Thermally disassociated anode active material comprising a turbostratic carbon coating

Abstract

An electrode material for a lithium ion secondary battery and a method for forming the same, the electrode material including composite particles, each composite particle including: primary particles including thermally disassociated silicon oxide; and a sheath provided on a surface of the primary particles. The sheath includes a turbostratic carbon having a Raman spectrum with: a D band having a peak intensity (I D ) at a wave number between 1330 cm ‑1 and 1360 cm ‑1 ; a G band having a peak intensity (I G ) at a wave number between 1530 cm ‑1 and 1600 cm ‑1 ; and a 2D band having a peak intensity (I 2D ) at a wave number between 2650 cm ‑1 and 2750 cm ‑1 , wherein: a ratio of I D / I G is in a range of greater than zero to about 1.0; and a ratio of I 2D / I G is in a range of about 0.4 to about 2.

Description

Technical Field

[0001] This invention relates to anodic active materials for electrochemical battery cells, and more particularly to advanced anodic active materials for secondary lithium-ion electrochemical battery cells, the anodic active materials comprising composite particles, the composite particles comprising thermally disproportionated primary particles coated with a low-defect disordered carbon material. Background Technology

[0002] Lithium (Li)-ion electrochemical battery cells typically require materials capable of achieving high energy density, high power density, and high cycle stability. Li-ion battery cells are commonly used in a wide range of applications, including consumer electronics, wearable computing devices, military mobile equipment, satellite communications, spacecraft, and electric vehicles, and are particularly prevalent in large-scale energy applications such as low-emission electric vehicles, renewable energy power plants, and stationary power grids. Furthermore, lithium-ion battery cells are at the forefront of next-generation wireless and portable communication applications. One or more lithium-ion battery cells can be used to configure a battery to power any of these applications. However, the surge in applications with even higher energy demands is accelerating research into lithium-ion battery cells with even higher energy densities, higher power densities, higher charge-discharge capabilities, and longer cycle lives. Additionally, with the increasing adoption of lithium-ion technology and the migration of applications towards higher current demands, longer operating times, wider and higher power ranges, and smaller form factors, the need to expand the energy and power densities available today is growing.

[0003] Silicon or silicon alloy anode materials are currently included in most long-term lithium-ion technology adoption roadmaps as a practical means to achieve higher energy and power densities. Silicon is the desired anode active material for lithium-ion electrochemical battery cell applications, with a theoretical gravimetric capacity of approximately 4,200 mAh / g and a volumetric capacity of approximately 9,786 mAh / cm³ when fully lithium-ionized. 3Silicon is also currently the preferred alternative to graphite-based anodes because its high lithium storage capacity can exceed that of graphite by up to 7 times. However, the market adoption of silicon-based anodes for lithium-ion battery cells faces challenges such as rapid cycle life degradation, poor charge-discharge rate capability under high power demands, and poor or insufficient coulombic efficiency, all of which can be caused by extreme anode volume changes during charging and discharging (volume expansion of up to 400% has been noted). Cycle life degradation in silicon-based alloys is well understood and can be broken down into two basic mechanisms: (1) electrical disconnection; and (2) an unstable solid electrolyte interphase (SEI) film that leads to lithium-ion consumption and impedance growth. These mechanisms also impair high rate capability and coulombic efficiency. Electrical disconnection occurs during charging and discharging, accompanied by significant volume fluctuations, due to the large volume changes during lithiation and delithiation.

[0004] These large volume changes can lead to the fragmentation of silicon particles (stress-induced cracking and fracture) and the loss of electrical contacts between these active silicon particles. The result is an electrochemical cell with low power capacity and rapid capacity decay. The cracking and fracture introduced in mechanism (1) further degrades cell performance by subsequently promoting mechanism (2) (unstable SEI). Because cracking and fracture expose the new Si surface to the electrolyte solvent, further SEI formation occurs, resulting in the deposition of lithiated compounds on the new Si surface. During charge / discharge cycles, the insulating SEI layer also thickens, further reducing the capacity and cycle stability of the Si anode and impairing charge / discharge rate capability and coulombic efficiency.

[0005] The continuous and new growth of the SEI layer gradually depletes the available Li. + Furthermore, the amount of available electrolyte is depleted due to side reactions with the electrolyte solvent and salt, thereby degrading the overall performance of the electrochemical cell. Because of these mechanisms' high ohmic and ionic contributions to polarization, the use of silicon-based anodes in applications requiring high charge / discharge rates for electrochemical cell units is severely limited.

[0006] For decades, improving the cycle stability of high-specific-capacity silicon or silicon alloy anodes has been a key focus of development. Various approaches have been adopted regarding the cycle life stability of silicon anodes, such as, but not limited to, (i) anode particle structure; (ii) particle size control; (iii) particle surface coating or encapsulation; (iv) composite particle composition and / or structure; (v) void space engineering; and (vi) carbon-containing anode composite material mixtures. Due to the favorable physical and electrochemical properties of carbon, utilizing carbon variants has become one of the most popular methods for stabilizing the cycle life of silicon alloy anodes. It has been shown that adding carbon to composite anode material mixtures can be used to provide silicon-based anodes with a conductive network and / or matrix that buffers volume expansion during lithiation and delithiation. Furthermore, it has been shown that nanocarbon materials with one to several finite atomic layers are particularly beneficial for silicon-based anodes due to their ability to maintain close contact with silicon particles during volume expansion and contraction. Carbon materials such as graphite, graphene, graphene oxide, reduced graphene oxide, exfoliated graphite and graphene, graphene nanosheets or nanoparticles, including nanosheets or nanoparticles containing one or more graphene layers, and carbon nanotubes (CNTs) such as single-walled, double-walled or multi-walled CNTs have all shown beneficial additions to electrode material mixtures, either independently or in combination.

[0007] It is generally accepted that the quality of graphene is largely dependent on the manufacturing and processing conditions during its fabrication. For example, through graphene oxide, the defect density of graphene nanosheets can be significantly affected by various modifications to the Hummers production method and subsequent reduction processes. However, the impact of graphene quality on battery electrode performance has not been fully characterized. For instance, the defect density and / or lattice stacking of carbon materials have virtually no effect on the performance of electrochemical battery cells. Historically, scanning electron microscopy (SEM) has often been the first option for observing the morphology of Si / graphene composites. However, due to the limitations of SEM imaging, it is not possible to properly quantify the thickness and number of graphene layers, as well as the defect density. Transmission electron microscopy (TEM) has been used to study the crystal structure of Si / graphene nanocomposites. By adjusting the contrast of TEM images, graphene sheets can be separated from Si / graphene nanocomposites due to their thinness and relatively low atomic weight; however, determining the number of layers and defining the defect density remains difficult. Atomic force microscopy (AFM) has been used to measure the thickness of graphene nanosheets. It has been shown that many fabricated Si / graphene nanocomposites have graphene thicknesses of less than 10 nm; however, AFM cannot determine the thickness or defect characteristics of the graphene.

[0008] Therefore, there is a need for an advanced anode material mixture for electrochemical battery cells that incorporates carbon materials with defined quality characteristics, which advantageously influence the cycle performance of the electrochemical battery cells. More specifically, there is a need for an advanced silicon-based anode mixture composition comprising low-defect disordered carbon, which enables lithium-ion electrochemical battery cells to achieve cycle life stability, energy density, and rate performance. Summary of the Invention

[0009] According to various embodiments of this disclosure, an electrode material comprising composite particles is provided, each composite particle comprising: a primary particle comprising thermally disproportionated silicon oxide; and an encapsulation disposed on the surface of the primary particle, the encapsulation comprising disordered layered carbon having a Raman spectrum having: a D band, the peak intensity of the D band being (I... D At 1330cm -1 With 1360cm -1 Between wavenumbers; G-band, the peak intensity of the G-band (I G ) at 1530cm -1 With 1580cm -1 The wavenumbers between; and the 2D spectral bands, the peak intensity of which (I) 2D At 2650cm -1 With 2750cm -1 At the wavenumbers between, where: I D / I G The ratio ranges from greater than zero to approximately 0.8; and I 2D / I G The ratio ranges from about 0.5 to about 2.

[0010] According to various embodiments, an electrode material for a lithium-ion secondary battery comprises composite particles, each composite particle comprising: a primary particle comprising thermally disproportionated metallized (e.g., metal-doped) silicon oxide; and an encapsulation disposed on the surface of the primary particle, the encapsulation comprising disordered layered carbon having a Raman spectrum having: a D band, the peak intensity of the D band being (I... D At 1330cm -1 With 1360cm -1 Between wavenumbers; G-band, the peak intensity of the G-band (I G At 1580cm -1 With 1600cm -1 The wavenumbers between; and the 2D spectral bands, the peak intensity of which (I) 2D At 2650cm -1 With 2750cm -1At the wavenumbers between, where: I D / I G The ratio ranges from greater than zero to approximately 1.1; and I 2D / I G The ratio ranges from about 0.4 to about 2.

[0011] According to various embodiments of this disclosure, the envelope comprises low-defect disordered carbon, which includes graphene layers that partially overlap each other on the surface of the primary particles to simulate a larger monolithic structure. In some embodiments, the disordered carbon may be in the form of a sheet-like structure having one or more layers of graphene. In some embodiments, the disordered carbon has a low thickness. In some embodiments, the disordered carbon is wrinkled, resembling a wrinkled spherical structure. In some embodiments, the disordered carbon is entangled or bonded to particles of electrode material.

[0012] According to various embodiments of this disclosure, a method for forming an anode material is provided, the method comprising: causing SiO2 to form an anode material. x Particle thermal disproportionation, wherein x ranges from about 0.7 to about 1.1, to form primary particles comprising crystalline Si domains disposed in a matrix comprising SiO2; to form a mixture comprising the primary particles and graphene; and to coat the primary particles with graphene to form composite particles.

[0013] According to various embodiments of this disclosure, a method for forming an anode material is provided, the method comprising: forming a material comprising graphene and SiO2. x A mixture of particles, wherein x ranges from about 0.7 to about 1.1; the primary particles are coated with graphene to form a composite powder; and the powder is thermally disproportionated to form composite particles. Each composite particle comprises: a primary particle including crystalline Si domains disposed in a matrix comprising SiO2; and an encapsulation disposed on the primary particle and comprising graphene.

[0014] Other key features and advantages of the invention will become apparent to those skilled in the art upon examination of the following drawings, detailed description and appended claims. Attached Figure Description

[0015] Figure 1A , Figure 1B and Figure 1C Raman spectra of graphite and various graphene-based materials are displayed.

[0016] Figure 2 This is a comparison of the Raman spectra of typical carbon materials and low-defect disordered carbon. D / I G A bar chart of ratios.

[0017] Figure 3 shows SiO2 encapsulated with reduced graphene oxide (rGO). x Raman spectra of primary particle electrode active materials.

[0018] Figure 4 shows SiO2 coated with amorphous carbon. x Raman spectra of primary particle electrode active materials.

[0019] Figure 5 shows SiO2 encapsulated by low-defect disordered carbon. x Raman spectra of primary particle electrode active materials.

[0020] Figure 6A The graph shows the cycle life of exemplary and comparative half-cell cells, and Figure 6B Comparison of various embodiments according to this disclosure Figure 6A A table showing the specific capacity, first coulombic efficiency (CE), and number of cycles up to 80% capacity of exemplary and comparative half-cell cells.

[0021] Figure 7 This is a diagram illustrating an exemplary hybrid pulse power characterization test scheme.

[0022] Figure 8 This is a graph illustrating a comparison of voltage polarization of exemplary and comparative full-cell cells according to various embodiments of the present disclosure.

[0023] Figure 9 It shows the use of from Figure 8 The voltage response curves are plotted using the area ratio impedance (ASI) calculated at various states of charge (SOC) of exemplary and comparative full-cell cells.

[0024] Figure 10 It shows the use of Figure 9 The voltage response curves are plotted using ASI data calculated after 30 electrochemical tests on exemplary and comparative full-cell cells.

[0025] Figure 11 The graph shows the cycle life of exemplary and comparative full-cell cells.

[0026] Figure 12A It includes SiO encapsulated by reduced graphene oxide. x Scanning electron microscope (SEM) image of a composite particle consisting of primary particles.

[0027] Figure 12B It includes SiO2 encapsulated by low-defect disordered carbon layers. x Scanning electron microscope (SEM) image of a composite particle consisting of primary particles.

[0028] Figure 13AFigure 13D is a micrograph showing composite particles according to various embodiments of the present disclosure.

[0029] Figure 14A and Figure 14B These are schematic cross-sectional views of thermally disproportionated composite electrode material particles 100 according to various embodiments of the present disclosure.

[0030] Figure 15A and Figure 15B It is formed based on the various embodiments of this disclosure. Figure 14A and Figure 14B A block diagram of different methods for composite particles. Detailed Implementation

[0031] Various embodiments will be described in detail with reference to the accompanying drawings. Where appropriate, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. Reference to specific examples and embodiments is for illustrative purposes and is not intended to limit the scope of the invention or the claims.

