JP6981210B2 - Method for manufacturing lithium hydroxide pulverized powder - Google Patents

Description

The present invention relates to a method for producing pulverized lithium hydroxide powder.

In recent years, with the spread of portable electronic devices such as mobile phones and notebook personal computers, the development of a compact and lightweight non-aqueous electrolyte secondary battery having a high energy density is strongly desired.

Further, it is strongly desired to develop a high output secondary battery as a large battery such as a power source for driving a motor.

As a secondary battery satisfying such a requirement, there is a lithium ion secondary battery. The lithium ion secondary battery is composed of a negative electrode, a positive electrode, an electrolytic solution, and the like, and a material capable of desorbing and inserting lithium is used as an active material for the negative electrode and the positive electrode.

Research and development of lithium-ion secondary batteries is currently underway. Among them, a lithium ion secondary battery using a layered or spinel type lithium metal composite oxide as a positive electrode material is being put into practical use as a battery having a high energy density because a high voltage of 4V class can be obtained.

_{Currently, lithium cobalt composite oxide (LiCoO 2 ), which is relatively easy to synthesize, lithium nickel composite oxide (LiNiO 2} ) using nickel, which is cheaper than cobalt, and lithium as positive electrode materials for such lithium ion secondary batteries. Nickel Cobalt Manganese Composite Oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ), Lithium Manganese Composite Oxide Using Manganese (LiMn ₂ O ₄ ), Lithium Nickel Manganese Composite Oxide (LiNi _0.5) Mn _0.5 O _2), lithium-rich nickel-cobalt-manganese composite oxide _{(Li 2 MnO 3 -LiNi X Mn} y Co z O 2) lithium composite oxide such as have been proposed.

As a method for producing the above-mentioned lithium composite oxide, for example, Patent Document 1 describes the production of a lithium cobalt oxide oriented sintered plate for producing a lithium cobalt oxide oriented sintered plate constituting a positive electrode plate of a lithium secondary battery. The method is a green sheet manufacturing step of manufacturing a green sheet containing Co raw material and Bi ₂ O _3.
By firing the green sheet obtained in the green sheet manufacturing step in a bismuth atmosphere to which a bismuth source is added, an oriented fired plate having an orientation such that the (h00) plane is parallel to the sheet plane is manufactured. Green sheet firing process and
Lithium cobalt oxide has an orientation such that the (104) plane _{of LiCoO 2} is parallel to the plate surface by firing the orientation firing plate obtained in the green sheet firing step in a lithium atmosphere in which a lithium source coexists. A method for manufacturing a lithium cobalt oxide oriented sintered plate including a step for producing a lithium cobalt oxide oriented sintered plate is disclosed.

Further, for example, in the case of obtaining the above-mentioned granules of the lithium composite oxide, a method of firing a mixture of a lithium composite oxide precursor containing a component other than the lithium metal and a lithium compound such as lithium hydroxide. Is used.

In the case of producing a lithium composite oxide in this way, lithium hydroxide is used as a lithium source, but since industrially available lithium hydroxide is often in the form of agglomerates, it is usually crushed lithium hydroxide. Is used. Further, the crushed lithium hydroxide is conveyed in the pipe by the air flow and is conveyed to various processes.

For example, in Patent Document 1, an example of the LiOH · H 2 _O powder as lithium hydroxide was used after pulverized below 1μm in a jet mill is disclosed.

Japanese Unexamined Patent Publication No. 2016-105376

However, when lithium hydroxide is crushed to produce crushed lithium hydroxide powder, the crushed lithium hydroxide powder adheres to the inside of the crusher and the transport pipeline of the crushed powder discharged from the crusher, and sticks to the inside. Depending on the degree, the piping or the like may be blocked. If lithium hydroxide crushed powder adheres to the crusher or piping and becomes clogged in this way, it is necessary to disassemble the crusher or piping and perform maintenance such as cleaning the inside of the crusher, which reduces the operation rate. , There was a problem from the viewpoint of productivity.

Therefore, in view of the problems of the prior art, one aspect of the present invention is to provide a method for producing pulverized lithium hydroxide powder in which the occurrence of sticking of lithium hydroxide is suppressed.

According to one aspect of the present invention for solving the above problems, have a pulverizing step of pulverizing by a mechanical pulverizer lithium hydroxide,
Provided is a method for producing a lithium hydroxide pulverized powder, wherein the pulverization step is carried out in an atmosphere having a carbon dioxide concentration of less than 100% by volume and a dew point of −70 ° C. or lower.

According to one aspect of the present invention, it is possible to provide a method for producing pulverized lithium hydroxide powder in which the occurrence of sticking of lithium hydroxide is suppressed.

Hereinafter, embodiments for carrying out the present invention will be described, but the present invention is not limited to the following embodiments, and various modifications and variations to the following embodiments are made without departing from the scope of the present invention. Substitutions can be added.
[Manufacturing method of crushed lithium hydroxide powder]
An example of the configuration of the method for producing the pulverized lithium hydroxide powder of the present embodiment will be described.

