JPH06310174A - Lithium secondary battery and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a battery whose cyclic life is long by processing the surface of a negative electrode faced to a positive electrode with a specified compound. CONSTITUTION:When the surface of a negative electrode current collector 100 containing negative electrode active material, which is faced to a positive electrode current collector 103 containing at least, positive electrode active material 104, is processed by a compound containing hydroxyl group or carboxyl group, the dendrite growth of lithium at the time of charging is controlled so as to allow a negative electrode to be restrained from being shortcircuited to a positive electrode, so that a battery can thereby be obtained, the cyclic life of charge/discharge of which is long. Moreover, metallic lithium can be used as negative electrode active material, and the battery high in energy density can thereby be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery using lithium as a negative electrode. In particular, the present invention relates to a long-life lithium secondary battery in which dendrite of lithium generated by repeated charging / discharging is suppressed.

[0002]

2. Description of the Related Art Recently, it is expected that global warming will occur due to the greenhouse effect due to an increase in CO ₂ and the construction of a new thermal power plant will become difficult. for that reason,
As an effective use of generated power, so-called load leveling has been devised, in which night power is stored in a secondary battery installed in a general household or the like to level the load and use it efficiently. Also, there is a demand for the development of high energy density secondary batteries for electric vehicles that do not emit air pollutants, and high performance secondary batteries for powering portable devices such as book-type personal computers, word processors, video cameras, and mobile phones. The demand for is increasing.

As the above high performance secondary battery, a rocking chair type lithium ion battery in which lithium ion is introduced into an intercalation compound as a positive electrode active material and carbon as a negative electrode active material has been developed and partially put into practical use. It's starting. However, the lithium ion battery has not achieved the high energy density which is the original feature of the lithium battery in which metallic lithium is used as the negative electrode active material. The reason why high-capacity lithium secondary batteries using lithium metal for the negative electrode have not been put to practical use is to suppress the generation of lithium dendrites (resin-like crystals), which are the main cause of short circuits due to repeated charging and discharging. It is thought that it is because it did not succeed. When the dendrite of lithium grows and the negative electrode and the positive electrode are short-circuited, the energy possessed by the battery is consumed in a short time and heat is generated. Due to the heat generation, the solvent of the electrolytic solution is decomposed, gas is generated, the internal pressure in the battery is increased, and the battery explodes, or an accident such as ignition occurs infrequently. Therefore, the development of a safe and long-life lithium secondary battery that does not cause the above-mentioned accident has been earnestly desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above conventional problems and provide a lithium secondary battery having a long cycle life.

[0005]

The present inventor has conducted extensive studies in order to solve the above conventional problems, and as a result, coats the surface of a lithium negative electrode with a compound having a hydroxyl group or a carboxyl group that slowly reacts with lithium. By
It was found that the generation of dendrites on the lithium negative electrode can be suppressed by eliminating the protrusions where the dendrites grow easily and suppressing the reactivity with water.

It is generally known that lithium easily reacts with water, methyl alcohol and an inorganic acid to decompose.

The present inventor has found that 0.2% by weight of a tetrahydrofuran solution in which 20% by weight of various alcohols and organic acids are dissolved.
When 5 grams of metallic lithium was soaked and reacted to plot the relationship between the carbon number of the alcohol and the organic acid and the logarithm of the reaction end time, the result is as shown in FIG. 4, and the alcohol and the organic acid having 4 or more carbon atoms are plotted. Reacts slowly with lithium,
It was found that the reaction was easy to control. It was also found that when an alcohol and an organic acid having a large number of carbon atoms were reacted with lithium, a protective film such as a protective film for suppressing the reaction with a trace amount of water was formed.

The lithium secondary battery of the present invention is a lithium secondary battery in which a negative electrode composed of a lithium negative electrode active material, a positive electrode composed of a positive electrode active material, and the positive electrode and the negative electrode are separated by a separator through an electrolyte. The battery is a lithium secondary battery in which at least the surface of the negative electrode of lithium facing the positive electrode is treated with a compound having a hydroxyl group or a carboxyl group.

