Electrode material containing silicon dioxide and single-walled carbon nanotubes

Abstract

An electrode material for a lithium-ion secondary battery contains active material particles including an alkali metal silicate or an alkaline earth metal silicate, a binder, and single-walled carbon nanotubes (SWCNTs).

Description

Technical Field

[0001] Aspects of the present disclosure relate to electrode materials including silicon and single-walled carbon nanotubes (SWCNTs), particularly anodes including the electrode materials, and lithium-ion batteries including the anodes.

Background Art

[0002] Lithium (Li)-ion electrochemical cells typically require materials that enable high energy density, high power density, and high cycle stability. Li-ion batteries are generally used in a variety of applications including household appliances, wearable computing devices, military mobile devices, satellite communications, spacecraft devices, and electric vehicles, and are particularly common for use in large-scale energy applications such as low-emission electric vehicles, renewable power plants, and stationary electric grids. Furthermore, lithium-ion batteries are at the forefront of next-generation wireless and portable communication applications. One or more lithium-ion batteries can be used to construct a battery that functions as a power source for any of these applications. However, as the number of applications requiring higher energy has exploded, research on lithium-ion batteries with even higher energy density, higher power density, higher rate charge and discharge capabilities, and longer cycle life has accelerated. Furthermore, with the increasing adoption of lithium-ion technology, applications are shifting to higher required currents, longer operating times, wider and higher power ranges, and smaller form factors, thus increasing the need to expand today's energy density and power density.

[0003] Anode active materials such as silicon are desirable alternatives to current graphite-based anodes because of their high lithium storage capacity, which can exceed seven times that of graphite (up to 3200 mAh / g). However, due to the large volume expansion of the alloy particles during lithiation, these anode materials typically exhibit very low cycle life due to mechanical stress, low Coulombic efficiency, and electrical disconnection. [Overview of the project] [Problems that the invention aims to solve]

[0004] Therefore, there is a need for advanced anode active materials for use in electrochemical batteries that incorporate carbon materials with defined quality characteristics that have a favorable effect on the cycleability of electrochemical batteries. [Means for solving the problem]

[0005] One embodiment of the present disclosure provides an electrode material for a lithium-ion secondary battery comprising an active material particle containing an alkali metal silicate or alkaline earth metal silicate, a binder, and single-walled carbon nanotubes (SWCNTs). In one embodiment, the electrode material comprises, with respect to the total weight of the electrode material, a combination of graphite particles and metal silicate particles in an amount of at least about 80% by weight, a binder in an amount of about 1% to about 5% by weight, and single-walled carbon nanotubes (SWCNTs) in an amount of about 0.05% to about 1% by weight. [Brief explanation of the drawing]

[0006] [Figure 1A] Figure 1A is a scanning electron microscope (SEM) image of active material composite particles according to various embodiments of the present disclosure. Figures 1B-1D are cross-sectional views of core particles that may be included in the composite particles of Figure 1A. [Figure 1B] Figure 1A is a scanning electron microscope (SEM) image of active material composite particles according to various embodiments of the present disclosure. Figures 1B-1D are cross-sectional views of core particles that may be included in the composite particles of Figure 1A. [Figure 1C] Figure 1A is a scanning electron microscope (SEM) image of active material composite particles according to various embodiments of the present disclosure. Figures 1B-1D are cross-sectional views of core particles that may be included in the composite particles of Figure 1A. [Figure 1D] Figure 1A is a scanning electron microscope (SEM) image of active material composite particles according to various embodiments of the present disclosure. Figures 1B-1D are cross-sectional views of core particles that may be included in the composite particles of Figure 1A. [Figure 2] Figures 2A-2C show the Raman spectra of graphite and various graphene-based materials. [Figure 3] This bar graph compares the Raman spectral ID / IG ratio of a typical carbon material and low-defect random-layer carbon. [Figure 4] Figures 4A-4C show the Raman spectra of electrode active materials containing core particles encapsulated by amorphous carbon, reduced graphene oxide (rGO), and low-defect randomized carbon, respectively. [Figure 5A] These are schematic cross-sectional views of a portion of the anode electrode in one embodiment, showing its state during manufacturing and after repeated charge-discharge cycles. [Figure 5B] These are schematic cross-sectional views of a portion of the anode electrode in one embodiment, showing its state during manufacturing and after repeated charge-discharge cycles. [Figure 6A] This graph shows the capacity retention of exemplary and comparative half-cells. [Figure 6B] This graph shows the capacity retention of exemplary and comparative half-cells. [Figure 6C] This graph shows the capacity retention of exemplary and comparative half-cells. [Modes for carrying out the invention]

[0007] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. References to specific examples and implementations are for illustrative purposes only and are not intended to limit the scope of the invention or the claims.

[0008] When an element or layer is described as being "on" another element or layer, or "connected" to it, it will be understood that there may be an element or layer that is directly on, directly "connected" to, or intervening to, the other element or layer. In contrast, when an element is described as being "directly on" another element or layer, or "directly connected" to it, there is no intervening element or layer. For the purposes of this disclosure, "at least one of X, Y, and Z" will be understood to mean X only, Y only, Z only, or any combination of two or more items of X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ).

[0009] With regard to the description of value ranges, unless it is clearly determined from the context otherwise, it is understood that each intermediate value between the upper and lower limits of a range, up to one-tenth of the lower limit unit, as well as any other specified or intermediate values ​​within the specified range, are included in the invention. The upper and lower limits of these smaller ranges may be independently included within the smaller range and are also included in the invention according to any particularly excluded limit values ​​within the specified range. If a specified range includes one or both of the limit values, the range that excludes one or both of these included limit values ​​is also included in the invention. It will also be understood that the term "approximately" may refer to a small measurement error of, for example, + / - 5% to 10%.

[0010] Words such as "then," "next," and "then" are not necessarily intended to limit the order of the steps, and these words may be used to guide the reader through the description of the method. Furthermore, references to claim elements in the singular form using articles such as "a," "an," or "the" should not be interpreted as limiting the element to the singular form.

[0011] "Electrode material" is defined as a material that can be constructed for use as an electrode in an electrochemical cell, such as a lithium-ion rechargeable battery. "Electrode" is defined as either the anode or the cathode of an electrochemical cell. "Composite electrode material" is also defined as containing active material particles that are conductive material, combined with one of the following: particles, flakes, spheres, plates, sheets, tubes, fibers, or a combination thereof. Particles, flakes, spheres, plates, sheets, tubes, fibers, or a combination thereof may further be flat, crushed, wrinkled, layered, woven, braided, or a combination thereof.

