KR102451128B1 - Sulfide-based all solid state lithium secondary battery - Google Patents

Abstract

The all-solid-state lithium secondary battery according to the present invention uses a sulfide-based solid electrolyte having an ionic conductivity close to that of an organic electrolyte, while the case is damaged by an external force. It is possible to provide a safe and highly reliable all-solid-state lithium secondary battery capable of suppressing the generation of hydrogen sulfide gas generated according to the reaction of the all-solid-state electrolyte and moisture.

Description

Sulfide-based all solid state lithium secondary battery

The present invention relates to an all-solid-state lithium secondary battery, and more particularly, to a sulfide-based all-solid-state lithium secondary battery capable of increasing the reliability and stability of a product by suppressing hydrogen sulfide that may be generated in a sulfide-based all-solid electrolyte.

With the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones in recent years, development of a secondary battery excellent as a power source, for example, a lithium secondary battery, is considered important.

In fields other than the information-related devices and communication-related devices, for example, also in the automobile industry, high-output and high-capacity lithium secondary batteries for electric vehicles and hybrid vehicles as low-emission vehicles are being developed.

However, since the lithium secondary battery currently on the market uses an organic electrolyte solution using a flammable organic solvent as a solvent, a safety device that suppresses the temperature rise during a short circuit is installed, and improvements in structure and material for preventing a short circuit I need this.

On the other hand, an all-solid-state lithium secondary battery in which the battery is all-solidified by changing the liquid electrolyte into a solid electrolyte does not use a flammable organic solvent in the battery, so the safety device is simplified, and the manufacturing cost and productivity are excellent. have.

In the above-described all-solid lithium secondary battery, for example, pellets having a three-layer configuration of positive electrode/solid electrolyte/negative electrode are formed by a powder molding method, inserted into a conventional coin-type battery case or button-type battery case, and sealed around the to make it

In such an all-solid-state lithium secondary battery, since the battery constituent group consisting of the positive electrode, the negative electrode, and the electrolyte are all solid solids, the electrochemical resistance is increased and the output current tends to decrease compared to the lithium secondary battery using the organic electrolyte. There is this.

Therefore, in order to make the output current of an all-solid-state lithium secondary battery large, as an electrolyte, a thing with high ion conductivity is preferable. For example, sulfide glasses such as Li ₂ S-SiS ₂ , Li ₂ SB ₂ S ₃ , and Li ₂ SP ₂ S ₅ exhibit high ionic conductivity exceeding 10 ⁻⁴ S/cm. In addition, those added with LiI, Li ₃ PO ₄ and the like exhibit high ionic conductivity of about 10 ^-3 S/cm. In the glass mainly composed of these sulfides, the sulfide ions are ions having a larger polarization than the oxide ions, and since the electrostatic attraction with the lithium ions is small, the ion conductivity is higher than that of the oxide glass.

However, in a battery using the above-described solid electrolyte material mainly composed of sulfide, when water enters the battery case, hydrogen sulfide (H ₂ S) gas is generated and there is a risk of leakage to the outside of the battery case. In particular, hydrogen sulfide is a colorless, poisonous gas that smells like rotting eggs and can be absorbed into the stomach or lungs and cause suffocation, lung disease, and nerve central paralysis.

Therefore, in order to suppress the generation of hydrogen sulfide or the outflow to the outside of the case, a method of providing an adsorbent inside or outside the case and adsorbing the hydrogen sulfide generated in the battery has been proposed.

For example, in Japanese Patent Laid-Open No. 2004-087152, a porous adsorbent such as zeolite, silica gel, or activated carbon is inserted into the case to adsorb hydrogen sulfide gas. However, the porous adsorbent described above has a problem in that the adsorption capacity is lost when the pores on the surface are clogged by a large amount of water because physical surface adsorption is applied to trap hydrogen sulfide or moisture in the pores.

