KR102218033B1 - Negative active material manufacturing method and negative active material for lithium secondary battery, negative electrode for lithium secondary battery, and lithium secondary battery including the same - Google Patents

Abstract

The present invention includes Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at%, wherein M is Al and , Ti, W, Co, Cr, Ge, or Ca, including at least one metal element selected from the group consisting of, and uniformly the crystalline Si phase, which is an active metal having a size of 100 nm or less, on an inert metal amorphous matrix or an inert crystalline matrix A method for manufacturing a negative electrode active material for a lithium secondary battery having a dispersed precipitated microstructure, a negative electrode active material for a lithium secondary battery, a negative electrode for a lithium secondary battery, and a lithium secondary battery including the same are provided. Therefore, the lithium secondary battery of the present invention has a yield strength that can withstand the expansion stress of silicon particles due to intercalation of lithium ions during charging and discharging, so that the volume of the anode active material expands and contracts during charging and discharging. Particle pulverization due to can be suppressed, and life characteristics can be improved.

Description

Manufacturing method of negative electrode active material for lithium secondary battery, negative electrode for lithium secondary battery, negative electrode for lithium secondary battery, and lithium secondary battery including the same. BATTERY INCLUDING THE 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 including the same. More specifically, a crystalline silicon phase, an active metal having a size of 100 nm or less, uniformly dispersed and precipitated in an inert metal amorphous matrix phase or inert crystalline matrix phase including silicon, aluminum, iron, and copper is uniformly dispersed and precipitated. 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 including the same.

Recently, as the wireless charging function using wireless power transmission technology has begun to be applied to smartphones worldwide, wireless charging technology that can charge the battery anytime, anywhere without power connection by cable is being grafted with IT. Accordingly, it is expected to be extended to the field of wearable devices that can be worn or attached to the body, as well as home appliances such as televisions and refrigerators or electric vehicles.

In such an industrial environment, lithium secondary batteries are increasingly applied as energy storage media applied to portable information devices such as smartphones, notebook computers, digital cameras, small home appliances and medical devices, electric vehicles, and large-capacity power storage systems, and their application range has gradually expanded, resulting in high capacity. There is an increasing demand for performance improvement 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 negative electrode and a positive electrode, installing a porous separator between the electrodes, and injecting an electrolyte solution. In general, electricity is generated or consumed by a redox reaction by insertion and desorption of lithium ions in the negative electrode and the positive electrode.

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

Typically, graphite, which is a negative electrode active material widely used in lithium secondary batteries, has a layered structure and is thus very useful for insertion and desorption of lithium ions. Graphite theoretically exhibits a capacity of 372 mAh/g, but as the demand for high-capacity lithium batteries in recent years increases, a new electrode capable of replacing graphite is required. Accordingly, research for commercialization of electrode active materials that form electrochemical alloys with lithium ions such as silicon (Si), tin (Sn), antimony (Sb), and aluminum (Al) as a high-capacity negative active material is actively conducted. Has become.

When silicon (Si) is used as a negative electrode active material, there is a problem in that the silicon particles are cracked and cracked due to volume change during the process of insertion and desorption of lithium ions by repeated charging and discharging. Due to this problem, the surface area of the negative electrode active material particles increases, and as a result, a film layer made of the decomposition product of the non-aqueous electrolyte is formed thick on the surface of the negative electrode active material, and the interface resistance between the negative electrode active material and the non-aqueous electrolyte increases, resulting in decreased charge/discharge life characteristics. There was a problem.

Currently, in order to overcome the problem of silicon (Si) as a negative electrode active material, various methods such as controlling the shape and particle size of the silicon material, alloying, oxidizing, and complexing with carbon materials have been attempted, but the fundamental problem has not been solved. It is not possible.

In addition, until now, research on the manufacture of silicon alloy-based negative electrode active materials using the mechanical alloying method Ball Milling or Rapidly Solidification Process is ongoing, but the manufacturing process parameters (ball milling time, powder particle The size of the silicon phase (Si phase), which is an active metal, cannot be uniformly and reproducibly dispersed and precipitated in the matrix phase, which is an inert metal, due to difficulty in controlling the size and cooling rate of the molten metal). When silicon is applied to a negative electrode active material for a lithium secondary battery, there is a problem in that the problem of volume expansion of the silicon material during charge and discharge cannot be solved.

Korean Patent Registration No. 10-1385602

The technical problem to be achieved by the present invention is to improve the deterioration of lifespan characteristics due to volume change when conventional silicon (Si) is used as a negative electrode active material, on an inert metal amorphous matrix including silicon, aluminum, iron, and copper. A negative electrode active material for lithium secondary batteries, a negative electrode for lithium secondary batteries, and a lithium secondary battery in which a microstructure in which the crystalline silicon phase, which is an active metal with a size of less than 100 nm, uniformly dispersed and precipitated in an inert crystalline matrix phase, is uniformly dispersed and precipitated. It aims to provide knowledge.

In addition, 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 the conventional silicon (Si) is used as a negative electrode active material, while securing a uniform size of the Si precipitation phase, charge/discharge capacity, cycle life, etc. Provides a method for manufacturing a negative electrode active material for a lithium secondary battery that enables the production of a negative electrode active material for a lithium secondary battery with secured reproducibility, a negative active material for the lithium secondary battery, a negative electrode for a lithium secondary battery made of the negative electrode active material, and a lithium secondary battery including the same To do it for a different purpose.

The technical problem to be achieved by the present invention is not limited to the technical problems mentioned above, and other technical problems that are not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. There will be.

