JP2022110636A - Spinel type lithium manganate, method for producing the same, and use of the same - Google Patents

Abstract

To provide a spinel type lithium manganate excellent in charge/discharge characteristics at a high temperature and a lithium secondary battery excellent in charge/discharge characteristics at a high temperature.SOLUTION: A spinel type lithium manganate contains a phosphate and is represented by chemical formula Li1+XMn2-X-Y-ZMgYMZO4 (In the formula, M is at least one element selected from Al, Ca, Ti, V, Cr, Co, and Ni, and 0.02≤X≤0.10, 0.05≤Y≤0.30, 0≤Z≤0.30), in which the Hausner ratio represented by the ratio of tap density to bulk density is 1.85 or less. A method for producing the spinel type lithium manganate and the use thereof are also provided.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a spinel-type lithium manganate, a method for producing the same, and uses thereof. related to lithium secondary batteries.

Lithium secondary batteries are widely used as storage batteries for portable terminals because they have a higher energy density than other storage batteries. In addition, recently, research is underway aimed at further improving performance, such as application to large-scale, large-capacity, and high-power applications such as stationary and vehicle-mounted applications.

At present, cobalt-based materials (LiCoO ₂ ) are mainly used as positive electrode materials for lithium secondary batteries for consumer small batteries such as mobile phones, and nickel-based materials ( LiNi _0.8 Co _0.15 Al _0.05 O ₂ ) and nickel-cobalt-manganese ternary materials (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ etc.) are mainly used. However, cobalt raw materials and nickel raw materials are not abundant in terms of resources and are expensive, and the output characteristics are not very high.

On the other hand, spinel-type lithium manganese oxide, which is one of the manganese-based materials, has an abundant source of manganese as a raw material, is inexpensive, and has excellent output characteristics and safety. It is one of the materials suitable for use in

However, spinel-type lithium manganate has problems with high-temperature stability, that is, charge-discharge characteristics at high temperatures, particularly charge-discharge characteristics of a carbon counter electrode and storage characteristics, and a solution to this problem has been desired. For example, Patent Literature 1 and Patent Literature 2 both propose spinel-type lithium manganese oxide containing a phosphate, but there is still room for improvement in charge-discharge characteristics at high temperatures, particularly in carbon counter electrode charge-discharge characteristics. there is

Japanese Patent No. 5556983 Japanese Patent Application Laid-Open No. 2017-31006

An object of the present invention is to provide a spinel-type lithium manganate having excellent charge-discharge characteristics at high temperatures, particularly charge-discharge characteristics of a carbon counter electrode, and further to provide a lithium secondary battery using the spinel-type lithium manganate as a positive electrode. It is something to do.

The present inventors have extensively studied spinel-type lithium manganate. As a result, it was found that the present invention having the following summary can achieve the above-described problems. _That is, the present _{invention comprises} a _{phosphate containing} is at least one selected element and satisfies 0.02 ≤ X ≤ 0.10, 0.05 ≤ Y ≤ 0.30, 0 ≤ Z ≤ 0.30). A spinel-type lithium manganate, a method for producing the same, and uses thereof, characterized in that the Hausner ratio, which is the ratio of the tap density to the bulk density, is 1.85 or less.

When the spinel-type lithium manganate of the present invention is used as a positive electrode material for a lithium secondary battery, it is possible to provide a lithium secondary battery with excellent charge-discharge characteristics at high temperatures, especially charge-discharge characteristics of a carbon counter electrode, compared to conventional lithium secondary batteries. become.

The present invention will be described in detail below.

The spinel-type lithium manganate of the present invention has the chemical formula Li _{1+X Mn 2-XYZ} Mg YM _Z O ₄ (wherein M is at least one selected from Al, Ca, Ti, V, Cr, Co and Ni). 0.02≦X≦0.10, 0.05≦Y≦0.30, and 0≦Z≦0.30).

In the chemical formula, M may be at least one element selected from the group consisting of Al, Ca, Ti, V, Cr, Co and Ni.

