KR20200062451A - 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, 25-45 atom% of an added metal M, and 10-25 atom% of Fe. The added metal M includes one or more metal elements selected from a group consisting of Al and Ni, Ti, W, Co, Cr, Ge or Ca. A manufactured Si-based amorphous alloy is heat-treated in a preset condition to have a microstructure in which a crystalline Si phase which is an active metal having a size of 100 nm or less is uniformly dispersed and precipitated in 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′s active material during charging and discharging, thereby improving 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 microstructure in which the crystalline silicon phase, which is an active metal having a size of 100 nm or less uniformly dispersed and deposited uniformly on an inert metal amorphous matrix phase or an inert crystalline matrix phase containing silicon, aluminum and iron, is uniformly dispersed and precipitated The present invention relates to an anode active material for a lithium secondary battery, a cathode 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 degradation 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 and iron or an inert crystalline matrix Providing 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, wherein a microstructure in which a crystalline silicon phase, which is an active metal having a size of less than 100 nm uniformly dispersed and deposited in a matrix phase, is uniformly dispersed and deposited It is aimed at.

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 comprises the steps of mixing the metals or alloys of Si, the additive metals M and Fe at an alloying ratio of a predetermined composition ratio, and then melting them to prepare a molten metal; Solidifying the molten metal by liquid quenching and solidifying to produce a Si-based amorphous alloy having a Si-M-Fe composition of the predetermined composition ratio; And heat-treating the Si-based amorphous alloy under a predetermined condition, thereby forming an anode active material for a lithium secondary battery having a microstructure in which an active metal crystalline Si phase 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. It comprises a step of manufacturing;

The additive metal M is a method for producing a negative electrode active material for a lithium secondary battery, which comprises a negative electrode active material for a lithium secondary battery comprising at least one metal element selected from the group consisting of Al, Ni, Ti, W, Co, Cr, Ge or Ca. Gives

In an embodiment of the present invention, the anode active material for a lithium secondary battery may include Si at least 45 at% and less than 60 at%, added metal M 25at% to 45 at%, and Fe 10 at% to 25 at%.

In an embodiment of the present invention, the heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃.

In an embodiment of the present invention, the negative electrode active material prepared in the step of preparing the negative electrode active material is 0.1 at least one metal element selected from the group consisting of the Ni, Ti, W, Co, Cr, Ge or Ca 0.1 at % To 5 at%.

In order to achieve the above technical problem, another embodiment of the present invention includes Si at least 45 at% and less than 60 at%, added metal M 25at% to 45 at% and Fe 10 at% to 25 at%, and the addition The metal M contains Al and at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge, or Ca, and Si prepared by liquid quenching to have the Si-M-Fe composition. A negative electrode 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 precipitated on an inert metal amorphous matrix phase or an inert crystalline matrix by heat-treating the amorphous alloy at a predetermined temperature. Provide active material.

In the embodiment of the present invention, the negative electrode active material is characterized in that it contains at least one metal element selected from the group consisting of Ni, 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 heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃.

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 a conductive material and 7 wt% to 15 wt% of a binder, and the negative electrode active material is a Si-based amorphous alloy prepared by a liquid quenching method to have the Si-M-Fe composition. It provides a negative electrode for a lithium secondary battery comprising 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 by heat treatment at a temperature.

In the embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, the additive metal M 25at% to 45 at% and Fe 10 at% to 25 at%, the additive metal M is It may be 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, Ni, Ti, W, Co, Cr, Ge or Ca.

In the embodiment of the present invention, the negative electrode active material is characterized in that it contains at least one metal element selected from the group consisting of Ni, 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 heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃.

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 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 the Si- A microstructure active metal having a size of 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix by heat-treating a Si-based amorphous alloy prepared by liquid quenching to have an M-Fe composition at a preset temperature. It provides a lithium secondary battery characterized in that it comprises a crystalline Si phase.

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

In the embodiment of the present invention, the negative electrode active material is characterized in that it contains at least one metal element selected from the group consisting of Ni, 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 heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃.