Japanese Patent Laid-Open No. 2004-087152 (March 18, 2004)

The present invention has been devised to solve the above problems, and specifically, when a large amount of moisture or water penetrates into the case due to damage of the case by an external force, the reaction between the sulfide-based all-solid electrolyte and moisture An object of the present invention is to provide a safe and highly reliable all-solid-state lithium secondary battery capable of suppressing the generation of hydrogen sulfide gas.

The present invention relates to a sulfide-based all-solid-state lithium secondary battery.

One aspect of the present invention is an all-solid-state lithium secondary battery in which a sulfide-based solid electrolyte material is accommodated in a case, wherein the all-solid-state lithium secondary battery is further provided with a hydrogen sulfide adsorbent comprising a metal oxide, a metal hydroxide and an adsorption improving agent inside the case It relates to a sulfide-based all-solid-state lithium secondary battery characterized in that.

In the present invention, the metal oxide is any one or a plurality selected from zinc oxide, titanium dioxide, copper oxide, manganese oxide, iron oxide (Fe ₂ O ₃ ) and calcium oxide,

The metal hydroxide is any one or a plurality selected from calcium hydroxide, magnesium hydroxide, sodium hydroxide and lithium hydroxide,

The adsorption improving agent is characterized in that one or more selected from lithium iodide, sodium iodide, potassium iodide (KI, KI ₃ ), rubidium iodide and cesium iodide.

In addition, the hydrogen sulfide adsorbent is characterized in that it comprises 50 to 80 wt% of a metal oxide, 10 to 40 wt% of a metal hydroxide, and 1 to 10 wt% of an adsorption improving agent, and the hydrogen sulfide adsorbent is attached to the inner surface of the case, characterized in that it is provided do.

The all-solid-state lithium secondary battery according to the present invention uses a sulfide-based solid electrolyte having an ionic conductivity close to that of an organic electrolyte, while the case is damaged by an external force. It is possible to provide a safe and highly reliable all-solid-state lithium secondary battery capable of suppressing the generation of hydrogen sulfide gas generated according to the reaction of the all-solid-state electrolyte and moisture.

Hereinafter, a sulfide-based all-solid-state lithium secondary battery according to the present invention will be described in more detail by way of Examples and Comparative Examples. However, the embodiments introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art.

Therefore, the present invention is not limited to the embodiments presented below and may be embodied in other forms, and the embodiments presented below are only described to clarify the spirit of the present invention, and the present invention is not limited thereto.

At this time, unless there are other definitions in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the technical field to which this invention belongs, and in the following description, it may unnecessarily obscure the subject matter of the present invention. Descriptions of possible known functions and configurations will be omitted.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

In the present invention, the term 'sulfide-based all-solid electrolyte' refers to a solid state electrolyte containing lithium and sulfur as main elements, and phosphorus, germanium, silicon, boron or other metals are further included. Although it has high energy capacity, it exhibits high lithium ion conductivity only by press molding, and the capacity deterioration hardly occurs even after multiple charging and discharging, so it is in the spotlight as a next-generation secondary battery electrolyte.

In addition, since there is no electrolyte leakage due to temperature changes and external shocks by having a solid electrolyte basically, the disadvantage of being sensitive to heat and pressure, which is a disadvantage of lithium secondary batteries, can be solved. It has the advantage of achieving energy density.

However, due to the characteristics of a solid electrolyte, it has a lower ionic conductivity than a liquid electrolyte and has a high interfacial resistance at the boundary between the active material and the electrolyte, so the lifespan may be relatively short. Accordingly, this problem can be solved by further adding the solid electrolyte to the active material layer of the positive electrode or the negative electrode and bringing the particle shape into an argyrodite structure.

Another disadvantage of the sulfide-based all-solid electrolyte is that it has high reactivity with water or oxygen. In particular, as the case or sealing is damaged or deformed, when it comes into contact with the atmosphere, hydrogen sulfide (H ₂ S) is generated by a reaction represented by Equation 1 with moisture in the atmosphere.

[Equation 1]

Li-AS + H ₂ O -> Li-AO +H ₂ S

(A in Formula 1 is at least one selected from phosphorus, germanium, boron, silicon, gallium, arsenic, antimony, iodine, aluminum, tin, indium, titanium, vanadium, niobium, and tantalum.

