WO2018236064A1 - Multilayer polymer solid electrolyte and all-solid-state battery comprising same - Google Patents

Abstract

The present invention relates to a multilayer polymer electrolyte and an all-solid-state battery comprising the same. When the multilayer polymer solid electrolyte comprising a first polymer electrolyte layer and a second polymer electrolyte layer, of the present invention, is used, stable use thereof in a high-voltage cathode and a low-voltage anode is possible, and an all-solid-state battery comprising the same can be applied to the field of batteries for electric vehicles in which a high-capacity and a high-output battery is used.

Description

Multi-layered polymer solid electrolyte and all solid-state cell including the same

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0077792, filed on June 20, 2017, and Korean Patent Application No. 10-2018-0059591, dated May 25, 2018, All of which are incorporated herein by reference.

The present invention relates to a multi-layered polymer solid electrolyte and a pre-solid battery including the same.

Lithium secondary batteries have been mainly applied to small-sized applications such as mobile devices and notebook computers. Recently, however, their research directions have been expanded to middle and large-sized fields. They are mainly used in energy storage systems (ESS) vehicle, and the like.

In the case of such a large-sized lithium secondary battery, unlike a small-sized battery, operating environment (for example, temperature, shock) is not only severe but also requires more batteries. Therefore, have.

Most commercialized lithium secondary batteries use an organic liquid electrolyte in which a lithium salt is dissolved in a flammable organic solvent, which poses a potential risk of leakage, explosion, and ignition. In fact, since the explosion of products using this product is constantly reported, it is urgent to overcome these problems.

If it is to be solved by a safety device, there is a risk that the energy density is lost due to a considerable weight of the safety device, and basically, there is a limit to overcome the safety problem by using the organic liquid electrolyte.

Therefore, the development of all solid-state cells using solid electrolytes instead of liquid electrolytes has been underway. Since all solid batteries do not contain a flammable organic solvent, they are advantageous in that a safety device can be simplified, and thus it is recognized that the battery is excellent in manufacturing cost and productivity. Further, since it is easy to laminate in series a junction structure including a pair of electrode layers including a positive electrode (positive electrode) layer and a negative electrode (negative electrode) layer and a solid electrolyte layer interposed between these electrode layers, And is expected to be a technology capable of manufacturing a high-output battery.

Conventional solid electrolytes have been applied / evaluated to lithium metal batteries using lithium metal cathodes or lithium ion batteries using graphite cathodes because they are made of one solid polymer electrolyte film and serve as electrolytes and separation membranes. However, as a polymer electrolyte, it is difficult to realize a battery that operates stably simultaneously on the anode in the high voltage region and on the cathode in the low voltage region. For example, there is a problem that the polymer electrolyte is oxidized at the surface of the anode in the high voltage region or reduced / decomposed at the surface of the cathode in the low voltage region, and the interface resistance between the electrode and the electrolyte increases due to the adhesive force member only with the single polymer electrolyte do.

The polymer electrolyte containing succinonitrile has a high ionic conductivity of 10 ^-4 S / cm or higher at room temperature and operates stably at the anode at a high voltage range of 4 V or more, but the stability at the cathode at the low voltage region is weak Which is difficult to apply to Li metal and graphite cathodes, and is limited to LTO (Lithium Titanate) cathodes with operating voltages of about 1.5V. On the other hand, the polymer electrolyte based on PEO (Polyethylene Oxide) is stable in the low voltage range and can operate on the lithium negative electrode and the graphite negative electrode. On the other hand, it is difficult to apply it to the high voltage positive electrode of 4V or more.

In order to solve various problems of the prior art, a method of manufacturing an inorganic solid electrolyte and a polymer electrolyte in a multi-layer form has been proposed. However, a multi-layer structure of a polymer solid electrolyte stable in both an anode in a high voltage region and a cathode in a low- Research has not been done.

Therefore, LCO (Lithium Cobalt Oxide), LNMO (LiNI 0. 5 Mn 1. 5 O 4) , such as the positive electrode material can be a cathode material is used, such as the positive electrode and Li metal and graphite at the high voltage areas that may be used in low-voltage region in the It is required to develop a polymer solid electrolyte having a multi-layer structure capable of stably operating at the same time on the cathode.

[Prior Art Literature]

[Patent Literature]

(Patent Document 1) Japanese Laid-Open Patent Application No. 2014-523068 (2014.09.08), "New Polymer Electrolyte and Lithium Secondary Battery Containing It"

 (Patent Document 2) Korean Unexamined Patent Publication No. 2003-0005254 (2003.01.17), " Multilayered Polymer Electrolyte and Lithium Secondary Battery Including the Same "

 [Non-Patent Document]

(Non-Patent Document 1) Weidong Zhou, Shaofei Wang, Yutao Li, Sen Xin, Arumugam Manthiram, and John B. Goodenough, Plating a Dendrite-Free Lithium Anode with a Polymer / Ceramic / Polymer Sandwich Electrolyte. J. Am. Chem . Soc . 2016, 138, 9385-9388

(Non-Patent Document 2) Pierre-Jean Alarco, Yaser Abu-Lebdeh, Ali Abouimrane and Michel Armand: The plastic-crystalline phase of succinonitrile as a universal matrix for solid-state ionic conductors , Nat. Mater . 2004, 4, 476-481.

