JP2003536233A - Microporous solid inorganic electrolyte and method for producing the same - Google Patents

Abstract

  (57) [Summary] According to the present invention, when producing an electrolyte membrane and / or a solid electrolyte having a microporous structure for a secondary battery, at least 70% by weight or more of inorganic absorbent particles are added to a polymer matrix. It is another object of the present invention to maintain the absorptive power and ionic conductivity of the solid electrolyte membrane with respect to the liquid electrolyte by preventing the porous structure from being greatly destroyed even during the battery assembly process such as lamination and pressing. In combination with the microporous structure, the absorbent particles contained in a specific content or more improve the ability of the liquid electrolyte to absorb, and in particular, as a structure for improving the mechanical strength of the electrolyte membrane and / or the solid electrolyte. Play a role. Therefore, there is a characteristic that excellent ion conductivity can be maintained as it is even after the battery is assembled.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a solid electrolyte film used in a secondary cell, and more specifically, to a solid electrolyte membrane of the present invention having a fine porous structure containing an absorbent in a specific amount or more. A liquid component and a lithium salt (collectively referred to as “liquid electrolyte” below) are introduced to provide a migration path for ions that move between the positive electrode and the negative electrode during the charging / discharging process of the secondary battery. is there.

The secondary battery of the present invention has three basic constituent elements of a positive electrode, a negative electrode, and an electrolyte, and is a battery by stacking positive electrode / electrolyte / negative electrode which are flat plates. Lithium metal or lithium ions are intercalated into the negative electrode material (in
A carbon material or a polymer material capable of tercalation / deintercalation is used, and a material of the positive electrode is a transition metal oxide or a polymer material capable of intercalating / extracting lithium ions. A solid electrolyte according to the present invention can be used as the electrolyte, and the liquid electrolyte is introduced after the battery is assembled.

[0003]

[Prior art]

An electrolyte in a battery such as a secondary battery or an electrochemical reaction system is an insulator that is arranged between two conductive surfaces of a positive electrode and a negative electrode, has no electronic conductivity, and has only ionic conductivity. . Until now, electrolytes have mostly consisted only of liquid components, but there is increasing interest in solid electrolytes with various advantages. Among them, various studies and attempts have been made to use polymers as electrolytes.

A pure polymer electrolyte containing a polar hetero element has an ionic conductivity at room temperature of only about 10 ⁻⁸ S / cm, and is difficult to use at room temperature. Therefore,
The main research on polyelectrolytes is to improve conductivity, and a method of introducing a liquid electrolyte component into a polymer skeleton has been proposed as a method.

Gel-type electrolytes such as US Pat. No. 5,219,679 include a liquid electrolyte in a polymer skeleton, and while exhibiting polymer characteristics,
Has a good level of conductivity. However, since a large amount of liquid electrolyte is already contained in the process of producing the polymer electrolyte, vaporization / damage of the liquid component is unavoidable, which causes problems such as composition change and decrease in conductivity. Besides, since the lithium salt in the liquid electrolyte is very sensitive to moisture, it is necessary to manufacture the electrolyte in an extremely severe dehumidifying atmosphere.

Hybrid polymer electrolyte systems in US Pat. No. 5,296,318, US Pat. No. 5,418,091, etc., are used in a battery manufacturing process by adding a liquid electrolyte after battery assembly. The influence of water can be minimized, and the advantages of gel-type polymer electrolyte, which conducts lithium ions through the liquid electrolyte, can be utilized. On the other hand, since the liquid electrolyte is added after the production of the electrolyte membrane, the plasticizer (p) is added in the process of producing the electrolyte membrane to provide a space for sucking the liquid electrolyte in the electrolyte membrane.
A method was used in which an organic solvent was extracted after the battery assembly was completed by adding a finalizer / processing aid. However, such a method has a fatal disadvantage that reproducibility is low, battery yield is reduced, and automation for mass production is difficult.

In order to solve the problems of the above technology, an attempt has been made to form a pore to facilitate the inhalation of a liquid electrolyte when a polymer membrane is manufactured. Generally, a polymer is dissolved in a solvent and cast into a film, and then the film is treated with a non-solvent (non-sodium).
There is an example in which a method of contacting with a solvent and exchanging a solvent was announced, and in addition, vulcanization, curing or stretching.
The method of introducing porosity is also disclosed. When the liquid electrolyte is sucked into the polymer membrane manufactured in this manner, the ionic conductivity becomes 10 ⁻³ S / cm or more at room temperature, which is suitable for actual use. However, the process for introducing the porosity becomes complicated, or the lamination (lamination) for assembling the battery is performed.
cation) or pressing, the porous structure formed in the polymer membrane is easily destroyed, resulting in a sudden decrease in ionic conductivity. In other words, although the polymer electrolyte alone has good performance, it is difficult to apply it to an actual battery system.

In order to solve the problem of destruction of porosity, an attempt has been made to apply a polymer film directly on the positive electrode and / or the negative electrode and bring it into contact with a non-solvent. However, when the electrode surface is used as a substrate for producing an electrolyte membrane, not only the manufacturing process is complicated but also water, which is generally used as a non-solvent, is used as a positive electrode and / or a positive electrode. Or, since it adversely affects the negative electrode plate, it is difficult to apply in practice.

US Pat. No. 5,631,103 discloses an electrolyte system with the addition of an inorganic filler. However, in order to obtain a practical level of conductivity, the content of the inorganic filler must be increased. In such a case, the mechanical strength of the polymer film is weakened, making it difficult to apply it to the actual process. . Furthermore, by selecting a method of adding a process auxiliary agent to form a polymer film and then removing / extracting it to introduce porosity, the above-mentioned US Pat. No. 5,296,318 and US Pat. , 4
A problem similar to 18,091 may occur.

On the other hand, Japanese Patent Laid-Open No. 11-16561 discloses a polymer electrolyte system in which an inorganic filler is added to a polyvinylidene fluoride resin porous body. The system is
It has good room temperature ionic conductivity and mechanical strength capable of being formed into a film, but the content of inorganic substances is only 1.9 to 66% by weight based on the total weight of the electrolyte membrane (polyvinylidene fluoride resin 100). 2 to 200 parts by weight based on parts by weight), preferably 4.8 to 33.3% by weight (corresponding to 5 to 50 parts by weight based on 100 parts by weight of polyvinylidene fluoride resin), Since it is not enough to support the porous structure, it is still difficult to eliminate the disadvantages of the destruction of the porous structure of the polymer electrolyte and the short circuit of the battery during the battery assembly process. Therefore, a battery having excellent physical properties cannot be manufactured.

