KR20200063424A - 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 provides a manufacturing method of a cathode active material for a lithium secondary battery, a cathode active material for a lithium secondary battery, a cathode for a lithium secondary battery, and a lithium secondary battery including the same. The cathode active material for a lithium secondary battery comprises 45-60 atom% (excluding 60 atom%) of Si, 25-44.9 atom% of an added metal M, 10-25 atom% of Fe, and 0.1-5 atom% of Cu. M includes Al and one or more metallic elements selected from a group consisting of Ti, W, Co, Cr, Ge, and Ca. The cathode active material for a lithium secondary battery has a microstructure in which a crystalline Si phase which is an active metal having a size of 100 nm or lower is uniformly dispersed and precipitated in a non-active metal amorphous matrix phase or a non-active crystalline matrix phase. Therefore, the lithium secondary battery of the present invention has a yield strength to withstand the expansion stress of silicon particles by intercalation of lithium ions during charging and discharging to suppress particle pulverization by volume expansion and contraction of the cathode active material during charging and discharging to improve life characteristics.

Description

Manufacturing method of negative electrode active material for lithium secondary battery, negative electrode active material 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 comprising the same. More specifically, the crystalline silicon phase, which is an active metal having a size of 100 nm or less, uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix phase containing 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 having a microstructure, a negative electrode for a lithium secondary battery, and a lithium secondary battery including the same.

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

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

The lithium secondary battery is manufactured by using a material capable of intercalation and deintercalation of lithium ions as a negative electrode and a positive electrode, and by 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 at the negative electrode and the positive electrode.

The performance improvement of lithium secondary battery 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 the lithium secondary battery has already reached the theoretical capacity, the need for a new negative electrode active material is increasing to realize a high-capacity and high-power battery 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 has very useful characteristics for insertion and desorption of lithium ions. Graphite theoretically shows a capacity of 372 mAh/g, but with the recent increase in demand for a high-capacity lithium battery, 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 high-capacity negative electrode active materials is actively conducted. Is becoming.

When silicon (Si) is used as a negative electrode active material, there is a problem that cracking and cracking of silicon particles due to volume change occurs during lithium ion insertion and desorption by repeated charging and discharging. Due to these problems, the surface area of the particles of the negative electrode active material is increased, and as a result, the coating layer made of the decomposition product of the non-aqueous electrolyte is formed thick on the surface of the negative electrode active material, thereby increasing the interface resistance between the negative electrode active material and the non-aqueous electrolyte, thereby decreasing charge/discharge life characteristics. There was a problem.

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

In addition, until now, studies on the production of silicon alloy-based negative active materials using mechanical alloying methods such as ball milling (Ball Milling) or liquid rapid solidification process (Rapidly Solidification Process) have been conducted, but manufacturing process parameters (ball milling time, powder particles Due to the difficulty in controlling the size, cooling rate of the molten metal), the size of only the silicon phase (Si phase), which is an active metal, cannot be uniformly and reproducibly dispersed in the matrix phase, which is an inert metal, at a level of 100 nm or less. When silicon is applied to the negative electrode active material for a lithium secondary battery, there is a problem that the volume expansion problem of the silicon material during charging and discharging cannot be solved.

Republic of Korea Registered Patent No. 10-1385602

Technical problem to be achieved by the present invention is to improve the deterioration of life characteristics due to volume change when conventional silicon (Si) is used as a negative electrode active material, an inert metal amorphous matrix containing silicon, aluminum, iron, and copper, or A negative electrode active material for a lithium secondary battery in which a microstructure in which a crystalline silicon phase, which is an active metal having a size of 100 nm or less uniformly dispersed and deposited uniformly dispersed and deposited on an inert crystalline matrix phase, is implemented, a negative electrode for a lithium secondary battery and a lithium secondary battery comprising the same The purpose is to provide paper.

In addition, the technical problem to be achieved by the present invention, while improving the degradation of life characteristics due to volume change when using a conventional silicon (Si) as a negative electrode active material, while securing a uniform size of the Si precipitate, charge and discharge capacity, cycle life, etc. Providing a method for manufacturing a negative electrode active material for a lithium secondary battery, a negative electrode 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 comprising the same, to enable the production of a negative electrode active material for a lithium secondary battery having a reproducibility of 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 not mentioned can be clearly understood by those skilled in the art from the following description. There will be.

