JP5229472B2 - Lithium manganate particles for non-aqueous electrolyte secondary battery, method for producing the same, and non-aqueous electrolyte secondary battery - Google Patents

Description

  The present invention provides lithium manganate having high output and excellent high-temperature stability.

  In recent years, electronic devices such as AV devices and personal computers are rapidly becoming portable and cordless, and there is an increasing demand for secondary batteries having a small size, light weight, and high energy density as power sources for driving these devices. Under such circumstances, a lithium ion secondary battery having advantages such as a high charge / discharge voltage and a large charge / discharge capacity has attracted attention.

Conventionally, as a positive electrode active material useful for a high energy type lithium ion secondary battery having a voltage of 4 V class, spinel type structure LiMn ₂ O ₄ , rock salt type structure LiMnO ₂ , LiCoO ₂ , LiCo _1-X Ni _X O ₂ , LiNiO _2, etc. are generally known. Among them, LiCoO ₂ is excellent in that it has a high voltage and a high capacity, but there is a problem of high manufacturing cost due to a small supply amount of cobalt raw material. It includes environmental safety issues of waste batteries. Therefore, research on spinel-structure-type lithium manganate particles (basic composition: LiMn ₂ O ₄ -hereinafter the same-) made from manganese, which is supplied at a low cost and has good environmental friendliness, has been actively conducted. Yes.

  As is well known, the lithium manganate particle powder can be obtained by mixing a manganese compound and a lithium compound at a predetermined ratio and firing at a temperature range of 700 to 800 ° C.

  However, when lithium manganate particle powder is used as a positive electrode active material of a lithium ion secondary battery, although it has a high voltage and a high energy density, there is a problem that charge / discharge cycle characteristics are inferior. This is due to the fact that the crystal lattice expands and contracts due to the lithium ion desorption / insertion behavior in the crystal structure with repeated charge and discharge, resulting in lattice breakage due to the volume change of the crystal and the dissolution of Mn in the electrolyte. It is said that.

  In lithium ion secondary batteries using lithium manganate particles, the most current demand is to suppress deterioration of charge / discharge capacity due to repeated charge / discharge and to improve charge / discharge cycle characteristics at high and low temperatures. Has been.

  In order to improve the charge / discharge cycle characteristics, it is necessary that the positive electrode active material made of lithium manganate particle powder is excellent in filling property, has an appropriate size, and further suppresses elution of Mn. As the means, a method of controlling the particle size and particle size distribution of lithium manganate particles, a method of obtaining a highly crystalline lithium manganate particle powder by controlling the firing temperature, and strengthening the bonding power of crystals by adding different elements For example, a method of suppressing the elution of Mn by performing a surface treatment or mixing an additive is performed.

  Until now, it has been known that lithium manganese oxide particle powder contains aluminum as one of different elements (Patent Documents 1 to 6). Further, it is known that a sintering aid effect can be obtained by adding a sintering aid having a melting point of 800 ° C. or less, particularly boron oxide, boric acid, lithium borate, or ammonium borate at the time of firing. (Patent Documents 7 to 11).

Lithium manganate particle powder contains Ca compound and / or Ni compound and Al compound (Patent Document 1), Lithium manganate particle powder contains Al, and the peak position of each diffraction surface of X-ray diffraction Limiting (Patent Document 2), Lithium manganate particle powder contains different elements such as Al, and firing is performed in multiple stages (Patent Document 3), Lithium manganate particle powder contains Al In addition, lithium manganate having a specific surface area of 0.5 to 0.8 m ² / g and a sodium content of 1000 ppm or less (Patent Document 4), and lithium manganate particle powder contains a different element such as Al. In addition, lithium manganate having a (400) plane half width of 0.22 ° or less and an average diameter of crystal grains of 2 μm or less (patent document ), Lithium manganate particles containing different elements such as Al, lithium manganate having a crystallite size of 600 mm or more and a lattice strain of 0.1% or less (Patent Document 6), lithium compound and manganese dioxide Lithium manganate (Patent Document 7) that heat-treats the boron compound and boron compound at a temperature of 600 ° C. to 800 ° C., an element having an oxide melting point of 800 ° C. or lower, and a fluorine compound added (Patent Document 8) ), A lithium secondary battery containing 5 to 20% by weight of lithium manganate containing lithium and lithium manganate (Patent Document 9), tetraboric acid fired at 700 to 850 ° C. A lithium manganate containing lithium (Patent Document 10) is described.

