JP7078217B2 - Fluorine-containing lithium composite transition metal oxide particles - Google Patents

Description

The present invention relates to fluorine-containing lithium composite transition metal oxide particles. More specifically, the present invention relates to fluorine-containing lithium composite transition metal oxide particles and a method for producing the same, fluorine-containing transition metal oxide particles used as a raw material for the fluorine-containing lithium composite transition metal oxide particles, and a method for producing the same. Fluorine-containing transition metal hydroxide particles used as a raw material for fluorine-containing transition metal oxide particles, an active material for a non-aqueous electrolyte secondary battery containing the fluorine-containing lithium composite transition metal oxide particles, and the non-aqueous electrolyte secondary. The present invention relates to an electrode for a non-aqueous electrolyte secondary battery containing an active material for a battery, and a non-aqueous electrolyte secondary battery having the electrode for the non-aqueous electrolyte secondary battery.

As the active material for a lithium secondary battery, composite oxide particles of lithium and a transition metal such as nickel, manganese, and cobalt are generally used. More specifically, composite oxide particles of lithium and a transition metal such as nickel, manganese, and cobalt are used as the positive electrode active material, and composite oxide particles of lithium and a transition metal such as titanium are used as the negative electrode active material. Is used. When producing the composite oxide particles, particles of a lithium compound such as lithium carbonate, lithium hydroxide, and lithium oxide are used as the lithium source of the composite oxide particles, and as a transition metal source of the composite oxide particles. Particles of transition metal compounds such as oxides of transition metals, hydroxides, carbonates and nitrates are used. The composite oxide particles are generally produced by firing (heat treating) a mixture of particles of a lithium compound and particles of a transition metal compound (see, for example, Patent Document 1). The active material for a lithium secondary battery has a property that the battery resistance below the freezing point is low, and is useful for, for example, a lithium secondary battery showing a high output.

However, in recent years, the development of active materials for non-electrolyte secondary batteries having a large charge / discharge capacity and excellent cycle characteristics has been awaited.

Japanese Unexamined Patent Publication No. 2015-118945

The present invention has been made in view of the above-mentioned prior art, and is used as a raw material for a non-aqueous electrolyte secondary battery active material having a large charge / discharge capacity and excellent cycle characteristics, and a raw material for the non-aqueous electrolyte secondary battery active material. Useful fluorine-containing lithium composite transition metal oxide particles and a method for producing the same, fluorine-containing transition metal oxide particles useful as a raw material for the fluorine-containing lithium composite transition metal oxide particles and a method for producing the same, fluorine-containing transition metal oxide. A non-aqueous electrolyte secondary battery electrode containing the fluorine-containing transition metal hydroxide particles useful as a raw material for the particles, the active material for the non-aqueous electrolyte secondary battery, and the non-aqueous electrolyte secondary battery electrode. An object of the present invention is to provide a water electrolyte secondary battery.

The present invention
(1) Particles having crystals made of a fluorine-containing lithium composite transition metal oxide having at least one transition metal selected from the group consisting of Co, Ni and Mn as the transition metal, and having a plurality of crystals. Fluorine is present at the boundary between the crystallites, and the electron beam impervious region and the electron beam impervious region that is relatively easy to transmit electron beams with respect to the electron beam impervious region are the sea-islands. The state is formed on the cut surface of the particle, the sea state is the electron beam impervious region, the island state is the electron beam transmissive region, and the electron beam transmissive region is the cut surface of the particle. Fluorine-containing lithium composite transition metal oxide particles, characterized in that the ratio of the area to the electron is 15 to 80%.
(2) The fluorine-containing lithium composite transition metal oxide particles according to (1) above, wherein the electron beam translucent region has an average diameter of 30 to 1000 nm.
(3) The fluorine-containing lithium composite transition metal oxide particles according to (1) or (2) above, wherein the fluorine-containing lithium composite transition metal oxide particles have a particle size of 100 nm to 100 μm.
(4) The method for producing a fluorine-containing lithium composite transition metal oxide particle according to any one of (1) to (3) above, wherein a plurality of transition metal hydroxide particles are treated with fluorine. Fluorine-containing transition metal hydroxide particles having crystallites and fluorine at the boundary between the crystallites are prepared, and the fluorine-containing transition metal hydroxide particles are fired to have a plurality of crystallites. Then, fluorine-containing transition metal oxide particles in which fluorine is present at the boundary between the crystallites are prepared, and the fluorine-containing transition metal oxide particles are used as the transition metal oxide particles to be used with the fluorine-containing transition metal oxide particles. A method for producing fluorine-containing lithium composite transition metal oxide particles, which comprises mixing with a lithium compound and firing the obtained mixture.
(5) A method for producing a fluorine-containing transition metal oxide particle having at least one transition metal selected from the group consisting of Co, Ni and Mn as the transition metal , which has a plurality of crystallites. A method for producing fluorine-containing transition metal oxide particles, which comprises firing fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary between crystallites.
(6) A particle made of a fluorine-containing transition metal hydroxide having at least one transition metal selected from the group consisting of Co, Ni and Mn as a transition metal, having a plurality of crystallites, and the crystal thereof. Fluorine-containing transition metal hydroxide particles, characterized by the presence of fluorine at the boundaries between the children,
(7) An active material for a non-aqueous electrolyte secondary battery, which comprises the fluorine-containing lithium composite transition metal oxide particles according to any one of (1) to (3) above.
(8) The electrode for a non-aqueous electrolyte secondary battery, which comprises the active material for the non-aqueous electrolyte secondary battery according to the above (7), and (9) the non-aqueous electrolyte according to the above (8). The present invention relates to a non-aqueous electrolyte secondary battery having an electrode for a secondary battery.

According to the present invention, a fluorine-containing lithium composite transition metal oxide useful as a raw material for a non-aqueous electrolyte secondary battery active material having a large charge / discharge capacity and excellent cycle characteristics and a non-aqueous electrolyte secondary battery active material. Particles and method for producing them, fluorine-containing transition metal oxide particles useful as a raw material for the fluorine-containing lithium composite transition metal oxide particles and methods for producing the same, fluorine-containing transition metal useful as a raw material for the fluorine-containing transition metal oxide particles. Provided are a non-aqueous electrolyte secondary battery electrode containing the hydroxide particles, the active material for the non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery having the electrode for the non-aqueous electrolyte secondary battery.

In Example 1, it is a graph which shows the measurement result of the powder X-ray diffraction of nickel hydroxide and fluorine-containing nickel hydroxide. (A) is a scanning electron micrograph of nickel hydroxide used in Example 1, and (b) is a scanning electron micrograph of fluorine-containing nickel hydroxide obtained in Example 1. In Example 1, it is a graph which shows the measurement result of the X-ray photoelectron spectroscopic analysis of nickel hydroxide and fluorine-containing nickel hydroxide. It is a graph which shows the measurement result of the Auger electron spectroscopic analysis of the fluorine-containing nickel hydroxide obtained in Example 1. FIG. It is a graph which shows the measurement result of the powder X-ray diffraction of the fluorine-containing nickel oxide particles and the nickel oxide particles obtained in Example 1. FIG. (A) is a scanning electron micrograph of the nickel oxide particles, and (b) is a scanning electron micrograph of the fluorine-containing nickel oxide particles obtained in Example 1. It is a graph which shows the measurement result of the X-ray photoelectron analysis of the fluorine-containing nickel oxide particles and the nickel oxide particles obtained in Example 1. It is a graph which shows the measurement result of the Auger electron spectroscopic analysis of the fluorine-containing nickel oxide particles obtained in Example 1. FIG. It is a graph which shows the measurement result of the powder X-ray diffraction of the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles obtained in Example 1. (A) is a scanning electron micrograph of the fluorine-containing lithium composite nickel oxide particles obtained in Example 1, and (b) is a scanning electron micrograph of the lithium composite nickel oxide particles. It is a graph which shows the measurement result of the X-ray photoelectron analysis of the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles obtained in Example 1. It is a graph which shows the charge-discharge curve using the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles obtained in Example 1, (a) shows a charge curve, (b) shows a discharge curve. It is a graph which shows the result of having investigated the cycle characteristic using the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles obtained in Example 1. It is a scanning electron micrograph when the cut surface of the fluorine-containing lithium composite nickel oxide particles obtained in Example 6 was irradiated with an electron beam.

Fluorine-containing lithium composite transition metal oxide particles are used as a raw material for the active material for a non-aqueous electrolyte secondary battery of the present invention. Fluorine-containing transition metal oxide particles are used as a raw material for the fluorine-containing lithium composite transition metal oxide particles. Fluorine-containing transition metal hydroxide particles are used as a raw material for the fluorine-containing transition metal oxide particles. Further, transition metal hydroxide particles are used as a raw material for the fluorine-containing transition metal hydroxide particles.

[Transition metal hydroxide particles]
Examples of the transition metal used for the transition metal hydroxide particles include transition metal hydroxides such as Fe, Co, Ni, Mn, V, Zr, W, and Ti. It is not limited to only. These transition metals may be used alone or in combination of two or more. Among the transition metals, Co, Ni and Mn are preferable, Ni and Co are more preferable, and Ni is further preferable, from the viewpoint of obtaining an active material for a non-aqueous electrolyte secondary battery having a large charge / discharge capacity and excellent cycle characteristics. .. The transition metal hydroxide may contain a typical metal such as Mg or Al as long as the object of the present invention is not impaired.

The transition metal hydroxide particles can be prepared, for example, by a continuous coprecipitation method, a batch coprecipitation method, or the like.

Hereinafter, an example of the case where transition metal hydroxide particles containing Ni, Co and Mn as transition metals are prepared by the coprecipitation method will be described, but the present invention is not limited to this one example.

The transition metal hydroxide particles contain, for example, Ni, Co and Mn by coexisting with a Ni salt aqueous solution, a Co salt aqueous solution, an Mn salt aqueous solution and, if necessary, a complexing agent, and neutralizing with an alkali. Oxide particles can be prepared.

Examples of the Ni salt which is a solute of the Ni salt aqueous solution include nickel sulfate, nickel nitrate, nickel chloride, nickel acetate and the like, but the present invention is not limited to such examples. These Ni salts may be used alone or in combination of two or more. Examples of the Co salt which is the solute of the Co salt aqueous solution include cobalt sulfate, cobalt nitrate, cobalt chloride, and the like, but the present invention is not limited to these examples. These Co salts may be used alone or in combination of two or more. Examples of the Mn salt which is the solute of the Mn salt aqueous solution include manganese sulfate, manganese nitrate, manganese chloride and the like, but the present invention is not limited to these examples. These Mn salts may be used alone or in combination of two or more.

As the complexing agent, one that forms a complex with each ion of Ni, Co, and Mn in water is used. Examples of the complexing agent include ammonium ion feeders such as ammonium sulfate, ammonium chloride, ammonium carbonate, and ammonium fluoride, hydrazine, ethylenediamine tetraacetic acid, nitrilotriacetic acid, uracildiacetic acid, and glycine. , The example is not limited to this.

The reaction of the Ni salt aqueous solution, the Co salt aqueous solution, the Mn salt aqueous solution and the complexing agent can be carried out, for example, at a reaction temperature of 10 to 80 ° C., preferably a reaction temperature of 20 to 60 ° C.

