WO2018225971A1 - Anode active material for lithium secondary battery, anode for lithium secondary battery, and lithium secondary battery comprising same anode - Google Patents

Abstract

The present invention provides an anode active material for a lithium secondary battery, the anode active material comprising: an inactive matrix including a 30 at% to 60 at% of silicon (Si), 15 at% to 50 at% of aluminum (A), 5 at% to 25 at% of iron (Fe), 0.1 at% to 5 at% of copper (Cu), and 1 at% to 25 at% of nickel (Ni); and active silicon nanoparticles uniformly dispersed and deposited on the inactive matrix, a fabrication method therefor, and a lithium secondary battery comprising the same anode active material. Accordingly, the lithium secondary battery of the present invention has a yield strength sufficient to endure the expansion stress of the silicon particles caused by the intercalation of lithium ions during charging and discharging and thus can restrain the particle refinement caused by the volume expansion and shrinkage of the anode active material during charging and discharging and thus has an improved property in the service life thereof.

Description

Anode active material for lithium secondary battery, anode for lithium secondary battery and lithium secondary battery comprising same

The present invention relates to a negative electrode active material for a lithium secondary battery, a negative electrode for a lithium secondary battery and a lithium secondary battery comprising the same. More particularly, the present invention relates to a negative active material for a lithium secondary battery, an anode for a lithium secondary battery, and a lithium secondary battery including the same, including active silicon nanoparticles uniformly dispersed and precipitated in an inactive matrix including silicon, aluminum, iron, copper, and nickel. will be.

Recently, as the wireless charging function using the wireless power transmission technology has been applied to smart phones all over the world, wireless charging technology that can charge the battery anytime and anywhere without a power connection by cable is being applied with IT. Accordingly, it is expected to be widely applied to wearable devices that can be worn or attached to a body as well as home appliances such as televisions and refrigerators or electric vehicles.

In this industrial environment, lithium secondary batteries are energy storage media applied to portable information devices such as smart phones, laptops, digital cameras, small home appliances and medical devices, electric vehicles, and large-capacity power storage systems. There is an increasing demand for performance improvements such as high power, long life and high safety.

Lithium secondary batteries are manufactured by using a material capable of intercalation and deintercalation of lithium ions as a cathode and an anode, and injecting an electrolyte after installing porous separators between the electrodes. In general, electricity is generated or consumed by a redox reaction by insertion and desorption of lithium ions in the cathode and the anode.

The performance improvement of the lithium secondary battery can be attributed to the technology development of four core materials: positive electrode, negative electrode, electrolyte, and separator which have a decisive influence on various characteristics such as capacity and output. Since the capacity of the positive electrode active material and the negative electrode active material used in the lithium secondary battery has already approached the theoretical capacity, the need for a new negative electrode active material is increasing to realize a high capacity and high output battery suitable for wireless charging energy storage. .

Generally, graphite, which is a negative electrode active material widely used in lithium secondary batteries, has a layered structure and thus has very useful characteristics for insertion and desorption of lithium ions. Graphite theoretically has a capacity of 372 mAh / g, but as the demand for high-capacity lithium batteries increases recently, new electrodes are required to replace graphite. Accordingly, active research for commercialization of electrode active materials forming an electrochemical alloy with lithium ions such as silicon (Si), tin (Sn), antimony (Sb), and aluminum (Al) as a high capacity negative electrode active material is actively conducted. It is becoming.

When silicon (Si) is used as a negative electrode active material, there is a problem that cracks and cracks of silicon particles occur due to volume change during the process of inserting and detaching lithium ions due to repeated charging and discharging. Due to this problem, the surface area of the negative electrode active material particles increases, and thus, a coating layer formed of the decomposition product of the nonaqueous electrolyte is formed on the surface of the negative electrode active material to increase the interfacial resistance between the negative electrode active material and the nonaqueous electrolyte, thereby degrading the charge and discharge life characteristics. There was a problem.

At present, in order to overcome the problems of silicon (Si) as a negative electrode active material, various methods such as controlling the shape and particle size of the silicon material or alloying, oxide, and complexing with a carbon material have been attempted, but fundamental problems are not solved. I can't.

[Preceding technical literature]

(Patent Document 1) Republic of Korea Patent No. 10-1385602

The technical problem to be achieved by the present invention is to improve the deterioration of the life characteristics due to the volume change when using a conventional silicon (Si) as a negative electrode active material, silicon (Si), aluminum (Al), iron (Fe), copper ( Life time does not decrease even after repeated charging and discharging by using a negative electrode active material containing 1 nm to 30 nm of active silicon nanoparticles uniformly dispersed and deposited on an inert matrix including Cu) and nickel (Ni). An object of the present invention is to provide a lithium secondary battery.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned above may be clearly understood by those skilled in the art from the following description. There will be.

In order to achieve the above technical problem, an embodiment of the present invention comprises the steps of preparing a melt by dissolving a mother alloy containing silicon; Preparing a silicon-based amorphous alloy by solidifying the melt by liquid quenching and solidification; And heat-treating the silicon-based amorphous alloy to produce a silicon-based composite metal, wherein the silicon-based composite metal comprises active silicon nanoparticles uniformly dispersed and precipitated in an inactive matrix. It provides a metal manufacturing method.

In an embodiment of the present invention, the silicon-based composite metal is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, copper ( Cu) 0.1 at% to 5 at% and nickel (Ni) 1 at% to 25 at%.

In order to achieve the above technical problem, another embodiment of the present invention is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, Lithium secondary, characterized in that it comprises an inert matrix comprising 0.1 at% to 5 at% of copper (Cu) and 1 to 25 at% of nickel (Ni) and active silicon nanoparticles uniformly dispersed and precipitated in the inactive matrix It provides a battery negative electrode active material.

