WO2024090739A1 - Anode active material for lithium secondary battery, method of producing same, and lithium secondary battery comprising same - Google Patents

Abstract

The present invention provides a method for producing an anode active material for a lithium secondary battery, an anode active material for a lithium secondary battery produced by the method, an anode comprising the anode active material for a lithium secondary battery, and a lithium secondary battery comprising the anode, wherein according to the method, a Si-based amorphous alloy with a Si-M-Fe-Mn composition is subjected to heat treatment, thereby allowing the anode active material to have a microstructure in which a crystalline Si phase, an active metal with a diameter of 100 nm or less, is uniformly dispersed and deposited in an inert metal crystalline matrix.

Description

Negative active material for lithium secondary battery, manufacturing method thereof, and lithium secondary battery containing the same

The present invention relates to a method of manufacturing a negative electrode active material for a lithium secondary battery, a negative electrode active material for a lithium secondary battery, a negative electrode for a lithium secondary battery, and a lithium secondary battery containing the same. More specifically, active metals with a diameter of 100 nm or less uniformly dispersed and precipitated in an inert metal crystalline matrix phase containing silicon (Si), additive metal (M), iron (Fe), and manganese (Mn). It relates to a method of manufacturing a negative electrode active material for lithium secondary batteries having a microstructure in which a crystalline silicon phase, which is a metal, is uniformly dispersed and precipitated, a negative electrode active material for lithium secondary batteries manufactured therefrom, a negative electrode for lithium secondary batteries, and a lithium secondary battery containing the same.

Recently, as the wireless charging function using wireless power transmission technology has begun to be applied to smartphones around the world, wireless charging technology that can charge the battery anytime, anywhere without being connected to power by a cable is being combined with IT. Accordingly, wireless charging technology is expected to be widely applied not only to home appliances such as televisions and refrigerators and electric vehicles, but also to wearable devices that can be worn or attached to the body.

According to this industrial environment, the scope of application of lithium secondary batteries is gradually expanding as an energy storage medium applied to portable information devices such as smartphones, laptops, and digital cameras, small home appliances and medical devices, electric vehicles, and large-capacity power storage systems. , performance improvements such as high capacity, high output, long life, and high safety are required.

Lithium secondary batteries are manufactured by using materials capable of intercalation and deintercalation of lithium ions as the cathode and anode, installing a porous separator between the electrodes, and then injecting an electrolyte solution. In general, electricity is generated or consumed through redox reactions caused by insertion and desorption of lithium ions in the cathode and anode.

The improvement in the performance of lithium secondary batteries can be said to be due to the technological development of four core materials: anode, cathode, electrolyte, and separator, which have a decisive influence on various characteristics such as capacity and output. The capacity of the positive electrode and negative electrode active materials currently used in lithium secondary batteries is already close to the theoretical capacity. Accordingly, the need for new anode active materials is increasing to implement high-capacity and high-output batteries suitable for wireless charging energy storage.

Typically, graphite, a negative electrode active material widely used in lithium secondary batteries, has a layered structure and is very useful for insertion and desorption of lithium ions. The theoretical capacity of graphite is 372 mAh/g, and as demand for high-capacity lithium batteries has recently increased, new electrodes that can replace graphite are required. Accordingly, research is actively underway to commercialize high-capacity negative electrode active materials that form electrochemical alloys with lithium ions, such as silicon (Si), tin (Sn), antimony (Sb), and aluminum (Al). It is becoming.

Meanwhile, when silicon (Si) is used as a negative electrode active material, there is a problem in that cracks or breaks in silicon particles occur due to volume changes during the process of insertion and desorption of lithium ions through repeated charging and discharging. Accordingly, the surface area of the negative electrode active material particles increases, and the film layer made of decomposition products of the non-aqueous electrolyte is formed thickly on the surface of the negative electrode active material, resulting in an increase in interfacial resistance between the negative electrode active material and the non-aqueous electrolyte, leading to a problem of deterioration of charge and discharge life characteristics. To solve this problem, various methods have been attempted, such as controlling the shape and particle size of the silicon (Si) material, alloying, oxidizing, and complexing with carbon materials, but the fundamental problem has not yet been solved.

Recent research has focused on chemical composition, morphology control, manufacturing process, and electrode structure including binder to suppress this volume change. However, in the case of the rapid solidification method, which is generally a manufacturing process for alloys capable of mass production, there is serious dispersion depending on the effect on the microstructure of the difference in cooling rate between the roll contact surface and the opposite surface, and the dispersion due to scale-up is also significant, making the material practical. It did not reach . Accordingly, design of alloy composition considering the process is required, and process design that reflects the mass production scale is required.

<Prior art literature>

(Registered Patent 1) KR 10-1385602 B1

One embodiment of the present invention to solve the problems of the prior art described above is an inert metal crystalline matrix phase containing silicon (Si), aluminum (Al), copper (Cu), iron (Fe), and manganese (Mn). A method of manufacturing a negative electrode active material for a lithium secondary battery having a microstructure in which a crystalline silicon phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated, a negative electrode active material for a lithium secondary battery produced by the manufacturing method, and a negative electrode active material for a lithium secondary battery containing the negative electrode active material. The problem to be solved is to provide a negative electrode and a lithium secondary battery including the negative electrode.

In addition, the technical problem to be achieved by the present invention is to improve the decline in life characteristics due to volume change when using conventional Si as a negative electrode active material, while ensuring uniform size of the Si precipitate phase and reproducibility of charge/discharge capacity and cycle life. Another purpose is to provide a secured manufacturing method of a negative electrode active material for a lithium secondary battery, a negative electrode active material for a lithium secondary battery manufactured by the manufacturing method, a negative electrode for a lithium secondary battery containing the negative electrode active material, and a lithium secondary battery containing the negative electrode.