[0032] It should be understood that when an element or layer is referred to as being "on" or "connected to" another element or layer, the element or layer may be directly on or directly connected to the other element or layer, or there may be intermediate elements or layers. Conversely, when an element is referred to as being "directly on" or "directly connected to" another element or layer, there are no intermediate elements or layers. It should be understood that, for the purposes of this disclosure, "at least one of X, Y, Z" can be interpreted as only X, only Y, only Z, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ).

[0033] Where a range of values ​​is provided, it should be understood that every intermediate value between the upper and lower limits of the range (to one-tenth of the unit of the lower limit, unless otherwise explicitly stated) and any other stated or intermediate values ​​within the range are covered by this invention. The upper and lower limits of these smaller ranges may be independently included within the smaller range and also covered by this invention, subject to any exact exclusions within the stated range. Where the stated range includes one or both of the limits, the range excluding any one or both of those included limits is also included by this invention. It should also be understood that the term "about" may refer to a small measurement error, for example, + / - 5% to 10%.

[0034] Words such as “thereafter,” “then,” and “next” are not necessarily intended to restrict the order of steps; these words can be used to guide the reader through the description of the method. Furthermore, any reference to an element declared in the singular (e.g., using the articles “a / an” or “the”) should not be construed as limiting the element to the singular.

[0035] "Electrode material" is defined as a material that can be configured to be used as an electrode within an electrochemical battery cell, such as a lithium-ion rechargeable battery. "Electrode" is defined as the anode or cathode of an electrochemical battery cell. "Composite electrode material" is also defined as an active material particle that is combined with one of the following: particles, flakes, spheres, lamellae, sheets, tubes, fibers, or combinations thereof, and is a conductive material. The particles, flakes, spheres, lamellae, sheets, tubes, fibers, or combinations thereof may further be one of the following: flat, wrinkled, pleated, layered, woven, braided, or combinations thereof. The conductive material 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. The conductive carbon-based material may further include one of the following: graphite, graphene, diamond, pyrolytic graphite, carbon black, low-defect disordered carbon, fullerene, or combinations thereof. "Electrode material mixture" is defined as a combination of materials such as: material particles (electrochemically active, conductive, composite, or combinations thereof), one or more binders, one or more non-crosslinked polymers, and / or one or more crosslinked polymers, mixed together to form the electrode of an electrochemical battery 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. The term "insertion and release" can be further understood as the insertion and deintercalation of ions or the lithiation and delithiation of ions. Therefore, the process of inserting and releasing ions should also be understood as insertion and deintercalation or lithiation and delithiation. Therefore, "active material," "electrochemically active material," or "active material particle" is defined as a material or ion capable of repeated ion insertion and deintercalation or lithiation and delithiation.

[0036] A "defect" is defined as any feature that disrupts the symmetry of the hexagonal lattice of carbon atoms in a given carbon sheet. According to this definition, defects can include vacancies, substitutional atoms, edges, grain boundaries, or variations in carbon hybridization. "Hybridization" is the mixing of standard atomic orbitals to form new orbitals, which can be used to describe the bonding of molecules. The mixing of standard atomic orbitals is often associated with sp... 2 and sp 3 The orbits occurred together.

[0037] Defect density is defined as the number of symmetrical fracture features (defects) per unit area of ​​a carbon plane. This value is typically estimated as the average distance between two defects. I can be used... D / I G The ratio is approximated by Raman spectroscopy to represent the defect density.

[0038] "Composite particles" may include primary particles or nuclei containing electrochemically active materials and an envelope disposed on the surface of the primary particles. The envelope may include disordered carbon.

[0039] According to various embodiments of this disclosure, the primary particles are at least partially encapsulated (e.g., covered) by an encapsulation. For example, the encapsulation and / or disordered carbon may cover approximately 10% to approximately 100% of the surface of each primary particle, such as approximately 20% to approximately 90%, approximately 25% to approximately 80%, approximately 30% to approximately 70%, or approximately 40% to approximately 60%.

[0040] A “capsule” can be a capsule or shell that at least partially covers, encloses, or encapsulates a core material such as at least one primary particle. The primary particle can include an electrochemically active material capable of producing reversible lithium storage capacity, such as a quasi-metallic or metal oxide material. In some embodiments, the capsule may have a corrugated morphology. The term “corrugated” is defined as a body or block exhibiting a distribution of creases, ripples, folds, wrinkles, and ridges. The term “corrugated” is also defined as bending or becoming curved. The term “morphology” is defined as the structure and one or more features of a surface. Specifically, “morphology” is the structure and features of the outer surface of a particle or macroscopic particle of an electrode material.

[0041] As defined herein, a “secondary” electrochemical cell is a rechargeable electrochemical cell or battery. “Capacity” is defined herein as a measure of the charge stored by the battery, determined by the mass of the active material contained within it, representing the maximum energy, in ampere-hours (Ah), that can be extracted from the battery at its rated voltage. Capacity can also be defined by the following equation: Capacity = Energy / Voltage or Current (A) × Time (h). “Energy” is defined mathematically 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 per unit volume of active electrode material within a specified time. Specific capacity can be measured in units of weight, such as (Ah) / g, or in units of volume, such as (Ah) / cc. Specific capacity is defined mathematically by the following equation: 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 specified time period. Alternatively, "rate capability" is the maximum continuous or pulsed energy that a battery can provide per unit time.

[0042] “C-rate” is defined in this document as a measure of the rate at which a battery discharges relative to its maximum nominal capacity. For example, a 1C current rate means that the discharge current will discharge the entire battery in 1 hour; a C / 2 current rate means that the battery cell will be fully discharged in 2 hours, and a 2C rate means that the battery cell will be fully discharged in 0.5 hours. “Power” is defined as the rate of energy transfer over time, measured in watts (W). Power is the product of the voltage (V) across the battery or battery cell and the current (A) flowing through the battery or battery cell. “C-rate” is defined mathematically as: C-rate (countdown) = current (A) / capacity (Ah) or C-rate (countdown) = 1 / discharge time (h). Power is defined by the following mathematical equation: Power (W) = energy (Wh) / time (h) or Power (W) = current (A) × voltage (V). Coulombic efficiency is the efficiency of charge transfer within an electrochemical battery cell. Coulombic efficiency is the ratio of the battery’s charge output to its charge input.

[0043] Among other things, this application discloses a composite particle comprising an active material and low-defect disordered carbon. It further discloses a composite electrode material, an electrochemical battery cell, and related processes. The low-defect disordered carbon material may include elements from one of the group consisting of: particle structures, particle structures having active material particles as a first component, electrode materials, electrodes, electrochemical battery cells, and combinations thereof. Compared to other carbon-based materials used in electrochemical battery cells, low-defect disordered carbon provides improved cycle stability and high-rate performance. Specifically, when low-defect, low-thickness disordered graphene and... That When the method is used as an element of the structure in an electrochemical battery cell, the low-defect, low-thickness disordered graphene and the method thereof provide superior performance of the electrochemical battery cell compared to other electrochemical battery cells using other carbon materials.

[0044] Raman spectroscopy is a technique used to observe vibrational, rotational, and other low-frequency modes in a system. It is commonly used in chemistry to provide structural fingerprints of molecules that can be identified. This technique relies on inelastic scattering, or Raman scattering, of monochromatic light from lasers typically in the visible, near-infrared, or near-ultraviolet range. The laser interacts with molecular vibrations, phonons, or other excitations in the system, causing the energy of the laser photons to shift upwards or downwards. This energy transfer provides information about the vibrational modes in the system. Therefore, Raman spectroscopy allows for the identification and characterization of carbon-based materials, ranging from well-structured carbons such as tetracoordinated diamond, to tricoordinated aromatic carbons such as graphene, nanotubes, nanosheets, nanocones, and nanoribbons, down to amorphous carbon. Multiwavelength Raman spectroscopy has proven to be a very powerful, non-destructive tool for characterizing such carbons. Depending on the material being studied, specific spectral parameters (e.g., band position, full width at half maximum, and relative intensity ratio between two bands) are used to characterize defects.

[0045] sp2 hybrid carbon constitutes a broad class of solid phases primarily composed of elemental carbon and can be synthetic or naturally occurring. Some non-limiting examples are graphite, graphene, carbon nanotubes, and pyrolytic carbon. These carbons can vary from highly ordered or crystalline solids to completely disordered or amorphous solids, and detailed knowledge of the internal structure and composition of said carbons is extremely important to the scientific and engineering electrochemical battery cell community using these materials.

[0046] Interestingly, graphene, the fundamental structural unit used in all graphite materials, currently lacks a universally accepted standard material definition because its application in electrochemical battery cells is crucial. Due to this lack of scientific clarity, many forms of graphene or graphene-like materials have been used as electrode additives, including, but not limited to, monolayer graphene, few-layer graphene, multilayer graphene, carbon nanoribbons and carbon nanosheets, graphene oxide, and reduced graphene oxide. Confusingly, all these materials are often vaguely labeled as graphene in scientific and legal publications despite not meeting the scientific definition of graphene. Because such a standard definition for graphene materials or a group of graphene materials for electrochemical battery cells does not exist, selecting the correct graphene-like carbon material suitable as an additive for use in mixtures of active materials in electrochemical battery cells is currently challenging.

[0047] Graphene is a material of interest for use in electrochemical battery cells because it is an extremely efficient conductor of both electrical and thermal energy. Graphene is also lightweight, chemically inert, and flexible. However, because graphene is produced using a variety of processes, the performance results of electrochemical battery cells vary and are often disappointing. Non-limiting processes for producing graphene include mechanical splitting, epitaxial growth, chemical vapor deposition, and chemical or mechanical exfoliation. Because so many different processes can be used to prepare graphene or graphene-like products, it is expected that graphene may contain many carbon species, may have undesirable byproducts as residues from the processes, and may have potentially harmful structural damage or combinations thereof resulting from the processes.

[0048] The Raman spectra of all carbon systems exhibited several notable features, regardless of the final structure, whether it was a conjugated polymer or a fullerene. Furthermore, the carbon system spectra characteristically ranged from 1000 to 2000 cm⁻¹. -1 Strong spectral bands are displayed in the region, in addition to several other second-order modulations present in the spectrum. The shape, intensity, and position of the peaks in the spectrum allow for the differentiation, for example, between hard amorphous carbon and carbon nanotubes.

[0049] Figure 1A , Figure 1B and Figure 1C The Raman spectra of graphite and various graphene-based materials are displayed. It is generally accepted that the characteristic peaks of graphite and graphene materials are located at approximately 1340 cm⁻¹. -1 1584cm -1 and 2700cm -1 Location. 1340cm -1 The peak at that location is shown Figure 1C In the middle, it is characterized as a D band. 1584cm -1 The peak at that location is shown Figure 1A and Figure 1C In the spectrum, and characterized as the G band, the G band is formed by all sp... 2 The D band originates from the vibrational modes represented by the stretching of the C=C bonds in hybrid carbon atom pairs. The D band indicates the presence of defects or broken symmetries in the graphene structure. (2700 cm⁻¹) -1 The peak at that location is shown Figure 1B The bimodal pattern is characterized as a 2D band generated by a double resonance process caused by the interaction between stacked graphene layers. The appearance of the bimodal pattern at the 2D wavenumber disrupts the peak symmetry and indicates the AB stacking order between graphene planes in graphite and graphene derivatives such as nanosheets. When the AB stacking order of disordered multilayer graphene particles is disrupted, Figure 1BThe 2D1 peak shown is suppressed. The positions of the G band and the 2D band are used to determine the number of layers in the material system. Therefore, Raman spectroscopy provides scientific clarity and definition for carbon material additives in electrochemical cell units, thus providing a fingerprint for the correct selection of additives as active material electrode compositions. As will be shown below, this definition provides a fingerprint for the low-defect disordered layered carbon of this application. When used as an additive in mixtures of active materials for electrochemical cell electrodes, this low-defect disordered layered carbon provides excellent electrochemical cell performance.

[0050] Disordered carbon

[0051] Figure 2 Compared to the low-defect disordered carbon of this application, this invention provides a significant improvement in the performance of carbon additives (i.e., reduced graphene oxide or amorphous carbon) commonly used in prior art electrode active material mixtures. D / I G ratio.

[0052] Reduced graphene oxide (rGO) is a carbon variant commonly referred to as graphene in industry; however, it is unique in its final structure and manufacturing process. Graphene oxide is typically first produced using a modified Hermes process, in which graphite material is oxidized and exfoliated into monolayers or lamellae comprising several layers of carbon that may include, but are not limited to, hydroxyl, epoxide, carbonyl, and carboxyl groups. These functional groups are then removed by chemical or thermal treatment that converts insulating graphene oxide into conductive reduced graphene oxide. While similar to graphene in that it consists of a single-layer lattice of carbon atoms, reduced graphene oxide differs in that it exhibits mixed sp2 and sp3 hybridization, residual functional groups, and a generally increased defect density resulting from the manufacturing and reduction processes. Reduced graphene oxide is shown in... Figure 2 In the first bar, and I D / I G The ratio is 0.9.