[0011]

[Problems to be Solved by the Invention]

The above problems of the prior art can be summarized as follows. First, an electrolyte consisting of pure polymer has low room temperature ionic conductivity and is not suitable for practical use. Secondly, a gel-type polymer electrolyte produced in a state containing a liquid electrolyte is advantageous because ions can be conducted by the liquid electrolyte and the room temperature ionic conductivity can be improved.
There are restrictions on the manufacturing process atmosphere and it is difficult to maintain constant performance. Thirdly, a hybrid polyelectrolyte that absorbs a liquid electrolyte by adding a plasticizer / process aid to a film form and then extracting it into a film form has less influence on the manufacturing process atmosphere. Although it is advantageous to have sufficient ionic conductivity without being affected by the above, complicated multi-step processes and materials are required, and the process unit price increases, making automation difficult and reproducibility low. Fourth, a polymer electrolyte that introduces fine porosity by various methods such as solvent / non-solvent exchange, vulcanization, curing, stretching, etc., has a fine porous structure destroyed by a lamination or pressing process, resulting in liquid There is a problem that the electrolyte cannot be absorbed sufficiently. Fifth, the method of forming the porous structure film on the electrode surface is advantageous for improving the interfacial adhesion between the electrolyte and the electrode, but the electrode performance may deteriorate and the process conditions are not simple, which is preferable. Absent. Sixth, there was an attempt to add an inorganic substance in order to improve the mechanical strength of the electrolyte, but this also solves the problem of porosity destruction in the battery assembly process, and the problem of maintaining ionic conductivity. I couldn't solve it completely.

On the other hand, the present inventors previously applied for a system that facilitates absorption of a liquid electrolyte by introducing fine porosity into an electrolyte membrane matrix containing an absorbent and can improve the conductivity of lithium ions. (PCT / KR99 / 00798).
The system does not require the addition of a moisture sensitive liquid electrolyte after cell assembly and the removal of the above absorbents after cell assembly. Incidentally, US Pat. No. 5,296,31
No. 8 and Nos. 5,418,091 and 5,631,103 do not require plasticizers or process auxiliary agents, and thus have an advantage that the manufacturing process is simple and the manufacturing cost is low. However, the present inventors have discovered that, as described above, the problems of microporous destruction of the solid electrolyte membrane and reduction of the absorption capacity for the liquid electrolyte may occur in the process of joining the positive electrode and / or the negative electrode. Therefore, the present inventors have confirmed that an absorbent having a specific content or more is required to solve the above problems, and have completed the present invention.

[0013]

[Means for Solving the Problems]

Accordingly, the present invention is directed to a microporous structure.
ure) in producing an electrolyte membrane and / or a solid electrolyte, inorganic particles are added in a specific amount or more so that they can simultaneously serve as a structure and an absorbent, and a battery assembly process such as lamination and pressing. Even in the case of (2), the porous structure is not largely destroyed, and the solid electrolyte membrane tries to maintain the absorption capacity for the liquid electrolyte and the lithium ion conductivity. In combination with the fine porous structure, the absorbent particles contained in a specific amount or more improve the absorption capacity of the liquid electrolyte, and in particular, as a structure that improves the mechanical strength of the electrolyte membrane and / or the solid electrolyte. Play a role. Therefore, there is a feature that excellent lithium ion conductivity can be maintained as it is even after the battery is assembled. At the same time, there is no need for a separate operation for absorbing the liquid electrolyte, and the liquid electrolyte has the advantage that it can exhibit the essential characteristics of the microporous structure when it is introduced after the battery is assembled.

[0014]

DETAILED DESCRIPTION OF THE INVENTION

The solid electrolyte of the present invention contains an inorganic absorbent and includes an electrolyte membrane having a fine porous structure and an ion conductive liquid electrolyte. That is, a solid electrolyte for a secondary battery is manufactured through an activation process of absorbing an ion conductive liquid electrolyte in a fine porous electrolyte membrane composed only of an inorganic absorbent and a polymer binder. The "electrolyte membrane" in the present specification is a microporous electrolyte membrane in a dry state and does not contain a liquid electrolyte, and the "solid electrolyte" means ion conductivity including liquid electrolyte in the electrolyte membrane. To have. Although it is not in a completely solid state because it contains a liquid electrolyte, since the basic skeleton of a solid electrolyte is based on a solid state electrolyte membrane, it is expressed as a concept distinguished from a liquid electrolyte.
Name it "solid electrolyte".

The electrolyte membrane is preferably a phase inversion method known in the art.
Although it can be manufactured by utilizing a reaction method, there are, for example, a wet method and a dry method. The wet process is a method of dissolving a mixture of an absorbent and a polymer binder in a solvent of the polymer binder, molding the mixture into a membrane, and then adding the solvent to the polymer binder. It is a method of producing by drying after exchanging with a non-solvent. On the other hand, dry process
Is a mixture of an absorbent and a polymeric binder, a solvent of the polymeric binder and a non-solvent of the polymeric binder, a pore former, and a wetting agent.
gent) is mixed and formed into a film form, and then completely dried.

The inorganic absorbent that can be used in the present invention has a high affinity for the liquid electrolyte and absorbs the liquid electrolyte, or improves the absorption capacity of the liquid electrolyte and has no electronic conductivity. . Further, those having excellent mechanical, thermal, chemical and electrochemical properties are used. As the inorganic absorbent, mineral particles, synthetic oxide particles and mesoporous molecular sieves (mesoporous molecules)
One or more particles selected from the group consisting of ar sieve) are used. Preferred examples of mineral particles include clay, paragonite (para).
Examples thereof include mineral particles having a phyllosilicate structure such as gonite), montmorillonite, and mica. Preferable examples of the above synthetic oxide particles include zeolite (zeolite), porous silica (silica), and porous alumina (a).
lumina), magnesium oxide (Magnesium oxide) and the like. Preferred examples of the above mesoporous molecular sieves include oxide compounds such as silica having a pore diameter of 2 to 30 nm. The mineral particles, the synthetic oxide particles and the mesoporous molecular sieve may be used in the form of a mixture in which two or more absorbents selected from the above-mentioned absorbents are combined.

The inorganic absorbent preferably has a particle size of 40 μm or less, and more preferably 20 μm or less, in order not to reduce the mechanical strength and uniformity of the formed electrolyte membrane. However, if the inorganic absorbent is too small, the absorbability is lowered or the electrolyte membrane is likely to have a dense structure, which is not preferable. In the prior art such as Japanese Patent Laid-Open No. 11-16561, an inorganic material having a very small particle size (for example, 20 nm or less) is used, but in this case, the inorganic material does not serve as an absorbent and a filler or a polymer film. Plays the role of reducing the crystallinity of That is, in order to simultaneously exhibit the properties of the absorbent and the structure as in the present invention, the particle size of at least 50 nm unit or the aggregated form (aggre) of several μm unit is used.
gated form) is required. The shape of the inorganic absorbent is not particularly limited, and may be fibrous, needle-shaped, plate-shaped, or spherical, but an asymmetrical shape is preferable in order to improve the mechanical strength of the electrolyte membrane.

