KR20230109312A - Composite material - Google Patents

Abstract

The present application provides a composite material, its use as a secondary battery electrode (eg, negative electrode), an electrode assembly and secondary battery comprising the composite material, and a method for manufacturing the composite material. In the present application, as an electrode to which a silicon material is applied, it is possible to provide an electrode having excellent lifespan characteristics that exhibits high capacity and stably maintains capacity even during repeated charging and discharging.

Description

Composites {COMPOSITE MATERIAL}

This application is about composites and their uses.

Secondary batteries such as lithium ion secondary batteries can be manufactured to be small and lightweight, have high energy density, and can be repeatedly charged and discharged, and thus are used in various ways.

An anode plays an important role in the lifespan and capacity of a secondary battery. Currently, graphite is widely used as a material for an anode, and silicon materials having a high theoretical capacity are also being studied.

Although silicon material has a high theoretical capacity, it repeats large expansion and contraction during charging and discharging, and as a result, the active material deteriorates over time, the electrode plate structure is destroyed, and the conductive path in the electrode is damaged. there is.

The present application relates to a composite material, its use as a secondary battery electrode (eg, negative electrode), an electrode assembly and a secondary battery comprising the composite material, and a method for manufacturing the composite material.

One object of the present application is to provide an electrode with excellent lifespan characteristics in which a silicon material is applied, exhibits high capacity, and maintains capacity stably even during repeated charging and discharging.

Among the physical properties mentioned in this specification, if the measurement temperature affects the corresponding physical properties, unless otherwise specified, the physical properties are measured at room temperature. The term room temperature is a natural temperature that is not heated or cooled, and may mean, for example, any temperature in the range of about 10 °C to 30 °C, about 23 °C, or about 25 °C. In addition, unless otherwise specified in the present specification, the unit of temperature is °C.

Among the physical properties mentioned in this specification, when the measured pressure affects the result, the corresponding physical property is a physical property measured at normal pressure unless otherwise specified. The term normal pressure refers to normal pressure of about 700 to 800 mmHg as natural pressure that is not pressurized and reduced.

Among the physical properties mentioned in this specification, when measured humidity affects the result, unless otherwise specified, the corresponding physical property is a physical property measured under humidity that is not particularly controlled at room temperature and normal pressure.

This application is for composite materials.

The composite material of the present application may include at least a metal foam and silicon formed on a surface and/or an inner surface of the metal foam. In the composite material, as long as the silicon is present at least on the surface of the metal foam, it may also be present on the inner surface of the metal foam, for example, on the inner surface of pores formed in the metal foam.

In this specification, the term metal foam or metal skeleton refers to a porous structure containing metal as a main component. In the above, the metal as the main component means that the ratio of the metal based on the total weight of the metal foam or metal skeleton is 55% by weight or more, 60% by weight or more, 65% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more It means the case of more than 85% by weight, more than 90% by weight or more than 95% by weight. The upper limit of the ratio of the metal included as the main component is not particularly limited, and may be, for example, 100% by weight, 99% by weight, or 98% by weight. In addition, in the above, the metal includes a single metal as well as an alloy of two or more types of metals.

As used herein, the term porosity may refer to a case in which the porosity is at least 10%, 15%, 20%, 25%, 30%, 35%, or 40%. The upper limit of the porosity is not particularly limited, but is, for example, about 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less. It may be on the order of less than or less than 50%. A method for obtaining the porosity is not particularly limited. For example, in the case of a metal form, a known method of confirming the porosity through the density of the metal form may be applied.

The composite material of the present application may exhibit excellent performance as an electrode (eg, a negative electrode) for a secondary battery, for example.

For example, the electrode exhibits high capacity by applying the silicon material, has excellent life characteristics in which capacity is stably maintained even during repeated charging and discharging through the application of the silicon material to a metal form, and high-speed charging Characteristics can also be excellent.

In the present application, the metal form may be controlled in order to efficiently achieve the composite of the metal form and the silicon component of the composite material. For example, the material, porosity and/or thickness of the metal foam applied to the composite may be controlled.

In one example, the metal foam may be a metal alloy foam. The term metal alloy form means a metal form containing two or more types of metals.

In one example, the metal form may be a metal alloy form including germanium and a metal different from the germanium.

The germanium present in the metal alloy form lowers the nucleation barrier to silicon so that silicon is uniformly formed in the metal alloy form, and as a result, a composite material having excellent desired effects can be formed. Such a composite material can be used as an electrode for a secondary battery, for example, a negative electrode for a secondary battery.

There is no particular limitation on the type of metal other than the germanium included in the metal alloy form. For example, as the other metal, a metal commonly used as a current collector of a negative electrode for a secondary battery may be applied. These metals may be any one or two or more selected from the group consisting of stainless steel, aluminum, nickel, titanium, copper, silver and cadmium, but are not limited thereto.