[0053] Amorphous carbon is commonly used as an additive or surface coating for both anode and cathode material mixtures in electrochemical battery cells to enhance electrode conductivity. Typically, amorphous carbon is produced using a chemical vapor deposition (CVD) process, in which hydrocarbon feedstock gases flow into a sealed container and carbonize onto the surface of the desired powder material at elevated temperatures. This thermal decomposition process can provide thin amorphous carbon coatings, on the order of nanometers, that lack any sp2 hybridization found in crystalline graphene-based materials. Amorphous carbon is shown in... Figure 2 In the third bar, and I D / I G Ratio>1.2.

[0054] Low-defect disordered carbon, also known as graphene, possesses unique properties resulting from its fabrication and processing. A common method for producing this material is through plasma-based CVD processes, in which hydrocarbon feedstock gases are fed through an inert gas plasma in the presence of a catalyst that enables the nucleation of graphene-like carbon structures. By controlling production parameters, carbon materials with several layers and no AB stacking order between the lattice layers can be produced. These carbon materials are typically highly ordered sp2 carbon lattices with low defect density.

[0055] The low-defect disordered carbon disclosed herein is shown in Figure 2 The second middle bar. The Raman spectrum of the low-defect disordered carbon additive of this application is derived from the intensity ratio of the D band and the G band (I D / I G ) and the intensity ratio of the 2D band and the G band (I 2D / I G ). I D I 2D and I G It is represented by its corresponding integral intensity. Low I D / I G The ratio indicates low-defect materials. In some embodiments, the I ratio of low-defect disordered carbon materials... D / I G The ratio is greater than zero and less than or equal to about 1.1, such as greater than zero to about 1, greater than zero to about 0.9, or greater than zero to about 0.85, wherein the ratio is determined by Raman spectroscopy and measured using an incident laser wavelength of 532 nm, where I G The wavenumber range is between 1530 and 1600 cm⁻¹ -1 Between, at approximately 1580cm -1 Up to approximately 1600cm -1 Or at 1530 and 1584cm -1 Between, I D The wavenumber range is between 1330 and 1360 cm⁻¹ -1 Between. In one embodiment, the low-defect disordered layer carbon material of the present invention I D / I G The ratio is greater than zero and less than or equal to approximately 0.8, and the ratio is determined by Raman spectroscopy and measured using an incident laser wavelength of 532 nm, where I G The wavenumber range is between 1530 and 1580 cm⁻¹ -1 Between, I D The wavenumber range is between 1330 and 1360 cm⁻¹ -1 Between. Furthermore, the low-defect disordered layer carbon material disclosed herein exhibits I... 2D / I GThe ratio is approximately 0.4 or greater, such as 0.5 or greater. As for I... 2D / I G The ratio reference is approximately 2 I. 2D / I G The ratio is typically associated with monolayer graphene. Less than approximately 0.5 Ig 2D / I G The ratio is typically associated with bulk graphite composed of numerous stacked AB graphene layers. Therefore, for the low-defect disordered layer carbon materials of this disclosure, approximately 0.5 or greater I0.5 2D / I G The ratio indicates a low-layer count ≤ 10. In some embodiments, the I of low-defect disordered carbon layers... 2D / I G The ratio can range from about 0.4 to about 2, or from about 0.5 to about 2. Low-defect, disordered-layer carbon materials with low layer counts further lack the AB stacking order between graphene layers (i.e., disordered layers). The disordered nature of these graphene planes, or the lack of AB stacking, is due to I... 2D Peak symmetry indication. The symmetry of 2D peaks distinguishes between disordered graphene layered materials and AB-stacked graphene layered materials, and indicates rotational stacking disorder and layered stacking order.

[0056] Carbon materials with a high AB stacking order will still exhibit 2D peaks; however, these 2D peaks exhibit double peaks that disrupt the symmetry of the peaks. This symmetry disruption is observed in both multi-layered AB-stacked graphene and multi-layered graphene. Therefore, 2D peaks (which are a very strong indicator of the presence of stacking order, regardless of the number of graphene layers present in the material) are important when selecting graphene or graphene-based additives. The low-defect disordered layered carbon of this disclosure differs from all other graphene or graphene-based additives used to date in that the rotational disorder of the stacking provides flexibility to the carbon-based particles, enabling them to provide and maintain contact with the active primary particles of the composite particles, including the electrodes of the electrochemical cell unit. The result is an electrochemical cell unit with increased cycle life, better cycle life stability, enhanced energy density, and excellent high-rate performance.

[0057] When silicon and silicon alloys are incorporated into the electrodes of an electrochemical battery cell, the capacity of the cell is significantly increased. Silicon and silicon alloys are typically incorporated into electrodes that include graphite, graphene, or other carbon-based active materials. Examples of electrodes comprising carbon-based materials and silicon are provided in U.S. Patents 8,551,650, 8,778,538, and 9,728,773 to Kung et al., and U.S. Patents 10,135,059 and 10,135,063 to Huang et al., the entire contents of which are incorporated herein by reference.

[0058] One embodiment of the material of the present invention includes composite particles. The composite particles may include at least one primary particle (i.e., an active material particle), wherein the primary particle comprises a quasi-metallic or metal oxide material. The primary particle may be an anodic active material particle. The average particle size of the primary particle may be in the range of about 1 μm to about 15 μm. Alternatively, the average primary particle size may be less than about 1 μm. The surface area of ​​the primary particle may be about 0.5 m². 2 / g to approximately 50m 2 Within the range of / g. In embodiments, the metal oxide of the primary particles includes silicon oxide (SiO2). x ), where x is in the range of about 0.1 to about 1.3. Some embodiments may include low-defect disordered carbon layers that at least partially cover the primary particles. The low-defect disordered carbon layers may be in the form of lamellae comprising one to about 10 layers of graphene material, such as graphene, graphene oxide, or reduced graphene oxide. In some embodiments, the low-defect disordered carbon layers may comprise at least 90%, such as about 90% to about 100%, of graphene.

[0059] In some embodiments, the average particle size of the composite particles can be ≤10 μm. In others, the average particle size can be about 1 μm or less. In still others, the average particle size can range from about 0.5 μm to about 15 μm, about 0.5 μm to about 5 μm, about 0.5 μm to about 2 μm, or about 0.5 μm to about 1.5 μm. The composite particles can be included in an active electrode material, such as an active anode electrode material.

[0060] Composite particles can be formed by combining electrochemically active carbon materials and low-defect disordered-layer carbon materials in dry weight ratios between 7:3 and 99:1. For example, the active and carbon materials can be combined to form dry mixtures without liquid solvents or wet mixtures containing liquid solvents. For example, in some embodiments, the original active and carbon materials can be suspended in polar liquid solvents such as water or ethanol by high-shear mixing or ultrasonic treatment. A significant advantage of low-defect disordered-layer carbon is its ability to be suspended in polar solvents with high solids loadings, making it suitable for low-cost wet chemical processing. Graphene oxide is a possible option because it possesses a variety of oxygen-containing functional groups. These functional groups are attached to the carbon lattice, allowing graphene oxide to be suspended in a variety of polar solvents with low solids loadings. Other types of carbon additives typically lack suspending ability and therefore must be dry-processed or grown directly on a matrix material. Suspensions of some materials can also be promoted by using surfactants. Importantly, the high conductivity achieved through the low-defect disordered layer structure allows for lower ratios of materials (<90:10 and as low as 99:1) to be mixed with electrochemically active materials to achieve comparable conductivity enhancements compared to other carbon additives.

[0061] Once the raw material suspension is prepared, it is then atomized and dried in a vacuum heating chamber to force the suspended solids into close contact. Process parameters can vary depending on the final powder particle requirements. For example, spherical composite particles can be formed by atomizing droplets and then rapidly drying them in a heating chamber. Alternatively, an atomizer atomizes the raw material suspension to form aerosol droplets. The atomization step requires sufficient spray parameters to allow the particles within the droplets to become ordered before aerosol evaporation begins. For disordered carbon materials, particles within the droplets migrate to the surface of the droplets to form a hollow envelope of spheres upon drying. If the droplets contain only disordered carbon, the envelope can be used as a conductive additive for electrode materials. The envelope minimizes particle aggregation and agglomeration because this structure overcomes the strong interparticle van der Waals attraction that causes the carbon material sheets to re-stack, complicating solution processability and reducing the particle-accessible surface area. This structure is also stable against unfolding or folding.

[0062] If the droplet contains both carbon-based and electrochemically active materials, the electrochemically active material may be located at the center of the droplet, while the carbon-based material may be located at the surface. Ordered aerosol droplets flowing through a preheating furnace allow carbon-based material particles to be positioned, aggregated, and spread out at the droplet surface, preparing to encapsulate the electrochemically active material located within the droplet's center. Aggregation and spreading occur simultaneously as the droplet shrinks due to evaporation during drying. The disordered carbon layers then concentrate completely around the internal cargo of the electrochemically active material, forming an initial spherical structure. As the droplet continues to shrink, curvature is introduced, followed by significant wrinkles, bends, and twisted edges. Ultimately, the lamellae are isotropically compressed by capillary forces, becoming fully wrinkled, transforming into a pleated sphere with numerous wrinkles, bends, and twists that do not relax over time. This structural transformation of the carbon-based particles into an envelope surrounding the core material is important for particle integrity, as any relaxation of the disordered carbon envelope will lead to reintroduction of the internal particle cargo into the electrolyte, exposure, and the formation of a fractured and unstable SEI.

[0063] The preparation of the mixture to be atomized is also important, as it aims to generate heterogeneous droplets comprising solid particles suspended in the liquid forming the droplets. The liquid forming the droplets should be one that maintains the integrity of the particles within it, allowing the particles to be isotropically compressed and plastically deformed to form approximately spherical particles, much like folded paper balls. Additionally, it is important to maintain the droplets in the furnace carrier gas for a sustained period (i.e., until complete evaporation is achieved) to complete the folded spherical encapsulation and internal cargo encapsulation. In this way, the aerosol-assisted evaporative capillary compression process forms particles resembling hollow spheres, which are resistant to aggregation, exhibit excellent processability, and can be used as conductive additives or alternatively encapsulate electrochemically active internal cargo for use as electrodes in electrochemical battery cells.

[0064] Once the droplets have evaporated completely, the dried powder is collected. After collection, the dry powder can be heat-treated in an inert atmosphere such as argon to carbonize any remaining surfactant or dispersant. The resulting dried powder can then be sorted by sieving or filtration to achieve the particle size distribution desired for a given application.

[0065] One embodiment of the material of the present invention includes an active electrode material comprising a quasi-metallic and / or metal oxide active material. The active material may include an active anode material. The active material may additionally include a carbon-based material additive. The carbon-based material additive may include a low-defect disordered layer carbon-based material. In some embodiments, the low-defect disordered layer carbon comprises graphene sheets, which are part of a structure comprising a continuous network for a composite electrode material comprising: (a) a mechanical support for the active electrode material; and (b) a conductive pathway for the active electrode material. The mechanical support assists the conductive pathway by providing and maintaining contact between the active electrode material and the carbon-based material additive during electrochemical cell cycling.

[0066] One embodiment of the material of the present invention includes an electrode comprising a quasi-metallic or metal oxide active material. The electrode may alternatively comprise a carbon-based material. The electrode may comprise both a quasi-metallic or metal oxide material and a carbon-based material. The carbon-based material may comprise low-defect disordered carbon layers, which may be present at wrinkled lamellae comprising one or more sheets of graphene. The electrode may comprise: composite particles; electrochemically active particles; conductive particles; electrically insulating particles; chemically active particles; intercalation / deintercalation particles; carbon-based particles; quasi-metallic or metal oxide particles; alloy particles; wrinkled particles; aggregated particles; composite particles; and combinations thereof. In some embodiments, the diameter of the composite particles may be ≤1 μm on average. In some embodiments, the diameter of the composite particles may range from about 1 μm to about 15 μm. The electrode may comprise partially overlapping disordered carbon sheets or lamellae to simulate a larger monolithic structure. In some embodiments, the lamellae have more than one or more layers of graphene-based material. In some embodiments, the sheet size of the lamellae may be <15 μm on average. In some embodiments, the sheet size of the lamellae may be <1 μm on average. In some embodiments, the randomized carbon-based material lamellae may have a low thickness. In some embodiments, the low thickness of the randomized carbon-based material lamellae may be ≤1 μm on average. In some embodiments, the low thickness of the randomized carbon-based material lamellae may be ≤100 nm on average. In some embodiments, the randomized carbon-based material lamellae are wound, woven / interwoven through, or bonded to at least some particles of the electrode material in the electrode. The electrode may further comprise one or more adhesives, one or more non-crosslinked polymers, one or more crosslinked polymers, and combinations thereof. The electrode may be an anode, a cathode, or both.