Alkaline metal hydroxides such as sodium hydroxide and potassium hydroxide are added to the reaction solution from the viewpoint of promoting precipitation after the coexistence of a Ni salt aqueous solution, a Co salt aqueous solution, an Mn salt aqueous solution and, if necessary, a complexing agent. Add an alkaline aqueous solution such as an aqueous solution or an aqueous ammonia solution.

As described above, a Ni salt aqueous solution, a Co salt aqueous solution, an Mn salt aqueous solution and, if necessary, a complexing agent are allowed to coexist, and the precipitate formed by adding the alkaline aqueous solution is washed with water and then dried to obtain Ni, Co and Hydroxide particles containing Mn can be isolated. The isolated hydroxide particles containing Ni, Co and Mn can be obtained by, for example, classification such as pulverization or sieving, or by using both of them in combination to obtain hydroxide particles containing Ni, Co and Mn having a predetermined particle size. Obtainable.

The particle size of the transition metal hydroxide particles is not particularly limited, but is usually preferably about 100 nm to 100 μm.

In the present invention, the particle diameter of each particle is a value measured based on the following method.
[Measurement method of particle size of particles]
Using water as a solvent, measure the particle size distribution of the particles using a laser diffraction / scattering type particle size distribution measuring device [Microtrac Bell Co., Ltd., product number: MT3300EXII], and D50 (median diameter) in the particle size distribution. Is the particle size of the particle.

[Fluorine-containing transition metal hydroxide particles]
The fluorine-containing transition metal hydroxide particles are particles made of a fluorine-containing transition metal hydroxide, have a plurality of crystallites, and are characterized by the presence of fluorine at the boundary between the crystallites.

In the present invention, one major feature is that fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary between crystallites are used. When a non-aqueous electrolyte secondary battery active material is prepared using fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary between crystals, the active material for the non-aqueous electrolyte secondary battery is filled. It has a large discharge capacity and excellent cycle characteristics.

Fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary of the crystallite can be prepared, for example, by subjecting the transition metal hydroxide particles to fluorine treatment.

Fluorine treatment of the transition metal hydroxide particles can be performed by a dry method or a wet method.

In the dry method, transition metal hydroxide particles are treated with fluorine in the gas phase using a gaseous fluorinating agent. In the wet method, transition metal hydroxide particles are treated with fluorine in a liquid phase using a liquid fluorinating agent or a fluorinating agent solution. Among these methods, the dry method is preferable because the operation is simple.

Examples of the fluorinating agent include fluorine (F ₂ ), nitrogen trifluoride, chlorine trifluoride, bromine trifluoride, bromine pentafluoride, bromine heptafluoride, and carbonyl difluoride. The invention is not limited to such embodiments. These fluorinating agents may be used alone or in combination of two or more. Among the fluorinating agents, fluorine, nitrogen trifluoride, chlorine trifluoride, bromine trifluoride, bromine pentafluoride and bromine heptafluoride are preferable from the viewpoint of ease of handling, and fluorine, nitrogen trifluoride and bromine trifluoride are preferable. Chlorine trifluoride is more preferred. If necessary, the fluorinating agent may be diluted with an inert gas such as nitrogen gas, helium gas, neon gas, argon gas or xenone gas, or a diluting gas such as a perfluorocarbon compound gas such as carbon tetrafluoride. .. When the transition metal hydroxide particles are treated with fluorine by a dry method, it is preferable to use a fluorinating agent gas such as fluorine gas, nitrogen trifluoride gas, or chlorine trifluoride gas as the fluorinating agent.

In the following, a case where the transition metal hydroxide particles are treated with fluorine by a dry method will be described.

When the transition metal hydroxide particles are treated with fluorine by a dry method, the transition metal hydroxide particles can be treated with fluorine by contacting the transition metal hydroxide particles with a fluorinating agent gas. As a method of bringing the transition metal hydroxide particles into contact with the fluorinating agent gas, for example, the transition metal hydroxide particles are fluorinated by allowing the transition metal hydroxide particles to exist in the closed atmosphere of the fluorinating agent gas. A method of contacting with an agent gas (hereinafter referred to as a batch method), a method of contacting a transition metal hydroxide particle with a fluorinating agent gas by supplying a fluorinating agent gas to the transition metal hydroxide particles (flow method). However, the present invention is not limited to such an example. Among these methods, the batch method is preferable from the viewpoint of safety and the like.

When the transition metal hydroxide particles are treated with fluorine by the batch method, for example, the transition metal hydroxide particles are in the atmosphere of a fluorinating agent gas having a pressure of 0.1 to 10 kPa and a temperature of 0 to 60 ° C. The transition metal hydroxide particles can be treated with fluorine by contacting with the fluorinating agent gas.

The pressure of the fluorinating agent gas when the transition metal hydroxide particles are brought into contact with the fluorinating agent gas is preferably 0.1 kPa or more, more preferably 0.1 kPa or more, from the viewpoint of increasing the efficiency of the fluorine treatment of the transition metal hydroxide particles. It is 0.3 kPa or more, more preferably 0.5 kPa or more, still more preferably 1 kPa or more, and is preferably 10 kPa or less, more preferably 5 kPa or less, still more preferably, from the viewpoint of enhancing safety and suppressing excessive fluorine treatment. Is 3 kPa or less.

The temperature of the fluorinating agent gas when the transition metal hydroxide particles are brought into contact with the fluorinating agent gas is preferably 0 ° C. or higher, more preferably 10 from the viewpoint of increasing the efficiency of the fluorine treatment of the transition metal hydroxide particles. The temperature is preferably 60 ° C. or higher, more preferably 20 ° C. or higher, preferably 60 ° C. or lower, more preferably 50 ° C. or lower, still more preferably 40 ° C. or lower, from the viewpoint of enhancing safety and suppressing excessive fluorine treatment. Therefore, in the present invention, since the fluorine treatment of the transition metal hydroxide particles can be performed at room temperature, no thermal energy for heating or cooling is required, so that the fluorine of the transition metal hydroxide particles is efficiently used. Processing can be performed.

In the present invention, fluorine gas is used as the fluorinating agent, and the transition metal hydroxide particles are brought into contact with the fluorine gas in the atmosphere of the fluorine gas to efficiently produce the fluorine-containing transition metal hydroxide particles. It is preferable from the viewpoint of

The time for contacting the transition metal hydroxide particles with the fluorinating agent gas cannot be unconditionally determined because it varies depending on the temperature of the fluorinating agent gas in contact with the transition metal hydroxide particles and the pressure thereof. The time required for the transition metal hydroxide particles to be brought into contact with the fluorinating agent gas is usually about 0.1 to 2 hours, which is the time required for sufficiently adhering fluorine to the transition metal hydroxide particles.

The end point of the fluorine treatment of the transition metal hydroxide particles is preferably performed until the fluorine content in the fluorine-containing transition metal hydroxide particles reaches a predetermined value. The fluorine content in the fluorine-containing transition metal hydroxide particles allows the lithium ions to move smoothly even when the firing temperature is low when the mixture of the fluorine-containing transition metal oxide particles and the lithium compound is fired. From the viewpoint of obtaining an active material for a non-aqueous electrolyte secondary battery having a large charge / discharge capacity and excellent cycle characteristics, it is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0.2. By mass% or more, lithium ions can be smoothly moved even if the firing temperature is low when firing a mixture of fluorine-containing transition metal oxide particles and a lithium compound in the same manner as described above, and the charge / discharge capacity is large. From the viewpoint of obtaining an active material for a non-aqueous electrolyte secondary battery having excellent cycle characteristics, it is preferably 10% by mass or less, more preferably 7% by mass or less, still more preferably 5% by mass or less.

In the present invention, the fluorine content in the fluorine-containing transition metal hydroxide particles is a value measured by energy-dispersed characteristic X-ray spectroscopy.

By applying the fluorine treatment to the transition metal hydroxide particles as described above, fluorine enters the boundary between the crystallites constituting the transition metal hydroxide particles, so that the transition metal hydroxide particles have a plurality of crystallites. Fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary between crystallites can be obtained.

The presence of fluorine at the boundary between the crystallites of the fluorine-containing transition metal hydroxide particles means that the crystals of the fluorine-containing transition metal hydroxide particles are not changed by X-ray diffraction, and that the fluorine-containing transition is observed. It can be confirmed by detecting the peak of fluorine by X-ray photoelectron spectroscopic analysis while etching the metal hydroxide particles. When the fluorine-containing transition metal hydroxide particles are observed with a scanning electron microscope, the crystallites of the fluorine-containing transition metal hydroxide particles and their boundaries can be observed. Since fluorine enters the boundary between the crystallites of the fluorine-containing transition metal hydroxide particles and the crystallites of the fluorine-containing transition metal hydroxide particles among the boundaries thereof, while etching the fluorine-containing transition metal hydroxide particles. By investigating whether the peak of fluorine is detected by X-ray photoelectron spectroscopic analysis, how deep is the fluorine present at the boundary between the crystallites of the fluorine-containing transition metal hydroxide particles? Can be confirmed.

[Fluorine-containing transition metal oxide particles]
The fluorine-containing transition metal oxide particles are particles made of a fluorine-containing transition metal oxide, have a plurality of crystallites, and fluorine is present at the boundary between the crystallites.

Fluorine-containing transition metal oxide particles can be prepared by firing fluorine-containing transition metal hydroxide particles having a plurality of crystallites and having fluorine at the boundary between the crystallites.

The firing temperature at the time of firing the fluorine-containing transition metal hydroxide particles is preferably 200 ° C. or higher, more preferably 400 ° C. or higher, still more preferably 600, from the viewpoint of efficiently preparing the fluorine-containing transition metal oxide particles. A temperature of ° C. or higher, more preferably 650 ° C. or higher, suppresses coarsening of fluorine-containing transition metal oxide particles, has high crystallinity, and obtains an active material for a non-aqueous electrolyte secondary battery having excellent cycle characteristics. From the viewpoint, it is preferably 950 ° C. or lower, more preferably 900 ° C. or lower, still more preferably 850 ° C. or lower.

The atmosphere for firing the fluorine-containing transition metal hydroxide particles is usually the atmosphere, but for example, pure oxygen gas, dehydrated dry air, decarbonized dry air, or the like may be used. good.

The firing time of the fluorine-containing transition metal hydroxide particles varies depending on the firing temperature and the like, and cannot be unconditionally determined. The firing of the fluorine-containing transition metal hydroxide particles suppresses the coarsening of the fluorine-containing transition metal oxide particles, and obtains an active material for a non-aqueous electrolyte secondary battery having high crystallinity and excellent cycle characteristics. From the viewpoint, it is preferable to carry out until the fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary of the crystallite disappear. The firing time of the fluorine-containing transition metal hydroxide particles is usually about 3 to 10 hours.

By firing the fluorine-containing transition metal hydroxide particles as described above, fluorine-containing transition metal oxide particles having a plurality of crystallites and having fluorine at the boundary between the crystallites can be obtained. be able to.

The presence of fluorine at the boundary between the crystallites of the fluorine-containing transition metal oxide particles means that the crystals of the fluorine-containing transition metal oxide particles are not changed by X-ray diffraction, and that the fluorine-containing transition metal oxide is oxidized. It can be confirmed by detecting the peak of fluorine by X-ray photoelectron spectroscopic analysis while etching the object particles. When the fluorine-containing transition metal oxide particles are observed with a scanning electron microscope, the crystallites of the fluorine-containing transition metal oxide particles and their boundaries can be observed. Since fluorine enters the boundary between the crystallites of the fluorine-containing transition metal oxide particles and the crystallites of the fluorine-containing transition metal oxide particles among the boundaries thereof, X-ray photoelectrons are performed while etching the fluorine-containing transition metal oxide particles. By investigating whether the peak of fluorine is detected by spectroscopic analysis, it is possible to confirm the depth of the boundary between the crystallites of the fluorine-containing transition metal oxide particles. Can be done.

