JP3468099B2 - Method for producing positive electrode active material for lithium secondary battery - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a positive electrode active material in a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, portable electronic devices for consumer use,
The cordless technology is rapidly advancing, and there is an increasing demand for a small-sized, lightweight secondary battery having a high energy density, which serves as a power source for driving these. From this point of view, non-aqueous secondary batteries, especially lithium secondary batteries, have great expectations as batteries having high voltage and high energy density, and their development is urgently needed.

In recent years, a battery system in which a lithium-containing composite oxide is used as a positive electrode active material and a carbonaceous material is used as a negative electrode has been attracting attention as a lithium secondary battery capable of obtaining high energy density. As this lithium-containing composite oxide, LiCoO ₂
A battery that uses a
Many attempts have been made to put iNiO ₂ into practical use. However, LiCoO ₂ is scarce in resources and expensive,
Further, LiNiO ₂ has a problem of low thermal stability.

On the other hand, as a lithium-containing composite oxide using manganese, which is rich in resources, LiMn ₂ O _{4 is used.}
Is proposed. This oxide has a two-stage discharge potential near 4V and around 2.8V. By using a plateau discharge region near 4V and repeating charge and discharge in the voltage range of 4.5 to 3.0V. High potential and high energy density can be achieved. As a main manufacturing method of this lithium composite manganese oxide, a method of mixing a manganese compound and a lithium compound in a predetermined molar ratio and then heat treating them to synthesize them is generally used.

However, when the lithium composite manganese oxide thus obtained is used as a positive electrode material for a lithium secondary battery, the obtained discharge capacity is small.

As a method for solving this problem, various methods for producing lithium manganate have been proposed. A method in which a mixture of lithium hydroxide and manganese oxide is pulverized and then fired to allow the reaction of both to uniformly proceed in a short time (JP-A-6-76824), 50
After performing the first heat treatment at a temperature of 0 ° C. or less, 50
A method of obtaining a spinel structure having a more uniform composition by performing a second heat treatment at a temperature of 0 ° C. or higher and 850 ° C. or lower (Japanese Patent Laid-Open No. 8-217452). After performing heat treatment at 200 ° C. or higher and lower than 500 ° C., 500 A method of obtaining a high-capacity lithium manganese oxide by carrying out a heat treatment again at not less than 850 ° C and not more than 850 ° C (JP-A-9-86933), and treating the manganese oxide in a lithium salt solution to uniformly disperse lithium ions. And then heat treatment to obtain LiMn ₂ O ₄ having a uniform composition and good crystallinity (JP-A-6-
295724), a lithium is rapidly and uniformly diffused by adding a reducing agent when a lithium-containing treatment is carried out in manganese oxide particles, and then a heat treatment is performed to obtain uniform and good crystallinity of manganese. A method of obtaining lithium oxide (Japanese Patent Laid-Open No. 8-213019), a fatty acid is added to a salt of a metal element to prepare an aqueous solution having a pH of less than 7, and the solution is spray-pyrolyzed and then heat-treated to obtain a good quality active material. Method (Japanese Patent Laid-Open No. 8-329945)
and so on.

On the other hand, there is a method of substituting a part of manganese with another element in order to improve the charge / discharge cycle. For example, a method of substituting B for a part of manganese (Japanese Patent Laid-Open No. 4-2
37970), a method of substituting with Al (Japanese Patent Application Laid-Open No. Hei 4-
89662), a method of substituting with P (Japanese Patent Application Laid-Open No. 9-2
There is a method of substituting Co, Ni, B and Al (Japanese Patent Laid-Open No. 10-92429).