If the value of X in the chemical formula is less than 0.02, the capacity tends to decrease during charge/discharge at high temperature, and if it exceeds 0.10, sufficient charge/discharge capacity cannot be obtained. Also, if the value of Y is less than 0.05, the capacity tends to decrease during charge/discharge at high temperature, and if it exceeds 0.30, sufficient charge/discharge capacity cannot be obtained. Moreover, when the value of Z exceeds 0.30, sufficient charge/discharge capacity cannot be obtained. X, Y, and Z of the spinel-type lithium manganate can be obtained from composition analysis. Examples of the method include inductively coupled plasma emission spectrometry, atomic absorption spectrometry, and the like.

The spinel-type lithium manganate of the present invention has a Hausner ratio of 1.85 or less. When the Hausner ratio is 1.85 or less, the fluidity of the powder is increased, and when used as a positive electrode active material in a lithium secondary battery, the uniformity with the conductive aid and binder is increased. Properties, especially carbon counter electrode charge/discharge properties are improved. If the Hausner ratio exceeds 1.85, the uniformity when mixed with the conductive aid or binder is lowered, and the charge/discharge characteristics are lowered, which is not preferable. The Hausner ratio is preferably 1.80 or less, more preferably 1.70 or less, even more preferably 1.60 or less. Here, the Hausner ratio means the ratio of tapped density to bulk density.

When the spinel-type lithium manganese oxide of the present invention is used as a positive electrode active material for a lithium secondary battery, the reaction of capturing hydrogen fluoride slightly contained in the electrolyte of the lithium secondary battery with a phosphate is rapid. As a result, the elution of manganese due to the reaction between hydrogen fluoride and spinel-type lithium manganate is suppressed, and it is possible to suppress the decrease in capacity during charging and discharging at high temperatures. The ratio is preferably 0.0015 or more and 0.1 or less. The phosphorus/manganese molar ratio is preferably 0.002 or more and 0.05 or less, more preferably 0.004 or more and 0.01 or less.

The spinel-type lithium manganate of the present invention contains a phosphate. Here, the phosphate contained in the _{spinel -} type lithium manganate is, for example, a lithium phosphate such as _Li3PO4 or _LiPO3 , or a phosphate such as _{Na3PO4 , NaH2PO4} or _{Na2HPO4 .} Examples include sodium phosphate, potassium phosphate such as K ₃ PO ₄ , KH ₂ PO ₄ and K ₂ HPO ₄ . Li ₃ PO ₄ and LiPO ₃ are preferred, and Li ₃ PO ₄ is more preferred. By containing the above phosphate in the spinel-type lithium manganate, it becomes possible to obtain excellent charge-discharge characteristics at high temperatures when used as a positive electrode active material for a lithium secondary battery. The properties of the phosphate to be contained are not particularly limited, and are crystalline, crystalline and porous, crystalline and dense, amorphous, and amorphous. Non-limiting examples include, but are not limited to, those in a non-crystalline and porous state, and those in an amorphous and dense state.

When the spinel-type lithium manganate of the present invention is used as a positive electrode active material for a lithium secondary battery, it is possible to obtain excellent charge/discharge characteristics at high temperatures and to obtain excellent output characteristics. Therefore, the BET specific surface area is preferably 0.2 m ² /g or more and 1.5 m ² /g or less. The BET specific surface area is preferably 0.2 m ² /g or more and 1.0 m ² /g or less, more preferably 0.2 m ² /g or more and 0.6 m ² /g or less.

When the spinel-type lithium manganese oxide of the present invention is used as a positive electrode active material in a lithium secondary battery, it is possible to obtain excellent output characteristics and to increase the fillability of the positive electrode mixture. Therefore, it is preferable that the average particle size of the secondary particles is 4 μm or more and 20 μm or less. The average particle size of secondary particles is preferably 5 μm or more and 15 μm or less, more preferably 5 μm or more and 10 μm or less.