In order to achieve the above technical problem, an embodiment of the present invention, Si, the additive metal M, Fe and Cu of each metal or alloy is mixed at a ratio to become an alloy of a predetermined composition ratio and then melted to produce molten metal step; Solidifying the molten metal by liquid quenching and solidifying to produce a Si-based amorphous alloy in which Cu has a Si-M-Fe-Cu composition having a predetermined compositional ratio, and Cu is forcibly employed in Fe; And heat-treating the Si-based amorphous alloy to prepare a negative electrode active material for a lithium secondary battery having a microstructure in which crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix; Including, M is Al, Ti, W, Co, Cr, Ge or Ca One or more metal elements selected from the group consisting of a lithium secondary battery negative electrode active material manufacturing method for producing a negative electrode active material for a lithium secondary battery Gives

In an embodiment of the present invention, the negative electrode active material for a lithium secondary battery, 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 one or more metal elements selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca, and an inert metal amorphous matrix phase or an inert crystalline matrix phase It provides a negative electrode active material for a lithium secondary battery, characterized in that the crystalline Si phase of the active metal having a size of 100 nm or less has a uniformly dispersed and precipitated microstructure.

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

In an embodiment of the present invention, the crystalline Si phase, which is the active metal, is inactive metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. It may be a negative electrode active material for a lithium secondary battery characterized in that it is uniformly dispersed and deposited on a 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, and the negative electrode active material layer is 75 wt% to 92 wt. %, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder, wherein the negative electrode active material is 100 nm or less in size uniformly dispersed and deposited 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 that is a tissue active metal.

In the embodiment of the present invention, the negative electrode active material, 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 may be a negative electrode for a lithium secondary battery, characterized in that it comprises Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge or Ca.

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

In an embodiment of the present invention, the crystalline Si phase, which is the active metal, is inactive metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. It may be a negative electrode for a lithium secondary battery characterized in that it is uniformly dispersed and deposited on a 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 It includes an active material layer, the negative electrode active material layer comprises 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, and the negative electrode active material is an inactive metal amorphous It provides a lithium secondary battery characterized in that it comprises a crystalline Si phase that is a microstructure active metal having a size of 100 nm or less uniformly dispersed and deposited on a matrix phase or an inert crystalline matrix.

In the embodiment of the present invention, the negative electrode active material, 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 may be a lithium secondary battery comprising Al and one or more metal elements selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

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

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

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

Accordingly, the copper clustering (Cu clustering) phenomenon, the crystallization temperature of the low-silicon (Si-rich) region is formed during the heat treatment of the inactive metal amorphous matrix phase or inactive crystalline Si phase fine crystalline Si phase as an active metal It can be precipitated.

As another effect of the present invention, the inactive metal amorphous matrix phase or the inert crystalline matrix phase in the negative electrode active material may serve to inhibit the volume expansion of the negative electrode active material while forming a structure that does not react with lithium ions, and the active metal is Since the crystalline Si phase can react reversibly with lithium ions, it is directly related to the capacity of the negative electrode active material, and thus can exhibit improved capacity characteristics of the negative electrode active material.

Therefore, when the charging and discharging of the negative electrode active material, the inactive metal amorphous matrix phase or the inactive crystalline matrix phase has a yield strength capable of withstanding the expansion stress of silicon particles due to intercalation of lithium ions, and progresses charging and discharging. At the time, particle micronization due to volume expansion and contraction of the negative electrode active material can be suppressed.

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

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

1 is a flow chart 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 TEM photograph of the negative electrode active material for a lithium secondary battery of Example 3 prepared according to an embodiment of the present invention.
Figure 3 is a diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Example 1 prepared according to an embodiment of the present invention.
Figure 4 is a graph showing the charge and discharge cycle life of the lithium secondary batteries of Examples 1 to 4 prepared 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 thus is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout the specification, when a part is "connected (connected, contacted, coupled)" with another part, it is not only "directly connected" but also "indirectly connected" with another member in between. "It also includes the case where it is. Also, when a part “includes” a certain component, this means that other components may be further provided instead of excluding other components, unless otherwise stated.

The terms used herein 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 this specification, the terms “include” or “have” are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

In the present invention, a high-capacity, high-power silicon alloy-based anode active material suitable for wireless charging energy storage is manufactured by using a rapid solidification process and an alloy design technology.

