JP2012033387A - MANUFACTURING METHOD OF POSITIVE ELECTRODE MATERIAL FOR SECONDARY BATTERY CONTAINING Cu, MANUFACTURING METHOD OF POSITIVE ELECTRODE MATERIAL FOR SECONDARY BATTERY, AND POSITIVE ELECTRODE MATERIAL FOR SECONDARY BATTERY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive positive electrode material for a secondary battery which has large charging or discharging electric capacity.SOLUTION: A manufacturing method of a positive electrode material for a secondary battery of this invention includes: a coprecipitation process for agitating a mixed solution of a strong alkaline aqueous solution added to a solution containing copper and manganese and obtaining a coprecipitate of hydroxide containing copper and manganese; a mixing process for obtaining a mixture by mixing the coprecipitate with LiOH-HO powder; a provisional burning process for obtaining a provisionally burned matter by provisionally burning the mixture; a molding process for obtaining a molded matter by molding after shattering the provisionally burned matter; and a proper burning process for obtaining LiCuMnOby properly burning the molded matter in an oxygen air current.

Description

  The present invention relates to a method for producing a positive electrode material for a secondary battery containing Cu, a method for producing a positive electrode material for a secondary battery, and a positive electrode material for a secondary battery.

A lithium secondary battery, which is an electricity storage device, has a high energy density and is expected not only as a portable device but also as an electricity storage system for next-generation automobiles. To achieve this, an energy density of 500 Wh / kg is required for the secondary battery. The lithium secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution, and has a structure in which charging and discharging reactions proceed. For example, the battery reaction formula when LiCoO ₂ is used for the positive electrode and C (graphite) is used for the negative electrode is as follows.

The positive _{electrode: LiCoO 2 ⇔ Li 1-x} CoO 2 + xLi + + xe -
Negative electrode: C + xLi ⁺ + xe ^- ⇔ CLi _x
Since this reaction is reversible, the reaction system functions as a secondary battery. The positive electrode material containing Co is disclosed in Patent Documents 1 and 2, for example. These references disclose Co-containing lithium ferrite composite oxides as positive electrode materials.

  The energy density of the battery is determined by the product of the operating voltage and the charge or discharge electric capacity. The operating voltage appears as a Fermi energy difference between the two electrodes, and the charge and discharge capacitances are proportional to the amount of lithium ions desorbed and inserted from the crystal structure. Therefore, to improve the energy density, it has a high battery voltage (that is, low Fermi energy relative to the negative electrode), and the charge and discharge capacity per unit weight increased (a lot of lithium ions are inserted and desorbed from the structure). There is a need for positive electrode materials that are possible.

JP 2004-131313 A (published April 30, 2004) JP 2006-36620 A (published February 9, 2006)

  However, conventional positive electrode materials have problems in terms of increase in charge and discharge electric capacity and cost.

That is, to increase the charge and discharge capacitance, search for new electrode materials that can be expected to have a large charge and discharge capacitance, or to desorb more lithium than the Li equivalent that normally operates from known electrode materials. If it is possible, the charging and discharging electric capacity can be increased. However, conventionally used LiCoO ₂ can usually be desorbed only up to 0.5 mol of Li in order to maintain cycle characteristics. Therefore, it is necessary to further desorb Li in order to increase the charge and discharge electric capacity of the positive electrode material. However, if it is attempted to desorb more than 0.5 mol of Li, the electrolyte is electrolyzed by a high voltage, so that the initial characteristics of the battery have not yet been achieved.

  Furthermore, although the positive electrode materials described in Patent Documents 1 and 2 are intended for low cost, they still contain expensive Co and have a problem of high cost.

  The present invention has been made in view of the above-described conventional problems, and a main object of the present invention is to provide a positive electrode material for a secondary battery having a large charge and discharge capacitance and a low cost.

In order to solve the above problems, a method for producing a positive electrode material for a secondary battery according to the present invention comprises stirring a mixed solution obtained by adding a strong alkaline aqueous solution to a solution of a copper raw material and a manganese raw material, and a hydroxide containing copper and manganese. A coprecipitation step for obtaining a coprecipitate, a mixing step for obtaining a mixture by mixing LiOH · H ₂ O powder with the coprecipitate, a calcining step for obtaining a calcined product by calcining the mixture, and A molding process in which the calcined product is pulverized and then molded to obtain a molded product, and the molded product is calcined in an oxygen stream and Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (X is not less than 0.01 and not more than 1/2).

