JP7189044B2 - Positive electrode mixture and positive electrode for non-aqueous electrolyte secondary battery, and method for manufacturing non-aqueous electrolyte secondary battery using the same and positive electrode for non-aqueous electrolyte secondary battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a positive electrode mixture and a positive electrode for a non-aqueous electrolyte secondary battery, and a method for producing a non-aqueous electrolyte secondary battery using the same and a positive electrode for a non-aqueous electrolyte secondary battery.

Lithium cobaltate (LiCoO ₂ ) is widely used as a positive electrode active material for non-aqueous electrolyte secondary batteries. The positive electrode of this type of non-aqueous electrolyte secondary battery is formed by mixing a positive electrode active material, a conductive agent such as graphite, and a binder made of a polymer compound or the like to form a positive electrode mixture. It is obtained by compression-molding the mixture into pellets. Alternatively, the positive electrode is manufactured by adding an organic solvent to the positive electrode mixture to prepare a paste, and applying the paste to a current collector.

A battery using lithium cobaltate as a positive electrode active material has a high operating voltage, and thus can be used at a high voltage. On the other hand, since the reactivity of lithium cobalt oxide is high, various measures have been taken to stably use batteries.
For example, the stability of battery performance can be improved by using a fluororesin with high heat resistance and low reactivity as a binder for forming electrodes. As the fluorine resin, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or the like is used.
Among these, PVDF is known to be excellent in dispersibility in the positive electrode mixture and capable of producing a battery having good electrical characteristics. However, since PVDF is insoluble in water and requires an organic solvent such as N-methyl-2-pyrrolidone as a dispersant, the production of electrodes requires investment in facilities such as local exhaust.
On the other hand, since PTFE is hydrophilic and water can be used as a dispersant, it is considered to be a preferable binder from the viewpoint of safety.

By the way, PTFE is a fluororesin having an average molecular weight of 1,000,000 to 5,000,000, which tends to become fibrous. By kneading PTFE with a positive electrode active material or a conductive aid in the form of powder or a suspension dispersed in a solvent, these materials can be wrapped in a fibrous form and bound together. As a result, the active material and the conductive agent can be bound without losing their properties, and a high capacity can be obtained when a battery is produced.
For example, Patent Document 1 below discloses that a chemical battery having a high discharge capacity and little variation during manufacturing can be obtained by including a binder made of a fluororesin and a water-soluble surface-active perfluoro group-containing compound in an electrode. is disclosed.

JP-A-7-153467

On the other hand, mixing the fibrous PTFE into the positive electrode mixture increases the viscosity of the mixture, so how to improve the handleability of the mixture poses a problem in manufacturing.
In the case of coin-shaped non-aqueous electrolyte secondary batteries, positive electrode pellets formed by compression-molding the positive electrode mixture described above are used as the positive electrode. When producing a positive electrode pellet, it is necessary to efficiently fill a positive electrode mixture into a mold during compression molding, and release the positive electrode mixture from the mold without adhering the positive electrode mixture to the mold after compression. However, since PTFE has a high viscosity as described above, the fluidity of the positive electrode mixture is poor and it cannot be sufficiently supplied into the mold, or the produced positive electrode pellets are poorly releasable from the mold. Such problems arise.

In response to such problems, Patent Document 1 discloses that a water-soluble surface-active perfluoro group-containing compound and a fluororesin are dispersed in water instead of being in powder form, and a dispersion liquid is used to obtain pellets or sheets. is disclosed.
However, when a mixture mixed with a dispersion liquid is used as a binder, the electrode mixture is produced through a process of mixing the dispersion liquid. Such a manufacturing method increases the number of steps and control points compared to the case of mixing an active material, a conductive agent, and a binder, and then adding water to mix and granulate, which can lead to an increase in cost. There's a problem.

In view of such conventional problems, the present invention provides a positive electrode mixture that is excellent in handleability and is mixed with PTFE as a binder and a positive electrode using the same, and a non-aqueous positive electrode using this positive electrode. An object of the present invention is to produce an electrolyte secondary battery.

(1) In order to solve the above problems, a positive electrode mixture for a non-aqueous electrolyte secondary battery according to one aspect of the present invention comprises a particulate positive electrode active material made of a transition metal composite oxide, a conductive aid, and a poly A granular mixture containing a binder made of tetrafluoroethylene (PTFE) and a lubricant , wherein the positive electrode active material is 50 to 95% by mass with respect to the total mass of the mixture. It contains 4 to 40 % of the conductive aid and 1.5 to 2.5% of the binder, and has a particle size of 75 to 500 μm and an angle of repose of 35° or less.

Since the positive electrode mixture has an angle of repose of 35° or less, it has excellent fluidity, and when it is put into a mold, it can be easily put into every corner of the mold. Since it contains a positive electrode active material and a conductive aid, it can be kneaded and used to wrap and bind them in a fibrous form.
As a result, it is possible to easily mold with a mold, obtain a positive electrode with a desired shape, and bind the active material and the conductive aid without losing their properties, and when the battery is produced, It is possible to provide a positive electrode mixture capable of obtaining a high capacity.
Positive electrode active material: 90-95%, conductive aid: 3-8%, binder made of PTFE: 1.5-2.5%, particle size: 75-500 μm Granular mixture. Then, a mixture having an angle of repose of 35° or less can be obtained.

(2) In the positive electrode mixture according to one aspect of the present invention, the transition metal composite oxide is lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or lithium titanate (Li ₄ Ti ₅ O ₁₂ ). , lithium manganate (Li ₄ Mn ₅ O ₁₂ ).

If the transition metal composite oxide is the lithium-based transition metal composite oxide described above, it is possible to provide a positive electrode that can be applied to batteries that can be used at high voltages. If the transition metal composite oxide is lithium cobalt oxide, it can be used at a high voltage, and a binder made of polytetrafluoroethylene (PTFE) enhances the bonding between the positive electrode active material and the conductive aid and stabilizes it. It is possible to provide a positive electrode mixture that contributes to a positive reaction.

(3) In the positive electrode material mixture according to one aspect of the present invention, it is preferable that the conductive aid is composed of one or more of graphite, carbon, furnace black, ketjen black, and acetylene black.

(4) A positive electrode according to an aspect of the present invention includes the positive electrode mixture for a non-aqueous electrolyte secondary battery according to any one of (1) to (3), and as the lubricant , the non-aqueous electrolyte secondary Hydrophobic silica is added in an amount of 0.5 to 2.0% by mass relative to the positive electrode material mixture for a battery, and the material is a pellet-shaped compression-molded body.
(5) A nonaqueous electrolyte secondary battery according to one aspect of the present invention includes the positive electrode for a nonaqueous electrolyte secondary battery according to (4).

