JPH0770327B2 - Secondary battery - Google Patents

Description

The present invention relates to a novel secondary battery, and further to a small and lightweight secondary battery.

[Prior Art] In recent years, electronic devices have been remarkably reduced in size and weight, and accordingly, there has been a great demand for reduction in size and weight of batteries serving as power sources. In the field of primary batteries, small and lightweight batteries such as lithium batteries have already been put into practical use, but since they are primary batteries, they cannot be repeatedly used, and their fields of use have been limited. On the other hand, lead batteries and nickel-cadmium batteries have been conventionally used in the field of secondary batteries, but both have serious problems in terms of size reduction and weight reduction.
From this point of view, non-aqueous secondary batteries have received a great deal of attention, but have not yet been put into practical use. One of the reasons is that the electrode active material used in the secondary batteries has cycleability, self-discharge characteristics, etc. The point is that nothing satisfying the practical physical properties has been found.

Meanwhile, a new group of electrode active materials utilizing intercalation of a layered compound or a doping phenomenon, which is a reaction mode which is essentially different from that of conventional nickel-cadmium batteries, lead batteries and the like, has been attracting attention.

Such a new electrode active material does not cause a complicated chemical reaction in the electrochemical reaction during charging and discharging, and therefore is expected to have an extremely excellent charge / discharge cycle property.

For example, as an example utilizing intercalation of a layered compound, a chalcogenite compound having a layered structure has attracted attention. For example, although chalcogenite compounds such as Li _X TiS ₂ and Li _X MoS ₃ have relatively excellent cycle characteristics, practical electromotive voltage is at most even when the electromotive force is low and Li metal is used for the negative electrode. It was around 2V and was not satisfactory in terms of high electromotive force, which is one of the features of non-aqueous batteries. On the other hand, Li _X V ₂ O ₅ and Li _X having the same layered structure
Metal oxide compounds such as V ₆ O ₁₃ , Li _X CoO ₂ , and Li _X NiO ₂ are attracting attention because they have the feature of high electromotive force. However, these metal oxide compounds are inferior in terms of cycleability, utilization factor, that is, the ratio that can be actually used for charging and discharging, and further, overvoltage during charging and discharging, and they have not yet been put to practical use.

In particular, Li _X CoO ₂ , L disclosed in JP-A-55-136131
The secondary battery positive electrode such as i _X NiO ₂ has an electromotive force of 4 V or more when Li metal is used as the negative electrode, and the theoretical energy density (per positive electrode active material) is 1,100 WHr / kg, which is an amazing value. However, the ratio that can actually be used for charge and discharge is low, and only an energy density far from the theoretical value can be obtained.

On the other hand, as an example of an electrode active material having a doping phenomenon separated from the bed, for example, a new type secondary battery using a conductive polymer as an electrode material is described in, for example, JP-A-56-136469. However, the secondary battery using such a conductive polymer has not yet been put to practical use because of problems such as instability, that is, low cycleability and large self-discharge.

Further, JP-A-58-35881, JP-A-59-173979, JP-A-59-2
JP 07568 proposes to use a high surface area carbon material such as activated carbon as an electrode material. Such an electrode material has been found to have a peculiar phenomenon which is considered to be due to the formation of an electric double layer based on its high surface area, which is different from the doping phenomenon, and is said to exhibit excellent performance particularly when used for a positive electrode. Although it is described that it is also used for a negative electrode in part, when such a high surface area carbon material is used as a negative electrode, it has a big defect in cycle characteristics and self-discharge characteristics, and the utilization rate is also high. That is, the ratio of electrons (or counter cations) that can reversibly enter and exit per carbon atom is extremely low, 0.05 or less, usually 0.01 to 0.02, which is the weight when used as a negative electrode of a secondary battery. In addition, it means that both the volume and the volume become extremely large, which has a big drawback in practical use.

Further, JP-A-58-209864 describes that a carbonaceous material, which is a carbide of a phenolic fiber and has a hydrogen atom / carbon atom ratio of 0.33 to 0.15, is used as an electrode material. It is said that it exhibits excellent properties when it is mainly p-doped with anions and used as a positive electrode material, and at the same time, it is described that it can be n-doped with cations and used as a negative electrode material. However, when such an n-doped material is used as a negative electrode, such a material also has a large defect in the cycle property and the self-discharge characteristic, and the utilization rate is extremely low, which is a large defect in practical use.

Also, graphite intercalation compounds have long been used as secondary battery electrode materials.
It is known that it can be used, in particular Br , ClO_Four , B
F_Four Graphite intercalation compound incorporating anions such as ions
Is known to be used as a positive electrode. On the other hand Li ion
Graphite intercalation compound incorporating cations such as
It is naturally conceivable to use it, and in fact, for example, JP-A-59-14.
3280 discloses a graphite intercalation compound incorporating cations.
It is described to be used as a negative electrode.