The spinel-type lithium manganate of the present invention increases crystallinity when used as a positive electrode active material for a lithium secondary battery, suppresses elution of manganese, suppresses crystal structure change accompanying charging and discharging, and is excellent at high temperatures. In order to obtain good charge-discharge characteristics, the half width of the (400) plane measured by XRD is preferably 0.005 or more and 0.06 or less, more preferably 0.005 or more and 0.05 or less. The method for measuring the half-value width is according to <measurement of the half-value width by XRD> in the example. It was calculated by subtracting the half-value width of the substance.

The spinel-type lithium manganese oxide of the present invention has an SO ₄ content of 0.5 to increase the charge-discharge capacity when used as a positive electrode active material for lithium secondary batteries and to obtain excellent charge-discharge characteristics at high temperatures. It is preferably 3 wt % or more and 1.0 wt % or less, more preferably 0.4 wt % or more and less than 0.7 wt %.

The spinel-type lithium manganese oxide of the present invention has a Na content of 3,000 wtppm or less in order to increase the crystallinity and obtain excellent charge-discharge characteristics at high temperatures when used as a positive electrode active material for a lithium secondary battery. and more preferably 1,000 wtppm or less.

Next, the method for producing the spinel-type lithium manganate of the present invention will be described.

The spinel-type lithium manganate of the present invention is a magnesium-manganese-M element composite material (M is at least one element selected from Al, Ca, Ti, V, Cr, Co and Ni. Same below), lithium It is obtained by mixing the raw material and the phosphoric acid raw material, firing at 830° C. or higher and 960° C. or lower in the atmosphere or in a high-concentration oxygen atmosphere (including a pure oxygen atmosphere), and pulverizing.

The form and state of the magnesium-manganese-M element composite material are not limited, and by using a composite compound (magnesium-manganese-M element composite material) obtained by a coprecipitation method etc. Spinel-type lithium manganate having excellent homogeneity can be obtained.

The magnesium-manganese-M element composite raw material can be produced by mixing an aqueous solution containing a magnesium salt compound, a manganese salt compound and a compound of the M element, and an oxidizing agent under pH 8.5 to 10.0 conditions. .

Examples of magnesium salt compounds include water-soluble magnesium salts such as magnesium sulfate, magnesium hydroxide, and magnesium acetate.

Examples of manganese salt compounds include water-soluble manganese salts such as manganese sulfate and manganese nitrate.

Examples of M element compounds include water-soluble M element salts such as aluminum sulfate, nickel sulfate, and cobalt sulfate.

In the production of the magnesium-manganese-M element composite raw material, it is preferable that the ratio of magnesium, manganese and M element is adjusted to the magnesium:manganese:M element ratio of the target spinel-type lithium manganate.

The total concentration (metal concentration) of magnesium, manganese and M elements in the metal salt aqueous solution is arbitrary, but is preferably 1.0 mol/L or more, more preferably 2.0 mol/L or more, in terms of excellent productivity. .

In order to maintain the reaction conditions of pH 8.5 to 10.0, it is preferable to appropriately add and mix an acid or a base. Examples of the acid include, but are not limited to, sulfuric acid, hydrochloric acid, nitric acid, and acetic acid. The base is not particularly limited, but examples include caustic soda, caustic potash, lithium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate and the like.

When adding the acid or base, the acid or base may be added directly or may be added as an aqueous solution. When added as an aqueous solution, the concentration is not particularly limited, but for example, 1 mol/L or more can be exemplified.

In order to maintain the reaction conditions of pH 8.5 to 10.0, it is preferable to add an aqueous solution of caustic soda. A concentration-adjusted sodium oxide aqueous solution can be used.

