JP2001266848A - Non-aqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous secondary battery of a flat shape which has high precision of thickness and has small internal resistance and little variations of capacity. SOLUTION: The non-aqueous secondary battery has a flat shape and comprises a positive electrode, a negative electrode and a non-aqueous electrolyte containing a lithium salt and is sealed by a battery container 1, 2 and has an energy capacity of 30 W/h or more, and a volume energy density of 180 Wh/l or more. The positive electrode 101a of this non-aqueous secondary battery contains at least a manganese oxide as an active material, and the mixture of the positive electrode composed of the active material, a conductor and a binder has a residual moisture amount of 400 ppm or less, based on the coulometry analysis of the Carl Fischer moisture measurement method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous secondary battery, and more particularly to a non-aqueous secondary battery for a power storage system.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of global environment preservation and effective use of energy with the aim of conserving resources, home-use decentralized power storage systems and electric vehicles for storing power at night or storing power by solar power generation have been developed. Is attracting attention. For example, Japanese Unexamined Patent Publication No. 6-86463 discloses a system capable of supplying energy to an energy consumer under optimal conditions.
A total system combining gas cogeneration, a fuel cell, a storage battery, and the like has been proposed. A secondary battery used in such a power storage system requires a large battery having a large capacity, unlike a small secondary battery for a portable device having an energy capacity of 10 Wh or less. In these systems, a plurality of secondary batteries are usually arranged in series, and the batteries are usually used as a battery pack of, for example, 50 to 400 V. In most cases, lead-acid batteries are collectively used.

On the other hand, in the field of small rechargeable batteries for portable devices, new types of batteries such as nickel-metal hydride batteries and lithium rechargeable batteries have been developed in order to meet the needs of small size and high capacity. Batteries having a volume energy density are commercially available. In particular, lithium-ion batteries have the potential to achieve a high volume energy density exceeding 350 Wh / l, and are reliable in terms of safety, cycle characteristics, and the like, compared to lithium secondary batteries using lithium metal as the negative electrode. The market is dramatically increasing due to its superiority.

[0004] Against the background of such technical achievements, in the field of large-sized batteries for power storage systems, research and development for the practical use of lithium-ion batteries as high energy density batteries has been carried out. Union (L
IBES).

[0005] These large-sized lithium ion batteries have an energy capacity of about 100 to 400 Wh and a volume energy density of 200 to 300 Wh / l, which is the level of a small secondary battery for portable equipment. The shape is typically a cylindrical shape having a diameter of about 50 to 70 mm and a length of about 250 to 450 mm, and a rectangular prism having a thickness of about 35 to 50 mm or an oblong prism.

[0006] As for the thin lithium secondary battery, a film battery in which a thin film of 1 mm or less in which a metal and a resin are laminated, for example, is accommodated in a thin exterior (Japanese Patent Application Laid-Open Nos. Hei 5-159775 and Hei 7-1995). No. 57788, etc.), and a small rectangular battery having a thickness of about 2 to 15 mm (Japanese Patent Application Laid-Open Nos. 8-195204 and 8-138727).
And Japanese Patent Application Laid-Open No. 9-213286) are known. The purpose of these lithium secondary batteries is to respond to the miniaturization and thinning of portable devices.
For example, a thin battery having a thickness of several mm and an area of about JIS A4 size that can be stored in the bottom surface of a portable personal computer has been disclosed (Japanese Unexamined Patent Publication No. 5-283105). The capacity is too small to be used as a secondary battery for the system.

On the other hand, it has been proposed to use lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide and the like as a positive electrode active material for a lithium secondary battery. These materials have a layer structure or a spinel structure, and have a property of forming an interlayer compound with lithium. Therefore, these materials have already been put to practical use as small secondary batteries for portable devices.

However, each of these materials has advantages and disadvantages. When a lithium composite cobalt oxide or a lithium composite nickel oxide is used, a battery having high true density, high charge / discharge capacity, and high capacity can be expected. On the other hand, raw material costs or material synthesis costs are high, and safety is inferior to lithium composite manganese oxides (LikeXi
e et al. , Mat. Res. Soc. Sym
p. Proc. , Vol. 393 1995, 285-
304). On the other hand, when using lithium composite manganese oxide, the material cost is low and the safety is higher than lithium composite cobalt oxide and lithium composite nickel oxide, so it is a material suitable for large batteries, It is inferior in that the true density and the charge / discharge capacity are low.

