KR101953738B1 - Composite Electrode with Ionic Liquid for All-Solid-State Battery, Method Of Manufacturing The Same, And All-Solid-State Lithium Battery Comprising The Same - Google Patents

Abstract

The present invention relates to a composite electrode for an all-solid-state battery including ionic liquid, a manufacturing method thereof, and an all-solid-state lithium battery including the same and, more specifically, to a composite electrode for an all-solid-state battery which adds ionic liquid to an interface of a solid electrolyte and a composite anode when manufacturing a lithium all-solid-state battery cell including a solid electrolyte densified by undergoing a sintering process and a solid electrolyte material to apply a composite anode having lithium ion conduction properties to improve adhesion of the interface between the solid electrolyte and the composite anode and reduce interface resistance by filling pores in the composite anode with the ionic liquid, and an all-solid-state battery which allows high output/long life and high performance when using the same as an electrode of a battery, and directly affixes a densified solid electrolyte to a composite electrode without inserting an intermediate layer such as a polymer electrolyte between the solid electrolyte and the composite anode.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite electrode for an all solid-state battery including an ionic liquid, a method for producing the same, and a full solid lithium battery including the same. BACKGROUND ART Comprising The Same}

The present invention relates to a composite electrode for an all solid-state battery containing an ionic liquid and an all-solid-state cell including the same, and more particularly to a composite electrode for a solid- The present invention relates to an all-solid-state cell produced by contacting an inorganic solid electrolyte densified through a sintering process or the like directly with a composite electrode without interposing an intermediate layer such as a polymer electrolyte, and having excellent electrochemical characteristics with excellent output and long life.

Recently, lithium batteries have been actively studied for efficient use of energy, and various efforts are being made to use them as energy sources for electric vehicles and electric power storage as well as small-sized mobile electronic devices.

The commercialized lithium ion secondary battery uses a liquid electrolyte based on an organic electrolyte. However, in the case of an organic electrolyte, the risk of explosion / fire is very high. To improve the safety of the battery, an organic liquid electrolyte is replaced with an inorganic- The need to do so has been increasing.

A pre-solid secondary battery in which an inorganic-based solid electrolyte is used instead of a liquid electrolyte does not use a flammable organic electrolytic solution, and has excellent safety because there is no risk of electrolyte leakage or ignition. However, in the case of all solid-state batteries, the anode, the solid electrolyte and the cathode are all in a solid state, and it is difficult for them to come into close contact with each other and thus the resistance of each interface and the cell cell becomes very large and the lithium ion conductivity of the solid electrolyte , And it is difficult to increase the output of the battery (JP-A No. 2004-183078 and JP-A No. 2000-138073).

There an inorganic solid electrolyte material may be divided into sulfide and oxide-based material, in the case of the Yellow River water system materials, but shows an oxide-based contrast high lithium ion conductive property, hygroscopicity is strong and is a sulfide of hydrogen (H ₂ S) toxic gas There is a high possibility of occurrence. Oxide-based solid electrolyte _{LLZO (Li a La 3 Zr 2} O 12), pages lobe _{LLTO (Li 3a La (2 /} 3a) □ (1 / 3-2a) having a tree structure having the garnet configuration Sky material _{TiO 3), LATP (Li 1} + a Al a Ti 2-a (PO 4) 3) and the like, the oxide-based solid electrolyte is a sulfide-based solid electrolyte compared to water, chemical, physical and mechanical stability having a NASICON structure And has attracted much attention as a solid electrolyte material due to its high bulk ion conduction property. However, most of the oxide-based solid electrolyte materials have a high grain boundary resistance, so that the total lithium ion conductivity is low, which makes it difficult to use the powder directly as a solid electrolyte of the battery. In order to solve this problem, the pellet is produced by sintering the solid electrolyte powder and then the sintering process (heat treatment) at a high temperature (800 ° C ~ 1400 ° C) is used to lower the grain boundary resistance by increasing the bonding force and pellet density between solid electrolyte particles. In this case, problems arise in interface bonding and adhesion between the solid electrolyte and the composite electrode containing the solid electrolyte material, so that the interfacial resistance of the solid electrolyte cell becomes very large and the cell output and lifetime characteristics are greatly deteriorated, The problem may be that it does not work at all.