As an effect of the present invention, after melting the Si, additive metal M and Fe mixture prepared by the rapid solidification method, the Si-based amorphous alloy prepared by the liquid rapid solidification method is heat treated under predetermined conditions to form the inactive metal amorphous matrix phase. Alternatively, a negative electrode active material including a crystalline Si phase that is an active metal uniformly dispersed and precipitated is produced by preferentially finely depositing a crystalline Si phase that is an active metal in an inert crystalline matrix phase.

As another effect of the present invention, the inert metal amorphous matrix phase or the inert crystalline matrix phase in the negative electrode active material may serve to suppress the volume expansion of the negative electrode active material while forming a structure that does not react with lithium ions, and the active metal is crystalline Since the 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 proceeds, the inert metal amorphous matrix phase or the inert crystalline matrix phase has a yield strength capable of withstanding the expansion stress of silicon particles due to intercalation of lithium ions, thereby charging and discharging. When proceeding, particle micronization due to volume expansion and contraction of the negative electrode active material may 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 83% or more. It is excellent, and can have a lifespan characteristic in which the capacity is maintained at least 78% 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 graph showing the diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Comparative Example 1 prepared according to an embodiment of the present invention.
Figure 3 is a diffraction pattern graph and TEM photograph 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, by using a rapid solidification process (Rapidly Solidification Process) and alloy design technology, suitable for wireless charging energy storage, securing a uniform size of Si precipitation phase, charging and discharging capacity, reproducibility such as cycle life, high capacity, It is intended to manufacture a high-power silicon alloy-based negative electrode active material.

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) , It is difficult to control the cooling rate of the molten metal), and the size of the silicon phase (Si phase) is uniformly and reproducibly dispersed in the matrix phase at a level of 100 nm or less to solve the volume expansion problem of the silicon material, and to precipitate Si There is no research report on the silicon alloy-based negative electrode active material having secured reproducibility such as securing a uniform size of the phase, charging and discharging capacity, and cycle life. In the present invention, the active metal crystalline Si phase is uniformly dispersed and deposited in the following two methods. It is to solve the problems of the prior art described above by providing a negative electrode active material having a microstructure.

First, Si-based amorphous alloy production using a rapid solidification process (Rapidly Solidification Process).

Second, the Si-based amorphous alloy is subjected to heat treatment under predetermined conditions to realize a microstructure in which the active metal Si phase is uniformly dispersed and deposited on 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, in one embodiment of the present invention, the metal or alloy of each of Si, additive metal M and Fe is mixed at a ratio to become an alloy having a predetermined composition ratio, and then melted to prepare a molten metal; Solidifying the molten metal by liquid quenching and solidifying to produce a Si-based amorphous alloy having a Si-M-Fe composition of the predetermined composition ratio; And heat-treating the Si-based amorphous alloy under a preset condition, thereby forming a negative electrode active material for a lithium secondary battery having a microstructure in which an active metal crystalline Si phase 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; manufacturing, the additive metal M is a negative electrode active material for a lithium secondary battery comprising at least one metal element selected from the group consisting of Al, Ni, Ti, W, Co, Cr, Ge or Ca It provides a method for manufacturing a negative electrode active material for a lithium secondary battery.

In an embodiment of the present invention, the anode active material for a lithium secondary battery may include Si at least 45 at% and less than 60 at%, added metal M 25at% to 45 at%, and Fe 10 at% to 25 at%.

In an embodiment of the present invention, the heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃.

In an embodiment of the present invention, the step of manufacturing the negative electrode active material. The anode active material may be a step performed to include 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge or Ca.

Another embodiment of the present invention, Si 45 at% or more and less than 60 at%, the additive metal M 25at% to 45 at% and Fe 10 at% to 25 at%, the additive metal M is Al, Ni, Contains one or more metal elements selected from the group consisting of Ti, W, Co, Cr, Ge, or Ca, and on the inert metal amorphous matrix or inert crystalline matrix by heat-treating the Si-based amorphous alloy at a predetermined temperature. It provides a negative electrode active material for a lithium secondary battery, characterized in that the crystalline Si phase, an active metal having a size of 100 nm or less, has a uniformly dispersed and precipitated microstructure.