Further, when a manganese oxide such as the above-described lithium composite manganese oxide is used as a positive electrode active material, there has been a problem that the residual moisture derived from the raw materials during the synthesis becomes extremely large. This is because cobalt oxide and nickel oxide are synthesized at a temperature of about 650 ° C. to 750 ° C., while manganese oxide is synthesized at a relatively low temperature of about 450 ° C. This is presumably because water tends to be adsorbed on fine pores on the surface of the manganese oxide and easily remains. As described above, when the residual moisture of the material of the positive electrode active material is large, a large amount of gas is generated due to the decomposition of water at the time of initial charging.

In response to such generation of gas, a conventional small battery for portable equipment using a lithium composite manganese oxide as a positive electrode material has a wound electrode in a cylindrical or square metal container. With such a structure, the electrode is unlikely to be deformed by the pressure of the generated gas. Therefore, the generated gas is pushed out from between the electrodes as the pressure rises, and there is no problem that stagnation occurs between the electrodes.

[0011]

On the other hand, in the flat battery as described above, as the thickness of the battery is reduced, the area of the front and back surfaces of the battery with respect to the thickness of the battery becomes relatively large, and the inside of the battery is reduced. The force for holding down the electrode surface housed in the battery is weakened. In particular, when a flat battery is manufactured in a large-sized lithium secondary battery (energy capacity of 30 Wh or more) used in a power storage system, the tendency is strong.
In the case of a lithium ion battery having a thickness of 00 Wh and a thickness of 6 mm,
The size of the battery front and back is 600 cm ² (one side)
Very large for thickness. From this, a flat lithium secondary battery was manufactured using a manganese oxide such as a lithium composite manganese oxide as a positive electrode active material,
When a large amount of gas is generated inside the battery due to decomposition of water during initial charging, it is difficult to suppress the battery from swelling. As a result, there has been a problem that the thickness of the battery becomes thicker than designed due to the above-mentioned swelling and a problem that the generated gas stays between the electrodes without being pushed out, thereby causing an uneven reaction of the electrodes. Furthermore, as described above, since the electrodes exhibit non-uniform reactions, a plurality of flat lithium secondary batteries have a problem that the internal resistance and capacity of the batteries vary.

The present invention has been made to solve the above problems, and has a large capacity of 30 Wh or more and a capacity of 180 Wh /
The object of the present invention is to provide a flat non-aqueous secondary battery having a volume energy density of 1 l or more, relatively inexpensive and highly safe, and capable of preventing swelling of the battery and variations in the internal resistance and capacity of the battery. And

[0013]

In order to achieve the above object, a non-aqueous secondary battery of the present invention comprises a positive electrode, a negative electrode and a non-aqueous electrolyte containing a lithium salt, and is sealed in a battery container and has an energy capacity of 30 Wh. And a non-aqueous secondary battery having a flat shape with a volume energy density of 180 Wh / l or more, wherein the positive electrode contains at least manganese oxide as an active material, and the active material, the conductive material, and the binder It is configured such that the residual water content by the coulometric method of the Karl Fischer moisture measurement method of the positive electrode mixture composed of the agent is 400 ppm or less.

The manganese oxide is LiMn ₂ in which a part of manganese has been replaced by lithium to make lithium excess.
It can be O ₄ .

The manganese oxide may be LiMn ₂ O ₄ in which a part of manganese is replaced by at least magnesium or aluminum.

The shape of the wide flat portion of the flat battery container may be rectangular.

The flat non-aqueous secondary battery may be configured to have a thickness of less than 12 mm.

The thickness of the battery container is 0.2 mm or more and 1
mm or less.

The operation of the present invention will be described below.

The non-aqueous secondary battery of the present invention has a flat shape having a positive electrode, a negative electrode and a non-aqueous electrolyte containing a lithium salt, sealed in a battery container and having an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. The non-aqueous secondary battery has a suitable non-aqueous secondary battery for a power storage system.