Therefore, in order to develop a high-performance pre-solid lithium secondary battery, interfacial control technology is required to reduce the interfacial resistance between the solid electrolyte and the composite electrode, and to improve the bonding and adhesion.

On the other hand, the ionic liquid is a room temperature molten salt composed of cations and anions. It has non-volatile, flame-retardant, nonflammable, wide potential window and chemical stability, so it can solve the safety problem of organic electrolyte. It is attracting attention. However, it is difficult to use an ionic liquid alone as an electrolyte due to its low ion conductivity compared to conventional organic electrolytes. Instead of adding an ionic liquid having a liquid characteristic to the solid electrolyte / composite electrode interface to increase interfacial bonding between the solid electrolyte and the composite electrode, not only the interface bonding can be increased, but also the impregnation into the pores in the composite electrode It is possible to improve the wettability of the electrode to facilitate the movement of lithium ions and to maintain the safety of the solid electrolyte due to non-volatility, flame retardancy, and non-flammability.

Accordingly, in consideration of the problems of the prior art, the inventors of the present invention have found that, in the manufacture of a lithium ion battery cell employing a composite anode including a solid electrolyte and a solid electrolyte material densified through a sintering process and having a lithium ion conduction characteristic, And imidazolium and pyrrolidinium-based ionic liquids are added to the complex anode interface to increase the bonding of the interface between the solid electrolyte and the composite anode, A composite electrode for a full-solid battery which is filled with a polymer electrolyte and which reduces the interfacial resistance is manufactured. When the polymer electrolyte is used as an electrode of a pre-solid battery, high power / long life and high performance of the pre- By confirming that the densified solid electrolyte can be directly bonded to the composite electrode without insertion, And it completed the invention.

An object of the present invention is to provide a lithium ion battery which comprises a solid electrolyte and a solid electrolyte material densified through a sintering process to form a composite anode having lithium ion conductive properties, imidazolium and pyrrolidinium based ionic liquids are added to increase the bondability of the interface between the solid electrolyte and the composite anode and to increase the adhesion of the pores in the composite electrode to the entire solid electrolyte A composite electrode, and a method of manufacturing the same.

It is a further object of the present invention to provide a solid electrolyte battery in which when the composite electrode according to the present invention is used as an electrode of a pre-solid battery, it is possible to achieve high output / long life and high performance of the pre- A solid lithium battery capable of directly bonding a solid electrolyte denatured without insertion to a composite electrode, and a method for manufacturing the same.

In order to achieve the above object, the present invention provides a composite electrode comprising a composite electrode containing a cathode active material and an inorganic solid electrolyte material, and an ionic liquid, wherein the interface between the composite electrode and the composite solid electrolyte is uniformly impregnated with an ionic liquid, Thereby providing a composite electrode for a battery.

Also, the present invention provides a method for manufacturing a composite electrode, comprising the steps of: 1) compositing a cathode active material, a binder, a conductive material, and an inorganic solid electrolyte material to prepare a composite electrode by slurry coating for current collector; And 2) uniformly injecting an ionic liquid onto the surface of the composite electrode to impregnate the pores and surfaces in the composite electrode, thereby providing a composite electrode for a full solid lithium battery.

The present invention also relates to a composite anode containing a cathode active material and an inorganic solid electrolyte material; A sintered body of an inorganic solid electrolyte; Polymer solid electrolyte; And a negative electrode including a negative electrode active material, which are stacked in this order, and in which an ionic liquid is uniformly filled in the interface between the composite electrode and the sintered body of the inorganic solid electrolyte.

In addition, the present invention provides a method for manufacturing a composite electrode, comprising: 1) preparing a composite electrode by slurry coating a current collector with a positive electrode active material, a binder, a conductive material, and an inorganic solid electrolyte material; 2) uniformly injecting an ionic liquid into the surface of the composite electrode to impregnate pores and surfaces in the composite electrode; 3) laminating a sintered body of an inorganic solid electrolyte on the surface of the composite electrode impregnated with the ionic liquid; 4) stacking a polymer solid electrolyte on the sintered body of the inorganic solid electrolyte; And 5) stacking a negative electrode comprising the negative active material on the polymer solid electrolyte.