In the embodiment of the present invention, the negative electrode active material is characterized in that it contains at least one metal element selected from the group consisting of Ni, 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 heat treatment under the preset conditions may be performed at 480°C to 750°C.

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. To 10 wt% and 7 wt% to 15 wt% of the binder, wherein the negative electrode active material is uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix by heat-treating a Si-based amorphous alloy at a preset temperature. It provides 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.

In the embodiment of the present invention, the negative electrode active material, Si 45 at% or more and less than 60 at%, the additive metal M 25at% to 45 at% and Fe 10 at% to 25 at%, the additive metal M is It may be 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, Ni, Ti, W, Co, Cr, Ge or Ca.

In the embodiment of the present invention, the negative electrode active material is characterized in that it contains at least one metal element selected from the group consisting of Ni, 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 heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃.

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 heat-treats the Si-based amorphous alloy at a preset temperature. Thereby provides a lithium secondary battery comprising 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.

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

In the embodiment of the present invention, the negative electrode active material is characterized in that it contains at least one metal element selected from the group consisting of Ni, 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 heat treatment under the preset conditions may be performed at 480°C to 750°C.

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 and Fe 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 molten metal Preparing a Si-based amorphous alloy having a Si-M-Fe composition of the predetermined composition ratio by solidifying the liquid by rapid quenching and solidification (S20), and heat-treating the Si-based amorphous alloy under predetermined conditions to form an inert metal amorphous matrix or A step (S) of preparing a negative electrode active material for a lithium secondary battery having a microstructure in which a crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniformly dispersed and deposited on an inert crystalline matrix, wherein the additive metal M is Al, Ni, 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 including at least one metal element selected from the group consisting of 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 30 at% to 45 at% and Fe 10 at% to 25 at%.

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 active metal crystalline Si phase is capable of reversibly reacting with lithium ions, it is directly related to the capacity of the negative electrode active material, and the inactive metal amorphous matrix phase or inactive crystalline matrix phase forms a structure that does not react with lithium ions while the volume of the negative electrode active material It can serve to inhibit swelling. 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, Si-type amorphous alloys having a Si-M-Fe composition, when heat treatment is performed in a specific temperature range, the active metal crystalline Si phase is uniformly dispersed and precipitated in an inert metal amorphous matrix phase or an inert crystalline matrix phase to form a microstructure. To form. In an embodiment of the present invention, the heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy may be performed at 480 ℃ ~ 750 ℃. This is because when the heat treatment is performed at a temperature of less than 480° C., the active Si phase is not precipitated, and thus the battery capacity is not expressed.

In the present invention, since Fe contained in the inert metal amorphous matrix phase or the inert crystalline matrix phase can play a role in improving the capacity of the negative electrode active material, capacity characteristics can be improved.

The inert metal amorphous matrix phase or the inert crystalline matrix phase includes a Si-based alloy comprising Si, additive metal M and Fe, as described above, wherein the Ni, Ti, W, Co, Cr, Ge or Ca 0.1 at% to 5 at% of one or more metal elements selected from the group may be included.

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 25at% to 45 at% and Fe 10 at% to 25 at%, and the added metal M is Al, Ni, Ti, W, It may include one or more metal elements selected from the group consisting of Co, Cr, Ge or Ca. In this case, at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge, or Ca may be included at 0.1 to 5 at%.

The crystalline Si phase, which is the active metal constituting the negative electrode active material, can react reversibly with lithium ions, and thus 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. 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 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%, Si amorphous alloy It is not produced, and since the content of components other than Si constituting the inert matrix 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 undesirable.

In general, the Si-based amorphous alloy prepared by liquid quenching and solidification method includes a crystalline Si phase that is an active metal uniformly dispersed and precipitated in an inert metal amorphous matrix phase or an inert crystalline matrix phase when heat treatment is performed under conditions having a specific temperature range. can do.

In the present invention, since Fe contained in the inert metal amorphous matrix phase or the inert crystalline matrix phase can play a role in improving the capacity of the negative electrode active material, capacity characteristics can be improved.

