JPH0888022A - Secondary battery and manufacture of secondary battery - Google Patents

Abstract

PURPOSE: To increase the energy density and lengthen the cycle life by covering the projecting part of a conductive body of a negative electrode with an insulator or a semiconductor film. CONSTITUTION: A projecting part 110 of a negative electrode conductor 100 is covered with an insulator or a semiconductor film 101 except for a region coming in contact with an electrolyte between the projecting parts 110. By charging, an active material 105 is deposited in the part coming in contact with the electrolyte of the conductor 100, but since the projecting part 110 is covered with the film 101, electric field is not concentrated on the projecting part 110. The electric field is concentrated on the bottom of a pore, coming in contact with the electrolyte, between the projecting parts to deposit the active material 105, and the active material 105 comes in contact with the projecting part 110 or the film 101 by continuing deposition. The growing direction of the active material 105 is suppressed, and the growth of dendrites is prevented or suppressed. If the total volume of pores formed with the film 101 is more than the total volume of the active material 105 deposited on charging, the contact area of the active material 105 with the electrolyte can be reduced, the growth of dendrites is retarded to lengthen the cycle life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery and a method for manufacturing the same, and more specifically, it is highly safe even when charging and discharging are repeated, and in particular, dendrite (dendritic crystal) generated by repeated charging and discharging. (2) A secondary battery capable of suppressing the growth and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, it has been pointed out that the global warming may occur due to the greenhouse effect due to an increase in CO ₂ contained in the atmosphere. In thermal power generation, thermal energy obtained by burning fossil fuels and the like is converted into electric energy, but it is difficult to construct a new thermal power plant because CO ₂ and NO _x are emitted with the fuel. ing. In addition, since the generator operates normally in terms of efficiency as well, so-called load leveling is used to level the load by storing night power, which is surplus power, in a secondary battery installed in a general household as an effective use of the generator. It is being advocated to do so.

Further, there is a demand for development of a lightweight and high energy density secondary battery for an electric vehicle which does not emit substances such as CO _x , NO _x and CH _{x which} are said to be related to air pollution, a book type personal computer and There is an ever-increasing demand for small, lightweight, high-performance secondary batteries that can be used as power sources for word processors or portable devices such as video cameras and mobile phones.

As one of the above high performance secondary batteries, a rocking chair type lithium ion battery using lithium ion as an intercalation compound as a positive electrode active material and carbon as a negative electrode active material has been developed, and some of them have been put into practical use. It is being converted. However, the lithium-ion batteries that can be obtained now cannot be said to have achieved the high energy density that is the original feature of lithium batteries that use metallic lithium as the negative electrode active material.

[0005]

In a lithium secondary battery, dendritic lithium may be deposited on the negative electrode during charging. When dendritic lithium is generated and grows, in the worst case, it may break through the separator normally provided between the positive and negative electrodes and reach the positive electrode, causing a short circuit, or even causing self-discharge. There is also.

Attention has been paid to secondary batteries with high energy density. One of the reasons why a high-capacity lithium storage battery using a lithium metal as a negative electrode has not been sufficiently put into practical use is caused by repeated charging and discharging as described above,
This is because we have not succeeded in sufficiently suppressing the generation of lithium dendrites that are the main cause of short circuits. When lithium dendrite grows due to repeated overcharging and charging / discharging and the negative electrode and positive electrode are short-circuited, the battery's energy is consumed in a short time, causing the battery to generate heat and the solvent of the electrolyte solution to decompose due to heat. In some cases, the gas may vaporize to generate gas and the internal pressure in the battery may increase.

In any case, the generation and growth of dendrites may cause deterioration of battery performance and life due to a short circuit inside the battery.

Also, a method of using a lithium alloy such as lithium-aluminum for the negative electrode has been attempted in order to suppress the reactivity of lithium and suppress the generation of dendrites.
However, under the present circumstances, those having a high energy density and a sufficiently long cycle life have not been put into practical use even though the generation of dendrites can be suppressed.

Examples of using a lithium alloy for the negative electrode are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 63-13264, 5-47381 and 5-190171.

[0010] To be more specific, taking Japanese Patent Application Laid-Open No. 5-190171 as an example, Japanese Patent Application Laid-Open No. 5-190171 discloses a non-aqueous electrolyte secondary battery having a long cycle characteristic life and excellent cycle characteristics after storage. In order to achieve this, the negative electrode is an active material and a base material made of an alloy in which at least one selected from a metal electrochemically more precious than aluminum (for example, vanadium, chromium, titanium) is added to an alloy made of aluminum and manganese. It is disclosed to be composed of an alloy of lithium, thereby increasing the active sites of the reaction with lithium and suppressing the localization of the reaction in the alloy.

Further, in Japanese Patent Laid-Open No. 63-114057, in order to improve charge / discharge cycle characteristics, a mixed sintered body of a fibrous aluminum and a metal fiber which is not alloyed with lithium is used as a negative electrode of a secondary battery. Is disclosed as a base material and a lithium-aluminum alloy as an active material.

Further, in Japanese Patent Laid-Open No. 234585/1993, metal powder which hardly forms an intermetallic compound with lithium metal is uniformly attached to the surface of a base material made of lithium metal to reduce dendrite precipitation. , Batteries with high charging efficiency and improved cycle life have been shown.

However, the lithium metal which is the base material repeatedly expands and contracts due to charge and discharge, resulting in the falling of the adhered powder and the cracking of the base material. As a result, as described above, it is possible to maintain the sufficient current collecting ability of the negative electrode. Dendrite precipitation may not be sufficiently suppressed.

In addition, JOURNAL OF APPLI
ED ELECTROCHEMISTRY 22,62
0-627, (1992) reported a lithium secondary battery using an aluminum foil whose surface was etched as a negative electrode. However, when the charge / discharge cycle is repeated to a practical range, the aluminum foil repeatedly expands and contracts due to repeated charge / discharge, resulting in cracks in the aluminum foil.
Growth of dendrites may occur with a decrease in current collection. Therefore, in this case as well, it cannot always be said that a battery having a sufficiently long cycle life at a practical level has been obtained.

While the advent of a lithium secondary battery having a negative electrode having such a high energy density and a sufficiently long cycle life is awaited, in reality, it still has a problem to be solved. Is the reality.

Further, nickel zinc batteries and zinc-air batteries, which use zinc or zinc alloy as the negative electrode, are also attracting attention because of their high energy densities. Similar to the secondary battery, it has a problem of dendrite generated in the negative electrode, and in reality, a battery having a high energy density and a practically long cycle life has not been obtained.

As described above, the development of secondary batteries such as a lithium secondary battery, a nickel zinc secondary battery, an air zinc secondary battery and a bromine zinc secondary battery, which have a sufficiently high energy density and a sufficiently long cycle life. However, in reality, there are still problems to be solved in reality.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a secondary battery having a high energy density and a long cycle life, and a method for manufacturing the same.

Further, according to the present invention, the structure of the battery is not complicated,
An object of the present invention is to provide a secondary battery which is not complicated in manufacturing method and procedure, is excellent in workability, has low cost, and has high reliability, and a manufacturing method thereof.

A further object of the present invention is to provide a secondary battery capable of suppressing the generation and growth of dendrites and having less variation in performance, and a method for manufacturing the secondary battery.

[0021]

The secondary battery of the present invention comprises a negative electrode, a positive electrode provided via the negative electrode and a separator, and an electrolyte indirectly provided on the negative electrode and the positive electrode. The secondary battery having the above-mentioned structure is characterized in that the protruding portion of the conductor of the negative electrode is covered with at least an insulator or a semiconductor.

The method for producing a secondary battery according to the present invention is a method for producing a secondary battery having a negative electrode, a positive electrode provided via the negative electrode and a separator, and an electrolyte provided between the negative electrode and the positive electrode. And at least the surface of the conductor material of the negative electrode in the electrolytic solution, by using one or more electrochemical methods selected from anodizing, anodic deposition, cathodic deposition, electrolytic polymerization, electrophoretic electrodeposition, the conductor The method is characterized by including a step of forming an insulator or a semiconductor on the protrusions on the surface.