The present applicant has conducted various studies in order to realize a battery which operates at the same time and stably at the anode in the high voltage range and the cathode in the low voltage range and has developed a multi-layered structure with different composition of each layer As a result of applying the solid electrolyte to the whole solid battery, the result of stable operation at the anode in the high voltage region and the cathode in the low voltage region was confirmed and the present invention was completed.

An object of the present invention is to provide a multi-layered polymer electrolyte for an all solid-state battery comprising a first polymer electrolyte layer and a second polymer electrolyte layer.

Another object of the present invention is to provide a pre-solid battery including the multi-layered polymer electrolyte.

In order to accomplish the above object, the present invention provides a lithium ion secondary battery comprising a first polymer electrolyte layer comprising an aliphatic dinitrile compound represented by the following general formula (1), a lithium salt and a lithium ion conductive polymer, an ionic liquid, a lithium salt and a lithium ion conductive polymer And a second polymer electrolyte layer including the second polymer electrolyte layer.

[Chemical Formula 1]

N≡C-R-C≡N

(Wherein, R is (CH _{2) n} is an integer of n = 1 to 6)

The first polymer electrolyte layer may include 20 to 50 parts by weight of an aliphatic dinitrile compound and 30 to 40 parts by weight of a lithium salt based on 100 parts by weight of the lithium ion conductive polymer.

The second polymer electrolyte layer includes 20 to 50 parts by weight of an ionic liquid and 30 to 40 parts by weight of a lithium salt based on 100 parts by weight of the lithium ion conductive polymer.

The present invention also provides a pre-solid battery comprising the multi-layered polymer electrolyte.

When the polymer electrolyte of the present invention is applied to all solid-state cells, there is no electrolyte decomposition at the anode in the high-voltage region appearing in the liquid electrolyte, so that the polymer electrolyte can be applied to a high- In addition, the present invention can be applied to a cathode in a low voltage region of 1.5 V or less without side reactions and surface reactions, and can simultaneously operate stably on both an anode in a high voltage region and a cathode in a low voltage region.

Such a pre-solid battery is suitably applicable in a battery field of an electric vehicle in which a high capacity, high output battery is used.

1 is a cross-sectional view of a pre-solid battery including a multi-layered polymer electrolyte.

2 is a cross-sectional view of a pre-solid battery.

3 is a photograph showing the first polymer electrolyte and the second polymer electrolyte.

4 is a graph showing the voltage stability of the multi-layered polymer electrolyte.

5 is a graph showing the voltage stability of the first polymer electrolyte layer.

6 is a graph showing the voltage stability of the second polymer electrolyte layer.

The present invention provides a lithium secondary battery comprising: a first polymer electrolyte layer comprising an aliphatic dinitrile compound represented by the following formula (1), a lithium salt, and a lithium ion conductive polymer; And a second polymer electrolyte layer including an ionic liquid, a lithium salt, and a lithium ion conductive polymer. The present invention also provides a multi-layered polymer electrolyte for an all solid-state battery.

[Chemical Formula 1]

N≡C-R-C≡N

(Wherein, R is (CH _{2) n} is an integer of n = 1 to 6)

In addition, the polymer electrolyte of the present invention has a multilayer structure, and the polymer electrolyte contacting the anode in the entire solid electrolyte cell exhibits stable performance without being decomposed in a high voltage region like a liquid electrolyte, and the polymer electrolyte contacting the cathode undergoes reduction and decomposition in a low- Polymer electrolyte and an all solid battery including the polymer electrolyte. Hereinafter, the present invention will be described in detail with reference to the drawings.

Multilayered polymer electrolyte

1 is a cross-sectional view of a multi-layered polymer electrolyte for a solid battery.

1, all solid state batteries 100 and 200 have a structure in which anodes 110 and 210, cathodes 170 and 250, and a polymer electrolyte layer 130 and 150 are interposed therebetween. The polymer electrolyte layer has a multi-layer structure and is composed of the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 from the side in contact with the anodes 110 and 210.

The entire solid state batteries 100 and 200 according to the present invention realize a multi-layered electrolyte using a polymer electrolyte. As a result, compared with a battery made of a conventional polymer electrolyte, a battery which stably operates both in a high voltage region and in a low voltage region. . Conventional polymer electrolytes were fabricated as a single polymer electrolyte membrane and acted as an electrolyte and a separator. As a polymer electrolyte, there was a difficulty in realizing a battery that operates stably at the anode of the high voltage region and the cathode of the low voltage region at the same time. In addition, the interface resistance between the electrode and the electrolyte was increased due to the absence of the adhesive force by the single polymer electrolyte alone. However, as shown in FIG. 1, this problem is solved by implementing a multi-layered polymer electrolyte.

According to the prior art ( J. Am. Chem . Soc . 2016, 138, 9385-9388), the voltage profile in a multi-layered electrolyte composed of polymer and ceramic is close to 0 V on the cathode side and high voltage on the anode side . Such a multi-layered solid electrolyte is mostly composed of a combination of a polymer and a ceramic. However, there is no example in which a whole electrolyte is composed of a polymer, and two solid polymers or two or more polymer electrolytes are combined according to their use and characteristics to realize an all solid battery.

 The present invention relates to a polymer solid electrolyte exhibiting stable performance characteristics without decomposition in a high voltage region such as a liquid electrolyte such as a liquid electrolyte and exhibiting voltage stability in which a reduction and decomposition does not occur in a low voltage region close to 0 V at the cathode, And the like. In particular, the polymer electrolyte of the present invention has a multilayer structure, and has an advantage that the operating voltage in each layer can be controlled by varying the composition of each layer.

First polymer Electrolyte layer

The first polymer electrolyte layer 130 of the present invention includes an aliphatic dinitrile compound represented by the following formula (1), a lithium salt, and a lithium ion conductive polymer.

[Chemical Formula 1]

N≡C-R-C≡N

(Wherein, R is (CH _{2) n} is an integer of n = 1 to 6)

When an aliphatic dinitrile compound is contained, the ionic conductivity of the polymer electrolyte at room temperature is 10 ^-4 S / cm And the electrolyte is not oxidized at the surface of the electrode in the anode at a high voltage region of 4 V or more as compared with the liquid electrolyte, so that it is possible to exhibit stable performance and effects as compared with the case where the aliphatic dinitrile compound is not contained.

Since the chain length of the aliphatic dinitrile compound does not greatly affect the performance and safety of the whole solid battery or rather adversely affects the performance of the cell, the number of aliphatic hydrocarbons including succinonitrile is 1 to 6 (N≡CRC≡N, n = 1 to 6), and it is more preferable to select a nitrile having a small number of carbon atoms, among which succinonitrile is most preferable. On the other hand, the aromatic nitrile and the fluorinated aromatic nitrile compound among the compounds containing a cyano functional group are not preferable because they easily decompose electrochemically in the entire solid-state cell to interfere with the migration of Li ions to deteriorate the performance of the battery.

The first polymer electrolyte layer 130 is prepared by selecting 20 to 50 parts by weight of the aliphatic dinitrile compound per 100 parts by weight of the lithium ion conductive polymer. If the amount of the aliphatic dinitrile compound is less than 20 parts by weight, the effect of the aliphatic dinitrile compound is insignificant. Therefore, the ionic conductivity is appropriately controlled within the above range. When the aliphatic dinitrile compound is used in an amount of 35 to 45 parts by weight, oxidation stability and ionic conductivity at the high-voltage anode can be remarkably increased.

The first polymer electrolyte layer may have an ionic conductivity of 5 x 10 ^-5 S / cm to 5 x 10 ^-4 S / cm.

Examples of the lithium ion conductive polymer in the first polymer electrolyte layer 130 include polyethylene glycol diacrylate (PEGDA), trimethylolpropaneethoxylate triacrylate (ETPTA), polyacrylonitrile (PAN), polypropylene oxide PPO), polypropylene carbonate (PPC), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF) (PA), polyethylene (PE), polyethylene glycol (PEG) and polystyrene (PS), or a combination thereof, preferably an acrylate-based polymer, more preferably , Trimethylolpropaneethoxylate triacrylate (ETPTA) can be used.

The lithium salt commonly applied to the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 according to the present invention is dissociated into lithium ions to form the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 ) To move freely. At this time, as a source of lithium ions and enables the basic operation of a lithium battery, so long as it is generally used in such lithium salts include a lithium battery can be used both one, preferably LiCl, LiBr, LiI, LiClO _4, LiBF _4, LiB _{10 Cl 10, LiPF 6, LiCF} 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, CH 3 SO 3 Li, CF 3 SO 3 Li, LiSCN, LiC (CF 3 SO 2) 3, ( CF ₃ SO ₂ ) ₂ NLi, (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, chloroborane lithium, lithium lower aliphatic carboxylate, lithium 4-phenylborate, , And more preferably LiTFSI (lithium bis (trifluoromethanesulfonyl) imide) represented by (CF ₃ SO ₂ ) ₂ NLi.

In the first polymer electrolyte layer 130, 30 to 40 parts by weight of the lithium salt is selected for 100 parts by weight of the lithium ion conductive polymer.

The second polymer Electrolyte layer

The second polymer electrolyte layer 150 includes an ionic liquid, a lithium salt, and a lithium ion conductive polymer.

The ionic liquid is ionic salts or molten salts which are composed of cations and anions. Ionic compounds such as salt, which are composed of cationic and nonmetal anions, are generally referred to as ionic liquids, which dissolve at a high temperature of 800 ° C or higher, and exist as liquids at a temperature of 100 ° C or lower. Particularly, an ionic liquid present as a liquid at room temperature is referred to as a room temperature ionic liquid (RTIL).

Ionic liquids are nonvolatile, non-toxic, non-flammable, and have excellent thermal stability and ionic conductivity compared to conventional liquid electrolytes. In addition, since the polarity is high, it dissolves inorganic and organometallic compounds well and has a unique characteristic of being present as a liquid in a wide temperature range. Therefore, it has the merit of obtaining various characteristics by changing the structure of cations and anions constituting the ionic liquid And is applied to a wide range of chemical fields such as catalyst, separation, and electrochemical.

Since the multi-layered polymer electrolyte for an all solid-state battery according to an embodiment of the present invention contains such an ionic liquid, the stability of the battery in the negative electrode in the low-voltage region is greatly improved. Further, since the ionic liquid has excellent thermal stability and excellent ionic conductivity, when the ionic liquid is added to the polymer electrolyte, the thermal stability can be improved without decreasing the ionic conductivity. Since the ionic liquid has high polarity and dissolves inorganic and organic metal compounds well and exists as a liquid even in a wide temperature range, it can be added to the composition for forming a polymer electrolyte through simple mixing and heating.

The ionic liquid according to the present invention may include a cation and an anion. The cation of the ionic liquid is preferably a cation of a heterocyclic compound, and the hetero atom of the heterocyclic compound is N, O, S, ≪ / RTI > and combinations thereof. Examples of the cation of such a heterocyclic compound include pyridinium, pyridazinium, pyrimidinium, pyrazinium, pyrazolium, thiazolium, oxazolium ( oxazolium, triazolium, pyrrolidinium, piperidinium, imidazolium, and combinations thereof may be preferably used as the cation of the compound selected from the group consisting of oxazolium, triazolium, pyrrolidinium, piperidinium, imidazolium and combinations thereof.

The ionic liquid according to the present invention may be formed of a combination of a cation and an anion, and examples of the anion of the ionic liquid include bis (perfluoroethylsulfonyl) imide, bis (trifluoromethylsulfonyl) imide , Bis (fluorosulfonyl) imide, tris (trifluoromethylsulfonylmethide), trifluoromethanesulfonimide, trifluoromethylsulfonimide, trifluoromethylsulfonate, tris (pentafluoro (Trifluoromethylsulfonyl) imide, tetrafluoroborate, hexafluorophosphate, and combinations thereof may be preferably used as the anion of the compound selected from the group consisting of bis (trifluoromethyl) trifluoroacetate, bis (trifluoromethylsulfonyl) imide, tetrafluoroborate, hexafluorophosphate and combinations thereof.

The second polymer electrolyte layer 150 may be manufactured by selecting the range of 20 to 50 parts by weight of the ionic liquid relative to 100 parts by weight of the lithium ion conductive polymer. When the content of the ionic liquid is less than 20 parts by weight, the effect of improving the swelling and the ion conductivity is not exhibited. When the ionic liquid is more than 50 parts by weight, the breakdown of the negative electrode and the decrease of the ionic conductivity occur. When the ionic liquid is used in an amount of 35 to 45 parts by weight, the reduction, decomposition stability and ionic conductivity of the electrolyte can be remarkably increased in the negative electrode in the low voltage region.

The second polymer electrolyte layer may have an ionic conductivity of 1 x 10 ^-6 S / cm to 1 x 10 ^-4 S / cm.

The lithium ion conductive polymer of the second polymer electrolyte layer 150 may be the same as or different from that of the first polymer electrolyte layer 130, and preferably the same one is used in view of process convenience.

The lithium salt commonly applied to the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 according to the present invention is dissociated into lithium ions to form the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 ) To move freely. In this case, a basic lithium battery can be operated as a supply source of lithium ions. The lithium salt can be any LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , _{LiB 10 Cl 10, LiPF 6,} LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, CH 3 SO 3 Li, CF 3 SO 3 Li, LiSCN, LiC (CF 3 SO 2) 3, (CF ₃ SO ₂ ) ₂ NLi, (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, chloroborane lithium, lithium lower aliphatic carboxylate, lithium 4-phenylborate, And more preferably LiTFSI (lithium bis (trifluoromethanesulfonyl) imide) represented by (CF ₃ SO ₂ ) ₂ NLi.

In the second polymer electrolyte layer 150, 30 to 40 parts by weight of the lithium salt is selected for 100 parts by weight of the lithium ion conductive polymer.

At least one of the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 according to the present invention may include an additive conventionally used in the polymer solid electrolyte field. For example, the additive may be at least one selected from the group consisting of an inorganic filler, an organic filler, and a polymer filler, and may preferably be an inorganic filler.

In the case of an inorganic filler, it is intended to prevent electrical short-circuiting due to impact and pressing in and out of the battery in the electrolyte, and to form an aggregate with the lithium ion conductive polymer to improve heat shrinkage characteristics at high temperature. The inorganic filler used herein does not cause any chemical change. The material of the inorganic filler is not particularly limited, and the material of the inorganic filler is TiO ₂ , BaTiO ₃ , Li ₂ O, LiF, LiOH, Li ₃ N, BaO, Na ₂ O, MgO , Li ₂ CO ₃ , LiAlO ₂ , SiO ₂ , Al ₂ O ₃ , PTFE, and mixtures thereof.

The content of the inorganic filler is preferably 5 wt% to 10 wt% in each of the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150. The particle size of the inorganic filler is preferably 0.01 to 0.8 mu m in size. In the case of the above-mentioned inorganic filler, a filler having porosity is preferable in order to improve the ease of movement of lithium ions in the electrolyte layer so as to sufficiently secure a path through which ions are transferred.

Polymer Of the electrolyte layer  thickness

The thickness of the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 described above needs to be limited in consideration of the function of the electrolyte.

The thickness of the final polymer electrolyte layer 190 including the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 may be 50 탆 to 250 탆. If the thickness is more than 250 탆, the resistance in the electrolyte layer may increase and the advantage of the discharge capacity may be lost. If the thickness is less than 50 탆, the limitation of the mechanical property of the electrolyte may be a problem. In this case, the thickness of each polymer electrolyte layer may be varied according to a desired voltage range, the thickness of the first polymer electrolyte layer 130 may be 25 to 225 μm, and the thickness of the second polymer electrolyte layer 150 may be Lt; / RTI > to < RTI ID =

The thickness of the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 may be 1: 9 to 9: 1. Since the present invention is a multilayer structure electrolyte for an all solid-state battery which exhibits a stable performance in a cathode of a high voltage region of 4.0V or higher and an anode of a low voltage region of 1.5V or lower including an aliphatic dinitrile compound, The thickness of the electrolyte layer 130 and the thickness of the second polymer electrolyte layer 150 can be different from each other.