JP 2000-294237 A JP 2001-146425 A JP 2001-328814 A JP 2002-33099 A JP 2002-316823 A JP 2006-252940 A JP-A-8-195200 JP 2001-48547 A JP 2002-170566 A JP 2005-127710 A

  As the positive electrode active material for nonaqueous electrolyte secondary batteries, lithium manganate that improves output characteristics and high-temperature characteristics is currently most demanded, but no material that satisfies the necessary and sufficient requirements has yet been obtained.

That is, Patent Documents 1 to 10 describe lithium manganate obtained by substituting a part of manganese for a metal element with a different element, and lithium manganate to which a small amount of a boron compound is added. The storage characteristics were not satisfactory and practically still insufficient.
Further, even if the crystallinity is improved, the high-temperature storage characteristics are not at a satisfactory level, and are insufficient in practical use.

  The technical problem can be achieved by the present invention as follows.

That is, the present invention is a lithium manganate particle powder having a primary particle diameter of 1 μm or more and substantially forming single-phase particles,
_{Formula: Li 1 + x Mn 2-} x-y Y1 y O 4 + Y2 (Y1 = Ni, Co, Mg, Fe, Al, Cr, at least one of: Ti, Y2 = melting point of 800 ° C. or less sintering aid At least one element constituting 0.03 ≦ x ≦ 0.15, 0.05 ≦ y ≦ 0.20, Y2: 0.1 mol% to 2.5 mol% with respect to Mn), and Y1 The element is dispersed inside the particle, and the X-ray diffraction intensity I (400) / I (111) is 38% or more and I (440) / I (111) is 18% or more. This is a lithium manganate particle powder (Invention 1).

  Moreover, this invention is a lithium manganate particle powder of this invention 1 characterized by having a lattice constant of 0.818 to 0.821 nm (present invention 2).

Moreover, this invention is a particle powder of the lithium manganate in any one of this invention 1-2 whose specific surface area is 0.3-1.25 m < ² > / g (BET method) (this invention 3).

  Moreover, this invention is a lithium manganate particle powder in any one of this invention 1-3 whose average particle diameter (D50) is 1.0-15 micrometers (invention 4).

  The present invention also provides lithium carbonate, manganese oxide coated with a compound of at least one element selected from Ni, Co, Mg, Fe, Al, Cr, and Ti, and a sintering aid having a melting point of 800 ° C. or lower. It is a manufacturing method of the lithium manganate particle powder in any one of this invention 1-4 characterized by baking at 800 to 1050 degreeC after adding and mixing an agent (invention 5).

  Further, the present invention relates to an aqueous suspension in which manganese oxide coated with a compound of at least one element selected from Ni, Co, Mg, Fe, Al, Cr, and Ti contains manganese oxide. An aqueous solution containing a salt of at least one element selected from Co, Mg, Fe, Al, Cr, and Ti is added to adjust the pH of the suspension, and Ni, Co, Mg are formed on the surface of the manganese oxide particles. This is a method for producing lithium manganate particle powder according to the present invention 5 obtained by forming a coating of a compound of at least one element selected from Fe, Al, Cr, Ti (Invention 6).

  Further, the present invention provides a book in which a compound of at least one element selected from Ni, Co, Mg, Fe, Al, Cr, and Ti formed on the surface of manganese oxide particles is amorphous by X-ray diffraction. It is a manufacturing method of the lithium manganate particle powder of invention 6, (this invention 7).

  Further, the present invention is the method for producing lithium manganate particle powder according to any one of the present inventions 5 to 7, wherein the manganese oxide is substantially single crystal and the average particle diameter is 1 μm or more (the present invention). 8).

  Moreover, this invention is a non-aqueous-electrolyte secondary battery using the lithium manganate particle powder in any one of this invention 1-4 as a positive electrode active material or its part (this invention 9).

In addition, the present invention uses a lithium manganate particle powder as a positive electrode active material, a non-aqueous electrolyte solution to which 1 mol / l LiPF ₆ is added (mixed at a ratio of EC: DEC = 3: 7), and a negative electrode In the CR2032-type non-aqueous electrolyte secondary battery using a 150 μm thick Li foil, the initial discharge capacity is 80 mAh / g or more and 120 mAh / g or less when the charge / discharge capacity is measured. It is a lithium manganate particle powder in any one of 1-4 (this invention 10).

In addition, the present invention uses a lithium manganate particle powder as a positive electrode active material, a non-aqueous electrolyte solution to which 1 mol / l LiPF ₆ is added (mixed at a ratio of EC: DEC = 3: 7), and a negative electrode In a CR2032-type non-aqueous electrolyte secondary battery using a 150 μm-thick Li foil, a 30-cycle charge / discharge test was performed at a rate of 1 hour in a 60 ° C. constant temperature bath. The lithium manganate particle powder according to any one of the present inventions 1 to 4, wherein the discharge capacity ratio at the cycle is 93% or more (Invention 11).