The inventors of the present invention have made repeated studies on the occurrence of dendrites in view of the above problems, and have thought that it is related to the concentration of lines of electric force. Therefore, the inventor conducted a model experiment.

5 (a) and 5 (b) are schematic sectional views of a part of the negative electrode, respectively. The negative electrode shown in FIG. 5A has a shape of a conductor negative electrode 500 having a protrusion 501, and the negative electrode shown in FIG. 5B has a surface of the conductor negative electrode 500 partially covered with an insulating film. It is configured.

The present inventor conducted a model experiment using a negative electrode having such a shape and configuration in which the lines of electric force are considered to be concentrated.

In the figure, reference numeral 502 indicates each conductor negative electrode 50.
It is a positive electrode arranged so as to face 0. In the figure, the electrolytic solution and the separator are respectively arranged between the negative electrode and the positive electrode, but they are omitted in the figure.

The arrows in the figure schematically represent the lines of electric force during charging. As shown in FIG.
In FIG. 5A, the lines of electric force are concentrated on the protrusion 501, and FIG.
In (b), it is considered that the lines of electric force are concentrated on the portion not covered with the insulator film 503.

A nickel or titanium foil is used to form a protrusion 501 as shown in FIG. 5 (a) and an insulating coating 503 as shown in FIG. 5 (b) on the model experimental conductor negative electrode 500. Then, when lithium was deposited on the conductor negative electrode 500 at a high current density by a charging reaction, dendrite deposition of lithium was observed at a place where electric lines of force seemed to be concentrated. This result suggests that the level of the electric field strength on the surface of the negative electrode, that is, the presence of the protrusions or the nonuniform insulating coating on the surface of the negative electrode of the conductor may be one of the causes of the dendrite growth of lithium.

In practice, for example, when using a lithium metal foil as the conductor negative electrode, if the positive and negative electrodes are pressed together to reduce the distance between the positive and negative electrodes in order to reduce the impedance of the battery, lithium is a soft metal and the positive electrode The unevenness may be transferred by pressure and a protrusion may be formed.
Further, lithium may react with impurities in the handling atmosphere or in the electrolytic solution to form a non-uniform insulating film such as lithium carbonate, lithium hydroxide or lithium fluoride on the surface.

Therefore, it is highly possible that the phenomenon described in the model as shown in FIGS. 5A and 5B actually occurs.

In order to suppress the dendrite growth of lithium due to the above causes, it is effective to eliminate or reduce the protrusion and the non-uniform insulating coating. For that purpose, it is necessary to give sufficient consideration so that the surface of the negative electrode is mirror-polished to eliminate even microscopic protrusions and that the surface is not scratched even after mirror-polishing.

Alternatively, it becomes necessary to completely or substantially completely remove lithium covered with lithium carbonate, lithium hydroxide or the like, or a metal insulating film covered with a metal oxide film. .

However, it is very difficult to perform mirror-polishing on a soft metal such as lithium, and in order to eliminate the insulating coating of lithium metal, the surface of the negative electrode causes unnecessary reaction with the surrounding atmosphere and surrounding substances, which is unnecessary. To prevent the formation of reaction products (insulating coatings) on the negative electrode surface, clean the negative electrode surface under an inert gas or vacuum that does not react with the negative electrode, and then perform all the steps up to battery assembly under an inert gas or vacuum. Not only does it have to be performed below, but it is also necessary that impurities that react with the electrolytic solution and the negative electrode to form an insulating coating are not present or substantially not present in the electrolytic solution.

However, in practice, the surface of lithium and zinc changes with time even in the electrolytic solution, so that it is difficult to strictly control the surface, and even if the above-mentioned negative electrode surface can be mirror-polished or cleaned, This will increase the manufacturing cost and can be a factor of variation in performance.

Therefore, the present inventor has further earnestly studied a simpler technique for suppressing dendrite growth. As a result, they have found that by using a negative electrode in which the protruding portion on the surface of the conductor is covered with an insulator film or a semiconductor film, dendrite growth of lithium, zinc or the like that occurs during charging can be effectively suppressed.

That is, according to the present invention, the generation and growth of dendrites due to the concentration of an electric field due to the projections or projections formed on the electrodes or the non-uniform surface state during charging and discharging are prevented by the projections or projections being formed into an insulating film or By covering with the semiconductor film, the concentration of the electric field on the outermost surface is eliminated or reduced, and the generation and growth of dendrites that cause a problem are suppressed.

The present invention also provides a method of forming an insulating film or a semiconductor film on the above-mentioned convex portions or projections of the electrode.

The "projections" and "protrusions" in the present invention are burrs at the edge of the electrode that form locally high electric field strength portions on the surfaces of the negative and positive conductors during charge and discharge. Or a convex portion or a protruding portion on the surface. The insulating film or the semiconductor film covering the protrusions is more effective in preventing dendrite growth of the negative electrode active material of lithium or zinc. The size of the protrusions depends on the radius of curvature of the protrusions and the applied voltage. According to
Generally, it is desirable that the size is about 1/100 or more of the distance between the positive electrode and the negative electrode.

[0039]

EXAMPLES FIGS. 1 (a) and 1 (b) show schematic cross-sectional views of preferred examples of negative electrodes applicable to the secondary battery of the present invention. FIG. 1A shows a conductor 100 that constitutes a negative electrode.
1 also serves as a collector electrode, and the protrusion 110 on the surface facing the positive electrode (not shown) in contact with the electrolytic solution (not shown) is covered with the insulator film or the semiconductor film 101.
(B) shows that the negative electrode protrusion 110 formed by mixing the conductive powder 100 with the conductive auxiliary agent 104 and binding it to the collector electrode 102 with the binder 103 is covered with the insulator film or the semiconductor film 101. There is something. In both cases, the surface of the conductor in the negative electrode is not completely covered with the insulator film or the semiconductor film, and there is a region where the conductor comes into contact with the electrolytic solution (in the figure, the openings between the protrusions 110). Present in the department).

FIG. 1C illustrates an example of the image when the active material 105 is deposited during charging in the pores formed in the conductor negative electrode 100 and formed in the insulator or semiconductor film 101. It is a schematic sectional view.

By charging, active material 105 is deposited on the portion of conductor 100 in contact with the electrolytic solution. If there is a protrusion 110 here, the electric field is concentrated there and the active material 105 is deposited along the lines of electric force.
Since 10 is covered with the insulator film or the semiconductor film 101, the electric field is not concentrated on the protrusion 110. The electric field is applied to the conductor 100 at the openings (bottoms of pores) between the protrusions 110.
Take Then, the active material 105 is deposited on this portion. In addition, as shown in FIG. 1C, the active material 105
When the precipitation of the active material 105 progresses, the active material 105 contacts the protrusion 110 or the insulator film of the protrusion 110 or the semiconductor film 101, so that the growth direction of the active material 105 is suppressed and the growth of dendrites is prevented or suppressed. Further, since the area where the active material 105 is in contact with the electrolytic solution is reduced, the possibility of dendrite generation is reduced.

FIG. 2 is a schematic configuration diagram of a secondary battery in which the above-mentioned negative electrode is used and a positive electrode is combined with a separator and an electrolyte. In FIG. 2, 200 is a collector electrode, 201 is a conductor whose protrusion is covered with an insulator film or a semiconductor film, 202 is a negative electrode, 203 is a positive electrode, 204 is an electrolyte (electrolyte), 205 is a separator, 206 Is the negative terminal, 20
7 is a positive electrode terminal, and 208 is a battery case.

When a secondary battery is constructed by forming at least a local electric field concentration portion such as a conductive protrusion on the surface of the negative electrode of the present invention with an insulator film or a semiconductor film, an electric field is applied during charging. At some time, electric field concentration does not occur on the protrusions and the like on the surface of the negative electrode, and as a result, the current density on the surface of the negative electrode makes the electric field uniform and suppresses the growth of dendrites such as lithium and zinc.