[0012] Conductive materials may be selected from the group consisting of conductive carbon-based materials, conductive polymers, graphite, metal powders, nickel, aluminum, titanium, stainless steel, and any combination thereof. Conductive carbon-based materials may further include graphite, graphene, diamond, pyrolytic graphite, carbon black, low-defect random-layer carbon, fullerene, or one of these combinations. "Electrode material mixture" is defined as a combination of materials such as material particles (either electrochemically active and conductive composite materials or any combination thereof), binders, and non-crosslinked and / or crosslinked polymers, which are mixed together for use in forming electrodes of an electrochemical cell. "Electrochemically active material," "electrode active material," or "active material" is defined herein as a material that inserts and releases ions, such as ions in an electrolyte, to store and release potential. Furthermore, the terms "insertion and release" may be understood as intercalating and deintercalating or lithiating and delithiating ions. Therefore, the processes of ion insertion and release can also be understood as intercalation and deintercalation, or lithiation and delithiation. Thus, “active material,” “electrochemically active material,” or “active material particle” is defined as a material or particle that can undergo repeated intercalation and deintercalation of ions, or lithiation and delithiation of lithium.

[0013] Where used herein, a secondary electrochemical cell is a rechargeable electrochemical cell or battery. “Capacity” is defined herein as a measure of the charge stored by a battery, determined by the mass of the active material contained within the battery, and represents the maximum amount of ampere-hours (Ah) of energy that can be extracted from the battery at the rated voltage. Capacity can also be defined by the following equation: Capacity = Energy / Voltage or Current (A) × Time (h). “Energy” is mathematically defined by the following equation: Energy = Capacity (Ah) × Voltage (V). “Specific capacity” is defined herein as the amount of charge that can be delivered per unit mass or unit volume of active electrode material in a given time. Specific capacity may be measured in units of weight, e.g., (Ah) / g, or in units of volume, e.g., (Ah) / cc. Specific capacity is defined by the following formula: Specific capacity (Ah / kg) = Capacity (Ah) / Mass (kg). “Rate capability” is the ability of an electrochemical cell to receive or deliver a certain amount of energy within a given period of time. Alternatively, "rate capability" refers to the maximum continuous or pulsed energy that a battery can deliver per unit of time.

[0014] "C-rate" is defined herein as a measure of the rate at which a battery discharges relative to its maximum nominal capacity. For example, a current rate of 1C means that the discharge current discharges the entire battery in 1 hour, a current rate of C / 2 means that the battery is completely discharged in 2 hours, and a 2C rate means that the battery is completely discharged in 0.5 hours. "Power" is defined as the rate of energy transfer measured in watts (W). Power is the product of the voltage (V) across the battery or cell and the current (A) flowing through the battery or cell. Mathematically, "C-rate" is defined as C-rate (reverse time) = current (A) / capacity (Ah) or C-rate (reverse time) = 1 / discharge time (h). Power is defined by the following formula: Power (W) = energy (Wh) / time (h) or Power (W) = current (A) × voltage (V). Coulomb efficiency is the efficiency of charge transfer within an electrochemical cell. Coulomb efficiency is the ratio of charge output to charge input by the battery.

[0015] Significant development in both commercial and academic settings has focused on designing systems that minimize or adapt to the total volume swelling of alloy particles and associated electrochemical losses. This has typically been approached in two ways: at the particle level, designing particle structures that confine swelling to small areas to prevent particle fracture and electrical disconnection; and at the electrode level, designing polymer matrices and conductive networks that can adapt to the volume swelling of lithium storage materials while maintaining mechanical and electronic integrity during repeated charge-discharge operations of Li-ion batteries.

[0016] Reputable techniques for stabilizing the cycle lifetime of anode alloy active materials such as silicon involve mixing, encapsulation, or other incorporation with various carbon materials to create an electron-conducting surface and facilitate overall electron conduction across the electrode particle network. These include CVD amorphous carbon coatings, graphene wrapping, and physical mixing with graphite, conductive carbon, and carbon nanoparticles. However, due to their rigidity and lack of long-range order, the active material can still swell, potentially leading to loss of storage capacity and trapped lithium as particles remain isolated.

[0017] Various embodiments of this disclosure provide anode materials for Li-ion batteries comprising active material particles containing alkali metal silicates or alkaline earth metal silicates, and single-walled carbon nanotubes (SWCNTs) that provide long-range conductivity in the active material particle network, enabling increased cycle life stability despite the inherent swelling associated with lithium storage metal alloy particles.

[0018] SiO material Silicon and silicon alloys, when incorporated into the electrodes of electrochemical cells, can significantly increase battery capacity. Silicon and silicon alloys are often incorporated into electrodes containing graphite, graphene, or other carbon-based active materials. Examples of electrodes containing carbon-based materials and silicon are described in U.S. Patents 8,551,650, 8,778,538, and 9,728,773 by Kung et al., and U.S. Patents 10,135,059 and 10,135,063 by Huang et al., all of which are fully incorporated herein by reference.

[0019] In this specification, "SiO" material may refer to silicon and oxygen-containing materials. SiO materials are of interest for use in the anode electrodes of lithium-ion batteries due to their high theoretical energy and power densities. However, the use of currently available commercial SiO materials has been limited due to the low first-cycle efficiency and high irreversibility of SiO materials. This low first-cycle efficiency is a major drawback of the high irreversibility of the SiO matrix. + It is due to a reaction.

[0020] Irreversible Li with silicon dioxide +To reduce the reaction, various embodiments include metallized silicon oxide (M-SiO) materials. Herein, M-SiO material may refer to an active material that reacts directly with a metal-containing precursor, such as an alkali and / or alkaline earth metal-containing precursor, such as a lithium-containing precursor and / or a magnesium-containing precursor, to form a silicon metallide and oxygen-containing phase before being used as an active material in a battery and / or before undergoing charge and discharge reactions. In one embodiment, all or part of the metallized metal remains in the active material and does not intercalate (i.e., not insert) or deintercalate during battery charging and discharging. However, in some embodiments, the M-SiO material may include an SiO material metallized to include other suitable alkali and / or alkaline earth metals, such as sodium, potassium, calcium, etc. For example, in some embodiments, the M-SiO material may be metallized to include magnesium, lithium, sodium, potassium, calcium, or any combination thereof. Preferably, the M-SiO material may refer to lithium metallized SiO (LM-SiO) material and / or Mg metallized SiO (MM-SiO) material.