A first object of the present invention is to manufacture a solid electrolyte that maintains the absorption power and ionic conductivity of a liquid electrolyte by having a mechanical strength such that the microporous structure is not greatly destroyed even after battery assembly. That is. The present inventors have found that the content of the inorganic absorbent is the most decisive condition in achieving this object. The content of the inorganic absorbent is preferably at least 70% by weight, more preferably 70 to 95% by weight, based on the weight of the electrolyte membrane composed of the inorganic absorbent and the polymer binder.
Are more preferred. When the content is 95% by weight or more, the ionic conductivity does not further increase as the content increases, and the mechanical strength of the electrolyte membrane formed on the contrary and the interfacial adhesion with the electrode are weakened. On the other hand, if the content is less than 70% by weight, the following problems will occur.

If the content of the inorganic material is less than 70% by weight, the porous structure of the solid electrolyte membrane is easily destroyed during the lamination or pressing process for assembling the battery, so that the absorption capacity and the ionic conductivity of the liquid electrolyte are reduced. Is greatly reduced. The inventors of the present invention produced the solid electrolyte membrane by changing the content of the inorganic absorbent, and then observed the thickness change and the ionic conductivity change due to the external load applied in the actual battery manufacturing process. It has been found that the thickness and ionic conductivity of the solid electrolyte membrane change significantly based on the weight percentage. This is a fact that has never been presented or implied in the conventional prior art, and is a fact that has been found for the first time that the optimum content condition of the inorganic absorbent is set. Based on empirical facts, only when the inorganic content is at least 70 wt% or more, the porous structure of the solid electrolyte is less destroyed even under the pressure applied in the manufacturing process, and the absorption capacity of the liquid electrolyte is lost. Since there is no ionic conductivity, the overall battery performance is improved.

2. When the content of the inorganic material is 70% by weight or less, the bulk ratio of the polymer based on the total weight of the electrolyte membrane or the solid electrolyte is large, so that the morphology changes drastically. That is,
During the process of drying the electrolyte membrane or the process of impregnating the liquid electrolyte after the battery is assembled, the degree of shrinkage / expansion of the polymer region increases, so that the dimensional stability of the electrolyte membrane / solid electrolyte decreases.

[0021] Third, when the content of the inorganic substance is 70% by weight or less, even though a large amount of the absorbent is contained, many drawbacks pointed out to the general polymer-based electrolyte are completely eliminated. It is difficult to resolve. For example, performance is degraded at low or high temperatures, similar to polymer-centered electrolytes. As described above, in a general polymer electrolyte, since the conduction of ions is directly affected by the movement of polymer chains, the influence of temperature on the ionic conductivity is large. In particular, at low temperatures, the movement of polymer chains slows down and the ionic conductivity is greatly reduced, resulting in very poor battery performance. However, when an inorganic absorbent is used as in the present invention, the ion conductivity is improved, and if the inorganic absorbent that is not so much affected by temperature is used in a specific amount or more, the characteristics of a general polymer electrolyte are Unlike, it is almost unaffected by temperature. In addition, since the electrolyte contains a specific amount or more of an inorganic substance, there is an advantage that resistance to ignition or explosion is improved as compared with an electrolyte containing a large amount of an organic substance such as a polymer.

Therefore, the discovery that the above problems can be solved only when the inorganic absorbent is contained in a specific amount or more is found in the prior art and other fields in which the amount of the inorganic material added as a filler is usually about Considering that the amount is around 50% by weight or less, it was found from the result of repeated experiment and analysis by setting the content of the inorganic substance in a range that seems to be somewhat excessive, and it is an exceptional exception exceeding the existing concept. It is also a typical configuration.

Most ordinary polymers are used as the polymer binder, and among them, polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene are used.
copolymer of vinyl), vinylidene fluoride and maleic anhydride (maleic)
copolymer of anhydride, polyvinyl chloride (polyvinyl)
loride), polymethylmethacrylate, polymethacrylate (pol)
ymethacrylate, cellulose triacetate (cellulos)
e triacetate), polyurethane (polyethane), polysulfone (polysulfone), polyether (polyether)
Polyolefins such as polyethylene, polyethylene or polypropylene
fine), polyethylene oxide, polyisobutylene (polyisobu)
poly (ethylene), polybutyldiene, poly (vinyl alcohol), polyacrylonitrile, polyimid.
e), polyvinyl formal, acrylonitrile butyl diene rubber (acrylonitrile butylene)
e ruber), ethylene propylene diene monomer (ethylene-
Propylene-diene-monomer), tetraethylene glycol diacrylate (tetra (ethyleneglycol) diacry)
plate), polydimethylsiloxane (polydimethylsiloxane)
ne), polycarbonate, and silicone polymer (polysilicone)
Particularly preferred are one or more polymer mixtures selected from the group consisting of or copolymers or polymer mixtures thereof.

As the polymer binder, it is not preferable that the physical properties of the polymer binder are largely changed by heat and pressure, or that crosslinking and curing reaction occur. Also, at least 1 in the monomer state
Polymerization, copolymerization, cross-linking, curing reaction, etc. are not preferable by adding a seed, but this reduces the performance of the battery by reacting with the electrolyte compound while the unreacted monomer is impregnated in the inorganic absorbent. Therefore, a separate step for removing this is required. Therefore, during the electrolyte membrane manufacturing process and battery assembly process,
It is desirable to avoid the conditions that cause the above problems.

The solvent of the polymer binder is one that has solubility in the polymer binder, and is NMP (
N-methylpyrrolidone), dimethylformamide (di
methylformamide), dimethylacetamide (dimethyl)
acetamide), tetrahydrofuran (tetrahydrofuran)
), Acetonitrile (acetonitril), cyclohexanone (cyc)
lohexanone), chloroform (chloroform), dichloromethane (dichloromethane), hexamethylphosphoamide (hex)
Amethyl phosphoramide), dimethyl sulfoxide (dim)
One or a mixture of two or more selected from the group consisting of ethyl sulfoxide, acetone and dioxane is preferable.

The non-solvent of the polymeric binder has no or very low solubility in the polymeric binder,
It is compatible with the above polymer binder solvents, such as water and ethanol.
nol), ethylene glycol (ethylene glycol), glycerol (glycerol), acetone, dichloromethane, ethyl acetate (e
thylacetate), butanol (butanol), pentanol (p
entanol), hexanol (ether) and ether (ether)
1) or a mixture of 2 or more selected from the group consisting of

The solid electrolyte having a fine porous structure of the present invention is manufactured by a phase conversion method such as a wet method or a dry method, and the details are as follows.

[0028]Wet method   The solid electrolyte having a fine porous structure of the present invention includes a polymer binder dissolved and an inorganic absorbent.
By a wet process consisting of 5 steps of mixing, film formation, porosification and drying, and activation.
Manufactured.

First, the polymer binder is dissolved in a solvent, and then the inorganic absorbent is added and sufficiently mixed so as to be uniformly dispersed. Solid content of the above mixed solution (solid co
content) is preferably 5 to 60% by weight based on the total weight, and when it is 5% by weight or less, the mechanical strength of the electrolyte membrane decreases after drying, and when it is 60% by weight or more, the inorganic absorbent is sufficiently contained. It may not be dispersed, or the viscosity of the mixed solution may become very high.