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 can be clearly understood by those skilled in the art from the description below. There will be.

One embodiment of the present invention for achieving the above-described object of the present invention provides a negative electrode active material for a lithium secondary battery.

The negative electrode active material for lithium secondary batteries according to an embodiment of the present invention is,

For the total 100 at%, it includes 45 at% to less than 60 at% of Si, 25 at% or more of added metal M, 1 at% to 20 at% of Fe, and 20 at% or less of Mn, and the above additions Metal M includes Al and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. It may be a negative electrode active material for a lithium secondary battery that further contains an element and is characterized by comprising a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.

In addition, according to an embodiment of the present invention, with respect to 100 at% of the negative electrode active material, the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less. There may be negative electrode active material for lithium secondary batteries.

In addition, according to one embodiment of the present invention, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix is heated by differential scanning calorimetry (DSC). When thermal analysis was performed at a rate of 10°C/min, a negative electrode active material for a lithium secondary battery was formed by heat treatment of a Si-based amorphous alloy with an exothermic peak due to Cu clustering in the temperature range of 300°C to 450°C. There may be.

In addition, according to one embodiment of the present invention, the inactive matrix phase of the negative electrode active material is any one selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases. There may be a negative electrode active material for a lithium secondary battery characterized by containing the above phases.

In order to achieve the above technical problem, another embodiment of the present invention provides a negative electrode for a lithium secondary battery.

The negative electrode for a lithium secondary battery according to an embodiment of the present invention,

It includes a negative electrode current collector and a negative electrode active material layer formed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer contains 75 wt% to 92 wt% of the negative electrode active material and 1 wt% to 10 wt of the conductive material, based on 100 wt%. %, and a binder of 7 wt% to 15 wt%, wherein the negative electrode active material includes 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, and 1 at% based on 100 at% of the negative electrode active material. Containing % or more and 20 at% or less of Fe, and 20 at% or less of Mn, wherein the added metal M includes Al and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. It may further include an element, and the negative electrode active material may be a negative electrode for a lithium secondary battery, characterized in that it includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.

In addition, according to an embodiment of the present invention, with respect to 100 at% of the negative electrode active material, the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less. There may be a negative electrode for a lithium secondary battery.

In addition, according to one embodiment of the present invention, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix is heated by differential scanning calorimetry (DSC). When thermal analysis was performed at a rate of 10°C/min, there was a negative electrode for a lithium secondary battery, which was formed by heat treatment of a Si-based amorphous alloy with an exothermic peak due to Cu clustering in the temperature range of 300°C to 450°C. You can.

In addition, according to one embodiment of the present invention, the inactive matrix phase of the negative electrode active material is any one selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases. There may be a negative electrode for a lithium secondary battery characterized by containing the above phases.

In order to achieve the above technical problem, another embodiment of the present invention provides a lithium secondary battery.

The lithium secondary battery according to an embodiment of the present invention,

In the 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 active material layer is 100 wt%. , containing 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, and the negative electrode active material is 45 at% based on 100 at% of the negative electrode active material. It contains more than 60 at% of Si, more than 25 at% of added metal M, more than 1 at% but less than 20 at% of Fe, and less than 20 at% of Mn, and the added metal M includes Al and Cu. ; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. It may further include an element, and the negative electrode active material may be a lithium secondary battery characterized in that it includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.

In addition, according to an embodiment of the present invention, with respect to 100 at% of the negative electrode active material, the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less. There may be a lithium secondary battery.

In addition, according to one embodiment of the present invention, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix is heated by differential scanning calorimetry (DSC). When thermal analysis was performed at a rate of 10°C/min, there may be a lithium secondary battery formed by heat treatment of a Si-based amorphous alloy with an exothermic peak due to Cu clustering in the temperature range of 300°C to 450°C. there is.

In addition, according to one embodiment of the present invention, the inactive matrix phase of the negative electrode active material is any one selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases. There may be a lithium secondary battery characterized by containing the above phases.

In order to achieve the above technical problem, another embodiment of the present invention provides a method for manufacturing a negative electrode active material for a lithium secondary battery.

The method for manufacturing an anode active material for a lithium secondary battery according to an embodiment of the present invention,

Preparing metals or alloys of Si, additive metal M, Fe, and Mn; Preparing a Si-based amorphous alloy having a Si-M-Fe-Mn composition using the prepared metals or alloys of Si, additive metals M, Fe, and Mn; And heat-treating the Si-based amorphous alloy to produce a negative electrode active material for a lithium secondary battery comprising a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix. , the negative electrode active material is 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, 1 at% or more and 20 at% or less of Fe, and 20 at% or less, based on 100 at% of the negative electrode active material. of Mn, and the added metal M includes Al and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. It may be a method of manufacturing a negative electrode active material for a lithium secondary battery, characterized in that it further contains an element.

In addition, according to an embodiment of the present invention, the negative electrode active material for a lithium secondary battery contains 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, and 1 at%, based on 100 at% of the negative electrode active material. There may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which is characterized by containing 20 at% or less of Fe and 20 at% or less of Mn.

In addition, according to an embodiment of the present invention, the step of manufacturing a Si-based amorphous alloy having the Si-M-Fe-Mn composition is mixing the prepared metals or alloys of Si, additive metal M, Fe, and Mn. producing molten metal by melting it and then melting it; And there may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which includes the step of solidifying the molten metal by liquid rapid solidification to produce a Si-based amorphous alloy having the Si-M-Fe-Mn composition.