The inert metal amorphous matrix phase or the inert crystalline matrix phase may include Si, Al, and Fe, as described above, and may also include materials made of any one or more of Ni, Ti, W, Co, Cr, Ge, and Ca. It may be used as a component to improve the capacity characteristics or life characteristics, including 0.1 at% to 5 at% further.

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%, the additive metal M 25at% to 45 at% and Fe 10 at% to 25 at%, the additive metal M is Al and one or more metal elements selected from the group consisting of Ni, 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 inactive crystalline matrix phase and a crystalline Si phase that is an active metal. Since the active metal crystalline Si phase is capable of reversibly reacting with lithium ions, it is directly related to the capacity of the negative electrode active material, and the inactive metal amorphous matrix phase or inactive crystalline matrix phase forms a structure that does not react with lithium ions while the volume of the negative electrode active material It can serve to inhibit swelling. The active metal crystalline Si phase may be uniformly dispersed and deposited as a microstructure 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 may not be formed, and the content of components other than Si constituting the inert metal amorphous matrix phase or the inert crystalline matrix phase may be small, and thus the life improvement effect of the negative electrode active material for lithium secondary batteries may be difficult to appear, which is undesirable.

In general, when the Si amorphous alloy prepared by the liquid quenching method is subjected to heat treatment under a specific temperature condition, 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, is uniformly dispersed and precipitated. It can be made of a negative electrode active material containing a microstructure.

In the present invention, since Fe contained in the inert metal amorphous matrix phase or the inert crystalline matrix phase can play a role in improving the capacity of the negative electrode active material, capacity characteristics can be improved.

The inert metal amorphous matrix phase or the inert crystalline matrix phase includes a Si-based alloy including Si, an additive metal M and Fe, wherein the additive metal M is Al and the Ni, Ti, W, Co, Cr, Ge, or Ca may include at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge or Ca, at least one metal element selected from the group consisting of 0.1 at % To 5 at%, whereby it can be used as a component to improve 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 electrolytic solution 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%) Crystal phase Temperature, time Example 1 50 33 17 Amorphous Pristine Example 2 50 32 17 Amorphous+crystalline 450℃, 1hr Example 3 50 32 17 Amorphous+crystalline 550℃, 1hr Example 4 50 32 17 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]

An alloy containing Si, Al, and Fe is melted by an arc melting method or the like, and then applied to a single-roll quenching solidification method in which the melt is sprayed onto a copper roll rotating at a speed of 40 m/s, Si ₅₀ Al ₃₃ Fe ₁₇ A Si-based amorphous alloy having a composition was prepared.

Zirconium ball (Zr-ball) 200g, the Si-based amorphous alloy 5g, n-hexane (n-Hexane) after mixing for 15 minutes using a paint shaker (paint shaker) 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]

An alloy containing Si, Al, and Fe is melted by an arc melting method or the like, and then applied to a single-roll quenching solidification method in which the melt is sprayed onto a copper roll rotating at a speed of 40 m/s, Si ₅₀ Al ₃₃ Fe ₁₇ A Si-based amorphous alloy having a composition was prepared.

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

Zirconium ball (Zr-ball) 200g, the negative electrode active material 5g, n-hexane (n-Hexane) mixed and then crushed for 15 minutes using a paint shaker (paint shaker) having a crystalline phase with a mixture of amorphous and crystalline A negative electrode active material powder was used to prepare a coin-shaped electrode plate, and a mixture of the negative electrode active material powder, Ketjen Black as a conductive material, and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, followed by 400°C, Ar atmosphere A heat treatment was performed at 1 hour to prepare a negative electrode (Example 2).

[Example 3]

An alloy containing Si, Al, and Fe is melted by an arc melting method or the like, and then applied to a single-roll quenching solidification method in which the melt is sprayed onto a copper roll rotating at a speed of 40 m/s, Si ₅₀ Al ₃₃ Fe ₁₇ A Si-based amorphous alloy having a composition was prepared.