  According to said invention, in order to obtain the coprecipitate containing copper and manganese in a coprecipitation process, it is possible to disperse | distribute copper and manganese uniformly in a coprecipitate. In the manufacturing method according to the present invention, the firing process is performed in an oxygen stream. Thereby, copper in a copper raw material can be oxidized and compounded with a positive electrode material. The secondary battery manufactured using the positive electrode material for the secondary battery thus obtained has excellent charge and discharge characteristics, and further, does not contain expensive Co and can be provided at low cost. Is possible.

  Moreover, in the manufacturing method of the positive electrode material for secondary batteries of this invention, it is preferable that the molar ratio of the manganese raw material with respect to the said copper raw material is 1-5.

  When the molar ratio of the manganese raw material to the copper raw material is the above molar ratio, the peak of CuO 3 in the positive electrode material of the present invention is detected more prominently. As a result, the structure peculiar to the positive electrode material of the present invention becomes more prominent, and a secondary battery using the positive electrode material exhibits a larger charge or discharge capacity.

  Moreover, in the manufacturing method of the positive electrode material for secondary batteries of this invention, it is preferable to stir the said mixed solution for 24 hours or more in a coprecipitation process.

  Thereby, the grain growth of the produced | generated deposit is accelerated | stimulated, the uniformity of a particle size can be given to a deposit, and a suitable coprecipitate can be obtained.

In the method for producing a positive electrode material for a secondary battery of the present invention, it is preferable that the copper raw material is CuSO ₄ .5H ₂ O and the manganese raw material is (CH ₃ COO) ₂ Mn · 4H ₂ O.

  When each raw material is the above compound, handling at the time of weighing becomes easy.

In the method for producing a secondary battery of the present invention, a mixed solution obtained by adding a strong alkaline aqueous solution to a solution in which a copper raw material and a manganese raw material are dissolved is stirred to obtain a coprecipitate of copper hydroxide and manganese hydroxide. A precipitating step, a mixing step in which LiOH · H ₂ O powder is mixed with the coprecipitate to obtain a mixture, a calcining step in which the mixture is calcined to obtain a calcined product, and the calcined product is pulverized and molded. A molding step for obtaining a molded product, and then subjecting the molded product to firing in an oxygen stream to produce Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (x is 0.01 or more, 1 And an assembling process for obtaining a secondary battery using at least the above Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ as a positive electrode material. It is preferable to include.

  Thereby, the secondary battery containing the positive electrode material which concerns on this invention can be manufactured. The secondary battery is excellent in charge and discharge characteristics, and does not contain expensive Co, and can be provided at a low cost.

The positive electrode material for a secondary battery according to the present invention is a positive electrode material for a secondary battery obtained by the above-described method for producing a positive electrode material for a secondary battery, and the peak of Li ₂ MnO ₃ is obtained by an X-ray diffraction method. A CuO peak is observed.

The positive electrode material in which the Li ₂ MnO ₃ peak and the CuO peak are observed has the structure according to the present invention more remarkably, and can exhibit a larger charge and discharge capacity.

As described above, the method for producing a positive electrode material for a secondary battery of the present invention stirs a mixed solution obtained by adding a strong alkaline aqueous solution to a solution of a copper raw material and a manganese raw material, and coprecipitates a hydroxide containing copper and manganese. A coprecipitation step for obtaining a product, a mixing step for obtaining a mixture by mixing LiOH / H ₂ O powder with the coprecipitate, a calcining step for calcining the mixture to obtain a calcined product, and the calcined product A molding process to obtain a molded product after pulverization, and to obtain Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ by firing the molded product in an oxygen stream. And a baking step.

  Therefore, it has excellent charging and discharging characteristics, and further has an effect that it does not contain expensive Co and can be provided at low cost.

It is a graph which shows the result of a X ray diffraction method. It is a graph which shows the result of having measured the battery voltage and electric capacity of positive electrode material.