In addition, according to an embodiment of the present invention, the step of manufacturing the Si-based amorphous alloy having the Si-M-Fe-Mn composition includes ball milling, mechanical alloying, and gas atomizer method. There may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which is characterized in that it is performed by one or more methods selected from the group consisting of gas atomization and chemical vapor deposition.

Additionally, according to an embodiment of the present invention, there may be a method of manufacturing a negative electrode active material for a lithium secondary battery, wherein the heat treatment is performed in a temperature range of 400°C to 650°C.

In addition, according to an embodiment of the present invention, with respect to 100 at% of the negative electrode active material, the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less. There may be a method of manufacturing anode active material for lithium secondary batteries.

In addition, according to one embodiment of the present invention, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix is heated by differential scanning calorimetry (DSC). Manufacture of anode active material for lithium secondary batteries, which is formed by heat treatment of a Si-based amorphous alloy that exhibits an exothermic peak due to Cu clustering in the temperature range of 300℃ to 450℃ when thermal analysis is performed at a rate of 10℃/min. There may be a way.

In addition, according to one embodiment of the present invention, the inactive matrix phase of the negative electrode active material is any one selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases. There may be a method for manufacturing a negative electrode active material for a lithium secondary battery, which is characterized by comprising the above phases.

As an effect of the present invention, the negative electrode active material including a crystalline Si phase, which is an active metal uniformly dispersed and precipitated on the inactive metal crystalline matrix including Si, additive metals M, Fe, and Mn, is formed on the inactive metal crystalline matrix. Copper clustering (Cu clustering) phenomenon may occur due to the tendency of iron (Fe) and copper (Cu) within the material to separate.

Accordingly, a Cu-rich region is formed in the amorphous alloy by the Cu clustering phenomenon, and nuclei of an inactive matrix phase due to the Cu are generated and precipitated, and accordingly, the crystallization temperature A low silicon (Si-rich) region is formed, so that a crystalline Si phase, which is an active metal, may be finely precipitated within the inactive metal crystalline matrix phase during heat treatment.

As another effect of the present invention, the inactive metal crystalline matrix phase in the negative electrode active material may play a role in suppressing the volume expansion of the negative electrode active material while forming a structure that does not react with lithium ions, and the crystalline Si phase, which is the active metal, may form a structure that does not react with lithium ions. Since it can react reversibly, it is directly related to the capacity of the negative electrode active material, showing improved capacity characteristics of the negative electrode active material.

Therefore, when charging and discharging the negative electrode active material, the inert metal crystalline matrix phase has a yield strength that can withstand the expansion stress of silicon particles due to intercalation of lithium ions, so that the volume of the negative electrode active material increases during charging and discharging. Particle micronization due to expansion and contraction can be suppressed.

Therefore, when a lithium secondary battery is manufactured using a negative electrode active material for a lithium secondary battery containing a crystalline Si phase, which is an active metal uniformly dispersed and precipitated on the inert metal crystalline matrix, the initial coulombic efficiency is excellent at 85% or more, and 50 cycles are achieved. It can have lifespan characteristics that maintain more than 83% of its capacity even after use.

The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

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

Figure 2 is a graph showing the results of thermal analysis of a negative electrode active material for a lithium secondary battery according to an embodiment of the present invention using differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min.

Figure 3 is a graph confirming the diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Example 1 manufactured according to an embodiment of the present invention.

Figure 4 is a graph confirming the diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Comparative Example 1 manufactured according to an embodiment of the present invention.

Figure 5 is a graph showing the capacity maintenance rate according to cycle of Example 1 and Comparative Example 1 manufactured according to an embodiment of the present invention.

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

Throughout the specification, when a part is said to be "connected (connected, contacted, combined)" with another part, this means not only "directly connected" but also "indirectly connected" with another member in between. "Includes cases where it is. Additionally, when a part is said to “include” a certain component, this does not mean that other components are excluded, but that other components can be added, unless specifically stated to the contrary.

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

The present invention seeks to manufacture a high-capacity, high-output silicon alloy-based anode active material suitable for wireless charging energy storage by using rapid solidification process and alloy design technology.

To date, research on the manufacture of silicon alloy-based anode active materials is ongoing using mechanical alloying methods such as ball milling or liquid rapid solidification process, but manufacturing process variables (ball milling time, powder particle size) Due to the difficulty in controlling the cooling rate of the molten metal, the diameter of the silicon phase (Si phase), which is an active metal, is dispersed and deposited uniformly and reproducibly in the matrix phase (an inactive metal) with a diameter of less than 100 nm, thereby solving the problem of volume expansion of the silicon material. There is no research report on a silicon alloy-based negative electrode active material that solves the problem, and the present invention seeks to solve this problem in the following three ways.

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

Second, manufacturing silicon-based amorphous alloy using rapid solidification process.

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

Through the above process, a matrix phase with a yield strength that can withstand the expansion stress of silicon particles due to intercalation of lithium ions during charge/discharge cycles is formed, with a diameter of 100 nm or less. By implementing a microstructure in which the silicon phase is uniformly dispersed and precipitated, we aim to suppress particle micronization caused by volume expansion and contraction of silicon particles caused by insertion and desorption reactions of lithium ions.

Specifically, an embodiment of the present invention provides a negative electrode active material for lithium secondary batteries.

As an example of the above embodiment, for the total 100 at%, 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, 1 at% or more and 20 at% or less of Fe, and 20 at% or less of Mn It includes, wherein the added metal M includes Al and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. There may be a negative electrode active material for a lithium secondary battery that further contains an element and is characterized by comprising a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.

As an example of the above embodiment, with respect to 100 at% of the negative electrode active material, the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less. This can be.

