JP2936217B2 - Method for producing lithium battery and negative electrode carrier thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lithium battery and a negative electrode carrier thereof, and more particularly, to a high energy density and long life applicable to a DC power source for vehicles such as automobiles and a power source for power storage. The present invention relates to a lithium secondary battery that can be increased in size and a method for manufacturing a negative electrode carrier thereof.

[0002]

2. Description of the Related Art Lithium is a very low-potential metal having a standard potential of -3.03 V and has a small atomic weight. Therefore, a lithium battery using lithium as a negative electrode active material has a high output voltage,
The energy density is also very high. Therefore, watches,
Lithium batteries are very often used in small and lightweight products such as cameras, but most of them are primary batteries that cannot be recharged.

[0003] A typical lithium primary battery uses metallic lithium as a negative electrode, graphite fluoride or manganese dioxide as a positive electrode active material, and a lithium salt as an electrolyte.
Some use an organic solvent solution (eg, LiBF ₄ , LiClO _4, etc.). Since metal Li, which is a negative electrode active material, has extremely high reactivity with water, it is difficult to use an electrolyte in an aqueous solution in a general-purpose lithium battery. A conductive solid is used as the electrolyte.

[0004] Since lithium can be electrodeposited from its ions by a cathodic reduction reaction, a lithium battery can also be used as a rechargeable secondary battery. Therefore, development of a high-output lithium secondary battery has been promoted utilizing the characteristics of lithium.

As a result, recently, rechargeable lithium secondary batteries have begun to be used in portable telephones, portable video cameras, and the like. The negative electrode of this lithium secondary battery is manufactured by binding a powder of a graphitic carbon material having a layered structure with a binder, and lithium penetrates between layers of the carbon material during charging and desorbs during discharging. It works by:
However, when the size of the negative electrode is increased, the current density is reduced and the cost is increased.

A practical problem of a lithium secondary battery using a metal-based negative electrode (lithium or lithium alloy) that is easy to increase in size is that lithium, which is a negative electrode active material, is deposited on the negative electrode surface during electrodeposition during charging. It grows like a dendrite, which contacts the positive electrode and causes an internal short circuit, which significantly shortens the charge / discharge cycle life. For this reason, performances such as charge / discharge cycle life and output density are still insufficient for large-sized lithium batteries for electric vehicles and power storage. In addition, a technique for manufacturing a large-area, inexpensive negative electrode has not been established. because of these reasons,
A lithium secondary battery using a metal-based negative electrode has not yet been put to practical use.

As a proposal for improving the life of a charge / discharge cycle of a lithium secondary battery, for example, Japanese Patent Application Laid-Open No. 52-5423 discloses a lithium battery using a Li--Al alloy having a Li content of 63 to 92% as a negative electrode. A battery is disclosed. In this battery, utilizing the property that aluminum absorbs and releases lithium,
Lithium is absorbed in aluminum during charging and Li-Al
Since the alloy is used, the dendritic growth of lithium is suppressed.

However, it has been found that the strength of the Li-Al alloy is not sufficient, and the alloy is pulverized by repetition of charge / discharge, so that a sufficient charge / discharge cycle life cannot be obtained. Therefore, it has been proposed to add various alloying elements to aluminum to increase the strength of the negative electrode and to improve the charge / discharge cycle characteristics of the battery.

For example, Japanese Patent Application Laid-Open No. 64-86451 discloses Al
A lithium secondary battery using a -Mn-In alloy as a negative electrode carrier is described. By adding Mn, which is difficult to alloy with Li, to act as an aggregate to increase the strength of the negative electrode, it is possible to compensate for the delay in diffusion of Li, which was impaired by the addition of Mn, by adding In, which has a large Li storage capacity. Described.

Japanese Patent Application Laid-Open No. Hei 3-182058 discloses Li-Al-XY which is an alloy of a group X consisting of Mn and Cr and a group Y consisting of Be, Bi, Cd, Ge, Pb, Sn and Ta. A lithium secondary battery using an alloy for a negative electrode is described. X is added to increase the strength of the Li-Al alloy, but X that does not form a solid solution segregates as an intermetallic compound at the grain boundary, and there is a problem that cracks are generated from the starting point during charge and discharge. Therefore, it is a proposal that by adding Y, a eutectic or peritectic metal structure is formed, and since Y is a metal having relatively high ductility, cracks can be suppressed.