[0021] Electrode materials containing M-SiO active material have been found to exhibit increased first-cycle efficiency (FCE) compared to unmetallated SiO materials. Unfortunately, M-SiO materials have been found to have serious electrical disconnection and rapid capacity loss problems, often resulting in a capacity drop of over 90% within 20 cycles. Coating M-SiO materials with carbon and / or other materials, and / or blending M-SiO materials with graphite, has been found to slightly reduce the electrical disconnection and capacity loss of the active material, delaying the capacity drop of over 50% to approximately 50 cycles, but this still represents very insufficient cycle stability for commercial applications. Overall, current M-SiO materials do not exhibit sufficient electrical stability for commercialization.

[0022] FIG. 1A is a scanning electron microscope (SEM) image of active material particles 100 according to various embodiments of the present disclosure, and FIGS. 1B-1D are cross-sectional views of core particles 102A-102C that may be included in the active material particles 100 of FIG. 1A. Referring to FIGS. 1A and 1B, the active material particles 100 include core particles 102 containing an electrochemically active material and a graphene-containing coating 110 that coats and / or encapsulates the core particles 102.

[0023] In a preferred embodiment, the core particles 102 include an M-SiO material. Accordingly, the active material particles 100 are described below with respect to the core particles 102 including the M-SiO material.

[0024] The active material particles 100 and / or the core particles 102 can have an average particle size in the range of from about 1 μm to about 20 μm, for example, from about 2 μm to about 15 μm, from about 3 μm to about 10 μm, from about 3 μm to about 7 μm, or about 5 μm. The core particles 102 can include an M-SiO material containing metallized silicon species and silicon (e.g., crystalline silicon and / or amorphous silicon). The metallized silicon species can include metallized silicides and metallized silicates. In some embodiments, the M-SiO material can also include silicon oxide (SiO x [where x is in the range from 0.8 to 1.2, for example, from 0.9 to 1.1]). In various embodiments, the M-SiO material can include lithiated silicon species. As used herein, "lithiated silicon species" includes lithium silicide (Li x Si, 0 < x < 4.4), and / or can include one or more lithium silicates (such as Li2Si2O5, Li2SiO3, and / or Li4SiO).

[0025] Referring to FIG. 1B, in some embodiments, the active material particles 100 can include a heterogeneous core particle 102A that includes an M-SiO material including a plurality of silicon-containing material phases 104, 106, 108. For example, the phases 104, 106, 108 can independently be crystalline silicon, silicon oxide (e.g., SiO x[where x ranges from 0.8 to 1.2, for example, from 0.9 to 1.1], and / or may contain lithiated silicon species. However, in some embodiments, the core particle 102 may be a substantially uniform particle lacking distinct phases but containing silicon, oxygen, and lithium.

[0026] Referring to FIG. 1C, in some embodiments, the active material particle 100 may include a core particle 102B that includes a primary phase 120 in which a crystalline silicon region 122 is dispersed as a secondary phase. For example, the primary phase 120 may include lithiated silicon species, such as lithium silicate species, and particularly Li2Si2O5. In other embodiments, the primary phase 120 may include magnesiated silicon species, such as magnesium silicate species, and particularly MgSiO3, Mg2SiO4, combinations thereof, etc. The crystalline silicon region 122 may include crystalline silicon nanoparticles having a particle size of less than 100 nm. For example, the crystalline silicon region 122 may have an average particle size ranging from about 3 nm to about 60 nm. In one embodiment, most of the crystalline silicon region 122 may have an average particle size ranging from about 5 nm to about 10 nm, and the remainder of the crystalline silicon region 122 may have an average particle size ranging from about 10 nm to about 50 nm.

[0027] Referring to FIG. 1D, in some embodiments, the active material particle 100 includes a primary phase 120 containing an M-SiO material, a crystalline silicon region 122, and SiO dispersed in the primary phase 120 as a secondary phase x region 124 (e.g., SiO x [where x ranges from 0.8 to 1.2, for example, from 0.9 to 1.1]), and may include a core particle 102C. For example, the primary phase 120 may include lithiated silicon species, such as lithium silicate species, and particularly Li2Si2O5, the crystalline silicon region 122 may include crystalline silicon nanoparticles, and SiO x region 124 may include SiO x phase and / or nanoparticles. The crystalline silicon region 122 and SiO x region 124 may have a particle size of less than about 100 nm. For example, the crystalline silicon region 122 and SiOx Region 124 may have an average particle size ranging from approximately 3 nm to approximately 60 nm, for example, from approximately 5 nm to approximately 50 nm.

[0028] In various embodiments, the core particles 102 may represent about 80% to about 99.5% by weight of the total weight of the active material particles 100, for example, about 90% to about 99% by weight, including about 90% to about 95% by weight. In some embodiments, the M-SiO material may contain about 40 atomic% to about 5 atomic%, for example, 20 atomic% to about 10 atomic%, or about 15 atomic% of lithium silicon species. In some embodiments, the M-SiO material of the core particles 102A may contain about 60 atomic% to about 95 atomic%, for example, about 80 atomic% to about 90 atomic%, or about 85 atomic% of silicon and SiO x This may include: The M-SiO material of the core particle 102 may have a silicon-to-oxygen atomic weight ratio ranging from about 1.25:1 to about 1:1.25, for example, from about 1.1:1 to about 1:1.1, or about 1:1. In some embodiments, the M-SiO material of the core particle 102 may have crystalline silicon and SiO with nearly equal atomic weights. x It may include.

[0029] During the initial and / or subsequent charging reactions, the composition of the M-SiO material in core particle 102A may change due to lithiumization and / or other reactions. For example, Si and SiO x Lithium is converted to Li x A Si region can be formed. Furthermore, some SiO x This can form inert species such as lithium silicate and Li2O.

[0030] In various embodiments, the coating 110 may be in the form of a shell that completely encapsulates the core particles 102, as shown in Figures 1B-1D. However, in some embodiments, the coating 110 may only partially encapsulate some or all of the core particles 102. In some embodiments, the coating 110 may represent about 0.5% to about 20% by weight relative to the total weight of the active material particles, for example, about 1% to about 10% by weight, or about 5% to about 10% by weight of the total weight of the active material particles 100.