The polymer electrolyte containing an aliphatic dinitrile compound has a high ionic conductivity at room temperature of 10 ^-4 S / cm or higher and stably operates at a high voltage anode of 4 V or more, but has a disadvantage of low voltage stability, (LTO) cathode, which is difficult to apply and has a high operating voltage of 1.5V. On the other hand, polyethylene oxide (PEO) -based polymer electrolytes can operate on lithium and graphite cathodes with good low-voltage stability, but on the contrary, they are difficult to apply to high-voltage cathodes of 4V or higher because of their low voltage stability. Therefore, the electrolyte of the multi - layer structure can be applied stably despite the voltage difference between the anode and the cathode.

Method for manufacturing polymer electrolyte of multi-layer structure

The multi-layered polymer electrolyte according to the present invention can be produced by any method capable of forming a multi-layered film.

First, a first coating solution for a first polymer electrolyte layer 130 including an aliphatic dinitrile compound satisfying Formula 1, a lithium salt, and a lithium ion conductive polymer is prepared. The solvent may be acetonitrile, propioniacryl, methoxypropionitrile or glutaronitrile, and acetonitrile may be preferably used. It is also possible to exclude the solvent when the viscosity is secured and the lithium salt can dissociate without a solvent.

The viscosity of the coating liquid at 25 ° C is 100 cp or less, which may vary depending on the coating apparatus, coating method and the like. Also, the thickness of the coating to be finally coated can be adjusted by adjusting the concentration of the coating liquid, the number of coatings, and the like.

The mixing of the first coating liquid is not particularly limited in the present invention, and a known mixing method can be used. For example, various methods such as gravure coating, die coating, multi-die coating, dip coating and comma coating or a combination thereof can be used, A dip coating or a gravure coating is used to obtain a uniform coating surface.

Next, the first coating liquid is coated on a substrate and dried to produce a coated film.

The substrate is not particularly limited and can be used. For example, the substrate may be a transparent inorganic substrate such as quartz or glass, or a transparent inorganic substrate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), polypropylene A transparent plastic selected from the group consisting of polyethersulfone (PI), polyethylene sulfonate (PES), polyoxymethylene (POM), polyetheretherketone (PEEK), polyethersulfone (PES) and polyetherimide A substrate can be used.

The first coating liquid is coated on the substrate, dried at room temperature for 24 hours, and dried at 40 DEG C under vacuum to prepare a film.

The drying process is a process for removing the solvent and moisture in the coating liquid to dry the coating liquid coated on the substrate, and may be varied depending on the solvent used. Examples of the drying method include a drying method by hot air, hot air, low-humidity air, vacuum drying, and irradiation with (circle) infrared rays or electron beams. The drying time is not particularly limited, but is usually in the range of 30 seconds to 24 hours. The drying step may further include a cooling step of slow cooling to room temperature.

In addition, when a solvent is not contained, a film can be produced using ultraviolet rays in the form of a photo-curing reaction.

In the photo-curing reaction, a photoinitiator can be used. Any compound capable of forming a radical by light such as ultraviolet rays can be used without limitation of its constitution. Examples of the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one (HMPP), benzoin ether, dialkyl acetophenone, At least one member selected from the group consisting of hydroxyl alkylketone, phenyl glyoxylate, benzyl dimethyl ketal, acyl phosphine and alpha-aminoketone, Can be used. On the other hand, as a specific example of the acylphosphine, a commonly used lucirin TPO, i.e., 2,4,6-trimethyl-benzoyl-trimethyl phosphine oxide can be used , Preferably 2-hydroxy-2-methyl-1-phenyl-propan-1-one (HMPP).

Next, a second coating liquid for the second polymer electrolyte layer is prepared by using an ionic liquid, a lithium salt, and a lithium ion conductive polymer and using acetonitrile as a solvent. The Teflon film is coated with the second coating liquid, dried at room temperature for 24 hours, and dried at 40 DEG C under vacuum to prepare a film.

Next, the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 are joined together to produce the polymer electrolyte 190 of the present invention. The first polymer electrolyte layer 130 and the second polymer electrolyte layer 150 are brought into close contact with each other by a lamination method and integrated by a roll lamination pressing process.

The pressing may be performed by cold-pressing or hot-pressing. In particular, the above-mentioned refrigeration pressure has a process advantage in that no special heat treatment is required. Specifically, the pressing may be that of Korean Patent Laid-Open Publication No. 10-2016-0013631 due to thermal pressure, which can affect the ion conductivity and the improvement of the contact area between particles ( J. Am. Ceram . Soc . 94 [6] 1779-1783 (2011)), it is possible to manufacture a multi-layered electrolyte having improved performance in terms of rate capability.

Further, the pressing may be performed at a pressure of 50 to 1000 MPa. If it is less than 50 MPa, a problem may arise that a multi-layer structure can not be formed between the first polymer electrolyte layer 130 and the second polymer electrolyte layer 150, and thus the range is limited to the above range.