In order to smoothly disperse the inorganic absorbent, a magnetic stirrer is used.
, mechanical stirrer, planetary mixer, high speed disperser
It is also possible to mix them by using a disperser or the like. An ultrasonic stirrer can be used to prevent the absorbents from aggregating with each other in the step and to prevent bubbles from being generated during the mixing. In some cases, defoaming
ing) and a filtering process.

After the polymer binder and the inorganic absorbent are uniformly mixed, the polymer binder and the inorganic absorbent are adjusted to have a constant thickness and formed into a film form. For example, it may be poured onto a flat substrate and cast to have a constant thickness, or it may be extruded into gaps at regular intervals and coated on the substrate. As the base material, a material that is chemically, thermally and mechanically stable and that can be separated from the electrolyte membrane through a drying or lamination process is used. For example, polymer films such as polyester and polytetrafluoroethylene, paper, and the like can be used. In addition, various application methods can be selected.

The shaped membrane is contacted with a non-solvent for the polymeric binder to extract the solvent for the polymeric binder. For example, a non-solvent tank containing a non-solvent (non-solvent po
sol) and the solvent can be extracted. Therefore, it is preferable to select a combination of miscible solvent and non-solvent. The immersion time in the non-solvent tank depends on the types of the solvent and non-solvent, but is preferably about 1 minute to 1 hour. If the time is short, sufficient porosity may not be induced or the solvent may be incompletely replaced, but if the time is long, the productivity may be decreased, which is not preferable. The temperature of this tank is preferably 10 ° C to 90 ° C, 2
0 ° C to 80 ° C is more preferable. When the temperature is low, sufficient porosity is not induced, and when the temperature is high, the mechanical strength of the electrolyte membrane decreases, which is not preferable. After the solvent extraction, the produced membrane is completely dried to produce an electrolyte membrane.

[0033]Dry method   The solid electrolyte having a porous structure of the present invention can dissolve a polymer binder and mix an inorganic absorbent.
In the case of addition, additives (non-solvent, pore-forming agent, wetting aid), film forming and drying, and
It is produced by a dry method consisting of 5 steps of activation and activation.

After dissolving the polymer binder in the solvent, the inorganic absorbent is added and mixed sufficiently so as to be uniformly dispersed. The dispersion or mixing process is the same as in the wet method. After the polymer binder and the absorbent are uniformly mixed, a solvent that does not dissolve the polymer binder, that is, a non-solvent is added in consideration of porosity within a range in which precipitation of the polymer binder does not occur. In order to smoothly generate a fine porous structure, it is preferable to add a pore forming agent, a wetting aid and the like. The process of forming the solution thus produced into a film form is the same as in the case of the wet method described above. After being formed into a membrane form, it is completely dried at 20 ° C to 200 ° C to manufacture an electrolyte membrane.

Since the dry method has the following problems as compared with the wet method, it is more preferable to manufacture the electrolyte membrane by the wet method.

First, in the dry method, it is relatively difficult to completely disperse or mix the inorganic absorbent, the polymer binder, the additives and the like. When it is not completely dispersed or mixed, the pore-forming agent or the inorganic absorbent is difficult to be uniformly distributed, it is difficult to form the electrolyte membrane, and the mechanical strength and reproducibility are deteriorated. That is, when the pore-forming agent or the inorganic absorbent is not uniformly distributed, when actually used as the electrolyte of the battery, the battery reaction proceeds in a nonuniformly unevenly distributed state, and it is difficult to form it into a membrane form. However, since mechanical strength is reduced, there are many restrictions on the process.

In the dry method, a non-solvent is added to form pores, but on the principle of the dry method, the pores are not formed unless the solvent is evaporated (dried) before the non-solvent, and the non-solvent First, since the pores are not formed when evaporated, it is generally necessary that the non-solvent has a boiling point higher than that of the solvent or is non-volatile. Therefore, there is a high possibility that nonsolvents will remain in the dry method. After all, the boiling point is high or the use of a non-volatile non-solvent makes it difficult to completely remove it from the electrolyte membrane during the drying process, and a separate method (for example, extraction with alcohol or ether, or drying) is used to completely remove it. Method of raising the temperature sufficiently) must be taken. Since the non-solvent may be chemically or electrochemically unstable, when it remains in the electrolyte membrane, it induces a side reaction or is oxidized or reduced during the charge / discharge process of the battery, and the capacity of the battery decreases. Or it may reduce the performance such as gas generation. Such a problem applies not only to the non-solvent but also to other additives. Therefore, in the process of completely removing the additives and the like to manufacture the electrolyte membrane containing only the absorbent and the polymer binder, the manufacturing process becomes complicated and reproducibility may be difficult to be ensured.

The thickness of the electrolyte membrane of the present invention is preferably adjusted to 20 to 200 μm.
If the film thickness is 20 μm or less, the mechanical strength is lowered, and a short circuit may occur during battery assembly. On the other hand, if it is 200 μm or more, the ionic conductivity is reduced, which is not preferable. The electrolyte membrane of the present invention preferably has a pore diameter of 20 μm or less,
It is more preferably 10 μm or less, and most preferably 0.01 to 5 μm. Also, the electrolyte membrane of the present invention has a porosity of 5 to 95%.
It is preferably ty), more preferably 20 to 90%, most preferably 40 to 85%.

The liquid electrolyte to be absorbed in the microporous electrolyte membrane produced by the above method is produced by dissolving a lithium salt in an organic solvent.

The organic solvent has high polarity and high reactivity with respect to lithium metal in order to increase the polarity of the electrolyte, improve the dissociation degree of ions, and reduce the local viscosity around the ions to facilitate the conduction of ions. Those are preferable. Examples of such organic solvents include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (
butylenes carbonate), dimethyl carbonate (dimethy)
lcarbonate, DMC), diethyl carbonate
onate, DEC), ethylmethyl carbonate (ethylmethylcar)
Bonate, EMC), gamma-butyrolactone (γ-butyrolac)
tone, GBL), dimethylsulfoxide
ide, DMSO), 1,3-dioxane (1,3-dioxane, DO
), Tetrahydrofuran (Tetrahydrofuran, THF), 2-
Methyl tetrahydrofuran (2-methyltetrahydrofuran
), Sulfolane, N, N-dimethylformamide (N,
N-dimethylformamide (DMF), diglyme (digly)
Me, DME), triglyme, tetraglyme (tetr)
aglyme) and the like. In particular, the organic solvent is preferably used in the form of a mixed solution of two or more consisting of a high viscosity solvent and a low viscosity solvent.

The lithium salt preferably has a low lattice energy and a high dissociation degree. Examples of such lithium salts include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiA.
sF ₆ , LiSCN, LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiC
(CF ₃ SO ₂ ) _{3 and the} like, and selective mixtures thereof are also used. The concentration of the lithium salt is preferably 0.5M to 2M.