The metal alloy form may include 0.1 wt % to 20 wt % of the germanium. Under this ratio, uniform deposition or plating of silicon is possible, and at the same time, conductivity for the composite material to function as an electrode can be secured. In another example, the ratio is 0.5% by weight or more, 1% by weight or more, 2% by weight or more, 3% by weight or more, 4% by weight or more, 5% by weight or more, 6% by weight or more, 7% by weight or more, 8% by weight or more. or about 9 wt% or more, 19 wt% or less, 18 wt% or less, 17 wt% or less, 16 wt% or less, 15 wt% or less, 14 wt% or less, 13 wt% or less, 12 wt% or less, 11 wt% or less % or less or 10% by weight or less.

In the metal alloy form, a metal other than the germanium may be included in an amount of 500 to 3000 parts by weight based on 100 parts by weight of the germanium. Under this ratio, uniform deposition or plating of silicon is possible, and at the same time, conductivity for the composite material to function as an electrode can be secured. In another example, the ratio is 550 parts by weight or more, 600 parts by weight or more, 650 parts by weight or more, 700 parts by weight or more, 750 parts by weight or more, 800 parts by weight or more, 850 parts by weight or more, 900 parts by weight or more, 950 parts by weight or more. Or about 1000 parts by weight or more, 2500 parts by weight or less, 2000 parts by weight or less, 1500 parts by weight or less, 1400 parts by weight or less, 1300 parts by weight or less, 1200 parts by weight or less, 1100 parts by weight or less, or 1000 parts by weight or less. .

In the metal alloy form, the germanium and the other metals, that is, the total amount of one or more metals selected from the group consisting of stainless steel, aluminum, nickel, titanium, copper, silver and cadmium is 55% by weight or more, 60% by weight or more, 65% by weight % or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more, or 100% or less, 99% or less, or 98% or less by weight. there is.

That is, the metal alloy form may include a metal other than the germanium as a main component. Through this, uniform deposition or plating of silicon is possible, and at the same time, conductivity for the composite material to function as an electrode can be secured.

In one example, the metal alloy foam may have a porosity of about 95% or less, 90% or less, 85% or less, 80% or less, or 75% or less. In another example, the porosity is 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, It may be 65% or more or 70% or more. For the porosity, a known method of confirming the porosity through the density of the metal alloy foam may be applied. Within the above range, it is possible to achieve a suitable composite with silicon, and to effectively exhibit the function of the composite material as a negative electrode for a secondary battery.

In one example, the metal alloy foam may be in the form of a film. The thickness of the film (metal alloy form) is, for example, about 1,000 μm or less, 950 μm or less, 900 μm or less, 850 μm or less, 800 μm or less, about 750 μm or less, about 700 μm or less, about 650 μm or less , about 600 μm or less, about 550 μm or less, about 500 μm or less, about 450 μm or less, about 400 μm or less, about 350 μm or less, about 300 μm or less, about 250 μm or less, or about 200 μm or less. Within the above range, it is possible to achieve a suitable composite with the silicon component, and to effectively perform the function of the composite material as an electrode for a secondary battery. The lower limit of the thickness of the metal alloy foam is not particularly limited, and for example, about 0.5 μm or more, about 1 μm or more, about 2 μm or more, about 3 μm or more, about 4 μm or more, about 5 μm or more, about 6 μm or more, about 7 μm or more, about 8 μm or more, about 9 μm or more, about 10 μm or more, about 50 μm or more, about 100 μm or more, about 150 μm or more, about 200 μm or more, about 250 μm or more, about 300 μm or more, about It may be about 350 μm or more or about 400 μm or more.

In the present specification, the thickness may be a minimum thickness, a maximum thickness, or an average thickness of the target when the thickness of the target is not constant.

In addition, the porosity and / or thickness of the metal alloy foam may be the porosity and / or thickness of the metal alloy foam when the silicon component is not present, or the porosity and / or thickness when the silicon component is present. .

In the composite material of the present application, the silicon component is deposited on the surface of the metal alloy form and / or the surface of the internal pores to form a layer, and at this time, since the thickness of the layer is relatively thin, the silicon component according to the presence or absence of the silicon component Variations in porosity and/or thickness are not significant.

These metal alloy forms are known in various ways, and methods for manufacturing metal alloy forms are also known in various ways. In the present application, such a known metal alloy form or a metal alloy form manufactured by the known method may be applied.

As a method for producing a metal alloy foam, a method of sintering a composite material of a pore former such as salt and a metal, a method of coating a metal on a support such as polymer foam and sintering in the state, a slurry method, and the like are known. . In addition, the metal alloy foam may be applied to Korean application Nos. 2017-0086014, 2017-0040971, 2017-0040972, 2016-0162154, 2016-0162153 or 2016-0162152, which are prior applications of the present applicant. It can also be prepared according to the disclosed method.

The silicon component complexed with the above metal alloy form may be present on at least the surface of the metal alloy form. In one example, the silicon component may be present on the surface and inside (eg, pores of the metal alloy form) of the metal alloy form. The silicon component may be deposited on the surface and/or inside (surface of internal pores) of the metal alloy form to form a layer.

As described later, the silicon component may be formed by depositing or plating silicon on the metal alloy form using electrolytic plating, electroless plating, or other electrochemical plating methods.

The amount of the silicon component included in the composite is not particularly limited, and an appropriate amount may be introduced in consideration of the capacity or performance of the desired electrode.