All solids  battery

As described above, the entire solid- state batteries 100 and 200 according to the present invention define the structure of the solid electrolyte, and the other elements constituting the solid electrolytes are the anode 110 and anode 210 and the cathode 170 and 250, And the following description will be given.

The cathodes 170 and 250 of the all solid state batteries 100 and 200 use lithium metal singly or the anode active material laminated on the anode current collector.

At this time, the negative electrode active material may be selected from the group consisting of lithium metal, lithium alloy, lithium metal composite oxide, lithium-containing titanium composite oxide (LTO), and combinations thereof. The lithium alloy may be an alloy of lithium and at least one metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al and Sn. The lithium metal composite oxide is any one of metal (Me) oxides (MeO _x ) selected from the group consisting of lithium and Si, Sn, Zn, Mg, Cd, Ce, Ni and Fe. For example, LixFe ₂ O ₃ 0 < x? 1) or LixWO ₂ (0 < x? 1).

In addition to this, the negative electrode active material is SnxMe _{1 - x} Me _'y O _z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, of the periodic table Group 1, Group 2, Group 3 element, Halogen; 0 <x? 1; 1? Y? 3; 1? Z? 8); _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO2 2, Bi 2 O 3, Bi 2 O 4 , and Bi ₂ O ₅ and the like, and carbonaceous anode active materials such as crystalline carbon, amorphous carbon or carbon composite may be used alone or in combination of two or more.

The anode current collector is not particularly limited as long as it has electrical conductivity without causing any chemical change in the pre-solid state batteries 100 and 200, and examples thereof include copper, stainless steel, aluminum, nickel, titanium, The surface of the stainless steel may be surface treated with carbon, nickel, titanium, silver or the like, or an aluminum-cadmium alloy may be used. The negative electrode current collector may be formed in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric having fine irregularities on its surface, as in the case of the positive electrode collector.

The anode of the pre-solid battery according to the present invention is not particularly limited, and may be a material used in a known all-solid-state cell.

A positive electrode current collector when the electrode is a positive electrode, and a negative electrode current collector when the electrode is a negative electrode.

The positive electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. For example, carbon, nickel , Titanium, silver, or the like may be used.

The positive electrode active material may vary according to the application of the lithium secondary _{battery, LiNi 0 .8- x Co 0.2 AlxO} 2, LiCo x Mn y O 2, LiNi x Co y O 2, LiNi x Mn y O 2, LiNi x Co y Lithium transition metal oxides such as Mn _z O ₂ , LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiFePO ₄ , LiCoPO ₄ , LiMnPO ₄ and Li ₄ Ti ₅ O ₁₂ ; Cu ₂ Mo ₆ S ₈ , chalcogenides such as FeS, CoS and MiS, oxides, sulfides or halides of scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, And more specifically TiS ₂ , ZrS ₂ , RuO ₂ , Co ₃ O ₄ , Mo ₆ S ₈ , V ₂ O _5, and the like can be used, but the present invention is not limited thereto.

The shape of the cathode active material is not particularly limited and may be a particle shape, for example, a spherical shape, an elliptical shape, a rectangular parallelepiped shape, or the like. The average particle diameter of the cathode active material may be within the range of 1 to 50 占 퐉, but is not limited thereto. The average particle diameter of the cathode active material can be obtained, for example, by measuring the particle size of the active material observed by a scanning electron microscope and calculating the average value thereof.

The binder contained in the positive electrode is not particularly limited, and a fluorine-containing binder such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) may be used.

The content of the binder is not particularly limited as long as it can fix the cathode active material, and may be in the range of 0 to 10 wt% with respect to the whole anode.

The anode may further include a conductive material. The conductive material is not particularly limited as long as it can improve the conductivity of the anode, and examples thereof include nickel powder, cobalt oxide, titanium oxide, and carbon. Examples of the carbon include any one selected from the group consisting of Ketjen black, acetylene black, furnace black, graphite, carbon fiber and fullerene, or at least one of them.

At this time, the content of the conductive material may be selected in consideration of the conditions of other batteries such as the kind of the conductive material, and may be, for example, in the range of 1 to 10 wt%

 The production of all the solid batteries having the above-mentioned constitution is not particularly limited in the present invention, and can be produced by a known method.

For example, a solid electrolyte is disposed between an anode and a cathode, and the cell is assembled by compression molding. And the first polymer electrolyte layer of the polymer electrolyte is disposed in contact with the anode.

The assembled cell is installed in the casing and then sealed by heat compression or the like. Laminate packs made of aluminum, stainless steel or the like, and cylindrical or square metal containers are very suitable for the exterior material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to preferred embodiments and accompanying drawings. However, it should be understood that the present invention is not limited by the following examples, and that various modifications and changes may be made without departing from the scope of the present invention.

&Lt; Example 1 >

For the preparation of the first polymer electrolyte layer, succinonitrile and LiTFSI were added as an aliphatic dinitrile compound at a mass ratio of 8:13, and the mixture was heated and mixed at 60 ° C for 3 hours. Then, 21.5 wt% and 0.5 wt% of 2-hydroxy-2-methyl-1-phenylpropan-1-one were added as a lithium ion conductive polymer and trimethylolpropane ethoxylate triacrylate (HTPP) .