[0031] Randomized carbon In some embodiments, the coating 110 may include a flexible, highly conductive graphene material, such as graphene, graphene oxide, partially reduced graphene oxide, or a combination thereof. For example, the coating 110 may preferably include a flexible, highly conductive graphene material having low-defect randomization properties, which may be referred to as randomized carbon. The low-defect randomized carbon may also be in the form of plates containing graphene material such as graphene, graphene oxide, or reduced graphene oxide, ranging from one to about ten layers. In some embodiments, the low-defect randomized carbon may contain at least 90% by weight of graphene, for example, from about 90% to about 100% by weight. The graphene material may further include powder, particles, single-layer sheets, multilayer sheets, flakes, plates, ribbons, quantum dots, tubes, fullerenes (hollow graphene spheres), or a combination thereof.

[0032] The randomly layered carbon may also be in the form of sheets or plates that partially overlap to replicate a larger single-sheet structure. In some embodiments, the plate has two or more layers of graphene-based material. In some embodiments, the plate may have a sheet size that is 15 μm or less on average. In some embodiments, the plate may have a sheet size that is 1 μm or less on average. In some embodiments, the randomly layered carbon-based material plate may have a small thickness. In some embodiments, the small thickness of the randomly layered carbon-based material plate may be 1 μm or less on average. In some embodiments, the small thickness of the randomly layered carbon-based material plate may be 100 nm or less on average.

[0033] In various embodiments, the coating 110 may be in the form of a shell that completely encapsulates the particles 100, as shown in Figure 1B. However, in some embodiments, the coating 110 may partially encapsulate some or all of the active material particles 100. In some embodiments, the coating 110 may represent about 0.5% to about 20% by weight of the total weight of the particles 100 and the coating 110, for example, about 1% to about 10% by weight, or about 5% to about 10% by weight.

[0034] The coating 110 ensures that the core particles 102 circulate uniformly throughout all three dimensions due to their conductivity (movement of electrons and Li ions in and out of the structure), thereby minimizing the stress exerted on and on the core particles and minimizing particle fracture. Furthermore, if the particles 100 do fracture, the flexible coating 110 acts to electrically connect the fractured silicon oxide material, maintaining the overall integrity of the particles 100, thereby resulting in significantly improved electrochemical performance.

[0035] Figures 2A, 2B, and 2C show the Raman spectra of graphite and various graphene-based materials. Graphite and graphene materials are approximately 1340 cm⁻¹. -1 , 1584cm -1 , and 2700cm -1 It is well established that it has a distinctive peak at 1340 cm. -1 The peak at 1584 cm is shown in Figure 2C and is characterized as the D band. -1 The peak at is shown in the spectra of Figures 2A and 2C and is characterized as a G band, which is sp 2 It arises from vibrational modes represented by the stretching of the C=C bonds in all pairs of hybridized carbon atoms. The D band originates from hybrid vibrational modes associated with the edges of graphene, indicating the presence of defects or symmetry breaking within the graphene structure. 2700 cm -1The peak at is shown in Figure 2B and is characterized as a 2D band, which arises from a double resonance process based on the interaction between stacked graphene layers. The appearance of a double peak at the 2D wavenumber breaks the peak's symmetry and indicates AB stacking order between graphene planes in graphite and graphite derivatives, e.g., between nanoscales. The 2D1 peak shown in Figure 1B is suppressed when the AB stacking order of the turbid multilayer graphene particles is disturbed. The positions of the G band and 2D band are used to determine the number of layers in the material system. Thus, Raman spectroscopy provides scientific clarity and definition for electrochemical cell carbon material additives and provides a fingerprint for the correct selection as an additive for active material electrode compositions. As shown, this definition provides a fingerprint for low-defect turbid carbon of this application. It is this low-defect turbid carbon that provides superior electrochemical cell performance when used as an additive to electrochemical cell electrode active material mixtures.

[0036] Figure 3 shows the carbon additives (i.e., reduced graphene oxide or amorphous carbon) commonly used in conventional electrode active material mixtures. D / I G The ratio is described in comparison to the low-defect, randomly layered carbon of this application.

[0037] Reduced graphene oxide (rGO) is another form of carbon often referred to as graphene in this industry, but its final structure and manufacturing process are unique. Graphene oxide is typically first manufactured using a modified Hummers process, which involves oxidizing a graphite material and exfoliating it into a single layer or plate containing several carbon layers that may contain various functional groups, including but not limited to hydroxyl, epoxide, carbonyl, and carboxyl. These functional groups are then removed by chemical or thermal treatments that convert the insulating graphene oxide into conductive reduced graphene oxide. Reduced graphene oxide is similar to graphene in that it consists of a single layer of carbon atom lattices, but differs in that it has a mixed sp2 and sp3 hybridization, residual functional groups, and a defect density that is often increased due to the manufacturing and reduction processes. Reduced graphene oxide is shown in the first bar of Figure 3, with a density of 0.9 I D / I G It has a ratio.

[0038] Amorphous carbon is often used as an additive or surface coating for both the anode and cathode material mixtures of electrochemical cells to enhance electrode conductivity. Typically, amorphous carbon is produced using a chemical vapor deposition (CVD) process, in which hydrocarbon feedstock gases are flowed into a sealed container and carbonized on the surface of the desired powder material at high temperatures. This pyrolysis process can provide a thin amorphous carbon coating on the order of several nanometers in thickness, completely free of sp2 hybridization as seen in crystalline graphene-based materials. Amorphous carbon is shown in the third bar of Figure 3, with a concentration greater than 1.2 I D / I G It has a ratio.

[0039] Low-defect, randomly layered carbon, also known as graphene, possesses unique properties stemming from its manufacturing process. One common method for producing this material is a plasma-based CVD process, in which hydrocarbon feedstock gases are supplied through an inert gas plasma in the presence of a catalyst capable of forming nuclei for graphene-like carbon structures. By controlling the manufacturing parameters, carbon materials with multiple layers and no AB stacking order between lattices can be produced. These carbon materials typically have a highly ordered sp2 carbon lattice with a low defect density.