The present invention relates to a process for producing a lithium-ion composite solid electrolyte battery comprising a solid electrolyte and a solid electrolyte material which are densified through a sintering process, And a pyrrolidinium-based ionic liquid are added to increase the bondability of the interface between the solid electrolyte and the composite anode, and the composite electrode for the entire solid-state battery in which the ionic liquid is filled in the pores in the composite electrode to reduce the interfacial resistance Can be provided.

In addition, when the composite electrode for a full solid battery is used, it is possible to achieve high output / long life and high performance of the entire solid electrolyte, and the densified solid electrolyte is directly bonded to the composite electrode without interposing an intermediate layer such as a polymer electrolyte between the solid electrolyte and the composite anode A solid lithium battery can be provided.

1 is a view showing a configuration of a pre-solid lithium battery according to the present invention.
FIG. 2 is a photograph showing the results of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) experiments of the cross-sectional shape of the composite electrode prepared in Example 1. FIG.
FIG. 3 is a graph showing initial charging / discharging curves of all the solid batteries manufactured in Example 1, Example 2, Comparative Example 1, and Comparative Example 2. FIG.
FIG. 4 is a graph showing the evaluation results of charge / discharge life characteristics of all the solid batteries manufactured in Example 1, Example 2, Comparative Example 1 and Comparative Example 2. FIG.

Hereinafter, the present invention will be described in detail.

The present invention

A composite electrode containing a positive electrode active material and an inorganic solid electrolyte material, and an ionic liquid,

Wherein the interface of the composite electrode is uniformly impregnated with an ionic liquid,

A composite electrode for a solid lithium battery is provided.

Examples of the inorganic solid electrolyte material include LATP (Li _{1 + a} Al _a Ti _2-a (PO ₄ ) ₃ ) having a NASICON structure (where a is an integer of 0 to 2 or a prime number).

The inorganic solid electrolyte may further include a general solid electrolyte including a sintering process in addition to the solid electrolyte. For example, LLZO having an oxide-based garnet structure _{(Li x La 3 Zr 2 O} 12), a perovskite structure having _{LLTO (Li 3 La 2 / (} 3-x) TiO 3), LIPON (Li 3 - _x PO _{4 - x} N _x) or the like. However, it is not necessarily limited to these as long as they can all be used in the art.

It is preferable that the composite electrode is formed by combining a cathode active material, a binder, a conductive material, and a solid electrolyte material and slurry coating the current collector such as Al or the like.

The positive electrode active material can be used without limitation as long as it is commonly used in a lithium battery. For _{example, LiCoO 2, LiMnO 2, LiMn} 2 O 4, LiNi 1 - x Mn x O2 (0 <x <1), LiNi 1-xy Co x Mn y O 2 (0 <x <0.5, 0 <y <0.5), a lithium transition metal oxide of LiFePO ₄ , TiS ₂ , FeS ₂ , or a transition metal sulfide.

The ionic liquid includes imidazolium, pyrrolidinium, ammonium, or piperidinium as a cation and tetrafluoroborate, bis (fluoro (Bis (fluorosulfonyl) imide), bis (fluorosufonyl) amide, or fluorophosphate.

The added amount of the ionic liquid varies depending on the composite electrode thickness and the degree of porosity upon addition, but generally an amount of 0.2 μl / cm ² to 5.0 μl / cm ² is suitable. In this case, when injected below 0.2 μl / cm ² , it is difficult to sufficiently penetrate the ionic liquid on the surface of the composite anode, so that the bonding between the solid electrolyte and the composite anode is decreased. When added at a concentration of 5.0 μl / cm ² or more, It is possible to cause a side reaction and thereby reduce the performance.

The thickness of the composite anode is suitably from 10 μm to 100 μm. When the thickness is less than 10 μm, the capacity of the composite anode is too small to be practical. When the thickness exceeds 100 μm, the active material, conductive material, binder, The ionic conductivity and the electron conductivity are reduced, and the capacity and life of the composite electrode can be reduced.

The composite electrode for a full solid lithium battery is preferably prepared by injecting an appropriate amount of an ionic liquid into the surface of the composite anode to impregnate pores and surfaces in the composite electrode.

