KR20210075024A - A surface treatment method of secondary battery electrode materials or secondary battery electrode using gamma rays - Google Patents

Abstract

Provided is a surface treatment method of a secondary battery electrode material, including the steps of: bringing a secondary battery material in contact with a reaction solution; and irradiating gamma rays to the reaction solution in contact with the secondary battery material to form an organic layer or an inorganic layer on the surface of the secondary battery material, wherein the organic material layer formed by grafting a reactant formed according to the gamma ray irradiation on the surface of the secondary battery material, and the inorganic material layer is formed by coating the metal salt of the reaction solution, which is collapsed upon irradiation with gamma rays, on the surface of the secondary battery material.

Description

A surface treatment method of secondary battery electrode materials or secondary battery electrode using gamma rays

The present invention relates to a method for surface treatment of a material for a secondary battery electrode or an electrode for a secondary battery using gamma rays, and more particularly, a method for surface treatment of a material for a secondary battery electrode or an electrode for a secondary battery using gamma rays, and a secondary battery manufactured accordingly It relates to an electrode including a material for an electrode, a material for a secondary battery electrode, and a lithium secondary battery including the electrode.

Graphite is a material with a structure in which sp2 carbon is stacked, and as a material in which lithium is chemically inserted into graphite was announced in the 1950s, it received a lot of attention in the battery field. The graphite failed to find a stable electrolyte due to a low operating voltage and side reaction similar to that of lithium metal, but was commercialized as a carbonate-based electrolyte was successfully applied in the 1990s.

Recently, as the need for high-speed charging is required, studies to increase the charging speed by modifying graphite are receiving a lot of attention. The lithium ion transfer rate inside graphite can theoretically be used even at a high speed of 60 °C or higher. However, since lithium takes a lot of resistance in the process of desorption from the electrolyte on the surface of graphite and in the process of passing through the surface SEI (Solid Electrolyte Interphase) layer, there is a problem in that the required speed characteristics cannot be satisfied. Although many studies have been conducted to overcome this problem, there are few cases in which graphite capable of high-speed charge/discharge has been successfully commercialized due to the low chemical reactivity of graphite and dependence on carbonate-based electrolytes.

Silicon-based anode is a _{composite characterized in that it contains silicon and silicon oxide of SiO x} (0≤x≤2) composition and may contain conductive carbon materials such as graphite, carbon fiber, and carbon black, and has a higher theoretical capacity than graphite. Therefore, it is receiving much attention as a next-generation anode active material. However, unlike graphite, it has a severe volume expansion problem, and various approaches are being applied to solve it. In particular, the method of coating the silicon surface with an organic material is known to be effective in solving the problem of cracking and detachment from the electrode due to volume expansion of silicon, and many studies are being conducted. However, there are still no reports of surface treatment technology that can commercialize silicon, and there are still many problems to be solved to replace graphite.

Metal oxide is Li _1+a Ni _b Co _c Mn _d O ₂ (0 ≤ a ≤ 0.2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, b+c+d=1), Li _1+e [M _2-e ]O ₄ (0 ≤ e ≤ 0.15, M= one or more kinds of Mn, Ni, Cr, Fe, Co, Cu), Li _1+f Ni _g Co _h Al _i O ₂ (0 ≤ f ≤ 0.2, 0 < g < 1, 0 < h < 1, 0 < i < 1, g+h+i=1), LiFe _1-j M _k PO ₄ (M= one or more transition metal elements, 0 ≤ j ≤ 0.5, 0 ≤ k ≤ 0.5), Li _l Ti _m O _n (0 < l < 7, 0 < m < 6, 0 < n < 15) structures, etc. Because it has voltage and cycle characteristics, it has been used as a representative anode material until now. However, as the demand for a high capacity increases, an active material having a high nickel content is required, thereby exhibiting structural instability. In order to solve this problem, research on an interface that can effectively solve a side reaction with an electrolyte is in progress, and there is a high demand for a new interface technology that can stably maintain the surface even after a cycle and a metal oxide-based active material including the same.

Ceramic-based solid electrolytes are LiO ₂ -Al ₂ O ₃ -TiO ₂ -P ₂ O ₅ , LiO ₂ -SiO ₂ -TiO ₂ -P ₂ O ₅ , LiO ₂ -La ₂ O ₃ -ZrO _{2 ,} LiO ₂ -La ₂ O ₃ -TiO ₂ , Li ₄ SiO ₄ -Li ₃ PO ₄ , LiO ₂ -Al ₂ O ₃ -Ge ₂ O ₃ -P ₂ O ₅ structure is used, and unlike liquid electrolyte, it does not burn when exposed to heat. It is attracting attention as a stable alternative electrolyte. In particular, with the commercialization of electric vehicles, etc., the stability of the battery is being evaluated as an increasingly important factor, and a lot of research is being focused. However, the solid electrolyte does not have enough lithium ion conductivity to be commercialized due to high interfacial resistance between particles, and thus shows low reversibility. To solve this problem, an approach to reduce the interfacial resistance by coating an organic material on the surface of the metal oxide solid electrolyte is in progress, and it is known that the lithium ion conductivity of the oxide electrolyte can be increased through this.

On the other hand, gamma rays refer to strong forms of electromagnetic radiation with an energy of 10 keV or more. In general, the gamma rays are generated from high-energy electromagnetic radiation generated by atomic nuclear transition, and have a high transmittance of about several cm compared to electrons. Currently, it is commercially useful for sterilization of medical devices such as bacteria removal, and there is an advantage that it is possible to process continuously using a container belt.

Accordingly, the present inventors used gamma rays to convert the reactants in a liquid state to graphite for secondary battery electrodes, silicon-based anodes, metal oxides, metal sulfides, lithium metals, sodium metals, Magnesium metal, zinc metal, aluminum metal, sulfur-based composite, organic material containing a quinone group, polymer-based solid electrolyte, sulfide-based solid electrolyte or ceramic-based solid electrolyte and react with, and deform the surface, To solve the problem, a secondary battery material development process with improved interfacial properties was aimed.

Republic of Korea Patent Registration No. 10-1789205

The present invention is to solve the above-described problems, a method for surface treatment of a material for a secondary battery electrode capable of transforming the surface of a positive electrode, a negative electrode, and a solid electrolyte for a secondary battery electrode using gamma rays, and a secondary battery surface-treated accordingly We would like to provide a material for an electrode.

In addition, an object of the present invention is to provide a secondary battery electrode having improved interfacial properties by including the above-described material for secondary battery electrodes, and a lithium secondary battery including the electrode.

In order to solve the above problems, the present invention comprises the steps of contacting a material for a secondary battery with a reaction solution; and irradiating gamma rays (γ-ray) to the reaction solution in contact with the secondary battery material to form an organic material layer or an inorganic material layer on the surface of the secondary battery material; The organic material layer is a material for secondary batteries, wherein the reactant formed according to the gamma ray irradiation is grafted onto the surface of the material for the secondary battery, and the inorganic material layer is a metal salt of the reaction solution that collapses according to the gamma ray irradiation. The material for the secondary battery It provides a surface treatment method of a material for a secondary battery electrode, characterized in that the coating on the surface.

In one embodiment of the present invention, the step of forming the organic layer on the surface of the material for secondary batteries comprises irradiating gamma rays (γ-ray) to the reaction solution to generate radicals on the surface of the material for secondary batteries or the reaction solution, The reactants or decomposition products present in the reaction solution are grafted onto the surface of the material for secondary batteries.

In one embodiment of the present invention, the material for the secondary battery is graphite, silicon-based negative electrode, metal oxide, metal sulfide, lithium metal, sodium metal, magnesium metal, zinc It is at least one selected from the group consisting of metals, aluminum metals, sulfur-based composites, organic materials containing a quinone group, polymer-based solid electrolytes, sulfide-based solid electrolytes, and oxide-based solid electrolytes.

In an embodiment of the present invention, the material for the secondary battery is at least one selected from the group consisting of graphite, a silicon-based negative electrode, a metal oxide, and an oxide-based solid electrolyte.

In one embodiment of the present invention, the graphite is in the form of a powder, artificial graphite manufactured by heat-treating natural graphite or a carbon material as a raw material.

In an embodiment of the present invention, the silicon-based negative electrode includes silicon, intrinsic silicon, n-type silicon, or p-type silicon having a _{SiO x (0≤x≤2) composition.}

In an embodiment of the present invention, the silicon-based negative electrode includes at least one conductive carbon material selected from the group consisting of graphite, carbon fiber, pitch-based carbon, graphene, carbon nanotubes, activated carbon, and carbon black.