The method for producing lithium hydroxide pulverized powder of the present embodiment can include a pulverization step of pulverizing lithium hydroxide with a mechanical pulverizer.

The inventors of the present invention have diligently investigated the cause of the lithium hydroxide pulverized powder sticking to the inside of the crusher and the transport pipeline of the pulverized powder discharged from the pulverizer when the lithium hydroxide is pulverized. rice field. As a result, when an air flow type crusher such as a jet mill is used as the crusher, the lithium hydroxide crushed powder is particularly likely to stick, and the gas and the gas in the crusher and the piping after the crusher are liable to stick. It was found that sticking is particularly likely to occur in the portion where the flow velocity of the pulverized powder is high.

In the method for producing lithium hydroxide pulverized powder of the present embodiment, based on the above-mentioned knowledge, a pulverization step by a mechanical crusher is provided as described above, and a pulverizer or a crusher is provided as compared with the case where an air flow crusher or the like is used. It suppresses the flow velocity of gas and crushed powder in the piping after the crusher. Therefore, the occurrence of sticking of lithium hydroxide and the occurrence of blockage due to the progress of sticking can be suppressed, and the production of pulverized lithium hydroxide powder can be carried out with high efficiency.

The type of crusher used in the crushing process is not particularly limited, and various mechanical crushers such as ball mills, bead mills, roller mills, planetary mills, hammer mills, pin mills, and stone mill type crushers (crushers) are used. be able to.

In particular, as the mechanical crusher used in the crushing step, a stone mill type crusher can be preferably used. The stone mill type crusher is an abrasive grain plate rubbing crusher having a plurality of abrasive grain plates provided with abrasive grains, and the abrasive grain plates are rubbed and arranged. The object to be crushed can be crushed by rubbing the abrasive grain plates. According to the stone mill type crusher, as described above, the flow velocity of the gas and the crushed powder in the crusher and the piping after the crusher can be particularly suppressed, and the sticking of lithium hydroxide and the occurrence of blockage can be suppressed. Therefore, the operation can be continuously performed, and the lithium hydroxide pulverized powder can be produced with high efficiency.

Further, by using a stone mill type crusher, if the object to be crushed passes between the grindstones in principle, the object to be crushed can be crushed in a short time with a particle size corresponding to a predetermined distance between the grindstones. Therefore, with respect to the obtained lithium hydroxide pulverized powder, it is possible to particularly improve the productivity while suppressing the variation in the pulverized particle size among a plurality of lots.

Further, by using a millstone type crusher, the crushing atmosphere can be easily changed and controlled depending on the purge air type.

Further, in the method for producing the lithium hydroxide pulverized powder of the present embodiment, it is preferable to carry out the pulverization step in a decarboxylation atmosphere.

The decarbonized atmosphere referred to here means an atmosphere in which the content of carbon dioxide gas, that is, carbon dioxide is lower than that of the atmospheric atmosphere, and for example, an atmosphere having a carbon dioxide concentration of less than 100 volume ppm is preferable, and 50 volume ppm is preferable. It is more preferably 20% by volume or less, and further preferably 20% by volume or less. The lower limit of the carbon dioxide content in the decarboxylation atmosphere is not particularly limited and may be 0, so that it can be 0 or more.

By suppressing the carbonation of the pulverized lithium hydroxide powder in the pulverization step, the inventors of the present invention can particularly suppress the fixation and blockage of lithium hydroxide in the pulverizer, the transport pipe, and the like. I found it.

Although it is not clear why the sticking and clogging of the lithium hydroxide pulverized powder can be particularly suppressed by suppressing the carbonization of the lithium hydroxide pulverized powder, the inventors of the present invention presume as follows. There is.

By crushing the massive lithium hydroxide into crushed lithium hydroxide powder, a new surface of lithium hydroxide is exposed, and the exposed new surface reacts with carbon dioxide in the atmosphere. For example, as shown by the following formula (1) or formula (2), lithium carbonate and water are produced.

2LiOH + CO ₂ → Li ₂ CO ₃ + H ₂ O ・ ・ ・ (1)
2LiOH ・ H ₂ O + CO ₂ → Li ₂ CO ₃ + 3H ₂ O ・ ・ ・ (2)
For this reason, when the carbon concentration (carbon content) of the lithium hydroxide pulverized powder is high, the water content due to the water generated during carbonization is also high, and the lithium hydroxide pulverized powder is stuck or hydroxylated. It is considered that agglomeration is likely to occur between the lithium pulverized powders and blockage of the pipe is likely to occur.

Therefore, by carrying out the crushing step in a decarbonized atmosphere as described above, carbonation of the crushed lithium hydroxide powder is suppressed, and sticking by the crushed lithium hydroxide powder and aggregation between the crushed lithium hydroxide powder are particularly prevented. It is thought that it can be prevented. Therefore, it is preferable to carry out the pulverization step in a decarboxylation atmosphere as described above.