In addition,

1) preparing a composite electrode by forming a composite of a cathode active material, a binder, a conductive material, and a solid electrolyte material and slurry coating the current collector; And

2) uniformly injecting an ionic liquid onto the surface of the composite electrode to impregnate the pores and surface in the composite electrode, and a method for manufacturing the composite electrode for a full solid lithium battery.

In the above production method, the positive electrode active material, the solid electrolyte and the ionic liquid are as described above.

The binder may be selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyacrylonitrile, polymethyl methacrylate Polyvinyl alcohol, carboxymethylcellulose (CMC), starch, cellulose, polyethylene, polypropylene, polyacrylic acid, styrene butadiene rubber (SBR), fluorine rubber, polyacrylic acid, .

In the above production method, the conductive material (conductive material) is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; metal powders such as aluminum and nickel powder; And a conductive metal oxide such as titanium oxide may be used.

In the above manufacturing method, the cathode active material, the binder, the conductive material, and the solid electrolyte material are preferably compounded in a ratio of 60 to 80:20 to 10:10 to 7:10 to 3, respectively.

In the above manufacturing method, a cathode active material, a binder, a conductive material, and a solid electrolyte material are combined and slurry coated for current collector such as Al, and then an appropriate amount of ionic liquid is injected onto the surface of the composite anode, Impregnating the pores and the surface, and bringing the inorganic solid electrolyte into close contact with each other.

In addition,

A composite anode containing a cathode active material and an inorganic solid electrolyte material; A sintered body of an inorganic solid electrolyte; Polymer solid electrolyte; And a negative electrode comprising a negative electrode active material,

And an ionic liquid is uniformly filled in the interface between the composite electrode and the sintered body of the inorganic solid electrolyte.

The positive electrode active material can be used without limitation as long as it is commonly used in a lithium battery. For _{example, LiCoO 2, LiMnO 2, LiMn} 2 O 4, LiNi 1 - x Mn x O2 (0 <x <1), LiNi 1-xy Co x Mn y O 2 (0 <x <0.5, 0 <y <0.5), a lithium transition metal oxide of LiFePO ₄ , TiS ₂ , FeS ₂ , or a transition metal sulfide.

The inorganic solid electrolyte may be a LATP (Li _{1 + a} Al _a Ti _{2 -a} (PO ₄ ) ₃ ) having a NASICON structure wherein a is an integer of 0 to 2 or a prime number, LLZO may be an _{x PO 4 -x N x) -} Li x La 3 Zr 2 O 12), page LLTO lobe having a tree structure Sky _{(Li 3 La 2 / (3} -x) TiO 3), LIPON (Li 3.

The sintered body of the inorganic solid electrolyte is preferably prepared by increasing the degree of densification of the pellet type solid electrolyte through a heat treatment (sintering process) in the range of 800 to 1200 ° C to improve the crystal phase formation and ion conduction characteristics.

The ionic liquid includes imidazolium, pyrrolidinium, ammonium, or piperidinium as a cation and tetrafluoroborate, bis (fluoro (Bis (fluorosulfonyl) imide), bis (fluorosufonyl) amide, or fluorophosphate.

The negative electrode active material can be used without limitation as long as it is commonly used in a lithium battery. For example, at least one selected from the group consisting of a lithium metal, a metal capable of alloying with lithium, a metal oxide, and a carbon-based material. For example, examples of the metal capable of being alloyed with lithium include Si, Sn, Al, Ge, Pb and Bi. Examples of the metal oxide include lithium titanium oxide, SnO ₂ , SiO _x to be. The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof.

As the matrix of the polymer solid electrolyte added between the inorganic solid electrolyte and the negative active material, a copolymer of polyethylene oxide, polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile, Polydimethylsiloxane, and polydimethylsiloxane. When the lithium salt is added to give a lithium ion conductive property _{LiPF 6, LiBF 4, LiSbF 6} , LiAsF 6, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, LiC 4 F 9 SO 3, LiAlO ₄ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl and LiI. The solvent may be selected from the group consisting of tetrahydrofuran and acetonitrile.

The lithium battery has characteristics of a cathode active material content of 50 to 90% and an anode specific capacity of 100 mAh g ^-1 or more, and a densified solid electrolyte is directly bonded to the composite electrode without interposing an intermediate layer such as a polymer electrolyte between the solid electrolyte and the composite anode .