In one embodiment of the present invention, the metal oxide is Li _1+a Ni _b Co _c Mn _d O ₂ (0 ≤ a ≤ 0.2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, b +c+d=1), Li _1+e [M _2-e ]O ₄ (0 ≤ e ≤ 0.15, M= Mn, at least one of Ni, Cr, Fe, Co, Cu), Li _1+f Ni _g Co _h Al _i O ₂ (0 ≤ f ≤ 0.2, 0 < g < 1, 0 < h < 1, 0 < i < 1, g+h+i=1), LiFe _1-j M _k PO ₄ (M= one or more transition metal elements, 0 ≤ j ≤ 0.5, 0 ≤ k ≤ 0.5), Li _l Ti _m O _n (0 < l < 7, 0 < m < 6, 0 < n < 15) or these Li _x MO _y (M=Zr, Al, Sn, Nb, Ti, Ta, 0.9 ≤ x ≤ 1.2, 1 ≤ y ≤ 3.5) on the surface of the coated material or a combination thereof.

In an embodiment of the present invention, the oxide-based solid electrolyte is, LiO ₂ -Al ₂ O ₃ -TiO ₂ -P ₂ O ₅ , LiO ₂ -SiO ₂ -TiO ₂ -P ₂ O ₅ , LiO ₂ -La ₂ O ₃ -ZrO _{2 ,} LiO ₂ -La ₂ O ₃ -TiO ₂ , Li ₄ SiO ₄ -Li ₃ PO ₄ , and LiO ₂ -Al ₂ O ₃ -Ge ₂ O ₃ -P ₂ O ₅ more than one

In one embodiment of the present invention, the secondary battery material dispersed in the reaction solution is a powder having an average particle diameter in the range of 10 nm to 50 μm.

In an embodiment of the present invention, gamma rays are irradiated with an irradiation dose in the range of 1 to 1000 kGy at an irradiation dose rate in the range of 0.1 to 50 kGy/hr, and the reaction solution is water, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, alcohols, esters , including one or more solvents selected from the group consisting of ketones, ethers, carbonates, amides, nitriles and sulfones.

In one embodiment of the present invention, the reaction solution is N-vinyl-2 pyrrolidone, vinyl olefin monomer, vinyl aromatic monomer, vinyl halogen monomer, vinyl alcohol monomer, ether monomer, acrylate monomer, and at least one monomer selected from the group consisting of acrylic acid-based monomers, amide-based monomers, nitrile-based monomers and sulfone-based monomers.

The present invention also provides a material for a secondary battery; And a polymer-based organic material layer surrounding the surface of the secondary battery material; It provides a material for a secondary battery electrode prepared by the surface treatment method of the material for a secondary battery electrode, including a.

In one embodiment of the present invention, the thickness of the organic material layer ranges from 0.1 nm to 10 μm on average.

The present invention also provides a secondary battery electrode comprising the secondary battery material.

The present invention provides a lithium secondary battery including the secondary battery electrode described above.

The present invention comprises the steps of immersing an electrode for a secondary battery in a reaction solution or applying the reaction solution to an electrode for a secondary battery; and irradiating a reaction solution containing an electrode for a secondary battery or an electrode for a secondary battery coated with the reaction solution with gamma rays (γ-ray) to form an organic material layer on the surface of the electrode for a secondary battery; Including, the step of forming the organic material layer on the surface of the electrode for secondary battery, irradiating gamma rays (γ-ray) to the reaction solution to generate radicals on the surface of the electrode for secondary batteries or the reaction solution, and present in the reaction solution It provides a surface treatment method for a secondary battery electrode, characterized in that grafting the reactant or decomposition product to the surface of the secondary battery electrode.

In the present invention, the secondary battery electrode is, graphite, silicon-based negative electrode, metal oxide, metal sulfide, lithium metal, sodium metal, magnesium metal, zinc metal, aluminum metal, and at least one selected from the group consisting of a sulfur-based complex, an organic material including a quinone group, a polymer-based solid electrolyte, a sulfide-based solid electrolyte, and an oxide-based solid electrolyte.

In an embodiment of the present invention, the gamma rays are irradiated with an irradiation dose in the range of 1 to 1000 kGy at an irradiation dose rate in the range of 0.1 to 50 kGy/hr.

In one embodiment of the present invention, the reaction solution includes at least one solvent selected from the group consisting of water, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, alcohols, esters, ketones, ethers, carbonates, amides, nitriles and sulfones. do.

In one embodiment of the present invention, the reaction solution is N-vinyl-2 pyrrolidone, vinyl olefin monomer, vinyl aromatic monomer, vinyl halogen monomer, vinyl alcohol monomer, ether monomer, acrylate monomer, It may include one or more monomers selected from the group consisting of acrylic acid-based monomers, amide-based monomers, nitrile-based monomers and sulfone-based monomers.

The present invention also provides an electrode for a secondary battery; and a polymer-based organic material layer surrounding the surface of the electrode for a secondary battery. It includes, and provides an electrode for a secondary battery manufactured by the above-described surface treatment method.

In an embodiment of the present invention, the thickness of the organic material layer ranges from 0.1 nm to 10 μm on average.

The present invention also provides a lithium secondary battery including the secondary battery electrode described above.

The present invention also includes the steps of immersing an electrode for a secondary battery in a reaction solution or contacting a reaction solution containing a metal salt to an electrode for a secondary battery; and irradiating the reaction solution with gamma rays (γ-ray); It provides a secondary battery electrode manufacturing method comprising the step of forming an inorganic material layer obtained from the metal salt that decays according to the irradiated gamma rays ((γ-ray) on the surface of the secondary battery electrode.

In one embodiment of the present invention, the reaction solution is LiF, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiB(Ph) ₄ , LiC ₄ BO ₈ , LiPF ₆ , LiCF ₃ SO ₃ , _{LiCF 3 CO 2, LiAsF 6,} LiSbF 6, LiAlCl 4, LiSO 3 CH 3, LiSO 3 CF 3, LiSCN, LiC (CF 3 SO 2) 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenyl borate, and at least one component selected from the group consisting of imides, wherein the energy of the gamma rays ionizes the metal salt level that can be done.

In an embodiment of the present invention, an inorganic material layer including a metal salt that has collapsed according to gamma ray (γ-ray) irradiation is formed on the surface of the secondary battery electrode.

The present invention also provides a secondary battery including the secondary battery electrode described above.

The present invention can easily form a decomposition layer of various components on the surface of a material with relatively low reactivity by dispersing a material for a secondary battery in a reaction solution or immersing/applying an electrode for a secondary battery and then irradiating with gamma rays. In the same principle, the decomposition layer can be coated by applying a reaction solution on the secondary battery electrode and then irradiating gamma rays.

In particular, it is possible to form a decomposition layer by reacting a reaction solution with a material for a secondary battery or an electrode for a secondary battery without adding an additional reaction initiator or the like in the process of irradiating the gamma rays.

As a result, the secondary battery electrode material or secondary battery electrode manufactured in this way has a surface modified by the decomposition layer to provide a secondary battery in which problems such as rate limit problem and low cycle efficiency of conventional materials are effectively improved.

1 is a flowchart illustrating a surface treatment method of a material for a secondary battery electrode according to an embodiment of the present invention.
2 is a flowchart illustrating a method for surface treatment of a secondary battery electrode according to an embodiment of the present invention.
3 is a view showing TGA data of the graphite coated in Preparation Example 1.
4 is a view showing SEM-EDS data of the graphite coated in Preparation Example 1.
5 is a graph showing the rate-rate characteristics of the coated graphite prepared in Example 1 and Comparative Example 1 in a constant current mode;
6 is a graph showing the electrochemical characteristics of the micro-silicon negative electrode prepared in Example 2 and Comparative Example 2 in a constant current mode.
7 is a graph showing cycle characteristics of the metal oxide anodes prepared in Example 3 and Comparative Example 3 in a constant current mode.
8 is a graph showing the lithium ion conductivity measurement of the oxide solid electrolyte prepared in Example 4 and Comparative Example 4;
9 is a graph comparing rate characteristics using the lithium secondary batteries prepared in Comparative Example 1 and Examples 5-13.
10 is a graph comparing the rate and discharge characteristics of Comparative Example 5 and Example 14 treated with gamma rays.

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present invention, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the possibility of addition or existence of numbers, steps, operations, components, parts, or combinations thereof.

In order to solve the above problem, the present invention is an organic material layer or an inorganic material layer that can affect the secondary battery performance by contacting a reaction solution capable of reacting with gamma rays to a material for secondary battery electrodes and irradiating the contacted reaction solution with gamma rays to form

Therefore, the method for manufacturing a secondary battery electrode according to an embodiment of the present invention includes the steps of contacting a material for a secondary battery with a reaction solution; and irradiating gamma rays (γ-ray) to the reaction solution in contact with the secondary battery material to form an organic material layer or an inorganic material layer on the surface of the secondary battery material; includes,

The organic material layer formed according to the selection of the reaction solution is a material formed by the gamma ray irradiation is grafted onto the surface of the secondary battery material. In addition, if the coating layer formed by gamma ray irradiation is an inorganic material layer, the inorganic material layer may be one in which a metal salt of a reaction solution that is disintegrated according to the gamma ray irradiation is coated on the surface of the material for secondary batteries.