Since it contains a suitable amount of hydrophobic silica in a mass ratio of 0.5 to 2.0% by mass with respect to the total mass of the positive electrode mixture, it is excellent in filling properties into the mold, and it can be removed from the mold after molding. Excellent releasability. In addition, when the particle size of the granular mixture is in the range of 75 to 500 μm, it is excellent in handleability, easy to handle, excellent in fillability in a mold, and a compacted product that is sufficiently compacted at the time of molding. Obtainable.
Therefore, it is possible to efficiently obtain a positive electrode that does not lose its shape, crack, or the like when it is released from the mold, and the yield of positive electrode production is improved.
Further, when a non-aqueous electrolyte secondary battery having a positive electrode of this structure is constructed, a battery capable of supplying a sufficient discharge capacity and a large current can be provided.

(6) In order to solve the above problems, a method for manufacturing a positive electrode for a coin-shaped non-aqueous electrolyte secondary battery according to one aspect of the present invention includes: a positive electrode active material made of a powdery transition metal composite oxide ; , a conductive agent, a binder made of polytetrafluoroethylene (PTFE) , and a lubricant are put into a mixing stirrer, and water is added to mix and stir to form granules having a particle size of 75 to 500 μm. The positive electrode active material, the conductive aid, and the The ratio of the amount of the binder added is in the range of 50 to 95%, 4 to 40 %, and 1.5 to 2.5% by mass relative to the total mass of these, and the amount of the water added is the above. A positive electrode mixture having an angle of repose of 35° or less is obtained by setting the mass ratio to the total mass of the positive electrode active material, the conductive aid and the binder in the range of 14 to 20 %.

A powdery positive electrode active material, a conductive aid, and a binder composed of polytetrafluoroethylene are put into a mixing stirrer. A kneaded product containing granules having a suitable particle size of 75 to 500 μm and excellent in handleability can be obtained. If the positive electrode material mixture has a particle size within this range, it can be smoothly filled without clogging the pipe or feeder when it is introduced into the mold through a pipe or the like.
The granules having a suitable particle size of 75 to 500 μm and excellent handleability and an angle of repose of 35° or less are compression-molded into pellets by press working as a positive electrode mixture, resulting in a state excellent in fillability in the mold. It is possible to mold a well-shaped pellet-shaped positive electrode that does not have sink marks or chips. In addition, since the positive electrode mixture described above is excellent in releasability from the mold, the pellet-shaped positive electrode can be safely removed from the mold, and the positive electrode can be obtained without cracks or chips.

(7) In one aspect of the present invention, hydrophobic silica is used as the lubricant in a mass ratio of 0.5 to 2.0% with respect to the positive electrode mixture.

By adding 0.5 to 2.0% by mass of hydrophobic silica to the positive electrode mixture, the adhesiveness of polytetrafluoroethylene used as a binder is alleviated and the releasability from the mold is improved. contribute to

(8) In one aspect of the present invention, the transition metal composite oxide includes lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), and lithium manganate. (Li ₄ Mn ₅ O ₁₂ ) can be used.
(9) A method for manufacturing a positive electrode for a coin-shaped non-aqueous electrolyte secondary battery according to one aspect of the present invention, wherein the conductive agent is graphite, carbon, furnace black, ketjen black, or acetylene black. Two or more kinds can be used.
(10) A method for manufacturing a coin-shaped non-aqueous electrolyte secondary battery according to one aspect of the present invention is a non-aqueous electrolyte secondary battery obtained by the manufacturing method according to any one of (6) to (9). It is characterized by using a positive electrode for

According to this aspect, by using a binder made of polytetrafluoroethylene (PTFE), the positive electrode active material and the conductive aid can be bound in an effective binding state. Therefore, when a battery having a positive electrode of this structure is constructed, a sufficient discharge capacity and a large current can be supplied.
If the positive electrode mixture is a granular positive electrode mixture with a particle size of 75 to 500 μm and an angle of repose of 35° or less, it has excellent fluidity, and when it is charged into the mold, it is introduced into every corner of the mold. It is possible to provide a positive electrode mixture that is easy to form, easy to mold with a mold, and easy to obtain a positive electrode having a desired shape. In addition, since the positive electrode mixture described above has excellent releasability from the mold, cracks and chips are less likely to occur when it is removed from the mold, and it is possible to efficiently produce well-shaped pellet-shaped positive electrodes. have the effect of

FIG. 1 is a cross-sectional view schematically showing a non-aqueous electrolyte secondary battery that is one embodiment of the present invention.

An example of a non-aqueous electrolyte secondary battery, which is one embodiment of the present invention, will be given and its configuration will be described in detail with reference to FIG.
In the following description, as a button-type or coin-type electrochemical cell, a lithium-ion secondary battery (hereinafter simply referred to as "battery"), which is a type of non-aqueous electrolyte secondary battery, will be taken as an example. The non-aqueous electrolyte secondary battery described below is specifically a non-aqueous electrolyte secondary battery in which an active material used as a positive electrode or a negative electrode and an electrolyte are housed in a container.
In addition, in the drawings used for the following explanation, the scale of each member is appropriately changed in order to make each member recognizable, so the relative sizes of each member are limited to those shown in the drawings. Of course not.

A non-aqueous electrolyte secondary battery 1 of the present embodiment shown in FIG. 1 is a so-called coin (button) type battery. This non-aqueous electrolyte secondary battery 1 is arranged in a storage container 2 between a positive electrode 10 capable of intercalating/releasing lithium ions, a negative electrode 20 capable of intercalating/releasing lithium ions, and between the positive electrode 10 and the negative electrode 20. and an electrolyte (electrolyte solution) 50 containing at least a supporting salt and an organic solvent.
More specifically, the non-aqueous electrolyte secondary battery 1 of this embodiment includes a bottomed cylindrical positive electrode can 12 and an opening 12 a of the positive electrode can 12 , which is fixed with a gasket 40 interposed therebetween. and a lidded cylindrical (hat-shaped) negative electrode can 22 that forms an accommodation space in the bottom. By crimping the periphery of the opening 12a of the positive electrode can 12 inward, that is, toward the negative electrode can 22 side, the storage container 2 that seals the storage space is configured.

In the non-aqueous electrolyte secondary battery 1 of the present embodiment, the positive electrode 10 includes a positive electrode active material made of a lithium transition metal composite oxide such as lithium cobalt oxide (LiCoO ₂ ), a conductive aid, and a binder (binder). and the negative electrode 20 includes a negative electrode active material such as lithium titanate, a conductive aid such as graphite, and a binder.
The lithium transition metal composite oxide used as the positive electrode active material includes lithium nickelate (LiNiO ₂ ), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), lithium manganate (Li ₄ Mn ₅ O ₁₂ ), and the like. Also good. Further, the negative electrode active material is silicon (Si), Si oxide (SiO), spinel-type lithium titanate (Li ₄ Ti ₅ O ₁₂ ), carbon (C), lithium-aluminum (Li—Al) alloy, or the like. can be
The detailed structure of each part of the non-aqueous electrolyte secondary battery 1 will be described below.