The hydrogen sulfide gas generated through Equation 1 is dissolved in water and dissociated into hydrogen (2H ⁺ ) and sulfur (S ² - ) ions in water. When the hydrogen and sulfur are saturated to the extent that they are no longer dissolved in water, hydrogen sulfide gas is generated in the atmosphere.

In order to solve the above problems, the present invention inserts an adsorbent (fixing agent), which has a higher reactivity with water than a sulfide-based solid electrolyte material, to be located on the inner surface of the case, thereby preventing the generation of hydrogen sulfide gas into the atmosphere even if water enters the case. can be suppressed

In the sulfide-based all-solid-state lithium secondary battery according to the present invention, the solid electrolyte layer is located between the positive electrode layer and the negative electrode layer in the case, and the current collector is disposed on the outer surfaces of the positive electrode layer and the negative electrode layer, so that the entirety is covered with the above-described case and sealed can be In addition, a hydrogen sulfide adsorbent is further provided on the inner surface of the case, and the hydrogen sulfide adsorbent may be disposed on a portion of the inner surface of the case to which an electric potential is not applied.

In the present invention, the hydrogen sulfide adsorbent may have an excellent hydrogen sulfide adsorption (fixation) effect at both high and low temperatures by including a metal oxide, a metal hydroxide, and an adsorption improving agent.

As described above, when a general sulfide-based solid electrolyte material comes into contact with water, hydrogen sulfide gas is generated by a reaction as in Equation 1 above. However, when the hydrogen sulfide adsorbent is further provided, moisture reacts with the metal oxide of the adsorbent before the sulfide-based solid electrolyte. Specifically, the metal oxide reacts with water to generate a metal cation, and the metal cation reacts with a sulfide ion (S ² - ) to form a metal sulfide, thereby fixing the sulfide ion.

In addition, metal oxides can react with sulfide ions in a state of dissociation into ions to generate metal sulfides, but when they are reduced by hydrogen sulfide and lose lattice oxygen, oxygen in the gas phase is active while providing lattice oxygen to the catalyst. It may proceed with an oxidation-reduction mechanism that maintains

In addition, it is possible to capture the hydrogen sulfide generated through the pores according to the structure of the metal oxide, thereby achieving an additional hydrogen sulfide removal effect.

As the metal hydroxide is included here, when water attaches to the surface of the metal hydroxide to form a kind of water film, hydrogen sulfide dissolves and decomposes in the water film, and HS ^- ions in an ionized state through an oxidation reaction by oxygen or hydroxyl groups on the surface to form The ions thus formed can be converted into a solid phase by reacting with the transition metal.

In addition, the adsorption improver is to improve the low hydrogen sulfide adsorption capacity at low temperature, which is a disadvantage of the metal oxide, and can increase the reactivity by increasing the active point for chemical adsorption of the adsorbent.

In the present invention, the metal oxide reacts with water to form a metal cation, and the metal cation reacts with the sulfide ion (S ² - ) to precipitate the product in a stable solid state that is difficult to dissolve in water. not limited to As the sulfide ions are precipitated in the solid form as described above, it is possible to prevent the diffusion of sulfide ions in the atmosphere and eliminate the risk of inhalation by humans.

In the present invention, as the metal oxide, for example, zinc oxide (ZnO), titanium dioxide (TiO ₂ ), copper oxide (CuO), manganese dioxide (MnO ₂ ), iron oxide (Fe ₂ O ₃ ) and calcium oxide (CaO), etc. These may be used alone or in combination of two or more.

More preferably, titanium dioxide is mentioned as the metal oxide in the present invention. The titanium dioxide has a very high oxidizing power compared to other metal oxides, so it has excellent reactivity with sulfides, is a very stable material, is nontoxic, has porosity, and can be physically adsorbed.

The metal oxide is preferably added in an amount of 50 to 80% by weight based on 100% by weight of the hydrogen sulfide adsorbent. When the amount of metal oxide added is less than the above range, both physical adsorption and chemical adsorption of hydrogen sulfide are reduced. Deformation may occur.