To date, studies on the production of silicon alloy-based negative active materials using mechanical alloying methods such as ball milling or rapid solidification process have been conducted, but manufacturing process parameters (ball milling time, powder particle size) , Silicon alloy system that solved the problem of volume expansion of silicon materials by dispersing and depositing the size of only the silicon phase in a matrix phase uniformly and reproducibly 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 negative electrode active material, and the present invention attempts to solve this problem in the following three methods.

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

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

Third, through the heat treatment of the silicon-based amorphous alloy, only the active metal realizes a microstructure with uniform dispersion and precipitation in the matrix.

Finally, through the above process, when the charge/discharge cycle is performed, a silicon phase having a size of 100 nm is formed in a matrix phase having a yield strength capable of withstanding the expansion stress of silicon particles due to lithium ion intercalation. It is intended to suppress the micronization of particles by volume expansion and contraction of silicon particles generated by the insertion and desorption reaction of lithium ions by realizing a uniformly dispersed and precipitated microstructure.

Specifically, an embodiment of the present invention comprises the steps of mixing the metals or alloys of Si, the additive metals M, Fe, and Cu at a ratio of alloys having a predetermined composition ratio, and then melting them to prepare molten metals; Solidifying the molten metal by liquid quenching and solidifying to produce a Si-based amorphous alloy in which Cu has a Si-M-Fe-Cu composition having a predetermined compositional ratio, and Cu is forcibly employed in Fe; And heat-treating the Si-based amorphous alloy to prepare a negative electrode active material for a lithium secondary battery having a microstructure in which crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix; Including, M is Al, Ti, W, Co, Cr, Ge or Ca One or more metal elements selected from the group consisting of a lithium secondary battery negative electrode active material manufacturing method for producing a negative electrode active material for a lithium secondary battery Gives

In an embodiment of the present invention, the negative electrode active material for a lithium secondary battery, 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%.

Other embodiments of the present invention include Si at least 45 at% 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%, wherein M is Al and Ti, W, Co, Cr, Ge, or one or more metal elements selected from the group consisting of Ca, on an inert metal amorphous matrix or an inert crystalline matrix, an active metal having a size of 100 nm or less It provides a negative electrode active material for a lithium secondary battery having a fine structure in which the Si phase is uniformly dispersed and deposited.

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

In an embodiment of the present invention, the crystalline Si phase, which is the active metal, is inactive metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. It may be a negative electrode active material for a lithium secondary battery characterized in that it is uniformly dispersed and deposited on a 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, wherein the negative electrode active material layer is 75 wt% to 92 wt% of the negative electrode active material, and 1 wt% of the conductive material 10 wt% and 7 wt% to 15 wt% of the binder, wherein the negative electrode active material is a crystalline Si phase that is a microstructured active metal having a size of 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. It provides a negative electrode for a lithium secondary battery comprising a.

In the embodiment of the present invention, the negative electrode active material, 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 may be a negative electrode for a lithium secondary battery, characterized in that it comprises Al and at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge or Ca.

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

In an embodiment of the present invention, the crystalline Si phase, which is the active metal, is inactive metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. It may be a negative electrode for a lithium secondary battery characterized in that it is uniformly dispersed and deposited on a 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 the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder, and the negative electrode active material is on an inert metal amorphous matrix or an inert crystalline matrix It provides a lithium secondary battery characterized in that it comprises a crystalline Si phase that is a microstructure active metal having a size of 100 nm or less uniformly dispersed and deposited.

In the embodiment of the present invention, the negative electrode active material, 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 may be a lithium secondary battery comprising Al and one or more metal elements selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca.

In the embodiment of the present invention, the negative electrode active material, Ti, W, Co, Cr, lithium characterized in that it contains at least one metal element selected from the group consisting of Ca at 0.1 to 5 at% It may be a secondary battery.