[0008]

However, LiMn ₂ O ₄ which is a lithium composite manganese oxide is theoretically characterized by high voltage and high energy density.
LiMn ₂ O ₄ obtained by the above conventional synthesis method cannot obtain a sufficient utilization ratio of the active material, and it is difficult to efficiently manufacture a positive electrode active material having a large discharge capacity. Also,
LiMn ₂ O ₄ obtained by substituting a part of manganese obtained by the above-mentioned conventional method with another element does not sufficiently suppress the capacity decrease due to charge / discharge cycles and the capacity decrease due to elution of manganese at high temperature. There is also a problem.
The present invention solves such a problem, and an object thereof is to provide a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which has a high utilization rate of the active material and has excellent charge / discharge characteristics.

[0009]

In order to solve the above-mentioned problems, the present invention provides a mixture of a manganese compound and a lithium compound,
Alternatively, the synthesis is carried out while flowing to allow the synthesis reaction to proceed uniformly and completely, thereby obtaining a lithium composite manganese oxide having a high utilization rate of the active material and exhibiting excellent charge / discharge characteristics. Furthermore, part of manganese is C
By using the above-mentioned synthesis method, a lithium composite manganese oxide substituted with at least one kind selected from the group consisting of o, Ni, Cr, B, Al or P is used to improve charge / discharge cycle characteristics and elute manganese at high temperature. It is intended to suppress the decrease in capacity due to.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which comprises synthesizing a manganese compound and a lithium compound by heating them while mixing or flowing them.
The maximum temperature for raising the temperature is preferably 750 to 950 ° C.

Further, according to the present invention, the manganese compound and the lithium compound are mixed or flowed to raise the temperature while synthesizing the mixture in the first synthesis step. Is a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which has the synthesis step of. The maximum temperature of the first synthesis stage is preferably 500 to 700 ° C, and the maximum temperature of the second synthesis stage is preferably 750 to 950 ° C.

Further, a part of manganese of the positive electrode active material for a non-aqueous electrolyte secondary battery is converted into Co, Ni,
It is substituted with at least one kind selected from the group consisting of Cr, B, Al or P, and the total content of atomic moles thereof is 0.01 to 5% with respect to the atomic moles of manganese.

As a method of synthesizing the lithium composite manganese oxide, a method of mixing a predetermined amount of a starting material manganese compound or a lithium compound in a stoichiometric ratio and firing at high temperature is a well-known synthesis method. However, since these mixtures are usually synthesized in a static state in a furnace, even if the atmosphere in the furnace is variously adjusted such as an oxidizing or reducing atmosphere, the interface where the solid phase contacts the gas phase is almost the same as the mixture and the gas phase. Focus on the contact area. For this reason, the vicinity of the center of the mixture, which is difficult to contact with the gas phase, is not easily affected by the adjustment atmosphere, and the contact between particles of the manganese compound or the lithium compound drags the first contact state to the end of the reaction, so that the homogeneous reaction field In many cases, unreacted substances are mixed in the final product, or the sample is obtained as a sample having a composition deviating from the desired composition.

According to the present invention, since a mixture of a manganese compound and a lithium compound is heated while synthesizing while mixing or flowing, the powder itself causes a change in reaction environment due to contact between particles or a reaction atmosphere. That is, the frequency of interfacial contact between the solid phase and the gas phase is remarkably increased,
It is possible to provide a uniform reaction field with little bias. Therefore, it is easily affected by the adjusted atmosphere, and the powders of the manganese source and the lithium source contact each other more frequently than in the stationary method, and a uniform reaction field is easily formed. For this reason, it becomes possible to obtain a sample having a desired composition which is unlikely to have unreacted substances mixed therein and a nonstoichiometric composition part as the final product.

In this case, the maximum temperature rise during synthesis is 7
When the temperature is 50 ° C. or lower, the crystallinity is low and the discharge capacity is small, and when the temperature is 950 ° C. or higher, the specific surface area is small and the battery performance is poor, so that the battery performance is good.
0-950 degreeC is preferable.

