JPH09213307A - Nonaqueous electrolyte system secondary cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous system secondary cell of small internal resistance with high energy density. SOLUTION: In a cell provided with a negative electrode 14 with lithium storable and separable, positive electrode 6, nonaqueous system electrolyte containing lithium salt and a vessel, a foaming metal mainly composed of nickel or a fiber-state metal sintered material is charged with a carbon material, capable of storing and separating lithium, together with a binder, to be pressed, the negative electrode 4 is formed, its thickness is set to 0.1mm or more and porosity to 20 to 50%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte type lithium ion secondary battery (hereinafter referred to as a non-aqueous type secondary battery), and particularly to excellent charge / discharge cycle durability, small internal resistance and large current. The present invention relates to a non-aqueous secondary battery that can be charged and discharged.

[0002]

2. Description of the Related Art Batteries using an alkali metal as an active material are attracting attention as high-performance batteries having high energy density. Among them, the lithium battery has a particularly high energy density and is excellent in reliability such as storability, so that it has already been widely used as a power source for small electronic devices as a primary battery. In addition, recently, with the spread of small portable electric devices, the demand for lithium secondary batteries that can be charged and used repeatedly is rapidly increasing.

Further, as a negative electrode material of a lithium secondary battery,
For example, a carbonaceous material in which lithium is occluded in a lithium metal, a lithium alloy, or a carbon material capable of occluding and releasing lithium is used. A non-aqueous secondary battery using lithium metal as the negative electrode can provide a battery with high energy density, but active lithium deposited when the dissolution and deposition of lithium metal is repeated in the charge / discharge cycle serves as a solvent for the electrolytic solution. Due to the reduction, the chargeable / dischargeable lithium is lost to reduce the charge / discharge efficiency of the negative electrode, and there is a risk that lithium dendrites (dendritic crystals) are generated and an internal short circuit occurs.

The positive electrode of the secondary battery is, for example, a positive electrode material,
A slurry in which a conductive material and a binder are mixed with a solvent is applied to the surface of a current collector of a metal foil to form an electrode layer having a thickness of 50 to 100 μm, which is then dried to obtain a positive electrode sheet. There is. For the negative electrode, for example, a slurry in which a solvent is mixed with a negative electrode material and a binder is applied to the surface of a current collector of a metal foil to form an electrode layer having a thickness of 50 to 100 μm, and then this is formed. Is dried to obtain a negative electrode sheet.

Then, a positive electrode sheet and a negative electrode sheet are cut into a desired size, and a separator film is sandwiched between the positive electrode and the negative electrode to form an element, or the positive electrode sheet and the negative electrode sheet are formed. A separator film is sandwiched between a sheet-shaped positive electrode and a negative electrode, which are cut into desired dimensions, and a large number of layers are alternately laminated to form an element. The element is housed in a container and impregnated with an electrolytic solution to form a battery.

In the coin-type non-aqueous secondary battery, the positive electrode is a disk-shaped molded product of a mixture of a positive electrode material, a conductive material and a binder, or a material obtained by molding these materials into a sheet and punching them into a circle. It Further, as the negative electrode, a disk obtained by pressure-molding a mixture of the negative electrode material and a binder, or a mixture obtained by molding the mixture into a sheet and punching it into a circle is used. In a coin-type battery, a separator made of a non-woven fabric is sandwiched between the positive electrode and the negative electrode to form an element, which is housed in a coin-shaped container and impregnated with a non-aqueous electrolyte solution.

[0007]

In the non-aqueous secondary battery,
The thickness of the electrode is usually 0.5 to 5 mm. When making the electrode to this thickness, if a flat collector such as a metal foil is placed on one side of the electrode to form a battery, there is a distance between the electrode and the collector, and Since the electric resistance in the vertical direction, that is, the internal resistance is large and the diffusion distance of lithium ions is long, the utilization factor of the electrode material is remarkably low, and there is a problem that the energy density and the capacity are small accordingly.

Further, since the positive electrode material and the negative electrode material repeatedly expand and contract due to repeated charge and discharge cycles, the contact between the particles of the electrode material in the electrode is cut off to increase the internal resistance, or the electrode to electrode material is increased. There is a problem in that the particles of the particles fall off and an electrode material that is not used for charging and discharging is partially generated, and the capacity of the battery is reduced and the internal resistance is increased.

The present invention solves these problems in the prior art, has a small internal resistance, the electrode material does not fall off from the electrode even after repeated charge and discharge cycles, and the battery capacity decreases and the internal resistance increases. It is an object of the present invention to provide a high energy density non-aqueous secondary battery that does not burn.

[0010]

The non-aqueous secondary battery of the present invention comprises a negative electrode capable of occluding and releasing lithium, a positive electrode capable of occluding and releasing lithium, a non-aqueous electrolyte containing a lithium salt, and And a container for accommodating the negative electrode, wherein the negative electrode is formed by pressing a foamed metal or fibrous metal sintered body containing nickel as a main component, a lithium-storing and desorbing carbon material together with a binder. The thickness is 0.1 mm or more, and the porosity is 20 to 50%.