In an embodiment of the present invention, the inert matrix may be formed of at least 0.1 of zirconium (Zr), niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca). It may be an anode active material for a lithium secondary battery, characterized in that it further comprises at% to 5 at%.

In an embodiment of the present invention, the inactive matrix may be a negative electrode active material for a lithium secondary battery, characterized in that it comprises any one or more of a crystalline matrix and an amorphous matrix.

In an embodiment of the present invention, the active silicon nanoparticles may be a negative electrode active material for a lithium secondary battery, characterized in that uniformly dispersed precipitation in the inactive matrix by copper clustering (Cu clustering) of the inactive matrix.

In an embodiment of the present invention, the active silicon nanoparticles may be a negative electrode active material for a lithium secondary battery, characterized in that the crystalline.

In an embodiment of the present invention, the particle size of the active silicon nanoparticles may be a negative electrode active material for a lithium secondary battery, characterized in that 1 nm to 30 nm.

In order to achieve the above technical problem, another embodiment of the present invention includes a negative electrode active material layer and a negative electrode active material layer formed on at least one surface of the negative electrode current collector, the negative electrode active material layer 75 wt% to 92 wt %, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder, wherein the anode active material includes an inert matrix and active silicon nanoparticles uniformly dispersed and precipitated in the inactive matrix. It provides a negative electrode for a lithium secondary battery.

In an embodiment of the present invention, the inert matrix may be a negative electrode for a lithium secondary battery, characterized in that it comprises a five-component or more silicon alloy.

In an embodiment of the present invention, the five-component or more silicon alloy is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, It may be a negative electrode for a lithium secondary battery comprising 0.1 to 5 at% of copper (Cu) and 1 to 25 at% of nickel (Ni).

In an embodiment of the present invention, the five-component or more silicon alloy is made of one or more of zirconium (Zr), niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge) and calcium (Ca). It may be a negative electrode for a lithium secondary battery characterized in that it further comprises 0.1 to 5 at% of the material.

In an embodiment of the present invention, the active silicon nanoparticles may be a negative electrode for a lithium secondary battery, characterized in that uniformly dispersed precipitation in the inactive matrix by copper clustering (Cu clustering) of the inactive matrix.

In an embodiment of the present invention, the particle size of the active silicon nanoparticles may be a negative electrode for a lithium secondary battery, characterized in that 1 nm to 30 nm.

In order to achieve the above technical problem, another embodiment of the present invention is a lithium secondary battery including a positive electrode, a negative electrode, an electrolyte and a separator, wherein the negative electrode is a negative electrode current collector and a negative electrode formed on at least one surface of the negative electrode current collector An active material layer, wherein the negative electrode active material layer comprises 75 wt% to 92 wt% of a negative electrode active material, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder; It provides a lithium secondary battery comprising the active silicon nanoparticles uniformly dispersed in the inert matrix.

In an embodiment of the present invention, the inactive matrix may be a lithium secondary battery comprising a silicon alloy of five or more components.

In an embodiment of the present invention, the five-component or more silicon alloy is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, The lithium secondary battery may include 0.1 at% to 5 at% of copper (Cu) and 1 to 25 at% of nickel (Ni).

In an embodiment of the present invention, the five-component or more silicon alloy is made of one or more of zirconium (Zr), niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge) and calcium (Ca). The lithium secondary battery may further include 0.1 at% to 5 at% of the material.

In an embodiment of the present invention, the active silicon nanoparticles may be a lithium secondary battery, characterized in that uniformly dispersed precipitation in the inactive matrix by copper clustering (Cu clustering) of the inactive matrix.

In an embodiment of the present invention, the particle size of the active silicon nanoparticles may be a lithium secondary battery, characterized in that 1 nm to 30 nm.

As an effect of the present invention, an anode comprising active silicon nanoparticles uniformly dispersed and precipitated in an inert matrix containing silicon (Si), aluminum (Al), iron (Fe), copper (Cu) and nickel (Ni) Since the active material tends to separate iron (Fe) and copper (Cu) in the inactive matrix, copper clustering may occur.

Accordingly, the Si-rich region having a low crystallization temperature is formed by the copper clustering phenomenon so that the active silicon particles are preferentially finely deposited during the heat treatment, and the inactive matrix has a crystalline structure or an amorphous structure. Can be formed.

As another effect of the present invention, the inactive matrix in the negative electrode active material may serve to suppress the volume expansion of the negative electrode active material while forming a structure that does not react with the lithium ions, the active silicon nanoparticles may be reversible reaction with lithium ions Therefore, the capacity of the negative electrode active material may be directly related to the capacity of the negative electrode active material.

Therefore, the inactive matrix has a yield strength that can withstand the expansion stress of the silicon particles due to the intercalation of lithium ions during the charging and discharging of the negative electrode active material, thereby expanding the volume of the negative electrode active material during the charging and discharging process. And particle differentiation due to shrinkage can be suppressed.

Therefore, when a lithium secondary battery is manufactured using a negative electrode active material for lithium secondary batteries including the active silicon nanoparticles uniformly dispersed in an inactive matrix, the initial coulombic efficiency is excellent at 80% or more, and the capacity is maintained even after 30 cycles. It may have a lifetime characteristic.

The effects of the present invention are not limited to the above-described effects, but should be understood to include all the effects deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a flow chart of a composite metal manufacturing method for a lithium secondary battery negative electrode active material according to an embodiment of the present invention.

FIG. 2 is a graph showing relative exothermic energy according to temperature with a differential scanning calorimetry (DSC) of a negative active material for a lithium secondary battery according to an exemplary embodiment of the present invention.