If the total volume of the pores formed from the conductor of the negative electrode of the present invention and the insulator film or the semiconductor film is equal to or more than the total volume of the active material deposited during charging, the active active material deposited It becomes possible to reduce the contact area with the electrolytic solution, the dendrite growth is further suppressed, and it is possible to form a secondary battery having a longer cycle life.

In the present invention, the insulator film or the semiconductor film covering at least the local electric field concentration portion such as the protrusions on the surface of the conductor constituting the negative electrode is an anodic oxide film, anodic deposition, cathodic deposition, monomer or olegomer. It is desirable that the film is formed of one or more kinds of films selected from the electrolytic polymerized film, the polymer or oxide film formed by the electrophoretic electrodeposition film.

In the present invention, the surface of the negative electrode made of at least a conductive material is subjected to at least one type of electrochemical treatment selected from anodic oxidation, anodic deposition, cathodic deposition, electrolytic polymerization, and electrophoretic electrodeposition in the treatment electrolytic solution. It is preferable to selectively form an insulator film or a semiconductor film on the protrusions on the surface of the negative electrode by using such a method.

In the above-mentioned electrochemical film forming method, since the reaction is selectively caused from the place where the electric field density is large, it is possible to form the film intensively on the protrusions of the conductor having the high electric field strength, which is relatively simple. The apparent electric field can be made uniform.

Among the above methods, in the reaction when anodizing the metal of the negative electrode conductor, the reaction of eluting the metal ions and simultaneously depositing the metal oxide film substance occurs, so that holes are formed and the specific surface area is increased. Therefore, it is more preferable as a method of covering the surface of the conductor having the local electric field concentration portion such as the protrusion with the insulator film or the semiconductor film. The fact that the negative electrode has a high specific surface area can reduce the substantial current density during charging, and can suppress dendrite growth when the active material is zinc, which is lithium.

Furthermore, by using an electrolytic solution containing a component that etches and dissolves the conductor constituting the negative electrode in the treatment electrolytic solution, an insulator or semiconductor having a large number of pores that conduct to the conductor of the negative electrode. A film can be formed on the conductor surface of the negative electrode, and when the active material is lithium or zinc, dendrite growth can be further suppressed.

Furthermore, before, after, or before or after the treatment of the negative electrode, the negative electrode surface is subjected to an etching treatment so that anodization, anodic deposition, cathodic deposition, electrolytic polymerization, or electrophoretic electrodeposition in the treated electrolytic solution can be performed. The etching treatment before the electrochemical treatment can increase the specific surface area of the negative electrode.
Increasing the specific surface area of the negative electrode lowers the substantial current density during charging, and suppresses side reactions such as dendrite growth of the active material and decomposition reaction of the battery electrolyte.

The etching treatment after the treatments of anodic oxidation, cathodic oxidation, electrolytic polymerization, and electrophoretic electrodeposition in the treatment electrolytic solution is performed by forming fine holes in the insulator film or semiconductor film that are electrically connected to the conductor forming the negative electrode. Pore volume can be increased. FIG. 1
As described in the explanation of (c), by increasing the pore volume, the reaction area of the active active material of lithium or zinc deposited during charging is reduced, and as a result, the charge / discharge cycle life is extended. Will be possible.

Further, the above-mentioned anodic oxidation, anodic (anode)
Electrochemical film forming treatments such as deposition, cathode deposition, electrolytic polymerization, electrophoretic electrodeposition, and electrochemical etching are performed in the treatment electrolyte solution between the counter electrode and the negative electrode for the secondary battery, which is the object to be treated, by applying a DC electric field. It is preferable to apply and process an electric field selected from an alternating current electric field, a pulsed electric field, and an electric field combining these. When an AC electric field is applied, it is possible to facilitate the deposition reaction for forming the insulator film or the semiconductor film, and to simultaneously perform the deposition reaction and the etching reaction, and the pores that conduct to the conductor that constitutes the negative electrode. Easier to form. In addition, when a pulsed electric field is applied, even if the resistance of the electrolytic solution is high, it becomes easy to control the formation of the insulator film or the semiconductor film on the protrusion on the negative electrode surface.

Further, in the present invention, when an aqueous solution is used for the above-mentioned electrochemical film forming treatment or etching treatment, the treated negative electrode is immersed in an organic solvent having a boiling point of 200 ° C. or less which is mixed with water to remove water in the negative electrode. After substituting with the organic solvent, it is desirable to dry under reduced pressure.

A film of a semiconductor or an insulator formed electrochemically by using an aqueous solution as the electrolytic solution is formed by adsorbing water deep inside the pores of a large number of pores. When the secondary battery in which the water content cannot be sufficiently removed and the negative electrode active material is lithium is used,
The adsorbed water reacts with lithium deposited during charging, which causes a problem that the discharge capacity decreases. The replacement treatment with the organic solvent is effective in removing the adsorbed water content of the negative electrode, and can reduce the lithium compound that cannot be eluted by discharge due to the deposition of lithium during charging of the secondary battery.

That is, by substituting the adsorbed moisture by immersing it in the above organic solvent, even if the organic solvent remains in the negative electrode pores, a reaction such as moisture and precipitated lithium is avoided, and water and an azeotropic mixture are further mixed. When the solvent to be prepared is used, the boiling point of evaporation can be made lower than the boiling point of water, so that dehydration by drying becomes easy.

Therefore, it is preferable that the organic solvent is easily removed when the negative electrode is dried, and the boiling point of the organic solvent used for the substitution treatment is preferably 200 ° C. or lower, more preferably 100 ° C. or lower. preferable.

Furthermore, after an insulator film or a semiconductor film is selectively formed on the protrusions on the negative electrode surface by an electrochemical method such as the above-mentioned anodic oxidation, cathodic oxidation, electrolytic polymerization, electrophoretic electrodeposition, etc., water repellency is obtained. It is desirable to apply treatment. This makes it possible to further reduce the adsorption of water that reacts with metallic lithium deposited during charging of the secondary battery.

(Negative Electrode) The negative electrode of the present invention has a conductor,
Examples of the conductor forming the negative electrode include aluminum, titanium, magnesium, tungsten, molybdenum, lead, silicon, germanium, zirconium, thallium, niobium, hafnium, antimony, copper, nickel and chromium,
A material composed of one or more elements selected from platinum and gold can be mentioned. Materials such as stainless steel can also be used.

The conductor has a plate shape, a foil shape,
Sponge-like, punching metal, expanded metal,
Any shape such as a mesh shape, a woven shape, a powder shape, a flake shape, and a fiber shape can be adopted. For powders, flakes, fibers, etc. that cannot retain the electrode shape as it is, they can be molded by adding a binder of inorganic glass or organic resin, or can be used by sintering them. .

In addition to the above-mentioned binder, a conductive auxiliary agent may be added to improve the current collecting property. The binder is preferably a stable electrolyte in the battery, for example,
Polytetrafluoroethylene, polyvinylidene fluoride,
Examples include polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-propylene-dienter-polymers, and the like. As the conductive auxiliary agent, carbon powder (for example, Ketjen black, acetylene black), carbon powder such as graphite, and carbon fiber can be used.

Of course, powder, flakes, fibers,
The negative electrode may be formed by applying and binding a conductor such as a plate, foil, sponge, punching metal, expanded metal, mesh, or fabric with a binder. As a coating method, methods such as screen printing, coater coating, and spray coating can be adopted.

The treatment of the negative electrode used as the negative electrode of the present invention is carried out by electrochemically treating the negative electrode formed of a conductor such as the foil or powder to form an insulator film on at least the conductive protrusions on the surface of the negative electrode. Alternatively, a semiconductor film is formed, and if necessary, an etching treatment is performed before and after the electrochemical film formation.