Further, the positive electrode is configured to contain at least manganese oxide as an active material, and can be manufactured at a relatively low price and has high safety.

Furthermore, since the positive electrode mixture comprising the active material, the conductive material, and the binder is configured so that the residual water content by the coulometric method of Karl Fischer's water content measurement method is 400 ppm or less, particularly at the time of initial charging. In addition to reducing the amount of gas generated due to the decomposition of water in the battery at the same time, it is possible to suppress a decrease in the initial charge / discharge efficiency, and to prevent the battery from swelling and the non-uniform reaction of the electrode due to accumulation of generated gas between electrodes. Can be. As a result, the cycle life of the battery can be improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-aqueous secondary battery according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flat rectangle (note type) according to an embodiment of the present invention.
FIG. 2 is a plan view and a side view of the non-aqueous secondary battery for a power storage system of FIG. 1, and FIG. 2 is a side view showing a configuration of an electrode laminate housed inside the battery shown in FIG.

As shown in FIGS. 1 and 2, the non-aqueous secondary battery according to the present embodiment has a battery case (battery container) including an upper lid 1 and a bottom container 2, and is housed in the battery case. And an electrode stack including a plurality of positive electrodes 101a, negative electrodes 101b and 101c, and a separator 104. In the case of a flat nonaqueous secondary battery as in this embodiment, the positive electrode 101a and the negative electrode 101b (or the negative electrode 101c disposed on both outer sides of the stacked body) are provided with, for example, a separator 104 as shown in FIG. The present invention is not particularly limited to this form, and the number of layers and the like can be variously changed according to the required capacity and the like. .

The positive electrode current collector 105a of each positive electrode 101a is:
Each of the negative electrodes 101 is electrically connected to the positive electrode terminal 3.
The negative electrode current collectors 105b of b and 101c are electrically connected to the negative electrode terminal 4. The positive terminal 3 and the negative terminal 4 are
It is attached in a state insulated from the battery case, that is, the top cover 1.

The upper lid 1 and the bottom container 2 are welded by melting the upper lid at the point A shown in the enlarged view of FIG. The upper lid 1 is provided with a liquid injection port 5 for an electrolytic solution. After the liquid injection, the liquid is sealed with a sealing film 6 made of an aluminum-modified polypropylene laminated film. In this case, the sealing film 6 can also have a function as a safety valve for releasing when the internal pressure inside the battery rises. The dimensions of the nonaqueous secondary battery shown in FIGS. 1 and 2 are, for example, 300 mm long × 210 mm wide × 6 mm thick, and LiMn ₂ O ₄ and the negative electrode 1
In the case of a lithium secondary battery using a carbon material for 01b and 101c, for example, it can be used for a power storage system.

The positive electrode active material used for the positive electrode 101a is not particularly limited as long as it contains at least manganese oxide. As the manganese oxide, a lithium composite manganese oxide represented by LiMn ₂ O ₄ , and a system in which one or more different metal elements such as magnesium and aluminum are added to these composite oxides (for example, at least a part of manganese is at least LiMn ₂ O ₄ which is substituted by magnesium or aluminum), and further being lithium, LiMn ₂ O ₄ that the oxygen or the like was excessive relative to the stoichiometric ratio (e.g., lithium-rich part of the manganese is substituted with lithium LiM
n ₂ O ₄ ) can be used. By using LiMn2O4 in which a part of manganese is substituted by magnesium, aluminum or lithium, the cycle life of the battery can be improved.

In order to increase the capacity of the battery, lithium composite cobalt oxide, lithium composite nickel oxide,
Alternatively, a mixture of these materials, or a system in which one or more kinds of different metal elements are added to these composite oxides, can be used in combination.