[0067] Low-defect disordered carbon materials are advantageous for electrode slurry coating techniques. Electrodes may include low-defect disordered carbon materials, optionally binders, and additional electrochemically active materials. Electrodes may include one of the following: (1) only one or more low-defect disordered carbon materials; (2) one or more low-defect disordered carbon materials and other carbon-based material additives, such as carbon black, graphite, graphene oxide, graphene, exfoliated graphite or graphene, graphene oxide, rGO, partially reduced GO, carbon nanotubes (CNTs) such as single-walled, double-walled, or multi-walled CNTs, graphene sheets, nanosheets or nanoparticles, nanosheets or nanoparticles comprising graphene sheets or several graphene sheets, and combinations thereof; (3) one or more low-defect disordered carbon materials and one or more cathode active materials, such as metal oxides, lithium-ionized metal oxides, etc. (3) Metal fluorides, lithium metal fluorides or combinations thereof; sulfur, lithium sulfide, metal fluorides, lithium metal fluorides, lithium metal phosphates and lithium metal silicates, wherein the metal may include transition metals (such as iron, manganese, cobalt, nickel, copper, vanadium, chromium) and / or non-transition metals (such as bismuth) and combinations thereof; lithium-rich positive electrode active material, which may include magnesium, strontium, barium, cadmium, zinc, aluminum, gallium, boron, zirconium, titanium, calcium, selenium, yttrium, niobium, chromium, iron, vanadium, lithium and combinations thereof; (4) one or more low-defect carbon-based materials and one or more anode active materials including anode active components, wherein the anode components include quasi-metallic or metal oxide materials.

[0068] The electrode may comprise a composite material mixture capable of providing 100% anode lithium capacity or may be mixed in a 0-100% mixture with other lithium-active materials such as graphite, graphene oxide, graphene oxide, rGO, and partially reduced GO. If the electrode includes a binder for holding the electrode materials together, the binder may comprise polymeric materials such as polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), CMC / SBR, polyacrylic acid (PAA), lithium polyacrylate (LiPAA), or combinations thereof. The electrode material components are then mixed in a polar solvent such as water or N-methyl-2-pyrrolidone (NMP) at a solids loading ranging from about 20% to about 60% to form an electrode slurry. Mixing is typically achieved using a planetary mixer and high-shear dispersion blades. The electrode slurry is then coated onto a metal substrate (typically copper or aluminum) at an appropriate mass loading to balance the lithium capacity of the anode with that of the selected cathode. Coating can be performed using various equipment, such as doctor blade coaters, comma coaters, gravure coaters, and slot coaters. After coating, the slurry is dried in forced air between room temperature and approximately 120°C. The final electrode processing step, prior to cell assembly, involves pressing the electrodes to reduce internal porosity and cutting them into appropriate geometries. Typical anode pressing densities range from approximately 1.0 g / cc to approximately 1.7 g / cc, depending on the electrode composition and target application. Cathode pressing densities range from approximately 2.7 to approximately 4.7 g / cc.

[0069] One embodiment of the material of the present invention includes an electrochemical cell unit comprising an anode, a cathode, and a non-aqueous electrolyte comprising a lithium salt. The anode comprises a quasi-metallic or metal oxide material. The anode further comprises a low-defect disordered-layer carbon material. The anode may comprise composite particles. The composite particles may further comprise a pleated spherical structure, wherein the pleated structure comprises low-defect disordered-layer carbon material encapsulating a quasi-metallic or metal oxide material in its core. The anode may alternatively comprise an anode material mixture having particles comprising quasi-metallic or metal oxide materials and particles comprising disordered-layer carbon material. The disordered-layer carbon material may comprise low-defect disordered-layer carbon sheets wound and / or bonded to at least some of the primary particles comprising quasi-metallic or metal oxide materials. The cathode may comprise a carbon-based material. In addition to conventional carbon-based materials used in the cathode electrode of an electrochemical cell unit, it is contemplated that the low-defect disordered-layer carbon material of this application may also be used as an additive for the cathode electrode of an electrochemical cell unit.

[0070] The construction of an electrochemical battery cell involves the pairing of a coated anode substrate and a coated cathode substrate, electrically isolated from each other by polymer and / or ceramic electrically insulating membranes. The electrode assembly is hermetically sealed in a housing, which may have various structures, such as, but not limited to, coin cell, pouch cell, or can cell, and contains a non-aqueous ionic conductive electrolyte operatively associated with the anode and cathode. The electrolyte is composed of an inorganic salt dissolved in a non-aqueous solvent, and more preferably an alkali metal salt dissolved in a mixture of a low-viscosity solvent comprising organic esters, ethers, and dialkyl carbonates, and a high-conductivity solvent comprising cyclic carbonates, cyclic esters, and cyclic amides. Non-limiting examples of the electrolyte may include lithium hexafluorophosphate (LiPF6) or lithium bis(fluorosulfonyl)imide (LiFSi) salts in an organic solvent comprising one of: ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), or combinations thereof. Other solvents that can be used in embodiments of the invention include dialkyl carbonates such as tetrahydrofuran (THF), methyl acetate (MA), diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 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. High dielectric constant solvents that may also be useful include cyclic carbonates, cyclic esters, and cyclic amides such as propylene carbonate (PC), butenyl carbonate, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, γ-valerolactone, γ-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP), and combinations thereof. The electrolyte acts as the medium for the migration of lithium ions between the anode and cathode during the electrochemical reactions of the battery cell, particularly during battery cell discharge and recharge. Electrochemical cell units may also have positive and negative terminals and / or contact structures.

[0071] In the above embodiments, the quasi-metallic or metal oxide material is selected from the group consisting of: silicon (Si), germanium (Ge), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), zinc (Zn), aluminum (Al), silver (Ag), gallium (Ga), magnesium (Mg), carbon (C), nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), sulfur (S), and cadmium (Cd); alloys thereof, intermetallic compounds thereof, oxides thereof, or any combination thereof.

[0072] Figures 3 to 5 show SiO₂ encapsulated or coated with carbon materials. x Raman spectra of active material mixtures containing primary particles. Figure 3 shows SiO₂ including amorphous carbon material coated with the active material. xRaman spectra of the active material mixture containing primary particles. Figure 4 shows the Raman spectra of SiO2 encapsulated with rGO. x Figure 5 shows the Raman spectra of an active material mixture comprising SiOx primary particles encapsulated by low-defect disordered carbon layers. Each spectrum varies depending on the layer thickness (wavelength 2700 cm⁻¹). -1 (Size, shape, and position of the surrounding 2D peaks) and disorder (wavelength 1340 cm⁻¹) -1 The size of the surrounding D peak varies.

[0073] Sample preparation for Raman analysis involves taking small aliquots of powder, such as active material powder, composite material powder, or carbon material powder, and placing these powders individually in clean glass vials. The sample powder is then rinsed with methanol. The powder / methanol solution is then briefly vortexed and sonicated for approximately 10 minutes. The suspension is then transferred to a microscope slide using a micropipette. The slide is then allowed to air dry completely before analysis.

[0074] The Raman spectroscopic analysis in this application was performed using confocal Raman spectroscopy on a Bruker Senterra Raman system under the following test conditions: 532 nm laser, 0.02 mW, 50 X objective lens, 90 sec integration time, using a 50 x 1000 μm aperture and a 9-18 cm⁻¹ aperture. -1 Three co-additions of resolution (three Raman spectroscopy sample runs). As a reference point, the D band is inactive in Raman scattering of perfect crystals. Due to a defect-induced double-resonance Raman scattering process involving π-π electronic transitions, the D band becomes Raman active in defective graphite materials. The intensity of the D band relative to the G band increases with the amount of disorder. Intensity I D / I G The ratio can thus be used to characterize graphene materials.

[0075] The D and G bands of amorphous carbon shown in Figure 3 are higher than those of reduced graphene oxide (rGO) in Figure 4 or disordered carbon in Figure 5. Amorphous carbon also exhibits significantly higher I intensity than rGO and disordered carbon. D / I G The ratio (1.25). The suppression intensity of the G band compared to the D band of amorphous carbon reflects the lack of crystallinity within its carbon structure (also known as its graphitic nature). The higher D peak intensity compared to the G peak intensity is due to the large number of defects in the amorphous carbon network. Therefore, compared to more crystalline carbons such as graphene, graphene oxide, and rGO, amorphous carbon spectra exhibit low crystallinity and a much higher degree of disorder within its graphitic network. Furthermore, the intensity of its D peak compared to the G peak of rGO, as well as its I... D / I GThe ratio (almost 2X) is greater than the intensity of the D and G peaks and the I peak of disordered carbon. D / I G The higher ratio indicates that rGO has more defects than the disordered carbon in this application.

[0076] Table 1 below provides details of the Raman spectra in Figures 3 through 5.

[0077] Table 1

[0078]

[0079] Careful examination of these spectra revealed that the D-band broadened and the relative intensities of the bands changed with increasing disorder. For the amorphous carbon-coated sample, the high intensity (6194.8) and broad D-peak indicated a large number of defects. The lower D-peak intensity (6194.8) compared to the G-peak intensity (4908.2) indicated a lack of crystallinity. The D-peak intensities (9115.5) and G-peak intensities (10033.3) of the rGO-encapsulated sample were quite similar. However, it is noteworthy that the D-peak intensity (9115.5) of the rGO sample was significantly higher than that of the disordered carbon sample (2915.3), indicating that the defect density of the rGO sample was significantly higher than that of the disordered carbon sample. Also noteworthy is that the G-bands of the amorphous carbon and rGO samples differed from those of the rGO sample at wavelength 1584 cm⁻¹. -1 Shift to the right to a wavelength of 1589.4 cm -1 and 1597.82cm -1 The G band of the disordered carbon sample is at 1581.32 cm⁻¹. -1 It is located slightly at a wavelength of 1584cm. -1 On the left. Importantly, unlike amorphous carbon and rGO samples, disordered carbon (in this case, the graphene sample) does not exhibit a large positional shift (if any), reflecting its low defect rate; therefore, the disordered carbon sample most closely resembles a near-perfect disordered carbon material. In some embodiments, disordered carbon can have the following Raman spectrum, with the peak intensity of its G band (I... G (Within a range of approximately 1530cm) -1 Up to approximately 1600cm -1 At the wave number, such as approximately 1530cm -1 Up to approximately 1584cm -1 Or approximately 1580cm -1 Up to approximately 1600cm -1 .

[0080] Figure 6A The comparison includes an anode (the anode comprises SiO₂ encapsulated by low-defect disordered carbon layers). xAn exemplary half-cell cell comprising an exemplary composite particle of primary particles, wherein x is approximately 0.6, and an anode comprising SiO2 encapsulated by rGO. x A graph showing the cycle lifetime of a comparative half-cell cell (comparative of primary particles and composite particles). Figure 6B This is a graph comparing the specific capacity, first coulombic efficiency (CE), and percentage capacity retained up to 80% of the capacity of exemplary and comparative half-cell cells.

[0081] Reference Figure 6A and Figure 6B Exemplary and comparative SiO composite particles x The carbon ratio is approximately 80:20. The anode is formed by coating a suspension of the corresponding anode material onto a substrate. The corresponding electrode composition contains an active material: conductive additive: LiPAA binder ratio of 75:5:20. The electrode is stamped and calendered to a compression density of 1.1 g / cc, and is integrated into an electrochemical test cell using a lithium or NMC 523 counter electrode, a polypropylene separator, and a 1.0 M LiPF6EC:DEC (3:7) electrolyte with 20% FEC additive. Figure 6B The table shows that the exemplary half-cell cell containing a low-defect disordered carbon anode material has a first coulombic efficiency that is 3% higher than that of the comparative half-cell cell containing a comparative anode material containing rGO, demonstrating less irreversible lithium loss during formation. Furthermore, the exemplary half-cell cell retains 98% of its capacity when cycled to 80% of its design capacity, while the comparative half-cell cell retains only 57% of its capacity when cycled to 80% of its design capacity. Thus, the exemplary half-cell cell exhibits approximately 42% more capacity retention compared to the comparative half-cell cell, demonstrating the positive impact of the low-defect disordered carbon material on cycle stability.

[0082] Figure 7This is a graph illustrating the sequence of rest periods, pulse profiles, and discharge segments during the standardized Hybrid Pulse Power Characterization (HPPC) technique developed by the US Council of Automotive Research. The purpose of this test is to determine the power capacity of discharge pulses (5C rate) and charge pulses (3.75C) at every 10% capacity increment relative to the maximum operating capacity of a given battery cell. Between each pair of discharge and regeneration (charge) pulses, the device is discharged to the next 10% increment based on the operating capacity using a C / 3 rate. The HPPC test begins with the device using the manufacturer-recommended procedure up to Vmax, followed by a default rest period (typically 1 hour). The test is typically programmed to remove 10% of the operating capacity in each test segment, including the operating capacity removed by the pulse profile itself. The HPPC profile is executed immediately, followed by discharge to the next 10% increment of the rated capacity at C / 3 and a default rest. This sequence is repeated until a final profile is obtained that removes 90% or nearly 90% of the operating capacity. The test was terminated when the device discharged to Vmin0 at C / 3 rate and finally defaulted to a stop.