The manufacturing method of the positive electrode material for secondary batteries which concerns on this invention is demonstrated below. First, the present invention is characterized in that the positive electrode material is a composite of Li ₂ MnO ₃ and CuO. Although CuO is used as a negative electrode material, there is no example reported as a positive electrode material for a secondary battery (hereinafter abbreviated as “positive electrode material” where appropriate). The positive electrode material in which CuO is compounded as a positive electrode material has a configuration uniquely found by the present inventors.

Further, the positive electrode material according to the present invention is characterized by a peak detected by an X-ray diffraction method although it depends on the concentration of Cu. Normally, when the cathode material based on Li ₂ MnO ₃ is analyzed by X-ray diffraction, a solid solution is formed with Li ₂ MnO ₃ and other transition metal oxides, so the peak of the transition metal oxide itself is observed. Not.

  On the other hand, in the positive electrode material according to the present invention, although depending on the concentration of CuO, a peak of CuO is observed. Such observation results have not been observed with conventional positive electrode materials. Although the detailed structure has not been analyzed, it is apparent that the positive electrode material of the present invention and the conventionally known positive electrode material are different from each other.

Next, the complexation of Li ₂ MnO ₃ and CuO is not simply performed by a solid-phase reaction using both raw material powders, but a synthesis process by a coprecipitation method that is a liquid phase method needs to be performed. is there. Although the detailed reason has not been clarified, there is a possibility that it is related to the ability to uniformly disperse copper and manganese in the coprecipitate by the coprecipitation method. On the other hand, when the process by the liquid phase method is not performed, the positive electrode material according to the present invention cannot be obtained. Hereinafter, each process included in the manufacturing method of the positive electrode material of the present invention will be described.

(Co-precipitation process)
The coprecipitation step is a step of obtaining a coprecipitate of copper hydroxide and manganese hydroxide by stirring a mixed solution obtained by adding a strong alkaline aqueous solution to a solution in which a copper raw material and a manganese raw material are dissolved.

The copper material contains copper, and the manganese raw material contains manganese. The copper raw material and the manganese raw material are not particularly limited as long as a coprecipitate of copper hydroxide and manganese hydroxide can be obtained by adding a strong alkaline aqueous solution to the dissolved solution. As the copper material, CuSO ₄ .5H ₂ O, CuCl ₂ .2H ₂ O, Cu (NO ₃ ) ₂ .3H ₂ O, or the like can be used. Of these, CuSO ₄ .5H ₂ O is more preferable from the viewpoint of handling during weighing.

On the other hand, (CH ₃ COO) ₂ Mn · 4H ₂ O, Mn (NO ₃ ) ₂ · 6H ₂ O, Mn (SO ₄ ) ₂ · 5H ₂ O, and the like can be used as manganese raw materials. Among these, (CH ₃ COO) ₂ Mn · 4H ₂ O is more preferable from the viewpoint of accurate composition control. Specifically, (CH ₃ COO) ₂ Mn · 4H ₂ O has a constant amount of water of hydration and is unlikely to cause deliquescence.

  The solution of the copper raw material and the manganese raw material may be obtained by mixing a solution obtained by separately dissolving the copper raw material and the manganese raw material in a solvent. The copper raw material and the manganese raw material are dissolved together in a solvent. It may be obtained. Water can be used as the solvent, and pure water (purity 99% or more) is preferably used. In addition, oxalate coprecipitate can be used instead of hydroxide, and ethanol can be used as a solvent in that case.

  The molar ratio of the copper raw material to the manganese raw material is preferably 1 or more and 5 or less. Since the peak by the X-ray diffraction method of CuO 2 in the positive electrode material of the present invention is more prominently detected by the above molar ratio, it is considered that the configuration unique to the positive electrode material of the present invention becomes more prominent.

  The concentration of the manganese raw material in the solution is preferably 0.02M or more and 0.05M or less. By being in the above range, a coprecipitate can be suitably obtained in the coprecipitation step. The concentration ratio of the copper raw material in the solution is 1 or more and 5 or less with respect to the concentration of the manganese raw material.

  In the coprecipitation step, a strong alkaline aqueous solution is added to the copper raw material and manganese raw material solution. The strong alkaline aqueous solution is preferably added gradually to the solution. For example, the strong alkaline aqueous solution may be dropped using a dropping funnel or the like. Specific examples of the strong alkaline aqueous solution include a LiOH aqueous solution, a NaOH aqueous solution, and a KOH aqueous solution. Among these, a LiOH aqueous solution is more preferable because it hardly affects the positive electrode material when it remains.