In an embodiment of the present invention, the crystalline Si phase, which is the active metal, is inactive metal amorphous matrix phase or inactive by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. It may be a lithium secondary battery characterized in that the precipitate is uniformly dispersed 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 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, Si, the additive metal M, Fe and Cu of each metal or alloy is mixed at a ratio to become a predetermined composition ratio alloy and then melted to prepare a molten metal (S10), the Solidifying the molten metal by liquid quenching and solidification to produce a Si-M-Fe-Cu composition having a predetermined compositional ratio and Cu forcing a solid solution of Si-based amorphous alloy (S20) and heat-treating the Si-based amorphous alloy. , A step (S) for preparing a negative electrode active material for a lithium secondary battery having a microstructure in which crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix, wherein M is Provided is a method for manufacturing a negative electrode active material for a lithium secondary battery, which produces a negative electrode active material for a lithium secondary battery comprising at least one metal element selected from the group consisting of Al, Ti, W, Co, Cr, Ge, or Ca.

The negative electrode active material for a lithium secondary battery may include Si at least 45 at% 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%. have.

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

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

In general, Cu and Fe are difficult to be dissolved in Si when they are in a solid state at room temperature, but when a manufacturing method such as a liquid quenching method such as melt spinning is used, Cu can be forcibly employed in Si. Cu, which is forcibly employed, tends to separate from Fe, and this tends to cause copper clustering. Active Si may be uniformly dispersed and precipitated on a portion where a copper clustering phenomenon occurs, and due to this phenomenon, the negative electrode active material of the present invention is an active metal uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix. Phosphorus crystalline Si phase may include a microstructure uniformly dispersed and deposited.

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

In the present invention, Fe contained in the inert metal amorphous matrix phase or the inert crystalline matrix phase may play a role in inducing copper clustering, and thus, the capacity characteristics may be improved.

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

A particle diameter of the active metal Si phase uniformly dispersed and deposited on the inactive metal amorphous matrix phase 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 is 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 the binder, wherein the negative electrode active material is a crystalline Si phase that is a microstructured active metal having a size of 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. It is characterized by including.

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 that is a microstructured active metal having a size of 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. The negative active material includes Si at least 45 at% 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 M is Al And, Ti, W, Co, Cr, Ge or Ca may include at least one metal element selected from the group consisting of. At this time, at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca may be included at 0.1 at% to 5 at%.

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

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

In general, Cu and Fe are difficult to be dissolved in Si when they are in a solid state at room temperature, but when a manufacturing method such as a liquid quenching method such as melt spinning is used, Cu can be forcibly employed in Si. Cu, which is forcibly employed, tends to separate from Fe, and this tends to cause copper clustering. The active silicon nanoparticles can be uniformly dispersed and precipitated on a portion where copper clustering occurs, and due to this phenomenon, the negative electrode active material of the present invention is uniformly dispersed and precipitated in an inert metal amorphous matrix phase or an inert crystalline matrix phase Crystalline Si phase, which is a metal.

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

In the present invention, Fe contained in the inert metal amorphous matrix phase or the inert crystalline matrix phase may play a role in inducing copper clustering, and thus, the capacity characteristics may be improved.

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

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

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

The conductive material is used to impart conductivity, and in the lithium secondary battery configured, any material can be used as long as it is an electronic conductive material without causing chemical changes. Specifically, any one or more of conductive polymer materials such as metal powders such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, copper, nickel, aluminum, silver, metal fibers, and polyphenylene derivatives 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 the effect of improving the lifespan characteristics thereof are negligible, and when the content of the conductive material is more than 5 wt%, the conductive material due to the increase in specific surface area And it is not preferable because the reaction between the electrolyte increases and the lifespan characteristics may deteriorate. More specifically, the content of the conductive material may be preferably 1 wt% to 3 wt%.

The binder serves to adhere the negative electrode active material particles to each other well, and serves to well adhere the negative electrode active material to the negative electrode current collector, specifically, polyimide, polyamide imide, polybenzimidazole, polyvinyl alcohol, carboxymethyl cellulose, hydroxy Hydroxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, Any one or more of styrene-butadiene, acrylate-styrene-butadiene, and epoxy resins may be used, but is not limited thereto.

When the content of the binder is less than 7 wt%, it is difficult to exhibit sufficient adhesive strength in the negative electrode, and it is not preferable. 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 content of the binder 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 desired level.

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

Hereinafter, a lithium secondary battery 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 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 the embodiment of the present invention, the negative electrode active material, 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 may include Al and one or more metal elements 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 a Si phase in an inert metal amorphous matrix phase or an inert crystalline matrix phase and a crystalline Si phase that is an active metal. Since the crystalline Si phase, which is the active metal, can reversibly react with lithium ions, it is directly related to the capacity of the negative electrode active material, and the inactive metal amorphous matrix phase or the inactive crystalline matrix phase forms a structure that does not react with lithium ions, and It can serve to suppress the volume expansion. The active metal crystalline Si phase may be uniformly dispersed and precipitated in the inactive metal amorphous matrix phase or inactive crystalline matrix phase.