[0083] Figures 8 to 10 These are graphs showing the voltage polarization, area ratio impedance (ASI) curves, and high-rate capability comparisons of exemplary and comparative full-cell cells, respectively. Figure 9 and Figure 10 ASI in the middle is based on Figure 7 The ASI measurement is obtained using HPPC technology. The ASI measurement is a complex combination of internal battery resistances, generated by physical processes occurring at different lengths and time scales. Therefore, the measured ASI value is a function of multiple factors, including: state of charge (SOC), pulse length, current density, C-rate, particle size, lithium diffusion length, and specific dielectric. This combination of factors is measured by the voltage response (polarization) to a charging or discharging current pulse, as defined by the following equation:

[0084]

[0085] Where V = the measured voltage of the battery cell,

[0086] I = the applied current,

[0087] t0 = the time immediately preceding the application of the pulsed current, and

[0088] t1 = the time immediately preceding the termination of the applied pulse current.

[0089] Construct exemplary and comparative electrochemical full cell units while keeping all components and feedstocks constant, except for a comparative cell unit containing an exemplary anode material containing disordered carbon and a comparative cell unit containing a comparative anode material containing rGO. Figure 9 It is displayed for Figure 8 The graph of the HPPC test results indicates that, at the same SOC, the ASI of the exemplary battery cell is lower than that of the comparative battery cell at all SOCs. Figure 9 ASI is used in various SoCs from Figure 8 The voltage response curve was calculated. This effect is attributed to the reduced impedance contribution of the disordered carbon additive to the overall cell polarization, due to its lower defect rate within the disordered carbon lattice. This trend continued as the test cells were cycled to 100% discharge.

[0090] Figure 10 The diagram shows that after 30 full-cell cycles between 4.2V and 2.8V using a 0.5C constant current constant voltage (CCCV) charging protocol and a 2C discharging protocol, the increase in ASI of the comparative cell is greater than that of the exemplary cell. For Figure 9 ASI was used after 30 electrochemical test cycles, derived from... Figure 8 The voltage response curve was calculated. This increase in ASI indicates that, compared to the exemplary battery cell, the comparative battery cell exhibits lower cycle stability and greater resistance accumulation during repeated cycles. Furthermore, the cycle stability of the comparative battery cell decreases and its resistance increases with increasing cycle number.

[0091] Figure 11 This is a graph illustrating the cycle life of exemplary and comparative full-cell cells according to various embodiments of the present disclosure. (Refer to...) Figure 11 An exemplary and comparative full-cell unit comprises 2032 coin-shaped cell units, each comprising: an NMC cathode; a polypropylene separator; an electrolyte comprising 1.0 M LiPF6 (EC:DEC:DMC (1:1:1) and 20% FEC); and an anode comprising 60% SiO2. x The composition includes 20% graphite, 5% conductive additives, and 15% PAA binder. The exemplary anode has SiO wound in disordered carbon, while the comparative cell's anode is coated with amorphous carbon deposited via CVD.

[0092] like Figure 11 As shown, the exemplary battery cell exhibits better initial capacity than the comparative battery cell at a 2C discharge rate. The exemplary battery cell also demonstrates improved cycle stability compared to the comparative battery cell.

[0093] Figure 12A It includes SiO x SiO₂ with a GO weight ratio of 80:20 x Scanning electron microscopy (SEM) images of primary particles and aggregates of wrinkled rGO sheets. Visible are SiO₂ particles randomly distributed around the wrinkled rGO sheets (region 2). x Small grape-like clusters of particles (Region 1). The composite particles shown are larger than 5 μm (as derived from image micrometer markers) and exhibit morphological variations that can further adversely affect the electrochemical properties of powders containing these particles. Various SiOx clusters encapsulated by wrinkles in rGO sheets are shown in the SEM images. Particle morphologies, which are particularly important for the resulting electrochemical properties of the powder, are also shown, specifically those occurring within the wrinkled rGO sheets and SiOx. x There are many void spaces between the primary particles, indicating poor contact (i.e., lack of close contact) (region 3 is an example). Furthermore, SEM images show that the composite particles also exhibit an excess of SiO₂. x Clustered, wrinkled rGO sheets (region 4 is an example). This variation in composite particle morphology is relative to the average SiO2 used. x The primary particles select for a large transverse rGO sheet size, thereby allowing excessive rGO to fold itself, resulting in SiO₂. x Composite particles with excessive or insufficient rGO covering of primary particles. As previously disclosed, SiOx primary particles can be submicron (less than 1 μm) or have an average particle size ranging from about 1 μm to about 15 μm. Therefore, compared to primary particles encapsulated with low-defect disordered carbon layers of this application, in addition to the higher defect density of said rGO (i.e., as determined by Raman spectroscopy), D / I G In addition to the ratio > 0.8, these morphological changes, which result in a lack of close and distributed contact with SiOx particles, further reduce the effectiveness of rGO in providing conductivity to SiOx primary particles.

[0094] Figure 12B It includes 80:20 SiO x : SiO2 encapsulated by low-defect disordered carbon sheets with a carbon weight percentage of % xSEM images of exemplary composite particles of primary particles. Visible are clusters of Si alloy primary particles encapsulated and in close contact with low-defect carbon sheets forming discrete, near-spherical composite particles (region 1 is an example of one of these particles). The particle size of the composite particles shown is less than 5 μm (as derived from micrometer markers in the image). These composite particles have a defined structural fingerprint exhibiting an Ig greater than zero and less than or equal to about 0.8, as determined by Raman spectroscopy performed at a 532 nm laser excitation wavelength. D / I G The ratio and I from approximately 0.5 to approximately 2.0 2D / I G Ratio, where I D / I G A ratio ≤0.8 indicates low defects, and approximately 0.5 or greater indicates low defects. 2D / I G The ratio indicates a low plate count of approximately 10 plates or fewer. Additionally, 2D bands exhibiting a single-peak profile with peak symmetry and an intensity higher than its G band indicate disordered layering and a lack of AB stacking between plates. The low plate count and lack of AB stacking between plates in low-defect disordered carbon materials produce a moss-like mosaic structure on the surface of these composite particles (region 2 is an example). The low plate count and lack of AB stacking order give the composite particles flexibility, making them suitable for use in SiO₂. x A tight contact is generated and maintained between the primary particles and the encapsulated low-defect disordered carbon material. This tight contact between the primary particles and carbon can be observed in SEM images. Notably, the low-defect disordered carbon material is unique in that it lacks the excessive folding or wrinkling present in rGO particles.

[0095] Various electrochemical tests were conducted, all demonstrating that low-defect disordered carbon exhibits superior performance compared to reduced graphene oxide. The winding, mixing, coating, or encapsulation of silicon alloy active materials with low-defect disordered carbon additives provides a flexible and conductive matrix, ensuring that individual particles maintain electrical contact after significant volume changes associated with lithiation / delithiation of the active material. The electrochemical performance of silicon alloy anode materials in terms of cycle stability and high-rate discharge can be maximized by optimizing the defect characteristics of the carbon additives and appropriately incorporating them into the surface of the silicon alloy active particles. Specifically, low defect density is necessary to enhance the intrinsic conductivity of the carbon material and is also important for SiO₂. x The close and uniform contact of the active materials ensures that this enhanced conductivity participates in the charge transfer process during lithium insertion and extraction.

[0096] Thermal disproportionation composite particles

[0097] Silicon is a promising and attractive electrode material for high-capacity lithium-ion battery cells due to its good theoretical capacity and availability. However, integrating silicon electrode materials into efficient and high-performance battery electrodes has proven challenging when using battery electrodes made from these silicon electrode materials, due to the significant irreversible capacity loss during the first cycle and subsequent rapid capacity decay during electrochemical cell cycling. In fact, studies have shown that: 1) it is difficult to form a (solid electrolyte interface) SEI film on the surface of the Si electrode during the first cycle; 2) lithium-ion (Li... + The insertion and deintercalation of Si leads to a large volume expansion that may include electrode conductivity, and the insertion and deintercalation kinetics of Si become sluggish; and 3) the internal resistance of the electrochemical cell varies with the lithiation state after cycling. This can be addressed by providing methods to reduce and / or limit irreversible Li-Si insertion and deintercalation. + The novel particle structure and its preparation method of this application solve these problems: particle structure and electrode powder material that improves reaction efficiency, reduces battery electrode resistance, and increases the first-cycle lithiation / delithiation efficiency of electrochemical battery cells.

[0098] Currently, much research is actively underway on silicon-based composite materials. For example, researchers are investigating the combination of silicon-based materials with various other materials. Some studies focus on conductive additives in silicon-based electrode powder materials. Some studies investigate coated silicon-based particles. Other studies involve electrode additive materials. Still others are directly dedicated to electrolyte additives. Many of these studies have indeed identified solutions that can improve capacity levels, broadly improve charge / discharge cycle behavior, or extend battery life. However, a remaining problem for silicon-based materials is the irreversible formation of electrochemically inert amorphous lithium-ionized silicon oxide (Li₂O₃) during the initial charge / discharge cycle. x SiO y This leads to low efficiency in the first charge / discharge cycle. The inventors of this application have discovered that by modifying the starting SiO material through a thermal disproportionation reaction, and then using this modified SiO to form particles comprising the modified SiO and graphene for the battery electrodes, irreversible Li₂O₂ formation during the initial electrochemical cell charge / discharge cycle can be achieved. + The reaction is greatly reduced. Irreversible Li + This reduction in reaction results in a significant improvement in the first cycle charge / discharge efficiency of the electrochemical battery cell.

[0099] Silica (SiO) powder is commercially available for a variety of applications, including powders for battery electrodes. SiO is an amorphous material comprising the +2 oxidation state, known by experimental and theoretical calculations to be inherently unstable and prone to disproportionation, irreversibly forming silicon dioxide (SiO2) and silicon (Si). The disproportionation reaction of SiO has been studied for decades, and both chemical and thermal methods have been evaluated as specifically designed to induce SiO disproportionation. However, disproportionated SiO has not yet been commercially available for any application, and its use in electrode materials for battery applications is minimal.

[0100] The purpose of SiO thermal disproportionation is twofold: (1) to provide electrochemically inert amorphous SiO2 domains to partially isolate oxygen atoms from the SiO matrix, thereby mitigating undesirable irreversible reactions with lithium ions during initial battery charging (lithiation) and discharging (delithiation); and (2) to provide size-controlled electrochemically active crystalline Si domains to provide increased battery capacity and / or battery energy density.

[0101] Lithium-ion batteries containing SiO as the anode active material may suffer from low coulombic efficiency and high irreversibility during the first cycle due to the irreversible consumption of lithium ions during the initial charging period. Specifically, it is believed that during the initial charging period, Li... + Ions may undergo irreversible reactions with SiO to form electrochemically inert Li-silicates (e.g., Li2Si2O5, Li6Si2O7 and Li4SiO4) and Li2O.

[0102] According to various embodiments of this disclosure, thermally disproportionated SiO2 can be utilized. x As an anode active material, it can improve the coulombic efficiency of the first cycle. Specifically, the thermal disproportionation (or disproportionation) reaction of SiO can be illustrated by the following equation 1:

[0103] Formula 1

[0104] 2SiO+ heated at 600℃-1400℃ → Si + SiO2

[0105] According to various embodiments of this disclosure, the composite particles of the electrode material may each comprise primary particles, said primary particles including a conductive silicon composite material coated with a low-defect disordered layer of carbon. As discussed in detail below, the composite particles can be made by... x Primary particles are formed by heat treatment, where x is in the range of about 0.7 to about 1.2, such as about 0.9 to about 1.1, to make SiO x Disproportionation forms a conductive silicon composite material. A disordered carbon coating can be applied before or after heat treatment.

[0106] Figure 13A and Figure 13B These are scanning electron microscope (SEM) images of multiple composite particles 100 of this application. The composite particles 100 are shown as at least partially comprising a heterogeneous composite particle structure, said heterogeneous composite particle structure comprising an electrochemically active component, an electrochemically inert component, and a conductive component. The electrochemically active component further comprises one or both of amorphous SiO and Si nanocrystals. The electrochemically inert component comprises amorphous SiO2. The conductive component comprises graphene.

[0107] Figure 13B Composite particles 100 in proportion Figure 13A A higher magnification reveals the composite particles 100. Notably, the particle morphology includes a mixture of surface textures, comprising mottled and smooth regions. The mottled regions comprise porous graphene 112, and the smooth regions comprise amorphous material 114, which includes amorphous SiO, amorphous carbon, or both. As used herein, the term "morphology" is defined as the structure and one or more features of a surface. Specifically, "morphology" refers to the structure and features of the outer surface of particles, nanoparticles, or macroparticles of an electrode material. Figure 13B Partially entangled dpp-SiO porous graphene 112 is shown, in which amorphous material 114 is partially visible. It should be understood that porous graphene 112 can completely entangle amorphous material 114. Both types of heterogeneous composite particles can be used alone or in combination to fabricate battery electrodes.