Japanese Patent Application Laid-Open No. 4-58468 discloses that the segregation of the third metal element added to the Li-Al alloy makes the insertion and detachment of lithium during charging and discharging non-uniform, thereby causing the electrode to be locally localized. It is pointed out that deterioration is pointed out, and it is described that by adding 0.01 to 10% by weight of the added metal as a solid solution, lithium insertion / removal becomes uniform and cycle characteristics are improved.

[0012]

In each of these proposals, an aluminum alloy having excellent strength is used as a negative electrode carrier, and lithium as an active material is inserted into the negative electrode carrier to form a negative electrode. . Such a metal-based anode using an aluminum alloy as a carrier has a certain effect in improving the charge / discharge cycle characteristics of a lithium battery,
According to the investigations by the present inventors, the performance is still insufficient.Especially, further improvement is required for large-sized and long-life (long-term use) applications such as electric vehicles and power storage. It was determined that there was. That is, in the lithium secondary battery according to the above proposal, since the negative electrode carrier made of an aluminum alloy is manufactured by a metallurgical method (eg, smelting → casting → rolling), segregation of a metal that does not occlude lithium occurs. This segregation severely limits the inherent lithium diffusion performance of aluminum metal, and thus limits the improvement of charge and discharge characteristics. In addition, since it is extremely difficult to form a highly brittle aluminum alloy into a large plate by metallurgical techniques, it is also difficult to increase the area of the negative electrode (that is, increase the capacity of the battery), and the production cost is high. .

Accordingly, an object of the present invention is to provide a lithium battery which can be used as a secondary battery having extremely excellent charge / discharge cycle characteristics. Another object of the present invention is to make it possible to realize a large-capacity secondary battery for an electric vehicle or for storing electric power, so that the area of the negative electrode can be easily increased and the negative electrode carrier can be manufactured at low cost. It is to provide a lithium battery. Still another object of the present invention is to provide a method for producing such a negative electrode carrier of a lithium battery.

[0014]

Means for Solving the Problems The present inventors have found that it is difficult to make a dramatic progress in the performance of lithium batteries with an existing anode using an aluminum alloy produced by a metallurgical method as a carrier for lithium absorption. Therefore, the inventors focused on an aluminum alloy which is in a thermodynamically non-equilibrium state as a negative electrode carrier material which can achieve the above object. This is because, in the case of aluminum alloys obtained by conventional metallurgical methods, the alloy system is in a thermodynamic equilibrium state, and the particles of the precipitated phase become larger due to growth. This is because, in the non-equilibrium state, the precipitated phase can be in a fine state close to the atomic order. And among the non-equilibrium aluminum alloys,
Focusing on Al-Mn alloy known as an alloy system that easily produces an amorphous phase and a quasicrystalline phase, coating a base metal that serves as a current collector with a specific Al-Mn alloy layer enables low cost It was found that it was possible to produce a negative electrode carrier having a large area easily.

Here, the present invention is characterized in that a lithium battery comprising a positive electrode, a negative electrode containing lithium as an active material, and an electrolyte comprising a non-aqueous solution of a lithium salt or a lithium ion conductive solid is provided. Another aspect of the present invention is to use a coating material having an Al-Mn alloy coating layer having a structure containing a thermodynamic non-equilibrium phase on the surface of a base metal.

Specifically, the support of the negative electrode in the lithium battery of the present invention is a thermodynamically non-equilibrium Al-Mn alloy comprising a mixed phase of a Mn supersaturated fcc-Al phase and an Al-Mn amorphous alloy phase. It consists of a coating material having an alloy coating layer on the surface of the base metal. Other phases may be present in the Al-Mn alloy coating within a range that does not have a substantial adverse effect.

This negative electrode carrier has a Mn content of 10 to 25 on the surface of the base metal by a coating method for forming a thermodynamic non-equilibrium phase.
It can be manufactured by coating with Al-Mn alloy of weight%.