That is, the present invention relates to a method for surface treatment of a material for a secondary battery electrode capable of deforming the surface of the material for a secondary battery electrode by using gamma rays, and a material for a secondary battery electrode manufactured thereby.

In addition, it relates to a secondary battery electrode having an interface of improved performance by including the material for the secondary battery electrode described above, and a lithium secondary battery including the electrode.

When graphite is used as an electrode material, the lithium ion transfer rate in the graphite can be theoretically used even at a high speed of 60° C. or higher. However, there is a problem in that the required speed characteristics cannot be satisfied because a lot of resistance is taken in the process of lithium being desorbed from the electrolyte and passing through the surface SEI layer on the surface of the graphite.

When silicon is used as an electrode material, it is in the spotlight as a new cathode material because it has a similar operating voltage and relatively high capacity to graphite. However, the silicon includes severe volume expansion during the charging and discharging process, and thus has problems such as cracking and detachment from the electrode.

When a cobalt-based layered metal oxide is used as an electrode material, a high operating voltage and cycle characteristics can be obtained as an anode, so it is used as a representative anode material. However, as the demand for high capacity increases, the content of nickel is increased, and as a result, there is a problem of poor reversibility due to the structural change caused by the instability of the interface.

When a metal oxide-based solid electrolyte is used as an electrode material, unlike a liquid electrolyte, it does not burn, and thus is in the spotlight as a stable alternative electrolyte. However, it showed low reversibility due to the high interfacial resistance between the electrolyte particles.

Accordingly, the present invention uses gamma rays to react a liquid reactant with a material for a secondary battery of graphite, a silicon-based negative electrode, a metal oxide-based positive electrode, or a ceramic-based solid electrolyte. To provide a surface treatment method of a material for a secondary battery electrode that can improve the interface problem, a secondary battery electrode including the secondary battery electrode material, a secondary battery electrode including the secondary battery electrode material, and a lithium secondary battery including the electrode .

Hereinafter, the present invention will be described in more detail.

Surface treatment method of materials for secondary battery electrodes

1 is a flowchart illustrating a surface treatment method of a material for a secondary battery electrode according to an embodiment of the present invention. Referring to FIG. 1 , the method for surface treatment of a material for a secondary battery electrode according to the present invention includes the steps of dispersing a secondary battery material in a reaction solution (S100); and

Forming a decomposition layer on the surface of the secondary battery material by irradiating gamma rays (γ-ray) to the reaction solution containing the secondary battery material (S200); includes,

In the step of forming a decomposition layer on the surface of the material for secondary batteries, gamma rays (γ-ray) are irradiated to the reaction solution to generate radicals on the surface or reaction solution of the material for secondary batteries, and reactants present in the reaction solution or It is characterized in that the decomposition product is grafted onto the surface of the material for secondary batteries.

According to an embodiment of the present invention, when gamma rays are irradiated to a reaction solution in which a solid electrode material is dispersed, energy of gamma rays is absorbed from the surface of the material and the reaction solution to form radicals, and is present in the reaction solution Since they can easily react with other molecules that do this, a decomposition layer containing oxygen, nitrogen, hydrogen, etc. can be easily formed on the surface of the material. More specifically, as described above, in the step of forming the decomposition layer on the surface of the material for secondary batteries, gamma rays (γ-ray) are irradiated to the reaction solution in which the material for secondary batteries is dispersed, and the surface or reaction of the material for secondary batteries is By generating radicals in the solution, the reactants present in the reaction solution may be grafted or the decomposition product may be coated on the surface.

The secondary battery material can be dispersed in the reaction solution and irradiated with radiation. As the radiation, conventional gamma rays (γ-rays), ultraviolet rays (UV), electron beams (β-rays), ion beams, neutron beams, and X-rays may be used. Meanwhile, since gamma rays have a penetration depth of several cm, a continuous coating process is possible, and thus, in an embodiment of the present invention, the radiation may be gamma rays (γ-rays). More specifically, the reaction solution may be irradiated with gamma rays in the range of 1 to 1000 kGy at an irradiation dose rate in the range of 0.1 to 50 kGy/hr. The irradiation dose of the gamma rays may vary in the range depending on the type of the reaction solution, but preferably at an irradiation dose rate in the range of 0.5 to 10 kGy/hr, and may be in the range of 5 to 500 kGy. At this time, if the irradiation dose rate is less than 0.1 kGy / hr, the surface treatment time may be very long and productivity may be lowered, and if it exceeds 50 kGy / hr, thermal damage may be caused, which may cause deterioration of the performance of the material. In addition, when the total irradiation amount of gamma rays is less than 1 kGy, the amount of reaction may be insignificant and may be difficult to utilize, and if it exceeds 1000 kGy, the material and bonding may be broken a lot, so that undesirable lowered physical properties may be obtained. Therefore, the above-mentioned gamma-ray irradiation range is preferable.

In particular, according to the method for surface treatment of a material for a secondary battery electrode of the present invention, by controlling the amount of gamma rays irradiated to the reaction solution in which the electrode material is dispersed, the degree of surface treatment can be easily adjusted, and the chemical modification reaction Since an additional initiator is not used, a large amount of material for secondary batteries can be easily surface-modified.

In addition, in the method for surface treatment of a material for a secondary battery electrode according to an embodiment of the present invention, the solvent is water, aromatic hydrocarbon, aliphatic hydrocarbon, halogenated hydrocarbon, alcohol, ester, ketone, ether, carbonate, amide, nitrile, sulfone series. It may include one or more selected from the group consisting of. In this case, in consideration of the dispersibility of the electrode material, it is preferable to select a solvent having excellent dispersibility, and may further include a monomer having a structure that is easily polymerized in the solvent.

Specifically, the monomer is N-vinyl-2 pyrrolidone, vinyl olefin-based monomer, vinyl aromatic monomer, vinyl halogen-based monomer, vinyl alcohol-based monomer, ether-based monomer, acrylate-based monomer, acrylic acid-based monomer, amide-based monomer , may be at least one selected from the group consisting of nitrile-based monomers and sulfone-based monomers. In this case, the coating layer can be controlled through the ratio and irradiation amount of the solvent and the monomer, and the structure of the monomer may include a vinyl-based functional group that easily initiates a polymerization reaction through a radical reaction, a ring structure, etc. For example, N-methyl-2 - may be pyrrolidone, or may be N-vinyl-2-pyrrolidone. However, in the case of using the N-vinyl-2-pyrrolidone, polymerization occurs severely, and the entire solution in which graphite is dispersed may become a hard gel, so it may be used by reacting with DMF. In this case, the weight ratio of NVP and DMF may be 9:1.

In addition, the reaction solution after irradiation with gamma rays is dried under vacuum at room temperature after removing the supernatant of the mixture to complete the surface treatment of the graphite-based material for secondary battery electrodes. In this case, it may be dried for an average of 6 to 16 hours, for example, it may be dried by treatment for 12 hours.

On the other hand, the material for the secondary battery is graphite in the form of particles or powder, a silicon-based negative electrode, a metal oxide, a metal sulfide, a lithium metal, a sodium metal, a magnesium metal, a zinc metal, It may be an aluminum metal, a sulfur-based composite, an organic material including a quinone group, a polymer-based solid electrolyte, a sulfide-based solid electrolyte or a ceramic-based solid electrolyte, or an electrode for a secondary battery made using the same. More specifically, the material for the secondary battery may be at least one selected from the group consisting of graphite, a silicon-based negative electrode, a metal oxide, and an oxide-based solid electrolyte, or may be graphite.

Graphite is in the form of a powder, and may be artificial graphite manufactured by heat-treating natural graphite or a carbon material as a raw material.

The silicon-based negative electrode may _{include silicon, intrinsic silicon, n-type silicon or p-type silicon of SiO x} (0≤x≤2) composition, and in a specific embodiment, the silicon-based negative electrode is graphite, carbon fiber, pitch-based carbon, yes It may be a composite including one or more conductive carbon materials selected from the group consisting of fins, carbon nanotubes, activated carbon, and carbon black.

Metal oxide is Li _1+a Ni _b Co _c Mn _d O ₂ (0 ≤ a ≤ 0.2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, b+c+d=1), Li _1+e [M _2-e ]O ₄ (0 ≤ e ≤ 0.15, M= Mn, at least one of Ni, Cr, Fe, Co, Cu), Li _1+f Ni _g Co _h Al _i O ₂ ( 0 ≤ f ≤ 0.2, 0 < g < 1, 0 < h < 1, 0 < i < 1, g+h+i=1), LiFe _1-j M _k PO ₄ (M= one or more transition metal elements) , 0 ≤ j ≤ 0.5, 0 ≤ k ≤ 0.5), Li _l Ti _m O _n (0 < l < 7, 0 < m < 6, 0 < n < 15) or Li _x MO _y (M =Zr, Al, Sn, Nb, Ti, Ta, 0.9 ≤ x ≤ 1.2, 1 ≤ y ≤ 3.5) coated material or a combination thereof.