[Fluorine-containing lithium composite transition metal oxide particles]
The fluorine-containing lithium composite transition metal oxide particles are particles made of a fluorine-containing lithium composite transition metal oxide, and transmit electron beams relatively to the electron beam impervious region and the electron beam impervious region. An easy electron beam permeable region is formed on the cut surface of the particle in a sea-island state, the sea state is an electron beam impervious region, and the island state is an electron beam permeable region. It is characterized by that. Since the fluorine-containing lithium composite transition metal oxide particles have the above-mentioned structure, by using the fluorine-containing lithium composite transition metal oxide particles, the charge / discharge capacity is large and the non-aqueous electrolyte secondary has excellent cycle characteristics. Active materials for batteries can be obtained.

The fluorine-containing lithium composite transition metal oxide particles use, for example, fluorine-containing transition metal oxide particles having a plurality of crystallites and fluorine present at the boundary between the crystallites, and the fluorine-containing transition metal. It can be prepared by mixing the oxide particles and the lithium compound and firing the obtained mixture.

Examples of the lithium compound include lithium salts such as lithium hydroxide, lithium carbonate and lithium nitrate, lithium oxide and the like, but the present invention is not limited to these examples. These lithium compounds may be used alone or in combination of two or more. Lithium compounds can usually be used in the form of particles. The particle size of the lithium compound particles is not particularly limited, but is usually preferably about 100 nm to 100 μm.

When the fluorine-containing transition metal oxide particles and the lithium compound are mixed, the ratio of the two is preferably appropriately determined according to the composition of the desired active material for a non-aqueous electrolyte secondary battery. The amount of the lithium compound per mole of the total amount of the transition metal contained in the fluorine-containing transition metal oxide particles has a large charge / discharge capacity, and an active material for a non-aqueous electrolyte secondary battery having excellent cycle characteristics can be obtained. From the viewpoint, it is preferably 0.5 to 1.5 mol, more preferably 0.8 to 1.2 mol, and further preferably 0.9 to 1.1 mol.

When the fluorine-containing transition metal oxide particles and the lithium compound are mixed, it is preferable to mix them so that they are uniformly dispersed from the viewpoint of obtaining an active material for a non-aqueous electrolyte secondary battery having a uniform composition.

After mixing the fluorine-containing transition metal oxide particles and the lithium compound, the obtained mixture is calcined. The atmosphere at the time of firing the mixture is usually the atmosphere, but for example, oxygen gas, dehydrated dry air, decarbonized dry air, nitrogen gas, an inert gas such as argon gas, or the like. May be.

In the present invention, when the fluorine-containing transition metal oxide particles and the lithium compound are mixed, the fluorine present on the surface of the fluorine-containing transition metal oxide particles between the fluorine-containing transition metal oxide particles and the lithium compound. Can be intervened. Therefore, lithium ions can be smoothly moved even if the firing temperature at the time of firing the mixture of the fluorine-containing transition metal oxide particles and the lithium compound particles is low.

The firing temperature of the mixture is a viewpoint of obtaining positive electrode active material particles for a non-aqueous electrolyte secondary battery having a large charge / discharge capacity and excellent cycle characteristics by smoothly moving lithium ions in fluorine-containing lithium composite transition metal oxide particles. Therefore, it is preferably 600 ° C. or higher, more preferably 650 ° C. or higher, suppresses coarsening of fluorine-containing lithium composite transition metal oxide particles, has high crystallinity, has a large charge / discharge capacity, and has excellent cycle characteristics. From the viewpoint of obtaining positive electrode active material particles for a non-aqueous electrolyte secondary battery, the temperature is preferably 1000 ° C. or lower, more preferably 950 ° C. or lower, still more preferably 850 ° C. or lower, and even more preferably 750 ° C. or lower.

The firing time of the mixture varies depending on the firing temperature of the mixture and the like, and cannot be unconditionally determined. The end point of firing of the mixture is the activity for non-aqueous electrolyte secondary batteries, which suppresses the coarsening of fluorine-containing lithium composite transition metal oxide particles, has high crystallinity, has a large charge / discharge capacity, and has excellent cycle characteristics. From the viewpoint of obtaining a substance, it is preferable to carry out until the fluorine-containing lithium composite transition metal oxide particles are sufficiently formed. The firing time of the mixture is usually preferably about 10 to 40 hours, more preferably about 15 to 35 hours.

When the mixture of the fluorine-containing transition metal oxide particles and the lithium compound particles is fired, the fluorine-containing transition metal oxide particles contained in the mixture react with the lithium compound particles, whereby the fluorine-containing lithium composite transition occurs. Metal oxide particles are formed.

By calcining the mixture as described above, fluorine-containing lithium composite transition metal oxide particles can be obtained. Since the fluorine-containing lithium composite transition metal oxide particles have a plurality of crystallites and fluorine is present at the boundary between the crystallites, the lithium ions contained in the fluorine-containing transition metal oxide particles are present. Since it moves smoothly through the fluorine, it has a large charge / discharge capacity and excellent cycle characteristics. Therefore, the fluorine-containing lithium composite transition metal oxide particles can be suitably used as an active material for a non-aqueous electrolyte secondary battery.

It can be confirmed that the fluorine-containing lithium composite transition metal oxide particles are produced by detecting lithium from the fluorine-containing lithium composite transition metal oxide particles by Auger electron spectroscopy. Further, the atomic ratio of the transition element in the fluorine-containing lithium composite transition metal oxide particles can be obtained by, for example, a metal element analysis method such as ICP emission spectroscopic analysis method.

The particle size of the fluorine-containing lithium composite transition metal oxide particles is preferably 100 nm to 100 μm from the viewpoint of obtaining fluorine-containing lithium composite transition metal oxide particles having a large charge / discharge capacity and excellent cycle characteristics.

The fluorine-containing lithium composite transition metal oxide particles have a sea-island state in which the electron beam impervious region and the electron beam transmissive region relatively easily transmit the electron beam with respect to the electron beam impervious region. Since the sea state is the electron beam impervious region and the island state is the electron beam transmissive region, the fluorine-containing lithium composite transition metal oxide particles are formed on the cut surface of the particles. By using the above, it is possible to obtain an active material for a non-aqueous electrolyte secondary battery having a large charge / discharge capacity and excellent cycle characteristics.

On the cut surface of the fluorine-containing lithium composite transition metal oxide particles, the electron beam impervious region and the electron beam transmissive region that easily transmits the electron beam relative to the electron beam impervious region are sea-islands. It can be confirmed by the following method that the particles are formed on the cut surface of the particles in the above state.

When the cut surface of the fluorine-containing lithium composite transition metal oxide particles is irradiated with an electron beam having an acceleration voltage of 1 kV, the cut surface of the fluorine-containing lithium composite transition metal oxide particles is observed with a scanning electron microscope. And the bright region adjacent to the dark region are observed. However, the dark region and the bright region cannot be specifically and quantitatively specified only by the observed dark region and bright region.

Therefore, as a result of diligent research, the present inventors have different current values (transmitted current values) flowing to the ground in the dark region and different current values (transmitted current values) flowing to the ground in the bright regions. It was found that the transmitted current value flowing in the dark region is larger than the transmitted current value flowing in the bright region. As an example, when the cut surface of the fluorine-containing lithium composite transition metal oxide particles is irradiated with an electron beam having an acceleration voltage of 1 kV, the transmission current value flowing in the dark region 60 seconds after the start of irradiation is 130 pA. Yes, the transmitted current value flowing in the bright region adjacent to the dark region is 120 pA, the transmitted current value flowing in the dark region is 80 pA, and the transmitted current value flowing in the bright region adjacent to the dark region is 70 pA. The transmitted current value flowing in the dark region is 126 pA, the transmitted current value flowing in the bright region adjacent to the dark region is 116 pA, and the transmitted current value flowing in the dark region is 130 pA. It has been confirmed that the transmission current value flowing in the bright region adjacent to the dark region is 127 pA. Further, on the cut surface of the fluorine-containing lithium composite transition metal oxide particles, the dark region exists in an island shape and the bright region exists in a sea shape. From these facts, on the cut surface of the fluorine-containing lithium composite transition metal oxide particles, the electron beam is easily transmitted through the electron beam impervious region and the electron beam impervious region relatively easily. The sex region is formed on the cut surface of the particles in the sea-island state, the sea state is the electron beam impervious region, and the island state is the electron beam transmissive region.

Therefore, on the cut surface of the fluorine-containing lithium composite transition metal oxide particles, the electron beam impervious region and the electron beam impervious region that is relatively easy to transmit electron beams with respect to the electron beam impervious region are sea-. The fluorine-containing lithium composite transition metal oxide particles are charged and discharged when they are formed in an island state, the sea state is an electron beam impervious region, and the island state is an electron beam transmissive region. It is recognized that it has a large capacity and excellent cycle characteristics.

The difference in the transmission current value of the electron beam between the electron beam easily transmissive region and the electron beam impervious region adjacent to the electron beam transmissive region is a fluorine-containing lithium composite having a large charge / discharge capacity and excellent cycle characteristics. From the viewpoint of obtaining transition metal oxide particles, it is preferably 3 to 15 pA. The transmission current value in the electron beam transmissive region and the transmission current value in the electron beam impervious region were determined by using an electric field radiation scanning electron microscope [manufactured by ZEISS, trade name: Ultra plus], and a fluorine-containing lithium composite. It is a value measured by irradiating the cut surface of the transition metal oxide particles with an electron beam having an acceleration voltage of 1 kV.

The ratio of the area of the electron beam permeable region to the cut surface of the fluorine-containing lithium composite transition metal oxide particles is from the viewpoint of obtaining fluorine-containing lithium composite transition metal oxide particles having a large charge / discharge capacity and excellent cycle characteristics. , 15-80% is preferable. The ratio of the area of the electron beam permeable region to the cut surface of the fluorine-containing lithium composite transition metal oxide particles is an acceleration voltage of 1 kV using an electric field radiation type scanning electron microscope [manufactured by ZEISS, trade name: Ultra plus]. The reflected electron image measured in 1 is calculated for 10 particles with the threshold value set to 50% and the areas of dark and bright areas calculated by the number of pixels, with the total area of dark and bright areas as the denominator and the area of dark areas as the numerator. It is the average value when it is done.

Further, the average diameter of the electron beam permeable region of the fluorine-containing lithium composite transition metal oxide particles is preferably 30 to 1000 nm from the viewpoint of obtaining fluorine-containing lithium composite transition metal oxide particles having excellent cycle characteristics. ..

The average diameter of the electron beam permeable region of the fluorine-containing lithium composite transition metal oxide particles was measured at an acceleration voltage of 1 kV using an electric field radiation scanning electron microscope [manufactured by ZEISS, trade name: Ultra plus]. From the electron image, 10 electron beam permeable regions in the island state are arbitrarily selected, and the sum of the short side and the long side in each selected region is divided by 2, which is the average value in the 10 locations. ..