The mixed solution was cast on a transparent polyethylene terephthalate (PET) film as a substrate, and irradiated with ultraviolet light having a wavelength of 254 to 365 nm for 90 seconds to produce a first polymer electrolyte layer film. The thickness of the first polymer electrolyte layer film was adjusted to 95 탆.

To prepare the second polymer electrolyte layer, 32.4 wt% LiTFSI was mixed with a lithium salt in a polymer mixture of polyethylene oxide (PEO) and polypropylene carbonate (PPC) in an 8: 2 mass ratio, 22.5 wt% of [FSI] (1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide) was further added, and 10 ml of acetonitrile was added thereto and stirred for 24 hours.

The mixed solution was cast on the Teflon film, dried at room temperature for 24 hours, and further dried at 40 캜 under vacuum to prepare a second polymer electrolyte layer film. The thickness of the second polymer electrolyte layer film was adjusted to 94 탆.

The prepared first polymer electrolyte layer film and the second polymer electrolyte layer film were roll laminated to form a polymer solid electrolyte layer film, and the film thickness was adjusted to 189 탆. The ionic conductivity and voltage stability of one polymer solid electrolyte were measured.

&Lt; Example 2 >

Example 1 was repeated except that the thickness of the first polymer electrolyte layer was adjusted to 67 탆 and the thickness of the second polymer electrolyte layer to 65 탆 to set the thickness of the polymer solid electrolyte to 132 탆.

&Lt; Comparative Example 1 &

Succinonitrile and LiTFSI were mixed at 8: 13 mass ratio and heated at 60 占 폚 for 3 hours to be mixed. Then, 21.5 wt% and 0.5 wt% of 2-hydroxy-2-methyl-1-phenylpropan-1-one were added as a lithium ion conductive polymer and trimethylolpropane ethoxylate triacrylate (HTPP) Solution.

The mixed solution was cast on a transparent polyethylene terephthalate (PET) film as a substrate, and irradiated with ultraviolet light having a wavelength of 254 to 365 nm for 90 seconds to produce a first polymer electrolyte layer film. The thickness of the first polymer electrolyte layer film was adjusted to 182 탆. The ionic conductivity and voltage stability of the fabricated polymer solid electrolyte were measured.

&Lt; Comparative Example 2 &

32.4 wt% of LiTFSI was mixed with a lithium salt in a polymer mixture of PEO (Polyethylene Oxide) and PPC (Polypropylene Carbonate) in an 8: 2 mass ratio, and then 22.5 wt% of [EMIM] [FSI] ionic liquid was added And 10 ml of acetonitrile was added thereto, followed by stirring for 24 hours. The mixed solution was cast on the Teflon film, dried at room temperature for 24 hours, and further dried at 40 ° C under vacuum to prepare a film. The film thickness was adjusted to 195 μm. The ionic conductivity and voltage stability of the fabricated polymer solid electrolyte were measured.

&Lt; Measurement of ion conductivity &

The ionic conductivity of the polymer solid electrolyte prepared in Examples 1 to 2 and Comparative Examples 1 and 2 was determined by using the following Equation 1 after measuring the impedance thereof.

A film sample of the polymer solid electrolyte having a certain width and thickness was prepared for measurement. An SUS substrate having excellent electron conductivity was brought into contact with an ion blocking electrode on both sides of a plate-shaped sample, and an AC voltage was applied through the electrodes on both sides of the sample. At this time, the amplitude was set in the range of 1.0 MHz to 0.1 Hz under the applied conditions, and the impedance was measured using BioLogic VMP3. The resistance of the bulk electrolyte was obtained from the intersection point (R _b ) where the semicircle or straight line of the measured impedance trajectory meets the real axis and the ionic conductivity of the polymer solid electrolyte membrane was calculated from the sample width and thickness.

[Equation 1]

σ: ion conductivity

R _b : Impedance trajectory intersects the real axis

A: Width of sample

t: thickness of the sample

The multilayer polyelectrolyte film of Example 1 exhibited ion conductivity of 2.14 ± 0.97 × 10 ^-4 S / cm.

The multilayer polyelectrolyte film of Example 2 exhibited an ion conductivity of 2.13 ± 0.97 × 10 ^-4 S / cm.

The first polymer electrolyte film of Comparative Example 1 showed an average ionic conductivity of 1.77 + - 0.26 x 10 ^-4 S / cm.

The second polymer electrolyte film of Comparative Example 2 had an average ionic conductivity of 4.01 ± 0.95 × 10 ^-6 S / cm.

As a result of the measurement of the ionic conductivity, it was confirmed that the multi-layer solid polymer electrolyte of the example according to the present invention had an excellent average ion conductivity as compared with the electrolyte of the comparative example.

<Measurement of voltage stability>

Voltage stability of the polymer solid electrolytes prepared in Examples 1 to 2 and Comparative Examples 1 and 2 was evaluated by using a linear sweep voltammetry (LSV), and BioLogic VMP3 was used. A coin cell was fabricated by contacting a lithium metal electrode on one side of the polymer electrolyte and a SUS substrate on the other side of the polymer electrolyte of Examples and Comparative Examples. The scanning speed was 10 mV / s, and the measurement was performed in the range of -1 V to 6 V.