Oxide-based solid electrolytes are LiO ₂ -Al ₂ O ₃ -TiO ₂ -P ₂ O ₅ , LiO ₂ -SiO ₂ -TiO ₂ -P ₂ O ₅ , LiO ₂ -La ₂ O ₃ -ZrO _{2 ,} LiO ₂ -La ₂ O ₃ -TiO ₂ , Li ₄ SiO ₄ -Li ₃ PO ₄ , and LiO ₂ -Al ₂ O ₃ -Ge ₂ O ₃ -P ₂ O ₅ may be at least one selected from the group consisting of.

Metal sulfide is a sulfide having _{a two-dimensional layered structure represented by MS 2} (M = at least one of Ti, Mo, Mn) and M _x Mo ₆ S ₈ (M = at least one of Mg, Pb, Ag, Cu, 0≤ x≤2), and may have a Chevrel phase structure.

The lithium metal may be an alloy including at least one metal selected from the group consisting of Al, Si, Ge, Sn, Pb, Sb, Bi, and Mg. In addition, the lithium metal may be in the form of powder, foam or foil.

The sodium metal may be sodium metal. Or it may be an alloy containing sodium. In a specific embodiment, it may be an inorganic material including sodium. In addition, the sodium metal may be in the form of powder, foam or foil.

The magnesium metal may be a magnesium metal, or may be an alloy containing magnesium. In a specific embodiment, it may be an inorganic material including magnesium. In addition, the magnesium metal may be in the form of powder, foam or foil.

The zinc metal may be a zinc metal, or may be an alloy containing zinc. In a specific embodiment, it may be an inorganic material including zinc. In addition, the zinc metal may be in the form of powder, foam or foil.

The aluminum metal may be an aluminum metal, and may be an alloy including aluminum. In a specific embodiment, it may be an inorganic material including aluminum. In addition, the aluminum metal may be in the form of powder, foam or foil.

The sulfur-based composite is inorganic sulfur (S ₈ , elemental sulfur), Li ₂ S _n (n≥1), an organic sulfur compound, a carbon-sulfur polymer ((C ₂ S _x ) _n , where x=2.5-50 , n≥2) and may be a cathode active material for a lithium sulfur battery comprising at least one selected from the group consisting of a layered inorganic sulfur compound.

The organic material-based complex including the quinone group is selected from the group consisting of quinone, ketone, aromatic imides, polyacetylene, and polymerized carbonyl compound. It may include more than one.

Polymer-based solid electrolytes are ion conductive polymer materials such as polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polypropylene carbonate (PPC), polyphenylene sulfide ( PPS), polymethacrylic acid ester, polyvinylidene fluoride (PVdF), copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), poly(methyl acrylate) ( PMA), poly(methylmethacrylate) (PMMA), mixtures of the above polymers, modifications of the above polymers, derivatives of the above polymers, random copolymers of the above mentioned polymers, alternating copolymers of the above mentioned polymers, It may be a graft copolymer, a block copolymer of the aforementioned polymers, or a combination thereof.

A sulfide-based solid electrolyte, in the form of AMSX, A contains at least one of Li, Na, K, Mg, Ca, Zn, and M is P, Sb, Si, Ge, Sn, B, Al, Ga, In, Ti , Zr, V, and one or more of Nb, and X may include F, Cl, Br, I, and may be in a powder form.

Graphite-based material for secondary battery electrodes

The present invention is a graphite-based material for a secondary battery electrode according to an embodiment is a graphite-based material for a secondary battery electrode manufactured according to the surface treatment method of the graphite-based material for a secondary battery electrode described above, more specifically, graphite and a decomposition layer surrounding the surface of graphite.

The graphite may be in the form of a powder as a graphite-based material, and may be in the form of a powder having an average particle diameter in the range of 50 nm to 50 μm, and may have good dispersibility in the reaction solution. When the average particle diameter of the graphite is less than 50 nm, it is not suitable for use as an electrode material, and when it exceeds 50 μm, an ion conductivity problem in the particles may occur. Therefore, the size of the above-mentioned range is preferable.

In this case, the thickness of the decomposition layer may be in the range of 0.5 to 100 nm on average, 1 to 90 nm on average, 2 to 80 nm on average, 3 to 50 nm on average, 4 to 20 nm on average, or 10 nm on average. can If the thickness of the decomposition layer coated on the graphite surface is less than 0.5 nm, the effect on the electrochemical performance may be insignificant, and if it exceeds 100 nm, the conduction of lithium ions may be inhibited. Therefore, the above-mentioned thickness range is preferable.

Such a decomposition layer may be included on the graphite surface, and the decomposition layer may react with the electrolyte to form a new interface, and thus SEI may be controlled, which may be advantageous for lithium ion transport.

Silicon-based material for secondary battery electrodes

In the present invention, the silicon-based material for secondary battery electrodes according to an embodiment is a silicon-based material for secondary battery electrodes manufactured according to the surface treatment method of the silicon-based material for secondary battery electrodes described above, and more specifically, silicon and a decomposition layer surrounding the surface of silicon.

The silicon material may be in the form of a powder, the average particle diameter may be in the form of a powder in the range of 10 nm to 50 μm, and may have good dispersibility in the reaction solution. When the average particle diameter of the graphite is less than 10 nm, it is not suitable for use as an electrode material, and when it exceeds 50 μm, a problem may occur due to severe volume expansion of the material. Therefore, the size of the above-mentioned range is preferable.

In this case, the thickness of the decomposition layer may be in the range of 0.5 to 100 nm on average, 1 to 90 nm on average, 2 to 80 nm on average, 3 to 50 nm on average, 4 to 20 nm on average, or 10 nm on average. can If the thickness of the decomposition layer coated on the silicon surface is less than 0.5 nm, the effect in solving the problem of volume expansion may be insignificant, and if it exceeds 100 nm, the conduction of lithium ions may be inhibited. Therefore, the above-mentioned thickness range is preferable.

Such a decomposition layer may be included on the silicon surface, and the decomposition layer may react with the electrolyte to form a new interface, which may be advantageous in preventing problems such as cracks and desorption from volume expansion.

Metal oxide-based materials for secondary battery electrodes

The present invention is a metal oxide-based material for secondary battery electrodes according to an embodiment is a metal oxide-based material for secondary battery electrodes manufactured according to the above-described method for surface treatment of a metal oxide-based material for secondary battery electrodes, and more specifically, cobalt (cobalt), nickel (nickel) and manganese (manganese) is composed of a metal oxide containing a transition metal and a decomposition layer surrounding the surface.

The metal oxide may be in the form of a cobalt, nickel, and manganese-based oxide material, and may be in the form of a powder having an average particle diameter in the range of 50 nm to 50 μm, and may have good dispersibility in the reaction solution. When the average particle diameter of the metal oxide is less than 50 nm, it is not suitable for use as an electrode material, and when it exceeds 50 μm, an ion conductivity problem in the particle may occur. Therefore, the size of the above-mentioned range is preferable.

In this case, the thickness of the decomposition layer may be in the range of 0.5 to 100 nm on average, 1 to 90 nm on average, 2 to 80 nm on average, 3 to 50 nm on average, 4 to 20 nm on average, or 10 nm on average. can If the thickness of the decomposition layer coated on the surface of the metal oxide is less than 0.5 nm, the effect of increasing electrochemical reversibility may be insignificant, and if it exceeds 100 nm, lithium ions and electrical conduction may be inhibited. Therefore, the above-mentioned thickness range is preferable.

Such a decomposition layer may be included on the surface of the metal oxide, and the decomposition layer may react with the electrolyte to form a new interface, and through this, a side reaction with the electrolyte may be controlled, so it may be advantageous to have long-term reversible cycle characteristics. have.

Ceramic-based solid electrolyte material for secondary battery electrodes

The present invention is a secondary battery electrode solid electrolyte material according to an embodiment is a metal oxide-based material for secondary battery electrodes manufactured according to the surface treatment method of the solid electrolyte material for secondary battery electrodes described above, more specifically, in a solid state It consists of a metal oxide electrolyte and a decomposition layer surrounding the surface.

The solid electrolyte may be in a powder form as a metal oxide-based material that may include lithium, aluminum, titanium, etc., and may be in a powder form having an average particle diameter in the range of 50 nm to 50 μm, and has good dispersibility in the reaction solution. may have When the average particle diameter of the metal oxide is less than 50 nm, it is not suitable for use as an electrode material, and when it exceeds 50 μm, an ion conductivity problem between interfaces may occur. Therefore, the size of the above-mentioned range is preferable.