As suitable fluorine-containing lithium composite transition metal oxide particles, for example, lithium composite transition metal oxide is represented by the formula (I) :.
Li _x My O _{2 (} I)
(In the formula, M is at least one atom selected from the group consisting of Co, Ni, Mn, V, Fe, Zr, W and Ti, and x satisfies 0.2 ≦ x ≦ 1.25. Indicates a number, where y indicates a number satisfying 0.3 ≦ y ≦ 1.25)
Examples thereof include fluorine-containing lithium composite transition metal oxide particles having a composition represented by.

In formula (I), M is at least one atom selected from the group consisting of Co, Ni, Mn, V, Fe, Zr, W and Ti. These atoms may be used alone or in combination of two or more. Among these atoms, Co, Ni and Mn are preferable, Ni and Co are more preferable, and Ni is further, from the viewpoint of obtaining an active material for a non-aqueous electrolyte secondary battery having a large charge / discharge capacity and excellent cycle characteristics. preferable. The transition metal hydroxide may contain a typical metal such as Mg or Al as long as the object of the present invention is not impaired.

In formula (I), x is a number from 0.2 to 1.25. x is a number of 0.2 or more, preferably 0.4 or more, from the viewpoint of stably maintaining the crystal structure of the fluorine-containing lithium composite transition metal oxide particles, and is a lithium atom per unit mass or unit volume. From the viewpoint of improving the storage amount of 1.25 or less, the number is preferably 1.0 or less.

In formula (I), y is a number from 0.3 to 1.25. y is a number of 0.3 or more from the viewpoint of stably maintaining the crystal structure of the fluorine-containing lithium composite transition metal oxide particles, and from the viewpoint of improving the storage amount of lithium atoms per unit mass or unit volume. The number is 1.25 or less, preferably 1.0 or less.

Among the lithium composite transition metal oxides represented by the formula (I), the formula (Ia): from the viewpoint of enhancing the electrochemical stability.
Li _x My O _{2 (} Ia)
(In the formula, M, x and y are the same as above)
Lithium composite transition metal oxides having the composition represented by are preferred, LiMO ₂ (M is the same as above), LiM ₂ O ₄ (M is the same as above), Li ₂ MO ₃ (M is the same as above) and Li ₄ M ₅ O ₁₂ (M is the same as above) is more preferred.

When the fluorine-containing lithium composite transition metal oxide particles do not have a desired particle size, it is preferable to pulverize or classify the fluorine-containing lithium composite transition metal oxide particles, if necessary.

The particle size of the fluorine-containing lithium composite transition metal oxide particles is preferably 100 nm to 100 μm, more preferably 100 nm to 100 μm, from the viewpoint of improving operability during electrode fabrication and increasing the electrochemical reaction field and increasing the electrode density. It is 1 to 50 μm, more preferably 3 to 30 μm, and even more preferably 4 to 10 μm.

[Active material for non-aqueous electrolyte secondary batteries]
The active material for a non-aqueous electrolyte secondary battery of the present invention is characterized by containing the fluorine-containing lithium composite transition metal oxide particles. Since the active material for a non-aqueous electrolyte secondary battery of the present invention contains the fluorine-containing lithium composite transition metal oxide particles, lithium ions can be smoothly moved during the charge / discharge operation, and the charge / discharge capacity can be increased. Is large and has excellent cycle characteristics.

The active material includes a positive electrode active material and a negative electrode active material, and the fluorine-containing lithium composite transition metal oxide particles can be suitably used for any of the active materials. Among these, the fluorine-containing lithium composite transition metal oxide particles can be suitably used as a positive electrode active material.

Since the content of the fluorine-containing lithium composite transition metal oxide particles in the active material for the non-aqueous electrolyte secondary battery of the present invention varies depending on the type of the non-aqueous electrolyte secondary battery and the like, it cannot be unconditionally determined. It is preferable to make an appropriate determination according to the target non-aqueous electrolyte secondary battery or the like. The active material for a non-aqueous electrolyte secondary battery of the present invention may be composed of only the fluorine-containing lithium composite transition metal oxide particles, and particles for other active materials may be used as long as the object of the present invention is not impaired. It may be included.

[Electrodes for non-aqueous electrolyte secondary batteries]
The electrode for a non-aqueous electrolyte secondary battery of the present invention is characterized by containing the active material particles for the non-aqueous electrolyte secondary battery. Since the active material for the non-aqueous electrolyte secondary battery of the present invention contains the active material particles for the non-aqueous electrolyte secondary battery, lithium ions can be smoothly moved during the charge / discharge operation, and the charge / discharge can be performed. It has a large capacity and excellent cycle characteristics.

The electrode for a non-aqueous electrolyte secondary battery of the present invention can be used for both a positive electrode for a non-aqueous electrolyte secondary battery and a negative electrode for a non-aqueous electrolyte secondary battery.

Since the positive electrode for a non-aqueous electrolyte secondary battery containing the active material particles for the non-aqueous electrolyte secondary battery contains the active material particles for the non-aqueous electrolyte secondary battery, lithium ions can be smoothly charged and discharged. Since it can be moved to, it has a large charge / discharge capacity and excellent cycle characteristics.

For the positive electrode for a non-aqueous electrolyte secondary battery, for example, the positive electrode active material for a non-aqueous electrolyte secondary battery, a conductive agent and a binder are mixed, and the obtained paste is applied to a current collector, dried and required. Can be obtained by pressing with.

The conductive agent is not particularly limited as long as it is an electronically conductive material that does not cause a chemical change in the battery. Examples of the conductive agent include natural graphite such as scaly graphite, graphite such as artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; carbon fiber, carbon nanotube, and the like. Conductive fibers made of metal fibers; metal powders such as copper, nickel, aluminum and silver; conductive whiskers such as zinc oxide and potassium titanate; organic conductive materials such as polyphenylene derivatives, etc. Is not limited to such examples. Each of these conductive agents may be used alone, or two or more kinds may be arbitrarily mixed and used as long as the object of the present invention is not impaired. Among these conductive agents, acetylene black and nickel are preferable.

The amount of the conductive agent per 100 parts by mass of the positive electrode active material for a non-aqueous electrolyte secondary battery is not particularly limited, but is usually preferably 0.5 to 10 parts by mass, and more preferably 2 to 5 parts by mass.

Specific examples of the binder include polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-perfluoro. Alkyl vinyl ether copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoro Propylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoro Examples thereof include a water-soluble polymer compound such as an ethylene copolymer, carboxymethyl cellulose and hydroxypropyl methyl cellulose, and rubber such as styrene-butadiene rubber, but the present invention is not limited to such examples. These binders may be used alone or in combination of two or more as long as the object of the present invention is not impaired. Among these binders, polyvinylidene fluoride and polytetrafluoroethylene are preferable.

The amount of the binder per 100 parts by mass of the positive electrode active material for a non-aqueous electrolyte secondary battery is not particularly limited, but is usually preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass.

The paste obtained by mixing the positive electrode active material for a non-aqueous electrolyte secondary battery, a conductive agent and a binder is applied to a current collector.

The current collector is not particularly limited as long as it is an electron conductor that does not easily undergo a chemical change in the battery. As the material constituting the current collector, for example, aluminum, aluminum alloy, stainless steel, nickel, titanium, carbon, etc., and carbon, nickel, titanium, or silver are adhered to the surface of a plate made of aluminum or stainless steel. Examples thereof include, but the present invention is not limited to such examples. Among the materials constituting the current collector, aluminum and an aluminum alloy are preferable.

If necessary, the surface of the current collector may be oxidized, or unevenness may be formed on the surface of the current collector by surface treatment.

The shape of the current collector may be any shape that is generally used for batteries. Specific examples of the shape of the current collector include foils, films, sheets, nets, laths, porous bodies, foams, fibers, woven fabrics, non-woven fabrics, etc., but the present invention is limited to such examples. It's not something. The thickness of the current collector is not particularly limited, but is usually preferably about 1 to 50 μm.

Next, the current collector coated with the paste is dried by a conventional method and pressed if necessary to obtain a positive electrode for a non-aqueous electrolyte secondary battery.

The electrode density, which is the density of the coating layer on the current collector to which the paste is applied, dried, and pressed if necessary, is not particularly limited, but is usually preferably about 1 to 4 g / mL.

Since the negative electrode for a non-aqueous electrolyte secondary battery containing the active material particles for the non-aqueous electrolyte secondary battery contains the active material particles for the non-aqueous electrolyte secondary battery, lithium ions can be smoothly charged and discharged. Since it can be moved to, it has a large charge / discharge capacity and excellent cycle characteristics.

The negative electrode for a non-aqueous electrolyte secondary battery is, for example, a mixture of the negative electrode active material for a non-aqueous electrolyte secondary battery, a conductive agent and a binder, and the obtained paste is applied to a current collector, dried and required. Can be obtained by pressing with.

The conductive agent is not particularly limited as long as it is an electronically conductive material that does not cause a chemical change in the battery. Examples of the conductive agent include natural graphite such as scaly graphite, graphite such as artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; carbon fiber, carbon nanotube, and the like. Conductive fibers such as metal fibers; powders of metals such as copper, nickel, aluminum and silver; conductive whiskers such as zinc oxide and potassium titanate; organic conductive materials such as polyphenylene derivatives, etc. , Not limited to such examples. Each of these conductive agents may be used alone, or two or more kinds may be arbitrarily mixed and used as long as the object of the present invention is not impaired. Among these conductive agents, acetylene black and nickel are preferable.

The amount of the conductive agent per 100 parts by mass of the negative electrode active material for a non-aqueous electrolyte secondary battery is not particularly limited, but is usually preferably 0 to 30 parts by mass, more preferably 1 to 20 parts by mass, and further preferably 2 to 2 to 20 parts by mass. It is 10 parts by mass.

Specific examples of the binder include polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-perfluoro. Alkyl vinyl ether copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polychlorotrifluoroethylene, vinylidene fluoride-pentafluoro Propylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoro Examples thereof include a water-soluble polymer compound such as an ethylene copolymer, carboxymethyl cellulose and hydroxypropyl methyl cellulose, and styrene-butadiene rubber, but the present invention is not limited to such examples. These binders may be used alone or in combination of two or more as long as the object of the present invention is not impaired. Among these binders, polyvinylidene fluoride and polytetrafluoroethylene are preferable.

The amount of the binder per 100 parts by mass of the negative electrode active material for a non-aqueous electrolyte secondary battery is not particularly limited, but is usually preferably 0.5 to 30 parts by mass, and more preferably 1 to 5 parts by mass.

The paste obtained by mixing the negative electrode active material for a non-aqueous electrolyte secondary battery, the conductive agent and the binder is applied to a current collector.

The current collector is not particularly limited as long as it is an electron conductor that does not easily undergo a chemical change in the battery. Materials that make up the current collector include, for example, copper, aluminum, aluminum alloys, stainless steel, nickel, titanium, carbon, etc., and carbon, nickel, titanium, or silver adheres to the surface of a plate made of aluminum or stainless steel. However, the present invention is not limited to such an example. Among the materials constituting these current collectors, copper, aluminum and aluminum alloys are preferable.

If necessary, the surface of the current collector may be oxidized, or unevenness may be formed on the surface of the current collector by surface treatment.

The shape of the current collector may be any shape that is generally used for batteries. Specific examples of the shape of the current collector include foil, film, sheet, net, lath, porous body, foam, fiber, woven fabric, non-woven fabric and the like. The thickness of the current collector is not particularly limited, but is usually preferably about 1 to 50 μm.