However, graphite intercalation compounds incorporating such cations are extremely unstable, and in particular, they have extremely high reactivity with electrolytes.
"Journal of Electrochemical Society, vol.11
7, No2, P.222-224 1970 '',
When graphite which can form an intercalation compound or graphite is used as the negative electrode, the stability as a battery such as self-discharge is lacked, and the above-mentioned utilization rate is extremely low and it cannot be put to practical use.

As a method for solving such a problem, Japanese Patent Application Laid-Open No. 61-
In 103785, a complex oxide having a specific composition and a carbonaceous material having a special structure were proposed as active materials for secondary batteries.
The electrode for a non-aqueous secondary battery made of the active material for a battery has a charge / discharge efficiency, a utilization ratio, that is, a ratio that can be used for actual charge / discharge, a cycle characteristic, and a self-discharge characteristic, as compared with a conventional electrode. It became clear that it had a very good basic performance. On the other hand, however, it has been found that the performance of the electrode made of the active material for a battery is significantly affected by the coating film forming method of the electrode, and it is not always easy to develop the basic performance. That is, while an electrode with excellent reproducibility was provided on a metal foil in a small area during film formation, the performance of an electrode coated on a metal foil with a large area using a coating machine remarkably varies. Met.

It is presumed that such a cause is caused by the peeling of the active material from the metal foil of the electrode current collector, which occurs during the winding process during coating, and the accompanying decrease in the current collecting performance.

These facts indicate that 1) the electrode performance is not stable, 2) the long-term performance of the battery using the electrode is unreliable, 3)
When a cylindrical battery is assembled using the electrode, it suggests that troubles such as peeling of the active material may occur in the winding process, and an electrode having a large area and excellent performance is manufactured. Has concluded that it is extremely important to solve these problems.

[Problems to be Solved by the Invention] As described above, in the mounted battery in which the active material is incorporated as the active material of the electrode, the current collecting performance of the current collector is dramatically improved, and the excellent basic property of the active material is obtained. How to bring out the characteristics is a very important issue.

[Means and Actions for Solving Problems] The present invention solves the above problems and provides a small-sized and lightweight secondary battery having excellent battery performance, particularly excellent cycle performance and self-discharge characteristics, high performance and high energy density. It was made to do.

According to the present invention, there is provided a secondary battery comprising at least positive and negative electrode active materials, a current collector, a separator and a non-aqueous electrolyte as constituent elements, wherein the positive electrode active material of the composite oxide is on an aluminum current collector. In addition, the negative electrode active material of carbonaceous material is formed by coating on a copper current collector, and the current collector has continuous holes with an average hole diameter of 1.5 mm or less, and an opening ratio of 5% or more Saga 500
Provided is a secondary battery, which is a metal current collector having a size of μm or less.

The positive electrode active material of the present invention is, for example, Li _(1-x) MnO ₂ , Li _(1-x) Co
_{O 2, Cu 2 V 2 O} 5, a-V 2 O 5 -P 2 O 5, Li (1-x) is a composite oxide of _2, such as NiO, the effect of the present invention is particularly exhibited in The complex oxides disclosed by the present inventors in Japanese Patent Application No. 61-103785 are listed below.

I: has a layered structure and has the general formula A _x M _y N _z O ₂ (wherein A is at least one selected from alkali metals, M is a transition metal, and N is a group of Al, In, Sn). Represents at least one selected, and x, y, z are each 0.05 ≦ x
Represents the numbers ≤1.10, 0.85 ≤ y ≤ 1.00, 0.001 ≤ z ≤ 0.10. ) Is a complex oxide.

Such a layered composite metal oxide has the general formula A_xM_yN_zO₂Indicated by
Where A is at least one selected from alkali metals
Also, it is one kind, for example, Li, Na, K, and Li is particularly preferable.
The value of x varies depending on the charged state and the discharged state, and the range is
0.05 ≦ x ≦ 1.10. That is, A by charging Aeon de
Intercalation occurs and the value of x becomes small.
Therefore, the value of x reaches 0.05 in the fully charged state.
Also, due to discharge, A Ion intercalation occurs
The value of x becomes large, and x becomes x in the fully discharged state.
Reaches a value of 1.10.

Further, M represents a transition metal, and Ni and Co are preferable among them.
The value of y does not change due to charging and discharging, but 0.85 ≦ y ≦ 1.
The range is 00. When the value of y is less than 0.85 or exceeds 1.00, sufficient performance as an active material for a secondary battery, that is, a phenomenon such as a decrease in cycleability and an increase in overvoltage occurs, which is not preferable.