3 is a diffraction pattern illustrating crystallinity of a negative electrode active material for a lithium secondary battery according to an exemplary embodiment of the present invention.

4 is TEM-EDS images showing the distribution of components of the negative electrode active material for a lithium secondary battery according to an embodiment of the present invention.

5 is a graph showing the charge and discharge cycle life of the lithium secondary battery according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, coupled)" with another part, it is not only "directly connected" but also "indirectly connected" with another member in between. "Includes the case. In addition, when a part is said to "include" a certain component, this means that it may further include other components, without excluding the other components unless otherwise stated.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms “comprise” or “have” are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, using a rapid solidification process (Rapidly Solidification Process) and alloy design technology, to manufacture a high capacity, high output silicon alloy-based negative electrode active material suitable for wireless charging energy storage.

Until now, research on the production of silicon alloy-based anode active materials by using a mechanical alloying method, such as ball milling or a rapidly solidification process, has been conducted, but manufacturing process variables (ball milling time, size of powder particles) The silicon alloy system solves the volume expansion problem of silicon materials by dispersing and depositing the size of the silicon phase in the matrix phase with uniformity and reproducibility at a level of 100 nm or less due to the difficulty of controlling the cooling rate of the melt. There is no research report on the negative electrode active material, and the present invention intends to solve these problems in the following three methods.

First, silicon amorphous alloy design considering the microstructure of Cu clustering effect after heat treatment.

Second, silicon-based amorphous alloy manufacturing using the Rapidly Solidification Process.

Third, only the active metal through the heat treatment of the silicon-based amorphous alloy to implement a microstructure uniformly dispersed in the matrix.

Finally, the 100 nm-class silicon phase is transformed into a matrix phase having a yield strength capable of withstanding the expansion stress of the silicon particles due to the intercalation of lithium ions during the charge and discharge cycle. By implementing a uniformly dispersed precipitated microstructure, it is intended to suppress the particle micronization due to volume expansion and contraction of silicon particles generated by the insertion and desorption reaction of lithium ions.

Referring to Figure 1, the present invention comprises the steps of preparing a melt by dissolving a mother alloy containing silicon (S100); Preparing a silicon-based amorphous alloy by solidifying the melt by liquid quenching and solidification (S200); And preparing a silicon-based composite metal by heat-treating the silicon-based amorphous alloy (S300), wherein the silicon-based composite metal includes active silicon nanoparticles uniformly dispersed and precipitated in an inactive matrix. It provides a method for producing a composite metal for an active material.

The silicon-based composite metal may include silicon at 30 to 60 at%, aluminum at 15 to 50 at%, iron at 5 to 25 at%, and copper at 0.1 to 5 at. % And 1 at% to 25 at% of nickel (Ni).

The anode active material for a lithium secondary battery of the present invention is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, copper (Cu) 0.1 at It may include an inert matrix including% to 5 at% and 1 at% to 25 at% of nickel (Ni) and active silicon nanoparticles uniformly dispersed and precipitated in the inactive matrix.

Silicon (Si) constituting the negative electrode active material is mixed with silicon (Si) and active silicon nanoparticles in an inactive matrix. Since the active silicon nanoparticles can be reversibly reacted with lithium ions, the active silicon nanoparticles are directly related to the capacity of the negative electrode active material, and the inactive matrix may serve to suppress the volume expansion of the negative electrode active material while forming a structure that does not react with the lithium ions. . The active silicon nanoparticles may be uniformly dispersed and precipitated in an inactive matrix.

In the negative electrode active material for a lithium secondary battery, silicon (Si) may be involved in occlusion and release of lithium ions when the negative electrode active material is used as a negative electrode of a lithium secondary battery. Therefore, the amount of silicon (Si) included in the negative electrode active material for a lithium secondary battery is related to the capacity and life characteristics of the negative electrode active material. Specifically, the more silicon (Si) is included in the alloy, the capacity of the negative electrode active material may be improved, but the life characteristics may be somewhat lowered. Therefore, the content of silicon (Si) in the negative electrode active material is 30 to 60 at% level in order to improve the life characteristics rather than to improve the capacity of the negative electrode active material of the present invention. When the content of the silicon (Si) is less than 30 at%, it is not preferable to exhibit an excessively small capacity to implement the capacity as a negative electrode active material for a lithium secondary battery, the content of the silicon (Si) is greater than 60 at% In this case, since the content of components other than silicon (Si) constituting the inert matrix is small, the life improvement effect of the negative electrode active material for a lithium secondary battery may be difficult to appear, which is not preferable.

In general, copper (Cu) and iron (Fe) are difficult to be dissolved in silicon (Si) when in a solid state at room temperature.However, using a manufacturing method such as liquid rapid solidification such as melt spinning, copper (Cu) may be converted into silicon (Si). Can be forcibly hired). Forced solid solution copper (Cu) tends to be separated from iron (Fe), which causes copper clustering (Cu clustering) phenomenon. The active silicon nanoparticles may be uniformly dispersed and precipitated at a portion where the copper clustering phenomenon occurs, and the cathode active material of the present invention may include the active silicon nanoparticles uniformly dispersed and precipitated in an inactive matrix. have.

The content of copper (Cu) is preferably 0.1 at% to 5 at% when the content of the silicon (Si) is 30 at% to 60 at%. This is because when the content of copper (Cu) is less than 0.1 at%, the above-mentioned copper clustering phenomenon is insignificant and dispersion precipitation of active silicon nanoparticles may not occur, which is undesirable. In addition, when the copper (Cu) content is more than 5 at%, rather than copper (Cu) may act as an impurity, the content of the copper (Cu) is 0.1 at% to 5 at% is preferred level to be.