In this case, the thickness of the decomposition layer may range from 0.5 nm to 5 µm on average, 1 to 1 µm on average, 5 to 500 nm on average, 10 to 100 nm on average, 20 to 50 nm on average, or 30 nm on average. can be If the thickness of the decomposition layer coated on the surface of the solid electrolyte is less than 0.5 nm, low ionic conductivity may be exhibited due to high interfacial resistance, and if it exceeds 5 μm, it may exhibit heat-sensitive properties. Therefore, the above-mentioned thickness range is preferable.

Such a decomposition layer may be included on the surface of the metal oxide-based solid electrolyte, and the decomposition layer may reduce the interfacial resistance between the solid electrolytes, which may be advantageous in having improved lithium ion conductivity.

secondary battery electrode

The present invention provides a secondary battery electrode comprising the above-described electrode material.

More specifically, the secondary battery electrode may be a negative electrode, a positive electrode, or a solid electrolyte. That is, the graphite and silicon-based material may be used as an anode material, and the metal oxide-based material may be used as an anode material and may be used as a solid electrolyte.

The graphite-based material according to the present invention includes a decomposition layer on the graphite surface, and the decomposition layer ^{reversibly facilitates intercalation or deintercalation of lithium ions (Li +} ), thereby providing a high rate of graphite-based material. characteristics can be expected. In addition, the decomposition layer may be effective in solving the problem of cracking and detachment from the electrode by dispersing the total stress generated from the volume expansion of the silicon-based active material.

The negative electrode includes an anode active material including the graphite-based material, a silicon-based material, and an anode current collector on which the anode active material is disposed on at least one surface.

The negative electrode current collector is platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), silver (Ag), rhodium (Rh), ruthenium (Ru), nickel (Ni), stainless steel, aluminum ( Al), molybdenum (Mo), chromium (Cr), copper (Cu), titanium (Ti), tungsten (W), ITO (In doped SnO ₂ ), FTO (F doped SnO ₂ ), and Si wafers It may be formed of at least any one of the formed metals.

Since the metal oxide-based material according to the present invention includes a decomposition layer on the surface, the decomposition layer reduces side reactions with the electrolyte and alleviates performance degradation due to structural changes, so that reversible cycle characteristics can be expected. In addition, the decomposition layer may be effective in increasing the conductivity of lithium ions when used as a solid electrolyte by reducing the interfacial resistance of the surface of the metal oxide.

The positive electrode includes the metal oxide-based material, a positive electrode active material including the metal oxide-based material, and a positive electrode current collector on which the positive electrode active material is disposed on at least one surface.

The positive electrode current collector may be formed of at least one of stainless steel, aluminum, nickel, titanium, sintered carbon, or a surface treatment of aluminum or stainless steel with carbon, nickel, titanium, silver, or the like.

The solid electrolyte includes the metal oxide-based material, a solid electrolyte including the metal oxide-based material, and an electrode including the solid electrolyte.

Since the structure and components of the anode, the anode, and the solid electrolyte are known to those of ordinary skill in the art to which the present invention pertains, a detailed description thereof will be omitted below.

lithium secondary battery

The present invention provides a lithium secondary battery including a secondary battery electrode.

More specifically, the lithium secondary battery is accommodated in the battery case as the positive electrode, the above-described negative electrode, and the separator are wound or folded. Then, electrolyte is injected into the battery case and sealed with a cap assembly to complete a lithium secondary battery.

The electrolyte may be a non-aqueous electrolyte, and the non-aqueous electrolyte contains a lithium salt and is composed of a lithium salt and an electrolyte, and as a solvent, a non-aqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte may be used. .

The lithium salt is a material that can be easily dissolved in a non-aqueous organic electrolyte, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiB(Ph) ₄ , LiC ₄ BO ₈ , LiPF ₆ , _{LiCF 3 SO 3, LiCF 3 CO} 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiSO 3 CH 3, LiSO 3 CF 3, LiSCN, LiC (CF 3 SO 2) 3, LiN (CF 3 SO 2) 2, LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenyl borate, and imide may be at least one selected from the group consisting of.

The concentration of the lithium salt varies from 0.1 to 6.0, depending on several factors such as the exact composition of the electrolyte mixture, the solubility of the salt, the conductivity of the dissolved salt, the charging and discharging conditions of the battery, the operating temperature and other factors known in the art of lithium-sulfur batteries. M, preferably 0.5M to 2.0M. If the concentration of the lithium salt is less than the above range, the conductivity of the electrolyte may be lowered and battery performance may be deteriorated. If the concentration of the lithium salt is greater than the above range, the viscosity of the electrolyte may increase and ^{the mobility of lithium ions (Li +} ) may be reduced within the above range. It is preferable to select an appropriate concentration in

The non-aqueous organic solvent is a material capable of dissolving lithium salts well, and is preferably N-methyl-2-pyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate. , diethyl carbonate, ethylmethyl carbonate, gamma-butylolactone, 1,2-dimethoxy ethane, 1,2-diethoxy ethane, 1-ethoxy-2-methoxy ethane, tetraethylene glycol dimethyl ether, Tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, 4-methyl-1,3-dioxene, diethyl ether, formamide, dimethylformamide, dioxolane , acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate Aprotic organic solvents such as derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, and ethyl propionate may be used, and one or more of them may be used in the form of a mixed solvent.

The organic solid electrolyte is preferably a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphoric acid ester polymer, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, ionic A polymer containing a dissociating group, etc. can be used.

The inorganic solid electrolyte of the present invention is preferably Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI-LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ Nitride, halide, sulfate, etc. of Li can be used.

Method for surface treatment of secondary battery electrode, secondary battery electrode manufactured accordingly, and secondary battery comprising same

2 is a flowchart illustrating a method for surface treatment of a secondary battery electrode according to an embodiment of the present invention. 2, the step of immersing the electrode for a secondary battery in a reaction solution or applying the reaction solution to the electrode for a secondary battery (S110); and forming a decomposition layer on the surface of the secondary battery electrode by irradiating gamma rays (γ-ray) to the reaction solution containing the secondary battery electrode or the secondary battery electrode coated with the reaction solution (S120); includes,

In the step of forming the decomposition layer on the surface of the electrode for secondary batteries, gamma rays (γ-ray) are irradiated to the reaction solution to generate radicals on the surface of the electrode for secondary batteries or the reaction solution, and reactants present in the reaction solution or It is characterized in that the decomposition product is grafted onto the surface of the electrode for the secondary battery.

As described above, when gamma rays are irradiated to the reaction solution in which the solid electrode is immersed or the electrode to which the reaction solution is applied, the energy of gamma rays is absorbed from the surface of the electrode and the reaction solution to form radicals, Since they can easily react with other molecules present in the reaction solution, decomposition containing oxygen, nitrogen, hydrogen, etc. can be easily generated on the surface of the electrode.

On the other hand, the secondary battery electrode, graphite, silicon-based negative electrode, metal oxide (metal oxide), metal sulfide (metal sulfide), lithium metal, sodium metal, magnesium metal, zinc metal, aluminum metal, sulfur-based It may include at least one selected from the group consisting of a composite, an organic material including a quinone group, a polymer-based solid electrolyte, a sulfide-based solid electrolyte, and an oxide-based solid electrolyte. Specific materials and manufacturing methods are the same as described above, and thus will be omitted.

The present invention provides an electrode for a secondary battery.

More specifically, the secondary battery electrode; And a polymer-based decomposition layer surrounding the surface of the secondary battery electrode; It provides an electrode for a secondary battery comprising a.

Specifically, the secondary battery electrode may be a secondary battery electrode manufactured by the above-described surface treatment method of the secondary battery electrode.

In this case, the thickness of the decomposition layer may be in the range of 0.1 nm to 10 μm on average.

The present invention provides a lithium secondary battery including the secondary battery electrode.

Hereinafter, the structure and components of a lithium secondary battery are known to those of ordinary skill in the art to which the present invention pertains, and thus detailed description thereof will be omitted.

Hereinafter, the present invention will be described in more detail by way of Examples and Experimental Examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following Examples and Experimental Examples.

<Production Example>

Preparation Example 1. Surface coating of graphite using gamma rays

First, a solution in which graphite is dispersed was prepared by mixing 0.5 ml of N-vinyl-2-pyrrolidone (NVP) and 1 g of graphite in 10 ml of N,N-dimethylformamide (DMF). Then, the solution was irradiated with 50 kGy at a rate of 2 kGy/hr for 25 hours using high-level gamma rays. Then, after removing the supernatant of the mixture, the mixture was dried under vacuum at room temperature for 12 hours. Accordingly, graphite was coated using gamma rays.