In addition, the present invention uses a lithium manganate particle powder as a positive electrode active material, a non-aqueous electrolyte solution to which 1 mol / l LiPF ₆ is added (mixed at a ratio of EC: DEC = 3: 7), and a negative electrode In the CR2032-type non-aqueous electrolyte secondary battery using a 150 μm thick Li foil, the initial discharge capacity was measured when charging / discharging at a voltage of 3.0 to 4.5 V at a time rate of 0.1 C ( a) Thereafter, after charging to 4.5 V at a time rate of 0.1 C and discharging to a depth of discharge of 70%, after leaving at 60 ° C. for 1 week, further discharging when charging and discharging at 0.1 C The lithium manganate particle powder according to any one of claims 1 to 4, wherein the capacity recovery rate is 95% or more when the capacity measurement (d) is performed to obtain a capacity recovery rate (= 100 x d / a). There is (Invention 12).

  The lithium manganate particle powder according to the present invention has a high output and is particularly excellent in high-temperature stability, and therefore is suitable as a positive electrode active material for a non-aqueous electrolyte secondary battery.

Further, when a sintering aid having a melting point of 800 ° C. or less is added to manganese oxide, in particular, a small amount of boric acid (H ₃ BO ₃ ) is added to Mn ₃ O ₄ and mixed with lithium carbonate. Lithium manganate particles having excellent characteristics can be obtained by firing at a temperature.

  The configuration of the present invention will be described in more detail as follows.

  First, the lithium manganate particle powder for nonaqueous electrolyte secondary batteries according to the present invention will be described.

  The lithium manganate particle powder according to the present invention contains at least one element (Y1) selected from Ni, Co, Mg, Fe, Al, Cr, and Ti. Moreover, it is a lithium manganate particle powder in which the (400) and (440) planes grow with respect to the (111) plane.

The chemical formula of the lithium manganate particles according to the present invention is Li _{1 + x} Mn _2−xy Y 1 O ₄ + Y 2, and Y 1 is at least one selected from Ni, Co, Mg, Fe, Al, Cr, and Ti. . Y2 is at least one constituent element in the sintering aid having a melting point of 800 ° C. or lower.
Among these, x is 0.03-0.15 and y is 0.05-0.20.
When x is less than 0.03, the capacity is increased, but the high temperature characteristics are remarkably deteriorated. When it exceeds 0.15, the high temperature characteristics are improved, but the capacity is remarkably lowered or a Li-rich phase is generated, which causes an increase in resistance. More preferably, it is 0.05-0.15.
When y is less than 0.05, a sufficient effect cannot be obtained. If it exceeds 0.20, the capacity drop is increased, which is not practical. More preferably, it is 0.05-0.15.
The content of Y2 is 0.1 to 2.5 mol% with respect to Mn. When the content of Y2 is less than 0.1 mol% with respect to Mn, a sufficient effect of adding the sintering aid cannot be obtained. When the amount exceeds 2.5 mol%, the degree of aggregation and fusion of lithium manganate particles becomes too strong, and fine powder is generated, which is not preferable. The content of Y2 is more preferably 0.5 to 2.0 mol% with respect to Mn.

  The Y1 element (at least one selected from Ni, Co, Mg, Fe, Al, Cr, Ti) of the lithium manganate particles according to the present invention is present inside the particles. The Y1 element is preferably present uniformly throughout the particle without being unevenly distributed from the particle surface of the lithium manganate particle to the particle center. In the state where the Y1 element is present uniformly, an EPMA surface analysis of the cross section of the particle is performed, and the white area indicating the presence of the Y1 element is 95% or more of the particle cross section, more preferably 98% or more, still more preferably This is the case when it is 100%. When the Y1 element is unevenly distributed, the stability is lowered when a secondary battery is manufactured.

  The Y2 element is preferably present in the vicinity of the particle surface, compounded with Li, and uniformly coated. When the Y2 element is also present inside the lithium manganate particles, the stability may be lowered when a secondary battery is produced.

In the X-ray diffraction of the lithium manganate particles according to the present invention, the peak intensity ratio I (400) / I (111) is 38% or more, and I (440) / I (111) is 18% or more.
When the intensity ratios of I (400) and I (440) are out of the above ranges, the stability and output are lowered. More preferably, I (400) / I (111) is 40 to 70% and I (440) / I (111) is 20 to 50%.