For example, synthesis is carried out while flowing a mixture of manganese dioxide as a starting material and manganese dioxide as a lithium compound and lithium carbonate as a lithium compound at a predetermined ratio. It is known that manganese dioxide, as well as the adsorbed water and bound water, have protons inserted therein, so that the valence of manganese is not tetravalent but exists in a slightly reduced state. The present inventors examined the change in the chemical state of the starting material during the temperature rising synthesis process. First, manganese dioxide begins to rise in temperature from room temperature and the attached water is released by 130 ° C., and then the protons as bound water are released in the oxidizing atmosphere in the furnace up to about 250 ° C. At this point, the oxidation state of manganese is Transition to oxidation. At this time, the valence as manganese dioxide is oxidized to almost tetravalent, and then the lithium insertion reaction of manganese dioxide starts and the reaction proceeds gradually due to the promotion of the decomposition reaction of lithium carbonate. Almost changed to cubic. In order to change the valence of manganese to tetravalent, it is necessary that each manganese dioxide particle interface comes into contact with a uniformly adjusted oxidizing atmosphere, and the frequency should be uniform.

After this, the fully lithiated lithium composite manganese oxide precursor is allowed to stand in an electric furnace to stand at 750 to 750.
It is reheated at 950 ° C. to finally obtain the target lithium composite manganese oxide. When it is reheated in the latter half, it is not necessary to fluidize it because lithium is impregnated into the precursor in a sufficiently uniform manner. Also, heating at 750 to 950 ° C. causes the crystal of the lithium composite manganese oxide to grow, so that it is kept in an electric furnace. It is preferable to perform it by leaving it to stand.

In the case where the first half of the step of synthesizing while flowing is performed in the electric furnace for the above-mentioned method of the present invention,
There is no change in the way that manganese dioxide receives heat, so there should be essentially no significant difference in physical changes. However, actually, the manganese dioxide particles exposed to the atmosphere in the furnace are limited, and since the manganese dioxide particles existing in the middle of the mixture do not enter the atmosphere gas,
All of the manganese dioxide used for the calcination is not uniformly oxidized to tetravalent, and many particles are partially oxidized, but the oxidation does not proceed sufficiently. For this reason, in the lithiation reaction that proceeds at a higher temperature, variations in reactivity occur due to different oxidation states of the groups, resulting in a final product with a different composition ratio or insufficient lithiation. is there.

Further, a part of manganese is used as Co, Ni, C.
Even in the method of substituting at least one of the group consisting of elements such as r, B, Al, and P, various compounds can be added to the lithium composite manganese oxide precursor by synthesizing a compound containing these elements while flowing. It is possible to uniformly replace the element. These substituting elements have the effect of alleviating the crystal phase change associated with charge and discharge of the lithium composite manganese oxide positive electrode, and contribute to the improvement of cycle characteristics. At the same time, it is considered that there is an effect on the specific surface area of the lithium composite manganese oxide, or an effect of increasing the bonding force of the cubic crystal skeleton, which leads to improvement of battery characteristics.

By using the method of synthesizing these substituting elements while flowing, a more uniform solid solution can be obtained, and the substituting effect of these elements can be maximized.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) A method for synthesizing the lithium composite manganese oxide of this example will be described.

Electrolytic manganese dioxide (MnO ₂ ) and lithium carbonate (Li ₂ CO ₃ ) have an atomic molar ratio of Mn to Li of 1:
2309 g of MnO ₂ and Li ₂ CO ₃ so as to be 0.5
Was mixed with 491 g. This mixture is rotated at a rotation speed of 2 rpm in a rotary rotary kiln of 20 L, and while being flown, the temperature is raised to a temperature A of 650 to 1000 ° C. shown in Table 1 for 2 hours in an air atmosphere of 10 l / min of blowing air, and the temperature is raised. the LiMn ₂ O ₄ compounds 1-5 were synthesized by holding for 10 hours the temperature a after. The obtained compound was pulverized and classified to obtain a battery active material. Moreover, the obtained compounds 1 to 5
X-ray diffraction measurement was performed, and the peak intensity of the (111) plane was 100 when synthesized by the conventional method shown in Comparative Example 1.
Was confirmed as a comparative value. The X-ray diffraction conditions at this time were CuKα, 40 kV, and 40 mA. The peak intensity of the (111) plane indicates the crystallinity of LiMn ₂ O ₄ .