Preparation Example 2. Surface coating of silicon using gamma rays

First, a silicone-dispersed solution was prepared by mixing 1 ml of acrylic acid and 1 g of micro silicone (1-5 μm) in 10 ml of distilled water. Then, in order to prevent gelation of the solution, 50 mg of copper sulfate was mixed, and 250 kGy was irradiated at a rate of 10 kGy/hr using high-level gamma rays for 25 hours. Then, after removing the supernatant of the mixture, the mixture was dried under vacuum at room temperature for 12 hours. Accordingly, the silicon surface was coated with acrylic acid using gamma rays.

Preparation Example 3. Surface coating of metal oxide anode using gamma rays

First, 0.5 ml of pyrrole and 1 g of nickel cobalt manganese oxide (Nickel : Cobalt : Manganese = 8 : 1 : 1) were mixed with 10 ml of ethanol to prepare a solution in which the metal oxide was dispersed. Then, the solution was irradiated with 250 kGy at a rate of 10 kGy/hr for 25 hours using high-level gamma rays. Then, after removing the supernatant of the mixture, the mixture was dried under vacuum at room temperature for 12 hours. Accordingly, the surface of the metal oxide anode was coated with pyrrole using gamma rays.

Preparation Example 4. Surface coating of oxide solid electrolyte using gamma rays

First, a solution in which an oxide solid electrolyte was dispersed was prepared by mixing 5 g of _{LiClO 4 1M acrylonitrile solution and an oxide solid electrolyte (LAGP).} Then, the solution was irradiated with 250 kGy at a rate of 10 kGy/hr for 25 hours using high-level gamma rays. Then, after removing the supernatant of the mixture, the mixture was dried under vacuum at room temperature for 12 hours. Accordingly, the surface of the oxide solid electrolyte was coated with acrylonitrile using gamma rays.

Preparation Example 5. Graphite electrode coating using gamma rays

Graphite was dispersed in water to prepare a slurry, and then cast to copper foil to prepare an electrode. The loading of the electrode ^{was the same at 8 mg/cm 2} , and in this case, the ratio of the slurry was configured such that the ratio of graphite: Super-P: SBR: CMC was 93: 3: 2: 2. Then, drying was performed in an oven at 70 °C for 12 hours.

The thus-prepared electrode was placed in a vial, immersed in various gamma-ray-treated electrolytes, and sealed under an argon composition. The sealed vials were treated for various times under gamma radiation at an irradiation rate of 2 kGy/hr. Specific gamma-ray treatment electrolyte conditions and time are shown in Table 1. The gamma-ray-treated graphite electrode was opened under an argon atmosphere, washed with DEC electrolyte, and dried. All treatment processes were carried out without exposure to air.

<Example>

Example 1. Preparation of a lithium secondary battery using graphite coated using gamma rays

In Preparation Example 1, a lithium secondary battery was prepared using graphite coated with NVP (N-vinyl-2-pyrrolidone) using gamma rays. More specifically, the graphite coated in Preparation Example 1 was dispersed in water to prepare a slurry, and then cast to copper foil to prepare an electrode.

The electrode was loaded with the same amount of 8 mg/cm ² , and at this time, the ratio of the slurry was configured such that the ratio of graphite: Super-P: SBR: CMC was 93: 3: 2: 2. And, the electrode dried in 70 ◎ oven for 12 hours was made of lithium metal as a reference electrode in a glove box under argon gas, and 1 M LiPF ₆ was dissolved in EC : DEC : FEC = 45 : 45 : 10 (volume ratio). ) was prepared as a coin cell by introducing the mixed solution as an electrolyte. For reference, the separator used PE.

Example 2. Preparation of a lithium secondary battery using silicon coated using gamma rays

In Preparation Example 2, a lithium secondary battery was manufactured using micro silicon coated with acrylic acid using gamma rays. More specifically, the silicone coated in Preparation Example 2 was dispersed in N-methyl-2-pyrrolidone to prepare a slurry, and then cast to copper foil to prepare an electrode.

The electrode was loaded with the same amount as 2.3 mg/cm ² , and at this time, the ratio of the slurry was configured such that the ratio of micro silicon: Super-P: PAA was 8: 1: 1. And, the electrode dried in 70 ◎ oven for 12 hours was made of lithium metal as a reference electrode in a glove box under argon gas, and 1 M LiPF ₆ was dissolved in EC : DEC : FEC = 45 : 45 : 10 (volume ratio). ) was prepared as a coin cell by introducing the mixed solution as an electrolyte. For reference, the separator used PE.

Example 3. Preparation of a lithium secondary battery using a metal oxide anode coated using gamma rays

In Preparation Example 3, a lithium secondary battery was prepared using a metal oxide coated with pyrrole using gamma rays. More specifically, the metal oxide coated in Preparation Example 3 was dispersed in N-methyl-2-pyrrolidone to prepare a slurry, and then cast to aluminum foil to prepare an electrode.

The electrode was loaded with the same amount as 7.8 mg/cm ² , and at this time, the ratio of the slurry was configured such that the ratio of the metal oxide: Super-P: PVDF was 8:1:1. And, the electrode dried in 70 ◎ oven for 12 hours was made of lithium metal as a reference electrode in a glove box under argon gas, and 1 M LiPF ₆ was dissolved in EC : DEC : FEC = 45 : 45 : 10 (volume ratio). ) was prepared as a coin cell by introducing the mixed solution as an electrolyte. For reference, the separator used PE.

Example 4. Preparation of pellets using an oxide solid electrolyte using gamma rays

Pellets were prepared using the oxide solid electrolyte coated with gamma rays prepared in Preparation Example 4. The formed pellets were immediately measured for lithium ion conductivity without heat treatment.

<Comparative example>

Comparative Example 1. Preparation of a lithium secondary battery using graphite

A lithium secondary battery was prepared in the same manner as in Example 1 using graphite (LG Chem).

Comparative Example 2. Preparation of a lithium secondary battery using silicon

A lithium secondary battery was manufactured in the same manner as in Example 2 using micro silicon (Alfa aesar).

Comparative Example 3. Preparation of a lithium secondary battery using a metal oxide positive electrode

A lithium secondary battery was prepared in the same manner as in Example 3 using a metal oxide (Nickel: Cobalt: Manganese = 8: 1:1) positive electrode.

Comparative Example 4. Preparation of pellets using an oxide solid electrolyte

A pellet was prepared in the same manner as in Example 8 using an oxide solid electrolyte (LAGP).

Comparative Example 5. Coin cell fabrication

A coin cell was manufactured together with a metal oxide anode using the graphite electrode prepared in the same manner as in Example 1. More specifically, for the metal oxide positive electrode, an active material having a nickel:cobalt:manganese ratio of 6:2:2 was used, and N-methyl-2- such that the metal oxide:Super-P:PVDF had a ratio of 95:3:2. The electrode was prepared by dispersing it in pyrrolidone and casting it on aluminum foil. The loading amount of the electrode was the ^{same as 15 mg/cm 2} , and drying was performed in a vacuum oven at 60 ˚C for 12 hours. The N/P ratio, which is the capacity ratio of the positive and negative electrodes of the prepared coin cell, was fixed to be 1.1.

<Experimental example>

Experimental Example 1. Characterization of coated graphite using gamma rays

1-1. thermogravimetric analysis

A thermogravimetric analysis (TGA) method was used to determine the graft rate of the graphite coated in Preparation Example 1. In general, since graphite is sufficiently stable up to a temperature of 600° C., the weight ratio of the coated layer can be confirmed through this.

Through thermogravimetric analysis, the weight change of the graphite coated and uncoated graphite in Preparation Example 1 using gamma rays was analyzed. And, the result is shown in FIG.

FIG. 3 is a thermogravimetric analysis graph, which is a thermogravimetric analysis graph showing the change in weight of graphite coated with gamma rays and graphite not treated with gamma rays in Preparation Example 1. FIG.

Referring to FIG. 3 , general graphite began to lose weight from around 600° C., and in the case of graphite coated with PVP using gamma rays in Preparation Example 1, there was a continuous weight loss around 200 to 600° C. could check Through this, it was confirmed that about 4% by weight of the total graphite was the coated material.

1-2. Surface analysis of graphite

Surface analysis of the graphite coated in Preparation Example 1 was performed. 4 is a view showing SEM-EDS data of the graphite coated in Preparation Example 1. Referring to FIG. 4 , as shown in the previous element analysis results, it can be confirmed that the elements of N and O are evenly distributed in the shape of particles.

Through this, it was determined that the coating layer was evenly spread around the graphite particles.

Experimental Example 2. Analysis of rate characteristics of graphite coated using gamma rays

The rate characteristics were compared using the lithium secondary batteries prepared in Example 1 and Comparative Example 1. And, the result is shown in FIG.