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

In general, Cu and Fe are difficult to be dissolved in Si when they are in a solid state at room temperature, but when a manufacturing method such as a liquid quenching method such as melt spinning is used, Cu can be forcibly employed in Si. Cu, which is forcibly employed, tends to separate from Fe, and this tends to cause copper clustering. Active Si may be uniformly dispersed and precipitated on a portion where a copper clustering phenomenon occurs, and due to this phenomenon, the negative electrode active material of the present invention is an active metal uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix. Phosphorus crystalline Si phase may include a microstructure uniformly dispersed and deposited.

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

In the present invention, Fe contained in the inert metal amorphous matrix phase or the inert crystalline matrix phase may play a role in inducing copper clustering, and thus, the capacity characteristics may be improved.

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

A particle diameter of the active metal crystalline Si phase uniformly dispersed and deposited on the inactive metal amorphous matrix or inert 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 the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder.

The conductive material is used to impart conductivity, and in the lithium secondary battery configured, any material can be used as long as it is an electronic conductive material without causing chemical changes. Specifically, any one or more of conductive polymer materials such as metal powders such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, copper, nickel, aluminum, silver, metal fibers, and polyphenylene derivatives 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 the effect of improving the lifespan characteristics thereof are negligible, and when the content of the conductive material is more than 5 wt%, the conductive material due to the increase in specific surface area And it is not preferable because the reaction between the electrolyte increases and the lifespan characteristics may deteriorate. More specifically, the content of the conductive material may be preferably 1 wt% to 3 wt%.

The binder serves to adhere the negative electrode active material particles to each other well, and serves to well adhere the negative electrode active material to the negative electrode current collector, specifically, polyimide, polyamide imide, polybenzimidazole, polyvinyl alcohol, carboxymethyl cellulose, hydroxy Hydroxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, Any one or more of styrene-butadiene, acrylate-styrene-butadiene, and epoxy resins may be used, but is not limited thereto.

When the content of the binder is less than 7 wt%, it is difficult to exhibit sufficient adhesive strength in the negative electrode, and it is not preferable. 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 content of the binder 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 desired level.

N-methylpyrrolidone or n-hexane may be used as a solvent for mixing the negative electrode active material, conductive material, and 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 solvent composition, the composition may be in a form applied on the positive electrode current collector. Since the anode manufacturing method is widely known in the art, detailed descriptions thereof will be omitted herein.

The positive electrode active material may include a material capable of reversibly inserting and removing 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 O ₄ (0<Z<2), LiMn _2-z Co _z O ₄ (0<Z<2), any one or more of LiCoPO ₄ and LiFePO ₄ may be used, but is not limited thereto.

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

The conductive material is used to impart conductivity, and in the lithium secondary battery configured, any material can be used as long as it is an electronic conductive material without causing chemical changes. Specifically, any one or more of conductive polymer materials such as metal powders such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, copper, nickel, aluminum, silver, metal fibers, and polyphenylene derivatives 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 a foam. For example, the positive electrode current collector may include aluminum, nickel, or alloys 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 carbonate-based, ester-based, ether-based, ketone-based, alcohol-based and aprotic solvents. 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 one or more selected from the group consisting of sulfolane (sulfolane) 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 LiB (C ₂ O ₄ ) ₂ It may include one or more selected from the group consisting of. These electrolyte salts may be used alone or in combination of two or more.

In the embodiment of the present invention, the separation membrane may be polyethylene, polypropylene or polyvinylidene fluoride as a monolayer membrane, or a multilayer membrane of two or more of these may be used.

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

-Experimental example-

division Alloy composition decision
rescue Amorphous alloy
Heat treatment conditions 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 Examples of the present invention and Comparative Example 1 without heat treatment were prepared.

[Example 1]

A single-roll liquid quenching and solidifying method in which an alloy containing Si, Al, Fe, and Cu is melted by an arc melting method or the like 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 ₁₇ Cu ₁ composition and Cu being forcibly dissolved in Fe was prepared.