Examples of carbon materials capable of inserting and extracting lithium include artificial graphite, natural graphite, soil graphite, expansive graphite, scaly graphite and heat-treated materials thereof, as well as carbon materials obtained by thermally decomposing organic substances under various conditions. Can be used. As the carbon material powder, it is preferable to use a powder having a particle diameter (diameter) of 1 to 50 μm. The reason is that the particle size is 1 μm
If it is less than 1, it is bulky and difficult to handle, and the particle size is 50 μm.
This is because the battery capacity tends to decrease if it exceeds the limit.

Of the above carbon materials, mesophase spherical carbon or mesophase short carbon fiber is preferably used. When the mesophase spherical carbon is used, it can be packed at a high density due to its spherical shape, and the capacity per unit volume becomes large. A large battery capacity can be obtained by using mesophase spherical carbon having a particle size of preferably 50 μm or less. When the mesophase short carbon fibers are used, the electrolytic solution is efficiently supplied to the electrode material through the gaps between the short fibers, and the charge / discharge characteristics due to a large current are improved. When the mesophase short carbon fibers having a length of 100 μm or less are preferable, it becomes easy to fill the pores of the current collector.

As carbon materials, char, pitch,
It is preferable to use a thermal decomposition product of a condensed polycyclic hydrocarbon compound such as coke because a high capacity secondary battery can be obtained.

In the negative electrode of the non-aqueous secondary battery of the present invention, a carbon material containing a binder, preferably a binder of a fluorine-containing resin, in a current collector of a foamed metal or a fibrous metal sintered body containing nickel as a main component. Is filled. That is, since the current collector is integrated with the negative electrode material in a three-dimensionally spread state in the negative electrode material, the average distance between the negative electrode material and the current collector is small, and the internal resistance of the negative electrode is small. Therefore, most of the negative electrode materials exhibit their functions, so that a battery with a large capacity can be obtained and can withstand a large current.

For the negative electrode, for example, a binder made of a carbon material and a fluorine-containing resin is mixed with a solvent to prepare a slurry, and the slurry is applied to a foam metal sheet or a mat-like fibrous metal sintered body and then dried. Get Preferably, it is then compressed with a press or the like to adjust the porosity. Further, the fluorine-containing resin and the crosslinking agent are dissolved in an organic solvent such as toluene or xylene,
Powder of a carbon material is mixed with this to form a slurry, which is applied to a foam metal sheet or a mat of a fibrous metal sintered body, and dried at 50 to 100 ° C. to remove the solvent, and
You may compress and harden with a press etc., heating at 0-180 degreeC.

In the negative electrode, since the foamed metal or fibrous metal sintered body and the binder such as the fluorine-containing resin bind the negative electrode material, the carbonaceous material may repeatedly expand and contract due to the charge / discharge cycle. Even if the particles of the carbonaceous material are held in contact with each other, the increase in the internal resistance of the negative electrode is suppressed, and the particles of the carbonaceous material do not fall off from the negative electrode during charge / discharge, and the initial capacity of the battery can be maintained. .

Since the negative electrode can be compressed with a press or the like, preferably at 100 to 1000 kg / cm ^2, to adjust the porosity, the capacity per volume of the negative electrode can be increased. In addition, since an appropriate amount of clearance can be secured in the negative electrode to allow the electrolytic solution to be easily impregnated into the negative electrode, and a route necessary for diffusion of lithium ions is secured, the electrode material can be used even when a large current is applied. Is highly used.

As described above, the thickness and porosity of the negative electrode are adjusted by compressing a foamed metal or fibrous metal sintered body filled with a carbon material containing a binder with a press or the like. 0.1 mm or more, preferably 0.2 mm or more. When the thickness is less than 0.1 mm, the amount of electrode material carried is small and the battery capacity becomes small. If it is too thick, it is difficult to adjust the porosity by compression. in this case,
When pressed while being heated to the melting point of the binder or higher, the strength of the negative electrode is increased and the battery characteristics are significantly improved. Also,
If the porosity is small, impregnation with the electrolytic solution becomes difficult, the ionic conductivity via the electrolytic solution decreases, the function of the negative electrode material is limited, and the battery capacity decreases, so the porosity is 20 to 50.
%, Preferably 25-40%. The porosity is represented by the volume of the void / apparent volume × 100, and the volume of the void is measured by mercury porosimetry.

The foamed metal containing nickel as a main component is preferably a spongy porous body having continuous cells.
In order to make the effect of the present invention that the internal resistance is small, the capacity decrease little even after repeating charge and discharge cycles, and the internal resistance can be prevented from increasing, the foamed metal mainly composed of nickel used for the negative electrode is Opening diameter of unit bubble is 10μ
It is preferably m to 1.0 mm. Open hole diameter is 10 μm
When it is less than 1.0, it becomes difficult to fill the mixture of the carbon material and the binder into the air bubbles, and when it is more than 1.0 mm, the carbonaceous material in which the foamed metal as the current collector and lithium as the negative electrode material are occluded The average distance to the material will increase and the internal resistance of the electrode will increase.

The porosity of the foamed metal containing nickel as a main component is preferably 70 to 98%. When the porosity is less than 70%, the amount of the mixture of the carbon material and the binder that can be filled in the bubbles decreases, and the battery capacity decreases. Further, when the porosity is more than 98%, the strength of the foamed metal becomes small and the force for binding the negative electrode material becomes small.