  After adding the strong alkaline aqueous solution, the mixed solution is stirred. The stirring time is preferably a long time in order to promote grain growth of the generated precipitate and to make the precipitate uniform in particle size. . Thereby, a more suitable coprecipitate can be obtained.

  Specifically, stirring for 12 hours or more is preferable, and stirring for 24 hours or more is more preferable. Although an upper limit is not specifically limited, It can be 48 hours or less.

  After stirring, a coprecipitate containing copper and manganese can be obtained. The coprecipitate may be recovered by a known method such as suction filtration. The coprecipitate is a hydroxide and is used as a raw material for the positive electrode raw material of the present invention. If the collected coprecipitate contains a large amount of water, dry it. The drying may be performed, for example, under drying conditions of 70 ° C. to 80 ° C. for 12 hours.

(Mixing process)
The mixing step is a step of obtaining a mixture by mixing LiOH · H ₂ O powder with the coprecipitate. The amount of LiOH · H ₂ O used is preferably an excess amount relative to the total moles of the copper raw material and the manganese raw material. Specifically, the excess amount can be 1% or more and 5% or less.

Thereafter, the coprecipitate and the LiOH.H ₂ O powder are mixed to obtain a mixture. For mixing, a known mixing device may be used, and a mortar and pestle, an agate mortar, a mesh or the like may be used. By using a mesh, the particle size of the mixture can be fractionated. The mixing time may be determined while observing the degree of mixing. For example, the mixing time may be 5 minutes or more and 30 minutes or less.

(Calcination process)
The calcining step is a step of calcining the mixture to obtain a calcined product, and calcining is performed before the calcining step to be performed later. In the temporary firing step, firing is performed at a lower temperature than in the firing step. As conditions for calcination, the temperature is raised from room temperature at a rate of 4 ° C. or more and 8 ° C. or less, 450 ° C. or more, 490 ° C. or less, 5 hours or more, 7 hours or less, and 4 ° C./min. Lower the temperature at the above speed. The calcination atmosphere may be in the air or in an oxidizing atmosphere such as oxygen flow.

  After the calcination time is over, natural cooling is started and the process proceeds to the molding step. From the viewpoint of safety, it is desirable to cool the calcined product to room temperature in natural cooling. In addition, a calcination process can be performed using a well-known electric furnace etc.

(Molding process)
The molding step is a step of obtaining a molded product by pulverizing the calcined product and then molding it. The molded product obtained by molding the powder obtained by pulverizing the temporarily fired product is preferably in the form of a pellet from the viewpoint of easy firing, but is not limited to this shape. The pellet-shaped molded product is molded by pressure molding.

(Main firing process)
The firing step is a step in which the molded product is _subjected to main firing in an oxygen stream to obtain a positive electrode material Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (x is 0. 0). 01 or more and 1/2 or less). As conditions for the main firing, the temperature can be raised from room temperature at a rate of 4 ° C or more and 8 ° C or less, 700 ° C or more, 800 ° C or less, 12 hours or more, 24 hours or less, and 4 ° C per minute Lower the temperature at the above speed.

In addition, the main firing is performed in an atmosphere of oxygen flow. The flow rate of oxygen was 5 cc / min. 25cc / min. Or less, preferably 10 cc / min. 20 cc / min. The following is more preferable. By carrying out the main firing in an oxygen stream, the resulting positive electrode material can be combined with a suitable chemical state of Li ₂ MnO ₃ and CuO.

  After the time of the main firing, natural cooling is started to cool the positive electrode material. From the viewpoint of safety, it is desirable to cool the positive electrode material to room temperature in natural cooling. In addition, this baking process can be performed using a well-known electric furnace etc.

(Assembly process)
The assembly process uses at least Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (x is 0.01 or more and 1/2 or less) as the positive electrode material. This is a step of obtaining a secondary battery. The secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode can be manufactured using the positive electrode material, the conductive agent, and the binder, and the negative electrode can be manufactured using the negative electrode material, the conductive agent, and the binder that can desorb and insert lithium ions.