Next, the current collector coated with the paste is dried by a conventional method and pressed if necessary to obtain a negative electrode for a non-aqueous electrolyte secondary battery.

The electrode density, which is the density of the coating layer on the current collector to which the paste is applied, dried, and pressed if necessary, is not particularly limited, but is usually preferably about 1 to 4 g / mL.

[Non-water electrolyte secondary battery]
The non-aqueous electrolyte secondary battery of the present invention is characterized by having the electrode for the non-aqueous electrolyte secondary battery. A positive electrode, a negative electrode, a separator and an electrolyte are used in the non-aqueous electrolyte secondary battery of the present invention. As the positive electrode and / or the negative electrode, the positive electrode for a non-aqueous electrolyte secondary battery and / or the negative electrode for the non-aqueous electrolyte secondary battery can be used. Therefore, the non-aqueous electrolyte secondary battery of the present invention has at least one of the positive electrode for the non-aqueous electrolyte secondary battery and the negative electrode for the non-aqueous electrolyte secondary battery. The reliability of the non-aqueous electrolyte secondary battery and the fact that the positive electrode of the non-aqueous electrolyte secondary battery of the present invention is the positive electrode for the non-aqueous electrolyte secondary battery and the negative electrode is the negative electrode for the non-aqueous electrolyte secondary battery It is preferable from the viewpoint of improving safety.

In the non-aqueous electrolyte secondary battery of the present invention, when the negative electrode for the non-aqueous electrolyte secondary battery is used as the negative electrode, the positive electrode may be the positive electrode for the non-aqueous electrolyte secondary battery, and another positive electrode may be used. May be. Examples of the other positive electrode include a positive electrode in which a compound such as lithium iron phosphate, lithium iron fluoride, lithium iron silicate, and lithium iron borate is used as an active material. , Is not limited to such examples.

In the non-aqueous electrolyte secondary battery of the present invention, when the positive electrode for a non-aqueous electrolyte secondary battery is used as the positive electrode, the negative electrode may be the negative electrode for the non-aqueous electrolyte secondary battery, and another negative electrode may be used. May be. The negative electrode material used for the other negative electrode may be, for example, a compound capable of storing or releasing lithium ions such as lithium, a lithium alloy, an intermetallic compound, and a carbon material. Each of these negative electrode materials may be used alone, or may be used in any combination as long as the object of the present invention is not impaired.

Examples of the lithium alloy include Li-Al alloys, Li—Al—Mn alloys, Li—Al—Mg alloys, Li—Al—Sn alloys, Li—Al—In alloys, and Li—Al—Cd. Examples thereof include based alloys, Li-Al-Te based alloys, Li-Ga based alloys, Li-Cd based alloys, Li-In based alloys, Li-Pb based alloys, Li-Bi based alloys, Li-Mg based alloys and the like. However, the present invention is not limited to such examples. These lithium alloys may be used alone or in combination of two or more as long as the object of the present invention is not impaired. The lithium content in the lithium alloy is preferably 10% by mass or more.

Examples of the intermetallic compound include a compound of a transition metal and silicon, a compound of a transition metal and tin, and the like, but the present invention is not limited to these examples. These intermetallic compounds may be used alone or in combination of two or more as long as the object of the present invention is not impaired.

Examples of the carbon material include carbon fibers such as polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, cellulose-based carbon fiber, and vapor-growth carbon-based carbon fiber, coke, thermally decomposed carbon, natural graphite, artificial graphite, and mesocarbon micro. Examples thereof include beads, graphitized mesophase globules, vapor-grown carbon, glassy carbon, polyamorphous carbon, and the like, but the present invention is not limited to these examples. These carbon materials may be used alone or in combination of two or more as long as the object of the present invention is not impaired.

The separator is a microporous thin film having high ion permeability and mechanical strength, such as polypropylene, olefin polymer such as polyethylene, sheet made of glass fiber, non-woven fabric, etc., and insulating property, organic solvent resistance and hydrophobicity. Is preferable. The pore size of the separator is preferably about 0.1 to 1 μm. The thickness of the separator is preferably about 5 to 100 μm. The porosity of the separator is appropriately determined depending on the permeability of ions and the like, but is generally preferably about 30 to 80%.

The electrolytic solution is obtained by dissolving the electrolyte in an organic solvent. Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate; acyclic carbonates such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate and dipropyl carbonate; methyl formate, methyl acetate and propionic acid. Alibo carboxylic acid esters such as methyl and ethyl propionate; γ-lactones such as γ-butyrolactone; acyclic ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane and ethoxymethoxyethane; tetrahydrofuran, 2- Cyclic ethers such as methyl tetrahydrofuran; dimethylsulfoxide, formamide, acetamide, dimethylformamide, dioxolane, dioxolane derivatives, acetonitrile, propylnitrile, nitromethane, ethyl monoglime, phosphate triester, trimethoxymethane, sulfolane, methylsulfolane, 1,3 -Dimethyl-2-imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, 1,3-propanesartone, anisole, dimethylsulfoxide, N-methylpyrrolidone and the like can be mentioned. , Not limited to such examples. These organic solvents may be used alone or in combination of two or more as long as the object of the present invention is not impaired.

The electrolyte is preferably a non-aqueous electrolyte. Examples of the non-aqueous electrolyte include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAlCl ₄ , LiSbF ₆ , LiSCN, LiCl, LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , Li (CF ₃ SO ₂ ) ₂ , LiAsF ₆ , and LiN. (CF ₃ SO ₂ ) ₂ , LiB ₁₀ Cl ₁₀ , lower aliphatic carboxylate lithium, LiCl, LiBr, LiI, chloroborane lithium, lithium tetraphenylborate, LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ ) , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), etc. Not limited. Each of these electrolytes may be used alone, or two or more of them may be used in combination as long as the object of the present invention is not impaired.

The amount of the electrolyte per liter of the organic solvent is not particularly limited, but is preferably 0.2 to 2 mol, more preferably 0.5 to 1.5 mol.

From the viewpoint of improving battery characteristics, the electrolytic solution contains vinylene carbonate, fluoroethylene carbonate, biphenyl, cyclohexylbenzene, propanesulton, 2-methylfuran, thiophene, pyrrole, aniline, crown ether, pyridine, triethylphosphite, and tri. Ethanolamine, cyclic ether, ethylenediamine, n-glime, hexaphosphate triamide, nitrobenzene derivative and the like may be dissolved.

Further, the electrolytic solution may be imparted with nonflammability. Nonflammability can be imparted by, for example, containing a halogen-containing organic solvent such as carbon tetrachloride or ethylene trifluoride in the electrolytic solution. Further, carbon dioxide gas may be blown into the electrolytic solution from the viewpoint of improving the storage stability of the electrolytic solution at high temperatures.

The electrolytic solution can usually be used by impregnating a separator such as a porous polymer, a glass filter, or a non-woven fabric.

Examples of the shape of the battery include a coin type, a button type, a sheet type, a cylindrical type, a flat type, a square type, and the like, but the present invention is not limited to such an embodiment. When the shape of the battery is coin-shaped or button-shaped, it can be used by molding the positive electrode material and the negative electrode material into pellets. The thickness and diameter of the pellets may be appropriately determined according to the use of the battery and the like. Further, the non-aqueous electrolyte secondary battery of the present invention may be a soft package battery (laminated cell or pouch cell) having a multilayer laminated film on which a metal is vapor-deposited as an exterior body.

The non-aqueous electrolyte secondary battery of the present invention configured as described above is reliable as a battery because it uses fluorine-containing lithium composite transition metal oxide particles having a large charge / discharge capacity and excellent cycle characteristics. Excellent in sex.

The non-aqueous electrolyte secondary battery of the present invention has a large charge / discharge capacity and excellent cycle characteristics. Therefore, for example, portable electronic devices such as mobile phones and notebook computers, power supply systems, electric vehicles, electric bicycles, and transport vehicles. It can be used in a wide range of applications such as vehicles and power supplies for various devices.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to such examples.

Example 1
(1) Preparation of Fluorine-Containing Nickel Hydroxide Particles 1 g of nickel hydroxide particles (particle size: about 6 μm) is placed in a nickel reaction vessel, spread so that the overlap between the nickel hydroxide particles is as small as possible, and then this is performed. The reaction vessel was placed in a 150 mL stainless steel (SUS316L) reaction vessel and connected to a fluorine gas introduction line. After confirming the airtightness of the connection between the reaction vessel and the fluorine gas introduction line, the pressure inside the reaction vessel was reduced so that the pressure was 1 Pa or less.

Next, the temperature inside the reaction vessel was adjusted to 25 ° C., and fluorine gas was introduced into the reaction vessel until the absolute pressure reached 6.67 kPa, and the mixture was held for 1 hour. Then, fluorine gas was adsorbed on activated alumina, and argon gas was introduced into the reaction vessel until the pressure reached atmospheric pressure. The reaction vessel was separated from the fluorine gas introduction line, the reaction vessel was opened in an argon gas atmosphere, and fluorine-containing nickel hydroxide particles were taken out as fluorine-containing transition metal hydroxide particles. The fluorine content in the obtained fluorine-containing nickel hydroxide particles was 2.3% by mass.

In each Example and each Comparative Example, the fluorine content in the fluorine-containing nickel hydroxide particles is an energy dispersion type characteristic linked to an electric field radiation scanning electron microscope [manufactured by ZEISS, trade name: Ultra plus]. Using an X-ray spectroscopic analyzer [Bruker AXS, trade name: QUANTAX Espirit 1.9], the analysis software [Bruker Nano GmbH] is used from the generated intensity of characteristic X-rays measured under electron beam irradiation with an acceleration voltage of 5 kV. Obtained using.

(2) Preparation of Fluorine-Containing Nickel Oxide Particles The fluorine-containing nickel hydroxide particles obtained above were pressed to prepare pellets (diameter: 20 mm, height: 5 mm), and the obtained pellets were placed in an electric furnace. The mixture was charged, heated to 750 ° C. at a heating rate of 5 ° C./min, and maintained at the same temperature for 6 hours to obtain fluorine-containing nickel oxide particles as fluorine-containing transition metal oxide particles.

(3) Preparation of Fluorine-Containing Lithium Composite Nickel Oxide Particles Li / Ni (molar ratio) of the fluorine-containing nickel oxide particles obtained above and lithium carbonate particles (particle size: about 4 μm) is 1.05 / 1.00. By mixing in air at 25 ° C. for 1 hour, a mixture having a uniform composition was obtained. The obtained mixture is pressed to prepare pellets (diameter: 20 mm, height: 5 mm), and the obtained pellets are placed in an electric furnace and heated to 700 ° C. at a heating rate of 2 ° C./min. By keeping the same temperature for 20 hours, fluorine-containing lithium composite nickel oxide particles were obtained as fluorine-containing lithium composite transition metal oxide particles.

(4) Preparation of Electrode The fluorine-containing lithium composite nickel oxide particles obtained above were used as an active material for a non-aqueous electrolyte secondary battery.

Fluorine-containing lithium composite nickel oxide particles, a conductive material (acetylene black), and a binder (polyvinylidene fluoride) were mixed at a mass ratio of 8: 1: 1, and then a solvent (N-methyl-) was added to 1 g of the obtained mixture. 2-Pyrrolidone) 0.5 mL was added, stirred with a ball mill, and the obtained positive electrode material was applied to an aluminum sheet with a doctor blade having an interval of 0.35 mm.