For the same reason as the case of the open pore diameter of the unit foam of the foam metal, the fiber diameter (diameter) of the sintered fiber metal containing nickel as the main component is preferably 1 to 50 μm. As the fibrous metal sintered body, a sintered body of short fibers or long fibers is used. It is preferable to use a porosity of 50 to 95% for the same reason as in the case of the foamed metal.

The foamed metal or fibrous metal sintered body used for the negative electrode of the present invention is corrosion-resistant to lithium such as nickel-copper alloy and nickel-iron-chromium alloy as long as it has nickel as a main component. Any material with is used. Further, the foamed metal or fibrous metal sintered body of nickel is easily available as a commercial product. The former example is a product name “CELMET” of Sumitomo Electric Industries, Ltd., and the latter example is
The product name of Nippon Seisen Co., Ltd. is "CNP-Ni-MAT".

As the electrolytic solution, a non-aqueous electrolytic solution having a high decomposition voltage is adopted, and the binder for the negative electrode and the positive electrode is not dissolved in the solvent of the electrolytic solution and the non-aqueous secondary battery functions electrochemically. It is preferable to use a stable fluororesin. The fluororesin has excellent heat resistance and chemical resistance, and when the fluororesin is used as a binder, the effect of maintaining contact between particles of the electrode material and the effect of preventing the electrode material from falling off the electrode are stable and high. As the fluorine-containing resin used for the binder, it is preferable to use a resin that is dispersed or soluble in an organic solvent, such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF). In this case, it is preferable to disperse or dissolve the binder in an organic solvent, mix this with an electrode material to form a slurry of the electrode material, and carry the slurry on the current collector. As the fluorine-containing resin, those using a curing agent (crosslinking agent etc.) can also be preferably used.

In the coin-type secondary battery of the present invention, the lid of the container preferably doubles as a negative electrode terminal, and the negative electrode and the inner surface of the lid are electrically connected, preferably by a nickel mesh in a compressed state. Has been done.

Further, in the coin type secondary battery of the present invention,
When the lid of the container also serves as the terminal of the negative electrode, the negative electrode and the inner surface of the lid can be electrically connected by welding. By welding, the electrical connection has a lower resistance,
The force to bind the electrode material is also increased. The welding is preferably electric welding in which electric current is passed for a short time. It is more preferred to use the welding with a nickel mesh in the compressed state.

In the preferred non-aqueous secondary battery of the present invention, the positive electrode is aluminum, titanium, SUS316 or SU.
A foamed metal or fibrous metal sintered body containing S316L as a main component is filled with a binder and a mixture of a positive electrode material capable of inserting and extracting lithium and a conductive material, and the thickness thereof is 0.1 mm. With the above, the porosity is 20 to 50%
Is preferred.

In the positive electrode as described above, as in the case of the negative electrode described above, the positive electrode material and the current collector are integrated in a three-dimensionally spread state in the positive electrode material. The average distance between the current collectors is small, and the internal resistance of the positive electrode is correspondingly small. As a result, all the positive electrode materials will exert their functions, and a battery with a large capacity can be obtained.

The positive electrode material capable of occluding and releasing lithium is, for example, 4, 5, 6, 7, 8, 9, 1 in the periodic table.
Chalcogenides such as oxides, complex oxides, and sulfides mainly containing metals belonging to groups 0, 11, 12, 13 and 14;
And oxyhalides based on the same metals are used. Further, there are conductive polymer materials such as polyaniline, polypyrrole, polythiophene, polyacene, polyparaphenylene, or their derivatives.

Among these, since the operating potential is high and the capacity for occluding and desorbing lithium is large, the energy density of the battery can be increased. Therefore, the chemical formulas are LiCoO ₂ , L
It is preferable to use a spinel type lithium manganese composite oxide represented by iNiO ₂ , LiMnO ₂ or LiMn ₂ O ₄ . Of these, LiMn ₂ O ₄ is a preferable positive electrode material because it is particularly rich in resources and can be manufactured industrially at low cost.

The spinel-type lithium manganese-based composite oxides include LiMn _2-X Fe _X O ₄ (X is 0.4 or less), LiMn _2-Y Zn _Y O ₄ (Y is O.4 or less), L
iMn _{2- XY} Fe _X Zn _Y O ₄ (X is 0.2 to 0.4,
It is preferable that Y is 0.04 to 0.15).

The particle size of the powder of the positive electrode material is 1 to 80 so that the gap between the current collectors can be easily filled, lithium can be smoothly absorbed and desorbed, and can be prevented from becoming too bulky.
It is preferably set to μm.

In the preferred secondary battery of the present invention, not only the positive electrode material as described above, but also the mixture of the positive electrode material and the conductive material is filled in the gap of the current collector together with the binder. Since powder is used for the positive electrode material as described above, by filling the current collector together with a binder as a mixture with a conductive material, the internal resistance of the positive electrode can be reduced, and the positive electrode swells due to charge / discharge cycles, It is possible to prevent the positive electrode material from falling off.

The conductive material is preferably natural graphite, carbon black or highly graphitized artificial graphite having good conductivity.