As an example of the above embodiment, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inert metal crystalline matrix was measured by differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min. When thermal analysis is performed, there may be a negative electrode active material for a lithium secondary battery, which is formed by heat treatment of a Si-based amorphous alloy that exhibits an exothermic peak due to Cu clustering in the temperature range of 300°C to 450°C.

As an example of the above embodiment, the inert matrix phase of the negative electrode active material is,

There may be a negative electrode active material for a lithium secondary battery, which _is characterized in that it contains one or more phases selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and _Fe 5 Si 3 phases.

Additionally, another embodiment of the present invention provides a negative electrode for a lithium secondary battery.

As an example of the above embodiment, it includes a negative electrode current collector and a negative electrode active material layer formed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer includes 75 wt% to 92 wt% of the negative electrode active material and a conductive material for 100 wt%. It contains 1 wt% to 10 wt%, and 7 wt% to 15 wt% of a binder, and the negative electrode active material includes 45 at% or more and less than 60 at% of Si, and 25 at% or more of Si, based on 100 at% of the negative electrode active material. Containing an added metal M, 1 at% or more and 20 at% or less of Fe, and 20 at% or less of Mn, wherein the added metal M includes Al and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. It further includes an element, and the negative electrode active material includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix. There may be a negative electrode for a lithium secondary battery. .

As an example of the above embodiment, the negative electrode for a lithium secondary battery is characterized in that the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less, with respect to 100 at% of the negative electrode active material. There may be.

As an example of the above embodiment, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inert metal crystalline matrix was measured by differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min. When thermal analysis is performed, there may be a negative electrode for a lithium secondary battery that is formed by heat treatment of a Si-based amorphous alloy that exhibits an exothermic peak due to Cu clustering in the temperature range of 300°C to 450°C.

As an example of the above embodiment, the inert matrix phase of the negative electrode active material includes one or more phases selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases. There may be a negative electrode for a lithium secondary battery characterized by this.

Additionally, another embodiment of the present invention provides a lithium secondary battery.

As an example of the above embodiment, 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 active material layer It 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, based on 100 wt% of silver, and the negative electrode active material is 100 at% of the negative electrode active material. For, it includes 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, 1 at% or more and 20 at% or less of Fe, and 20 at% or less of Mn, wherein the added metal M is Al. and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. There may be a lithium secondary battery that further includes an element, and the negative electrode active material includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.

As an example of the above embodiment, there is a lithium secondary battery characterized in that the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less, with respect to 100 at% of the negative electrode active material. You can.

As an example of the above embodiment, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inert metal crystalline matrix was measured by differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min. When thermal analysis is performed, there may be a lithium secondary battery that is formed by heat treatment of a Si-based amorphous alloy that exhibits an exothermic peak due to Cu clustering in the temperature range of 300°C to 450°C.

As an example of the above embodiment, the inert matrix phase of the negative electrode active material is,

There may be a lithium secondary battery characterized in that it contains one or more phases selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases.

Additionally, another embodiment of the present invention provides a method for manufacturing a negative electrode active material for a lithium secondary battery.

As an example of the above embodiment, preparing metals or alloys of Si, additive metal M, Fe, and Mn, respectively; Preparing a Si-based amorphous alloy having a Si-M-Fe-Mn composition using the prepared metals or alloys of Si, additive metals M, Fe, and Mn; And heat-treating the Si-based amorphous alloy to produce a negative electrode active material for a lithium secondary battery comprising a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix. , the negative electrode active material is 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, 1 at% or more and 20 at% or less of Fe, and 20 at% or less, based on 100 at% of the negative electrode active material. of Mn, and the added metal M includes Al and Cu; Or, including Al and Cu, but at least one selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. There may be a method of manufacturing a negative electrode active material for a lithium secondary battery, characterized in that it further contains an element.

As an example of the above embodiment, the negative electrode active material for a lithium secondary battery contains 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, and 1 at% or more and 20 at% or less, based on 100 at% of the negative electrode active material. There may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which is characterized by containing Fe and 20 at% or less of Mn.

As an example of the above embodiment, the step of manufacturing a Si-based amorphous alloy having the Si-M-Fe-Mn composition includes mixing the prepared metals or alloys of Si, additive metals M, Fe, and Mn, and then melting them. manufacturing metal; And there may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which includes the step of solidifying the molten metal by liquid rapid solidification to produce a Si-based amorphous alloy having the Si-M-Fe-Mn composition.

As an example of the above embodiment, the step of manufacturing the Si-based amorphous alloy having the Si-M-Fe-Mn composition includes ball milling, mechanical alloying, gas atomization, There may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which is characterized in that it is performed by one or more methods selected from the group consisting of chemical vapor deposition.

As an example of the above embodiment, there may be a method of manufacturing a negative electrode active material for a lithium secondary battery, wherein the heat treatment is performed in a temperature range of 400°C to 700°C.

As an example of the above embodiment, with respect to 100 at% of the negative electrode active material, the Al is contained in an amount of 24.9 at% or more and less than 49.8 at%, and the Cu is contained in an amount of 0.1 at% or more and 5 at% or less. There may be a manufacturing method.

As an example of the above embodiment, the microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inert metal crystalline matrix was measured by differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min. When thermal analysis is performed, there may be a method of manufacturing a negative electrode active material for a lithium secondary battery, which is characterized in that it is formed by heat treatment of a Si-based amorphous alloy that has an exothermic peak due to Cu clustering in the temperature range of 300 ℃ to 450 ℃. .

As an example of the above embodiment, the inert matrix phase of the negative electrode active material includes one or more phases selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases. There may be a method for manufacturing a negative electrode active material for a lithium secondary battery, which is characterized in that:

In the present invention, in melt spinning, which is a liquid rapid solidification method, an amorphous alloy can be manufactured reproducibly at a rotational speed of the copper wheel in the range of 30 m/s to 60 m/s, more preferably 40 m/s. Amorphous alloys can be manufactured reproducibly at high speeds.