The aluminum sheet was placed in a dryer, dried at a temperature of 120 ° C. for 1 hour, and then removed from the dryer. A circular sample having a diameter of 16 mm was cut from the aluminum sheet, pressed against the sample at a pressure of 2 MPa for 10 minutes, and then dried under reduced pressure for 12 hours to obtain an electrode.

(5) Preparation of non-aqueous electrolyte secondary battery The electrode obtained above was used as a positive electrode plate. A polyethylene porous film separator (thickness: 25 μm, porosity: 45%) is interposed between the positive electrode plate and the counter electrode plate (lithium metal) in an argon gas atmosphere to form the electrode layer of the positive electrode plate and the counter electrode plate. The obtained laminates were placed in a tomcell [manufactured by Nippon Tomsel Co., Ltd., trade name: TOMCELL (registered trademark)].

Next, LiPF ₆ was dissolved in a solution in which 50 parts by volume of propylene carbonate and 50 parts by volume of dimethyl ether were mixed in an argon gas atmosphere to prepare a non-aqueous electrolyte solution having a concentration of LiPF ₆ of 1 mol / L. A non-aqueous electrolyte secondary battery was produced by putting this non-aqueous electrolyte solution into the tom cell and sealing the tom cell.

The non-aqueous electrolyte secondary battery is charged with a constant current of 0.1 C until the final voltage reaches 4.3 V, and then the non-aqueous electrolyte secondary battery is discharged at 0.1 C until the final voltage reaches 3.0 V. rice field. The discharge capacity in the third cycle in which the change in discharge capacity due to the charge / discharge cycle became sufficiently small was defined as the initial discharge capacity.

For reference, the same operation as described in "(3) Preparation of fluorine-containing lithium composite nickel oxide particles" is performed except that nickel oxide particles are used instead of the fluorine-containing nickel oxide particles. Lithium composite nickel oxide particles were obtained.

(6) Evaluation of Physical Properties Nickel hydroxide particles used as a raw material, fluorine-containing nickel hydroxide particles obtained in Example 1, fluorine-containing nickel oxide particles obtained in Example 1, nickel oxide particles, Example 1 The physical properties of the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles obtained in the above method were investigated based on the following methods.

[Powder X-ray diffraction (XRD)]
The measurement conditions for investigating powder X-ray diffraction are as follows.
[Device used]
-Powder X-ray diffractometer [manufactured by Shimadzu Corporation, product number: XRD-6100]
[Measurement condition]
・ Target: Cu
・ Voltage: 30kV
・ Current: 20mA
-Scale factor: 1 to 4 kcps
・ Time constant: 0.4sec
・ Scan speed: 2 ° / min
・ 2θ: 10-80 °

[Observation with scanning electron microscope (SEM)]
[Device used]
-Scanning electron microscope [manufactured by Hitachi, Ltd., product number: S-3400N or ZEISS, trade name: Ultra plus]
[Measurement condition]
-Magnification: 1900x, 2300x, 4700x or 8000x-Acceleration voltage: 15.0kV (when using the S-3400N), 3.00kV (when using the Ultra plus)

[X-ray Photoelectron Spectroscopy (XPS)]
The measurement conditions for X-ray photoelectron analysis are as follows.
[Device used]
-Photoelectron analyzer [manufactured by JEOL Ltd., product number: JSP-9010MC]
[Measurement condition]
・ Elements to be analyzed: ⁴ Be ～ ⁹² U
・ X-ray source: Mg
・ Power output: 600W (12kV, 50mA)
-Energy analyzer: Center starting radius: 100 mm, electrostatic hemispherical binding energy range: 0 to 1458 eV
Ultimate vacuum measurement: 10 ^-8 Pa order

[Auger electron spectroscopy (AES)]
[Device used]
・ Field Emission Auger Microprobe [manufactured by JEOL Ltd., product number: JAMP-9500F]
[Measurement condition]
・ Electron beam output: 10kV, 10nA
・ Elements to be analyzed: ³ Li ～ ⁹² U
Resolution: M4
-Collection time (Dwell time): 50 to 150 ms
・ Number of integrations: 3 to 25 times ・ Measurement range: 0 to 2500 eV

(7) Evaluation results of physical properties [Contrast between nickel hydroxide and fluorine-containing nickel hydroxide]
A. Powder X-ray Diffraction The measurement results of powder X-ray diffraction of nickel hydroxide and fluorine-containing nickel hydroxide are shown in FIG. In FIG. 1, A shows the measurement result of powder X-ray diffraction of fluorine-containing nickel hydroxide, and B shows the measurement result of powder X-ray diffraction of nickel hydroxide.

From the results shown in FIG. 1, since no peak movement, appearance and disappearance of new peaks were observed in nickel hydroxide and fluorine-containing nickel hydroxide, there was a large change in the crystal structure and lattice constant of both. It is considered that there is no such thing.

B. Observation with a scanning electron microscope (SEM) A scanning electron micrograph of nickel hydroxide and fluorine-containing nickel hydroxide is shown in FIG.

In FIG. 2, (a) is a scanning electron micrograph of nickel hydroxide, and (b) is a scanning electron micrograph of fluorine-containing nickel hydroxide. From the results shown in FIG. 2, it can be seen that there is no change in the surface shape and morphology of nickel hydroxide and fluorine-containing nickel hydroxide.

C. X-ray photoelectron spectroscopy (XPS)
FIG. 3 shows the measurement results of X-ray photoelectron spectroscopy of nickel hydroxide and fluorine-containing nickel hydroxide. In FIG. 3, A shows the measurement result of X-ray photoelectron spectroscopy of fluorine-containing nickel hydroxide, and B shows the measurement result of X-ray photoelectron spectroscopy of nickel hydroxide.

From the results shown in FIG. 3, since the nickel hydroxide does not have a fluorine-based peak, the fluorine-containing nickel hydroxide has a fluorine-based peak, so that the fluorine-containing hydroxide is present. It is considered that fluorine is bonded to nickel.

D. Auger electron spectroscopy (AES)
FIG. 4 shows the measurement results of Auger electron spectroscopy of fluorine-containing nickel hydroxide particles. In FIG. 4, the distance indicates the distance from the surface of the fluorine-containing nickel hydroxide particles. Further, in FIG. 4, Ni indicates the measurement result of nickel, O indicates the measurement result of oxygen, and F indicates the measurement result of fluorine.

From the results shown in FIG. 4, it can be seen that fluorine is present even inside the particles of the fluorine-containing nickel hydroxide. Further, since fluorine does not permeate into the place where the grain boundary does not exist inside the fluorine-containing nickel hydroxide particles, fluorine exists at the boundary between the crystallites constituting the fluorine-containing nickel hydroxide particles. You can see that.

[Contrast between fluorine-containing nickel oxide particles and nickel oxide particles]
A. Powder X-ray Diffraction The measurement results of powder X-ray diffraction of fluorine-containing nickel oxide particles and nickel oxide particles are shown in FIG. In FIG. 5, A shows the measurement result of powder X-ray diffraction of fluorine-containing nickel oxide particles, and B shows the measurement result of powder X-ray diffraction of nickel oxide particles.

From the results shown in FIG. 5, since no peak movement, appearance and disappearance of new peaks were observed in the fluorine-containing nickel oxide particles and nickel oxide particles, there was a large change in the crystal structure and lattice constant of both. It is considered that there is no such thing.

B. Observation with a scanning electron microscope (SEM) A scanning electron micrograph of fluorine-containing nickel oxide particles and nickel oxide particles is shown in FIG.

In FIG. 6, (a) is a scanning electron micrograph of nickel oxide particles, and (b) is a scanning electron micrograph of fluorine-containing nickel oxide particles. From the results shown in FIG. 6, it can be seen that there is no change in the surface shape and morphology of the fluorine-containing nickel oxide particles and the nickel oxide particles.

C. X-ray photoelectron spectroscopy (XPS)
FIG. 7 shows the measurement results of X-ray photoelectron analysis of fluorine-containing nickel oxide particles and nickel oxide particles. In FIG. 7, A shows the measurement result of X-ray photoelectron spectroscopy of fluorine-containing nickel oxide particles, and B shows the measurement result of X-ray photoelectron spectroscopy of nickel oxide particles.

From the results shown in FIG. 7, since the nickel oxide particles do not have a fluorine-based peak, while the fluorine-containing nickel oxide particles have a fluorine-based peak, the fluorine-containing nickel oxide has a peak. It is considered that fluorine is bound to the particles.

D. Auger electron spectroscopy (AES)
FIG. 8 shows the measurement results of Auger electron spectroscopy of fluorine-containing nickel oxide particles. In FIG. 8, the distance indicates the distance from the surface of the fluorine-containing nickel oxide particles. Further, in FIG. 8, Ni indicates the measurement result of nickel, O indicates the measurement result of oxygen, C indicates the measurement result of carbon, and F indicates the measurement result of fluorine.

From the results shown in FIG. 8, it can be seen that fluorine is present even inside the fluorine-containing nickel oxide particles. Further, since fluorine does not permeate into the place where the grain boundary does not exist inside the fluorine-containing nickel oxide particles, it is necessary that fluorine exists at the boundary between the crystallites constituting the fluorine-containing nickel oxide particles. Recognize.

[Comparison between fluorine-containing lithium composite nickel oxide particles and lithium composite nickel oxide particles]
A. Powder X-ray Diffraction The measurement results of powder X-ray diffraction of fluorine-containing lithium composite nickel oxide particles and lithium composite nickel oxide particles are shown in FIG. In FIG. 9, A shows the measurement result of powder X-ray diffraction of fluorine-containing lithium composite nickel oxide particles, and B shows the measurement result of powder X-ray diffraction of lithium composite nickel oxide particles.

From the results shown in FIG. 9, since no peak movement, appearance and disappearance of new peaks were observed in the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles, the crystal structures and lattice constants of both were observed. It is considered that there is no major change in.

B. Observation with a scanning electron microscope (SEM) FIG. 10 shows scanning electron micrographs of fluorine-containing lithium composite nickel oxide particles and lithium composite nickel oxide particles.

In FIG. 10, (a) is a scanning electron micrograph of fluorine-containing lithium composite nickel oxide particles, and (b) is a scanning electron micrograph of lithium composite nickel oxide particles.

From the results shown in FIG. 10, among the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles, the fluorine-containing lithium composite nickel oxide particles have a relatively small primary particle diameter and have rounded edges. You can see that it is tinged.

C. X-ray photoelectron spectroscopy (XPS)
FIG. 11 shows the measurement results of X-ray photoelectron spectroscopy of the fluorine-containing lithium composite nickel oxide particles and the lithium composite nickel oxide particles. In FIG. 11, NT is the measurement result of X-ray photoelectron analysis of lithium composite nickel oxide particles, and 0s, 5s, 10s, 15s, and 20s are, respectively, argon etching at 0 seconds, 5 seconds, 10 seconds, 15 seconds, and 20s, respectively. The measurement result of the X-ray photoelectron analysis of the fluorine-containing lithium composite nickel oxide particles after a second is shown.

From the results shown in FIG. 11, since the lithium composite nickel oxide particles do not have a fluorine-based peak, the fluorine-containing lithium composite nickel oxide particles have a fluorine-based peak. It is considered that fluorine is bound to the fluorine-containing lithium composite nickel oxide particles.