Next, a cylindrical lithium secondary battery was constructed by using the obtained compounds 1 to 5 as a positive electrode active material. FIG. 1 is a vertical sectional view of a cylindrical lithium secondary battery used in an example of the present invention. In FIG. 1, a positive electrode plate 5 and a negative electrode plate 6 are spirally wound a plurality of times with a separator 7 in between, and an electrode plate group 4 is housed in a battery case 1 formed by processing an organic electrolytic solution resistant stainless steel plate. There is. A positive electrode aluminum lead 5a is drawn out from the positive electrode plate 5 and connected to the sealing plate 2, and a negative electrode nickel lead 6a is drawn out from the negative electrode plate 6 and connected to the bottom of the battery case 1. Insulating rings 8 are provided on the upper and lower portions of the electrode plate group 4, respectively, and the opening of the battery case 1 is sealed by a sealing plate 2 provided with a safety valve and an insulating packing 3. For the negative electrode plate 6, a carbon material (pitch-based spherical graphite was used in the present embodiment) was mixed with an aqueous dispersion of styrene-butadiene rubber in a weight ratio of 100: 3.5, and this was mixed with an aqueous solution of carboxymethyl cellulose. The obtained product was suspended in a paste form and applied to both sides of a copper foil, dried, and then rolled and cut into a predetermined size to prepare a negative electrode plate. The mixing ratio of the aqueous dispersion of styrene-butadiene rubber is calculated based on its solid content. The positive electrode plate 5 is the synthesized compound 1
˜5 LiMn ₂ O ₄ with an aqueous dispersion of acetylene black and polytetrafluoroethylene in a weight ratio of 10
Mix at a ratio of 0: 2.5: 7.5 and suspend this in an aqueous solution of carboxymethyl cellulose to form a paste. Next, this paste was applied on both sides of an aluminum foil, dried, rolled and cut into a predetermined size to prepare a positive electrode plate. The mixing ratio of the aqueous dispersion of polytetrafluoroethylene is calculated based on its solid content.

Leads were attached to the positive and negative electrode plates produced by the above method, respectively, and they were spirally wound with a polyethylene separator interposed therebetween and housed in a battery case. The electrolytic solution used was a solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 3, and lithium hexafluorophosphate (LiPF ₆ ) was dissolved therein at 1.5 mol / l. This electrolytic solution was injected into the above battery case under reduced pressure and then sealed to obtain batteries 1 to 5. In this example, in order to evaluate the characteristics of the positive electrode active material, a negative electrode having a large capacity was used in advance.

Tests were carried out using the batteries 1 to 5 under the following conditions. First, at 20 ° C, the battery voltage up to 4.2V 12
The battery is charged with a constant current of 0 mA, rested for 1 hour, and then discharged with a constant current of 120 mA to a battery voltage of 3.0 V.
By repeating this method, charging and discharging were repeated three times, and the discharge capacity at the third time was used as the initial capacity. In addition, the initial capacity is L included in the battery.
The specific capacity of the active material was calculated by dividing by the weight of iMn ₂ O ₄ .

Comparative Example 1 As a comparative example, a lithium composite manganese oxide was prepared by allowing it to stand in an electric furnace. Hereinafter, a method for synthesizing the positive electrode active material will be described.