In the present invention, the crystalline Si phase, which is an active metal, is a Si system in which Cu is forcibly dissolved, produced by a liquid quenching and solidification method in which molten metal is sprayed onto a copper wheel rotating at a speed in the range of 30 m/s to 60 m/s. It is uniformly dispersed and precipitated on an inert metal crystalline matrix by Cu clustering through heat treatment of amorphous alloy.

After manufacturing the amorphous alloy, heat treatment is performed at a constant temperature (400°C to 700°C) to produce a negative electrode active material in which reproducible active silicon particles are uniformly dispersed and precipitated in nano size within an inert matrix. It can be judged that it can have excellent lifespan characteristics with capacity maintained even after 50 cycles.

In the present invention, when heat treating an amorphous alloy at a temperature below 400°C, capacity development is not possible because the active silicon phase that reacts with lithium ions does not precipitate during charge and discharge, and when heat treatment is performed above 700°C, the precipitated active silicon As the phase grows and becomes coarse, a rapid decrease in capacity may occur.

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

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

Referring to Figure 1, the present invention includes the step of preparing metals or alloys of Si, additive metals M, Fe, and Mn (S10), liquid quenching solidification method, ball milling method, and mechanical alloying method. ), performing one or more processes of gas atomization, and chemical vapor deposition (S20), manufacturing a Si-based amorphous alloy having a Si-M-Fe-Mn composition ( S30); and heat-treating the Si-based amorphous alloy to produce a negative electrode active material for a lithium secondary battery having a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix (S40). It can be confirmed that it contains .

At this time, the added metal M includes Al and Cu; or,

Al and Cu, but any one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. A method for manufacturing a negative electrode active material for a lithium secondary battery is provided, further comprising:

The negative electrode active material for the lithium secondary battery is 45 at% to less than 60 at% of Si, 25 at% or more of added metal M, 1 at% to 20 at% of Fe, and 20 at% based on 100 at% of the negative electrode active material. It may contain less than % Mn.

The crystalline Si phase, which is the active metal, can react reversibly with lithium ions and is therefore directly related to the capacity of the negative electrode active material, and the inactive metal crystalline matrix phase forms a structure that does not react with lithium ions and serves to suppress the volume expansion of the negative electrode active material. can do.

The crystalline Si phase, which is the active metal, may be uniformly dispersed and precipitated within the inactive metal crystalline matrix phase. For example, the structure of the matrix phase that does not react with lithium ions may be one or more phases selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases.

The negative electrode active material may include a crystalline Si phase, which is a microstructured active metal with a diameter of 100 nm or less, uniformly dispersed and precipitated on an inert metal crystalline matrix. The particle size of the Si phase, which is the active metal, uniformly dispersed and precipitated on the inactive metal crystalline matrix may be 1 nm to 100 nm.

In the negative electrode active material for a lithium secondary battery, Si may be involved in the insertion 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 Si contained in the negative electrode active material for lithium secondary batteries is related to the capacity and lifespan 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 the lifespan characteristics may be somewhat reduced. Therefore, in order to improve the lifespan characteristics of the negative electrode active material of the present invention rather than improving capacity, the Si content in the negative electrode active material is preferably at a level of 45 at% or more and less than 60 at%. If the Si content is less than 45 at%, it is undesirable because it may exhibit excessively low capacity to realize capacity as a negative electrode active material for lithium secondary batteries, and if the Si content is more than 60 at%, it becomes crystalline and Si Amorphous. This is undesirable because an alloy is not produced or the content of components other than Si constituting the inert metal crystalline matrix phase is low, making it difficult to improve the lifespan of the negative electrode active material for lithium secondary batteries.

In general, Cu is difficult to dissolve in Fe when it is in a solid state at room temperature, but by using a liquid rapid solidification method such as melt spinning, Cu can be forcibly dissolved in Fe. Cu that is forcibly dissolved tends to separate from Fe, and this tendency causes the copper clustering phenomenon. The inactive metal matrix phase may first precipitate in areas where Cu clustering occurs, and due to this phenomenon, the anode active material of the present invention has a crystalline Si phase, which is an active metal, uniformly dispersed and precipitated on the inactive metal crystalline matrix. It may include dispersed and precipitated microstructure.

The Cu content is preferably 0.1 at% or more and 5 at% or less when the Fe content is 1 at% or more and 20 at% or less. This is because, when the Cu content is less than 0.1 at%, the above-mentioned Cu clustering phenomenon is so small that dispersion and precipitation of active silicon nanoparticles may not occur, which is not desirable. In addition, if the Cu content exceeds 5 at%, it is undesirable because Cu may act as an impurity. Therefore, the Cu content is preferably 0.1 at% or more and 5 at% or less.

In the present invention, since Fe included in the inert metal crystalline matrix can play a role in inducing Cu clustering, capacity characteristics can be improved.

As described above, the inert metal crystalline matrix phase includes a Si-based alloy containing Si, an added metal M, Fe, and Mn, where the added metal M includes Al and Cu; or,

Al and Cu, but any one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. More may be included. That is, the added metal M essentially includes Al and Cu, and additionally Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and It may further include one or more elements selected from the group consisting of Nb.

At this time, one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb are present in an amount of 0.1 at% to It can be included at 5 at% and can be used as an ingredient to improve capacity characteristics or lifespan characteristics.

Figure 2 is a graph showing the results of thermal analysis of a negative electrode active material for a lithium secondary battery according to an embodiment of the present invention using differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min.