A mixture of the positive electrode material, the conductive material and the binder is supported on a foamed metal or fibrous metal sintered body which is a current collector. The material used for the current collector of the positive electrode is stable in the potential range in which the positive electrode operates, preferably does not dissolve or dissolve, and is preferably excellent in conductivity, aluminum, titanium, SUS316 or S
The foamed metal or fibrous metal sintered body containing US316L as a main component satisfies these conditions. Also,
These are manufactured industrially. For example, the foam metal of aluminum is Energy Research.
and Generation Inc. Product name of "D
uocel Al Foam ”, and the sintered body of SUS316 is“ Naslon Web ”manufactured by Nippon Seisen Co., Ltd.
Sintered ".

The foam metal is preferably a sponge-like porous material having communicating cells. For the same reason as in the case of the negative electrode, the opening diameter of the unit foam of the foamed metal used for the current collector of the positive electrode is preferably 10 μm to 1.0 mm.

The porosity of the foamed metal is preferably 70 to 98% for the same reason as in the case of the negative electrode.

For the same reason as explained for the negative electrode current collector,
Aluminum, titanium, SUS31 used for positive electrode
The fibrous metal sintered body made of 6 or SUS316L preferably has a fiber diameter of 1 to 50 μm and a porosity of 50 to 95%. Preferred forms of these fibrous metal sintered bodies include a sintered body of short fibers, a cotton-like aggregate of long fibers, and a sintered body of long fibers.

The positive electrode is manufactured, for example, as follows. That is, an organic solvent is added to a mixture of a positive electrode material powder, a conductive material, and a fluororesin that is a binder to form a slurry, and the slurry is applied to a sheet of foam metal or a mat of a fibrous metal sintered body. , Dry to remove organic solvent. Then, preferably by a press or the like
Compress at 1000 kg / cm ² to adjust the thickness and porosity of the positive electrode.

Further, the binder of the fluorine-containing resin and the curing agent (crosslinking agent) may be first dissolved in an organic solvent, and the powder of the positive electrode material and the powder of the conductive material may be added and mixed to form a slurry. When a binder containing a curing agent is used, the organic solvent is removed and the resin polymer is crosslinked when the slurry is applied to the foamed metal or fibrous metal sintered body and then dried and heated.

As the fluorine-containing resin used as the binder and the fluorine-containing resin containing the crosslinking agent, the same resins as those used in the above-mentioned negative electrode can be preferably used.

In the positive electrode, since the foamed metal or fibrous metal sintered body and the binder bind the electrode material together, even if the positive electrode material expands and contracts repeatedly during charge and discharge cycles, the positive electrode material The contact between the particles is maintained, the increase in the internal resistance of the positive electrode is suppressed, and the initial capacity of the battery can be maintained for a long time without the particles of the positive electrode material dropping off from the positive electrode.

Further, since the positive electrode can be compressed by a press or the like to reduce its porosity, the capacity per volume of the positive electrode can be increased. In addition, since an appropriate amount of gap can be secured in the positive electrode to allow the electrolyte solution to be easily impregnated into the positive electrode, and a route necessary for diffusion of lithium ions can be secured, the electrode material can be used even when a large current is applied. Is highly used.

For the same reason as in the case of the negative electrode, the thickness of the positive electrode is 0.1 mm or more, preferably 0.2 mm or more, and more preferably 10 mm or less. The porosity is 20 to 50%, preferably 25 to 40%. Note that, as in the case of the negative electrode, when the material is pressed while being heated to the melting point of the binder or higher, the strength of the positive electrode is increased and the battery characteristics are remarkably improved.

When the non-aqueous secondary battery of the present invention is a coin type, it is preferable that the metal case of the container also serves as a terminal of the positive electrode, and the space between the positive electrode and the inner surface of the case is compressed aluminum. , Titanium, SUS316, or SUS316L through a mesh. By doing so, the contact resistance between the positive electrode and the case that also serves as the positive electrode terminal can be reduced.

If the case of the container also serves as the positive electrode terminal, the positive electrode and the inner surface of the case can be electrically connected by welding. Welding results in a lower resistance electrical connection and also increases the force with which the electrode material is bound. The welding is preferably electric welding in which an electric current is passed for a short time. It is more preferable to use welding together with the metal mesh in a compressed state.

In another preferable mode of the coin-type battery, a disk-shaped positive electrode is provided around the periphery thereof with a metal ring in contact with the positive electrode, and the metal ring is provided on the upper surface and / or the lower surface thereof. A metal mesh that is in electrical contact with is buried.

Since the metal mesh is embedded in the upper surface and / or the lower surface of the positive electrode as described above, the positive electrode material and the positive electrode material are different from those in the case where a flat collector such as a metal foil is arranged on one side of the positive electrode. Good contact with the metal mesh. Further, when the metal mesh is provided on the upper and lower surfaces of the positive electrode, the electric resistance in the thickness direction of the positive electrode, that is, the internal resistance is reduced and the diffusion distance of lithium ions is shortened. As a result, the utilization factor of the positive electrode material is increased, and the energy density and the capacity are increased.

A metal ring is provided around the positive electrode in contact with the positive electrode, and the metal mesh embedded in the positive electrode is in contact with the metal ring. The current flowing through can be efficiently collected by the metal ring.