In the present invention, since nickel (Ni) and iron (Fe) included in the inactive matrix can play a role of improving the capacity of the negative electrode active material, the capacity characteristics can be improved.

As described above, the inactive matrix may include a five-component silicon-based alloy including silicon (Si), aluminum (Al), iron (Fe), copper (Cu), and nickel (Ni). Zirconium (Zr) may include a six-component silicon-based alloy further comprising 0.1 at% to 5 at%. At this time, zirconium (Zr) may serve to make the structure of the negative electrode active material fine, and improve the life characteristics.

In addition to the zirconium (Zr), 0.1 at% to 5 at% of a material consisting of at least one of niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca) is further included. It is possible to use a silicon-based alloy containing a six-component or more as the inert matrix, it can be used as a component for improving the capacity characteristics or life characteristics.

The inert matrix may include any one or more of a crystalline matrix and an amorphous matrix, and the active silicon nanoparticles uniformly dispersed in the inactive matrix may be in a crystalline phase, and the particle size of the active silicon nanoparticles may be 1 nm. It may be from 30 nm, more preferably from 10 nm to 20 nm.

Hereinafter, the negative electrode for lithium secondary batteries is demonstrated.

The negative electrode for a lithium secondary battery of the present invention includes a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector, and the negative electrode active material layer is 75 wt% to 92 wt% of a negative electrode active material, and 1 wt% to conductive material. 10 wt% and 7 wt% to 15 wt% of the binder, wherein the negative electrode active material may include an inert matrix and active silicon nanoparticles uniformly dispersed in the inactive matrix.

In an embodiment of the present invention, the negative electrode current collector may include a conductive material, and specifically, may be a thin conductive foil or foam. For example, the negative electrode current collector may include, but is not limited to, copper, gold, nickel, stainless, or titanium.

The negative electrode active material layer may be prepared by mixing a negative electrode active material, a conductive material, and a binder in a solvent to prepare a composition for forming a negative electrode active material layer, and then coating the composition on a negative electrode current collector. Since such a negative electrode manufacturing method is well known in the art, detailed description thereof will be omitted.

In an embodiment of the present invention, the negative electrode active material may include an inert matrix and active silicon nanoparticles uniformly dispersed in the inactive matrix, and the inert matrix may include a five-component or more silicon alloy. More specifically, the five-component or more silicon alloy is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, copper (Cu) 0.1 at% to 5 at% and nickel (Ni) 1 at% to 25 at%.

Silicon (Si) constituting the negative electrode active material is mixed with silicon (Si) and active silicon nanoparticles in an inactive matrix. Since the active silicon nanoparticles can be reversibly reacted with lithium ions, the active silicon nanoparticles are directly related to the capacity of the negative electrode active material, and the inactive matrix may serve to suppress the volume expansion of the negative electrode active material while forming a structure that does not react with the lithium ions. . The active silicon nanoparticles may be uniformly dispersed and precipitated in an inactive matrix.

In the negative electrode active material for a lithium secondary battery, silicon (Si) may be involved in occlusion and release of lithium ions when the negative electrode active material is used as a negative electrode of a lithium secondary battery. Therefore, the amount of silicon (Si) included in the negative electrode active material for a lithium secondary battery is related to the capacity and life characteristics of the negative electrode active material. Specifically, the more silicon (Si) is included in the alloy, the capacity of the negative electrode active material may be improved, but the life characteristics may be somewhat lowered. Therefore, the content of silicon (Si) in the negative electrode active material is 30 to 60 at% level in order to improve the life characteristics rather than to improve the capacity of the negative electrode active material of the present invention. When the content of the silicon (Si) is less than 30 at%, it is not preferable to exhibit an excessively small capacity to implement the capacity as a negative electrode active material for a lithium secondary battery, the content of the silicon (Si) is greater than 60 at% In this case, since the content of components other than silicon (Si) constituting the inert matrix is small, the life improvement effect of the negative electrode active material for a lithium secondary battery may be difficult to appear, which is not preferable.

In general, copper (Cu) and iron (Fe) are difficult to be dissolved in silicon (Si) when in a solid state at room temperature.However, using a manufacturing method such as liquid rapid solidification such as melt spinning, copper (Cu) may be converted into silicon (Si). Can be forcibly hired). Forced solid solution copper (Cu) tends to be separated from iron (Fe), which causes copper clustering (Cu clustering) phenomenon. Active silicon nanoparticles may be uniformly dispersed and precipitated at a portion where copper clustering appears, and due to this phenomenon, the negative active material of the present invention may include active silicon nanoparticles uniformly dispersed and precipitated in an inactive matrix. .

The content of copper (Cu) is preferably 0.1 at% to 5 at% when the content of the silicon (Si) is 30 at% to 60 at%. This is because when the content of copper (Cu) is less than 0.1 at%, the above-mentioned copper clustering phenomenon is insignificant and dispersion precipitation of active silicon nanoparticles may not occur, which is undesirable. In addition, when the copper (Cu) content is more than 5 at%, rather than copper (Cu) may act as an impurity, the content of the copper (Cu) is 0.1 at% to 5 at% is preferred level to be.

In the present invention, since nickel (Ni) and iron (Fe) included in the inactive matrix can play a role of improving the capacity of the negative electrode active material, the capacity characteristics can be improved.

As described above, the inactive matrix may include a five-component silicon-based alloy including silicon (Si), aluminum (Al), iron (Fe), copper (Cu), and nickel (Ni). Zirconium (Zr) may include a six-component silicon-based alloy further comprising 0.1 at% to 5 at%. At this time, zirconium (Zr) may serve to make the structure of the negative electrode active material fine, and improve the life characteristics.