[0108] Figures 13C and 13D are from Figure 13B Magnified images of two composite particles extracted from SEM images depicted in the figure. In these magnified images, the space, pores, and irregularities of the porous graphene 12 are more clearly visible. The space, pores, and irregularities shown facilitate particle-to-particle mixing and electrical interconnection, and also impart a surface microporosity to the composite particles 100. The microporosity provided to the particle surface is in addition to the mesoporosity of any agglomerated particles in the electrode material powder and the macroporosity of the electrode itself when manufactured using such particles. Furthermore, in addition to the particle surface microporosity, disproportionated SiO also contributes to the microporosity. The disproportionation reaction induced in SiO during heat treatment leads to the local development of unsaturated bonds within the silicon oxide. When a structural transformation from SiO to Si and SiO2 occurs, unsaturated bonds emerge, introducing disorder and defects that trigger porosity development in dpp-SiO. The combination of microporosity on the surface of heterogeneous composite particles and inside disproportionated SiO, mesoporosity of aggregated particles, and macroporosity of the electrode itself provides the following electrode performance advantages: i) enhanced electrolyte absorption capacity of the electrode; ii) increased wettability of the electrolyte at the electrode-electrolyte interface; iii) improved ion diffusion to the particle surface; and iv) promoted interfacial charge transfer. The end result is a reduction in electrode charge transfer resistance.

[0109] Further concerning graphene, in addition to providing microporosity to heterocomposite particles, graphene's excellent electrical conductivity endows such particles with superior conductivity, thereby significantly reducing the internal resistance of battery electrodes. The resistance of a battery electrode is essentially composed of three elements: 1) internal electrode resistance, 2) solid electrolyte interface (SEI) resistance, and 3) charge transfer resistance. The influence of heterocomposite particle structure on charge transfer resistance has been disclosed above. SEI resistance is a passivation film formed on the electrode surface due to electrolyte decomposition. Once formed, the SEI film should protect the electrolyte solution within the electrochemical battery cell from further decomposition and should also advantageously affect the safety, power capacity, shelf life, cycle life, and performance of the electrochemical battery cell. While the SEI film may undesirably limit the capacity and dynamic response of the electrochemical battery cell by restricting ion transport, and while the resistance on the SEI film can also limit the electrode current, SEI resistance is not the subject of this application. Nevertheless, it is important to note that for optimal electrochemical cell performance, the SEI film should have high lithium-ion permeability to minimize electrode concentration polarization. It should also function as a resistor to prevent further SEI film thickening, as electrode concentration polarization and SEI film thickening are associated with internal resistance, self-discharge, and low faradaic efficiency in electrochemical cells. High-performance electrochemical cells, in addition to including an SEI film exhibiting high ionic conductivity to reduce overvoltage, should also include a uniform chemical composition and morphology to ensure uniform current distribution.

[0110] To reiterate the importance of graphene and internal electrode resistance, specifically, it is crucial to use graphene as a component of the particle structure rather than as an electrode material or a conductive additive to the electrode. It is well known that silicon-based materials have low intrinsic conductivity (10⁻⁶ Ω·cm). -5 -10 -3 This (S / m) can negatively impact the internal electrode resistance. Carbon-based materials typically have a conductivity greater than 10. 3The S / m ratio indicates that incorporating carbon-based materials into silicon battery electrode materials can advantageously influence the internal electrode resistance. However, due to the superior conductivity of graphene compared to carbon-based materials, its impact on internal electrode resistance is even greater. Graphene's superior conductivity compared to carbon-based materials is attributed to its being a zero-overlapping half-metal. Graphene includes both holes and electrons as charge carriers, thus its conductivity surpasses that of all other conductive materials, even other carbon materials. This is because, in graphene, each atom is bonded to three other carbon atoms in its two-dimensional plane, leaving one electron free for electron conduction in the three-dimensional plane. These highly mobile electrons, i.e., pi (π) electrons, are located above and below the graphene sheet. These pi orbitals overlap and contribute to strengthening the carbon-carbon bonds in graphene. Fundamentally, the electronic properties of graphene depend on the bonding and anti-bonding of these pi orbitals, i.e., the valence band and conduction band. Therefore, graphene, as part of the particle structure, contributes not only to the conductivity of individual particles but also to the overall conductivity of the battery electrode. Therefore, graphene and dpp-SiO provide microporosity for heterocomposite particles, thereby reducing electrode charge transfer resistance, and provide excellent conductivity by directly incorporating graphene into the structure of heterocomposite particles, resulting in increased particle conductivity while reducing internal electrode resistance.

[0111] Figure 14A and Figure 14B These are schematic cross-sectional views of thermally disproportionated composite electrode material particles 100 according to various embodiments of the present disclosure. (Refer to...) Figure 14A and Figure 14B The composite particle 100 may contain primary particles 102, each coated with a sleeve 110. The sleeve 110 may completely encapsulate the primary particles 102, such as... Figure 14A As shown, it may be possible to partially encapsulate the primary particle 102, such as Figure 14B As shown.

[0112] Enclosure 110 may contain graphene-based materials, such as low-defect disordered carbon. In some embodiments, the graphene-based material may contain graphene, graphene oxide, partially reduced graphene oxide, or combinations thereof. The graphene-based material may further include powders, particles, monolayers, multilayers, sheets, lamellae, ribbons, quantum dots, tubes, fullerenes (hollow graphite spheres), or combinations thereof. Enclosure 110 may also include other materials, such as lithium-containing substances (e.g., LiF), alkali metal substances, polymer coating substances, amorphous carbon, and / or other conductive additives or reagents.

[0113] For example, conductive additives or reagents may include carbon black, KETJENBLACK, Super-P carbon black, low-defect disordered carbon, acetylene black, channel black, furnace black, lampblack, thermal cracking black, graphite, natural graphite, synthetic graphite, graphite oxide, partially reduced graphite, flake graphite, exfoliated graphite, lamellar graphite, or combinations thereof. The conductive agent may also include one of the following: conductive fibers, carbon fibers, metal fibers, carbon nanotubes (CNTs), single-walled CNTs, double-walled CNTs, multi-walled CNTs, metal powder, fluorocarbon powder, aluminum powder, nickel powder; nickel flakes, conductive whiskers, zinc oxide whiskers, potassium titanate whiskers, conductive metal oxides, titanium oxide, conductive organic compounds, conductive polystyrene derivatives, or combinations thereof. The binder may include sodium carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), lithium polyacrylate (Li-PAA), polyacrylonitrile (PAN), polyimide (PI), sodium alginate (SA), polymeric β-cyclodextrin (β-CDp), or combinations thereof.

[0114] In various embodiments, primary particles 102 may comprise from about 70% to about 98% by weight of the total weight of composite particles 100, such as from about 80% to about 97% by weight. Encapsulation 110 may comprise from about 2% to about 30% by weight of the total weight of composite particles 100, such as from about 3% to about 20% by weight.

[0115] Primary particle 102 may include a silicon composite material comprising an active region 104 and a passive region 108 disposed within an amorphous matrix 106. Prior to the first charging reaction (e.g., prior to any lithium-ion insertion in the electrochemical cell), the active region 104 may comprise crystalline Si domains (zero-valent Si). The inert region 108 may comprise regions that do not react with Li. + Materials with ion interactions, such as SiO2. Matrix 106 may contain amorphous SiO.

[0116] The oxygen atoms released during the formation of crystalline Si in the active region 104 can be isolated in the passive region 108. Therefore, the amount of oxygen available for irreversible reactions with lithium ions (e.g., lithiation) during the initial charging reaction may be reduced. Consequently, the primary particles 102 can provide more oxygen than those comprising non-disproportionated SiO. x The higher first-cycle coulomb efficiency of primary particles can also lead to higher cell-level energy density.

[0117] During the initial charging reaction and / or subsequent charging reactions, the composition of the primary particles 102 may be altered due to lithiation and / or other reactions. For example, Si and SiO can be lithlated to form Li. x Si is an active material. In addition, some SiO may form inert materials, such as lithium silicate and Li2O.

[0118] During discharge, Li can be... x Si materials undergo delithiation to form crystalline or amorphous Si. LixSi materials may also contain amorphous Si particles generated during the electrochemical delithiation process. However, inert materials such as SiO2, lithium silicate, and / or Li2O can remain in the primary particles 102 without reacting.

[0119] Due to the accumulation of SiO2 on the surface of disproportionated Si material particles, conventional thermal disproportionation of SiO2... x The material may exhibit higher resistivity. Furthermore, lithium dendrites may form on such particles, which could also degrade electrochemical performance. For example, electrically insulating SiO2 can increase resistivity. Additionally, particle expansion and contraction during Li ion insertion and extraction can lead to particle fracture, potentially causing the resulting fragmented particles to be electrically disconnected. Therefore, when used as an anode in lithium-ion batteries, conventional disproportionated SiO2... x The materials may exhibit short electrochemical cycle life and / or low reversible capacity. These detrimental characteristics may hinder the successful application of such materials in lithium-ion batteries.

[0120] However, the inventors have discovered that the disordered carbon in the envelope 110 reduces the resistivity of the primary particles 102 and also improves the cycle life and first coulombic efficiency of the lithium-ion battery containing an anode including composite particles 100.

[0121] Specifically, the disordered carbon of the envelope 110 can provide a flexible conductive network that is resilient to the expansion-contraction behavior of the primary particles 102 (e.g., those containing crystalline Si and / or SiO) during electrochemical cycling, leading to an increase in electrochemical cycle lifetime. Therefore, the successful application of carbon materials, such as low-defect disordered carbon, to the surface of the primary particles 102 can overcome the limitations previously considered to be SiO. x The inherent harmful characteristics of disproportionation can be mitigated, and this disproportionated silicon oxide material can be integrated into materials used in lithium-ion battery applications.

[0122] In some embodiments, primary particles 102 may optionally be metallized (e.g., metal-doped) to include additional metals and / or metal compounds (e.g., dopants) and / or precursors to further increase conductivity, energy density, and / or electrical performance. For example, irreversible Li-ion consumption may additionally and / or alternatively be controlled by: metallizing (e.g., pre-doping) primary particles 102 with Li-ions, adding oxygen-chelating metals to primary particles 102, adding additional supplemental lithium sources to the electrolyte, and / or synthesizing via a bottom-up synthesis process comprising a lithium-ion-containing electrolyte. x SiO y Primary particles 102 of crystalline Si domains in the matrix.

[0123] For example, Li and / or Mg ions can be added to primary particles 102 to form a Li-containing... y SiO x Phase (where M is Li) and / or Mg y SiO x M-SiO phase (where M is Mg) x Particles. In some embodiments, Li and / or Mg precursors may be added to primary particles 102, and the primary particles may then be heat-treated to generate a metal silicate phase. In other embodiments, metals such as Mg, B, Ti, Fe, Al, Cu, etc., may be added to primary particles 102 to isolate reactive oxygen species released during initial charging by forming metal oxides. In some embodiments, primary particles 102 may be synthesized using synthetic techniques, such as sol-gel synthesis, to generate Li within primary particles 102. y SiO x Buffer matrix. In some embodiments, elements such as B, Li, and N may be added to the primary particles 102 to increase electrical conductivity.

[0124] method

[0125] Figure 15A It is formed based on the various embodiments of this disclosure. Figure 14A and Figure 14B A block diagram of the method for composite particles. (Refer to...) Figure 15A In step 10, the method may include heating SiO2. x Primary particles, wherein x ranges from about 0.9 to about 1.6, such as from about 0.9 to about 1.1, are used to thermally disproportionate the primary particles and form a silicon composite.

[0126] For example, the primary particles can be heated in an inert atmosphere (e.g., argon) at a temperature range of about 600°C to about 1400°C (e.g., about 950°C to about 1200°C or about 1000°C to about 1150°C). Heating can be carried out for a period of about 30 minutes to about 4 hours (e.g., about 1 hour to about 3.5 hours). In some embodiments, the average diameter of the primary particles can range from about 0.5 μm to about 15 μm.

[0127] A heat treatment process initiates a thermal SiO disproportionation reaction, thereby forming disproportionated SiO within an amorphous electrochemically active SiO matrix. The disproportionated SiO comprises one or more electrochemically active Si domains and one or more electrochemically inert SiO2 domains. Depending on the desired Si crystallite size, size distribution, and / or quantity, and the particle size of the bulk silicon-based powder, the heat treatment is performed in a furnace using an inert atmosphere at a temperature range greater than 550°C to less than 1400°C.

[0128] In step 12, the resulting disproportionated primary particles can then be suspended in water to produce a homogeneous suspension. The suspension can then be mixed with an aqueous carbon suspension at a predetermined ratio to produce a homogeneous mixture of primary particles and carbon. The aqueous carbon suspension may contain an organic dispersant and disordered carbon, such as disordered graphene. In some embodiments, the dispersion may be stabilized by mixing and / or ultrasonic treatment until the dispersion is demonstrably homogeneous. In other embodiments, the aqueous carbon may contain graphene, graphene oxide, partially reduced graphene oxide, or combinations thereof. Graphene-based materials may further include powders, particles, monolayers, multilayers, flakes, lamellae, ribbons, quantum dots, tubes, fullerenes (hollow graphene spheres), or combinations thereof.