[0040] The low-defect turbid carbon of this disclosure is shown in the second bar in the center of Figure 3. The Raman spectrum of the low-defect turbid carbon additive of this application is shown in terms of the intensity ratio of the D band to the G band (I D / I G ) and the intensity ratio between the 2D band and the G band (I 2D / I G ) is derived from. D , I 2D , and I G This is represented by the integrated intensity of each of them. Low I D / I G The ratio indicates a low-defect material. The low-defect random-layer carbon material of the present invention has ratios of 1580 and 1600 cm². -1 I in wavenumber within the range between G , 1330 and 1360 cm -1 I in wavenumber within the range between D I is determined by Raman spectroscopy using and measured with an incident laser wavelength of 532 nm, and is greater than 0 and less than or equal to approximately 0.8. D / I G It has a ratio of approximately 0.4 or more I 2D / I G It exhibits a ratio. 2D / I G For reference regarding ratios, typically, it is about 2 to 1. 2D / I G The ratio is related to single-layer graphene. I is less than approximately 0.4 2D / I GThe ratio is typically related to bulk graphite consisting of numerous AB stacked graphene layers. Therefore, for the low-defect random-layer carbon material of this disclosure, the ratio is approximately 0.4 or higher. 2D / I G The ratio indicates a small number of layers, less than 10. Low-defect, randomly layered carbon materials with fewer layers exhibit an even greater lack of AB stacking order between graphene layers (i.e., random layering). The random layering nature or lack of AB stacking on these graphene surfaces indicates I 2D This is indicated by the symmetry of the peaks. The symmetry of the 2D peaks distinguishes randomized graphene layered materials from AB stacked graphene layered materials, which, in contrast to the orderliness of layered stacking, indicates the disorder of rotational stacking.

[0041] Highly ordered AB stacked carbon materials still exhibit 2D peaks, but these 2D peaks exhibit doublets that break the peak's symmetry. This symmetry breaking is present in both multi-layer AB stacked graphene and many-layer graphite. Therefore, regardless of the number of graphene layers present in the material, the 2D peak, a very strong indicator of the presence of stacked order, is important when selecting graphene or graphene-based additives. What distinguishes the low-defect random-layered carbon of this disclosure from all other graphene or graphene-based additives used to date is the rotational disorder of the stacking in this carbon. This is because the rotational disorder of the low-defect random-layered carbon stack of this application provides flexibility to the carbon-based particles of this application, thereby enabling these carbon-based particles to provide and maintain contact with the active core particles of the composite particles constituting the electrodes of an electrochemical cell. As a result, an electrochemical cell with increased cycle life, better cycle life stability, improved energy density, and better high-rate performance is obtained.

[0042] Figures 4A-4C show the Raman spectra of active material formulations containing SiO particles encapsulated or coated with carbon materials. Figure 4A is a graph of the Raman spectrum of an active material formulation containing SiO core particles coated with amorphous carbon material. Figure 4B is a graph of the Raman spectrum of an active material formulation containing SiO core particles encapsulated with rGO. Figure 4C is a graph showing the Raman spectrum of an active material formulation containing core particles encapsulated with low-defect random-layer carbon. Layer thickness (wavelength 2700 cm) -1 (Size, shape, and location of nearby 2D peaks) and disorder (wavelength 1340 cm) -1 Each spectrum differs because the size of the nearby D peaks is different.

[0043] The preparation of Raman analysis samples involved taking small aliquots of powders such as active material powder, composite material powder, and carbon material powder, and placing these powders individually into clean glass vials. The sample powders were rinsed with methanol. The powder / methanol solution was then vortexed briefly and sonicated for about 10 minutes. The suspension was then transferred to a glass slide using a micropipette. The slide was then completely air-dried before performing the analysis.

[0044] The Raman spectroscopy described in this application is performed using confocal Raman spectroscopy in a Bruker Senterra Raman system under the following test conditions: 532 nm laser, 0.02 mW, 50x objective lens, 90 sec integration time, 50 × 1000 μm aperture, and 9–18 cm². -1 Three co-dopsy tests (three Raman spectroscopy runs on samples) were performed using the following resolution. For reference, the D band is not active in Raman scattering of perfect crystals. The D band becomes Raman active in defective graphite materials by a defect-induced double-resonance Raman scattering process involving π-π electron transitions. The intensity of the D band relative to the G band increases with the degree of disorder. Therefore, intensity I D / I G The graphene material can be characterized using ratios.

[0045] The D and G bands of amorphous carbon shown in Figure 4A are both more intense than those of reduced graphene oxide (rGO) in Figure 4B, or the D and G bands of turbid carbon in Figure 4C. Amorphous carbon has a considerably higher I₂ intensity than rGO and turbid carbon. D / I G It also exhibits a ratio of (1.25). The suppressed G-band intensity of amorphous carbon compared to the D-band intensity reflects the lack of crystallinity within its carbon structure (also known as the properties of graphite). The higher D-peak intensity than the G-peak intensity is caused by a greater amount of defects in the amorphous carbon network. Therefore, the spectrum of amorphous carbon exhibits lower crystallinity and a much higher degree of disorder in its graphite network compared to more crystalline carbons such as graphene, graphene oxide, and rGO. Furthermore, its D-peak intensity is higher compared to the G-peak of rGO, as are the D and G-peak intensities of turbid carbon and I D / I G I of rGO is higher compared to the ratio D / I G The ratio (almost 2 times) indicates that rGO has more defects than the torn carbon of this application.

[0046] Table 1 below shows the details of the Raman spectra in Figures 4A-4C.

[0047] [Table 1]

[0048] Careful examination of these spectra reveals that as disorder increases, the D band broadens and the relative intensity of the band changes. In the case of the amorphous carbon-coated sample, the high intensity (6194.8) and broad D peak indicate a large number of defects. A lower G peak intensity (4908.2) than the D peak (6194.8) indicates a lack of crystallinity. The D peak intensities (9115.5) and G peak intensities (10033.3) of the rGO-encapsulated sample are very similar. However, it is noteworthy that the D peak intensity (9115.5) of the rGO sample is considerably higher than that of the chaotic carbon sample (2915.3), indicating that the rGO sample has a considerably higher defect density than the chaotic carbon sample. Similarly noteworthy are the G bands of the amorphous carbon and rGO samples at a wavelength of 1589.4 cm², respectively. -1 and 1597.82cm -1 wavelength 1584cm -1 It is shifted to the right, and the G-band of the turbid carbon sample is 1581.32 cm⁻¹. -1 1584cm -1 It is slightly to the left of the wavelength. Importantly, unlike amorphous carbon and rGO samples, the randomized carbon (in this case, the graphene sample) shows little, if any, positional shift, which reflects fewer defects within it, making the randomized carbon sample very similar to an almost "perfect" randomized carbon material.