Zirconium ball (Zr-ball) 200g, the Si-based amorphous alloy 5g, n-hexane (n-Hexane) and then mixed with a paint shaker (paint shaker) for 15 minutes to form a negative electrode active material powder having an amorphous crystal phase After preparing the Locoin-shaped electrode plate, a mixture of a 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 at 400° C., in an Ar atmosphere. A negative electrode (Example 1) was prepared by heat treatment for 1 hour.

[Example 2]

A single-roll liquid quenching and solidifying method in which an alloy containing Si, Al, Fe, and Cu is melted by an arc melting method or the like 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 ₁₇ Cu ₁ composition and Cu being forcibly dissolved in Fe was prepared.

Microstructure in which the Si-based amorphous alloy is heat-treated in an inert gas atmosphere for 1 hour at a temperature of 450° C., whereby an crystalline Si phase that is an active metal having a size of 100 nm or less is uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix A negative electrode active material for a lithium secondary battery having a crystalline phase in which amorphous and crystalline is mixed.

Zirconium ball (Zr-ball) 200g, the negative electrode active material 5g, n-hexane (n-Hexane) mixed and then pulverized using a paint shaker (paint shaker) for 15 minutes to form a coin-shaped electrode plate Prepared, and after applying the 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, heat treated at 400° C., Ar atmosphere for 1 hour, and then cathode (Example 2) was prepared.

[Example 3]

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

A microstructure in which the Si-based amorphous alloy is heat-treated at an inert gas atmosphere for 1 hour at a temperature of 550° C. to form an crystalline Si phase, which is an active metal having a size of 100 nm or less, uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. It has a negative electrode active material for a lithium secondary battery having a crystalline phase having a mixture of amorphous and crystalline.

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

[Example 4]

A single-roll liquid quenching and solidifying method in which an alloy containing Si, Al, Fe, and Cu is melted by an arc melting method or the like 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 ₁₇ Cu ₁ composition and Cu being forcibly dissolved in Fe was prepared.

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

Zirconium ball (Zr-ball) 200g, the negative electrode active material 5g, n-hexane (n-Hexane) mixed and then pulverized using a paint shaker (paint shaker) for 15 minutes to form a coin-shaped electrode plate Prepared, coated with 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, and then heat treated at 400° C. for 1 hour in an Ar atmosphere for 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 with a Si-based amorphous alloy in which crystalline and amorphous were mixed.

Zirconium ball (Zr-ball) 200g, the Si-based amorphous alloy 5g, n-hexane (n-Hexane) mixed and then pulverized using a paint shaker (paint shaker) for 15 minutes to form a coin of negative electrode active material powder An anode plate was prepared, and after applying the mixture of the anode active material powder, Ketjen Black as a conductive material, and PAI as a binder in a weight ratio of 87:3:10 to the electrode plate, heat treatment was performed at 400°C for 1 hour in an Ar atmosphere for the cathode ( Comparative Example 1) was prepared.

Figure 2 is a TEM photograph of the negative electrode active material for a lithium secondary battery of Example 3 prepared according to an embodiment of the present invention, Figure 3 is a negative electrode active material for a lithium secondary battery of Example 1 prepared according to an embodiment of the present invention It is a figure 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 is performed. 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, is uniformly dispersed and deposited on the inactive metal amorphous matrix phase or the inactive crystalline matrix phase 10.

Charge capacity, discharge capacity, and initial coulomb efficiency (ICE: initial discharge capacity of initial discharge capacity) of a negative electrode active material when charging and discharging is performed once after manufacturing a lithium secondary battery using the negative electrode of Examples 1 to 4 Results divided by () are shown in Table 2 below.

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
Coulomb
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

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

Referring to Table 2 and FIG. 4, the Si-based amorphous alloy in which Cu prepared by liquid quenching and coerced into Fe is heat-treated in a temperature range of 480°C to 750°C to perform the present invention having a crystalline and amorphous crystal structure In the case of the negative electrode made of the negative electrode active materials 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 as low as 47.5% and 65.8%. The retention rate after 30 cycles was also low at 42.8% and 65.2%. Particularly, in the case of Example 1 in which heat treatment was not performed, the initial coulomb efficiency due to the fact that the crystalline Si phase 20, which is an active metal having a size of 100 nm or less, was not formed on the inert metal amorphous matrix phase or the inert crystalline matrix phase 10 ( ICE: Initial Coulombic Efficiency (47.5%) was low, and after 30 cycles, the retention rate was also confirmed to be low at 42.8%.