N is at least one selected from the group consisting of Al, In and Sn,
Of these, Sn is preferable. In such a novel active material for a secondary battery, the function of N is extremely important and exhibits an excellent cycle property, particularly in deep charging and deep discharging cycles. The value of z does not change due to charging and discharging, but is in the range of 0.001 ≦ z ≦ 0.10, preferably 0.0
The range is 05 ≦ z ≦ 0.075. When the value of z is less than 0.001, the effect of N is not sufficiently exerted, the cycleability in deep charging and deep discharging described above is low, and the overvoltage during deep charging remarkably increases, which is not preferable. Also, if the value of z is
When it exceeds 0.10, the hygroscopicity becomes too strong, the handling becomes difficult, and the basic characteristics as an active material for a secondary battery are impaired, which is not preferable.

To produce such a composite oxide for a secondary battery active material, A,
M, N metal oxides, hydroxides, carbonates, nitrates,
It is obtained by mixing an organic acid salt and the like, and then firing in a temperature range of 600 ° C to 950 ° C, preferably 700 ° C to 900 ° C in air or in an oxygen atmosphere.

A firing time of about 5 to 48 hours is usually sufficient. A _x M _y N _z O ₂ obtained by such a method, the discharge state of the secondary battery positive electrode, i.e. the value of x is obtained in the range of usually 0.90 to 1.10.

Thus A _x M _y N _z O ₂ resulting charged as described above, de-intercalation reaction by the discharge, and the intercalation reaction, the value of x varies the range of 0.05 ≦ x ≦ 1.10.

If the reaction is represented by a formula, It is represented by. (Here, x'represents the value of x before charging and x "represents the value of x after charging.) It is a value defined by.

Such a non-aqueous secondary battery active material is characterized in that the utilization rate is large, that is, it has an extremely stable cycle property with respect to deep charging and discharging.

The composite oxide for a secondary battery active material has a very noble potential of 3.9 to 4.5 V with respect to the Li standard potential, and particularly has excellent performance when used as a positive electrode of a non-aqueous secondary battery. Demonstrate.

Examples of the negative electrode active material of the present invention include polyacetylene and poly-
Conductive polymer negative electrodes such as p-phenylene, vapor grown carbon fibers, carbonaceous materials such as pitch-based carbon and polyacrylonitrile-based carbon fibers, and carbonaceous materials disclosed in Japanese Patent Application No. 61-103785. Listed below are II.

II: BET specific surface area A (m ² / g) in the range of 0.1 <A <100,
And the crystal thickness Lc (Å) and the true density ρ (g /
The value of cm ³ ) is 1.70 <ρ <2.18 and 10 <Lc <120ρ under the following conditions.
An n-doped body of a carbonaceous material in a range satisfying −189.

The carbonaceous material used in the present invention must have a BET specific surface area A (m ² / g) described below of more than 0.1 and less than 100. Preferably more than 0.1 and less than 50, more preferably
The range is greater than 0.1 and less than 25.

If it is 0.1 m ² / g or less, the surface area is too small and a smooth electrochemical reaction on the electrode surface is difficult to proceed, which is not preferable. Further, when the specific surface area is 100 m ² / g or more, the characteristics are deteriorated in terms of cycle life characteristics, self-discharge characteristics, and current efficiency characteristics, which is not preferable. It is presumed that such a phenomenon causes a variety of side reactions on the electrode surface because the surface area is too large and adversely affects the battery performance.

In addition, the values of the crystal thickness Lc (Å) and the true density ρ (g / cm ³ ) in the X-ray diffraction described below are the following conditions: 1.70 <ρ <2.18 and 1
It must be in the range 0 <Lc <120ρ-189. Preferably 1.80 <ρ <2.16 and 15 <Lc <120ρ−196 and Lc> 12
0ρ−227, more preferably 1.96 <ρ <2.16 and 15
The range is <Lc <120ρ−196 and Lc> 120ρ−227.

When the n-doped body of the carbonaceous material is used as a stable electrode active material, the crystal thickness Lc (Å) in the above X-ray diffraction is used.
And the value of true density ρ (g / cm ³ ) is extremely important.

That is, when the value of ρ is 1.70 or less or the value of Lc is 10 or less,
This means that the carbonaceous material is not sufficiently carbonized, that is, the crystal growth of carbon has not progressed, and that there are a large number of amorphous portions. Therefore, the carbonaceous material in this range inevitably has a large surface area in the carbonization process, and deviates from the value of the BET specific surface area in the above range. Such an n-doped body of a carbonaceous material is extremely unstable, has a low doping amount, cannot substantially stably exist as an n-doped body, and cannot be used as a battery active material.