By carrying out the pulverization step in such a decarboxylation atmosphere, it is preferable to produce a lithium hydroxide pulverized powder having a carbon concentration, that is, a carbon content of 0.3% by mass or less. This is because when the carbon concentration of the lithium hydroxide pulverized powder is 0.3% by mass or less, the above reaction is suppressed and the amount of water generated is small, so that the lithium hydroxide pulverized powder is stuck or between the crushed powders. This is because the aggregation of the powder can be particularly suppressed.

The carbon concentration of the lithium hydroxide pulverized powder obtained by the method for producing the lithium hydroxide pulverized powder of the present embodiment is preferably small, and more preferably 0.2% by mass or less.

Further, the lower limit of the carbon concentration of the lithium hydroxide pulverized powder obtained by the method for producing the lithium hydroxide pulverized powder of the present embodiment is not particularly limited, but may be, for example, 0 or more.

The method for measuring the carbon concentration of the pulverized lithium hydroxide powder is not particularly limited, but for example, it can be measured and evaluated by an inorganic carbon analyzer that burns and analyzes carbon in a sample at a high frequency or the like.

The carbon concentration of lithium hydroxide as a raw material is preferably 0.3% by mass or less, and more preferably 0.15% by mass or less. The lower limit of the carbon concentration of lithium hydroxide as a raw material is not particularly limited, but may be, for example, 0.02% by mass or more.

Further, the water content in the atmosphere of the pulverization step does not directly affect the surface condition of the lithium hydroxide pulverized powder, and the content thereof is not particularly limited. However, it is preferable that the content of water in the atmosphere used in the crushing step is small, particularly from the viewpoint of suppressing sticking by the crushed lithium hydroxide powder and aggregation between the crushed lithium hydroxide powders. For example, the pulverization step is preferably carried out in an atmosphere having a dew point of −70 ° C. or lower.

The lower limit of the dew point in the atmosphere of the crushing step is not particularly limited, but the dew point in the atmosphere of the crushing step can be −90 ° C. or higher because the cost is high in order to make it excessively low.

The atmosphere of the crushing step is not particularly limited, and for example, air having a reduced carbon dioxide and / or water content (decarboxylated air and / or dry air), an inert gas atmosphere, an oxygen atmosphere, or the like is arbitrary. Atmosphere can be used. Even in the case of an inert gas atmosphere, an oxygen atmosphere, etc., it is preferable that the content of carbon dioxide and water is small as described above, and the content of carbon dioxide and / or water is within the above-mentioned range. It is preferable to meet.

In the method for producing the lithium hydroxide pulverized powder of the present embodiment, the atmosphere after the pulverization step is not particularly limited, and any atmosphere can be used. For example, it can be an atmospheric atmosphere.

The particle size of the lithium hydroxide pulverized powder obtained by the method for producing the lithium hydroxide pulverized powder of the present embodiment is not particularly limited, but the smaller the particle size, the larger the bulk of the lithium hydroxide pulverized powder, so that the filling property is improved. It can be a problem. Therefore, the average particle size of the pulverized lithium hydroxide powder of the present embodiment is preferably, for example, 10 μm or more, and more preferably 30 μm or more.

However, if the average particle size is too large, there may be a problem in the mixing property of the pulverized lithium hydroxide powder and the transition metal precursor powder when producing the positive electrode active material. Therefore, the lithium hydroxide of the present embodiment may be problematic. The average particle size of the pulverized powder is, for example, preferably 120 μm or less, and more preferably 100 μm or less.

The average particle size here means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method. As used herein, the average particle size has the same meaning.

The type of lithium hydroxide contained in the lithium hydroxide pulverized powder obtained by the method for producing the lithium hydroxide pulverized powder of the present embodiment is not particularly limited. For example, the pulverized lithium hydroxide powder preferably contains one or more selected from anhydrous lithium hydroxide and lithium hydroxide monohydrate.

Further, the pulverized lithium hydroxide powder may be composed of one or more selected from anhydrous lithium hydroxide and lithium hydroxide monohydrate. However, even in this case, it is not excluded that the lithium hydroxide pulverized powder contains an unavoidable component mixed in the pulverizing step or the like.

According to the method for producing the lithium hydroxide pulverized powder of the present embodiment described above, since the mechanical crusher is used in the crushing step, the inside of the pulverizer and the pulverization are performed as compared with the case where the air flow crusher is used. It is possible to particularly suppress the sticking of lithium hydroxide in the transport pipe after the machine and the accompanying blockage. Therefore, the production of pulverized lithium hydroxide powder can be carried out with high efficiency.
[Non-aqueous electrolyte solution Positive electrode active material for secondary batteries and its manufacturing method]
Next, a configuration example of the positive electrode active material for a non-aqueous electrolyte secondary battery of the present embodiment (hereinafter, also simply referred to as “positive electrode active material”) and a method for producing the same will be described.

The positive electrode active material of the present embodiment may be any positive electrode active material produced by using the above-mentioned pulverized lithium hydroxide powder, and the composition thereof is not particularly limited.

Positive electrode active material of the present embodiment, for example, the general _{formula: Li x Ni (1-y} -z) Co y M z O 2 + α ( wherein, M is, Al, at least one element selected from among Ti Representation of x, y, and z is 0.90 ≦ x ≦ 1.10, 0.02 ≦ y ≦ 0.35, 0.005 ≦ z ≦ 0.15, −0.2 ≦ α ≦ 0.2, respectively. It can be a lithium metal composite oxide represented by).

The method for producing the positive electrode active material of the present embodiment is not particularly limited. The method for producing the positive electrode active material of the present embodiment can include, for example, the following steps.

A roasting process that heat treats precursor hydroxides.

A mixing step in which a heat-treated precursor hydroxide and lithium hydroxide pulverized powder are mixed to form a mixture.

A firing step of firing the mixture formed in the mixing step.

Hereinafter, each step will be described.
(Roasting process)
In the roasting step, the precursor hydroxide can be heat-treated, and the precursor hydroxide can be selected according to the composition of the positive electrode active material to be produced. For example, nickel-cobalt composite hydroxide can be used. Examples of the nickel-cobalt composite hydroxide, for example the general _{formula: Ni} in _{(1-y-z) Co} y M z (OH) 2 + β ( wherein, M is, Al, at least one element selected from among Ti Represented by y and z, respectively, satisfying 0.02 ≦ y ≦ 0.35, 0.005 ≦ z ≦ 0.15, −0.2 ≦ β ≦ 0.2)) Things can be used. The method for producing the nickel-cobalt composite hydroxide is not particularly limited, and for example, nickel-cobalt composite hydroxide can be obtained by coprecipitating nickel, cobalt and the additive element M.

In the roasting step, for example, the water content in the precursor hydroxide can be removed, and at least a part of the precursor hydroxide can be used as an oxide.

The heat treatment temperature in the roasting step is not particularly limited, but the heat treatment removes the water contained in the precursor hydroxide particles, and the ratio of the number of atoms of lithium and other metals in the finally obtained positive electrode active material is It is preferable to select so that variation can be prevented.

The heat treatment temperature in the roasting step is not particularly limited, but for example, the heat treatment temperature is preferably 105 ° C. or higher and 800 ° C. or lower, and more preferably 500 ° C. or higher and lower than 800 ° C.

This is because when the heat treatment temperature in the roasting process is less than 105 ° C, the excess water in the precursor hydroxide cannot be removed, and the number of atoms of lithium and other metals in the finally obtained positive electrode active material is high. This is because there is a possibility that the variation in the ratio of the above will be large.

Further, if the heat treatment temperature exceeds 800 ° C., the particles may be sintered by roasting and a positive electrode active material having a uniform particle size may not be obtained.

In the roasting step, it is sufficient that water can be removed to the extent that the ratio of the number of atoms of a metal such as lithium in the obtained positive electrode active material does not vary, so that all precursor hydroxides are not necessarily converted to oxides. do not have to. However, in order to further reduce the variation in the number of atoms of the metal in the obtained positive electrode active material, it is preferable to convert all the precursor hydroxide into an oxide at a heat treatment temperature of 500 ° C. or higher.

Therefore, it is more preferable that the heat treatment temperature in the roasting step is, for example, 500 ° C. or higher and lower than 800 ° C.

The atmosphere during the heat treatment in the roasting step is not particularly limited and may be a non-reducing atmosphere, but it is preferably performed in an air stream that can be easily performed.

The heat treatment time (roasting time) in the roasting step is not particularly limited, but less than 1 hour may not sufficiently remove the excess water of the precursor hydroxide, so 1 hour or more is preferable. 2 hours or more is more preferable. The upper limit of the heat treatment time is not particularly limited, but is preferably 15 hours or less in consideration of productivity and the like.

The equipment used for roasting is not particularly limited as long as it can heat the precursor hydroxide in a non-reducing atmosphere, preferably in an air stream, and is an electric furnace that does not generate gas. Etc. are preferably used.
(Mixing process)
In the mixing step, the precursor hydroxide (hereinafter referred to as “roasted particles”) after the heat treatment obtained in the roasting step is mixed with the pulverized lithium hydroxide powder to obtain a mixture (mixed powder). It is a process.

The ratio (Li / Me) of the number of atoms of a metal other than lithium in the mixture of the roasted particles and the pulverized lithium hydroxide powder to the number of atoms of lithium (Li) is 0.90 or more and 1.10 or less. It is preferable to mix them so as to be. Since Li / Me hardly changes before and after the firing step described later, the Li / Me in the mixture to be subjected to the firing step is almost the same as the Li / Me in the obtained positive electrode active material. Therefore, it is preferable to mix Li / Me in the mixture prepared in the mixing step so as to be the same as Li / Me in the positive electrode active material to be obtained.

In the mixing step, a general mixer can be used as a mixing means for mixing the roasted particles and the pulverized lithium hydroxide powder, and for example, a shaker mixer, a ladyge mixer, a julia mixer, a V blender, or the like can be used. You can use it.
(Baking process)
The firing step is a step of firing the mixture obtained in the above mixing step to obtain a positive electrode active material. When the mixture is fired in the firing step, lithium in the lithium hydroxide pulverized powder diffuses into the roasted particles to form a positive electrode active material, for example, lithium nickel cobalt composite oxide particles.

In the firing step, the firing temperature for firing the mixture is not particularly limited, but is preferably 600 ° C. or higher and 950 ° C. or lower, and more preferably 700 ° C. or higher and 900 ° C. or lower.

By setting the firing temperature to 600 ° C. or higher, the diffusion of lithium into the roasted particles can be sufficiently promoted, the crystal structure of the obtained positive electrode active material can be made uniform, and the product can be used as the positive electrode. This is because the battery characteristics can be particularly enhanced when used as a substance, which is preferable. Further, since the reaction can be sufficiently proceeded, it is possible to suppress the residual of excess lithium and the residual of unreacted particles.

By setting the firing temperature to 950 ° C. or lower, it is possible to suppress the progress of sintering between the particles of the positive electrode active material to be produced. In addition, it is possible to suppress the occurrence of abnormal grain growth and suppress the coarsening of the particles of the obtained positive electrode active material.

Further, in the process of raising the temperature to the heat treatment temperature, it is preferable to keep the temperature near the melting point of lithium hydroxide for about 1 hour or more and 5 hours or less so that the reaction can be carried out more uniformly.

Of the firing times in the firing step, the holding time at a predetermined temperature, that is, the above-mentioned firing temperature is not particularly limited, but is preferably 2 hours or longer, more preferably 4 hours or longer. This is because by setting the holding time at the firing temperature to 2 hours or more, it is possible to sufficiently promote the production of the positive electrode active material and more reliably prevent the unreacted material from remaining.

The upper limit of the holding time at the firing temperature is not particularly limited, but is preferably 24 hours or less in consideration of productivity and the like.

The atmosphere at the time of firing is not particularly limited, but an oxidizing atmosphere is preferable. As the oxidizing atmosphere, an oxygen-containing gas atmosphere can be preferably used, and for example, an atmosphere having an oxygen concentration of 18% by volume or more and 100% by volume or less is more preferable.

This is because the crystallinity of the positive electrode active material can be particularly enhanced by setting the oxygen concentration in the atmosphere at the time of firing to 18% by volume or more.

In the case of an oxygen-containing gas atmosphere, for example, the atmosphere, oxygen, a mixed gas of oxygen and an inert gas, or the like can be used as the gas constituting the atmosphere.

When a mixed gas of oxygen and an inert gas is used as the gas constituting the oxygen-containing gas atmosphere, for example, the oxygen concentration in the mixed gas preferably satisfies the above range.

In particular, the firing step is preferably carried out in an oxygen-containing gas atmosphere as described above, more preferably in an oxygen-containing gas stream, and even more preferably in an atmosphere or an oxygen stream. In particular, considering the battery characteristics, it is preferable to perform the operation in an oxygen stream.

The furnace used for firing is not particularly limited as long as it can fire the mixture in the atmosphere or an oxygen stream, but from the viewpoint of keeping the atmosphere in the furnace uniform, electricity that does not generate gas is used. A furnace is preferable, and either a batch type or a continuous type furnace can be used.

The positive electrode active material obtained by the firing step may be aggregated or slightly sintered. In this case, it may be crushed.

Here, crushing is to apply mechanical energy to an agglomerate composed of a plurality of secondary particles generated by sintering necking between secondary particles during firing to almost destroy the secondary particles themselves. It is an operation to separate secondary particles and loosen aggregates.

Further, it is preferable to carry out temporary firing before the firing step.

When the calcination is carried out, the calcination temperature is not particularly limited, but may be lower than the calcination temperature in the calcination step. The calcination temperature is preferably, for example, 250 ° C. or higher and 600 ° C. or lower, and more preferably 350 ° C. or higher and 550 ° C. or lower.

The tentative firing time, that is, the holding time at the tentative firing temperature is preferably, for example, about 1 hour or more and 10 hours or less, and more preferably 3 hours or more and 6 hours or less.

After the temporary firing, it can be cooled once and then subjected to the firing step, but it is also possible to continuously carry out the firing step by raising the temperature from the temporary firing temperature to the firing temperature.

The atmosphere when performing the temporary firing is not particularly limited, but can be, for example, the same atmosphere as in the firing step.

By tentative firing, lithium is sufficiently diffused into the roasted particles, and a particularly uniform positive electrode active material can be obtained.

According to the positive electrode active material of the present embodiment and the method for producing the same, the lithium hydroxide pulverized powder obtained by the above-mentioned method for producing the lithium hydroxide pulverized powder can be used as one of the raw materials. Therefore, the pulverized lithium hydroxide powder can react uniformly with the roasted particles, and the lithium site occupies a high proportion of lithium, so that it can be a positive electrode active material having excellent crystallinity. Therefore, it is possible to obtain a non-aqueous electrolyte secondary battery having excellent battery characteristics when used as a positive electrode material for the non-aqueous electrolyte secondary battery.
[Non-aqueous electrolyte secondary battery]
Next, a configuration example of the non-aqueous electrolyte secondary battery of the present embodiment will be described.

The non-aqueous electrolyte secondary battery of the present embodiment can have a positive electrode using the above-mentioned positive electrode active material as the positive electrode material.

First, a configuration example of the structure of the non-aqueous electrolyte secondary battery of the present embodiment will be described.

The non-aqueous electrolyte secondary battery of the present embodiment may have substantially the same structure as a general non-aqueous electrolyte secondary battery except that the above-mentioned positive electrode active material is used as the positive electrode material. can.

Specifically, the non-aqueous electrolyte secondary battery of the present embodiment can have a structure including a case and a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator housed in the case.

More specifically, a positive electrode and a negative electrode can be laminated via a separator to form an electrode body, and the obtained electrode body can be impregnated with a non-aqueous electrolytic solution. Then, the positive electrode current collector of the positive electrode and the positive electrode terminal communicating with the outside are connected, and the negative electrode current collector of the negative electrode and the negative electrode terminal communicating with the outside are connected by using a current collector lead or the like, and connected to the case. It can have a closed structure.

Needless to say, the structure of the non-aqueous electrolyte secondary battery of the present embodiment is not limited to the above example, and various shapes such as a tubular shape and a laminated shape can be adopted as the outer shape thereof.

A configuration example of each member will be described below.
(Positive electrode)
First, the positive electrode will be described.

The positive electrode is a sheet-shaped member, and for example, a positive electrode mixture paste containing the above-mentioned positive electrode active material can be applied and dried on the surface of a current collector made of aluminum foil. The positive electrode is appropriately processed according to the battery used. For example, it is possible to perform a cutting process for forming the battery into an appropriate size according to the target battery, a pressure compression process using a roll press or the like in order to increase the electrode density, and the like.

The above-mentioned positive electrode mixture paste can be formed by adding a solvent to the positive electrode mixture and kneading the paste. Then, the positive electrode mixture can be formed by mixing the above-mentioned positive electrode active material in powder form, the conductive material, and the binder.

The conductive material is added to give appropriate conductivity to the electrode. The material of the conductive material is not particularly limited, and for example, graphite such as natural graphite, artificial graphite and expanded graphite, and carbon black materials such as acetylene black and ketjen black can be used.

The binder serves to hold the positive electrode active material together. The binder used for the positive electrode mixture is not particularly limited, and for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluororubber, ethylenepropylenediene rubber, styrene-butadiene, cellulose resin, and polyacrylic acid. One or more selected from acids and the like can be used.

Activated carbon or the like can also be added to the positive electrode mixture. By adding activated carbon or the like to the positive electrode mixture, the electric double layer capacity of the positive electrode can be increased.

The solvent has a function of dissolving the binder and dispersing the positive electrode active material, the conductive material, activated carbon and the like in the binder. The solvent is not particularly limited, but an organic solvent such as N-methyl-2-pyrrolidone can be used.

Further, the mixing ratio of each substance in the positive electrode mixture paste is not particularly limited, and can be, for example, the same as in the case of the positive electrode of a general non-aqueous electrolyte secondary battery. For example, when the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material is 60 parts by mass or more and 95 parts by mass or less, and the content of the conductive material is 1 part by mass or more and 20 parts by mass or less. The content of the binder can be 1 part by mass or more and 20 parts by mass or less.

The method for manufacturing the positive electrode is not limited to the above method, and for example, the positive electrode mixture or the positive electrode paste can be press-molded and then dried in a vacuum atmosphere.
(Negative electrode)
The negative electrode is a sheet-like member formed by applying a negative electrode mixture paste to the surface of a metal foil current collector such as copper and drying it.

The negative electrode is formed by substantially the same method as the above-mentioned positive electrode, although the components constituting the negative electrode mixture paste, their composition, the material of the current collector, etc. are different. Will be done.

The negative electrode mixture paste can be made into a paste by adding an appropriate solvent to the negative electrode mixture in which the negative electrode active material and the binder are mixed.

As the negative electrode active material, for example, a substance containing lithium such as metallic lithium or a lithium alloy, or an occlusion substance capable of storing and desorbing lithium ions can be adopted.

The occluded substance is not particularly limited, but one or more selected from, for example, an organic compound calcined body such as natural graphite, artificial graphite, and phenol resin, and a powdery body of a carbon substance such as coke can be used.

When the occlusal substance is used as the negative electrode active material, a fluororesin such as PVDF can be used as the binder as in the case of the positive electrode, and the solvent for dispersing the negative electrode active material in the binder can be used. An organic solvent such as N-methyl-2-pyrrolidone can be used.
(Separator)
The separator is arranged so as to be sandwiched between the positive electrode and the negative electrode, and has a function of separating the positive electrode and the negative electrode and holding an electrolytic solution.

As the material of the separator, a thin film such as polyethylene or polypropylene, which has a large number of fine pores, can be used, but is not particularly limited as long as it has the above-mentioned function.
(Non-aqueous electrolyte solution)
The non-aqueous electrolyte solution is, for example, a solution obtained by dissolving a lithium salt as a supporting salt in an organic solvent.

Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and trifluoropropylene carbonate; and chain carbonates such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate and dipropyl carbonate; further, tetrahydrofuran and 2-. Ether compounds such as methyltetrahydrofuran and dimethoxyethane; sulfur compounds such as ethylmethyl sulfone and butane sulton; phosphorus compounds such as triethyl phosphate and trioctyl phosphate are used alone or in combination of two or more. be able to.

As the supporting salt, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , and a composite salt thereof can be used.

The non-aqueous electrolyte solution may contain a radical scavenger, a surfactant, a flame retardant, or the like in order to improve the battery characteristics.

The non-aqueous electrolyte secondary battery of the present embodiment includes a positive electrode using the above-mentioned positive electrode active material as the positive electrode material. Therefore, a non-aqueous electrolyte secondary battery having excellent battery characteristics can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples.
[Example 1]
(Manufacturing of crushed lithium hydroxide powder)
Lithium hydroxide pulverized powder was produced by the following procedure.

For lithium hydroxide monohydrate (LiOH · _H 2 O), it was subjected to dry treatment by vacuum drying. The carbon concentration of this anhydrous lithium hydroxide was 0.05% by mass.

Then, the obtained anhydrous lithium hydroxide was subjected to a pulverization step.

In the crushing process, in order from the upstream side of the transport path of anhydrous lithium hydroxide as a raw material, a hopper that stores anhydrous lithium hydroxide before crushing, and a stone mill type crusher and a mechanical crusher, Mascoroida. -(Registered trademark) (Masuyuki Sangyo Co., Ltd. model: MKZA15-40JM), a bag filter for collecting crushed powder, a hopper for storing crushed powder, and a packing device for packing crushed powder are arranged. The crushing means was used.

The hopper, crusher, bag filter, storage hopper, and packing device are connected by pipes, anhydrous lithium hydroxide supplied from the hopper is crushed by the crusher, and the crushed powder transported by air is the bag filter. It is configured to be collected by the hopper, temporarily stored in the hopper, and collected in the packing device. Further, on the pipe between the hopper and the crusher, a permanent magnet type magnet for removing foreign matter in metal and a vibrating sieve for removing foreign matter in the raw material are arranged.

In this embodiment, decarboxylated air having a dew point of −70 ° C. and a carbon dioxide content of 20 parts by volume ppm was continuously supplied into the crusher during the crushing step, and the inside of the crusher was made into the atmosphere. In addition, air transportation was used from the outlet of the crusher to the storage hopper, and normal air was used for air transportation.

Then, a preliminary test was conducted in advance, operating conditions of the crusher were selected so that the average particle size of the pulverized powder was in the range of 40 μm or more and 100 μm or less, and anhydrous lithium hydroxide was pulverized under such conditions. ..

After crushing, the carbon concentration of the crushed lithium hydroxide powder recovered in the packing device was analyzed by an inorganic carbon analyzer (manufactured by LECO Japan), and it was confirmed that it was 0.18% by mass.

In addition, the average particle size of the obtained crushed lithium hydroxide powder was measured by a laser diffraction / scattering type particle size distribution measuring device (manufactured by Microtrac Bell), and the bulk density was measured by measuring the powder weight of the constant volume container. As a result of analysis, the average particle size was 92.3 μm and the bulk density was 0.32 g / cc.

Further, when continuous pulverization was performed under the same conditions as in the above case, the occurrence of lithium hydroxide sticking in the crusher or the like could be particularly suppressed as compared with the case of Reference Example 1 described later, and the frequency of clogging in the crusher occurred. The maintenance frequency inside the crusher was reduced to 1/5, and the productivity was improved.
(Manufacturing of positive electrode active material)
Ni _0.88 Co _0.09 Al _0.03 (OH) ₂ was prepared as the precursor hydroxide, and the precursor hydroxide was placed in an air (oxygen: 21% by volume) air stream at 600 ° C. for 2 hours. Was treated to remove the water contained in the precursor hydroxide, which was converted into an oxide (Ni _0.88 Co _0.09 Al _0.03 O) and recovered. The average particle size of the nickel composite oxide was 12 μm, and the bulk density was 1.1 g / cc.

The above-mentioned pulverized lithium hydroxide powder and the precursor hydroxide that had been heat-treated in the roasting step were mixed to prepare a mixture (mixing step).

The obtained mixture is placed in a firing vessel having an internal size of 280 mm (L) × 280 mm (W) × 90 mm (H), and the mixture is placed in a firing vessel having an oxygen concentration of 80 by using a roller hearth kiln which is a continuous firing furnace. %, In an atmosphere where the balance is an inert gas, firing was performed at a maximum temperature of 765 ° C. (firing step). Further, in order to remove excess components adhering to the surface of the obtained calcined product, the calcined product was added to pure water so that the mass ratio was 1.5 with respect to 1 water to form a slurry, and the mixture was stirred for 5 minutes. After that, it was filtered and dried to obtain a positive electrode active material (washing step).