The liquid electrolyte is 20 to 90 based on the total amount of the electrolyte including the liquid electrolyte.
The solid electrolyte may have a room temperature lithium ion conductivity of about 1 to 3 mS / cm.

Further, the present invention relates to a secondary battery using the above porous solid electrolyte as an electrolyte, particularly to a lithium secondary battery.

[0044]   The method for manufacturing a secondary battery using the solid electrolyte of the present invention will be described in detail below.

The dried solid state electrolyte membrane obtained from the above process is sandwiched in the middle and the positive electrode and the negative electrode are joined by a method such as lamination and pressing to form a battery assembly. The positive electrode, the negative electrode, and the electrolyte membrane are separately manufactured, and the positive electrode is electrically connected to the positive electrode current collector, and the negative electrode is electrically connected to the negative electrode current collector. In order to obtain a solid electrolyte having sufficient ion conductivity to be used, an activation step of absorbing a liquid electrolyte should be performed, and the step allows the battery to operate.

The method of separately manufacturing the electrolyte membrane and the electrodes (positive electrode and negative electrode) is preferable because performance management, process design and equipment are simple. However, in order to improve the bonding property between the electrode and the electrolyte membrane and make the electrolyte membrane thin, a method of directly forming a slurry containing an absorbent, a polymer binder, a solvent, etc. on the fabricated electrode to form the electrolyte membrane. Can be considered,
It is not preferable because it is difficult to use if the manufacturing process conditions of the electrode and the electrolyte membrane do not match, or if the electrode or the electrolyte membrane is contaminated during the process or its performance is easily damaged.

The process of assembling or stacking the electrolyte membrane between the electrodes and performing the lamination or pressing process on the battery may be variously changed considering the performance and process conditions of the battery. First, the electrolyte membrane is first laminated on the surface of either the positive electrode or the negative electrode, and then the other electrode is laminated with the electrolyte membrane interposed therebetween. Secondly, an electrolyte membrane is laminated on each of the surfaces of the positive electrode and the negative electrode, and then the positive electrode and the negative electrode are laminated so that the electrolyte membrane faces each other. Third, the positive electrode, the electrolyte, and the negative electrode are simultaneously laminated in the order described above.

In the above-mentioned lamination process (lamination process), it is preferable to set the lamination conditions so that the bulk reduction of the electrolyte membrane occurs within 50% to the minimum. The reduction of the bulk of the electrolyte membrane means the destruction of the porous structure, but a slight reduction of the bulk is inevitable for the lamination due to heat and / or pressure. Therefore, it is necessary to find a stacking condition that can minimize bulk reduction. As described above, it was confirmed that such bulk reduction is remarkably reduced by adding at least 70% by weight or more of the inorganic absorbent, which is one of the features of the present invention.

In order to suppress the bulk reduction of the electrolyte membrane, a method is selected in which heat and pressure are used to a minimum and the bonding between the electrode and the electrolyte membrane is made by an adhesive layer. For example, PE
Solution / dispersion, ethylene / ethyl acrylate based or ethylene / vinyl acetate based adhesives are used. However, such adhesive components must be thermally, chemically and electrochemically stable, the adhesive layer must not destroy the interfacial porous structure, and must not increase the interfacial resistance. . Therefore, the use of the adhesive layer is not actually preferable in battery fabrication and performance control.

The manufacturing process of the positive electrode or the negative electrode will be described in detail below. Each of the positive electrode and the negative electrode includes a current collector and an active material layer. The active material layer includes an active material and a conductive material.
ing material), a binding material, and the like. In addition, various additives (additives) for the purpose of improving battery performance.
) May be introduced. The current collector, the conductive material, the binder, and the additive contained in the positive electrode or the negative electrode may be the same as each other, or may be different depending on the purpose. A mixture of each of the above positive electrode or negative electrode materials is made into a slurry and then directly formed on a current collector, or a thin film is formed by a method such as casting, coating, or screen printing, followed by pressing and laminating. It can also be manufactured by combining it with a current collector.

The current collector provides a transfer path of electrons generated in the oxidation / reduction reaction performed in the positive electrode or the negative electrode. As the current collector, a grid, a foil, a punching foil, an etching foil, or the like is used, which can be selected according to the battery performance and the manufacturing process. When the grid is used, the filling rate of the active material is increased, but the manufacturing process becomes difficult, and when using a foil or the like, the battery performance is improved and the manufacturing process can be simplified, but the filling rate of the active material is reduced. obtain. Copper, aluminum, nickel, titanium, stainless steel, carbon, etc. are used for the current collector. Generally, aluminum is used for the positive electrode and copper is used for the negative electrode. The current collector can be pre-treated if necessary. For example, cleaning, surface treatment or application of an adhesive layer can be performed.

The active material is a material in which the charge / discharge reaction (or oxidation / reduction reaction) of the battery actually occurs, and is the most important factor that determines the performance of the battery. It is also the component with the highest content in the active material layer. As a positive electrode active material, a transition metal (transiti)
on Metal) oxides, sulfides, organic compounds, polymer compounds and the like are used, and preferably lithium cobalt oxide (L).
i _x CoO _2), lithium nickel oxide _(Li x _NiO 2), lithium nickel cobalt oxide _{(Li x Ni y Co 1-} y O 2), spinel type lithium-manganese oxide _{(Li x Mn 2 O 4)} , An oxide such as manganese dioxide (MnO ₂ ) or a polymer material is used. As the negative electrode active material, an alkali metal (alka)
li metal), alkaline earth metal (alkaline earth met)
al) or the like, or carbon, transition metal oxide / sulfide, organic compound, polymer compound or the like can be used. Preferably, carbon material or polymer material can be used. The active material is preferably selected according to the battery performance or application.

The conductive material is a material added to the positive electrode or the negative electrode for the purpose of improving conductivity, and carbon is generally used. Among them, graphite
, Cokes, activated carbon and carbon black are preferable, and graphite and carbon black are more preferable. One or more conductive materials selected from the above group are used, and either synthetic products or natural substances may be used. The conductive material is added in an amount of 3 wt% to about 15 wt% of the total weight of the electrode material, and the conductive material is added in an amount of about 3 wt%.
When the amount is less than the following, the electrical conductivity is lowered, and there may be a problem that an overvoltage occurs. On the other hand, when the content is about 15% by weight or more, there is a problem that the energy density per unit volume decreases and the side reaction by the conductive material becomes serious.

The binder is added to strengthen the bond of the active material layer, and a polymer compound is mainly used. The above-mentioned polymer compound used when producing a solid electrolyte membrane can also be used as a binder, and is the same as the polymer of the electrolyte membrane or compatible (
It is preferable to use one having miscibility). The binder is added in up to about 15% by weight of the total weight of the electrode material. When the amount of the binder added is small, the binding force of the electrode may be reduced, and when it is about 15% by weight or more, the workability and porosity of the electrode may be reduced.