Although the lithium battery of the present invention can be used as a primary battery, it is possible to take advantage of its excellent charge / discharge characteristics especially when it is a secondary battery. Coating methods for forming a thermodynamic non-equilibrium phase include any coating method that can form a coating containing a thermodynamic non-equilibrium phase. Examples thereof include dry methods such as sputtering, ion plating, vapor deposition, and CVD, and non-aqueous electroplating methods such as molten salt electroplating and electroplating in a non-aqueous solvent electrolyte. Above all, formation of a coating by electroplating is most preferable from the viewpoint of battery performance.

[0019]

[Effect] Al, Al ₆ Mn,
Al ₄ Mn, Al ₁₁ Mn ₄ , Mn, etc. exist, and Al-
When an Mn alloy is produced, a thermodynamically equilibrium alloy structure composed of any one of these single phases or a mixed phase of two or more phases is obtained depending on the composition.

On the other hand, non-equilibrium phases not shown in the thermal equilibrium diagram of the Al-Mn binary system include an amorphous phase and a quasi-crystalline phase. These non-equilibrium phases can be formed by a liquid quenching method, a mechanical alloying method, or a dry method such as sputtering, ion plating, vapor deposition, or CVD, or a non-aqueous electrolytic method such as molten salt electroplating or electroplating in an organic solvent. It is known that Al-Mn alloys are produced when they are produced by plating or the like.

For example, in the case of electroplating by molten salt electrolysis, as the Mn concentration increases, fcc-Al (face-centered cubic Al crystal)
Single phase, Mn supersaturated fcc-Al phase (hereinafter referred to as Mn supersaturated Al phase)
, The mixed phase of the Mn supersaturated Al phase and the Al-Mn amorphous phase, and then the Al-Mn amorphous single phase. Of these, the first fcc-Al
The single phase is an equilibrium phase (same as Al in the equilibrium phase), but the rest are non-equilibrium phases that cannot be obtained by metallurgical techniques.

The present inventors conducted a charge / discharge life test of a lithium battery obtained by alloying an Al-Mn alloy system containing these various non-equilibrium phases with lithium and using it as a negative electrode. In the case of a mixed phase of the Al-Mn amorphous phase and the Al-Mn amorphous phase, the deterioration of the negative electrode due to the removal of brittle compounds as seen in the conventional aluminum alloy-based negative electrode material does not occur, and the cycle characteristics (charge and discharge Lifetime) is very high. This is due to the fact that the crystalline portion (fc existing in the Mn supersaturated Al phase)
The c-Al phase) is responsible for the charge / discharge reaction due to the insertion and extraction of lithium, and the Al-Li compound generated at that time falls off during repeated charge / discharge. This is probably due to the support of the Mn amorphous phase). Moreover, the crystalline fcc-Al phase that reacts with lithium is itself a relatively high-strength phase because Mn forms a solid solution in supersaturation (that is, forms a Mn supersaturated Al phase). The amorphous phase supporting this is not a crystalline and brittle phase such as a segregated compound phase in an Al-Mn alloy by metallurgy. Therefore, it is considered that superior cycle characteristics that have not been achieved in the past can be exhibited.

It has been found that the battery exhibits excellent charge / discharge characteristics.
An Al-Mn alloy having a thermodynamic non-equilibrium structure mainly composed of a mixed phase of an Mn supersaturated Al phase and an Al-Mn amorphous phase is obtained when the Mn content is in an alloy composition within a range of 10 to 25% by weight. It turns out that it can. Such an Al-Mn alloy material having a high Mn content is
It is difficult to produce by a metallurgical technique using rolling, and it can be produced by the above method capable of forming a non-equilibrium phase.

In the present invention, in order to increase the area and reduce the cost of the electrode, the surface of the base metal functioning as a current collector is formed by absorbing and releasing lithium as the negative electrode active material. A coating material coated with an Al-Mn alloy layer capable of performing the above is used. Therefore, the base metal is made to have a Mn content of 10 to 25% by weight by a coating method for forming a thermodynamic non-equilibrium phase.
By coating with an Al-Mn alloy, Mn supersaturated Al phase and Al
A coating layer of an Al-Mn alloy having a non-equilibrium structure composed of a mixed phase with a -Mn amorphous phase and exhibiting excellent charge / discharge characteristics can be formed. In the present invention, the thus obtained coating material is used as a negative electrode carrier of a lithium battery.