The lithium battery is also suitable for applications requiring high safety and high capacity such as an electric vehicle and can be used in a hybrid vehicle by being combined with a conventional internal combustion engine, a fuel cell, a supercapacitor, , And the lithium battery can be used for all other purposes such as mobile compact IT products such as mobile phones and portable computers.

In addition,

1) Compositing a cathode active material, a binder, a conductive material, and an inorganic solid electrolyte material to prepare a composite electrode by slurry coating for current collector;

2) uniformly injecting an ionic liquid into the surface of the composite electrode to impregnate pores and surfaces in the composite electrode;

3) laminating a sintered body of an inorganic solid electrolyte on the surface of the composite electrode impregnated with the ionic liquid;

4) stacking a polymer solid electrolyte on the sintered body of the inorganic solid electrolyte; And

5) laminating a negative electrode containing the negative electrode active material on the polymer solid electrolyte.

In the above manufacturing method, the cathode active material, the solid electrolyte, the ionic liquid, the sintered body of the inorganic solid electrolyte, the polymer solid electrolyte and the anode active material are as described above.

In the above manufacturing method, the cathode active material, the binder, the conductive material, and the solid electrolyte material are preferably compounded in a ratio of 60 to 80:20 to 10:10 to 7:10 to 3, respectively.

In the above manufacturing method, an inorganic solid electrolyte such as LATP, which is densified through a sintering process, is prepared and a composite electrode is prepared by mixing a cathode active material, a binder material, a conductive material, and a solid electrolyte material, A polymer solid electrolyte layer for facilitating contact between the inorganic solid electrolyte and the negative electrode is laminated and then the negative electrode including the negative active material is laminated to form a lower layer can do.

Hereinafter, the present invention will be described in more detail with reference to examples.

However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

< Example  1>

As a starting material, LiNO ₃ , Al precursor, Al (NO ₃ ) ₃₂ O, Ti precursor Ti (OCH ₂ CH ₂ CH ₂ CH ₃ ) ₄ and P precursor NH ₄ H ₂ PO ₄ were selected as Li precursor Li _{1 . 4} Al _{0 .} Was prepared by weighing a _{3: 4 Ti 1 .6 (PO} 4) 3 is obtained so that the molar ratios between Li, Al, Ti, P 1.4 : 0.4: 1.6. The starting materials were dissolved in ethylene glycol and citric acid (HOC (COOH) (CH ₂ COOH) ₂ ) corresponding to four times the molar amount of the total metal nitrate was added to the solution, (sol). The solution was heated to 170 占 폚 to prepare a gel, and the gel was continuously heated and pyrolyzed at 300 占 폚. Thereafter, the solid electrolyte powder was prepared after the heat treatment was performed at 800 ° C for 5 hours. The powder was milled by wet milling at 220 rpm for 12 hours by adding zirconia balls and ethanol. The powder was collected, dried at 80 ° C for 24 hours, and filtered through a 100-micron mesh to obtain a fine LATP powder having a size of 100 nm to 5 μm. The powder thus obtained was subjected to a sintering process at 850 ° C for 6 hours in an air atmosphere at a heating rate of 200 ° C / h in a furnace, followed by naturally drying in a furnace, LATP solid electrolyte sintered body.

The composite positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the dispersed LATP powder, super-P (conductive material) and PVdF (binder) 10:10, and dissolved in NMP (N-methyl pyrrolidinine) solution. The slurry was coated on Al foil with a doctor blade to prepare an electrode plate. After sufficiently drying in a vacuum oven at 120 ° C to volatilize a solvent such as NMP, the electrode density was increased through a roll press.

A free-standing polymer solid electrolyte used as an interlayer to increase the interfacial stability between the LATP solid electrolyte and the lithium anode was prepared as follows. 0.4 g of PEO (molecular weight 600,000) and 0.054 g of LiClO ₄ were dissolved in 20 ml of ACN (actetonitile) solvent, and the polymerization was carried out at 50 ° C for 4 hours or more. Then, the slurry was cooled at room temperature, poured into a PTFE plate, coated with a doctor blade to a thickness of 40 μm, dried and peeled to prepare a self-standing PEO-LiClO ₄ polymer electrolyte membrane.