Electrolytic manganese dioxide (MnO ₂ ) and lithium carbonate (Li ₂ CO ₃ ) have an atomic molar ratio of Mn to Li of 1:
MnO ₂ and Li ₂ CO ₃ were mixed in the same amount as in Example 1 so that the ratio became 0.5. This mixture was placed in a container, allowed to stand in an electric furnace, heated to 850 ° C. in 2 hours, and then heated to 850 ° C.
LiMn ₂ O ₄ was synthesized by holding at 10 ° C. for 10 hours. The obtained compound was pulverized and classified to obtain a battery active material. The obtained compound was subjected to X-ray diffraction measurement in the same manner as in Example 1.

Comparative battery 1 was prepared and tested in the same manner as in Example 1 except that the obtained LiMn ₂ O ₄ was used as the positive electrode active material.

Table 1 shows the maximum temperature A of the batteries 1 to 5 and the comparative battery 1 at the time of temperature rise, the initial capacity, the specific capacity of the active material, and the peak intensity of the (111) plane of the positive electrode active material.

[0031]

[Table 1]

From Table 1, comparing battery 3 and comparative battery 1, battery 3 has a better active material specific capacity than comparative battery 1 even though the maximum temperature during heating is the same as 850 ° C. The value obtained was It is considered that this is because the synthesis reaction proceeds more completely and uniformly by mixing and flowing during synthesis. This is determined by X-ray diffraction measurement (1
This is also supported by the fact that the peak intensity of the 11) plane of the battery 3 is larger than that of the comparative battery 1. The synthesis temperature is 75
The optimum range is 0 ° C. to 950 ° C., and among them, the active material specific capacity was highest when the temperature A was 850 ° C.

Example 2 A method of synthesizing the lithium composite manganese oxide of this example will be described.

Electrolytic manganese dioxide (MnO ₂ ) and lithium carbonate (Li ₂ CO ₃ ) are mixed at an atomic molar ratio of Li and Mn of 1:
The same amount as in Example 1 was mixed so as to be 0.5. This mixture was rotated in a 20 L rotary rotary kiln at a rotation speed of 2 r
While rotating at pm and flowing, the temperature was raised to a temperature B of 400 to 800 ° C. shown in Table 2 for 2 hours in an air atmosphere of blowing air of 10 l / min, and the temperature B was kept for 10 hours. Then, it is placed in a container and allowed to stand in an electric furnace, and the temperature is raised from a temperature B to a temperature C of 650 to 1000 ° C. shown in Table 2 in 2 hours,
By holding the temperature C for 10 hours, LiMn ₂ O ₄ of compounds 6 to 14 was synthesized. The obtained compound was pulverized and classified to obtain a battery active material. The X-ray diffraction measurement of the compound, the battery constitution and the test method were the same as in Example 1. In this example, in order to evaluate the characteristics of the positive electrode active material, a negative electrode having a large capacity was used in advance.

Table 2 shows the maximum temperature B when the batteries 6 to 14 are heated.
And C, the initial capacity, the specific capacity of the active material, and the peak intensity of the (111) plane of the positive electrode active material are shown.

[0036]

[Table 2]

From Table 2, the temperature B is in the range of 500 to 700 ° C., and the temperature C is higher than the temperature B, 750 to 950.
It was found that the active material specific capacity was good in the range of ° C. Further, comparing the battery 3 obtained in Example 1 with the batteries 7 to 9 of Example 2, the maximum temperature is the same as 850 ° C., but the maximum temperature is 500 to 500 ° C. while flowing in the first synthesis stage.
It was also found that a larger active material specific capacity can be obtained by synthesizing at 700 ° C. and then allowing it to stand still at a higher maximum temperature of 850 ° C. in the second synthesis step. This is 500-7
It is considered that by synthesizing while mixing and flowing at 00 ° C., the synthesis reaction proceeded completely and uniformly, and the crystals were further grown by standing and heat-treating. This is supported by the fact that the peak intensities of the (111) plane measured by X-ray diffraction are large in Examples 7 to 9.