Further, the positive electrode mixture of the positive electrode 101a comprising at least an active material using manganese oxide, a conductive material, and a binder has a residual water content of 400 ppm or less, more preferably 400 ppm or less according to the coulometric method of the Karl Fischer moisture measurement method. Is 2
Those having a concentration of 50 ppm or less, more preferably 100 ppm or less, are used. In order to adjust the residual water content in this manner, for example, a method of reducing the moisture content by performing the synthesis of manganese oxide in a low humidity environment, or drying the synthesized manganese oxide A method of removing water or the like can be employed. This value is 400 ppm
In particular, when the initial charge is performed, a large amount of gas is generated due to decomposition of water in the battery at the time of initial charging, the initial charge / discharge efficiency is reduced, the battery swells, and the generated gas collects between the electrodes. Heterogeneous reaction occurs. As a result, the cycle life of the battery is significantly reduced. From this viewpoint, the residual water content is set to 400 ppm or less,
It is more preferably at most ppm, and even more preferably at most 100 ppm.

The negative electrode active material used for the negative electrodes 101b and 101c is not particularly limited as long as it is a lithium-based negative electrode material. This is preferable because it improves the reliability such as. As a material capable of doping and undoping lithium, a graphite-based material, a carbon-based material, which is used as a negative electrode material of a known lithium ion battery,
Examples thereof include metal oxides such as tin oxides and silicon oxides, and conductive polymers represented by polyacene-based organic semiconductors. In particular, from the viewpoint of safety, thermal analysis (DSC:
A polyacene-based substance having a small calorific value at about 150 ° C. in differential scanning calorimetry or a material containing the same is desirable.

The structure of the separator 104 is not particularly limited, but a single-layer or multi-layer separator can be used, and at least one of the separators is preferably made of a nonwoven fabric. In this case, the cycle characteristics are improved. . The material of the separator 104 is also not particularly limited, and examples thereof include polyethylene, polyolefin such as polypropylene, polyamide, kraft paper, glass, and the like. Polyethylene and polypropylene are preferred from the viewpoints of cost, water content, and the like. preferable. Also, the separator 104
When using polyethylene or polypropylene,
The basis weight of the separator is preferably 5 g / m ² or more and 30
g / m ² or less, more preferably 5 g / m ² or more and 20
g / m ² or less, more preferably 8 g / m ² or more.
0 g / m ² or less. The basis weight of the separator is 30 g
/ M ² , the separator becomes too thick,
In addition, the porosity is decreased, and the internal resistance of the battery is increased. If the porosity is less than 5 g / m ² , it is not preferable because practical strength cannot be obtained.

As the electrolyte of the non-aqueous secondary battery of the present embodiment, a known non-aqueous electrolyte containing a lithium salt can be used, and is appropriately selected according to the conditions of use such as a positive electrode material, a negative electrode material, and a charging voltage. , More specifically LiPF ₆ ,
LiBF ₄ , a lithium salt such as LiClO ₄ , propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyrolactone, methyl acetate, methyl formate, or a mixed solvent of two or more of these Examples thereof include those dissolved in an organic solvent. The concentration of the electrolytic solution is not particularly limited, but is generally practically 0.5 mol / l to 2 mol / l. The electrolytic solution has a water content of 100 ppm or less for suppressing gas generation. It is preferable to use one. In this specification, the term "non-aqueous electrolyte" means a concept including a non-aqueous electrolyte and an organic electrolyte, and also a concept including a gel or solid electrolyte.

It should be noted that the non-aqueous secondary battery of the present invention is configured so that the pressure in the battery is lower than the atmospheric pressure even when gas is generated from the positive electrode mixture due to residual moisture. Is preferably 650 Torr or less, particularly preferably 550 Torr or less. This pressure is determined in consideration of the separator used, the type of electrolyte, the material and thickness of the battery can, and the shape of the battery. When the internal pressure is equal to or higher than the atmospheric pressure, the battery becomes larger than the designed thickness, or the thickness of the battery varies greatly, which causes variations in the internal resistance and capacity of the battery, which is not preferable.

The non-aqueous secondary battery configured as described above can be used in a home power storage system (nighttime power storage, cogeneration, solar power generation, etc.), a power storage system of an electric vehicle, etc., and has a large capacity. And it can have a high energy density. In this case, the energy capacity is preferably 30 Wh or more, more preferably 50 Wh or more, and the energy density is preferably 180 Wh /
1 or more, more preferably 200 Wh / l or more. When the energy capacity is less than 30 Wh or when the volume energy density is less than 180 Wh / l, the capacity is small for use in a power storage system, and it is necessary to increase the number of series-parallel batteries in order to obtain a sufficient system capacity. In addition, it is not preferable for a power storage system because a compact design is difficult.

In general, a large lithium secondary battery (energy capacity of 30 Wh or more) for a power storage system can obtain a high energy density, but its battery design is an extension of a small battery for a portable device. Alternatively, the battery has a cylindrical shape, a square shape, or the like having a thickness three times or more that of a small battery for a portable device. In this case, heat easily accumulates inside the battery due to Joule heat generated by the internal resistance of the battery during charge / discharge or internal heat generated by the battery due to a change in entropy of the active material due to the entrance and exit of lithium ions. For this reason, the temperature difference between the temperature inside the battery and the temperature near the battery surface increases, and the internal resistance differs accordingly. As a result, the charge amount and the voltage are likely to vary. Also, since a plurality of batteries of this type are used as assembled batteries, the heat storage easiness varies depending on the installation position of the batteries in the system, causing variations among the batteries, and accurate control of the entire assembled battery. It becomes difficult. In addition, the battery temperature rises due to insufficient heat dissipation during high-rate charging and discharging, and the battery is put in an unfavorable state. Problems such as induction of reliability and, in particular, safety remain.

The flat non-aqueous secondary battery of the present embodiment has a large heat radiation area and is advantageous for heat radiation, so that the above problems can be solved. That is, the non-aqueous secondary battery of the present embodiment has a flat shape,
Its thickness is preferably less than 12 mm, more preferably less than 10 mm, even more preferably less than 8 mm. The lower limit of the thickness is practically 2 mm or more in consideration of the filling rate of the electrode and the battery size (the smaller the thickness, the larger the area for obtaining the same capacity). Battery thickness is 12
mm or more, it becomes difficult to sufficiently radiate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the vicinity of the battery surface increases, resulting in a difference in internal resistance. , The variation in voltage increases.
Although the specific thickness is appropriately determined according to the battery capacity and the energy density, it is preferable to design the thickness so as to obtain the expected heat radiation characteristics.

The shape of the non-aqueous secondary battery of the present embodiment is, for example, that the flat front and back surfaces are square, circular,
Various shapes such as an oval shape can be used. In the case of a square shape, the shape is generally a rectangle, but it can also be a polygon such as a triangle or a hexagon. Further, it may be a cylindrical shape such as a thin-walled cylinder. In the case of a cylindrical shape, the thickness of the cylinder is the thickness referred to here. Further, from the viewpoint of ease of production, the flat front and back surfaces of the battery are preferably rectangular, and a notebook-type shape as shown in FIG. 1 is preferable.

The material used for the top cover 1 and the bottom container 2 serving as a battery case is appropriately selected depending on the use and shape of the battery, and is not particularly limited.
Aluminum and the like are common and practical. Also,
The thickness of the battery case is also appropriately determined depending on the use and shape of the battery or the material of the battery case, and is not particularly limited. Preferably, the thickness of a portion that is 80% or more of the battery surface area (the thickness of the portion having the largest area constituting the battery container)
Is 0.2 mm or more. If the thickness is less than 0.2 mm, the strength required for manufacturing the battery cannot be obtained, which is not desirable. From this viewpoint, the thickness is more preferably 0.3 mm or more. Further, it is desirable that the thickness of the portion is 1 mm or less. When the thickness exceeds 1 mm, the force for pressing down the electrode surface increases, but it is not desirable because the internal volume of the battery is reduced and a sufficient capacity cannot be obtained, or the weight increases, which is not desirable. Preferably 0.
7 mm or less.

As described above, the thickness of the non-aqueous secondary battery is set to 1
By designing it to be less than 2 mm, for example,
When the battery has a large capacity of 0 Wh or more and a high energy density of 180 Wh / l, the battery temperature rise is small even during high-rate charging and discharging, and excellent heat radiation characteristics can be obtained. Therefore, heat storage of the battery due to internal heat generation is reduced, and as a result, thermal runaway of the battery can be suppressed, and a non-aqueous secondary battery excellent in reliability and safety can be provided.

[0040]

The present invention will be described more specifically below with reference to examples of the present invention. Example 1 (1) Li ₁ . ₀₇ Mn ₁ . ₉₃ O ₄ 100 parts by weight, acetylene black 3 parts by weight, polyvinylidene difluoride (P
VDF) 7 parts by weight of N-methylpyrrolidone (NMP) 1
And 100 parts by weight to obtain a positive electrode mixture slurry. The slurry was applied to both sides of a 20 μm-thick aluminum foil serving as a current collector, dried, and then pressed to obtain a positive electrode. FIG.
(A) is an explanatory view of a positive electrode. In this embodiment, the positive electrode 1
The application area (W1 × W2) of 01a is 262.5 × 19
2 mm ² and a 20 μm thick current collector 105 a (FIG. 2).
) Is applied with a thickness of 108 μm. As a result, the electrode thickness t is 236 μm. Also,
A positive electrode current collector 106a to which the positive electrode mixture is not applied is provided on the short side of the electrode, and a hole of φ3 mm is formed.

The fabricated electrode was placed under reduced pressure before assembling the battery.
It was re-dried at 170 ° C. for about 5 hours. Positive electrode mixture 1 for this electrode
0 g is weighed, and a Karl Fischer Coulometric Moisture Analyzer (Model KF-100) manufactured by Mitsubishi Chemical Corporation and a moisture vaporizer (VA)
-100 ppm), the residual water content was 280 ppm.

(2) Graphitized mesocarbon microbeads (MCMB, manufactured by Osaka Gas Chemical Company, product number 6-28) 1
00 parts by weight and 10 parts by weight of PVDF were mixed with 90 parts by weight of NMP to obtain a negative electrode mixture slurry. After applying and drying the slurry on both sides of a 14 μm thick copper foil serving as a current collector,
Pressing was performed to obtain a negative electrode. FIG. 3B is an explanatory diagram of the negative electrode. In the present embodiment, the application area (W
1 × W2) is 267 × 195 mm ² and has a thickness of 14
It is applied to both sides of a μm current collector 105b (see FIG. 2) with a thickness of 95 μm. As a result, the electrode thickness t becomes 204
μm. Further, on the short side of the electrode, a negative electrode current collector 106b to which the negative electrode mixture is not applied is provided.
mm holes are drilled. Further, a single-sided electrode having a thickness of 109 μm was prepared in the same manner except that the coating was performed on one side only. The single-sided electrode is disposed outside in the electrode laminate of item (3) (101c in FIG. 2).

(3) As shown in FIG.
Nine positive electrodes and ten negative electrodes (single-sided electrode 2) obtained in section (2)
Sheet 104) with separator 104a (polypropylene nonwoven fabric: manufactured by Nippon Advanced Paper Industry Co., Ltd., MP1050, basis weight 10).
g / m ² ) and separator 104b (polyethylene microporous membrane; HIPORE6022 manufactured by Asahi Kasei Corporation, weight per unit area 13.
3 g / m ² ) were alternately laminated via a separator 104 bonded thereto, and a separator 104 b was further disposed outside the outer negative electrode 101 c for insulation from a battery container, thereby producing an electrode laminate. The laminated separators 104 were arranged such that the separator 104b was on the positive electrode side and the separator 104a was on the negative electrode side. Note that FIG.
(C) shows the plane of the separator 104. In this embodiment, the dimension (W1 × W2) of the separator 104 is 272.
× 198 mm ² .

(4) As shown in FIG. 1, the bottom container 2 is made by squeezing a 0.5 mm thick SUS304 thin plate to a depth of 5 mm, and the upper lid 1 is also a 0.5 mm thick SUS304 thin plate. Produced. Next, as shown in FIG. 4, a positive electrode terminal 3 made of aluminum and a negative electrode terminal 4 made of copper
mmφ, M3 thread). The positive and negative terminals 3 and 4 were insulated from the upper lid 1 by a polypropylene gasket.

(5) The positive electrode terminal 3 is inserted into the hole of each positive electrode current collector (exposed aluminum foil) 106a of the electrode laminate manufactured in the above item (3), and each negative electrode current collector (exposed copper foil) is inserted. 10
The negative electrode terminal 4 was inserted into the hole 6b and connected with aluminum and copper bolts, respectively. The connected electrode laminate was fixed with an insulating tape, and the corner A of FIG. 1 was laser-welded over the entire circumference. Then, ethylene carbonate, dimethyl carbonate,
Then, a solution in which LiPF ₆ was dissolved at a concentration of 1 mol / l in a solvent in which the mixture was mixed with methyl ethyl carbonate at a volume ratio of 6: 7: 7 was injected. Next, under a reduced pressure of 300 Torr, 1
The injection port 5 was sealed by heat-sealing a sealing film 6 made of an aluminum foil-modified polypropylene laminated film having a thickness of 0.08 mm punched into 2 mmφ at a temperature of 250 to 350 ° C.

(6) The five batteries obtained as described above are charged to 4.2 V with a current of 5 A, and then 4.2 batteries are charged.
Constant current constant voltage charging applying a constant voltage of V for 8 hours,
Subsequently, the battery was charged and discharged three times under the condition that the battery was discharged to 3.2 V at a constant current of 5 A. The third discharge capacity is 26.
It was 1-26.2 Ah. When the thicknesses of these five batteries were measured at five measurement points T1 to T5 shown in FIG.
It was between 6.14 mm and 6.19 mm for all cells. The internal resistance was measured using an alternating current of 1 KHz and found to be 5 mΩ to 6 mΩ.

(Example 2) The positive electrode in this example is the same as the positive electrode described in item (1) of Example 1 except that Li ₁ . ₀₇ M
n ₁ . _{In place of 93} O ₄ , Li ₁ . ₁₀ Mn ₁ . ₈₀₅ A
l ₀ . With ₀₉₅ O _4, a mixture slurry was applied to both sides of 20μm of the current collector 105a with a thickness of 115 .mu.m, except that the electrode thickness t is in the 250 [mu] m, Example 1
It was produced in the same manner as described above. When measured under the same conditions as in Example 1, the residual water content of 10 g of the positive electrode mixture of this electrode was 2
It was 60 ppm.

The negative electrode is a 14 μm current collector 105b.
The negative electrode mixture slurry was applied to both sides of the substrate at a thickness of 85 μm, and the electrode thickness t was 184 μm. Similarly, only one side of the current collector 105b was applied to form a single-sided electrode having a thickness of 99 μm. Was prepared in the same manner as described in the section (2) of Example 1.

The five batteries thus obtained were charged and discharged three times under the same conditions as in Example 1. The third discharge capacity was 24.0 to 24.1 Ah. When the thickness of these batteries was measured in the same manner as in Example 1, it was found to be between 6.15 mm and 6.20 mm for all batteries. The internal resistance was measured using an alternating current of 1 KHz and found to be 5 mΩ to 6 mΩ.

Comparative Example 1 A battery was assembled in the same manner as in Example 1 except that the electrode re-drying temperature before the battery assembly was changed to 150 ° C. in the section (1) of the example 1. The residual water content of 10 g of the positive electrode mixture of this electrode was measured under the same conditions as in Example 1 and was 530 ppm.

The five batteries thus obtained were charged and discharged three times under the same conditions as in Example 1. The third discharge capacity varied greatly from 16.1 to 20.5 Ah. One of them has a thickness of T1 = 7.1 mm,
T2 = 6.9 mm, T3 = 6.7 mm, T4 = 6.7 m
m, T5 = 6.7 mm, which varied greatly at each measurement point, and was 10% or more thicker than the design thickness of 6.00 mm.
Furthermore, the thickness of the other four batteries also varied from 6.6 to 7.3 mm. The internal resistance also varied greatly from 9 mΩ to 15 mΩ.

Comparative Example 2 A battery was assembled in the same manner as in Example 2 except that the electrode re-drying temperature before the battery assembly was changed to 150 ° C. in the item (1) of the embodiment 2. The amount of residual water in 10 g of the positive electrode mixture of this electrode was measured under the same conditions as in Example 1 and found to be 510 ppm.