For example, the composite material may include the silicon component in an amount of about 0.1 to 10 mg/cm ² . The amount of the silicon component is a value obtained by dividing the amount of the silicon component present in the composite material by the surface area of the composite material. In this case, the surface of the composite material is a main surface of the metal alloy form, and may be, for example, upper and/or lower surfaces of the metal alloy form.

The composite material as described above can be applied to various uses, for example, it can be applied as an electrode for a secondary battery, more specifically, as a negative electrode for a secondary battery.

Therefore, the present application is a metal alloy form including a metal alloy including the germanium and a metal different from the germanium; And it may be for a negative electrode for a secondary battery containing silicon present on the surface of the metal alloy form. The specific details of the metal alloy foam and silicon applied at this time are the same as those described in the composite material.

The present application also relates to an electrode assembly for a secondary battery including the composite material as an anode. Such an electrode assembly may include, for example, an anode; A negative electrode and a separator may be included between the positive electrode and the negative electrode, and the composite material described above may be applied as the negative electrode.

In addition, the present application relates to a secondary battery including the composite material as an anode or including the electrode assembly.

There is no particular limitation on the type of other components such as a cathode, a separator, or an electrolyte applied in the electrode assembly and the secondary battery, and known materials for secondary batteries may be applied without limitation.

The present application also relates to a method of manufacturing such a composite or negative electrode.

The manufacturing method may include, for example, forming silicon on or inside the metal alloy form, that is, the metal alloy form including germanium and a metal different from the germanium.

There is no particular limitation on the method of manufacturing the metal alloy form applied to the manufacturing method, and the metal alloy form can be manufactured by applying a known method of manufacturing a metal form using germanium and another metal as a material. For example, for the metal alloy foam, a method of sintering a composite material of a pore former such as salt and a metal, a method of coating a metal on a support such as polymer foam and sintering in that state, or applying a slurry method or the like , Korean application Nos. 2017-0086014, 2017-0040971, 2017-0040972, 2016-0162154, 2016-0162153 or 2016-0162152, which are prior applications of the present applicant It can be.

For example, the metal alloy form may be prepared by sintering a precursor molded from a slurry containing the germanium powder and the powder of another metal. That is, the method of manufacturing the metal alloy form may include obtaining a porous metal sintered body by sintering a metal structure (precursor) including, as metal components, the germanium powder and the other metal powder.

In the above, the term metal structure or precursor refers to a structure before a process performed to form a metal alloy form, such as sintering, that is, a structure before forming a metal alloy form. In addition, even if the metal structure is called a porous metal structure, it does not necessarily need to be porous per se, and if it can form a metal alloy form, which is a porous metal structure, it can be called a porous metal structure for convenience.

The metal component included in the metal structure may include germanium powder and other metal powder. These ratios can be adjusted so that the ratio of each metal in the above-described metal alloy form can be satisfied.

The metal powder may have an average particle diameter ranging from about 0.01 μm to about 200 μm. In another example, the average particle diameter is about 0.05 μm or more, about 0.1 μm or more, about 0.2 μm or more, about 0.3 μm or more, about 1 μm or more, about 10 μm or more, about 20 μm or more, about 30 μm or more, about 40 μm or more, about 50 μm or more. μm or greater or about 55 μm or greater. In another example, the average particle diameter is about 150 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, 1 μm or less, or 0.5 μm or less. can The average particle diameter is a so-called median particle diameter (D50 particle diameter) measured by the method described in the Examples below.

In order to secure an appropriate effect, the ratio of the average particle diameters of the metal powders may be controlled. For example, the ratio (M/Ge) of the average particle diameter (Ge) of the germanium powder and the average particle diameter (M) of the other metal powder may be in the range of 100 to 500. In another example, the ratio (M/Ge) may be 120 or more, 140 or more, 160 or more, 180 or more, or 200 or more, or 450 or less, 400 or less, 350 or less, 300 or less, 250 or less, or 200 or less. Under this ratio, it is possible to obtain a metal alloy form that exhibits desired effects appropriately.

In the above, the powder of a metal other than germanium may have an average particle diameter in the range of about 20 μm to about 200 μm. In another example, the average particle diameter may be about 25 μm or more, about 30 μm or more, about 35 μm or more, about 40 μm or more, about 45 μm or more, about 50 μm or more, about 55 μm or more, or about 60 μm or more. In another example, the average particle diameter may be about 150 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less.

In the present application, a metal structure including a metal component as described above may be formed using a slurry (hereinafter, referred to as slurry A) including at least the metal component, a dispersant, and a binder in one example.

The ratio of the metal component in the slurry A is not particularly limited, and may be selected in consideration of a desired viscosity or process efficiency. In one example, the ratio of the metal component in the slurry A may be about 0.5% to 95% by weight, but is not limited thereto. In another example, the ratio is about 1% or more, about 1.5% or more, about 2% or more, about 2.5% or more, about 3% or more, about 5% or more, 10% or more, 15% or more, 20% or more, 25% ≥ 30%, ≥ 35%, ≥ 40%, ≥ 45%, ≥ 50%, ≥ 55%, ≥ 60%, ≥ 65%, ≥ 70%, ≥ 75%, ≥ 80%, or about 90% or less, about 85% or less, about 80% or less, about 75% or less, about 70% or less, about 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less , 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, or 5% or less, but is not limited thereto.