As a coating method, a dry method such as a sputtering method, an ion plating method, a vapor deposition method, and a CVD method is used.
(Dry process) is also possible. However, the non-aqueous electroplating method can form an Al-Mn alloy coating showing particularly excellent charge / discharge characteristics. Although the reason is not clear, the metastable non-equilibrium state obtained when Al and Mn in the ionic state are changed to the metal state by voltage application in electroplating has superior characteristics compared to those obtained by other methods. It seems to be able to demonstrate.

Next, a method for producing the above-mentioned coating material used as the negative electrode carrier of the lithium battery of the present invention will be described. Al
It is preferable to use a current collector as the base metal covered with the -Mn alloy layer. When the base metal is a current collector, Al-
Since the negative electrode with the current collector integrated with the Mn alloy coating can be obtained, the electrical contact is better than when the current collector and the negative electrode are separately made and then joined as in the past. This is because the steps and the battery structure can be simplified. However, since it is not always necessary to use the current collector as the base metal, it is also possible to configure the negative electrode portion by using another base metal and bonding the obtained coating material to the current collector as the negative electrode carrier. It is possible.

The metal material suitable for the substrate is a material which has relatively good corrosion resistance in the battery and is inexpensive. For example, nickel, iron, stainless steel, titanium, aluminum and the like can be used. The shape of the base metal can be selected from various shapes such as a foil, a plate, a corrugated plate, a mesh, and a perforated plate according to the configuration of the battery.

As the coating method, both the dry method and the non-aqueous electroplating method can be adopted as described above, but the electroplating method is more preferable. The dry method requires vacuum equipment, is costly, has a manufacturing constraint that the film formation rate is not so fast, and the coating formed by the electroplating method exhibits particularly excellent charge / discharge characteristics as described above. It is.

The formation of the Al-Mn alloy coating layer by the dry method is as follows.
What is necessary is just to implement according to a conventionally well-known method. For example,
Sputtering can be performed using a conventional sputtering apparatus that uses an Al-Mn alloy plate having substantially the same composition as the Al-Mn alloy to be coated as a target material and generates argon gas ions by glow discharge.

In Al-based electroplating containing Al metal and Al alloy, the deposition potential of Al in an aqueous solution system is considerably lower than the hydrogen generation potential from water, and aluminum does not precipitate from an aqueous solution. It must be performed in a non-aqueous electrolyte. There are two types of non-aqueous electrolytes: non-aqueous solvent system (organic solvent + inorganic salt) and molten salt system. Industrially, molten salt electroplating without organic solvent is more suitable. .

The non-aqueous solvent-based Al-Mn alloy plating is performed, for example, by mixing an aluminum compound such as AlCl ₃ and LiAlH ₄ with MnCl _2.
A solution in which a manganese compound such as manganese is dissolved in an organic solvent such as ether or tetrahydrofuran can be used as an electrolytic solution.

The electrolytic solution of the Al-based molten salt electroplating includes:
Room temperature type molten salt using special organic matter (eg, AlCl ₃ + EM
IC <ethyl methyl imidazolium chloride>) and molten salt consisting only of inorganic salt (eg, AlCl ₃ + NaCl + KCl) .Either type can be used. A description will be given of an example of an electroplating method of an Al-Mn alloy using a salt.

This molten salt electroplating is performed, for example, in the following steps. Alkaline degreasing → washing with water → pickling → washing with water → (pre-plating → washing with water) → drying → molten salt plating → washing with water → drying The pretreatment of the base metal to be coated is usually a combination of alkali degreasing, pickling, washing with water, etc. Activate by removing the surface oxide film on the substrate. The kind and order of such pretreatment are not particularly limited as long as surface activation is achieved. Further, as a pretreatment, activation may be performed by dissolving the anode in a molten salt.

When the base metal is an easily oxidizable metal such as stainless steel, titanium, or aluminum, the oxide film on the surface is strong, and the pretreatment for surface activation as described above is performed. In some cases, the adhesion between the substrate and the plating film cannot be ensured. In that case, pre-plating is performed in addition to the pretreatment. The kind of metal to be pre-plated is not particularly limited, but nickel is preferable from the viewpoint of adhesion to Al-Mn alloy plating and corrosion resistance in the battery.
The pre-plating method may be a general electroplating method, and there is no problem even if at least one element other than nickel is contained as an inevitable impurity. Film thickness when coating weight of the pre-plating of 0.05 to 5 g / m ² about (Ni 0.006
0.60.6 μm). If the pre-plated coating weight is less than 0.05 g / m ² , there are too many pre-plated portions on the surface of the material to be plated, and an oxide film is formed on those portions, and the adhesion of the Al-Mn alloy plating It can cause failure. The pre-plated coating weight can be more than 5 g / m ² , but is not preferred from the viewpoint of cost.