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

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

[Example 4]

An alloy containing Si, Al, and Fe is melted by an arc melting method or the like, and then applied to a single-roll quenching solidification method in which the melt is sprayed onto a copper roll rotating at a speed of 40 m/s, Si ₅₀ Al ₃₃ Fe ₁₇ A Si-based amorphous alloy having a composition was prepared.

Microstructure in which the Si-based amorphous alloy is heat-dissipated in an inert gas atmosphere furnace at a temperature of 700° C. for 1 hour to form an active metal crystalline Si phase uniformly dispersed and deposited 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 crushed for 15 minutes using a paint shaker (paint shaker) having a crystalline phase with a mixture of amorphous and crystalline A negative electrode active material powder was used to prepare a coin-shaped electrode plate, and a mixture of the negative electrode active material powder, Ketjen Black as a conductive material, and PAI as a binder in a weight ratio of 87:3:10 was applied to the electrode plate, followed by 400°C, Ar atmosphere Heat treatment at 1 hour to prepare a cathode (Experimental Example 4).

[Comparative Example 1]

An alloy containing Si, Al, and Fe is melted by an arc melting method or the like, and then applied to a single-roll quenching solidification method in which the melt is sprayed onto a copper roll rotating at a speed of 40 m/s, Si ₆₀ Al ₂₆ Fe ₁₄ A Si-based alloy having a composition was prepared.

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

Figure 2 is a graph showing the diffraction pattern showing the crystallinity of the negative electrode active material for a lithium secondary battery of Comparative Example 1 prepared according to an embodiment of the present invention.

From the X-ray diffraction analysis results of FIG. 2, it was confirmed that the negative electrode active material for lithium secondary battery of Comparative Example 1 had a crystal structure in which crystalline and amorphous mixtures were combined.

Figure 3 is a diffraction pattern graph and TEM photograph 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.

From the X-ray diffraction analysis results of FIG. 3 and the TEM photograph, it was confirmed that the negative electrode active material of Example 1 of the present invention was a Si-based amorphous alloy.

Charge capacity, discharge capacity, and initial coulomb efficiency (ICE: initial discharge capacity) of the negative electrode active material when charge and discharge were performed once after the lithium secondary battery was prepared using the negative electrode of Examples 1 to 4 and Comparative Example 1 Is divided by the initial charge capacity) and the results for the capacity retention rate after 30 cycles 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%) Crystal phase Temperature, time Initial charge
(mAh/g) Early
Discharge
(mAh/g) Early
Coulomb
efficiency(%) Volume
Retention rate
(30cy.%) Example 1 50 33 17 Amorphous Pristine 259.4 114.3 44.0 42.1 Example 2 50 32 17 Amorphous+crystalline 450℃, 1hr 221.0 94.5 42.7 38.1 Example 3 50 32 17 Amorphous+crystalline 550℃, 1hr 927.7 775.0 83.5 78.0 Example 4 50 32 17 Crystalline 700℃, 1hr 1032.2 877.3 84.9 80.0 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 Figure 4, Si-based liquid-cooled solidification method In the case of the negative electrode made of the negative electrode active materials of Examples 3 and 4 of the present invention having a crystalline and amorphous or crystalline crystal structure by heat-treating the amorphous alloy at a temperature of 480°C or higher, the initial Coulombic Efficiency (ICE) is 83.5% and It was high at 84.9%, and the retention rate after 30 cycles was also high at 78.0% and 80.0%.

On the other hand, in the case of Experimental Examples 1 and 2 in which heat treatment was performed at only 480° C., the initial Coulombic Efficiency (ICE) was low at 44.0% and 42.7%. After 30 cycles, the retention rate was also low at 42.1% and 38.1%.

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) was high at 90.2%, but it was confirmed that by forming a crystalline Si alloy, 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.