Example 3 A positive electrode active material was synthesized in which a part of manganese of LiMn ₂ O ₄ was replaced with Co, Ni, Cr, B, Al and P. In this embodiment, Co is cobalt trioxide (Co ₃ O ₄ ), Ni is nickel hydroxide (N
i (OH) ₂ ) and Cr are chromium trioxide (Cr ₂ O ₃ ),
B is boron trioxide (B ₂ O ₃ ), Al is aluminum hydroxide (Al (OH) ₃ ) and P is diphosphorus pentoxide (P ₂ O).
₅ ) was used as the dopant species.

The method for synthesizing the positive electrode active material will be described below. Electrolytic manganese dioxide (MnO ₂ ), lithium carbonate (Li ₂ CO ₃ ), and cobalt trioxide (Co ₃ O ₄ ) are mixed with Li.
And were mixed so that the total atomic mole ratio of Mn and Co was 0.5: 1. The atomic mole ratio of Co to Mn at this time was 0.001 to 20%. When Ni, Cr, B, Al and P were added instead of Co, the above dopant species were mixed with manganese in the same predetermined ratio as Co. This mixture was rotated at a rotation speed of 2 rpm in a rotary rotary kiln of 20 L, and was flowed for 6 hours in an air atmosphere of 10 l / min of blowing air for 6 hours.
The temperature was raised to 00 ° C., and after the temperature was raised, the temperature was maintained at 600 ° C. for 10 hours. After that, put it in a container and leave it in the electric furnace for 85 hours in 2 hours.
By raising the temperature to 0 ° C. and then holding the temperature at 850 ° C. for 10 hours, a part of manganese is changed to Co, Ni, Cr, B, Al
Alternatively, LiMn ₂ O ₄ substituted with P was synthesized. The obtained compound was pulverized and classified to obtain a battery active material. The battery configuration and the measurement of the initial capacity were the same as in Example 1.

Further, the charging / discharging current is 120 mA at 20 ° C.
Then, a constant current charge / discharge cycle test was performed under the conditions of a charge end voltage of 4.2V and a discharge end voltage of 3.0V. The discharge capacity at the time of 300 cycles with respect to the initial capacity was represented by% and calculated as the capacity retention rate.

The battery after the initial capacity was measured was 4.
It was charged to 2V and stored at 80 ° C for 3 days. After that, the battery was disassembled, and the amount of manganese eluted into the electrolytic solution was measured by the IPC emission spectroscopic analysis method. As the elution amount of manganese increases, the charging / discharging is hindered, so the smaller the elution amount, the better.

Comparative Example 2 As a comparative example, a part of manganese of LiMn ₂ O ₄ was used as Co, Ni, Cr, B, Al and P.
The positive electrode active material replaced with was left standing in an electric furnace. The synthesis method was the same as in Example 3 except that the first synthesis step was changed to a flow using a rotary rotary kiln while flowing, and the mixture was placed in a container and allowed to stand in an electric furnace. The battery configuration and evaluation method were also the same as in Example 3.

Co, Ni, C of Example 3 and Comparative Example 2
FIG. 2 shows the active material specific capacities with respect to the atomic mole ratios of r, B, Al, and P with respect to Mn, FIG. 3 shows the capacity retention rate, and FIG. 4 shows the manganese elution amount.

From FIG. 3, the capacity retention rate of the battery according to the present invention is high when the content of Co, Ni, Cr, B, Al and P is 0.01% or more in atomic mole ratio with respect to manganese. It is good. Further, as shown in FIG. 4, the amount of manganese eluted from the battery according to the present invention is small, and the content of Co, Ni, Cr, B, Al and P is as small as 0.01% or more by atomic mole ratio with respect to manganese. However, as shown in FIG. 2, the specific capacity of the active material decreases in the range of 5% or more. From the above, when the content of Co, Ni, Cr, B, Al and P is in the range of 0.01% to 5% in terms of atomic mole ratio with respect to manganese, the active material specific capacity, capacity retention rate and manganese elution amount are all Was found to be good.