In addition to the zirconium (Zr), 0.1 at% to 5 at% of a material consisting of at least one of niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca) is further included. It is possible to use a silicon-based alloy containing a six-component or more as the inert matrix, it can be used as a component for improving the capacity characteristics or life characteristics.

The inert matrix may include any one or more of a crystalline matrix and an amorphous matrix, and the active silicon nanoparticles uniformly dispersed in the inactive matrix may be in a crystalline phase, and the particle size of the active silicon nanoparticles may be 1 nm. It may be from 30 nm, more preferably from 10 nm to 20 nm.

In an embodiment of the present invention, the negative electrode active material layer may include 75 wt% to 92 wt% of the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder.

The conductive material is used to impart conductivity, and any lithium secondary battery configured may be used as long as it is an electron conductive material without causing chemical change. Specifically, any one or more of conductive polymer materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder such as copper, nickel, aluminum, silver, metal fiber and polyphenylene derivatives Can be used, but is not limited thereto.

When the content of the conductive material is less than 1 wt%, the effect of improving the conductivity and the lifespan characteristics according to the use of the conductive material is insignificant, and when the conductive material content is more than 5 wt%, the conductive material due to the increase in the specific surface area of the conductive material It is not preferable because the reaction between the electrolyte and the electrolyte may be increased to reduce the life characteristics. More specifically, the content of the conductive material may be 1 wt% to 3 wt%.

The binder adheres the particles of the negative electrode active material to each other well, and adheres the negative electrode active material to the negative electrode current collector, and specifically, polyimide, polyamideimide, polybenzimidazole, polyvinyl alcohol, carboxymethylcellulose, and hydroxide. Oxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, Any one or more of styrene-butadiene, acrylated styrene-butadiene, and an epoxy resin may be used, but is not limited thereto.

When the content of the binder is less than 7 wt%, it is not preferable to exhibit sufficient adhesive strength in the negative electrode, and when the content of the binder is more than 15 wt%, it is not preferable because there is a fear of deterioration in capacity characteristics of the lithium secondary battery. More specifically, the binder content may be 7 wt% to 10 wt%.

Since the content of the conductive material is preferably 1 wt% to 10 wt%, and the content of the binder is preferably 7 wt% to 15 wt%, the content of the negative electrode active material in the negative electrode active material layer is 75 wt% to 92 wt%. Is the preferred level.

N-methylpyrrolidone or n-hexane may be used as a solvent for mixing the negative electrode active material, the conductive material and the binder, but is not limited thereto.

Hereinafter, a lithium secondary battery will be described.

The lithium secondary battery of the present invention may include a positive electrode, a negative electrode, an electrolyte, and a separator, and the negative electrode may include a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector.

In an embodiment of the present invention, the negative electrode current collector may include a conductive material, and specifically, may be a thin conductive foil or foam. For example, the negative electrode current collector may include, but is not limited to, copper, gold, nickel, stainless, or titanium.

The negative electrode active material layer may be prepared by mixing a negative electrode active material, a conductive material, and a binder in a solvent to prepare a composition for forming a negative electrode active material layer, and then coating the composition on a negative electrode current collector. Since such a negative electrode manufacturing method is well known in the art, detailed description thereof will be omitted.

In an embodiment of the present invention, the negative electrode active material may include an inert matrix and active silicon nanoparticles uniformly dispersed in the inactive matrix, and the inert matrix may include a five-component or more silicon alloy. More specifically, the five-component or more silicon alloy is silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, copper (Cu) 0.1 at% to 5 at% and nickel (Ni) 1 at% to 25 at%.

Silicon (Si) constituting the negative electrode active material is mixed with silicon (Si) and active silicon nanoparticles in an inactive matrix. Since the active silicon nanoparticles can be reversibly reacted with lithium ions, the active silicon nanoparticles are directly related to the capacity of the negative electrode active material, and the inactive matrix may serve to suppress the volume expansion of the negative electrode active material while forming a structure that does not react with the lithium ions. . The active silicon nanoparticles may be uniformly dispersed and precipitated in an inactive matrix.

In the negative electrode active material for a lithium secondary battery, silicon (Si) may be involved in occlusion and release of lithium ions when the negative electrode active material is used as a negative electrode of a lithium secondary battery. Therefore, the amount of silicon (Si) included in the negative electrode active material for a lithium secondary battery is related to the capacity and life characteristics of the negative electrode active material. Specifically, the more silicon (Si) is included in the alloy, the capacity of the negative electrode active material may be improved, but the life characteristics may be somewhat lowered. Therefore, the content of silicon (Si) in the negative electrode active material is 30 to 60 at% level in order to improve the life characteristics rather than to improve the capacity of the negative electrode active material of the present invention. When the content of the silicon (Si) is less than 30 at%, it is not preferable to exhibit an excessively small capacity to implement the capacity as a negative electrode active material for a lithium secondary battery, the content of the silicon (Si) is greater than 60 at% In this case, since the content of components other than silicon (Si) constituting the inert matrix is small, the life improvement effect of the negative electrode active material for a lithium secondary battery may be difficult to appear, which is not preferable.

In general, copper (Cu) and iron (Fe) are difficult to be dissolved in silicon (Si) when in a solid state at room temperature.However, using a manufacturing method such as liquid rapid solidification such as melt spinning, copper (Cu) may be converted into silicon (Si). Can be forcibly hired). Forced solid solution copper (Cu) tends to be separated from iron (Fe), which causes copper clustering (Cu clustering) phenomenon. Active silicon nanoparticles may be uniformly dispersed and precipitated at a portion where copper clustering appears, and due to this phenomenon, the negative active material of the present invention may include active silicon nanoparticles uniformly dispersed and precipitated in an inactive matrix. .

The content of copper (Cu) is preferably 0.1 at% to 5 at% when the content of the silicon (Si) is 30 at% to 60 at%. This is because when the content of copper (Cu) is less than 0.1 at%, the above-mentioned copper clustering phenomenon is insignificant and dispersion precipitation of active silicon nanoparticles may not occur, which is undesirable. In addition, when the copper (Cu) content is more than 5 at%, rather than copper (Cu) may act as an impurity, the content of the copper (Cu) is 0.1 at% to 5 at% is preferred level to be.

In the present invention, since nickel (Ni) and iron (Fe) included in the inactive matrix can play a role of improving the capacity of the negative electrode active material, the capacity characteristics can be improved.

As described above, the inactive matrix may include a five-component silicon-based alloy including silicon (Si), aluminum (Al), iron (Fe), copper (Cu), and nickel (Ni). Zirconium (Zr) may include a six-component silicon-based alloy further comprising 0.1 at% to 5 at%. At this time, zirconium (Zr) may serve to make the structure of the negative electrode active material fine, and improve the life characteristics.

In addition to the zirconium (Zr), 0.1 at% to 5 at% of a material consisting of at least one of niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca) is further included. It is possible to use a silicon-based alloy containing a six-component or more as the inert matrix, it can be used as a component for improving the capacity characteristics or life characteristics.

The inert matrix may include any one or more of a crystalline matrix and an amorphous matrix, and the active silicon nanoparticles uniformly dispersed in the inactive matrix may be in a crystalline phase, and the particle size of the active silicon nanoparticles may be 1 nm. It may be from 30 nm, more preferably from 10 nm to 20 nm.

In an embodiment of the present invention, the negative electrode active material layer may include 75 wt% to 92 wt% of the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder.

The conductive material is used to impart conductivity, and any lithium secondary battery configured may be used as long as it is an electron conductive material without causing chemical change. Specifically, any one or more of conductive polymer materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder such as copper, nickel, aluminum, silver, metal fiber and polyphenylene derivatives Can be used, but is not limited thereto.

When the content of the conductive material is less than 1 wt%, the effect of improving the conductivity and the lifespan characteristics according to the use of the conductive material is insignificant, and when the conductive material content is more than 5 wt%, the conductive material due to the increase in the specific surface area of the conductive material It is not preferable because the reaction between the electrolyte and the electrolyte may be increased to reduce the life characteristics. More specifically, the content of the conductive material may be 1 wt% to 3 wt%.

The binder adheres the particles of the negative electrode active material to each other well, and adheres the negative electrode active material to the negative electrode current collector, and specifically, polyimide, polyamideimide, polybenzimidazole, polyvinyl alcohol, carboxymethylcellulose, and hydroxide. Oxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, Any one or more of styrene-butadiene, acrylated styrene-butadiene, and an epoxy resin may be used, but is not limited thereto.

When the content of the binder is less than 7 wt%, it is not preferable to exhibit sufficient adhesive strength in the negative electrode, and when the content of the binder is more than 15 wt%, it is not preferable because there is a fear of deterioration in capacity characteristics of the lithium secondary battery. More specifically, the binder content may be 7 wt% to 10 wt%.

Since the content of the conductive material is preferably 1 wt% to 10 wt%, and the content of the binder is preferably 7 wt% to 15 wt%, the content of the negative electrode active material in the negative electrode active material layer is 75 wt% to 92 wt%. Is the preferred level.

N-methylpyrrolidone or n-hexane may be used as a solvent for mixing the negative electrode active material, the conductive material and the binder, but is not limited thereto.

In an embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer is mixed with a positive electrode active material, a binder and a conductive material in a solvent to form a positive electrode active material layer After the composition is prepared, the composition may be in a form coated on a positive electrode current collector. Since such a method for manufacturing a positive electrode is well known in the art, detailed description thereof will be omitted.

The cathode active material may include a material capable of reversibly inserting and detaching lithium ions. Specifically, the cathode active material may include a lithium-containing transition metal oxide, a lithium-containing transition metal sulfide, and the like. For example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), LiNi _1-y Co _y O ₂ (0 <y <1), LiCo _1-y Mn _y O ₂ (0 <y <1), LiNi _1-y Mn _y O ₂ (0 < y <1), Li (Ni _a Co _b Mn _c ) O ₄ (0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), LiMn _2-z Ni _z One or more of O ₄ (0 <Z <2), LiMn _2-z Co _z O ₄ (0 <Z <2), LiCoPO ₄ , and LiFePO ₄ may be used, but is not limited thereto.

The binder serves to adhere the positive electrode active material particles to each other and to adhere the positive electrode active material to the positive electrode current collector, and specifically, to polyimide, polyamideimide, polybenzimidazole, polyvinyl alcohol, carboxymethyl cellulose, and hydroxide. Oxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, Any one or more of styrene-butadiene, acrylated styrene-butadiene, and an epoxy resin may be used, but is not limited thereto.

The conductive material is used to impart conductivity, and any lithium secondary battery configured may be used as long as it is an electron conductive material without causing chemical change. Specifically, any one or more of conductive polymer materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder such as copper, nickel, aluminum, silver, metal fiber and polyphenylene derivatives Can be used, but is not limited thereto.

N-methylpyrrolidone or n-hexane may be used as the solvent, but is not limited thereto.

The positive electrode current collector may include a conductive material, and specifically, may be a thin conductive foil or foam. For example, the positive electrode current collector may include, but is not limited to, aluminum, nickel or an alloy thereof.