Then, 1 μl / cm ² of imidazolium-based ionic liquid (1-Ethyl-3-methylimidazolium tetrafluoroborate) was uniformly injected into the composite anode plate and then the LATP solid electrolyte sintered body was directly laminated Polymer solid electrolyte and a lithium negative electrode were laminated on the LATP sintered body to form a total solid lithium battery composed of a composite anode / inorganic solid electrolyte (LATP) / polymer electrolyte / cathode (lithium foil) Respectively.

< Example  2>

(1-ethyl-1-methylpyrrolidinium tetrafluoroborate) was uniformly injected into a composite anode plate during the preparation of a solid lithium battery, and the same procedure as in Example 1 was repeated, except that 1 μl / cm ² of a pyrrolidinium- A total solid lithium battery was produced.

< Example  3>

The composition of the complex positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the LATP powder treated with the dispersion, super-P (conductive material) and PVdF : 10: 5 in the same manner as in < Example 1 &gt;.

< Example  4>

The composition of the complex positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the LATP powder treated with the dispersion, super-P (conductive material) and PVdF : 10: 5 was prepared in the same manner as in < Example 2 &gt;.

< Example  5>

The composition of the composite positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the dispersed LATP powder, super-P (conductive material) and PVdF : &Lt; / RTI > 7: 3 was prepared in the same manner as in &lt; Example 1 &gt;.

< Example  6>

The composition of the composite positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the dispersed LATP powder, super-P (conductive material) and PVdF : &Lt; / RTI > 7: 3 was prepared in the same manner as in &lt; Example 2 &gt;.

< Comparative Example  1>

A full solid lithium battery was prepared in the same manner as in < Example 1 > except that no ionic liquid was injected.

< Comparative Example  2>

Polymer electrolyte / inorganic solid electrolyte (LATP) / polymer electrolyte / negative electrode (lithium foil)] was added in place of adding the ionic liquid in the above Example 1, and a self-supporting polymer solid electrolyte was added between the composite positive electrode and the solid electrolyte. ] Was prepared.

< Comparative Example  3>

The composition of the complex positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the LATP powder treated with the dispersion, super-P (conductive material) and PVdF : 10: 5, the entire solid lithium battery was fabricated in the same manner as in < Comparative Example 2 &gt;.

< Comparative Example  4>

The composition of the composite positive electrode was prepared by mixing the positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), the dispersed LATP powder, super-P (conductive material) and PVdF : 7: 3, the entire solid lithium battery was fabricated in the same manner as in < Comparative Example 2 &gt;.

< Evaluation example  1> Scanning electron microscope ( SEM ) And energy dispersive spectroscopy (EDS) experiments

A scanning electron microscope (SEM) and an energy dispersive spectroscopy (EDS) experiment were conducted to examine the cross-sectional characteristics of the composite anode prepared in Example 1 above. In Example 1, the composite electrode was prepared by mixing a positive electrode active material Li [Ni _0.6 Co _0.2 Mn _0.2 ] O ₂ (NCM), a dispersed LATP powder, super-P (conductive material), and PVdF 20:10:10. SEM and EDS analyzes were performed on the cross section of the plate.

The experimental results are shown in Fig. From the cross-sectional SEM results, it can be seen that the electrode plate is compact and has a thickness of about 20 μm. From the results of the EDS analysis, it was confirmed that the Ni, Ti, and C components are uniformly present on the electrode surface, and the cathode active material, LATP powder, conductive carbon, and binder are uniformly dispersed and distributed (FIG.

< Evaluation example  2> Battery Charging and discharging  Experiment

The charge / discharge evaluation of the all solid lithium battery manufactured through the above-described Example 1, Example 2, Comparative Example 1 and Comparative Example 2 was performed. The current density was 40 mA / g based on the weight of the cathode active material, the voltage range was 2.5 V to 4.2 V, and the temperature was 60 ° C. The results of the first charge-discharge curve and the discharge capacity curve after 50 charge- Respectively.