On the other hand, when the value of ρ is 2.18 or more or the value of Lc is 120ρ-189 or more, carbonization of the carbonaceous material proceeds too much, that is, graphite with advanced crystallization of carbon, having a structure similar to graphite. Means that

As parameters showing the structure of such a carbonaceous material, the true density ρ (g / cm ³ ), the crystal thickness Lc, which are limited in the present invention,
In addition to (Å) and BET specific surface area A (m ² / g), for example, the interlayer surface spacing d ₀₀₂ (Å) in X-ray diffraction can be mentioned. The value of the interplanar spacing d ₀₀₂ (Å) becomes smaller as the crystallization progresses, and is not particularly limited, but a carbonaceous material having a value of less than 3.43 Å, and further less than 3.46 Å deviates from the range defined above. To do.

On the other hand, the intensity ratio R (I 13
60cm ^-1 / I 1580cm ^-1) values are also of a parameter showing the structure of the carbonaceous material, such intensity ratio R decreases with the progress of crystallization, in particular but not limited but less than 0.6 or 2.5
Carbonaceous materials having a value in the above range, or even less than 0.7 or in the range of 2.5 or more depart from the range limited by the present invention.

As mentioned above, graphite has a regular layered structure.
The carbon material of this structure has various ions.
Forming an intercalation compound, especially ClO_Four , BF
_Four P-type intercalation compounds with anions such as
However, attempts to use it as a positive electrode for a secondary battery have long been known.
Has been done. For such purpose, it is easy to form an intercalation compound
That is an essential condition, for example, JP-A-60-36315.
The Raman intensity ratio R (I 1360 cm^-1/ I 1
580 cm^-1) Is as small as possible, that is, the value of ρ and Lc
It was essential that the value of was as large as possible.

From another point of view, the present inventors consider that carbonaceous materials are not anions.
Ku Li Various studies on incorporating cations such as ions
In the process of doing, I found a surprising fact. That is, Li Io
When incorporating positive ions such as ions, the value of ρ is 2.18 or more.
Above, or carbonaceous material having Lc value of 120ρ-189 or more
If a material is used, as described above, graphite
Motion, the cycle life characteristics and self-discharge characteristics are poor,
Furthermore, the utilization rate is extremely low, and in extreme cases, as a secondary battery
It may not work substantially, which is not preferable.

The carbonaceous material satisfying such conditions can be obtained, for example, by thermal decomposition of various organic compounds or carbonization by firing. In this case, the heat history temperature condition is important, and as described above, when the heat history temperature is too low, the carbonization is not sufficient, the electric conductivity is small, and the carbonaceous material does not meet the conditions. The lower limit of temperature varies slightly depending on the object, but is usually 600
℃ or more, preferably 800 ℃ or more. What is more important is the thermal history temperature upper limit, and heat treatment at temperatures close to 3,000 ° C., which is used in ordinary graphite, graphite and carbon fiber production, causes crystal growth to proceed too much, and the function as a secondary battery is remarkably high. Be damaged. 2,400 ℃ or less, preferably 1,800
C. or lower, more preferably 1,400.degree. C. or lower is a preferable range. Under such heat treatment conditions, the heating rate, the cooling rate, the heat treatment time, etc. can be arbitrarily selected according to the purpose. Further, a method of performing heat treatment in a relatively low temperature region and then raising the temperature to a predetermined temperature is also adopted.

An example of the carbonaceous material satisfying the condition range is, for example, vapor grown carbon fiber. The vapor grown carbon fiber can be obtained, for example, by gas phase pyrolysis of a carbon source compound such as benzene, methane, or carbon monoxide in the presence of a transition metal catalyst (for example, 600 as described in JP-A-59-207823). ℃ ~ 150
A carbon material that can be obtained at most (at a temperature of 0 ° C.), and refers to all that is obtained by a known method similar to the above, in which fibers are placed on a substrate (for example, ceramics, a graphite substrate, carbon fiber, carbon black, Ceramic particles, etc.), a method of generating it in a gas phase, etc. are known. Usually obtained by such a method as fibrous, that is, carbon fiber,
In the present invention, it may be used as a fibrous form as it is, but may be used as a pulverized powder form.