As shown in FIG. 4, the polymer electrolyte membrane prepared in the form of a multilayer of two films showed stable characteristics at a voltage of 0.5 V to 5 V. On the other hand, as shown in FIG. 5, the electrolyte layer of Comparative Example 1 is stable at 5 V or more, but is unstable at a low voltage region of 1.5 V or less. Also, as shown in FIG. 6, in the case of Comparative Example 2, it was stable in a low voltage region of 1.5 V or less, but was unstable at 3.8 V or more.

[Description of Symbols]

100, 200: entire solid battery 110, 210: anode

190, 230: solid electrolyte 170, 250: negative electrode

130: first polymer electrolyte layer

150: second polymer electrolyte layer

The multi-layered polymer electrolyte according to the present invention can be stably used in an anode in a high voltage region and a cathode in a low voltage region, and the whole solid battery including the same can be applied as a high capacity, high output battery in various technical fields.

Claims (16)

1. A first polymer electrolyte layer comprising an aliphatic dinitrile compound represented by Formula 1, a lithium salt, and a lithium ion conductive polymer; And

   A second polymer electrolyte layer comprising an ionic liquid, a lithium salt, and a lithium ion conductive polymer;

   A polymer electrolyte for a solid polymer electrolyte membrane.

   [Chemical Formula 1]

   N≡C-R-C≡N

   (Wherein, R is (CH _{2) n} is an integer of n = 1 to 6)
2. The method according to claim 1,

   Wherein the aliphatic dinitrile compound is succinonitrile. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
3. The method according to claim 1,

   Wherein the ionic liquid comprises a cation and an anion,

   Wherein the cation is a cation of a heterocyclic compound.
4. The method of claim 3,

   The cation of the heterocyclic compound may be at least one selected from the group consisting of pyridinium, pyridazinium, pyrimidinium, pyrazinium, pyrazolium, thiazolium, oxazolium, ), Triazolium, pyrrolidinium, piperidinium, imidazolium, and combinations thereof. The multi-layered structural polymer for all-solid-state cells Electrolyte.
5. The method of claim 3,

   Wherein the ionic liquid comprises a cation and an anion,

   The anion may be selected from the group consisting of bis (perfluoroethylsulfonyl) imide, bis (trifluoromethylsulfonyl) imide, bis (fluorosulfonyl) imide, tris (trifluoromethylsulfonylmethide) Fluoromethanesulfonimide, trifluoromethylsulfonimide, trifluoromethylsulfonate, tris (pentafluoroethyl) trifluorophosphate, bis (trifluoromethylsulfonyl) imide, tetrafluoroborate , Hexafluorophosphate, and combinations thereof. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
6. The method according to claim 1,

   Wherein the first polymer electrolyte layer comprises 20 to 50 parts by weight of an aliphatic dinitrile compound and 30 to 40 parts by weight of a lithium salt based on 100 parts by weight of the lithium ion conductive polymer.
7. The method according to claim 1,

   Wherein the second polymer electrolyte layer comprises 20 to 50 parts by weight of an ionic liquid and 30 to 40 parts by weight of a lithium salt per 100 parts by weight of the lithium ion conductive polymer.
8. The method according to claim 1,

   The lithium salt is _{LiCl, LiBr, LiI, LiClO 4} , LiBF 4, LiB 10 Cl 10, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, CH 3 SO 3 Li, CF ₃ SO ₃ Li, LiSCN, LiC (CF ₃ SO ₂ ) ₃ , (CF ₃ SO ₂ ) ₂ NLi, (FSO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylate lithium, Layered polymer electrolyte for all-solid-state cells.
9. The method according to claim 1,

   The lithium ion conductive polymer may be at least one selected from the group consisting of polyethylene glycol diacrylate, trimethylolpropaneethoxylate triacrylate, polypropylene oxide, polypropylene carbonate, polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polyvinyl chloride, poly Wherein at least one polymer selected from the group consisting of vinylidene fluoride, polyester, polyamide, polyethylene, polystyrene, and polyethylene glycol is used.
10. The method according to claim 1,

    Wherein the first polymer electrolyte layer has an ionic conductivity of 5 x 10 ^-5 to 5 x 10 ^-4 S / cm, and the second polymer electrolyte layer has an ionic conductivity of 1 x 10 ^-6 to 1 x 10 ^-4 S / cm A multi - layered polymer electrolyte for a solid electrolyte cell.
11. The method according to claim 1,

    Wherein the first polymer electrolyte layer and the second polymer electrolyte layer each have a thickness of 25 mu m to 225 mu m.
12. The method according to claim 1,

    Wherein the first polymer electrolyte layer and the second polymer electrolyte layer have a thickness ratio of 1: 9 to 9: 1.
13. The method according to claim 1,

    Wherein the multi-layered polymer electrolyte has a thickness of 50 to 250 占 퐉.
14. The method according to claim 1,

    Wherein at least one of the first polymer electrolyte layer and the second polymer electrolyte layer further comprises at least one selected from the group consisting of an inorganic filler, an organic filler, and a polymer filler.
15. In an all solid-state battery comprising a positive electrode, a negative electrode and a polymer electrolyte interposed therebetween,

    Wherein the polymer electrolyte is the polymer electrolyte according to any one of claims 1 to 14.
16. 16. The method of claim 15,

    Wherein the pre-solid battery is disposed such that the first polymer electrolyte layer of the polymer electrolyte is in contact with the anode.

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