In addition, other metal oxides generate severe heat when a high concentration of hydrogen sulfide is generated. As a result, when the temperature of hydrogen sulfide rises, the adsorption performance is significantly reduced. It is preferable to use titanium dioxide because the adsorption rate becomes slow and the volume time becomes long.

In the present invention, the metal hydroxide is intended to further supplement the adsorption performance of the above-described metal oxide. In particular, when the moisture content in the air increases as moisture enters the case, the adsorption performance of the general metal oxide is greatly reduced, but the metal oxide When the hydroxide is further added, a water film is formed on the surface of the adsorbent by the metal hydroxide, and the water film promotes the oxidation reaction of hydrogen sulfide and leads to decomposition.

Examples of the metal hydroxide in the present invention include calcium hydroxide (Ca(OH) ₂ ), magnesium hydroxide (Mg(OH) ₂ ), sodium hydroxide (NaOH ₂ ) and lithium hydroxide (LiOH). Or two or more may be mixed and used.

More preferably, magnesium hydroxide is used as the metal hydroxide in the present invention. The magnesium hydroxide has a lower calorific value when absorbed than other metal hydroxides, and is harmless to the human body. In addition, since the affinity with water is high, it can induce a water film-forming reaction to further enhance the adsorption and fixation effect of hydrogen sulfide.

In the present invention, the metal hydroxide is preferably added in an amount of 10 to 40 wt% based on 100 wt% of the hydrogen sulfide adsorbent. If the content of the metal hydroxide is less than the above range, the hydrogen sulfide adsorption effect is reduced due to insufficient water film formation of the composition. can occur

In the present invention, the adsorption improver is to solve the disadvantage of the metal oxide, which is a decrease in hydrogen sulfide adsorption efficiency at low temperature, and to increase the reactivity with hydrogen sulfide by increasing the active point as described above.

Examples of the adsorption improving agent include lithium iodide (LiI), sodium iodide (NaI), potassium iodide (KI, KI ₃ ), rubidium iodide (RbI) and cesium iodide (CsI) as metal iodide. , These may be used alone or in combination of two or more.

More preferably, potassium iodide (KI) is mentioned as the adsorption improving agent. The potassium iodide is water-soluble, so it is easy to mix with the metal oxide, and although the pore properties for physical adsorption of the metal oxide are reduced, the chemical adsorption performance can be improved due to the increase of the active point.

The adsorption improving agent is preferably added in an amount of 1 to 10 wt% based on 100 wt% of the hydrogen sulfide adsorbent. When the content of the adsorption improver is less than the above range, the hydrogen sulfide adsorption effect decreases due to a decrease in the effect of forming an active point. .

The hydrogen sulfide adsorbent is not particularly limited as long as it can fix sulfide ions or hydrogen sulfide through the above-described reaction, but preferably has a solid shape so that water can rapidly react with water when water enters the case. As said solid form, the pellet which shape|molded the powder, powder, the film form etc. are mentioned, for example, Among these, the film-form thing is preferable.

The hydrogen sulfide adsorbent is not limited to a manufacturing method. For example, an adsorption improving agent and a metal hydroxide are dissolved in distilled water and stirred, and then a porous metal oxide is mixed. Then, the moisture is evaporated using an evaporator and then heat-treated to prepare an adsorption improver and a metal hydroxide coated in the pores or surface of the metal oxide. In addition, the prepared hydrogen sulfide adsorbent may be mixed with a polymer resin as needed to further improve moldability, and then filmed through a method such as casting.

As a position where the hydrogen sulfide adsorbent is provided, it is preferable to install it so that it does not come into contact with an electrode such as a positive electrode or a negative electrode and a place where a potential such as a terminal is applied among the inner surfaces of the case. This is to prevent the components of the adsorbent from changing due to unnecessary reactions such as reduction of metal salts due to potential.