  The weight of the positive electrode material according to the present invention can be 30 parts by weight or more and 70 parts by weight with respect to the total weight of the positive electrode, and is 40 parts by weight or more and 60 parts by weight or less. Above preferred.

  On the other hand, as the negative electrode material, lithium metal, lithium alloy (lithium metal-containing alloys such as lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin and lithium-aluminum-tin), lithium composite oxide (lithium-titanium) ) Can be used. The weight of the negative electrode material can be 30 parts by weight or more and 70 parts by weight, and preferably 40 parts by weight or more and 60 parts by weight or less with respect to the total weight of the negative electrode.

  The conductive agent is not particularly limited as long as it does not adversely affect the performance of the secondary battery. For example, conductive materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon whisker, carbon fiber, metal (copper, aluminum, etc.) can be used as one kind or a mixture thereof.

  Among these, acetylene black is desirable from the viewpoint of improving electronic conductivity in the positive electrode and the negative electrode. The addition amount of the conductive agent is preferably 10% by weight or more and 40% by weight or less, and preferably 20% by weight or more and 30% by weight or less with respect to the total weight of the positive electrode or the negative electrode.

  Known binders can be used, and thermoplastic resins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene and polypropylene, and polyolefin polymers such as ethylene-propylene-diene terpolymers are used. be able to. The addition amount of the binder is preferably 10 parts by weight or more and 50% by weight or less, more preferably 15% by weight or more and 30 parts by weight or less with respect to the total weight of the positive electrode or the negative electrode.

  Examples of the equipment for mixing the raw materials for the positive electrode and the negative electrode include a powder mixer such as a V-type mixer, an S-type mixer, a ball mill, and a planetary ball mill. A positive electrode mixture and a negative electrode mixture are obtained by a powder mixer. The method for forming the positive electrode mixture as a positive electrode and the negative electrode mixture as a negative electrode is not particularly limited, and a known method may be used. For example, the method of forming a pellet-like positive electrode and negative electrode by pressurization is mentioned. Moreover, the method of apply | coating the paste formed by adding a solvent to a positive electrode mixture and a negative electrode mixture to a collector, and forming a sheet-like positive electrode and a negative electrode is also mentioned.

  A conventionally well-known thing should just be used for electrolyte solution, and what dissolved electrolyte in the organic solvent can be used. Examples of the organic solvent include esters such as propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate, and ethers such as diethyl ether. On the other hand, examples of the electrolyte include lithium salts such as lithium perchlorate and lithium halide.

  The separator that separates the electrolytic solution in the secondary battery is not particularly limited. For example, fluorine-containing copolymers such as polyolefin resins such as polyethylene and polypropylene, ester resins such as polyethylene terephthalate and polybutylene terephthalate, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-trifluoroethylene copolymer, etc. Coalescence can be mentioned.

  Examples of the shape of the secondary battery include a button type, a coin type, and a sheet type, and are not particularly limited.

The positive electrode material according to the present invention has a structure of Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ , and Li ₂ MnO ₃ and CuO are combined. FIG. 1 shows the result of performing X-ray diffraction on each positive electrode in which the molar ratio x of Cu in the positive electrode material is variously changed. FIG. 1 is a graph showing the results of X-ray diffraction. For the X-ray diffraction method, an XRD-6100 apparatus (Shimadzu Corporation) was used. The X-ray source used was a CuKa line monochromatized with graphite, and diffraction lines were measured with a diffractometer. The measurement conditions were a powdered positive electrode material with a tube voltage of 40.0 kV, a tube current of 30.0 mA, and a range of 2θ of 10.0 to 100.0 in 0.02 ° steps, a scanning speed of 4 ° / min, and a continuous scan mode. .

As is clear from FIG. 1, when x is 1/100 and 1/20, the X-ray diffraction peak of CuO is not clear, but when x exceeds 1/10, the peak of CuO is clearly observed. I understand that In general, in composite oxides, peaks of transition metal oxides other than Li ₂ MnO ₃ are not observed in this way, and the observation of CuO peaks is a matter specific to the positive electrode material according to the present invention. is there.

In FIG. 1, a significant peak of Li ₂ MnO ₃ is detected when 2θ is 18.68 / degree or more, 18.72 / degree or less, 37.04 / degree or more, 37.08 / degree or less, 44.66 / degree or more, 44.76 / degree or less. ing. On the other hand, significant peaks of CuO 2 are detected at 2θ of 35.62 / degree or more and 35.66 / degree or less, 38.84 / degree or more, 38.90 / degree or less, 48.70 / degree or more, and 48.82 / degree or less.