Also, the lithium secondary battery in which the compound having a hydroxyl group is alcohol or glycol, and the compound having a carboxyl group is carboxylic acid.

Further, it is a lithium secondary battery in which the compound having a hydroxyl group or a carboxyl group has 4 or more carbon atoms, and a lithium secondary battery in which the treated surface is irradiated with ultraviolet rays.

The method for producing a lithium secondary battery of the present invention comprises the steps of forming a negative electrode composed of a negative electrode active material of lithium, a positive electrode composed of a positive electrode active material, and a separator, respectively, and facing at least the positive electrode of the negative electrode. A step of immersing the surface into a solution of a compound having a hydroxyl group or a carboxyl group, a step of sandwiching the separator between the negative electrode and the positive electrode, and a step of injecting an electrolytic solution into the separator sandwiching the negative electrode and the positive electrode. And a method for manufacturing a lithium secondary battery having a.

Another method of manufacturing a lithium secondary battery according to the present invention is the step of forming a negative electrode composed of a lithium negative electrode active material, a positive electrode composed of a positive electrode active material, and a separator, respectively, and At least immersing the surface facing the positive electrode in a solution of a compound having a hydroxyl group or a carboxyl group, irradiating the surface of the negative electrode with ultraviolet light, sandwiching the separator between the negative electrode and the positive electrode, and the negative electrode. And a step of injecting an electrolytic solution into a separator in which a separator is sandwiched between positive electrodes, and a method for manufacturing a lithium secondary battery.

Another method of manufacturing a lithium secondary battery according to the present invention is a negative electrode composed of a lithium negative electrode active material,
A step of forming a positive electrode and a separator each composed of a positive electrode active material, a step of immersing at least the surface of the negative electrode facing the positive electrode in a solution of a compound having a hydroxyl group or a carboxyl group, and the negative electrode below the melting point of lithium And a step of sandwiching a separator between the negative electrode and the positive electrode, and a step of injecting an electrolytic solution into the sandwiching separator between the negative electrode and the positive electrode.

The basic structure of the lithium secondary battery of the present invention is
At least a surface facing the positive electrode is treated with a compound having a hydroxyl group or a carboxyl group, a lithium negative electrode, and a collector, a positive electrode active material, an electrolyte, a negative electrode active material, and a current collector electrically connected to the positive electrode active material, respectively. Consists of. FIG. 1 shows a basic configuration diagram of the lithium secondary battery of the present invention. In FIG. 1, 100 is a negative electrode current collector, 101
Is a negative electrode having a negative electrode active material (lithium or lithium alloy), 102 is a protective film formed by surface treatment, 103 is a positive electrode current collector, 104 is a positive electrode having a positive electrode active material, and 105 is an electrolyte solution (electrolytic solution) , 106 is a negative electrode terminal, 107 is a positive electrode terminal, 108 is a separator, 109
Is a battery case. In the discharge reaction, lithium ions in the electrolytic solution 105 enter the layers of the positive electrode active material 104, and at the same time, are dissolved as lithium ions in the electrolytic solution 105 from the negative electrode 101 through the protective film 102. On the other hand, in the charging reaction, lithium ions in the electrolytic solution 105 are deposited as lithium metal on the negative electrode 101 through the protective film 102, and at the same time, lithium between the layers of the positive electrode active material 104 is dissolved in the electrolytic solution 105.

Compound Having Hydroxyl Group or Carboxyl Group As the compound having a hydroxyl group or a carboxyl group for surface treatment of the negative electrode of the present invention, alcohol, glycol or carboxylic acid is used. The carbon number of these compounds is preferably 4 or more. As the carbon number increases, the reactivity with lithium decreases. Methyl alcohol and ethyl alcohol having a small carbon number have high reactivity with lithium and are not suitable for treating only the lithium surface.

Examples of the above alcohols include n-butyl alcohol, isoamyl alcohol, 2-ethylbutanol, n-octyl alcohol, 2-ethylhexanol and the like.

Examples of the above glycol include 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, pinacol, cyclopentane-1,2-diol, and the like. Is mentioned.