A positive electrode 10 provided on the positive electrode can 12 side and a negative electrode 20 provided on the negative electrode can 22 side are arranged facing each other via a separator 30 in the storage space sealed by the storage container 2 . is filled.
Moreover, as shown in FIG. 1 , the gasket 40 is narrowly inserted along the inner peripheral surface of the positive electrode can 12 and is connected to the outer periphery of the separator 30 to hold the separator 30 .
Moreover, the positive electrode 10 , the negative electrode 20 and the separator 30 are impregnated with an electrolyte (electrolyte solution) 50 filled in the storage container 2 .

In the non-aqueous electrolyte secondary battery 1 of the example shown in FIG. It is electrically connected to the inner surface of the negative electrode can 22 . In the present embodiment, the non-aqueous electrolyte secondary battery 1 including the positive electrode current collector 14 and the negative electrode current collector 24 as illustrated in FIG. Instead, for example, a configuration in which the positive electrode can 12 also serves as a positive electrode current collector and the negative electrode can 22 also serves as a negative electrode current collector may be adopted.

The non-aqueous electrolyte secondary battery 1 of the present embodiment is roughly configured as described above, so that lithium ions move from one of the positive electrode 10 and the negative electrode 20 to the other, thereby accumulating (charging) an electric charge. A battery that can release (discharge) an electric charge.

(Positive can and negative can)
In the present embodiment, the positive electrode can 12 constituting the storage container 2 is, as described above, formed in a bottomed cylindrical shape and has a circular opening 12a in plan view. As the material for such a positive electrode can 12, conventionally known materials can be used without any limitation, and examples thereof include stainless steel such as SUS316L, SUS304-BA, and NAS64.

Further, as described above, the negative electrode can 22 is configured in a lidded cylindrical shape (hat shape), and the tip portion 22a thereof is configured to enter the positive electrode can 12 through the opening 12a. Similar to the material of the positive electrode can 12, conventionally known stainless steel can be used as the material of the negative electrode can 22. For example, SUS304-BA can be used. Further, for the negative electrode can 22, for example, a clad material obtained by press-contacting copper, nickel, or the like to stainless steel can be used.

As shown in FIG. 1, the cathode can 12 and the anode can 22 are fixed by crimping the periphery of the opening 12a of the cathode can 12 toward the anode can 22 with a gasket 40 interposed therebetween. For this reason, the non-aqueous electrolyte secondary battery 1 is hermetically held in a state in which the housing space is formed. Therefore, the maximum inner diameter of the positive electrode can 12 is set larger than the maximum outer diameter of the negative electrode can 22 .

The plate thickness of the metal plate material used for the positive electrode can 12 and the negative electrode can 22 is generally about 0.1 to 0.3 mm. It can be configured as a degree.

In the example shown in FIG. 1, the tip portion 22a of the negative electrode can 22 has a folded shape, but the present invention is not limited to this. It is also possible to apply the present invention to a shape that does not have.

Non-aqueous electrolyte secondary batteries to which the configuration described in detail in the present embodiment can be applied include, for example, 920 size (outer diameter φ9.0 mm), which is a general size of coin-type non-aqueous electrolyte secondary batteries. 5 mm×height 2.0 mm), 621 size (external diameter φ6.8 mm×height 2.1 mm), and batteries of various sizes.

(gasket)
As shown in FIG. 1 , the gasket 40 is formed in an annular shape along the inner peripheral surface of the positive electrode can 12 , and the front end portion 22 a of the negative electrode can 22 is arranged inside the annular groove 41 .
Further, for example, the material of the gasket 40 is preferably a resin having a heat distortion temperature of 230° C. or higher. If the heat distortion temperature of the resin material used for the gasket 40 is 230° C. or higher, heat is generated when the non-aqueous electrolyte secondary battery 1 is used or stored in a high-temperature environment, or when the non-aqueous electrolyte secondary battery 1 is in use. Even if this occurs, it is possible to prevent the electrolyte 50 from leaking due to significant deformation of the gasket.

Examples of materials for the gasket 40 include polypropylene resin (PP), polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin. (PFA), polyetheretherketone resin (PEEK), polyethernitrile resin (PEN), polyetherketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexanedimethylene terephthalate resin, polyether Plastic resins such as sulfone resins (PES), polyaminobismaleimide resins, polyetherimide resins, and fluorine resins such as polytetrafluoroethylene (PTFE) and ethylene-tetrafluoroethylene (ETFE) can be used. Among these, the use of any one of PP, PPS, and PEEK for the gasket 40 can prevent the gasket from significantly deforming during use or storage in a high-temperature environment, and can seal the non-aqueous electrolyte secondary battery. It is preferable from the viewpoint of further improving the properties.

Also, the gasket 40 can be suitably used by adding glass fiber, mica whisker, fine ceramic powder, or the like to the above material in an amount of 30% by mass or less. By using such a material, it is possible to prevent the electrolyte solution 50 from leaking due to significant deformation of the gasket due to high temperatures.

Further, the inner surface of the annular groove of the gasket 40 may be coated with a sealing agent. As such a sealing agent, asphalt, epoxy resin, polyamide resin, butyl rubber adhesive, or the like can be used. Also, the sealant is applied to the inside of the annular groove 41 and then dried before use.

The gasket 40 is sandwiched between the positive electrode can 12 and the negative electrode can 22, and at least a portion of the gasket 40 is compressed. 1 can be reliably sealed and the gasket 40 is not broken.

(Electrolytes)
The non-aqueous electrolyte secondary battery 1 of the present embodiment uses an electrolyte (electrolyte solution) 50 containing at least an organic solvent and a supporting salt. In the case of the electrolytic solution 50, the organic solvent is any one of propylene carbonate (PC), which is a cyclic carbonate solvent, ethylene carbonate (EC), which is a cyclic carbonate solvent, and ethyl methyl carbonate (EMC), which is a chain carbonate solvent, or A mixed solvent is preferably used. Alternatively, an ionic liquid or a solid electrolyte may be used as the electrolyte.
In the case of the electrolytic solution, a supporting salt is usually dissolved in a non-aqueous solvent such as an organic solvent.

As the supporting salt used in the electrolytic solution 50, a known Li compound that is added as a supporting salt to the electrolytic solution in the non-aqueous electrolyte secondary battery can be used, and is not particularly limited. For example, in consideration of thermal stability, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate, lithium bisperfluoromethylsulfonylimide, lithium bisperfluoroethylsulfonylimide, lithium bistrifluoro methanesulfonimide (Li(CF ₃ SO ₂ ) ₂ N) and the like. Among these, it is particularly preferable to use Li(CF ₃ SO ₂ ) ₂ N or LiPF ₆ as the supporting salt, since the heat resistance of the electrolytic solution is enhanced and the decrease in capacity at high temperatures can be suppressed.
In addition, the supporting salt may be used alone or in combination of two or more.