As the dispersant, for example, alcohol may be applied. As alcohol, methanol, ethanol, propanol, butanol, pentanol, octanol, ethylene glycol, propylene glycol, pentanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, glycerol, texanol ( texanol) or C1-C20 monohydric alcohol such as terpineol, or C1-C20 dihydric alcohol or higher polyhydric alcohol, such as ethylene glycol, propylene glycol, hexanediol, octanediol or pentanediol, etc. This may be used, but the type is not limited to the above.

Slurry A may further include a binder. The type of binder is not particularly limited and may be appropriately selected depending on the type of metal component or dispersant used in preparing slurry A. For example, as the binder, an alkyl cellulose having an alkyl group having 1 to 8 carbon atoms such as methyl cellulose or ethyl cellulose, a polyalkylene carbonate having an alkylene unit having 1 to 8 carbon atoms such as polypropylene carbonate or polyethylene carbonate, or Polyvinyl alcohol-based binders such as polyvinyl alcohol or polyvinyl acetate may be exemplified, but are not limited thereto.

The ratio of each component in the slurry A is not particularly limited. This ratio may be adjusted in consideration of process efficiency such as coatability or moldability during the process using slurry A.

For example, in the slurry A, the binder may be included in an amount of about 1 to 500 parts by weight based on 100 parts by weight of the metal component. In another example, the ratio is about 2 parts by weight or more, about 3 parts by weight or more, about 4 parts by weight or more, about 5 parts by weight or more, about 6 parts by weight or more, about 7 parts by weight or more, about 8 parts by weight or more, about 9 parts by weight or more. At least about 10 parts by weight, at least about 20 parts by weight, at least about 30 parts by weight, at least about 40 parts by weight, at least about 50 parts by weight, at least about 60 parts by weight, at least about 70 parts by weight, about 80 parts by weight Or more, about 90 parts by weight or more or about 100 parts by weight or more, about 450 parts by weight or less, about 400 parts by weight or less, about 350 parts by weight or less. It may be about 300 parts by weight or less, about 250 parts by weight or less, about 200 parts by weight or less, about 150 parts by weight or less, or about 100 parts by weight or less.

The dispersant in the slurry A may be included in an amount of about 10 to 2,000 parts by weight based on 100 parts by weight of the binder. In another example, the ratio is about 20 parts by weight or more, about 30 parts by weight or more, about 40 parts by weight or more, about 50 parts by weight or more, about 60 parts by weight or more, about 70 parts by weight or more, about 80 parts by weight or more, about 90 parts by weight or more. About 100 parts by weight or more, about 110 parts by weight or more, about 120 parts by weight or more, about 130 parts by weight or more, about 140 parts by weight or more, about 150 parts by weight or more, about 160 parts by weight or more, about 170 parts by weight or more, about 180 parts by weight or more, about 190 parts by weight or more, about 200 parts by weight or more, about 300 parts by weight or more, about 400 parts by weight or more, about 500 parts by weight or more, about 550 parts by weight or more, about 600 parts by weight or more; about 650 parts by weight or more, about 1,800 parts by weight or less, about 1,600 parts by weight or less, about 1,400 parts by weight or less, about 1,200 parts by weight or less, about 1,000 parts by weight or less, about 800 parts by weight or less, about 600 parts by weight or less, About 400 parts by weight or less, about 300 parts by weight or less, about 250 parts by weight or less or about 200 parts by weight or less, about 150 parts by weight or less or about 120 parts by weight or less.

By controlling the ratio of the dispersant or the binder in the slurry A as described above, it is possible to effectively form a metal alloy foam having desired characteristics.

Slurry A may further contain a solvent, if necessary. As the solvent, an appropriate solvent may be used in consideration of the solubility of the components of the slurry A, for example, the metal component or the binder. For example, a solvent having a dielectric constant within a range of about 10 to 120 can be used. In other examples, the dielectric constant may be about 20 or more, about 30 or more, about 40 or more, about 50 or more, about 60 or more, or about 70 or more, or about 110 or less, about 100 or less, or about 90 or less. Examples of such a solvent include alcohols having 1 to 8 carbon atoms such as water, ethanol, butanol, or methanol, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), or N-methylpyrrolidinone (NMP), but are not limited thereto. no.

When the solvent is applied, it may be present in the slurry A in an amount of about 50 to 400 parts by weight based on 100 parts by weight of the binder, but is not limited thereto.

The slurry A may contain additionally necessary known additives in addition to the above-mentioned components. However, in order to effectively obtain desired pore characteristics, the slurry may not contain a so-called foaming agent. The term blowing agent includes components commonly referred to as blowing agents in the art as well as components capable of exhibiting a foaming effect in relation to other components in the slurry. Therefore, the foaming process may not proceed during the process of manufacturing the metal alloy foam in the present application.

A method of forming the metal structure (precursor) using the slurry A is not particularly limited. In the field of manufacturing metal alloy foam, various methods for forming a metal structure are known, and all of these methods may be applied in the present application. For example, the metal structure may be formed by holding the slurry A in an appropriate template or by coating the slurry A in an appropriate manner.