From the result of the X-ray diffraction method, the positive electrode material according to the present invention is assumed to have a unique structure. Usually, in the case of a complex oxide (Li [Ni ²⁺ _x Li _{(1 / 3-2 / 3x)} Mn ⁴⁺ _{(2 / 3-x / 3)} ] O ₂ ) with Ni added to Li ₂ MnO ₃ , The upper limit of 0.8 mol of Li to be desorbed and inserted is usually. However, in the positive electrode material according to the present invention, more than 1 mol of Li can be desorbed and inserted, and a large charge and discharge capacitance can be obtained.

On the other hand, FIG. 2 is a graph showing the results of measuring the battery voltage and electric capacity of each positive electrode material. Comparing the graph of Li ₂ MnO ₃ indicated by the broken line in FIG. 2 with the graph of the positive electrode material of the present invention (x = 0.01 (1/100)), the ratio of CuO was only slightly increased. However, it can be seen that the battery voltage is lowered and the electron conductivity is improved. Furthermore, when x = 1/2, it can be seen that a significant increase in the charge capacity of 400 mAh / g was achieved while suppressing the operating voltage, and the discharge capacity up to 2.0 V reached 200 mAh / g. . In addition, comparison with Li ₂ MnO ₃ alone shows that the electron conductivity is improved and the overvoltage is reduced. In addition, it can be seen that the charge and discharge electric capacities are larger than those of the conventional Li ₂ Ni _0.5 Mn _0.5 O ₃ .

  Further, the positive electrode material of the present invention does not contain Co, but contains Cu which is cheaper and easily available. Therefore, it can be provided at a lower cost than conventional positive electrode materials containing expensive Co.

  Further, as shown in FIG. 1, the positive electrode material according to the present invention has a characteristic structure in which CuO is observed as a single peak due to the ratio of Cu, and CuO is mixed in the positive electrode material. Yes. In addition, as shown in FIG. 2, since a significant effect is observed even if the mixing ratio of Cu is small, charging and discharging are performed in a process different from that of a conventional positive electrode material that desorbs and inserts Li ions. It is thought that. Such a phenomenon has not been reported so far, and is a unique phenomenon of the positive electrode material, which is a significant difference from the conventional positive electrode material.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

  The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention. In addition, the electric capacity of the secondary battery in the following examples and comparative examples was evaluated as follows.

All samples Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (X is 1/100, 1/20, 1/10, 1/5, 1/4, 1/3, 5/12, 1/2) were synthesized using the coprecipitation method (1.0 g / batch). The starting materials were CuSO ₄ · 5H ₂ O (Wako Pure Chemical Industries, Ltd., purity 95.0%) and (CH ₃ COO) ₂ Mn · 4H ₂ O (Wako Pure Chemical Industries, Ltd., purity> 99.0%). . A stoichiometric amount of the starting material was weighed and dissolved in 200 ml of distilled water, and 100 ml of 1M LiOH aqueous solution was gradually added dropwise while stirring the solution to co-precipitate Cu-Mn. After the coprecipitate was stirred in the atmosphere for 24 hours, the coprecipitate was collected by suction filtration and dried at 72 ° C. overnight (12 hours). Mix the dried coprecipitate with 5% excess LiOH · H ₂ O (Wako Pure Chemical Industries, Ltd., purity 98.0-102.0%) for 10 minutes using a mortar and pestle and then mix for 15 minutes in an agate mortar. To obtain a mixture. The above mixture was pressure-molded into pellets and calcined in the atmosphere at 470 ° C. for 6 hours. The calcined product was pulverized and pressed again into a pellet to form a molded product, and then the molded product was calcined at 700 ° C. for 12 hours in an oxygen stream (10-20 cc / min) to obtain a positive electrode material.