Since the positive electrode material is further bound by the metal ring in the positive electrode, the contact between the particles of the positive electrode material is maintained even if the positive electrode material repeatedly expands and contracts due to charge and discharge cycles. Therefore, the internal resistance of the positive electrode is prevented from increasing, and the initial capacity of the battery can be maintained for a long time without the particles of the positive electrode material dropping off from the positive electrode.

Materials used for the metal ring and the metal mesh are aluminum, titanium and SUS31.
6 or SUS316L is preferable because it is stable in the potential range in which the positive electrode operates, does not dissolve or elute, and has excellent conductivity.

The organic solvent of the non-aqueous electrolyte of the battery of the present invention includes, for example, cyclic carbonates such as propylene carbonate and ethylene carbonate, linear carbonates such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, γ-butyrolactone, 1,3-dioxolane, sulfolane, dioxolane, 1,3-dioxane, 1,2-dimethoxyethane,
Tetrahydrofuran and 2-methyltetrahydrofuran can be preferably used.

The lithium salt which is the electrolyte used in the battery of the present invention includes, for example, ClO ₄ ⁻ , CF ₃ SO _{4.
^{3 -, BF 4 -, PF}} 6 -, AsF 6 -, SbF 6 -, CF 3 CO
_At least one selected from lithium salts having anions such as ₂ ⁻ , B ₁₀ Cl ₁₀ ²⁻ , (CF ₃ SO ₂ ) ₂ N ^{− and the} like can be preferably used. The non-aqueous electrolytic solution is preferably prepared by dissolving the lithium salt in the organic solvent at a concentration of 0.2 to 2.0 mol / liter. If the concentration is out of this range, the ionic conductivity will decrease and the lithium salt will precipitate.

[0053]

EXAMPLES The present invention will be specifically described below with reference to examples of coin type batteries, but the present invention is not limited to these examples of coin type batteries, and the principle of the present invention is to wind Needless to say, it can be applied to a mold, for example, US Pat. No. 5,370,710, or a laminated mold (JP-A-4-294071).

FIG. 1 and FIG. 2 are vertical sectional views of a coin type non-aqueous secondary battery having a diameter of 24.5 mm and a thickness of 3.0 mm, which was prototyped in the embodiment of the present invention. In FIGS. 1 and 2, 1 is a case of a coin-shaped container that also serves as a positive electrode terminal, and 3 is a lid of a coin-shaped container that also serves as a negative electrode terminal. The case 1 and the lid 3 of the container are caulked and sealed via a gasket 2. A negative electrode 4, a separator 5 and a positive electrode 6 are housed inside the container. The negative electrode 4, the separator 5 and the positive electrode 6 are impregnated with a non-aqueous electrolyte solution. There is a compressed mesh or expanded metal 8 between the positive electrode case 1 and the positive electrode 6, and a compressed mesh or expanded metal 7 between the negative electrode lid 3 and the negative electrode 4, which are electrically connected to each other. Has been done. The metal ring 9 in FIG. 1 is fitted around the sheet of the positive electrode 6.

Example 1 The negative electrode 4 has a thickness of 1.4 mm.
On a sheet of nickel foam metal (porosity 96%, average pore size of unit foam 0.4 mm), fired petroleum coke, which is a heat-treated condensed polycyclic hydrocarbon compound (average particle size: about 15 μm
m, d002 = 0.344 nm, Lc = 5 nm) 47 parts by weight, polyvinylidene fluoride (PVDF) 3 parts by weight and N-methyl-2-pyrrolidone 50 parts by weight are applied as a slurry, and dried by heating at 180 ° C. The formed sheet was punched into a circle having a diameter of 19 mm and pressed with a press to have a thickness of 0.8 mm. In order to completely remove the water content contained in this negative electrode, the pressure was reduced to 180 under a reduced pressure of 0.1 torr.
It was kept at ℃ for 4 hours and dried. The porosity of this negative electrode is 36.
%Met.

The positive electrode 6 is composed of 80 parts by weight of LiMn ₂ O ₄ , 15 parts by weight of natural graphite, polytetrafluoroethylene (PT).
FE) 5 parts by weight of a mixture is formed into a sheet having a thickness of 1.7 mm, which is punched to form a disk having a diameter of 18 mm, and a metal ring 9 made of SUS316L is formed around the disk.
Then, place aluminum expanded metal 8 (hereinafter referred to as EXM) with a thickness of 0.05 mm and a diameter of 8 mm on both sides of the disk, press it with a press to compress it to a thickness of 1.5 mm, and at the same time use EXM as a metal ring. After being electrically connected, in order to completely remove water, the product was dried at 180 ° C. for 4 hours under a reduced pressure of 0.1 torr. The porosity of the obtained positive electrode was 33%. The porosity is Quan
TaChrome's trade name Autoscan-50
0 Durometer was used for measurement. The same applies to the following examples and comparative examples.

Next, using a separator composed of a polypropylene non-woven fabric and a polypropylene microporous film, the electrolyte solution was mixed with a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 1 and a concentration of 1 mol / liter. It was used after dissolving LiPF ₆ so.