In addition, a place close to the sulfide-based solid electrolyte layer where there is a possibility that a large amount of hydrogen sulfide gas is generated when water enters the battery case, or a place close to the sealing part that seals the battery, etc. is preferable

Here, it is preferable to install in the widest possible range within the battery case. This is because it can cope with damage to any part of the battery case. In other words, since the metal salt is decomposed even if water enters from any part of the battery, the metal cation generated by dissociation reacts with the sulfide ion to cause precipitation of the metal sulfide to immobilize the sulfide ion. This is because the occurrence can be suppressed.

In the present invention, the sulfide-based solid electrolyte layer includes a sulfide-based solid electrolyte and may be specifically formed by mixing a sulfide-based solid electrolyte material with an additive such as a binder or a solvent and then uniaxially compression molding.

Specific examples of the sulfide-based solid electrolyte material used for the sulfide-based solid electrolyte layer include a solid electrolyte material (Li-AS) composed of Li, A, and S. At this time, among the sulfide-based solid electrolyte material Li-AS, A is at least one selected from the group consisting of P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, and Ta. Specific examples of the sulfide-based solid electrolyte material Li-AS include 70Li ₂ S-30P ₂ S ₅ , LiGe _0.25 P _0.75 S ₄ , 80Li ₂ S-20P ₂ S ₅ , Li ₂ S-SiS ₂ , and the like. and 70Li ₂ S-30P ₂ S ₅ having high ionic conductivity is more preferable.

The method for producing the sulfide-based solid electrolyte material used in the present invention is not particularly limited as long as it is a method capable of obtaining a desired sulfide-based solid electrolyte material. , and a method obtained by heat treatment thereafter.

As the binder, known binders that may be included in the electrolyte layer, the positive electrode layer, the negative electrode layer, and the like of a solid battery may be appropriately used. As such binders, butylene rubber (BR), acrylonitrile butadiene rubber (ABR), butadiene rubber (BR), polyvinylidene fluoride (PVdF) and styrene butadiene rubber (SBR) can be exemplified.

In the present invention, the positive electrode layer is a layer including a positive electrode active material and a sulfide-based solid electrolyte, and as the positive electrode active material contained in the positive electrode layer, a known positive electrode active material usable in an all-solid-state battery may be appropriately used.

As the positive electrode active material, for example, in addition to layered active materials such as lithium cobaltate (LiCoO ₂ ) or lithium nickelate (LiNiO ₂ ), Li _1+x Ni _1/3 Mn _1/3 Co _1/3 O ₂ (x is a positive number) is), lithium manganate (LiMn ₂ O ₄ ), Li _1+x Mn _2-xy M _y O ₄ (M is any one or a plurality selected from Al, Mg, Co, Fe, Ni, Zn, x and y is a positive number); lithium metal phosphate represented by lithium titanate (Li _x TiO _y ) (x and y are positive numbers), LiMPO ₄ (M is Fe, Mn, Co or Ni); etc. can be exemplified.

The shape of the positive electrode active material can be, for example, a particle shape or a thin film state. Although the average particle diameter (D50) of the positive electrode active material is not limited in the present invention, for example, it is preferably 1 nm to 100 μm, and more preferably 10 nm to 30 μm. In addition, the content of the positive electrode active material in the positive electrode layer is not particularly limited, but is preferably, for example, in the range of 40 to 99% by weight.

The sulfide-based solid electrolyte included in the positive electrode layer is preferably a sulfide-based solid electrolyte material included in the above-described electrolyte layer, and the aforementioned 70Li ₂ S-30P ₂ S ₅ is more preferable.

In addition, in some cases, a high resistance layer may be formed at the interface between the positive electrode active material and the sulfide solid electrolyte. From the viewpoint of suppressing the formation of the high resistance layer to easily suppress the increase in battery resistance, the positive electrode active material is preferably coated with a coating layer containing an ion conductive oxide.