[0129] In some embodiments, the mixture may contain a primary particle to carbon weight ratio ranging from about 80:20 to about 98:02, such as about 90:10 to about 95:05. In some embodiments, the mixture may contain a carbon to dispersant weight ratio ranging from about 3:1 to about 6:1.

[0130] In step 14, a stable mixture of primary particles and carbon can be processed such that the primary particles are coated with graphene. For example, the mixture can be dried using various methods, such as the spray drying method described above, to evaporate water and produce a powder comprising composite particles, including disproportionated primary particles coated with carbon, such as disordered carbon, or disordered graphene.

[0131] In various embodiments, step 12 may alternatively comprise forming a dry mixture comprising carbon material (e.g., disordered graphene powder) and disproportionated primary particles and excluding liquid solvents. Then, step 14 may alternatively comprise adding an adhesive material to the mixture and then applying a mechanical fusion process. Specifically, the adhesive material may be physically mixed with graphene powder and active material particles such that the primary particles are coated with graphene using the adhesive to form composite particles. Non-limiting adhesive materials may include polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene terephthalate, polyacrylonitrile, polydiallyl dimethyl ammonium chloride, polyacrylic acid, lithium-ionized polyacrylic acid (LiPAA), sodium polystyrene sulfonate, polyvinylpyrrolidone, polyethylene glycol, polyethylene oxide, nylon, carboxymethyl cellulose, polysiloxane, polyarylamide, polyamide, polyimide, polyacrylate, polycarbonate, polyurethane, polyacetylene, etc. Pyrrole, polyphenylene sulfide, poly(3,4-ethylenedioxythiophene), poly(1,3-dioxolane), polyphenylenevinyl chloride, polythiophene, polyaniline, polyfluorene, polypyrene, petroleum coke, coal tar pitch, carbon black, carbon nanotubes, sucrose, silicon dioxide, indium tin oxide, aluminum-doped zinc oxide, lithium hydroxide, lithium acetate, lithium perchlorate, lithium fluoride, lithium nitride, lithium nitrate, lithium hexafluorophosphate, LiTFSI, LiFSI, NASICON, LISICON, LIPON, Li3PO4, Li7P3S 11 Perovskite, garnet, polymeric ionic liquid, or any combination thereof.

[0132] In other embodiments, step 12 may alternatively comprise forming a first mixture by dispersing the disproportionated active material particles in a liquid solvent such as water or ethanol. A polyelectrolyte, such as polydiallyldimethylammonium chloride (PDDA), polyacrylic acid (PAA), or sodium polystyrene sulfonate (PSS), may be added to the solvent before or after the addition of the active material particles to form a first surface charge on the active material particles, thereby stably suspending the active material particles in the solvent. A second mixture may be formed by dispersing a carbon material (e.g., disordered graphene powder) in a solvent such as water or ethanol. A polyelectrolyte with an opposite charge may be added to the solvent before or after the addition of graphene to form a second surface charge on the graphene, thereby stably suspending the graphene in the solvent. The first and second surface charges may be different positive and negative charges.

[0133] Then, step 14 may alternatively include forming a third mixture by combining the first mixture and the second mixture, such that graphene is attracted to the surface of the active material particles due to the charge difference between them, thereby forming composite particles comprising graphene-coated active material particles. The polyelectrolytes on the graphene and the active material particles can neutralize each other, making the composite particles substantially uncharged. Step 14 may further include drying the particles by an evaporation process or the like to produce a powder comprising the composite particles.

[0134] In step 16, the resulting composite particles can be collected and then subjected to a second heat treatment process at approximately 700°C under an inert gas atmosphere to carbonize and volatilize any remaining organic graphene dispersant on the composite particles.

[0135] In step 18, the method may optionally include forming an anode using composite particles, as described above. Step 18 may also optionally include incorporating the anode into a lithium-ion battery.

[0136] In some embodiments, the method may include further modification of the primary particles before or after step 10. For example, dopants and / or ionic precursors may be added to the primary particles, and / or additional thermal treatment steps or chemical reactions may be performed.

[0137] Figure 15B It is formed based on the various embodiments of this disclosure. Figure 14A and Figure 14B A block diagram of alternative methods for composite particles. (See reference...) Figure 15B In step 20, the following can be generated: Figure 15A The mixture disclosed in step 12 differs in that the mixture includes non-disproportionated SiO₂. x Primary particles.

[0138] In step 22, the mixture may be processed to produce composite particles, said composite particles comprising nondisproportionated SiO coated with carbon (e.g., disordered graphene). x Primary particles, such as Figure 15A As described in step 14.

[0139] In step 24, the composite particles can be placed in a furnace (such as a tube furnace) and heated to thermally disproportionate the primary particles. Heating parameters can be as follows: Figure 15A As described in step 10. Therefore, heating can also carbonize and volatilize any organic solvents remaining on the composite particles.

[0140] In step 26, the method may optionally include forming the anode using composite particles, as described above. Step 26 may also optionally include incorporating the anode into a lithium-ion battery.

[0141] In some embodiments, the method may include further modification of the primary particles before or after step 24. For example, dopants and / or ionic precursors may be added to the primary particles, and / or additional thermal treatment steps or chemical reactions may be performed.

[0142] Therefore, the composite particles formed by the method of this disclosure can include thermally disproportionated primary particles. Similarly, embodiments of the primary particles can each include particles capable of inserting and extracting Li. + The active domains of the ions, and the matrix in which the active domains are arranged and contain inert SiO2 domains. The size of the active silicon domains can be matched with the inert SiO2 domains and can occupy about 30 vol% of the particles. The remaining 70 vol% may contain active SiO domains, which react with lithium during initial charging to produce active Si domains and inert Li. x SiO y domain.

[0143] Experimental Examples

[0144] The following examples relate to anodes formed using anodic active materials (e.g., composite particles) from various embodiments of this disclosure and comparative anodic active material composite particles, and are given by way of illustration rather than limitation. In the examples, % is weight percentage, g is grams, and mAh / g is capacity.

[0145] Each anode is formed by: adding 1.0g of anode active material (i.e., SiO2) x Graphene-SiO x The anode paste was rigorously mixed for 60 minutes in a planetary mixer with 0.07 g of conductive agent (Super-P carbon black, graphite, etc.), 0.266 g of lithium polyacrylate (LiPAA) binder, and 3.0 g of water. The resulting anode paste was then coated onto copper foil with a loading of approximately 2.5 mAh / cm². 2 The electrode was dried overnight at 120°C. The electrode was rolled to a porosity of 40%. Lithium metal was used as the counter electrode, with an area of ​​1.6 cm². 2 Circular specimens were stamped and assembled into half-cell units. The electrolyte consisted of 1 M LiPF6 in a mixture of EC:DMC (3:7) and 20% FEC. The cell units were electrochemically “formed” under C / 20, C / 10, and C / 5 charge-discharge cycles. The resulting half-cell units were then characterized under a standard C / 2 charge-discharge protocol until the anode capacity reached 80% of its initial capacity.

[0146] Example: T1

[0147] The silicon dioxide powder (SiO) from the first supplier xSilica powder (x ~ 0.9–1.1) was placed in a horizontal furnace and heated at 1000°C for 3 hours under an inert gas atmosphere to carry out a thermal disproportionation reaction. The heat-treated powder was then dispersed in water at a concentration of 1% and further combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 95:05. The resulting mixture was then treated to produce graphene-SiO₂. x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, an anode was prepared using the powder, and battery cells were constructed and cycled.

[0148] Example: T2

[0149] The silicon dioxide powder (SiO) from the first supplier x Silica powder (x ~ 0.9–1.1) was placed in a horizontal furnace and heated at 1050 °C for 3 hours under an inert gas atmosphere to carry out a thermal disproportionation reaction. The heat-treated powder was then dispersed in water at a concentration of 1% and further combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 95:05. The resulting mixture was then treated to produce graphene-SiO₂. x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, an anode was prepared using the powder, and battery cells were constructed and cycled.

[0150] Example: T3

[0151] The silicon dioxide powder (SiO) from the first supplier x Silica powder (x ~ 0.9–1.1) was placed in a horizontal furnace and heated at 1100°C for 3 hours under an inert gas atmosphere to carry out a thermal disproportionation reaction. The heat-treated powder was then dispersed in water at a concentration of 1% and further combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 95:05. The resulting mixture was then treated to produce graphene-SiO₂. x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, an anode was prepared using the powder, and battery cells were constructed and cycled.

[0152] Example: T3-B

[0153] The silicon dioxide powder (SiO) from the first supplier x1% (x ~ 0.9–1.1) was dispersed in water and combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 95:05. The resulting mixture was then treated to produce graphene-SiO x Composite powder. The composite powder was then heated at 1100°C for 3 hours under an inert gas atmosphere. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, an anode was prepared using the powder, and battery cells were constructed and cycled.

[0154] Example: NoG-1

[0155] Using silica powder (SiO2) from the first supplier x (x~0.9–1.1) An anode electrode was constructed using the above electrode formulation, without containing graphene. An electrochemical cell cell containing an anode was prepared and cycled as described above.

[0156] Example: Compare with 1

[0157] The silicon dioxide powder (SiO) from the first supplier x 1% (x ~ 0.9–1.1) was dispersed in water and combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 95:05. The resulting mixture was then treated to produce graphene-SiO x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere to prevent SiO from decaying. x Disproportionation. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, the powder was used to prepare the anode, and battery cells were constructed and cycled for testing.

[0158] Example: Compare with 2

[0159] The silicon dioxide powder (SiO) from the first supplier x ,x~0.9–1.1) were dispersed in water at a concentration of 1% and combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 90:10. The resulting mixture was then treated to produce graphene-SiO x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere to prevent SiO from decaying. x Disproportionation. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, the powder was used to prepare the anode, and battery cells were constructed and cycled for testing.

[0160] Example: Comparison

[0161] The silicon dioxide powder (SiO) from the first supplier xThe powder (x ~ 0.9–1.1) was placed in a horizontal furnace and heated at 1100°C for 3 hours under an inert gas atmosphere to carry out a thermal disproportionation reaction. The obtained powder was analyzed by X-ray diffraction, scanning electron microscopy, and electrochemical cell cycle testing. The material was not mixed or composited with graphene. As described above, an anode was prepared using the powder, and a cell was constructed and cycle-tested.

[0162] Example: NoG-2

[0163] Using amorphous carbon-coated silica powder (C-SiO2) from the first supplier x An anode electrode was constructed using the electrode formulation described above (x ~ 0.9–1.1). The material was not mixed with or composited with graphene. An electrochemical cell cell containing an anode was prepared and cycled as described above.

[0164] Example: Compare with 3

[0165] Amorphous carbon-coated silica powder (C-SiO2) from the first supplier x ,x~0.9–1.1) were dispersed in water at a concentration of 1% and combined with a 1% concentration of aqueous graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 90:10. The resulting mixture was then treated to produce SiO2 coated with graphene and amorphous carbon. x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere to prevent SiO from decaying. x Disproportionation. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, the powder was used to prepare the anode, and battery cells were constructed and cycled for testing.

[0166] Example: T4

[0167] Amorphous carbon-coated silica powder (C-SiO2) from the first supplier x Silica powder (x ~ 0.9–1.1) was placed in a horizontal furnace and heated at 1050 °C for 3 hours under an inert gas atmosphere to carry out a thermal disproportionation reaction. The heat-treated powder was then dispersed in water at a concentration of 1% and further combined with a 1% concentration of aqueous disordered graphene dispersion. The ratio of silica powder to graphene dispersion was maintained at 95:05. The resulting mixture was then treated to produce graphene-SiO₂. x Composite powder. The composite powder was then heated at 700°C for 1 hour under an inert gas atmosphere. The obtained powder was analyzed by X-ray diffraction and scanning electron microscopy. As described above, an anode was prepared using the powder, and battery cells were constructed and cycled.

[0168] Example: T5

[0169] Example T5 is the same as Example T4, except that the temperature of the horizontal furnace is increased to 1100℃.

[0170] Example: T6

[0171] Example T6 is the same as Example T4, except that Example T6 undergoes thermal disproportionation at 1175°C.

[0172] Example: NoG-3

[0173] Example NoG-3 is the same as Example NoG-1, except that it uses silicon oxide powder (SiO2) from a second supplier. x (x~0.9–1.1) as starting material.

[0174] Example: Comparison-4

[0175] Example Comparison-4 is the same as Example Comparison-2, except that it uses silicon oxide powder (SiO2) from a second supplier. x (x~0.9–1.1) as starting material.

[0176] Example: Comparison -5

[0177] Example Control-5 is the same as Example Control-4, except that 20% by weight of graphene coating is applied to the starting material.

[0178] Examples: T7 and T8

[0179] Examples T7 and T8 are the same as Example Control-5, except that Example T7 disproportionates at 1000℃ and Example T8 disproportionates at 1100℃.