In the production of the magnesium-manganese-M element composite raw material, the method of adding and mixing an acid or a base to control the pH is not particularly limited. For example, it may be performed continuously or intermittently. may

Examples of the oxidizing agent include, but are not limited to, aerobic gas and hydrogen peroxide water. Examples of the aerobic gas include, but are not limited to, air, oxygen, and the like. Air is most preferred economically. A gas such as air or oxygen is added by bubbling using a bubbler or the like. On the other hand, the hydrogen peroxide solution can be mixed in the same manner as the metal salt solution and the caustic soda solution.

Although the temperature at which the oxidizing agent is added to the aqueous solution containing the magnesium salt compound, the manganese salt compound and the M element compound is not particularly limited, it is usually preferably 40° C. or higher.

The production of the magnesium-manganese-M element composite raw material does not require any special atmosphere control, and can be carried out in a normal atmospheric atmosphere.

The magnesium-manganese-M element composite raw material can be produced either batchwise or continuously. Mixing time is arbitrary in the case of batch type. Examples include 3 to 48 hours.

The magnesium-manganese-M element composite raw material precipitated by the production of the magnesium-manganese-M element composite raw material can be isolated by an operation such as filtration, and further washed and dried for handling. is preferred.

Impurities adhering to and adsorbed on the magnesium-manganese-M element composite material can be removed by washing. The washing method is not particularly limited, but for example, a method of adding a magnesium-manganese-M element composite raw material to water (for example, pure water, tap water, river water, etc.) and dissolving impurities in the water. I can give an example.

Drying can remove moisture from the magnesium-manganese-M element composite material. Although the drying method is not particularly limited, for example, the magnesium-manganese-M element composite raw material is dried by heating at 110 to 150° C. for 2 to 15 hours.

In the production of the magnesium-manganese-M element composite raw material, it may be washed, dried and then pulverized.

In pulverization, powder having an average particle size suitable for the application is obtained. Pulverization conditions are arbitrary as long as the desired average particle size is obtained. For example, wet pulverization, dry pulverization, or the like can be used.

The magnesium-manganese-M element composite raw material obtained by the above method can be used in the method for producing spinel-type lithium manganate of the present invention.

Examples of lithium raw materials include lithium carbonate, lithium hydroxide, lithium nitrate, lithium chloride, lithium iodide, and lithium oxalate.

Examples of phosphoric acid raw materials include lithium phosphates such as Li ₃ PO ₄ and LiPO ₃ , sodium phosphates such as Na ₃ PO ₄ , NaH ₂ PO ₄ and Na ₂ HPO ₄ , K ₃ PO ₄ , KH Potassium phosphates such as _2PO4 , _K2HPO4 , etc. _Magnesium phosphates such as _{Mg3 ( PO4} ) ₂ , _MgHPO4 , _{Mg ( H2PO4 ) 2} , _NH4H2PO4 , (NH ₄ ) ₂ HPO ₄ and ammonium phosphates.

Examples of the method for mixing the magnesium-manganese-M element composite raw material, the lithium raw material and the phosphoric acid raw material include dry mixing and wet mixing. In the case of wet mixing, a method of dissolving the phosphoric acid raw material in a solvent such as water or ethanol and adding it to the magnesium-manganese-M element composite raw material and the lithium raw material is exemplified.

Firing for obtaining the spinel-type lithium manganate of the present invention is carried out in the air or in a high-concentration oxygen atmosphere (including a pure oxygen atmosphere), that is, in an oxygen atmosphere with an oxygen content of 18 to 100 vol%, It is carried out at 830° C. or more and 960° C. or less. When the temperature is lower than 830°C, the BET specific surface area of the spinel-type lithium manganate tends to increase, and when it exceeds 960°C, the oxygen deficiency of the spinel-type lithium manganate increases. charge-discharge cycle characteristics tend to deteriorate when Firing is preferably performed at 850° C. or higher and 950° C. or lower, more preferably 900° C. or higher and 950° C. or lower.

Secondary particles of spinel-type lithium manganate are likely to solidify with each other during firing, so pulverization is performed to obtain a desired particle size. As the crushing method, crushing by shearing force is preferable in order to suppress the generation of fine powder and the increase in BET specific surface area.