The shape of such a metal structure is determined according to the desired metal alloy form and is not particularly limited. In one example, the metal structure may be in the form of a film or sheet. For example, when the structure is in the form of a film or sheet, its thickness may be adjusted in consideration of the desired thickness of the metal alloy form. Metal alloy foam generally has brittle properties due to its porous structural characteristics, so it is difficult to manufacture it in the form of a film or sheet, especially in the form of a thin film or sheet, and there is a problem that it is easily broken even when manufactured. However, according to the method of the present application, it is possible to form a metal alloy foam having a thin thickness, uniform pores formed therein, and excellent mechanical properties.

In another example of the present application, a metal structure (precursor) including the metal component may be formed by using a slurry (hereinafter, referred to as slurry B) of the metal component, an aqueous solvent, an organic solvent, and a surfactant. . Unlike slurry A, slurry B may be a slurry containing a foaming component.

The type of the metal component contained in the slurry B or the ratio of the metal component in the slurry is the same as that of the slurry A.

The slurry B contains a metal powder (the metal component), an aqueous solvent, an organic solvent, and a surfactant. When the ratio and type of the aqueous solvent, organic solvent, and surfactant are adjusted in the slurry, a fine emulsion is formed in the metal alloy foam precursor, and the foaming process may proceed while the emulsion is vaporized under appropriate conditions. For example, due to the difference in vapor pressure between the organic solvent and the aqueous solvent, a component having a higher vapor pressure is vaporized during the foaming process, thereby controlling the porosity of the metal alloy foam.

As the aqueous solvent in the above, water or other polar solvents may be applied, and typically water may be applied. The aqueous solvent may be included in an amount of 10 to 100 parts by weight based on 100 parts by weight of the metal powder in the slurry. In other examples, the ratio of the aqueous solvent is about 15 parts by weight or more, about 20 parts by weight or more, about 25 parts by weight or more, about 30 parts by weight or more, about 35 parts by weight or more, about 40 parts by weight or more, about 45 parts by weight or more. , About 50 parts by weight or more, about 55 parts by weight or more, or about 60 parts by weight or more, about 95 parts by weight or less, about 90 parts by weight or less, about 85 parts by weight or less, about 80 parts by weight or less, about 75 parts by weight or less, or It may be about 70 parts by weight or less.

As the organic solvent, an appropriate kind may be selected without particular limitation. As such an organic solvent, a hydrocarbon-based organic solvent can be applied, for example. As the hydrocarbon-based organic solvent, an organic solvent having 4 to 12 carbon atoms may be applied, and specific examples include n-pentane, neopentane, hexane, isohexane, cyclohexane, heptane, isoheptane, octane, toluene, or benzene. can be applied The organic solvent may be included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the metal powder in the slurry. In other examples, the ratio of the organic solvent is about 0.05 parts by weight or more, about 0.1 parts by weight or more, about 0.15 parts by weight or more, about 0.2 parts by weight or more, about 0.25 parts by weight or more, about 0.3 parts by weight or more, about 0.35 parts by weight or more. , about 0.4 parts by weight or more, about 0.45 parts by weight or more, about 0.5 parts by weight or more, about 0.55 parts by weight or more, about 0.6 parts by weight or more, about 0.65 parts by weight or more, about 0.7 parts by weight or more, about 0.75 parts by weight or more, 0.8 About 0.85 parts by weight or more, about 0.9 parts by weight or more, about 0.95 parts by weight or more, about 1 part by weight or more, about 1.05 parts by weight or more, about 1.1 parts by weight or more, about 1.15 parts by weight or more, 1.2 parts by weight More than 1.25 parts by weight, about 1.3 parts by weight or more, about 1.35 parts by weight or more, about 1.4 parts by weight or more, or about 1.45 parts by weight or more, about 9 parts by weight or less, about 8 parts by weight or less, 7 parts by weight or less It may be about 6 parts by weight or less, about 5 parts by weight or less, about 4 parts by weight or less, about 3 parts by weight or less, or about 2 parts by weight or less.

A surfactant may be included to form an appropriate microemulsion in the metal alloy foam precursor and/or to properly control the vaporization described above.

As the surfactant in the present application, any one selected from the group consisting of amphoteric surfactants, nonionic surfactants and anionic surfactants or a mixture of two or more of the above may be applied. In some cases, even when any one type of surfactant among amphoteric surfactants, nonionic surfactants, and anionic surfactants is used, a mixture of two or more surfactants having different structures within one type may be applied.

Among the above surfactants, an appropriate type for forming a desired microemulsion may be selected, and the type of aqueous solvent and organic solvent applied in this process may be considered.

As is well known, anionic surfactants are surfactants in which a moiety exhibiting surface activity is an anion, and examples of anionic surfactants include carboxylate compounds, sulfate compounds, and isethionate Compound, sulfosuccinate compound, taurate compound and/or glutamate compound may be applied, but is not limited thereto.