[0180] Example: NoG-4

[0181] Example NoG-4 is the same as Example NoG-2, except that it uses amorphous carbon-coated silicon dioxide powder (SiO2) from a second supplier. x (x~0.9–1.1) as starting material.

[0182] Comparison-6

[0183] Example Comparison-6 is the same as Example Comparison-3, except that it uses amorphous carbon-coated silicon dioxide powder (SiO2) from a second supplier. x (x~0.9–1.1) as starting material.

[0184] Examples T9, T10, and T11

[0185] Examples T9, T10, and T11 are the same as Example Control-6, except that Example T9 undergoes thermal disproportionation at 1100℃, Example T10 undergoes thermal disproportionation at 1120℃, and Example T11 undergoes thermal disproportionation at 1140℃.

[0186] Table 2 below contains the physical and electrochemical properties of the above examples.

[0187] Table 2

[0188]

[0189]

[0190] As can be seen from Group 1 of Table 2, the comparative examples (which contain SiO2 heat-treated at 1100°C) x The material (excluding the graphene coating) exhibited high resistance and correspondingly low lithiation capacity of 38 mAh / g, low delithiation capacity of 12 mAh / g, and a first-cycle coulombic efficiency of only 31.6%. It is believed that the poor performance of Example T6 is likely due to the high-resistivity surface layer (SiO2) formed at the higher reaction temperature, which essentially prevents lithium ions and electrons from passing through the material quickly enough to cause the cell voltage to rise to a safe limit and prevents the material from fully reacting with lithium ions and electrons.

[0191] In contrast, Instance T3 (which contains SiO2 covered with the same heat-treated SiO2) x The graphene-based material maintains sufficient conductivity to achieve a lithiation capacity of 1684 mAh / g, a delithiation capacity of 1282 mAh / g, and a first-cycle coulombic efficiency of 76.1%. Furthermore, it comprises thermally disproportionated SiO₂ coated with amorphous carbon and disordered graphene. x The instance T9 exhibits an unexpectedly high first-cycle coulomb efficiency of 78.7%.

[0192] Therefore, compared with undisproportionated but graphene-free NoG materials, control examples of undisproportionated but graphene-free materials, and comparative examples of disproportionated but graphene-free materials, the exemplary materials provide improved results. The exemplary materials provide a first-cycle lithiation capacity of at least 1450 mAh / g, for example 1850-1930 mAh / g, a first-cycle delithiation capacity of at least 1090 mAh / g, for example 1200-1320 mAh / g, and a first-cycle coulombic efficiency of at least 70%, i.e., 76.0 to 78.9%.

[0193] Also noteworthy is the extremely low first-cycle lithiation / delithiation capacity and first-cycle coulombic efficiency (only 31.6%) of the comparative example, which is achieved with SiO₂ after heat treatment at 1100°C for 3 hours. xTest samples of the powder. Comparing Example 8 (comparison) and Example 1 (NoG-1 test sample with untreated SiOx powder), the data shows that the NoG-1 test sample exhibits a significantly higher first-cycle lithiation / delithiation capacity than the comparison test sample, and the NoG-1 test sample also demonstrates a first-cycle coulombic efficiency approximately twice (63.3%) higher than the comparison test sample. This data indicates that for SiO... x Heat treatment to form dpp-SiO has a significant adverse effect on the first cycle performance, indicating that the Li + Insertion is highly resistant. For Li + The strong resistance to insertion is likely due to the formation of electrochemically inert SiO2 domains within dpp-SiO during heat treatment.

[0194] Regarding group 2 in Table 2, it is worth noting that the data for these samples follow the same results as those for their similarly treated counterparts, i.e., i) to SiO₂ x The addition of graphene improves the first cycle coulombic efficiency, ii) when graphene is part of a heterogeneous composite particle structure, SiO x The heat treatment improved the first cycle coulombic efficiency, and iii) increasing the disproportionation reaction temperature improved the first cycle coulombic efficiency, but reduced the first cycle lithiation / delithiation capacity.

[0195] For Groups 1 and 2 in Table 2, comparing the No-G data with the control data (where the No-G data does not contain graphene, while the control data contains 5% by weight of graphene) and showing that the silicon-based materials in both groups were not heat-treated, the data indicates that the carbon coating improved the first-cycle coulombic efficiency of both the No-G and control powders. This data validates previous findings that carbon-coated silicon-based powders can improve both the first-cycle coulombic efficiency and the first-cycle lithiation / delithiation capacity. However, when the silicon-based material was heat-treated to form dpp-SiO, the data showed that the carbon coating did not contribute to the first-cycle coulombic efficiency. In fact, data from two test cell pairs showed a decrease in coulombic efficiency in electrodes using powders including carbon-coated dpp-SiO cores. Furthermore, the data further indicate that the first-cycle coulombic efficiency increases with increasing heat treatment temperature without significantly adversely affecting the first-cycle lithiation / delithiation capacity.

[0196] In summary, the examples above demonstrate that the heterocomposite particles comprising dpp-SiO and graphene of this application provide a composite silicon-based electrode with reduced irreversible active ion reactions, lower lithium-ion insertion resistance, higher conductivity, and increased first-cycle efficiency without compromising first-cycle lithiation / delithiation. Graphene, as part of the particle structure, increases the electrode's conductivity while providing microporosity to the electrode particle surface, thereby reducing charge transfer resistance. Thermal treatment of SiOx initiates a thermal disproportionation reaction to reduce the reactivity with Li. + The amount of SiO that undergoes irreversible reactions with ions is increased, thereby improving the coulombic efficiency of the first cycle and extending the battery cycle life.

[0197] While the foregoing refers to specific preferred embodiments, it should be understood that the invention is not limited thereto. Those skilled in the art will appreciate that various modifications can be made to the disclosed embodiments, and these modifications are intended to remain within the scope of the invention. All publications, patent applications, and patents cited herein are incorporated herein by reference in their entirety.

Claims

1. An electrode material for a lithium-ion secondary battery, the electrode material comprising composite particles, each composite particle comprising: a primary particle, the primary particle comprising a thermally disproportionated metal-doped silicon oxide; and an envelope disposed on a surface of the primary particle, the envelope comprising turbostratic graphene having a Raman spectrum measured using an incident laser wavelength of 532 nm, the Raman spectrum having: a D band having a peak intensity (I D ) at a wave number between 1330 cm -1 and 1360 cm -1 ; a G band having a peak intensity (I G ) at a wave number between 1580 cm -1 and 1600 cm -1 ; and 2D bands, the peak intensity (I 2D ) at wavenumbers between 2650 cm -1 and 2750 cm -1 , wherein: I D / I G the ratio of the concentration of the compound of formula (I) to the concentration of the compound of formula (II) is in the range of greater than zero to 0.9; and I 2D / I G The ratio of the specific surface area of the particles of the first component to the specific surface area of the particles of the second component is in the range of greater than 1 to 2.

2. The electrode material of claim 1, wherein: the primary particle comprises a crystalline silicon domain disposed in a matrix comprising silicon dioxide.

3. The electrode material of claim 1, wherein: The I D / I G the ratio is in the range of 0.3 to 0.7; and The I 2D / I G The ratio is in the range of greater than 1 to 1.

2.

4. The electrode material of claim 1, wherein: I D at a wavenumber of 1340 cm -1 at a wavenumber of 1340 cm I 2D at 2700 cm -1 of wave number.

5. The electrode material of claim 4, wherein the primary particles comprise SiO x particles, wherein 0.9 < x < 1.1, the SiO x particles thermally disassociate at temperatures ranging from 1050 °C to 1150 °C.

6. The electrode material of claim 1, wherein the primary particle comprises at least 50 weight percent of the total weight of the composite particle.

7. The electrode material of claim 1, wherein: the composite particle has an average particle size in a range of 1.0 pm to 15.0 pm; and the primary particle comprises an average particle size in a range of 50 nm to 10 pm.

8. The electrode material of claim 1, wherein the envelope covers, on average, 10% to 100% of a surface area of the primary particle.

9. An electrode comprising: the electrode material of claim 1; and a binder.

10. The electrode of claim 9, wherein the binder comprises polytetrafluoroethylene, polyvinylidene fluoride, polyethylene tetrafluoroethylene, polyamide and polyimide, polyethylene, carboxymethylcellulose, styrene butadiene rubber, polyacrylic acid, lithium polyacrylate, or a mixture thereof.

11. The electrode of claim 9, further comprising a conductive additive selected from the group consisting of carbon black, carbon nanotubes, conductive polymers, graphite, nickel, aluminum, titanium, stainless steel, and any combination thereof.

12. A lithium secondary battery comprising: an anode, the anode comprising the electrode of claim 9; a cathode; a housing, the housing containing the anode and the cathode; and an electrolyte disposed between the anode and the cathode.

13. The battery of claim 12, wherein the battery has a first cycle coulombic efficiency of at least 78% when cycled between 1.50 - 0.02 V vs. Li / Li + when using a 0.05 C constant current constant voltage charge and discharge protocol.

14. A method of forming an anode material, the method comprising: SiO x particle thermal disproportionation, where x is in the range of 0.9 to 1.1, to form primary particles comprising crystalline Si domains disposed in a matrix comprising SiO2; forming a mixture comprising the primary particle and carbon; and processing the mixture to form composite particles, each composite particle comprising: one of the primary particles; and an envelope disposed on the primary particle and comprising turbostratic graphene having a Raman spectrum measured using an incident laser wavelength of 532 nm, the Raman spectrum having: a D band having a peak intensity (I D ) at a wavenumber between 1330 cm -1 and 1360 cm -1 ; a G band having a peak intensity (I G ) at a wave number between 1580 cm -1 and 1600 cm -1 ; and 2D bands, the peak intensity (I 2D ) at wavenumbers between 2650 cm -1 and 2750 cm -1 , wherein: I D / I G the ratio of the concentration of the compound of formula (I) to the concentration of the compound of formula (II) is in the range of greater than zero to 0.9; and I 2D / I G The ratio of the amounts of the compound of formula (I) to the compound of formula (II) is in the range of greater than 1.0 to 2.

15. The method of claim 14, wherein: The thermal disproportionation comprises heating the SiO x particles; and the processing the mixture comprises spray drying the mixture.

16. The method of claim 14, further comprising carbonizing the composite particles.

17. The method of claim 14, wherein the envelope comprises at least 90 weight percent turbostratic graphene.

18. The method of claim 14, further comprising adding a metal dopant or dopant precursor to the primary particles prior to or after the thermal disproportionation of the particles. x adding a metal dopant or dopant precursor to the primary particles prior to or after the thermal disproportionation of the particles.

19. A method of forming an anode material, the method comprising: forming a mixture comprising SiO x a mixture of particles and carbon, wherein x is in the range of 0.7 to 1.1; processing the mixture into a powder; and thermally disproportionating the powder to form composite particles, each of the composite particles comprising: a primary particle including a crystalline Si domain disposed in a matrix including SiO2; and an envelope disposed on the primary particle and including turbostratic graphene having a Raman spectrum measured using an incident laser wavelength of 532 nm, the Raman spectrum having: a D band having a peak intensity (I D ) at a wave number between 1330 cm -1 and 1360 cm -1 ; a G band having a peak intensity (I G ) at a wave number between 1580 cm -1 and 1600 cm -1 ; and 2D spectral bands, the peak intensity (I) of the 2D spectral bands 2D ) at 2650 cm -1 With 2750 cm -1 At the wavenumbers between, wherein: I D / I G the ratio of the concentrations of the first and second components is in the range of greater than zero to 0.9; and I 2D / I G The ratio of the amounts of the compound of formula (I) to the compound of formula (II) is in the range of greater than 1.0 to 2.

20. The method of claim 19, further comprising carbonizing the composite particle.

21. The method of claim 19, wherein the envelope includes at least 90 wt% turbostratic graphene.

22. The method of claim 19, wherein: the thermal disproportionation includes heating the composite particle in an inert atmosphere at a temperature in a range from 1050 °C to 1150 °C; and the processing the mixture includes spray drying the mixture.

23. The method of claim 19, further comprising adding a metal dopant or dopant precursor to the primary particle before or after the thermal disproportionation of the composite particle.

24. An electrode material for a lithium-ion secondary battery, the electrode material including composite particles, each composite particle including: a primary particle including a thermally disproportionated metalated silicon oxide; and an envelope disposed on a surface of the primary particle, the envelope including turbostratic graphene having a Raman spectrum measured using an incident laser wavelength of 532 nm, the Raman spectrum having: a D band having a peak intensity (I D ) at a wave number between 1330 cm -1 and 1360 cm -1 ; a G band having a peak intensity (I G ) at a wave number between 1580 cm -1 and 1600 cm -1 ; and 2D bands having peak intensities (I 2D ) at wavenumbers between 2650 cm -1 and 2750 cm -1 , wherein: I D / I G the ratio of the concentration of the compound of formula (I) to the concentration of the compound of formula (II) is in the range of greater than zero to 1.1; and I 2D / I G The ratio of the specific surface area of the particles of the first component to the specific surface area of the particles of the second component is in the range of greater than 1 to 2.

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