[0049] electrode material Various embodiments of this disclosure provide electrode materials for lithium-ion batteries, and in particular anode electrode compositions. As shown in Figure 5A, the electrode material may comprise an active material, a binder (not shown), and single-walled carbon nanotubes (SWCNTs) 120. The active material may comprise the active material particles 100 described above and optionally additional graphite particles 130. In some embodiments, the electrode material may optionally comprise a conductive additive such as carbon black particles 140. The active material particles 100 and graphite particles 130 may be mixed with each other. The carbon black particles 140 may be smaller than the active material particles 100 and graphite particles 130 (i.e., have a smaller diameter) and may be located between and / or on the surface of the active material particles 100 and / or graphite particles 130. The SWCNTs 120 may extend between the mixture of active material particles 100 and graphite particles 130 and provide long-range conductivity across multiple active particles (100, 130).

[0050] As shown in Figure 5B, after numerous charge-discharge cycles, the silicon oxide particles 100 and graphite particles 130 may swell and push each other away. However, due to its long length and high aspect ratio, the SWCNT 120 still brings multiple active material particles 100 and graphite particles 130 into contact and electrically connects them. Therefore, the SWCNT 120 is thought to result in a percolation network of conductive links between active particles (e.g., a web or mesh exceeding the percolation threshold) that provides sufficient conductivity to the anode electrode.

[0051] The electrode material may contain at least 80 wt% of active material, for example, at least 90 wt%, at least 94 wt%, for example, 90 to 96.5 wt% of active material. The active material may contain a mixture of active material particles 100 and optionally graphite particles 130. For example, the active material may contain M-SiO from about 5 wt% to about 50 wt%, for example, from about 10 wt% to about 30 wt%, from about 15 wt% to about 25 wt%, and graphite from about 95 wt% to about 50 wt%, for example, from about 90 wt% to about 70 wt%, from about 85 wt% to about 75 wt%. In some preferred embodiments, the active material may contain less than 50 wt% of M-SiO and more than 50 wt% of graphite. Thus, the active material may contain more graphite particles 130 by weight than active material particles 100.

[0052] The active material particles 100 may include a silicon and metal silicate phase and optionally the silicon oxide phase described above. The active material particles 100 may include an optional carbon coating 110, or the carbon coating 110 may be omitted.

[0053] The active material particles 100 may have an average particle size ranging from approximately 1 μm to approximately 20 μm, for example, from approximately 1 μm to approximately 10 μm, from approximately 3 μm to approximately 7 μm, or approximately 5 μm. The active material particles 100 are approximately 0.5 m 2 From / g to approximately 30m 2 Up to / g, for example, about 1m 2 From / g to approximately 20m 2 It may have a surface area in the range of up to / g, which is approximately 5m 2 From / g to approximately 15m 2 Includes up to / g.

[0054] The graphite may include synthetic or naturally occurring graphite particles 130. The graphite may have an average particle size ranging from about 2 μm to about 30 μm, for example, from about 10 μm to about 20 μm, including from about 12 μm to about 18 μm. In one embodiment, the average particle size of the graphite particles 130 may be larger than the average particle size of the silicon oxide particles 100. The graphite particles 130 are about 0.5 m2 From / g to approximately 2.5m 2 Up to / g, for example, about 1m 2 From / g to approximately 2m 2 The graphite particles 130 may have a surface area in the range of up to / g. The graphite particles 130 may be larger than the silicon oxide particles 110.

[0055] The electrode material may include any suitable electrode material binder (not shown in Figures 5A and 5B for clarity). For example, the electrode material may include polymer binders such as polyvinylidene fluoride (PVDF), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), lithium polyacrylate (LiPAA), or combinations thereof. In some embodiments, the binder may include a combination of CMC and SBR, where CMC has a molecular weight ranging from 250 to 850 g / mol and a degree of substitution ranging from 0.65 to 0.9.

[0056] In various embodiments, the electrode material may contain a binder in an amount ranging from about 1% to about 5% by weight, or from about 2% to about 3% by weight.

[0057] SWCNT120 may have an average length greater than approximately 1 μm. For example, SWCNTs may have an average length ranging from approximately 1 μm to approximately 500 μm, for example, from approximately 1 μm to approximately 10 μm. SWCNTs may have an average diameter ranging from approximately 0.5 nm to approximately 2.5 nm, for example, from approximately 1 nm to approximately 2 nm.

[0058] SWCNT120 is 1580~1600cm -1 I related to Raman intensity at wavenumber G , and 1330~1360cm -1 I related to Raman intensity at wavenumber D Determined by Raman spectroscopy using a 633 nm incident laser wavelength, I is greater than approximately 5, for example, greater than approximately 6 or greater than approximately 10. G / I D It may have a ratio.

[0059] In various embodiments, the electrode material may include SWCTN in amounts ranging from about 0.05% by weight to about 1% by weight, for example, from about 0.075% by weight to about 0.9% by weight, from about 0.08% by weight to about 0.25% by weight, or about 0.1% by weight.

[0060] Conductive additives (i.e., conductive agents) may include carbon black (e.g., KETJENBLACK or Super-P carbon black), low-defect random-layer carbon, acetylene black, channel black, furnace black, lamp black, thermal black, or combinations thereof. Optionally, conductive additives may include metal powders, fluorocarbon powders, aluminum powders, nickel powders; nickel flakes, conductive whiskers, zinc oxide whiskers, potassium titanate whiskers, conductive metal oxides, titanium oxide, conductive organic compounds, conductive polyphenylene derivatives, conductive polymers, or combinations thereof.

[0061] In various embodiments, the electrode material may contain a conductive additive (i.e., a conductive agent) selected from carbon black, a conductive polymer, a metal powder, or any combination thereof, in amounts from 0 to about 5% by weight, for example from about 0.1% to about 5% by weight, for example from about 0.25% to about 3% by weight, for example from about 0.5% to about 1.5% by weight, or about 1% by weight. In some embodiments, the conductive additive may preferably contain carbon black.

[0062] Anode formation According to various embodiments, the anode can be formed using any suitable method known to those skilled in the art. For example, the active material particles 100 described above can be mixed with graphite particles 130 to form an active material. In one embodiment, the active material may contain less than 50% by weight of M-SiO and more than 50% by weight of graphite. The active material can be mixed with SWCNTs, a binder, and an optional conductive additive to form a solid component. In some embodiments, the active material particles can be coated with a randomized carbon coating 110 before forming the active material, for example, using a spray drying process. Alternatively, the coating 110 can be omitted.