In order to achieve the above technical problem, an embodiment of the present invention is to prepare a molten metal by mixing each metal or alloy of Si, added metal M, Fe, and Cu in a ratio to become an alloy of a preset composition ratio and then melting it. step; Solidifying the molten metal by a liquid quenching solidification method to prepare a Si-based amorphous alloy having a Si-M-Fe-Cu composition of the predetermined composition ratio and in which Cu is forcibly dissolved in Fe; And heat-treating the Si-based amorphous alloy to prepare a negative active material for a lithium secondary battery having a microstructure in which a crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and precipitated on an inert metal amorphous matrix or on an inactive crystalline matrix. Including, wherein M is Al, Ti, W, Co, Cr, Ge, or a method for manufacturing a negative active material for a lithium secondary battery for producing a negative active material for a lithium secondary battery containing at least one metal element selected from the group consisting of Ca Provides.

In an embodiment of the present invention, the anode active material for a lithium secondary battery is Si 45 at% or more and less than 60 at%, added metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at%, and Cu 0.1 at% To 5 at%.

In order to achieve the above technical problem, another embodiment of the present invention, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% To 5 at%, wherein M includes Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca, and inert metal amorphous matrix phase or inert crystalline matrix phase It provides an anode active material for a lithium secondary battery, characterized in that it has a microstructure in which a crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and precipitated.

In an embodiment of the present invention, a negative active material for a lithium secondary battery comprising 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca Can be

In an embodiment of the present invention, the active metal crystalline Si phase is the inert metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly dissolved by a liquid quench solidification method. It may be a negative active material for a lithium secondary battery, characterized in that uniformly dispersed and precipitated on the crystalline matrix.

In order to achieve the above technical problem, another embodiment 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, wherein the negative electrode active material layer is 75 wt% to 92 wt% of the negative electrode active material %, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder, and the negative electrode active material is a fine particle having a size of 100 nm or less uniformly dispersed and precipitated on an inert metal amorphous matrix or an inert crystalline matrix. It provides a negative electrode for a lithium secondary battery, characterized in that it comprises a crystalline Si phase, which is a tissue active metal.

In an embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at %, and M may be a negative electrode for a lithium secondary battery, characterized in that it contains Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

In an embodiment of the present invention, the negative active material comprises 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. It may be a negative electrode for a lithium secondary battery.

In an embodiment of the present invention, the active metal crystalline Si phase is the inert metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly dissolved by a liquid quench solidification method. It may be a negative electrode for a lithium secondary battery, characterized in that uniformly dispersed and precipitated on the crystalline matrix.

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. Including an active material layer, wherein the negative electrode active material layer comprises a negative electrode active material 75 wt% to 92 wt%, a conductive material 1 wt% to 10 wt%, and a binder 7 wt% to 15 wt%, the negative electrode active material is an inert metal amorphous It provides a lithium secondary battery comprising a crystalline Si phase, a microstructured active metal having a size of 100 nm or less uniformly dispersed and precipitated on a matrix phase or an inert crystalline matrix.

In an embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at %, and M may be a lithium secondary battery comprising Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

In an embodiment of the present invention, the negative active material comprises 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. It may be a lithium secondary battery.

In an embodiment of the present invention, the active metal crystalline Si phase is the inert metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly dissolved by a liquid quench solidification method. It may be a lithium secondary battery characterized in that uniform dispersion and precipitation on the crystalline matrix.

As an effect of the present invention, the negative electrode active material comprising a crystalline Si phase, an active metal uniformly dispersed and precipitated on the inert metal amorphous matrix phase or the inert crystalline matrix including Si, additive metals M, Fe, and Cu, Copper clustering may occur due to a tendency of separation of iron (Fe) and copper (Cu) in an inert metal amorphous matrix phase or an inert crystalline matrix phase.

Accordingly, a Si-rich region having a low crystallization temperature is formed by the Cu clustering phenomenon, so that the crystalline Si phase, which is an active metal, is finely formed in the inert metal amorphous matrix phase or the inactive crystalline matrix phase during heat treatment. It can precipitate.

As another effect of the present invention, the inert metal amorphous matrix phase or the inert crystalline matrix phase 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 lithium ions. Since the crystalline Si phase can react reversibly with lithium ions, it is directly related to the capacity of the negative electrode active material, thereby exhibiting improved capacity characteristics of the negative electrode active material.

Therefore, when charging and discharging the negative electrode active material, the inert metal amorphous matrix phase or the inert crystalline matrix phase has a yield strength capable of withstanding the expansion stress of silicon particles due to intercalation of lithium ions, and charging and discharging proceeds. When the negative electrode active material expands and contracts in volume, particle micronization can be suppressed.

Therefore, when a lithium secondary battery is manufactured using a negative electrode active material for a lithium secondary battery including an active metal crystalline Si phase uniformly dispersed and precipitated on the inert metal amorphous matrix or the inert crystalline matrix, the initial coulomb efficiency is 85% or more. It is excellent, and can have a lifespan characteristic in which the capacity is maintained at 75% or more even after 30 cycles.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be 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 method for manufacturing a negative active material for a lithium secondary battery according to an embodiment of the present invention.
2 is a TEM photograph of a negative active material for a lithium secondary battery of Example 3 prepared according to an embodiment of the present invention.
3 is a diffraction pattern showing the crystallinity of the negative active material for a lithium secondary battery of Example 1 prepared according to an embodiment of the present invention.
4 is a graph showing the charge/discharge cycle life of lithium secondary batteries of Examples 1 to 4 manufactured according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be implemented in various different forms, and therefore is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, bonded)" with another part, it is not only "directly connected", but also "indirectly connected" with another member in the middle. "Including the case. In addition, when a part "includes" a certain component, it means that other components may be further provided, rather than excluding other components unless specifically stated to the contrary.

The terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

In the present invention, a high-capacity, high-power silicon alloy-based negative electrode active material suitable for wireless charging energy storage is to be manufactured using a liquid rapid solidification process and alloy design technology.