Referring to Figure 2, in the case of a negative electrode active material for a lithium secondary battery and a lithium secondary battery containing the same according to an embodiment of the present invention, Cu and Fe are necessarily included as described above, Si-M-Fe-Mn The first crystallization temperature ( _T It can be seen that there is an exothermic peak due to Cu clustering around 300°C to 450°C, and that when heat treatment is performed at a temperature above 450°C, the inactive matrix phase precipitates first, and then the active silicon phase precipitates.

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 side of the negative electrode current collector, and the negative electrode active material layer contains 75 wt% to 92 wt% of the negative electrode active material and 1 wt% to 1 wt% of the conductive material. It contains 10 wt% and 7 wt% to 15 wt% of binder, and the negative electrode active material is characterized in that it includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix. do.

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 conductive material is used to provide conductivity, and in the lithium secondary battery being constructed, any electronically conductive material can be used as long as it does not cause chemical change. Specifically, at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder such as copper, nickel, aluminum, and silver, metal fiber, and conductive polymer materials such as polyphenylene derivatives. It can be used, but is not limited to this.

When the content of the conductive material is less than 1 wt%, the effect of improving conductivity and the resulting lifespan characteristics due to the use of the conductive material is minimal, and when the content of the conductive material is more than 5 wt%, the specific surface area of the conductive material increases due to the conductive material. This is undesirable because the reaction between the electrolyte and the electrolyte may increase and the lifespan characteristics may deteriorate. More specifically, the content of the conductive material may preferably be 1 wt% to 3 wt%.

In an embodiment of the present invention, the binder serves to adhere the negative electrode active material particles to each other and the negative electrode active material to the negative electrode current collector, and specifically, polyimide, polyamidoimide, polybenzimidazole, poly Vinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene. Any one or more of fluoride, polyethylene, polypropylene, styrene-butadiene, acrylated styrene-butadiene, and epoxy resin may be used, but is not limited thereto.

If the binder content is less than 7 wt%, it is undesirable because it is difficult to exhibit sufficient adhesion within the negative electrode, and if the binder content is more than 15 wt%, it is undesirable because there is a risk of deterioration in the capacity characteristics of the lithium secondary battery. More specifically, the binder content may preferably 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 a desirable level.

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

Hereinafter, lithium secondary batteries will be described.

The lithium secondary battery of the present invention includes 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 side of the negative electrode current collector.

In an embodiment of the present invention, the cathode includes a cathode current collector and a cathode active material layer formed on the cathode current collector, and the cathode active material layer is formed by mixing the cathode active material, a binder, and a conductive material in a solvent. After preparing the composition, the composition may be applied on the positive electrode current collector. Since this method of manufacturing an anode is widely known in the art, detailed description will be omitted in this specification.

The positive electrode active material may include a material capable of reversibly inserting and deintercalating lithium ions. Specifically, the positive electrode active material may include lithium-containing transition metal oxide, lithium-containing transition metal sulfide, etc. 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 O4 (0<Z<2), LiMn _2-z Co _z O ₄ (0<Z<2), LiCoPO ₄ , and LiFePO ₄ may be used, but are not limited thereto.

The binder serves to adhere the positive electrode active material particles to each other and to the positive electrode current collector, and specifically, polyimide, polyamidoimide, polybenzimidazole, polyvinyl alcohol, carboxymethyl cellulose, and 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 is not limited thereto.

The conductive material is used to provide conductivity, and in the lithium secondary battery being constructed, any electronically conductive material can be used as long as it does not cause chemical change. Specifically, at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder such as copper, nickel, aluminum, and silver, metal fiber, and conductive polymer materials such as polyphenylene derivatives. It can be used, but is not limited to this.

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 may specifically 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 one or more of carbonate-based, ester-based, ether-based, ketone-based, alcohol-based and aprotic solvents. For example, the non-aqueous organic solvents include dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), n-methyl acetate, and dibutyl ether. , cyclohexanone, isopropyl alcohol, and sulfolane solvents. These non-aqueous organic solvents can be used individually or in combination of two or more types.

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 can be used individually or in combination of two or more types.

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

Hereinafter, embodiments or experimental examples of the present invention will be described in detail with reference to the attached drawings. The examples or experimental examples of the present invention are intended to explain the configuration and effects of the present invention in more detail, and it is clear that the scope of the present invention is not limited thereto.

<Example 1> Preparation of Amorphous alloy

The amorphous alloy of the present invention was manufactured under the conditions shown in Table 1 below.

	alloy composition					crystal structure	Heat treatment conditions	Electrode characteristics evaluation results
	Si (at%)	Al (at%)	Cu (at%)	Fe (at%)	Mn (at%)	XRD crystal phase	temperature, time	initial charge capacity (mAh/g)	initial discharge capacity (mAh/g)	Early Charge/discharge efficiency (%)	Capacity maintenance rate (50 cycles, %)
Example 1	53	29	One	15	2	Si + Fe 2 Al 3 Si 3 +FeSi 2 + Al 2.7 Fe 1 Si 2.3	Amorphous → 650℃, 1hr	1279.08	1095.60	85.66	83.53
Comparative Example 1	60	26	-	14	-	Si + Fe 2 Al 3 Si 3 + amorphous phase	As-quenched	1629.00	1470.50	90.20	66.89

A single-roll liquid rapid solidification method in which an alloy containing Si, Al, Cu, Fe, and Mn is melted by arc melting to prepare a molten liquid, and then the molten liquid is sprayed on a copper wheel rotating at 40 m/s, Si ₅₃ Al ₂₉ Cu. A Si-based amorphous alloy with a composition of ₁ Fe ₁₅ Mn ₂ and Cu in which Cu was forcibly dissolved was manufactured.