  The lattice constant of the lithium manganate particles according to the present invention is preferably 0.818 to 0.821 nm. If it is less than 0.818 nm, the capacity decreases. When it exceeds 0.821 nm, the stability is lowered. More preferably, the lattice constant is 0.819 to 0.821 nm.

The BET specific surface area of the lithium manganate particles according to the present invention is preferably 0.3 to 1.25 m ² / g. When the BET specific surface area is less than 0.3 m ² / g, the output decreases. When it exceeds 1.25 m ² / g, the stability decreases. More preferably, the BET specific surface area is 0.35 to 1.2 m ² / g.

  As for the average particle diameter (D50: secondary particle diameter) in the particle size distribution meter of the lithium manganate particle powder which concerns on this invention, 1.0-15 micrometers is preferable. When the average particle size is less than 1.0 μm, the stability is lowered. When the average particle size exceeds 15 μm, the output decreases. The average particle size of the lithium manganate particle powder is more preferably 2 to 10 μm, still more preferably 2 to 9 μm.

  The average primary particle diameter of the lithium manganate particles according to the present invention is preferably 1.0 to 10 μm. When the average primary particle size is less than 1.0 μm, the stability is lowered. When the average primary particle diameter exceeds 10 μm, the output decreases. More preferably, the average primary particle size is 1.0 to 9.0 μm.

  The lithium manganate particle powder according to the present invention substantially consists of a single phase. In the case of a polycrystal, a large number of lattice mismatch planes exist, so that it becomes a resistance component against lithium desorption and the output is difficult to obtain.

  Next, a method for producing lithium manganate particles according to the present invention will be described.

The lithium manganate particle powder according to the present invention uses substantially single-phase manganese trioxide (Mn ₃ O ₄ ) as a manganese precursor, and the manganese precursor is treated in an aqueous solution to obtain Ni, Co , Mg, Fe, Al, Cr, Ti, a compound composed of at least one element selected from manganese, a very fine and low crystallinity compound (a state that cannot be detected by X-ray diffraction even when added at 10 mol%). After surface treatment and then mixing with surface-treated manganese oxide, lithium carbonate and a sintering aid having a melting point of 800 ° C. or lower, firing is performed at a temperature range of 800 ° C. or higher, preferably 850 to 1050 ° C. Can do.

As the manganese oxide in the present invention, trimanganese tetraoxide (Mn ₃ O ₄ ) is preferable. As trimanganese tetraoxide (Mn ₃ O ₄ ), it is preferable that the average particle diameter (D50) is 1 to 8 μm, the primary particle diameter is 1 to 10 μm, and the BET specific surface area is 0.5 to 15 m ² / g.

  When manganese precursors with good crystallinity are used, the reactivity with surface-coated compounds such as Al compounds decreases, so even if submicron-sized aluminum compounds are used, a uniform solid solution state is obtained. It is difficult to make a finely mixed aluminum compound with low crystallinity that cannot be detected by X-ray diffraction.

  In order to make the surface coating (aluminum compound, etc.) into the above state, after forming a homogeneous mixed state of manganese precursor and aluminum ions by mixing an ionic aqueous solution of aluminum with a suspension of manganese oxide By adjusting the pH, a fine and low crystalline hydroxide can create a homogeneous mixed state with the manganese precursor.

  As for the reaction conditions, when the aluminum compound is coated, the pH of the reaction solution is controlled to 6 to 10, and the reaction temperature is controlled to 10 to 90 ° C.

  For example, when Mg is coated, the pH of the reaction solution is controlled to 9 to 11, and the reaction temperature is controlled to 10 to 90 ° C. When coating Co, it is preferable to control the pH to 7 to 10 and the reaction temperature to 10 to 90 ° C. When coating Ni, it is preferable to control the pH to 9 to 11 and the reaction temperature to 10 to 90 ° C. When coating Fe, it is preferable to control pH to 9-11 and reaction temperature to 10-90 degreeC. When coating with Cr, it is preferable to control the pH to 6 to 10 and the reaction temperature to 10 to 90 ° C. When coating Ti, it is preferable to control the pH to 6 to 10 and the reaction temperature to 10 to 90 ° C.

  In the present invention, sintering is performed by adding a sintering aid having a melting point of 800 ° C. or lower. More preferred is a sintering aid having a melting point of 600 ° C. or lower. As a sintering aid having a melting point of 800 ° C. or lower, a boron compound is preferable (in the case of a boron compound, Y2 is B (boron)). Examples of the boron compound include boric acid, lithium tetraborate, boron oxide, and ammonium borate. Particularly good is when boric acid is used.