The additive is a material added for the purpose of improving the performance of the battery or the electrode, and can be variously selected according to the intended performance and application. Improve the binding force inside the electrode plate or with the current collector, induce the porosity or non-crystallinity of the electrode plate, improve the degree of dispersion of the electrode plate constituent materials or the efficiency of the electrode manufacturing process, or the active material. Is added for the purpose of improving performance such as suppressing overcharging / overdischarging, recombining or removing side reaction products, or improving absorption of the liquid electrolyte. Generally, salts, organic / inorganic compounds, minerals, and polymer compounds are used as the additives, and the electrolyte membrane is used to improve the absorption capacity for liquid electrolyte and form a continuous phase with the electrolyte. It is preferred that the absorbent added to is added.

In summary, the solid electrolyte of the present invention and the secondary battery using the same have the following features as compared with the prior art.

1. The manufacturing process and material conditions are simple. Since it is easy to form a film and has excellent porosity by a simple method such as a wet method, a conventional technique for introducing porosity, that is, a manufacturing method by vulcanization, curing and stretching, particularly a plasticizer / step It is much simpler than the manufacturing method using an auxiliary agent. At the same time, the electrolyte membrane of the present invention has a simple structure consisting only of a large amount of an inorganic absorbent and a small amount of a polymer binder, and includes a plasticizer / process aid, a curable polymer, a crosslinked polymer or a fibrous polymer. No structure is needed.

Second, the performance and stability as an electrolyte are excellent. Since the ions are conducted in the liquid phase impregnated in the porous structure, the ionic conductivity is high. Low polymer content and high inorganic absorbent content means that ionic conductivity is not significantly affected by temperature, mechanical, thermal and electrochemical stability is large, and bulk change is small, resulting in dimensional stability. . It has a wide potential window and has a large resistance to ignition or explosion. In particular, the inorganic absorbent contained in a specific amount or more acts as a structure, improves resistance to lamination or pressing, and has little electrolyte performance reduction after battery assembly.

Third, the battery assembly process is simple. A special dehumidifying environment is not required during the electrolyte membrane manufacturing and battery assembly process, and the manufacturing process is simple because it is not affected by moisture or temperature after the battery assembly and before the activation process of impregnating the liquid electrolyte. And it is easy to automate.

[0060]

【Example】

In this example, the solid electrolyte according to the present invention and a method for manufacturing a battery using the solid electrolyte will be described in detail. A solid electrolyte was manufactured and a performance test was performed. Furthermore, a method of assembling a positive electrode and a negative electrode together with a solid electrolyte to manufacture a battery and inspecting its performance will be described. However, these embodiments do not limit the content of the present invention, and various applications and modifications are possible within a range not departing from the basic gist of the present invention.

[0061]Example 1 (wet method: experiment according to type and content of inorganic absorbent and type of liquid electrolyte) )   A polymer binder solution was prepared by dissolving 14 g of PVdF in 86 g of NMP. This
The absorbent was added thereto and mixed until the absorbent particles were completely dispersed. Absorbent particles
Ultrasonic agitation was performed for 30 minutes to prevent them from aggregating with each other. Blend produced by the above method
The mixed solution was coated on a glass plate to a thickness of about 100 μm. Coe
Immediately soak the coated film in the non-solvent tank for about 10 minutes, then take out the film.
It was dried at 70 ° C. for about 1 hour. Porous electrolyte produced by this method
Soak the membrane in the liquid electrolyte solution for about 10 minutes, before and after the liquid electrolyte is completely absorbed.
Ion conductivity was measured using the AC impedance method.
.

The characteristics and conductivity of the porous solid electrolyte according to the kind and content ratio of the inorganic absorbent and the binder are summarized in Table 1 below. In order to compare the ability of the porous electrolyte membranes to absorb the liquid electrolyte, the absorption (absorption capacity, Δab) was defined as follows.

[0063] Δab = [amount of absorbed liquid electrolyte (mg)] / [weight of electrolyte membrane (mg)]

When the volume ratio of the solvent constituting the liquid electrolyte is not specified below, it means that they are mixed in the same volume.

[0065]

[Table 1]

The “mechanical strength” in the above Table 1 and the following Table 2 is evaluated in the form of the electrolyte membrane or in the state of being impregnated with the liquid electrolyte, and therefore is strong against lamination or pressing in the battery assembly process. It does not mean to have resistance. In other words, even if the mechanical strength in the table is excellent, the properties may differ in the actual battery assembly process depending on the content of the absorbent.

[0067]Example 2 (wet method: experiment depending on binder type)   An experiment was conducted in the same manner as in Example 1 except for the type of binder, and the results are shown in Table 2 below.
Summarized.

[0068]

[Table 2]

[0069]Example 3 (dry method)   In a 20 ml glass vial, 0.5 g of P (VdF-HFP) was added.
A polymer binder solution was prepared by dissolving it in 8 g of acetone. Paragonite here
1.17 g was added and continuously stirred until the particles were completely dissolved. Inorganic absorbent grain
Sonicate for 30 minutes to prevent the pups from clumping together. Insoluble in this mixture
0.9 g of ethylene glycol as a medium, Triton X-10 as an absorption aid
0.1 g and 1.8 g of a pore-forming agent, isopropanol, were added.
The mixture was ultrasonically stirred for about 10 minutes until it was uniformly mixed. Blends produced by the above method
Coat the mixed solution on a glass plate to a thickness of about 100 μm, then
After drying at 0 ° C for about 2 hours, 6 in a vacuum dryer controlled at 50 ° C
It was further dried for about an hour. The electrolyte membrane manufactured by the above method is EC / DEC 1M
LiPF₆Immerse in the solution for about 10 minutes, and after the liquid electrolyte is completely absorbed,
The Δab value calculated by measuring the weight change is 7.5.
The room temperature ionic conductivity measured and utilized was 2.0 mS / cm.

[0070]Example 4 (Comparative Example: Non-porous solid electrolyte production experiment)   A polymer binder solution was prepared by dissolving 14 g of PVdF in 86 g of NMP.
Add 2g of paragonite powder to 1.85g of polymer binder solution and mix the particles completely.
Stir until stirred. Supersonic for 30 minutes to prevent the absorbent particles from agglomerating with each other
Wave stirred. The mixed solution prepared by the above method is applied on a glass plate to a thickness of about 100 μm.
After coating, dry at room temperature for about 2 hours and adjust to about 50 ° C.
It was further dried for 6 hours in a knotted vacuum dryer. The electrolyte membrane produced by the above method is
C / DMC 1M LiPF₆Immerse in solution for about 10 minutes and completely absorb liquid electrolyte
After measuring the change in weight before and after, the conductivity is measured using the AC impedance method.
It was measured. The lithium ion conductivity was 0.72 mS / cm at room temperature.
. The ionic conductivity is slightly insufficient for practical use in batteries. In this example,
Unlike the above-mentioned Examples 1 to 3, the steps for forming a porous structure were not performed.
Based on this result, in order to improve the battery performance, many methods such as wet method or dry method are used.
It can be seen that an additional porosity introduction process is required.