Nonionic surfactants, as is known, are surfactants that do not dissociate into ions, and such surfactants include, for example, alkyl polyglucoside surfactants, fatty acid alkanol amide surfactants, or amine oxide-based surfactants and higher alcohols. Surfactants of a type in which ethylene oxide is added to oil and a type in which ethylene oxide is added to oil may be used.

An amphoteric surfactant is a surfactant having both anionic and cationic moieties, and such surfactants include betaines such as cocamidopropyl betaine, lauramidopropyl betaine, cocobetaine, or lauryl betaine. Phosphorus, etc., or sultaine type, for example, lauryl hydroxysulfane, lauramidopropyl sultaine, cocamidopropyl hydroxysultaine or coco sultaine may be applied, but is not limited thereto.

As the surfactant, any one type of surfactant among the anionic, nonionic or amphoteric surfactants of the above-mentioned chemical formulas may be used alone or two or more types of surfactants may be used in combination.

The surfactant may be included in an amount of 1 to 10 parts by weight based on 100 parts by weight of the metal powder in the slurry. In another example, the ratio is about 1.5 parts by weight or more, about 2 parts by weight or more, about 2.5 parts by weight or more, about 3 parts by weight or more, about 3.5 parts by weight or more, about 4 parts by weight or more, or about 4.5 parts by weight or more, About 9.5 parts by weight or less, about 9 parts by weight or less, about 8.5 parts by weight or less, about 8 parts by weight or less, about 7.5 parts by weight or less, about 7 parts by weight or less, about 6.5 parts by weight or less, about 6 parts by weight or less, or 5.5 parts by weight or less It may be less or less.

The slurry B may also further contain necessary components in addition to the above components. For example, the slurry may further include a binder.

The binder is not particularly limited, and may be appropriately selected depending on the type of, for example, a water-soluble binder, a metal powder, an aqueous solvent, an organic solvent, and/or a surfactant applied in preparing the slurry. For example, as the binder, the same type of material as described as the binder in the first slurry may be applied.

The binder may be included in an amount of 1 to 100 parts by weight based on 100 parts by weight of the metal powder in the slurry. In other examples, the ratio is about 2 parts by weight or more, about 3 parts by weight or more, about 4 parts by weight or more, about 5 parts by weight or more, about 6 parts by weight or more, about 7 parts by weight or more, about 8 parts by weight or more, about 9 parts by weight or more. About 10 parts by weight or more, About 90 parts by weight or less, About 80 parts by weight or less, About 70 parts by weight or less, About 60 parts by weight or less, About 50 parts by weight or less, About 40 parts by weight or less, About 30 parts by weight It may be about 20 parts by weight or less, or about 15 parts by weight or less. Under this ratio, a metal alloy foam having desired porosity characteristics can be effectively manufactured.

In order to impart plasticity to the metal alloy form or its precursor, slurry B may further include a plasticizer. As the plasticizer, an appropriate type capable of imparting plasticity to the above-described slurry system or metal alloy form may be selected, and for example, polyhydric alcohol, fat, ether compound or ester compound may be applied, but is limited thereto It is not.

When included, the plasticizer may be included in a ratio of 0.5 to 10 parts by weight based on 100 parts by weight of the metal powder in the slurry. In another example, the ratio is about 1 part by weight or more, about 1.5 parts by weight or more, about 2 parts by weight or more, about 2.5 parts by weight or more, or about 3 parts by weight or more, about 9 parts by weight or less, about 8 parts by weight or less, about 7 parts by weight or less. It may be about 6 parts by weight or less, about 5 parts by weight or less, or about 4 parts by weight or less. Under this ratio, a metal alloy foam having desired porosity characteristics can be effectively manufactured.

Slurry B may also contain known additives required in addition to the above-mentioned components.

The method of forming the metal alloy foam precursor using the slurry B is not particularly limited, and is the same as the case of slurry A.

A porous metal sintered body may be formed by sintering the metal structure formed in the above manner. In this case, a method of performing sintering for producing the metal alloy form is not particularly limited, and a known sintering method may be applied. That is, the sintering may be performed by applying an appropriate amount of heat to the metal structure in an appropriate manner.

In the case of sintering the metal structure by applying heat, the applied heat is not particularly limited. That is, heat application conditions may be appropriately adjusted in consideration of the properties of the metal used or the desired mechanical strength.

In one example, the sintering may be performed under an atmosphere of hydrogen gas, nitrogen gas, and/or an inert gas (such as argon gas).

In particular, in the above manner, sintering may be performed under a predetermined oxygen partial pressure. For example, the sintering may be performed under an oxygen partial pressure of 10 ⁻¹⁹ atm to 10 ⁻¹⁵ atm. In another example, the oxygen partial pressure is 5×10 ^-19 atm or higher, 10 ^-18 atm or higher, 1.5×10 ^{-18 atm or higher, 2×10 -18 atm} or higher, or 2.24×10 ^-18 atm or higher, or 5×10 -18 atm ^{or higher.} It may be about ¹⁶ atm or less, 1.58×10 ^-16 atm or less, 10 ^-17 atm or less, 5×10 ^-18 atm or less, or 3×10 ^-18 atm or less. By controlling the oxygen partial pressure as described above, it is possible to properly burn organic matter in the precursor and at the same time minimize or suppress oxidation of metal components.