Examples of the carboxylic acid include caproic acid, lauric acid, stearic acid, palmitic acid, sorbic acid,
Resin acids such as

The negative electrode may be treated by a known method such as a method of directly reacting the above compound or a method of immersing the negative electrode in a dilute solution dissolved in a solvent from which water has been removed, pulling it up and then drying it.

Surface Treatment of Lithium Negative Electrode The lithium surface or the lithium alloy surface of the negative electrode is treated by appropriately mixing the alcohol, glycol or carboxylic acid and selecting the concentration.

The surface treatment of the negative electrode, which is a component of the battery of the present invention, will be described in more detail. Lithium is immersed in a solution of a compound having a hydroxyl group or a carboxyl group for reaction, and then pulled up and dried to protect it. A film is formed on the surface of the negative electrode. The treatment layer formed on the surface of the negative electrode needs to have a thickness that does not impede the permeation of ions involved in the battery reaction.

Further, since the film of the product is not high in molecular weight, the film strength is weak, and if the protective film is made too thick, a clutch or disengagement may occur. On the other hand, if the film of the product is too thin, the unevenness of lithium does not provide a sufficient and uniform coating. Therefore, the range of 10 angstrom to 1 micron is preferable, and the range of 50 angstrom to 5000 angstrom is more preferable. The film thickness of the film formed on the surface of the negative electrode is adjusted by the reaction time or the concentration of the compound having a hydroxyl group or a carboxyl group. In order to improve the lithium ion permeability of the film formed by the surface treatment, the electrolyte used in the battery may be dissolved in the treatment solution to perform the surface treatment of the negative electrode.

Further, in order to increase the strength of the protective film formed by the above treatment, it is desirable to irradiate the surface of the lithium negative electrode with ultraviolet rays or heat it at a temperature not higher than the melting point of lithium.

By using the negative electrode having the protective film surface-treated by the above-mentioned method, it is possible to prevent the lithium deposited during charging from directly contacting the electrolytic solution, and to form a secondary battery in which generation of dendrites during charging is suppressed. can do.
As a result, a lithium secondary battery having a long charge / discharge cycle life can be obtained. Further, by applying the above treatment to the surface of the negative electrode, it is possible to suppress the reactivity between water and lithium mixed in the battery due to any cause, and prevent the performance of the battery from being deteriorated, thus facilitating the handling.

Negative Electrode Active Material As the negative electrode active material 101 of the negative electrode, a lithium alloy containing at least one element selected from magnesium, aluminum, potassium, sodium, calcium, zinc and lead in addition to metallic lithium is used. It is possible.

[0026] As the positive electrode active material 104 of the positive electrode active material the positive electrode, lithium enters the interlayer, nickel oxide, cobalt oxide, titanium oxide, iron oxide, vanadium oxide, manganese oxide, molybdenum oxide,
Uses metal oxides such as chromium oxide and tungsten oxide, metal sulfides such as molybdenum sulfide, iron sulfide and titanium sulfide, hydroxides such as iron oxyhydroxide, and conductive polymers such as polyacetylene, polyaniline, polypyrrole and polythiophene. it can.

In order to facilitate the molding of the positive electrode active material, a solvent resistant resin such as polypropylene, polyethylene or fluororesin is used as a binder in some cases. In order to facilitate current collection, it is preferable to mix the conductor powder during molding. As the material of the conductor powder, various types of carbon, copper, nickel, titanium, etc. can be used.

(Coating of Positive Electrode) In order to prevent generation of dendrite which causes a short circuit at the time of charging, it is possible to extend the cycle life of the battery by further coating the surface of the positive electrode with a film that allows lithium ions to pass therethrough. .

As the coating material, a macrocyclic compound derivative polymer, an aromatic hydrocarbon derivative polymer, a fluororesin, a silicone resin, a titanium resin, a polyolefin, or an inorganic oxide, a nitride, a carbide or a halide can be used. . Covering with a flame-retardant material or a non-combustible material such as a fluororesin, polyphosphazene, an inorganic oxide, a nitride, a carbide, or a halide is effective for further improving the safety of the lithium secondary battery.