The content of the supporting salt in the electrolytic solution 50 can be determined in consideration of the type of the supporting salt and the type of the positive electrode active material described later. 1.8 mol/L is more preferred, and approximately 1.5 mol/L is particularly preferred.
If the concentration of the supporting salt in the electrolytic solution 50 is too high or too low, the electrical conductivity may decrease and the battery characteristics may be adversely affected. The amount is preferably regulated within the above range.

(positive electrode)
In the non-aqueous electrolyte secondary battery 1 of the present embodiment, as an example of the positive electrode 10, a mixture containing a positive electrode active material made of lithium cobaltate (LiCoO ₂ ), a conductive aid, and a binder (binder) , a lubricant can be used.

A positive electrode active material made of lithium cobalt oxide is used for the positive electrode 10, and the negative electrode ₂₀ , which will be described later, contains lithium titanate _{( Li4Ti5O12} ) as a negative electrode active material. Also, a CTL battery with a high capacity can be configured.
The positive electrode active material is preferably the combination described above, but other lithium-transition metal composite oxides listed in the description of the positive electrode 10 described above may also be used.

When a lithium transition metal composite oxide such as lithium cobalt oxide is used as the positive electrode active material, it is granulated as described below to form a granular mixture having a particle size of about 75 to 500 μm, after adding a lubricant. Molding into pellets is preferred.
In addition, when molding into pellets in the present embodiment, a granular mixture of 250 to 500 μm as described later is used after adding a lubricant to the granular mixture of 75 to 500 μm. is more preferred.
The particle size (D50) of the lithium cobalt oxide used in preparing the granular mixture is not particularly limited, but is preferably 2 to 20 μm, more preferably 4 to 8 μm, for example.
In addition, the "particle diameter (D50) of the positive electrode active material" in the present invention means a particle diameter measured by a laser diffraction method and a median diameter.

The content of the positive electrode active material in the positive electrode 10 is determined in consideration of the discharge capacity required for the non-aqueous electrolyte secondary battery 1, and is preferably in the range of 50 to 95% by mass, for example. If the content of the positive electrode active material is equal to or higher than the lower limit of the preferred range, a sufficient discharge capacity can be easily obtained, and if it is equal to or lower than the preferred upper limit, the positive electrode 10 can be easily molded.

The positive electrode 10 contains a conductive aid (hereinafter, the conductive aid used in the positive electrode 10 may be referred to as a "positive conductive aid").
Examples of positive electrode conductive aids include carbonaceous materials such as graphite, carbon, furnace black, ketjen black, and acetylene black.
As for the positive electrode conductive aid, one of the above may be used alone, or two or more thereof may be used in combination.
Also, the content of the positive electrode conductive aid in the positive electrode 10 is preferably 4 to 40% by mass, more preferably 7 to 20% by mass. If the content of the positive electrode conductive aid is at least the lower limit value of the preferable range, sufficient conductivity can be easily obtained. In addition, it becomes easy to shape|mold when shape|molding an electrode in a pellet form. On the other hand, when the content of the positive electrode conductive additive in the positive electrode 10 is equal to or less than the upper limit value of the preferable range, the positive electrode 10 can easily obtain a sufficient discharge capacity.

The positive electrode 10 contains a binder (hereinafter, the binder used for the positive electrode 10 may be referred to as "positive electrode binder or positive electrode binder").
The positive electrode binder is preferably made of polytetrafluoroethylene (PTFE).
By using PTFE as the positive electrode binder, the fibrous PTFE can effectively bind the positive electrode active material and the conductive aid.
By using PTFE as the positive electrode binder, a sufficient discharge capacity can be obtained and a large current can be supplied. From the viewpoint of obtaining the above effects more significantly, it is preferable to use PTFE as the positive electrode binder.
The content of the positive electrode binder in the positive electrode 10 can be, for example, 1 to 20% by mass.

As the lubricant, a lubricant that suppresses adhesion between particles can be selected, and a hydrophobic silica lubricant such as hydrophobic fumed silica can be used. Hydrophobic fumed silica is a type of hydrophobic silica whose surface is treated with various silanes such as dimethylchlorosilane, and has a specific surface area (BET) of 90 to 130 m ² /g. By adding a small amount of the above-mentioned lubricant, the granular mixture becomes a state in which it can slide somewhat in the mold, and the releasability after molding is improved.
The hydrophobic silica used in the present embodiment is not limited to hydrophobic fumed silica, and may be silica produced by an arc method other than fumed silica (flame method silica).

The content of the lubricant in the positive electrode 10 can be in the range of 0.5 to 2.0% by mass relative to the total mass of the mixture. If the content of the lubricant is less than 0.5% by mass, the releasability from the mold is insufficient. Moreover, the fillability into the mold also deteriorates. If the content of the lubricant exceeds 2.0% by mass, the amount of the active material in the electrode is relatively reduced, making it difficult to obtain sufficient characteristics (capacity) when used as a battery.

The size of the positive electrode 10 is determined according to the size of the non-aqueous electrolyte secondary battery 1 .
The thickness of the positive electrode 10 is also determined according to the size of the non-aqueous electrolyte secondary battery 1. If the non-aqueous electrolyte secondary battery 1 is a coin type for various electronic devices, for example, the thickness It is formed to have a thickness of about 300 to 1000 μm.
As the positive electrode current collector 14, a conventionally known one can be used, and examples thereof include a conductive resin adhesive using carbon as a conductive filler.

"Manufacturing method of positive electrode"
The method for producing a pellet-shaped positive electrode includes a granulation step of preparing a positive electrode mixture into granules having a predetermined particle size from each constituent raw material, and press-molding the granular positive electrode mixture into a pellet shape. at least a tableting step.
(Granulation process)
The granulation step is a step of putting the positive electrode active material, the conductive aid, and the binder into a mixing stirrer and mixing and stirring.
The positive electrode material mixture applied in the present embodiment can use the material constituting the positive electrode of the non-aqueous electrolyte secondary battery described above. As an example, lithium cobalt oxide can be used as the positive electrode active material, graphite can be used as the conductive aid, and PTFE can be used as the binder.
Here, in this embodiment, the positive electrode active material, the conductive aid, and the binder are all prepared in the form of powder. In general, the binder used when mixing the materials constituting the electrode may be supplied in the form of powder or dispersed in a liquid or the like.
When supplied in the form of powder, it is easy to handle, but if it is not sufficiently stirred, it may not be sufficiently dispersed in the positive electrode mixture and may not sufficiently exhibit its function as a binder. Further, when the binder is dispersed in a liquid form and used, it is sufficiently dispersed in the positive electrode mixture by stirring, but there is a problem in that it is difficult to control the viscosity for granulating into granules. In the case of this embodiment, the positive electrode mixture can be easily formed into granules having a predetermined particle size by using PTFE powder as the binder and by employing a mixing stirrer.