There is no particular limitation on the method of controlling the oxygen partial pressure during sintering as described above.

In one example, the sintering may be performed at a temperature within the range of about 700 °C to 1,100 °C. In another example, the sintering temperature may be about 750 ° C or higher, 800 ° C or higher, 850 ° C or higher, or 900 ° C or higher, or 1,050 ° C or lower, 1,000 ° C or lower, 950 ° C or lower, or 900 ° C or lower.

At the above sintering temperature, organic materials in the precursor are appropriately burned while at the same time, oxidation of metal components can be minimized or suppressed.

The sintering time can also be appropriately adjusted, and sintering can be performed for a time within a range of about 30 minutes to 600 minutes, for example.

In the case of the metal precursor formed from the slurry B, a foaming process may be performed before the sintering process. The foaming process is applied in the case of a precursor formed from slurry B or formed using slurries A and B together, and may not be applied when only slurry A is used. The foaming process may proceed, for example, in a manner of vaporizing the emulsion in a state in which a desired fine emulsion is formed in the precursor. For example, the foaming process may be performed by maintaining the metal alloy foam precursor at a temperature within a range of about 20° C. to 100° C. for an appropriate time. Under these conditions, the foaming process may proceed while the fine emulsion is vaporized due to the difference in vapor pressure between the aqueous solvent and the organic solvent. The foaming process time is determined according to the purpose and is not particularly limited. For example, it may be performed for a time within a range of about 1 minute to 10 hours, but is not limited thereto.

A metal alloy form can be manufactured by forming a sintered body in the above manner and, if necessary, subjecting it to appropriate post-treatment (eg, washing or drying). Subsequently, silicon may be introduced into the surface and/or inside (surface of internal pores) of the metal alloy form.

The method of introducing silicon is not particularly limited, and may be performed by a known electrolytic plating, electroless plating, or other electrochemical plating method.

That is, the silicon may be introduced by being deposited on the surface and/or inside (surface of internal pores) of the metal alloy form by a plating method.

The plating method is not particularly limited, and a known plating method may be applied. For example, a method of depositing silicon by applying the metal alloy foam as a working electrode in a solution in which a silicon precursor such as silicon chloride (SiCl ₄ ) is present may be used.

The plating conditions are not particularly limited and can be controlled so that a desired amount of silicon can be introduced.

The present application provides a composite material, its use as a secondary battery electrode (eg, negative electrode), an electrode assembly and secondary battery comprising the composite material, and a method for manufacturing the composite material.

In the present application, as an electrode to which a silicon material is applied, it is possible to provide an electrode having excellent lifespan characteristics that exhibits high capacity and stably maintains capacity even during repeated charging and discharging.

1 is a diagram showing a charge/discharge test result for a coin cell to which a composite material of the present application is applied as a negative electrode.

The present application will be specifically described through examples and comparative examples below, but the scope of the present application is not limited to the following examples.

1. Measurement of average particle diameter of metal powder

The average particle diameter of the metal powder (active material) was measured by a laser diffraction method, and a particle diameter (D50 particle diameter) corresponding to 50% of the volume cumulative amount in the volume-based particle size distribution curve was set as the average particle diameter. The laser diffraction method was performed according to KS L 1614 standard.

Example 1.

Manufacture of metal alloy foam

Copper (Cu) powder with an average particle diameter (D50 particle diameter) within the range of about 60 μm and germanium (Ge) powder with an average particle diameter (D50 particle diameter) of about 0.3 μm are mixed at a weight ratio (Cu:Ge) of 10:1. Used as a metal component. Subsequently, a slurry was prepared by mixing the metal component with butanol and ethyl cellulose in a weight ratio of 1:0.9:0.1 (metal component:butanol:ethyl cellulose).

The slurry was bar-coated to a thickness of about 400 μm on a graphite foil having a thickness of about 200 μm. After bar coating, the coating layer was maintained at about 100° C. for 30 minutes to dry, and then sintered at 900° C. for 2 hours in an H ₂ /N ₂ gas atmosphere to prepare a metal alloy form. During the sintering, the oxygen partial pressure (pO ₂ ) was adjusted to about 2.24 Х 10 ^-18 atm. The pore size of the prepared metal alloy foam was in the range of about 1 to 10 μm, and the porosity was about 72%.

manufacture of electrodes

Silicon was deposited on the metal alloy form by electrochemical plating. Specifically, a solution was prepared by dissolving SiCl ₄ in propylene carbonate at a concentration of about 0.5 M and then dissolving tetrabutylammonium chloride at a concentration of about 0.1 M. The prepared metal alloy form was applied to the solution as a working electrode, a Pt plate was applied as a counter electrode, and -1.5V was applied using an Ag wire as a reference electrode. Plating was performed for about 1 hour at a voltage of , and washed with propylene and then washed again with acetone to prepare an electrode. In the above process, whether or not silicon was deposited on the metal alloy form was confirmed through EDS (Energy Dispersive X-ray spectroscopy) analysis. The amount of silicon deposited on the metal alloy form was about 0.9 mg/cm ² . The amount of silicon is a value obtained by dividing the amount of silicon obtained through the weight before and after silicon deposition by the area of the metal alloy form.