Separator As a separator, it 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 the ions involved in the battery reaction can move, and must be insoluble and stable in the electrolytic solution, a non-woven fabric such as glass, polypropylene, polyethylene, fluororesin, or a material having a micropore structure is used. Used. Further, a metal oxide film having fine pores or a resin film in which a metal oxide is composited can also be used. In particular, when a metal oxide film having a multilayer structure is used, lithium dendrites are unlikely to penetrate, which 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.

[0031] The electrolyte electrolyte in addition to the case of using as it is, to use those immobilized by adding a gelling agent such as a solution or solution polymer dissolved in a solvent. Usually, an electrolyte solution (electrolyte solution) in which an electrolyte is dissolved in a solvent is used while being retained in a porous separator.

The higher the conductivity of the electrolyte or electrolytic solution, the more preferable it is, and the conductivity at least at 25 ° C. is 1 × 1.
It is preferably 0 ⁻³ S / cm or more, and 5 × 10 ⁻³ S
/ Cm or more is preferable.

The electrolyte contains lithium ions (Li ⁺ ) and Lewis acid ions (BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , C1).
It is possible to use salts of O ₄ ⁻ ) 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 used. It is desirable that the salt be heated under reduced pressure to be sufficiently dehydrated and deoxidized.

As the solvent of the electrolyte, acetonitrile,
Benzonitol, propylene carbonate, ethylene carbonate, dimethylformamide, tetrahydrofuran, nitrobenzene, dichloroethane, diethoxyethane, chlorobenzene, γ-butyrolactone, dioxolane, sulfolane, nitromethane, dimethylsulfide, dimethylsulfoxide, dimethoxyethane, methyl formate, 3-methyl- 2-Oxazolidinone, 2-methyltetrahydrofuran, sulfur dioxide, phosphoryl chloride,
Thionyl chloride, sulfuryl chloride, a mixed solution thereof or the like can be used.

The solvent may be dehydrated with activated alumina, molecular sieves, phosphorus pentoxide, calcium chloride or the like, or depending on the solvent, it may be distilled in an inert gas in the presence of an alkali metal to remove impurities and dehydrate. Is preferred.

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

As the current collectors 100 and 103, fibrous, porous or mesh carbon, stainless steel, titanium, nickel, copper, aluminum, platinum, gold and the like are preferable.

(Battery Shape and Structure) Actual batteries have a flat battery shape, a cylindrical battery shape, a rectangular battery shape, a sheet battery shape and the like. In the spiral structure cylindrical type, a separator is sandwiched between a negative electrode and a positive electrode and housed in a battery case, so that the electrode area can be increased and a large current can be passed during charging and discharging. Also, in the rectangular parallelepiped type,
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.

2 and 3 are examples of schematic cross-sectional views of a single-layer flat type battery and a spiral structure cylindrical battery, respectively. 2 and 3, 201 is a negative electrode made of a negative electrode active material, 203 is a protective film, 301 is a negative electrode surface-treated with a compound having a hydroxyl group or a carboxyl group, 202 and 302 are negative electrode current collectors, and 303 is Positive electrode current collector, 204 and 304 are positive electrodes made of positive electrode active material, 206
And 306 are negative terminals (negative cap), 207 and 307
Is an outer can (positive electrode can) and battery case, 208 and 308 are separators holding an electrolytic solution, 210 and 310 are insulating packings, 311 is an insulating plate.

As an example of assembling the battery of FIGS. 2 and 3,
A negative electrode 201 which has been subjected to a surface treatment and has a protective film 203,
301 and the positive electrodes 204, 304 are separators 208, 3
After being assembled in the positive electrode cans 207 and 307 with sandwiching 08, and injecting an electrolytic solution, the negative electrode caps 206 and 306 and the insulating packings 210 and 310 are assembled and caulked to manufacture a battery.

The preparation of the material for the lithium secondary battery and the assembly of the battery are preferably carried out in dry air from which water is sufficiently removed or in dry inert gas.

Battery Case As the battery case, in addition to a metal outer can that also serves as an output terminal, a case made of a plastic resin member can be used.