A Rietveld analysis of the obtained positive electrode active material using an X-ray diffractometer (X'Pert-PRO manufactured by Spectris Co., Ltd.) revealed that the seat occupancy rate of the lithium seat exceeded 98.5%. It could be confirmed. From this, it was confirmed that a high-quality positive electrode active material having excellent crystallinity was obtained.
[Example 2]
Lithium hydroxide according to Example 2 in the same manner as in Example 1 except that decarboxylated air having a dew point of −70 ° C. and a carbon dioxide content of 90 parts by volume ppm was used as the gas supplied into the crusher. A crushed powder was obtained.

The carbon concentration of the pulverized lithium hydroxide powder was 0.29% by mass. The average particle size was 66.8 μm and the bulk density was 0.31 g / cc.

Further, continuous pulverization was performed under the same conditions as in Example 1 except that decarboxylated air having a dew point of −70 ° C. and a carbon dioxide content of 90 parts by volume was used as the gas supplied into the pulverizer. Compared with the case of Reference Example 1 described later, the occurrence of lithium hydroxide sticking in the crusher or the like can be particularly suppressed, the frequency of blockage in the crusher is reduced, and the maintenance frequency inside the crusher is 1/4. It decreased to and the productivity was improved.

A positive electrode active material was produced in the same manner as in Example 1 except that the lithium hydroxide pulverized powder obtained in this example was used. When the Rietveld analysis of the obtained positive electrode active material was carried out by an X-ray diffractometer in the same manner as in Example 1, it was confirmed that the seat occupancy rate of the lithium seat exceeded 98.5%. From this, it was confirmed that a high-quality positive electrode active material having excellent crystallinity was obtained.
[Reference Example 1]
(Manufacturing of crushed lithium hydroxide powder)
Lithium hydroxide pulverized powder was produced by the following procedure.

The same anhydrous lithium hydroxide as in Example 1 was subjected to the pulverization step.

In the crushing process, in order from the upstream side of the transport path of anhydrous lithium hydroxide as a raw material, a hopper that stores anhydrous lithium hydroxide before crushing, a jet mill that is an airflow type crusher (manufactured by Seishin Enterprise Co., Ltd.), and A crushing means equipped with a bag filter for collecting crushed powder and a packing device for packing crushed powder was used.

The hopper, crusher, bag filter, and packing device that make up the crushing means are connected by piping, the anhydrous lithium hydroxide supplied from the hopper is crushed by the crusher, and the crushed powder is collected by the bag filter. , Is configured to be collected by the packing device. Further, on the pipe between the hopper and the crusher, a permanent magnet type magnet for removing foreign matter in metal and a vibrating sieve for removing foreign matter in the raw material are arranged.

As the jet mill, which is a crusher, a horizontal jet mill was used. Then, in the crusher, the raw material accelerated by the pusher air and the Venturi nozzle is introduced into the crushing chamber, and the high-speed fluid discharged from the gliding nozzle installed in the crushing chamber causes mutual collision and friction of the raw materials. Ultra-fine powder is obtained.

In this embodiment, decarboxylated air having a dew point of −70 ° C. and a carbon dioxide content of 20 parts by volume ppm is used as the gas to be introduced into the crusher, and the inside of the crusher is maintained in such an atmosphere during the crushing step. There is.

After crushing, the carbon concentration of the crushed lithium hydroxide powder recovered in the packing device was analyzed by an inorganic carbon analyzer (manufactured by LECO Japan), and it was confirmed that it was 0.17% by mass.

In addition, the average particle size of the obtained crushed lithium hydroxide powder was measured by a laser diffraction / scattering type particle size distribution measuring device (manufactured by Microtrac Bell), and the bulk density was measured by measuring the powder weight of the constant volume container. As a result of analysis, the average particle size was 67.5 μm and the bulk density was 0.30 g / cc.
(Manufacturing of positive electrode active material)
A positive electrode active material was obtained in the same manner as in Example 1 except that the lithium hydroxide pulverized powder produced in this reference example was used as the lithium hydroxide pulverized powder.

When the Rietveld analysis of the obtained positive electrode active material was performed by an X-ray diffractometer, it was confirmed that the seat occupancy rate of the lithium seat exceeded 98.5%. From this, it was confirmed that a high-quality positive electrode active material having excellent crystallinity was obtained.

Also in this reference example, by using decarboxylated air as the gas to be introduced into the crusher, the adhesion of lithium hydroxide is suppressed as compared with the case of using non-decarboxylated air, which is a conventional technique. However, the maintenance frequency can be significantly reduced. However, in Examples 1 and 2 described above, it was confirmed that by using the mechanical crusher, the sticking of lithium hydroxide can be further suppressed and the maintenance frequency can be reduced.

Claims (2)

Lithium hydroxide have a pulverizing step of pulverizing by a mechanical pulverizer,
A method for producing lithium hydroxide pulverized powder, wherein the pulverization step is carried out in an atmosphere where the carbon dioxide concentration is less than 100 volume ppm and the dew point is −70 ° C. or less. The method for producing lithium hydroxide pulverized powder according to claim 1, wherein the mechanical crusher is a stone mill type crusher.