The boron compound promotes crystal growth of lithium manganate as a sintering aid during firing. Further, the edge of the lithium manganate particle is dulled, and the effect is obtained as a rounded particle. In conventional lithium manganate, manganese is eluted from the edge portion of the particles, and it is considered that battery characteristics, particularly characteristics at high temperatures are deteriorated. In the present invention, the edge (angular portion) of the lithium manganate particle is blunted to form a rounded particle, so that the elution site of manganese can be reduced. As a result, the stability of the secondary battery can be reduced. It is thought that the property can be improved.
In addition, it is considered that the boron compound reacts with lithium in lithium carbonate to form a B-Li compound during firing. Since this B-Li compound is considered to be melted at 800 ° C. or higher, it is considered that the lithium manganate particles are coated. It is considered that the B-Li compound serves as a kind of protective film and can prevent elution of manganese with battery characteristics, particularly at high temperatures.

  In the present invention, the firing temperature must be 800 ° C. or higher. Below 800 ° C., it is impossible to obtain a state in which aluminum is uniformly distributed inside the particles. Moreover, if it is less than 800 degreeC, the sufficient aggregation effect of the particle | grains by boron cannot be acquired.

  In the above-mentioned patent document 2 (Japanese Patent Laid-Open No. 2001-146425), the homogeneity state of Al is verified by EPMA analysis of the particle appearance, but such a result is obtained even when Al is localized only on the particle surface. However, when the actual output is measured, the resistance is large and it is difficult to extract the current. Preferably, the baking is performed at a temperature range of 850 ° C to 1050 ° C.

  Next, the positive electrode using the positive electrode active material which consists of lithium manganate particle powder for nonaqueous electrolyte secondary batteries which concerns on this invention is described.

  When a positive electrode is produced using the positive electrode active material according to the present invention, a conductive agent and a binder are added and mixed according to a conventional method. As the conductive agent, acetylene black, carbon black, graphite and the like are preferable, and as the binder, polytetrafluoroethylene, polyvinylidene fluoride and the like are preferable.

  The secondary battery manufactured using the positive electrode active material according to the present invention includes the positive electrode, the negative electrode, and an electrolyte.

  As the negative electrode active material, lithium metal, lithium / aluminum alloy, lithium / tin alloy, graphite, graphite, or the like can be used.

  In addition to the combination of ethylene carbonate and diethyl carbonate, an organic solvent containing at least one of carbonates such as propylene carbonate and dimethyl carbonate and ethers such as dimethoxyethane can be used as the solvent for the electrolytic solution.

  Further, as the electrolyte, in addition to lithium hexafluorophosphate, at least one lithium salt such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in the above solvent and used.

The secondary battery manufactured using the positive electrode active material according to the present invention has an initial discharge capacity of 80 mAh / g or more, a capacity maintenance rate of 55% or more after high temperature storage, a capacity recovery rate of 95% or more, and a high temperature cycle capacity maintenance. The rate is 93% or more, and the use of a sintering aid is a dramatic improvement over the case of lithium manganate that does not use a sintering aid.
When the discharge capacity of the positive electrode using the lithium manganate particles according to the present invention is less than 80 mAh / g, the output is low and not practical. More preferably, it is 87-113 mAh / g, and when it exceeds 110 mAh / g, sufficient stability cannot be ensured.

<Action>
The important point in the present invention is that the crystallinity of the lithium manganate particles, particularly the strength ratio of I (440) / I (111), I (400) / I (111) is high, and Ni is a substitutional element. Co, Mg, Fe, Al, Cr, and Ti are uniformly dispersed, and the constituent elements of the sintering aid having a melting point of 800 ° C. or less are present on the particle surface. .

  In the present invention, manganese oxide is coated with a fine and low-crystalline coating such as an aluminum compound on the particle surface so as to be in a homogeneously mixed state, and boric acid is added at a high temperature of 800 ° C. or higher. By firing, lithium manganate having the above-mentioned characteristics was obtained.

  As a result, the secondary battery using lithium manganate according to the present invention has improved high-temperature storage characteristics as well as output characteristics.

  A typical embodiment of the present invention is as follows.

  The average particle diameter is a volume-based average particle diameter measured by a wet laser method using a laser type particle size distribution measuring apparatus Microtrac HRA [manufactured by Nikkiso Co., Ltd.].

  The average primary particle size was read from the SEM image.

  The presence state of the particles to be coated or present was observed using a scanning electron microscope SEM-EDX with an energy dispersive X-ray analyzer [manufactured by Hitachi High-Technologies Corporation].