Referring to FIG. 5 , it was confirmed that the lithium secondary battery manufactured using graphite coated with gamma rays showed higher rate characteristics than that of the graphite of Comparative Example 1. In general, graphite (Comparative Example 1) had a large capacity decrease of about 80 mAh/g at a rate of about 1C, but it was confirmed that the coated graphite (Example 1) showed a high capacity of about 180 mAh/g. . This is thought to be because the decomposition film generated in the coating process of Example 1 reacts with the electrolyte to form a new interface, and this interface is more advantageous for lithium ion transfer than the decomposition film made only of the existing carbonate.

Through this, it was found that it is possible to easily react and coat graphite, which does not easily react chemically, using the strong energy of gamma rays.

Experimental Example 3. Analysis of electrochemical properties of silicon coated using gamma rays

Comparative Example 2 and the lithium secondary battery prepared in Comparative Example 2 were used. And, the result is shown in FIG. Referring to FIG. 6 , it was confirmed that a lithium secondary battery manufactured using silicon coated with gamma rays showed better cycle characteristics than micro silicon of Comparative Example 2. In general, microsilicon (Comparative Example 2) showed a coulombic efficiency of about 73% in the first cycle, whereas it was confirmed that the coated silicon showed a coulombic efficiency of about 90%. It is considered that this is because the acrylic acid polymer having a similar shape to PAA generated in the coating process of Example 2 acts as a coating film to relieve stress due to volume expansion of the silicon electrode and to improve binding properties.

Through this, it was found that the coating using gamma rays can be effectively applied to the problem of volume expansion of micro silicon.

Experimental Example 4. Electrochemical analysis of coated metal oxide using gamma rays

Electrochemical properties were compared using the lithium secondary batteries prepared in Example 3 and Comparative Example 3. And, the result is shown in FIG.

Referring to FIG. 7 , it was confirmed that the lithium secondary battery manufactured using the metal oxide positive electrode coated with gamma rays showed better cycle characteristics than the metal oxide positive electrode of Comparative Example 3. As a result of performing 120 cycles at a speed of 1C, it was confirmed that Comparative Example 3 showed a specific capacity retention ratio of about 80%, whereas Example 3 showed a specific capacity retention ratio of about 95%. In general, when charging and discharging at high speed, the capacity decreases due to the deactivation of the metal oxide surface, but in the case of the coated metal oxide, the coating layer maintains the surface, which is judged to show a high specific capacity retention rate.

Through this, it can be confirmed that it is possible to effectively improve the cycle characteristics by coating the metal oxide anode using gamma rays.

Experimental Example 5. Lithium ion conductivity measurement using an oxide solid electrolyte using gamma rays

The lithium ion conductivity was measured using the pellets prepared in Example 4 and Comparative Example 4. And, the result is shown in FIG. Referring to FIG. 8 , it was confirmed that the lithium ion conductivity was significantly higher than that of the oxide solid electrolyte of Comparative Example 4. In general, oxide solid electrolytes have little lithium ion conductivity without heat treatment, but improved lithium ion conductivity of ^{about 4.2 X 10 -7} S/cm ^-1 without heat treatment by forming a coating film using lithium salt and acrylonitrile polymer using gamma rays was able to confirm that Through this, it was determined that a coating film could be effectively formed by using gamma rays on the oxide solid electrolyte, thereby reducing the resistance between particles.

In another embodiment of the present invention, an inorganic material layer is formed on the electrode surface by applying or immersing the electrode in an electrolyte solution containing an inorganic metal salt and then irradiating gamma rays. In this case, there is an advantage in that the properties of the layer formed on the electrode surface can be selected according to the selection of the electrolyte solution component.

Hereinafter, the present invention will be described in more detail through preferred embodiments.

Preparation Example 1-1 Preparation of gamma-irradiated electrode and coin cell

Graphite was dispersed in water to prepare a slurry, and then cast to copper foil to prepare an electrode. The loading of the electrode ^{was the same at 8 mg/cm 2} , and in this case, the ratio of the slurry was configured such that the ratio of graphite: Super-P: SBR: CMC was 93: 3: 2: 2. Then, drying was performed in an oven at 70 °C for 12 hours.

The thus-prepared electrode was placed in a vial, immersed in an electrolyte solution containing various kinds of lithium salts as shown in Table 1 below, and sealed under an argon composition. The sealed vials were treated for various times under gamma radiation at an irradiation rate of 2 kGy/hr. Specific gamma-ray treatment electrolyte conditions and time are shown in Table 1. The gamma-ray-treated graphite electrode was opened under an argon atmosphere, washed with DEC electrolyte, and dried. All treatment processes were carried out without exposure to air. In an embodiment of the present invention, it is preferable that the gamma rays have at least a level of energy capable of ionizing a metal salt such as lithium.

[Table 1]

The electrode prepared under the conditions of Table 1 was then used as a lithium metal as a reference electrode in a glove box under argon gas, and EC:DEC:FEC=45:45:10 (volume ratio) in which _{1 M LiPF 6 was dissolved.} The mixed solution was added as an electrolyte to prepare a coin cell. For reference, the separator used PE.

Preparation Example 2-1. Full-Cell Manufacturing

A full-cell was prepared by using a graphite electrode treated with gamma rays in the same electrolyte as in Example 13 of Table 1 above. More specifically, in this preparation example, a metal oxide positive electrode was used together with the graphite electrode prepared in Example 13, and an active material having a nickel: cobalt: manganese ratio of 6: 2: 2 was used as the metal oxide anode, and metal oxide: Super -P: PVDF was dispersed in N-methyl-2-pyrrolidone in a ratio of 95: 3: 2 and cast on aluminum foil to prepare an electrode. The loading amount of the electrode was the ^{same as 15 mg/cm 2} , and drying was performed in a vacuum oven at 60 ˚C for 12 hours. The N/P ratio, which is the capacity ratio of the positive electrode and the negative electrode of the prepared coin cell, was fixed to be 1.1.

Comparative Example 5. Graphite electrode not subjected to gamma-ray treatment

As a comparative example, the same full-cell as in Preparation Example 2-1 was prepared except that a graphite electrode not treated with gamma ray was used.

Experimental Example 6. Analysis of rate characteristics of graphite electrode coated using gamma rays

The rate characteristics were compared using the lithium secondary batteries prepared in Comparative Example 1 and Examples 5-13. And the result is shown in FIG. Referring to FIG. 9 , it was confirmed that the graphite electrode coated with gamma rays showed significantly higher rate characteristics than the graphite electrode of Comparative Example 1. Comparative Example 1 showed a capacity of about 80 mAh/g at 1C, whereas the treated Examples 5-13 realized a higher capacity. In particular, in the case of Example 13, a capacity of about 250 mAh/g was implemented. This is thought to be because the lithium salt LiTFSI collapses during the gamma-ray coating process and forms a LiF coating layer on the graphite surface, and the high rate characteristic of this interface is reflected in the cell performance.

In addition, it was confirmed that excellent performance was maintained even when the graphite electrode prepared in Example 14 and Comparative Example 5 was operated as a full cell together with the metal oxide anode. Referring to FIG. 10 , it can be seen that the rate-rate characteristic of Example 14 treated with gamma rays is much better than Comparative Example 5 containing a general graphite electrode, and as a result, it can be confirmed that much more capacity is realized at the same speed. In addition, it can be confirmed that the charge/discharge curve of Example 14 realizes the capacity at a lower voltage range than the charge/discharge curve of Comparative Example 5 at the same charge rate due to low ionic resistance.

Through this, it can be seen that coating using gamma rays is an excellent technique that can be applied even after being made into electrodes. In addition, it can be confirmed that the gamma-irradiation process is an effective method for forming LiF, a good interfacial component, through the decay of various lithium salts.

Therefore, the reaction solution according to an embodiment of the present invention is to contain a metal salt that decays upon irradiation with gamma rays (γ-ray) to form an inorganic material layer, LiF, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiB(Ph) ₄ , LiC ₄ BO ₈ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , _{LiAlCl 4} , LiSO ₃ CH ₃ , LiSO ₃ CF ₃ , LiSCN, LiC (CF ₃ SO ₂ ) ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , Chloroborane lithium, lower aliphatic lithium carboxylate, 4-phenyl lithium borate and one or more components selected from the group consisting of imides.