Until now, research on the manufacture of silicon alloy-based negative electrode active material using mechanical alloying method Ball Milling or Rapidly Solidification Process is ongoing, but manufacturing process parameters (ball milling time, powder particle size) Silicon alloy system that solves the problem of volume expansion of silicon materials by dispersing and depositing only the silicon phase in the matrix phase in a uniform and reproducible manner at a level of 100 nm or less due to difficulty in controlling the cooling rate of the molten metal) There is no research report on the anode active material, and the present invention seeks to solve this problem in the order of the following three methods.

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

Second, the manufacture of silicon-based amorphous alloys using the rapid solidification process (Rapidly Solidification Process).

Third, through the heat treatment of a silicon-based amorphous alloy, only the active metal is uniformly dispersed and precipitated in the matrix.

Through the above process, finally, a 100 nm-sized silicon phase is transferred to a matrix phase having a yield strength capable of withstanding the expansion stress of silicon particles due to intercalation of lithium ions during the charging/discharging cycle. By implementing a uniformly dispersed precipitated microstructure, it is intended to suppress particle micronization due to volume expansion and contraction of silicon particles caused by lithium ions intercalation and desorption reactions.

Specifically, an embodiment of the present invention comprises the steps of preparing a molten metal by mixing each metal or alloy of Si, M, Fe, and Cu in a ratio to become an alloy of a predetermined composition ratio and then melting it; Solidifying the molten metal by a liquid quenching solidification method to prepare a Si-based amorphous alloy having a Si-M-Fe-Cu composition of the predetermined composition ratio and in which Cu is forcibly dissolved in Fe; And heat-treating the Si-based amorphous alloy to prepare a negative active material for a lithium secondary battery having a microstructure in which a crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and precipitated on an inert metal amorphous matrix or on an inactive crystalline matrix. Including, wherein M is Al, Ti, W, Co, Cr, Ge, or a method for manufacturing a negative active material for a lithium secondary battery for producing a negative active material for a lithium secondary battery containing at least one metal element selected from the group consisting of Ca Provides.

In an embodiment of the present invention, the anode active material for a lithium secondary battery is Si 45 at% or more and less than 60 at%, added metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at%, and Cu 0.1 at% To 5 at%.

Another embodiment of the present invention comprises Si 45 at% or more and less than 60 at%, added metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at%, and the M is an active metal having a size of 100 nm or less on an inert metal amorphous matrix or on an inactive crystalline matrix, including Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. It provides an anode active material for a lithium secondary battery having a microstructure in which the Si phase is uniformly dispersed and precipitated.

In an embodiment of the present invention, the negative active material comprises 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. It may be a negative electrode active material for a lithium secondary battery.

In an embodiment of the present invention, the active metal crystalline Si phase is the inert metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly dissolved by a liquid quench solidification method. It may be a negative active material for a lithium secondary battery, characterized in that uniformly dispersed and precipitated on the crystalline matrix.

Another embodiment 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 includes 75 wt% to 92 wt% of a negative electrode active material, and 1 wt% to a conductive material. 10 wt% and 7 wt% to 15 wt% of a binder, and the anode active material is a crystalline Si phase, a microstructure active metal having a size of 100 nm or less uniformly dispersed and precipitated on an inert metal amorphous matrix or an inert crystalline matrix. It provides a negative electrode for a lithium secondary battery comprising a.

In an embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at %, and M may be a negative electrode for a lithium secondary battery, characterized in that it contains Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

In an embodiment of the present invention, the negative electrode active material further comprises 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. It may be a negative electrode for a lithium secondary battery.

In an embodiment of the present invention, the active metal crystalline Si phase is the inert metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly dissolved by a liquid quench solidification method. It may be a negative electrode for a lithium secondary battery, characterized in that uniformly dispersed and precipitated on the crystalline matrix.

In another embodiment of the present invention, in a lithium secondary battery including 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, and the negative electrode The active material layer includes 75 wt% to 92 wt% of an anode active material, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder, and the anode active material is on an inert metal amorphous matrix or an inert crystalline matrix. It provides a lithium secondary battery comprising a crystalline Si phase which is a microstructured active metal having a size of 100 nm or less uniformly dispersed and precipitated.

In an embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at %, and M may be a lithium secondary battery comprising Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

In an exemplary embodiment of the present invention, the negative electrode active material comprises 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. It may be a secondary battery.

In an embodiment of the present invention, the active metal crystalline Si phase is the inert metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly dissolved by a liquid quench solidification method. It may be a lithium secondary battery characterized in that uniform dispersion and precipitation on the crystalline matrix.

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

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

Referring to FIG. 1, the present invention is a step (S10) of preparing a molten metal by mixing metals or alloys of Si, added metals M, Fe, and Cu in a ratio to become an alloy of a predetermined composition ratio, and melting the Solidifying a molten metal by a liquid quenching solidification method to prepare a Si-based amorphous alloy having a Si-M-Fe-Cu composition of the predetermined composition ratio and in which Cu is forcibly dissolved in Fe (S20) and heat treatment of the Si-based amorphous alloy , Manufacturing a negative active material for a lithium secondary battery having a microstructure in which a crystalline Si phase, an active metal having a size of 100 nm or less, is uniformly dispersed and precipitated on an inert metal amorphous matrix or an inactive crystalline matrix, wherein M is It provides a method of manufacturing a negative electrode active material for a lithium secondary battery for preparing a negative electrode active material for a lithium secondary battery containing at least one metal element selected from the group consisting of Al and Ti, W, Co, Cr, Ge, or Ca.

The negative electrode active material for a lithium secondary battery may include Si 45 at% or more and 60 at% or less, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at%, and Cu 0.1 at% to 5 at% have.

The Si phase constituting the negative electrode active material is a mixture of an inert metal amorphous matrix phase or a Si phase in an inert crystalline matrix phase and an active metal crystalline Si phase. Since the active metal crystalline Si phase can reversibly react with lithium ions, it is directly related to the capacity of the negative electrode active material, and the inert metal amorphous matrix phase or the inactive crystalline matrix phase forms a structure that does not react with lithium ions while forming a structure that does not react with lithium ions. It can play a role in suppressing volume expansion. The crystalline Si phase, which is the active metal, may be uniformly dispersed and precipitated in the inert metal amorphous matrix phase or the inactive crystalline matrix phase.

In the negative electrode active material for a lithium secondary battery, when the negative electrode active material is used as a negative electrode of a lithium secondary battery, Si may participate in the occlusion and release of lithium ions. Therefore, the amount of Si contained 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, as more Si is included in the alloy, the capacity of the negative electrode active material may be improved, but life characteristics may be slightly lowered. Therefore, in the negative active material of the present invention, the content of Si in the negative active material is preferably 45 at% or more and less than 60 at% in order to improve the life characteristics rather than the capacity. When the content of Si is less than 45 at%, it is not preferable because it can exhibit an excessively small capacity to realize capacity as a negative electrode active material for a lithium secondary battery. When the content of Si is more than 60 at%, it becomes crystalline and Si The amorphous alloy is not generated, or the content of components other than Si constituting the inactive metal amorphous matrix phase or the inactive crystalline matrix phase is small, so that it may be difficult to improve the lifespan of the negative electrode active material for a lithium secondary battery, which is not preferable.

In general, when Cu and Fe are solid at room temperature, it is difficult to dissolve in Si. However, when a manufacturing method such as a liquid quenching solidification method such as melt spinning is used, Cu can be forcibly dissolved in Si. Forcibly dissolved Cu tends to be separated from Fe, and this tendency causes a copper clustering phenomenon. Active Si may be uniformly dispersed and precipitated in the portion where the Cu clustering phenomenon occurs, and due to this phenomenon, the anode active material of the present invention is an active metal uniformly dispersed and precipitated on an inert metal amorphous matrix or an inert crystalline matrix. The phosphorus crystalline Si phase may include a microstructure in which uniformly dispersed and precipitated.

The content of Cu is preferably 0.1 at% to 5 at% when the Si content is 45 at% or more and less than 60 at%. This is because when the content of Cu is less than 0.1 at%, the above-described copper clustering phenomenon is insignificant and dispersion precipitation of active silicon nanoparticles may not occur, which is not preferable. In addition, when the content of Cu is more than 5 at%, it is not preferable that Cu may act as an impurity, so the content of Cu is preferably 0.1 at% to 5 at%.

In the present invention, since Fe contained on the inert metal amorphous matrix or the inactive crystalline matrix can serve to induce copper clustering, the capacity characteristics can be improved.

As described above, the inert metal amorphous matrix phase or the inert crystalline matrix phase includes a Si-based alloy including Si, an additive metal M, Fe, and Cu, wherein the additive metal M is Al, Ti, W, Co , Cr, Ge, or Ca containing at least one metal element selected from the group consisting of, the Ti, W, Co, Cr, Ge, or 0.1 to 5 at least one metal element selected from the group consisting of Ca May contain at%.

The particle diameter of the active metal Si phase uniformly dispersed and precipitated on the inert metal amorphous matrix and the crystalline matrix may be 1 nm to 100 nm.

Hereinafter, a negative electrode for a lithium secondary battery will be described.

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 includes 75 wt% to 92 wt% of a negative electrode active material and 1 wt% of a conductive material. 10 wt% and 7 wt% to 15 wt% of a binder, and the anode active material is a crystalline Si phase, a microstructure active metal having a size of 100 nm or less uniformly dispersed and precipitated on an inert metal amorphous matrix or an inert crystalline matrix. It characterized in that it includes.

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 copper, gold, nickel, stainless steel, or titanium, but is not limited thereto.

In an embodiment of the present invention, the negative electrode active material may include a crystalline Si phase, which is a microstructure active metal having a size of 100 nm or less uniformly dispersed and precipitated on an inert metal amorphous matrix or an inactive crystalline matrix. The negative electrode active material contains Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at%, and Cu 0.1 at% to 5 at%, and M is Al And, it may contain at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca. At this time, at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca may be included in an amount of 0.1 at% to 5 at%.

Since the crystalline Si phase, which is an active metal constituting the negative electrode active material, can react reversibly with lithium ions, it is directly related to the capacity of the negative electrode active material, and the inert metal amorphous matrix phase or the inactive crystalline matrix phase forms a structure that does not react with lithium ions. While it can play a role of suppressing the volume expansion of the negative electrode active material. The crystalline Si phase as the active metal may be uniformly dispersed and precipitated in the inert metal amorphous matrix phase or the inactive crystalline matrix phase.

In the negative electrode active material for a lithium secondary battery, when the negative electrode active material is used as a negative electrode of a lithium secondary battery, Si may participate in the occlusion and release of lithium ions. Therefore, the amount of Si contained 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, as more Si is included in the alloy, the capacity of the negative electrode active material may be improved, but life characteristics may be slightly lowered. Therefore, in the negative active material of the present invention, the content of Si in the negative active material is preferably 45 at% or more and less than 60 at% in order to improve the life characteristics rather than the capacity. When the content of Si is less than 45 at%, it is not preferable because it can exhibit an excessively small capacity to realize capacity as an anode active material for a lithium secondary battery, and when the content of Si is more than 60 at%, an inert matrix is formed. Since the content of components other than silicon Si is small, it may be difficult to improve the lifespan of the negative electrode active material for a lithium secondary battery, which is not preferable.

In general, when Cu and Fe are solid at room temperature, it is difficult to dissolve in Si. However, when a manufacturing method such as a liquid quenching solidification method such as melt spinning is used, Cu can be forcibly dissolved in Si. Forcibly dissolved Cu tends to be separated from Fe, and this tendency causes a copper clustering phenomenon. Active silicon nanoparticles may be uniformly dispersed and precipitated in the portion where Cu clustering appears, and due to this phenomenon, the anode active material of the present invention is uniformly dispersed and precipitated in an inert metal amorphous matrix or an inert crystalline matrix. It may comprise a crystalline Si phase that is a metal.

The content of Cu is preferably 0.1 at% to 5 at% when the Si content is 45 at% or more and less than 60 at%. This is because when the content of Cu is less than 0.1 at%, the above-described copper clustering phenomenon is insignificant and dispersion precipitation of active silicon nanoparticles may not occur, which is not preferable. In addition, when the Cu content exceeds 5 at%, it is not preferable that Cu may act as an impurity, and thus the content of Cu is preferably 0.1 at% to 5 at%.

In the present invention, since Fe contained on the inert metal amorphous matrix or the inactive crystalline matrix can serve to induce copper clustering, the capacity characteristics can be improved.

As described above, the inert metal amorphous matrix phase or the inert crystalline matrix phase may include Si, additive metals M, Fe, and Cu, and the additive metal M is Al and Ti, W, Co, Cr, Ge, and Contains one or more metal elements selected from the group consisting of Ca, and the one or more metal elements selected from the group consisting of Ti, W, Co, Cr, Ge, and Ca include 0.1 at% to 5 at%, capacity characteristics or It can be used as an ingredient to improve life characteristics.

The active metal crystalline Si phase uniformly dispersed and precipitated on the inactive metal amorphous matrix or the inactive crystalline matrix may have a size of 1 nm to 100 nm.

The anode active material layer may include 75 wt% to 92 wt% of an anode active material, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder.

The conductive material is used to impart conductivity, and in the lithium secondary battery to be configured, any material may be used as long as it does not cause chemical change and is an electron conductive material. Specifically, any one or more of a conductive polymer material 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 derivative It 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 according to the use of the conductive material and thus improving the life characteristics is insignificant, and when the content of the conductive material is more than 5 wt%, the conductive material due to an increase in the specific surface area of the conductive material And it is not preferable because the reaction between the electrolyte may increase and the life characteristics may decrease. More specifically, the content of the conductive material may be preferably 1 wt% to 3 wt%.

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

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

Since the content of the conductive material is preferably 1 wt% to 10 wt%, and the binder content is preferably 7 wt% to 15 wt%, the content of the anode active material in the anode 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 copper, gold, nickel, stainless steel, or titanium, but is not limited thereto.

In an embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at %, and M may include Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

The Si phase constituting the negative electrode active material is a mixture of an inert metal amorphous matrix phase or a Si phase in an inert crystalline matrix phase and an active metal crystalline Si phase. Since the active metal crystalline Si phase can reversibly react with lithium ions, it is directly related to the capacity of the negative electrode active material, and the inert metal amorphous matrix phase or the inactive crystalline matrix phase forms a structure that does not react with lithium ions while forming a structure that does not react with lithium ions. It can play a role in suppressing volume expansion. The crystalline Si phase, which is the active metal, may be uniformly dispersed and precipitated in the inert metal amorphous matrix phase or the inactive crystalline matrix phase.

In the negative electrode active material for a lithium secondary battery, when the negative electrode active material is used as a negative electrode of a lithium secondary battery, Si may participate in the occlusion and release of lithium ions. Therefore, the amount of Si contained 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, as more Si is included in the alloy, the capacity of the negative electrode active material may be improved, but life characteristics may be slightly lowered. Therefore, in the negative active material of the present invention, the content of Si in the negative active material is preferably 45 at% or more and less than 60 at% in order to improve the life characteristics rather than the capacity. When the content of Si is less than 45 at%, it is not preferable because it can exhibit an excessively small capacity to realize capacity as a negative electrode active material for a lithium secondary battery, and when the content of Si is more than 60 at%, the inert metal amorphous Since the content of components other than Si constituting the matrix phase or the inactive crystalline matrix phase is small, it may be difficult to improve the lifespan of the anode active material for a lithium secondary battery, which is not preferable.

In general, when Cu and Fe are solid at room temperature, it is difficult to dissolve in Si. However, when a manufacturing method such as a liquid quenching solidification method such as melt spinning is used, Cu can be forcibly dissolved in Si. Forcibly dissolved Cu tends to be separated from Fe, and this tendency causes a copper clustering phenomenon. Active Si may be uniformly dispersed and precipitated in the portion where the Cu clustering phenomenon occurs, and due to this phenomenon, the anode active material of the present invention is an active metal uniformly dispersed and precipitated on an inert metal amorphous matrix or an inert crystalline matrix. The phosphorus crystalline Si phase may include a microstructure in which uniformly dispersed and precipitated.

The content of Cu is preferably 0.1 at% to 5 at% when the Si content is 45 at% or more and less than 60 at%. This is because when the content of Cu is less than 0.1 at%, the above-described copper clustering phenomenon is insignificant and dispersion precipitation of active silicon nanoparticles may not occur, which is not preferable. In addition, when the content of Cu is more than 5 at%, it is not preferable that Cu may act as an impurity, so the content of Cu is preferably 0.1 at% to 5 at%.

In the present invention, since Fe contained on the inert metal amorphous matrix or the inactive crystalline matrix can serve to induce copper clustering, the capacity characteristics can be improved.

As described above, the inert metal amorphous matrix phase or the inert crystalline matrix phase includes a Si-based alloy including Si, an additive metal M, Fe, and Cu, wherein the additive metal M is Al, Ti, W, Co , Cr, Ge, or Ca, containing at least one metal element selected from the group consisting of, the Ti, W, Co, Cr, Ge, or 0.1 to 5 at least one metal element selected from the group consisting of Ca It may contain at%, whereby it may be used as a component for improving capacity characteristics or life characteristics.

The particle diameter of the active metal crystalline Si phase uniformly dispersed and precipitated on the inactive metal amorphous matrix or the inactive crystalline matrix may be 1 nm to 100 nm.

In an embodiment of the present invention, the negative electrode active material layer may include 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.

The conductive material is used to impart conductivity, and in the lithium secondary battery to be configured, any material may be used as long as it does not cause chemical change and is an electron conductive material. Specifically, any one or more of a conductive polymer material 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 derivative It 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 according to the use of the conductive material and thus improving the life characteristics is insignificant, and when the content of the conductive material is more than 5 wt%, the conductive material due to an increase in the specific surface area of the conductive material And it is not preferable because the reaction between the electrolyte may increase and the life characteristics may decrease. More specifically, the content of the conductive material may be preferably 1 wt% to 3 wt%.

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

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

Since the content of the conductive material is preferably 1 wt% to 10 wt%, and the binder content is preferably 7 wt% to 15 wt%, the content of the anode active material in the anode 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 forms a positive electrode active material layer by mixing a positive electrode active material, a binder, and a conductive material in a solvent. After preparing the composition for use, the composition may be applied on a positive electrode current collector. Since such a method of manufacturing a positive electrode is widely known in the art, a detailed description thereof will be omitted herein.

The positive electrode active material may include a material capable of reversibly inserting and desorbing lithium ions. Specifically, the positive electrode 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 attach the positive electrode active material particles well to each other and the positive electrode active material to the positive electrode current collector, and specifically, polyimide, polyamideimide, polybenzimidazole, polyvinyl alcohol, carboxymethylcellulose, hydride Roxypropylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, Any one or more of styrene-butadiene, acrylated styrene-butadiene, and epoxy resin may be used, but the present invention is not limited thereto.

The conductive material is used to impart conductivity, and in the lithium secondary battery to be configured, any material may be used as long as it does not cause chemical change and is an electron conductive material. Specifically, any one or more of a conductive polymer material 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 derivative It can be used, but is not limited thereto.

The solvent may be N-methylpyrrolidone or n-hexane, 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 aluminum, nickel, or an alloy thereof, but is not limited thereto.

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), ethyl methyl 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.

In addition, the lithium salt is 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 It may include one or two or more selected from the group consisting of LiB(C ₂ O ₄ ) ₂ . These electrolyte salts may be used alone or in combination of two or more.

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

Hereinafter, preparation examples and experimental examples of the present invention will be described. However, these Preparation Examples and Experimental Examples are for explaining the configuration and effects of the present invention in more detail, and it should be noted that the scope of the present invention is not limited thereto.

-Experimental example-

division Alloy composition decision
rescue Amorphous alloy
Heat treatment condition division Si(at%) Al(at%) Fe(at%) Cu(at%) Crystal phase Temperature, time Example 1 50 32 17 One Amorphous Pristine Example 2 50 32 17 One Amorphous + crystalline 450℃, 1hr Example 3 50 32 17 One Amorphous + crystalline 550℃, 1hr Example 4 50 32 17 One Crystalline 700℃, 1hr Comparative Example 1 60 26 14 Crystalline+Amorphous Pristine

Under the conditions of [Table 1], Examples 1 to 4 according to an embodiment of the present invention and Comparative Example 1 without heat treatment were prepared.

[Example 1]

A single-roll liquid quench solidification method in which an alloy containing Si, Al, Fe, and Cu is melted by an arc melting method to prepare a melt, and then the melt is sprayed onto a copper roll rotating at a speed of 40 m/s.Si ₅₀ Al ₃₂ Fe A Si-based amorphous alloy having a composition of ₁₇ Cu ₁ and in which Cu is forcibly dissolved in Fe was prepared.

A negative electrode active material powder having an amorphous crystal phase formed by mixing 200 g of zirconium balls, 5 g of the Si-based amorphous alloy, and n-Hexane and pulverizing for 15 minutes using a paint shaker After preparing a coin-shaped electrode plate, a mixture of negative electrode active material powder, Ketjen Black as a conductive material, and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, and then in an Ar atmosphere at 400°C. Heat treatment was performed for 1 hour to prepare a negative electrode (Example 1).

[Example 2]

A single-roll liquid quench solidification method in which an alloy containing Si, Al, Fe, and Cu is melted by an arc melting method to prepare a melt, and then the melt is sprayed onto a copper roll rotating at a speed of 40 m/s.Si ₅₀ Al ₃₂ Fe A Si-based amorphous alloy having a composition of ₁₇ Cu ₁ and in which Cu is forcibly dissolved in Fe was prepared.

Microstructure in which the Si-based amorphous alloy is heat-treated at 450°C in an inert gas atmosphere for 1 hour to uniformly disperse and precipitate a crystalline Si phase, an active metal having a size of 100 nm or less, on an inert metal amorphous matrix or an inert crystalline matrix And a negative active material for a lithium secondary battery having a crystalline phase in which amorphous and crystalline are mixed was prepared.

After mixing 200 g of zirconium balls, 5 g of the negative electrode active material, and n-Hexane, the negative electrode active material powder formed by pulverizing for 15 minutes using a paint shaker is used to form a coin-shaped electrode plate. Prepared, the negative electrode active material powder, a mixture of Ketjen Black as a conductive material and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, and then heat-treated in an Ar atmosphere at 400° C. for 1 hour to perform a negative electrode (Example 2) was prepared.

[Example 3]

An alloy containing Si, Al, Fe, and Cu is melted by an arc melting method to prepare a melt, and then the melt is sprayed on a copper roll rotating at a speed of 40 m/s.Si ₅₀ Al ₃₂ Fe ₁₇ A Si-based amorphous alloy having a composition of Cu ₁ and in which Cu is forcibly dissolved in Fe was prepared.

Microstructure in which the Si-based amorphous alloy is heat-treated at 550°C in an inert gas atmosphere for 1 hour to uniformly disperse and precipitate a crystalline Si phase, an active metal having a size of 100 nm or less, on an inert metal amorphous matrix or an inert crystalline matrix And a negative active material for a lithium secondary battery having a crystalline phase in which amorphous and crystalline are mixed was prepared.

A negative electrode active material powder having an amorphous crystal phase formed by mixing 200 g of zirconium balls, 5 g of the negative electrode active material, and n-hexane for 15 minutes using a paint shaker. After preparing a shaped electrode plate, a mixture of the negative electrode active material powder, Ketjen Black as a conductive material, and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, and then heat-treated at 400°C for 1 hour in an Ar atmosphere. A negative electrode (Example 3) was prepared.

[Example 4]

A single-roll liquid quench solidification method in which an alloy containing Si, Al, Fe, and Cu is melted by an arc melting method to prepare a melt, and then the melt is sprayed onto a copper roll rotating at a speed of 40 m/s.Si ₅₀ Al ₃₂ Fe A Si-based amorphous alloy having a composition of ₁₇ Cu ₁ and in which Cu is forcibly dissolved in Fe was prepared.

Microstructure in which the Si-based amorphous alloy is heat-treated at 700° C. in an inert gas atmosphere for 1 hour to uniformly disperse and precipitate a crystalline Si phase, an active metal having a size of 100 nm or less, on an inert metal amorphous matrix or an inert crystalline matrix And was prepared a negative active material for a lithium secondary battery having a crystalline crystal phase.

After mixing 200 g of zirconium balls, 5 g of the negative electrode active material, and n-Hexane, the negative electrode active material powder formed by pulverizing for 15 minutes using a paint shaker is used to form a coin-shaped electrode plate. Prepared, the negative electrode active material powder, a mixture of Ketjen Black as a conductive material and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, and then heat-treated in an Ar atmosphere at 400° C. for 1 hour to obtain a negative electrode (Experimental Example 4) was prepared.

[Comparative Example 1]

And melting the alloy including Si, Al and Fe in such an arc melting method to prepare a melt of the following, danrol liquid quenching solidification of the melt jet to a copper roll rotating at 40 m / s speed, Si ₆₀ Al ₂₆ Fe ₁₄ composition Eggplant was prepared a Si-based amorphous alloy in which crystalline and amorphous were mixed.

A negative electrode active material powder formed by mixing 200 g of zirconium balls, 5 g of the Si-based amorphous alloy, and n-hexane for 15 minutes using a paint shaker. An electrode plate was prepared, and a mixture of the negative electrode active material powder, Ketjen Black as a conductive material, and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, and then heat-treated in an Ar atmosphere at 400° C. for 1 hour to obtain a negative electrode ( Comparative Example 1) was prepared.

2 is a TEM photograph of the negative active material for a lithium secondary battery of Example 3 prepared according to an embodiment of the present invention, and FIG. 3 is a TEM photograph of the negative active material for a lithium secondary battery of Example 1 prepared according to an embodiment of the present invention. It is a diagram showing a diffraction pattern showing crystallinity.

2 and 3, as in Examples 1 and 3, it was confirmed that the negative electrode active material of the present invention has an inert metal amorphous matrix phase or an inert crystalline matrix phase 10, and in particular, heat treatment was performed. In Example 3, as shown in FIG. 2, it was confirmed that the crystalline Si phase 20, which is an active metal having a size of 100 nm or less, has a microstructure uniformly dispersed and precipitated on the inert metal amorphous matrix phase or the inactive crystalline matrix phase 10.

Charge capacity, discharge capacity, and initial coulomb 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 4 (ICE: initial discharge capacity The results for the value divided by) are shown in the following [Table 2].

division Alloy composition decision
rescue Amorphous alloy
Heat treatment conditions Electrode characteristic evaluation result division Si
(at%) Al
(at%) Fe
(at%) Cu
(at%) Crystal phase Temperature, time Initial charge
(mAh/g) Early
Discharge
(mAh/g) Early
Coolung
efficiency(%) Volume
Retention rate
(30cy.%) Example 1 50 32 17 One Amorphous Pristine 223.5 106.3 47.5 42.8 Example 2 50 32 17 One Amorphous + crystalline 450℃, 1hr 387.8 255.37 65.8 65.2 Example 3 50 32 17 One Amorphous + crystalline 550℃, 1hr 996.9 848.8 85.1 82.8 Example 4 50 32 17 One Crystalline 700℃, 1hr 996.7 855.0 85.7 76.0 Comparative Example 1 60 26 14 Crystalline+Amorphous Pristine 1629.0 1470.5 90.2 55.0

4 is a graph showing charge/discharge cycle life of lithium secondary batteries of Examples 1 to 4 manufactured according to an embodiment of the present invention.

Referring to Table 2 and Figure 4, the implementation of the present invention having a crystalline and amorphous crystal structure by heat-treating a Si-based amorphous alloy in which Cu is forcibly dissolved in Fe prepared by the liquid quenching solidification method in a temperature range of 480°C to 750°C. In the case of the negative electrode made of the negative electrode active material of Examples 3 and 4, the initial coulombic efficiency (ICE) was high at 85.1% and 85.7%, and the retention rate after 30 cycles was also high at 82.8% and 76%. appear.