The positive electrode can 207, which is the outer can of the actual battery,
As the material for 307 and the caps 206 and 306, stainless steel, particularly titanium clad stainless steel, copper clad stainless steel, nickel-plated copper plate, or the like is used.

In FIGS. 2 and 3, the positive electrode cans 207 and 307 also serve as the battery case and the output terminal. As the material of the battery case, metal such as aluminum, plastic such as polypropylene, or metal other than stainless steel can be used. Alternatively, a composite material of glass fiber and plastic can be used.

[0045] As the material for the insulating packing insulating packing 210 and 310, fluorine resins, polyamide resins, polysulfone resins, and various rubbers can be used.

[0046] As the sealing sealing method, in addition to caulking using a gasket such as insulating packing also adhesives, welding, soldering, it can be used a method such as a glass sealed tube.

[0047] As a material of the insulating plate 311 used for the insulating isolation within the insulation board battery, various organic resin materials and ceramics are used.

Safety valve Although not shown in FIGS. 2 and 3, as a safety measure when the internal pressure of the battery increases, a safety valve using rubber, springs, metal balls or the like is provided.

[0049]

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

(Example 1) A flat type lithium secondary battery having the structure shown in FIG. The materials were prepared and assembled in dry argon.

First, in a dry argon gas atmosphere, a negative electrode current collector 202 made of titanium mesh with a lead was pressure-bonded to a lithium metal foil from the back side, and sorbic acid (20% by weight) and lithium tetrafluoroborate (2% by weight) were attached. %)-Containing tetrahydrofuran solution, dried at 100 ° C., irradiated with ultraviolet rays to form a film of 5000 Å, and surface-treated to prepare a negative electrode 201.

As the positive electrode active material, electrolytic manganese dioxide and lithium carbonate were mixed in a ratio of 1: 0.4, and then 80
A lithium-manganese oxide was prepared by heating at 0 ° C.
Ketjen black and powder fluororesin paint Super Konak (made by NOF CORPORATION) were mixed with the prepared lithium-manganese oxide, and then pressure-molded on a nickel mesh.
Heat treatment was performed at 0 ° C. to form the positive electrode 204.

As the separator 208, an alumina film and a polypropylene non-woven fabric sandwiched between polypropylene micropore separators were used.

The electrolytic solution contains propylene carbonate (P
C) and dimethoxyethane (DME) in an equal amount mixed solvent,
A solution of lithium tetrafluoroborate salt dissolved in 1 M (mo1 / 1) was used.

For the assembly, a separator 208 is sandwiched between the negative electrode 201 and the positive electrode 204, inserted into a positive electrode can 207 made of a titanium clad stainless material, and an electrolytic solution is injected.
A lithium secondary battery was produced by sealing with a negative electrode cap 206 made of a titanium clad stainless material and an insulating packing 210 made of fluororesin rubber.

Example 2 In the same manner as in Example 1, the materials were prepared and assembled in dry argon to produce the battery shown in FIG.

First, in a dry argon gas atmosphere, a negative electrode current collector 202 of a titanium mesh with a lead was pressure-bonded to a lithium metal foil from the back side, and n-octyl alcohol (3
0% by weight) in tetrahydrofuran solution, then 1
The film was dried at 00 ° C., irradiated with ultraviolet rays to form a film having a thickness of 1500 Å, and a surface-treated negative electrode 201 was prepared.

As the positive electrode active material, electrolytic manganese dioxide and lithium carbonate were mixed in a ratio of 1: 0.4, and then 80
A lithium-manganese oxide was prepared by heating at 0 ° C.
Ketjen black and powder fluororesin paint Super Konak (made by NOF CORPORATION) were mixed with the prepared lithium-manganese oxide, and then pressure-molded on a nickel mesh.
Heat treatment was performed at 0 ° C. to form the positive electrode 204.

As the separator 208, a polypropylene nonwoven fabric sandwiched with polypropylene micropore separators was used.