Next, the positive electrode 6 was electrically welded to the inner surface of the case 1 together with the aluminum EXM. Further, the negative electrode 4 and the inner surface of the lid 3 are arranged so as to be in contact with each other and electrically connected, and the separator 5 is sandwiched between the positive electrode 6 and the negative electrode 4,
It was housed in a coin-shaped container, and the positive electrode 6, the negative electrode 4 and the separator 5 in the container were impregnated with the above electrolytic solution. In addition, the impregnation of the electrode with the electrolytic solution and the sealing of the container have a dew point of minus 70.
It was carried out in a glove box with an argon atmosphere at 0 ° C. In this way, a coin-type secondary battery as shown in FIG. 1 was produced.

[Embodiment 2] In this embodiment, as the current collector of the negative electrode 4, a nickel fibrous metal sintered body (porosity 91%, fiber diameter 20 μm) having a thickness of 1.4 mm before pressing is used. Other points are the same as in Example 1 except that the produced negative electrode (thickness 0.8 mm, porosity 36%).

[Embodiment 3] In Embodiment 1 described above, the anode 4 and the lid 3 were arranged so as to be in contact with each other and electrically connected. However, in this embodiment, the foamed nickel of the anode 4 is formed. The difference is that the metal is electrically welded to the inner surface of the lid 3, but the other points are the same as in the first embodiment.

[Embodiment 4] In Embodiment 2, the anode 4 and the lid 3 were arranged so as to be in contact with each other and electrically connected, but in this embodiment, the nickel fiber of the anode 4 is in a fibrous shape. The difference is that the metal is electrically welded to the inner surface of the lid 3, but the other points are the same as in the case of the second embodiment.

[Embodiment 5] The negative electrode 4 has a thickness of 1.4 mm.
A sheet of nickel foamed metal (porosity 96%, unit cell open pore size 0.4 mm) was heat-treated with a condensed polycyclic hydrocarbon compound, a petroleum coke calcined product (average particle size: about 15 μm).
m, d ₀₀₂ = 0.344 nm, Lc = 5 nm) 47 parts by weight, 3 parts by weight of PVDF and 50 parts by weight of N-methyl-2-pyrrolidone are applied to the slurry, dried by heating at 180 ° C., and then circular with a diameter of 19 mm. Punched into nickel EX
M (thickness 0.08 mm, diameter 19 mm) was placed on one side and pressed by a press to compress its thickness to 0.8 mm. In order to completely remove water contained in this negative electrode,
It was kept at 180 ° C. for 4 hours under a reduced pressure of 1 torr and dried. The porosity of this negative electrode was 36%.

The positive electrode 6 was manufactured in the same manner as in Example 1.
The same separator and electrolytic solution as in Example 1 were used.

The positive electrode 6 was electrically welded to the inner surface of the case 1 together with the aluminum EXM. The negative electrode 4 was also welded to the inner surface of the lid 3 together with the nickel EXM. Next, the separator 5 was sandwiched between the positive electrode 6 and the negative electrode 4 and housed in a coin-shaped container, and the positive electrode 6, the negative electrode 4 and the separator 5 in the container were impregnated with the electrolytic solution. The impregnation of the electrodes with the electrolytic solution and the sealing of the container were performed in a glove box in an argon atmosphere with a dew point of −70 ° C. In this way, a coin type battery as shown in FIG. 1 was produced.

Example 6 The negative electrode 4 was manufactured in the same manner as in Example 5.

The positive electrode 6 is made of a foam metal made of aluminum (porosity 93%, average pore size of unit foam 0.4 mm, thickness 3.0 mm), 42 parts by weight of LiMn ₂ O ₄ and 5 parts by weight of natural graphite. , PVDF (3 parts by weight), and N-methyl-2-pyrrolidone (50 parts by weight) were mixed, and the resulting slurry was charged and dried by heating at a temperature of 180 ° C. Next, it was punched into a disk with a diameter of 18 mm and pressed to a thickness of 1.5 mm, and at a temperature of 180 ° C. and a pressure of 0.1 tor for removing water.
r dried under reduced pressure for 4 hours. The porosity of the obtained positive electrode is 3
5%.

The same separator and electrolytic solution as in Example 1 were used.

The aluminum foam metal of the positive electrode 6 was electrically welded to the inner surface of the case 1. Also, the negative electrode 4 is made of nickel E
It was electrically welded to the inner surface of the lid 3 together with XM. Next, the separator 5 was sandwiched between the positive electrode 6 and the negative electrode 4 and housed in a coin-shaped container, and the positive electrode 6, the negative electrode 4 and the separator 5 in the container were impregnated with the electrolytic solution. The impregnation of the electrodes with the electrolytic solution and the sealing of the container were performed in a glove box in an argon atmosphere with a dew point of −70 ° C. In this way, a coin-type secondary battery as shown in FIG. 2 was produced.

[Embodiment 7] In this embodiment, SUS316 is used.
Sintered fibrous metal made of L (porosity 91%, fiber diameter 15
μm, thickness 3.0 mm) was used to manufacture the positive electrode 6 with a porosity of 36%, and the other points were implemented except that the SUS316L fibrous metal of the positive electrode 6 was electrically welded to the inner surface of the case 1. A battery was produced in the same manner as in Example 6.

[Example 8] A negative electrode was produced in the same manner as in Example 5.