As the method for forming the electrochemical coating, methods such as anodic oxidation, anodic deposition, cathodic deposition, electrolytic polymerization, and electrophoretic electrodeposition as described above can be employed.

As a method of anodic oxidation, the conductor forming the negative electrode contains an element such as aluminum, titanium, magnesium, tungsten, molybdenum, lead, silicon, germanium, zirconium, thallium, niobium, hafnium or antimony. If so, the treating electrolyte is sulfuric acid, oxalic acid, phosphoric acid, chromic acid, boric acid, sulfosalicylic acid, p-phenol sulfonic acid, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium phosphate, ammonium borate, ammonium tartrate. , Aqueous solution of ammonium phosphate, malonic acid, etc. can be used,
The thickness and density of the oxide film, the pore volume and the density can be optimized by selecting the type and the solution concentration and / or by selecting the conditions for applying the electric field. Further, depending on whether a component in which the conductor is chemically dissolved is added or a treatment electrolyte is selected, it becomes easier to form pores in the coating film that are electrically connected to the base material of the conductor.

As a method for depositing an anode in the treatment electrolytic solution, an aqueous solution of a low-valent simple salt or complex such as nickel, cobalt, manganese, copper or iridium is used as the treatment electrolytic solution. And anodic oxidation,
Nickel oxide, cobalt oxide, manganese oxide, copper oxide,
A method of forming an oxide film such as iridium oxide can be used.

The method of depositing the cathode in the treatment electrolyte solution is to carry out the cathode reduction by using an aqueous solution of a high-valent oxo acid salt such as tungsten, molybdenum, vanadium, etc. in the treatment electrolyte solution. Then, a method of forming an oxide film of tungsten oxide, molybdenum oxide, vanadium oxide, or the like can be employed.

The electrolytic polymerization method is a method in which a monomer or an olegomer is added to a treated electrolytic solution and an electric field is applied to form a polymerized film. The addition of a monomer or olegomer that renders the polymer coating electrically conductive is usually not suitable, but can be applied if the electrical conductivity is sufficiently low. Examples of the added monomer include dibenzocrown ether and furan. The electrolytic solution used for the electrolytic polymerization may be the electrolytic solution used for lithium batteries.

As the electrophoretic electrodeposition method, a polymer solution for an electrodeposition coating which is usually used for electrodeposition coating or a sol solution of an inorganic oxide added with a surfactant can be used. In order to selectively form a coating film on the protrusions on the surface of the negative electrode, the concentrations of the electrolytic solution and the additive and the conditions for electrolytic application may be appropriately selected.

When the negative electrode active material is lithium and an active material containing a lithium element is used as the positive electrode active material, the negative electrode produced by the above method may be used as it is. Even if there is no lithium in the negative electrode, lithium from the positive electrode active material is deposited by charging and functions as a negative electrode active material. When an active material containing no lithium element is used as the positive electrode active material, lithium is mixed with a conductor to form the negative electrode, or a lithium alloy is used as the conductor of the negative electrode.

When the negative electrode active material is zinc, the negative electrode previously formed by the above method is electrochemically plated with zinc and the negative electrode deposited is used, or the negative electrode is prepared by mixing zinc with a conductor. It may be formed or a zinc alloy may be adopted as the conductor of the negative electrode.

(Etching Treatment) The etching treatment of the negative electrode of the present invention is carried out before the electrochemical coating forming treatment such as anodic oxidation in the electrolytic solution, anodic deposition, cathodic deposition, electrolytic polymerization, electrophoretic electrodeposition. Has the effect of increasing the specific surface area. Further, in the etching process after the electrochemical film forming process, there is an effect of increasing the volume of pores opened in the insulator or the semiconductor film which is electrically connected to the conductor forming the negative electrode.

As the etching method, methods such as chemical etching, electrochemical etching, plasma etching and the like can be preferably adopted.

In the chemical etching, etching is performed by reacting with acid or alkali. The following are specific examples.

For example, when the conductor forming the negative electrode is aluminum, the etching solution is an acid such as phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, acetic acid, potassium hydroxide, sodium hydroxide, Bases such as lithium hydroxide and ethylenediamine, and mixed solutions thereof are used. A dilute acid such as nitric acid is used as an etching solution when the conductor forming the negative electrode is nickel. When the conductor forming the negative electrode is copper, an organic acid such as sulfuric acid, hydrochloric acid, nitric acid or acetic acid, a cupric chloride solution, a ferric chloride solution, or ammonia water can be used as the etching solution. When the conductor forming the negative electrode is titanium, hydrofluoric acid, phosphoric acid, or the like can be used as the etching solution.

In the electrochemical etching, an electric field is applied between counter electrodes in an electrolytic solution to electrochemically elute it as metal ions. When the conductor forming the negative electrode is aluminum, a mixed solution of phosphoric acid, sulfuric acid and chromic acid is used as the electrolytic solution. A phosphoric acid solution or the like can be used as an etching solution when the conductor forming the negative electrode is copper.

Plasma etching is a method in which an etching gas is turned into plasma and reactive ions and radicals are reacted to perform etching. As the raw material etching gas, tetrachloromethane, tetrafluoromethane, chlorine, trichloromonofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, or the like can be used.

(Water repellent treatment) After the insulator film or the semiconductor film is formed on the protrusions on the surface of the negative electrode by the electrochemical film forming method, the water repellent treatment is applied to reduce the adsorption of water. preferable. As a method of water repellent treatment, in addition to a method of coating a fluororesin by coating, plasma coating, or sputtering, a solution in which a fluororesin olegomer and a surfactant are dispersed in a plating solution of a metal salt is used. The method of electrolytic plating or chemical (electroless) plating can be preferably adopted.

(Negative Electrode Surface Coating) By coating the surface of the negative electrode of the battery of the present invention with a film of an insulating film or a semiconductor film which selectively permeates lithium ions and does not permeate precipitated lithium metal, during charging. The effect of suppressing the generation of dendrites can be further enhanced.

As a material for coating the surface of the negative electrode of the present invention, a material having a narrow mouth or a molecular structure capable of transmitting lithium ions is used. Examples of those having a molecular structure capable of penetrating lithium ions include polymers having a structure of a large crown ether, a structure having an ether bond, and the like. As a method of positively producing a fine mouth through which lithium ions can pass, a foaming agent or a material that is easily pyrolyzed is prepared by mixing a coating solution for the coating material with a material such as an electrolyte salt that can be eluted after forming the coating film. It is possible to adopt a method of preparing a narrow mouth by mixing the above.

(Positive Electrode) The positive electrode usually has a positive electrode active material and, if necessary, a current collector, a conductive auxiliary agent, a binder and the like. For example, a positive electrode active material, a conductive auxiliary agent, a binder and the like are mixed and molded on a current collector. The conductive additive used for the positive electrode is powdery or fibrous aluminum,
Copper, nickel, stainless steel, graphite, or amorphous carbon such as carbon black (eg Ketjen black, acetylene black) can be used.

The binder is preferably one which is stable in the electrolytic solution. For example, when the electrolytic solution is a non-aqueous solvent system, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene. Fluorine resins such as diene terpolymers and polyolefins. When the electrolytic solution is an aqueous solution, polyvinyl alcohol, cellulose, polyamide or the like can be used.

The current collector has a role of supplying a current that is efficiently consumed by the electrode reaction during charging / discharging or collecting a current that is generated. Therefore, a material having high electric conductivity and inert to the battery reaction is desirable. Preferable materials include nickel, titanium, copper, aluminum, stainless steel, platinum, palladium, gold, zinc, various alloys, and composite metals of two or more of the above materials.
As the shape of the current collector, a plate shape, a foil shape, a mesh shape, a sponge shape, a fiber shape, a punching metal, an expanded metal, or the like can be adopted.