The mixing stirrer used in the present embodiment is required to finely shear the PTFE used as the binder and control the viscosity in addition to sufficient stirrability.
As the mixing stirrer, it is preferable to use a mixing stirrer that can apply a strong shearing force to the positive electrode mixture by reducing the dead space of stirring by revolving and rotating a plurality of blades (planetary motion).
In the present embodiment, in addition to the powdery positive electrode active material, conductive aid, and binder described above, water is added to the mixing stirrer and stirred to agglomerate these powders into granules. A positive electrode mixture having a shape is prepared. The amount of water added at this time is 10 to 30%, more preferably 14 to 20%, based on the total weight of the positive electrode active material, the conductive aid, and the binder. can be isolated in good yields.

In order to carry out granulation, various mixing stirrers such as Supermixer, Loedigemixer, Spartanreuser, and Planetary mixer can be used.
According to the present embodiment, the amounts of the positive electrode active material (lithium cobaltate), the conductive agent (graphite), and the binder (polytetrafluoroethylene) constituting the positive electrode mixture are set to the above values, and Mixing granulation using a mixer is preferred.
As a result, a mixture of granules having a desired particle size can be obtained by using an easy-to-handle mixing and agitating step of pulverizing each raw material, adding water, and agitating.

When mixing and stirring, it is preferable to revolve and rotate multiple blades to apply a strong shearing force to the material for processing such as dispersion. It is preferable to disperse in By doing so, it becomes possible to produce a granular mixture with a desired particle size at a high yield with an appropriate amount of water input.

As an example of the mixing and stirring conditions, for example, materials can be put into a mixing stirrer at room temperature in an air atmosphere, and the revolution speed of the blade: 35 rpm, and the rotation speed: 92 rpm, but the conditions are not limited to these conditions. Moreover, it is preferable to add and mix the positive electrode active material, the conductive aid, and the binder before adding water as the solvent. An example of the mixing conditions is, for example, a blade revolution speed of 8 rpm and a rotation speed of 22 rpm, but is not limited to this. There are no particular restrictions on the time for mixing and stirring, but granulation can be performed by kneading for about 10 minutes to several tens of minutes, for example.
Then, the granules granulated by the mixing stirrer are dried to remove moisture. As drying conditions, general conditions for removing moisture can be applied. As an example of the drying conditions, a drying apparatus such as an oven can be used to heat in the air at 120° C. for 12 hours, but the conditions are not limited to these.

The dried granules are further sieved and screened to select and take out the positive electrode material mixture having a desired particle size range. In particular, a positive electrode mixture having a particle size range of 75 to 500 μm, more preferably 250 to 500 μm is preferable because it is easy to handle in the tableting step described below.
After granulation, the dried granules also contain fine particles of less than 75 μm, so the dried granules are sieved for the purpose of removing these fine particles. , 75 to 500 μm in particle size range.

If the particle size of the granulated mixture is less than 75 μm, there is a problem that when the mixture is supplied to the mold, the pipe becomes clogged with the finely powdered mixture, making it impossible to supply the mixture.
When the particle size of the granular mixture exceeds 500 μm, there is a problem that the amount of the mixture filled in the mold varies and the weight variation of the positive electrode increases.
In addition, assuming that the granular mixture of 75 to 500 μm is selected, it should be classified as a positive electrode mixture of 250 to 500 μm in order to obtain a sufficiently high yield in the manufacturing method described later. is more preferred.
Further, in order to obtain a granular mixture with a particle size of 250 to 500 μm in a good yield, it is preferable to granulate with an amount of water added of 10 to 30% with respect to the total mass of the mixture as described above. Further, in order to obtain a granular mixture with a particle size of 250 to 500 μm in a better yield, it is more preferable to set the amount of water to be added in the range of 14 to 20% as described above.

(Tabletting process)
Next, the tableting process will be described. The tableting step is a step of preparing a pellet-shaped positive electrode by filling a mold with the positive electrode material mixture having a predetermined particle size range prepared by the above-described granulation step and performing press molding.
As an example, the mold is made of cemented carbide, has a concave portion formed in a bottomed cylindrical shape, and has a die to be filled with the positive electrode mixture, and a positive electrode mixture whose tip is formed in a cylindrical shape and filled in the die. It consists of a punch that compresses the In addition to this mold, the pressing device has a feeder equipped with a mechanism for filling the positive electrode mixture and a mechanism for taking out the produced pellets.

In the tableting step, first, the concave portion of the die of the mold is filled with the granular positive electrode mixture stored in the feeder of the pressing device. Then, a punch is pressed from above the die to apply sufficient pressure to compress the positive electrode mixture, thereby forming a pellet-shaped positive electrode such as a flat disc or flat cylinder. The pressure during pressure molding is determined in consideration of the type of the positive electrode conductive aid, and can be, for example, 0.2 to 6 ton/cm ² .
The formed pellet-shaped positive electrode can be removed by being moved to a removal section by a feeder.
A granular mixture having a particle size of 250 to 500 μm obtained by the above-described granulation process can be obtained with a good yield, and the angle of repose of the granular mixture is 35° or less. Therefore, it is easy to put into the mold.

(Addition of lubricant)
In this embodiment, a lubricant can be added to the granular positive electrode mixture prior to the tableting step described above. When PTFE is used as the binder, the granules of the positive electrode mixture are highly viscous, and the granules easily adhere to each other, which may make it difficult to fill the mold with the positive electrode mixture. In addition, the positive electrode mixture and pelletized positive electrode after pressing tend to adhere to the mold and the feeder of the pressing device, which may easily cause troubles in the device.
In this embodiment, by adding a lubricant to the positive electrode mixture, the viscosity of the surface of the granules is adjusted to be small, the filling of the positive electrode mixture into the mold is facilitated, and the releasability from the mold, etc. is enhanced. be able to.

As a lubricant, if the surface has water repellency, a releasability effect can be obtained.
In order to disperse uniformly on the surface of the positive electrode material mixture granules and sufficiently exhibit the releasability effect, it is preferable to use particles having a nano-order particle size.
As such a lubricant, for example, hydrophobic silica such as hydrophobic fumed silica having a nano-sized particle size can be used. If the amount of the lubricant is large, the effect of releasability can be enhanced.
The amount of the lubricant to be added is preferably 0.5 to 5.0% by weight, more preferably 0.5 to 2.0% by weight, based on the total weight of the positive electrode mixture.

By adding and mixing hydrophobic fumed silica, which is nano-sized fine particles, silica can be attached to the surface of the granules. Since this silica is hydrophobic, the adhesion to the surface of the granules can be reduced by adding the silica in the amount described above. As a result, the fluidity of the positive electrode material mixture can be improved, the supply to the mold can be facilitated, and the releasability of the molded pellet from the mold can be improved to maintain the shape of the pellet.
Therefore, the positive electrode 10 can be safely removed from the mold without causing defects such as cracks in the positive electrode 10 at the time of demolding, and the yield in manufacturing the pellet-shaped positive electrode 10 can be improved.

When adding the lubricant to the positive electrode mixture and mixing, various mixing stirrers can be used. For example, it is possible to use the various mixing stirrers used during the mixing and stirring described above. The surface viscosity of the positive electrode mixture can be reduced by putting the positive electrode mixture and the lubricant into a mixing stirrer and sufficiently mixing them.
As an example of mixing and stirring conditions, for example, materials are put into a mixing stirrer at room temperature and in an air atmosphere, and the revolution speed of the blade: 35 rpm and the rotation speed: 92 rpm. Not limited to conditions.

As described above, it is possible to efficiently produce positive electrode pellets using a positive electrode mixture that is excellent in handling properties and that is mixed with PTFE.

(negative electrode)
In the non-aqueous electrolyte secondary battery 1 of the present embodiment, as an example of the negative electrode 20, a negative electrode active material made of lithium titanate (Li ₄ Ti ₅ O ₁₂ ), a conductive aid made of graphite, and a binder Use one that contains

By using a negative electrode active material made of lithium titanate for the negative electrode 20 and using a positive electrode active material made of lithium cobaltate as the positive electrode 10, the operating voltage is as high as 2 V or higher and the capacity is high. A CTL battery can be constructed. Although the above-described combination of the negative electrode active materials is desirable, other materials listed in the description of the negative electrode 20 described above may be used.

When lithium titanate is used as the negative electrode active material, its particle size (D50) is not particularly limited, and is preferably 3 to 7 μm, more preferably 4 to 6 μm, for example.
If the particle size (D50) of the negative electrode active material is less than the lower limit of the preferred range, the reactivity of the non-aqueous electrolyte secondary battery increases when exposed to high temperatures, making it difficult to handle. , the discharge rate may decrease.

The content of the negative electrode active material in the negative electrode 20 is determined in consideration of the discharge capacity required for the non-aqueous electrolyte secondary battery 1, and is preferably 50% by mass or more, more preferably 60 to 80% by mass.
In the negative electrode 20, if the content of the negative electrode active material made of the above material is equal to or higher than the lower limit of the preferred range, a sufficient discharge capacity can easily be obtained. Cheap.

The negative electrode 20 contains graphite as a conductive aid (hereinafter, the conductive aid used in the negative electrode 20 may be referred to as a “negative conductive aid”) in an amount of 7% by mass or more and 10% by mass with respect to the total mass of the negative electrode 20. Including less than The non-aqueous electrolyte secondary battery 1 of the present embodiment uses lithium cobaltate as a positive electrode active material in the positive electrode 10 and lithium titanate as a negative electrode active material in the negative electrode 20. Further, graphite (a conductive agent) contained in the negative electrode is used. By limiting the content of the non-aqueous electrolyte secondary battery 1 to the above range, the current flow in the negative electrode is improved while ensuring a sufficient capacity for the non-aqueous electrolyte secondary battery 1 . As a result, even with a small size, it is possible to obtain a sufficient discharge capacity and supply a large current.

Note that if the content of graphite (conductive assistant) in the negative electrode 20 is less than 7% by mass, the conductivity is lowered and the discharge current characteristics are also lowered.
On the other hand, when the content of graphite (conductive assistant) in the negative electrode 20 is 10% by mass or more, the content of the negative electrode active material in the negative electrode 20 is relatively decreased, resulting in a decrease in discharge capacity.
Further, from the viewpoint of obtaining the above effect more remarkably, the content of the conductive aid made of graphite in the negative electrode 10 is more preferably in the range of 8 to 9% by mass with respect to the total mass of the negative electrode 20. preferable.

The negative electrode 20 contains a binder (hereinafter, the binder used for the negative electrode 20 may be referred to as "negative electrode binder or negative electrode binder").
Examples of negative electrode binders include polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), polyacrylic acid (PA), polyimide (PI), and polyimideamide (PAI). It is preferred to use polymers.

Moreover, one type of the negative electrode binder may be used alone, or two or more types may be used in combination. When PA is used as the negative electrode binder, it is preferable to adjust the PA to pH 3 to 10 in advance. For adjusting the pH in this case, for example, an alkali metal hydroxide such as lithium hydroxide or an alkaline earth metal hydroxide such as magnesium hydroxide can be used.
The content of the negative electrode binder in the negative electrode 20 is, for example, 1 to 20 mass %.

The size and thickness of the negative electrode 20 are the same as those of the positive electrode 10 .
That is, the thickness of the negative electrode 20 is determined according to the size of the non-aqueous electrolyte secondary battery 1. If the non-aqueous electrolyte secondary battery 1 is a coin type for various electronic devices, for example, the thickness It is formed to have a thickness of about 300 to 1000 μm.

As a method of manufacturing the negative electrode 20, for example, the above material is used as the negative electrode active material, and if necessary, a negative electrode conductive aid and/or a negative electrode binder are mixed to prepare a negative electrode mixture, and this negative electrode mixture is prepared. A method of pressure-molding the mixture into an arbitrary shape can be employed.
In this case, the pressure during pressure molding is determined in consideration of the type of the negative electrode conductive aid, etc., and can be, for example, 0.2 to 5 tons/cm ² .

Also, the negative electrode current collector 24 can be configured using the same material as the positive electrode current collector 14 . For example, a conductive resin adhesive using carbon as a conductive filler can be exemplified.

(separator)
The separator 30 is interposed between the positive electrode 10 and the negative electrode 20, and an insulating film having high ion permeability, excellent heat resistance, and predetermined mechanical strength is used.
As the separator 30, any material that has been conventionally used as a separator for non-aqueous electrolyte secondary batteries and that satisfies the above characteristics can be applied without any limitation. Examples include alkali glass, borosilicate glass, quartz glass, lead glass, and the like. glass, polypropylene (PP), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethylene terephthalate (PET), polyamideimide (PAI), polyamide, polyimide (PI), aramid, cellulose, fluororesin, ceramics, etc. Examples include nonwoven fabrics and fibers made of resin. As the separator 30, among the above, those made of a porous polymer material such as polypropylene (PP) resin can provide a separator having a high ion permeability while ensuring sufficient mechanical strength. It is particularly preferable because the internal resistance of the secondary battery is reduced and the discharge capacity is further improved.
The thickness of the separator 30 is determined in consideration of the size of the non-aqueous electrolyte secondary battery 1, the material of the separator 30, etc., and can be, for example, about 5 to 300 μm.

"Manufacturing method of non-aqueous electrolyte secondary battery"
A method for manufacturing a non-aqueous electrolyte secondary battery according to the present embodiment includes an electrode manufacturing step of manufacturing a positive electrode and a negative electrode, a pre-assembling step of manufacturing a positive electrode unit and a negative electrode unit using the positive electrode and the negative electrode, and a positive electrode unit and a negative electrode unit. and an assembling process of assembling a battery using the same as the main process.
Among the electrode preparation steps, the step of preparing the positive electrode has been described in detail in the method of manufacturing the positive electrode pellets described above. In addition, the step of manufacturing the negative electrode includes the case of forming pellets from the powder material such as spinel type lithium titanate (Li ₄ Ti ₅ O ₁₂ ) and SiO described above as the negative electrode active material, and the case of forming aluminum etc. on the surface of the negative electrode can. It is different from the case of forming a metal and alloying it with lithium.

Various known negative electrodes can be employed as the negative electrode of the non-aqueous electrolyte secondary battery used in this embodiment.
For example, the negative electrode can be a negative electrode pellet formed by press-molding a negative electrode mixture composed of a mixture containing a negative electrode active material, a conductive aid, and a binder as main constituent materials. Alternatively, the negative electrode can be formed by alloying lithium with a metal such as aluminum or an aluminum alloy formed on the surface of the negative electrode can.
When using a negative electrode pellet as a negative electrode, _spinel type lithium titanate _{( Li4Ti5O12} ), SiO, etc. can be used as a negative electrode active material, for example. At this time, for example, a carbon material such as graphite can be used as the conductive aid. As the binder, various high molecular compounds such as butyl rubber, fluorine compounds, polyacrylic acid and the like can be used. In this case, the negative electrode pellets are produced by mixing, granulating, and compressing the negative electrode active material, the conductive aid, and the binder in the same manner as the method for producing the positive electrode pellets, which will be described later. It can be a step of manufacturing.

In the pre-assembly step, the positive electrode pellets and negative electrode pellets produced by the method described above are fixed to the positive electrode can and the negative electrode can, respectively, to produce the positive electrode unit and the negative electrode unit.
As a fixing method, for example, a paste-like conductive adhesive made by dispersing a carbon material in a resin such as phenolic resin is applied to the inner bottom surfaces of the positive electrode can and the negative electrode can, and then the positive electrode pellet and the negative electrode pellet are attached to each other. It can be attached to the inner bottom surfaces of the positive electrode can and the negative electrode can and dried. Moreover, when using SiO as a negative electrode active material, metal lithium is stuck on the surface of a negative electrode pellet. Additionally, gaskets and separators are attached to either the positive or negative unit.
In the assembly process, after injecting an electrolytic solution into each of the positive electrode unit and the negative electrode unit produced in the previous assembly process, the positive electrode unit and the negative electrode unit are overlapped, and the opening of the positive electrode can is crimped to the negative electrode can using a sealing machine. This is done by sealing the battery.
As described above, the desired coin-shaped non-aqueous electrolyte secondary battery can be produced by applying the above-described steps.

[Use of non-aqueous electrolyte secondary battery]
As described above, the non-aqueous electrolyte secondary battery 1 of the present embodiment can obtain a sufficient discharge capacity and can supply a large current even if it is small in size. It is suitable for use as a power source for digital watches or analog watches with various functions such as, and various small electronic devices.

As described above, according to the non-aqueous electrolyte secondary battery 1 configured using the positive electrode 10 according to the embodiment of the present invention, lithium cobaltate is used as the positive electrode active material in the positive electrode 10, and lithium cobalt oxide is used as the negative electrode active material in the negative electrode 20. Since lithium titanate is used, it is possible to obtain a sufficient discharge capacity and supply a large current even with a small size while securing a sufficient capacity as a non-aqueous electrolyte secondary battery. be possible.
Furthermore, in the above-described structure, since the granular mixture constituting the positive electrode 10 is molded with a lubricant in a suitable range of 0.5 to 2.0%, the mixture can be smoothly injected into the mold. In addition, it is excellent in releasability when the molded product is taken out after molding. Therefore, it is possible to reliably obtain the positive electrode 10 as a non-defective product free from cracks or the like at the time of demolding.
Therefore, the inclusion of the lubricant in a suitable range of 0.5 to 2.0% contributes to the improvement of the yield when manufacturing the positive electrode 10 in the form of pellets.

EXAMPLES Next, the present invention will be described more specifically by showing examples and comparative examples. It should be noted that the scope of the present invention is not limited by this embodiment. The method for manufacturing a non-aqueous electrolyte secondary battery according to the present invention can be modified appropriately without departing from the gist of the present invention.

As a positive electrode mixture, 90% by mass of lithium cobalt oxide (LiCoO ₂ ), 8.0% by mass of graphite powder (SP-270 manufactured by Nippon Graphite Co., Ltd.), and 2.0% by mass of polytetrafluoroethylene (PTFE) were mixed. 20% of the total weight of water was added to the mixture, and the mixture was mixed and stirred for 20 minutes with a mixer stirrer.
The mixture obtained by this mixing and stirring treatment was dried by heating to obtain mixed particles of fine particles having a particle size of less than 75 μm and granules having a particle size of 75 to 500 μm.
A positive electrode mixture composed of granular granules having a particle size of 250 to 500 μm was selected and taken out from the mixed particles by sieving (test sieve manufactured by Tokyo Screen Co., Ltd.). Through the granulation process as described above, a granular mixture (Example 1) having a particle size of 250 to 500 μm was obtained.
Table 1 below shows the measurement results of particle size distribution, input water amount, yield (%) and repose angle (°) of the obtained granular mixture (Example 1). The angle of repose was measured by the method specified in JISR9301-2-2:1999.

(Evaluation of granulation, measurement of angle of repose)
Next, the granular mixtures of Examples 2 to 4 and Comparative Example 5 were obtained by changing only the amount of water supplied to the mixing stirrer in the method for producing the mixture of Example 1. Table 1 shows the measurement results of particle size distribution, input water amount, yield (%) and angle of repose (°) of these mixtures.

As the results shown in Table 1 show, when the amount of water added during granulation is in the range of 10 to 30% by mass with respect to the total mass of the positive electrode active material, the conductive aid and the binder, the angle of repose is 30 to 30. It was found that 40° granules could be obtained.
Further, a range of 14 to 20% of added water is more preferable, and granules having an angle of repose of about 30° could be obtained by setting the amount of added water to 14 to 20%.
In terms of yield, it can be judged that the yield is poor when there are many granules of less than 75 μm. Therefore, in Comparative Example 5 in which 79.5% of the granules are less than 75 μm, the yield of granules with a particle size of 250 to 500 μm can be judged to be poor. Also, in Example 2, the yield of granules with a particle size of 250 to 500 μm was 6.9%, and it can be judged that the yield of granular granules is poor. It should be noted that when the amount of water added increases, the granules tend to become paste (slurry).
From the above results, when the yield of granules having a particle size of 250 to 500 μm is emphasized, it is desirable that the amount of water input in the granulation process is in the range of 14% or more and 20% or less.