The electrolytic solution contains propylene carbonate (P
C) and dimethoxyethane (DME) in an equal amount mixed solvent,
Lithium tetrafluoroborate salt was dissolved in 1M (mo1 / 1), and a lithium secondary battery was produced in the same manner as in Example 1.

Example 3 In the same manner as in Example 1, the materials were prepared and assembled in dry argon to produce the battery shown in FIG.

First, in a dry argon gas atmosphere, a negative electrode current collector 202 of a titanium mesh with a lead was pressure-bonded to a lithium metal foil from the back side, and 1,4-butanediol (1
0% by weight) and cyclopentane-1,2-diol (10
10% by weight in a tetrahydrofuran solution of 10% by weight
A lithium negative electrode 201 was prepared by drying at 0 ° C. and irradiating with ultraviolet rays to form a film having a thickness of 200 Å.

As the positive electrode active material, electrolytic manganese dioxide and lithium carbonate were mixed in a ratio of 1: 0.4, and then 80
A lithium-manganese oxide was prepared by heating at 0 ° C.
The prepared lithium-manganese oxide was mixed with Ketjen black and tetrafluoroethylene powder, and then pressed into a nickel mesh and heat-treated at 250 ° C. to obtain a positive electrode 20.
4 was formed.

As the separator 208, a polypropylene nonwoven fabric sandwiched with polypropylene micropore separators was used.

The electrolytic solution contains propylene carbonate (P
C) and dimethoxyethane (DME) in an equal amount mixed solvent,
Lithium tetrafluoroborate salt was dissolved in 1M (mo1 / 1), and a lithium secondary battery was produced in the same manner as in Example 1.

The film thickness of each film was adjusted for 10 seconds to 5 minutes to form each film.

In order to compare and evaluate the performance of the lithium secondary batteries manufactured in the above examples, the batteries of the following comparative examples were manufactured.

(Comparative Example 1) Except that the metallic lithium foil crimped with nickel mesh was directly used as the negative electrode.
A lithium secondary battery was produced in the same manner as in Example 3.

(Evaluation of Performance of Secondary Battery) Examples 1, 2, 3
The lithium secondary battery manufactured in Comparative Example 1 was subjected to a charge / discharge cycle test under the following conditions, and the performance was evaluated in comparison with the lithium secondary battery in Comparative Example 1.

The condition of the charge / discharge cycle test is 0.2C.
(Charge / discharge of 0.2 times the capacity / hour), a break time of 30 minutes, and a cutoff voltage of 1.0V. Hokuto Denko HJ-101M6 was used for the battery charging / discharging device. The charge / discharge cycle test was started from discharge.
The battery capacity was the amount of discharge at the third time, and the cycle life was the number of cycles below 60% of the battery capacity.

The performance evaluation results regarding the cycle life of the lithium secondary batteries prepared in Examples 1, 2 and 3 of the present invention and the lithium secondary battery prepared in Comparative Example 1 are shown as the performance of the battery of Comparative Example 1. .0 and summarized in Table 1.

From the evaluation results of Table 1 comparing Examples 1, 2 and 3 with Comparative Example 1, it was found that the cycle life is extended by using the lithium secondary battery having the constitution of the present invention.

[0073]

[Table 1]

[0074]

According to the present invention, it is possible to suppress the dendrite growth of lithium during charging, to prevent the negative electrode and the positive electrode from being short-circuited, and to manufacture a lithium secondary battery having a long charge / discharge cycle life. Become. Furthermore, since metallic lithium can be used as the negative electrode active material, a secondary battery with high energy density can be manufactured. Further, the use of the surface-treated lithium foil lowers the reactivity with water as compared with the untreated one, which facilitates the handling of lithium in the battery assembly process.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a lithium secondary battery of the present invention.

FIG. 2 is a schematic cross-sectional view of a flat type lithium secondary battery of the present invention.

FIG. 3 is a schematic sectional view of a cylindrical lithium secondary battery of the present invention.

FIG. 4 is a diagram showing the logarithm of the reaction end time of metallic lithium and the carbon number of alcohols and organic acids.