[0071]Example 5 (electrochemical stability experiment)   To measure the electrochemical stability of porous solid electrolytes, stainless steel (
# 304) as the working electrode and lithium metal as the counter electrode and the reference electrode.
A linear sweep voltammetry was performed. Electric
The scanning range is from open circuit voltage to 5.5V, and potential scanning speed is 10 mV / s.
ec. Methods of Examples 1- (h), 1- (l), 1- (n) and 2- (s)
The results of the linear potential scanning analysis of the porous solid electrolyte produced by
It is shown in B, C and D. As shown in FIG. 1, the solid electrolyte manufactured according to the present invention has a solid electrolyte of 4.
Electrochemically stable up to 8V. Synthetic oxide absorbent (Zeora) from natural mineral absorbent
Ito) is more stable.

[0072]Example 6 (battery performance experiment)   To test the battery performance using a solid electrolyte, the battery was constructed as follows. The positive electrode
, Lithium transition metal oxide active material, conductive material carbon powder, polymer binder and additives
82: 7: 8: 3 by weight, mixed as a slurry, coated on an aluminum grid and dried.
I made it. The negative electrode contains artificial graphite, conductive carbon powder, polymer binder and additives.
Slurry mixture at 5: 3: 10: 2 weight ratio, applied on copper grid and dried
Made Laminate the positive electrode, the electrolyte membrane, and the negative electrode three rows at the same time.
After forming the battery and absorbing the liquid electrolyte, film packaging leaving only the electrode terminals
Sealed with wood. A charge / discharge test of the battery manufactured through the above process was performed. Reversible capacity
The constant voltage of the rate (C / 2 rate) to charge the battery in 2 hours, the battery voltage to 4.2V
Applied until the voltage reaches 4.2V and the constant potential is applied again, and the current decreases to C / 10 mA.
Charged up. After that, up to 2.5V or 2.75V for 2 hours at the discharge rate of current
It was discharged (C / 2 rate). By repeating the above charging and discharging,
The change in discharge capacity was observed. The battery configuration and test results are summarized in Table 3 below.
It is shown in FIG. As shown in Table 3, each solid electrolyte absorbs the corresponding liquid electrolyte in the electrolyte membrane.
Represents the state of being stored. In addition, the solid electrolyte produced in Example 4 was tested by the battery.
Did not apply to.

[0073]

[Table 3]

FIG. 2 shows, for each example, each discharge capacity obtained by repeating the charge / discharge test of the battery in comparison with the discharge capacity at the first time. From the above battery test results, when using the solid electrolyte obtained from the wet method (Examples 1 and 2) (Example 6-u)
, V, x) are superior in performance to the case where the solid electrolyte obtained from the dry method (Example 3) is used (Example 6-w). In other words, the performance difference (ionic conductivity, mechanical strength, etc.) is not great only with the electrolyte membrane or the solid electrolyte itself,
In fact, the result of applying the battery shows that the one manufactured by the wet method using the inorganic absorbent has a more desirable effect on the overall battery performance (charge / discharge performance, etc.).

[0075]Example 7 (Physical property experiment by changing the content of paragonite used as an inorganic absorbent) )   In the same manner as in Example 1, the content of the paragonite powder as the inorganic absorbent was changed.
About 10 cm^TwoThe size of the porous solid electrolyte membrane is controlled by a laboratory press.
At 130 ° C. for 15 seconds at 1 metric ton
Pressed with pressure. Observe the thickness change before and after pressing, and
Using the pedance method, measure the change in ionic conductivity before and after pressing and
Based on the film thickness and ionic conductivity before pressing shown in Table 4,
Each value after singing is shown in percentage in FIG. Used when measuring ionic conductivity
The prepared liquid electrolyte is EC / DMC / DEC 1M LiPF₆Is.

[0076]

[Table 4]

From the measurement results, when the content of the inorganic absorbent is 70% by weight or more (Example 7-
After cc), it can be seen that the film thickness and ionic conductivity after pressing do not change much compared to before pressing. That is, it is understood that the difference in ionic conductivity of the electrolyte membrane or the solid electrolyte itself does not largely depend on the content of the inorganic absorbent, but the effect of the content increases after the pressing process.

[0078]Example 8 (Physical property experiment by changing content of zeolite as inorganic absorbent)   The same experiment as in Example 7 was carried out using zeolite as the inorganic absorbent. Press
The changes in the ionic conductivity of the electrolyte membrane before and after singing were measured and are shown in Table 5 below.

[0079]

[Table 5]

Similar to the results of Example 7 above, when the content of the inorganic absorbent was 70% or more (
It is understood that the decrease in the thickness and the ionic conductivity before and after pressing is not significant in Examples 8-ll and later). When the results of Example 7 are summarized, it is found that such a characteristic phenomenon is not largely related to the type of the inorganic substance, and the battery is assembled by lamination or pressing using the electrolyte to measure the performance. if,
It can be expected that the battery performance is significantly different depending on the content of the inorganic substances.

[0081]Example 9 (Battery performance experiment by changing kind and content of inorganic absorbent)   A battery was constructed in the same manner as in Example 6 to change the type and content of the inorganic absorbent.
We investigated the impact of this. The charging / discharging method of the manufactured battery is the same as that of the sixth embodiment. Electric
The pond composition and test results are summarized in Table 6 below and shown in FIG. 4 or FIG. Open in Table 6
As shown, each solid electrolyte is in a state where the electrolyte membrane absorbs the corresponding liquid electrolyte.
It

[0082]

[Table 6]

From the above battery test results, in the case of using the solid electrolyte having the content of the inorganic absorbent of 70% by weight or more (Example 9-tt, uu or Example 9-xx, yy),
It can be seen that the performance is better than the other cases. Summarizing the results of Example 7, Example 8 and this example, although the electrolyte membrane or the solid electrolyte itself does not cause a large difference in performance such as ionic conductivity and mechanical strength depending on the content of the absorbent, an actual battery is manufactured. In this case, it can be seen that the effect of the absorbent content is large because the lamination or pressing process is performed. The content of inorganic absorbent is at least 7
It can be seen that when the content is 0% by weight or more, the ability to absorb the liquid electrolyte is not lost even after the battery is assembled, so that the battery performance is excellently influenced. Furthermore, the phenomenon is
It can be confirmed that they are common regardless of the type of inorganic absorbent.