Such vapor grown carbon fiber is a typical example of graphitizable carbon.
This is a known fact. That is, it is extremely easy by heat treatment
It has the characteristic of graphitizing into graphite. Communication
This heat treatment is usually performed at a temperature of 2400 ° C or higher. Write
The graphitized vapor grown carbon fiber obtained by
Various characteristics have already been reported as a well-organized graphite material.
For example, Endo et al. "Synthetic Metals (Synt
hetic Metals) vol.7, P.203, 1983 ”.
It is extremely easy to form intercalation compounds with anions such as
Furthermore, an intercalation compound with such an anion is used as a positive electrode and a negative electrode.
It is known that it can be used as a pole to make a temperature difference battery.
It However, such a battery system usually has an extremely high electromotive force.
It was too low for practical use.

On the other hand, as mentioned above, graphite and graphite are regular layers.
It has a structure, and carbon materials with such a structure have various types of
Forming intercalation compounds with benzene as guest, especially ClO
_Four , BF_Four Intercalation compounds with anions such as
It has long been attempted to use it as a positive electrode for secondary batteries.
Has been done. For such purpose, easy formation of intercalation compounds
It is an essential condition that, for example, JP-A-60-36315
Graphite that has been heat-treated near 3000 ℃ as described in the report, Graph
The eight structure was a prerequisite. The present inventors filed a Japanese patent application Sho 61
As disclosed in −103785, carbonaceous materials have Such as ionic
When incorporating cations, the carbonaceous material will
History has been shown to have better properties
It

That is, the vapor-grown carbon fiber used in the present invention preferably has a maximum thermal history temperature of 2400 ° C. or lower, including the manufacturing process, preferably 2000 ° C. or lower, and particularly 1400 ° C. or lower.
When the temperature exceeds 2400 ° C, the characteristics of the n-doped body are adversely affected, which is not preferable.

Another example is a pitch-based carbonaceous material. Examples of pitches used in the present invention include petroleum pitch, asphalt pitch, coal tar pitch, crude oil cracking pitch, petroleum sludge pitch, etc., pitch obtained by thermal decomposition of coal, thermal decomposition of high-molecular polymer And the pitch obtained by thermal decomposition of an organic low molecular weight compound such as tetrabenzophenazine.

Thermal history temperature conditions are important for obtaining pitch-based calcined carbides that satisfy such conditions. As described above, thermal history at a high temperature gives calcined carbides that are excessively crystallized, and the characteristics of the n-doped body are remarkably high. Getting worse. The heat history temperature condition is 2,
The preferred range is 400 ° C or lower, preferably 1,800 ° C or lower, and more preferably 1,400 ° C or lower.

The lower limit of the temperature is preferably at least 600 ° C., more preferably at least 800 ° C., at which the characteristics such as electric conductivity of the calcined carbide start to appear.

Needle coke etc. are mentioned if a specific example of such a pitch-type calcined carbide is shown.

Further exemplifying such a carbonaceous material is a calcined carbide of a polymer containing acrylonitrile as a main component.

The thermal history temperature condition is important for obtaining a calcined carbide of a polymer containing acrylonitrile as a main component that satisfies the above-mentioned conditions, and as described above, the thermal history at a high temperature gives a calcined carbide in which the crystal grows too much. , The characteristics of the n-doped body are significantly deteriorated. The heat history temperature condition is 2,400 ° C or lower, preferably 1,800 ° C or lower, and more preferably 1,400 ° C or lower.

The lower limit of the temperature is preferably at least 600 ° C., more preferably at least 800 ° C., at which the characteristics such as electric conductivity of the calcined carbide start to appear.

Such carbonaceous materials are different from ordinary graphite and graphite
However, it has a layered structure that can form an intercalation compound.
What is not done is X-ray analysis, Raman analysis, true density measurement
It should be clear from the results such as. In fact, the condition range of the present invention
Carbonaceous materials are graphite, graphite and very intercalation compounds
ClO that easily forms_Four , BF_Four , Br Anions such as
The fact that it ’s not or very hard to capture
is there.

More specifically, the anion uptake amount, that is, the p-doping amount is less than 0.005 in the 0.6M-LiClO ₄ -propylene carbonate electrolyte system, and further less than 0.002, on the contrary, shows excellent performance as a negative electrode. Demonstrate.

Further, as in the example of the above-mentioned Japanese Patent Laid-Open No. 58-35881, electric double layer formation on the surface found in high surface area carbon materials such as activated carbon, that is, unlike a kind of capacitor-like behavior, in this case surface area and battery performance Has no correlation, and conversely, if the surface area is large, it will have a negative effect on performance such as current efficiency and self-discharge.

This fact is different from the phenomenon found in conventionally known carbon materials, and when used as a secondary battery active material, the following characteristics are exhibited. At least 10 cycle life characteristics
It has cycle life characteristics of 0 times or more, 300 times or more, and even 500 times or more. In addition, the current efficiency in charging and discharging is at least 90% or more, depending on the thing, 95% or more,
Reach over%. The self-discharge rate is at least 30% / month or less, 20% / month or less, and even 10% / month or less. Furthermore, one of the characteristics of the carbonaceous material that satisfies such conditions is that the utilization rate is very high.