The coating layer may contain a material having lithium ion conductivity and maintaining its shape without flowing even when in contact with a positive electrode active material or a sulfide solid electrolyte. As the ion conductive oxide contained in the coating layer covering the positive electrode active material, for example, the general formula Li _x AO _y (A is B, C, Al, Si, P, S, Ti, Zr, Nb, Mo, Ta or W) Oxide represented by any one selected from, and x and y are positive numbers) may be used. Specifically, Li ₃ BO ₃ , LiBO ₂ , Li ₂ CO ₃ , LiAlO ₂ , Li ₄ SiO ₄ , Li ₂ SiO ₃ , Li ₃ PO ₄ , Li ₂ SO ₄ , Li ₂ TiO ₃ , Li ₄ Ti ₅ O ₁₂ , Li ₂ Ti ₂ O ₅ , Li ₂ ZrO ₃ , LiNbO ₃ , Li ₂ MoO ₄ , Li ₂ WO ₄ , and the like may be used.

In addition, the lithium ion conductive oxide as described above may be a composite oxide. As the composite oxide, any combination of the above lithium ion conductive oxides can be employed. For example, Li ₄ SiO ₄ -Li ₃ BO ₃ and Li ₄ SiO ₄ -Li ₃ PO ₄ may be used.

When the surface of the positive electrode active material is coated with an ion conductive oxide as described above, the ion conductive oxide may cover at least a part of the positive electrode active material and may cover the entire surface of the positive electrode active material. Moreover, it is preferable that it is 0.1-100 nm, and, as for the thickness of the ion conductive oxide which coat|covers a positive electrode active material, it is more preferable that it is 1-20 nm, for example.

In addition, the positive electrode layer may contain, if necessary, a conductive auxiliary agent for improving conductivity and a binder for binding the positive electrode active material and the solid electrolyte, and may include a thickener in some cases.

As the conductive aid, known conductive aids that can be used in an all-solid-state battery may be appropriately used. For example, in addition to carbon materials such as vapor grown carbon fibers, etc., acetylene black (AB), Ketjen black (KB), carbon nanotubes (CNT) and carbon nanofibers (CNF) that can withstand the environment when a solid-state battery is used ) and other carbon materials or metal materials may be used.

In addition, when a positive electrode layer is manufactured using a slurry-type composition for a positive electrode prepared by dispersing a positive electrode active material in a liquid, heptane may be exemplified as a usable liquid, and a non-polar solvent may be preferably used. In this case, the thickness of the anode layer is preferably 0.1 μm to 1 mm, more preferably 1 μm to 100 μm. In addition, the positive electrode layer is preferably manufactured through a pressing process to facilitate improving the performance of the all-solid-state battery.

In the present invention, the negative electrode layer is a layer including a negative electrode active material and a sulfide-based solid electrolyte. As the negative electrode active material contained in the negative electrode layer, a known negative electrode active material usable in an all-solid-state battery may be appropriately used, for example, carbon active materials, oxide active materials, and metal active materials.

The carbon active material is not particularly limited as long as it contains carbon, and for example, mesocarbon microbeads (MCMB), highly oriented pyrolytic graphite (HOPG), hard carbon and soft carbon may be used. In addition, as the oxide active material, for example, Nb ₂ O ₅ , Li ₄ Ti ₅ O ₁₂ , SiO may be used. As the metal active material, for example, In, Al, Si, Sn, and alloys thereof can be used.

In addition, as the negative electrode active material, a lithium-containing metal active material other than the above active materials may be used. The lithium-containing metal active material is not particularly limited as long as it is an active material containing at least Li, and lithium metal or a lithium alloy may be used. As the lithium alloy, for example, an alloy containing Li and at least one of In, Al, Si, and Sn may be used.

The shape of the negative electrode active material may be in the form of a particle, a thin film, or the like. The average particle diameter (D50) of the negative electrode active material is, for example, preferably 1 µm to 100 mm, and more preferably 10 µm to 30 mm. In addition, the content of the negative electrode active material in the negative electrode layer is not particularly limited, but is preferably 40 to 99% by weight, for example.

Here, the negative electrode layer may further include additives such as the above-described conductive aid, binder, and solvent, if necessary, and their content may also be added within the above-described range.