The five batteries thus obtained were charged and discharged three times under the same conditions as in Example 1. The third discharge capacity varied greatly from 15.0 to 19.1 Ah. One of the batteries has a thickness of T1 = 7.0 mm,
T2 = 6.9 mm, T3 = 6.6 mm, T4 = 6.7 m
m, T5 = 6.6 mm, which varied greatly at each measurement point, and was 10% or more thicker than the design thickness of 6.00 mm.
Furthermore, the thickness of the other four batteries also varied from 6.5 to 7.1 mm. The internal resistance also varied greatly from 8 mΩ to 13 mΩ.

[0054]

As is apparent from the above, according to the present invention, in a flat battery, particularly a flat battery having a large capacity and a high volume energy density, at least manganese oxide is used as an active material for a positive electrode, Active material, conductive material, and the residual water content by the coulometric method of Karl Fischer moisture measurement of the positive electrode mixture composed of the binder is 400 ppm or less, the thickness accuracy is high, the internal resistance, the variation in capacity is small And a non-aqueous secondary battery can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view and a side view of a non-aqueous secondary battery for a power storage system according to an embodiment of the present invention.

FIG. 2 is a side view showing a configuration of an electrode laminate housed inside the battery shown in FIG.

FIG. 3 is an explanatory view of a positive electrode (FIG. 3A), a negative electrode (FIG. 3B), and a separator (FIG. 3C) used in an example of the non-aqueous secondary battery of the present invention. .

FIG. 4 is an explanatory view of an upper lid used in an example of the non-aqueous secondary battery of the present invention.

FIG. 5 is an explanatory diagram of a thickness measurement point of the battery in the embodiment of the non-aqueous secondary battery of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top cover 2 Bottom container 3 Positive electrode terminal 4 Negative terminal 5 Injection port 6 Sealing film 101a Positive electrode (both sides) 101b Negative electrode (both sides) 101c Negative electrode (one side) 104, 104a, 104b Separator 105a Positive electrode collector 105b Negative electrode collector 106a Positive current collector 106b Negative current collector

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shiro Kato 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Kansai New Technology Research Institute Co., Ltd. (72) Inventor Shizukuni Yada, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 4-1-2 1-2 Kansai New Technology Research Institute Co., Ltd. (72) Haruo Kikuta Inventor 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka Gas Co., Ltd. 5H029 AJ12 AJ14 AK03 AL06 AM03 AM04 AM05 AM07 BJ04 BJ15 DJ12 HJ01 HJ02 HJ04 5H050 AA15 AA19 BA17 CA09 CB07 DA02 DA09 EA02 EA09 EA23 FA06 FA12 HA01 HA02 HA04 HA19

Claims (6)

[Claims] 1. A battery comprising a positive electrode, a negative electrode and a non-aqueous electrolyte containing a lithium salt, which is sealed in a battery container and has an energy capacity of 3
A non-aqueous secondary battery having a flat shape of 0 Wh or more and a volume energy density of 180 Wh / l or more, wherein the positive electrode contains at least manganese oxide as an active material, and the active material, the conductive material, A non-aqueous secondary battery characterized in that the residual water content of the positive electrode mixture comprising the adhesive is 400 ppm or less as measured by the coulometric method of the Karl Fischer moisture measurement method. 2. The manganese oxide according to claim 1, wherein the manganese oxide is LiMn in which a part of manganese is replaced with lithium to make lithium excess.
_2. The non-aqueous secondary battery according to claim 1, wherein the secondary battery is ₂ O ₄ . 3. The non-aqueous secondary battery according to claim 1, wherein the manganese oxide is LiMn ₂ O ₄ in which at least a part of manganese is substituted with magnesium or aluminum. 4. The flat battery container according to claim 1, wherein a shape of the wide flat portion of the flat battery container is rectangular.
The non-aqueous secondary battery according to any one of the above. 5. The non-aqueous secondary battery according to claim 1, wherein the flat non-aqueous secondary battery has a thickness of less than 12 mm. 6. The non-aqueous secondary battery according to claim 1, wherein the thickness of the battery container is 0.2 mm or more and 1 mm or less.