When the heat treatment is performed at a constant temperature after the production of the amorphous alloy, a negative electrode active material 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 phase or an inert crystalline matrix can be prepared with reproducibility. In addition, it can be determined that the reproducible negative electrode active material can have excellent lifespan characteristics that maintain capacity 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 (15)

Preparing a molten metal by mixing each of metals or alloys of Si, additive metals M and Fe 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 having a Si-M-Fe composition of the predetermined composition ratio; And
The Si-based amorphous alloy is heat-treated under predetermined conditions to prepare a negative electrode active material for a lithium secondary battery having a microstructure in which an active metal crystalline Si phase 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. Comprising;
The additive metal M is a method for producing a negative electrode active material for a lithium secondary battery, which comprises a negative electrode active material for a lithium secondary battery comprising at least one metal element selected from the group consisting of Al, Ni, 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 25at% to 45 at% and Fe 10 at% to 25 at%, characterized in that it comprises a negative electrode active material for a lithium secondary battery. The method of claim 1, wherein the heat treatment under the predetermined conditions of the step of manufacturing the Si-based amorphous alloy,
Method for manufacturing a negative electrode active material for lithium secondary charging, characterized in that is carried out in the range of 480 ℃ ~ 750 ℃. According to claim 1, The negative electrode active material prepared in the step of manufacturing the negative electrode active material,
Method for producing a 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 the Ni, Ti, W, Co, Cr, Ge or Ca 0.1 at% to 5 at%. Si at least 45 at% and less than 60 at%, including additive metal M 25at% to 45 at% and Fe 10 at% to 25 at%,
The additive metal M includes at least one metal element selected from the group consisting of Al, Ni, Ti, W, Co, Cr, Ge or Ca,
The crystalline Si phase, which is an active metal having a size of 100 nm or less, is uniform on the inert metal amorphous matrix phase or the inert crystalline matrix by heat-treating the Si-based amorphous alloy prepared by liquid quenching to have the Si-M-Fe composition at a preset temperature. A negative electrode active material for a lithium secondary battery, characterized in that it has a finely dispersed and precipitated microstructure. The method of claim 5, wherein the negative electrode active material,
The at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge, or Ca is 0.1 at% to 5 at%, the negative electrode active material for a lithium secondary battery. The method of claim 5, wherein the heat treatment under the preset conditions,
A negative electrode active material for a lithium secondary battery, characterized in that is carried out in the range of 480 ℃ ~ 750 ℃. 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 cathode active material is 100 nm uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix by heat-treating a Si-based amorphous alloy prepared by liquid quenching to have the Si-M-Fe composition at a predetermined temperature. A negative electrode for a lithium secondary battery, comprising a crystalline Si phase that is a microstructured active metal of the following size. The method of claim 8, wherein the negative electrode active material,
Si at least 45 at% and less than 60 at%, including additive metal M 25at% to 45 at% and Fe 10 at% to 25 at%,
The additive metal 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, Ni, Ti, W, Co, Cr, Ge or Ca. 10. The method of claim 9, The negative electrode active material,
A negative electrode for a lithium secondary battery, comprising 0.1 at% to 5 at% of at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge or Ca. The method of claim 8, wherein the heat treatment under the preset conditions,
A negative electrode for a lithium secondary battery, characterized in that is carried out in the range of 480 ℃ ~ 750 ℃. 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 anode active material is 100 nm or less uniformly dispersed and deposited on an inert metal amorphous matrix or an inert crystalline matrix by heat-treating a Si-based amorphous alloy prepared by liquid quenching to have the Si-M-Fe composition at a predetermined temperature. Lithium secondary battery, characterized in that it comprises a crystalline Si phase of the microstructure active metal of the size. The method of claim 12, wherein the negative electrode active material,
Si 45 at% or more and less than 60 at%, added metal M 25at% to 45 at% and Fe 10 at% to 25 at%, the added metal M is Al, Ni, Ti, W, Co, Cr, A lithium secondary battery comprising at least one metal element selected from the group consisting of Ge or Ca. The anode active material of claim 13,
The lithium secondary battery comprising at least one metal element selected from the group consisting of Ni, Ti, W, Co, Cr, Ge or Ca at 0.1 to 5 at%. The method of claim 12, wherein the heat treatment under the preset condition,
Lithium secondary battery, characterized in that carried out in the range of 480 ℃ ~ 750 ℃.

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