Claims (30)

contacting the secondary battery material with the reaction solution; and
Forming an organic layer or an inorganic layer on the surface of the secondary battery material by irradiating gamma rays (γ-ray) to the reaction solution in contact with the secondary battery material; It is characterized in that it comprises
In the organic material layer, a reactant formed by irradiation with gamma rays is grafted onto the surface of the material for secondary batteries,
The inorganic material layer is a method for surface treatment of a material for a secondary battery electrode, characterized in that the metal salt of the reaction solution that collapses upon irradiation with gamma rays is coated on the surface of the material for secondary battery. The method of claim 1,
In the step of forming an organic material layer on the surface of the material for secondary batteries, gamma rays (γ-ray) are irradiated to the reaction solution to generate radicals on the surface or reaction solution of the material for secondary batteries, and reactants or decomposition products present in the reaction solution A surface treatment method of a material for a secondary battery electrode, characterized in that grafting on the surface of the material for a secondary battery. According to claim 1,
The secondary battery material is, graphite, silicon-based negative electrode, metal oxide (metal oxide), metal sulfide (metal sulfide), lithium metal, sodium metal, magnesium metal, zinc metal, aluminum metal, sulfur-based composite , A method for surface treatment of a material for a secondary battery electrode, characterized in that at least one selected from the group consisting of an organic material containing a quinone group, a polymer-based solid electrolyte, a sulfide-based solid electrolyte, and an oxide-based solid electrolyte.
According to claim 1,
The material for the secondary battery is a surface treatment method of a material for a secondary battery electrode, characterized in that at least one selected from the group consisting of graphite, a silicon-based negative electrode, a metal oxide, and an oxide-based solid electrolyte .
4. The method of claim 3,
The graphite is in the form of a powder, and a method for surface treatment of a material for a secondary battery electrode, characterized in that it is artificial graphite manufactured by heat-treating natural graphite or a carbon material as a raw material.
4. The method of claim 3,
The silicon-based negative electrode, SiO _x (0≤x≤2) composition of silicon, intrinsic silicon, n-type silicon or p-type silicon, characterized in that it comprises a surface treatment method of a material for a secondary battery electrode.
4. The method of claim 3,
The silicon-based negative electrode, graphite, carbon fiber, pitch-based carbon, graphene, carbon nanotubes, activated carbon and carbon black, characterized in that the surface of the secondary battery electrode material comprising at least one conductive carbon material selected from the group consisting of processing method.
4. The method of claim 3,
The metal oxide is Li _1+a Ni _b Co _c Mn _d O ₂ (0 ≤ a ≤ 0.2, 0 ≤ b < 1, 0 ≤ c < 1, 0 ≤ d < 1, b+c+d=1) , Li _1+e [M _2-e ]O ₄ (0 ≤ e ≤ 0.15, M= at least one of Mn, Ni, Cr, Fe, Co, Cu), Li _1+f Ni _g Co _h Al _i O ₂ (0 ≤ f ≤ 0.2, 0 < g < 1, 0 < h < 1, 0 < i < 1, g+h+i=1), LiFe _1-j M _k PO ₄ (M= more than one kind of transition Metal elements, 0 ≤ j ≤ 0.5, 0 ≤ k ≤ 0.5), Li _l Ti _m O _n (0 < l < 7, 0 < m < 6, 0 < n < 15) or Li _x MO _{y on their surface} (M = Zr, Al, Sn, Nb, Ti, Ta, 0.9 ≤ x ≤ 1.2, 1 ≤ y ≤ 3.5) Surface treatment of a material for a secondary battery electrode comprising a coated material or a combination thereof Way.
4. The method of claim 3,
The oxide-based solid electrolyte is, LiO ₂ -Al ₂ O ₃ -TiO ₂ -P ₂ O ₅ , LiO ₂ -SiO ₂ -TiO ₂ -P ₂ O ₅ , LiO ₂ -La ₂ O ₃ -ZrO _2, LiO ₂ -La ₂ O ₃ -TiO ₂ , Li ₄ SiO ₄ -Li ₃ PO ₄ , and LiO ₂ -Al ₂ O ₃ -Ge ₂ O ₃ -P ₂ O ₅ Secondary, characterized in that at least one selected from the group consisting of A method for surface treatment of materials for battery electrodes.
According to claim 1,
The secondary battery material dispersed in the reaction solution is a surface treatment method of a secondary battery electrode material, characterized in that the powder has an average particle diameter in the range of 10 nm to 50 ㎛.
According to claim 1,
The gamma-ray is a surface treatment method of a material for a secondary battery electrode, characterized in that for irradiating an irradiation dose in the range of 1 to 1000 kGy at an irradiation dose rate in the range of 0.1 to 50 kGy / hr.
According to claim 1,
The reaction solution comprises at least one solvent selected from the group consisting of water, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, alcohols, esters, ketones, ethers, carbonates, amides, nitriles and sulfones. A method for surface treatment of electrode materials.
According to claim 1,
The reaction solution is N-vinyl-2 pyrrolidone, vinyl olefin monomer, vinyl aromatic monomer, vinyl halogen monomer, vinyl alcohol monomer, ether monomer, acrylate monomer, acrylic acid monomer, amide monomer , a method for surface treatment of a material for a secondary battery electrode, characterized in that it may include one or more monomers selected from the group consisting of nitrile-based monomers and sulfone-based monomers.
materials for secondary batteries; and
A polymer-based organic material layer surrounding the surface of the secondary battery material; A secondary battery electrode material manufactured by the surface treatment method of the secondary battery electrode material according to any one of claims 1 to 12, comprising a. 15. The method of claim 14,
The thickness of the organic material layer is a secondary battery electrode material, characterized in that the average range of 0.1 nm to 10 μm
A secondary battery electrode comprising the material for a secondary battery according to claim 14 .
A lithium secondary battery comprising the secondary battery electrode according to claim 16 .
immersing the electrode for a secondary battery in a reaction solution or applying the reaction solution to the electrode for a secondary battery; and
Forming an organic material layer on the surface of the electrode for a secondary battery by irradiating a reaction solution containing the electrode for a secondary battery or a secondary battery electrode coated with the reaction solution with gamma rays (γ-ray); includes,
In the step of forming an organic material layer on the surface of the electrode for a secondary battery, gamma rays (γ-ray) are irradiated to the reaction solution to generate radicals on the surface of the electrode for a secondary battery or the reaction solution, and reactants or decomposition products present in the reaction solution A surface treatment method for a secondary battery electrode, characterized in that grafting on the surface of the secondary battery electrode.
19. The method of claim 18,
The secondary battery electrode, graphite, silicon-based negative electrode, metal oxide (metal oxide), metal sulfide (metal sulfide), lithium metal, sodium metal, magnesium metal, zinc metal, aluminum metal, sulfur-based composite , An organic material containing a quinone group, a polymer-based solid electrolyte, a sulfide-based solid electrolyte, and an oxide-based solid electrolyte surface treatment method for a secondary battery electrode comprising at least one selected from the group consisting of.
19. The method of claim 18,
The gamma ray is a surface treatment method of an electrode for a secondary battery, characterized in that irradiating an irradiation dose in the range of 1 to 1000 kGy at an irradiation dose rate in the range of 0.1 to 50 kGy / hr.
19. The method of claim 18,
The reaction solution is water, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, alcohols, esters, ketones, ethers, carbonates, amides, nitriles and secondary batteries, characterized in that it contains one or more solvents selected from the group consisting of sulfone series A method for surface treatment of electrodes.
19. The method of claim 18,
The reaction solution is N-vinyl-2 pyrrolidone, vinyl olefin monomer, vinyl aromatic monomer, vinyl halogen monomer, vinyl alcohol monomer, ether monomer, acrylate monomer, acrylic acid monomer, amide monomer , a method for surface treatment of an electrode for a secondary battery, characterized in that it may include one or more monomers selected from the group consisting of nitrile-based monomers and sulfone-based monomers.
electrodes for secondary batteries; and
A polymer-based organic material layer surrounding the surface of the secondary battery electrode; A secondary battery electrode manufactured by the surface treatment method of the secondary battery electrode according to any one of claims 17 to 21, comprising a.
24. The method of claim 23,
The thickness of the organic material layer is a secondary battery electrode material, characterized in that the average range of 0.1 nm to 10 μm.
A lithium secondary battery comprising the secondary battery electrode according to claim 23.
immersing an electrode for a secondary battery in a reaction solution or contacting a reaction solution containing a metal salt with an electrode for a secondary battery;
irradiating the reaction solution with gamma rays (γ-ray); and
and forming an inorganic material layer obtained from the metal salt that decays according to the irradiated gamma rays (γ-ray) on the surface of the secondary battery electrode. 27. The method of claim 26,
The reaction solution is LiF, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiB(Ph) ₄ , LiC ₄ BO ₈ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , _{LiAlCl 4} , LiSO ₃ CH ₃ , LiSO ₃ CF ₃ , LiSCN, LiC(CF ₃ SO ₂ ) ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(SO) ₂ F) ₂ , A method for manufacturing a secondary battery electrode comprising at least one component selected from the group consisting of lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenyl borate, and imide. 27. The method of claim 26,
The secondary battery electrode manufacturing method, characterized in that the energy of the gamma ray is at a level capable of ionizing the metal salt. As a secondary battery electrode,
The secondary battery electrode, characterized in that the inorganic material layer containing the metal salt collapsed upon irradiation with gamma rays (γ-ray) is formed on the surface of the secondary battery electrode. A secondary battery comprising the secondary battery electrode according to claim 28 .

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