In an embodiment of the present invention, the electrolyte may include a non-aqueous organic solvent and a lithium salt. Specifically, the non-aqueous organic solvent may be any one or more of a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based and aprotic solvent. For example, the non-aqueous organic solvent is dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), n-methyl acetate, dibutyl ether , Cyclohexanone, isopropyl alcohol and sulfolane (sulfolane) may include one or more selected from the group consisting of solvents. These non-aqueous organic solvents may be used alone or in combination of two or more thereof.

In addition, the lithium salt may be LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiN (SO ₂ C ₂ F ₅ ) ₂ , Li (CF ₃ SO ₂ ) ₂ N, LiN (SO ₃ C ₂ F ₅ ) ₂ , LiC ₄ F ₉ SO ₃ , LiClO ₄ , LiAlO ₂ , LiAlCl ₄ , LiN (C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (x and y are natural numbers), LiCl, LiI and LiB (C ₂ O ₄ ) ₂ It may include one or two or more selected from the group consisting of. These electrolyte salts may be used alone or in combination of two or more thereof.

In an embodiment of the present invention, the separator may be polyethylene, polypropylene, or polyvinylidene fluoride as a single layer, or two or more multilayer films thereof may be used.

Hereinafter, the preparation examples and experimental examples of the present invention. However, these preparation examples and experimental examples are intended to explain the configuration and effects of the present invention in more detail, and the scope of the present invention is not limited thereto.

Example 1

Alloys containing silicon (Si), aluminum (Al), iron (Fe), copper (Cu) and nickel (Ni) are melted by an arc melting method to prepare a melt, and then the melt is rotated at a speed of 40 m / s. The amorphous alloy having the composition of Si ₅₆ Al ₂₅ Fe ₁₆ Cu ₁ Ni ₂ was prepared by applying to a single roll quench solidification method sprayed onto a copper roll.

Coin-shaped electrode plates were prepared by using the amorphous alloy as a negative electrode active material, and Ketjen Black as a negative electrode active material and a conductive material and PAI as a binder were mixed at a weight ratio of 87: 3: 10, and heat-treated at 400 ° C. for 1 hour in an Ar atmosphere. A negative electrode was prepared.

Example 2

Alloys containing silicon (Si), aluminum (Al), iron (Fe), copper (Cu) and nickel (Ni) are melted by an arc melting method to prepare a melt, and then the melt is rotated at a speed of 40 m / s. The amorphous alloy having the composition of Si ₅₆ Al ₂₅ Fe ₁₆ Cu ₁ Ni ₂ was prepared by applying to a single roll quench solidification method sprayed onto a copper roll. The amorphous alloy was heat-treated at 450 ° C. to produce a silicon-based composite metal.

A coin-shaped electrode plate was manufactured by using the silicon-based composite metal as a negative electrode active material, and Ketjen Black as a negative electrode active material and a conductive material and PAI as a binder were mixed at a weight ratio of 87: 3: 10, and heat treated at 400 ° C. for 1 hour in an Ar atmosphere. To prepare a negative electrode.

Example 3

An anode was prepared in the same manner as in Example 2 except that the amorphous alloy was heat-treated at 500 ° C. to produce a silicon-based composite metal.

Example 4

A negative electrode was prepared in the same manner as in Example 2 except that the amorphous alloy was heat-treated at 550 ° C. to produce a silicon-based composite metal.

Example 5

A negative electrode was prepared in the same manner as in Example 2 except that the amorphous alloy was heat-treated at 650 ° C. to produce a silicon-based composite metal.

FIG. 2 is a graph showing relatively exothermic energy according to temperature with a differential scanning calorimetry (DSC) of a negative active material for a lithium secondary battery of Example 1; Figure 2 shows the crystallization behavior according to the temperature change of the amorphous negative electrode active material.

3 is a diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Example 1. FIG. 4 is TEM-EDS images showing the component distribution of the negative electrode active material for a lithium secondary battery of Example 1.

3 to 4, it was confirmed that Example 1 is an amorphous alloy having an amorphous phase.

Charge capacity, discharge capacity, and initial coulombic efficiency of the negative electrode active material when charging and discharging was performed once after manufacturing a lithium secondary battery using the negative electrodes of Examples 1 to 5 (initial discharge capacity divided by initial charge capacity) Values) are shown in Table 1 below.

division	Alloy composition					Crystal structure	Amorphous alloy heat treatment condition	Electrode characteristic evaluation result
division	Si (at%)	Al (at%)	Fe (at%)	Cu (at%)	Ni (at%)	Crystal phase	Temperature, time	Initial charge (mAh / g)	Initial discharge (mAh / g)	Initial Coulomb Efficiency (%)
Example 1	56	25	16	One	2	Amorphous	Pristine	236.2	91.5	38.7
Example 2	56	25	16	One	2	Amorphous + crystalline	450 ℃, 1hr	278.4	155.1	55.7
Example 3	56	25	16	One	2	Amorphous + crystalline	500 ℃, 1hr	1100.9	943.5	85.7
Example 4	56	25	16	One	2	Crystalline	550 ℃, 1hr	1192.3	1021.4	85.6
Example 5	56	25	16	One	2	Crystalline	650 ℃, 1hr	1309.8	1144.9	87.4

5 is a graph showing charge and discharge cycle lifetimes of Examples 1 to 5.

Referring to Table 1 and FIG. 5, a lithium secondary battery using a negative electrode active material having a crystalline structure has a high initial Coulomb efficiency but a decrease in cycle life, and a lithium secondary battery using a negative electrode active material having an amorphous structure has a low initial Coulomb efficiency. It can be seen that the cycle life is maintained.