As a result of the experiment, in Comparative Example 1, the ionic liquid was not added and the interfacial resistance between the composite electrode and the LATP solid electrolyte was so high that the polarization was greatly increased during charging and discharging, so that the battery could not operate at all. In the case of Comparative Example 2, when the polymer solid electrolyte layer was applied, the discharge capacity was measured to be 130 mAh / g. On the other hand, in Examples 1 and 2 in which imidazolium and pyrrolidinium-based ionic liquids were added, the initial discharge capacities were 139 mAh / g and 137 mAh / g, respectively , And it was confirmed that the characteristics of the initial capacity characteristics were superior to those of the polymer electrolyte of Comparative Example 2. The discharging capacities after 50 cycles of charging and discharging were 59, 85 and 79 mAh / g in Examples 2 and 3 and 45 and 61 and 58%, respectively It was confirmed that when the ionic liquid was added, it showed a better charge / discharge life. These results indicate that the ionic liquid is impregnated into the pores of the composite electrode, and the interface resistance between the composite electrode and the LATP solid electrolyte is improved by decreasing the interfacial resistance. In addition, Liquid was more effective in improving the specific capacity and the charge / discharge life span of the composite electrode (FIGS. 3 and 4).

The total current density of the entire solid battery fabricated through Example 3, Example 4, Example 5, Example 6, Comparative Example 3, and Comparative Example 4 was 40 charge / discharge evaluation was carried out at a voltage of 2.5 V to 4.2 V and a temperature of 60 ° C., and discharge capacity and capacity retention ratio after initial and 50 cycles of charge / discharge were shown in the following Table 1.

The discharge capacity after the initial 50 cycles of charge / discharge of all solid-state cells, the discharge capacity retention rate after 50 cycles of charging / discharging Initial discharge capacity
(mAh / g) Discharge capacity after 50 cycles
(mAh / g) Capacity retention rate
(%) Example 3 132 76 57.6 Example 4 130 72 55.4 Comparative Example 3 125 51 40.8 Example 5 120 65 54.2 Example 6 118 62 52.5 Comparative Example 4 109 41 37.6

As a result, it was confirmed that the initial capacity and capacity retention rate decreased as the ratio of the active material of the composite electrode increased. However, in the case of Comparative Example 3 and Comparative Example 4 to which the ionic liquid was added in Examples 3, 4, 5, and 6, It was confirmed that the ionic liquid showed better capacity and lifetime characteristics than the case where the polymer electrolyte was applied (Table 1).

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. More variations are possible within a range that does not. Accordingly, the present invention may be embodied in other forms without departing from the spirit or scope of the inventive concept as defined by the appended claims and their equivalents.

Claims (11)

delete delete delete delete delete A composite anode containing a cathode active material and an inorganic solid electrolyte material;
A sintered body of an inorganic solid electrolyte;
Polymer solid electrolyte; And
A negative electrode including a negative electrode active material;
Wherein the interface between the complex anode and the sintered body of the inorganic solid electrolyte is uniformly filled with imidazolium and pyrrolidinium based ionic liquids,
All solid lithium batteries.
The method according to claim 6,
The sintered body of the inorganic solid electrolyte may be a sintered body of LATP (Li _{1 + a} Al _a Ti _2-a (PO ₄ ) ₃ ) wherein a is an integer of 0 to 2 or a prime number at 800 to 1200 ° C through a sintering process. Wherein the solid lithium battery is formed in the shape of a cylinder.
delete ◈ Claim 9 is abandoned upon payment of registration fee. The method according to claim 6,
The polymer solid electrolyte may be any one selected from the group consisting of a copolymer of polyethylene oxide, polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene, polymethacrylate, polyacrylonitrile and polydimethylsiloxane &Lt; / RTI &gt; wherein the electrolyte is a matrix.
1) Compositing a cathode active material, a binder, a conductive material, and an inorganic solid electrolyte material to prepare a composite electrode by slurry coating for current collector;
2) uniformly injecting an ionic liquid into the surface of the composite electrode to impregnate pores and surfaces in the composite electrode;
3) laminating a sintered body of an inorganic solid electrolyte on the surface of the composite electrode impregnated with the ionic liquid;
4) stacking a polymer solid electrolyte on the sintered body of the inorganic solid electrolyte; And
5) stacking a negative electrode comprising the negative active material on the polymer solid electrolyte;
A method for manufacturing a solid lithium battery.
11. The method of claim 10,
Wherein the positive electrode active material, the binder, the conductive material, and the solid electrolyte material are compounded in a ratio of 60 to 80:20 to 10:10 to 7:10 to 3, respectively.

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