the surface on which the “membrane” is installed.

  For example, in the case of the present application, the “film” of the metal oxide may exist in a form covering only a part of the surface of the member covered with the “film”, that is, lithium manganese oxide particles. In this case, an exposed portion that is not covered with the metal oxide is present on a part of the surface of the lithium manganese oxide particle, and in this exposed portion, good adsorption characteristics for lithium ions can be significantly maintained. Can do. Moreover, the other part of the surface of the lithium manganese oxide particles is covered with the metal oxide, so that the amount of manganese dissolved in the acid solution can be significantly suppressed.

  However, as a matter of course, for example, when the “film” of the metal oxide is thin or when the “film” is porous, it exhibits both good adsorption / desorption characteristics for lithium ions and an inhibitory effect on manganese elution. Where possible, the metal oxide “film” may cover the entire surface of the lithium manganese oxide particles.

  Hereinafter, an embodiment of the present invention will be described in detail.

(Manufacturing method of lithium adsorbing material according to an embodiment of the present invention)
FIG. 1 schematically shows a flow of a method for producing a lithium adsorbing material according to an embodiment of the present invention.

In the example shown in FIG. 1, the method for producing a lithium adsorbing material according to an embodiment of the present invention includes:
(1) adding a basic solution to the first aqueous solution containing metal ions to prepare a second aqueous solution containing the metal hydroxide oligomer (step S110);
(2) adding lithium manganese oxide particles to the second aqueous solution to prepare a suspension (step S120);
(3) drying the suspension to form a dried product (step S130);
(4) heating the dried product in an oxidizing atmosphere (step S140);
Have

  Hereinafter, each step will be described.

  In the following description, the lithium adsorbing material obtained by this manufacturing method will be particularly referred to as “particulate lithium adsorbing material (according to one embodiment of the present invention)”. “Particulate lithium adsorbing material (according to one embodiment of the present invention)” includes lithium manganese oxide particles and a metal oxide covering at least a part of the surface of the particles. In other words, the “particulate lithium adsorbing material” has a form in which at least a part of the surface of the lithium manganese oxide particles is coated with the metal oxide.

(Step S110)
First, a first aqueous solution containing metal ions is prepared. For example, the first aqueous solution may be prepared by dissolving a metal salt in water.

  The type of metal is not particularly limited as long as it exhibits the effects of the present invention as described above. That is, it is a material that becomes a metal oxide after performing the subsequent step S140, can significantly suppress the elution of manganese from lithium manganese oxide, and does not significantly inhibit the adsorption / desorption characteristics of lithium manganese oxide with respect to lithium ions. Any metal may be used as long as it is present. The metal is selected from those whose oxides have acid resistance.

  The metal may be, for example, one or more selected from the group consisting of aluminum, magnesium, nickel, iron, and other transition metals. In addition, when multiple metals are selected, there is no particular problem that one of them contains manganese, but when a single metal is selected, such metals are selected from those other than manganese. Is done.

  Examples of metal salts include, but are not limited to, chlorides, sulfides, hydroxides, nitrates, sulfates, carbonates, and organic metal salts. These metal salts can be used alone or in combination of two or more.

  The concentration of the metal ion in the first aqueous solution is, for example, in the range of 1 mmol / liter to 1 mol / liter.

  Next, the basic solution is added to the first aqueous solution. By the addition of this basic solution, the pH of the first aqueous solution rises and a hydroxide oligomer of the metal species is formed (second aqueous solution). This hydroxide oligomer functions as a precursor that later becomes a metal oxide.

  Although the basic solution to be added is not particularly limited, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, and / or aqueous ammonia can be used.

  The addition of the basic solution is preferably carried out while stirring the first aqueous solution. Further, the basic solution may be dropped at a rate of 0.1 ml / min to 100 ml / min, for example. Moreover, the density | concentration of a basic solution is the range of 1 mmol / liter-10 mol / liter, for example.

  The liquidity of the second aqueous solution is preferably about neutral to strongly alkaline (pH 7 to pH 12), preferably about pH 9 to 11. However, it should be noted that the preferred pH varies depending on the metal salt used. For example, a metal hydroxide oligomer may be generated even in a pH 6.5 to 8 region where the liquidity of the solution is near neutral.

(Step S120)
Next, lithium manganese oxide particles are added to the second aqueous solution prepared in step S110.

  It is preferable to add the lithium manganese oxide particles while stirring the second aqueous solution. Thereby, the obtained suspension can be quickly homogenized. Moreover, addition and stirring of particles are usually performed at room temperature in the air.

The lithium manganese oxide has, for example, a spinel (λ-type) structure represented by a general formula of LiMn ₂ O ₄ , Li _1.33 Mn _1.67 O ₄ , or Li _1.6 Mn _1.6 O _4. You may select from the manganese oxide which has.

  However, the lithium manganese oxide is amorphous lithium such as α-type (hollandite type), β-type (rutile type), γ-type, δ-type, and ramsdellite type, although the adsorptivity to lithium ions is somewhat inferior Manganese oxide may be used.

  The particle size of the lithium manganese oxide particles is not particularly limited, and is, for example, in the range of 0.1 μm to 1 mm. In particular, when it is assumed in the future that the particulate lithium adsorbing material according to one embodiment of the present invention will be kneaded into activated carbon or the like, a material having a small particle size of about submicron is preferable.

  The addition amount of the lithium manganese oxide is selected so that the weight ratio of the metal oxide to the lithium manganese oxide is in the range of 0.5 wt% to 20 wt% in the particulate lithium adsorbing material obtained after step S140. It is preferable. The weight ratio of the metal oxide to the lithium manganese oxide is more preferably in the range of 1 wt% to 10 wt%.

  If the ratio of the metal oxide is less than 0.5 wt%, there may be a case where a good manganese elution suppressing effect cannot be obtained in the particulate lithium adsorbing material. On the contrary, when the ratio of the metal oxide exceeds 20 wt%, the adsorptivity with respect to lithium ions may be reduced in the particulate lithium adsorbing material.

(Step S130)
Next, the suspension obtained in step S120 is dried to form a dried product.

  The drying method is not particularly limited, but in the obtained dried product, in order to distribute the metal hydroxide oligomer as evenly as possible on the surface of the lithium manganese oxide particles, a method of drying the suspension while wet kneading is performed. It is preferable to adopt.

  In such a drying method, for example, the suspension is stirred at room temperature for about 30 minutes to 1 hour, and then the suspension is heated using a hot plate or a sand bath while stirring is continued. Moisture is evaporated.

  Alternatively, a drying method such as a spray drying method may be used. Since the obtained dried product is an inorganic compound and has high heat resistance, it can be dried under relatively high temperature conditions. For example, the drying conditions may be a temperature range of 40 ° C. to 160 ° C. under normal pressure.

(Step S140)
Next, the obtained dried product is heat-treated.

  The heat treatment conditions are not particularly limited as long as the metal oxide can be properly formed from the metal hydroxide oligomer contained in the dried product. For example, the heat treatment may be performed by heating the dried product in a range of 400 ° C. to 900 ° C. in air or in an oxidizing atmosphere. The heat treatment time may be in the range of 1 hour to 20 hours, for example.

However, the heat treatment conditions vary depending on the raw materials and the like. For example, when LiMn ₂ O ₄ is used as the lithium manganese oxide raw material, the heat treatment of the dried product may be performed at around 600 ° C. for about 1 hour. Further, when Li _1.33 Mn _1.67 O ₄ is used as the lithium manganese oxide raw material, the heat treatment of the dried product may be performed at around 400 ° C. for 3 hours.

  For the heat treatment, for example, an electric furnace such as a horizontal tubular furnace and a muffle furnace as a reaction apparatus capable of controlling the atmosphere, a heating furnace having another heat source, or the like can be used.

  Through the above steps, lithium manganese oxide particles having at least a part of the surface coated with a metal oxide, that is, particulate lithium adsorbing material according to an embodiment of the present invention can be obtained.

  As described above, the particulate lithium adsorption material produced by such a method can significantly suppress the elution of manganese from the lithium manganese oxide particles in the acid solution due to the presence of the metal oxide. . In such a particulate lithium adsorbing material, the metal oxide is installed as a “film” on at least a part of the lithium manganese oxide particles, so that the adsorption / desorption sites of lithium ions in the lithium manganese oxide are reduced. Can be minimized.

  Therefore, the particulate lithium adsorbing material according to one embodiment of the present invention can significantly suppress the dissolution amount of manganese while maintaining the adsorptivity to lithium ions.

(Lithium adsorption material according to one embodiment of the present invention)
Next, a lithium adsorbing material according to an embodiment of the present invention will be described.

A lithium adsorbing material according to an embodiment of the present invention includes a particulate material,
The particulate material is configured such that at least a part of the surface of the lithium manganese oxide particles is coated with an oxide of a metal other than manganese,
The ratio of the metal oxide to the lithium manganese oxide particles is in the range of 0.5 wt% to 20 wt%.

  The type of metal oxide is not particularly limited. For example, it is one or more selected from aluminum oxide, magnesium oxide, nickel oxide, iron oxide, and other transition metal oxides. There may be.

On the other hand, the lithium manganese oxide is, for example, a spinel type (λ type) represented by a general formula of LiMn ₂ O ₄ , Li _1.33 Mn _1.67 O ₄ , or Li _1.6 Mn _1.6 O _4. You may select from the manganese oxide which has a structure.

  The particle size of the lithium manganese oxide particles is not particularly limited, and is, for example, in the range of 0.1 μm to 1 mm. The particle size of the lithium manganese oxide particles is preferably in the range of 1 μm to 100 μm.

  The lithium adsorbing material having such characteristics significantly elutions manganese from the lithium manganese oxide particles in the acid solution due to the metal oxide present so as to cover at least a part of the surface of the lithium manganese oxide particles. Can be suppressed.

  In this metal oxide, a part of the metal element in the metal oxide undergoes a substitution reaction with Mn (III) of the lithium manganese oxide particles, so that the disproportionation reaction of Mn (III) The effect which suppresses is also considered.

Here, the disproportionation reaction of Mn (III) is, for example,

2Mn ³⁺ = Mn ²⁺ + Mn ⁴⁺ (1) Formula

By this reaction, Mn (III) is eluted as Mn (II). Such a disproportionation reaction is considered to contribute to a phenomenon in which manganese is eluted from lithium manganese oxide in an acid solution.

  However, in the lithium adsorbing material according to one embodiment of the present invention, the disproportionation reaction is suppressed by the metal oxide present on the surface of the lithium manganese oxide particles, thereby suppressing the elution of manganese. You can think of it.

  Further, the metal oxide is installed as a “film” that covers at least a part of the surface of the lithium manganese oxide particles. This “film” can also cover the entire surface of the lithium manganese oxide particles as a porous film. Such an arrangement form of the metal oxide can significantly suppress the reduction of the lithium ion adsorption / desorption sites of the lithium manganese oxide.

  In addition, in order to acquire such an effect reliably, in the lithium adsorption material by one Example of this invention, the ratio of the metal oxide with respect to lithium manganese oxide particle is the range of 0.5 wt%-20 wt%. In particular, the ratio of the metal oxide to the lithium manganese oxide particles is preferably in the range of 1 wt% to 10 wt%.

  When the ratio of the metal oxide is less than 0.5 wt%, a good manganese elution suppression effect may not be obtained in the lithium adsorbent material. On the other hand, when the ratio of the metal oxide exceeds 20 wt%, the lithium adsorbent material may have a reduced adsorptivity to lithium ions.

  With the above features, the lithium adsorbing material according to one embodiment of the present invention can significantly suppress elution of manganese while maintaining the adsorption / desorption characteristics with respect to lithium ions.

  By the way, it should be noted that the lithium adsorbing material according to one embodiment of the present invention can be used in various applications in various modes.

  For example, the lithium adsorbing material according to an embodiment of the present invention may be provided in the form of a molded body that is formed after the granulation process. In addition, the lithium adsorbing material according to an embodiment of the present invention may be used in a form supported as a powder on a substrate and / or dispersed in a fixing agent such as an organic binder.

  The lithium adsorbing material according to one embodiment of the present invention may be used as a material for recovering lithium ions from seawater, salt lake brine, or lithium-containing wastewater. Alternatively, the lithium adsorbing material according to an embodiment of the present invention can be used as a water-dispersed lithium ion selective adsorbing material or a positive electrode active material for a secondary battery.

  Next, examples of the present invention will be described.

Example 1
As a first aqueous solution, aluminum nitrate was dissolved in deionized water to prepare 20 ml of a 0.125 mol / liter aluminum nitrate aqueous solution.

  Next, an aqueous sodium hydroxide solution was added to the first aqueous solution. The aqueous sodium hydroxide solution was added with stirring the first aqueous solution until the first aqueous solution reached a pH of about 9. The concentration of the aqueous sodium hydroxide solution was 1 mol / liter, and the addition rate was about 1 mL / min.

  As a result, an aluminum hydroxide oligomer was formed in the aqueous solution, and a second aqueous solution was obtained.

Next, while stirring the second aqueous solution in a beaker, lithium manganese oxide (LiMn ₂ O ₄ ) particles (hereinafter referred to as “first particles”) are added to the second aqueous solution. A turbid liquid was obtained. The particle size (particle size distribution) of the first particles is in the range of 1 μm to 100 μm. The amount of the first particles added was 5.0 g.

  Even after the addition of the first particles, the suspension in the beaker was kept stirred for 1 hour at room temperature. Then, the beaker containing the suspension was placed on a hot plate, and the suspension was dried by heating the beaker. The heating temperature was 80 ° C., and the suspension was continuously stirred during the heating.

  As a result, a dried product (blocked solid) was obtained in the beaker.

  Next, the obtained dried product was collected and heat-treated in an air atmosphere. The heat treatment temperature was 600 ° C., and the heat treatment time was 1 hour. After the heat treatment, a powdery sample (hereinafter referred to as “sample according to Example 1”) was obtained.

From the X-ray diffraction analysis result of the sample according to Example 1, the LiMn ₂ O ₄ peak is clearly recognized in the sample according to Example 1, and the crystal structure of the first particles is maintained even after the heat treatment. It has been confirmed.

  Next, fluorescent X-ray analysis was performed using the sample according to Example 1. From the obtained results, it was found that the sample according to Example 1 contains about 2.09 wt% of aluminum oxide by weight with respect to the first particles. From the evaluation with a transmission electron microscope, it was found that the aluminum oxide was formed so as to cover the first particles.

(Example 2)
A sample according to Example 2 was manufactured in the same manner as in Example 1. However, in Example 2, a magnesium nitrate aqueous solution having a concentration of 0.125 mol / liter was used as the first aqueous solution. Other conditions are the same as in the first embodiment.

From the X-ray diffraction analysis result of the sample according to Example 2, the LiMn ₂ O ₄ peak is clearly recognized in the sample according to Example 2, and the crystal structure of the first particles is maintained even after the heat treatment. It has been confirmed.

  Next, fluorescent X-ray analysis was performed using the sample according to Example 2. From the obtained results, it was found that the magnesium oxide having a weight ratio of about 1.81 wt% with respect to the first particles was present in the sample according to Example 2.

  In FIG. 2, an example of the transmission electron microscope (TEM) photograph of the sample concerning Example 2 is shown.

In FIG. 2, the central black portion corresponds to LiMn ₂ O ₄ particles (first particles), and the upper left thin contrast portion adjacent to the black portion corresponds to magnesium oxide. From this result, it was found that the magnesium oxide had a thickness of about 10 nm and was formed so as to cover the first particles.

(Example 3)
A sample according to Example 3 was manufactured in the same manner as in Example 1. However, in Example 3, a nickel nitrate aqueous solution having a concentration of 0.125 mol / liter was used as the first aqueous solution. Other conditions are the same as in the first embodiment.

From the X-ray diffraction analysis result of the sample according to Example 3, the LiMn ₂ O ₄ peak is clearly recognized in the sample according to Example 3, and the crystal structure of the first particles is maintained even after the heat treatment. It has been confirmed.

  Next, fluorescent X-ray analysis was performed using the sample according to Example 3. From the obtained results, it was found that the nickel oxide having a weight ratio of about 4.05 wt% with respect to the first particles was present in the sample according to Example 3. From the evaluation by a transmission electron microscope, it was found that this nickel oxide was formed so as to cover the first particles.

(Comparative Example 1)
As Comparative Example 1, the first particles used as raw materials for lithium manganese oxide (LiMn ₂ O ₄ ) in Examples 1 to 3 described above were prepared. In Comparative Example 1, the first particles were used as they were without performing heat treatment or the like.

Example 4
As a first aqueous solution, aluminum nitrate was dissolved in deionized water to prepare 20 ml of a 0.125 mol / liter aluminum nitrate aqueous solution.

  Next, an aqueous potassium hydroxide solution was added to the first aqueous solution. The potassium hydroxide aqueous solution was added in a state where the first aqueous solution was stirred until the pH of the first aqueous solution reached about 10. The concentration of the aqueous potassium hydroxide solution was 1 mol / liter, and the addition rate was about 1 mL / min.

  As a result, an aluminum hydroxide oligomer was formed in the aqueous solution, and a second aqueous solution was obtained.

Next, while stirring the second aqueous solution in a beaker, lithium manganese oxide (Li _1.33 Mn _1.67 O ₄ ) particles (hereinafter referred to as “second particles”) are added to the second aqueous solution. ) Was added to obtain a suspension. The particle size (particle size distribution) of the second particles is in the range of 1 μm to 100 μm. The amount of the second particles added was 2.0 g.

  Even after the addition of the second particles, the suspension in the beaker was kept stirred for 1 hour at room temperature. Then, the beaker containing the suspension was placed on a hot plate, and the suspension was dried by heating the beaker. The heating temperature was 80 ° C., and the suspension was continuously stirred during the heating.

  As a result, a dried product (blocked solid) was obtained in the beaker.

  Next, the obtained dried product was collected and heat-treated in an air atmosphere. The heat treatment temperature was 400 ° C., and the heat treatment time was 3 hours. After the heat treatment, a powdery sample (hereinafter referred to as “sample according to Example 4”) was obtained.

From the result of X-ray diffraction analysis of the sample according to Example 4, the peak according to Example 4 clearly shows a peak of Li _1.33 Mn _1.67 O ₄ , and even after the heat treatment, the second It was confirmed that the crystal structure of the particles was maintained.

  Next, fluorescent X-ray analysis was performed using the sample according to Example 4. From the obtained results, it was found that the sample according to Example 4 contained about 7.13 wt% aluminum oxide by weight with respect to the second particles. From the evaluation with a transmission electron microscope, it was found that the aluminum oxide was formed so as to cover the second particles.

(Example 5)
A sample according to Example 5 was manufactured in the same manner as in Example 4. However, in Example 6, a nickel nitrate aqueous solution having a concentration of 0.125 mol / liter was used as the first aqueous solution. Other conditions are the same as in the fourth embodiment.

From the result of X diffraction analysis of the sample according to Example 5, the peak according to Example 5 clearly shows a peak of Li _1.33 Mn _1.67 O ₄ , and the second after the heat treatment. It was confirmed that the crystal structure of the particles was maintained.

  Next, fluorescent X-ray analysis was performed using the sample according to Example 5. From the obtained results, it was found that the nickel oxide having a weight ratio of about 11.7 wt% with respect to the second particles was present in the sample according to Example 5. From the evaluation by a transmission electron microscope, it was found that the nickel oxide was formed so as to cover the second particles.

(Comparative Example 2)
As Comparative Example 2, second particles used as raw materials for lithium manganese oxide (Li _1.33 Mn _1.67 O ₄ ) in Examples 4 to 5 described above were prepared. In Comparative Example 2, the second particles were used as they were without performing heat treatment or the like.

  Table 1 below collectively shows sample manufacturing methods according to Examples 1 to 5 and Comparative Examples 1 and 2.

(Evaluation)
(1) Elution characteristic evaluation of each sample The elution characteristic evaluation test was done using the sample which concerns on Examples 1-5 prepared by the above-mentioned method, and Comparative Examples 1-2.

  The elution characteristic evaluation test was performed as follows.

  First, 0.5 g of the sample according to Example 1 is added to 500 ml of a hydrochloric acid aqueous solution having a concentration of 0.25 mol / liter at room temperature while stirring the hydrochloric acid aqueous solution (stirring speed 200 rpm). The time when the addition is completed is set to 0 (zero) on the time axis. Next, the hydrochloric acid aqueous solution is maintained as it is while stirring is continued, 10 mL of the aqueous solution is sampled at predetermined time intervals, and the manganese concentration and the lithium concentration contained in the sampling solution are measured.

  Such a test was implemented with respect to each of the samples according to Examples 1 to 5 and Comparative Examples 1 and 2, respectively. However, in Examples 4 to 5, an aqueous sulfuric acid solution having the same concentration was used instead of the aqueous hydrochloric acid solution. (For Examples 2-3, the same aqueous hydrochloric acid solution as in Example 1 was used.) Note that a high-frequency inductively coupled plasma emission spectrometer was used to measure the manganese concentration and the lithium concentration.

  In FIG. 3, the elution characteristic evaluation result of the sample which concerns on Examples 1-3 and the comparative example 1 is shown collectively. In FIG. 3, the horizontal axis represents the retention time (min) of the sample in the aqueous hydrochloric acid solution. In addition, the vertical axis shows the manganese concentration contained in the sampling liquid on the left, that is, the manganese elution amount (mol / liter) per unit mass of lithium manganese oxide contained in the powder sample, The second axis indicates the lithium ion concentration contained in the sampling solution, that is, the lithium ion desorption amount (mol / liter) per unit mass of the lithium manganese oxide contained in the powder sample.

  FIG. 4 also shows the manganese elution rate at the same retention time of other samples when the manganese elution amount and the desorbed lithium ion amount obtained in the sample according to Comparative Example 1 with a retention time of 90 minutes are defined as 100. The lithium ion desorption rate is shown.

From FIG. 3 and FIG. 4, in the sample according to Comparative Example 1 consisting only of the first particles, the elution amount of manganese is very high (about 0.008 mol / liter) from the initial stage of hydrochloric acid immersion, and this high for 90 minutes. It can be seen that the elution amount is maintained. On the other hand, in the samples according to Examples 1 to 3 including the lithium manganese oxide (LiMn ₂ O ₄ ) particles coated with the metal oxide, the elution of manganese is significantly suppressed as compared with Comparative Example 1. (At most, less than about 0.006 mol / liter).

  In particular, as apparent from FIG. 4, in the sample according to Example 1, the manganese elution amount after 90 minutes was reduced by about 42% as compared with the sample according to Comparative Example 1.

  On the other hand, regarding the lithium ion desorption characteristics, in the sample according to Comparative Example 1, the lithium ion desorption amount is about 0.02 mol / liter, whereas in the samples according to Examples 1 to 3, it is lower than this. There was a trend. However, the rate of decline is not very noticeable. For example, from FIG. 4, even in the sample according to Example 3 with a small amount of lithium ion desorption, the decrease rate of the lithium ion desorption amount after 90 minutes with respect to the sample according to Comparative Example 1 is only about 25%.

  Therefore, in the samples according to Examples 1 to 3, it can be said that the degree of decrease in the lithium ion adsorption / desorption characteristics is small as compared with the manganese elution suppressing effect.

  Thus, in the samples according to Examples 1 to 3, it was confirmed that the dissolution amount of manganese can be significantly suppressed without significantly impairing the adsorption / desorption characteristics with respect to lithium ions.

  On the other hand, in FIG. 5, the elution characteristic evaluation result of the sample which concerns on Examples 4-5 and the comparative example 2 is shown collectively. In FIG. 5, the horizontal axis represents the retention time (minutes) of the sample in the sulfuric acid aqueous solution. In addition, the vertical axis shows the manganese concentration contained in the sampling liquid on the left, that is, the manganese elution amount (mol / liter) per unit mass of lithium manganese oxide contained in the powder sample, The second axis indicates the lithium ion concentration contained in the sampling solution, that is, the lithium ion desorption amount (mol / liter) per unit mass of the lithium manganese oxide contained in the powder sample.

  Further, FIG. 6 shows the manganese elution rate at the same sampling time of other samples when the manganese elution amount and the lithium ion desorption amount obtained in the sample according to Comparative Example 2 having a retention time of 90 minutes are defined as 100. The lithium ion desorption rate is shown.

From FIG. 5 and FIG. 6, in the sample according to Comparative Example 2 consisting of only the second particles, the elution amount of manganese is extremely high from the initial stage of sulfuric acid immersion, and this high elution amount is maintained for 90 minutes. I understand. On the other hand, in the samples according to Examples 4 to 5 including the lithium manganese oxide (Li _1.33 Mn _1.67 O ₄ ) particles partially coated with the metal oxide, the sample according to Comparative Example 2 In comparison with the above, elution of manganese is significantly suppressed. In particular, as apparent from FIG. 6, in the sample according to Example 4, the manganese elution amount after 90 minutes was reduced by about 25% compared to the sample according to Comparative Example 2.

  On the other hand, regarding the lithium ion desorption characteristics, in the sample according to Comparative Example 2, the lithium ion desorption amount is about 0.03 mol / liter (after 90 minutes), whereas in the samples according to Examples 4 to 5, There was a tendency to lower than this. However, as apparent from FIG. 6, even in the sample according to Example 4 having a relatively low lithium ion desorption amount, the decrease rate of the lithium ion desorption amount after 90 minutes with respect to the sample according to Comparative Example 2 is about 15%. It was about.

  Therefore, in the samples according to Examples 4 to 5, it can be said that the degree of decrease in the lithium ion desorption property is small as compared with the manganese elution suppressing effect.

  As described above, in the samples according to Examples 4 to 5, it was confirmed that the dissolution amount of manganese can be significantly suppressed without significantly impairing the desorption characteristic for lithium ions.

(3) Lithium Ion Adsorption / Desorption Repeat Test Next, lithium ion adsorption / desorption repeated tests were performed using the samples according to Example 4, Example 5, and Comparative Example 2.

  This test was performed as follows.

  The powdery sample (1.0 g) according to Example 4 is placed in 40 mL of lithium ion-containing water at room temperature and held for 1 day. Next, a sample is taken out from the lithium ion-containing water, and the sample is immersed in 125 mL of a 0.25 mol / liter sulfuric acid aqueous solution at room temperature and held for 1 day. This was set as one period, and the immersion of the sample was repeated between the lithium ion-containing water and the sulfuric acid aqueous solution. After completion of each cycle, the manganese concentration and the lithium concentration contained in the sulfuric acid aqueous solution were analyzed. From the obtained results, the elution rate of manganese and the desorption amount of lithium ions in each cycle were evaluated.

  As the lithium ion-containing water, Uyuni salt lake brine (from Bolivia) was used. The brine was used after adjusting the pH to 6.6 with sodium bicarbonate. Note that a high-frequency inductively coupled plasma optical emission analyzer was used for the measurement of manganese concentration and lithium concentration.

  Such a test was also performed on each of the samples according to Example 5 and Comparative Example 2.

  In FIG. 7, the result of the adsorption / desorption repetition test obtained in the sample which concerns on Example 4, Example 5, and the comparative example 2 is shown collectively.

  In FIG. 7, the horizontal axis indicates the number of cycles (times). The vertical axis indicates the lithium ion desorption amount (mg / g) per unit mass of the lithium manganese oxide contained in the powder sample, and the right second axis is contained in the powder sample. The manganese elution rate (wt%) per unit mass of lithium manganese oxide.

  From FIG. 7, in the sample according to Comparative Example 2, the lithium ion desorption amount in the first cycle is high (50 mg / g or more), but the lithium ion desorption amount tends to decrease sharply after the second cycle. Recognize. In addition, the manganese elution rate shows a very high value in the first cycle, and although it decreases somewhat after the second cycle, it can be seen that the high manganese elution rate continues.

  On the other hand, in the samples according to Example 4 and Example 5, the decrease tendency of the lithium ion desorption amount with respect to the number of cycles is generally gentler than that of the sample according to Comparative Example 1. In particular, in the samples according to Example 4 and Example 5, the initial lithium ion desorption amount is lower than the sample according to Comparative Example 2, but after the second cycle, the lithium ion desorption amount of the sample according to Comparative Example 1 is reduced. It turns out that it reverses and shows a good lithium ion desorption behavior.

  Further, in the samples according to Example 4 and Example 5, the manganese elution rate is lower than the manganese elution amount of the sample according to Comparative Example 2 in any cycle, and a good manganese elution suppressing effect can be obtained. Recognize.

  Thus, it was confirmed that by coating at least a part of the lithium manganese oxide particles with the metal oxide, a good manganese elution suppression effect and a good lithium ion adsorption / desorption characteristic can be obtained in each cycle. .

In the present invention, a method for producing a lithium adsorbing material capable of adsorbing and desorbing lithium ions,
(1) adding a basic solution to the first aqueous solution containing metal ions to prepare a second aqueous solution containing the metal hydroxide oligomer;
(2) adding lithium manganese oxide particles to the second aqueous solution to prepare a suspension;
(3) drying the suspension to form a dry matter;
(4) heating the dried product in an oxidizing atmosphere;
Have
After the step (4), a particulate lithium adsorbing material is obtained, and the particulate lithium adsorbing material comprises lithium manganese oxide particles and a metal oxide covering at least a part of the surface of the lithium manganese oxide particles. seen including,
The concentration of the metal ions in the first aqueous solution ranges from 1 mmol / liter to 1 mol / liter;
The concentration of the basic solution is in the range of 1 mmol / liter to 10 mol / liter,
The pH of the second aqueous solution is in the range of 7 to 12,
In the step (2), the lithium manganese oxide is a spinel type (λ type), and the general formula is Li _1.33 Mn _1.67 O ₄ or Li _1.6 Mn _1.6 O ₄ . And
In the step (4), the heating is performed at a temperature of 400 ° C. to 900 ° C.,
In the particulate lithium adsorbing material obtained after the step (4), the ratio of the metal oxide to the lithium manganese oxide particles is in the range of 7.13 wt% to 20 wt%. A method is provided.

Furthermore, in the present invention, a lithium adsorbing material capable of adsorbing and desorbing lithium ions,
The lithium adsorption material includes a particulate material,
The particulate material is configured such that at least a part of the surface of the lithium manganese oxide particles is coated with an oxide of a metal other than manganese,
The lithium manganese oxide particles are spinel type (λ type), and the general formula is represented by Li _1.33 Mn _1.67 O ₄ or Li _1.6 Mn _1.6 O ₄ .
A lithium adsorbing material is provided, wherein a ratio of the metal oxide to the lithium manganese oxide particles is in a range of 7.13 wt% to 20 wt%.

It is the flowchart which showed roughly the manufacturing method of the lithium adsorption material by one Example of this invention. It is the figure which showed an example of the transmission electron microscope (TEM) photograph of the sample which concerns on the reference example 2. FIG. It is the figure which showed the manganese elution amount and lithium ion desorption amount of the lithium adsorption material which concerns on a reference example compared with the lithium adsorption material which concerns on a comparative example. It is the graph which showed the manganese elution rate and lithium ion desorption rate in the same holding time of another sample when the manganese elution amount and the lithium ion desorption amount obtained in the sample according to Comparative Example 1 were set to 100. It is the figure which showed the manganese elution amount and lithium ion desorption amount of the lithium adsorption material which concerns on an Example compared with the lithium adsorption material which concerns on a comparative example. It is the graph which showed the manganese elution rate and lithium ion desorption rate in the same holding time of another sample when the manganese elution amount and the lithium ion desorption amount obtained in the sample according to Comparative Example 2 were set to 100. It is the figure which showed collectively the result of the lithium ion adsorption / desorption repetition test.

( Reference Example 1 )
As a first aqueous solution, aluminum nitrate was dissolved in deionized water to prepare 20 ml of a 0.125 mol / liter aluminum nitrate aqueous solution.

Next, the obtained dried product was collected and heat-treated in an air atmosphere. The heat treatment temperature was 600 ° C., and the heat treatment time was 1 hour. After the heat treatment, a powdery sample (hereinafter referred to as “sample according to Reference Example 1 ”) was obtained.

From X-ray diffraction analysis of samples according to obtained in Reference Example 1, the samples according to Example 1, the peak of LiMn ₂ O ₄ is clearly observed, even after the heat treatment, the crystal structure of the first particles is maintained It has been confirmed.

Next, fluorescent X-ray analysis was performed using the sample according to Reference Example 1 . From the obtained results, it was found that the sample according to Reference Example 1 contains about 2.09 wt% aluminum oxide by weight with respect to the first particles. From the evaluation with a transmission electron microscope, it was found that the aluminum oxide was formed so as to cover the first particles.

( Reference Example 2 )
A sample according to Reference Example 2 was produced in the same manner as in Reference Example 1 . However, in Reference Example 2 , a magnesium nitrate aqueous solution having a concentration of 0.125 mol / liter was used as the first aqueous solution. Other conditions are the same as in Reference Example 1 .

From X-ray diffraction analysis of a sample according to a reference example 2 obtained, the samples according to Example 2, the peak of LiMn ₂ O ₄ is clearly observed, even after the heat treatment, the crystal structure of the first particles is maintained It has been confirmed.

Next, fluorescent X-ray analysis was performed using the sample according to Reference Example 2 . From the obtained results, it was found that the magnesium oxide having a weight ratio of about 1.81 wt% with respect to the first particles was present in the sample according to Reference Example 2 .

In FIG. 2, an example of the transmission electron microscope (TEM) photograph of the sample concerning the reference example 2 is shown.

( Reference Example 3 )
A sample according to Reference Example 3 was produced in the same manner as in Reference Example 1 . However, in Reference Example 3 , an aqueous nickel nitrate solution having a concentration of 0.125 mol / liter was used as the first aqueous solution. Other conditions are the same as in Reference Example 1 .

From X-ray diffraction analysis of samples according to obtained Reference Example 3, the samples according to Example 3, the peak of LiMn ₂ O ₄ is clearly observed, even after the heat treatment, the crystal structure of the first particles is maintained It has been confirmed.

Next, fluorescent X-ray analysis was performed using the sample according to Reference Example 3 . From the obtained results, it was found that the nickel oxide having a weight ratio of about 4.05 wt% with respect to the first particles was present in the sample according to Reference Example 3 . From the evaluation by a transmission electron microscope, it was found that this nickel oxide was formed so as to cover the first particles.

(Comparative Example 1)
As Comparative Example 1, first particles used as a raw material for lithium manganese oxide (LiMn ₂ O ₄ ) in Reference Examples 1 to 3 described above were prepared. In Comparative Example 1, the first particles were used as they were without performing heat treatment or the like.

( Example 1 )
As a first aqueous solution, aluminum nitrate was dissolved in deionized water to prepare 20 ml of a 0.125 mol / liter aluminum nitrate aqueous solution.

Next, the obtained dried product was collected and heat-treated in an air atmosphere. The heat treatment temperature was 400 ° C., and the heat treatment time was 3 hours. After the heat treatment, a powdery sample (hereinafter referred to as “sample according to Example 1 ”) was obtained.

From X-ray diffraction analysis of samples according to obtained Example 1, the samples according to Example _1, the peak of Li _{1.33 Mn 1.67} O ₄ is clearly observed, even after the heat treatment, the second It was confirmed that the crystal structure of the particles was maintained.

Next, fluorescent X-ray analysis was performed using the sample according to Example 1 . From the obtained results, it was found that the aluminum oxide having a weight ratio of about 7.13 wt% with respect to the second particles was present in the sample according to Example 1 . From the evaluation with a transmission electron microscope, it was found that the aluminum oxide was formed so as to cover the second particles.

( Example 2 )
A sample according to Example 2 was manufactured in the same manner as in Example 1 . However, in Example 6, a nickel nitrate aqueous solution having a concentration of 0.125 mol / liter was used as the first aqueous solution. Other conditions are the same as in the first embodiment .

From X-ray diffraction analysis of samples according to Example 2 obtained, the samples according to Example _2, the peak of Li _{1.33 Mn 1.67} O ₄ is clearly observed, even after the heat treatment, the second It was confirmed that the crystal structure of the particles was maintained.

Next, fluorescent X-ray analysis was performed using the sample according to Example 2 . From the obtained results, it was found that the nickel oxide having a weight ratio of about 11.7 wt% with respect to the second particles was present in the sample according to Example 2 . From the evaluation by a transmission electron microscope, it was found that the nickel oxide was formed so as to cover the second particles.

(Comparative Example 2)
As Comparative Example 2, second particles used as a raw material for lithium manganese oxide (Li _1.33 Mn _1.67 O ₄ ) in Examples 1-2 described above were prepared. In Comparative Example 2, the second particles were used as they were without performing heat treatment or the like.

Table 1 below collectively shows sample manufacturing methods according to Reference Examples 1 to 3 , Examples 1 to 2, and Comparative Examples 1 to 2.

(Evaluation)
(1) Elution characteristic evaluation of each sample The elution characteristic evaluation test was done using the samples according to Reference Examples 1 to 3 , Examples 1 and 2, and Comparative Examples 1 and 2 prepared by the method described above.

First, 0.5 g of the sample according to Reference Example 1 is added to 500 ml of a hydrochloric acid aqueous solution having a concentration of 0.25 mol / liter at room temperature while stirring the hydrochloric acid aqueous solution (stirring speed 200 rpm). The time when the addition is completed is set to 0 (zero) on the time axis. Next, the hydrochloric acid aqueous solution is maintained as it is while stirring is continued, 10 mL of the aqueous solution is sampled at predetermined time intervals, and the manganese concentration and lithium concentration contained in the sampling solution are measured.

Such a test was implemented with respect to each of the samples according to Reference Examples 1 to 3 , Examples 1 and 2, and Comparative Examples 1 and 2, respectively. However, about Examples 1-2 , the sulfuric acid aqueous solution of the same density | concentration was used instead of hydrochloric acid aqueous solution. (For Reference Examples 2 to 3, the same aqueous hydrochloric acid solution as in Reference Example 1 was used.) A high-frequency inductively coupled plasma emission analyzer was used for the measurement of manganese concentration and lithium concentration.

In FIG. 3, the elution characteristic evaluation result of the sample which concerns on Reference Examples 1-3 and the comparative example 1 is shown collectively. In FIG. 3, the horizontal axis represents the retention time (min) of the sample in the aqueous hydrochloric acid solution. In addition, the vertical axis shows the manganese concentration contained in the sampling liquid on the left, that is, the manganese elution amount (mol / liter) per unit mass of lithium manganese oxide contained in the powder sample, The second axis indicates the lithium ion concentration contained in the sampling solution, that is, the lithium ion desorption amount (mol / liter) per unit mass of the lithium manganese oxide contained in the powder sample.

From FIG. 3 and FIG. 4, in the sample according to Comparative Example 1 consisting only of the first particles, the elution amount of manganese is very high (about 0.008 mol / liter) from the initial stage of hydrochloric acid immersion, and this high for 90 minutes. It can be seen that the elution amount is maintained. On the other hand, in the samples according to Reference Examples 1 to 3 including the lithium manganese oxide (LiMn ₂ O ₄ ) particles coated with the metal oxide, the elution of manganese is significantly suppressed as compared with Comparative Example 1. (At most, less than about 0.006 mol / liter).

In particular, as is apparent from FIG. 4, in the sample according to Reference Example 1 , the amount of manganese elution after 90 minutes was reduced by about 42% compared to the sample according to Comparative Example 1.

On the other hand, with respect to the lithium ion desorption characteristics, in the sample according to Comparative Example 1, the lithium ion desorption amount is about 0.02 mol / liter, whereas in the samples according to Reference Examples 1 to 3, it is lower than this. There was a trend. However, the rate of decline is not very noticeable. For example, from FIG. 4, even in the sample according to Reference Example 3 with a small amount of lithium ion desorption, the decrease rate of the lithium ion desorption amount after 90 minutes with respect to the sample according to Comparative Example 1 is only about 25%.

Therefore, in the samples according to Reference Examples 1 to 3, it can be said that the degree of decrease in the lithium ion adsorption / desorption characteristics is small as compared with the manganese elution suppressing effect.

Thus, in the samples according to Reference Examples 1 to 3, it was confirmed that the dissolution amount of manganese can be significantly suppressed without significantly impairing the adsorption / desorption characteristics with respect to lithium ions.

On the other hand, in FIG. 5, the elution characteristic evaluation result of the sample which concerns on Examples 1-2 and the comparative example 2 is shown collectively. In FIG. 5, the horizontal axis represents the retention time (minutes) of the sample in the sulfuric acid aqueous solution. In addition, the vertical axis shows the manganese concentration contained in the sampling liquid on the left, that is, the manganese elution amount (mol / liter) per unit mass of lithium manganese oxide contained in the powder sample, The second axis indicates the lithium ion concentration contained in the sampling solution, that is, the lithium ion desorption amount (mol / liter) per unit mass of the lithium manganese oxide contained in the powder sample.

From FIG. 5 and FIG. 6, in the sample according to Comparative Example 2 consisting of only the second particles, the elution amount of manganese is extremely high from the initial stage of sulfuric acid immersion, and this high elution amount is maintained for 90 minutes. I understand. On the other hand, in the sample according to Examples 1 and 2 including the lithium manganese oxide (Li _1.33 Mn _1.67 O ₄ ) particles partially coated with the metal oxide, the sample according to Comparative Example 2 In comparison with the above, elution of manganese is significantly suppressed. In particular, as apparent from FIG. 6, in the sample according to Example 1 , the manganese elution amount after 90 minutes was reduced by about 25% as compared with the sample according to Comparative Example 2.

On the other hand, regarding the lithium ion desorption characteristics, in the sample according to Comparative Example 2, the lithium ion desorption amount is about 0.03 mol / liter (after 90 minutes), whereas in the sample according to Examples 1-2 , There was a tendency to lower than this. However, as is clear from FIG. 6, even in the sample according to Example 1 having a relatively low lithium ion desorption amount, the decrease rate of the lithium ion desorption amount after 90 minutes with respect to the sample according to Comparative Example 2 is about 15%. It was about.

Therefore, in the samples according to Examples 1 and 2 , it can be said that the degree of decrease in lithium ion desorption characteristics is small as compared with the elution suppression effect of manganese.

Thus, in the samples according to Examples 1 and 2 , it was confirmed that the dissolution amount of manganese can be significantly suppressed without significantly degrading the desorption characteristics for lithium ions.

(3) Lithium Ion Adsorption / Desorption Repeat Test Next, lithium ion adsorption / desorption repeated tests were carried out using the samples according to Example 1 , Example 2 and Comparative Example 2.

The powdery sample (1.0 g) according to Example 1 is placed in 40 mL of lithium ion-containing water at room temperature and held for 1 day. Next, a sample is taken out from the lithium ion-containing water, and the sample is immersed in 125 mL of a 0.25 mol / liter sulfuric acid aqueous solution at room temperature and held for 1 day. This was set as one period, and the immersion of the sample was repeated between the lithium ion-containing water and the sulfuric acid aqueous solution. After completion of each cycle, the manganese concentration and the lithium concentration contained in the sulfuric acid aqueous solution were analyzed. From the obtained results, the elution rate of manganese and the desorption amount of lithium ions in each cycle were evaluated.

Such a test was also performed on each of the samples according to Example 2 and Comparative Example 2.

In FIG. 7, the result of the adsorption / desorption repetition test obtained in the sample which concerns on Example 1 , Example 2, and Comparative Example 2 is shown collectively.

On the other hand, in the samples according to Example 1 and Example 2 , the decrease tendency of the lithium ion desorption amount with respect to the number of cycles is generally gentler than that of the sample according to Comparative Example 1. In particular, in the samples according to Example 1 and Example 2 , the initial lithium ion desorption amount is lower than the sample according to Comparative Example 2, but after the second cycle, the lithium ion desorption amount of the sample according to Comparative Example 1 is reduced. It turns out that it reverses and shows a good lithium ion desorption behavior.

Further, in the samples according to Example 1 and Example 2 , the manganese elution rate is lower than the manganese elution amount of the sample according to Comparative Example 2 in any cycle, and a good manganese elution suppressing effect can be obtained. Recognize.

Claims (14)

A method for producing a lithium adsorbing material capable of adsorbing and desorbing lithium ions,
(1) adding a basic solution to the first aqueous solution containing metal ions to prepare a second aqueous solution containing the metal hydroxide oligomer;
(2) adding lithium manganese oxide particles to the second aqueous solution to prepare a suspension;
(3) drying the suspension to form a dry matter;
(4) heating the dried product in an oxidizing atmosphere;
Have
After the step (4), a particulate lithium adsorbing material is obtained, and the particulate lithium adsorbing material comprises lithium manganese oxide particles and a metal oxide covering at least a part of the surface of the lithium manganese oxide particles. A manufacturing method comprising:   The manufacturing method according to claim 1, wherein the metal is at least one selected from the group consisting of aluminum, magnesium, nickel, iron, and other transition metals. The concentration of the metal ions in the first aqueous solution ranges from 1 mmol / liter to 1 mol / liter;
The method according to claim 1 or 2, wherein the concentration of the basic solution is in the range of 1 mmol / liter to 10 mol / liter.   The manufacturing method according to any one of claims 1 to 3, wherein the pH of the second aqueous solution is in the range of 7 to 12. In the step (2), the lithium manganese oxide is a spinel type (λ type), and the general formulas are LiMn ₂ O ₄ , Li _1.33 Mn _1.67 O ₄ , and Li _1.6 Mn _{1. 5.} The production method according to claim 1, wherein the production method is one or more selected from the group consisting of lithium manganese oxides represented by _.6 O ₄ .   The manufacturing method according to claim 1, wherein the step (3) is performed by drying the suspension while wet-kneading.   In the particulate lithium adsorbing material obtained after the step (4), a ratio of the metal oxide to the lithium manganese oxide particles is in a range of 0.5 wt% to 20 wt%. Item 7. The manufacturing method according to any one of Items 1 to 6.   8. The method according to claim 1, wherein in the step (4), the heating is performed at a temperature of 400 to 900.degree. A lithium adsorbing material capable of absorbing and desorbing lithium ions,
The lithium adsorption material includes a particulate material,
The particulate material is configured such that at least a part of the surface of the lithium manganese oxide particles is coated with an oxide of a metal other than manganese,
The lithium adsorption material, wherein a ratio of the metal oxide to the lithium manganese oxide particles is in a range of 0.5 wt% to 20 wt%.   The lithium adsorbent material according to claim 9, wherein the metal other than manganese is at least one selected from the group consisting of aluminum, magnesium, nickel, iron, and other transition metal oxides.   11. The lithium adsorbing material according to claim 9, wherein a particle diameter of the lithium manganese oxide particles is in a range of 0.1 μm to 1 mm. The lithium manganese oxide particles are of a spinel type (λ type), and the general formula is represented by LiMn ₂ O ₄ , Li _1.33 Mn _1.67 O ₄ , and Li _1.6 Mn _1.6 O _4. The lithium adsorbing material according to claim 9, comprising at least one selected from the group consisting of lithium manganese oxides.   The lithium adsorption according to claim 9, further comprising a substrate for supporting the particulate material, and / or an organic bonding agent for fixing the particulate material. material.   The lithium adsorbing material according to any one of claims 9 to 13, wherein the lithium adsorbing material is used for recovering lithium ions from seawater, salt lake brine, or lithium-containing wastewater.