After the base metal thus pretreated is washed with water, it is sufficiently dried so that moisture does not enter the molten salt bath for Al-Mn alloy plating in the next step. For this drying, adjust the atmosphere or temperature so that no oxide film is formed on the pre-plated surface (eg, dry in an inert gas atmosphere)
Is preferred.

Aluminum-based molten salt electroplating is already well-known, and the Al—Mn alloy plating coating of the present invention may be performed according to a conventional method. The molten salt electrolytic bath is not particularly limited as long as it contains aluminum and manganese salts. Also, it is within the scope of the present invention that other metals co-deposit in the formed Al-Mn alloy coating due to impurity ions unavoidably mixed into the bath, but the amount of eutectoid is within 1% by weight. Is preferred.

A typical example of the electrolytic bath used is an aluminum chloride-based mixed molten salt, which contains other chlorides such as inorganic salts together with aluminum chloride and manganese chloride. Examples of inorganic chlorides include, for example, sodium chloride,
Examples thereof include alkali metal chlorides such as potassium chloride and lithium chloride. The temperature of the molten salt varies depending on its component and composition.For example, in the case of an alloy plating bath in which MnCl ₂ is added to a molten salt having a eutectic composition of AlCl ₃ -NaCl-KCl, plating is performed at around 200 ° C. .

After the molten salt electroplating, the plating material taken out of the molten salt bath is washed with water and dried to obtain a coating material used as the negative electrode carrier of the lithium battery of the present invention. FIG. 1 shows a configuration example of the negative electrode carrier. In FIG. 1, 1 is a base metal (a current collector, eg, SUS430 stainless steel foil having a thickness of 0.4 mm), 2 is a pre-plating layer (eg, a nickel plating layer having a thickness of 0.2 μm), and 3 is a feature of the present invention. It is an Al—Mn alloy plating layer (eg, a 20 μm thick Al-17% Mn alloy plating layer) formed by a certain molten salt electroplating method. When the base metal is a metal which is hardly oxidized such as nickel, or when the coating is formed by a dry method such as sputtering, the pre-plating layer 2 is not necessary.

In the present invention, it is sufficient that at least the surface of the negative electrode carrier has a structure containing a non-equilibrium phase, specifically, a mixed phase of a Mn supersaturated Al phase and an Al-Mn amorphous phase.
The Al-Mn alloy layer having such a structure can be formed not only by non-aqueous electroplating but also by the above-mentioned dry method. Also,
It is conceivable that the entire negative electrode carrier may be formed from an Al-Mn alloy having such a non-equilibrium phase structure by a liquid quenching method or a mechanical alloying method.However, these methods produce a large-area and uniform negative electrode carrier. And the mechanical strength is not sufficient. Further, in this case, the obtained negative electrode carrier must be joined to a separately manufactured current collector. As described above, by constituting the negative electrode carrier from a coating material obtained by coating the current collector with an Al-Mn alloy by a dry method or an electroplating method, having a structure integrated with the current collector,
It is possible to easily produce a large-area negative electrode carrier having high mechanical strength.

The Mn content in the Al-Mn alloy coating layer is set in the range of 10 to 25% by weight. If the Mn content is less than 10% by weight, almost no Al-Mn amorphous phase that supports the Al crystal phase (Mn supersaturated Al phase) that reacts with Li is formed, and the Mn supersaturated Al phase is substantially single. Since it is the same as the phase, it is not possible to effectively prevent the pulverization due to the falling off of the reaction product Al-Li compound at the time of repetition of charge and discharge, and the cycle characteristics are deteriorated.