[0063] The solid components can be mixed in water or a polar solvent such as N-methyl-2-pyrrolidone (NMP) in a solid packing amount between approximately 20% and approximately 60% by weight to form an electrode slurry. For example, mixing may involve using a planetary mixer and high-shear dispersion blades under vacuum.

[0064] The electrode slurry can be coated onto a metal substrate, such as a copper or stainless steel substrate, with an appropriate mass filling density to balance the lithium capacity of the anode with the lithium capacity of the selected cathode. The coating can be performed using various devices such as a doctor blade, comma coater, gravure coater, or slot die coater.

[0065] After coating, the slurry can be dried to form the anode. For example, the slurry can be dried under forced air at a temperature ranging from room temperature to about 120°C. The dried slurry may be pressed to reduce its internal porosity, and the electrode can be cut into the desired shape. Typical anode press densities can range from about 1.0 g / cc to about 1.7 g / cc, depending on the electrode composition and the application of the target. Cathode press densities can range from about 2.7 to about 4.7 g / cc.

[0066] In some embodiments, the active material particles may be coated with randomized carbon before the active material is formed. For example, a mixture of active material particles, randomized carbon, and a solvent may be spray-dried to form a powder, which may then be heat-treated in an inert atmosphere such as argon gas to carbonize any remaining surfactant or dispersant. In other embodiments, the active material particles may be coated with randomized carbon using a binder and a mechanofusion process.

[0067] Electrochemical cell assembly The construction of an electrochemical cell involves pairing a coated anode substrate and a coated cathode substrate, which are electronically insulated from each other by a polymer and / or ceramic electrical insulating separator. The electrode assembly is sealed within a housing that can be a variety of structures, such as a coin cell, pouch cell, or can cell, and contains a non-aqueous ion-conducting electrolyte associated with the anode and cathode to enable operation. The electrolyte consists of an alkali metal salt dissolved in a mixture of an inorganic salt dissolved in a non-aqueous solvent, more preferably an alkali metal salt dissolved in a mixture of a low-viscosity solvent containing organic esters, ethers, and dialkyl carbonates, and a high-conductivity solvent containing cyclic carbonates, cyclic esters, and cyclic amides. Non-limiting examples of electrolytes include lithium hexafluorophosphate (LiPF6) or bis(fluorosulfonyl)imide lithium (LiFSi) salts in an organic solvent containing one of the following: ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), or a combination thereof.

[0068] Additional solvents useful in embodiments of the present invention include dialkyl carbonates, such as tetrahydrofuran (THF), methyl acetate (MA), diglyme, trigylm, tetragylm, 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1-ethoxy,2-methoxyethane (EME), ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, and combinations thereof. Similarly useful high dielectric constant solvents include cyclic carbonates, cyclic esters, and cyclic amides, such as propylene carbonate (PC), butylene carbonate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, gamma-valerolactone, gamma-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP), and combinations thereof.

[0069] The electrolyte may also contain one or more additives, such as vinylene carbonate (VC), 1,3-propanesulfone (PS), propa-1-ene-1,3-sultone (PES), fluoroethylene carbonate (FEC), and / or propylene carbonate (PC). The electrolyte acts as a medium for the movement of lithium ions between the anode and cathode during the electrochemical reaction of the battery, particularly during the discharge and recharge of the battery. The electrochemical battery may also have positive and negative terminals and / or contact structures.

[0070] Experimental example The following experimental examples relate to anodes formed using electrode materials of various embodiments of this disclosure and comparative electrode materials, and are given exemplarily, not limitingly. In the experimental examples, % is weight percent, g is grams, CE is Coulomb efficiency, and mAh / g is capacity.

[0071] Exemplary batteries 1-3 (E1, E2, E3) A solid component was formed by mixing the active material, SWCNTs, a conductive agent (carbon black), and a binder (CMC / SBR). The solid component was mixed with a polar solvent (water or NMP) and an electrode material slurry was formed under vacuum in a planetary mixer with high shear dispersion blades, with a solid filler content between 20% and 60% by weight.

[0072] The electrode material slurry was coated onto a copper current collector plate with an appropriate mass filling ratio to balance the lithium capacity of the anode with the lithium capacity of the selected cathode, dried, and pressed to form the anode. The anodes were assembled into half cells (excess counter electrode material = lithium metal), and the electrolyte was supplied to each half cell to form exemplary batteries 1-3. The anodes of exemplary batteries 1-3 contained 96 wt% active material, 0.1 wt% SWCNTs, 0.9 wt% carbon black, and 3 wt% CMC / SBR binder, respectively.

[0073] The anode of exemplary battery 1 contained 20 wt% LM-SiO and 76 wt% graphite. The anode of exemplary battery 2 contained 30 wt% LM-SiO and 66 wt% graphite. The anode of exemplary battery 3 contained 30 wt% unmetallic SiO and 66 wt% graphite.

[0074] Comparison batteries 1~4 (C1, C2, C3, C4) Comparative batteries 1-4 were formed in the same manner as exemplary batteries 1-3. The anode of comparative battery 1 contained 20 wt% LM-SiO, 76 wt% graphite, and 1 wt% carbon black, and did not contain CNTs. The anode of comparative battery 2 contained 30 wt% LM-SiO, 66 wt% graphite, 0.9 wt% carbon black, and 0.1 wt% multiwalled carbon nanotubes (MWCNTs).

[0075] The anode of comparative battery 3 contained 30 wt% LM-SiO, 66 wt% graphite, and 1 wt% carbon black, and did not contain CNTs. The anode of comparative battery 4 contained 30 wt% non-metallic SiO, 66 wt% graphite, and 1 wt% carbon black, and did not contain CNTs.

[0076] Table 2 below shows the half-cell cycle protocols applied to exemplary and comparative batteries.

[0077] [Table 2]

[0078] Figure 6A is a graph showing the specific capacity retention during cycles for exemplary battery 1 and comparative battery 1. As seen in Figure 6A, exemplary battery 1, which contained SWCNTs, exhibited superior capacity retention over 100 cycles. In contrast, comparative battery 1, which did not contain SWCNTs, lost more than 50% of its initial capacity in less than 20 cycles.

[0079] Figure 6B is a graph showing the specific capacity retention during cycles for exemplary battery 2 and comparative batteries 2 and 3. As seen in Figure 6B, exemplary battery 2, which contained SWCNTs, exhibited excellent capacity retention. In contrast, comparative batteries 2 and 3, which contained MWCNTs or did not contain CNTs, respectively, showed capacity loss of more than 50% in less than 10 cycles.