The Si-based amorphous alloy is heat-treated at 650°C for 1 hour in a furnace under inert gas conditions to form a crystalline crystalline phase with a microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix. A negative electrode active material for lithium secondary batteries was prepared.

Negative active material powder having a crystal phase formed by mixing 200 g of zirconium balls (Zr-balls), 5 g of the heat-treated Si-based alloy, and n-hexane and then pulverizing them for 15 minutes using a paint shaker. After manufacturing a raw 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 incubated at 400°C under Ar gas conditions. The anode of Example 1 was manufactured by heat treatment for 1 hour.

Figure 3 is a graph confirming the diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery in Example 1 manufactured according to an embodiment of the present invention. As can be seen in Figure 3, it was confirmed that the inert matrix phase of the negative electrode active material of the present invention contains FeSi ₂ , Fe ₂ Al ₃ Si ₃ , and Al _2.7 Fe ₁ Si _2.3 .

Meanwhile, Comparative Example 1 was prepared in the same manner as Example 1, except that the amorphous alloy was left without heat treatment to prepare a Si-based alloy containing a mixture of crystalline and amorphous Si ₆₀ Al ₂₆ Fe ₁₄ composition. Additionally, a negative electrode was manufactured in the same manner as Example 1.

Figure 4 is a graph confirming the diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Comparative Example 1 manufactured according to an embodiment of the present invention. As can be seen in FIG. 4, it was confirmed that Fe ₂ Al ₃ Si ₃ was included in the inactive matrix of the negative electrode active material of Comparative Example 1, and in addition, amorphous materials were confirmed.

<Experimental Example 1> Electrode characteristic evaluation

After manufacturing a lithium secondary battery using the negative electrode prepared in Example 1, the charging capacity, discharge capacity, and initial coulombic efficiency (ICE) of the negative electrode active material when charging and discharging were performed once were measured. The value divided by the initial charge capacity) and the capacity retention rate according to 50 repetitions of charge/discharge are listed in Table 2 below.

	Electrode characteristics evaluation results
	initial charge (mAh/g)	initial discharge (mAh/g)	Initial Coulombic Efficiency (%)	Capacity maintenance rate (50 cycles, %)
Example 1	1279.08	1095.60	85.66	83.53
Comparative Example 1	1629.00	1470.50	90.20	66.89

In the case of the anode manufactured with the anode active material of Example 1 of the present invention, which has a crystalline crystal structure, by heat-treating a Si-based amorphous alloy in which Cu was forcibly dissolved and produced by liquid quenching and solidification at 650°C, the initial coulombic efficiency was confirmed to be 85.66. The capacity maintenance rate after 50 cycles was also high at 83.53%.

On the other hand, in the case of Comparative Example 1, a rapidly solidified alloy manufactured without heat treatment, the initial coulombic efficiency was high at 90.20%, while the capacity retention rate after 50 cycles was confirmed to be significantly lower at 66.89%. Comparative Example 1 has a mixed crystalline phase and amorphous phase. It was manufactured without heat treatment on a Si-based alloy with a composition of Si ₆₀ Al ₂₆ Fe ₁₄ , and the capacity maintenance rate was judged to be significantly lower than the high initial coulombic efficiency. It has been done.

Figure 5 is a graph comparing capacity maintenance rates according to charge and discharge cycles. It was confirmed that the capacity maintenance rate of Comparative Example 1 significantly decreased as the charge/discharge cycle increased.

An embodiment of the present invention can manufacture an amorphous alloy reproducibly at a rotational speed of a copper wheel in the range of 30 m/s to 60 m/s in melt spinning, which is a liquid rapid solidification method, and more preferably 40 m/s. Amorphous alloys can be manufactured reproducibly at high speeds.

After manufacturing the amorphous alloy, heat treatment is performed at a constant temperature (400°C to 700°C) to produce a negative electrode active material in which reproducible active silicon particles are uniformly dispersed and precipitated in nano size within an inert matrix. It can be judged that it can have excellent lifespan characteristics with capacity maintained even after 50 cycles.

Although the technical idea of the present invention described above has been described in detail in preferred embodiments, it should be noted that the above-described embodiments are for illustrative purposes only and are not intended for limitation. Additionally, those of ordinary skill in the technical field of the present invention will understand that various embodiments are possible within the scope of the technical idea of the present invention. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the attached claims.

Claims (20)

1. For the total 100 at%, it includes 45 at% to 60 at% of Si, 25 at% to 25 at% of added metal M, 1 at% to 20 at% of Fe, and 20 at% to 20 at% of Mn,

   The added metal M includes Al and Cu; or,

   Al and Cu, but any one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. It includes more,

   A negative electrode active material for a lithium secondary battery, characterized in that it includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix.
2. According to paragraph 1,

   For 100 at% of the negative electrode active material,

   The Al is 24.9 at% or more and less than 49.8 at%,

   A negative electrode active material for a lithium secondary battery, characterized in that the Cu is contained in an amount of 0.1 at% or more and 5 at% or less.
3. According to paragraph 1,

   The microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix,

   When thermal analysis was performed using differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min, a Si-based amorphous alloy with an exothermic peak due to Cu clustering was heat treated in the temperature range of 300°C to 450°C. A negative electrode active material for a lithium secondary battery, characterized in that formed.
4. According to paragraph 1,

   The inert matrix phase of the negative electrode active material is,

   A negative electrode active material for a lithium secondary battery, characterized in that it contains at least one phase selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases.
5. It includes a negative electrode current collector and a negative electrode active material layer formed on at least one side 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, based on 100 wt%,

   The negative electrode active material is 45 at% to less than 60 at% of Si, 25 at% or more of added metal M, 1 at% to 20 at% of Fe, and 20 at% or less of the negative electrode active material, based on 100 at% of the negative electrode active material. Contains Mn,