Using the obtained positive electrode material, a coin-type secondary battery was manufactured. The positive electrode (φ14mm) is made from positive electrode material 55wt%, acetylene black (Electrochemical Industry Co., Ltd.) 20wt%, PVDF (Kureha Co., Ltd.) 25wt%, and the negative electrode (φ14mm) is lithium metal (thickness 0.2mm, Honjo Metal) GLASS MICROFIBER FILTERS (Whatman Inc.) was used for the separator (φ15mm). Further, 1M LiClO ₄ / PC: DMC (1: 1 v / v%) was used as the electrolyte.

  The battery characteristics were evaluated by using a coin-type cell (2032 type) and performing a constant current charge / discharge measurement (HJ-SD8, Hokuto Denko Co., Ltd.) at a current density of 13.65 mA / g between 1.5 V and 4.8 V. The result of measuring the positive electrode material by the X-ray diffraction method is shown in FIG. In addition, FIG. 2 shows a charge / discharge measurement result of a secondary battery using a positive electrode material having x of 0.5 (1/2) or 0.01 (1/100).

[Comparative Example 1]
A positive electrode material (Li ₂ MnO ₃ ) was obtained in the same procedure as in Example 1 except that CuSO ₄ .5H ₂ O was not used as a starting material. Thereafter, in the same manner as in Example 1, a secondary battery was manufactured using the obtained positive electrode material. The results are shown in FIG.

[Comparative Example 2]
In Example 1, the starting material CuSO ₄ · 5H ₂ O was changed to Ni (NO ₃ ) ₂ · 6H ₂ O, and the resulting positive electrode material was NiNi at a stoichiometric amount of LiNi _0.5 Mn _0.5 O _2. (NO ₃ ) ₂ · 6H ₂ O is weighed and dissolved in 200 ml of distilled water, and the calcination process is performed at 600 ° C. for 6 hours in the atmosphere and the firing process is performed at 900 ° C. for 24 hours in the atmosphere. Got. Thereafter, in the same manner as in Example 1, a secondary battery was manufactured using the obtained positive electrode material. The results are shown in FIG.

  Since the positive electrode material according to the present invention can be used as a material for a secondary battery, it can be used in all fields related to a secondary battery.

Claims (6)

A coprecipitation step of stirring a mixed solution obtained by adding a strong alkaline aqueous solution to a copper raw material and a manganese raw material solution to obtain a coprecipitate of a hydroxide containing copper and manganese;
A mixing step of obtaining a mixture by mixing LiOH · H ₂ O powder with the coprecipitate;
A calcining step of calcining the mixture to obtain a calcined product;
After pulverizing the calcined product, a molding step for molding to obtain a molded product,
A book obtained by firing the above molded product in an oxygen stream to obtain Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (x is 0.01 or more and 1/2 or less). The manufacturing method of the positive electrode material for secondary batteries characterized by including a baking process.   The method for producing a positive electrode material for a secondary battery according to claim 1, wherein a molar ratio of the manganese raw material to the copper raw material is 1 or more and 5 or less.   The method for producing a positive electrode material for a secondary battery according to claim 1 or 2, wherein the mixed solution is stirred for 24 hours or more in the coprecipitation step. The _secondary material according to any one of claims 1 to 3, wherein the copper raw material is CuSO ₄ · 5H ₂ O and the manganese raw material is (CH ₃ COO) ₂ Mn · 4H ₂ O. A method for producing a positive electrode material for a battery. A coprecipitation step of stirring a mixed solution obtained by adding a strong alkaline aqueous solution to a solution in which a copper raw material and a manganese raw material are dissolved, to obtain a coprecipitate of copper hydroxide and manganese hydroxide;
A mixing step of obtaining a mixture by mixing LiOH · H ₂ O powder with the coprecipitate;
A calcining step of calcining the mixture to obtain a calcined product;
A molding step of pulverizing and molding the calcined product to obtain a molded product;
A book obtained by firing the above molded product in an oxygen stream to obtain Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ (x is 0.01 or more and 1/2 or less). Baking process,
A method of manufacturing a secondary battery, comprising: an assembly step of obtaining a secondary battery using at least the above Li _{4 / 3-2x / 3} Cu _x Mn _{2 / 3-x / 3} O ₂ as a positive electrode material. A positive electrode material for a secondary battery obtained by the method for producing a positive electrode material for a secondary battery according to any one of claims 1 to 4,
A positive electrode material for a secondary battery, characterized in that a Li ₂ MnO ₃ peak and a CuO peak are observed by an X-ray diffraction method.

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