Further, FIG. 11 shows the result of investigating the influence of the fluorine-based peak due to argon etching, and a fluorine-based peak is observed from the initial stage of no etching to 10 seconds of argon etching, but the argon etching time is 15 seconds. Since no peak based on fluorine is observed in the above, it can be seen that fluorine is present near the surface of the fluorine-containing lithium composite nickel oxide particles.

D. Evaluation of Electrical Characteristics Using fluorine-containing lithium composite nickel oxide particles and lithium composite nickel oxide particles, the charge / discharge rate was adjusted to 0.1 C and the charge-discharge curve was investigated. The results are shown in FIG. In FIG. 12, (a) shows a charge curve and (b) shows a discharge curve.

From the results shown in FIG. 12, it can be seen that the fluorine-containing lithium composite nickel oxide particles (reference numeral A in the figure) have a larger charge / discharge capacity than the lithium composite nickel oxide particles (reference numeral B in the figure).

Using fluorine-containing lithium composite nickel oxide particles and lithium composite nickel oxide particles, adjust the charge / discharge rate to 1C, and change the number of cycles of discharge capacity in charge condition: 4.3V cut and discharge condition: 3.0V cut (cycle). (Characteristics) was investigated. The result is shown in FIG. In FIG. 13, A shows the result of examining the cycle characteristics of the fluorine-containing lithium composite nickel oxide particles, and B shows the result of examining the cycle characteristics of the lithium composite nickel oxide particles.

From the results shown in FIG. 13, it can be seen that the fluorine-containing lithium composite nickel oxide particles are superior in cycle characteristics to the fluorine-containing lithium composite nickel oxide particles. The reason why the fluorine-containing lithium composite nickel oxide particles are superior in cycle characteristics to the fluorine-containing lithium composite nickel oxide particles is not clear, but probably the boundary between the crystals of the fluorine-containing lithium composite nickel oxide particles. Fluorine present in the fluorine smoothly promoted the insertion and desorption of lithium ions, and the fluorine present in the fluorine-containing lithium composite nickel oxide particles improved the affinity between the electrolytic solution and the fluorine-containing lithium composite nickel oxide particles. It is thought that it is based on what was done.

Example 2
After 0.1 g of nickel hydroxide particles (particle size: 6 μm) are placed in a nickel reaction vessel and expanded so that the overlap between the particles is as small as possible, the reaction vessel is expanded into a 150 mL stainless steel (SUS316L) reaction. It was installed inside the container and connected to the fluorine gas introduction line. After confirming the confidentiality of the connection part, the pressure was reduced to 1 Pa or less.

Next, the temperature inside the reaction vessel was adjusted to 25 ° C., and fluorine gas was introduced into the reaction vessel until the absolute pressure reached 1.3 kPa, and the mixture was held for 1 hour. Then, the fluorine gas was exhausted and the argon gas was introduced into the reaction vessel until the atmospheric pressure was reached. The reaction vessel was separated from the fluorine gas introduction line, the vessel was opened in an argon gas atmosphere, and the fluorine-containing nickel hydroxide particles were taken out. The fluorine content in the obtained fluorine-containing nickel hydroxide particles was 1.44% by mass.

Example 3
After 0.1 g of nickel hydroxide particles (particle size: 6 μm) are placed in a nickel reaction vessel and expanded so that the overlap between the particles is as small as possible, the reaction vessel is expanded into a 150 mL stainless steel (SUS316L) reaction. It was installed in a container and connected to a fluorine gas introduction line. After confirming the confidentiality of the connection part, the pressure was reduced to 1 Pa or less.

Next, the temperature inside the reaction vessel was adjusted to 25 ° C., and fluorine gas was introduced into the reaction vessel until the absolute pressure reached 4.0 kPa, and the mixture was held for 1 hour. Then, the fluorine gas was exhausted and the argon gas was introduced into the reaction vessel until the pressure reached 1 atm. The reaction vessel was separated from the fluorine gas introduction line, the vessel was opened in an argon gas atmosphere, and the fluorine-containing nickel hydroxide particles were taken out. The fluorine content in the obtained fluorine-containing nickel hydroxide particles was 2.89% by mass.

Example 4
After 0.1 g of nickel hydroxide particles (particle size: 6 μm) are placed in a nickel reaction vessel and expanded so that the overlap between the particles is as small as possible, the reaction vessel is expanded into a 150 mL stainless steel (SUS316L) reaction. It was installed in a container and connected to a fluorine gas introduction line. After confirming the confidentiality of the connection part, the pressure was reduced to 1 Pa or less.

Next, the temperature inside the reaction vessel was adjusted to 25 ° C., and fluorine gas was introduced into the reaction vessel until the absolute pressure reached 6.7 kPa, and the mixture was held for 1 hour. Then, the fluorine gas was exhausted and the argon gas was introduced into the reaction vessel until the pressure reached 1 atm. The reaction vessel was separated from the fluorine gas introduction line, the vessel was opened in an atmosphere of argon gas, and nickel hydroxide particles were taken out. The fluorine content in the obtained nickel hydroxide particles was 4.55% by mass.

Example 5
After 0.1 g of nickel hydroxide particles (particle size: 6 μm) are placed in a nickel reaction vessel and expanded so that the overlap between the particles is as small as possible, the reaction vessel is expanded into a 150 mL stainless steel (SUS316L) reaction. It was installed in a container and connected to a fluorine gas introduction line. After confirming the confidentiality of the connection part, the pressure was reduced to 1 Pa or less.

Next, the temperature inside the reaction vessel was adjusted to 25 ° C., and fluorine gas was introduced into the reaction vessel until the absolute pressure reached 9.3 kPa, and the mixture was held for 1 hour. Then, the fluorine gas was exhausted and the argon gas was introduced into the reaction vessel until the pressure reached 1 atm. The reaction vessel was separated from the fluorine gas introduction line, the vessel was opened in an argon gas atmosphere, and the fluorine-containing nickel hydroxide particles were taken out. The fluorine content in the obtained fluorine-containing nickel hydroxide particles was 5.17% by mass.

From the results of Examples 2 to 5, it can be seen that the amount of fluorine present in the obtained fluorine-containing nickel hydroxide particles increases as the pressure of the fluorine gas when the nickel hydroxide particles are treated with fluorine increases. ..

[Observation with scanning electron microscope (SEM)]
The appearances of the fluorine-containing nickel hydroxide particles obtained in Examples 2 to 5 and the nickel hydroxide particles having no fluorine on the surface were observed with a scanning electron microscope. As a result, no significant difference was observed in the appearance of the fluorine-containing nickel hydroxide particles and the nickel hydroxide particles having no fluorine on the surface.

[X-ray Photoelectron Spectroscopy (XPS)]
X-ray photoelectron spectroscopy (XPS) of the fluorine-containing nickel hydroxide particles obtained in Example 4 was performed in the same manner as in Example 1. As a result, since peaks are present in the spectrum at least around 687 eV and around 684 eV, the fluorine introduced into the nickel hydroxide particles by the contact of the nickel hydroxide particles with fluorine has at least two kinds of chemical states. One of them has an interaction with nickel having a valence close to +2, and the other one has an interaction with nickel having a higher valence. It turned out that there was.

From the above results, it can be seen that some nickel atoms are oxidized by fluorination and have a valence larger than +2.

Example 6
Fluorine-containing nickel hydroxide particles obtained in Example 4 were calcined in air at a temperature of 750 ° C. for 6 hours to prepare fluorine-containing nickel oxide particles.

Next, the fluorine-containing nickel oxide particles and the lithium carbonate particles (particle size: 4 μm) obtained above are placed in air at 25 ° C. so that the Li / Ni (molar ratio) is 1.05 / 1.00. Mixing for 1 hour gave a mixture having a uniform composition.

The mixture obtained above is pelletized in the same manner as in Example 1, dried by leaving it in air at 70 ° C., and then fired in air at a temperature of 700 ° C. for 5 hours to obtain fluorine-containing lithium. Fluorine-containing lithium composite nickel oxide particles (particle size: 21 μm, refractive index: 1.7) were obtained as the composite transition metal oxide particles.

The cut surface of the fluorine-containing lithium composite nickel oxide particles obtained above is irradiated with an electron beam having an acceleration voltage of 1 kV, and the cut surface is observed with an electric current radiation scanning electron microscope [manufactured by ZEISS, trade name: Ultra plus]. By measuring the current flowing to the ground 60 seconds after the start of irradiation, the transmitted current value flowing in the dark region is 130 pA, and the transmitted current value flowing in the bright region adjacent to the dark region is 120 pA. As shown in FIG. 14, it was confirmed that the electron beam transmissive region (dark region) has an island state and the electron beam impervious region (bright region) has a sea-island state dispersed in the sea state. ..

FIG. 14 is a scanning electron micrograph when the cut surface of the fluorine-containing lithium composite nickel oxide particles is irradiated with an electron beam.

In addition, the ratio of the area of the electron beam permeable region to the cut surface of the fluorine-containing lithium composite nickel oxide is measured using an electric field radiation scanning electron microscope [ZEISS, trade name: Ultra plus] at an acceleration voltage of 1 kV. The reflected electron image was calculated for 10 particles with the threshold value set to 50% and the areas of dark and bright areas calculated by the number of pixels, with the total area of dark and bright areas as the denominator and the area of dark areas as molecules. When the average value was calculated, it was 38%. In addition, a reflected electron image of the average diameter of the electron beam permeable region of the fluorine-containing lithium composite nickel oxide particles measured at an acceleration voltage of 1 kV using an electric field radiation scanning electron microscope [manufactured by ZEISS, trade name: Ultra plus]. 10 electron beam transmissive regions in the island state of No. were arbitrarily selected, and the sum of the short side and the long side in each selected region was divided by 2 and averaged at the 10 locations. , 40 nm.

Example 7
Fluorine-containing nickel-cobalt cobalt hydroxide manganese particles [Ni / Co / Mn (molar ratio): 5/2/3, particle size: 6 μm] obtained by the same method as in Example 4 are calcined at a temperature of 750 ° C. for 6 hours. By doing so, fluorine-containing nickel oxide cobalt-cobalt manganese particles were obtained.

The fluorine-containing nickel-cobalt oxide manganese particles and lithium carbonate particles (particle size: 4 μm) obtained above are mixed in air at 25 ° C. so that the molar ratio of Li / (Ni + Co + Mn) is 1.05 / 1.00. Mixing for 1 hour gave a mixture having a uniform composition.

Next, the mixture obtained above was dried by leaving it in air at 70 ° C., and then fired in air at a temperature of 900 ° C. for 10 hours to obtain fluorine-containing lithium composite transition metal oxide particles. Fluorine-containing lithium composite nickel-cobalt oxide manganese particles [Ni / Co / Mn (molar ratio): 5/2/3, particle diameter 5 μm, refractive index: 1.7] were obtained.

While observing the cut surface of the fluorine-containing lithium composite nickel-cobalt manganese particles obtained above with a scanning electron microscope, the cut surface is irradiated with an electron beam having an acceleration voltage of 1 kV in the same manner as in Example 6 to obtain a dark portion. The transmitted current value flowing in the region is 80 pA, the transmitted current value flowing in the bright region adjacent to the dark region is 70 pA, the electron beam transmissive region (dark region) is in an island state, and the electron beam imperviousity is impervious. It was confirmed that the region (bright region) had a sea-island state dispersed in the sea state. Further, the ratio of the area of the electron beam translucent region to the cut surface of the fluorine-containing lithium composite transition metal oxide particles was measured in the same manner as in Example 6 and found to be 45%. Moreover, when the average diameter of the electron beam easily transparent region of the fluorine-containing lithium composite transition metal oxide particles was measured in the same manner as in Example 6, it was 65 nm.