If the Mn content exceeds 25% by weight, the structure becomes Al
-Change to a single phase of the Mn amorphous phase. In some cases, the Al crystalline phase that reacts with Li and alloys may remain a little, but since the ratio is reduced, the amount of lithium absorbed decreases, the battery capacity is significantly reduced, and the Al crystalline phase disappears. Then, it does not substantially function as a negative electrode. The preferred Mn content of the Al-Mn alloy coating layer is in the range of 13 to 20% by weight.

The thickness of the Al—Mn alloy coating layer is appropriately set depending on the purpose of use of the battery, but is usually preferably 1 to 100 μm, particularly preferably 3 to 30 μm. If the coating thickness is small,
Film formation is possible in a short time, but the battery capacity is reduced.
Conversely, as the coating thickness increases, the battery capacity increases, but it takes time to form the film. Al-Mn alloy layer coating,
It is not necessary to cover the entire surface of the base metal, and only a part of the surface may be coated. Normally, as shown in FIG. 1, the above-mentioned Al-Mn alloy coating layer is formed on the entire surface of the base metal. However, in the case of a coin-type battery, only one side may be coated.

The lithium battery of the present invention is characterized in that a coating material having an Al-Mn alloy coating layer composed of a structure containing the above non-equilibrium phase on the surface of a base metal (preferably a current collector) is used as a negative electrode carrier. Thus, it can be configured similarly to a conventional lithium battery. That is, the other components such as the positive electrode, the electrolyte, and the separator may be the same as the conventional components. In addition, as the electrolyte, a lithium salt, which has been generally used conventionally,
(E.g., LiBF ₄ , LiClO ₄ etc.) with an aprotic organic solvent
In addition to a non-aqueous solution dissolved in (eg, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, etc.), a lithium ion conductive solid (eg, an electrolyte composed of polyethylene oxide and a lithium salt) can also be used.

The lithium battery of the present invention is suitable for a large-capacity lithium secondary battery used for electric vehicles and electric power storage because the area of the negative electrode can be easily increased and the charge / discharge characteristics are excellent. In terms of its performance, it is obvious that there is no problem even if it is used for a lithium primary battery or a small lithium secondary battery used for a portable electric product.

[0045]

The present invention will be described in more detail with reference to the following examples. In the examples,% is% by weight unless otherwise specified.
It is.

Example 1 A lithium secondary battery having the following structure was manufactured. The positive electrode is a suspension in which the positive electrode active material MnO ₂ , conductive graphite, and polyvinylidene fluoride as a binder are mixed with DMF (dimethylformamide), and has a thickness of 20 μm, a width of 40 mm, and a length of 1250 m.
m was uniformly applied to a nickel foil and dried.

The negative electrode was prepared by coating the entire surface of both sides of a nickel foil having the same dimensions as above with a 10 μm thick Al-Mn alloy by a molten salt electroplating method or a sputtering method. The electroplating conditions were as shown in Table 1. Sputtering method, Al-Mn produced by melting method
Using alloy plate as target material, vacuum degree 10 ^-6 to 10 ^-7
The film was formed at a power of 150 W in a vacuum vessel of torr. The film thickness was controlled by adjusting the sputtering time. The Mn content was adjusted by changing the Mn content in the target material.

[0048]

[Table 1] A 40 μm thick polypropylene microporous membrane was used as the separator. The positive and negative electrodes were wound into a roll via a separator, placed in a battery can, filled with a 1 M propylene carbonate solution of LiClO ₄ , which is a non-aqueous solution, as an electrolytic solution, sealed, and sealed as shown in FIG. The secondary battery was assembled. 2, reference numeral 4 denotes a positive electrode, 5 denotes a separator, 6 denotes a negative electrode, 7 denotes an insulating plate, 8 denotes a nickel positive electrode lead, and 9 denotes a gasket.

The cycle life of this lithium secondary battery was repeatedly measured by a charge / discharge test. The charge and discharge cycle is
(Charge 500 mA x 30 minutes) → (5 minutes pause) → (Discharge 500 mA
1.0V vs. Li) → (5 minutes pause), and the cycle life (to the life is defined as the life when the charge / discharge efficiency [= (discharged electricity / charged electricity × 100)] drops to 90% And the charge / discharge characteristics were evaluated.

Table 2 shows the cycle life thus obtained.
It shows the Mn content in the Al-Mn alloy coating in the negative electrode, the structure of the Al-Mn alloy coating examined by X-ray diffraction and observation of the structure by a transmission electron microscope.