[0084]

【The invention's effect】

According to the present invention, a solid electrolyte having excellent ion conductivity and a solid electrolyte thereof are produced by allowing a liquid electrolyte to be smoothly sucked into an electrolyte membrane to which an absorbent has been added to provide porosity. A method and a lithium secondary battery using such a solid electrolyte as an electrolyte are provided. The solid electrolyte of the present invention has the advantages that the manufacturing process and material conditions are simple, the performance and stability as an electrolyte are excellent, and the battery using the solid electrolyte is easy to assemble. In particular, due to the feature that the inorganic absorbent is added in a specific amount or more, in the lamination or pressing step, since it maintains the porosity of the electrolyte membrane and the liquid electrolyte absorption capacity,
Not only the performance of the solid electrolyte itself, but also excellent performance can be maintained after the battery is assembled.

[Brief description of drawings]

FIG. 1 shows the results of an experiment by a linear potential scanning method for measuring the electrochemical stability of the solid electrolyte of the present invention.

FIG. 2 shows a change in discharge capacity of a battery using the solid electrolyte of the present invention by a charge / discharge experiment.

FIG. 3 is a diagram showing changes in thickness and ionic conductivity of a film manufactured by changing an inorganic electrolyte content, relative to an initial value.

FIG. 4 is a graph showing a change in discharge capacity of a battery using the solid electrolyte of the present invention during a charge / discharge experiment.

FIG. 5 shows a change in discharge capacity of a battery using the solid electrolyte of the present invention during a charge / discharge experiment.

─────────────────────────────────────────────────── ─── Continued front page    (71) Applicants Kim and Han Jun             South Korea, Seoul 122-012, Yumpyeong             -Gu, Yungham-Don, 231-25 (72) Inventor Jean, Dong Hoon             Republic of Korea, Seoul 132-033, Dobon-             Gu, Sangmun-dong, 388-33, Hanyang               Apartment, 8-403 (72) Inventor Kim, Suffum             Republic of Korea, Kyung-gee-do, Kumpo-shite             435-050, Kumjeong-don, 880,             Hansan Mokuwa Apartment, 132-1202 (72) Inventor Kim, Han Jun             South Korea, Seoul 122-012, Yumpyeong             -Gu, Yungham-Don, 231-25 F-term (reference) 5H029 AJ06 AK03 AL07 AL08 AM03                       AM04 AM05 AM07 AM12 AM16                       CJ02 CJ03 CJ05 CJ12 DJ09                       EJ05 EJ12 HJ01 HJ04 HJ05                       HJ09 HJ10

Claims (8)

[Claims] 1. A solid electrolyte for a secondary battery comprising an electrolyte membrane having a thickness of 20 to 200 μm and having a fine porous structure, and an ion conductive liquid electrolyte, wherein the electrolyte membrane does not contain a liquid electrolyte. An inorganic absorbent having a particle diameter of 40 μm or less, which is at least 70% by weight based on the total weight of the electrolyte membrane in a dry state, and a polymer binder, and further, the content of the ion conductive liquid electrolyte is A solid electrolyte for a secondary battery, which is 20 to 90% by weight based on a total weight of an electrolyte including a liquid electrolyte. 2. The solid electrolyte for a secondary battery according to claim 1, wherein the content of the inorganic absorbent is 70 to 95% by weight. 3. The inorganic absorbent is mineral particles having a phyllosilicate structure such as clay, paragonite, montmorillonite, mica; zeolite, porous silica,
One or two selected from the group consisting of porous alumina, compatible oxide particles such as magnesium oxide; mesoporous molecular sieve made of oxide or polymer material having a pore diameter of 2 to 30 nm; and commercially available absorbent. The above-mentioned mixture, and the polymer binder is polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, a copolymer of vinylidene fluoride and maleic anhydride, polyvinyl chloride, polymethylmethacryl Rate, polymethacrylate, cellulose triacetate, polyurethane, polysulfone, polyether, polyethylene, polypropylene, polyethylene oxide, polyisobutylene, polybutyldiene, polyvinyl alcohol, polyacrylonitrile, polyimide, polyvinyl formal, acrylate Ronitrile butyl diene rubber, ethylene propylene diene monomer, tetraethylene glycol diacrylate, polydimethyl siloxane, polycarbonate, and one or more polymer mixtures selected from the group consisting of silicone polymers or copolymers thereof The solid electrolyte for a secondary battery according to claim 1, which is a polymer or a polymer mixture. 4. In the electrolyte membrane, an inorganic absorbent is dispersed in a solution consisting of a polymer binder and a solvent for the polymer binder, the inorganic absorbent is molded into a membrane form, and then the solvent is replaced with a non-solvent for the polymer binder. The solid electrolyte for a secondary battery according to claim 1, which is manufactured by a wet method of drying and drying. 5. The solvent of the polymer binder is NMP (N-methyl p).
yrrolidinone), dimethylformamide, dimethylacetamide,
One or a mixture of two or more selected from the group consisting of tetrahydrofuran, acetonitrile, cyclohexanone, chloroform, dichloromethane, hexamethylphosphoamide, dimethylsulfoxide, acetone and dioxane; and the non-solvent of the polymer binder is , A mixture of two or more selected from the group consisting of water, ethanol, ethylene glycol, glycerol, acetone, dichloromethane, ethyl acetate, butanol, pentanol, hexanol and ether. The solid electrolyte for a secondary battery according to claim 4. 6. The solid electrolyte is produced by an activation process in which an ion conductive liquid electrolyte is absorbed by an electrolyte membrane, and the ion conductive liquid electrolyte is ethylene carbonate, propylene carbonate or butylene carbonate. , Dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, gamma-butyrolactone, 1,3-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, sulfolane, N, N-dimethylformamide, diglyme, triglyme and tetraglyme. in an organic solvent consisting of one or a mixture of two or more selected from the group consisting _{of, LiClO 4, LiBF 4, LiPF} 6, LiAsF 6, LiSCN, LiCF 3 SO 3, LiN (CF 3 SO 2) 2 and LiC ( selected from the group consisting of CF ₃ SO _{2) 3} One or two or more claims 1, characterized in that it is obtained by dissolving at 0.5~2M concentration of lithium salt to a solid electrolyte for a secondary battery according to any one of 4 that. 7. An inorganic absorbent having a particle size of 40 μm or less is dispersed in a solution comprising a polymer binder and a solvent at a weight ratio of 70/30 to 95/5 with respect to the polymer binder, and then obtained. The obtained mixture is formed into a film form, and then the solvent is exchanged with a non-solvent for the polymer binder, and then dried to obtain fine pores having a diameter of 20 μm or less, a porosity of 5 to 95%, and a thickness. Of 20 to 200 μm is formed, then the obtained electrolyte membrane is arranged between the positive electrode and the negative electrode, laminated and bonded by lamination or pressing to assemble into a battery form, and then ion conductive. A lithium secondary battery, which is manufactured by absorbing a liquid electrolyte. 8. The positive electrode and the negative electrode are separately prepared from the electrolyte membrane,
Alternatively, the polymer binder used for the negative electrode is the same as or compatible with the polymer binder for the electrolyte membrane, and the additive used for the positive electrode and / or the negative electrode is selected from among the absorbents used for the electrolyte membrane. The lithium secondary battery according to claim 7, which is one or a mixture of two or more selected.