The positive electrode 5 is a foamed metal made of aluminum having a thickness of 3.0 mm (porosity: 93%, average pore diameter of unit foam: 0.
4 mm), 42 parts by weight of LiMn ₂ O ₄ and 5 parts of natural graphite
The slurry obtained by mixing 50 parts by weight of PVDF, 3 parts by weight of PVDF, and 50 parts by weight of N-methyl-2-pyrrolidone was filled, dried by heating at a temperature of 180 ° C., and then had a diameter of 18 m.
stamped into a disc of aluminum and made of aluminum EXM (thickness: 0.
(05 mm, diameter 18 mm) was placed on one side of the disk and pressed by a press to a thickness of 1.5 mm, and dried at a temperature of 180 ° C. under a reduced pressure of 0.1 torr for 4 hours to remove water. The porosity of the obtained positive electrode was 35%.

The same separator and electrolyte as in Example 1 were used.

The positive electrode 6 was electrically welded to the inner surface of the case 1 together with the aluminum EXM. The negative electrode 4 was also electrically welded to the inner surface of the lid 3 together with the nickel EXM. Next, the separator 5 was sandwiched between the positive electrode 6 and the negative electrode 4 and housed in a coin-shaped container, and the positive electrode 6, the negative electrode 4 and the separator 5 in the container were impregnated with the electrolytic solution. The impregnation of the electrodes with the electrolytic solution and the sealing of the container were performed in a glove box in an argon atmosphere with a dew point of −70 ° C. In this way,
A battery was made.

[Embodiment 9] In this embodiment, SUS316 is used.
Sintered fibrous metal made of L (porosity 91%, fiber diameter 15
(μm, thickness 3.0 mm) and SUS316L EXM (thickness 0.05 mm, diameter 18 mm) are used for porosity 36
% Of the positive electrode 6 and the positive electrode 6 is made of SUS316L EXM
In addition, it is different from the case of Example 8 in that it is electrically welded to the inner surface of the case 1. A battery was produced in the same manner as in Example 8 except for the above points.

Example 10 Graphitized mesophase spherical carbon powder (average particle size of about 20 μm, d ₀₀₂ = 0.33) was used in place of the heat-treated condensed polycyclic hydrocarbon compound of Example 9 above.
A battery was produced in the same manner as in Example 9 except that a negative electrode having a porosity of 37% was produced using 47 parts by weight of (65 nm, Lc = 30 nm).

Example 11 Graphitized mesophase carbon fibrous powder (fiber diameter 8.3 μm, fiber length 60) was used in place of the graphitized mesophase spherical carbon powder of Example 10 above.
μm, d ₀₀₂ = 0.337 nm, Lc = 64 nm) 47
A battery was prepared in the same manner as in Example 10 except that a negative electrode having a porosity of 39% was prepared using parts by weight.

Example 12 LiMn of Example 11 above
LiZn _0.05 Fe _0.35 Mn _1.6 O ₄ 42 instead of ₂ O ₄
A battery was produced in the same manner as in Example 11 except that the parts by weight were used to produce a positive electrode.

[Comparative Example 1] The negative electrode 4 was a calcined product of petroleum coke, which was a heat-treated condensed polycyclic hydrocarbon compound (average particle size 1
5 μm, d ₀₀₂ = 0.344, Lc = 5 nm) 95 parts by weight and 5 parts by weight of (PTFE) were mixed and rolled to form a sheet-like molded product having a thickness of 1.0 mm and a diameter of 19 m.
After punching into a disk of m, the thickness is 0.08 mm,
A nickel EXM having a diameter of 19 mm was placed on one side of a disk and pressed by a press to a thickness of 0.8 mm, and dried for 4 hours under a reduced pressure of 180 ° C. and a pressure of 0.1 torr to remove water. The porosity of this negative electrode was 31%.

The positive electrode 6 was made into a sheet-shaped molded product having a thickness of 1.7 mm by mixing 80 parts by weight of LiMn ₂ O ₄ , 15 parts by weight of natural graphite and 5 parts by weight of PTFE and rolling.
After punching into a disc having a diameter of 18 mm, the thickness is further reduced to 0.
An aluminum EXM with a diameter of 05 mm and a diameter of 18 mm is placed on one side of a disk and pressed by a press to a thickness of 1.5 mm. To remove water, a temperature of 180 ° C. and a pressure of 0.1 torr.
It was dried under reduced pressure of r for 4 hours. The porosity of the obtained positive electrode was 33%.

Further, a polypropylene non-woven fabric and a polypropylene microporous film were used as the separator, and a non-aqueous electrolyte solution containing a mixture of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 1 had an L concentration of 1 mol / liter.
It was prepared by dissolving the iClO _4. The aluminum EXM surface of the positive electrode and the inner surface of the case, and the nickel EXM surface of the negative electrode and the inner surface of the lid were arranged so as to face each other, and were electrically contacted. The injection of the electrolytic solution and the sealing were performed in an argon atmosphere glove box with a dew point of −70 ° C. to manufacture a coin-type secondary battery as shown in FIG.

Comparative Example 2 Graphitized mesophase spherical carbon powder (average particle size of about 20 μm, d ₀₀₂ = 0.336) was used in place of the heat-treated condensed polycyclic hydrocarbon compound of Comparative Example 1 above.
5 nm, Lc = 30 nm) was used to prepare a negative electrode, and otherwise the same as in Comparative Example 1 to prepare a battery.