The above-mentioned utilization rate means the ratio of electrons (or counter cations) that can reversibly enter and exit per carbon atom, and is defined by the following formula.

Here, w represents the weight (g unit) of the carbonaceous material used.

The utilization rate reaches at least 0.08, and even 0.15 or more, and it is possible to store a large amount of electricity with a small weight and volume.

The n-doped body of the carbonaceous material exhibits excellent performance when used as a secondary battery active material, and particularly excellent performance when used as a negative electrode active material.

As a particularly preferred combination of the above active materials, active material I:
A combination of using A _x M _y N _z O ₂ as a positive electrode and active material II as a negative electrode is most preferable.

As described above, for example, the performance of the electrode obtained by continuously coating the electrode active material using a coating machine and forming a film has a remarkable variation due to local peeling. The facts are that 1) the electrode performance is not stable, and 2) the long-term performance of a battery using the electrode is unreliable. Especially vulnerable to shock such as vibration. 3) When a cylindrical battery is assembled, it is suggested that troubles such as peeling of the active material occur in the winding process, and it is extremely important to solve such a problem.

The present inventors have, as a current collector, a continuous hole having an average hole diameter of 1.5 mm or less, an opening ratio of 5% or more, and a thickness of 500 μm.
It has been found that the use of the following metal current collector significantly improves the deterioration of the electrode performance due to the above-described peeling and allows the characteristics of the active material to be exhibited without being impaired.

In the present invention, the average hole diameter means a value obtained by dividing the arithmetic mean of the maximum diameters of holes per cm ^{2 by} the arithmetic mean of the minimum diameters, and it must be 1.5 mm or less. Average hole diameter is 1.5 mm
If it is larger, it becomes difficult to collect current smoothly from the active material in the center of the hole in the electrode composed of such a current collector, and the center of the hole easily comes off, which creates a new problem in mechanical strength. Occurs. The opening ratio in the present invention means a value obtained by multiplying the total cross-sectional area of holes per 1 cm ² by 100%, and must be 5% or more. When the aperture ratio is less than 5%, no significant improvement in peel strength of the film-forming electrode is observed, and no significant improvement in performance is exhibited even in the charge / discharge characteristics of such electrode. In the present invention, the thickness of the current collector should be 500 μ or less. When the thickness is more than 500 μ, the apparent volume of the current collector itself becomes remarkably large, which is not preferable as the current collector of the small and lightweight secondary battery intended by the present invention. The metal current collector in the present invention refers to a positive electrode made of aluminum and a negative electrode made of copper foil, a net, an expanded metal or a punching metal, but is not particularly limited thereto.

Next, a secondary battery using the above active material and the current collector will be described.

Although non-aqueous batteries have been excellent in performance such as high energy density, small size and light weight, they have drawbacks in output characteristics as compared with aqueous batteries and have not been widely used in the past. In particular, in the field of secondary batteries where output characteristics are required, this defect is one of the factors hindering practical use.

Causes non-aqueous battery is inferior in output characteristics is high if the ion conductivity of the aqueous electrolyte solution, usually while having 10 ^-1 Ω ^-1 cm ^-1 order values, in the case of the non-aqueous usually ^10-2 to ^{- This} is due to its low ionic conductivity of ⁴ Ω ^-1 cm ^-1 .

As one method for solving such a problem, increasing the electrode area, that is, using a thin film or a large area electrode is considered.

A method of forming an electrode active material using an organic polymer dissolved and / or dispersed in a solvent as a binder is a particularly preferable method for obtaining such a thin film and a large area electrode.

As described above, stable performance is obtained only by using a metal current collector having a hole with an average hole diameter of 1.5 mm or less and having an average hole diameter of 1.5 mm or less and an opening ratio of 5% or more and a thickness of 500 μm or less. It became possible to obtain electrodes. In addition, the characteristics of the cylindrical battery, which has been markedly deteriorated by peeling in the past, were also remarkably improved by using the electrode on at least one side.

When using such an organic polymer as a binder, a method of using as a coating solution a dispersion of an electrode active material in a binder solution prepared by dissolving the organic polymer in a solvent, or water-emulsion dispersion of the organic polymer An example is a method of using a liquid in which an electrode active material is dispersed as a coating liquid. The amount of binder used is not particularly limited, but is usually 0.1 to 100 parts by weight of the electrode active material.
20 parts by weight, preferably 0.5 to 10 parts by weight.