   The added metal M includes Al and Cu; or,

   Al and Cu, but any one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. Contains more,

   The negative electrode active material is a negative electrode for a lithium secondary battery, characterized in that it includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.
6. According to clause 5,

   For 100 at% of the negative electrode active material,

   The Al is 24.9 at% or more and less than 49.8 at%,

   A negative electrode for a lithium secondary battery, characterized in that the Cu is contained in an amount of 0.1 at% or more and 5 at% or less.
7. According to clause 5,

   The microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix,

   When thermal analysis was performed using differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min, a Si-based amorphous alloy with an exothermic peak due to Cu clustering was heat treated in the temperature range of 300°C to 450°C. A negative electrode for a lithium secondary battery, characterized in that formed.
8. According to clause 5,

   The inert matrix phase of the negative electrode active material is,

   A negative electrode for a lithium secondary battery, characterized in that it contains at least one phase selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases.
9. In a lithium secondary battery including an anode, a cathode, 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, based on 100 wt%,

   The negative electrode active material is 45 at% to less than 60 at% of Si, 25 at% or more of added metal M, 1 at% to 20 at% of Fe, and 20 at% or less of the negative electrode active material, based on 100 at% of the negative electrode active material. Contains Mn,

   The added metal M includes Al and Cu; or,

   Al and Cu, but any one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. Contains more,

   The negative electrode active material is a lithium secondary battery characterized in that it includes a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inactive metal crystalline matrix.
10. According to clause 9,

    For 100 at% of the negative electrode active material,

    The Al is 24.9 at% or more and less than 49.8 at%,

    A lithium secondary battery, characterized in that the Cu is contained in an amount of 0.1 at% or more and 5 at% or less.
11. According to clause 9,

    The microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix,

    When thermal analysis was performed using differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min, a Si-based amorphous alloy with an exothermic peak due to Cu clustering was heat treated in the temperature range of 300°C to 450°C. A lithium secondary battery characterized in that it is formed.
12. According to clause 9,

    The inert matrix phase of the negative electrode active material is,

    A lithium secondary battery comprising at least one phase selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases.
13. Preparing metals or alloys of Si, additive metal M, Fe, and Mn;

    Preparing a Si-based amorphous alloy having a Si-M-Fe-Mn composition using the prepared metals or alloys of Si, additive metals M, Fe, and Mn; and

    A step of heat treating the Si-based amorphous alloy to produce a negative electrode active material for a lithium secondary battery comprising a microstructure in which a crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on an inert metal crystalline matrix.

    The negative electrode active material is 45 at% to less than 60 at% of Si, 25 at% or more of added metal M, 1 at% to 20 at% of Fe, and 20 at% or less of the negative electrode active material, based on 100 at% of the negative electrode active material. Contains Mn,

    The added metal M includes Al and Cu; or,

    Al and Cu, but any one or more elements selected from the group consisting of Ni, Ti, W, Co, Cr, Mo, Zr, Ge, Ca, Ag, Bi, Sb, Sn, Zn, B, and Nb. A method for manufacturing a negative electrode active material for a lithium secondary battery, further comprising:
14. According to clause 13,

    The negative electrode active material for the lithium secondary battery is, with respect to 100 at% of the negative electrode active material,

    Manufacture of anode active material for lithium secondary batteries characterized by containing 45 at% or more and less than 60 at% of Si, 25 at% or more of added metal M, 1 at% or more and 20 at% or less of Fe, and 20 at% or less of Mn. method.
15. The method of claim 13, wherein the step of manufacturing the Si-based amorphous alloy having the Si-M-Fe-Mn composition,

    Mixing the prepared Si, additive metals M, Fe, and Mn metals or alloys and then melting them to produce molten metal; and

    A method for producing a negative electrode active material for a lithium secondary battery, comprising the step of solidifying the molten metal by liquid rapid solidification to produce a Si-based amorphous alloy having the Si-M-Fe-Mn composition.
16. The method of claim 13, wherein the step of manufacturing the Si-based amorphous alloy having the Si-M-Fe-Mn composition,

    Lithium, characterized in that it is performed by one or more methods selected from the group consisting of ball milling, mechanical alloying, gas atomization, and chemical vapor deposition. Method for manufacturing anode active material for secondary batteries.
17. According to clause 13,

    A method of manufacturing a negative electrode active material for a lithium secondary battery, characterized in that the heat treatment is carried out in a temperature range of 400 ℃ to 700 ℃.
18. According to clause 13,

    For 100 at% of the negative electrode active material,

    The Al is 24.9 at% or more and less than 49.8 at%,

    A method of manufacturing a negative electrode active material for a lithium secondary battery, characterized in that the Cu is contained in an amount of 0.1 at% or more and 5 at% or less.
19. According to clause 13,

    The microstructure in which the crystalline Si phase, which is an active metal with a diameter of 100 nm or less, is uniformly dispersed and precipitated on the inactive metal crystalline matrix,

    When thermal analysis was performed using differential scanning calorimetry (DSC) at a temperature increase rate of 10°C/min, a Si-based amorphous alloy with an exothermic peak due to Cu clustering was heat treated in the temperature range of 300°C to 450°C. A method of manufacturing a negative electrode active material for a lithium secondary battery, characterized in that it is formed.
20. According to clause 13,

    The inert matrix phase of the negative electrode active material is,

    A method for producing a negative electrode active material for a lithium secondary battery, comprising at least one phase selected from the group consisting of FeSi ₂ , Fe ₂ Al ₃ Si ₃ , Al _2.7 Fe ₁ Si _2.3 , and Fe ₅ Si ₃ phases.

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