(Positive Electrode Active Material When Negative Electrode Active Material is Lithium) In a battery in which the negative electrode active material is lithium, the positive electrode active material is
A transition metal oxide or a transition metal sulfide containing a lithium element is preferably used. The transition metal element of the transition metal oxide or the transition metal sulfide is an element partially having a d-shell or f-shell, and is Sc, Y, a lanthanoid, an actinide, Ti, Zr, Hf, V, Nb, Ta, Cr. , Mo,
W, Mn, Tc, Re, Fe, Ru, Os, Co, R
h, Ir, Ni, Pd, Pt, Cu, Ag and Au are used. Mainly, Ti, V, Cr, M of the first transition series metals
Preference is given to using n, Fe, Co, Ni, Cu.
In order to contain lithium in the positive electrode active material, a lithium compound may be prepared by reacting the transition metal oxide or the transition metal sulfide during preparation.

(Positive Electrode Active Material When Negative Electrode Active Material is Zinc)
In a nickel-zinc battery in which the negative electrode active material is zinc, it is preferable to use nickel oxide hydroxide as the positive electrode active material. In an air zinc battery in which the negative electrode active material is zinc, the positive electrode active material is oxygen, and the positive electrode usually has a current collector, a catalyst, and a water repellent material.
Porous carbon, porous nickel, copper oxide, etc. are used for the catalyst. As the water repellent material, a fluororesin such as a porous tetrafluoroethylene resin is used.

In a zinc bromine battery in which the negative electrode active material is zinc, bromine is used as the positive electrode active material.

(Separator) The separator has a role of preventing a short circuit between the negative electrode and the positive electrode. It may also have a role of holding the electrolytic solution. Since the separator has pores through which ions involved in the battery reaction such as lithium ions and hydroxide ions can move, and is required to be insoluble and stable in the electrolyte solution in the battery, glass, polypropylene,
A non-woven fabric such as polyethylene, fluororesin or polyamide, or a material having a micropore structure is used. Further, a metal oxide film having fine pores or a resin film in which a metal oxide is composited can also be used. Especially when using a metal oxide film having a multilayer structure,
Dendrite is less likely to penetrate and is effective in preventing short circuits. When a fluororesin film which is a flame retardant material or a glass or metal oxide film which is a nonflammable material is used, the safety can be further enhanced.

(Electrolyte) In addition to the case where the electrolyte is used as it is, a solution in which a solvent is dissolved and a gelling agent such as a polymer is added and immobilized can be used. Generally, an electrolyte solution obtained by dissolving an electrolyte in a solvent is used by holding it in a porous separator.

The higher the conductivity of the electrolyte, the more preferable, and the conductivity at least at 25 ° C. is 1 × 10 ⁻³ S / cm.
It is desirable that it is at least 5 × 10 ⁻³ S / cm, and more desirably at least 5 × 10 ⁻³ S / cm.

(When the negative electrode active material is lithium) The electrolyte is an acid such as H ₂ SO ₄ , HC 1 or HNO ₃ , lithium ion (Li ⁺ ) and Lewis acid ion (SF ₄ −, PF _{6).
-, ClO 4 -, CF 3} SO 3 -, BPh 4 - (Ph:
Preference is given to using salts consisting of phenyl groups)) and mixed salts thereof. In addition to the above supporting electrolyte, a salt of a cation such as sodium ion, potassium ion, tetraalkylammonium ion and Lewis acid ion can also be preferably used. It is desirable that the above salt be sufficiently dehydrated and deoxidized by heating under reduced pressure.

As a solvent for the electrolyte, acetonitrile,
Benzonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, dimethylformamide, tetrahydrofuran, nitribenzene, dichloroethane, diethoxyethane,
1,2-dimethoxyethane, chlorobenzene, γ-butyrolactone, dioxolane, sulfolane, nitromethane, dimethyl sulfide, dimethylsulfoxide, dimethoxyethane, methyl formate, 3-methyl-2-oxazolidinone, 2-methyltetrahydrofuran, 3-propylsydnone , Sulfur dioxide, phosphoryl chloride, thionyl oxide, sulfuryl chloride, and the like, and mixtures thereof can be preferably used.

The above solvent is dehydrated with activated alumina, molecular sieve, phosphorus pentoxide, calcium chloride or the like, or depending on the solvent, the removal of impurities and dehydration are also carried out by distillation in the presence of an alkali metal in an inert gas. Is good.

Gelation is preferable in order to prevent leakage of the electrolytic solution. As the gelling agent, it is desirable to use a polymer that absorbs the solvent of the electrolytic solution and swells,
Polymers such as polyethylene oxide, polyvinyl alcohol and polyacrylamide are used.

(When the negative electrode active material is zinc) As the electrolyte, alkalis such as potassium hydroxide, sodium hydroxide, lithium hydroxide and salts such as zinc bromide are used.

Gelation is preferable in order to prevent leakage of the electrolytic solution. As the gelling agent, it is desirable to use a polymer that absorbs the solvent of the electrolytic solution and swells,
Polymers such as polyethylene oxide, polyvinyl alcohol and polyacrylamide, and starch are used.

(Battery Shape and Structure) Actual battery shapes include flat type, cylindrical type, rectangular parallelepiped type and sheet type batteries. In the spiral cylindrical structure, the electrode area can be increased by winding a separator between the negative electrode and the positive electrode, and a large current can be flowed during charging and discharging. Further, in the rectangular parallelepiped shape, the storage space of the device that stores the secondary battery can be effectively used. As for the structure, there are structures such as a single layer type and a multilayer type.

FIG. 3 is an example of a schematic sectional view of a single-layer flat type battery, and FIG. 4 is a schematic sectional view of a spiral structure cylindrical battery. FIG.
4, reference numeral 300 denotes a negative electrode current collector, 301 denotes a negative electrode active material, 303 denotes a positive electrode active material, 304 denotes a positive electrode current collector, 30
5 is a negative electrode terminal (negative electrode cap), 306 is a positive electrode can, 30
7 is electrolyte and separator, 310 is insulating packing,
311 is an insulating plate.

As an example of assembling the battery shown in FIGS. 5 and 6,
After the separator 307 is sandwiched between the negative electrode active material 301 and the molded positive electrode active material 303, and the electrolyte is injected into the positive electrode can 306, the negative electrode cap 305 and the insulating packing 31 are inserted.
0 is assembled and caulked to produce a battery.

Preparation of the material for the lithium battery and assembly of the battery prevent the reaction between water and lithium, and
It is desirable to carry out in dry air from which water is sufficiently removed or in a dry inert gas in order to prevent deterioration due to the reaction of water and lithium inside the battery.

(Insulating packing) Insulating packing 310
As a material for the above, any sealing material having an insulating property may be used, and a fluororesin, a polyamide resin, a polysulfone resin, various rubbers and the like can be preferably used. As the sealing method, in addition to caulking using a gasket such as an insulating packing as shown in FIGS. 3 and 4, a method such as a glass sealing tube, an adhesive, welding, and soldering is preferably used.

Various organic resin materials and ceramics are preferably used as the material of the insulating plate of FIG.

(Outer can) As the material of the positive electrode can 306 and the negative electrode cap 305 of the actual battery, stainless steel,
Particularly, Tilan-clad stainless steel, copper-clad stainless steel, nickel-plated steel plate and the like are preferably used.

In FIGS. 3 and 4, the positive electrode can 306 also serves as a battery case, but as the material of the battery case, metal such as zinc other than stainless steel, plastic such as polypropylene, or metal or glass fiber and plastic is used. The composite material of can be preferably used.

(Safety valve) Although not shown in FIGS. 3 and 4, as a safety measure when the internal pressure of the battery rises for some reason, the elastic pressure of rubber, spring, etc. for lowering the internal pressure of the battery is used. It is desirable to provide a safety valve that uses the body, metal balls, ruptured foil, etc. for communication with the outside.

The present invention will be described in detail below based on examples. The present invention is not limited to these examples.

(Example 1) A lithium secondary battery having a schematic sectional structure shown in FIG.