The organic polymer used here is not particularly limited, but when the organic polymer has a relative permittivity of 4.5 or more at 25 ° C. and a frequency of 1 kHz, particularly preferable results are obtained, and particularly as battery performance. It has excellent characteristics in terms of cycleability and overvoltage.

Examples of organic polymers satisfying such conditions include polymers or copolymers of acrylonitrile, methacrylonitrile, vinyl fluoride, vinylidene fluoride, chloroprene, vinylidene chloride, nitrocellulose, cyanoethyl cellulose, polysulfide rubber and the like. Can be mentioned.

When the electrode is manufactured by such a method, it is produced by coating and drying the coating liquid on the current collector.

The battery electrode manufactured using the active material of the present invention, the binder, the conductive auxiliary agent, other additives, for example, thickeners, dispersants, extenders, adhesion enhancers, etc. may be added, It means one containing at least 25% by weight of the above-mentioned active material.

Examples of the conductive auxiliary agent include metal powder, conductive metal oxide powder, carbon and the like. Particularly, the addition of such a conductive auxiliary agent is found to have a remarkable effect when I: A _x M _y N _z O ₂ of the present invention is used.

Among them, it is carbon that gives preferable results, and the addition of 1 to 30 parts by weight with respect to 100 parts by weight of I: A _x M _y N _z O ₂ usually exerts a remarkable effect of reducing overvoltage, and exhibits excellent cycle characteristics. Demonstrate.

The carbon referred to here is required to have characteristics completely different from those of the carbonaceous material II defined under the above-mentioned conditions, and does not necessarily mean the specified carbon.

Examples of such carbon include graphite and carbon black. As a particularly preferred combination, when carbon having an average particle size of 0.1 to 10 μ and carbon having an average particle size of 0.01 μ to 0.08 μ are mixed and used, a particularly excellent effect is provided.

The basic constituent elements for assembling the non-aqueous secondary battery of the present invention include an electrode using the active material of the present invention, a separator, and a non-aqueous electrolytic solution. The separator is not particularly limited, woven cloth, non-woven cloth, glass woven cloth,
Examples thereof include synthetic resin microporous membranes. As described above, when a thin film or a large area electrode is used, for example, JP-A-58-59
The synthetic resin microporous membrane disclosed in No. 072, especially a polyophine microporous membrane is preferable in terms of thickness, strength and membrane resistance.

The electrolyte of the non-aqueous electrolyte is not particularly limited, but an example
, LiClO_Four， LiBF_Four， LiAsF₆, CF₃SO₃Li, LiPF₆, L
iI, LiAlCl_Four， NaClO_Four， NaBF_Four, NaI, (n-Bu)_FourN ClO
_Four, (N-Bu)_FourN BF_Four， KPF₆Etc. or,
Examples of the organic solvent of the electrolytic solution used include ether.
, Ketones, lactones, nitriles, amines,
Amides, sulfur compounds, chlorinated hydrocarbons, esters,
Carbonates, nitro compounds, phosphate compounds
Compounds, sulfolane compounds, etc. can be used.
Among them, ethers, ketones, nitriles, salts
Organohydrocarbons, carbonates, sriphorane compounds
Is preferred. More preferably cyclic carbonates
It

As typical examples of these, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, anisole, monoglyme, acetonitrile, propionitrile, 4-methyl-2-pentanone, butyronitrile, valeronitrile, benzonitrile, 1,2- Dichloroethane, γ-butyrolactone, dimethoxyethane, methyl formate, propylene carbonate, ethylene carbonate, vinylene carbonate, dimethylformamide, dimethylsulfoxide, dimethylthioformamide, sulfolane, 3-methyl-sulfolane, trimethyl phosphate, trimethyl phosphate, and triethyl phosphate thereof. Examples of the mixed solvent include, but are not necessarily limited to, these.

Further, if necessary, a battery is constructed using parts such as terminals and insulating plates. Further, the structure of the battery is not particularly limited, but a positive electrode, a negative electrode, and further, if necessary, a paper type battery having a single layer or a multi-layer separator, a laminated type battery, or a positive electrode, a negative electrode, and further required. For example, a form of a cylindrical battery or the like in which a separator is wound in a roll shape can be mentioned.

[Effects of the Invention] The battery of the present invention is small and lightweight, has excellent cycle characteristics and self-discharge characteristics in particular, and is extremely useful as a power source for small electronic devices, electric vehicles, power storage, and the like.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The surface area was measured by a nitrogen adsorption method using a BET surface area measuring device P-700 type manufactured by Shibata Scientific Instruments Co., Ltd.
In addition, X-ray diffraction was performed according to the "Japan Society for the Promotion of Science". The true density was measured by a float-sink method at 25 ° C. using a powder prepared by crushing a carbonaceous material so as to pass through a 150 mesh standard sieve in an agate mortar and using a mixed solution of bromoform and carbon tetrachloride. For the sample having a true density distribution, the value at which about 50% of the entire powder particles settled was used as the measured value.