[Explanation of symbols]

100, 200, 300 Negative electrode current collector 101 Negative electrode 102, 203 Ion-permeable protective film 201, 301 formed by surface treatment 201, 301 Surface treated negative electrode 103, 303 Positive electrode current collector 104, 204, 304 Positive electrode 105 Electrolyte 106, 206, 306 Negative electrode terminal 107, 207, 307 Positive electrode terminal 108 Separator 208, 308 Separator holding electrolyte 109 Battery case 210, 310 Insulation packing 311 Insulation plate

Claims (17)

[Claims] 1. A lithium secondary battery in which a negative electrode composed of a negative electrode active material of lithium, a positive electrode composed of a positive electrode active material, and the positive electrode and the negative electrode are separated by a separator through an electrolyte, A lithium secondary battery in which the surface of the negative electrode of lithium facing the positive electrode is treated with a compound having a hydroxyl group or a carboxyl group. 2. The lithium secondary battery according to claim 1, wherein the compound having a hydroxyl group is alcohol. 3. The lithium secondary battery according to claim 1, wherein the compound having a hydroxyl group is glycol. 4. The lithium secondary battery according to claim 1, wherein the compound having a carboxyl group is a carboxylic acid. 5. The lithium secondary battery according to claim 1, wherein the compound having a hydroxyl group or a carboxyl group has 4 or more carbon atoms. 6. The lithium secondary battery according to claim 1, wherein the treated surface is irradiated with ultraviolet rays. 7. The lithium secondary battery according to claim 1, wherein the treated negative electrode is heat-treated at a temperature not higher than the melting point of lithium. 8. The lithium secondary battery according to claim 1, wherein at least a surface of the positive electrode made of the positive electrode active material facing the negative electrode is coated with a film that permeates lithium ions. 9. The lithium secondary battery according to claim 1, wherein the film is a flame-retardant material or a non-combustible material. 10. The lithium secondary battery according to claim 1, wherein the negative electrode active material is a lithium alloy. 11. A step of forming a negative electrode composed of a negative electrode active material of lithium, a positive electrode composed of a positive electrode active material, and a separator, respectively, and a compound having a hydroxyl group or a carboxyl group on at least the surface of the negative electrode facing the positive electrode. The step of immersing the separator in the solution, the step of sandwiching the separator between the negative electrode and the positive electrode, and the step of injecting an electrolytic solution into the sandwiching the separator between the negative electrode and the positive electrode. Next battery manufacturing method. 12. The method for producing a lithium secondary battery according to claim 11, wherein the compound having a hydroxyl group is alcohol. 13. The method for producing a lithium secondary battery according to claim 11, wherein the compound having a hydroxyl group is glycol. 14. The method for producing a lithium secondary battery according to claim 11, wherein the compound having a carboxyl group is a carboxylic acid. 15. The method for producing a lithium secondary battery according to claim 11, wherein the compound having a hydroxyl group or a carboxyl group has 4 or more carbon atoms. 16. A step of forming a negative electrode composed of a negative electrode active material of lithium, a positive electrode composed of a positive electrode active material, and a separator, respectively, and a compound having a hydroxyl group or a carboxyl group on at least the surface of the negative electrode facing the positive electrode. Step of immersing in the solution of, the step of irradiating the surface of the negative electrode with ultraviolet rays, the step of sandwiching the separator between the negative electrode and the positive electrode, and the step of injecting an electrolytic solution into the one in which the separator is sandwiched between the negative electrode and the positive electrode. And a method for manufacturing a lithium secondary battery, comprising: 17. A step of forming a negative electrode composed of a negative electrode active material of lithium, a positive electrode composed of a positive electrode active material, and a separator, respectively, and a compound having a hydroxyl group or a carboxyl group on at least the surface of the negative electrode facing the positive electrode. The step of immersing the negative electrode in the solution, the step of heat-treating the negative electrode at a temperature equal to or lower than the melting point of lithium, the step of sandwiching the separator between the negative electrode and the positive electrode, and the injection of the electrolytic solution into the negative electrode and the positive electrode sandwiching the separator. The method of manufacturing a lithium secondary battery, comprising: