JP2971403B2 - Non-aqueous solvent secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous solvent secondary battery having an improved positive electrode .

[0002]

2. Description of the Related Art In recent years, lithium batteries using lithium, a lithium alloy or a compound capable of inserting and extracting lithium ions as a negative electrode active material have attracted attention as high energy density batteries. Among them, primary batteries using manganese dioxide (MnO ₂ ), carbon fluoride ((CF ₂ ) _n ), thionyl chloride (SOCl ₂ ), etc. as a positive electrode active material have already been used as backup batteries for calculators, watches, and memories. It is heavily used.

Further, in recent years, with the reduction in size and weight of various electronic devices such as VTRs, communication devices, and personal computers, the demand for high-energy-density secondary batteries as power sources for them has been increasing. In response to such demands, research on non-aqueous solvent secondary batteries using lithium as a negative electrode active material has been actively conducted.

In a non-aqueous solvent secondary battery, a negative electrode is made of lithium, a lithium alloy, or a carbonaceous material that stores and releases lithium ions, and propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate is used as an electrolyte. (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC),
1,2-dimethoxyethane (DME), γ-butyl lactone (γ-BL), tetrahydrofuran (THF), 2,
LiClO ₄ , LiBF ₄ , LiAsF ₆ , L in a non-aqueous solvent of -methyltetrahydrofuran (2-MeTHF)
iPF _6, LiCF ₃ obtained by dissolving a SO _3, a lithium salt of LiAlCl ₄ is utilized. Further, as the positive electrode, a positive electrode containing an active material utilizing intercalation or doping of a layered compound has been attracting attention.

[0005] Chalcogenide compounds are known as active materials utilizing the intercalation of the layered compounds. Although the positive electrode containing the chalcogenide compound has relatively excellent cycle characteristics, the electromotive force is low, and the practical discharge voltage is at most about 2 V even when lithium metal is used as the negative electrode. However, it did not satisfy the high electromotive force required.

A non-aqueous solvent secondary battery having a high electromotive force can be realized, and V ₂ O ₅ , V ₆ O ₁₃ , LiCoO ₂ ,
LiNiO ₂ is known. As an active material utilizing the doping phenomenon, there is LiMn ₂ O ₄ . In particular, a positive electrode containing LiCoO ₂ or LiNiO ₂ as an active material has an electromotive force of about 4 V, and has a large theoretical energy density of 1 kWh / kg per positive electrode active material.

However, when LiCoO ₂ is used as the active material, it is difficult to reduce the battery manufacturing cost due to the resource constraints of cobalt. On the other hand, LiNiO ₂ , which is being studied as an alternative compound to LiCoO ₂ , is LiC
Although higher capacity and lower cost can be expected as compared with oO ₂ , it is difficult to synthesize and it is difficult to synthesize a large amount of those having a uniform crystal structure.

[0008] LiNiO ₂ having a non-homogeneous crystal structure often causes lithium ions and nickel ions to be disordered. In a crystal structure with many disorder, the valence of nickel ions is less than 3, and the amount of lithium ions that can be inserted and extracted is reduced by the action of keeping the charge in the crystal neutral. As a result, the charge / discharge capacity decreases.

For this reason, the starting material is heated at 950 ° C.
The synthesis of LiNiO ₂ particles is performed by heat treatment at a high temperature exceeding 300 ° C., the nitrate having a strong oxidizing power is used as a starting material, or the starting material is heat-treated in an oxygen atmosphere to synthesize LiNiO ₂ particles. ing.

However, if the heat treatment temperature is higher than 950 ° C., there is a problem that oxygen is easily desorbed due to the decomposition reaction of the generated LiNiO ₂ . When oxygen is desorbed, a large amount of oxide having extremely high reaction resistance adheres to the surface of the LiNiO ₂ particles, so that the lithium ion occlusion / release reaction of LiNiO ₂ is inhibited.

On the other hand, when a nitrate having a strong oxidizing power is used as the starting material, or when the heat treatment is performed in an oxygen atmosphere, a large amount of nitrate or oxygen gas is industrially handled, which may cause a great danger. Further, according to the synthesis method in which the starting material is heat-treated in an oxygen atmosphere, the oxidizing power is increased, so that a large amount of lithium oxide such as lithium carbonate and lithium oxide adheres to the surface of the LiNiO ₂ particles, or a large amount of lithium oxide is interposed between the particles. An intervening substance causes a local overcharge / overdischarge reaction to easily occur on the particle surface due to a decrease in the reaction area, and a decomposition reaction of the electrolytic solution occurs to generate gas, thereby causing an increase in the internal pressure of the battery. Furthermore, since the conductivity of the positive electrode decreases, there is a problem that the large-current discharge characteristics of the secondary battery deteriorate.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a high capacity and a high electromotive force, to suppress an increase in the internal pressure of a battery, to have a long life, to be excellent in a large current discharge characteristic, and to manufacture a semiconductor device. An object of the present invention is to provide a method for manufacturing a non-aqueous solvent secondary battery with low cost.

An object of the present invention is to provide a non-chargeable battery having a long charge-discharge cycle life and a high capacity recovery rate when stored in a high-temperature environment, in which local overcharge / overdischarge during repeated charge / discharge is suppressed. An object of the present invention is to provide a water solvent secondary battery.

[0014]

A non-aqueous solvent secondary battery according to the present invention comprises a positive electrode active material and a vinylidene fluoride-based fluororesin.
The positive electrode layer containing the binder containing the was coated on the current collector
Comprising a positive electrode having a structure, a negative electrode, and a non-aqueous electrolyte,
The positive electrode active material is (a) LiNiO ₂ or LiNiO ₂
The composition in which a part of nickel of NiO ₂ is replaced by another element
Containing lithium-containing nickel oxide as a main component
And 0.1% to 1.5% by weight formed on the surface of the particles.
% Lithium oxide layer, or (b) L
One of manganese of iMn ₂ O ₄ or LiMn ₂ O ₄
Lithium manganese composite acid with a part replaced by another element
And particles formed on the surface of the particles.
0.1% to 1.5% by weight of a lithium oxide layer.
It is characterized in that that.

Further, the non-aqueous solvent secondary battery according to the present invention comprises:
LiNiO _2, or LiNiO particles and LiMn ₂ O ₄ or the main component of lithium-containing nickel oxide having a composition obtained by substituting a part of ₂ nickel with other elements, or a portion of manganese LiMn ₂ O ₄ A positive electrode including at least one particle of particles mainly composed of a lithium manganese composite oxide having a composition obtained by substituting another element, a negative electrode, and a non-aqueous electrolyte. weight%~
It is characterized by having a lithium oxide layer in a range of 1.5% by weight.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a non-aqueous solvent secondary battery according to the present invention will be described. According to the present invention,
A positive electrode is manufactured by the following methods (1) to (8). (1) LiNiO ₂ or a positive electrode containing lithium-containing nickel oxide having a composition in which nickel in LiNiO ₂ is partially replaced with lithium (slurry preparation formula) A mixture comprising a nickel compound and a lithium compound
An atmosphere containing oxygen gas having a concentration in the range of 8% to 20%, for example, 60 to 60% / hour so that the oxygen gas concentration is in the above range.
670 liters in an atmosphere with an air flow of 5000 l
Lithium-containing nickel oxide particles (active material) by performing a heat treatment for maintaining the temperature in the range of 950C to 950C.
Are synthesized. The obtained lithium-containing nickel oxide particles, the conductive agent and the binder are dispersed in an organic solvent to prepare a slurry. Applying the slurry to a current collector, drying,
The positive electrode is manufactured by rolling if necessary.

Examples of the nickel compound include nickel hydroxide [Ni (OH) ₂ ], nickel carbonate (Ni
CO ₃ ) and nickel nitrate [Ni (NO ₃ ) ₂ ].

Examples of the lithium compound include lithium hydroxide (LiOH) and lithium oxide (Li ₂
O), lithium carbonate (Li ₂ CO ₃ ), lithium nitrate (LiNO ₃ ), lithium halide and the like.

In the above mixture, the ratio of lithium to nickel (Li / Ni) is preferably in the range of 1 to 1.5.
As the lithium-containing nickel oxide, a composition formula Li
A composition represented by _{1 + y} Ni _1-y O ₂ (where y represents 0 ≦ y ≦ 0.1) is preferable. Y is 0.1
If it exceeds 3, the crystal structure becomes unstable, and the charge / discharge cycle life may be reduced.

The concentration of the oxygen gas is limited to the above range for the following reason. When the oxygen gas concentration is less than 18%, a large amount of unreacted products such as nickel hydroxide remains in the generated particles, and the occlusion / release reaction of lithium ions in the particles is inhibited. On the other hand, when the oxygen gas concentration exceeds 20%, although a crystal structure with less disorder of lithium ions and nickel ions is obtained, a large amount of lithium carbonate, nickel oxide, lithium oxide, etc. adhere to the particle surface, and The ion occlusion / release reaction is inhibited. If a large amount of these by-products remain on the particle surface, the adhesion between the particles and between the particles and the current collector may decrease depending on the type of the binder. A more preferred oxygen gas concentration is 1
It is in the range of 8.5% to 19.8%. Note that the atmosphere containing the oxygen gas at the above concentration may be an atmosphere in which oxygen gas is introduced into an inert gas atmosphere such as an argon gas so as to be in the above concentration range.

The heat treatment temperature is limited to the above range for the following reason. The heat treatment temperature is 6
If the temperature is lower than 70 ° C., the reaction becomes insufficient, unreacted products such as nickel hydroxide and lithium hydroxide remain in the particles, and the occlusion / release reaction of lithium ions is inhibited. In addition, lithium ions and nickel ions are likely to be disordered, making it difficult to synthesize a lithium-containing nickel oxide having a uniform crystal structure. On the other hand, when the heat treatment temperature exceeds 950 ° C., oxygen is desorbed due to a decomposition reaction of the generated lithium-containing nickel oxide, and an oxide having extremely high reaction resistance (such as nickel oxide) is formed on the surface of the lithium-containing nickel oxide particles. Is attached in a large amount, so that the lithium ion storing / releasing reaction of the lithium-containing nickel oxide is inhibited. A more preferred heat treatment temperature is
It is in the range of 670 ° C to 740 ° C. A more preferred heat treatment temperature is in the range of 700C to 720C. Note that in the heat treatment step, two or more heat treatment operations may be performed in which the temperature is increased stepwise within the range of 670 ° C. to 950 ° C.

The heat treatment can be performed using an electric furnace equipped with an outside air introduction mechanism or a continuous furnace such as an open-type pusher furnace. The heat treatment is preferably performed for 1 hour to 20 hours.

In such a heat treatment step, the nickel compound and the lithium compound are treated with water, an acidic aqueous solution, an alkaline aqueous solution (for example, an aqueous ammonia solution and an aqueous lithium hydroxide solution), an organic solvent (for example, methanol, ethanol,
Acetone) or mixed by dissolving or dispersing, drying and then molding into pellets or rods,
The heat treatment may be performed on the obtained pellet-like or rod-like mixture under the above-mentioned conditions.

The lithium-containing nickel oxide particles include:
Allows a small amount of lithium carbonate, lithium hydroxide and lithium oxide. The average particle diameter of the lithium-containing nickel oxide particles is 2 to 20 in order to improve the adhesion and electrochemical characteristics between the particles and the current collector in the positive electrode.
It is preferable to set it in the range of μm.

The specific surface area of the lithium-containing nickel oxide particles is preferably in the range of 0.5 to ² m ² / g. This is due to the following reasons. If the specific surface area is less than 0.5 m ² / g, the packing density of the positive electrode active material may decrease, and a sufficient discharge capacity may not be achieved. Also, the charge / discharge efficiency may decrease due to the decrease in the reaction area of the positive electrode. On the other hand, the specific surface area is 2 m ²
If it exceeds / g, the adhesion between the active materials and between the active material and the current collector may be reduced.

Examples of the binder include vinylidene fluoride-based fluororesin (for example, polyvinylidene fluoride (PVdF), a copolymer of vinylidene fluoride-6-propylene fluoride, vinylidene fluoride-tetrafluoroethylene-6) Terpolymer of propylene fluoride, copolymer of vinylidene fluoride-pentafluoropropylene, copolymer of vinylidene fluoride-chlorotrifluoroethylene, copolymer of tetrafluoroethylene-vinylidene fluoride,
Terpolymer of tetrafluoroethylene-perfluoroalkylvinyl ether (PFA) -vinylidene fluoride, terpolymer of tetrafluoroethylene-hexafluoropropylene (FEP) -vinylidene fluoride, tetrafluoroethylene-ethylene-fluoro Vinylidene fluoride terpolymer, chlorotrifluoroethylene-vinylidene fluoride copolymer, chlorotrifluoroethylene-ethylene-vinylidene fluoride terpolymer, vinyl fluoride
And copolymers of vinylidene fluoride, etc., ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR) and the like. These binders may be used alone or in combination of two or more.

Examples of the conductive agent include acetylene black, graphite, carbon black and the like. As the organic solvent, for example, N-2-methylpyrrolidone (NMP), toluene, xylene, ethyl acetate, dimethylformamide (DMF), dimethylacetamide, dimethylimidazolidine, tetrahydrofuran, acetonitrile and the like are used. The organic solvent,
These may be used alone, but two or more types (for example, N
MP and ethyl acetate).

The mixing ratio of the active material, the conductive agent and the binder is 80% to 95% by weight of the active material, 3% to 20% by weight of the conductive agent, and 2% by weight of the binder. 1
It is preferably 0% by weight. In particular, the positive electrode active material has a coating amount of only 10
It is preferable to set it in the range of 0 to 400 g / m ² .

Examples of the current collector include an aluminum foil, a stainless steel foil, and a titanium foil.
In consideration of tensile strength, electrochemical stability, flexibility at the time of winding, and the like, aluminum foil is most preferable. The thickness of the current collector is preferably in the range of 10 μm to 30 μm.

It is preferable that the slurry is prepared while maintaining the active material, the conductive agent, the organic solvent and the binder at a temperature not lower than the freezing point of the binder and not higher than room temperature. If the preparation temperature is higher than room temperature, a curing reaction may occur in the slurry depending on the type of the binder. On the other hand, when the preparation temperature is lower than the freezing point temperature of the binder, the binder may be solidified to make it difficult to prepare a slurry.

The humidity of the preparation atmosphere when preparing the slurry is preferably 60% or less. This is due to the following reasons. If the humidity exceeds 60%, depending on the type of the binder, a curing reaction occurs in the slurry, and the adhesion between the active material and the current collector may be reduced, and the flexibility of the positive electrode may be reduced. A more preferred humidity is in the range of 30% or less.

(2) LiNiO ₂ or LiNiO
_2. Positive electrode (sheet type) containing lithium-containing nickel oxide having a composition in which a part of nickel is replaced with lithium (sheet type).
An atmosphere containing oxygen gas having a concentration in the range of 8% to 20%, for example, 60 to 60% / hour so that the oxygen gas concentration is in the above range.
670 liters in an atmosphere with an air flow of 5000 l
Lithium-containing nickel oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of 950C to 950C. A pellet formed by molding the obtained lithium-containing nickel oxide particles together with a conductive agent and a binder, or a sheet formed by kneading the lithium-containing nickel oxide particles together with a conductive agent and a binder and forming a sheet into a current collector Thus, a positive electrode is manufactured.

Synthesis of the particles, properties of the particles (composition,
The specific surface area, average particle size, etc.), the types of the conductive agent, the binder, and the current collector, and the mixing ratio of the active material, the conductive agent, and the binder in the positive electrode were described in the above-described positive electrode (1). It is the same as

(3) A positive electrode containing a lithium-containing nickel oxide having a composition in which a part of nickel of LiNiO ₂ is replaced by at least one element selected from cobalt, manganese, boron and aluminum (slurry preparation formula) 18% of a mixture comprising at least one compound selected from a manganese compound, a boron compound and an aluminum compound and a nickel compound and a lithium compound
An atmosphere containing oxygen gas having a concentration in the range of 20 to 20%, for example, 60 to 5 hours / hour so that the oxygen gas concentration is in the above range.
670 ° C. in an atmosphere where an air flow of 000 l is introduced
The composite oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of ９950 ° C. The obtained composite oxide particles, the conductive agent and the binder are dispersed in an organic solvent to prepare a slurry. The positive electrode is prepared by applying the slurry to a current collector, drying and rolling as necessary.

As the nickel compound and the lithium compound, the same compounds as those described for the positive electrode (1) can be used. Further, as the cobalt compound, for example, cobalt hydroxide [Co (OH)
₂ ], cobalt carbonate (CoCO ₃ ), cobalt nitrate [C
o (NO ₃ ) ₂ ].

Examples of the manganese compound include electrolytic manganese, manganese oxide (MnO ₂ ), manganese carbonate (MnCO ₃ ), and manganese nitrate [Mn (NO ₃ ) ₂ ].

Examples of the boron compound include boric acid (H ₃ BO ₃ ) and lithium borate (Li ₂ B ₄ O).
₇ ), boron oxide (B ₂ O ₃ ), lithium tetrahydride borate (LiBH ₄ ), and the like.

Examples of the aluminum compound include aluminum oxide (Al ₂ O ₃ ), aluminum hydroxide [Al (OH) ₃ ], aluminum nitrate [Al (N
O ₃ ) ₃ ].

As the lithium-containing nickel oxide, the composition formula is LiNi _1-x M _x O ₂ (where M is:
It is preferably composed of at least one element selected from Co, Mn, B and Al, wherein x represents 0 <x ≦ 0.5). When the value of x exceeds 0.5, nickel ions easily mix into lithium ion sites,
Since the diffusion of lithium ions at the time of charge and discharge may be hindered, there is a possibility that large current discharge characteristics may be deteriorated.

The concentration of the oxygen gas is set in the range of 18 to 20% by weight for the same reason as described for the positive electrode (1). More preferred oxygen gas concentration is 18.
It is in the range of 5% to 19.8%.

The heat treatment temperature is set in the range of 670 ° C. to 950 ° C. for the same reason as described for the positive electrode (1). A more preferred heat treatment temperature is 670 ° C to 74 ° C.
It is in the range of 0 ° C. A more preferred heat treatment temperature is 70
It is in the range of 0 ° C to 720 ° C.

The heat treatment can be performed using the same furnace as described for the positive electrode (1). The heat treatment is preferably performed for 1 hour to 20 hours.

In such a heat treatment step, at least one compound selected from the cobalt compound, the manganese compound, the boron compound and the aluminum compound, the nickel compound and the lithium compound are treated with water, an acidic aqueous solution, an alkaline aqueous solution ( For example, an aqueous ammonia solution, aqueous lithium hydroxide solution) or an organic solvent (e.g., methanol, ethanol, acetone) is dissolved or dispersed in a mixture, dried, and then formed into a pellet or a rod to obtain a pellet. Alternatively, the heat treatment may be performed on the rod-shaped mixture under the above-described conditions.

The lithium-containing nickel oxide particles include:
Allows a small amount of lithium carbonate, lithium hydroxide and lithium oxide. The average particle size of the lithium-containing nickel oxide particles is preferably in the range of 2 to 20 μm for the same reason as described in the above-described positive electrode (1).

The specific surface area of the lithium-containing nickel oxide particles is preferably in the range of 0.5 to ² m ² / g for the same reason as described in the positive electrode (1).

As the binder, the conductive agent, the current collector and the organic solvent, the same ones as described in the positive electrode (1) can be used. The active material,
The mixing ratio of the conductive agent and the binder is determined according to the active material 8
It is preferable that the content is 0% to 95% by weight, the conductive agent is 3% to 20% by weight, and the binder is 2% to 10% by weight. In particular, it is preferable that the amount of the positive electrode active material be in the range of 100 to 400 g / m ² as a coating amount on one side only after the positive electrode is manufactured.

The preparation temperature for preparing the slurry is as follows:
For the same reason as described in the above-mentioned positive electrode (1), it is preferable that the temperature be equal to or higher than the freezing point temperature of the binder and equal to or lower than room temperature.

It is preferable that the humidity of the preparation atmosphere at the time of preparing the slurry be 60% or less for the same reason as described for the positive electrode (1). A more preferred humidity is in the range of 30% or less.

(4) Positive electrode (sheet type) containing lithium-containing nickel oxide having a composition in which a part of nickel of LiNiO ₂ is substituted by at least one element selected from cobalt, manganese, boron and aluminum (sheet type) 18% of a mixture comprising at least one compound selected from a compound, a boron compound and an aluminum compound and a nickel compound and a lithium compound
An atmosphere containing oxygen gas having a concentration in the range of 20 to 20%, for example, 60 to 5 hours / hour so that the oxygen gas concentration is in the above range.
670 ° C. in an atmosphere where an air flow of 000 l is introduced
The composite oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of ９950 ° C. A positive electrode is obtained by kneading the obtained composite oxide particles with a conductive agent and a binder, or kneading the composite oxide particles with a conductive agent and a binder, and adhering the formed sheet to a current collector. Is prepared.

Synthesis of the particles, properties of the particles (composition,
The specific surface area, average particle size, etc.), the types of the conductive agent, the binder, and the current collector, and the mixing ratio of the active material, the conductive agent, and the binder in the positive electrode were described in the above-described positive electrode (3). It is the same as

(5) Positive electrode containing lithium manganese composite oxide represented by the composition formula LiMn ₂ O ₄ (slurry preparation formula) A mixture comprising a manganese compound and a lithium compound
An atmosphere containing oxygen gas having a concentration in the range of 8% to 20%, for example, 60 to 60% / hour so that the oxygen gas concentration is in the above range.
670 liters in an atmosphere with an air flow of 5000 l
Lithium-manganese composite oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of from ℃ to 950 ° C. The obtained lithium manganese composite oxide particles, the conductive agent and the binder are dispersed in an organic solvent to prepare a slurry. The positive electrode is prepared by applying the slurry to a current collector, drying and rolling as necessary.

Examples of the manganese compound and the lithium compound include the same compounds as described above. In the mixture, the ratio of lithium to manganese (Li / Mn) is preferably in the range of 0.5 to 0.8.

The reason why the concentration of the oxygen gas is limited to the above range is as follows. If the oxygen gas concentration is less than 18%, a large amount of unreacted products remain in the generated particles, and the occlusion / release reaction of lithium ions in the particles is inhibited. On the other hand, when the oxygen gas concentration is 2
When the content exceeds 0%, the crystal structure has a small disorder of lithium ions and manganese ions, but a large amount of lithium carbonate, manganese dioxide, and lithium oxide adhere to the surface of the particles, and the occlusion / release reaction of lithium ions in the particles is inhibited. Is done. If a large amount of these by-products remain on the particle surface, the adhesion between the particles and between the particles and the current collector may decrease depending on the type of the binder. A more preferred oxygen gas concentration is in the range of 18.5% to 19.8%. Note that the atmosphere containing the oxygen gas at the above concentration may be an atmosphere in which oxygen gas is introduced into an inert gas atmosphere such as an argon gas so as to be in the above concentration range.

The reason why the heat treatment temperature is limited to the above range is as follows. The heat treatment temperature is 6
If the temperature is lower than 70 ° C., the reaction becomes insufficient, unreacted products remain in the particles, and the occlusion / release reaction of lithium ions is inhibited. In addition, lithium ions and manganese ions are likely to be disordered, making it difficult to synthesize a lithium-manganese composite oxide having a uniform crystal structure. On the other hand, when the heat treatment temperature exceeds 950 ° C., oxygen is desorbed due to a decomposition reaction of the produced lithium manganese composite oxide, and a large amount of oxide having extremely high reaction resistance adheres to the particle surface. The lithium ion occlusion / release reaction of the oxide is inhibited. A more preferred heat treatment temperature is in the range of 720C to 780C. In addition,
In the heat treatment step, two or more heat treatment operations may be performed in which the temperature is increased stepwise within the range of 670 ° C. to 950 ° C.

The heat treatment can be performed using a furnace similar to that described for the positive electrode (1). The heat treatment is preferably performed for 1 hour to 20 hours.

In such a heat treatment step, the manganese compound and the lithium compound are treated with water, an acidic aqueous solution, an alkaline aqueous solution (eg, an ammonia aqueous solution, a lithium hydroxide aqueous solution), and an organic solvent (eg, methanol, ethanol, etc.).
Acetone) or mixed by dissolving or dispersing, drying and then molding into pellets or rods,
The heat treatment may be performed on the obtained pellet-like or rod-like mixture under the above-mentioned conditions.

The lithium manganese composite oxide particles are as follows:
Allows a small amount of lithium carbonate, lithium hydroxide and lithium oxide. The average particle diameter of the lithium manganese composite oxide particles is preferably in the range of 2 to 20 μm for the same reason as described for the positive electrode (1).

The specific surface area of the lithium manganese composite oxide particles is preferably in the range of 0.5 to ² m ² / g for the same reason as described for the positive electrode (1). As the binder, the conductive agent, the organic solvent, and the current collector, the same ones as described in the above-described positive electrode (1) are used.

The mixing ratio of the active material, the conductive agent and the binder is 80% to 95% by weight of the active material, 3% to 20% by weight of the conductive agent, and 2% by weight of the binder. 1
It is preferably 0% by weight. In particular, the positive electrode active material has a coating amount of only 10
It is preferable to set it in the range of 0 to 400 g / m ² .

The preparation temperature for preparing the slurry is as follows:
For the same reason as described for the positive electrode (1) described above, it is preferable that the temperature be equal to or higher than the freezing point temperature of the binder and equal to or lower than room temperature.

It is preferable that the humidity of the preparation atmosphere at the time of preparing the slurry be 60% or less for the same reason as described for the positive electrode (1). A more preferred humidity is in the range of 30% or less.

(6) Positive electrode (sheet type) containing lithium manganese composite oxide represented by the composition formula LiMn ₂ O _{4: A} mixture comprising a manganese compound and a lithium compound
An atmosphere containing oxygen gas having a concentration in the range of 8% to 20%, for example, 60 to 60% / hour so that the oxygen gas concentration is in the above range.
670 liters in an atmosphere with an air flow of 5000 l
Lithium-manganese composite oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of from ℃ to 950 ° C. A pellet obtained by molding the obtained lithium manganese composite oxide particles together with a conductive agent and a binder, or kneading the lithium-containing nickel oxide particles together with a conductive agent and a binder, and adhering a sheet formed into a sheet to a current collector Thus, a positive electrode is manufactured.

Synthesis of the particles, properties of the particles (composition,
The specific surface area, the average particle size, etc.), the types of the conductive agent, the binder, and the current collector, and the mixing ratio of the active material, the conductive agent, and the binder in the positive electrode were described in the above-described positive electrode (5). It is the same as

(7) A positive electrode containing a lithium manganese composite oxide having a composition in which part of manganese of LiMn ₂ O ₄ is substituted with at least one element selected from cobalt, nickel, boron and aluminum (slurry preparation formula) 18% of a mixture comprising at least one compound selected from a compound, a nickel compound, a boron compound and an aluminum compound and a manganese compound and a lithium compound
An atmosphere containing oxygen gas having a concentration in the range of 20 to 20%, for example, 60 to 5 hours / hour so that the oxygen gas concentration is in the above range.
670 ° C. in an atmosphere where an air flow of 000 l is introduced
The composite oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of ９950 ° C. The obtained composite oxide particles, the conductive agent and the binder are dispersed in an organic solvent to prepare a slurry. The positive electrode is prepared by applying the slurry to a current collector, drying and rolling as necessary.

The lithium compound, the cobalt compound, the nickel compound, the boron compound, the aluminum compound and the manganese compound include the same compounds as described above.

The composite oxide has a composition formula of LiM
n _2-z M _z O ₄ (where M is one or more elements selected from Co, Mn, B and Al, and z is 0
<X ≦ 0.5) is preferable. When z exceeds 0.5, manganese ions are likely to be mixed into lithium ion sites, which may hinder diffusion of lithium ions during charging and discharging. As a result, the high-current discharge characteristics may be reduced.

The concentration of the oxygen gas is set in the range of 18 to 20% by weight for the same reason as described for the positive electrode (5). More preferred oxygen gas concentration is 18.
It is in the range of 5% to 19.8%.

The heat treatment temperature is set in the range of 670 to 950 ° C. for the same reason as described for the positive electrode (5). A more preferable heat treatment temperature is 720 ° C. to 780
It is in the range of ° C.

The heat treatment can be performed in the same furnace as that described for the positive electrode (1). The heat treatment is preferably performed for 1 hour to 20 hours.

In the heat treatment step, one or more compounds selected from the cobalt compound, the nickel compound, the boron compound and the aluminum compound, the manganese compound and the lithium compound are treated with water, an acidic aqueous solution, an alkaline aqueous solution ( For example, an aqueous ammonia solution, aqueous lithium hydroxide solution) or an organic solvent (e.g., methanol, ethanol, acetone) is dissolved or dispersed in a mixture, dried, and then formed into a pellet or a rod to obtain a pellet. Alternatively, the heat treatment may be performed on the rod-shaped mixture under the above-described conditions.

The lithium manganese composite oxide particles are as follows:
Allows a small amount of lithium carbonate, lithium hydroxide and lithium oxide. The average particle size of the lithium manganese composite oxide particles is preferably in the range of 2 to 20 μm for the same reason as described in the positive electrode (1).

The specific surface area of the lithium manganese composite oxide particles is preferably in the range of 0.5 to ² m ² / g for the same reason as described in the above-mentioned positive electrode (1).

As the binder, the conductive agent, the current collector and the organic solvent, the same ones as described in the positive electrode (1) can be used. The active material,
The mixing ratio of the conductive agent and the binder is determined according to the active material 8
It is preferable that the content is 0% to 95% by weight, the conductive agent is 3% to 20% by weight, and the binder is 2% to 10% by weight. In particular, it is preferable that the amount of the positive electrode active material be in the range of 100 to 400 g / m ² as a coating amount on one side only after the positive electrode is manufactured.

The preparation temperature for preparing the slurry is as follows:
For the same reason as described in the above-mentioned positive electrode (1), it is preferable that the temperature be equal to or higher than the freezing point temperature of the binder and equal to or lower than room temperature.

It is preferable that the humidity of the preparation atmosphere at the time of preparing the slurry be 60% or less for the same reason as described for the positive electrode (1). A more preferred humidity is in the range of 30% or less.

(8) Positive electrode (sheet type) containing lithium manganese composite oxide having a composition in which part of manganese of LiMn ₂ O ₄ is substituted by at least one element selected from cobalt, nickel, boron and aluminum , A mixture of at least one compound selected from a nickel compound, a boron compound and an aluminum compound, and a manganese compound and a lithium compound by 18%
An atmosphere containing oxygen gas having a concentration in the range of 20 to 20%, for example, 60 to 5 hours / hour so that the oxygen gas concentration is in the above range.
670 ° C. in an atmosphere where an air flow of 000 l is introduced
Lithium-manganese composite oxide particles (active material) are synthesized by performing a heat treatment at a temperature in the range of ９950 ° C. A pellet obtained by molding the obtained lithium manganese composite oxide particles together with a conductive agent and a binder, or kneading the lithium-containing nickel oxide particles together with a conductive agent and a binder, and adhering a sheet formed into a sheet to a current collector Thus, a positive electrode is manufactured.

Synthesis of the particles, properties of the particles (composition,
The specific surface area, average particle size, etc.), the types of the conductive agent, the binder, and the current collector, and the mixing ratio of the active material, the conductive agent, and the binder in the positive electrode were described in the above-described positive electrode (7). It is the same as

Hereinafter, a non-aqueous electrolyte secondary battery (for example, a cylindrical non-aqueous solvent secondary battery) manufactured by the method according to the present invention will be described in detail with reference to FIG. For example, a cylindrical container 1 with a bottom made of stainless steel has an insulator 2 disposed at the bottom. The electrode group 3 is housed in the container 1.
The electrode group 3 is formed by laminating a positive electrode 4, a separator 5 and a negative electrode 6 produced in the above-described methods (1) to (4) in this order so that the separator 5 is located on the outer periphery. It has a spirally wound structure. The separator 5 is made of, for example, a synthetic resin nonwoven fabric, a polyethylene porous film, or a polypropylene porous film.

The container 1 contains a nonaqueous electrolyte. The insulating paper 7 having a central portion opened is placed above the electrode group 3 in the container 1. Insulating sealing plate 8
Is disposed in the upper opening of the container 1 and the vicinity of the upper opening is caulked inward to fix the sealing plate 8 to the container 1 in a liquid-tight manner. Positive terminal 9
Is fitted at the center of the insulating sealing plate 8. One end of a positive electrode lead 10 is connected to the positive electrode 4, and the other end is connected to the positive electrode terminal 9. The negative electrode 6 is connected to the container 1 as a negative terminal via a negative lead (not shown).

Next, the negative electrode 6 and the non-aqueous electrolyte will be specifically described. 1) Negative Electrode 6 This negative electrode has a structure in which a current collector is coated with a negative electrode layer containing a binder in a compound that stores and releases lithium ions.

Examples of the compounds that occlude and release lithium ions include conductive polymers such as lithium ion-doped polyacetal, polyacetylene, and polypyrrole, and carbon materials formed of lithium ion-doped organic fired materials. be able to.

The characteristics of the carbon material differ considerably depending on the raw material and the firing method. Examples of the carbon material include graphite-based carbon, carbon in which a graphite crystal part and an amorphous part are mixed, and a carbon material having a turbostratic structure with no regularity in crystal lamination.

As the binder, the above-mentioned positive electrode (1)
And the same as those described above. The compounding ratio of the compound that absorbs and releases lithium ions and the binder is 80 to 98% by weight of the compound and the binder 2 to 80% by weight.
Preferably it is in the range of 20% by weight. In particular, it is preferable that the amount of the compound be in the range of 50 to 200 g / m ² in the state where the negative electrode 6 is prepared, as a coating amount on only one side.

Examples of the current collector include a copper foil and a nickel foil. In consideration of electrochemical stability and flexibility at the time of winding, it is preferable to use a copper foil. The thickness of the current collector is preferably in the range of 8 to 20 μm.

The negative electrode 6 is produced, for example, by the following method. (A) A binder is suspended in a suitable solvent in a compound that stores and releases lithium to prepare a slurry. The slurry is applied to one side or both sides of a current collector, dried, cut, and the negative electrode layer is coated on the current collector to produce a negative electrode. As the solvent, for example, N-2
-Methylpyrrolidone (NMP), toluene, xylene,
Ethyl acetate, dimethylformamide (DMF), dimethylacetamide, dimethylimidazolidine, tetrahydrofuran, acetonitrile and the like are used.

(B) A pellet molded with a compound capable of absorbing and releasing lithium and a binder, or a sheet kneaded and compounded with a compound capable of absorbing and releasing lithium and a binder is adhered to a current collector. To produce a negative electrode.

2) Nonaqueous Electrolyte This nonaqueous electrolyte has a composition in which an electrolyte is dissolved in a nonaqueous solvent. Examples of the non-aqueous solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, 1,2-dimethoxyethane,
One or a mixture of two or more selected from acetonitrile, ethyl acetate, methyl acetate, diethoxyethane, 1,3-dioxolan, and 1,3-dimethoxypropane can be exemplified.

Examples of the electrolyte include lithium borofluoride (LiBF ₄ ) and lithium hexafluorophosphate (Li
PF ₆ ), lithium perchlorate (LiClO ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium aluminum tetrachloride (LiAlCl ₄ ), bistrifluoromethylsulfonylimide One or more lithium salts selected from lithium can be mentioned. The amount of the electrolyte dissolved in the non-aqueous solvent is 0.5 to 1.5.
Preferably it is mol / l.

In FIG. 1 described above, an example in which the present invention is applied to a cylindrical non-aqueous electrolyte secondary battery which is spirally wound with a separator interposed between a positive electrode and a negative electrode and housed in a bottomed cylindrical container. However, for example, a separator is interposed between the positive electrode and the negative electrode, the same applies to a square non-aqueous electrolyte secondary battery in which a laminate obtained by laminating a plurality of these is housed in a bottomed rectangular cylindrical container. Can be applied to

Hereinafter, the non-aqueous solvent secondary battery according to the present invention will be described. The non-aqueous solvent secondary battery according to the present invention is Li
NiO ₂ or particles containing lithium-containing nickel oxide as a main component and having a composition in which nickel of LiNiO ₂ is partially replaced with another element, and LiMn ₂ O ₄ or LiM
a positive electrode including at least one of particles mainly composed of a lithium manganese composite oxide having a composition in which a part of manganese of n ₂ O ₄ is replaced with another element, a negative electrode, and a non-aqueous electrolyte. The particles are characterized in that a lithium oxide layer in a range of 0.1% by weight to 1.5% by weight based on the particles is formed on the surface of the particles.

The non-aqueous solvent secondary battery has an electrode group formed by spirally winding a separator between the positive electrode and the negative electrode as shown in FIG. 1, for example. Can be housed in a container together with the non-aqueous electrolyte. In addition, the secondary battery may have a structure in which a separator is interposed between a positive electrode and a negative electrode, and a laminate of a plurality of such layers is housed in a bottomed rectangular cylindrical container.

Examples of the negative electrode, the separator and the non-aqueous electrolyte include the same as those described above. (Positive Electrode) The positive electrode comprises particles (active material) containing the lithium-containing nickel oxide as a main component and having a lithium oxide layer in the range of 0.1% to 1.5% by weight on the surface, or the lithium manganese. Positive electrode layer containing at least one particle of particles (active material) having a lithium oxide layer in the range of 0.1% to 1.5% by weight on the surface of a composite oxide as a main component, a conductive agent and a binder Is covered with a current collector.

When the replacement element of Ni in the LiNiO ₂ is Li, the composition represented by the composition formula Li _{1 + y} Ni _1-y O ₂ (where y represents 0 <y ≦ 0.1) Are preferred. If the value of y exceeds 0.1, the crystal structure becomes unstable, and the charge / discharge cycle life may be reduced.

When the substitution element of Ni in LiNiO ₂ is one or more elements selected from Co, Mn, B and Al, the composition formula is LiNi _1-x M _x O ₂ (where M is Co , Mn, B and Al, and x is preferably 0 <x ≦ 0.5). If the value of x exceeds 0.5, nickel ions easily mix into lithium ion sites, and diffusion of lithium ions during charging and discharging may be hindered. is there.

When the substitution element of Mn in LiMn ₂ O ₄ is one or more elements selected from Co, Ni, B and Al, the composition formula is LiMn _{2-z Mz} O ₄ (provided that:
M is preferably composed of at least one element selected from Co, Mn, B and Al, and z is preferably 0 <x ≦ 0.5). When the z exceeds 0.5,
Manganese ions are likely to be mixed into lithium ion sites, and diffusion of lithium ions during charging and discharging may be hindered, which may lead to deterioration of large current discharge characteristics.

The average particle size of these particles is preferably in the range of 2 to 20 μm in order to improve the adhesion between the particles and the current collector in the positive electrode and the electrochemical characteristics. The specific surface area of the particles is 0.5 to ² m ² / g.
It is preferable to be within the range. This is due to the following reasons. When the specific surface area is less than 0.5 m ² / g, the packing density of the active material is reduced, and a sufficient discharge capacity may not be achieved. Also, the charge / discharge efficiency may decrease due to the decrease in the reaction area of the positive electrode. On the other hand, if the specific surface area exceeds 2 m ² / g, adhesion between particles and between the positive electrode layer and the current collector may be reduced.

When the adhesion amount of the lithium oxide (Li ₂ O) layer to the particles exceeds 1.5% by weight, the adhesion between the positive electrode layer and the current collector and between the particles is reduced, and the Internal short circuit, decrease in charge / discharge cycle,
This results in deterioration of large current discharge characteristics and a decrease in capacity recovery rate after storage at high temperatures. Further, the occlusion / release reaction of lithium ions in the particles is inhibited. On the other hand, the adhesion amount is 0.1
If the amount is less than% by weight, the cycle life may be reduced. A more preferred coverage is in the range of 0.5% to 1.2% by weight.

(A) LiNiO ₂ , Li _{1 + y} Ni _1-y O
Particles A having ₂ as a main component and having a lithium oxide layer in the range of 0.1% by weight to 1.5% by weight on the surface are synthesized, for example, by the following method.

The mixture comprising the nickel compound and the lithium compound was introduced into an atmosphere containing oxygen gas at a concentration in the range of 18% to 20%, for example, an air stream of 60 to 5000 l / h so that the oxygen gas concentration was in the above range. A heat treatment for maintaining the temperature in a range of 670 ° C. to 950 ° C. in an atmosphere is performed (first stage heat treatment). Next, the particles A are synthesized by performing a second-stage heat treatment at a temperature in a range of 600 ° C. to 650 ° C. in an atmosphere introduced with an oxygen gas so that an oxygen gas concentration is in a range of 21% to 100%.

In the first stage of heating, the surface has a layer of lithium oxide (Li ₂ O) and a layer of lithium carbonate (Li ₂ CO ₃ ), and is mainly composed of LiNiO ₂ or Li _{1 + y} Ni _1-y O ₂ . Is obtained. In the subsequent second-stage heating, most of the lithium carbonate is oxidized to lithium oxide, and the particles A are synthesized.

The heat treatment in the first stage is the same as that described for the positive electrode (1).

(B) Particles B containing LiNi _1-x M _x O ₂ as a main component and having a lithium oxide layer in the range of 0.1% by weight to 1.5% by weight on the surface can be prepared, for example, by the following method. Synthesized.

An atmosphere containing a mixture of at least one compound selected from a cobalt compound, a manganese compound, a boron compound and an aluminum compound and a nickel compound and a lithium compound in an oxygen gas concentration of 18% to 20%, for example, Heat treatment is performed to maintain the temperature in the range of 670 ° C. to 950 ° C. in an atmosphere in which an air flow of 60 to 5000 l / h is introduced so that the oxygen gas concentration is in the above range (first stage heat treatment). Next, when the oxygen gas concentration is 21
The particles B are synthesized by performing a second stage heat treatment at a temperature in the range of 600 ° C. to 650 ° C. in an atmosphere in which an oxygen stream is introduced so as to be in the range of 100% to 100%.

In the first stage of heating, particles having a lithium oxide (Li ₂ O) and lithium carbonate (Li ₂ CO ₃ ) layer on the surface and containing LiNi _1-x M _x O ₂ as a main component are obtained. . In the subsequent second stage heating, most of the lithium carbonate is oxidized to lithium oxide and the particles B
Are synthesized.

The heat treatment in the first stage is the same as that described for the positive electrode (3).

(C) Particles C containing LiMn ₂ O ₄ as a main component and having a lithium oxide layer in the range of 0.1% to 1.5% by weight on the surface are synthesized, for example, by the following method. A mixture of a manganese compound and a lithium compound is exposed to an atmosphere containing oxygen gas at a concentration in the range of 18% to 20%, for example, in an atmosphere introduced with an air flow of 60 to 5000 l / h so that the oxygen gas concentration is in the above range. A heat treatment is performed to maintain the temperature in the range of 950C to 950C (first stage heat treatment). Next, the oxygen gas concentration is 21%
The particles C are synthesized by performing the second-stage heat treatment at a temperature in the range of 600 ° C. to 650 ° C. in an atmosphere in which an oxygen stream is introduced so as to be in the range of 100% to 100%.

In the first stage of heating, particles having a layer of lithium oxide (Li ₂ O) and a layer of lithium carbonate (Li ₂ CO ₃ ) on the surface and containing LiMn ₂ O ₄ as a main component are obtained.
In the subsequent second stage heating, most of the lithium carbonate is oxidized to lithium oxide, and the particles C are synthesized.

The heat treatment in the first stage is the same as that described for the positive electrode (5).

(D) Particles D containing LiMn _2-z M _z O ₄ as a main component and having a lithium oxide layer in the range of 0.1% by weight to 1.5% by weight on the surface can be prepared, for example, by the following method. Synthesized.

An atmosphere containing oxygen gas at a concentration in the range of 18% to 20% is prepared by mixing a mixture of at least one compound selected from a cobalt compound, a nickel compound, a boron compound and an aluminum compound with a manganese compound and a lithium compound, for example, Heat treatment is performed to maintain the temperature in the range of 670 ° C. to 950 ° C. in an atmosphere in which an air flow of 60 to 5000 l / h is introduced so that the oxygen gas concentration falls within the above range (first stage heat treatment). Next, when the oxygen gas concentration is 21
The particles D are synthesized by performing a second stage heat treatment at a temperature in the range of 600 ° C. to 650 ° C. in an atmosphere in which an oxygen stream is introduced so as to be in the range of 100% to 100%.

In the first stage heating, particles having a layer of lithium oxide (Li ₂ O) and a layer of lithium carbonate (Li ₂ CO ₃ ) on the surface and containing LiMn _{2-z Mz} O ₄ as a main component are obtained. . In the subsequent second stage heating, most of the lithium carbonate is oxidized to lithium oxide and the particles D
Are synthesized.

The first-stage heat treatment is the same as that described for the positive electrode (7).

Particles having the lithium-containing nickel oxide as a main component and having a lithium oxide layer in the range of 0.1% to 1.5% by weight on the surface and the lithium-manganese composite oxide as the main component, A positive electrode including at least one particle selected from particles having a lithium oxide layer in the range of 0.1% by weight to 1.5% by weight is produced, for example, by the method described in the following (a) and (b). You.

(A) Slurry preparation method The particles, the conductive agent and the binder are dispersed in an organic solvent to prepare a slurry. The positive electrode having a structure in which the positive electrode layer covers the current collector is manufactured by applying the slurry to a current collector, drying and rolling as necessary.

As the binder, the conductive agent, the current collector, and the organic solvent, the same ones as described in the positive electrode (1) are used. The mixing ratio of the active material, the conductive agent and the binder is 80% by weight of the active material.
Preferably, the content of the conductive agent is 3 to 20% by weight, and the content of the binder is 2 to 10% by weight. In particular, it is preferable that the amount of the positive electrode active material be in the range of 100 to 400 g / m ² as a coating amount on one side only after the positive electrode is manufactured.

The preparation temperature for preparing the slurry is as follows:
For the same reason as described for the positive electrode (1) described above, it is preferable that the temperature be equal to or higher than the freezing point temperature of the binder and equal to or lower than room temperature.

It is preferable that the humidity of the preparation atmosphere at the time of preparing the slurry be 60% or less for the same reason as described for the positive electrode (1). A more preferred humidity is in the range of 30% or less.

(B) Sheet method A pellet formed by molding the particles together with the conductive agent and the binder, or a sheet formed by kneading the particles together with the conductive agent and the binder and forming a sheet is attached to the current collector. A positive electrode is produced by attaching.

According to the method for manufacturing a non-aqueous solvent secondary battery according to the present invention described above, a mixture containing a nickel compound and a lithium compound is heated to 670 ° C. in an atmosphere containing oxygen at a concentration of 18% to 20%. A positive electrode is manufactured by a method including a step of performing a heat treatment at a temperature in a range of 950 ° C. Since the obtained positive electrode contains a homogeneous lithium-containing composite oxide as an active material, the amount of inserted and released lithium ions can be improved. Therefore, a non-aqueous solvent secondary battery having a high discharge capacity and high electromotive force and a long charge-discharge cycle life can be provided at low cost.

Further, since the heat treatment temperature at the time of synthesis is 950 ° C. or less, it is possible to prevent oxygen from being desorbed from the produced lithium-containing nickel oxide or a decomposition reaction from occurring.

Further, by performing a heat treatment in an atmosphere containing oxygen having a concentration in the above range, a large amount of lithium oxide such as lithium carbonate, lithium oxide and lithium hydroxide adheres to the surface of the lithium-containing nickel oxide particles. Can be prevented. As a result, a local overcharge / overdischarge reaction can be prevented from occurring on the surface of the lithium-containing nickel oxide particles, so that an increase in the internal pressure can be avoided. In addition, since the conductivity of the positive electrode can be improved, the impedance of the battery can be suppressed low, and excellent high-current discharge characteristics can be realized.

Further, in the homogeneous lithium-containing oxide synthesized by the above method, a composition in which a part of Ni of LiNiO ₂ is substituted by at least one element selected from Co, Mn, B, Li and Al. Can prevent lithium ions and nickel ions from being disordered, and can also prevent the crystal from being distorted due to the insertion and extraction of lithium ions due to the substitution of elements. Can be prevented from destruction of the crystal structure accompanying the progress of the process, and the cycle life can be remarkably improved.

Further, by setting the specific surface area of the lithium-containing nickel oxide in the range of 0.5 to ² m ² / g, it is possible to improve the active material packing density of the positive electrode and to remove the active material from the positive electrode. Can be suppressed.

The method for producing a non-aqueous solvent secondary battery according to the present invention is characterized in that a mixture containing a manganese compound and a lithium compound
A positive electrode is manufactured by a method including a step of performing a heat treatment at a temperature of 670 ° C. to 950 ° C. in an atmosphere containing oxygen at a concentration of 8% to 20%. The resulting positive electrode is
Since a homogeneous lithium-manganese composite oxide is contained as an active material, the amount of inserted and released lithium ions can be improved. Therefore, a non-aqueous solvent secondary battery having a high discharge capacity and high electromotive force and a long charge-discharge cycle life can be provided at low cost.

Further, since the heat treatment temperature at the time of synthesis is 950 ° C. or less, it is possible to prevent oxygen from being desorbed from the produced lithium manganese composite oxide and a decomposition reaction from occurring.

Further, by performing a heat treatment in an atmosphere containing oxygen having a concentration in the above range, it is possible to prevent a large amount of lithium oxide such as lithium carbonate, lithium oxide and lithium hydroxide from adhering to the surface of the lithium manganese composite oxide particles. Can be prevented. As a result, a local overcharge / overdischarge reaction can be prevented from occurring on the particle surface, and an increase in the internal pressure can be avoided. In addition, since the conductivity of the positive electrode can be improved, the impedance of the battery can be suppressed low, and excellent high-current discharge characteristics can be realized.

In the homogeneous lithium manganese composite oxide synthesized by the above method, a part of Mn of LiMn ₂ O ₄ is replaced by at least one element selected from Co, Ni, B, Li and Al. Oxide having the composition described
It can prevent lithium ions and manganese ions from being disordered, and can also suppress the distortion of the crystal due to the insertion and extraction of lithium ions due to the substitution of elements. Can be prevented, and the cycle life can be dramatically improved.

Further, by setting the specific surface area of the lithium manganese composite oxide particles in the range of 0.5 to ² m ² / g, the active material filling density of the positive electrode can be improved, and the active material filling from the positive electrode can be improved. Dropout can be suppressed.

The non-aqueous solvent secondary battery according to the present invention comprises LiN
Particles mainly composed of lithium-containing nickel oxide having a composition in which a part of nickel of iO ₂ or LiNiO ₂ is replaced by another element and LiMn ₂ O ₄ or LiMn
A positive electrode including at least one of particles mainly composed of a lithium manganese composite oxide in which a part of manganese of ₂ O ₄ is substituted by another element; Li _{2 in} the range of 1% to 1.5% by weight
An O layer is formed. This positive electrode is made of, for example, Li ₂ O
It is formed from a current collector coated with a positive electrode layer containing particles having a layer and a vinylidene fluoride-based fluororesin. When such a positive electrode contains particles having a Li ₂ O layer as an active material, the adhesion between the active material and between the positive electrode layer and the current collector can be improved. It is possible to provide a non-aqueous solvent secondary battery that is prevented from being overcharged and has improved capacity recovery rate, large current discharge characteristics, and cycle life when stored in a high-temperature environment. Also,
The secondary battery can suppress occurrence of an internal short circuit in manufacturing.

That is, the vinylidene fluoride-based fluororesin contained as the binder for the positive electrode is formed when synthesizing particles containing the lithium-containing nickel oxide or the lithium-manganese composite oxide as a main component. Li ₂
CO ₃ , Li ₂ O, and LiOH, which is an unreacted product during synthesis
Reacts with to form a carbon double bond. This double bond is extremely unstable and causes a cross-linking reaction between molecules or within a molecule. When this cross-linking reaction occurs during the production, the amount of the fluororesin functioning as a binder decreases, so that the adhesion between the active materials and between the positive electrode layer and the current collector decreases. LiOH, Li ₂ CO ₃ , Li
₂ O. LiOH and Li ₂ CO ₃ are more likely to cause the crosslinking reaction when moisture is present in the atmosphere. In addition, when the positive electrode having the above structure is manufactured by a slurry preparation method, the adhesiveness between the slurry and the current collector is reduced due to a cross-linking reaction occurring during the preparation of the slurry, so that the active material is removed from the current collector in a drying step performed after the slurry is applied. It is easy to peel off. Furthermore, if the cross-linking reaction occurs remarkably during the preparation of the slurry, the slurry hardens and the slurry cannot be applied to the current collector. In addition, N-2-methylpyrrolidone used as a solvent for the slurry has high water solubility, and tends to absorb moisture during storage, including during handling. For this reason, when N-2-methylpyrrolidone is used as a solvent, if LiOH and Li ₂ CO ₃ are present in the slurry, N-2-methylpyrrolidone is used.
The crosslinking reaction is promoted by the water contained in methylpyrrolidone, and the slurry is hardened.

As described in the present invention, a specific amount of Li ₂ O
When particles having a lithium-containing nickel oxide as a main component or particles having a Li ₂ O layer and a lithium-manganese composite oxide as a main component are used as an active material, vinylidene fluoride Since the crosslinking reaction of the fluorocarbon resin can be suppressed, the adhesion between the active materials and between the active material and the current collector can be improved. As a result, conduction between the active material and between the active material and the current collector can be improved, so that overdischarge and overcharge can be locally prevented at the positive electrode, and the cycle life can be reduced. Can be improved. In addition, large current discharge characteristics can be improved. Furthermore, since the positive electrode layer can be prevented from peeling off from the current collector when stored in a high-temperature environment, the impedance of the battery can be kept low, and the capacity recovery rate can be improved. Further, a separator is interposed between the positive electrode and the negative electrode, and when a spiral is wound to form an electrode group, it is possible to suppress the active material from falling off from the positive electrode. Internal short-circuiting when housed inside can be reduced. When the positive electrode is manufactured by a slurry preparation method, a crosslinking reaction of a vinylidene fluoride-based fluororesin in a slurry preparation step can be suppressed, so that the slurry can be uniformly applied to a current collector. For this reason, in the drying step, it is possible to prevent the slurry from peeling off from the current collector. In addition, the fluorine resin has a three-dimensional structure due to the cross-linking reaction that occurs in the drying step, and since the three-dimensional structure can enhance the binding between particles, a positive electrode with significantly improved adhesion is provided. And a non-aqueous solvent secondary battery.

Co, Mn, B, Al and L are substituted elements for nickel contained in the lithium-containing nickel oxide.
By using one or more elements selected from i, it is possible to suppress the crystal from being distorted due to the insertion and extraction of lithium ions, and thus the non-aqueous solvent whose charge-discharge cycle life has been dramatically improved A secondary battery can be provided.

Further, Co, Ni, B, Al are substituted elements for manganese contained in the lithium manganese composite oxide.
And one or more elements selected from Li and Li, the non-aqueous solvent having significantly improved charge / discharge cycle life can be prevented from distorting the crystal due to occlusion / release of lithium ions. A secondary battery can be provided.

[0134]

An embodiment of the present invention will be described below in detail with reference to FIG. (Example 1) <Preparation of Positive Electrode> First, nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1 and mixed sufficiently by a ball mill. Is 19
%, And heat treatment was performed at a temperature of 670 ° C. for 5 hours while introducing an air stream at 4000 l / h.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiNiO ₂ . 90% by weight of the LiNiO ₂ powder (active material),
After mixing 5% by weight of acetylene black in a ball mill for 1 hour, polyvinylidene fluoride was dissolved in N-2-methyl-pyrrolidone so as to be 5% by weight.
The positive electrode slurry was prepared by mixing and dispersing in an atmosphere having a humidity of 20% or less while maintaining the temperature at ° C. Subsequently, the slurry was applied to an aluminum foil (current collector), dried, and roll-pressed to produce a positive electrode.

<Preparation of Negative Electrode> First, mesophase pitch-based carbon fiber was graphitized at 3000 ° C. in an argon gas atmosphere, and then heat-treated in a chlorine gas atmosphere at 2400 ° C. to synthesize a graphitized carbon powder. 94% by weight of the obtained graphitized carbon powder and 6% by weight of polyvinylidene fluoride
-Methyl-pyrrolidone to prepare a negative electrode slurry. Next, the slurry was applied on a copper foil (current collector), dried, and roll-pressed to produce a negative electrode.

<Preparation of Electrode Group> The positive electrode, the separator made of a porous film made of polypropylene, and the negative electrode were laminated in this order, and then wound in a spiral so that the separator was located at the outermost periphery. An electrode group was prepared.

<Preparation of Non-Aqueous Electrolyte> 1.0 mol / l of lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate (mixing volume ratio 1: 2) to obtain a non-aqueous electrolyte. A water electrolyte was prepared.

The above-mentioned electrode group and the above-mentioned non-aqueous electrolyte were accommodated in a stainless steel bottomed cylindrical container, and the opening was sealed with a sealing plate to obtain the cylindrical non-aqueous solvent secondary battery shown in FIG. Assembled.

(Example 2) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficient mixing by a ball mill, the oxygen concentration was reduced to 19%. The heat treatment was performed at a temperature of 740 ° C. for 5 hours while introducing an air stream at 4000 l / h.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiNiO ₂ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiNiO ₂ powder was used as an active material of a positive electrode.

(Example 3) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficient mixing by a ball mill, the oxygen concentration was reduced to 19%. The heat treatment was performed at a temperature of 800 ° C. for 5 hours while introducing an air stream at 4000 l / h.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiNiO ₂ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiNiO ₂ powder was used as an active material of a positive electrode.

Example 4 A mixture of nickel hydroxide powder, lithium hydroxide and cobalt hydroxide powder was prepared so that the molar ratio of Li: Ni: Co was 1: 0.5: 0.5. After sufficient mixing, an air stream of 4000 l / h was introduced so that the oxygen concentration was 19%.
Heat treatment was performed for 1 hour at a temperature of ° C. Furthermore, at 900 ° C, 4
After holding for a time, the temperature was lowered.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the product had a LiNiO ₂ structure. Further, the total lithium content of the product was measured by an atomic absorption method, and redox titration and neutralization titration were performed. As a result, it was found that the composition was LiNi _0.5 Co _0.5 O ₂ .

A cylindrical nonaqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.5 Co _0.5 O ₂ powder was used as an active material of a positive electrode. (Example 5) Nickel hydroxide powder, lithium hydroxide and lithium borate were mixed at a molar ratio of Li: Ni: B of 1: 0.9.
7: 0.3 and sufficiently mixed by a ball mill, and then heat-treated at a temperature of 700 ° C. for 1 hour while introducing 4000 l / h of an air stream so that the oxygen concentration became 19%. .

The obtained product (particles) was measured by X-ray diffraction, and it was confirmed that the product had a LiNiO ₂ structure. Further, the total amount of lithium of the product was measured by an atomic absorption method, and redox titration and neutralization titration were performed. As a result, it was found that the composition was LiNi _0.97 B _0.03 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.97 B _0.03 O ₂ powder was used as an active material of a positive electrode. (Example 6) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1.1: 0.9, and the mixture was sufficiently mixed by a ball mill.
%, And heat treatment was performed at a temperature of 740 ° C. for 15 hours while introducing an air stream at 4000 l / h.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that it had a LiNiO ₂ structure. In addition, the total amount of lithium of the product was measured by an atomic absorption method, and redox titration and neutralization titration were performed. As a result, the product was found to have a composition of Li _1.1 Ni _0.9 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned Li _1.1 Ni _0.9 O ₂ powder was used as an active material of a positive electrode. (Example 7) Nickel hydroxide powder, lithium hydroxide and aluminum hydroxide were mixed at a molar ratio of Li: Ni: Al of 1:
After mixing at 0.97: 0.3 and thoroughly mixing with a ball mill, heat treatment was performed for 5 hours at a temperature of 700 ° C. while introducing 4000 l / h of air air so that the oxygen concentration became 19%. went.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the product had a LiNiO ₂ structure. Further, the total amount of lithium of the product was measured by an atomic absorption method, and redox titration and neutralization titration were performed. As a result, it was found that the composition was LiNi _0.97 Al _0.03 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.97 Al _0.03 O ₂ powder was used as an active material of a positive electrode. Example 8 Nickel hydroxide powder, cobalt hydroxide, aluminum hydroxide, and lithium hydroxide were mixed with Li: Ni: C.
After blending so that the molar ratio of o: Al is 1: 0.8: 0.15: 0.05 and sufficiently mixing with a ball mill,
The air current is increased to 4000 / h so that the oxygen concentration is 19%.
Heat treatment was carried out at a temperature of 750 ° C. for 5 hours while introducing l.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the product had a LiNiO ₂ structure. Further, the total lithium content of the product was measured by an atomic absorption method, and redox titration and neutralization titration were performed. As a result, it was found that the composition was LiNi _0.80 Co _0.15 Al _0.05 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.80 Co _0.15 Al _0.05 O ₂ powder was used as the active material of the positive electrode. (Comparative Example 1) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1 and sufficiently mixed by a ball mill, so that the oxygen concentration became 19%. While introducing 4000 l / h of air flow,
Heat treatment was performed at a temperature of 5 ° C. for 5 hours.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiNiO ₂ , nickel hydroxide was contained as an unreacted product, and the crystallinity of LiNiO ₂ was low. .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNiO ₂ powder was used as an active material of a positive electrode. (Comparative Example 2) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficient mixing with a ball mill, the oxygen concentration was adjusted to 19%. 970 l while introducing an air stream at 4000 l / h.
Heat treatment was performed at a temperature of 5 ° C. for 5 hours.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiNiO ₂ and that it contained nickel oxide. A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiNiO ₂ powder was used as an active material of a positive electrode.

(Comparative Example 3) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficient mixing by a ball mill, the oxygen concentration was reduced to 10%. Heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at a rate of 10 l / h.

The product (particles) obtained was measured by X-ray diffraction, and it was confirmed that the composition was LiNiO ₂ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiNiO ₂ powder was used as an active material of a positive electrode.

(Comparative Example 4) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficient mixing by a ball mill, the oxygen concentration was reduced to 30%. The heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at 8000 l / h.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiNiO ₂ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiNiO ₂ powder was used as an active material of a positive electrode.

Comparative Example 5 Nickel hydroxide powder, lithium hydroxide and cobalt hydroxide powder were blended so that the molar ratio of Li: Ni: Co was 1: 0.5: 0.5. After sufficient mixing, 650 l of air was introduced at an hour so that the oxygen concentration was 19%.
After a heat treatment at a temperature of 15 ° C. for 15 hours, the temperature was lowered.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the product had a LiNiO ₂ structure, indicating that LiNiO ₂ had low crystallinity. Further, for the product, the total amount of lithium was measured by an atomic absorption method, and redox titration and neutralization titration were performed.
It was found that the composition was LiNi _0.5 Co _0.5 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.5 Co _0.5 O ₂ powder was used as the active material of the positive electrode. Comparative Example 6 Nickel hydroxide powder, lithium hydroxide and cobalt hydroxide powder were mixed at a Li: Ni: Co molar ratio of 1:
After mixing at a ratio of 0.5: 0.5 and thoroughly mixing with a ball mill, the mixture was heated at a temperature of 970 ° C. while introducing 4000 l / h of an air stream so that the oxygen concentration became 19%.
After the heat treatment for 5 hours, the temperature was lowered.

The obtained product (particles) was measured by X-ray diffraction. As a result, it was confirmed that the product had a LiNiO ₂ structure, and nickel oxide was detected. Further, for the product, the total amount of lithium was measured by an atomic absorption method,
When redox titration and neutralization titration were performed, LiNi _0.5
It was found that the composition was Co _0.5 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.5 Co _0.5 O ₂ powder was used as an active material of a positive electrode. Comparative Example 7 Nickel hydroxide powder, lithium hydroxide and cobalt hydroxide powder were mixed at a molar ratio of Li: Ni: Co of 1:
After mixing at 0.5: 0.5 and thoroughly mixing with a ball mill, heat treatment was performed at a temperature of 700 ° C. for 15 hours while introducing an air stream at a rate of 10 l / h so that the oxygen concentration became 10%. went. Furthermore, after holding at 900 ° C. for 4 hours, the temperature was lowered.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the product had a LiNiO ₂ structure, and nickel oxide was detected. Further, for the product, the total amount of lithium was measured by an atomic absorption method,
When redox titration and neutralization titration were performed, LiNi _0.5
It was found that the composition was Co _0.5 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.5 Co _0.5 O ₂ powder was used as an active material of a positive electrode. Comparative Example 8 Nickel hydroxide powder, lithium hydroxide and cobalt hydroxide powder were mixed at a Li: Ni: Co molar ratio of 1:
The mixture was mixed at a ratio of 0.5: 0.5 and thoroughly mixed with a ball mill.
Heat treatment was performed for a time. Furthermore, after holding at 900 ° C. for 4 hours, the temperature was lowered.

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the product had a LiNiO ₂ structure, and nickel oxide was detected. Further, for the product, the total amount of lithium was measured by an atomic absorption method,
When redox titration and neutralization titration were performed, LiNi _0.5
It was found that the composition was Co _0.5 O ₂ .

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiNi _0.5 Co _0.5 O ₂ powder was used as an active material of a positive electrode. The specific surface areas of the active materials synthesized in Examples 1 to 8 and Comparative Examples 1 to 8 were measured, and the results are shown in Table 1 below.

With respect to the secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 8, 12 hours after the assembly of the batteries, the internal impedance of the batteries at an alternating current of 1 kHz was measured, and the results are shown in Table 1 below. I do.

After charging the secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 8 at 900 mA to 4.1 V, the batteries were further charged at a constant voltage of 4.1 V (total charging time of 3 hours). Charge / discharge in which the battery was discharged at a constant current of 900 mA until 0.0 V was repeated, and the internal pressure of the battery was measured after 300 cycles. Further, for the secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 8, the same charge / discharge was repeated,
The number of cycles when the discharge capacity was reduced to 80% of the initial capacity was measured, and the results are shown in Table 1 below.

[0173]

[Table 1]

As is clear from Table 1, the non-aqueous solvent secondary batteries of Examples 1 to 8 were different from the secondary batteries of Comparative Examples 1 to 8 in comparison with those of Comparative Examples 1 to 8.
It can be seen that the initial battery internal impedance is low, the increase in battery internal pressure after 300 cycles has been suppressed, and the cycle life is long.

(Example 9) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2, and after sufficiently mixed by a ball mill, the oxygen concentration was reduced to 19%. The heat treatment was performed at a temperature of 670 ° C. for 5 hours while introducing an air flow of 4000 l / h so that

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiMn ₂ O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn ₂ O ₄ powder was used as a positive electrode active material.

(Example 10) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2, and thoroughly mixed by a ball mill. The heat treatment was performed at a temperature of 800 ° C. for 5 hours while introducing an air flow of 4000 l / h so that

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiMn ₂ O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn ₂ O ₄ powder was used as a positive electrode active material.

(Example 11) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2, and after sufficiently mixed by a ball mill, the oxygen concentration was reduced to 19%. The heat treatment was performed at a temperature of 950 ° C. for 5 hours while introducing an air flow of 4000 l / h so that

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiMn ₂ O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn ₂ O ₄ powder was used as a positive electrode active material.

(Example 12) Electrolytic manganese powder, lithium hydroxide and nickel hydroxide powder were blended so that the molar ratio of Li: Mn: Ni was 1.2: 1.9: 0.1.
After sufficiently mixing with a ball mill, air was introduced at a rate of 4000 l / h so that the oxygen concentration became 19%.
Heat treatment was performed at a temperature of 00 ° C. for 5 hours.

When the obtained product was measured by X-ray diffraction, it was confirmed that the composition was LiMn _1.9 Ni _0.1 O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn _1.9 Ni _0.1 O ₄ powder was used as an active material of a positive electrode.

(Example 13) Electrolytic manganese powder, lithium hydroxide and cobalt hydroxide powder were blended so that the molar ratio of Li: Mn: Co was 1.2: 1.9: 0.1.
After sufficiently mixing with a ball mill, air was introduced at a rate of 4000 l / h so that the oxygen concentration became 19%.
Heat treatment was performed at a temperature of 00 ° C. for 5 hours.

When the obtained product was measured by X-ray diffraction, it was confirmed that the composition was LiMn _1.9 Co _0.1 O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn _1.9 Ni _0.1 O ₄ powder was used as an active material of a positive electrode.

(Example 14) Electrolytic manganese powder, lithium hydroxide and lithium borate were blended so that the molar ratio of Li: Mn: B was 1.2: 1.9: 0.1, and the mixture was subjected to ball milling. After sufficient mixing, heat treatment was performed at a temperature of 800 ° C. for 5 hours while introducing 4000 l / h of an air stream so that the oxygen concentration became 19%.

When the obtained product was measured by X-ray diffraction, it was confirmed that the composition was LiMn _1.9 B _0.1 O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn _1.9 B _0.1 O ₄ powder was used as an active material of a positive electrode.

(Example 15) Electrolytic manganese powder, lithium hydroxide and aluminum hydroxide were blended so that the molar ratio of Li: Mn: Al was 1.2: 1.9: 0.1.
After sufficiently mixing with a ball mill, air was introduced at a rate of 4000 l / h so that the oxygen concentration became 19%.
Heat treatment was performed at a temperature of 00 ° C. for 5 hours.

When the obtained product was measured by X-ray diffraction, it was confirmed that the composition was LiMn _1.9 Al _0.1 O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn _1.9 Al _0.1 O ₄ powder was used as an active material of a positive electrode.

Comparative Example 9 Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2, and the mixture was sufficiently mixed by a ball mill. The heat treatment was performed at a temperature of 600 ° C. for 5 hours while introducing an air flow of 4000 l / h so that

The obtained product (particles) was measured by X-ray diffraction, and it was confirmed that the composition was LiMn ₂ O ₄ and the crystallinity of LiMn ₂ O ₄ was low. Except that the LiMn ₂ O ₄ powder was used as a positive electrode active material,
A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled.

(Comparative Example 10) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2, and thoroughly mixed by a ball mill. The heat treatment was carried out at a temperature of 1000 ° C. for 5 hours while introducing an air flow of 4000 l / h so that

The obtained product (particles) was measured by X-ray diffraction, and it was confirmed that the composition was LiMn ₂ O ₄ . Further, MnO ₂ formed by elimination of oxygen from the obtained product was detected.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the above-mentioned LiMn ₂ O ₄ powder was used as an active material of a positive electrode. (Comparative Example 11) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2.
After sufficiently mixing with a ball mill, 800 l of air was introduced at an hour so that the oxygen concentration became 10%.
Heat treatment was performed at a temperature of 5 ° C. for 5 hours.

The obtained product (particles) was measured by X-ray diffraction, and it was confirmed that the composition was LiMn ₂ O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn ₂ O ₄ powder was used as a positive electrode active material.

(Comparative Example 12) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2, and after sufficiently mixed by a ball mill, the oxygen concentration was reduced to 30%. The heat treatment was performed at a temperature of 800 ° C. for 5 hours while introducing an air flow of 8000 l / h so that

When the obtained product (particles) was measured by X-ray diffraction, it was confirmed that the composition was LiMn ₂ O ₄ . A cylindrical non-aqueous solvent secondary battery similar to that of Example 1 was assembled except that the LiMn ₂ O ₄ powder was used as a positive electrode active material.

The obtained Examples 9 to 15 and Comparative Examples 9 to
The specific surface area of the active material synthesized in 12 was measured, and the results are shown in Table 2 below. Examples 9 to 15 and Comparative Examples 9-1
For the secondary battery of No. 2, the internal impedance, the internal pressure of the battery after 300 cycles, and the number of cycles when the discharge capacity decreased to 80% of the initial capacity were measured in the same manner as described above. It is shown in Table 2 below.

[0198]

[Table 2]

As apparent from Table 2, Examples 9 to 15
The non-aqueous solvent secondary batteries have lower initial battery internal impedance than the secondary batteries of Comparative Examples 9 to 12, suppress the increase in battery internal pressure after 300 cycles, and have a longer cycle life. Recognize.

Example 16 <Preparation of Positive Electrode> First, nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1.1: 1, and they were sufficiently mixed by a ball mill. After that, a heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at 4000 l / h so that the oxygen gas concentration became 19%. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiNiO ₂ and lithium oxide were detected.
The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed. As a result, a 1.44% by weight lithium oxide layer was attached to the LiNiO ₂ particle surface on 100% by weight of the LiNiO ₂ particles. I understood that.

After 90% by weight of the above-mentioned LiNiO ₂ powder (active material) and 5% by weight of acetylene black were mixed in a ball mill for 1 hour, the polyvinylidene fluoride was dissolved in N-methyl-2-pyrrolidone so as to be 5% by weight. These were mixed and dispersed in an atmosphere having a humidity of 20% or less while maintaining them at 10 ° C. to prepare a positive electrode slurry. Then,
This slurry was applied to an aluminum foil (current collector), dried, and roll-pressed to produce a positive electrode.

<Preparation of Negative Electrode> First, mesophase pitch-based carbon fibers were graphitized at 3000 ° C. in an argon gas atmosphere, and heat-treated in a chlorine gas atmosphere at 2400 ° C. to synthesize graphitized carbon powder. 94% by weight of the obtained graphitized carbon powder and 6% by weight of polyvinylidene fluoride were dissolved in N-methyl-2-pyrrolidone to prepare a negative electrode slurry. Next, the slurry was applied on a copper foil (current collector), dried, and roll-pressed to produce a negative electrode.

<Preparation of Electrode Group> After the positive electrode, the separator made of a microporous film made of polypropylene, and the negative electrode were respectively laminated in this order, they were spirally wound so that the separator was located on the outer periphery again. An electrode group was prepared.

<Preparation of Nonaqueous Electrolyte> Lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate (mixing volume ratio 1: 2) in an amount of 1.0 mol / l to obtain a nonaqueous electrolyte. A water electrolyte was prepared.

The electrode group and the non-aqueous electrolyte were accommodated in a stainless steel bottomed cylindrical container, and the opening was sealed with a sealing plate to obtain the cylindrical non-aqueous solvent secondary battery shown in FIG. Assembled.

Example 17 Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1.02: 1, and the mixture was sufficiently mixed by a ball mill. 400% of air flow per hour to reach 19%
While introducing 0 l, heat treatment was performed at a temperature of 700 ° C. for 5 hours. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiNiO ₂ and lithium oxide were detected.
The total amount of lithium was measured by an atomic absorption method, and redox titration and neutralization titration were performed. As a result, a 0.1% by weight lithium oxide layer was attached to the LiNiO ₂ particle surface on 100% by weight of the LiNiO ₂ particles. I understood that.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiNiO ₂ powder was used as an active material of a positive electrode. (Example 18) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1.2: 0.9, and the mixture was sufficiently mixed by a ball mill. % At a temperature of 700 ° C. for 5 hours and further at 580 ° C.
Heat treatment was performed for 0 hours. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, Li _1.1 Ni _0.9 O ₂ and lithium oxide were detected. When the lithium amount was measured by atomic absorption spectrometry was conducted redox titration, neutralization titration, Li _1.1 Ni _0.9
O The ₂ particle surface 1.5 wt% of lithium oxide layer with respect to Li _1.1 Ni _0.9 O ₂ particles 100 wt% were found to be deposited.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the LiNiO ₂ powder was used as a positive electrode active material. (Example 19) Nickel hydroxide powder, lithium hydroxide and cobalt hydroxide powder were blended so that the molar ratio of Li: Ni: Co was 1: 0.8: 0.2, and sufficiently mixed with a ball mill. After mixing, heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at 4000 l / h so that the oxygen concentration became 19%. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiNi _0.8 Co _0.2 O ₂ and lithium oxide were detected. Measure the total amount of lithium by atomic absorption method,
When redox titration and neutralization titration were performed, LiNi
_{On the} surface of the _0.8 Co _0.2 O ₂ particles, LiNi _0.8 Co
It was found that 0.1% by weight of the lithium oxide layer was attached to 100% by weight of the _0.2 O ₂ particles.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiNi _0.8 Co _0.2 O ₂ powder was used as an active material of a positive electrode. Example 20 Nickel hydroxide powder, lithium hydroxide and lithium borate were mixed at a molar ratio of Li: Ni: B of 1: 0.9.
7: 0.3 and sufficiently mixed by a ball mill, and then heat-treated at a temperature of 700 ° C. for 1 hour while introducing 4000 l / h of an air stream so that the oxygen concentration became 19%. . Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiNi _0.97 B _0.03 O ₂ and lithium oxide were detected. The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed. As a result, LiNi _0.97 B
_{On the} surface of the _0.03 O ₂ particles, LiNi _0.97 B _0.03 O ₂ particles 1
It was found that 0.1% by weight of the lithium oxide layer was adhered to 00% by weight.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiNi _0.97 B _0.03 O ₂ powder was used as a positive electrode active material. (Example 21) Nickel hydroxide powder, lithium hydroxide and aluminum hydroxide were blended so that the molar ratio of Li: Ni: Al was 1.1: 0.97: 0.3, and the mixture was sufficiently mixed with a ball mill. After mixing at a temperature of 700 ° C. while introducing 4000 l / h of air air so that the oxygen concentration becomes 19%.
At a temperature of 5 hours. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiNi _0.97 Al _0.03 O ₂ and lithium oxide were detected. Measure the total amount of lithium by atomic absorption method,
When redox titration and neutralization titration were performed, LiNi _0.97
On the surface of the Al _0.03 O ₂ particles, LiNi _0.97 Al _0.03 O ₂
It was found that 0.1% by weight of the lithium oxide layer was attached to 100% by weight of the particles.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiNi _0.97 Al _0.03 O ₂ powder was used as a positive electrode active material. (Example 22) Electrolytic manganese powder and lithium hydroxide were blended so that the molar ratio of Li: Mn was 1.2: 2.
After sufficiently mixing with a ball mill, air was introduced at a rate of 4000 l / h so that the oxygen concentration became 19%.
Heat treatment was performed at a temperature of 00 ° C. for 5 hours. In addition, 650 ° C
For 1 hour, an oxygen gas flow was introduced to maintain the oxygen gas concentration at 95% or more, and then the temperature was lowered.

When the obtained product was measured by X-ray diffraction, LiMn ₂ O ₄ and lithium oxide were detected. When the lithium amount was measured by atomic absorption spectrometry was conducted redox titration, neutralization titration, the LiMn ₂ O ₄ particle surface with respect to LiMn ₂ O ₄ particles 100 wt% 1.
It was found that a 2% by weight lithium oxide layer had been deposited.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiMn ₂ O ₄ powder was used as an active material of a positive electrode. (Example 23) Electrolytic manganese powder, lithium hydroxide and nickel hydroxide powder were mixed at a molar ratio of Li: Mn: Ni of 1.
2: 1.9: 0.1, and after sufficient mixing by a ball mill, at a temperature of 800 ° C. for 5 hours while introducing 4000 l / h of air air so that the oxygen concentration becomes 19%. Heat treatment was performed. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiMn _1.9 Ni _0.1 O ₄ and lithium oxide were detected. Measure the total amount of lithium by atomic absorption method,
When redox titration and neutralization titration were performed, LiMn _1.9
On the surface of the Ni _0.1 O ₄ particles, LiMn _1.9 Ni _0.1 O ₄
It was found that 1.2% by weight of the lithium oxide layer was attached to 100% by weight of the particles.

A cylindrical nonaqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiMn _1.9 Ni _0.1 O ₄ powder was used as a positive electrode active material. Example 24 Electrolytic manganese powder, lithium hydroxide and cobalt hydroxide powder were mixed at a Li: Mn: Co molar ratio of 1.
2: 1.9: 0.1, and after sufficient mixing by a ball mill, at a temperature of 800 ° C. for 5 hours while introducing 4000 l / h of air air so that the oxygen concentration becomes 19%. Heat treatment was performed. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiMn _1.9 Co _0.1 O ₄ and lithium oxide were detected. Measure the total amount of lithium by atomic absorption method,
When redox titration and neutralization titration were performed, LiMn _1.9
On the surface of the Co _0.1 O ₄ particles, LiMn _1.9 Co _0.1 O ₄
It was found that 1.2% by weight of the lithium oxide layer was attached to 100% by weight of the particles.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the LiMn _1.9 Ni _0.1 O ₄ powder was used as a positive electrode active material. (Example 25) Electrolytic manganese powder, lithium hydroxide and lithium borate were mixed at a molar ratio of Li: Mn: B of 1.2: 1.
9: 0.1 and sufficiently mixed in a ball mill, and then heat-treated at a temperature of 800 ° C. for 5 hours while introducing an air stream at 4000 l / h so that the oxygen concentration became 19%. . Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiMn _1.9 B _0.1 O ₄ and lithium oxide were detected. The total amount of lithium was measured by the atomic absorption method, and the redox titration and the neutralization titration were performed. As a result, LiMn _1.9 B
_{On the} surface of the _0.1 O ₄ particles, LiMn _1.9 B _0.1 O ₄ particles 1
It was found that 1.2% by weight of the lithium oxide layer was adhered to 00% by weight.

A cylindrical non-aqueous solvent secondary battery similar to that in Example 16 was assembled except that the above-mentioned LiMn _1.9 B _0.1 O ₄ powder was used as a positive electrode active material. (Example 26) An electrolytic manganese powder, lithium hydroxide and aluminum hydroxide having a molar ratio of Li: Mn: Al of 1.
2: 1.9: 0.1, and after sufficient mixing by a ball mill, at a temperature of 800 ° C. for 5 hours while introducing 4000 l / h of air air so that the oxygen concentration becomes 19%. Heat treatment was performed. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiMn _1.9 Al _0.1 O ₄ and lithium oxide were detected. Measure the total amount of lithium by atomic absorption method,
When redox titration and neutralization titration were performed, LiMn _1.9
On the surface of the Al _0.1 O ₄ particles, LiMn _1.9 Al _0.1 O ₄
It was found that 1.2% by weight of the lithium oxide layer was attached to 100% by weight of the particles.

A cylindrical non-aqueous solvent secondary battery similar to that in Example 16 was assembled except that the above-mentioned LiMn _1.9 Al _0.1 O ₄ powder was used as a positive electrode active material. (Example 27) Nickel hydroxide powder, cobalt hydroxide powder, aluminum hydroxide and lithium hydroxide were mixed with Li: N
i: Co: Al molar ratio of 1.1: 0.8: 0.15:
The mixture was blended so as to be 0.05 and sufficiently mixed by a ball mill, and then heat-treated at a temperature of 700 ° C. for 5 hours while introducing 4000 l / h of an air stream so that the oxygen concentration became 19%. Further, the temperature was lowered after introducing an oxygen gas flow at 650 ° C. for 1 hour so as to maintain the oxygen gas concentration at 95% or more.

When the obtained product was measured by X-ray diffraction, LiNi _0.80 Co _0.15 Al _0.05 O ₂ and lithium oxide were detected. The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed.
Ni _0.80 Co _0.15 Al _0.05 O ₂
It was found that a lithium oxide layer of 0.1% by weight was attached to 100% by weight of _0.80 Co _0.15 Al _0.05 O ₂ particles.

A cylindrical non-aqueous solvent secondary battery similar to that in Example 16 was assembled except that the above-mentioned LiNi _0.80 Co _0.15 Al _0.05 O ₂ powder was used as an active material of a positive electrode. (Example 28) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1.1: 1, and after sufficiently mixed by a ball mill, the oxygen gas concentration was reduced to 19%. Heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at 4000 l / h. Furthermore,
At 650 ° C. for one hour, an oxygen gas flow is introduced to reduce the oxygen gas concentration to 9
After maintaining the temperature at 5% or more, the temperature was lowered.

When the obtained product was measured by X-ray diffraction, LiNiO ₂ and lithium oxide were detected.
When the lithium amount was measured by atomic absorption spectrometry was conducted redox titration, neutralization titration, the LiNiO ₂ particle surface, LiNiO ₂ particles 1.5 wt% of lithium oxide layer with respect to 100 wt% is deposited I understood that.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the LiNiO ₂ powder was used as a positive electrode active material. (Comparative Example 13) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficiently mixed by a ball mill, the oxygen concentration was adjusted to 10%. 700 ° C. while introducing an air flow of 10 l / h
At a temperature of 5 hours.

When the obtained product was measured by X-ray diffraction, lithium hydroxide, lithium oxide and LiNiO
₂ has been detected. The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed.
O The ₂ particle surface, it was found that the lithium layer and lithium hydroxide layer oxide is deposited 0.05 wt% combined with respect to LiNiO ₂ particles 100 wt%.

A cylindrical non-aqueous solvent secondary battery similar to that of Example 16 was assembled except that the above-mentioned LiNiO ₂ powder was used as an active material of a positive electrode. (Comparative Example 14) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1.25: 1, and the mixture was sufficiently mixed using a ball mill.
%, And heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at 4000 l / h.

When the obtained product was measured by X-ray diffraction, it was found that lithium carbonate, lithium oxide and LiNiO ₂
Was detected. The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed.
The O ₂ particle surface, it was found that 1.8 wt% of lithium oxide layer and 0.4 wt% of lithium carbonate layer is deposited against LiNiO ₂ particles 100 wt%.

A cylindrical non-aqueous solvent secondary battery similar to that in Example 16 was assembled except that the LiNiO ₂ powder was used as a positive electrode active material. (Comparative Example 15) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficiently mixed by a ball mill, the oxygen concentration was adjusted to 10%. 700 ° C. while introducing an air flow of 10 l / h
At a temperature of 5 hours.

When the obtained product was measured by X-ray diffraction, lithium hydroxide, lithium oxide and LiNiO
₂ has been detected. The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed.
O The ₂ particle surface, it was found that the lithium layer and lithium hydroxide layer oxide is deposited 0.05 wt% combined with respect to LiNiO ₂ particles 100 wt%.

Using a material obtained by adding 1.5% by weight of lithium carbonate to 100% by weight of the above-mentioned LiNiO ₂ powder as an active material of the positive electrode, a positive electrode was prepared in the same manner as in Example 16, and a slurry was prepared. Occasionally, the slurry hardened and a positive electrode could not be produced.

(Comparative Example 16) Nickel hydroxide powder and lithium hydroxide were blended so that the molar ratio of Li: Ni was 1: 1. After sufficient mixing by a ball mill, the oxygen concentration was reduced to 10%. Heat treatment was performed at a temperature of 700 ° C. for 5 hours while introducing an air stream at a rate of 10 l / h.

When the obtained product was measured by X-ray diffraction, lithium hydroxide, lithium oxide and LiNiO
₂ has been detected. The total amount of lithium was measured by the atomic absorption method, and redox titration and neutralization titration were performed.
O The ₂ particle surface, it was found that the lithium layer and lithium hydroxide layer oxide is deposited 0.05 wt% combined with respect to LiNiO ₂ particles 100 wt%.

Using a material obtained by adding 1.5% by weight of lithium hydroxide to 100% by weight of the LiNiO ₂ powder as the active material of the positive electrode, a positive electrode was produced in the same manner as in Example 16, and the slurry was obtained. The slurry hardened during preparation, and a positive electrode could not be produced.

Examples 16 to 28 and Comparative Examples 13 to 14
The number of internal short-circuit occurrences (out of 100) when the secondary battery was assembled was examined, and the results are shown in Table 3 below. Regarding the secondary batteries of Examples 16 to 28 and Comparative Examples 13 to 14, 24 hours passed after battery assembly and 85
After standing at 24 ° C. for 24 hours, the internal impedance was measured with an alternating current at a frequency of 1 kHz, and the results are also shown in Table 3 below.

Examples 16 to 28 and Comparative Example 13
Charges up to 4.1V for 900
After charging at mA, charging and discharging were further performed at a constant voltage of 4.1 V (total charging time: 5 hours) and discharging at a constant current of 900 mA to 3.0 V, and the discharge capacity was reduced to 80% of the initial capacity. The number of cycles at the time was measured, and the results are shown in Table 3 below.

[0243]

[Table 3]

The non-aqueous solvent secondary batteries of Examples 16 to 28
It can be seen that, compared to the secondary batteries of Comparative Examples 13 and 14, short-circuiting at the time of winding is less and the cycle life is longer. In addition, it can be seen that the non-aqueous solvent secondary batteries of Examples 16 to 28 can suppress an increase in internal impedance after storage at high temperature and have an excellent capacity recovery rate after storage at high temperature.

[0245]

As described above, according to the present invention,
A method for manufacturing a non-aqueous solvent secondary battery having improved internal pressure characteristics, large current discharge characteristics, and cycle characteristics can be provided. Further, according to the present invention, it is possible to provide a non-aqueous solvent secondary battery having improved cycle characteristics and large current discharge characteristics, and having a high capacity recovery rate after storage in a high-temperature environment.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a cylindrical non-aqueous solvent secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container, 3 ... Electrode group, 4 ... Positive electrode, 5 ... Separator, 6 ... Negative electrode, 8 ... Sealing plate, 9 ... Positive electrode terminal.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Isazaki 72 Horikawa-cho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Inside the Toshiba Kawasaki Office (72) Inventor Yuji Sato 72 Horikawacho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Toshiba Corporation Inside the Kawasaki Plant (56) References JP-A-7-153466 (JP, A) JP-A-4-237970 (JP, A) JP-A 8-195200 (JP, A) JP-A 9-147867 (JP, A) A) JP-A-2-139860 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 4/58 H01M 4/02 H01M 4/04 H01M 10/40

Claims (3)

(57) [Claims] 1. A cathode active material and vinylidene fluoride-based fluorine
The current collector is coated with a positive electrode layer containing a resin-containing binder.
A positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein the positive electrode active material is (a) LiNiO ₂ or Li
The composition in which a part of nickel of NiO ₂ is replaced by another element
Containing lithium-containing nickel oxide as a main component
And 0.1% to 1.5% by weight formed on the surface of the particles.
% Lithium oxide layer, or (b) L
One of manganese of iMn ₂ O ₄ or LiMn ₂ O ₄
Lithium manganese composite acid with a part replaced by another element
And particles formed on the surface of the particles.
0.1% to 1.5% by weight of a lithium oxide layer.
Non-aqueous solvent secondary battery, characterized by that. 2. The element that replaces nickel in the lithium-containing nickel oxide is Co, Mn, B, or Al.
2. The non-aqueous solvent secondary battery according to claim 1 , wherein the non-aqueous solvent secondary battery is one or more elements selected from Li and Li. 3. The element substituted with manganese in the lithium manganese composite oxide is Co, Ni, B, Al
2. The non-aqueous solvent secondary battery according to claim 1 , wherein the non-aqueous solvent secondary battery is one or more elements selected from Li and Li.