The relative permittivity was measured under the following conditions.

(Measurement temperature) 25 ° C (Measurement frequency) 1kHz (Sample shape) 0.5mm sheet (Measurement device) TR-10C type dielectric volume measuring instrument (manufactured by Ando Electric Co., Ltd.) Experimental example 1 10 μm thick copper foil 4 cm × 1c round hole with a hole diameter of 1.5mm in 100cm
16 holes per m ² with continuous holes with an average hole diameter of 1.5 mm,
A copper current collector having an aperture ratio of 28% and a thickness of 10 μm was obtained.

Experimental Example 2 36 round holes 1.0 mm in diameter were drilled in 4 cm x 100 cm aluminum foil with a thickness of 15 μm per cm ² , and there were continuous holes with an average hole diameter of 1.0 mm, and the aperture ratio was 28% and the thickness was An aluminum current collector of 15 μm was obtained.

Experimental Example 3 Commercially available petroleum diameter needle coke (Koa Oil Co., Ltd., KOA-SJ
Coke) was crushed with a ball mill to an average particle size of 3 μm. A coating solution was prepared by mixing 1 part by weight of this powder with 2.5 parts by weight of a solution of fluororubber in methyl isobutyl ketone (2 wt% concentration).

Experimental Example 4 A composite oxide having a composition of Li _1.03 Co _0.95 Sn _0.042 O ₂ was pulverized with a ball mill to an average of 3 μm, and then 1 part by weight of the composite oxide was added to a solution of fluororubber in methyl isobutyl ketone (2 wt% concentration). By weight, 0.2 part by weight of graphite as a conduction aid was mixed to prepare a coating liquid.

Example 1 The coating liquid prepared in Experimental Example 3 was applied to a copper foil current collector having holes in Experimental Example 1 using a dip coater under the following conditions and coating speed.
Coating was performed at 1 m / min, a drying temperature of 120 ° C. and a drying zone length of 1 m to obtain a film-forming electrode having a thickness of 75 μm. The appearance of this film-forming body was extremely good. A size of 1 cm × 5 cm was cut out from the film-forming electrode and sandwiched with a SUS net to obtain a negative electrode for the battery shown in FIG.

On the other hand, the coating liquid prepared in Experimental Example 4 was applied to the aluminum foil current collector having holes in Experimental Example 2 under the same conditions using a dip coater to obtain a film-forming electrode having a thickness of 100 μm. The appearance of this film-forming body was extremely good. 1 cm from the membrane electrode
A size of 5 cm was cut out, and this was sandwiched between SUS nets to be used as a positive electrode.

A 35 μm polyethylene microporous membrane was used as a separator, and a LiClO ₄ -propylene carbonate solution having a molar concentration of 0.6 was used as an electrolytic solution, and battery evaluation was performed at a constant current of 2 mA.

The above results are shown in Table 1.

Comparative Example 1 Positive and negative electrodes were formed in exactly the same manner as in Example 1 except that the copper foil having holes was replaced with copper foil in Example 1 and the aluminum foil having holes was replaced with aluminum foil. , The battery was evaluated. As the results are shown in Table 1, peeling is locally recognized in the appearance of the electrode film-forming body, and the battery performance is not stable.

Example 2, Comparative Examples 2 to 4 In Example 1, various thicknesses, hole diameters, and
An electrode was formed into a film by the same method except that a current collector having a hole shape and an aperture ratio was used, and the battery was evaluated. The results are shown in Table 1.

[Brief description of drawings]

FIG. 1 is a sectional view of a constitutional example of a secondary battery of the present invention. In FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 and 3'are collector rods,
4,4 'is a SUS net, 5,5' is an external electrode terminal, 6 is a battery case, 7 is a separator, and 8 is an electrolytic solution or a solid electrolyte.

Claims (1)

[Claims] 1. A secondary battery comprising at least a positive electrode, a negative electrode active material, a current collector, a separator and a non-aqueous electrolyte as constituent elements, wherein the positive electrode active material of a composite oxide is formed on an aluminum current collector. The carbonaceous material of the negative electrode active material is applied and formed on a copper current collector, and the current collector has continuous holes each having an average hole diameter of 1.5 mm or less, and an opening ratio of 5% or more and a thickness. Is 500 μm
A secondary battery comprising the following metal current collector.