[0080] Figure 6C is a graph showing the specific capacity retention during the cycle of exemplary battery 3 and comparative battery 4. As seen in Figure 6C, the exemplary battery contained SWCNTs and non-metallated SiO instead of LM-SiO. 3 The battery showed excellent capacity retention. In contrast, comparative battery 4, which contained non-metallic SiO but no CNTs, showed a capacity loss of approximately 50% after 10 cycles.

[0081] Therefore, mixing SWCNTs with M-SiO and graphite improves the Coulomb efficiency and cycle life of the silicon anode and reduces measurable swelling of the electrode by buffering the volume changes of silicon particles during charging and discharging. Adding SWCNTs to the electrode composition provides relatively long-range conductivity across multiple electrode particles, which is flexible enough to maintain the conductive network as the particles within the electrode swell. This improves capacity retention as the Li-ion battery / electrode is charged and discharged during operation.

[0082] The long-range conductivity provided by SWCNTs unexpectedly enables high packing density of high-capacity alloy active materials, and despite more severe swelling of the entire electrode, capacity reduction due to electrical disconnection is avoided.

[0083] The addition of SWCNTs can also reduce the total carbon black content added for electronic conductivity, and consequently, the amount of polymer binder added for the total electrode surface area and mechanical integrity. Furthermore, carbon black is a nanomaterial that clogs pores and occupies the gaps between lithium storage active materials. High concentrations of carbon black are undesirable because they hinder proper calendering (compression) of the electrodes. Both the reduction in binder content and the increase in calendering density bring significant advantages to the high-energy-density Li-ion batteries that become possible.

[0084] While the foregoing refers to certain preferred embodiments, it will be understood that the present invention is not limited thereto. Various modifications can be made to the disclosed embodiments, and it will be apparent to those skilled in the art that such modifications are intended to fall within the scope of the present invention. All publications, patent applications, and patents referenced herein are incorporated herein by reference in their entirety.

Claims

1. An electrode material for lithium-ion secondary batteries, Active material particles containing alkali metal silicates or alkaline earth metal silicates, Binder and, Single-walled carbon nanotubes (SWCNTs) and Includes, The active material particles have a D-band peak intensity (ID) at wavenumbers between 1330 cm⁻¹ and 1360 cm⁻¹. G-bands with peak intensity (IG) at wavenumbers between 1580 cm⁻¹ and 1600 cm⁻¹, and It has a 2D band with peak intensity (I²D) at wavenumbers between 2650 cm⁻¹ and 2750 cm⁻¹. The I / D / IG ratio is in the range of greater than 0 to 1.

1. The I²D / IG ratio is in the range of 1.03 to 2. Measured using an incident laser wavelength of 532 nm, Electrode material for lithium-ion secondary batteries, including a coating containing turbid carbon having a Raman spectrum.

2. With respect to the total weight of the electrode material, A combination of at least 80% by weight of graphite particles and the active material particles, The binder in an amount of 1% to 5% by weight, The single-walled carbon nanotube (SWCNT) in an amount ranging from 0.05% by weight to 1% by weight and The electrode material according to claim 1, comprising:

3. The electrode material according to claim 2, wherein the SWCNT has an average diameter in the range of 0.5 nm to 2.5 nm and an average length greater than 1 μm.

4. The SWCNT is determined by Raman spectroscopy to have a value greater than 5 I Ｇ / I Ｄ It has a ratio and an average length in the range of 10 μm to 500 μm. The electrode material according to claim 3, wherein the electrode material contains 0.08% by weight to 0.25% by weight of SWCNTs.

5. The electrode material according to claim 2, comprising a combination of graphite particles and active material particles in an amount from 90% by weight to 96.5% by weight.

6. The graphite particles in an amount of 50% to 95% by weight, and The active material particles are contained in an amount ranging from 5% by weight to 50% by weight. The electrode material according to claim 5.

7. The graphite particles in an amount of 70% to 90% by weight, and The active material particles are contained in an amount ranging from 10% to 30% by weight. The electrode material according to claim 6.

8. The graphite particles have an average particle size in the range of 2 μm to 30 μm, and 0.5 m ２ / g to 2.5m ２ Having a surface area in the range of up to / g, The active material particles have an average particle size in the range of 1 μm to 20 μm, and 0.5 m ２ / g to 30m ２ Having a surface area in the range of up to / g, The graphite particles have a larger average particle size than the active material particles. The electrode material according to claim 6.

9. The active material particles are Li ２ Si ２ O ５ 、Li ２ SiO ３ 、Li ４ SiO ４ 、or a primary phase containing any combination thereof, and The primary phase includes a crystalline silicon region dispersed within it. The electrode material according to claim 2.

10. The electrode material according to claim 9, wherein the active material particles further comprise a SiOx region [wherein x is in the range of 0.8 to 1.2] dispersed within the primary phase.

11. The primary phase is Li ２ Si ２ O ５ Includes, The crystalline silicon region has an average particle size of less than 100 nm. The electrode material according to claim 9.

12. The active material particles are MgSiO ３ Mg ２ SiO ４ , or a primary phase including any combination thereof, and The primary phase includes a crystalline silicon region dispersed within it. The electrode material according to claim 2.

13. The electrode material according to claim 2, wherein the binder comprises polyvinylidene fluoride (PVDF), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), lithium polyacrylate (LiPAA), or a combination thereof.

14. The electrode material according to claim 13, wherein the binder includes a combination of the CMC and SBR.

15. The electrode material according to claim 2, further comprising 0.1% to 5% by weight of a conductive agent selected from carbon black, a conductive polymer, a metal powder, or any combination thereof.

16. The electrode material according to claim 15, wherein the conductive agent comprises carbon black powder having an average particle size smaller than the particle size of the active material particles and the graphite particles.

17. The electrode material according to claim 1, wherein the SWCNTs form a percolation network of conductive links between the active material particles.

18. The I Ｄ / I Ｇ The ratio is 0.

8. The above I ２Ｄ / I Ｇ The electrode material according to claim 1, wherein the ratio is 1.

03.

19. an anode comprising the electrode material described in claim 1, Separator and, Cathode and, The electrolyte disposed between the anode and the cathode Lithium-ion secondary batteries, including

20. The battery according to claim 19, wherein the SWCNT reduces the electrical disconnection of active material particles during charging and discharging of the lithium secondary battery.

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