Comparing the results of Example 3 and Comparative Example 2, Example 3 showed better results regardless of the element and the substitution rate in any of the active material specific capacity, capacity retention rate and manganese elution amount. Is shown.

This is because the synthesis reaction proceeds more completely and uniformly by mixing and flowing during the synthesis, so that the element substitution is performed more uniformly, and the effect of element substitution is more prominent. Conceivable.

In this example, a combination of electrolytic manganese dioxide and lithium carbonate was used as the starting material for LiMn ₂ O ₄ , but other manganese compounds such as manganese carbonate, lower oxide and nitrate, and water. Similar effects can be obtained by using other lithium compounds such as lithium oxide, lithium nitrate and lithium oxide in combination.

In addition to the substances listed in the examples as starting materials for elements substituting for manganese, cobalt hydroxide (C
o (OH) ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), cobalt carbonate (CoCO ₃ ), chromium trioxide (CrO ₃ ),
Nickel oxide (NiO), nickel carbonate (NiC
O _3), nickel nitrate _{(Ni (NO 3) 2)} , aluminum nitrate _{(Al (NO 3) 3)} , boric acid (H ₃ BO _3), also by using a phosphoric acid (H ₃ PO ₄₎ similar The effect is obtained.

The same effect can be seen in batteries using various carbonaceous materials capable of inserting and extracting lithium, lithium alloys, and inorganic intercalable negative electrodes as the negative electrode. Further, as an electrolyte, an electrolyte solution in which a lithium salt is dissolved in a solvent of a combination other than that in which lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate used in this example, a battery using a polymer electrolyte is used. The effect is seen also in.

[0050]

As described above, according to the present invention, LiMn
_By synthesizing the lithium composite manganate compound represented by ₂ O ₄ by mixing or flowing a manganese compound and a lithium compound, the synthesis reaction can be progressed completely and uniformly, and the charge and discharge characteristics can be improved. An excellent positive electrode active material for lithium secondary batteries can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a cylindrical lithium secondary battery of the present invention.

FIG. 2 is a diagram showing an active material specific capacity with respect to an atomic mole ratio of a substituted metal to manganese.

FIG. 3 is a diagram showing the capacity retention ratio at the time of 300 cycles with respect to the atomic mole ratio of the substituted metal to manganese.

FIG. 4 is a diagram showing the elution amount of manganese into the electrolytic solution with respect to the atomic mole ratio of the substituted metal to manganese.

[Explanation of symbols]

1 battery case 2 Seal plate 3 insulating packing 4 electrode group 5 Positive plate 5a Positive lead 6 Negative plate 6a Negative electrode lead 7 separator 8 insulating ring

Front page continuation (72) Inventor Masatoshi Nagayama 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yoshiaki Nitta 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 56) References JP-A-9-86933 (JP, A) JP-A-7-101727 (JP, A) JP-A-8-217452 (JP, A) JP-A-11-71115 (JP, A) Flat 10-182158 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 4/00-4/58 C01G 45/00

Claims (2)

(57) [Claims] 1. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which comprises a lithium composite manganese oxide having a composition represented by the general formula LiMn ₂ O ₄ , wherein a manganese compound and a lithium compound are mixed or mixed. first and synthetic steps Ru which Nessu pressurized fluidization while <br/>, and a second synthesis step that Nessu pressurized to stand, the maximum temperature of the first synthesis stage is 500 to 700
℃, the maximum temperature of the second synthesis step is 750 to 950
A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which is at 0 ° C. 2. A part of manganese of the lithium composite manganese oxide represented by the general formula LiMn ₂ O ₄ is Co, Ni, C.
At least one of the group consisting of r, B, Al or P
The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the total content of Co, Ni, Cr, B, Al or P is 0.01 to 5 atomic mol% with respect to manganese. Method of manufacturing active material.