First, 50 having a maximum surface roughness of 0.8 μm is used.
A micron-thick aluminum foil is immersed in an aqueous solution of phosphoric acid: nitric acid: acetic acid: water = 20: 1: 2: 2 for etching, and then a direct current voltage of 20 V is applied in a 56% by weight (wt)% sulfuric acid aqueous solution. After anodic oxidation, the resultant was subjected to etching treatment with an aqueous potassium hydroxide solution, followed by washing with water, replacing water in the negative electrode with acetone and isopropyl alcohol to remove water, and then drying under reduced pressure for 3 hours to prepare a negative electrode.

As the positive electrode active material, electrolytic manganese dioxide and lithium were mixed at a ratio of 1: 0.4, and then 800 ° C.
The mixture was heated to prepare a lithium-manganese oxide. The prepared lithium-manganese oxide was mixed with 3 wt% of acetylene black carbon powder and 5 wt% of polyvinylidene fluoride powder and N-methylpyrrolidone was added to prepare a paste, which was then applied to an aluminum foil and dried to form a positive electrode. did.

As the electrolytic solution, ethylene carbonate (EC) and dimethyl carbonate (D
A solvent obtained by dissolving lithium tetrafluoroborate salt IM (mol / l) in an equal amount mixed solvent of NC) was used.

As the separator 307, a polypropylene microporous separator having a thickness of 25 μm was used.

Assembly was carried out in a dry argon gas atmosphere,
A separator 307 is sandwiched between the negative electrode and the positive electrode, inserted into a titanium-clad stainless steel positive electrode can 306, and an electrolytic solution is injected therein, and then sealed with a titanium-clad stainless steel negative electrode cap 305 and a fluororubber insulating packing 310. Then, a lithium secondary battery was produced.

Upon charging, the lithium in the positive electrode moves and deposits on the negative electrode to become a negative electrode active material.

Using the copper decoration method, the aluminum foil used for the negative electrode prepared by the above procedure was applied to the negative electrode as a negative electrode, and a DC voltage was applied in an aqueous solution of copper sulfate to apply copper on the negative electrode. Was deposited. SEM the surface of the negative electrode on which copper was deposited with a scanning micro auger measuring device
(Scanning electron microscope) When the image and copper element were mapped and observed, copper was not deposited on the convex portion of the surface, and copper was selectively selected only in the concave portion which seems to be conductive to the aluminum body. It was observed that precipitation had occurred. Thus, copper was selectively deposited only on the conductor portion on the surface-treated aluminum surface. Therefore, from the observation result of the scanning micro Auger, it can be said that a film having a low electric conductivity is formed on the convex portion of the aluminum surface.

Example 2 A negative electrode was manufactured by the following procedure. A lithium secondary battery was made in the same manner as in Example 1 except for the above.

50% -50% nickel-aluminum alloy powder was mixed with 5% by weight of polyvinyl alcohol powder, and N-
A paste prepared by adding methylpyrrolidone was applied on a nickel foil having a thickness of 30 μm to a thickness of 50 μm, dried, and then fired at 650 ° C. under a hydrogen flow. Next, an AC pulse of 20 V is applied in a 5 wt% aqueous solution of potassium hydroxide containing 1 wt% of hydrogen peroxide, followed by anodic oxidation, washing with water, drying, and replacement of water in the negative electrode with acetone and isopropyl alcohol, followed by depressurization. A negative electrode was prepared by drying.

Further, in the same manner as in Example 1, copper was deposited on the negative electrode prepared by the above procedure using the copper decoration method, and an SEM image was obtained using the scanning micro-Auger measuring device in the same manner as the surface thereof. At the same time, the distribution of copper was measured. As a result, in this case as well, it was found that a film having a low electric conductivity was formed on the convex portion on the surface of the negative electrode, and pores that were electrically connected to the nickel-aluminum alloy powder of the negative electrode were present.

Example 3 A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode was produced by the following procedure.

A paste prepared by mixing 60 wt% of aluminum powder, 35 wt% of magnesium powder and 5 wt% of polyvinyl alcohol powder and adding N-methylpyrrolidone to a copper foil of 35 μm in thickness of 50 μm was dried. Calcination at 600 ° C. under hydrogen flow. next,
A DC pulse of 30 V was applied in a 23 wt% sulfuric acid aqueous solution to perform anodic oxidation, washing with water, drying, and replacement of water in the negative electrode with acetone and isopropyl alcohol, followed by vacuum drying to prepare a negative electrode.

Further, the copper decoration method was applied in the same manner as in Example 1, and the results of measurement using a scanning micro Auger measuring apparatus revealed that a film having a low electric conductivity was formed on the convex portion on the surface of the negative electrode, and the aluminum powder of the negative electrode was formed. It was also found that there are pores that communicate with the magnesium powder.

Example 4 A titanium foil having a thickness of 50 μm was immersed in an aqueous solution of hydrofluoric acid = 1: 19 for etching, and then subjected to direct current in a 6 wt% sulfuric acid aqueous solution containing 1 wt% of hydrofluoric acid. A voltage of 20 V was applied to carry out anodization, followed by washing with water, replacing water in the negative electrode with acetone, and drying under reduced pressure to prepare a negative electrode, and in the same manner as in Example 1,
A lithium secondary battery was produced.

Further, as in Example 1, the negative electrode was subjected to the copper decoration method, and the measurement result by the scanning micro Auger measuring device showed that a film having a low electric conductivity was formed on the convex portion of the surface of the negative electrode of the titanium foil. It was found that the titanium foil had pores that were electrically connected.

(Embodiment 5) An aluminum foil having a maximum surface roughness of 0.8 micron and a thickness of 50 micron was applied in an aqueous solution of 20 wt% nickel nitrate at an alternating voltage of 40 V to form an anode when the aluminum foil became an anode. After the oxide and the aluminum oxide were deposited, they were washed with water and dried, then subjected to an etching treatment with a 5 wt% potassium hydroxide aqueous solution and then washed with water, and after replacing water in the negative electrode with acetone and isopropyl alcohol, they were dried under reduced pressure. A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode was prepared in the same manner as in Example 1.

Further, the copper decoration method was applied in the same manner as in Example 1, and the results of measurement by a scanning micro Auger measuring apparatus revealed that a film having a low electric conductivity was formed on the convex portion of the surface of the aluminum foil negative electrode, and the aluminum foil of the negative electrode was formed. It was found that there are pores that are connected to.

Example 6 A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode was produced by the following procedure.

An aluminum foil having a maximum surface roughness of 0.8 μm and a thickness of 50 μm was etched with a 5 wt% potassium hydroxide aqueous solution, washed with water, replaced with acetone and isopropyl alcohol to replace water in the negative electrode, and then dried under reduced pressure. . Then the monomer dibenzo-18-crown-6
Of 0.1 M (mol / l) and 0.2 M of tetrabutylammonium tetrafluoroammonium tetrafluoride salt as an electrolyte were soaked in an etched aluminum foil, and a platinum electrode was used as a cathode electrode for a pulse voltage of 3 V. Was applied to form a coating film of macrocyclic compound polymer by electrolytic polymerization, washed with acetonitrile, and dried under reduced pressure to prepare a negative electrode.

Also, the negative electrode was subjected to the copper decoration method in the same manner as in Example 1, and the result of the scanning micro Auger measurement device showed that a film having a low electric conductivity was formed on the convex portion on the surface of the negative electrode of the aluminum foil described above. It was found that there were pores that were conducting in the foil.

Example 7 A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode was produced by the following procedure.

The surface of an aluminum foil having a maximum surface roughness of 0.8 μm and a thickness of 50 μm was etched and washed with a 5 wt% potassium hydroxide aqueous solution, and then a DC voltage of 20 V was applied in a 56 wt% sulfuric acid aqueous solution. It was anodized, washed with water and dried. Then, add perfluoroalkyltrimethylammonium salt and tetrafluoroethylene olegomer to a nickel plating solution of nickel sulfate-nickel chloride-boric acid aqueous solution, immerse the anodized aluminum foil on the surface, and apply a DC voltage to the counter electrode of nickel. Then, nickel plating and water-repellent treatment were performed at the same time, and after washing with water and drying, the water content in the negative electrode was replaced with acetone and isopropyl alcohol, and the negative electrode was dried under reduced pressure to prepare a negative electrode.