  The average primary particle diameter of the particles to be coated or present was observed and confirmed using a scanning electron microscope SEM-EDX with an energy dispersive X-ray analyzer [manufactured by Hitachi High-Technologies Corporation].

  The X-ray diffraction of the sample was measured using RAD-IIA manufactured by Rigaku Corporation.

  The lattice constant was calculated by the Rietveld method from the powder X-ray diffraction results.

  Confirmation of whether it was a single phase was judged from the said powder X-ray-diffraction result.

  Whether or not it was a single crystal was determined by observing the orientation plane by EBSD of the cross section of the particle or from the SEM image.

The initial charge / discharge characteristics and high-temperature storage characteristics of the coin cell were evaluated using lithium manganate particles.
First, 92% by weight of Li—Mn composite oxide as a positive electrode active material, 2.5% by weight of acetylene black and 2.5% by weight of graphite as a conductive material, and polyvinylidene fluoride 3 dissolved in N-methylpyrrolidone as a binder After mixing with wt%, it was applied to an Al metal foil and dried at 120 ° C. This sheet was punched out to 16 mmφ, and then pressure-bonded at 1.5 t / cm ² to make the electrode thickness 50 μm for the positive electrode. The negative electrode was metallic lithium blanked into diameter of 16 mm, the electrolytic solution 3 EC and DEC in which LiPF ₆ was dissolved in 1 mol / l at a volume ratio of: was prepared a coin cell of a CR2032 type using a mixed solution of 7.
The initial charge / discharge characteristics are as follows: at room temperature, charging is performed at a current density of 0.1C up to 4.5V, and then discharging is performed at a current density of 0.1C up to 3.0V. Capacity (a) and initial efficiency were measured.

As the high-temperature storage characteristics, the capacity retention rate and the capacity recovery rate are measured by measuring the residual discharge capacity after charging at 0.1 C to 4.5 V and discharging to a discharge depth of 70% and then leaving at 60 ° C. for 1 week. (C) is performed to obtain a capacity retention ratio (= 100 × c / (0.3 × a)), and further, discharge capacity measurement (d) is performed when charging / discharging is performed again at 0.1 C to recover the capacity. Rate (= 100 × d / a).
Regarding the high-temperature cycle capacity maintenance rate, charging / discharging was repeated at a rate of 1 C at 60 ° C., and the ratio of the discharge capacity at the 30th cycle to the initial discharge capacity was used.

Example 1 <Production of Lithium Manganate Particle Powder>
Under nitrogen aeration, 0.5 mol of manganese sulfate was added to 3.5 mol of sodium hydroxide to make the total amount 1 L, and the obtained manganese hydroxide was aged at 90 ° C. for 1 hour. After aging, air was passed through, oxidized at 90 ° C., washed with water and dried to obtain manganese oxide particles.

The obtained manganese oxide particle powder was Mn ₃ O ₄ , the particle shape was granular, the average particle size was 4.8 μm, and the BET specific surface area was 0.6 m ² / g. When an SEM image of the produced manganese oxide particles was observed, it was confirmed that each primary particle was an octahedral single crystal surrounded by a (111) plane.

The aqueous suspension containing the manganese oxide particles was washed with 5 times the amount of water using a filter press, and then poured so that the concentration of the manganese oxide particles became 10 wt%. A 0.2 mol / l sodium aluminate aqueous solution was continuously supplied into the reaction tank so that Mn: Al = 95: 5. While the reaction vessel is constantly stirred with a stirrer, a 0.2 mol / l sulfuric acid aqueous solution is automatically supplied so that the pH becomes 8 ± 0.5, and the suspension contains manganese oxide particles coated with aluminum hydroxide. A liquid was obtained.
This suspension was washed with water 10 times the weight of the manganese oxide particles using a filter press and then dried, and the average secondary particle size of Mn: Al = 95: 5 was 4. Manganese oxide particles coated with 8 μm aluminum hydroxide were obtained.

  An X-ray diffraction pattern of manganese oxide before aluminum treatment is shown in FIG. 1, and an X-ray diffraction pattern of manganese oxide after aluminum treatment is shown in FIG. In FIG. 2, since no peak based on the Al compound is observed, it was confirmed that the film was very fine and low in crystallinity.