In addition, the thickness and porosity of the metal alloy form on which the silicon was deposited were substantially the same as those of the metal alloy form before silicon deposition.

Comparative Example 1.

Manufacture of metal foam

As a metal component, a metal foam was prepared in the same manner as in Example 1, except that only copper (Cu) powder having an average particle diameter (D50 particle diameter) within a range of about 60 μm was used. The prepared metal foam had the same thickness and porosity as the metal alloy foam of Example 1.

manufacture of electrodes

Silicon was deposited on the prepared metal foam in the same manner as in Example 1. Specifically, a solution was prepared by dissolving SiCl ₄ in propylene carbonate at a concentration of about 0.5 M and then dissolving tetrabutylammonium chloride at a concentration of about 0.1 M. Applying the prepared metal foam to the solution as a working electrode, applying a Pt plate as a counter electrode, and using an Ag wire as a reference electrode, -1.5V Plating was performed for about 1 hour with a voltage, followed by washing with propylene and then again with acetone to prepare an electrode.

Comparative Example 2.

An electrode was prepared by depositing silicon on a copper foil having a thickness of about 50 μm in the same electrochemical plating method as in Example 1.

Test Example 1. Charge and discharge test

A coin cell was manufactured by applying the electrode prepared in Example or Comparative Example as a negative electrode, and a charge/discharge test was performed.

The coin cell was manufactured using a CR2032 standard coin cell kit (Wellcos Co., Ltd, Korea), a lithium foil (Li Foil) having a thickness of about 100 μm was used as an anode, and a carbonate-based electrolyte was used as an electrolyte. As, 1M LiPF ₆ in EC (Ethylene carbonate) / EMC (Ethylmethyl carbonate) (3/7, v / v, Korea GTR, Korea) was used.

Thereafter, a charge/discharge test was performed on the manufactured coin cell. In the charge/discharge test, the first and second cycles were charged and discharged at 0.1C, the third cycle was charged and discharged at 0.5C, and charging and discharging at 0.5C was repeated 50 times (charging conditions: CC/CV). , 5 mV/0.005C cuf-off, discharge conditions: CC, 1.5V cut off).

Table 1 below summarizes the capacity confirmed for each cycle in Examples and Comparative Examples. In Table 1 below, cycle 0 is the discharge capacity of the coin cell before charging and discharging, cycle 1 is the discharge capacity of the coin cell after charging and discharging once (charging and discharging once at 0.1C), and cycle 2 is the discharge capacity of the coin cell twice. The discharge capacity of a coin cell after charging and discharging (2 charging and discharging at 0.1 C), and 50 cycles is the discharge capacity of a coin cell after 50 charging and discharging (2 charging and discharging at 0.1 C + 48 charging and discharging at 0.5 C). .

Discharge capacity (mAh/g) 0 Cycle 1 Cycle 2 Cycle 50 Cycles Example 1 3500 3250 3120 2762 Comparative Example 1 3500 2998 2788 2098 Comparative Example 2 3500 3117 2941 2425

Claims (15)

a metal alloy form including a metal alloy including germanium and a metal different from the germanium; and
A composite material containing silicon present on or inside the metal alloy form. The composite material according to claim 1, wherein the metal other than germanium is at least one selected from the group consisting of stainless steel, aluminum, nickel, titanium, copper, silver and cadmium. The composite material according to claim 1, wherein the metal alloy form contains 0.1 wt % to 20 wt % of germanium. The composite material according to claim 3, wherein the metal alloy form includes 500 to 3000 parts by weight of a metal other than germanium, based on 100 parts by weight of the germanium. The composite material according to claim 1, wherein the metal alloy foam has a porosity in the range of 30% to 90%. The composite material according to claim 1, wherein the metal alloy foam has a thickness ranging from 0.5 μm to 1,000 μm. The composite material according to claim 1, wherein silicon is deposited on or inside the metal alloy form to form a layer. The composite of claim 1 comprising silicon in an amount of 0.1 to 10 mg/cm ² . a metal alloy form including a metal alloy including germanium and a metal different from the germanium; and
A negative electrode for a secondary battery comprising silicon present on the surface of the metal alloy form. anode; A negative electrode and a separator between the positive electrode and the negative electrode,
The cathode is
a metal alloy form including a metal alloy including germanium and a metal different from the germanium; and
Electrode assembly containing silicon present on the surface of the metal alloy form. A secondary battery comprising the electrode assembly of claim 10. A method of manufacturing a composite material comprising the step of forming silicon on or inside a metal alloy form containing germanium and a metal other than the germanium. 13. The method of claim 12 , wherein the metal alloy form is formed by sintering a precursor formed of a slurry containing germanium powder and a powder of a metal other than germanium under an oxygen partial pressure in the range of 1×10 ^-19 atm to 1×10 ^-15 atm Method for producing a composite material manufactured through the steps of. The method of claim 13, wherein the sintering is performed at a temperature of 700° C. to 1100° C. 13. The method of claim 12, wherein silicon is deposited on or inside the metal alloy form by a plating method.