From the observation result of the prepared negative electrode using a scanning micro Auger measuring apparatus, a film having a low electric conductivity was formed on the convex portion of the surface of the above-mentioned aluminum foil negative electrode, and nickel fine particles were formed in the pores conducting to the aluminum foil of the negative electrode. It was found that there was something that looked like a fluororesin.

Example 8 A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode was produced by the following procedure.

An aluminum foil having a maximum surface roughness of 0.8 μm and a thickness of 50 μm was immersed in a 56 wt% sulfuric acid aqueous solution.
A DC voltage of 20 V was applied to carry out anodization, washing with water and drying under reduced pressure to prepare a negative electrode.

Further, the negative electrode was subjected to the copper decoration method in the same manner as in Example 1, and from the results of the copper distribution and the SEM image using the scanning micro-Auger measurement result, the conductivity of the convex portion on the surface of the negative electrode of the aluminum foil was confirmed. It was found that a low film was formed and that there were pores that were conducting in the aluminum foil of the negative electrode.

In the positive electrode active materials of Examples 1 to 8, one type of lithium-manganese oxide was used to evaluate the performance of the negative electrode, but the present invention is not limited to this, and lithium-nickel oxide is used. Thing, lithium-cobalt oxide,
Various positive electrode active materials can also be adopted.

Further, regarding the electrolytic solution, Examples 1 to 8 were used.
However, the present invention is not limited to this.

(Example 9) A nickel-zinc secondary battery having a schematic sectional structure shown in FIG.

For the positive electrode, nickel powder was added to nickel hydroxide, and carboxymethyl cellulose as a binder and water were added to prepare a paste, which was filled in a nickel foam (Celmet manufactured by Sumitomo Electric Industries, Ltd.). It was dried, pressed and produced.

The negative electrode has a maximum surface roughness of 0.5 μm and is 50 μm.
After the surface of a micron-thick titanium foil was first etched with hydrofluoric acid, ammonium borate was used as an electrolytic solution to anodize glassy carbon at a counter electrode of 20 V, and the anodized titanium foil was prepared by washing and drying. , An aqueous solution of zinc and sodium hydroxide (zincate bath) is used as an electrolyte, and zinc is anodized at a current density of 2.5 A / dm ² using zinc as the anode and the previously prepared anodized titanium foil as the cathode. Prepared by applying to the foil surface.

The electrolytic solution was 30 w to which lithium hydroxide was added.
A t% aqueous potassium hydroxide solution was used.

As the separator, a microporous polypropylene film (25 μm thick) that had been subjected to water immersion treatment was used.

Assembling was carried out by inserting a titanium clad stainless steel battery case through a separator between the negative electrode and the positive electrode and injecting an electrolytic solution, and then a titanium clad stainless steel negative electrode cap and an insulating packing of fluororubber. Then, a nickel-zinc secondary battery was manufactured.

From the results of zinc distribution and SEM image using a scanning micro auger measuring device, a film having low electric conductivity was formed on the convex portion of the negative electrode surface, and zinc was introduced into the pores conducting to the titanium foil of the negative electrode. It turned out to exist.

Example 10 In this example, a zinc-air secondary battery was prepared. The positive electrode was made by mixing acetylene black with manganese dioxide, nickel oxide, cobalt oxide, and tetrafluoroethylene polymer powder, and adding a powdery fluororesin paint Super Konak 5 wt% xylene solution made by NOF Corporation into a paste. It was applied to a plated copper mesh, cured at 170 ° C., and then molded through a pressure heater roller.

The negative electrode prepared in the same manner as in Example 9 was used as the negative electrode.

For assembly, a cellophane separator was interposed between the negative electrode and the positive electrode, and the battery was inserted into a battery case (positive electrode side) made of titanium-clad stainless steel material and injected with an electrolytic solution. The negative electrode cap was sealed with an insulating packing of fluororubber to prepare an air zinc secondary battery.

Comparative Example 1 A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode of Example 1 was replaced with an aluminum foil having a maximum surface roughness of 0.8 μm.

The negative electrode was subjected to the copper decoration method in the same manner as in Example 1, and from the results of the SEM image and the copper distribution obtained by using a scanning micro Auger measuring apparatus, copper was deposited on the entire aluminum surface of the negative electrode, It was found that copper was thickly deposited on the convex portions on the surface.

Comparative Example 2 A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode of Example 1 was replaced by an aluminum foil manufactured by Japan Condenser Industry Co., Ltd., the surface of which was only subjected to etching treatment.

Further, as in Example 1, the negative electrode was subjected to the copper decoration method, and from the results of the copper distribution and the SEM image by the scanning micro auger measuring device, copper was deposited on the entire surface of the negative electrode, and the protrusions on the surface were more It was found that copper was thickly deposited. This result was more remarkable than in Comparative Example 1.

(Comparative Example 3) A lithium secondary battery was produced in the same manner as in Example 1 except that the negative electrode formed by sintering in Example 2 was not anodized.

(Comparative Example 4) A lithium secondary battery was produced in the same manner as in Example 3 except that the sintered negative electrode of Example 3 was not anodized.

(Comparative Example 5) A lithium ion battery was produced in the same manner as in Example 1 except that the flafitite negative electrode produced by the following procedure was used instead of the negative electrode of Example 1.

The graphite negative electrode was prepared by subjecting natural graphite powder to heat treatment at 2000 ° C. under argon gas, and then adding 3% by weight (wt) of acetylene black to the natural graphite powder.
Was mixed with 5 wt% of polyvinylidene fluoride powder and N-methylpyrrolidone was added to prepare a paste, which was then applied to a copper foil having a thickness of 35 microns to a thickness of 75 microns and dried under reduced pressure at 150 ° C.

Comparative Example 6 A lithium secondary battery was prepared in the same manner as in Example 1 except that a titanium foil having a maximum surface roughness of 0.5 μm, which had been washed, was used in place of the negative electrode of Example 4 without anodizing. A battery was made.

Comparative Example 7 The surface of a titanium foil having a maximum surface roughness of 0.5 μm, which had been washed in place of the negative electrode of Example 9, was plated with zinc in the same manner as in Example 9 without anodizing. A nickel-zinc secondary battery was produced in the same manner as in Example 9 except that the produced negative electrode was used.

(Comparative Example 8) Instead of the negative electrode of Example 10,
A zinc-air secondary battery was produced in the same manner as in Example 10 except that a zinc electrode plate obtained by mixing tetrafluoroethylene polymer powder with zinc oxide and metallic zinc and then press-molding the copper mesh was used.

(Evaluation of Performance of Secondary Battery) The performance of secondary batteries produced in Examples and Comparative Examples was evaluated by performing a charge / discharge cycle test under the following conditions.

The conditions of the cycle test were a charge / discharge of 0.5 C (0.5 times the capacity / hour) based on the electric capacity calculated from the amount of the positive electrode active material, and a break time of 30 minutes.
Hokuto Denko HJ-106M was used for the battery charging / discharging device. The charge / discharge test was started from charging, the battery capacity was the third discharge amount, and the cycle life was the number of cycles below 60% of the battery capacity. In the case of a lithium battery, a charge cutoff voltage of 4.5V, a discharge cutoff voltage of 2.5V, and in the case of a nickel zinc battery and an air zinc battery, a charge cutoff voltage of 2.0V and a discharge cutoff voltage of 0V. It was set to 0.9V.

Table 1 shows the results of comparative evaluation of the cycle life performance of the batteries of Examples and Comparative Examples produced using the present invention. Table 2 shows the energy density ratio per unit volume of the secondary battery of the present invention of the example and the secondary battery of the comparative example 5.