The obtained Mn ₃ O ₄ particle powder coated with aluminum hydroxide, lithium carbonate, and boric acid were mixed with Li: Mn: Al = 1.072: 1.828: 0.10, and boron in boric acid with respect to Mn. Then, boric acid was weighed to a ratio of 2.0 mol% and dry-mixed for 1 hour to obtain a uniform mixture. 30 g of the obtained mixture was put in an alumina crucible and kept at 960 ° C. in an air atmosphere for 3 hours to obtain lithium manganate particles. The obtained lithium manganate particle powder was obtained. In the X-ray diffraction, no peaks related to the added boron and boron compound were detected, and it was confirmed to be a lithium manganate single phase. The SEM image of the obtained lithium manganate powder is shown in FIG. As shown in FIG. 3, it can be confirmed that the particles are not rounded and rounded.

The obtained lithium manganate particle powder has a composition of Li _{1 + x} Mn _2−xy O ₄ , x is 0.072, y is 0.10, and the amount of Y2 element (boron) present is It is 1.00 mol% with respect to Mn, the average primary particle diameter is 5.0 μm, the average particle diameter (D ₅₀ ) of the secondary particles (behavior particles) is 9.5 μm, and the BET specific surface area value is 0 .38 m ² / g, I (400) / I (111) was 51%, I (440) / I (111) was 27%, and the lattice constant was 0.8204 nm.

  In addition, 5 g of lithium manganate powder and 100 ml of pure water were placed in a 200 ml beaker, boiled for 7 minutes, cooled, and then filtered with No5B filter paper to identify elements by ICP. It was. As a result, boron (Y2 element) was completely dissolved. Therefore, it was confirmed that boron of Y2 element exists only on the particle surface of the lithium manganate particle powder. Further, since Li was dissolved in proportion to the amount of boron dissolved, it is estimated that boron is compounded with Li.

  The coin-type battery produced using the positive electrode active material made of the lithium manganate particles obtained here had an initial discharge capacity of 110 mAh / g. The capacity retention ratio (RTN) and capacity recovery ratio (RCV) after storage at 60 ° C. for 1 week were 59% and 99%, respectively, and the capacity retention ratio after 30 cycles at 60 ° C. was 98%.

  The lithium manganate particles obtained in Example 1 were kneaded with a resin, the particles were cut with a cross section polisher, and the results of EPMA mapping of Mn and Al in the cross section are shown in FIG. It can be seen that Al is uniformly distributed in the cross section of the particles as in Mn.

Examples 2-6
A lithium manganate particle powder was obtained in the same manner as in Example 1 except that the addition ratio of the additive containing the Y2 element and the firing conditions were variously changed.
The production conditions at this time are shown in Table 1, and the characteristics of the obtained lithium manganate particles are shown in Table 2.

Comparative Example 1
Manganese oxide (MnO ₂ ) (average particle size 15 μm), aluminum hydroxide (Al (OH) ₃ ) and lithium carbonate were mixed and then fired at 960 ° C. to obtain lithium manganate particle powder.

Comparative Examples 2-4
Lithium manganate particles were obtained in the same manner as in Example 1 except that the type of manganese oxide to be used, the amount of aluminum coating, the amount of boron added, and the firing conditions were variously changed.
The production conditions at this time are shown in Table 1, and the characteristics of the obtained lithium manganate particles are shown in Table 2.

  About the lithium manganate particle powder obtained in Comparative Example 2, EPMA mapping of Mn and Al of the particle cross section was performed in the same manner as in Example 2. The result is shown in FIG. As shown in FIG. 5, Al was localized on the surface and was not present uniformly.

Comparative Example 5
Manganese oxide (MnO ₂ ) (average particle size 15 μm), aluminum hydroxide (Al (OH) ₃ ), boric acid and lithium carbonate were mixed and then fired at 960 ° C. to obtain lithium manganate particle powder.

About Example 2-6, it carried out similarly to Example 1, and performed the result of the solubility test.
As a result, boron (Y2 element) present in the lithium manganate particles of Examples 2 to 6 was completely dissolved. Therefore, it was confirmed that boron of Y2 element exists only on the particle surface of the lithium manganate particle powder. Further, since Li was dissolved in proportion to the amount of boron dissolved, it is estimated that boron is compounded with Li.

The lithium manganate particle powder according to the present invention is a secondary material in which different metals such as Al, Co or Mg are uniformly present inside the particle, and since the crystallinity is high, the output characteristics are high and the high temperature storage characteristics are excellent. It is suitable as a positive electrode active material for batteries.

X-ray diffraction pattern of manganese oxide before Al treatment in Example 1 X-ray diffraction pattern of manganese oxide after Al treatment in Example 1 SEM image of lithium manganate powder obtained in Example 1 The lithium manganate particles obtained in Example 1 were kneaded into a resin, the particles were cut with a cross section polisher, and EPMA mapping of Mn and Al in the cross section. The lithium manganate particles obtained in Comparative Example 2 were kneaded into a resin, the particles were cut with a cross section polisher, and EPA mapping of Mn and Al in the cross section.