Embodiment of the present invention can produce amorphous alloy reproducibly in the range of 30 m / s to 60 m / s rotational linear velocity of the copper wheel in the melt spinning is a liquid quenching solidification method, more preferably 40 m / s It is possible to produce amorphous alloys reproducibly at speed.

After the amorphous alloy is manufactured, the heat treatment is performed at a constant temperature to produce a cathode active material in which reproducible active silicon particles are uniformly dispersed and precipitated in a nano size in an inert matrix, and the capacity of the reproducible anode active material is maintained even after 30 cycles. It can be determined that it can have excellent life characteristics.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is represented by the following claims, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention.

Claims (20)

1. Preparing a melt by dissolving a mother alloy including silicon;

   Preparing a silicon-based amorphous alloy by solidifying the melt by liquid quenching and solidification; And

   Heat treating the silicon-based amorphous alloy to produce a silicon-based composite metal,

   The silicon-based composite metal manufacturing method of a composite metal for a lithium secondary battery negative electrode active material, characterized in that it comprises active silicon nanoparticles dispersed uniformly in an inert matrix.
2. The method of claim 1,

   The silicon-based composite metal may include silicon at 30 to 60 at%, aluminum at 15 to 50 at%, iron at 5 to 25 at%, and copper at 0.1 to 5 at. % And nickel (Ni) 1 at% to 25 at% of a composite metal manufacturing method for a lithium secondary battery negative electrode active material.
3. Silicon (Si) 30 at% to 60 at%, aluminum (Al) 15 at% to 50 at%, iron (Fe) 5 at% to 25 at%, copper (Cu) 0.1 at% to 5 at% and nickel (Ni ) Inert matrix comprising 1 at% to 25 at%; And

   An anode active material for a lithium secondary battery, characterized in that it comprises active silicon nanoparticles uniformly dispersed in the inert matrix.
4. The method of claim 3, wherein

   The inert matrix further comprises 0.1 at% to 5 at% of a material consisting of at least one of zirconium (Zr), niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca). An anode active material for a lithium secondary battery, characterized in that.
5. The method of claim 3, wherein

   The inert matrix is a negative electrode active material for a lithium secondary battery, characterized in that it comprises any one or more of a crystalline matrix and an amorphous matrix.
6. The method of claim 3, wherein

   The active silicon nanoparticles are anode active material for lithium secondary battery, characterized in that uniformly dispersed precipitation in the inert matrix by copper clustering (Cu clustering) of the inert matrix.
7. The method of claim 3, wherein

   The active silicon nanoparticles are negative electrode active material for lithium secondary battery, characterized in that the crystalline.
8. The method of claim 3, wherein

   The particle size of the active silicon nanoparticles is a lithium active battery negative electrode active material, characterized in that 1 nm to 30 nm.
9. Negative electrode current collector; And

   It includes a negative electrode active material layer formed on at least one surface of the negative electrode current collector,

   The negative electrode active material layer includes 75 wt% to 92 wt% of the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder,

   The negative electrode active material is a negative electrode for a lithium secondary battery, characterized in that it comprises an inert matrix and active silicon nanoparticles uniformly dispersed in the inactive matrix.
10. The method of claim 9,

    The inert matrix is a negative electrode for a lithium secondary battery, characterized in that containing a five-component or more silicon alloy.
11. The method of claim 10,

    The five-component or more silicon alloy may include at least 30 at% to 60 at% of silicon (Si), at least 15 at% to 50 at% of aluminum (Al), at least 5 to 25 at% of iron (Fe), and at least 0.1 at% of copper (Cu). A negative electrode for a lithium secondary battery comprising 5 at% and 1 at% to 25 at% nickel (Ni).
12. The method of claim 10,

    The five-component or more silicon alloy is 0.1 at% to 5 at% of a material consisting of at least one of zirconium (Zr), niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca). A negative electrode for a lithium secondary battery, characterized in that it further comprises%.
13. The method of claim 9,

    The active silicon nanoparticles are uniformly dispersed precipitated in the inactive matrix by copper clustering (Cu clustering) of the inert matrix, characterized in that the lithium secondary battery negative electrode.
14. The method of claim 9,

    The particle size of the active silicon nanoparticles is a lithium secondary battery negative electrode, characterized in that 1 nm to 30 nm.
15. In a lithium secondary battery comprising a positive electrode, a negative electrode, an electrolyte and a separator,

    The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector,

    The negative electrode active material layer includes 75 wt% to 92 wt% of the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder,

    The negative electrode active material is a lithium secondary battery comprising an inert matrix and active silicon nanoparticles uniformly dispersed in the inert matrix.
16. The method of claim 15,

    The inert matrix is a lithium secondary battery, characterized in that containing a five-component or more silicon alloy.
17. The method of claim 16,

    The five-component or more silicon alloy may include at least 30 at% to 60 at% of silicon (Si), at least 15 at% to 50 at% of aluminum (Al), at least 5 to 25 at% of iron (Fe), and at least 0.1 at% of copper (Cu). A lithium secondary battery comprising 5 at% and 1 at% to 25 at% of nickel (Ni).
18. The method of claim 17,

    The five-component or more silicon alloy is 0.1 at% to 5 at% of a material consisting of at least one of zirconium (Zr), niobium (Nb), titanium (Ti), chromium (Cr), germanium (Ge), and calcium (Ca). Lithium secondary battery, characterized in that it further comprises.
19. The method of claim 15,

    The active silicon nanoparticles are uniformly dispersed precipitated in the inactive matrix by copper clustering (Cu clustering) of the inert matrix.
20. The method of claim 15,

    The particle size of the active silicon nanoparticles is a lithium secondary battery, characterized in that 1 nm to 30 nm.

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