On the other hand, in the case of Experimental Examples 1 and 2, in which heat treatment was performed at less than 480°C, the initial coulombic efficiency (ICE) was low at 47.5% and 65.8%. The retention rate after 30 cycles was also low at 42.8% and 65.2%. In particular, in the case of Example 1 in which the heat treatment was not performed, the initial coulomb efficiency was not formed on the inert metal amorphous matrix phase or the inert crystalline matrix phase 10, which is an active metal having a size of 100 nm or less. ICE: Initial Coulombic Efficiency) was as low as 47.5%, and the retention rate after 30 cycles was also as low as 42.8%.

In addition, in the case of the negative electrode of Comparative Example 1 prepared without performing heat treatment of a Si-based alloy having a composition of Si ₆₀ Al ₂₆ Fe ₁₄ having a crystalline phase in which a crystalline and amorphous mixture is mixed, the initial coulomb efficiency ( ICE: Initial Coulombic Efficiency) was high at 90.2%, but it was confirmed that the retention rate after 30 cycles significantly decreased to 55.0%.

In the embodiment of the present invention, in melt spinning, which is a liquid quench solidification method, an amorphous alloy can be produced reproducibly in the range of 30 m/s to 60 m/s in the rotational linear speed of the copper wheel, and more preferably 40 m/s. It is possible to produce amorphous alloys reproducibly at speed.

If heat treatment is performed at a constant temperature (480°C to 750°C) after manufacturing an amorphous alloy, a negative electrode active material in a form in which reproducible active silicon particles are uniformly dispersed and precipitated in nano size in an inert matrix can be prepared. It can be determined that silver can have excellent life characteristics in which the capacity is maintained even after 30 cycles.

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that it can be easily modified into 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 illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later, and all changes or modified forms derived from the meaning and scope of the claims and the concept of equivalents thereof should be construed as being included in the scope of the present invention.

Claims (13)

Mixing the metals or alloys of Si, the additive metals M, Fe, and Cu in a ratio to become an alloy having a predetermined composition ratio, and then melting them to prepare a molten metal;
The molten metal is solidified by a liquid quenching solidification method in which the molten metal is sprayed onto a copper roll rotating at a speed in the range of 30 m/s to 60 m/s, and has a Si-M-Fe-Cu composition of the preset composition ratio, and Cu is forcibly dissolved in Fe. Preparing a Si-based amorphous alloy; And
The Si-based amorphous alloy is heat-treated at a temperature ranging from 480°C to 750°C, and a microstructure in which a crystalline Si phase, an active metal having a size of 100 nm or less, is uniformly dispersed and precipitated on an inert metal amorphous matrix or an inactive crystalline matrix by Cu clustering. Including; preparing a negative active material for a lithium secondary battery having,
The M is characterized in that Al,
The negative electrode active material for a lithium secondary battery contains 45 at% or more and less than 60 at% of Si, 25 at% to 44.9 at% of added metal M, 10 at% to 25 at% Fe, and 0.1 at% to 5 at% Cu Method for producing a negative active material for a lithium secondary battery, characterized in that. delete Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at%,
The M is characterized in that Al,
It is characterized in that it has a microstructure in which a crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and precipitated on an inert metal amorphous matrix or an inactive crystalline matrix,
The crystalline Si phase as the active metal is 480° C. of a Si-based amorphous alloy in which Cu is forcibly dissolved, prepared by a liquid quench solidification method in which molten metal is sprayed on a copper roll rotating at a speed in the range of 30 m/s to 60 m/s. A negative electrode active material for a lithium secondary battery, characterized in that uniformly dispersed and precipitated on the inert metal amorphous matrix or on the inactive crystalline matrix by copper clustering through heat treatment in a temperature range of ~750°C. delete delete 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 a negative electrode active material, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder,
The negative electrode active material is characterized in that it comprises a crystalline Si phase, which is a microstructured active metal having a size of 100 nm or less uniformly dispersed and precipitated on an inert metal amorphous matrix or an inert crystalline matrix,
The negative electrode active material, Si 45 at% or more and less than 60 at%, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at% and Cu 0.1 at% to 5 at%,
The M is characterized in that Al,
The crystalline Si phase as the active metal is 480° C. of a Si-based amorphous alloy in which Cu is forcibly dissolved, prepared by a liquid quench solidification method in which molten metal is sprayed on a copper roll rotating at a speed in the range of 30 m/s to 60 m/s A negative electrode for a lithium secondary battery, characterized in that uniformly dispersed and precipitated on the inert metal amorphous matrix or on the inactive crystalline matrix by copper clustering through heat treatment in a temperature range of ~750°C. delete delete delete In the 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 a negative electrode active material, 1 wt% to 10 wt% of a conductive material, and 7 wt% to 15 wt% of a binder,
The negative electrode active material is characterized in that it comprises a crystalline Si phase, which is a microstructured active metal having a size of 100 nm or less uniformly dispersed and precipitated on an inert metal amorphous matrix or on an inert crystalline matrix,
The negative electrode active material includes Si 45 at% or more and 60 at% or less, additive metal M 25 at% to 44.9 at%, Fe 10 at% to 25 at%, and Cu 0.1 at% to 5 at%, wherein M is Al Characterized by being,
The crystalline Si phase as the active metal is 480° C. of a Si-based amorphous alloy in which Cu is forcibly dissolved, prepared by a liquid quench solidification method in which molten metal is sprayed on a copper roll rotating at a speed in the range of 30 m/s to 60 m/s. A lithium secondary battery, characterized in that uniformly dispersed and precipitated on the inert metal amorphous matrix or on the inert crystalline matrix by copper clustering through heat treatment in a temperature range of ~750°C. delete delete delete

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