[0051]

[Table 2]

As is clear from the results in Table 2, among the comparative examples, in Test Nos. 1 to 5, the Mn content in the Al-Mn alloy coating was lower than 10%, and the crystal structure was fcc-Al single phase ( (Including those in the non-equilibrium state where Mn is supersaturated.)
It was short, less than times. On the other hand, in Test Nos. 12 to 14, Al-Mn
Since the Mn content of the alloy coating exceeded 25% by weight, the structure was changed to Al.
Since it became -Mn amorphous single phase and did not alloy with Li, an efficiency of 90% or more could not be obtained.

On the other hand, Test No. 6 which is an example of the present invention
In ~ 11, an Al-Mn alloy coating consisting of a mixed phase structure of a crystalline fcc-Al phase (Mn supersaturated) and an Al-Mn amorphous phase is formed,
The cycle life has been dramatically extended to over 1,000 times.

For reference, as a conventional example, a pure Al plate and Al-Mn prepared by a metallurgical method (melting, casting, rolling).
Using the alloy plate (thickness: 100 μm) pressed against the nickel foil to form a negative electrode carrier, a secondary battery was assembled and a charge / discharge test was repeated in the same manner as described above. The cycle life in this case is about 90 times with a pure Al plate, and the Al-
Even in the case of the Mn alloy plate, even if the Mn content was changed, it was almost the same as that of the comparative example in Table 2, and the cycle life was not significantly improved as in the present invention.

[0055]

According to the present invention, the Mn content is 10 to 25% by weight.
By coating the base metal with an Al-Mn alloy by a coating method such as an electroplating method that forms a thermodynamic non-equilibrium phase and a sputtering method, a non-equilibrium phase, specifically, a Mn supersaturated Al crystal phase and Al An Al-Mn alloy coating layer composed of a mixed phase with a -Mn amorphous phase is formed, and the charge / discharge cycle characteristics of the lithium secondary battery are dramatically improved. Furthermore, the negative electrode carrier produced by the method of the present invention can produce a large area substrate at low cost. Therefore, a large-sized, large-output lithium secondary battery for electric vehicles and power storage can be manufactured at low cost, and the industrial value of the present invention is extremely high.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one example of a negative electrode carrier according to the present invention.

FIG. 2 is a schematic sectional view of one example of a lithium battery according to the present invention.

[Explanation of symbols]

1: metal substrate (current collector), 2: pre-plated layer, 3: Al-
Mn alloy coating layer, 4: positive electrode, 5: separator, 6: negative electrode, 7: insulating plate, 8: positive electrode lead, 9: gasket

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01M 10/40 H01M 10/40 Z (72) Inventor Shunichi 1-8-3 Midorigaoka, Ikeda-shi, Osaka Within the Technical Research Institute (72) Inventor Ken Abe 4-5-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries, Ltd. (72) Inventor Junichi Uchida 4-5-33, Kitahama, Chuo-ku, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor Katsuro Hirayama 4-5-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries, Ltd. (72) Inventor Kunihiro Fukui 4-5-33, Kitahama, Chuo-ku, Osaka City Examination in Sumitomo Metal Industries, Ltd. Government Hitoshi Amano (56) References JP-A-5-290853 (JP, A) JP-A-6-310126 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 4/02 -4/12 H01M 4/64-4/84 H01M 6/14-6/20 H01M 10/40

Claims (4)

(57) [Claims] 1. A lithium battery comprising a positive electrode, a negative electrode using lithium as an active material, and an electrolyte comprising a non-aqueous solution of a lithium salt or a lithium ion conductive solid, wherein the negative electrode has a Mn supersaturated fcc- A carrier having a coating material having a thermodynamically non-equilibrium Al-Mn alloy coating layer composed of a mixed phase of an Al phase and an Al-Mn amorphous alloy phase on the surface of the base metal, Lithium battery. 2. The lithium battery according to claim 1, which is a secondary battery. 3. A method for producing a negative electrode carrier for a lithium battery, comprising coating a surface of a base metal with an Al—Mn alloy having a Mn content of 10 to 25% by weight by a coating method for forming a thermodynamic non-equilibrium phase. . 4. The method according to claim 3, wherein said coating method is a non-aqueous electroplating method.