Among the current collectors, the positive electrode current collector may be formed of known conductive materials that can be used as a positive electrode current collector of an all-solid-state battery. For example, the positive electrode current collector may be formed of a metal material including any one or a plurality of elements selected from the group consisting of stainless steel, Ni, Cr, Au, Pt, Al, Fe, Ti, and Zn. In addition, the positive electrode current collector may be provided in the form of, for example, a foil or a mesh.

The negative electrode current collector is made of a known conductive material that can be used as a negative electrode current collector of an all-solid-state battery, and contains a metal reacting with the sulfide solid electrolyte contained in the negative electrode layer.

In this case, the "metal that reacts with the sulfide solid electrolyte" means a metal that generates a sulfur compound when heated while in contact with the sulfide solid electrolyte. As a specific example of such a metal, a metal material containing one or a plurality of elements selected from Cu, Fe, Ni, Co, Ti, etc., or a metal material plated or deposited with a conductive material such as another metal material or carbon material can be configured by Such a negative electrode current collector may be provided in the form of a foil or a mesh, similar to the positive electrode current collector.

The all-solid-state lithium secondary battery according to the present invention may further include a spacer, a sealing (packing), a case, and the like. These configurations are not particularly limited, and, for example, the spacer or the case may be made of stainless steel or aluminum. In addition, as the sealing, it is preferable to include a polymer resin having a low water absorption, for example, a polymer resin such as epoxy.

Here, the all-solid lithium secondary battery may further include a porous adsorbent such as zeolite, silica gel, activated carbon, etc. in addition to the hydrogen sulfide adsorbent. Such an adsorbent may be provided inside or outside the battery case similarly to the hydrogen sulfide adsorbent described above, and may adsorb hydrogen sulfide generated under a small amount of moisture such that dissociation of the metal salt does not occur.

The all-solid-state lithium secondary battery according to the present invention is not limited to a manufacturing method. For example, a positive electrode layer material, a sulfide-based solid electrolyte material, and a negative electrode layer material are put into a molding jig and uniaxially compression molded to obtain a layer having a multilayer structure, and then place it at a predetermined position in the battery case. In addition, it is preferable to prevent the decomposition of the metal salt by attaching the above-described hydrogen sulfide adsorbent to the inner surface of the case separately, but placing it in a portion where the electric potential does not reach as described above.

The all-solid-state lithium secondary battery according to the present invention is not limited in shape. For example, there are coin type, laminate type, cylinder type, square type, etc., among these, coin type, laminate type, etc. are preferable.

Although the use of the all-solid-state lithium secondary battery according to the present invention is not particularly limited, it may be used as an all-solid-state lithium secondary battery for automobiles. At this time, since generation of hydrogen sulfide can be suppressed even if moisture penetrates into the case due to damage or deformation of the case, it is safe and highly reliable.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples and comparative examples are only examples for explaining the present invention in detail, and the present invention is not limited to the following examples.

The specifications and physical properties of the specimens prepared through the following Examples and the like were measured as follows.

(Hydrogen sulfide adsorption efficiency)

The all-solid-state lithium secondary battery cells obtained in Examples and Comparative Examples were put into two reactors each having a temperature set at room temperature (25° C.) and high temperature (100° C.). Then, after supplying air with a relative humidity of 70% to the reactor at a rate of 500 cc/min for 10 minutes, the concentration of hydrogen sulfide in each reactor was measured.

(Sulphide-based all-solid-state lithium secondary battery)

A positive electrode active material (LiCoO ₂ ) and a sulfide-based solid electrolyte material (LiGe _0.25 P _0.75 S ₄ ) were mixed in a mass ratio of 7:3 to prepare a positive electrode mixture. Separately, a negative electrode active material (Li ₄ Ti ₅ O ₁₂ ) and a sulfide-based solid electrolyte material (LiGe _0.25 P _0.75 S ₄ ) were mixed in a 7:3 weight ratio to make a negative electrode mixture, and 15 mg of this positive electrode mixture and a sulfide-based solid Electrolyte material 200 mg, negative electrode active material (Li ₄ Ti ₅ O ₁₂ ), and indium foil 60 mg (thickness 0.2 mm) as the negative electrode were sequentially supplied to the mold, installed with a molding jig, and pressed at 5 t/cm 2 to have a diameter of about 10 mm and an electrode pellet of about 1.5 mm in thickness was produced.