Example 8
Fluorine-containing cobalt hydroxide particles obtained by the same method as in Example 4 were calcined at a temperature of 750 ° C. for 6 hours to obtain fluorine-containing cobalt oxide particles.

By mixing the fluorine-containing cobalt oxide particles obtained above and lithium carbonate in air at 25 ° C. for 1 hour so that the Li / Co (molar ratio) is 1.05 / 1.00, a uniform composition is obtained. Was obtained. The mixture obtained above is dried by leaving it in air at 70 ° C., and then fired in air at a temperature of 900 ° C. for 20 hours to obtain fluorine-containing lithium as a fluorine-containing lithium composite transition metal oxide particle. Composite cobalt oxide particles (particle size: 5 μm, refractive index: 1.7) were obtained.

While observing the cut surface of the fluorine-containing lithium composite cobalt oxide particles obtained above with a scanning electron microscope, the cut surface is irradiated with an electron beam having an acceleration voltage of 1 kV in the same manner as in Example 6 to cover the dark region. The transmitted current value flowing is 126 pA, the transmitted current value flowing in the bright region adjacent to the dark region is 116 pA, the electron beam transmissive region (dark region) is in an island state, and the electron beam impervious region (electron beam impervious region). It was confirmed that the bright region) had a sea-island state dispersed in the sea state. Further, the ratio of the area of the electron beam permeable region to the cut surface of the fluorine-containing lithium composite transition metal oxide particles was measured in the same manner as in Example 6 and found to be 75%. Moreover, when the average diameter of the electron beam easily transparent region of the fluorine-containing lithium composite transition metal oxide particles was measured in the same manner as in Example 6, it was 80 nm.

Comparative Example 1
Except for the fact that instead of the fluorine-containing nickel hydroxide particles used in Example 4, nickel hydroxide particles not treated with the same type of fluorine as the nickel hydroxide particles used in Example 4 were used. Lithium composite nickel oxide particles were obtained in the same manner as in Example 6.

While observing the cut surface of the lithium composite nickel oxide particles with a scanning electron microscope, the cut surface was irradiated with an electron beam having an acceleration voltage of 1 kV in the same manner as in Example 6. Since it was displayed in (white to grayish white), it was confirmed that the electron beam impervious region was formed as a whole and the electron beam transmissive region was not formed.

Comparative Example 2
Except for the fact that instead of the fluorine-containing nickel-cobalt-cobalt manganese hydroxide used in Example 7, nickel-cobalt-cobalt manganese hydroxide which has not been treated with the same type of fluorine as the nickel-cobalt manganese hydroxide used in Example 7 was used. Obtained lithium composite nickel-cobalt-cobalt-manganese particles in the same manner as in Example 7.

While observing the cut surface of the lithium composite nickel-cobalt oxide manganese particles with a scanning electron microscope, the cut surface was irradiated with an electron beam having an acceleration voltage of 1 kV in the same manner as in Example 6. Since it was displayed in a partial region (white to grayish white), it was confirmed that the electron beam impervious region was formed as a whole and the electron beam transmissive region was not formed.

Comparative Example 3
Example 8 except that the fluorine-containing cobalt hydroxide used in Example 8 was replaced with cobalt hydroxide which was not treated with the same type of fluorine as the cobalt hydroxide used in Example 8. Lithium composite cobalt oxide particles were obtained in the same manner as above.

While observing the cut surface of the lithium composite cobalt oxide particles with a scanning electron microscope, the cut surface was irradiated with an electron beam having an acceleration voltage of 1 kV in the same manner as in Example 6. Since it was displayed in (white to grayish white), it was confirmed that the electron beam impervious region was formed as a whole and the electron beam transmissive region was not formed.

Experimental Example 1
The fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 and the fluorine-free lithium composite transition metal composite oxide particles obtained in Comparative Examples 1 to 3 have copper characteristic X-rays (wavelength 1. X-ray diffraction was examined by irradiating with 54 Å) and scanning at 2 ° / min with 2θ in the range of 10-85 °. An X-ray diffractometer [manufactured by Shimadzu Corporation, product number: XRD-6100] was used for the measurement of X-ray diffraction.

The (003) plane and the (104) plane of the fluorine-containing lithium composite transition metal composite oxide particles obtained in Examples 6 to 8 and the fluorine-free lithium composite transition metal composite oxide particles obtained in Comparative Examples 1 to 3 The diffraction intensity ratio [peak intensity ratio [(003) / (104)]] of the above is shown in Table 1.

From the results shown in Table 1, the peak intensity ratio of the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 was about 1.2 to 1.6, whereas the peak intensity ratio was about 1.2 to 1.6, whereas Comparative Examples 1 to 1. It can be seen that the peak intensity ratio of the fluorine-free lithium composite transition metal oxide particles obtained in No. 3 is about 1.4 to 1.6.

From the above results, the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 promoted the growth of crystals, but the growth of the primary particles was suppressed, so that crystallization was promoted. It is considered that fluorine-containing lithium composite transition metal oxide particles in which the coarsening of the primary particles is suppressed are produced.

Experimental Example 2
The charge / discharge test of the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 and the fluorine-free lithium composite transition metal oxide particles obtained in Comparative Examples 1 to 3 was carried out based on the following method. I did.

[Charging / discharging test method]
80 parts by mass of each of the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 and the fluorine-free lithium composite transition metal oxide particles obtained in Comparative Examples 1 to 3 and acetylene as a conductive agent. By mixing each component in a ratio of 10 parts by mass of black and 10 parts by mass of polyvinylidene fluoride as a binder, and further mixing and dispersing the obtained mixture in N-methyl-2-pyrrolidone as an organic solvent, Obtained a paste.

The paste obtained above is applied to an aluminum current collector sheet so that the thickness after drying is 100 μm, dried and press-rolled, and cut out to have a diameter of 16 mm to obtain a positive electrode plate. rice field.

In an argon gas atmosphere, a polyethylene porous film separator (thickness: 25 μm, porosity: 45%) is interposed between the positive electrode plate obtained above and the counter electrode plate (lithium plate) to form a positive electrode plate. The electrode layer and the counter electrode plate were overlapped with each other facing each other, and the obtained laminate was placed in Tomcell [manufactured by Nippon Tomcell Co., Ltd., trade name: TOMCELL (registered trademark)].

Next, LiPF ₆ was dissolved in a solution in which 50 parts by volume of propylene carbonate and 50 parts by volume of dimethyl ether were mixed in an argon gas atmosphere to prepare a non-aqueous electrolyte solution having a concentration of LiPF ₆ of 1 mol / L. A non-aqueous electrolyte secondary battery was produced by putting this non-aqueous electrolyte solution into the tom cell and sealing the tom cell.

The non-aqueous electrolyte secondary battery obtained above is charged with a constant current of 0.2 C until the final voltage reaches 4.3 V, and then the non-aqueous electrolyte secondary battery is charged at 0.2 C until the final voltage reaches 3.0 V. The battery was discharged. The discharge capacity in the third cycle in which the change in discharge capacity due to the charge / discharge cycle became sufficiently small was defined as the initial discharge capacity.

Table 2 shows the initial discharge capacities of the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 and the fluorine-free lithium composite transition metal oxide particles obtained in Comparative Examples 1 to 3.

From the results shown in Table 2, the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 are the fluorine-free lithium composite transition metal oxide particles obtained in Comparative Examples 1 to 3, respectively. It can be seen that the initial discharge capacity is large in comparison with.

Experimental Example 3
Using the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 and the fluorine-free lithium composite transition metal oxide particles obtained in Comparative Examples 1 to 3, 0.5C charge-0.5C After performing a test of repeating discharge, a so-called cycle test, for 50 cycles, the discharge capacity of each tom cell was examined. Table 3 shows the discharge capacity at the 50th cycle.

From the results shown in Table 3, the fluorine-containing lithium composite transition metal oxide particles obtained in Examples 6 to 8 are the fluorine-free lithium composite transition metal oxide particles obtained in Comparative Examples 1 to 3, respectively. It can be seen that the discharge capacity is maintained at a high level in comparison with.

From the above results, it can be seen that the non-aqueous electrolyte secondary battery of the present invention uses fluorine-containing lithium composite transition metal oxide particles, so that it has a large initial charge / discharge capacity and is excellent in cycle characteristics.

Claims (9)

Particles having crystallites made of a fluorine-containing lithium composite transition metal oxide having at least one transition metal selected from the group consisting of Co, Ni and Mn as the transition metal, among crystallites of a plurality of crystallites. Fluorine is present at the boundary of the electron beam, and the electron beam impervious region and the electron beam impervious region that is relatively easy to transmit electron beams with respect to the electron beam impervious region are in the sea-island state. It is formed on the cut surface of the particle, the sea state is the electron beam impervious region, the island state is the electron beam transmissive region, and the area occupied by the electron beam transmissive region on the cut surface of the particle. Fluorine-containing lithium composite transition metal oxide particles characterized by a ratio of 15 to 80%. The fluorine-containing lithium composite transition metal oxide particle according to claim 1, wherein the electron beam translucent region has an average diameter of 30 to 1000 nm. The fluorine-containing lithium composite transition metal oxide particles according to claim 1 or 2, wherein the fluorine-containing lithium composite transition metal oxide particles have a particle size of 100 nm to 100 μm. The method for producing fluorine-containing lithium composite transition metal oxide particles according to any one of claims 1 to 3, wherein the transition metal hydroxide particles are treated with fluorine to have a plurality of crystallites. Fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary between the crystallites are prepared, and the fluorine-containing transition metal hydroxide particles are fired to have a plurality of crystallites, and the crystallites have a plurality of crystals. Fluorine-containing transition metal oxide particles in which fluorine is present at the boundary between the two are prepared, the fluorine-containing transition metal oxide particles are used as the transition metal oxide particles, and the fluorine-containing transition metal oxide particles and the lithium compound are mixed. , A method for producing fluorine-containing lithium composite transition metal oxide particles, which comprises firing the obtained mixture. It is a method for producing a fluorine-containing transition metal oxide particle having at least one transition metal selected from the group consisting of Co, Ni and Mn as a transition metal, and has a plurality of crystallites and between the crystallites. A method for producing fluorine-containing transition metal oxide particles, which comprises firing fluorine-containing transition metal hydroxide particles in which fluorine is present at the boundary between the two. It is a particle made of a fluorine-containing transition metal hydroxide having at least one transition metal selected from the group consisting of Co, Ni and Mn as a transition metal, and has a plurality of crystallites among the crystallites. Fluorine-containing transition metal hydroxide particles characterized by the presence of fluorine at the boundary. An active material for a non-aqueous electrolyte secondary battery, which comprises the fluorine-containing lithium composite transition metal oxide particles according to any one of claims 1 to 3. An electrode for a non-aqueous electrolyte secondary battery, which comprises the active material for a non-aqueous electrolyte secondary battery according to claim 7. A non-aqueous electrolyte secondary battery having the electrode for the non-aqueous electrolyte secondary battery according to claim 8.

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