Although not shown in Table 1, when mixing and stirring is performed at an amount of water input of less than 10%, the fine powder does not bind, and a granular granule cannot be obtained. As a result, the entire mixture became slurry and no granular granules were obtained as in the case where the water content was small.

(Pellet preparation (tabletting) evaluation)
Next, using the positive electrode material mixture granules obtained in the above-described examples, it was evaluated whether or not pellets having a desired shape could be obtained.
To the granules having a particle size of 250 to 500 μm obtained in Example 1, hydrophobic fumed silica (hydrophobic fumed silica; manufactured by Nippon Aerosil Co., Ltd. R972) as a lubricant was added in an amount of 0.00 to the total weight of the granules. 5 mass% added mixture (Example 7), 1.0 mass% added mixture (Example 8), 2.0 mass% added mixture (Example 9), and a lubricant added Evaluation described below was performed using a mixture (Comparative Example 6) that was not used.
Here, the lubricant is added by adding 400 g of the granular positive electrode mixture of Example 1 described above, and 2 g, 4 g, and 8 g of hydrophobic fumed silica in Examples 7, 8, and 9, respectively. Mixed for 20 minutes.

(Powder feeding evaluation)
These positive electrode mixtures were separately weighed, put into a mold individually, and pressure-molded at a pressure of 6 t/cm ² to produce a disk-shaped pellet-shaped positive electrode (φ6.3×t0.7 mm). The fillability (evaluation of feeding powder) into the mold when using each positive electrode mixture, the presence or absence of adhesion of the mixture to the mold after press molding, and the presence or absence of chipping of the molded product were examined.
On the other hand, the mixture (Example 1) to which no lubricant was added was regarded as the mixture of Comparative Example 6. The presence or absence of cracks in the molded product was examined. The above results are summarized in Table 2 below.

In Table 2, the evaluation item of powder supply indicates whether or not the granules could be supplied to every corner of the mold during molding.

(Molding evaluation)
In Table 2, the item for evaluation of moldability indicates whether or not the pellet-shaped positive electrode taken out was chipped. x means that the pellet-shaped positive electrode is chipped.

As the results shown in Table 2 show, when a positive electrode mixture having a particle size of 250 to 500 μm containing 0.5 to 2.0% by mass of hydrophobic silica was tableted to form a pellet-shaped positive electrode, the mold was released. It can be seen that the addition of a lubricant is advantageous in terms of properties. In this case, it is preferable to add the lubricant in an amount of 0.5 to 2.0% by mass based on the positive electrode mixture using hydrophobic silica.
Comparative Example 6 (Example 1) is an acceptable product in terms of powder feeding.

DESCRIPTION OF SYMBOLS 1... Non-aqueous electrolyte secondary battery, 2... Housing container, 10... Positive electrode, 12... Positive electrode can, 14... Positive electrode current collector, 20... Negative electrode, 22... Negative electrode can, 24... Negative electrode current collector, 30... Separator, 40... Gasket, 50... Electrolyte (electrolytic solution).

Claims (10)

A granular mixture containing a particulate positive electrode active material made of a transition metal composite oxide, a conductive agent, a binder made of polytetrafluoroethylene (PTFE), and a lubricant ,
50 to 95% by mass of the positive electrode active material, 4 to 40 % by mass of the conductive aid, and 1.5 to 2.5% by mass of the binder with respect to the total mass of the mixture,
A positive electrode mixture for a non-aqueous electrolyte secondary battery, characterized by having a particle size of 75 to 500 μm and an angle of repose of 35° or less. The transition metal composite oxide is any one of lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), and lithium manganate (Li ₄ Mn ₅ O ₁₂ ). The positive electrode mixture for a non-aqueous electrolyte secondary battery according to claim 1, characterized in that: 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the conductive agent is one or more of graphite, carbon, furnace black, ketjen black, and acetylene black. positive electrode mixture. The positive electrode mixture for non-aqueous electrolyte secondary batteries according to any one of claims 1 to 3 is included,
Hydrophobic silica is added as the lubricant in a mass ratio of 0.5 to 2.0% with respect to the positive electrode mixture for the non-aqueous electrolyte secondary battery ,
A positive electrode for a non-aqueous electrolyte secondary battery, comprising a pellet-shaped compression-molded body. A nonaqueous electrolyte secondary battery comprising the positive electrode for a nonaqueous electrolyte secondary battery according to claim 4 . A method for manufacturing a positive electrode for a coin-shaped non-aqueous electrolyte secondary battery, comprising:
A positive electrode active material made of a transition metal composite oxide , a conductive agent, a binder made of polytetrafluoroethylene (PTFE) , and a lubricant , which are each in powder form, are put into a mixing stirrer, and water is added. In addition, a granulation step of mixing and stirring to take out a positive electrode mixture having a particle size of 75 to 500 μm in a granular form;
A tableting step of supplying the positive electrode mixture to a mold and compressing and molding it into a pellet shape by pressing;
with at least
The ratio of the amount of the positive electrode active material, the conductive aid, and the binder added is 50 to 95%, 4 to 40 %, and 1.5 to 2.5% by mass, respectively, with respect to the total mass of these. range and
By setting the amount of the water input to be in the range of 14 to 20 % by mass with respect to the total mass of the positive electrode active material, the conductive aid, and the binder,
A method for producing a positive electrode for a coin-shaped non-aqueous electrolyte secondary battery, comprising obtaining a positive electrode mixture having an angle of repose of 35° or less. 7. The method for producing a positive electrode for a coin-shaped non-aqueous electrolyte secondary battery according to claim 6, wherein hydrophobic silica is used as the lubricant in a mass ratio of 0.5 to 2.0% with respect to the positive electrode mixture. . Any one of lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium titanate (Li ₄ Ti ₅ O ₁₂ ), and lithium manganate (Li ₄ Mn ₅ O ₁₂ ) as the transition metal composite oxide. 8. The method for producing a positive electrode for a coin-shaped non-aqueous electrolyte secondary battery according to claim 6 or 7, wherein the positive electrode is used. 9. The conductive aid according to any one of claims 6 to 8, wherein one or more of graphite, carbon, furnace black, ketjen black, and acetylene black is used. A method for manufacturing a positive electrode for a coin-type non-aqueous electrolyte secondary battery. A method for manufacturing a coin-type non-aqueous electrolyte secondary battery, comprising using the positive electrode for a non-aqueous electrolyte secondary battery obtained by the manufacturing method according to any one of claims 6 to 9.

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