After the spinel-type lithium manganate is pulverized, it is preferably passed through a sieve in order to remove coarse particles exceeding the thickness of the positive electrode. The mesh size of the sieve is preferably 100 μm or less, more preferably 50 μm or less.

By using the spinel-type lithium manganate of the present invention for the positive electrode of a lithium secondary battery, a lithium secondary battery with excellent charge-discharge cycle characteristics at high temperatures and excellent output characteristics, which could not be obtained in the past, can be obtained. be able to configure.

The configuration of the _{lithium secondary} battery other than the _positive electrode is not particularly limited. A material that forms an alloy is exemplified. Examples of materials forming an alloy with Li include silicon-based materials and aluminum-based materials. Examples of the electrolyte include an organic electrolytic solution obtained by dissolving a Li salt and various additives in an organic solvent, a Li ion-conducting solid electrolyte, a combination thereof, and the like.

EXAMPLES Next, the present invention will be described with specific examples, but the present invention should not be construed as being limited to these examples.

<Measurement of Hausner ratio>
The density (bulk density) immediately after filling the spinel-type lithium manganate obtained in Examples and Comparative Examples into a graduated cylinder without tapping and the density (tapped density) after tapping 200 times were measured.

From the measured bulk density and tap density, the Hausner ratio was calculated according to the following formula.

Hausner ratio = tap density/bulk density <Battery performance test>
The spinel-type lithium manganate obtained in each example and a conductive binder (trade name: TAB-2, manufactured by Hosen) were mixed at a weight ratio of 1/2 using an agate mortar. The resulting mixture was uniaxially pressed at 2 ton/cm ² onto a SUS mesh (SUS316) with a diameter of 16 mmφ to form disc-shaped pellets, which were then dried under reduced pressure at 150° C. for 2 hours to obtain a positive electrode.

As the negative electrode, a spherulitic graphite sheet (TSG-A1 manufactured by Hosen, nominal capacity 1.6 mAh/cm ² ) was punched out to a diameter of 16.156 mmφ and then uniaxially pressed at 3 tons/cm ² . The amount of the positive electrode active material was adjusted so that the /positive electrode capacity ratio was 1.2.

A solution of 1 mol/dm ³ of LiPF ₆ dissolved in a solvent of ethylene carbonate and dimethyl carbonate at a volume ratio of 1:2 was used as the electrolyte, and a polyethylene sheet (trade name: Celgard, manufactured by Polypore) was used as the separator. A battery using a CR2032 type coin cell was produced.

Using the prepared battery, one cycle of constant-current constant-voltage charge-constant-current discharge was performed at 24° C. at a cell voltage between 4.25 V and 3.0 V and a current density of 0.14 mA/cm ² . Then, at 24° C., one cycle of constant-current constant-voltage charge-constant-current discharge was performed at a cell voltage between 4.25 V and 3.0 V and a current density of 0.28 mA/cm ² , and the discharge capacity was taken as the battery capacity. . Next, at 60 ° C., the cell voltage is between 4.25 V and 3.0 V, the constant current constant voltage charge-constant current discharge is performed 50 cycles at the current density of the discharge rate for 1 hour with respect to the battery capacity, and the 50th cycle The charge-discharge cycle characteristics of the carbon counter electrode were obtained from the ratio of the discharge capacity at the first cycle and the discharge capacity at the first cycle. The termination condition of the constant voltage charging was the time point when the charging current attenuated to 1/10 of that of the constant voltage charging.

<Composition analysis, measurement of _SO4 content, Na content>
The composition, _SO4 content, and Na content of the spinel-type lithium manganate obtained in Examples and Comparative Examples were determined by dissolving the spinel-type lithium manganate in a hydrochloric acid-hydrogen peroxide mixed aqueous solution, followed by inductively coupled plasma emission spectrometry. Analysis was performed using an apparatus (trade name: ICP-AES, manufactured by PerkinElmer Japan).

<Measurement of BET specific surface area>
1.0 g of the sample was placed in a glass cell for BET specific surface area measurement and dehydrated at 150° C. for 30 minutes under a nitrogen stream to remove water adhering to the powder particles.

The BET specific surface area of the treated sample was measured by the one-point method using a BET measurement device (trade name: MICROMERITICS DeSorb III, manufactured by Shimadzu Corporation) using a mixed gas of 30% nitrogen and 70% helium as the adsorption gas. .

<Measurement of half width by XRD>
For the spinel-type lithium manganese oxides obtained in Examples and Comparative Examples, the half-value width was measured by XRD using a powder XRD measurement device (trade name: Ultima IV, manufactured by Rigaku). The measurement conditions were as follows.

・Target: Cu
・Output: 1.6kW (40mA-40kV)
・Filter: Kβ filter ・Divergence slit: 1°
・Vertical divergence limiting slit: 10 mm
・Scattering slit: open ・Receiving slit: open ・Scanning mode: continuous ・Scan speed: 4.000°/min ・Sampling width: 0.04° (2θ/θ)
・Number of times of integration: 1 time ・Measurement range: 10-90° (2θ/θ)
The XRD data of the obtained spinel-type lithium manganate was analyzed using analysis software (PDXL2) attached to the powder X-ray diffraction measurement device, and the integrated width of the (400) plane near 2θ = 44° was determined.

In addition, in order to correct the error of the measuring device, the XRD standard material (α-type quartz powder manufactured by NIST) was measured in advance, and the half-value width was obtained by subtracting the integration width of the standard material from the integration width of the spinel-type lithium manganate. rice field.

Example 1
Magnesium sulfate, aluminum sulfate and manganese sulfate are dissolved in pure water to prepare an aqueous solution (metal salt aqueous solution) was obtained. Further, after 8 L of pure water was put into a reaction vessel having an inner volume of 10 L, the temperature was raised to 60° C. and maintained.

The obtained metal salt aqueous solution was continuously supplied to the reactor at a supply rate of 12 g/min. As an oxidizing agent, air was bubbled into the reactor at a supply rate of 0.5 L/min. Furthermore, when supplying the metal salt aqueous solution and air, the reaction was allowed to proceed continuously while continuously adding a 5 mol/L sodium hydroxide aqueous solution (caustic soda aqueous solution) so that the pH was 8.7 (reaction The oxidation-reduction potential at that time was 0.08 V). Due to the above reaction, the magnesium-manganese-aluminum composite raw material precipitated in the reaction vessel to obtain a slurry. A wet cake was obtained by filtering the slurry in the reaction vessel and washing with pure water. The wet cake was dried at 110° C. for 15 hours to obtain a magnesium-manganese-aluminum composite raw material.

A solution of 0.07 g of Mg(H ₂ PO ₄ ) ₂ dissolved in 2 g of pure water was added to 20 g of the magnesium-manganese-aluminum composite material obtained, and dried at 60° C. for 1 hour. and 0.8 g of lithium carbonate were mixed, baked in a box furnace at 930° C. for 6 hours while air was circulated at a rate of 5 L/min, and cooled to room temperature. The temperature increase rate was 100°C/hr, the temperature decrease rate was 20°C/hr from 850°C to 600°C, and 100°C/hr from 600°C to room temperature. After pulverizing the obtained phosphate-containing spinel-type lithium manganate with a powerful small crusher (trade name: Force Mill, manufactured by Osaka Chemical), it is passed through a sieve with an opening of 32 μm to obtain a phosphate-containing spinel type. Lithium manganate was obtained.

The composition of the obtained phosphate-containing _{spinel -} type lithium _{manganese oxide} was _{Li1.04Mn1.85Mg0.09Al0.02O4} . Further, from the XRD measurement, the obtained phosphate-containing spinel-type lithium manganate was JCPDS No. 35-782 (LiMn ₂ O ₄ ) and No. It was a mixed phase of 25-1030 (Li ₃ PO ₄ ). The phosphorus/manganese molar ratio, the Hausner ratio, the BET specific surface area, the average particle size of the lithium manganate secondary particles, and the measurement results of the half width of the (400) plane by XRD measurement (hereinafter referred to as measurement results) are shown in Table 1. Table 2 shows the battery performance.

Example 2
Using a magnesium-manganese-aluminum composite oxide obtained from a metal salt aqueous solution containing 0.08 mol/L (liter) of magnesium sulfate, 0.03 mol/L of aluminum sulfate and 2.0 mol/L of manganese sulfate; , a phosphate-containing spinel-type lithium manganate was obtained in the same manner as in Example 1, except that the sintering temperature was changed to 950°C.

The composition of the obtained phosphate-containing _{spinel -} type lithium _{manganese oxide} was _{Li1.05Mn1.85Mg0.08Al0.02O4} . Further, from the XRD measurement, the obtained phosphate-containing spinel-type lithium manganate was JCPDS No. 35-782 (LiMn ₂ O ₄ ) and No. It was a mixed phase of 25-1030 (Li ₃ PO ₄ ). Table 1 shows the measurement results, and Table 2 shows the battery performance.

Example 3
Using a magnesium-manganese-aluminum composite oxide obtained from a metal salt aqueous solution containing 0.05 mol/L (liter) of magnesium sulfate, 0.05 mol/L of aluminum sulfate and 2.0 mol/L of manganese sulfate; , Mg(H ₂ PO ₄ ) ₂ was changed from 0.07 g to 0.035 g to obtain a phosphate-containing spinel-type lithium manganate in the same manner as in Example 1.

The composition of the obtained phosphate-containing _{spinel -} type lithium _{manganese oxide} was _{Li1.03Mn1.85Mg0.05Al0.05O4} . Further, from the XRD measurement, the obtained phosphate-containing spinel-type lithium manganate was JCPDS No. 35-782 (LiMn ₂ O ₄ ) and No. It was a mixed phase of 25-1030 (Li ₃ PO ₄ ). Table 1 shows the measurement results, and Table 2 shows the battery performance.

Example 4
Using a magnesium-manganese-nickel composite oxide obtained from a metal salt aqueous solution containing 0.08 mol/L (liter) of magnesium sulfate, 0.03 mol/L of nickel sulfate, and 2.0 mol/L of manganese sulfate; , a phosphate-containing spinel-type lithium manganate was obtained in the same manner as in Example 1, except that the sintering temperature was changed to 900°C.

The composition of the obtained phosphate-containing _{spinel -} type lithium _{manganese oxide} was _{Li1.04Mn1.86Mg0.08Ni0.02O4} . Further, from the XRD measurement, the obtained phosphate-containing spinel-type lithium manganate was JCPDS No. 35-782 (LiMn ₂ O ₄ ) and No. It was a mixed phase of 25-1030 (Li ₃ PO ₄ ). Table 1 shows the measurement results, and Table 2 shows the battery performance.

Example 5
Using a magnesium-manganese-cobalt composite oxide obtained from a metal salt aqueous solution containing 0.08 mol/L (liter) of magnesium sulfate, 0.03 mol/L of cobalt sulfate and 2.0 mol/L of manganese sulfate; , a phosphate-containing spinel-type lithium manganate was obtained in the same manner as in Example 1, except that the sintering temperature was changed to 900°C.

The composition of the obtained phosphate-containing _{spinel -} type lithium _{manganese oxide} was _{Li1.05Mn1.85Mg0.08Co0.02O4} . Further, from the XRD measurement, the obtained phosphate-containing spinel-type lithium manganate was JCPDS No. 35-782 (LiMn ₂ O ₄ ) and No. It was a mixed phase of 25-1030 (Li ₃ PO ₄ ). Table 1 shows the measurement results, and Table 2 shows the battery performance.

Comparative example 1
Manganese sulfate was dissolved in pure water to obtain a 2.0 mol/L manganese sulfate aqueous solution. Further, after 8 L of pure water was put into a reaction vessel having an inner volume of 10 L, the temperature was raised to 60° C. and maintained.

The manganese sulfate aqueous solution thus obtained was continuously supplied to the reactor at a supply rate of 12 g/min. As an oxidizing agent, air was bubbled into the reactor at a supply rate of 0.5 L/min. Furthermore, when supplying an aqueous manganese sulfate solution and air, the reaction was allowed to proceed continuously while continuously adding a 5 mol/L sodium hydroxide aqueous solution (caustic soda aqueous solution) so that the pH was 7.5 (reaction The oxidation-reduction potential at that time was 0.08 V). Due to the reaction, Mn ₃ O ₄ was precipitated in the reaction vessel to obtain a slurry. A wet cake was obtained by filtering the slurry in the reaction vessel and washing with pure water. Mn ₃ O ₄ was obtained by drying the wet cake at 110° C. for 15 hours.

After 3 g of Mn ₃ O ₄ , 0.8 g of Li ₂ CO ₃ , and 0.12 g of Mg(OH) ₂ (manufactured by Wako Pure Chemical Industries, average particle size: 0.07 μm) were dry-mixed, Firing, pulverization and classification were performed in the same manner. The composition of the obtained _{spinel -} type lithium _manganate was _{Li1.04Mn1.86Mg0.10O4} . Further, from the XRD measurement, the obtained spinel-type lithium manganate was JCPDS No. 35-782 (LiMn ₂ O ₄ ) single phase. Table 1 shows the measurement results, and Table 2 shows the battery performance. From Table 2, it is clear that Comparative Example 1 is inferior to Examples in carbon counter electrode cycle characteristics.

The spinel-type lithium manganate of the present invention has Mg atoms and M elements uniformly dispersed, and has a specific Hausner ratio, BET specific surface area and secondary particle size. It can be used as a positive electrode active material for lithium secondary batteries with excellent characteristics and output characteristics.

Claims (10)

containing a phosphate and having the chemical formula Li _{1+X Mn 2-XYZ} Mg YM _Z O ₄ (wherein M is at least one selected from Al, Ca, Ti, V, Cr, Co and Ni); element and 0.02 ≤ X ≤ 0.10, 0.05 ≤ Y ≤ 0.30, 0 ≤ Z ≤ 0.30). A spinel-type lithium manganate having a Hausner ratio of 1.85 or less, which is expressed as a ratio of tap densities. 2. The spinel-type lithium manganate according to claim 1, wherein the phosphorus/manganese molar ratio is 0.0015 or more and 0.1 or less. The spinel-type lithium manganate according to claim 1 or 2, having a BET specific surface area of 0.2 m ² /g or more and 1.5 m ² /g or less. 4. The spinel-type lithium manganate according to claim 1, wherein the secondary particles have an average particle size of 4 μm or more and 20 μm or less. 5. The spinel-type lithium manganate according to any one of claims 1 to 4, wherein the half width of the (400) plane by XRD measurement is 0.005 or more and 0.08 or less. The spinel-type lithium manganate according to any one of claims 1 to 5, characterized in that the content of SO ₄ is 0.3 wt% or more and 1.0 wt% or less. The spinel-type lithium manganate according to any one of claims 1 to 6, wherein the Na content is 3,000 wtppm or less. Magnesium-manganese-M element composite raw material (M is at least one element selected from Al, Ca, Ti, V, Cr, Co and Ni), a lithium raw material and a phosphoric acid raw material are mixed, in the air, or , The spinel-type manganic acid according to any one of claims 1 to 7, which is fired at 830 ° C. or higher and 960 ° C. or lower in a high-concentration oxygen atmosphere (including a pure oxygen atmosphere) and pulverized. A method for producing lithium. An electrode comprising the spinel-type lithium manganate according to any one of claims 1 to 7. A lithium secondary battery, wherein the electrode according to claim 9 is used as a positive electrode.