Comparative Example 3 Graphitized mesophase carbon fibrous powder (fiber diameter 8.3 μm, fiber length 60 μ) was used in place of the graphitized mesophase spherical carbon powder of Comparative Example 2 above.
m, d ₀₀₂ = 0.337 nm, Lc = 64 nm) was used to prepare a negative electrode, and otherwise the same as in Comparative Example 2 to prepare a battery.

The produced Examples 1 to 12 and Comparative Examples 1 to 1
As an evaluation of the discharge characteristics of the battery of No. 3, 0.5 mA after charging for 100 hours at the maximum current of 1 mA until the voltage of 4.2 V was reached.
Was discharged at a constant current of 2.5 V to measure its capacity. Next, as an evaluation of the large current discharge characteristics, after charging for 100 hours with a maximum current of 1 mA until the voltage reaches 4.2 V, 5 mA
Was discharged at a constant current of 2.5 V to measure its capacity. In addition, as an evaluation of charge / discharge cycle characteristics, 4.2
Charge up to a voltage of V for 50 hours with a maximum current of 2 mA,
The cycle of discharging at a constant current of 1 mA to 3.0 V was repeated 20 times, and the ratio of the capacity at the 20th cycle to the initial discharge capacity was measured. The results are shown in Table 1.

[0084]

[Table 1]

[0085]

As is clear from the results of these Examples and Comparative Examples, the coin-type non-aqueous electrolyte secondary battery to which the present invention is applied has improved large current discharge characteristics and can realize high energy density. The charge / discharge cycle durability is remarkably excellent.

[Brief description of drawings]

FIG. 1 is a sectional view of a battery used in Examples 1-5 of the present invention.

FIG. 2 is a cross-sectional view of batteries used in Examples 6-12 of the present invention and a comparative example.

[Explanation of symbols]

 1: Positive electrode case 2: Gasket 3: Negative electrode lid 4: Negative electrode 5: Separator 6: Positive electrode 7: Mesh 8: Mesh 9: Metal ring

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01M 4/80 H01M 4/80 C 10/40 10/40 Z (72) Inventor Go Morimoto Kanagawa Yokohama, Kanagawa Asahi Glass Co., Ltd. Central Research Laboratory, 1150, Hazawa-machi, Tokyo (72) Inventor Shinji Matsumoto 2-2-1 Tsujido Shinmachi, Fujisawa-shi, Kanagawa Elner Co., Ltd.

Claims (11)

[Claims] 1. A negative electrode capable of occluding and releasing lithium, a positive electrode capable of occluding and releasing lithium, a non-aqueous electrolyte containing a lithium salt, and a container accommodating these, the negative electrode containing nickel. A foamed metal or fibrous metal sintered body as a main component is filled with a carbon material capable of absorbing and desorbing lithium together with a binder and pressed, and the thickness thereof is 0.1 mm or more and the porosity is 20. A non-aqueous electrolyte-based secondary battery characterized by being -50%. 2. The battery according to claim 1, wherein the carbon material is mesophase spherical carbon or mesophase short carbon fiber. 3. The battery according to claim 1, wherein the carbon material is a thermal decomposition product of a condensed polycyclic hydrocarbon compound. 4. The lid of the container also serves as a terminal of the negative electrode, and the negative electrode and the inner surface of the lid are electrically connected via a nickel mesh in a compressed state.
~ The battery according to any one of 3 to 3. 5. The battery according to claim 1, wherein the lid of the container also serves as a terminal of the negative electrode, and the negative electrode and the inner surface of the lid are electrically connected by welding. . 6. The positive electrode is formed by filling a foamed metal or fibrous metal sintered body with a mixture of a positive electrode material capable of inserting and extracting lithium and a conductive material together with a binder,
The battery according to claim 1, which has a thickness of 0.1 mm or more and a porosity of 20 to 50%. 7. The foamed metal or fibrous metal sintered body,
Aluminum, titanium, SUS316 or SUS3
The battery according to claim 6, which is composed of 16 L. 8. The positive electrode is provided with a metal ring made of aluminum, titanium, SUS316, or SUS316L around the positive electrode, and the upper surface and / or the lower surface of the metal ring are in electrical contact with the metal ring. 6. The battery according to claim 1, wherein a metal mesh made of titanium, titanium, SUS316, or SUS316L is embedded, and the positive electrode has a thickness of 0.1 mm or more and a porosity of 20 to 50%. 9. The case of the container also serves as a terminal of the positive electrode, and aluminum, titanium, SUS316 or SUS in a compressed state is provided between the positive electrode and the inner surface of the case.
The battery according to claim 6 or 7, which is electrically connected through a metal mesh made of 316L. 10. The battery according to claim 6, wherein the case of the container also serves as a terminal of the positive electrode, and the positive electrode and the inner surface of the case are electrically connected by welding. . 11. The positive electrode material is LiMn ₂ O ₄ or L.
iMn _2-XY Fe _X Zn _Y O ₄ (X is 0.2 to 0.4,
Y is 0.04 to 0.15).
The battery according to any one of 1.