As described above, from Table 1, when the secondary battery using the negative electrode of the present invention is adopted, the cycle life is longer than that in the case where the negative electrode in which the insulator or the semiconductor is not formed at least on the protruding portion of the negative electrode is adopted. I found it to grow. Further, from Table 2, Example 1 had a cycle life of 10% shorter than that of Comparative Example 5, but had an energy density of 30% higher,
It was found that the other secondary batteries using the negative electrode of the present invention can obtain energy density of 20 to 60% higher than that of the lithium ion battery using the carbon negative electrode. Therefore,
By applying the present invention, it has been found that a secondary battery having a high energy density and a long cycle life can be manufactured.

[0159]

[Table 1]

[0160]

[Table 2]

Further, comparison was made between Example 1 and Comparative Example 1, Example 2 and Comparative Example 3, Example 3 and Comparative Example 4, Example 4 and Comparative Example 6, Example 9 and Comparative Example 7, and Example 10. When the energy densities of Example 8 were compared, the results shown in Table 3 were obtained.

As can be seen from Table 3, the energy density was high in any case using the negative electrode having the insulator or semiconductor in the convex portion of the negative electrode.

[0163]

[Table 3]

[0164]

As described above, according to the present invention, there are provided a secondary battery having a high energy density and a long cycle life, and a manufacturing method thereof.

Further, according to the present invention, there is provided a secondary battery having a simple structure of the battery, a complicated manufacturing method and procedure, excellent workability, low cost and high reliability, and a manufacturing method thereof. Provided.

Further, the present invention is produced by the concentration of an electric field,
Provided are a secondary battery that can suppress the generation and growth of dendrites that reduce the life of the battery and the capacity thereof, and have less variation in performance, and a method for manufacturing the secondary battery.

Further, according to the present invention, it is possible to suppress the growth of dendrite, which is the cause of the performance deterioration that occurs during charging of the secondary battery, and has a long life and high energy density, a lithium secondary battery, a nickel zinc secondary battery, Secondary batteries such as an air zinc secondary battery and a bromine zinc secondary battery can be manufactured.

It is needless to say that the present invention is not limited to the above embodiments and description, and can be appropriately modified and combined within the scope of the gist of the present invention.

[Brief description of drawings]

1A and 1B are schematic cross-sectional views each illustrating a preferred example of a negative electrode of the present invention, and FIG. 1C is a schematic cross-sectional view of an active material deposited on the negative electrode of the present invention. 3 is a schematic cross-sectional view of FIG.

FIG. 2 is a schematic configuration diagram for explaining an example of a schematic configuration of a secondary battery of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining a preferred configuration example of a single-layer flat battery.

FIG. 4 is a schematic cross-sectional view for explaining a suitable configuration example of a spiral structure cylindrical battery.

5A and 5B are schematic cross-sectional views for explaining an example of a state of lines of electric force to a negative electrode.

[Explanation of symbols]

100 Conductor 101 Insulator Film or Semiconductor Film 102 Current Collecting Electrode 103 Binder 104 Conductive Aid 105 105 Active Material 110 Projection (Protrusion) 200 Current Collecting Electrode 201 Projection is Covered with Insulator Film or Semiconductor Film Conductor 202 Negative electrode 203 Positive electrode 204 Electrolyte 205 Separator 206 Negative electrode terminal 207 Positive electrode terminal 208 Battery case 300 Negative electrode current collector 301 Negative electrode active material 303 Positive electrode active material 304 Positive electrode current collector 306 Positive electrode can 307 Electrolyte and separator 310 Insulating packing 311 Insulation plate 500 Conductor Negative Electrode 501 Projection 502 Positive Electrode 503 Insulator Film

Front page continuation (72) Inventor Masaya Asao 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (22)

[Claims] 1. A secondary battery comprising a negative electrode, a positive electrode provided via the negative electrode and a separator, and an electrolyte provided in contact with the negative electrode and the positive electrode, wherein a conductor of the negative electrode. A secondary battery characterized in that the protruding portion of is covered with at least an insulator or a semiconductor. 2. The secondary battery according to claim 1, wherein the total volume of the holes formed by the conductor of the negative electrode and the insulating film or the semiconductor is not less than the total volume of the battery active material deposited during charging. 3. The insulator or semiconductor covering the protrusion of the conductor of the negative electrode is a metal anodic oxide film.
The secondary battery described. 4. The insulator or semiconductor covering the projection of the conductor of the negative electrode is a metal cathodic oxide film.
The secondary battery according to. 5. The method according to claim 1, wherein the insulator or semiconductor covering the protrusions of the conductor of the negative electrode is an electropolymerized film of a monomer or an olegomer, or a polymer or oxide film formed by electrophoretic deposition. Next battery. 6. The negative electrode conductor is one or more elements selected from aluminum, titanium, magnesium, tungsten, molybdenum, lead, silicon, germanium, zirconium, thallium, niobium, hafnium, antimony, copper, nickel and chromium. The secondary battery according to claim 1, further comprising: 7. The negative electrode active material involved in the charge / discharge reaction of the secondary battery is lithium.
The secondary battery according to item. 8. The secondary battery according to claim 1, wherein the positive electrode active material forming the positive electrode contains a lithium element. 9. The secondary battery according to claim 1, wherein the negative electrode active material of the secondary battery is zinc. 10. A method of manufacturing a secondary battery comprising a negative electrode, a positive electrode provided with the negative electrode via a separator, and an electrolyte provided between the negative electrode and the positive electrode, wherein at least a conductor of the negative electrode. The material surface is anodized, anodized, cathodically deposited, electrolytically polymerized, or electrophoretic electrodeposited in an electrolytic solution using one or more electrochemical methods to form an insulator or A method of manufacturing a secondary battery, comprising the step of forming a semiconductor. 11. The method for manufacturing a secondary battery according to claim 10, further comprising the step of forming an insulator or a semiconductor on a protrusion on the surface of the conductor and then etching the conductor. 12. The method according to claim 10, further comprising the step of etching an anode surface made of the conductor material and then forming an insulator or a semiconductor on the protrusion of the conductor surface.
A method for manufacturing a secondary battery according to 1. 13. The method of manufacturing a secondary battery according to claim 12, wherein the negative electrode having an insulator or a semiconductor formed on the protrusion on the surface of the conductor is further subjected to etching treatment. 14. The method for producing a secondary battery according to claim 10, wherein the electrolytic solution used in the electrochemical method contains a component that dissolves a conductor forming the negative electrode. 15. The etching is chemical etching,
The method for manufacturing a secondary battery according to claim 11, further comprising a step using one or more kinds of etching methods selected from electrochemical etching and plasma etching. 16. The electrochemical method applies at least one electric field selected from the group consisting of a DC electric field, an AC electric field, and a pulse electric field between a counter electrode and the conductive material in an electrolytic solution. 10. The method for manufacturing a secondary battery according to item 10. 17. The method for manufacturing a secondary battery according to claim 10, wherein the electrolytic solution used in the chemical method is an aqueous solution. 18. After the step of using the chemical method,
The method for manufacturing a secondary battery according to claim 10 or 17, further comprising the step of immersing at least the conductor in an organic solvent having a boiling point of 200 ° C or less that is mixed with water and then drying under reduced pressure. 19. After the step of forming an insulator film or a semiconductor film on the protrusions on the surface of the conductor by the electrochemical method,
The method for manufacturing a secondary battery according to claim 10, further comprising a step of applying a water repellent treatment. 20. The electrochemical etching applies at least one electric field selected from the group consisting of a DC electric field, an AC electric field, and a pulsed electric field between a counter electrode and a conductor material in an electrolytic solution. 15. The method for manufacturing a secondary battery according to item 15. 21. The method for manufacturing a secondary battery according to claim 15, wherein the electrolytic solution for electrochemical etching is an aqueous solution. 22. After the electrochemical etching, there is a step of immersing at least the conductor in an organic solvent having a boiling point of 200 ° C. or lower, which is mixed with water, and then dried under reduced pressure.
22. The method for manufacturing a secondary battery according to 5 or 21.