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

In an embodiment of the present invention, an amorphous alloy can be produced reproducibly in a range of 30 m/s to 60 m/s in rotational speed of a copper wheel in melt spinning, which is a liquid quenching method, more preferably 40 m/s. Amorphous alloys can be produced with reproducibility at speed.

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

The above description of the present invention is for illustration only, and a person having ordinary knowledge in the technical field to which the present invention pertains can understand that it can be easily modified to 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 restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted to be included in the scope of the present invention.

Claims (13)

Preparing a molten metal by mixing the metals or alloys of Si, the additive metals M, Fe, and Cu at a ratio to become an alloy having a predetermined composition ratio and then melting them;
Solidifying the molten metal by liquid quenching and solidifying to produce a Si-based amorphous alloy in which Cu has a Si-M-Fe-Cu composition having a predetermined compositional ratio, and Cu is forcibly employed in Fe; And
By heat-treating the Si-based amorphous alloy, a negative electrode active material for a lithium secondary battery having a microstructure in which an crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix by Cu clustering is prepared. Comprising;
The M is a negative electrode active material for a lithium secondary battery manufacturing method for producing a negative electrode active material for a lithium secondary battery comprising at least one metal element selected from the group consisting of Al, Ti, W, Co, Cr, Ge or Ca. According to claim 1, The negative electrode active material for the lithium secondary battery,
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% of the negative electrode active material for a lithium secondary battery comprising Manufacturing method. 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%,
The M contains at least one metal element selected from the group consisting of Al, Ti, W, Co, Cr, Ge or Ca,
A negative electrode active material for a lithium secondary battery, characterized in that the crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. According to claim 3, The negative electrode active material,
A negative electrode active material for a lithium secondary battery, characterized in that it 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. The method of claim 3, wherein the crystalline Si phase is the active metal,
For lithium secondary battery, characterized in that copper is uniformly dispersed and precipitated on the inert metal amorphous matrix or inert crystalline matrix by Cu clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. Cathode active material. A negative electrode current collector and a negative electrode active material layer formed on at least one surface of the negative electrode current collector,
The negative electrode active material layer includes 75 wt% to 92 wt% of the negative electrode active material, 1 wt% to 10 wt% of the conductive material, and 7 wt% to 15 wt% of the binder,
The negative electrode active material is a negative electrode for a lithium secondary battery, characterized in that it comprises a crystalline Si phase that is a microstructure active metal having a size of 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. The method of claim 6, wherein the negative electrode active material,
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%,
The M is a negative electrode for a lithium secondary battery, characterized in that it comprises at least one metal element selected from the group consisting of Al, Ti, W, Co, Cr, Ge or Ca. The method of claim 6, wherein the negative electrode active material,
The Ti, W, Co, Cr, Ge or Ca negative electrode for a lithium secondary battery comprising at least one metal element selected from the group consisting of 0.1 at% to 5 at%. The method of claim 6, wherein the crystalline Si phase is the active metal,
For lithium secondary battery, characterized in that copper is uniformly dispersed and precipitated on the inert metal amorphous matrix or inert crystalline matrix by Cu clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by liquid quenching and solidification. cathode. In the lithium secondary battery comprising 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,
The negative electrode active material is a lithium secondary battery characterized in that it comprises a crystalline Si phase that is a microstructure active metal having a size of 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix phase or an inert crystalline matrix. The method of claim 10, wherein the negative electrode active material,
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%, wherein M is Al, Ti, A lithium secondary battery comprising at least one metal element selected from the group consisting of W, Co, Cr, Ge or Ca. The method of claim 11, wherein the negative electrode active material,
A lithium secondary battery comprising at least one metal element selected from the group consisting of Ti, W, Co, Cr, Ge or Ca at 0.1 to 5 at%. The method of claim 10, wherein the crystalline Si phase is the active metal,
Lithium secondary battery characterized by uniformly dispersed and deposited on the inert metal amorphous matrix or the inert crystalline matrix by copper clustering through heat treatment of a Si-based amorphous alloy in which Cu is forcibly employed by a liquid quenching solidification method. .

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