And the electrode pellet prepared as described above is installed in the coin case and sealed with resin (polypropylene), but since submergence is assumed when the coin case (made by SUS) is damaged, the diameter 1 on the upper cover of the coin case A coin cell was prepared by drilling a hole of mm.

(Example 1)

When manufacturing the sulfide-based all-solid-state lithium secondary battery, a membrane-type hydrogen sulfide adsorbent was formed in the case before the electrode pellets were installed in the coin case. Specifically, potassium iodide (KI) and magnesium hydroxide (Mg(OH) ₂ ) are added to a solvent and dissolved by stirring, and the amounts of potassium iodide and magnesium hydroxide are 8 wt%, respectively, compared to titanium dioxide (TiO ₂ ) to be described later, 27% by weight. And 65 wt% of titanium dioxide was added thereto and stirred for 2 hours.

After stirring, the composition is put into a dryer formed at 80°C to completely evaporate moisture, then put into a mold and heat-treated at a temperature of 500°C under atmospheric atmosphere for 3 hours to plastically mold into a rectangular parallelepiped shape of 10mm×10mm×0.1mm. did. The molded adsorbent was adhered to the inner surface of the case with an adhesive (epoxy resin). After the bonding was completed, the electrode pellet was inserted into the case to prepare a secondary battery.

(Examples 2 to 8 and Comparative Examples 1 to 3)

A secondary battery was prepared in the same manner as in Example 1, except that the composition was prepared as shown in Table 1 when preparing the hydrogen sulfide adsorbent. At this time, the metal oxide of Example 6 was iron oxide (Fe ₂ O ₃ ), the metal hydroxide of Example 7 was manganese hydroxide (Mn(OH) ₂ ), and the adsorption improver of Example 8 was lithium iodide (LiI).

[Table 1]

[Table 2]

As shown in Table 2, Examples 1 and 6 to 8 in which the content of the metal oxide, the metal hydroxide and the adsorption improver satisfy the range of the present invention have a lower hydrogen sulfide concentration compared to other examples that do not satisfy the content range is showing In particular, in Example 1 using titanium dioxide as the metal oxide, magnesium hydroxide as the metal hydroxide, and potassium iodide as the adsorption improving agent, hydrogen sulfide was not generated, so iron oxide (Fe ₂ O ₃ ) was used as the metal oxide or manganese hydroxide as the metal hydroxide. (Mn(OH) ₂ ) or use of lithium iodide (LiI) as an adsorption improver compared to Examples 6 to 8 show better results.

Separately, Comparative Example 1, in which no adsorption improver was added, showed particularly poor hydrogen sulfide removal efficiency at high temperature, and Comparative Example 2, in which no metal hydroxide was added, had poor hydrogen sulfide removal efficiency at low temperature. And in Comparative Example 3, in which none of these were added, it can be seen that, despite the addition of metal salts, the hydrogen sulfide removal ability completely disappeared due to prolonged exposure to moisture, and thus the largest amount of hydrogen sulfide was generated.

As described above, although the present invention has been described with reference to preferred embodiments and test examples, those skilled in the art may vary the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be understood that modifications and changes can be made to

Claims (6)

An all-solid-state lithium secondary battery in which a sulfide-based solid electrolyte material is accommodated in a case, wherein the all-solid-state lithium secondary battery contains 50 to 80% by weight of titanium dioxide, 10 to 40% by weight of magnesium hydroxide, and 1 to 10 of potassium iodide as an adsorption improving agent A sulfide-based all-solid-state lithium secondary battery, characterized in that it further comprises a hydrogen sulfide adsorbent comprising wt%.
delete delete delete delete The method of claim 1,
The sulfide-based all-solid-state lithium secondary battery, characterized in that the hydrogen sulfide adsorbent is attached to the inner surface of the case.