Claims (12)

Lithium manganate particles having a primary particle diameter of 1 μm to 10 μm and substantially forming single phase particles,
_{Formula: Li 1 + x Mn 2-} x-y Y1 y O 4 + Y2 (Y1 = Al, Y2 = elemental melting point that make up the sintering aid is at 800 ° C. or less B, 0.03 ≦ x ≦ 0.15, 0.05 ≦ y ≦ 0.20, Y2: 0.1 mol% to 2.5 mol% with respect to Mn), and the Y1 element is dispersed inside the particle, and the X-ray diffraction intensity I (400 ) / I (111) is 38% or more, and I (440) / I (111) is 18% or more. 2. The lithium manganate particles according to claim 1, wherein the lattice constant is 0.818 to 0.821 nm. 3. The lithium manganate particle powder according to claim 1, wherein the specific surface area is 0.3 to 1.25 m ² / g (BET method). 4. The lithium manganate particle powder according to claim 1, which has an average particle diameter (D50) of 1.0 to 15 μm. After mixing lithium carbonate, manganese oxide coated with a compound of at least one element selected from Ni, Co, Mg, Fe, Al, Cr, and Ti, and a sintering aid having a melting point of 800 ° C. or less The method for producing a lithium manganate particle powder according to any one of claims 1 to 4, wherein the mixture is fired at 800 ° C to 1050 ° C. Manganese oxide coated with a compound of at least one element selected from Ni, Co, Mg, Fe, Al, Cr, and Ti, Ni, Co, Mg, Fe with respect to an aqueous suspension containing manganese oxide. An aqueous solution containing a salt of at least one element selected from Al, Cr, Ti is added to adjust the pH of the suspension, and Ni, Co, Mg, Fe, Al, Cr are formed on the surface of the manganese oxide particles. The method for producing a lithium manganate particle powder according to claim 5, which is obtained by forming a coating of a compound of at least one element selected from Ti. The manganic acid according to claim 6, wherein the compound of at least one element selected from Ni, Co, Mg, Fe, Al, Cr and Ti formed on the surface of the manganese oxide particles is amorphous by X-ray diffraction. Method for producing lithium particle powder. The method for producing lithium manganate particle powder according to any one of claims 5 to 7, wherein the manganese oxide is substantially single crystal and has an average particle diameter of 1 µm or more. A non-aqueous electrolyte secondary battery using the lithium manganate particle powder according to claim 1 as a positive electrode active material or a part thereof. Using a lithium manganate particle powder as a positive electrode active material, a non-aqueous electrolyte solution (mixed at a ratio of EC: DEC = 3: 7) to which 1 mol / l LiPF ₆ is added is used, and the negative electrode has a thickness of 150 μm. The CR2032-type nonaqueous electrolyte secondary battery using Li foil has an initial discharge capacity of 80 mAh / g or more and 110 mAh / g or less when charge / discharge capacity is measured. The lithium manganate particle powder according to claim 1. Using a lithium manganate particle powder as a positive electrode active material, a non-aqueous electrolyte solution (mixed at a ratio of EC: DEC = 3: 7) to which 1 mol / l LiPF ₆ is added is used, and the negative electrode has a thickness of 150 μm. In a CR2032-type non-aqueous electrolyte secondary battery using Li foil, when a 30-cycle charge / discharge test was performed at a rate of 1 hour in a constant temperature bath at 60 ° C., the discharge capacities of the first and 30th cycles were The lithium manganate particle powder according to any one of claims 1 to 4, wherein the ratio is 93% or more. Using a lithium manganate particle powder as a positive electrode active material, a non-aqueous electrolyte solution (mixed at a ratio of EC: DEC = 3: 7) to which 1 mol / l LiPF ₆ is added is used, and the negative electrode has a thickness of 150 μm. In a CR2032-type nonaqueous electrolyte secondary battery using Li foil, after initial charge capacity measurement (a) when charging / discharging at a voltage of 3.0-4.5 V at a time rate of 0.1 C, 0. After charging to 4.5 V at a time rate of 1 C and discharging to a discharge depth of 70%, after leaving at 60 ° C. for 1 week, and further charging and discharging at 0.1 C, discharge capacity measurement (d) The lithium manganate particle powder according to any one of claims 1 to 4, wherein the capacity recovery rate when the capacity recovery rate (= 100 x d / a) is 95% or more.